Merge main and treat what the token scanner does not model as an executable edit

.github/workflows/ci.yml

@@ -364,6 +364,20 @@ jobs:
           target: wasm32-wasi
           helper: "false"
       - run: pnpm build
+      # The sanitized seed compiles the compiler's 700 MB module with one clang
+      # process under AddressSanitizer. It peaks near 14 GB while the Node
+      # process that emitted the module still holds about 6 GB. Together they
+      # exceed the runner's 16 GB of memory, so back them with swap.
+      - name: Enlarge swap for the sanitized seed
+        if: matrix.flavor == 'san'
+        run: |
+          sudo swapoff -a
+          sudo rm -f /mnt/swapfile
+          sudo fallocate -l 24G /mnt/swapfile
+          sudo chmod 600 /mnt/swapfile
+          sudo mkswap /mnt/swapfile
+          sudo swapon /mnt/swapfile
+          free -h
       - name: Prepare bootstrap seed
         run: node scripts/bootstrap-seed.mjs
         env:

.oxlintrc.jsonc

@@ -241,6 +241,7 @@
         "packages/compiler/src/frontend/comptime-node.ts",
         "packages/compiler/src/frontend/ts7/world-check.ts",
         "packages/compiler/src/frontend/ts7/source-parser.test.ts",
+        "packages/compiler/src/frontend/jsx-source.test.ts",
         "packages/compiler/src/frontend/npm-static-rewrite.ts",
         "packages/compiler/src/frontend/npm-static-bundled-cjs.ts",
         "packages/compiler/src/library/semantic-source.ts",

CHANGELOG.md

@@ -6,6 +6,161 @@ All notable changes to scriptc will be documented in this file.
 
 <!-- release:start -->
 
+## 0.4.2
+
+### Highlights
+
+- **Faster builds of large programs:**
+  - scriptc checks with tsc-ts 0.0.7, which answers contextual types and resolved signatures in batches, so lowering asks for them in one request per chunk instead of one per node. A native build of tsc-ts is 7% faster (110.5 → 103.5 s on 8 vCPUs, lowering 12% faster), with an identical executable.
+  - The native compiler is built with profile-guided optimization, so tsc-ts builds 6.9% faster cold and 10.7% faster after an edit.
+  - The native compiler's optimization profile is refreshed, so a native build of tsc-ts is a further 10% faster (124.7 → 111.7 s on 16 vCPUs), with lowering 17% faster.
+  - The class dispatch passes index their receivers by name instead of testing each one, and they reuse their per-function scans while a function's body is unchanged.
+  - Checker replies resolve objects the compiler already holds from their ids without decoding them.
+- **Leaner builds:**
+  - The frontend of an optimized executable's first build runs in a child process, so the native code generator starts after its memory is released. The cold build of tsc-ts peaks at 2.21 GB instead of 3.30 GB.
+  - The compiler collects its heap as lowering and LLVM emission grow it.
+- **WebCrypto:**
+  - The `crypto` global, `node:crypto`'s `webcrypto` and `crypto.subtle` are one object.
+  - `generateKey`, `importKey`, `exportKey`, `encrypt`, `decrypt`, `deriveBits`, `deriveKey`, `wrapKey` and `unwrapKey` cover HMAC, AES-GCM, AES-CBC, AES-CTR, AES-KW, PBKDF2, HKDF and JSON Web Keys.
+  - `crypto.subtle` signs and verifies with ECDSA, RSASSA-PKCS1-v1_5, RSA-PSS and Ed25519.
+  - All of it follows Node 24's argument conversion, algorithm normalization and `DOMException`s. jose's symmetric JWE paths run as in Node.
+- **JSX:** `.tsx`, `.jsx` and JavaScript files with JSX compile under the project's `jsx` options.
+  - `react`, `react-jsx` and `react-jsxdev` lower to the factory calls TypeScript emits, with the same keys, fallbacks and source positions.
+  - `preserve` and `react-native` are refused with a named diagnostic.
+- **Faster worker messages:**
+  - A message is encoded into one block sized to its contents.
+  - A typed record is posted from its fields.
+  - A `'message'` listener with a typed parameter builds it from the message, without a checked-dynamic copy.
+  - Messages between `MessageChannel` ports take 90 ms where they took 250 ms in 0.4.1 (Node: 337 ms), with a peak RSS of 45 MB instead of 115 MB.
+- **Loops over typed arrays vectorize:** a loop to a typed array's length keeps one bounds test for every typed array it indexes.
+  - Index temporaries such as `const j = i * 4` are computed as integers.
+  - Uint8ClampedArray stores convert inline.
+  - Row-major index terms such as `r * cols + j` are tested once before the loop.
+  - Typed-array callback methods call a literal callback directly on an integer counter.
+  - An 896 × 896 matrix-vector product with four accumulators takes 55 ms instead of 396 ms (Node: 275 ms). `Uint8Array.map` is 4.5 times as fast and `Int32Array.some` 7.8 times as fast as in 0.4.1.
+
+### Features
+
+- **Asymmetric keys and signatures in `node:crypto`:**
+  - `generateKeyPair`, `generateKeyPairSync`, `createPrivateKey` and `createPublicKey` handle RSA, EC and Ed25519 keys in PEM, DER and JWK.
+  - `sign`, `verify`, `createSign` and `createVerify` sign and verify with those keys, with Node's output and errors.
+  - Ed25519 verification matches Node on 2,083 test vectors, including small-order and mixed-order keys.
+- **`crypto.createDiffieHellman`, `crypto.getDiffieHellman` and `crypto.createDiffieHellmanGroup`:**
+  - The modp1, modp2 and modp5 to modp18 groups, explicit primes and generators, and generated safe primes are supported, with Node 24's key widths, `verifyError` bits, key range checks and errors.
+  - Secrets of 0, 1 and p − 1 are rejected, and so are peer keys outside the RFC 5114 subgroups.
+  - Primes longer than 8192 bits are refused.
+- **TLS:**
+  - `tls.connect` and `tls.createServer` negotiate `ALPNProtocols`, and both sockets report `alpnProtocol`. `minVersion` and `maxVersion` bound the handshake, and `getProtocol()` reports the version it picked.
+  - `tls.createServer` takes an `SNICallback` that answers a `SecureContext` synchronously or later.
+  - `new tls.TLSSocket(socket, { isServer: true, ... })` and `tls.connect({ socket })` run the handshake on an open socket, such as an HTTP `CONNECT` tunnel.
+  - A client whose peer closes before the handshake completes fails with Node's `ECONNRESET`.
+- **Streams:**
+  - Readable, Writable, Duplex, Transform and PassThrough streams take `objectMode`, `readableObjectMode` and `writableObjectMode`, and an object-mode side carries any value through `push`, `write`, `pipe`, `pipeline`, `for await` and `'data'` listeners.
+  - `_write` and `_transform` receive the encoding argument as Node passes it.
+  - `Cipheriv` and `Decipheriv` are Transforms: they can be piped, used as `pipeline()` stages, read and iterated.
+  - `pipeline()` accepts function stages anywhere among its streams, and an array, a string or a synchronous generator as its source.
+- **Packages compiled from their JavaScript:**
+  - js-yaml and smol-toml compile statically and match Node: ES5 error constructors (`Object.create(Error.prototype)`, `Error.call(this)`, `Error.captureStackTrace`) and classes extending `Date` behave as in Node.
+  - TypeScript's UMD module wrapper compiles as the module body, and tsc's `__importDefault` and `__importStar` helpers around builtin modules compile as plain `require()` calls.
+  - Interfaces, type aliases and enums that only a package's `.d.ts` declares keep their types.
+- **JavaScript sources:**
+  - Error constructors can be read as values, so `err.constructor === TypeError` works.
+  - `workerData` can be destructured.
+  - Unary `+` converts unions of strings, numbers, booleans, `null` and `undefined` as `Number()` does, so `+process.argv[2]` compiles.
+  - These compile and behave as in Node:
+    - chained readline listener registration;
+    - `Number.parseInt` without a radix;
+    - `match` and `search` with a possibly undefined regular expression;
+    - `Buffer.from` over an untyped `ArrayBuffer`, with its byte offset;
+    - Atomics on untyped arrays.
+  - Buffer methods run on Buffers held as untyped values.
+- **`fs`:**
+  - The synchronous functions (`readFileSync`, `writeFileSync`, `statSync`, `readdirSync`, `mkdirSync`, `rmSync`, `openSync` and the others) accept `file:` URLs wherever they accept a path, with Node's conversion errors.
+  - `fs.promises.rm` takes `recursive`, `force`, `maxRetries` and `retryDelay`, and removing a directory without `recursive` throws Node's `ERR_FS_EISDIR`.
+- **`TypedArray.of`** creates a typed array of its arguments, and a dynamic iterable spread into `Array.of`, `push` or `TypedArray.of` is drained through the iterator protocol.
+- **Global `isFinite` converts its argument with ToNumber,** as `isNaN` does. The Math functions and `String.fromCharCode` evaluate every argument before converting any.
+- **`Object.freeze`, `Object.seal` and `Object.preventExtensions` of a function** act on its own properties, and `Object.isFrozen`, `Object.isSealed` and `Object.isExtensible` answer for functions. @noble/hashes' frozen hashers work.
+- **EventEmitters used through both typed and untyped references** share one listener list. An untyped `emit` reaches typed listeners, an untyped `emit('error')` follows Node's contract, and `listenerCount`, `eventNames`, `listeners`, `rawListeners`, `removeAllListeners`, `setMaxListeners` and `getMaxListeners` work on untyped values.
+- **Template literals, `join`, `Array.prototype.toString` and the default `sort()`** call an object's own or inherited `toString`, as `String()` does, instead of printing `[object Object]`.
+- **Classes and generics:**
+  - A generic factory declared to return a constructor type can return one of its local classes, including an anonymous class expression, and `class X extends factory(...)` extends it.
+  - Static methods of a function-local class compile.
+  - Constructor types declared in the program (`new () => unknown`, types that also name static members, construct overloads) hold class values.
+  - Members typed by a conditional type over a literal class type argument (`Field<string, "required">`) resolve.
+  - Object literals under an erased generic member may hold callbacks with optional or defaulted parameters.
+- **Assignment and update targets wrapped in parentheses or non-null assertions** (`(x) = 1`, `h.sums[k]! += 10`) compile.
+- **Untyped values keep what JavaScript code adds:**
+  - Properties that untyped code adds to a typed object literal stay on it.
+  - Named properties written to an array through an `unknown` view stay on the array, and `for...in` visits them after the indices.
+  - An `unknown` value asserted to a structural type with methods keeps its class's methods.
+  - The type inferred from an empty object literal holds any non-nullish value, as TypeScript's `{}` does.
+- **A WebAssembly module the build finds but does not translate** rejects with a `CompileError` that names the reason, for example a proposal outside the translated feature set.
+- **SC6101 names the functions that likely run often and use untyped values:**
+  - It shows up to five, most likely hot first, with why their values are untyped: an `any`, an untyped `JSON.parse` result or an untyped JavaScript file.
+  - `scriptc coverage --fail-on=dynamic` fails on it, and `--no-dynamic-tier-warning` leaves it out.
+
+### Performance
+
+- **Regular expressions skip start positions that their leading character sets rule out,** testing 16 positions at once. Searching 50 MB of text for nine case-insensitive alternations takes 0.83 s instead of 3.88 s (Node: 4.38 s).
+- **Loop counters stay integers in more loops:**
+  - Counters that step beside a counted loop's counter (`for (let i = 0, p = 0; i < n; i++, p += 4)`) stay integers: a pixel-stride loop takes 114 ms instead of 340 ms (Node: 190 ms).
+  - So do two counters that close in on each other (`lo++, hi--`), 17% faster on a permutation-reversal loop.
+  - So do counters of loops bounded by a string's length or by an invariant limit other than an array's length, and while-loop counters that nested scans advance. A non-ASCII lexer is 9.5% faster.
+- **Loops that call a known callback** test its closure once before the loop and call the function directly, so captured `let` bindings stay in registers. `forEach` sums with a captured accumulator are 25 to 55% faster.
+- **A speculative integer loop whose check fails** finishes the iteration outside the ordinary loop, which stays optimizable, and a loop site that keeps failing stops trying. With the hole-free-prefix test that element reads now take first, a pairwise loop over an array of class instances with number fields is about 1.25 times as fast as in 0.4.1.
+- **Typed arrays over a SharedArrayBuffer** read and write elements inline as relaxed atomic accesses. A numeric kernel over shared `Float64Array`s takes 0.78 s instead of 1.56 s (Node: 0.84 s).
+- **`Math.pow(2, n)` for integer exponents** builds the result from its bits. A counter that masks with `Math.pow(2, length)` takes 11.0 s instead of 20.4 s.
+- **Async calls that never suspend run in place,** and so does `await Promise.all` of such calls, with Node's microtask turns and rejection handling. An async pipeline takes 5.5 ms instead of 9.7 ms.
+- **Strings:**
+  - `Number()` of a short integer string returns the integer directly.
+  - `split` builds its result in one inline block, and `indexOf` and `slice` on ASCII strings skip the UTF-16 index map. A log summary is 20% faster.
+  - `charAt` and `s[i]` on ASCII strings read the character from a table.
+  - Chains of one-character `replace` calls (the HTML-escape idiom) replace a block of 16 bytes at a time, 12.8% faster on a template renderer.
+- **`JSON.parse` and `JSON.stringify`** scan whole words and append parsed typed arrays in bulk, 22% faster to parse and 10% faster to stringify records.
+- **Smaller arrays, maps and program-lifetime instances:**
+  - The array header is 32 bytes instead of 48.
+  - Arrays of up to 16 known elements keep their slots in their own block.
+  - Arrays of a known final length get exactly that capacity.
+  - Small map entry arrays grow in finer steps.
+  - On Linux, `ProgramLifetime` instances take a 32-bit header and are referenced in 4 bytes.
+  - They lower the peak memory of a large TypeScript type checker: the 4-byte references alone take a large project's check from 4.13 GB to 3.75 GB, and the 32-bit header saves a further 5%.
+- **Worker messages queued together are delivered in one batch** before immediates run. 20,000 messages interleaved with a worker's output drain in 0.5 s instead of 5.6 s (Node: 0.57 s).
+- **The cycle collector** never buffers instances of classes whose fields hold nothing cycle-capable, and its per-object paths are shorter. A workload of cyclic graphs is about 5% faster.
+- **Array helpers specialized for a callback that cannot throw** skip the pending-exception test, 4.5% faster on a functional pipeline.
+- **Compile time:**
+  - A file's function declarations are walked once for their references, so lowering a 10 MB single-module bundle takes 69 s instead of 219 s.
+  - LLVM emission computes its module facts once, 6.9% faster on tsc-ts.
+  - AST walks visit subtrees by their node ranges and read node words through a `Uint32Array`.
+  - Program builds no longer import runtime bitcode, so builds through Node and through the native compiler produce identical executables.
+
+### Fixes
+
+- **Member reads and method calls on an array hole** held in a binding narrowed to one arm of a wide union throw Node's `Cannot read properties of undefined` TypeError.
+- **`AsyncLocalStorage`:**
+  - A store entered before an async function's first await, or in a body that never suspends, is the caller's store after the call.
+  - Each synchronous generator step runs in its resumer's context, as in Node.
+- **Generic arrow and function-expression bindings used before their declarations** behave as in Node, including the `ReferenceError` of a `let` or `const`.
+- **Assignment expressions into a module `let` declared without an initializer** (`new Promise((r) => (resolve = r))`) store the value instead of throwing a `ReferenceError`.
+- **The `extends` expression of a class defined inside a function** is evaluated each time the definition runs.
+- **A `super()` call that leads an `if` condition's comma chain** compiles.
+- **A catch binding tests `instanceof`** correctly for values thrown as `unknown`, rejected promises and runtime errors.
+- **zlib callbacks receive `undefined` as their result when the operation fails,** as in Node, and a callback may assign a fallback to it.
+- **`Readable.push` and `Writable.write` with `string | null` or `Buffer | null` chunks** no longer crash.
+- **Object literals keep their key order** through compiler rewrites and on shapes a typed `JSON.parse` also builds, so `JSON.stringify`, `Object.keys` and `console.log` match Node.
+- **`console.log` prints class instances with their class name** in programs that test `instanceof` on unknown values.
+- **`String`, `Number` and `Boolean` passed to array methods** convert as their direct calls do, and nested array literals in a recursive JSON-style union build.
+- **A dynamic method call that the program also reads through a prototype** finds the method when the instance's property bag does not hold it.
+- **Storing an element on `Array.prototype`** fails with SC2020, because holes in native arrays do not read inherited elements.
+- **A recursive type alias in a generic signature** no longer crashes the compiler.
+- **A `Buffer` view of an untyped typed array** compiles.
+- **JSX programs checked with tsgo** compile as they do with tsc-ts.
+- **Two programs whose entries share a name and build into one directory** no longer share a cached translation unit, so a later cache hit always relinks the right program.
+- **A warm build whose cached LLVM exceeds the engine's string limit** reads it in parts instead of failing with `Invalid string length`.
+- **The same program compiles to the same executable wherever it sits on disk** and whatever order its functions lower in, and edits outside a declaration do not rename the helpers and closures inside it.
+- **Libraries that use untyped byte arrays** link.
+
+<!-- release:end -->
+
 ## 0.4.1
 
 ### Highlights
@@ -77,8 +232,6 @@ All notable changes to scriptc will be documented in this file.
 - **TypeScript enum exports in compiled packages stay `undefined` until they are assigned,** as in Node.
 - **Element writes accept a possibly undefined index** (typed-array writes, compound and update writes, element assignments used as values and destructuring targets) and convert it with ToNumber, as element reads already did.
 
-<!-- release:end -->
-
 ## 0.4.0
 
 ### Breaking changes

benchmarks/runtime/README.md

@@ -11,6 +11,7 @@ Application-shaped workloads for measuring the speed of compiled executables. Ea
 | `channel-messages` | cpu | 200,000 MessageChannel messages in one thread, half numbers and half small objects, all posted before the port delivers any |
 | `csv-numbers` | cpu | `split`, `Number`, `parseInt`, `toFixed` |
 | `cyclic-graphs` | cpu | object graphs with back references built and dropped: trees with parent and sibling links, rings of records sharing a long-lived registry, closures capturing their owner |
+| `dictionary-walks` | cpu | `Record<string, number>` dictionaries walked with for-in and `Object.keys`/`values`/`entries` while entries are added, updated and deleted |
 | `functional-pipeline` | cpu | `filter`/`map`/`reduce`/`flatMap` chains, closures, small records |
 | `intern-table`, `intern-table-map`, `intern-table-1`, `intern-table-map-1` | cpu | worker threads interning the same type-like objects under string keys and records under number keys, then hits and misses: one shared `InternTable` per kind of key, or a module-level `Map` per thread (the `-map` entries), with 8 threads or 1 (the `-1` entries); under Node.js every thread has its own tables |
 | `json-records` | cpu | `JSON.stringify`, typed `JSON.parse`, Map aggregation |
@@ -26,7 +27,7 @@ Application-shaped workloads for measuring the speed of compiled executables. Ea
 | `region-builds` | cpu | a watch-mode build loop over `LifetimeRegion`: each build binds a program in a new region and releases the previous one, which a cache keeps referenced for two builds |
 | `template-render` | cpu | template literals, escaping, `map`/`join` |
 | `thread-slots`, `thread-slots-cache` | cpu | worker threads reading one published type graph from an `InternTable` and keeping per-thread state for each type they visit: a `ThreadSlots` family, or a direct-mapped cache by id in front of a `Map` by id (the `-cache` entry); under Node.js both are per thread |
-| `typed-array-kernels` | cpu | element-wise loops that run to one typed array's length and index others at the same position: `Float64Array` axpy, `Float32Array` blend, `Uint8Array` mask, wrapping `Int32Array` add, `Uint8ClampedArray` brighten, RGBA to gray, and `reduce`/`some`/`map` callbacks |
+| `typed-array-kernels` | cpu | element-wise loops that run to one typed array's length and index others at the same position: `Float64Array` axpy, `Float32Array` blend, `Uint8Array` mask, wrapping `Int32Array` add, `Uint8ClampedArray` brighten, RGBA to gray, a row-major `Float32Array` matrix-vector product, and `reduce`/`some`/`map` callbacks |
 | `typed-array-scan`, `typed-array-scan-workers` | cpu | element-by-element scan loops over `Uint8Array`, `Uint16Array`, `Int32Array` and `Float64Array`; the second entry is a worker-enabled executable (it can start a worker), so each access also checks for shared storage |
 | `unicode-lexer` | cpu | a hand-written lexer over a 2.7M-unit bundled module whose comments and strings are in several languages: `charCodeAt` scans, line starts |
 | `validate-errors` | cpu | throw/catch on a fraction of inputs, small call chains |

benchmarks/runtime/workloads/dictionary-walks.json

@@ -0,0 +1,6 @@
+{
+  "entry": "workloads/dictionary-walks.ts",
+  "args": [
+    "1"
+  ]
+}

benchmarks/runtime/workloads/dictionary-walks.ts

@@ -0,0 +1,53 @@
+// String-keyed dictionaries (`Record<string, number>`) walked with for-in,
+// Object.keys, Object.values and Object.entries while entries are added,
+// updated and deleted: per-category totals, a pruning pass and a merge.
+let seed = 777;
+function random(): number {
+  seed = (Math.imul(seed, 1103515245) + 12345) >>> 0;
+  return seed / 4294967296;
+}
+
+const scale = Number(process.argv[2] ?? "1");
+const categories = 4000;
+const counts: Record<string, number> = {};
+for (let i = 0; i < Math.floor(200000 * scale); i++) {
+  const key = "c" + Math.floor(random() * categories);
+  counts[key] = (counts[key] ?? 0) + 1;
+}
+
+let walked = 0;
+let sum = 0;
+for (let pass = 0; pass < 40; pass++) {
+  for (const key in counts) {
+    walked++;
+    sum += counts[key]!;
+  }
+}
+
+// Prune: delete the small categories during the walk, including keys the
+// walk has not reached yet.
+let pruned = 0;
+for (const key in counts) {
+  const n = counts[key]!;
+  if (n < 45) {
+    delete counts[key];
+    pruned++;
+  }
+  const ahead = "c" + ((Number(key.slice(1)) + 1) % categories);
+  if (n > 60 && ahead in counts && counts[ahead]! < 45) {
+    delete counts[ahead];
+    pruned++;
+  }
+}
+
+// Merge into a second dictionary and read it back every way.
+const merged: Record<string, number> = {};
+for (const key of Object.keys(counts)) merged[key.toUpperCase()] = counts[key]! * 2;
+let values = 0;
+for (const v of Object.values(merged)) values += v;
+let entries = 0;
+for (const [key, v] of Object.entries(merged)) entries += key.length + v;
+
+console.log(
+  `walked ${walked}, sum ${sum}, pruned ${pruned}, kept ${Object.keys(counts).length}, values ${values}, entries ${entries}`,
+);

benchmarks/runtime/workloads/typed-array-kernels.ts

@@ -1,5 +1,6 @@
 // Element-wise loops over several typed arrays: each loop runs to one
-// array's length and reads or writes the others at the same index.
+// array's length and reads or writes the others at the same index. Also a
+// row-major matrix-vector product with four accumulators per row.
 
 function axpy(a: number, x: Float64Array, y: Float64Array, out: Float64Array): void {
   for (let i = 0; i < out.length; i++) out[i] = a * x[i]! + y[i]!;
@@ -21,6 +22,23 @@ function brighten(src: Uint8ClampedArray, gain: number, out: Uint8ClampedArray):
   for (let i = 0; i < out.length; i++) out[i] = src[i]! * gain + 8;
 }
 
+function matvec(w: Float32Array, x: Float32Array, out: Float32Array, cols: number): void {
+  for (let r = 0; r < out.length; r++) {
+    const base = r * cols;
+    let s0 = 0;
+    let s1 = 0;
+    let s2 = 0;
+    let s3 = 0;
+    for (let j = 0; j < cols; j += 4) {
+      s0 += w[base + j]! * x[j]!;
+      s1 += w[base + j + 1]! * x[j + 1]!;
+      s2 += w[base + j + 2]! * x[j + 2]!;
+      s3 += w[base + j + 3]! * x[j + 3]!;
+    }
+    out[r] = s0 + s1 + s2 + s3;
+  }
+}
+
 // Callback methods over a whole typed array.
 function callbacks(samples: Float32Array, limit: number, data: Uint8Array): number {
   const energy = samples.reduce((sum, v) => sum + v * v, 0);
@@ -53,6 +71,10 @@ const io = new Int32Array(n);
 const pixels = new Uint8ClampedArray(n);
 const bright = new Uint8ClampedArray(n);
 const rgba = new Uint8Array(n * 4);
+const side = 256;
+const weights = new Float32Array(side * side);
+const vector = new Float32Array(side);
+const product = new Float32Array(side);
 const luma = new Uint8Array(n);
 let state = 2463534242;
 const next = (): number => {
@@ -73,6 +95,8 @@ for (let i = 0; i < n; i++) {
   pixels[i] = next() & 255;
 }
 for (let i = 0; i < rgba.length; i++) rgba[i] = next() & 255;
+for (let i = 0; i < weights.length; i++) weights[i] = (next() % 2001) / 1000 - 1;
+for (let i = 0; i < side; i++) vector[i] = (next() % 1001) / 1000;
 
 const rounds = Math.round(1200 * scale);
 let f64Sum = 0;
@@ -81,6 +105,7 @@ let byteSum = 0;
 let intSum = 0;
 let brightSum = 0;
 let lumaSum = 0;
+let productSum = 0;
 let callbackSum = 0;
 for (let r = 0; r < rounds; r++) {
   // Change one input element per round so no round repeats the last.
@@ -91,12 +116,14 @@ for (let r = 0; r < rounds; r++) {
   ia[at] = r * 65537;
   pixels[at] = r & 255;
   rgba[at * 4] = r & 255;
+  vector[r & (side - 1)] = (r % 1001) / 1000;
   axpy(1.5, x, y, d);
   blend((r & 15) / 16, fa, fb, fo);
   mask(data, key, masked);
   addWrap(ia, ib, io);
   brighten(pixels, 0.75 + (r & 7) / 8, bright);
   gray(rgba, luma);
+  matvec(weights, vector, product, side);
   if ((r & 3) === 0) callbackSum += callbacks(fo, 140 + (r & 12), masked);
   const probe = (r * 104729) & (n - 1);
   f64Sum += d[probe]!;
@@ -105,6 +132,7 @@ for (let r = 0; r < rounds; r++) {
   intSum = (intSum + io[probe]!) | 0;
   brightSum += bright[probe]!;
   lumaSum += luma[probe]!;
+  productSum += product[probe & (side - 1)]!;
 }
 console.log(`float64 ${f64Sum.toFixed(3)}`);
 console.log(`float32 ${f32Sum.toFixed(3)}`);
@@ -112,4 +140,5 @@ console.log(`uint8 ${byteSum}`);
 console.log(`int32 ${intSum}`);
 console.log(`clamped ${brightSum}`);
 console.log(`gray ${lumaSum}`);
+console.log(`matvec ${productSum.toFixed(3)}`);
 console.log(`callbacks ${callbackSum.toFixed(3)}`);

docs/content/docs/contracts.mdx

@@ -349,7 +349,7 @@ class Identifier extends SyntaxNode {
 }
 ```
 
-On Linux, except in builds with sanitizers, the instances also take less memory. An executable keeps them in one address range below 32 GiB that it reserves at startup (only the pages in use take memory), and a field typed `C`, `C | undefined` or `C | null`, where `C` is a program-lifetime class, stores the instance's address in 4 bytes instead of 8. In the example, `parent` takes 4 bytes.
+On Linux, except in builds with sanitizers, the instances also take less memory. An executable keeps them in one address range below 32 GiB that it reserves at startup (only the pages in use take memory), and a field typed `C`, `C | undefined` or `C | null`, where `C` is a program-lifetime class, stores the instance's address in 4 bytes instead of 8, as does each element of an array of such a type and each value of a `Map` with `string` keys and such a value type. In the example, `parent` takes 4 bytes.
 
 scriptc checks that the promise cannot change what the program computes (SC7008):
 

docs/content/docs/coverage.mdx

@@ -38,6 +38,8 @@ When a program has unsupported operations, the report adds a group for each root
     <tr><td><code>compile statically</code></td><td>Statements that compile to native instructions.</td></tr>
     <tr><td><code>in dynamic tier</code></td><td>Of those, the statements in functions that operate on values typed only at runtime, such as <code>any</code> values and untyped JavaScript. Shown when there are any. See <a href="#dynamic-tier">Dynamic tier</a>.</td></tr>
     <tr><td><code>blockers</code></td><td>Unsupported operations with counts, diagnostic codes, reasons, locations, and hints.</td></tr>
+    <tr><td><code>runs at startup</code></td><td>Deferred operations in a JavaScript module's top-level code, which runs when the module loads: at startup for a module the program imports.</td></tr>
+    <tr><td><code>deferred to runtime</code></td><td>Other deferred operations in JavaScript code. Each throws only if it runs.</td></tr>
     <tr><td><code>in unreached code</code></td><td>Blockers in code the entry never reaches. A build never compiles that code, so these cannot fail it.</td></tr>
     <tr><td><code>differs from Node</code></td><td>Sites that compile but can behave differently from Node.js. See <a href="#node-divergences">Node divergences</a>.</td></tr>
     <tr><td><code>npm package compilation</code></td><td>Native package compilation outcomes and refusal reasons.</td></tr>
@@ -46,7 +48,7 @@ When a program has unsupported operations, the report adds a group for each root
 
 Blockers in unreached code and deferred operations in JavaScript packages are listed separately because they don't fail a build. A deferred operation throws a runtime error if it runs, so a successful build doesn't mean every API of a package works; see [unsupported code inside a package](/docs/dependencies#unsupported-code-inside-a-package).
 
-If a function's signature can't compile, the statements in its body count as not compiling, so the percentage reflects how much of the program compiles.
+If a function's signature can't compile, the statements in its body count as not compiling, so the percentage reflects how much of the program compiles. The report still lists the diagnostics of those statements; a use of a parameter whose type can't compile reports `SC2004` back to the signature.
 
 <span id="programs-that-require-dynamic-execution" />
 <span id="analyze-with-dynamic" />
@@ -211,6 +213,10 @@ For editors, CI annotations, and other tools, `scriptc coverage --print=diagnost
       <td><code>group</code></td>
       <td>The <code>id</code> of the root-cause group the diagnostic belongs to. A group's <code>primary</code> site is its first in source order.</td>
     </tr>
+    <tr>
+      <td><code>startup</code></td>
+      <td><code>true</code> on a <code>deferred</code> diagnostic in a module's top-level code, which runs when the module loads. Absent otherwise.</td>
+    </tr>
   </tbody>
 </table>
 

docs/content/docs/dependencies.mdx

@@ -132,7 +132,7 @@ CommonJS packages compile with Node.js's module semantics. Each `require()` eval
 
 ## Unsupported code inside a package
 
-A JavaScript package can contain operations scriptc can't compile, often in functions your program never calls. These don't fail the build: each one compiles to code that throws a runtime error if it ever runs. Coverage reports list them as deferred sites, so review the list and test the parts of the package your program uses.
+A JavaScript package can contain operations scriptc can't compile, often in functions your program never calls. These don't fail the build: each one compiles to code that throws a runtime error if it ever runs. Coverage reports list them as deferred sites, so review the list and test the parts of the package your program uses. Sites in a module's top-level code are listed under `runs at startup`: that code runs when the module loads, at startup for a module the program imports.
 
 ## Provenance sources (experimental)
 

docs/content/docs/limitations.mdx

@@ -34,6 +34,8 @@ title: "Limitations"
 
 <include>../limitations/language-features/commonjs-require.mdx</include>
 
+<include>../limitations/language-features/jsx.mdx</include>
+
 ### Types and class definitions
 
 <include>../limitations/types-and-class-definitions/bigint.mdx</include>

docs/content/limitations/builtin-apis/crypto.mdx

@@ -4,11 +4,11 @@
   `copy()` of a Hash whose stream flushed, and stream use of a value after its stream closed, throw a coded SC2020 error.
   Through `unknown` and `any` slots and untyped JavaScript, Hash and Hmac values keep their identity and support `update()`, `digest()`, and Hash's `copy()`, called or read as values; their stream and event members there throw a coded SC2020 error.
   `timingSafeEqual` compares any view or ArrayBuffer.
-  Secret KeyObjects (`createSecretKey`, `generateKey` and `generateKeySync` for `hmac` and `aes`) support `type`, `symmetricKeySize`, `export()`, `equals()`, and `instanceof KeyObject`, and createHmac, hkdf, createCipheriv, and createDecipheriv accept them; asymmetric keys, `KeyObject.from()`, and `toCryptoKey()` are not available.
+  Secret KeyObjects (`createSecretKey`, `generateKey` and `generateKeySync` for `hmac` and `aes`) support `type`, `symmetricKeySize`, `export()`, `equals()`, and `instanceof KeyObject`, and createHmac, hkdf, createCipheriv, and createDecipheriv accept them; `KeyObject.from()` and `toCryptoKey()` are not available.
   `randomFill`, `randomFillSync` (every view kind and ArrayBuffer), `randomInt`, `randomUUID`, and `randomUUIDv7` follow Node 24.22, including callback timing; a `randomInt` callback whose error parameter is typed `Error | null` receives `null` where Node passes `undefined`.
   Scrypt supports its default parameters, numeric options, aliases, and memory limit.
   Both KDFs accept strings, Buffers, numeric typed arrays, DataViews, and fixed-length ArrayBuffers.
-  `createCipheriv` and `createDecipheriv` support aes-128, aes-192, and aes-256 in CBC, CTR, and GCM modes and chacha20-poly1305, on native targets, through `update()`, `final()`, `setAAD()`, `setAutoPadding()`, `getAuthTag()`, and `setAuthTag()`; other ciphers and wasm32-wasi builds are refused.
+  `createCipheriv` and `createDecipheriv` support aes-128, aes-192, and aes-256 in CBC, CTR, GCM, ECB, CFB, CFB8, CFB1, and OFB modes, des-ede3 in CBC, ECB, CFB, CFB8, CFB1, and OFB modes, des-ede in CBC, ECB, CFB, and OFB modes, chacha20, and chacha20-poly1305, on native targets, through `update()`, `final()`, `setAAD()`, `setAutoPadding()`, `getAuthTag()`, and `setAuthTag()`; other ciphers and wasm32-wasi builds are refused.
   Cipheriv and Decipheriv values are also Transforms: they can be written, piped into, used as `pipeline()` stages, read, iterated with `for await`, and listened to, and their stream properties read as in Node; written chunks go through `update()`, and the end pushes `final()` or reports its error through `'error'`.
   Through `unknown` and `any` slots and untyped JavaScript, in a program that uses streams, their stream properties and their `on`, `once`, `off`, `pipe`, `unpipe`, `read`, `pause`, `resume`, `setEncoding`, `write`, `end`, `destroy`, `cork`, and `uncork` members work; `write` and `end` take no encoding or callback there, and the other stream members throw a coded SC2020 error.
   Hash, Hmac, Cipheriv, and Decipheriv streams count a written string's bytes in `writableLength`, where Node counts the string's length.
@@ -18,8 +18,31 @@
   `createECDH` and `ECDH.convertKey` support prime192v1, secp224r1, prime256v1, secp384r1, secp521r1, secp192k1, secp224k1, secp256k1, brainpoolP256r1, brainpoolP384r1, and brainpoolP512r1, on native targets, through `generateKeys()`, `computeSecret()`, `getPublicKey()`, `getPrivateKey()`, `setPrivateKey()`, and `setPublicKey()`, in compressed, uncompressed, and hybrid forms; the other curves `crypto.getCurves()` lists and wasm32-wasi builds are refused.
   A call on an ECDH value whose arguments no @types/node overload accepts (`getPublicKey("HEX")`) is refused at compile time, as is `computeSecret(view, encoding)`: Node reads that encoding as the input encoding and answers a Buffer where @types/node declares a string.
   ECDH property reads and writes throw a coded SC2020 error.
-  Other public-key operations remain unsupported.
+  `createDiffieHellman`, `getDiffieHellman`, and `createDiffieHellmanGroup` support the modp1, modp2, modp5, and modp14 through modp18 groups, explicit primes and generators, and generated safe primes, on native targets, through `generateKeys()`, `computeSecret()`, `getPrime()`, `getGenerator()`, `getPublicKey()`, `getPrivateKey()`, `setPublicKey()`, `setPrivateKey()`, and `verifyError`, with Node's private key lengths, DH_check results, and errors; wasm32-wasi builds are refused.
+  Primes longer than 8192 bits throw a coded SC2020 error; Node accepts primes up to 10000 bits for key generation and secrets.
+  `setPublicKey()` and `setPrivateKey()` keys longer than 80000 bytes, not counting leading zero bytes, throw a coded SC2020 error, as does a generator that long with a prime below 512 bits; Node accepts them.
+  A call on a DiffieHellman value whose arguments no @types/node overload accepts, or whose output encoding is typed `any`, is refused at compile time, as are its `Object.prototype` methods; other property reads, and property writes, throw a coded SC2020 error.
+  `Object.keys()` and `in` do not see a DiffieHellman's own `verifyError` property, and `JSON.stringify()` and `instanceof` are refused.
+  After `createDiffieHellman(primeLength)` throws `Invalid DH parameters`, the next OpenSSL error Node throws can list the failed generation's errors in `opensslErrorStack`; errors in a compiled binary list only their own.
+  `crypto.diffieHellman`, which takes DH, EC, or X25519 KeyObjects, and the `DiffieHellman` and `DiffieHellmanGroup` constructors are not available.
+  `checkPrime`, `checkPrimeSync`, `generatePrime`, and `generatePrimeSync` support bigint, ArrayBuffer, typed-array, Buffer, and DataView values and the `checks`, `safe`, `add`, `rem`, and `bigint` options on native targets, with Node's errors; the callback forms compute before they return and call back in a later macrotask.
+  Candidates and sizes longer than 262144 bits throw a coded SC2020 error, and wasm32-wasi builds are refused.
+  Node calls their callbacks with `undefined` as the error, which a callback whose error parameter is typed `Error | null`, as @types/node declares it, receives as `null`.
+  RSA, EC, and Ed25519 private and public KeyObjects come from `generateKeyPairSync`, `generateKeyPair`, `createPrivateKey`, and `createPublicKey`, on native targets.
+  The EC curves are prime256v1 (P-256), secp384r1 (P-384), secp521r1 (P-521), and secp256k1.
+  Keys read and write PEM and DER as PKCS#1, SEC1, PKCS#8, and SubjectPublicKeyInfo, and JWK (Ed25519 keys use PKCS#8, SubjectPublicKeyInfo, and JWK); `createPublicKey` also takes a private key or an X.509 certificate.
+  They support `type`, `asymmetricKeyType`, `asymmetricKeyDetails`, `export()`, `equals()`, and `instanceof KeyObject`.
+  `crypto.sign`, `crypto.verify`, `createSign`, and `createVerify` support RSA PKCS#1 v1.5 and PSS padding and ECDSA with DER and IEEE P1363 encodings over SHA-1 and SHA-2 digests, and Ed25519 through `crypto.sign` and `crypto.verify` with a `null` or `undefined` algorithm.
+  Ed25519 signing, verification, and private keys link when a string literal in the program names `ed25519` (in any case); without one they throw a coded SC2020 error, while Ed25519 public keys still import and export.
+  Sign and Verify values accumulate `update()` data and are not writable streams.
+  Encrypted private keys (`passphrase`, `cipher`), the other key types (`rsa-pss`, `dsa`, `ed448`, `x25519`, and the rest), and wasm32-wasi builds throw a coded SC2020 error or are refused.
+  Comparing keys of different types with `equals()` answers false; Node also leaves an OpenSSL error queued, which a later key operation can report.
+  `publicEncrypt`/`privateDecrypt` remain unsupported.
   The WebCrypto `crypto` global, which node:crypto also exports as `webcrypto`, supports `randomUUID()` and `getRandomValues()`, also read as values from untyped JavaScript.
-  Its `subtle` object, also node:crypto's `subtle` export, supports `generateKey()` and `exportKey()` for HMAC and AES keys, `importKey()` for HMAC, AES, PBKDF2, and HKDF keys, `encrypt()` and `decrypt()` with AES-GCM, AES-CBC, and AES-CTR on native targets, `deriveBits()` and `deriveKey()` with PBKDF2 and HKDF, HMAC `sign()` and `verify()`, and SHA-1 and SHA-2 `digest()`.
-  Secret keys import and export in the `raw`, `raw-secret`, and `jwk` formats; other SubtleCrypto methods, algorithms, and key formats are refused.
+  Its `subtle` object, also node:crypto's `subtle` export, supports `generateKey()` and `exportKey()` for HMAC and AES keys, `importKey()` for HMAC, AES, PBKDF2, and HKDF keys, `encrypt()` and `decrypt()` with AES-GCM, AES-CBC, and AES-CTR and `wrapKey()` and `unwrapKey()` of secret keys with AES-KW or those ciphers on native targets, `deriveBits()` and `deriveKey()` with PBKDF2 and HKDF, HMAC `sign()` and `verify()`, and SHA-1 and SHA-2 `digest()`.
+  Secret keys import and export in the `raw`, `raw-secret`, and `jwk` formats.
+  `generateKey()`, `importKey()`, `exportKey()`, `sign()`, and `verify()` also support ECDSA (P-256, P-384, and P-521), Ed25519, RSASSA-PKCS1-v1_5, and RSA-PSS, with the `spki`, `pkcs8`, and `jwk` formats and `raw` for ECDSA and Ed25519 public keys; ECDSA, Ed25519, and RSA are refused in wasm32-wasi builds.
+  ECDSA, Ed25519, and RSA link when a string literal in the program names the algorithm; a name built only at run time throws a coded SC2020 error.
+  `wrapKey()` and `unwrapKey()` of ECDSA, Ed25519, and RSA keys throw a coded SC2020 error.
+  Other SubtleCrypto methods, algorithms, and key formats are refused or throw a coded SC2020 error.
   Native derivations finish before their deferred callbacks, so computation blocks the caller.

docs/content/limitations/builtin-apis/streams-and-readline.mdx

@@ -1,13 +1,17 @@
-- **Streams and readline:** Stream chunks are Buffers or strings.
+- **Streams and readline:** Stream chunks are Buffers or strings, and on an object-mode side any value that converts to a checked-dynamic value.
   `NodeJS.ReadableStream` and `NodeJS.WritableStream`, and `stream.Readable` and `stream.Writable` under `@types/node`, accept every stream: when a program passes file, zlib, or `node:stream` streams through them, child-process pipes and `process.stdout` and `process.stderr` join those streams as `Readable` and `Writable` instances.
   `readable.pipe(process.stdout)` and `readable.pipe(process.stderr)` compile and, as in Node, do not end the process stream.
   When an untyped value reaches `NodeJS.ReadableStream` or `NodeJS.WritableStream`, those two interfaces hold any value, so JavaScript stream objects (constructor-function streams, plain objects with `on` and `pipe`) pass through TypeScript functions typed with them and come back to JavaScript as the same objects.
   Member calls on such a value use the native stream when it is one and call the object's own members otherwise; `readable.pipe()` into a JavaScript destination follows Node's pipe protocol.
   A `pipeline` stage and a `for await` source that arrive as untyped values must be native streams, or `Cipheriv` and `Decipheriv` values, at run time; other values throw a not-supported error.
   Native streams expose no `emit` to JavaScript, so a JavaScript stream whose own `pipe()` emits on its destination (the legacy `Stream` pipe) cannot pipe into one.
-  `Readable.from` accepts arrays, Sets, Map and Set iterators, generators, async generators, and class iterables and async iterables whose values are strings or Buffers, and in JavaScript any iterable or async iterable of them; a stream that mixes strings and Buffers is unsupported.
+  `Readable.from` accepts strings, Buffers, arrays, Sets, Maps, Map and Set iterators, generators, async generators, and class iterables and async iterables, and in JavaScript any iterable or async iterable.
   In JavaScript, a sync iterator value with a `then` method that is not a promise, and an object whose `[Symbol.asyncIterator]` or `[Symbol.iterator]` method is a generator method, are unsupported.
-  Object-mode streams of other values (including `Readable.from` over a `Map`, whose values are entry arrays) are unsupported.
+  The `objectMode` option, and the `readableObjectMode` and `writableObjectMode` options of a `Duplex`, `Transform`, or `PassThrough`, take `true` or `false` literals in an options object literal; options passed as a value are read when the stream is built.
+  In typed code, a `write` or `transform` callback, or a `_write` or `_transform` method, may declare its chunk with any type that converts to a checked-dynamic value: the chunk converts when the callback runs, and a value of another type throws a TypeError there.
+  An object-mode write passes its encoding argument to `write` and `transform` as Node does (`undefined` when absent, `null` when a callback took its place); a parameter declared `string` receives `""` for `undefined` and `null`, and one declared `string | null | undefined` receives Node's value.
+  `readable.read()` on an object-mode stream answers its Buffers; another value throws a not-supported error (read such values with `'data'` listeners, `for await`, or `pipe`).
+  `node:stream/consumers` and readline interfaces read object-mode streams of strings and Buffers; other values throw a not-supported error.
   `pipeline` accepts function stages anywhere among its streams: async generator functions (`async function* (source)`, iterating `source` with `for await`), an async generator source function (`async function* ({ signal })`), and an async function destination whose value resolves the promise form and reaches the callback's second argument.
   A stage is written inline, or named by a function declaration or a `const` bound to a function expression that nothing reassigns.
   The source may also be an array, a string, a synchronous generator object, or a synchronous generator function without parameters; their elements reach the next stage on the same ticks as in Node.

docs/content/limitations/builtin-function-values.mdx

@@ -28,7 +28,7 @@ The `captureRejections` option and `events.errorMonitor` listeners are not suppo
 The stream calls the object's `_read`, `_write`, `_final`, `_transform`, `_flush`, and `_destroy` with the object as `this`, and the stream prototypes' methods and accessors work on it.
 Its listeners live in the native stream rather than in `_events`, and `_readableState` and `_writableState` are read-only views that answer the commonly read fields.
 Typed code that receives such an object as a stream class uses its native stream, and piping a native stream into it works.
-The options the native streams refuse (`objectMode`, `decodeStrings: false`, `signal`, and others) are refused here too, as are `_writev`, `_construct`, symbol event names, `listeners()`, `rawListeners()`, `wrap()`, strings written in encodings other than UTF-8, and pipes into a destination that overrides `write()` or `end()`.
+The options the native streams refuse (`decodeStrings: false`, `signal`, and others) are refused here too, as are `_writev`, `_construct`, symbol event names, `listeners()`, `rawListeners()`, `wrap()`, strings written to a byte-mode stream in encodings other than UTF-8, and pipes into a destination that overrides `write()` or `end()`.
 Other class constructors passed to `util.inherits` or `util.deprecate` are refused.
 Deprecation warnings are emitted on the next tick and follow assignments to `process.noDeprecation` and `process.throwDeprecation`; compiled binaries take no Node command-line flags such as `--no-deprecation` or `--trace-deprecation`, and `process.traceDeprecation` is unsupported.
 A stored `util.deprecate` reports a `length` of 4, where Node reports 3.

docs/content/limitations/language-features/jsx.mdx

@@ -0,0 +1,5 @@
+- **JSX:** JSX in `.tsx`, `.jsx` and JavaScript files compiles with the project's `jsx` setting: `"react"` with `jsxFactory`, `jsxFragmentFactory` or `reactNamespace`, and `"react-jsx"` or `"react-jsxdev"` with `jsxImportSource`, as well as the `@jsx`, `@jsxFrag`, `@jsxImportSource` and `@jsxRuntime` pragmas.
+  The checker types JSX with these settings, and each element becomes the call TypeScript emits for it, importing the automatic runtime's functions from `<jsxImportSource>/jsx-runtime` or `jsx-dev-runtime`.
+  `"jsx": "preserve"` and `"react-native"`, which keep JSX in the output, are refused.
+  The call an element becomes must type-check: a factory or runtime function whose parameters do not accept what an element passes is reported at the element.
+  With `"react-jsxdev"`, `jsxDEV` receives `undefined` as `self` where `this` has no declared type (in a function that is not a method), which is the value such a function observes when called without a receiver.

docs/src/generated/node-v24-compatibility.json

@@ -11085,9 +11085,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the call shapes accepted by the compiler lowering.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11108,9 +11108,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the call shapes accepted by the compiler lowering.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11177,9 +11177,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Supports the modp groups, explicit primes and generators, and generated safe primes up to 8192 bits with Node's argument, generator and modulus errors.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11200,9 +11200,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Supports the modp groups, explicit primes and generators, and generated safe primes up to 8192 bits with Node's argument, generator and modulus errors.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11223,9 +11223,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Supports the modp groups, explicit primes and generators, and generated safe primes up to 8192 bits with Node's argument, generator and modulus errors.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11247,7 +11247,7 @@
       },
       "static": {
         "status": "partial",
-        "detail": "Implemented for the call shapes accepted by the compiler lowering.",
+        "detail": "Supports prime192v1, secp224r1, prime256v1, secp384r1, secp521r1, secp192k1, secp224k1, secp256k1, brainpoolP256r1, brainpoolP384r1 and brainpoolP512r1 with Node's curve, key, point, format and encoding errors; other curves Node knows are refused.",
         "verification": "test-backed"
       }
     },
@@ -11338,9 +11338,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11361,9 +11361,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11407,9 +11407,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11430,9 +11430,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11545,9 +11545,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11568,9 +11568,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11614,9 +11614,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the call shapes accepted by the compiler lowering.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11637,9 +11637,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the call shapes accepted by the compiler lowering.",
+        "verification": "test-backed"
       }
     },
     {
@@ -11729,9 +11729,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Supports the modp groups, explicit primes and generators, and generated safe primes up to 8192 bits with Node's argument, generator and modulus errors.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12327,9 +12327,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12373,9 +12373,9 @@
         "inherited": true
       },
       "static": {
-        "status": "refused",
-        "detail": "Explicitly rejected by a named compiler diagnostic.",
-        "verification": "explicit-refusal"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12856,9 +12856,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12879,9 +12879,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12902,9 +12902,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12925,9 +12925,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12948,9 +12948,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12971,9 +12971,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -12994,9 +12994,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13017,9 +13017,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13040,9 +13040,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13063,9 +13063,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13086,9 +13086,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13523,9 +13523,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13546,9 +13546,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13684,9 +13684,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13707,9 +13707,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13730,9 +13730,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13753,9 +13753,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13776,9 +13776,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -13799,9 +13799,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -18880,9 +18880,9 @@
       "anchor": "err_crypto_invalid_keylen",
       "nodeStability": null,
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -19006,9 +19006,9 @@
       "anchor": "err_crypto_invalid_state",
       "nodeStability": null,
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -19276,9 +19276,9 @@
       "anchor": "err_crypto_unknown_dh_group",
       "nodeStability": null,
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented by a dedicated static compiler/runtime path.",
+        "verification": "test-backed"
       }
     },
     {
@@ -67806,9 +67806,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the documented scriptc module-loader subset.",
+        "verification": "test-backed"
       }
     },
     {
@@ -68565,9 +68565,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the documented scriptc module-loader subset.",
+        "verification": "test-backed"
       }
     },
     {
@@ -80277,9 +80277,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the documented scriptc module-loader subset.",
+        "verification": "test-backed"
       }
     },
     {
@@ -80323,9 +80323,9 @@
         "inherited": true
       },
       "static": {
-        "status": "not-implemented",
-        "detail": "No static compiler lowering is registered for this API yet.",
-        "verification": "registry-gap"
+        "status": "partial",
+        "detail": "Implemented for the documented scriptc module-loader subset.",
+        "verification": "test-backed"
       }
     },
     {

internal/compatibility/src/generate.mjs

@@ -582,17 +582,27 @@ function publicDetail(tier) {
   if (/^surface-manifest:node-builtin\.crypto\.create(?:Cipheriv|Decipheriv)$/.test(source)) {
     return "Supports aes-128/192/256 in cbc, ctr, and gcm modes and chacha20-poly1305 with Node's argument, IV, tag-length, and key-length errors; other OpenSSL ciphers and KeyObject keys are refused.";
   }
+  if (/^surface-manifest:node-builtin\.crypto\.createECDH$/.test(source)) {
+    return "Supports prime192v1, secp224r1, prime256v1, secp384r1, secp521r1, secp192k1, secp224k1, secp256k1, brainpoolP256r1, brainpoolP384r1 and brainpoolP512r1 with Node's curve, key, point, format and encoding errors; other curves Node knows are refused.";
+  }
+  if (
+    /^surface-manifest:node-builtin\.crypto\.(?:createDiffieHellman|createDiffieHellmanGroup|getDiffieHellman)$/.test(
+      source,
+    )
+  ) {
+    return "Supports the modp groups, explicit primes and generators, and generated safe primes up to 8192 bits with Node's argument, generator and modulus errors.";
+  }
   if (source.startsWith("surface-manifest:"))
     return "Implemented for the call shapes accepted by the compiler lowering.";
   if (/^compiler-dedicated:assert\.doesNot(?:Throw|Reject)$/.test(source)) {
     return "Supports callbacks or native promises with messages, Error classes, regular expressions, and validators accepting unknown values; object expectations and complete AssertionError metadata remain unsupported.";
   }
-  if (/^surface-manifest:node-builtin\.crypto\.createECDH$/.test(source)) {
-    return "Supports prime192v1, secp224r1, prime256v1, secp384r1, secp521r1, secp192k1, secp224k1, secp256k1, brainpoolP256r1, brainpoolP384r1 and brainpoolP512r1 with Node's curve, key, point, format and encoding errors; other curves Node knows are refused.";
-  }
   if (/^compiler-dedicated:(?:ECDH|ecdh\.)/.test(source)) {
     return "Matches Node's key formats, point encodings, private-key range checks, key-pair checks and errors on the supported curves; ECDH.convertKey is supported, and property reads and writes are refused.";
   }
+  if (/^compiler-dedicated:(?:DiffieHellman|diffieHellman\.)/.test(source)) {
+    return "Matches Node's private key lengths, DH_check results, public key range checks, secret padding and errors; primes longer than 8192 bits, property writes and property reads other than verifyError are refused.";
+  }
   if (/^compiler-dedicated:(?:Cipheriv|Decipheriv|cipher\.|decipher\.)/.test(source)) {
     return "Matches Node's update() output lengths, padding, authentication tags, string encodings, and state errors for the supported ciphers, and its stream.Transform behavior: chunks written through update(), final() pushed at the end, and its errors reported through 'error'.";
   }

internal/compatibility/static-support.json

@@ -42,8 +42,12 @@
     "node-builtin.child_process": ["tests/corpus/1361-spawn-events.ts", "tests/corpus/1565-spawn-pipe-streams.ts", "tests/corpus/2911-execfile-callback.ts", "tests/corpus/2939-child-shell-text.ts", "tests/corpus/2946-child-fork-ipc/main.ts", "tests/corpus/3127-spawn-runtime-options.ts", "tests/corpus/3130-child-generic-streams.ts", "tests/corpus/3131-child-rest-listeners.js", "tests/corpus/3132-child-generic-stream-completion.ts"],
     "node-builtin.cluster": ["tests/corpus/957-builtins-namespace.ts"],
     "node-builtin.console": ["tests/corpus/console-imports.cjs", "tests/corpus/2440-console-inspect-args.ts", "tests/corpus/console-native-value.js", "tests/harness/npm-static.test.ts"],
-    "node-builtin.crypto.createCipheriv": ["tests/corpus/5250-cipher-aes-gcm.ts", "tests/corpus/5251-cipher-aes-cbc.ts", "tests/corpus/5252-cipher-aes-ctr.ts", "tests/corpus/5253-cipher-chacha20-poly1305.ts", "tests/corpus/5254-cipher-errors.js", "tests/corpus/5255-cipher-encodings.cjs", "tests/corpus/5256-cipher-deprecation.cjs", "tests/corpus/5257-cipher-vectors.ts", "tests/corpus/5258-cipher-handles.js", "tests/corpus/5259-cipher-chunked.ts", "tests/corpus/7055-cipher-streams.ts", "tests/corpus/7056-cipher-stream-errors.ts", "tests/corpus/7057-cipher-streams.mjs", "tests/fixtures/node-types/cipher.ts"],
-    "node-builtin.crypto.createDecipheriv": ["tests/corpus/5250-cipher-aes-gcm.ts", "tests/corpus/5251-cipher-aes-cbc.ts", "tests/corpus/5252-cipher-aes-ctr.ts", "tests/corpus/5253-cipher-chacha20-poly1305.ts", "tests/corpus/5254-cipher-errors.js", "tests/corpus/5255-cipher-encodings.cjs", "tests/corpus/5256-cipher-deprecation.cjs", "tests/corpus/5257-cipher-vectors.ts", "tests/corpus/5258-cipher-handles.js", "tests/corpus/5259-cipher-chunked.ts", "tests/corpus/7055-cipher-streams.ts", "tests/corpus/7056-cipher-stream-errors.ts", "tests/corpus/7057-cipher-streams.mjs", "tests/fixtures/node-types/cipher.ts"],
+    "node-builtin.crypto.checkPrime": ["tests/corpus/7152-crypto-prime.ts", "tests/corpus/7153-crypto-prime-errors.cjs"],
+    "node-builtin.crypto.checkPrimeSync": ["tests/corpus/7152-crypto-prime.ts", "tests/corpus/7153-crypto-prime-errors.cjs"],
+    "node-builtin.crypto.createCipheriv": ["tests/corpus/7150-cipher-legacy-modes.ts", "tests/corpus/7151-cipher-legacy-errors.cjs", "tests/corpus/5250-cipher-aes-gcm.ts", "tests/corpus/5251-cipher-aes-cbc.ts", "tests/corpus/5252-cipher-aes-ctr.ts", "tests/corpus/5253-cipher-chacha20-poly1305.ts", "tests/corpus/5254-cipher-errors.js", "tests/corpus/5255-cipher-encodings.cjs", "tests/corpus/5256-cipher-deprecation.cjs", "tests/corpus/5257-cipher-vectors.ts", "tests/corpus/5258-cipher-handles.js", "tests/corpus/5259-cipher-chunked.ts", "tests/corpus/7055-cipher-streams.ts", "tests/corpus/7056-cipher-stream-errors.ts", "tests/corpus/7057-cipher-streams.mjs", "tests/fixtures/node-types/cipher.ts"],
+    "node-builtin.crypto.createDecipheriv": ["tests/corpus/7150-cipher-legacy-modes.ts", "tests/corpus/7151-cipher-legacy-errors.cjs", "tests/corpus/5250-cipher-aes-gcm.ts", "tests/corpus/5251-cipher-aes-cbc.ts", "tests/corpus/5252-cipher-aes-ctr.ts", "tests/corpus/5253-cipher-chacha20-poly1305.ts", "tests/corpus/5254-cipher-errors.js", "tests/corpus/5255-cipher-encodings.cjs", "tests/corpus/5256-cipher-deprecation.cjs", "tests/corpus/5257-cipher-vectors.ts", "tests/corpus/5258-cipher-handles.js", "tests/corpus/5259-cipher-chunked.ts", "tests/corpus/7055-cipher-streams.ts", "tests/corpus/7056-cipher-stream-errors.ts", "tests/corpus/7057-cipher-streams.mjs", "tests/fixtures/node-types/cipher.ts"],
+    "node-builtin.crypto.createDiffieHellman": ["tests/corpus/6706-dh-groups.ts", "tests/corpus/6707-dh-explicit-params.ts", "tests/corpus/6708-dh-errors.js", "tests/corpus/6709-dh-generate.ts", "tests/corpus/6710-dh-encodings.cjs", "tests/corpus/6711-dh-handles.ts", "tests/fixtures/node-types/dh.ts"],
+    "node-builtin.crypto.createDiffieHellmanGroup": ["tests/corpus/6706-dh-groups.ts", "tests/corpus/6707-dh-explicit-params.ts", "tests/corpus/6708-dh-errors.js", "tests/corpus/6709-dh-generate.ts", "tests/corpus/6710-dh-encodings.cjs", "tests/corpus/6711-dh-handles.ts", "tests/fixtures/node-types/dh.ts"],
     "node-builtin.crypto.createECDH": ["tests/corpus/6700-ecdh-shared-secret.ts", "tests/corpus/6701-ecdh-formats.ts", "tests/corpus/6702-ecdh-errors.js", "tests/corpus/6703-ecdh-private-keys.ts", "tests/corpus/6704-ecdh-set-public-key.cjs", "tests/corpus/6705-ecdh-handles.ts", "tests/fixtures/node-types/ecdh.ts"],
     "node-builtin.crypto": ["tests/corpus/1358-crypto-random.ts", "tests/corpus/1534-crypto-hash-chain.ts", "tests/corpus/2556-crypto-introspection.ts", "tests/corpus/2890-crypto-static-utility.ts", "tests/harness/npm-static.test.ts", "tests/corpus/node24-crypto-sha2.ts", "tests/corpus/node24-crypto-kdf.ts", "tests/corpus/node24-crypto-kdf-errors.ts", "tests/corpus/node24-crypto-kdf-options.ts"],
     "node-builtin.dgram": ["tests/corpus/2597-dgram-send-ladders.cjs"],
@@ -118,6 +122,9 @@
     "node-builtin.os.version": ["tests/corpus/5140-os-host-facts.ts"],
     "node-builtin.os.constants": ["tests/corpus/5141-os-constants.ts"],
     "node-builtin.fs.constants": ["tests/corpus/6207-fs-constants-object.ts", "tests/corpus/6208-fs-constants-require.cjs"],
+    "node-builtin.crypto.generatePrime": ["tests/corpus/7152-crypto-prime.ts", "tests/corpus/7153-crypto-prime-errors.cjs"],
+    "node-builtin.crypto.generatePrimeSync": ["tests/corpus/7152-crypto-prime.ts", "tests/corpus/7153-crypto-prime-errors.cjs"],
+    "node-builtin.crypto.getDiffieHellman": ["tests/corpus/6706-dh-groups.ts", "tests/corpus/6707-dh-explicit-params.ts", "tests/corpus/6708-dh-errors.js", "tests/corpus/6709-dh-generate.ts", "tests/corpus/6710-dh-encodings.cjs", "tests/corpus/6711-dh-handles.ts", "tests/fixtures/node-types/dh.ts"],
     "node-builtin.crypto.getRandomValues": ["tests/corpus/6204-crypto-get-random-values.ts", "tests/corpus/6205-crypto-get-random-values.js"],
     "node-builtin.url.parse": ["tests/corpus/5220-url-parse-warnings.ts", "tests/corpus/5221-url-parse-shapes.ts", "tests/corpus/5222-url-parse-hosts.ts", "tests/corpus/5223-url-parse-query.ts", "tests/corpus/5227-url-legacy-dependency/main.ts", "tests/corpus/5229-url-legacy-errors.cjs", "packages/runtime/test/url-legacy.test.ts", "tests/fixtures/node-types/url-legacy.ts"],
     "node-builtin.url.format": ["tests/corpus/5224-url-format-objects.ts", "tests/corpus/5225-url-format-whatwg.ts", "tests/corpus/5227-url-legacy-dependency/main.ts", "tests/corpus/5229-url-legacy-errors.cjs", "packages/runtime/test/url-legacy.test.ts", "tests/fixtures/node-types/url-legacy.ts"],
@@ -187,14 +194,14 @@
     "stdlib.set": ["tests/corpus/typed-collection-iterators.ts", "tests/corpus/typed-collection-iterator-references.ts", "tests/corpus/checked-collection-iterators.ts"],
     "stdlib.headers": ["tests/harness/fetch-conformance.test.ts"],
     "stdlib.request": ["tests/harness/fetch-conformance.test.ts"],
-    "stdlib.webcrypto.subtle": ["tests/corpus/7128-webcrypto-derive.ts", "tests/corpus/7129-webcrypto-derive-errors.mjs", "tests/corpus/7126-webcrypto-aes.ts", "tests/corpus/7127-webcrypto-aes-errors.mjs", "tests/corpus/7124-webcrypto-secret-keys.ts", "tests/corpus/7125-webcrypto-key-errors.mjs", "tests/corpus/6291-webcrypto-hmac-sign-verify.ts", "tests/corpus/6292-webcrypto-hmac-errors.ts", "tests/corpus/6293-webcrypto-digest.ts", "tests/corpus/6294-webcrypto-js-values.mjs", "tests/corpus/6295-jose-hs256/main.mjs"],
+    "stdlib.webcrypto.subtle": ["tests/corpus/7130-webcrypto-wrap-key.ts", "tests/corpus/7131-webcrypto-wrap-key-errors.mjs", "tests/corpus/7132-jose-pbes2/main.mjs", "tests/corpus/7128-webcrypto-derive.ts", "tests/corpus/7129-webcrypto-derive-errors.mjs", "tests/corpus/7126-webcrypto-aes.ts", "tests/corpus/7127-webcrypto-aes-errors.mjs", "tests/corpus/7124-webcrypto-secret-keys.ts", "tests/corpus/7125-webcrypto-key-errors.mjs", "tests/corpus/6291-webcrypto-hmac-sign-verify.ts", "tests/corpus/6292-webcrypto-hmac-errors.ts", "tests/corpus/6293-webcrypto-digest.ts", "tests/corpus/6294-webcrypto-js-values.mjs", "tests/corpus/6295-jose-hs256/main.mjs"],
     "stdlib.webcrypto.CryptoKey": ["tests/corpus/7124-webcrypto-secret-keys.ts", "tests/corpus/6291-webcrypto-hmac-sign-verify.ts", "tests/corpus/6294-webcrypto-js-values.mjs", "tests/corpus/6295-jose-hs256/main.mjs"],
     "stdlib.response": ["tests/harness/fetch-conformance.test.ts"],
     "stdlib.readable-stream": ["tests/harness/fetch-conformance.test.ts"],
     "stdlib.abort": ["tests/harness/fetch-conformance.test.ts"]
   },
   "features": [
-    { "chapter": "webcrypto", "symbols": ["subtle.importKey", "subtle.generateKey", "subtle.exportKey", "subtle.encrypt", "subtle.decrypt", "subtle.deriveBits", "subtle.deriveKey", "subtle.sign", "subtle.verify", "subtle.digest"], "status": "partial", "evidence": ["tests/corpus/7128-webcrypto-derive.ts", "tests/corpus/7129-webcrypto-derive-errors.mjs", "tests/corpus/7126-webcrypto-aes.ts", "tests/corpus/7127-webcrypto-aes-errors.mjs", "tests/corpus/7124-webcrypto-secret-keys.ts", "tests/corpus/7125-webcrypto-key-errors.mjs", "tests/fixtures/node-types/webcrypto-keys.ts", "tests/corpus/6291-webcrypto-hmac-sign-verify.ts", "tests/corpus/6292-webcrypto-hmac-errors.ts", "tests/corpus/6293-webcrypto-digest.ts", "tests/corpus/6294-webcrypto-js-values.mjs", "tests/corpus/6295-jose-hs256/main.mjs", "tests/fixtures/node-types/webcrypto-hmac.ts"] },
+    { "chapter": "webcrypto", "symbols": ["subtle.importKey", "subtle.generateKey", "subtle.exportKey", "subtle.encrypt", "subtle.decrypt", "subtle.wrapKey", "subtle.unwrapKey", "subtle.deriveBits", "subtle.deriveKey", "subtle.sign", "subtle.verify", "subtle.digest"], "status": "partial", "evidence": ["tests/corpus/7130-webcrypto-wrap-key.ts", "tests/corpus/7131-webcrypto-wrap-key-errors.mjs", "tests/corpus/7132-jose-pbes2/main.mjs", "tests/corpus/7128-webcrypto-derive.ts", "tests/corpus/7129-webcrypto-derive-errors.mjs", "tests/corpus/7126-webcrypto-aes.ts", "tests/corpus/7127-webcrypto-aes-errors.mjs", "tests/corpus/7124-webcrypto-secret-keys.ts", "tests/corpus/7125-webcrypto-key-errors.mjs", "tests/fixtures/node-types/webcrypto-keys.ts", "tests/corpus/6291-webcrypto-hmac-sign-verify.ts", "tests/corpus/6292-webcrypto-hmac-errors.ts", "tests/corpus/6293-webcrypto-digest.ts", "tests/corpus/6294-webcrypto-js-values.mjs", "tests/corpus/6295-jose-hs256/main.mjs", "tests/fixtures/node-types/webcrypto-hmac.ts", "tests/corpus/7081-webcrypto-ed25519.mjs", "tests/corpus/7085-webcrypto-ecdsa-rsa.ts", "tests/corpus/7086-webcrypto-ecdsa-rsa-errors.mjs"] },
     { "chapter": "webcrypto", "signatures": ["Class: `SubtleCrypto`", "`subtle` Type: {SubtleCrypto}"], "status": "partial", "evidence": ["tests/corpus/6291-webcrypto-hmac-sign-verify.ts", "tests/corpus/6292-webcrypto-hmac-errors.ts", "tests/corpus/6293-webcrypto-digest.ts", "tests/corpus/6294-webcrypto-js-values.mjs", "tests/corpus/6295-jose-hs256/main.mjs"] },
     { "chapter": "webcrypto", "signatures": ["Class: `CryptoKey`", "`cryptoKey.algorithm`", "`extractable` Type: {boolean}", "`type` Type: {string} One of `'secret'`, `'private'`, or `'public'`.", "`usages` Type: {string\\[]}"], "status": "partial", "evidence": ["tests/corpus/7124-webcrypto-secret-keys.ts", "tests/corpus/6291-webcrypto-hmac-sign-verify.ts", "tests/corpus/6294-webcrypto-js-values.mjs", "tests/corpus/6295-jose-hs256/main.mjs"] },
     { "chapter": "webcrypto", "signatures": ["Class: `Crypto`"], "status": "partial", "evidence": ["tests/corpus/7120-webcrypto-random-uuid.ts", "tests/corpus/7121-webcrypto-crypto-object.mjs", "tests/corpus/6293-webcrypto-digest.ts"] },
@@ -369,6 +376,7 @@
     { "chapter": "console", "signatures": ["Class: `Console`"], "status": "partial", "evidence": ["tests/corpus/4900-console-instances.ts", "tests/corpus/4901-console-instance-errors.ts"] },
     { "chapter": "tls", "signatures": ["`alpnProtocol` Type: {string|boolean|null}"], "status": "partial", "evidence": ["tests/corpus/6721-tls-alpn-protocols.ts"] },
     { "chapter": "tls", "signatures": ["`tlsSocket.getProtocol()`"], "status": "partial", "evidence": ["tests/corpus/6722-tls-min-max-version.ts"] },
+    { "chapter": "tls", "signatures": ["Class: `tls.TLSSocket`", "Event: `'secure'`"], "status": "partial", "evidence": ["tests/corpus/7087-tls-socket-wrap.ts", "tests/corpus/7088-tls-socket-connect-tunnel.ts", "tests/fixtures/node-types/tls-socket-wrap.ts"] },
     { "chapter": "webstreams", "signatures": ["`readableStream.values([options])`"], "status": "partial", "evidence": ["tests/corpus/2862-web-readable-async-iteration.ts"] },
     { "chapter": "webstreams", "signatures": ["`streamConsumers.text(stream)`", "`streamConsumers.json(stream)`", "`streamConsumers.buffer(stream)`"], "status": "partial", "evidence": ["tests/corpus/2629-stream-consumers.ts", "tests/corpus/2630-stream-consumers-errors.ts"] },
     { "chapter": "webstreams", "signatures": ["`streamConsumers.arrayBuffer(stream)`"], "status": "partial", "evidence": ["tests/corpus/4875-stream-consumers-array-buffer.ts"] },
@@ -417,10 +425,13 @@
     { "chapter": "crypto", "symbols": ["Cipheriv", "cipher.update", "cipher.final", "cipher.setAAD", "cipher.getAuthTag", "cipher.setAutoPadding", "Decipheriv", "decipher.update", "decipher.final", "decipher.setAAD", "decipher.setAuthTag", "decipher.setAutoPadding"], "status": "partial", "evidence": ["tests/corpus/5250-cipher-aes-gcm.ts", "tests/corpus/5251-cipher-aes-cbc.ts", "tests/corpus/5252-cipher-aes-ctr.ts", "tests/corpus/5253-cipher-chacha20-poly1305.ts", "tests/corpus/5254-cipher-errors.js", "tests/corpus/5255-cipher-encodings.cjs", "tests/corpus/5256-cipher-deprecation.cjs", "tests/corpus/5257-cipher-vectors.ts", "tests/corpus/5258-cipher-handles.js", "tests/corpus/5259-cipher-chunked.ts", "tests/corpus/7055-cipher-streams.ts", "tests/corpus/7056-cipher-stream-errors.ts", "tests/corpus/7057-cipher-streams.mjs", "tests/fixtures/node-types/cipher.ts"] },
     { "chapter": "crypto", "symbols": ["crypto.webcrypto", "subtle"], "status": "partial", "evidence": ["tests/corpus/7122-webcrypto-node-crypto.ts", "tests/corpus/7123-webcrypto-node-crypto.cjs"] },
     { "chapter": "crypto", "symbols": ["ECDH", "ecdh.computeSecret", "ecdh.generateKeys", "ecdh.getPrivateKey", "ecdh.getPublicKey", "ecdh.setPrivateKey", "ecdh.setPublicKey"], "status": "partial", "evidence": ["tests/corpus/6700-ecdh-shared-secret.ts", "tests/corpus/6701-ecdh-formats.ts", "tests/corpus/6702-ecdh-errors.js", "tests/corpus/6703-ecdh-private-keys.ts", "tests/corpus/6704-ecdh-set-public-key.cjs", "tests/corpus/6705-ecdh-handles.ts", "tests/fixtures/node-types/ecdh.ts"] },
+    { "chapter": "crypto", "symbols": ["DiffieHellman", "DiffieHellmanGroup", "diffieHellman.computeSecret", "diffieHellman.generateKeys", "diffieHellman.getGenerator", "diffieHellman.getPrime", "diffieHellman.getPrivateKey", "diffieHellman.getPublicKey", "diffieHellman.setPrivateKey", "diffieHellman.setPublicKey", "diffieHellman.verifyError"], "status": "partial", "evidence": ["tests/corpus/6706-dh-groups.ts", "tests/corpus/6707-dh-explicit-params.ts", "tests/corpus/6708-dh-errors.js", "tests/corpus/6709-dh-generate.ts", "tests/corpus/6710-dh-encodings.cjs", "tests/corpus/6711-dh-handles.ts", "tests/fixtures/node-types/dh.ts"] },
+    { "chapter": "errors", "symbols": ["ERR_CRYPTO_UNKNOWN_DH_GROUP", "ERR_CRYPTO_INVALID_KEYLEN", "ERR_CRYPTO_INVALID_STATE"], "status": "partial", "evidence": ["tests/corpus/6708-dh-errors.js"] },
     { "chapter": "errors", "symbols": ["ERR_CRYPTO_ECDH_INVALID_FORMAT", "ERR_CRYPTO_ECDH_INVALID_PUBLIC_KEY"], "status": "partial", "evidence": ["tests/corpus/6702-ecdh-errors.js"] },
     { "symbols": ["crypto.createHash", "Hash", "hash.update", "hash.digest", "hash.copy", "crypto.createHmac", "Hmac", "hmac.update", "hmac.digest", "crypto.hash", "crypto.pbkdf2", "crypto.pbkdf2Sync"], "status": "partial", "evidence": ["tests/corpus/5760-crypto-hash-stream.ts", "tests/corpus/5768-crypto-hash-unknown.ts", "tests/corpus/5769-crypto-hash-unknown.cjs", "tests/corpus/5761-crypto-hash-stream-states.ts", "tests/corpus/5762-crypto-hash-stream.cjs", "tests/corpus/2890-crypto-static-utility.ts", "tests/corpus/node24-crypto-sha2.ts", "tests/corpus/5435-crypto-hash-algorithms.ts", "tests/corpus/5436-crypto-hash-names.js", "tests/corpus/5437-crypto-hmac-algorithms.ts", "tests/corpus/5438-crypto-kdf-digests.ts", "tests/corpus/5440-crypto-hash-encodings.js", "tests/corpus/5441-crypto-hash-output-length.ts", "tests/harness/npm-static.test.ts"] },
     { "symbols": ["crypto.randomFill", "crypto.randomFillSync", "crypto.randomUUID", "crypto.randomUUIDv7"], "status": "supported", "evidence": ["tests/corpus/5442-crypto-random-values.ts", "tests/corpus/5443-crypto-random-arguments.js", "tests/corpus/1358-crypto-random.ts"] },
     { "symbols": ["crypto.createSecretKey", "crypto.generateKey", "crypto.generateKeySync", "KeyObject", "keyObject.export", "keyObject.equals", "keyObject.symmetricKeySize", "keyObject.type"], "status": "partial", "evidence": ["tests/corpus/5445-crypto-secret-key-objects.ts", "tests/corpus/5446-crypto-secret-key-errors.js"] },
+    { "symbols": ["crypto.createPrivateKey", "crypto.createPublicKey", "crypto.generateKeyPair", "crypto.generateKeyPairSync", "crypto.sign", "crypto.verify", "crypto.createSign", "crypto.createVerify", "Sign", "sign.update", "sign.sign", "Verify", "verify.update", "verify.verify", "asymmetricKeyType", "asymmetricKeyDetails"], "status": "partial", "evidence": ["tests/corpus/7080-crypto-ed25519.mjs", "tests/corpus/7082-crypto-key-objects.ts", "tests/corpus/7083-crypto-sign-verify.ts", "tests/corpus/7084-crypto-key-pairs.cjs", "tests/fixtures/node-types/keys.ts"] },
     { "symbols": ["crypto.getRandomValues"], "status": "supported", "evidence": ["tests/corpus/6204-crypto-get-random-values.ts", "tests/corpus/6205-crypto-get-random-values.js"] },
     { "symbols": ["crypto.timingSafeEqual"], "status": "supported", "evidence": ["tests/corpus/5444-crypto-timing-safe-equal.js", "tests/corpus/2890-crypto-static-utility.ts"] },
     { "symbols": ["crypto.randomInt"], "status": "partial", "evidence": ["tests/corpus/5442-crypto-random-values.ts", "tests/corpus/2890-crypto-static-utility.ts"] },

packages/cli-darwin-arm64/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/cli-darwin-arm64",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Native scriptc compiler for darwin-arm64",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli-darwin-x64/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/cli-darwin-x64",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Native scriptc compiler for darwin-x64",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli-linux-arm64-gnu/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/cli-linux-arm64-gnu",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Native scriptc compiler for linux-arm64-gnu",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli-linux-arm64-musl/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/cli-linux-arm64-musl",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Native scriptc compiler for linux-arm64-musl",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli-linux-x64-gnu/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/cli-linux-x64-gnu",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Native scriptc compiler for linux-x64-gnu",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli-linux-x64-musl/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/cli-linux-x64-musl",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Native scriptc compiler for linux-x64-musl",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli-win32-x64-msvc/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/cli-win32-x64-msvc",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Native scriptc compiler for win32-x64-msvc",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "scriptc",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Compile ordinary TypeScript and JavaScript to small, fast native executables and WebAssembly modules that run without Node.js",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",

packages/cli/test/executable-cache.test.ts

@@ -1,12 +1,13 @@
 import { execFile } from "node:child_process";
 import { createRequire } from "node:module";
-import { chmod, mkdir, mkdtemp, readFile, rm, stat, writeFile } from "node:fs/promises";
+import { chmod, mkdir, mkdtemp, readdir, readFile, rm, stat, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { delimiter, dirname, join } from "node:path";
 import { promisify } from "node:util";
 import { expect, test } from "vitest";
 import { precompiledRuntimePackTarget } from "../../compiler/src/startup-cache.js";
 import { platformLinkerSupportsPersistentCache } from "../../compiler/src/backend/linker.js";
+import { toolchainEnvironmentCachePolicy } from "../../compiler/src/backend/toolchain-environment.js";
 
 const execFileAsync = promisify(execFile);
 const require = createRequire(import.meta.url);
@@ -102,6 +103,59 @@ test("exact executable repeats skip lowering while edits and damaged outputs sta
   }
 }, 120_000);
 
+// Sanitize builds compile the LLVM text with the C driver rather than linking a precompiled
+// runtime pack, and that route's native cache proof records the output directory.
+test.skipIf(process.platform === "win32")(
+  "sanitize builds compile uncached and keep the executable on unchanged repeats",
+  async () => {
+    const dir = await mkdtemp(join(tmpdir(), "scriptc-cli-executable-sanitize-"));
+    const cacheRoot = join(dir, "cache");
+    const entry = join(dir, "main.ts");
+    const outPath = join(dir, "program");
+    const build = async (env: NodeJS.ProcessEnv = {}): Promise<{ stderr: string }> => {
+      const { stderr } = await execFileAsync(
+        process.execPath,
+        ["--import", tsxLoader, cliEntry, "build", entry, "--sanitize", "-o", outPath],
+        {
+          env: { ...process.env, SCRIPTC_CACHE_DIR: cacheRoot, SCRIPTC_TIMING: "1", ...env },
+          maxBuffer: 4 * 1024 * 1024,
+        },
+      );
+      return { stderr };
+    };
+    const run = async (): Promise<string> =>
+      (await execFileAsync(outPath, [], { maxBuffer: 1024 * 1024 })).stdout;
+    try {
+      await mkdir(cacheRoot, { mode: 0o700 });
+      await writeFile(entry, 'console.log("sanitized");\n');
+
+      // With the native cache off, clang compiles the build's private copy of the LLVM text.
+      await build({ SCRIPTC_NO_CACHE: "1" });
+      expect(await run()).toBe("sanitized\n");
+
+      expect((await build()).stderr).toContain("scriptc lowering");
+      expect(await run()).toBe("sanitized\n");
+      const built = await stat(outPath);
+      const tuTime = (await stat(join(dir, "main.ll"))).mtimeMs;
+
+      // The output directory does not change after the native cache proof is recorded, so an
+      // unchanged repeat keeps the executable instead of linking it again.
+      expect((await build()).stderr).not.toContain("scriptc lowering");
+      if (toolchainEnvironmentCachePolicy(process.env).completeArtifacts) {
+        const repeated = await stat(outPath);
+        expect(repeated.ino).toBe(built.ino);
+        expect(repeated.mtimeMs).toBe(built.mtimeMs);
+      }
+      expect(await run()).toBe("sanitized\n");
+      expect((await stat(join(dir, "main.ll"))).mtimeMs).toBe(tuTime);
+      expect((await readdir(dir)).sort()).toEqual(["cache", "main.ll", "main.ts", "program"]);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  },
+  240_000,
+);
+
 test.skipIf(process.platform === "win32")(
   "an executable appearing earlier on unchanged PATH invalidates the early binary",
   async () => {

packages/cli/test/native-link-info.test.ts

@@ -72,7 +72,7 @@ describe.runIf(supported)("macOS arm64 native link info", () => {
         minimum_os: "14.0",
       },
       program: { object, entry_symbol: "main" },
-      runtime_abi: { version: 25, marker: "scr_runtime_abi_v25" },
+      runtime_abi: { version: 27, marker: "scr_runtime_abi_v27" },
       runtime_pack: {
         kind: "precompiled",
         package: "@scriptc/runtime-darwin-arm64",
@@ -165,6 +165,6 @@ describe.runIf(supported)("macOS arm64 native link info", () => {
       () => null,
       (failure: { stderr?: string }) => failure,
     );
-    expect(error?.stderr).toContain("scr_runtime_abi_v25");
+    expect(error?.stderr).toContain("scr_runtime_abi_v27");
   });
 });

packages/compiler/ambient/scriptc-node-fallback.d.ts

@@ -544,15 +544,17 @@ declare var DOMException: {
   readonly prototype: DOMException;
 };
 
-/* WebCrypto's secret-key slice (scr_webcrypto.c): crypto.subtle's
- * importKey, generateKey and exportKey for HMAC and AES keys (importKey
- * also for PBKDF2 and HKDF keys), AES-GCM/CBC/CTR encrypt and decrypt,
- * PBKDF2 and HKDF deriveBits and deriveKey, HMAC sign/verify and the SHA-1/SHA-2 digests, typed as
- * exactly that surface (the declarations mirror @types/node's webcrypto
- * shapes), plus the global's randomUUID and getRandomValues. Every other
- * SubtleCrypto method and crypto member is absent, so a use is an honest
- * type error. CryptoKey values are native handles whose four members read
- * through the handle. */
+/* WebCrypto (scr_webcrypto.c): crypto.subtle's importKey, generateKey and
+ * exportKey for HMAC and AES keys (importKey also for PBKDF2 and HKDF
+ * keys), AES-GCM/CBC/CTR encrypt and decrypt, wrapKey and unwrapKey of
+ * secret keys (AES-KW or those ciphers), PBKDF2 and HKDF deriveBits and
+ * deriveKey, HMAC sign/verify, generateKey, importKey, exportKey, sign
+ * and verify for ECDSA, Ed25519, RSASSA-PKCS1-v1_5 and RSA-PSS, and the
+ * SHA-1/SHA-2 digests, typed as exactly that surface (the declarations
+ * mirror @types/node's webcrypto shapes), plus the global's randomUUID and
+ * getRandomValues. Every other SubtleCrypto method and crypto member is
+ * absent, so a use is an honest type error. CryptoKey values are native
+ * handles whose four members read through the handle. */
 declare var crypto: Crypto;
 /* The Crypto and SubtleCrypto constructors (feature probes only) stay
  * `unknown`; the values keep this declaration order. */
@@ -661,6 +663,42 @@ interface JsonWebKey {
   x?: string;
   y?: string;
 }
+interface EcKeyGenParams extends Algorithm {
+  namedCurve: string;
+}
+interface EcKeyImportParams extends Algorithm {
+  namedCurve: string;
+}
+interface EcdsaParams extends Algorithm {
+  hash: HashAlgorithmIdentifier;
+}
+interface RsaHashedKeyGenParams extends Algorithm {
+  modulusLength: number;
+  publicExponent: Uint8Array;
+  hash: HashAlgorithmIdentifier;
+}
+interface RsaHashedImportParams extends Algorithm {
+  hash: HashAlgorithmIdentifier;
+}
+interface RsaPssParams extends Algorithm {
+  saltLength: number;
+}
+interface EcKeyAlgorithm extends KeyAlgorithm {
+  namedCurve: string;
+}
+interface RsaHashedKeyAlgorithm extends KeyAlgorithm {
+  modulusLength: number;
+  publicExponent: Uint8Array;
+  hash: KeyAlgorithm;
+}
+interface CryptoKeyPair {
+  privateKey: CryptoKey;
+  publicKey: CryptoKey;
+}
+/* HMAC and AES keys generate, import and export as 'raw' and 'jwk'
+ * (PBKDF2 and HKDF keys import as 'raw'); ECDSA and RSA keys generate,
+ * import and export as 'spki', 'pkcs8' and 'jwk', and ECDSA public keys as
+ * 'raw'. */
 interface SubtleCrypto {
   decrypt(
     algorithm: AesGcmParams | AesCbcParams | AesCtrParams,
@@ -687,6 +725,11 @@ interface SubtleCrypto {
   ): Promise<ArrayBuffer>;
   exportKey(format: "jwk", key: CryptoKey): Promise<JsonWebKey>;
   exportKey(format: Exclude<KeyFormat, "jwk">, key: CryptoKey): Promise<ArrayBuffer>;
+  generateKey(
+    algorithm: EcKeyGenParams | RsaHashedKeyGenParams | "Ed25519" | { name: "Ed25519" },
+    extractable: boolean,
+    keyUsages: readonly KeyUsage[],
+  ): Promise<CryptoKeyPair>;
   generateKey(
     algorithm: AesKeyGenParams | HmacKeyGenParams,
     extractable: boolean,
@@ -695,24 +738,43 @@ interface SubtleCrypto {
   importKey(
     format: "jwk",
     keyData: JsonWebKey,
-    algorithm: AlgorithmIdentifier | HmacImportParams,
+    algorithm: AlgorithmIdentifier | HmacImportParams | EcKeyImportParams | RsaHashedImportParams,
     extractable: boolean,
     keyUsages: readonly KeyUsage[],
   ): Promise<CryptoKey>;
   importKey(
     format: Exclude<KeyFormat, "jwk">,
     keyData: BufferSource,
-    algorithm: AlgorithmIdentifier | HmacImportParams,
+    algorithm: AlgorithmIdentifier | HmacImportParams | EcKeyImportParams | RsaHashedImportParams,
+    extractable: boolean,
+    keyUsages: readonly KeyUsage[],
+  ): Promise<CryptoKey>;
+  sign(
+    algorithm: AlgorithmIdentifier | EcdsaParams | RsaPssParams,
+    key: CryptoKey,
+    data: BufferSource,
+  ): Promise<ArrayBuffer>;
+  unwrapKey(
+    format: KeyFormat,
+    wrappedKey: BufferSource,
+    unwrappingKey: CryptoKey,
+    unwrapAlgorithm: AlgorithmIdentifier | AesGcmParams | AesCbcParams | AesCtrParams,
+    unwrappedKeyAlgorithm: AlgorithmIdentifier | HmacImportParams,
     extractable: boolean,
     keyUsages: readonly KeyUsage[],
   ): Promise<CryptoKey>;
-  sign(algorithm: AlgorithmIdentifier, key: CryptoKey, data: BufferSource): Promise<ArrayBuffer>;
   verify(
-    algorithm: AlgorithmIdentifier,
+    algorithm: AlgorithmIdentifier | EcdsaParams | RsaPssParams,
     key: CryptoKey,
     signature: BufferSource,
     data: BufferSource,
   ): Promise<boolean>;
+  wrapKey(
+    format: KeyFormat,
+    key: CryptoKey,
+    wrappingKey: CryptoKey,
+    wrapAlgorithm: AlgorithmIdentifier | AesGcmParams | AesCbcParams | AesCtrParams,
+  ): Promise<ArrayBuffer>;
 }
 interface Crypto {
   readonly subtle: SubtleCrypto;
@@ -2773,8 +2835,20 @@ declare module "crypto" {
   import { Transform } from "stream";
   export type KeyObjectType = "secret" | "public" | "private";
   export interface JsonWebKey {
-    kty?: string;
+    crv?: string;
+    d?: string;
+    dp?: string;
+    dq?: string;
+    e?: string;
     k?: string;
+    kty?: string;
+    n?: string;
+    p?: string;
+    q?: string;
+    qi?: string;
+    x?: string;
+    y?: string;
+    [key: string]: unknown;
   }
   export interface JwkKeyExportOptions {
     format: "jwk";
@@ -2782,16 +2856,183 @@ declare module "crypto" {
   export interface KeyExportOptions {
     format?: "buffer" | undefined;
   }
-  /** Secret keys only; the asymmetric key types are not available. */
+  export type KeyFormat = "pem" | "der" | "jwk";
+  export interface AsymmetricKeyExportOptions<T extends KeyFormat> {
+    type: "pkcs1" | "spki" | "pkcs8" | "sec1";
+    format: T;
+  }
+  export interface AsymmetricKeyDetails {
+    modulusLength?: number;
+    publicExponent?: bigint;
+    namedCurve?: string;
+  }
+  /* Secret keys, and RSA and EC private and public keys. */
   export class KeyObject {
     private constructor();
     type: KeyObjectType;
     symmetricKeySize?: number;
     asymmetricKeyType?: string;
+    asymmetricKeyDetails?: AsymmetricKeyDetails;
+    export(options: AsymmetricKeyExportOptions<"pem">): string | Buffer;
+    export(options: AsymmetricKeyExportOptions<"der">): Buffer;
     export(options?: KeyExportOptions): Buffer;
     export(options: JwkKeyExportOptions): JsonWebKey;
     equals(otherKeyObject: KeyObject): boolean;
   }
+  export interface PrivateKeyInput {
+    key: string | Buffer;
+    format?: "pem" | "der" | undefined;
+    type?: "pkcs1" | "pkcs8" | "sec1" | undefined;
+    encoding?: string | undefined;
+  }
+  export interface PublicKeyInput {
+    key: string | Buffer;
+    format?: "pem" | "der" | undefined;
+    type?: "pkcs1" | "spki" | undefined;
+    encoding?: string | undefined;
+  }
+  export interface JsonWebKeyInput {
+    key: JsonWebKey;
+    format: "jwk";
+  }
+  export function createPrivateKey(
+    key: PrivateKeyInput | string | Buffer | JsonWebKeyInput,
+  ): KeyObject;
+  export function createPublicKey(
+    key: PublicKeyInput | string | Buffer | KeyObject | JsonWebKeyInput,
+  ): KeyObject;
+  export interface KeyPairKeyObjectResult {
+    publicKey: KeyObject;
+    privateKey: KeyObject;
+  }
+  export interface KeyPairSyncResult<T1 extends string | Buffer, T2 extends string | Buffer> {
+    publicKey: T1;
+    privateKey: T2;
+  }
+  export interface RSAKeyPairKeyObjectOptions {
+    modulusLength: number;
+    publicExponent?: number | undefined;
+  }
+  export interface ECKeyPairKeyObjectOptions {
+    namedCurve: string;
+  }
+  export interface RSAKeyPairOptions<PubF extends KeyFormat, PrivF extends KeyFormat> {
+    modulusLength: number;
+    publicExponent?: number | undefined;
+    publicKeyEncoding: { type: "pkcs1" | "spki"; format: PubF };
+    privateKeyEncoding: { type: "pkcs1" | "pkcs8"; format: PrivF };
+  }
+  export interface ECKeyPairOptions<PubF extends KeyFormat, PrivF extends KeyFormat> {
+    namedCurve: string;
+    publicKeyEncoding: { type: "pkcs1" | "spki"; format: PubF };
+    privateKeyEncoding: { type: "sec1" | "pkcs8"; format: PrivF };
+  }
+  export function generateKeyPairSync(
+    type: "rsa",
+    options: RSAKeyPairOptions<"pem", "pem">,
+  ): KeyPairSyncResult<string, string>;
+  export function generateKeyPairSync(
+    type: "rsa",
+    options: RSAKeyPairOptions<"der", "der">,
+  ): KeyPairSyncResult<Buffer, Buffer>;
+  export function generateKeyPairSync(
+    type: "rsa",
+    options: RSAKeyPairKeyObjectOptions,
+  ): KeyPairKeyObjectResult;
+  export function generateKeyPairSync(
+    type: "ec",
+    options: ECKeyPairOptions<"pem", "pem">,
+  ): KeyPairSyncResult<string, string>;
+  export function generateKeyPairSync(
+    type: "ec",
+    options: ECKeyPairOptions<"der", "der">,
+  ): KeyPairSyncResult<Buffer, Buffer>;
+  export function generateKeyPairSync(
+    type: "ec",
+    options: ECKeyPairKeyObjectOptions,
+  ): KeyPairKeyObjectResult;
+  export interface ED25519KeyPairOptions<PubF extends KeyFormat, PrivF extends KeyFormat> {
+    publicKeyEncoding: { type: "spki"; format: PubF };
+    privateKeyEncoding: { type: "pkcs8"; format: PrivF };
+  }
+  export function generateKeyPairSync(
+    type: "ed25519",
+    options: ED25519KeyPairOptions<"pem", "pem">,
+  ): KeyPairSyncResult<string, string>;
+  export function generateKeyPairSync(
+    type: "ed25519",
+    options: ED25519KeyPairOptions<"der", "der">,
+  ): KeyPairSyncResult<Buffer, Buffer>;
+  export function generateKeyPairSync(type: "ed25519", options?: {}): KeyPairKeyObjectResult;
+  export function generateKeyPair(
+    type: "ed25519",
+    options: {} | undefined,
+    callback: (err: Error | null, publicKey: KeyObject, privateKey: KeyObject) => void,
+  ): void;
+  export function generateKeyPair(
+    type: "rsa",
+    options: RSAKeyPairKeyObjectOptions,
+    callback: (err: Error | null, publicKey: KeyObject, privateKey: KeyObject) => void,
+  ): void;
+  export function generateKeyPair(
+    type: "ec",
+    options: ECKeyPairKeyObjectOptions,
+    callback: (err: Error | null, publicKey: KeyObject, privateKey: KeyObject) => void,
+  ): void;
+  export interface SigningOptions {
+    padding?: number | undefined;
+    saltLength?: number | undefined;
+    dsaEncoding?: "der" | "ieee-p1363" | undefined;
+  }
+  export interface SignPrivateKeyInput extends PrivateKeyInput, SigningOptions {}
+  export interface SignKeyObjectInput extends SigningOptions {
+    key: KeyObject;
+  }
+  export interface VerifyPublicKeyInput extends PublicKeyInput, SigningOptions {}
+  export interface VerifyKeyObjectInput extends SigningOptions {
+    key: KeyObject;
+  }
+  export function sign(
+    algorithm: string | null | undefined,
+    data: ArrayBufferView,
+    key: KeyObject | string | Buffer | SignKeyObjectInput | SignPrivateKeyInput,
+  ): Buffer;
+  export function verify(
+    algorithm: string | null | undefined,
+    data: ArrayBufferView,
+    key: KeyObject | string | Buffer | VerifyKeyObjectInput | VerifyPublicKeyInput,
+    signature: ArrayBufferView,
+  ): boolean;
+  /* Sign and Verify accumulate update() data; they are not usable as
+   * writable streams. */
+  export class Sign {
+    private constructor();
+    update(data: string | ArrayBufferView): this;
+    update(data: string, inputEncoding: Encoding): this;
+    sign(
+      privateKey: KeyObject | string | Buffer | SignKeyObjectInput | SignPrivateKeyInput,
+    ): Buffer;
+    sign(
+      privateKey: KeyObject | string | Buffer | SignKeyObjectInput | SignPrivateKeyInput,
+      outputFormat: BinaryToTextEncoding,
+    ): string;
+  }
+  export class Verify {
+    private constructor();
+    update(data: string | ArrayBufferView): this;
+    update(data: string, inputEncoding: Encoding): this;
+    verify(
+      object: KeyObject | string | Buffer | VerifyKeyObjectInput | VerifyPublicKeyInput,
+      signature: ArrayBufferView,
+    ): boolean;
+    verify(
+      object: KeyObject | string | Buffer | VerifyKeyObjectInput | VerifyPublicKeyInput,
+      signature: string,
+      signatureEncoding?: BinaryToTextEncoding,
+    ): boolean;
+  }
+  export function createSign(algorithm: string): Sign;
+  export function createVerify(algorithm: string): Verify;
   export function createSecretKey(key: ArrayBufferView | ArrayBufferLike): KeyObject;
   export function createSecretKey(key: string, encoding: BufferEncoding): KeyObject;
   export function generateKeySync(type: "hmac" | "aes", options: { length: number }): KeyObject;
@@ -2930,7 +3171,8 @@ declare module "crypto" {
     callback: (error: Error | null, buffer: Buffer) => void,
   ): void;
   export type BinaryLike = string | ArrayBuffer | ArrayBufferView;
-  /* Cipheriv/Decipheriv: aes-128/192/256 in cbc, ctr, and gcm modes and
+  /* Cipheriv/Decipheriv: aes-128/192/256 in cbc, ctr, gcm, ecb, cfb, cfb8,
+   * cfb1, and ofb modes, des-ede3 and des-ede, chacha20, and
    * chacha20-poly1305. Both are Transforms: written chunks go through
    * update(), and the end pushes final(). */
   export type CipherGCMTypes = "aes-128-gcm" | "aes-192-gcm" | "aes-256-gcm";
@@ -3048,6 +3290,123 @@ declare module "crypto" {
     setPrivateKey(privateKey: string, encoding: BinaryToTextEncoding): void;
   }
   export function createECDH(curveName: string): ECDH;
+  export class DiffieHellman {
+    private constructor();
+    generateKeys(): Buffer;
+    generateKeys(encoding: BinaryToTextEncoding): string;
+    computeSecret(
+      otherPublicKey: ArrayBufferView,
+      inputEncoding?: null,
+      outputEncoding?: null,
+    ): Buffer;
+    computeSecret(
+      otherPublicKey: string,
+      inputEncoding: BinaryToTextEncoding,
+      outputEncoding?: null,
+    ): Buffer;
+    computeSecret(
+      otherPublicKey: ArrayBufferView,
+      inputEncoding: null,
+      outputEncoding: BinaryToTextEncoding,
+    ): string;
+    computeSecret(
+      otherPublicKey: string,
+      inputEncoding: BinaryToTextEncoding,
+      outputEncoding: BinaryToTextEncoding,
+    ): string;
+    getPrime(): Buffer;
+    getPrime(encoding: BinaryToTextEncoding): string;
+    getGenerator(): Buffer;
+    getGenerator(encoding: BinaryToTextEncoding): string;
+    getPublicKey(): Buffer;
+    getPublicKey(encoding: BinaryToTextEncoding): string;
+    getPrivateKey(): Buffer;
+    getPrivateKey(encoding: BinaryToTextEncoding): string;
+    setPublicKey(publicKey: ArrayBufferView): void;
+    setPublicKey(publicKey: string, encoding: BufferEncoding): void;
+    setPrivateKey(privateKey: ArrayBufferView): void;
+    setPrivateKey(privateKey: string, encoding: BufferEncoding): void;
+    verifyError: number;
+  }
+  export type DiffieHellmanGroup = Omit<DiffieHellman, "setPublicKey" | "setPrivateKey">;
+  export function createDiffieHellman(primeLength: number, generator?: number): DiffieHellman;
+  export function createDiffieHellman(
+    prime: ArrayBuffer | ArrayBufferView,
+    generator?: number | ArrayBuffer | ArrayBufferView,
+  ): DiffieHellman;
+  export function createDiffieHellman(
+    prime: ArrayBuffer | ArrayBufferView,
+    generator: string,
+    generatorEncoding: BinaryToTextEncoding,
+  ): DiffieHellman;
+  export function createDiffieHellman(
+    prime: string,
+    primeEncoding: BinaryToTextEncoding,
+    generator?: number | ArrayBuffer | ArrayBufferView,
+  ): DiffieHellman;
+  export function createDiffieHellman(
+    prime: string,
+    primeEncoding: BinaryToTextEncoding,
+    generator: string,
+    generatorEncoding: BinaryToTextEncoding,
+  ): DiffieHellman;
+  export function getDiffieHellman(groupName: string): DiffieHellmanGroup;
+  export function createDiffieHellmanGroup(name: string): DiffieHellmanGroup;
+  export type LargeNumberLike = ArrayBufferView | SharedArrayBuffer | ArrayBuffer | bigint;
+  export interface GeneratePrimeOptions {
+    add?: LargeNumberLike | undefined;
+    rem?: LargeNumberLike | undefined;
+    safe?: boolean | undefined;
+    bigint?: boolean | undefined;
+  }
+  export interface GeneratePrimeOptionsBigInt extends GeneratePrimeOptions {
+    bigint: true;
+  }
+  export interface GeneratePrimeOptionsArrayBuffer extends GeneratePrimeOptions {
+    bigint?: false | undefined;
+  }
+  export function generatePrime(
+    size: number,
+    callback: (err: Error | null, prime: ArrayBuffer) => void,
+  ): void;
+  export function generatePrime(
+    size: number,
+    options: GeneratePrimeOptionsBigInt,
+    callback: (err: Error | null, prime: bigint) => void,
+  ): void;
+  export function generatePrime(
+    size: number,
+    options: GeneratePrimeOptionsArrayBuffer,
+    callback: (err: Error | null, prime: ArrayBuffer) => void,
+  ): void;
+  export function generatePrime(
+    size: number,
+    options: GeneratePrimeOptions,
+    callback: (err: Error | null, prime: ArrayBuffer | bigint) => void,
+  ): void;
+  export function generatePrimeSync(size: number): ArrayBuffer;
+  export function generatePrimeSync(size: number, options: GeneratePrimeOptionsBigInt): bigint;
+  export function generatePrimeSync(
+    size: number,
+    options: GeneratePrimeOptionsArrayBuffer,
+  ): ArrayBuffer;
+  export function generatePrimeSync(
+    size: number,
+    options: GeneratePrimeOptions,
+  ): ArrayBuffer | bigint;
+  export interface CheckPrimeOptions {
+    checks?: number | undefined;
+  }
+  export function checkPrime(
+    value: LargeNumberLike,
+    callback: (err: Error | null, result: boolean) => void,
+  ): void;
+  export function checkPrime(
+    value: LargeNumberLike,
+    options: CheckPrimeOptions,
+    callback: (err: Error | null, result: boolean) => void,
+  ): void;
+  export function checkPrimeSync(candidate: LargeNumberLike, options?: CheckPrimeOptions): boolean;
   export interface ScryptOptions {
     N?: number;
     r?: number;
@@ -4858,8 +5217,8 @@ declare module "net" {
      * unshift — read answers exactly n buffered bytes or null. */
     read(size?: number): Buffer | null;
     unshift(chunk: Uint8Array): void;
-    /* secureConnect/session are TLS-socket events declared on the shared
-     * socket surface (the lowering collapses TLSSocket onto this kind):
+    /* secureConnect/secure/session are TLS-socket events declared on the
+     * shared socket surface (the lowering collapses TLSSocket onto this kind):
      * the runtime gates on the transport, so a plain socket's
      * registration never fires — Node's exact split. 'session' fires
      * once with the serialized session (the received-ticket event). */
@@ -4867,7 +5226,15 @@ declare module "net" {
     /* After setEncoding the chunk is a string. */
     on(event: "data", listener: (chunk: string) => void): void;
     on(
-      event: "end" | "connect" | "ready" | "timeout" | "readable" | "finish" | "secureConnect",
+      event:
+        | "end"
+        | "connect"
+        | "ready"
+        | "timeout"
+        | "readable"
+        | "finish"
+        | "secureConnect"
+        | "secure",
       listener: () => void,
     ): void;
     on(event: "close", listener: (hadError: boolean) => void): void;
@@ -4883,7 +5250,15 @@ declare module "net" {
     /* After setEncoding the chunk is a string. */
     addListener(event: "data", listener: (chunk: string) => void): void;
     addListener(
-      event: "end" | "connect" | "ready" | "timeout" | "readable" | "finish" | "secureConnect",
+      event:
+        | "end"
+        | "connect"
+        | "ready"
+        | "timeout"
+        | "readable"
+        | "finish"
+        | "secureConnect"
+        | "secure",
       listener: () => void,
     ): void;
     addListener(event: "close", listener: (hadError: boolean) => void): void;
@@ -4898,7 +5273,15 @@ declare module "net" {
     /* After setEncoding the chunk is a string. */
     once(event: "data", listener: (chunk: string) => void): void;
     once(
-      event: "end" | "connect" | "ready" | "timeout" | "readable" | "finish" | "secureConnect",
+      event:
+        | "end"
+        | "connect"
+        | "ready"
+        | "timeout"
+        | "readable"
+        | "finish"
+        | "secureConnect"
+        | "secure",
       listener: () => void,
     ): void;
     once(event: "close", listener: (hadError: boolean) => void): void;
@@ -4949,9 +5332,10 @@ declare module "net" {
     on(event: "timeout", listener: (socket: Socket) => void): void;
     on(event: "error", listener: (err: Error) => void): void;
     /* The WebSocket handover: fires INSTEAD of 'request' for
-     * Connection: upgrade requests, with the raw socket + head bytes. */
+     * Connection: upgrade requests, with the raw socket + head bytes;
+     * 'connect' is its twin for CONNECT requests (HTTP tunneling). */
     on(
-      event: "upgrade",
+      event: "upgrade" | "connect",
       listener: (req: import("http").IncomingMessage, socket: Socket, head: Buffer) => void,
     ): void;
     /* http.createServer(handler)'s event twin (a no-parser net server
@@ -4967,7 +5351,7 @@ declare module "net" {
     addListener(event: "timeout", listener: (socket: Socket) => void): void;
     addListener(event: "error", listener: (err: Error) => void): void;
     addListener(
-      event: "upgrade",
+      event: "upgrade" | "connect",
       listener: (req: import("http").IncomingMessage, socket: Socket, head: Buffer) => void,
     ): void;
     addListener(
@@ -4980,7 +5364,7 @@ declare module "net" {
     once(event: "timeout", listener: (socket: Socket) => void): void;
     once(event: "error", listener: (err: Error) => void): void;
     once(
-      event: "upgrade",
+      event: "upgrade" | "connect",
       listener: (req: import("http").IncomingMessage, socket: Socket, head: Buffer) => void,
     ): void;
     once(
@@ -5451,6 +5835,7 @@ declare module "tls" {
    * split — authorizationError is the verify-failure CODE STRING
    * (DEPTH_ZERO_SELF_SIGNED_CERT, ...), or null. */
   export interface TLSSocket extends Socket {
+    readonly encrypted: true;
     authorized: boolean;
     authorizationError: string | null;
     /* null before the handshake, then the negotiated protocol or false */
@@ -5462,6 +5847,21 @@ declare module "tls" {
     /* whether the handshake resumed a cached session */
     isSessionReused(): boolean;
   }
+  /** new tls.TLSSocket(socket, options): the server-mode wrap of an open
+   * socket (a server connection or an http CONNECT socket). The options
+   * record reads at runtime; isServer, cert, key, secureContext,
+   * ALPNProtocols, minVersion and maxVersion are implemented. */
+  export interface TLSSocketOptions {
+    isServer?: boolean;
+    cert?: string | Uint8Array;
+    key?: string | Uint8Array;
+    secureContext?: SecureContext;
+    ALPNProtocols?: string[] | Uint8Array;
+    minVersion?: string;
+    maxVersion?: string;
+    [option: string]: unknown;
+  }
+  export const TLSSocket: new (socket: Socket, options: TLSSocketOptions) => TLSSocket;
   export interface CipherNameAndProtocol {
     name: string;
     standardName: string;
@@ -5470,12 +5870,14 @@ declare module "tls" {
   export const DEFAULT_MIN_VERSION: string;
   export const DEFAULT_MAX_VERSION: string;
   /** tls.connect options — the RUNTIME options record (members read at
-   * runtime; port/host/rejectUnauthorized/ca/servername are the
+   * runtime; port/host/socket/rejectUnauthorized/ca/servername are the
    * honestly-implemented set, every other documented member throws the
    * runtime fence — the options-record stance's divergence-66 shape). */
   export interface ConnectionOptions {
     port?: number;
     host?: string;
+    /* an open socket to run the client handshake over */
+    socket?: Socket;
     rejectUnauthorized?: boolean;
     ca?: string | Uint8Array | ReadonlyArray<string | Uint8Array>;
     servername?: string;
@@ -6710,11 +7112,10 @@ declare module "node:events" {
  * write(chunk, enc, cb) {} })`, Duplex/Transform/PassThrough, push/read,
  * flowing vs paused, write/end backpressure + 'drain', pipe/unpipe, and
  * destroy — with Node's event orderings. Chunks are BYTES (Buffer), with
- * utf8 strings converted at push/write like Node; objectMode and
- * setEncoding are declared so uses fence at their sites with their own
- * words. `class My extends Readable` (the _read override form) is a
- * separate feature and fences at the class declaration. The runtime-fired
- * events carry per-class FORCED argument tuples ('data' is one Buffer,
+ * strings converted at push/write like Node, and any value on an
+ * object-mode side (objectMode, readableObjectMode, writableObjectMode —
+ * the object-mode constructor overloads come first). The runtime-fired
+ * events carry per-class FORCED argument tuples ('data' is one chunk,
  * 'error' one Error, 'pipe'/'unpipe' one Readable, the rest empty) — the
  * overloads below hand tsc the same contract so unannotated listener
  * parameters contextually type in .js sources. */
@@ -6820,6 +7221,51 @@ declare module "stream" {
     signal?: AbortSignal;
   }
 
+  /* Object-mode options (objectMode: true, or a Duplex's or Transform's
+   * readableObjectMode / writableObjectMode): chunks and completion data
+   * are any values, and an object-mode write's encoding argument reaches
+   * write/transform as passed (undefined when absent, null when a
+   * callback took its place). The constructors take these before the
+   * byte-mode options, so a byte-mode stream's callbacks keep Buffer
+   * chunks. */
+  type ObjectModeEncoding = string | null | undefined;
+  type ObjectModeFlag =
+    | { objectMode: true }
+    | { readableObjectMode: true }
+    | { writableObjectMode: true };
+  interface ObjectWritableOptions extends Omit<WritableOptions, "objectMode" | "write"> {
+    objectMode: true;
+    write?(
+      this: Writable,
+      chunk: any,
+      encoding: ObjectModeEncoding,
+      callback: (error?: Error | null) => void,
+    ): void;
+  }
+  type ObjectDuplexOptions = Omit<DuplexOptions, "write"> & {
+    write?(
+      this: Duplex,
+      chunk: any,
+      encoding: ObjectModeEncoding,
+      callback: (error?: Error | null) => void,
+    ): void;
+  } & ObjectModeFlag;
+  type ObjectTransformOptions = Omit<TransformOptions, "transform" | "flush" | "write"> & {
+    transform?(
+      this: Transform,
+      chunk: any,
+      encoding: ObjectModeEncoding,
+      callback: (error?: Error | null, data?: any) => void,
+    ): void;
+    flush?(this: Transform, callback: (error?: Error | null, data?: any) => void): void;
+    write?(
+      this: Transform,
+      chunk: any,
+      encoding: ObjectModeEncoding,
+      callback: (error?: Error | null) => void,
+    ): void;
+  } & ObjectModeFlag;
+
   /* The operators' options: concurrency and highWaterMark bound map's
    * in-flight callbacks and queued results. */
   interface ArrayOptions {
@@ -6839,7 +7285,10 @@ declare module "stream" {
     [Symbol.asyncIterator](): AsyncIterableIterator<any>;
     iterator(options?: { destroyOnReturn?: boolean }): AsyncIterableIterator<any>;
     push(chunk: Buffer | string | null, encoding?: string): boolean;
+    /* An object-mode stream's values. */
+    push(chunk: any, encoding?: string): boolean;
     unshift(chunk: Buffer | string, encoding?: string): void;
+    unshift(chunk: any, encoding?: string): void;
     read(size?: number): Buffer | null;
     pause(): this;
     resume(): this;
@@ -6946,6 +7395,7 @@ declare module "stream" {
   }
 
   class Writable extends EventEmitter {
+    constructor(opts: ObjectWritableOptions);
     constructor(opts?: WritableOptions);
     /* The underscore-method surface (see Readable). */
     _write(chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
@@ -6961,9 +7411,19 @@ declare module "stream" {
       encoding: string,
       callback?: (error?: Error | null) => void,
     ): boolean;
+    /* An object-mode stream's values (the encoding argument reaches
+     * _write as passed). */
+    write(chunk: any, callback?: (error?: Error | null) => void): boolean;
+    write(
+      chunk: any,
+      encoding: ObjectModeEncoding,
+      callback?: (error?: Error | null) => void,
+    ): boolean;
     end(callback?: () => void): this;
     end(chunk: Buffer | string, callback?: () => void): this;
     end(chunk: Buffer | string, encoding: string, callback?: () => void): this;
+    end(chunk: any, callback?: () => void): this;
+    end(chunk: any, encoding: ObjectModeEncoding, callback?: () => void): this;
     cork(): void;
     uncork(): void;
     setDefaultEncoding(encoding: string): this;
@@ -7013,6 +7473,7 @@ declare module "stream" {
    * mirrors @types/node: extends Readable, the writable half declared
    * again. The lowering treats both halves as first-class. */
   class Duplex extends Readable {
+    constructor(opts: ObjectDuplexOptions);
     constructor(opts?: DuplexOptions);
     /* The underscore-method surface (see Readable). */
     _write(chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
@@ -7027,9 +7488,19 @@ declare module "stream" {
       encoding: string,
       callback?: (error?: Error | null) => void,
     ): boolean;
+    /* An object-mode stream's values (the encoding argument reaches
+     * _write as passed). */
+    write(chunk: any, callback?: (error?: Error | null) => void): boolean;
+    write(
+      chunk: any,
+      encoding: ObjectModeEncoding,
+      callback?: (error?: Error | null) => void,
+    ): boolean;
     end(callback?: () => void): this;
     end(chunk: Buffer | string, callback?: () => void): this;
     end(chunk: Buffer | string, encoding: string, callback?: () => void): this;
+    end(chunk: any, callback?: () => void): this;
+    end(chunk: any, encoding: ObjectModeEncoding, callback?: () => void): this;
     cork(): void;
     uncork(): void;
     setDefaultEncoding(encoding: string): this;
@@ -7101,16 +7572,18 @@ declare module "stream" {
   }
 
   class Transform extends Duplex {
+    constructor(opts: ObjectTransformOptions);
     constructor(opts?: TransformOptions);
     /* The underscore-method surface (see Readable). */
     _transform(
       chunk: any,
       encoding: string,
-      callback: (error?: Error | null, data?: Buffer | string) => void,
+      callback: (error?: Error | null, data?: any) => void,
     ): void;
-    _flush(callback: (error?: Error | null, data?: Buffer | string) => void): void;
+    _flush(callback: (error?: Error | null, data?: any) => void): void;
   }
   class PassThrough extends Transform {
+    constructor(opts: ObjectTransformOptions);
     constructor(opts?: TransformOptions);
   }
 

packages/compiler/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scriptc/compiler",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "The scriptc compiler — TypeScript/JavaScript frontend, typed IR, LLVM backend",
   "license": "Apache-2.0",
   "homepage": "https://scriptc.dev",
@@ -40,7 +40,7 @@
   },
   "dependencies": {
     "@scriptc/runtime": "workspace:*",
-    "tsc-ts": "0.0.5",
+    "tsc-ts": "0.0.7",
     "typescript": "7.0.2",
     "typescript5": "npm:typescript@5.9.3"
   },

packages/compiler/src/backend/executable-features.ts

@@ -56,6 +56,9 @@ export function executableLinkFeatures(mod: IrModule): NativeLinkFeatures {
     tlsCa: features.tlsCa,
     cipher: features.cipher,
     ecdh: features.ecdh,
+    dh: features.dh,
+    pki: features.pki,
+    ed25519: features.ed25519,
     webcrypto: features.webcrypto,
     perfLoop: features.perfLoop,
   };

packages/compiler/src/backend/library-pack.ts

@@ -60,6 +60,9 @@ export async function compilePackedLibrary(
     tls: false,
     cipher: false,
     ecdh: false,
+    dh: false,
+    pki: false,
+    ed25519: false,
     webcrypto: false,
     perfLoop: false,
     tlsCa: false,

packages/compiler/src/backend/llvm/array-search.ts

@@ -10,6 +10,8 @@
  *   SameValueZero are both pointer identity (class instances, records,
  *   arrays, maps, sets, typed arrays): 64-bit compares, four slots per
  *   branch.
+ * - sc_arr_index_of_cref, the same over the 4-byte slots of compact class
+ *   references (SCR_ELEM_CREF), against the needle's 32-bit reference.
  * - sc_arr_index_of_str, for strings: pointer identity, then the length,
  *   then the bytes. Strings of up to 16 bytes compare as two words; a short
  *   string's word is the eight bytes ending at its last byte, which start
@@ -26,10 +28,12 @@ import type { IrType } from "../../ir/ir.js";
 import { SCR_ARR_FIELD } from "./common.js";
 import { FN_ATTRS } from "./shapes.js";
 
-export type ArraySearchKind = "ptr" | "str";
+export type ArraySearchKind = "ptr" | "cref" | "str";
 
-/** The inline search for arrays of `elem`, or null for the runtime search. */
-export function arraySearchKind(elem: IrType): ArraySearchKind | null {
+/** The inline search for arrays of `elem`, or null for the runtime search.
+ * `compact`: the arrays hold compact class references (SCR_ELEM_CREF). */
+export function arraySearchKind(elem: IrType, compact: boolean): ArraySearchKind | null {
+  if (compact) return elem.kind === "object" ? "cref" : null;
   switch (elem.kind) {
     case "object":
     case "record":
@@ -46,7 +50,7 @@ export function arraySearchKind(elem: IrType): ArraySearchKind | null {
 }
 
 export function arraySearchHelperName(kind: ArraySearchKind): string {
-  return kind === "ptr" ? "sc_arr_index_of_ptr" : "sc_arr_index_of_str";
+  return `sc_arr_index_of_${kind}`;
 }
 
 /** The definitions of the helpers in `kinds`; they declare their slow paths
@@ -76,9 +80,18 @@ export function emitArraySearchHelpers(
       `  %dp = getelementptr inbounds %ScrArr, ptr %a, i32 0, i32 ${SCR_ARR_FIELD.data}`,
       `  %data = load ptr, ptr %dp`,
     );
-    if (kind === "ptr") {
+    if (kind === "ptr" || kind === "cref") {
+      // A compact reference is the address over 8 (classes.ts
+      // compactRefLoadLines).
+      const slot = kind === "ptr" ? "i64" : "i32";
       defs.push(
-        `  %needle = ptrtoint ptr %v to i64`,
+        ...(kind === "ptr"
+          ? [`  %needle = ptrtoint ptr %v to i64`]
+          : [
+              `  %vaddr = ptrtoint ptr %v to i64`,
+              `  %vref = lshr i64 %vaddr, 3`,
+              `  %needle = trunc i64 %vref to i32`,
+            ]),
         // Four slots per step with one branch, then one at a time.
         `  br label %quad`,
         `quad:`,
@@ -89,9 +102,9 @@ export function emitArraySearchHelpers(
         `quadbody:`,
         ...[0, 1, 2, 3].flatMap((k) => [
           `  %qi${k} = add ${sz} %q, ${k}`,
-          `  %qp${k} = getelementptr inbounds i64, ptr %data, ${sz} %qi${k}`,
-          `  %qs${k} = load i64, ptr %qp${k}`,
-          `  %qh${k} = icmp eq i64 %qs${k}, %needle`,
+          `  %qp${k} = getelementptr inbounds ${slot}, ptr %data, ${sz} %qi${k}`,
+          `  %qs${k} = load ${slot}, ptr %qp${k}`,
+          `  %qh${k} = icmp eq ${slot} %qs${k}, %needle`,
         ]),
         `  %qh01 = or i1 %qh0, %qh1`,
         `  %qh23 = or i1 %qh2, %qh3`,
@@ -107,9 +120,9 @@ export function emitArraySearchHelpers(
         `  %done = icmp eq ${sz} %i, %len`,
         `  br i1 %done, label %miss, label %body`,
         `body:`,
-        `  %sp = getelementptr inbounds i64, ptr %data, ${sz} %i`,
-        `  %s = load i64, ptr %sp`,
-        `  %hit = icmp eq i64 %s, %needle`,
+        `  %sp = getelementptr inbounds ${slot}, ptr %data, ${sz} %i`,
+        `  %s = load ${slot}, ptr %sp`,
+        `  %hit = icmp eq ${slot} %s, %needle`,
         `  br i1 %hit, label %found, label %cont`,
       );
     } else {

packages/compiler/src/backend/llvm/blocks.ts

@@ -95,8 +95,8 @@ export class BlockBuilder {
     this.terminate(`br label %${label}`);
   }
 
-  condBr(v: string, t: string, f: string): void {
-    this.terminate(`br i1 ${v}, label %${t}, label %${f}`);
+  condBr(v: string, t: string, f: string, attachment = ""): void {
+    this.terminate(`br i1 ${v}, label %${t}, label %${f}${attachment}`);
   }
 
   /** Emit a double-indexed `for (i = 0; i < len; i++)` loop. `next` is

packages/compiler/src/backend/llvm/byte-windows.ts

@@ -43,6 +43,7 @@ export function findInitializedByteLoopBindings(
         if (stmt.init) list([stmt.init], inner);
         list(stmt.body, inner);
       }
+      if (stmt.kind === "while") entries.set(stmt, new Set(known));
       if (stmt.kind === "while" || stmt.kind === "doWhile") list(stmt.body, new Set(known));
     }
   }

packages/compiler/src/backend/llvm/bytes-loop-versions.test.ts

@@ -134,6 +134,39 @@ test("a counted loop's affine accesses get one guard and exact operand ranges",
   expect(version.ranges.get(shifted)).toEqual({ min: 1, max: Number.MAX_SAFE_INTEGER });
 });
 
+test("invariant terms without a range are tested by the guard", () => {
+  // for (let i = 0; i < n; i++) out[i] = src[k + i], with `k` a parameter
+  const shifted = bin("+", ref("k"), ref("i"));
+  const loop = counted([set(ref("out", f64s), ref("i"), get(ref("src", f64s), shifted))]);
+  const kernel = fn([loop]);
+  const version = match(kernel, loop)!;
+  expect([...version.guarded]).toEqual(["v1:k"]);
+  expect(version.affine.map((c) => c.terms.map((t) => t.key))).toEqual([[], ["v1:k"]]);
+  // In the fast copy the term has the range the guard tests.
+  expect(version.ranges.get(shifted.kind === "bin" ? shifted.left : shifted)).toEqual({
+    min: -(2 ** 32),
+    max: 2 ** 32,
+  });
+  const mod: IrModule = {
+    irVersion: 17,
+    sourceFile: loc.file,
+    entry: "__main",
+    functions: [
+      { name: "__main", params: [], returnType: VOID, locals: [], body: [], loc },
+      kernel,
+    ],
+  };
+  const body = /^define internal [^\n]*@sc_bf_kernel[^]*?^}/m.exec(emitLlvmModule(mod))![0];
+  const guard = body.slice(0, body.search(/^bytes\.version\.(fast|slow)\d+:$/m));
+  // -2^32 <= k <= 2^32, and k is the double of its frozen integer.
+  expect(guard).toMatch(/fcmp oge double %\S+, 0xC1F0000000000000/);
+  expect(guard).toMatch(/fcmp ole double %\S+, 0x41F0000000000000/);
+  expect(guard).toMatch(/freeze i64/);
+  const fast = /^bytes\.version\.fast\d+:$[^]*?^bytes\.version\.done\d+:$/m.exec(body)![0];
+  expect(fast).not.toContain("bytes.index");
+  expect(body.slice(0, body.indexOf(fast))).toContain("bytes.index.invalid");
+});
+
 test("statically ranged indices compare one constant with the length", () => {
   const masked = bin("&", bin("^", ref("i"), ref("k")), num(255));
   const loop = counted([set(ref("out", f64s), num(0), get(ref("table", i32s), masked))]);
@@ -144,6 +177,11 @@ test("statically ranged indices compare one constant with the length", () => {
   ]);
   expect(version.affine).toEqual([]);
   expect(version.counted).toBeNull();
+  // A uint32 index (an array counter's range) gets no guard: no typed array
+  // in practice has 2^31 elements.
+  const wide = bin(">>>", bin("^", ref("i"), ref("k")), num(0));
+  const unbounded = counted([set(ref("out", f64s), num(0), get(ref("table", i32s), wide))]);
+  expect(match(fn([unbounded]), unbounded)!.fixed).toEqual([{ receiver: 0, end: 0 }]);
 });
 
 test("scaled counters and body temps resolve to their receiver and index", () => {
@@ -325,6 +363,63 @@ test("index temps of a version's counter are integers in the fast copy", () => {
   expect(fast).not.toContain("bytes.index");
 });
 
+test("while loop counters below a bound version their accesses", () => {
+  // while (i < n) { out[i] = src[i + 1]; i = i + 1 }
+  const step: IrStmt = { kind: "assign", localId: "i", value: bin("+", ref("i"), num(1)), loc };
+  const whileLoop = (body: IrStmt[]): IrStmt & { kind: "while" } => ({
+    kind: "while",
+    cond: { kind: "bin", op: "<", left: ref("i"), right: ref("n"), type: BOOL, loc },
+    body,
+    loc,
+  });
+  const copy = whileLoop([
+    set(ref("out", f64s), ref("i"), get(ref("src", f64s), bin("+", ref("i"), num(1)))),
+    step,
+  ]);
+  const declared = (loop: IrStmt): IrFunction =>
+    fn([{ kind: "varDecl", localId: "i", init: ref("k"), loc }, loop]);
+  const versionOf = (loop: IrStmt & { kind: "while" }): BytesLoopVersion | null => {
+    const f = declared(loop);
+    const ranges = analyzeIntegerRanges(f);
+    return matchBytesLoopVersion(loop, null, {
+      locals: new Map(f.locals.map((l) => [l.id, l])),
+      invariantGlobals: new Set(),
+      captured: new Set(),
+      ranges,
+      initialized: findInitializedByteLoopBindings(f).get(loop) ?? new Set(),
+      proven: new Set(),
+      workers: false,
+      owned: new Set(),
+    });
+  };
+  const version = versionOf(copy)!;
+  expect(version.bounds.size).toBe(2);
+  expect(version.bounded.map((c) => [version.receivers[c.receiver]!.ref, c.slack])).toEqual([
+    [ref("out", f64s), 0],
+    [ref("src", f64s), 1],
+  ]);
+  // `out[i]` needs `i` to start at 0 or above (`src[i + 1]` only at -1).
+  expect(version.counters.map((c) => [c.ref.kind === "varRef" && c.ref.localId, c.min])).toEqual([
+    ["i", 0],
+  ]);
+  // An access after the counter advances in the same pass stays checked.
+  const advanced = whileLoop([step, set(ref("out", f64s), ref("i"), num(0))]);
+  expect(versionOf(advanced)).toBeNull();
+  const mod: IrModule = {
+    irVersion: 17,
+    sourceFile: loc.file,
+    entry: "__main",
+    functions: [
+      { name: "__main", params: [], returnType: VOID, locals: [], body: [], loc },
+      declared(copy),
+    ],
+  };
+  const body = /^define internal [^\n]*@sc_bf_kernel[^]*?^}/m.exec(emitLlvmModule(mod))![0];
+  const fast = /^bytes\.version\.fast\d+:$[^]*?^bytes\.version\.done\d+:$/m.exec(body)![0];
+  expect(fast).not.toContain("bytes.index");
+  expect(body.slice(0, body.indexOf(fast))).toContain("bytes.index.invalid");
+});
+
 test("Float16Array accesses version in elements and share the element tag", () => {
   const f16s: IrType = { kind: "bytes", elem: "f16" };
   const withHalves = (body: IrStmt[]): IrFunction => {

packages/compiler/src/backend/llvm/bytes-loop-versions.ts

@@ -1,4 +1,4 @@
-import type { IrExpr, IrLocal, IrStmt } from "../../ir/ir.js";
+import { F64, type IrExpr, type IrLocal, type IrStmt } from "../../ir/ir.js";
 import type { IntegerRange, IntegerRanges } from "../../ir/integer-ranges.js";
 import type { IntegerCountedForLoop } from "../../ir/integer-loops.js";
 import type { LlvmEmitterContext } from "./expr-context.js";
@@ -7,6 +7,7 @@ import { everyExprChild, everyStmtChild } from "../../ir/traverse.js";
 import { exactInteger, widenInteger } from "./integer-values.js";
 import { emitCountedLoopLimit, emitCountedLoopSafety } from "./counted-loops.js";
 import { emitBytesHeaderLength, emitBytesSharedStorage } from "./expr-bytes.js";
+import { f64Lit } from "./common.js";
 
 type Node = IrExpr | IrStmt;
 type VarRef = IrExpr & { kind: "varRef" };
@@ -22,6 +23,24 @@ interface KeyedTerm extends Term {
   key: string;
 }
 
+/** Every access of `receiver` at a while loop counter `c + d` happens while
+ * `c < bound` (`c <= bound` when `inclusive`) holds and before the counter
+ * advances, so it is in bounds when `bound + slack <= length`. */
+interface BoundedCheck {
+  receiver: number;
+  bound: IrExpr;
+  slack: number;
+}
+
+/** A while loop counter whose entry value the guard tests: an exact
+ * integer of at least `min`. A counter that `| 0` wraps also needs every
+ * bound of its loops at most `wrapLimit`, so that it never reaches 2^31. */
+interface CounterCheck {
+  ref: VarRef;
+  min: number;
+  wrapBounds: { bound: IrExpr; limit: number }[];
+}
+
 /** Every access of `receiver` at a static index range ends below `end + 1`. */
 interface FixedCheck {
   receiver: number;
@@ -50,6 +69,12 @@ export interface BytesLoopVersion {
   ownedReceivers: number[];
   fixed: FixedCheck[];
   affine: AffineCheck[];
+  /** While loops: accesses at a counter below a loop-invariant bound. */
+  bounded: BoundedCheck[];
+  counters: CounterCheck[];
+  /** Keys of affine terms the guard tests at run time: exact integers
+   * within GUARDED_TERM. */
+  guarded: ReadonlySet<string>;
   /** The counted loop whose iteration space the affine checks cover. */
   counted: IntegerCountedForLoop | null;
   /** The guard also requires every counter value within [-bound, bound]. */
@@ -79,10 +104,13 @@ export interface BytesLoopFacts {
 }
 
 const MAX_COST = 400;
-const MAX_FIXED_END = 2 ** 32;
+const MAX_FIXED_END = 2 ** 31;
 const MAX_CHECKS = 8;
 const MAX_OFFSET = 2 ** 31;
 const SAFE = Number.MAX_SAFE_INTEGER;
+/** The range the guard requires of an invariant index term without a
+ * proven one: every index of a typed array of at most 2^32 elements. */
+const GUARDED_TERM: IntegerRange = { min: -(2 ** 32), max: 2 ** 32 };
 const INVARIANT_OPS = new Set(["+", "-", "*", "&", "|", "^", "<<", ">>", ">>>"]);
 
 /** Loop versioning for typed-array bounds. A typed array's length and data
@@ -95,7 +123,9 @@ const INVARIANT_OPS = new Set(["+", "-", "*", "&", "|", "^", "<<", ">>", ">>>"])
  *   `hi < length`, such as `table[x & 0xff]` or a constant-trip counter;
  * - an index `k * counter + invariant + c` of a counted loop needs its first
  *   and last values in bounds, such as `out[base + i]` for `i < n` or
- *   `view.getUint32(i * 4)`.
+ *   `view.getUint32(i * 4)`. An invariant without a proven integer range,
+ *   such as `base` for `const base = r * cols`, must also be an exact
+ *   integer between -2^32 and 2^32, which the guard tests.
  *
  * In worker programs, every access of a view that may be shared tests its
  * shared storage. A view's storage is also fixed at construction, so the
@@ -107,7 +137,7 @@ const INVARIANT_OPS = new Set(["+", "-", "*", "&", "|", "^", "<<", ">>", ">>>"])
  * whenever the guard fails, and keeps every out-of-bounds read, ignored
  * write and NaN-index behavior. */
 export function matchBytesLoopVersion(
-  loop: IrStmt & { kind: "for" },
+  loop: IrStmt & { kind: "for" | "while" },
   counted: IntegerCountedForLoop | null,
   facts: BytesLoopFacts,
 ): BytesLoopVersion | null {
@@ -146,10 +176,10 @@ export function matchBytesLoopVersion(
   // writes is not invariant either: `for (let i = (a = b, 0); ...)` must
   // not keep the bounds the guard proved for the old `a`.
   if (
-    (loop.init !== null && !scanStmt(loop.init)) ||
+    (loop.kind === "for" && loop.init !== null && !scanStmt(loop.init)) ||
     !loop.body.every(scanStmt) ||
     (loop.cond !== null && !scanExpr(loop.cond)) ||
-    (loop.update !== null && !scanStmt(loop.update))
+    (loop.kind === "for" && loop.update !== null && !scanStmt(loop.update))
   )
     return null;
   // A body temp stands for its initializer only when it is a constant
@@ -198,9 +228,8 @@ export function matchBytesLoopVersion(
     }
     return invariant(e.localId) ? e : null;
   };
-  // A pure integer operand evaluated again before the loop.
-  const invariantKey = (e: IrExpr): string | null => {
-    if (!facts.ranges.get(e)) return null;
+  // A pure loop-invariant number, evaluated again before the loop.
+  const pureKey = (e: IrExpr): string | null => {
     if (e.kind === "numLit") return Number.isSafeInteger(e.value) ? `n${e.value}` : null;
     if (e.kind === "varRef")
       return invariant(e.localId) ? `v${e.localId.length}:${e.localId}` : null;
@@ -210,12 +239,27 @@ export function matchBytesLoopVersion(
       e.left.type.kind === "f64" &&
       e.right.type.kind === "f64"
     ) {
-      const left = invariantKey(e.left),
-        right = invariantKey(e.right);
+      const left = pureKey(e.left),
+        right = pureKey(e.right);
       return left !== null && right !== null ? `(${e.op} ${left} ${right})` : null;
     }
     return null;
   };
+  // Invariant terms without a proven range, such as `base` in
+  // `w[base + j]` with `const base = r * cols` for a parameter `cols`. The
+  // guard tests each one: an exact integer (not -0) within GUARDED_TERM.
+  const guardedRanges = new Map<IrExpr, IntegerRange>();
+  const guardedNodes = new Map<IrExpr, string>();
+  // The key of a loop-invariant index term, with a proven range or guarded.
+  const invariantKey = (e: IrExpr): string | null => {
+    const key = pureKey(e);
+    if (key === null || facts.ranges.get(e)) return key;
+    if (e.kind === "numLit") return null;
+    guardedRanges.set(e, GUARDED_TERM);
+    guardedNodes.set(e, key);
+    return key;
+  };
+  const termRange = (e: IrExpr): IntegerRange => facts.ranges.get(e) ?? guardedRanges.get(e)!;
   interface Affine {
     /** The counter's coefficient; 0 when the value is loop-invariant. */
     counter: number;
@@ -223,9 +267,10 @@ export function matchBytesLoopVersion(
     offset: number;
   }
   // Every operand of an affine index is `counter * k + Σ terms + offset`.
-  // Invariant terms need proven ranges. Operands that involve the counter
-  // need none: the guard bounds the counter so that each of them is a safe
-  // integer, which makes the index's double arithmetic exact.
+  // Invariant terms need proven ranges or the guard's test (guarded terms).
+  // Operands that involve the counter need none: the guard bounds the
+  // counter so that each of them is a safe integer, which makes the index's
+  // double arithmetic exact.
   const shapes = new Map<IrExpr, Affine | null>();
   const affine = (e: IrExpr): Affine | null => {
     if (shapes.has(e)) return shapes.get(e)!;
@@ -309,10 +354,48 @@ export function matchBytesLoopVersion(
   };
   const termMagnitude = (terms: Term[]): number =>
     terms.reduce((sum, t) => {
-      const r = facts.ranges.get(t.expr)!;
+      const r = termRange(t.expr);
       return sum + Math.max(Math.abs(r.min), Math.abs(r.max));
     }, 0);
 
+  const whileAccesses = loop.kind === "while" ? whileCounterAccesses(loop) : null;
+  function whileCounterAccesses(loop: IrStmt & { kind: "while" }) {
+    return findWhileCounterAccesses(loop, {
+      counterLocal: (id) => {
+        const local = facts.locals.get(id);
+        return (
+          local?.type.kind === "f64" &&
+          !local.boxed &&
+          !local.tdz &&
+          !facts.captured.has(id) &&
+          facts.initialized.has(id)
+        );
+      },
+      boundKey: (e) => {
+        if (e.type.kind !== "f64") return null;
+        // The guard evaluates the bound before the loop: a typed array's
+        // length needs the binding itself, not a temp the body declares.
+        if (
+          e.kind === "bytesIntrinsic" &&
+          e.method === "length" &&
+          e.receiver.kind === "varRef" &&
+          e.receiver.type.kind === "bytes" &&
+          invariant(e.receiver.localId)
+        )
+          return `bytes-length:${e.receiver.localId}`;
+        if (
+          e.kind === "strIntrinsic" &&
+          e.method === "length" &&
+          e.args.length === 0 &&
+          e.receiver.kind === "varRef" &&
+          e.receiver.type.kind === "string" &&
+          invariant(e.receiver.localId)
+        )
+          return `string-length:${e.receiver.localId}`;
+        return pureKey(e);
+      },
+    });
+  }
   const receivers: { ref: VarRef; global: boolean }[] = [];
   const receiverIndex = new Map<string, number>();
   const fixed = new Map<number, { check: FixedCheck; nodes: Node[] }>();
@@ -332,6 +415,11 @@ export function matchBytesLoopVersion(
   // Worker programs: accesses through invariant receivers, proven or not,
   // become thread-owned when the guard finds no shared storage.
   const owned = new Map<number, Node[]>();
+  // While loops: accesses at a counter below a bound, by receiver and bound.
+  const boundedChecks = new Map<
+    string,
+    { check: BoundedCheck; nodes: { node: Node; access: WhileAccess }[] }
+  >();
   const access = (node: Node, array: IrExpr, index: IrExpr, width: number): void => {
     const ref = root(array);
     if (!ref) return;
@@ -366,11 +454,30 @@ export function matchBytesLoopVersion(
         });
       return;
     }
+    const bounded = whileAccesses?.accesses.get(node);
+    const loopCounter = bounded && whileAccesses!.counters.get(bounded.counter);
+    if (bounded && loopCounter && (!loopCounter.wraps || loopCounter.bounds !== null)) {
+      const receiver = receiverOf(ref);
+      const key = `${receiver}|${bounded.key}|${bounded.adj}`;
+      const slack = bounded.offset + width - 1 + bounded.adj;
+      const group = boundedChecks.get(key);
+      if (group) {
+        group.check.slack = Math.max(group.check.slack, slack);
+        group.nodes.push({ node, access: bounded });
+      } else
+        boundedChecks.set(key, {
+          check: { receiver, bound: bounded.bound, slack },
+          nodes: [{ node, access: bounded }],
+        });
+      return;
+    }
     const range = facts.ranges.get(index);
     if (!range) return;
     const end = range.max + width - 1;
-    // Only a length a buffer can have: an outer loop must not pay for a
-    // guard that bounds an inner loop's unbounded counter.
+    // Only an end below 2^31: an outer loop must not pay for a guard that
+    // bounds an inner loop's unbounded counter, and the counter of a loop to
+    // an array's length reaches 2^32 - 2, a length no typed array in
+    // practice has.
     if (range.min < 0 || end >= MAX_FIXED_END) return;
     const receiver = receiverOf(ref);
     const group = fixed.get(receiver);
@@ -392,6 +499,7 @@ export function matchBytesLoopVersion(
     return everyStmtChild(s, visitExpr, visitStmt);
   };
   loop.body.every(visitStmt);
+  if (loop.kind === "while") visitExpr(loop.cond);
   // Bound the counter so every counter operand stays a safe integer.
   let bound = SAFE;
   const affineGroups = [...affineChecks.values()].filter((group) => {
@@ -407,8 +515,18 @@ export function matchBytesLoopVersion(
   });
   const fixedKept = [...fixed.values()].slice(0, MAX_CHECKS);
   const affineKept = affineGroups.slice(0, MAX_CHECKS - fixedKept.length);
+  const boundedKept = [...boundedChecks.values()].slice(
+    0,
+    Math.max(0, MAX_CHECKS - fixedKept.length - affineKept.length),
+  );
   const ownedKept = [...owned.entries()].slice(0, MAX_CHECKS);
-  if (fixedKept.length === 0 && affineKept.length === 0 && ownedKept.length === 0) return null;
+  if (
+    fixedKept.length === 0 &&
+    affineKept.length === 0 &&
+    boundedKept.length === 0 &&
+    ownedKept.length === 0
+  )
+    return null;
   const bounds = new Set<Node>();
   const ownedNodes = new Set<Node>();
   const used = new Set<number>();
@@ -433,7 +551,7 @@ export function matchBytesLoopVersion(
       let min = Math.min(a, b) + shape.offset,
         max = Math.max(a, b) + shape.offset;
       for (const term of shape.terms) {
-        const r = facts.ranges.get(term.expr)!;
+        const r = termRange(term.expr);
         min += term.sign > 0 ? r.min : -r.max;
         max += term.sign > 0 ? r.max : -r.min;
       }
@@ -447,6 +565,45 @@ export function matchBytesLoopVersion(
         ranges.set(operand, { min: Math.max(min, known.min), max: Math.min(max, known.max) });
     }
   }
+  // Guarded terms of the kept checks, and the range the guard proves for
+  // every node of each in the fast copy.
+  const guarded = new Set<string>();
+  for (const group of affineKept)
+    for (const term of group.check.terms) if (guardedRanges.has(term.expr)) guarded.add(term.key);
+  for (const [node, key] of guardedNodes) if (guarded.has(key)) ranges.set(node, GUARDED_TERM);
+  // While loop counters of the kept checks: each entry value is an exact
+  // integer that no access offset takes below 0. In the fast copy each
+  // access's index is below its length, and its counter read at least the
+  // most negative offset.
+  const narrow = (e: IrExpr, range: IntegerRange): void => {
+    const known = ranges.get(e) ?? facts.ranges.get(e);
+    ranges.set(
+      e,
+      known ? { min: Math.max(known.min, range.min), max: Math.min(known.max, range.max) } : range,
+    );
+  };
+  const counterMins = new Map<string, number>();
+  for (const group of boundedKept) {
+    used.add(group.check.receiver);
+    for (const { node, access } of group.nodes) {
+      bounds.add(node);
+      const min = 0 - access.offset;
+      counterMins.set(access.counter, Math.max(counterMins.get(access.counter) ?? -SAFE, min));
+      narrow(access.ref, { min: -MAX_OFFSET, max: SAFE });
+      if (access.index !== access.ref) narrow(access.index, { min: 0, max: SAFE });
+    }
+  }
+  const counterChecks: CounterCheck[] = [];
+  for (const [id, min] of counterMins) {
+    const info = whileAccesses!.counters.get(id)!;
+    counterChecks.push({
+      ref: { kind: "varRef", localId: id, type: F64, loc: loop.loc },
+      min,
+      wrapBounds: info.wraps
+        ? info.bounds!.map((b) => ({ bound: b.bound, limit: 2 ** 31 - info.sum - b.adj }))
+        : [],
+    });
+  }
   // Renumber the receivers the kept checks use.
   const order = [...used].sort((a, b) => a - b);
   const renumber = new Map(order.map((old, index) => [old, index]));
@@ -470,12 +627,320 @@ export function matchBytesLoopVersion(
       minOffset: g.check.minOffset,
       maxEnd: g.check.maxEnd,
     })),
+    bounded: boundedKept.map((g) => ({
+      receiver: renumber.get(g.check.receiver)!,
+      bound: g.check.bound,
+      slack: g.check.slack,
+    })),
+    counters: counterChecks,
+    guarded,
     counted: affineKept.length > 0 ? counted : null,
     counterBound: needsBound ? bound : null,
     ranges,
   };
 }
 
+/** A typed-array access at a while loop counter: `counter + offset`, read
+ * or written while `counter < bound` (`<=` when `adj` is 1) holds. */
+interface WhileAccess {
+  counter: string;
+  /** The index, and the counter's read in it. */
+  index: IrExpr;
+  ref: IrExpr;
+  bound: IrExpr;
+  key: string;
+  adj: number;
+  offset: number;
+}
+
+interface WhileCounter {
+  /** Some increment is `c = (c + k) | 0`. */
+  wraps: boolean;
+  /** The sum of every increment literal in the loop. */
+  sum: number;
+  /** One bound from the condition of the loop and of every nested while
+   * loop that advances the counter; null when one of them has none. */
+  bounds: { bound: IrExpr; adj: number }[] | null;
+}
+
+/** `counter = counter + k`, `counter = (counter + k) | 0` or `counter++`. */
+function counterStep(s: IrStmt): { id: string; k: number; wraps: boolean } | null {
+  if (s.kind === "exprStmt" && s.expr.kind === "incDec" && s.expr.op === "+")
+    return { id: s.expr.localId, k: 1, wraps: false };
+  if (s.kind !== "assign") return null;
+  let value = s.value,
+    wraps = false;
+  if (
+    value.kind === "bin" &&
+    value.op === "|" &&
+    value.right.kind === "numLit" &&
+    value.right.value === 0 &&
+    value.left.kind === "bin"
+  ) {
+    value = value.left;
+    wraps = true;
+  }
+  if (
+    value.kind !== "bin" ||
+    value.op !== "+" ||
+    value.left.kind !== "varRef" ||
+    value.left.localId !== s.localId ||
+    value.right.kind !== "numLit" ||
+    !Number.isSafeInteger(value.right.value) ||
+    value.right.value <= 0 ||
+    value.right.value > MAX_OFFSET
+  )
+    return null;
+  return { id: s.localId, k: value.right.value, wraps };
+}
+
+/** Typed-array accesses of a while loop that happen at a counter below a
+ * loop-invariant bound. A counter is a number local that the loop changes
+ * only by positive integer increments, written as statements of the body,
+ * of its blocks and branches, or of nested while loops. The condition of
+ * the loop, an `if` or a `&&` chain that compares the counter below a bound
+ * (`while (pos < end && bytes[pos] === 32) pos++`) makes it below that
+ * bound until the next increment on the path. The counter starts at its
+ * entry value and only grows (a `| 0` increment never wraps when every
+ * bound is at most 2^31 minus the increments), so an access at `counter +
+ * d` is in bounds for the whole loop when the entry value is at least `-d`
+ * and `bound + d < length` (`+ 1` for `<=`). */
+function findWhileCounterAccesses(
+  loop: IrStmt & { kind: "while" },
+  host: {
+    counterLocal: (id: string) => boolean;
+    /** A key for a bound expression whose value the loop never changes. */
+    boundKey: (e: IrExpr) => string | null;
+  },
+): { accesses: Map<Node, WhileAccess>; counters: Map<string, WhileCounter> } {
+  const steps = new Map<string, { sum: number; wraps: boolean }>();
+  const refused = new Set<string>();
+  // Increments count only as statements of the loop's straight-line
+  // structure; any other write refuses the binding.
+  const writes = (list: readonly IrStmt[], direct: boolean): void => {
+    for (const s of list) {
+      const step = counterStep(s);
+      if (step && direct) {
+        const prior = steps.get(step.id);
+        steps.set(step.id, {
+          sum: (prior?.sum ?? 0) + step.k,
+          wraps: (prior?.wraps ?? false) || step.wraps,
+        });
+        continue;
+      }
+      if (step) refused.add(step.id);
+      const nested =
+        direct &&
+        (s.kind === "if" || s.kind === "while" || (s.kind === "block" && !s.labels?.length));
+      if (s.kind === "assign" || s.kind === "varDecl" || s.kind === "forOf") refused.add(s.localId);
+      if (s.kind === "tryCatch" && s.catchLocalId) refused.add(s.catchLocalId);
+      everyStmtChild(
+        s,
+        (e) => (exprWrites(e), true),
+        (c) => (writes([c], nested), true),
+      );
+    }
+  };
+  const exprWrites = (e: IrExpr): void => {
+    if (e.kind === "assignExpr" || e.kind === "incDec") refused.add(e.localId);
+    everyExprChild(
+      e,
+      (c) => (exprWrites(c), true),
+      (c) => (writes([c], false), true),
+    );
+  };
+  exprWrites(loop.cond);
+  writes(loop.body, true);
+  const counter = (id: string): boolean =>
+    steps.has(id) && !refused.has(id) && host.counterLocal(id);
+
+  type Fact = { bound: IrExpr; key: string; adj: number };
+  type Clean = ReadonlyMap<string, Fact>;
+  // The bounds a condition puts on counters while it holds.
+  const facts = (cond: IrExpr, into: Map<string, Fact>): void => {
+    if (cond.kind === "toBool") return facts(cond.operand, into);
+    if (cond.kind === "logical" && cond.op === "&&") {
+      facts(cond.left, into);
+      facts(cond.right, into);
+      return;
+    }
+    if (cond.kind !== "bin") return;
+    const below = cond.op === "<" || cond.op === "<=",
+      above = cond.op === ">" || cond.op === ">=";
+    const c = below ? cond.left : above ? cond.right : null,
+      bound = below ? cond.right : cond.left;
+    if (c?.kind !== "varRef" || !counter(c.localId) || into.has(c.localId)) return;
+    const key = host.boundKey(bound);
+    if (key === null) return;
+    into.set(c.localId, { bound, key, adj: cond.op === "<=" || cond.op === ">=" ? 1 : 0 });
+  };
+  // The facts that hold after either of two paths.
+  const meet = (a: Clean | null, b: Clean | null): Clean | null => {
+    if (a === null) return b;
+    if (b === null) return a;
+    const out = new Map<string, Fact>();
+    for (const [id, fact] of a) if (b.get(id) === fact) out.set(id, fact);
+    return out;
+  };
+  const withFacts = (clean: Clean, cond: IrExpr): Clean => {
+    const out = new Map(clean);
+    facts(cond, out);
+    return out;
+  };
+  const accesses = new Map<Node, WhileAccess>();
+  const record = (node: Node, index: IrExpr, clean: Clean): void => {
+    let ref: IrExpr = index,
+      offset = 0;
+    if (index.kind === "bin" && (index.op === "+" || index.op === "-")) {
+      const literal =
+        index.right.kind === "numLit" ? index.right : index.op === "+" ? index.left : null;
+      const other = literal === index.right ? index.left : index.right;
+      if (literal?.kind !== "numLit" || !Number.isSafeInteger(literal.value)) return;
+      if (Math.abs(literal.value) > MAX_OFFSET || Object.is(literal.value, -0)) return;
+      offset = index.op === "-" ? -literal.value : literal.value;
+      ref = other;
+    }
+    if (ref.kind !== "varRef") return;
+    const fact = clean.get(ref.localId);
+    if (fact) accesses.set(node, { counter: ref.localId, index, ref, ...fact, offset });
+  };
+  const expr = (e: IrExpr, clean: Clean): void => {
+    if (e.kind === "bytesIntrinsic") {
+      const numeric = byteNumberAccess(e);
+      const index = numeric
+        ? e.args[numeric.offsetArg]
+        : e.method === "get"
+          ? e.args[0]
+          : undefined;
+      if (index) record(e, index, clean);
+    }
+    if (e.kind === "logical" && e.op === "&&") {
+      expr(e.left, clean);
+      expr(e.right, withFacts(clean, e.left));
+      return;
+    }
+    if (e.kind === "ternary") {
+      expr(e.cond, clean);
+      expr(e.then, withFacts(clean, e.cond));
+      expr(e.else_, clean);
+      return;
+    }
+    everyExprChild(
+      e,
+      (c) => (expr(c, clean), true),
+      (c) => (stmts([c], clean), true),
+    );
+  };
+  // Walks statements in order; the result is the clean state where the
+  // list falls through, or null when it never does.
+  const stmts = (list: readonly IrStmt[], clean: Clean): Clean | null => {
+    let current: Clean | null = clean;
+    for (const s of list) {
+      if (current === null) return null;
+      const step = counterStep(s);
+      if (step) {
+        const next: Map<string, Fact> = new Map(current);
+        next.delete(step.id);
+        current = next;
+        continue;
+      }
+      switch (s.kind) {
+        case "if": {
+          expr(s.cond, current);
+          const then = stmts(s.then, withFacts(current, s.cond));
+          const otherwise = stmts(s.else_ ?? [], current);
+          current = meet(then, otherwise);
+          break;
+        }
+        case "while": {
+          // A pass of the nested loop may follow its own increments.
+          const advanced: Map<string, Fact> = new Map(current);
+          for (const id of writtenCounters(s.body)) advanced.delete(id);
+          expr(s.cond, advanced);
+          stmts(s.body, withFacts(advanced, s.cond));
+          current = advanced;
+          break;
+        }
+        case "block":
+          if (!s.labels?.length) {
+            current = stmts(s.body, current);
+            break;
+          }
+          everyStmtChild(
+            s,
+            (e) => (expr(e, current!), true),
+            (c) => (stmts([c], current!), true),
+          );
+          break;
+        case "bytesSet":
+          record(s, s.index, current);
+          everyStmtChild(
+            s,
+            (e) => (expr(e, current!), true),
+            (c) => (stmts([c], current!), true),
+          );
+          break;
+        case "break":
+        case "continue":
+        case "return":
+        case "throw":
+          everyStmtChild(
+            s,
+            (e) => (expr(e, current!), true),
+            (c) => (stmts([c], current!), true),
+          );
+          current = null;
+          break;
+        default:
+          everyStmtChild(
+            s,
+            (e) => (expr(e, current!), true),
+            (c) => (stmts([c], current!), true),
+          );
+          break;
+      }
+    }
+    return current;
+  };
+  const writtenCounters = (list: readonly IrStmt[]): Set<string> => {
+    const out = new Set<string>();
+    const visit = (s: IrStmt): boolean => {
+      const step = counterStep(s);
+      if (step) out.add(step.id);
+      return everyStmtChild(s, () => true, visit);
+    };
+    list.every(visit);
+    return out;
+  };
+  expr(loop.cond, new Map());
+  stmts(loop.body, withFacts(new Map(), loop.cond));
+
+  // Each counter's bounds: the loop's and those of nested while loops that
+  // advance it.
+  const counters = new Map<string, WhileCounter>();
+  const loops: (IrStmt & { kind: "while" })[] = [loop];
+  const collectLoops = (s: IrStmt): boolean => {
+    if (s.kind === "while") loops.push(s);
+    return everyStmtChild(s, () => true, collectLoops);
+  };
+  loop.body.every(collectLoops);
+  for (const [id, step] of steps) {
+    if (!counter(id)) continue;
+    let bounds: WhileCounter["bounds"] = [];
+    for (const l of loops) {
+      if (l !== loop && !writtenCounters(l.body).has(id)) continue;
+      const fact = withFacts(new Map(), l.cond).get(id);
+      if (!fact) {
+        bounds = null;
+        break;
+      }
+      bounds.push({ bound: fact.bound, adj: fact.adj });
+    }
+    counters.set(id, { ...step, bounds });
+  }
+  return { accesses, counters };
+}
+
 /** Branches to `fast` when every access the version proves is in bounds for
  * every iteration and every view it proves thread-owned has no shared
  * storage, and to `slow` otherwise (including a counted loop whose
@@ -522,6 +987,39 @@ export function emitBytesLoopVersionGuard(
     B.line(`${ok} = icmp ugt i64 ${lengths[check.receiver]}, ${check.end}`);
     conditions.push(ok);
   }
+  for (const counter of version.counters) {
+    const value = host.emitExpr(counter.ref);
+    // A counter held as an integer (an int32 slot) is exact already and
+    // needs at most its lower bound tested.
+    const integer = exactInteger(host, value, counter.ref);
+    if (integer && integer.range.max <= SAFE) {
+      if (integer.range.min < counter.min) {
+        const ok = B.tmp();
+        B.line(`${ok} = icmp sge i64 ${widenInteger(host, integer)}, ${counter.min}`);
+        conditions.push(ok);
+      }
+    } else conditions.push(emitExactIntegerTest(host, value.name, counter.min, SAFE).ok);
+    for (const wrap of counter.wrapBounds) {
+      const bound = host.emitExpr(wrap.bound);
+      const boundInteger = exactInteger(host, bound, wrap.bound);
+      if (boundInteger && boundInteger.range.max <= wrap.limit) continue;
+      const ok = B.tmp();
+      B.line(`${ok} = fcmp ole double ${bound.name}, ${f64Lit(wrap.limit)}`);
+      conditions.push(ok);
+    }
+  }
+  for (const check of version.bounded) {
+    // `bound <= length - slack` in doubles: both sides are exact (a length
+    // is below 2^53 and a slack below 2^32), and NaN fails.
+    const bound = host.emitExpr(check.bound).name;
+    const length = B.tmp(),
+      room = B.tmp(),
+      ok = B.tmp();
+    B.line(`${length} = uitofp i64 ${lengths[check.receiver]} to double`);
+    B.line(`${room} = fsub double ${length}, ${f64Lit(check.slack)}`);
+    B.line(`${ok} = fcmp ole double ${bound}, ${room}`);
+    conditions.push(ok);
+  }
   if (counted && version.affine.length > 0) {
     // The first and last counter values, in ascending order. The last value
     // of a non-unit step is exact: `start + ⌊(limit ∓ 1 - start) / step⌋ *
@@ -567,6 +1065,14 @@ export function emitBytesLoopVersionGuard(
       let base = "0";
       for (const term of check.terms) {
         const value = host.emitExpr(term.expr);
+        if (version.guarded.has(term.key)) {
+          const tested = emitExactIntegerTest(host, value.name, GUARDED_TERM.min, GUARDED_TERM.max);
+          conditions.push(tested.ok);
+          const sum = B.tmp();
+          B.line(`${sum} = ${term.sign > 0 ? "add" : "sub"} i64 ${base}, ${tested.integer}`);
+          base = sum;
+          continue;
+        }
         const integer = exactInteger(host, value, term.expr);
         if (!integer) {
           // Unreachable: every term has a proven range. Stay checked.
@@ -614,6 +1120,39 @@ export function emitBytesLoopVersionGuard(
   else B.condBr(valid, fast, slow);
 }
 
+/** Tests that a double is an exact integer within [min, max] (not -0; NaN
+ * fails the ordered comparisons) and gives its i64. The integer is frozen,
+ * so it is a fixed value even when the test fails. */
+function emitExactIntegerTest(
+  host: LlvmEmitterContext,
+  value: string,
+  min: number,
+  max: number,
+): { ok: string; integer: string } {
+  const B = host.B;
+  const low = B.tmp(),
+    high = B.tmp(),
+    inRange = B.tmp(),
+    raw = B.tmp(),
+    integer = B.tmp(),
+    back = B.tmp(),
+    bits = B.tmp(),
+    backBits = B.tmp(),
+    exact = B.tmp(),
+    ok = B.tmp();
+  B.line(`${low} = fcmp oge double ${value}, ${f64Lit(min)}`);
+  B.line(`${high} = fcmp ole double ${value}, ${f64Lit(max)}`);
+  B.line(`${inRange} = and i1 ${low}, ${high}`);
+  B.line(`${raw} = fptosi double ${value} to i64`);
+  B.line(`${integer} = freeze i64 ${raw}`);
+  B.line(`${back} = sitofp i64 ${integer} to double`);
+  B.line(`${bits} = bitcast double ${value} to i64`);
+  B.line(`${backBits} = bitcast double ${back} to i64`);
+  B.line(`${exact} = icmp eq i64 ${bits}, ${backBits}`);
+  B.line(`${ok} = and i1 ${inRange}, ${exact}`);
+  return { ok, integer };
+}
+
 function scaleCounter(host: LlvmEmitterContext, value: string, scale: number): string {
   if (scale === 1) return value;
   const scaled = host.B.tmp();

packages/compiler/src/backend/llvm/classes.test.ts

@@ -1,5 +1,14 @@
 import { expect, test } from "vitest";
-import { DYN, F64, STRING, VOID, type IrModule } from "../../ir/ir.js";
+import {
+  DYN,
+  F64,
+  STRING,
+  VOID,
+  type IrExpr,
+  type IrFunction,
+  type IrModule,
+  type IrType,
+} from "../../ir/ir.js";
 import {
   assignCompactLayouts,
   buildClassGraph,
@@ -222,12 +231,13 @@ test("ProgramLifetime classes pack their fields after a 32-bit header", () => {
     contracts: { programLifetime: ["Node"] },
   };
   const llvm = emitLlvmModule(mod, { pointerBits: 64 });
-  // Fields go widest first, each at the first offset that fits it. Node's
-  // weight (an int32 slot: nothing stores a fraction) takes the word the
-  // header shares (24 bytes, not 32); Leaf keeps Node's offsets and puts its
-  // bool next to Node's (32 bytes, not 48).
-  expect(llvm).toContain(`%${mangleClassStruct("Node")} = type { i32, i32, ptr, i8 }`);
-  expect(llvm).toContain(`%${mangleClassStruct("Leaf")} = type { i32, i32, ptr, i8, i8, ptr }`);
+  // Scalars narrower than 8 bytes go first, then the rest, widest first,
+  // each at the first offset that fits it. Node's weight (an int32 slot:
+  // nothing stores a fraction) takes the word the header shares and its
+  // flag the next one (24 bytes, not 32); Leaf keeps Node's offsets and puts
+  // its bool next to Node's (32 bytes, not 48).
+  expect(llvm).toContain(`%${mangleClassStruct("Node")} = type { i32, i32, i8, ptr }`);
+  expect(llvm).toContain(`%${mangleClassStruct("Leaf")} = type { i32, i32, i8, i8, ptr, ptr }`);
   // Without the contract, the layout is the declared one.
   const mortal = emitLlvmModule({ ...mod, contracts: {} }, { pointerBits: 64 });
   expect(mortal).toContain(`%${mangleClassStruct("Leaf")} = type { i64, ptr, i8, i32, ptr, i8 }`);
@@ -332,6 +342,99 @@ test("references between ProgramLifetime instances are 32-bit indexes into their
   expect(classFieldIndex(leafMeta, "label").compressed).toBe(false);
 });
 
+test("arrays of ProgramLifetime instances keep 32-bit references in 4-byte slots", () => {
+  const node = { kind: "object" as const, className: "Node" };
+  const nodes = { kind: "array" as const, elem: node };
+  const ref = (localId: string, type: IrType): IrExpr => ({ kind: "varRef", localId, type, loc });
+  const fn = (name: string, body: IrExpr, returnType: IrType): IrFunction => ({
+    name,
+    params: [
+      { name: "a", localId: "a", type: nodes },
+      { name: "v", localId: "v", type: node },
+    ],
+    returnType,
+    locals: [
+      { id: "a", name: "a", type: nodes, mutable: false },
+      { id: "v", name: "v", type: node, mutable: false },
+    ],
+    body: [{ kind: "return", value: body, loc }],
+    loc,
+  });
+  const mod: IrModule = {
+    irVersion: 17,
+    sourceFile: loc.file,
+    entry: "main",
+    functions: [
+      { name: "main", params: [], returnType: VOID, locals: [], body: [], loc },
+      fn(
+        "first",
+        {
+          kind: "arrayGet",
+          arr: ref("a", nodes),
+          index: { kind: "numLit", value: 0, type: F64, loc },
+          type: node,
+          loc,
+        },
+        node,
+      ),
+      fn(
+        "add",
+        {
+          kind: "arrIntrinsic",
+          method: "push",
+          receiver: ref("a", nodes),
+          args: [ref("v", node)],
+          type: F64,
+          loc,
+        },
+        F64,
+      ),
+      fn("make", { kind: "arrayLit", elems: [ref("v", node)], type: nodes, loc }, nodes),
+      fn(
+        "find",
+        {
+          kind: "arrIntrinsic",
+          method: "indexOf",
+          receiver: ref("a", nodes),
+          args: [ref("v", node)],
+          type: F64,
+          loc,
+        },
+        F64,
+      ),
+    ],
+    classes: [{ name: "Node", fields: [{ name: "kids", type: nodes }], methods: [], loc }],
+    contracts: { programLifetime: ["Node"] },
+  };
+  const body = (llvm: string, name: string): string =>
+    llvm.split(/^define /m).find((f) => f.includes(`; ${name}\n`)) ?? "";
+  const llvm = emitLlvmModule(mod, { pointerBits: 64, objectAudit: false, lowRegion: true });
+  // The element type's ops say so (SCR_ARR_OPS_COMPACT), so the runtime makes
+  // the arrays SCR_ELEM_CREF.
+  expect(llvm).toMatch(
+    /^@sc_arrops\.\S+\.c = internal global \{ ptr, ptr, ptr, i32, i32 \} \{ [^}]*, i32 0, i32 1 \}$/m,
+  );
+  // A read loads the 32-bit reference and shifts it; an append stores one.
+  const first = body(llvm, "first");
+  expect(first).toMatch(/getelementptr inbounds i32, ptr %\S+, i64 \S+\n\s+%\S+ = load i32/);
+  // The states follow 4-byte slots.
+  expect(first).toContain("getelementptr inbounds [5 x i8]");
+  expect(first).toMatch(/= inttoptr i64 %\S+ to ptr/);
+  expect(body(llvm, "add")).toMatch(
+    /= lshr i64 %\S+, 3\n\s+%\S+ = trunc i64 %\S+ to i32\n\s+store i32/,
+  );
+  // indexOf scans the 4-byte slots for the needle's reference.
+  expect(llvm).toMatch(/call double @sc_arr_index_of_cref\(ptr %\S+, ptr %\S+\)/);
+  expect(/^define internal double @sc_arr_index_of_cref[^]*?^}/m.exec(llvm)?.[0]).toContain(
+    "load i32, ptr %qp0",
+  );
+  // Elsewhere the arrays keep 8-byte slots.
+  const elsewhere = emitLlvmModule(mod, { pointerBits: 64, objectAudit: false });
+  expect(elsewhere).not.toMatch(/sc_arrops\.\S+\.c /);
+  expect(body(elsewhere, "first")).not.toContain("inttoptr");
+  expect(elsewhere).not.toContain("sc_arr_index_of_cref");
+});
+
 test("a recycled block is cleared from the end of a ProgramLifetime instance's 32-bit header", () => {
   const BOOL = { kind: "bool" as const };
   const mod: IrModule = {

packages/compiler/src/backend/llvm/classes.ts

@@ -703,11 +703,13 @@ export function classFieldTypes(host: ShapeHost, cls: IrClassDef, int32?: Int32S
 
 /** Gives the classes `compact` admits (whole hierarchies: the test is the
  * root's) the 32-bit header and packed fields. A class keeps its base's
- * field offsets, and places each of its own fields, widest first, at the
- * first offset after the header that fits it: in a hole another field's
- * alignment left, in the base's tail padding, or at the end. So 32-bit and
- * smaller fields share 8-byte words. The struct lists the header and the
- * fields by offset, which LLVM's layout of the type reproduces (checked). */
+ * field offsets, and places each of its own fields at the first offset
+ * after the header that fits it: in a hole another field's alignment left,
+ * in the base's tail padding, or at the end. Scalars narrower than 8 bytes
+ * (flags, ids, counts) go first, widest first, so they share the header's
+ * cache line; then the other fields, widest first. So 32-bit and smaller
+ * fields share 8-byte words. The struct lists the header and the fields by
+ * offset, which LLVM's layout of the type reproduces (checked). */
 export function assignCompactLayouts(
   metaMap: ReadonlyMap<string, LlClassMeta>,
   compact: (root: LlClassMeta) => boolean,
@@ -751,10 +753,12 @@ export function assignCompactLayouts(
         );
       return COMPACT_REF;
     });
+    const smallScalar = (f: { type: string; field: number; size: number }): number =>
+      f.size < 8 && f.type !== "ptr" && !compressed[f.field] ? 0 : 1;
     const own = types
       .map((type, field) => ({ type, field, ...fieldStorage(type) }))
       .slice(baseCount)
-      .sort((a, b) => b.size - a.size || a.field - b.field);
+      .sort((a, b) => smallScalar(a) - smallScalar(b) || b.size - a.size || a.field - b.field);
     for (const f of own) {
       const sorted = [...elems].sort((a, b) => a.offset - b.offset);
       let at = -1;
@@ -860,9 +864,9 @@ export function emitClassShapes(
   nullable?: NullableRefFields,
   int32?: Int32Slots,
 ): { typeDefs: string[]; defs: string[] } {
-  // Whether compact instances live in the program-lifetime region (any
-  // field holds a 32-bit reference to one; emitter.ts assignCompactLayouts).
-  const regionRefs = [...metaMap.values()].some((m) => m.compressed.some(Boolean));
+  // Whether compact instances live in the program-lifetime region, where
+  // fields and arrays can refer to them in 32 bits (LlEmitter.compactRegion).
+  const regionRefs = host.compactRegion?.() === true;
   const typeDefs: string[] = [];
   const defs: string[] = [];
   const emitted = (mod.classes ?? []).filter((c) => !c.runtime);

packages/compiler/src/backend/llvm/counted-loops.ts

@@ -1,4 +1,9 @@
-import type { IntegerCountedForLoop, IntegerPairedForLoop } from "../../ir/integer-loops.js";
+import type {
+  IntegerCountedForLoop,
+  IntegerLoopFollower,
+  IntegerPairedForLoop,
+} from "../../ir/integer-loops.js";
+import { FOLLOWER_GUARD_LIMIT } from "../../ir/integer-loops.js";
 import type { IrExpr } from "../../ir/ir.js";
 import type { LlvmEmitterContext } from "./expr-context.js";
 import { f64Lit } from "./common.js";
@@ -61,9 +66,47 @@ export function emitCountedLoopSafety(
     );
   }
   if (loop.startGuarded) safe = andSafe(host, safe, emitExactStart(host, loop.start));
+  for (const follower of loop.followers) {
+    if (follower.startGuarded) safe = andSafe(host, safe, emitExactStart(host, follower.start));
+    if (follower.tripGuarded) safe = andSafe(host, safe, emitFollowerReach(host, loop, follower));
+  }
   return safe;
 }
 
+/** `|start| + |step| * span / |driver step| <= 2^52` for a follower, where
+ * `span` is the distance from the driver's start to the limit. The body runs
+ * at most `span / |driver step| + 1` times, so every value the follower holds
+ * on a body entry is within the bound. NaN and infinities fail the ordered
+ * test. */
+function emitFollowerReach(
+  host: LlvmEmitterContext,
+  loop: IntegerCountedForLoop,
+  follower: IntegerLoopFollower,
+): string {
+  const B = host.B;
+  const start = host.emitExpr(loop.start),
+    limit = host.emitExpr(loop.limit),
+    from = host.emitExpr(follower.start);
+  const span = B.tmp(),
+    reach = B.tmp(),
+    magnitude = B.tmp(),
+    total = B.tmp(),
+    ok = B.tmp();
+  B.line(
+    loop.step > 0
+      ? `${span} = fsub double ${limit.name}, ${start.name}`
+      : `${span} = fsub double ${start.name}, ${limit.name}`,
+  );
+  B.line(
+    `${reach} = fmul double ${span}, ${f64Lit(Math.abs(follower.step) / Math.abs(loop.step))}`,
+  );
+  host.declare(`declare double @llvm.fabs.f64(double)`);
+  B.line(`${magnitude} = call double @llvm.fabs.f64(double ${from.name})`);
+  B.line(`${total} = fadd double ${magnitude}, ${reach}`);
+  B.line(`${ok} = fcmp ole double ${total}, ${f64Lit(FOLLOWER_GUARD_LIMIT)}`);
+  return ok;
+}
+
 /** The run-time test of a guarded paired loop: each unproven start is an
  * exact safe integer. */
 export function emitPairedLoopSafety(host: LlvmEmitterContext, loop: IntegerPairedForLoop): string {

packages/compiler/src/backend/llvm/dense-array-access.ts

@@ -27,6 +27,8 @@ import {
   storeArrCount,
 } from "./common.js";
 import type { LlValue, LlvmEmitterContext } from "./expr-context.js";
+import { compactRefLoadLines, compactRefStoreLines } from "./classes.js";
+import { elemAccess } from "./shapes.js";
 import { exactInteger, widenInteger } from "./integer-values.js";
 
 const SCR_ARR_VALUE = 1;
@@ -209,26 +211,40 @@ function statePointer(
   return statePtr;
 }
 
-/** The dense slot type: boolean arrays store one byte per element, every
- * other element kind an 8-byte slot. */
-function slotType(acc: ArrayAccess): "i8" | "i64" {
-  return acc === "bool" ? "i8" : "i64";
+/** How an array's dense slots hold its elements: the access kind, or
+ * `cref` for references to compact class instances (SCR_ELEM_CREF: a 4-byte
+ * slot holding the address over 8; LlEmitter.compactArrayElem). */
+type SlotKind = ArrayAccess | "cref";
+
+function slotKind(host: LlvmEmitterContext, acc: ArrayAccess, element: IrType): SlotKind {
+  return acc === "ref" && host.compactArrayElem(element) ? "cref" : acc;
+}
+
+/** The dense slot type: boolean arrays store one byte per element, compact
+ * references four, every other element kind an 8-byte slot. */
+function slotType(kind: SlotKind): "i8" | "i32" | "i64" {
+  return kind === "bool" ? "i8" : kind === "cref" ? "i32" : "i64";
 }
 
 /** Bytes per dense slot (scr_arr_slot_width). */
-export function slotWidth(acc: ArrayAccess): number {
-  return acc === "bool" ? 1 : 8;
+function slotWidth(kind: SlotKind): number {
+  return kind === "bool" ? 1 : kind === "cref" ? 4 : 8;
+}
+
+/** Bytes per dense slot of an array of `element` (scr_arr_slot_width). */
+export function denseSlotWidth(host: LlvmEmitterContext, element: IrType): number {
+  return slotWidth(slotKind(host, elemAccess(element), element));
 }
 
 function valuePointer(
   host: LlvmEmitterContext,
   guard: Pick<DenseGuard, "offset" | "data">,
-  acc: ArrayAccess,
+  kind: SlotKind,
 ): string {
   const B = host.B;
   const valuePtr = B.tmp();
   B.line(
-    `${valuePtr} = getelementptr inbounds ${slotType(acc)}, ptr ${guard.data}, ${host.sizeType} ${guard.offset}`,
+    `${valuePtr} = getelementptr inbounds ${slotType(kind)}, ptr ${guard.data}, ${host.sizeType} ${guard.offset}`,
   );
   host.markMemoryPointer(valuePtr, "array:elements");
   return valuePtr;
@@ -300,6 +316,7 @@ export function emitDenseArrayGet(
   const B = host.B;
   const ty = acc === "f64" ? "double" : acc === "bool" ? "i1" : "ptr";
   const ret = acc === "bool" ? "zeroext i1" : ty;
+  const kind = slotKind(host, acc, element);
   host.declare(`declare ${ret} @${getter}(ptr, double)`);
   if (acc === "ref" && retain && !isRefCounted(element)) {
     const t = B.tmp();
@@ -322,7 +339,7 @@ export function emitDenseArrayGet(
     slow,
     true,
     valueLabel,
-    slotWidth(acc),
+    slotWidth(kind),
     proven,
     induction,
   );
@@ -333,7 +350,7 @@ export function emitDenseArrayGet(
     B.condBr(present, valueLabel, slow);
   }
   B.startBlock(valueLabel);
-  const ptr = valuePointer(host, guard, acc);
+  const ptr = valuePointer(host, guard, kind);
   let fast: string;
   let fastLabel = valueLabel;
   if (acc === "f64") {
@@ -347,7 +364,13 @@ export function emitDenseArrayGet(
   } else {
     const raw = B.tmp(),
       nonnull = B.tmp();
-    B.line(`${raw} = load ptr, ptr ${ptr}${host.fieldAliasAttachment(ptr)}`);
+    if (kind === "cref") {
+      const ref = B.tmp();
+      B.line(`${ref} = load i32, ptr ${ptr}${host.fieldAliasAttachment(ptr)}`);
+      for (const line of compactRefLoadLines(ref, raw, `${raw}.r`)) B.line(line.trimStart());
+    } else {
+      B.line(`${raw} = load ptr, ptr ${ptr}${host.fieldAliasAttachment(ptr)}`);
+    }
     B.line(`${nonnull} = icmp ne ptr ${raw}, null`);
     fastLabel = B.newLabel("arr.get.ref");
     B.condBr(nonnull, fastLabel, slow);
@@ -448,6 +471,7 @@ export function emitDenseArraySet(
 ): void {
   const B = host.B;
   const ty = acc === "f64" ? "double" : acc === "bool" ? "i1" : "ptr";
+  const kind = slotKind(host, acc, element);
   const setter = `scr_arr_set_${acc}`;
   host.declare(`declare void @${setter}(ptr, double, ${acc === "bool" ? "i1 zeroext" : ty})`);
   const call = (attrs: string): void =>
@@ -467,7 +491,7 @@ export function emitDenseArraySet(
     slow,
     false,
     filledLabel,
-    slotWidth(acc),
+    slotWidth(kind),
     proven,
   );
   const { offset, len } = guard;
@@ -478,15 +502,20 @@ export function emitDenseArraySet(
       const bits = B.tmp();
       B.line(`${bits} = zext i1 ${value} to i8`);
       B.line(`store i8 ${bits}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
+    } else if (kind === "cref") {
+      const ref = B.tmp();
+      for (const line of compactRefStoreLines(value, ref, `${ref}.r`)) B.line(line.trimStart());
+      B.line(`store i32 ${ref}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
     } else {
       B.line(`store ptr ${value}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
     }
   };
   const statePtr = statePointer(host, guard);
-  const valuePtr = valuePointer(host, guard, acc);
+  const valuePtr = valuePointer(host, guard, kind);
   let oldState: string | null = null;
   let old: string | null = null;
-  if (acc === "ref") {
+  // Compact instances are never released: a replaced one needs nothing.
+  if (kind === "ref") {
     oldState = B.tmp();
     old = B.tmp();
     B.line(`${oldState} = load i8, ptr ${statePtr}${host.fieldAliasAttachment(statePtr)}`);
@@ -537,7 +566,7 @@ export function emitDenseArraySet(
   storeArrCount(host, nextLen, lenPtr, host.fieldAliasAttachment(lenPtr));
   B.br(storedLabel);
   B.startBlock(storedLabel);
-  if (acc === "ref" && oldState && old) {
+  if (kind === "ref" && oldState && old) {
     const hadValue = B.tmp();
     B.line(`${hadValue} = icmp eq i8 ${oldState}, ${SCR_ARR_VALUE}`);
     const releaseLabel = B.newLabel("arr.set.release");
@@ -549,9 +578,9 @@ export function emitDenseArraySet(
   // Below the bound the slot holds a present value: replace it, leaving
   // the state alone, and release a replaced reference after the store.
   B.startBlock(filledLabel);
-  const filledValuePtr = valuePointer(host, guard, acc);
+  const filledValuePtr = valuePointer(host, guard, kind);
   let filledOld: string | null = null;
-  if (acc === "ref") {
+  if (kind === "ref") {
     filledOld = B.tmp();
     B.line(
       `${filledOld} = load ptr, ptr ${filledValuePtr}${host.fieldAliasAttachment(filledValuePtr)}`,
@@ -578,10 +607,12 @@ export function emitDenseArrayPop(
   host: LlvmEmitterContext,
   array: string,
   acc: ArrayAccess,
+  element: IrType,
   empty: string,
   slow: string,
 ): string {
   const B = host.B;
+  const kind = slotKind(host, acc, element);
   const size = host.sizeType;
   const header = (field: number): string => {
     const ptr = B.tmp();
@@ -615,16 +646,23 @@ export function emitDenseArrayPop(
     states = B.tmp();
   B.line(`${data} = load ptr, ptr ${dataPtr}${host.fieldAliasAttachment(dataPtr)}`);
   loadArrCount(host, cap, capPtr, host.fieldAliasAttachment(capPtr));
-  scrArrStates(host, states, data, cap, slotWidth(acc));
-  const valuePtr = valuePointer(host, { offset: last, data }, acc);
+  scrArrStates(host, states, data, cap, slotWidth(kind));
+  const valuePtr = valuePointer(host, { offset: last, data }, kind);
   const statePtr = statePointer(host, { offset: last, states });
-  const slotTy = slotType(acc);
+  const slotTy = slotType(kind);
   let raw = B.tmp();
   B.line(`${raw} = load ${slotTy}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
   if (slotTy === "i8") {
     const wide = B.tmp();
     B.line(`${wide} = zext i8 ${raw} to i64`);
     raw = wide;
+  } else if (slotTy === "i32") {
+    // The 8-byte slot of a compact reference is its address.
+    const wide = B.tmp(),
+      address = B.tmp();
+    B.line(`${wide} = zext i32 ${raw} to i64`);
+    B.line(`${address} = shl nuw nsw i64 ${wide}, 3`);
+    raw = address;
   }
   B.line(`store ${slotTy} 0, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
   B.line(`store i8 0, ptr ${statePtr}${host.fieldAliasAttachment(statePtr)}`);
@@ -648,10 +686,12 @@ export function emitDenseArrayPush(
   host: LlvmEmitterContext,
   array: string,
   acc: ArrayAccess,
+  element: IrType | null,
   value: string,
 ): string {
   const B = host.B;
   const size = host.sizeType;
+  const kind = element === null ? acc : slotKind(host, acc, element);
   const ty = acc === "f64" ? "double" : acc === "bool" ? "i1" : "ptr";
   const pusher = `scr_arr_push_${acc}`;
   host.declare(`declare double @${pusher}(ptr, ${acc === "bool" ? "i1 zeroext" : ty})`);
@@ -685,16 +725,20 @@ export function emitDenseArrayPush(
   B.line(`${spare} = sub nuw ${size} ${cap}, ${len}`);
   B.line(`${near} = getelementptr inbounds i8, ptr ${data}, ${size} ${spare}`);
   B.line(
-    `${statePtr} = getelementptr inbounds [${slotWidth(acc)} x i8], ptr ${near}, ${size} ${cap}, ${size} -1`,
+    `${statePtr} = getelementptr inbounds [${slotWidth(kind)} x i8], ptr ${near}, ${size} ${cap}, ${size} -1`,
   );
   host.markMemoryPointer(statePtr, "array:present");
-  const valuePtr = valuePointer(host, { offset: len, data }, acc);
+  const valuePtr = valuePointer(host, { offset: len, data }, kind);
   if (acc === "f64") {
     B.line(`store double ${value}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
   } else if (acc === "bool") {
     const bits = B.tmp();
     B.line(`${bits} = zext i1 ${value} to i8`);
     B.line(`store i8 ${bits}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
+  } else if (kind === "cref") {
+    const ref = B.tmp();
+    for (const line of compactRefStoreLines(value, ref, `${ref}.r`)) B.line(line.trimStart());
+    B.line(`store i32 ${ref}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
   } else {
     B.line(`store ptr ${value}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
   }

packages/compiler/src/backend/llvm/dense-array-loops.test.ts

@@ -1,5 +1,6 @@
 import { expect, test } from "vitest";
 import { BOOL, F64, arrayOf, type IrExpr, type IrLocal, type IrStmt } from "../../ir/ir.js";
+import type { IntegerCountedForLoop } from "../../ir/integer-loops.js";
 import {
   countedDenseShape,
   matchDenseArrayLoop,
@@ -111,16 +112,24 @@ test("loops that may resize, rebind or move storage keep the ordinary copy only"
   expect([...rebound!.arrays.keys()]).toEqual(["a"]);
 });
 
+const counted = (
+  fields: Pick<IntegerCountedForLoop, "start" | "limit" | "step" | "inclusive" | "range">,
+): IntegerCountedForLoop => ({
+  localId: "i",
+  guarded: false,
+  limitGuarded: false,
+  startGuarded: false,
+  guardLimit: 0,
+  followers: [],
+  ...fields,
+});
+
 test("counted shapes need a non-negative counter strictly below the length", () => {
   const ascending = (limit: IrExpr, inclusive: boolean, min = 0) =>
-    countedDenseShape(loop([]), {
-      localId: "i",
-      start: num(min),
-      limit,
-      step: 1,
-      inclusive,
-      range: { min, max: 100 },
-    });
+    countedDenseShape(
+      loop([]),
+      counted({ start: num(min), limit, step: 1, inclusive, range: { min, max: 100 } }),
+    );
   const minus = (offset: number): IrExpr => ({
     kind: "bin",
     op: "-",
@@ -129,19 +138,58 @@ test("counted shapes need a non-negative counter strictly below the length", ()
     type: F64,
     loc,
   });
-  expect(ascending(method("a", "length"), false)?.length.localId).toBe("a");
-  expect(ascending(minus(1), true)?.length.localId).toBe("a");
+  expect(ascending(method("a", "length"), false)?.length?.localId).toBe("a");
+  expect(ascending(minus(1), true)?.length?.localId).toBe("a");
   expect(ascending(method("a", "length"), true)).toBeNull();
   expect(ascending(minus(1), false, -1)).toBeNull();
+  // Another invariant limit bounds the counter itself; the entry test
+  // compares it with every indexed array's hole-free prefix.
+  const limited = ascending(ref("n"), false);
+  expect(limited?.length).toBeNull();
+  expect(limited?.limit?.limit).toEqual(ref("n"));
+  expect(ascending(ref("n"), false, -1)).toBeNull();
   const descending = (offset: number) =>
-    countedDenseShape(loop([]), {
-      localId: "i",
-      start: minus(offset),
-      limit: num(0),
-      step: -1,
-      inclusive: true,
-      range: { min: 0, max: 100 },
-    });
-  expect(descending(1)?.length.localId).toBe("a");
+    countedDenseShape(
+      loop([]),
+      counted({
+        start: minus(offset),
+        limit: num(0),
+        step: -1,
+        inclusive: true,
+        range: { min: 0, max: 100 },
+      }),
+    );
+  expect(descending(1)?.length?.localId).toBe("a");
   expect(descending(0)).toBeNull();
 });
+
+test("a loop to another invariant limit covers each array whose length it keeps", () => {
+  const limited: DenseLoopShape = {
+    counter: "i",
+    length: null,
+    limit: counted({
+      start: num(0),
+      limit: ref("n"),
+      step: 1,
+      inclusive: false,
+      range: { min: 0, max: 100 },
+    }),
+    range: { min: 0, max: 100 },
+  };
+  const matchLimited = (body: IrStmt[], unaliased = new Set<string>()) =>
+    matchDenseArrayLoop(loop(body), limited, locals, unaliased, new Set(["a", "b"]));
+  const copy = write("b", read("a"));
+  const dense = matchLimited([copy]);
+  expect([...dense!.arrays.keys()].sort()).toEqual(["a", "b"]);
+  expect(dense!.length).toBeNull();
+  expect(dense!.limit?.limit).toEqual(ref("n"));
+  // An array the loop may resize is not covered; neither is one it may
+  // share storage with.
+  const resizing = [
+    { kind: "exprStmt" as const, expr: read("a"), loc },
+    { kind: "exprStmt" as const, expr: method("b", "getNumber", [ref("i")]), loc },
+    { kind: "exprStmt" as const, expr: method("b", "push", [num(1)]), loc },
+  ];
+  expect([...matchLimited(resizing, new Set(["b"]))!.arrays.keys()]).toEqual(["a"]);
+  expect(matchLimited(resizing)).toBeNull();
+});

packages/compiler/src/backend/llvm/dense-array-loops.ts

@@ -15,22 +15,33 @@
  * test bounds `a.length` by 2^31 - 1, so the fast copy's counter is an int32.
  * Arrays longer than that are sparse in practice (a dense one would need
  * 16 GB of slots) and take the ordinary copy, as does every array with a
- * hole, present undefined or sparse storage below `a.length`. */
+ * hole, present undefined or sparse storage below `a.length`.
+ *
+ * A counted loop with another invariant limit, such as `j < n` after
+ * `const n = a.length` or `j < 5`, is covered the same way: the test bounds
+ * the loop's exclusive limit by 2^31 - 1 and by each indexed array's
+ * `filled`, and the loop must provably never change any of their lengths. */
 
 import type { IrExpr, IrLocal, IrStmt } from "../../ir/ir.js";
 import type { IntegerRange } from "../../ir/integer-ranges.js";
 import { preservesArrayLength } from "../../ir/array-length-stability.js";
 import { everyExprChild, everyStmtChild } from "../../ir/traverse.js";
+import type { IntegerCountedForLoop } from "../../ir/integer-loops.js";
 import type { LlvmEmitterContext } from "./expr-context.js";
 import { loadArrCount, SCR_ARR_FIELD } from "./common.js";
+import { emitCountedLoopLimit } from "./counted-loops.js";
 
 export const INT32_MAX = 2147483647;
 
 export interface DenseArrayLoop {
   /** The loop's counter binding. */
   counter: string;
-  /** The array whose length bounds the counter. */
-  length: IrExpr & { kind: "varRef" };
+  /** The array whose length bounds the counter, or null for a counted loop
+   * bounded by `limit`. */
+  length: (IrExpr & { kind: "varRef" }) | null;
+  /** The ascending counted loop whose invariant limit bounds the counter,
+   * when `length` is null. */
+  limit: IntegerCountedForLoop | null;
   /** Arrays whose accesses at the counter are proven to be inside the
    * hole-free prefix in the fast copy, with a read of each binding. */
   arrays: ReadonlyMap<string, IrExpr & { kind: "varRef" }>;
@@ -39,12 +50,15 @@ export interface DenseArrayLoop {
 }
 
 /** The fast copy duplicates the loop; keep the duplicated code small. */
-const MAX_LOOP_NODES = 120;
+const MAX_LOOP_NODES = 160;
 
 /** How a matched integer loop bounds its counter below `length.length`. */
 export interface DenseLoopShape {
   counter: string;
-  length: IrExpr & { kind: "varRef" };
+  /** The array whose length bounds the counter, or null for `limit`. */
+  length: (IrExpr & { kind: "varRef" }) | null;
+  /** An ascending counted loop bounded by another invariant limit. */
+  limit?: IntegerCountedForLoop;
   /** The counter's proven range on every pass of the ordinary loop; the
    * fast copy keeps its minimum, which must be at least 0. */
   range: IntegerRange;
@@ -73,22 +87,18 @@ function lengthOffset(e: IrExpr): { receiver: IrExpr & { kind: "varRef" }; offse
 
 /** The array bounding a counted loop's counter below its length: an
  * ascending loop compared below `a.length - c`, or a descending one starting
- * at `a.length - c` (c >= 1). */
+ * at `a.length - c` (c >= 1). Another ascending loop is bounded by its own
+ * invariant limit. */
 export function countedDenseShape(
   loop: IrStmt & { kind: "for" },
-  counted: {
-    localId: string;
-    start: IrExpr;
-    limit: IrExpr;
-    step: number;
-    inclusive: boolean;
-    range: IntegerRange;
-  },
+  counted: IntegerCountedForLoop,
 ): DenseLoopShape | null {
   if (counted.range.min < 0) return null;
   if (counted.step > 0) {
     const bound = lengthOffset(counted.limit);
-    if (!bound || bound.offset < (counted.inclusive ? 1 : 0)) return null;
+    if (!bound)
+      return { counter: counted.localId, length: null, limit: counted, range: counted.range };
+    if (bound.offset < (counted.inclusive ? 1 : 0)) return null;
     return { counter: counted.localId, length: bound.receiver, range: counted.range };
   }
   // The start is evaluated once, before the loop; the counter only falls.
@@ -143,9 +153,11 @@ export function matchDenseArrayLoop(
     return everyStmtChild(s, expr, stmt);
   };
   if (!loop.body.every(stmt) || !expr(loop.cond) || nested) return null;
+  const nodesOfLoop = [loop.cond, ...loop.body];
   if (
+    length !== null &&
     !preservesArrayLength(
-      [loop.cond, ...loop.body],
+      nodesOfLoop,
       { receiver: length.localId, inRange: counter },
       locals,
       unaliased,
@@ -161,7 +173,14 @@ export function matchDenseArrayLoop(
       local.boxed ||
       local.tdz ||
       disturbed.has(id) ||
-      (id !== length.localId && !initialized.has(id))
+      (id !== length?.localId && !initialized.has(id))
+    )
+      continue;
+    // Without a bounding array, the entry test reads each array's `filled`
+    // once: the loop must not change any of their lengths.
+    if (
+      length === null &&
+      !preservesArrayLength(nodesOfLoop, { receiver: id, inRange: counter }, locals, unaliased)
     )
       continue;
     arrays.set(id, ref);
@@ -170,13 +189,15 @@ export function matchDenseArrayLoop(
   return {
     counter,
     length,
+    limit: length === null ? (shape.limit ?? null) : null,
     arrays,
     range: { min: shape.range.min, max: Math.min(shape.range.max, INT32_MAX - 1) },
   };
 }
 
-/** The fast copy's entry test: the bounding length is at most 2^31 - 1 and
- * at most every indexed array's hole-free prefix bound. */
+/** The fast copy's entry test: the bounding length (or the counted loop's
+ * exclusive limit) is at most 2^31 - 1 and at most every indexed array's
+ * hole-free prefix bound. */
 export function emitDenseLoopGuard(host: LlvmEmitterContext, loop: DenseArrayLoop): string {
   const B = host.B;
   const size = host.sizeType;
@@ -186,7 +207,29 @@ export function emitDenseLoopGuard(host: LlvmEmitterContext, loop: DenseArrayLoo
     host.markMemoryPointer(ptr, "array:header");
     return ptr;
   };
-  const receiver = host.emitStableReceiver(loop.length, []);
+  if (loop.length === null) {
+    // A limit at or below the start runs no pass, and passes the test.
+    const limit = emitCountedLoopLimit(host, loop.limit!);
+    const small = B.tmp();
+    B.line(`${small} = icmp sle i64 ${limit}, ${INT32_MAX}`);
+    let valid = small;
+    for (const ref of loop.arrays.values()) {
+      const array = host.emitStableReceiver(ref, []);
+      const filledPtr = header(array.name, SCR_ARR_FIELD.filled),
+        filled = B.tmp(),
+        wide = B.tmp(),
+        covered = B.tmp(),
+        both = B.tmp();
+      B.line(`${filled} = load i32, ptr ${filledPtr}${host.fieldAliasAttachment(filledPtr)}`);
+      B.line(`${wide} = zext i32 ${filled} to i64`);
+      B.line(`${covered} = icmp sle i64 ${limit}, ${wide}`);
+      B.line(`${both} = and i1 ${valid}, ${covered}`);
+      valid = both;
+    }
+    return valid;
+  }
+  const length = loop.length;
+  const receiver = host.emitStableReceiver(length, []);
   const lenPtr = header(receiver.name, SCR_ARR_FIELD.len),
     len = B.tmp(),
     small = B.tmp();
@@ -194,7 +237,7 @@ export function emitDenseLoopGuard(host: LlvmEmitterContext, loop: DenseArrayLoo
   B.line(`${small} = icmp ule ${size} ${len}, ${INT32_MAX}`);
   let valid = small;
   for (const [id, ref] of loop.arrays) {
-    const array = id === loop.length.localId ? receiver : host.emitStableReceiver(ref, []);
+    const array = id === length.localId ? receiver : host.emitStableReceiver(ref, []);
     const filledPtr = header(array.name, SCR_ARR_FIELD.filled),
       filled = B.tmp(),
       covered = B.tmp(),

packages/compiler/src/backend/llvm/dyn.ts

@@ -108,6 +108,15 @@ const DYN_HANDLE_UNBOX_FN: Record<string, string> = {
   dgramSocket: "scr_dgram_from_dyn",
 };
 
+/** ScrMessageKind (scr_message.h): the node kinds message readers test. */
+const MESSAGE_KIND = {
+  UNDEFINED: 0,
+  NULL: 1,
+  BOOL: 2,
+  NUMBER: 3,
+  STRING: 4,
+} as const;
+
 export const DYN_KIND = {
   NULL: 0,
   BOOL: 1,
@@ -173,6 +182,8 @@ export class LlDyn {
   private readonly dynFuncThunks = new Map<string, string>();
   private readonly dynFuncBoxes = new Map<string, string>();
   private readonly dynFuncAdapters = new Map<string, string>();
+  private readonly messageListeners = new Map<string, string | null>();
+  private readonly messageReaders = new Map<string, string>();
   private readonly promiseDynAdapters = new Map<string, string>();
   private readonly mapDynOps = new Map<string, string>();
   private dynToStrFn: string | null = null;
@@ -4610,6 +4621,297 @@ export class LlDyn {
     return name;
   }
 
+  /** `sc_dml_<n>(ptr c, ptr message) -> i1`, the typed message entry of a
+   * closure registered as a 'message' listener (ScrDynMessageListener):
+   * builds the closure's parameter from the message's nodes and calls the
+   * closure. It answers false, without calling it, when the message does
+   * not have the parameter's exact layout, and the listener then runs
+   * through its thunk on the decoded message, as before. Null when the
+   * signature's parameter has no message reader (messageReadable). */
+  messageListenerHelper(t: IrType & { kind: "func" }): string | null {
+    const key = typeKey(t);
+    const existing = this.messageListeners.get(key);
+    if (existing !== undefined) return existing;
+    const param = t.params[0];
+    const supported =
+      t.params.length === 1 &&
+      t.rest !== true &&
+      param !== undefined &&
+      (t.ret.kind === "void" || t.ret.kind === "f64" || t.ret.kind === "bool") &&
+      this.messageReadable(param, new Set());
+    if (!supported) {
+      this.messageListeners.set(key, null);
+      return null;
+    }
+    const name = `sc_dml_${this.messageListeners.size}`;
+    this.messageListeners.set(key, name);
+    const B = new BlockBuilder();
+    B.entryAllocas.push(`%fail = alloca i1`);
+    B.line(`store i1 false, ptr %fail`);
+    const value = B.tmp();
+    B.line(
+      `${value} = call ${this.valTy(param)} @${this.messageReaderHelper(param)}(ptr %m, ${this.host.sizeType} 0, ptr %fail)`,
+    );
+    const failed = B.tmp();
+    B.line(`${failed} = load i1, ptr %fail`);
+    const lMiss = B.newLabel("dml.miss");
+    const lCall = B.newLabel("dml.call");
+    B.condBr(failed, lMiss, lCall);
+    B.startBlock(lMiss);
+    B.terminate(`ret i1 false`);
+    B.startBlock(lCall);
+    // The closure consumes its parameter; a pending exception stays for
+    // the emitter, as after the thunk.
+    const fnp = B.tmp();
+    const fn = B.tmp();
+    B.line(`${fnp} = getelementptr inbounds %ScrClosure, ptr %c, i64 0, i32 1`);
+    B.line(`${fn} = load ptr, ptr ${fnp}`);
+    const args = `ptr %c, ${this.valTy(param)} ${value}`;
+    if (t.ret.kind === "void") B.line(`call void ${fn}(${args})`);
+    else B.line(`${B.tmp()} = call ${this.valTy(t.ret)} ${fn}(${args})`);
+    B.terminate(`ret i1 true`);
+    this.defs.push(
+      `define internal zeroext i1 @${name}(ptr %c, ptr %m) ${FN_ATTRS} { ; message entry for ${llvmCommentText(key)}`,
+      B.render(),
+      `}`,
+      ``,
+    );
+    return name;
+  }
+
+  /** Whether a message reader can build T: numbers, booleans and strings;
+   * records of them with only declared fields, none of union type; and
+   * boxed unions of those arms and null or undefined without a literal
+   * discriminator, with at most one number, boolean and string arm. */
+  private messageReadable(t: IrType, seen: Set<string>): boolean {
+    switch (t.kind) {
+      case "f64":
+      case "bool":
+      case "string":
+        return true;
+      case "record": {
+        const shape = this.host.recordsById.get(t.shapeId);
+        if (!shape || shape.tuple || shape.indexValue || shape.fields.length === 0) return false;
+        if (seen.has(t.shapeId) || this.isRecursiveShape(t)) return false;
+        seen.add(t.shapeId);
+        const readable = shape.fields.every(
+          (f) =>
+            !f.name.startsWith("%") &&
+            f.type.kind !== "union" &&
+            llFieldType(f.type, this.host.inlineUnions.record(f.type)) !== INLINE_UNION_FIELD &&
+            this.messageReadable(f.type, seen),
+        );
+        seen.delete(t.shapeId);
+        return readable;
+      }
+      case "union": {
+        const def = this.host.unionsById.get(t.unionId);
+        // A discriminated union's checked conversion also tests the arm's
+        // literal discriminator, which the readers do not.
+        if (!def || def.discriminant || this.host.nullableUnions.has(t.unionId)) return false;
+        const scalars = new Set<string>();
+        for (const arm of def.arms) {
+          if (arm.kind === "nullT" || arm.kind === "undefinedT") continue;
+          if (arm.kind === "f64" || arm.kind === "bool" || arm.kind === "string") {
+            if (scalars.has(arm.kind)) return false;
+            scalars.add(arm.kind);
+            continue;
+          }
+          if (arm.kind !== "record" || !this.messageReadable(arm, seen)) return false;
+        }
+        return true;
+      }
+      default:
+        return false;
+    }
+  }
+
+  /** `sc_dmr_<n>(ptr message, size node, ptr fail) -> T`: T (+1) built
+   * from a message node, for a type messageReadable accepts. Sets *fail
+   * and returns a dummy when the node does not have T's layout: the arm
+   * the checked conversion would choose, a record's declared keys in
+   * declaration order and no others. */
+  private messageReaderHelper(t: IrType): string {
+    const key = typeKey(t);
+    const existing = this.messageReaders.get(key);
+    if (existing) return existing;
+    const name = `sc_dmr_${this.messageReaders.size}`;
+    this.messageReaders.set(key, name);
+    const host = this.host;
+    const S = host.sizeType;
+    if (t.kind !== "record") host.declare(`declare i32 @scr_message_kind(ptr, ${S})`);
+    const retTy = this.valTy(t);
+    const dummy = retTy === "double" ? f64Lit(0) : retTy === "i1" ? "false" : "null";
+    const B = new BlockBuilder();
+    const lFail = B.newLabel("dmr.fail");
+    // scr_message_fields tests a record's kind itself.
+    const kind = B.tmp();
+    if (t.kind !== "record") B.line(`${kind} = call i32 @scr_message_kind(ptr %m, ${S} %n)`);
+    const requireKind = (want: number): void => {
+      const ok = B.tmp();
+      B.line(`${ok} = icmp eq i32 ${kind}, ${want}`);
+      const lOk = B.newLabel("dmr.kind");
+      B.condBr(ok, lOk, lFail);
+      B.startBlock(lOk);
+    };
+    switch (t.kind) {
+      case "f64":
+      case "bool": {
+        host.declare(`declare double @scr_message_number(ptr, ${S})`);
+        requireKind(t.kind === "f64" ? MESSAGE_KIND.NUMBER : MESSAGE_KIND.BOOL);
+        const n = B.tmp();
+        B.line(`${n} = call double @scr_message_number(ptr %m, ${S} %n)`);
+        if (t.kind === "f64") B.terminate(`ret double ${n}`);
+        else {
+          const b = B.tmp();
+          B.line(`${b} = fcmp une double ${n}, ${f64Lit(0)}`);
+          B.terminate(`ret i1 ${b}`);
+        }
+        break;
+      }
+      case "string": {
+        host.declare(`declare ptr @scr_message_string(ptr, ${S})`);
+        requireKind(MESSAGE_KIND.STRING);
+        const str = B.tmp();
+        B.line(`${str} = call ptr @scr_message_string(ptr %m, ${S} %n)`);
+        B.terminate(`ret ptr ${str}`);
+        break;
+      }
+      case "record": {
+        const shape = host.recordsById.get(t.shapeId)!;
+        const order = recordSourceFieldOrder(shape);
+        const fields = new Map(shape.fields.map((f, i) => [f.name, { field: f, index: i }]));
+        const base = host.nullableUnions.fieldBase(t.shapeId);
+        const struct = mangleRecordStruct(t.shapeId);
+        const names = this.recordNameTable(t.shapeId, shape);
+        host.declare(`declare zeroext i1 @scr_message_fields(ptr, ${S}, ptr, ptr, ${S}, ptr)`);
+        B.entryAllocas.push(`%kids = alloca [${order.length} x ${S}]`);
+        const matched = B.tmp();
+        B.line(
+          `${matched} = call zeroext i1 @scr_message_fields(ptr %m, ${S} %n, ptr ${names.names}, ptr ${names.lens}, ${S} ${order.length}, ptr %kids)`,
+        );
+        const lBuild = B.newLabel("dmr.build");
+        B.condBr(matched, lBuild, lFail);
+        B.startBlock(lBuild);
+        B.line(`%r0 = call ptr @${mangleRecordNew(t.shapeId)}()`);
+        order.forEach((fieldName, i) => {
+          const { field, index } = fields.get(fieldName)!;
+          const kidp = B.tmp();
+          const kid = B.tmp();
+          B.line(
+            `${kidp} = getelementptr inbounds [${order.length} x ${S}], ptr %kids, i64 0, i64 ${i}`,
+          );
+          B.line(`${kid} = load ${S}, ptr ${kidp}`);
+          const v = B.tmp();
+          B.line(
+            `${v} = call ${this.valTy(field.type)} @${this.messageReaderHelper(field.type)}(ptr %m, ${S} ${kid}, ptr %fail)`,
+          );
+          const failed = B.tmp();
+          B.line(`${failed} = load i1, ptr %fail`);
+          const lDrop = B.newLabel("dmr.drop");
+          const lStore = B.newLabel("dmr.store");
+          B.condBr(failed, lDrop, lStore);
+          B.startBlock(lDrop);
+          B.line(`call void ${releaseSym(host, t)}(ptr %r0)`);
+          B.terminate(`ret ptr null`);
+          B.startBlock(lStore);
+          const p = B.tmp();
+          B.line(
+            `${p} = getelementptr inbounds %${struct}, ptr %r0, i64 0, i32 ${index + base} ; .${llvmCommentText(fieldName)}`,
+          );
+          const fieldTy = llFieldType(field.type, host.inlineUnions.record(field.type));
+          if (fieldTy === "i8") {
+            const z = B.tmp();
+            B.line(`${z} = zext i1 ${v} to i8`);
+            B.line(`store i8 ${z}, ptr ${p}`);
+          } else {
+            B.line(`store ${fieldTy} ${v}, ptr ${p}`);
+          }
+        });
+        B.terminate(`ret ptr %r0`);
+        break;
+      }
+      case "union": {
+        const def = host.unionsById.get(t.unionId)!;
+        def.arms.forEach((arm, i) => {
+          const lNext = B.newLabel("dmr.next");
+          if (arm.kind === "nullT" || arm.kind === "undefinedT") {
+            const hit = B.tmp();
+            B.line(
+              `${hit} = icmp eq i32 ${kind}, ${arm.kind === "nullT" ? MESSAGE_KIND.NULL : MESSAGE_KIND.UNDEFINED}`,
+            );
+            const lHit = B.newLabel("dmr.unit");
+            B.condBr(hit, lHit, lNext);
+            B.startBlock(lHit);
+            B.terminate(`ret ptr ${host.unitInstanceRef(t.unionId, i)}`);
+            B.startBlock(lNext);
+            return;
+          }
+          if (arm.kind !== "record") {
+            const want =
+              arm.kind === "f64"
+                ? MESSAGE_KIND.NUMBER
+                : arm.kind === "bool"
+                  ? MESSAGE_KIND.BOOL
+                  : MESSAGE_KIND.STRING;
+            const hit = B.tmp();
+            B.line(`${hit} = icmp eq i32 ${kind}, ${want}`);
+            const lHit = B.newLabel("dmr.arm");
+            B.condBr(hit, lHit, lNext);
+            B.startBlock(lHit);
+          }
+          // A record arm that does not match leaves *fail clear for the
+          // next arm, like the checked conversion's next-arm match.
+          const v = B.tmp();
+          B.line(
+            `${v} = call ${this.valTy(arm)} @${this.messageReaderHelper(arm)}(ptr %m, ${S} %n, ptr %fail)`,
+          );
+          if (arm.kind === "record") {
+            const failed = B.tmp();
+            B.line(`${failed} = load i1, ptr %fail`);
+            const lHit = B.newLabel("dmr.arm");
+            const lMiss = B.newLabel("dmr.miss");
+            B.condBr(failed, lMiss, lHit);
+            B.startBlock(lMiss);
+            B.line(`store i1 false, ptr %fail`);
+            B.br(lNext);
+            B.startBlock(lHit);
+          }
+          const u = B.tmp();
+          if (arm.kind === "f64") {
+            host.declare(`declare ptr @scr_union_new_f64(i32, double)`);
+            B.line(`${u} = call ptr @scr_union_new_f64(i32 ${i}, double ${v})`);
+          } else if (arm.kind === "bool") {
+            host.declare(`declare ptr @scr_union_new_bool(i32, i1 zeroext)`);
+            B.line(`${u} = call ptr @scr_union_new_bool(i32 ${i}, i1 ${v})`);
+          } else {
+            const rc = vAdapters(host, arm);
+            host.declare(`declare ptr @scr_union_new_ref(i32, ptr, ptr, ptr, ptr)`);
+            B.line(
+              `${u} = call ptr @scr_union_new_ref(i32 ${i}, ptr ${v}, ptr ${rc.retain}, ptr ${rc.release}, ptr ${traceArg(host, arm)})`,
+            );
+          }
+          B.terminate(`ret ptr ${u}`);
+          B.startBlock(lNext);
+        });
+        B.br(lFail);
+        break;
+      }
+      default:
+        throw new InternalCompilerError(`llvm emitter bug: message reader of ${key}`);
+    }
+    B.startBlock(lFail);
+    B.line(`store i1 true, ptr %fail`);
+    B.terminate(`ret ${retTy} ${dummy}`);
+    this.defs.push(
+      `define internal ${retTy === "i1" ? "zeroext i1" : retTy} @${name}(ptr %m, ${S} %n, ptr %fail) ${FN_ATTRS} { ; message reader for ${llvmCommentText(key)}`,
+      B.render(),
+      `}`,
+      ``,
+    );
+    return name;
+  }
+
   /** The adapter closure body for one TARGET signature: caps[0] is an
    * untraced obj-box owning the dyn function value. */
   dynFuncAdapterHelper(t: IrType & { kind: "func" }): string {

packages/compiler/src/backend/llvm/emit-function.ts

@@ -55,6 +55,7 @@ import { INT32_ABI_SUFFIX, SCALAR_UNION_RESULT } from "./int32-abi.js";
 import { f64Lit } from "./common.js";
 import { RESULT_ENTRY_PREFIX } from "./record-results.js";
 import { emitIntegerClone, emitIntegerDispatcher } from "./integer-clones.js";
+import { runningExtremumUpdates } from "./running-extrema.js";
 
 export function emitFunction(emitter: LlEmitter, fn: IrFunction): string {
   const B = new BlockBuilder();
@@ -81,8 +82,11 @@ export function emitFunction(emitter: LlEmitter, fn: IrFunction): string {
     emitter.currentLocals.set(id, plain);
     emitter.lazyCaptureBoxes.set(id, "");
   }
+  emitter.runningExtrema = emitter.debug === null ? runningExtremumUpdates(fn) : new Set();
   emitter.currentConstantCallbacks =
     emitter.debug === null ? (emitter.constantCallbacks.get(fn.name) ?? new Map()) : new Map();
+  emitter.knownCallbacks.clear();
+  emitter.callbackVersionsEnabled = emitter.debug === null && !fn.async && !fn.generator;
   // Preserve concrete source bindings for debugger inspection. Suspended
   // functions keep the established array lifetime across continuations.
   emitter.streamingSplitsEnabled = emitter.debug === null && !fn.async && !fn.generator;

packages/compiler/src/backend/llvm/emit-module.ts

@@ -35,9 +35,11 @@ import { emitClassMembershipHelper } from "./classes.js";
 import { type RegexMatcherCode, compileRegexMatcher } from "./regex-matchers.js";
 import {
   MAP_ITER_DECL,
+  MAP_SIZE_DECL,
   MAP_ITER_NUM_DECL,
   SCR_MAP_NUM_DEAD,
   NUMBER_MAP_ENTRY_DECL,
+  STRING_MAP_ENTRY_C_DECL,
   STRING_MAP_ENTRY_DECL,
 } from "./map-number-lookup.js";
 import { RUNTIME_ABI_MARKER } from "../runtime-abi.js";
@@ -456,15 +458,18 @@ export function emitModuleParts(emitter: LlEmitter): string[] {
     // RC fast paths test the traced byte (shapes.ts).
     ...(emitter.rcHelpers === null ? [] : [`%ScrMapRc = type { ${emitter.sizeType}, i8, i8, i8 }`]),
     // The complete ScrMap and its entries, read by the inline number-key
-    // lookup (sc_map_entry_f64) and the inline iteration steps
-    // (sc_map_iter_entry, sc_map_iter_entry_num): field 8 is the i32 entry
+    // lookup (sc_map_entry_f64), the inline iteration steps
+    // (sc_map_iter_entry, sc_map_iter_entry_num) and Map.size
+    // (sc_map_size): field 8 is the i32 entry count, field 9 the i32 live
     // count, field 10 the i64 absent-key filter, entries is field 11,
     // nbuckets and buckets fields 13 and 14, the direct index and its i32
     // length fields 15 and 16.
     ...(emitter.decls.has(NUMBER_MAP_ENTRY_DECL) ||
     emitter.decls.has(STRING_MAP_ENTRY_DECL) ||
+    emitter.decls.has(STRING_MAP_ENTRY_C_DECL) ||
     emitter.decls.has(MAP_ITER_DECL) ||
-    emitter.decls.has(MAP_ITER_NUM_DECL)
+    emitter.decls.has(MAP_ITER_NUM_DECL) ||
+    emitter.decls.has(MAP_SIZE_DECL)
       ? [
           `%ScrMapIx = type { ${emitter.sizeType}, i8, i8, i8, i8, i32, ptr, ptr, i32, i32, i64, ptr, i32, i32, ptr, ptr, i32, i32 }`,
         ]
@@ -479,6 +484,11 @@ export function emitModuleParts(emitter: LlEmitter): string[] {
     emitter.decls.has(MAP_ITER_NUM_DECL)
       ? [`%ScrMapEntry = type { i64, i64, i64 }`, `%ScrMapNumEntry = type { i64, i64 }`]
       : []),
+    // A compact-value map's { key, hash, val } entry (scr_map.h ScrMapCEntry):
+    // a 32-bit hash and the value as an address over 8.
+    ...(emitter.decls.has(STRING_MAP_ENTRY_C_DECL)
+      ? [`%ScrMapCEntry = type { i64, i32, i32 }`]
+      : []),
     // The runtime error prefix { rc, vt, name, message, code, cause } and the
     // class-object shape { rc, pre, post, ctor, name } — field reads on
     // builtin errors and classval loads GEP through these.
@@ -545,7 +555,7 @@ export function emitModuleParts(emitter: LlEmitter): string[] {
     ``,
     `@scr_error_vts = external ${tl}global [${RUNTIME_ERROR_CLASSES.size} x %ScrVt]`,
     `declare void @scr_init()`,
-    ...(emitter.usesCompactRefs ? [`declare void @scr_plr_init()`] : []),
+    ...(emitter.compactRegion ? [`declare void @scr_plr_init()`] : []),
     `declare void @scr_lib_init(i32, ptr)`,
     ...(emitter.mod.workers ? [`declare void @scr_runtime_workers_v8()`] : []),
     ...(emitter.stackChecks?.size ? [`declare void @scr_stack_guard_init()`] : []),
@@ -840,7 +850,7 @@ export function emitModuleParts(emitter: LlEmitter): string[] {
     `  call void @scr_init()`,
     // Compressed fields hold addresses in the program-lifetime region, which
     // is reserved below 32 GiB before compiled code runs.
-    ...(emitter.usesCompactRefs ? [`  call void @scr_plr_init()`] : []),
+    ...(emitter.compactRegion ? [`  call void @scr_plr_init()`] : []),
     // Each context (the main thread, every worker) installs its stack
     // guard before running compiled code that checks it.
     ...(emitter.stackChecks?.size ? [`  call void @scr_stack_guard_init()`] : []),
@@ -1293,6 +1303,18 @@ export function helperDefs(emitter: LlEmitter): string[] {
       ``,
     );
   }
+  // Map.size and Set.size read the live entry count (scr_map_size).
+  if (emitter.decls.has(MAP_SIZE_DECL))
+    defs.push(
+      `define internal double @sc_map_size(ptr %m) ${FN_ATTRS} {`,
+      `entry:`,
+      `  %np = getelementptr inbounds %ScrMapIx, ptr %m, i32 0, i32 9`,
+      `  %n = load i32, ptr %np`,
+      `  %nf = uitofp i32 %n to double`,
+      `  ret double %nf`,
+      `}`,
+      ``,
+    );
   // String-key Map/Set lookups test the map's absent-key filter inline
   // (scr_map.c scr_map_filter_bits): a key whose two filter bits are not
   // both set is absent, so most misses on small and medium maps return
@@ -1301,36 +1323,69 @@ export function helperDefs(emitter: LlEmitter): string[] {
   // and the filter reads its bits 44..55, which are the capacity word's
   // own. A key without a cached hash, and every possible hit, take the
   // runtime lookup.
-  if (emitter.decls.has(STRING_MAP_ENTRY_DECL)) {
+  // A compact-value map's lookup (sc_map_entry_str_c) tests the same filter
+  // and calls scr_map_entry_str_c; its iteration step (sc_map_iter_entry_c)
+  // reads 16-byte entries and their 32-bit hash.
+  const stringMapEntry = (helper: string, runtime: string): string[] => [
+    `define internal ptr @${helper}(ptr %m, ptr %k) ${FN_ATTRS} {`,
+    `entry:`,
+    ...(emitter.sizeType === "i64"
+      ? [
+          `  %fp = getelementptr inbounds %ScrMapIx, ptr %m, i32 0, i32 10`,
+          `  %filter = load i64, ptr %fp`,
+          `  %capp = getelementptr inbounds %ScrStr, ptr %k, i32 0, i32 2`,
+          `  %cap = load i64, ptr %capp`,
+          `  %cached = icmp uge i64 %cap, 4294967296`,
+          `  br i1 %cached, label %test, label %slow`,
+          `test:`,
+          `  %s1 = lshr i64 %cap, 44`,
+          `  %i1 = and i64 %s1, 63`,
+          `  %b1 = shl i64 1, %i1`,
+          `  %s2 = lshr i64 %cap, 50`,
+          `  %i2 = and i64 %s2, 63`,
+          `  %b2 = shl i64 1, %i2`,
+          `  %bits = or i64 %b1, %b2`,
+          `  %have = and i64 %filter, %bits`,
+          `  %maybe = icmp eq i64 %have, %bits`,
+          `  br i1 %maybe, label %slow, label %absent`,
+          `absent:`,
+          `  ret ptr null`,
+        ]
+      : [`  br label %slow`]),
+    `slow:`,
+    `  %r = call ptr @${runtime}(ptr %m, ptr %k)`,
+    `  ret ptr %r`,
+    `}`,
+    ``,
+  ];
+  if (emitter.decls.has(STRING_MAP_ENTRY_DECL))
+    defs.push(...stringMapEntry("sc_map_entry_str", "scr_map_entry_str"));
+  if (emitter.decls.has(STRING_MAP_ENTRY_C_DECL)) {
+    const sz = emitter.sizeType;
     defs.push(
-      `define internal ptr @sc_map_entry_str(ptr %m, ptr %k) ${FN_ATTRS} {`,
+      ...stringMapEntry("sc_map_entry_str_c", "scr_map_entry_str_c"),
+      `define internal ptr @sc_map_iter_entry_c(ptr %m, double %i) ${FN_ATTRS} {`,
       `entry:`,
-      ...(emitter.sizeType === "i64"
-        ? [
-            `  %fp = getelementptr inbounds %ScrMapIx, ptr %m, i32 0, i32 10`,
-            `  %filter = load i64, ptr %fp`,
-            `  %capp = getelementptr inbounds %ScrStr, ptr %k, i32 0, i32 2`,
-            `  %cap = load i64, ptr %capp`,
-            `  %cached = icmp uge i64 %cap, 4294967296`,
-            `  br i1 %cached, label %test, label %slow`,
-            `test:`,
-            `  %s1 = lshr i64 %cap, 44`,
-            `  %i1 = and i64 %s1, 63`,
-            `  %b1 = shl i64 1, %i1`,
-            `  %s2 = lshr i64 %cap, 50`,
-            `  %i2 = and i64 %s2, 63`,
-            `  %b2 = shl i64 1, %i2`,
-            `  %bits = or i64 %b1, %b2`,
-            `  %have = and i64 %filter, %bits`,
-            `  %maybe = icmp eq i64 %have, %bits`,
-            `  br i1 %maybe, label %slow, label %absent`,
-            `absent:`,
-            `  ret ptr null`,
-          ]
-        : [`  br label %slow`]),
-      `slow:`,
-      `  %r = call ptr @scr_map_entry_str(ptr %m, ptr %k)`,
-      `  ret ptr %r`,
+      `  %np = getelementptr inbounds %ScrMapIx, ptr %m, i32 0, i32 8`,
+      `  %n = load i32, ptr %np`,
+      `  %nf = uitofp i32 %n to double`,
+      `  %lo = fcmp oge double %i, 0.0`,
+      `  %hi = fcmp olt double %i, %nf`,
+      `  %in = and i1 %lo, %hi`,
+      `  br i1 %in, label %load, label %none`,
+      `load:`,
+      `  %ix = fptoui double %i to ${sz}`,
+      `  %ep = getelementptr inbounds %ScrMapIx, ptr %m, i32 0, i32 11`,
+      `  %entries = load ptr, ptr %ep`,
+      `  %e = getelementptr inbounds %ScrMapCEntry, ptr %entries, ${sz} %ix`,
+      `  %hp = getelementptr inbounds %ScrMapCEntry, ptr %e, i32 0, i32 1`,
+      `  %h = load i32, ptr %hp`,
+      `  %live = icmp ne i32 %h, 0`,
+      `  br i1 %live, label %yes, label %none`,
+      `yes:`,
+      `  ret ptr %e`,
+      `none:`,
+      `  ret ptr null`,
       `}`,
       ``,
     );

packages/compiler/src/backend/llvm/emit-statements.ts

@@ -51,10 +51,11 @@ import {
   emitCountedLoopSafety,
   emitPairedLoopSafety,
 } from "./counted-loops.js";
-import { emitBytesLoopVersionGuard } from "./bytes-loop-versions.js";
+import { emitBytesLoopVersionGuard, type BytesLoopVersion } from "./bytes-loop-versions.js";
 import { mangleLocal } from "../mangle.js";
 import { LlvmUnsupportedError } from "./unsupported.js";
 import type { LlValue } from "./expr-context.js";
+import { everyExprChild, everyStmtChild } from "../../ir/traverse.js";
 import { widenInteger } from "./integer-values.js";
 import { SCALAR_UNION_RESULT } from "./int32-abi.js";
 import { emitLiteralSwitch } from "./switch-dispatch.js";
@@ -76,6 +77,9 @@ import {
 } from "./string-construction.js";
 import { emitStringInputs } from "./string-lifetimes.js";
 
+/** A callback loop version copies the loop; keep the copies small. */
+const MAX_CALLBACK_VERSION_COST = 400;
+
 export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
   const B = emitter.B;
   emitter.frames.push([]);
@@ -469,7 +473,7 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
         B.startBlock(pop);
         const elem = s.arr.type.elem;
         const acc = elemAccess(elem);
-        const raw = emitDenseArrayPop(emitter, arr.name, acc, call, call);
+        const raw = emitDenseArrayPop(emitter, arr.name, acc, elem, call, call);
         if (acc === "ref" && isRefCounted(elem)) {
           const old = B.tmp();
           B.line(`${old} = inttoptr i64 ${raw} to ptr`);
@@ -782,7 +786,12 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
       const trueLabel = B.newLabel("if.t");
       const joinLabel = B.newLabel("if.j");
       const falseLabel = s.else_ ? B.newLabel("if.f") : joinLabel;
-      B.condBr(cond, trueLabel, falseLabel);
+      // A running maximum or minimum is rarely updated; the weights keep
+      // the branch, where a select would make each element wait on the last.
+      const weights = emitter.runningExtrema.has(s)
+        ? `, !prof !{!"branch_weights", i32 1, i32 1000}`
+        : "";
+      B.condBr(cond, trueLabel, falseLabel, weights);
       B.startBlock(trueLabel);
       emitter.emitBlock(s.then);
       B.br(joinLabel);
@@ -795,6 +804,21 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
       break;
     }
     case "while": {
+      const callbacks = callbackVersionBindings(emitter, s);
+      if (callbacks) {
+        emitCallbackVersionedLoop(emitter, s, callbacks);
+        break;
+      }
+      const version =
+        emitter.bytesLoopVersionsEnabled &&
+        emitter.bytesLoopVersioning.size < MAX_BYTES_LOOP_VERSION_DEPTH &&
+        !emitter.bytesLoopVersioning.has(s)
+          ? emitter.matchBytesLoopVersion(s, null)
+          : null;
+      if (version) {
+        emitVersionedLoop(emitter, s, version);
+        break;
+      }
       const workerBudget = emitter.workerLoopBudget(s);
       const le = B.newLabel("loop.e");
       emitter.emitLoopCopies(s, true, le, (exit) => {
@@ -803,6 +827,7 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
         const lp = workerBudget !== null ? B.newLabel("loop.p") : lc;
         B.br(lc);
         B.startBlock(lc);
+        enterLoopHeader(emitter, lc);
         B.condBr(emitter.emitCondition(s.cond), lb, exit);
         B.startBlock(lb);
         emitter.jumpTargets.push({
@@ -827,6 +852,11 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
       break;
     }
     case "doWhile": {
+      const callbacks = callbackVersionBindings(emitter, s);
+      if (callbacks) {
+        emitCallbackVersionedLoop(emitter, s, callbacks);
+        break;
+      }
       const workerBudget = emitter.workerLoopBudget(s);
       // Body first (runs at least once); continue jumps to the CONDITION.
       const le = B.newLabel("loop.e");
@@ -835,6 +865,7 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
         const lc = B.newLabel("loop.c");
         B.br(lb);
         B.startBlock(lb);
+        enterLoopHeader(emitter, lb);
         emitter.jumpTargets.push({
           kind: "loop",
           brkLabel: exit,
@@ -855,6 +886,11 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
       break;
     }
     case "for": {
+      const callbacks = callbackVersionBindings(emitter, s);
+      if (callbacks) {
+        emitCallbackVersionedLoop(emitter, s, callbacks);
+        break;
+      }
       // The init's scope wraps the whole loop (break/continue must NOT
       // release it — scopeDepth captured after the push, C parity).
       const integerArrayLoop =
@@ -879,8 +915,9 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
         !integerLoop && !countedLoop && emitter.countedLoopsEnabled
           ? matchIntegerPairedForLoop(s, emitter.numericLocals, emitter.integerRanges)
           : null;
+      // Byte windows and dense loops reason about one counter.
       const window =
-        countedLoop && emitter.byteWindowsEnabled
+        countedLoop && countedLoop.followers.length === 0 && emitter.byteWindowsEnabled
           ? matchByteWindow(
               s,
               countedLoop,
@@ -898,7 +935,7 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
               length: integerArrayLoop.limitReceiver as IrExpr & { kind: "varRef" },
               range: { min: 0, max: 4294967294 },
             }
-          : countedLoop && !countedLoop.guarded
+          : countedLoop && !countedLoop.guarded && countedLoop.followers.length === 0
             ? countedDenseShape(s, countedLoop)
             : null;
       const dense =
@@ -979,35 +1016,7 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
           : countedLoop;
       const version = versionable ? emitter.matchBytesLoopVersion(s, versionCounted) : null;
       if (version) {
-        const fast = B.newLabel("bytes.version.fast"),
-          slow = B.newLabel("bytes.version.slow"),
-          done = B.newLabel("bytes.version.done");
-        emitBytesLoopVersionGuard(emitter, version, fast, slow);
-        const originalBounds = emitter.bytesBounds,
-          originalOwned = emitter.bytesOwned,
-          originalRanges = emitter.integerRanges;
-        emitter.bytesLoopVersioning.add(s);
-        try {
-          B.startBlock(slow);
-          emitter.emitStmt(s);
-          B.br(done);
-          B.startBlock(fast);
-          emitter.bytesBounds = new Set([...originalBounds, ...version.bounds]);
-          if (version.owned.size > 0)
-            emitter.bytesOwned = new Set([...originalOwned, ...version.owned]);
-          if (version.ranges.size > 0)
-            emitter.integerRanges = new Map([...originalRanges, ...version.ranges]);
-          if (version.counted?.guarded) emitter.provenCountedGuards.add(s);
-          emitter.emitStmt(s);
-          B.br(done);
-        } finally {
-          emitter.bytesBounds = originalBounds;
-          emitter.bytesOwned = originalOwned;
-          emitter.integerRanges = originalRanges;
-          emitter.provenCountedGuards.delete(s);
-          emitter.bytesLoopVersioning.delete(s);
-        }
-        B.startBlock(done);
+        emitVersionedLoop(emitter, s, version);
         break;
       }
       let countedJoin: string | null = null;
@@ -1030,6 +1039,7 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
       let integerSlot: string | null = null;
       let countedLimit: string | null = null;
       const pairedSlots: string[] = [];
+      const followerSlots: string[] = [];
       if (integerLoop) {
         integerSlot = B.slot();
         B.entryAllocas.push(
@@ -1073,6 +1083,23 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
               ? emitter.denseLoop.range
               : countedLoop.range,
         });
+        for (const follower of countedLoop.followers) {
+          const slot = B.slot();
+          B.entryAllocas.push(
+            `${slot} = alloca i64 ; integer induction ${emitter.currentLocals.get(follower.localId)!.name}`,
+          );
+          const value = emitter.emitExpr(follower.start);
+          const followerStart = B.tmp();
+          B.line(`${followerStart} = fptosi double ${value.name} to i64`);
+          B.line(`store i64 ${followerStart}, ptr ${slot}`);
+          followerSlots.push(slot);
+          emitter.integerLoopBindings.set(follower.localId, {
+            slot,
+            type: "i64",
+            signed: true,
+            range: follower.range,
+          });
+        }
         countedLimit = emitCountedLoopLimit(emitter, countedLoop);
       } else if (pairedLoop) {
         for (const counter of [pairedLoop.low, pairedLoop.high]) {
@@ -1135,6 +1162,7 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
           s.update || capturedLets.length > 0 || workerBudget !== null ? B.newLabel("loop.u") : lc;
         B.br(lc);
         B.startBlock(lc);
+        enterLoopHeader(emitter, lc);
         if (integerLoop && integerSlot) {
           const receiver = emitter.emitStableReceiver(integerLoop.limitReceiver, []);
           const lenPtr = B.tmp();
@@ -1212,6 +1240,13 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
             B.line(`${old} = load i64, ptr ${integerSlot}`);
             B.line(`${next} = add nsw i64 ${old}, ${countedLoop.step}`);
             B.line(`store i64 ${next}, ptr ${integerSlot}`);
+            countedLoop.followers.forEach((follower, i) => {
+              const was = B.tmp();
+              const now = B.tmp();
+              B.line(`${was} = load i64, ptr ${followerSlots[i]}`);
+              B.line(`${now} = add nsw i64 ${was}, ${follower.step}`);
+              B.line(`store i64 ${now}, ptr ${followerSlots[i]}`);
+            });
           } else if (pairedLoop) {
             [pairedLoop.low, pairedLoop.high].forEach((counter, i) => {
               const old = B.tmp();
@@ -1227,7 +1262,11 @@ export function emitStmtBody(emitter: LlEmitter, s: IrStmt): void {
       B.startBlock(le);
       emitter.releaseScope(emitter.scopes.pop()!);
       if (integerLoop) emitter.integerLoopBindings.delete(integerLoop.localId);
-      if (countedLoop) emitter.integerLoopBindings.delete(countedLoop.localId);
+      if (countedLoop) {
+        emitter.integerLoopBindings.delete(countedLoop.localId);
+        for (const follower of countedLoop.followers)
+          emitter.integerLoopBindings.delete(follower.localId);
+      }
       if (pairedLoop) {
         emitter.integerLoopBindings.delete(pairedLoop.low.localId);
         emitter.integerLoopBindings.delete(pairedLoop.high.localId);
@@ -1885,10 +1924,148 @@ export function emitSwitch(emitter: LlEmitter, s: IrStmt & { kind: "switch" }):
   B.startBlock(end);
 }
 
+/** The loop copies a callback loop version needs: the bindings the loop
+ * calls that the constant-callback census resolves to one function, each
+ * with that function's direct entry. Only small loops of optimized
+ * synchronous functions, and only bindings declared before the loop,
+ * qualify: the guard reads each binding before the loop runs. Versions do
+ * not nest: a loop inside either copy of a version (including the
+ * versioned loop itself, emitted again for each copy) keeps its calls as
+ * they are, so a loop nest is emitted at most twice. */
+function callbackVersionBindings(
+  emitter: LlEmitter,
+  s: IrStmt & { kind: "for" | "while" | "doWhile" },
+): { ref: IrExpr & { kind: "varRef" }; direct: string }[] | null {
+  if (
+    !emitter.callbackVersionsEnabled ||
+    emitter.currentConstantCallbacks.size === 0 ||
+    emitter.callbackVersioning.size > 0
+  )
+    return null;
+  const found = new Map<string, { ref: IrExpr & { kind: "varRef" }; direct: string }>();
+  // Bindings the loop declares or writes (a callback declared in its body).
+  const bound = new Set<string>();
+  let cost = 0;
+  const expr = (e: IrExpr): boolean => {
+    if (++cost > MAX_CALLBACK_VERSION_COST) return false;
+    if (e.kind === "assignExpr") bound.add(e.localId);
+    if (e.kind === "callValue" && e.callee.kind === "varRef" && !found.has(e.callee.localId)) {
+      const local = emitter.currentLocals.get(e.callee.localId);
+      const target =
+        local && local.tdz !== true ? emitter.knownCallbackTarget(e.callee) : undefined;
+      if (target) found.set(e.callee.localId, { ref: e.callee, direct: target.direct });
+    }
+    return everyExprChild(e, expr, stmt);
+  };
+  const stmt = (x: IrStmt): boolean => {
+    if (++cost > MAX_CALLBACK_VERSION_COST) return false;
+    if (x.kind === "varDecl" || x.kind === "assign" || x.kind === "forOf") bound.add(x.localId);
+    else if (x.kind === "tryCatch" && x.catchLocalId !== null) bound.add(x.catchLocalId);
+    return everyStmtChild(x, expr, stmt);
+  };
+  if (!stmt(s)) return null;
+  const bindings = [...found.values()].filter(({ ref }) => !bound.has(ref.localId));
+  return bindings.length > 0 ? bindings : null;
+}
+
+/** A callback loop version. The guard tests, once before the loop, that
+ * each binding's closure holds its known function: a closure's code
+ * pointer is written only when the closure is built, and the census
+ * resolves only bindings the function never rebinds. The copy where the
+ * guard holds calls those functions directly, with no indirect fallback
+ * that could rewrite the closure or what it captures, so LLVM can keep a
+ * captured scalar the callback updates in a register. The other copy is the
+ * ordinary loop. */
+function emitCallbackVersionedLoop(
+  emitter: LlEmitter,
+  s: IrStmt & { kind: "for" | "while" | "doWhile" },
+  bindings: { ref: IrExpr & { kind: "varRef" }; direct: string }[],
+): void {
+  const B = emitter.B;
+  let ok = "true";
+  for (const { ref, direct } of bindings) {
+    // A borrowed read: the guard only compares the code pointer.
+    const closure = emitter.emitReadReceiver(ref).name;
+    const fnp = B.tmp(),
+      fn = B.tmp(),
+      same = B.tmp();
+    B.line(`${fnp} = getelementptr inbounds %ScrClosure, ptr ${closure}, i64 0, i32 1`);
+    B.line(`${fn} = load ptr, ptr ${fnp}`);
+    B.line(`${same} = icmp eq ptr ${fn}, ${direct}`);
+    if (ok === "true") ok = same;
+    else {
+      const both = B.tmp();
+      B.line(`${both} = and i1 ${ok}, ${same}`);
+      ok = both;
+    }
+  }
+  const fast = B.newLabel("callback.version.fast"),
+    slow = B.newLabel("callback.version.slow"),
+    done = B.newLabel("callback.version.done");
+  B.condBr(ok, fast, slow);
+  emitter.callbackVersioning.add(s);
+  try {
+    B.startBlock(slow);
+    emitter.emitStmt(s);
+    B.br(done);
+    B.startBlock(fast);
+    for (const { ref } of bindings) emitter.knownCallbacks.add(ref.localId);
+    emitter.emitStmt(s);
+    B.br(done);
+  } finally {
+    for (const { ref } of bindings) emitter.knownCallbacks.delete(ref.localId);
+    emitter.callbackVersioning.delete(s);
+  }
+  B.startBlock(done);
+}
+
+/** Entries in a row whose fast copy bailed before a speculative loop site
+ * stops trying it. */
+const SPECULATION_BAILS = 8;
+
 /** Emit a loop's condition, body and update through `emitCopy`, twice
  * when speculative-integers.ts plans a fast integer copy. Both copies
  * share the loop's setup and exit; the ordinary copy comes first so the
  * fast copy is only emitted when every resume point exists. */
+/** A typed-array loop version: the guard, then the checked copy, which
+ * runs whenever the guard fails, and the copy whose accesses the guard
+ * proves in bounds (or thread-owned). */
+function emitVersionedLoop(
+  emitter: LlEmitter,
+  s: IrStmt & { kind: "for" | "while" },
+  version: BytesLoopVersion,
+): void {
+  const B = emitter.B;
+  const fast = B.newLabel("bytes.version.fast"),
+    slow = B.newLabel("bytes.version.slow"),
+    done = B.newLabel("bytes.version.done");
+  emitBytesLoopVersionGuard(emitter, version, fast, slow);
+  const originalBounds = emitter.bytesBounds,
+    originalOwned = emitter.bytesOwned,
+    originalRanges = emitter.integerRanges;
+  emitter.bytesLoopVersioning.add(s);
+  try {
+    B.startBlock(slow);
+    emitter.emitStmt(s);
+    B.br(done);
+    B.startBlock(fast);
+    emitter.bytesBounds = new Set([...originalBounds, ...version.bounds]);
+    if (version.owned.size > 0) emitter.bytesOwned = new Set([...originalOwned, ...version.owned]);
+    if (version.ranges.size > 0)
+      emitter.integerRanges = new Map([...originalRanges, ...version.ranges]);
+    if (version.counted?.guarded) emitter.provenCountedGuards.add(s);
+    emitter.emitStmt(s);
+    B.br(done);
+  } finally {
+    emitter.bytesBounds = originalBounds;
+    emitter.bytesOwned = originalOwned;
+    emitter.integerRanges = originalRanges;
+    emitter.provenCountedGuards.delete(s);
+    emitter.bytesLoopVersioning.delete(s);
+  }
+  B.startBlock(done);
+}
+
 export function emitLoopCopies(
   emitter: LlEmitter,
   loop: Extract<IrStmt, { kind: "while" | "doWhile" | "for" }>,
@@ -1939,23 +2116,66 @@ export function emitLoopCopies(
       ok = both;
     }
   }
+  // Each entry whose fast copy bails counts at the loop site, and a fast
+  // copy that completes a speculated write and leaves the loop clears the
+  // count. After SPECULATION_BAILS bailing entries in a row, the site runs
+  // the ordinary copy only. The count is a hint: both copies give the same
+  // results, and a race between workers loses at most an update.
+  const bails = `@scr.spec.bails.${emitter.speculativeLoopSites++}`;
+  emitter.declare(`${bails} = internal global i8 0`);
+  const count = B.tmp(),
+    trying = B.tmp();
+  B.line(`${count} = load atomic i8, ptr ${bails} unordered, align 1`);
+  B.line(`${trying} = icmp ult i8 ${count}, ${SPECULATION_BAILS}`);
+  if (ok === "true") ok = trying;
+  else {
+    const both = B.tmp();
+    B.line(`${both} = and i1 ${ok}, ${trying}`);
+    ok = both;
+  }
   const fast = B.newLabel("spec.fast"),
     slow = B.newLabel("spec.slow");
   B.condBr(ok, fast, slow);
   const resume = new Map<IrStmt, { label: string; placed: boolean }>();
   for (const s of plan.writes) resume.set(s, { label: B.newLabel("spec.resume"), placed: false });
+  // A failed check finishes its iteration in a third copy, entered only
+  // there: it re-executes the statement and the rest of the body and the
+  // update, then enters the ordinary copy through its header. Jumping
+  // into the middle of the ordinary copy instead would give that loop a
+  // second entry, and LLVM does not optimize an irreducible loop.
+  const points = [...resume.values()];
+  let header: string | null = null;
   B.startBlock(slow);
+  emitter.speculationHeader = (label) => {
+    header = label;
+  };
+  try {
+    emitCopy(exit);
+  } finally {
+    emitter.speculationHeader = null;
+  }
+  if (header === null)
+    throw new InternalCompilerError("llvm emitter bug: speculative loop copy without a header");
+  B.startBlock(B.newLabel("spec.tail"));
   emitter.speculationResume = resume;
+  emitter.speculationHeader = () => {
+    B.br(header!);
+    B.startBlock(B.newLabel("spec.unused"));
+  };
   try {
     emitCopy(exit);
   } finally {
     emitter.speculationResume = null;
+    emitter.speculationHeader = null;
   }
   B.startBlock(fast);
-  if (![...resume.values()].every((r) => r.placed)) {
+  if (!points.every((r) => r.placed)) {
     B.br(slow);
     return;
   }
+  const ran = B.slot();
+  B.entryAllocas.push(`${ran} = alloca i1 ; speculated write completed`);
+  B.line(`store i1 false, ptr ${ran}`);
   for (const id of plan.locals.keys()) {
     const shadow = B.slot();
     B.entryAllocas.push(
@@ -1992,22 +2212,43 @@ export function emitLoopCopies(
     writes: plan.writes,
     resume: new Map([...resume].map(([s, r]) => [s, r.label])),
     deferred,
+    bails,
+    ran,
   };
   try {
-    if (deferred.size === 0) emitCopy(exit);
-    else {
-      const leave = B.newLabel("spec.leave");
-      emitCopy(leave);
-      B.startBlock(leave);
-      emitter.writeBackDeferred(deferred);
-      B.br(exit);
-    }
+    const leave = B.newLabel("spec.leave");
+    emitCopy(leave);
+    B.startBlock(leave);
+    emitter.writeBackDeferred(deferred);
+    // An entry that never ran a speculated write (a loop of no iterations)
+    // says nothing about the site.
+    const wrote = B.tmp(),
+      left = B.tmp(),
+      counted = B.tmp(),
+      both = B.tmp(),
+      clear = B.newLabel("spec.clear");
+    B.line(`${wrote} = load i1, ptr ${ran}`);
+    B.line(`${left} = load atomic i8, ptr ${bails} unordered, align 1`);
+    B.line(`${counted} = icmp ne i8 ${left}, 0`);
+    B.line(`${both} = and i1 ${wrote}, ${counted}`);
+    B.condBr(both, clear, exit);
+    B.startBlock(clear);
+    B.line(`store atomic i8 0, ptr ${bails} unordered, align 1`);
+    B.br(exit);
   } finally {
     emitter.speculation = null;
     for (const id of plan.locals.keys()) emitter.integerLoopBindings.delete(id);
   }
 }
 
+/** At the top of a loop copy's header: lets a speculative loop find its
+ * ordinary copy's header, and keeps its third copy out of the loop. */
+function enterLoopHeader(emitter: LlEmitter, header: string): void {
+  const dispatch = emitter.speculationHeader;
+  emitter.speculationHeader = null;
+  dispatch?.(header);
+}
+
 /** A proven integer loop (speculative-integers.ts) for this loop, or null.
  * A shadowed local's double is stale until the loop is left, which only
  * the loop's exit, a return and an exception do: the loop is planned only
@@ -2134,7 +2375,8 @@ export function emitSpeculativeWrite(
   if (emitter.frames.pop()!.length > 0)
     throw new InternalCompilerError("llvm emitter bug: speculative write owns a temporary");
   B.line(`store i64 ${result}, ptr ${binding.slot}`);
-  const deferred = emitter.speculation!.deferred;
+  const { deferred, bails: site, ran } = emitter.speculation!;
+  if (ran !== undefined) B.line(`store i1 true, ptr ${ran}`);
   if (!deferred.has(target.localId)) {
     const number = B.tmp();
     B.line(`${number} = sitofp i64 ${result} to double`);
@@ -2145,6 +2387,14 @@ export function emitSpeculativeWrite(
   B.br(done);
   B.startBlock(failed);
   emitter.writeBackDeferred(deferred);
+  if (site !== undefined) {
+    const count = B.tmp(),
+      next = B.tmp();
+    emitter.declare("declare i8 @llvm.uadd.sat.i8(i8, i8)");
+    B.line(`${count} = load atomic i8, ptr ${site} unordered, align 1`);
+    B.line(`${next} = call i8 @llvm.uadd.sat.i8(i8 ${count}, i8 1)`);
+    B.line(`store atomic i8 ${next}, ptr ${site} unordered, align 1`);
+  }
   B.br(resume!);
   B.startBlock(done);
 }

packages/compiler/src/backend/llvm/emitter.ts

@@ -72,6 +72,7 @@ import { scalarizeNumericRecords } from "../../ir/scalar-records.js";
 import { addRecordResultEntries } from "./record-results.js";
 import { specializeCallbackCalls } from "../../ir/callback-specialization.js";
 import { specializeNumericCalls } from "../../ir/numeric-call-specialization.js";
+import { versionLoopBoundParameters } from "../../ir/parameter-versions.js";
 import { everyExpr, everyExprChild, everyStmtChild, everyStmtList } from "../../ir/traverse.js";
 import { INT32_RANGE, type IntegerRange, type IntegerRanges } from "../../ir/integer-ranges.js";
 import { unshareNodes } from "../../ir/unshare.js";
@@ -442,6 +443,14 @@ export function lowRegionTarget(platform: string, sanitize: boolean): boolean {
   return platform === "linux" && !sanitize;
 }
 
+/** Function versions on loop-bounding number parameters
+ * (ir/parameter-versions.ts). Library builds have no int32 entries, and a
+ * module that observes call stacks could see the version's frame. */
+function versionParameters(mod: IrModule): IrModule {
+  if (mod.lib !== undefined || observesStacks(mod)) return mod;
+  return versionLoopBoundParameters(mod, mangleFunction);
+}
+
 export function emitLlvmModule(input: IrModule, options: LlvmTargetOptions = {}): string {
   // Facts are keyed by node identity: emit the same module whether it was
   // lowered in memory or read back from its serialized form.
@@ -449,20 +458,22 @@ export function emitLlvmModule(input: IrModule, options: LlvmTargetOptions = {})
   // Keep source storage intact for debugger inspection in dev builds.
   return new LlEmitter(
     options.debugSources === undefined
-      ? addRecordResultEntries(
-          scalarizeNumericRecords(
-            specializeCallbackCalls(
-              specializeNumericCalls(
-                foldConstantGlobals(
-                  copyStableCaptures(
-                    resolveSelfCaptures(
-                      hoistFinalFieldReads(freezeInitOnlyGlobals(dropUnwrittenPropertyBags(mod))),
+      ? versionParameters(
+          addRecordResultEntries(
+            scalarizeNumericRecords(
+              specializeCallbackCalls(
+                specializeNumericCalls(
+                  foldConstantGlobals(
+                    copyStableCaptures(
+                      resolveSelfCaptures(
+                        hoistFinalFieldReads(freezeInitOnlyGlobals(dropUnwrittenPropertyBags(mod))),
+                      ),
                     ),
                   ),
+                  mangleFunction,
                 ),
                 mangleFunction,
               ),
-              mangleFunction,
             ),
           ),
         )
@@ -481,20 +492,22 @@ export function emitLlvmModuleSource(
   const mod = unshareNodes(input);
   const parts = new LlEmitter(
     options.debugSources === undefined
-      ? addRecordResultEntries(
-          scalarizeNumericRecords(
-            specializeCallbackCalls(
-              specializeNumericCalls(
-                foldConstantGlobals(
-                  copyStableCaptures(
-                    resolveSelfCaptures(
-                      hoistFinalFieldReads(freezeInitOnlyGlobals(dropUnwrittenPropertyBags(mod))),
+      ? versionParameters(
+          addRecordResultEntries(
+            scalarizeNumericRecords(
+              specializeCallbackCalls(
+                specializeNumericCalls(
+                  foldConstantGlobals(
+                    copyStableCaptures(
+                      resolveSelfCaptures(
+                        hoistFinalFieldReads(freezeInitOnlyGlobals(dropUnwrittenPropertyBags(mod))),
+                      ),
                     ),
                   ),
+                  mangleFunction,
                 ),
                 mangleFunction,
               ),
-              mangleFunction,
             ),
           ),
         )
@@ -641,9 +654,11 @@ export class LlEmitter {
    * 32-bit references to compact class instances (LlClassMeta.compressed):
    * loadField/loadRef decode them and storeField/storeRef encode them. */
   readonly compressedFieldPtrs = new Set<string>();
-  /** Whether a class has compressed fields: main reserves the region before
-   * compiled code runs (scr_plr_init). */
-  usesCompactRefs = false;
+  /** Compact class instances live in the program-lifetime region below
+   * 32 GiB (LlvmTargetOptions.lowRegion, and the program has compact
+   * classes): main reserves it before compiled code runs (scr_plr_init), and
+   * fields and arrays of compactRefType hold 32-bit references. */
+  compactRegion = false;
 
   /** Native class fields with different property names cannot occupy the
    * same slot of one object. Inherited views of the same property share a
@@ -831,6 +846,15 @@ export class LlEmitter {
   readonly callLifetimes: CallLifetimes;
   readonly constantCallbacks: Map<string, Map<string, string>>;
   currentConstantCallbacks: ReadonlyMap<string, string> = new Map();
+  /** The current function's running maximum and minimum updates, whose
+   * branches are weighted as rarely taken (running-extrema.ts). */
+  runningExtrema: ReadonlySet<IrStmt> = new Set();
+  /** Callback bindings whose closures an enclosing callback loop version
+   * proved to hold their known function: calls take the direct entry with
+   * no fallback (emitCallbackVersionedLoop). */
+  knownCallbacks = new Set<string>();
+  readonly callbackVersioning = new Set<IrStmt>();
+  callbackVersionsEnabled = false;
   readonly stackCallbacks: StackCallbacks;
   readonly receiverReaders: AmbientReceiverReaders;
   readonly stackCaptures: StackCaptures;
@@ -1102,9 +1126,20 @@ export class LlEmitter {
     resume: Map<IrStmt, string>;
     /** Globals whose double is written back only when the copy is left. */
     deferred: Set<string>;
+    /** The loop site's count of bailing entries in a row (a global), and
+     * whether this entry completed a speculated write (a slot). A proven
+     * integer loop has neither. */
+    bails?: string;
+    ran?: string;
   } | null = null;
+  /** Speculative loop sites numbered so far in the module. */
+  speculativeLoopSites = 0;
   /** The ordinary copy being emitted: resume labels still to place. */
   speculationResume: Map<IrStmt, { label: string; placed: boolean }> | null = null;
+  /** Run once at the top of the next loop copy's header
+   * (`enterLoopHeader`): records the ordinary copy's header, or sends the
+   * third copy's header there. */
+  speculationHeader: ((header: string) => void) | null = null;
   /** The function being emitted, for speculative globals. */
   speculativeFunction = "";
   /** Every function that writes each number global (computed on demand). */
@@ -1459,6 +1494,8 @@ export class LlEmitter {
       }
     }
     this.shapeHost = {
+      compactArrayElem: (elem) => this.compactArrayElem(elem),
+      compactRegion: () => this.compactRegion,
       sizeType: this.sizeType,
       cycleBufOffset: this.cycleBufOffset,
       tracedShapes: this.tracedShapes,
@@ -1588,22 +1625,19 @@ export class LlEmitter {
           ? (cls, i, isCompact) => {
               const f = cls.fields[i]!;
               if (this.inlineUnions.classField(cls.name, f.name)) return false;
-              const t = f.type;
-              if (t.kind === "object") return isCompact(t.className);
-              if (t.kind !== "union") return false;
-              const single = this.nullableUnions.single(t.unionId);
-              if (single !== null)
-                return (
-                  single.nullTag < 0 &&
-                  single.arm.kind === "object" &&
-                  isCompact(single.arm.className)
-                );
-              const nullable = this.nullableFields.get(cls.name, f.name);
+              if (this.compactRefType(f.type, isCompact)) return true;
+              const nullable =
+                f.type.kind === "union" && this.nullableUnions.single(f.type.unionId) === null
+                  ? this.nullableFields.get(cls.name, f.name)
+                  : null;
               return nullable !== null && isCompact(nullable.arm.className);
             }
           : undefined,
       );
-    this.usesCompactRefs = [...this.classMeta.values()].some((m) => m.compressed.some(Boolean));
+    this.compactRegion =
+      mod.lib === undefined &&
+      options.lowRegion === true &&
+      [...this.classMeta.values()].some((m) => m.compact);
     for (const [name, rec] of RUNTIME_ERROR_CLASSES) {
       const meta = this.classMeta.get(name);
       if (!meta) break; // hand-written IR without the builtin defs: no stamps
@@ -1896,14 +1930,14 @@ export class LlEmitter {
 
   /** Whether a fiberless body running on its caller's stack needs the
    * frame scr_async_inline_enter/exit keep: it isolates the Error.stack
-   * frame chain, which only stack-observing programs push, and the
-   * AsyncLocalStorage context, which only programs that enter stores
-   * change (RuntimeFeatures asyncContext), as a fresh fiber would. Other
-   * programs run the body with a plain call. The frame also counts the
-   * bodies running on a fiber's stack for the runtime's trap on a fiberless
-   * body that suspends. */
+   * frame chain, which only stack-observing programs push, as a fresh fiber
+   * would. Other programs run the body with a plain call. The body runs in
+   * its caller's AsyncLocalStorage context either way, as Node runs an async
+   * body up to its first await. The frame also counts the bodies running on
+   * a fiber's stack for the runtime's trap on a fiberless body that
+   * suspends. */
   get fiberlessFrames(): boolean {
-    return this.stackTraces || this.schedulesInContext;
+    return this.stackTraces;
   }
 
   /** The spawn wrapper of a fiberless async function: runs the body on the
@@ -2215,7 +2249,7 @@ export class LlEmitter {
       B.condBr(thrown, rejected, clean);
       B.startBlock(clean);
       if (acc === "ref") this.toHeap(value);
-      this.arrPush(values, acc, value.name);
+      this.arrPush(values, acc, value.name, elem);
       B.br(next);
       B.startBlock(rejected);
       const promise = B.tmp();
@@ -3568,6 +3602,30 @@ export class LlEmitter {
     return { ptr: p, type, inline: this.inlineUnions.classField(className, field), compressed };
   }
 
+  /** Whether values of `t` are NULL or a compact class instance: `C`,
+   * `C | undefined` or `C | null` for a compact class `C`. `C | null |
+   * undefined` is not: its null is a sentinel outside the region. */
+  compactRefType(
+    t: IrType,
+    isCompact: (className: string) => boolean = (name) =>
+      this.classMeta.get(name)?.compact === true,
+  ): boolean {
+    if (t.kind === "object") return isCompact(t.className);
+    if (t.kind !== "union") return false;
+    const single = this.nullableUnions.single(t.unionId);
+    return (
+      single !== null &&
+      single.nullTag < 0 &&
+      single.arm.kind === "object" &&
+      isCompact(single.arm.className)
+    );
+  }
+
+  /** Whether arrays of `elem` hold 32-bit references (SCR_ELEM_CREF). */
+  compactArrayElem(elem: IrType): boolean {
+    return this.compactRegion && this.compactRefType(elem);
+  }
+
   /** Loads the reference a field pointer addresses: a pointer, or the
    * decoded 32-bit reference of a compressed field (compressedFieldPtrs).
    * `tagged`: the load carries the field's alias tags. */
@@ -3832,7 +3890,7 @@ export class LlEmitter {
   /** A binding's storage: a module global, a plain local slot, or a boxed
    * local (the slot holds the capture BOX; access goes through it). */
   matchBytesLoopVersion(
-    s: IrStmt & { kind: "for" },
+    s: IrStmt & { kind: "for" | "while" },
     counted: IntegerCountedForLoop | null,
   ): ReturnType<typeof matchBytesLoopVersion> {
     const fn = this.bytesLoopFunction;
@@ -3901,6 +3959,25 @@ export class LlEmitter {
     return b;
   }
 
+  /** The function a call through `callee` is known to reach (a literal
+   * closure, or a binding the constant-callback census resolves) and the
+   * entry it calls directly. Async and generator functions stay indirect. */
+  knownCallbackTarget(callee: IrExpr): { known: IrFunction; direct: string } | undefined {
+    const knownName =
+      callee.kind === "closure"
+        ? callee.fnName
+        : callee.kind === "varRef"
+          ? this.currentConstantCallbacks.get(callee.localId)
+          : undefined;
+    const known = knownName ? this.fnByName.get(knownName) : undefined;
+    if (!known || known.async || known.generator) return undefined;
+    if (known.captures === undefined) {
+      this.fnValues.add(known.name);
+      return { known, direct: `@${mangleWrapper(known.name)}` };
+    }
+    return { known, direct: `@${this.callTarget(known.name)}` };
+  }
+
   /** The payload slot of a capture box (ScrBox.slot, field 5). */
   boxSlot(box: string): string {
     const slot = this.B.tmp();
@@ -3914,12 +3991,18 @@ export class LlEmitter {
     const r = B.tmp();
     // Scalar payloads are read in place (scr_box_get_f64/bool are a
     // memcpy and a nonzero test of the same slot), so LLVM can keep a
-    // captured number in a register across a loop of calls.
+    // captured number in a register across a loop of calls. They have an
+    // alias category of their own: every other access to a box's payload
+    // is untagged or a runtime call.
     if (acc === "f64") {
-      B.line(`${r} = load double, ptr ${this.boxSlot(box)}`);
+      B.line(
+        `${r} = load double, ptr ${this.boxSlot(box)}${this.memoryAliasAttachment("box:scalar")}`,
+      );
     } else if (acc === "bool") {
       const raw = B.tmp();
-      B.line(`${raw} = load i64, ptr ${this.boxSlot(box)}`);
+      B.line(
+        `${raw} = load i64, ptr ${this.boxSlot(box)}${this.memoryAliasAttachment("box:scalar")}`,
+      );
       B.line(`${r} = icmp ne i64 ${raw}, 0`);
     } else {
       this.declare(`declare ptr @scr_box_get_ref(ptr)`);
@@ -3933,11 +4016,15 @@ export class LlEmitter {
     const B = this.B;
     const acc = boxAccess(t);
     if (acc === "f64") {
-      B.line(`store double ${value}, ptr ${this.boxSlot(box)}`);
+      B.line(
+        `store double ${value}, ptr ${this.boxSlot(box)}${this.memoryAliasAttachment("box:scalar")}`,
+      );
     } else if (acc === "bool") {
       const raw = B.tmp();
       B.line(`${raw} = zext i1 ${value} to i64`);
-      B.line(`store i64 ${raw}, ptr ${this.boxSlot(box)}`);
+      B.line(
+        `store i64 ${raw}, ptr ${this.boxSlot(box)}${this.memoryAliasAttachment("box:scalar")}`,
+      );
     } else {
       this.declare(`declare void @scr_box_set_ref(ptr, ptr)`);
       B.line(`call void @scr_box_set_ref(ptr ${box}, ptr ${value})`);
@@ -3986,7 +4073,7 @@ export class LlEmitter {
     const acc = boxAccess(t);
     const cell = B.tmp();
     B.line(`${cell} = ${arrNewCall(this.shapeHost, t, "1")} ; TDZ cell`);
-    this.arrPush(cell, acc === "bool" ? "bool" : "f64", value);
+    this.arrPush(cell, acc === "bool" ? "bool" : "f64", value, null);
     this.declare(`declare void @scr_box_set_ref(ptr, ptr)`);
     B.line(`call void @scr_box_set_ref(ptr ${box}, ptr ${cell})`);
   }
@@ -6136,8 +6223,8 @@ export class LlEmitter {
     return tagInSet(this, uName, unionId, tags);
   }
 
-  arrPush(arr: string, acc: "f64" | "bool" | "ref", value: string): string {
-    return arrPush(this, arr, acc, value);
+  arrPush(arr: string, acc: "f64" | "bool" | "ref", value: string, element: IrType | null): string {
+    return arrPush(this, arr, acc, value, element);
   }
 
   emitArrayCopyLoop(dst: string, src: string, acc: "f64" | "bool" | "ref"): void {

packages/compiler/src/backend/llvm/expr-calls.ts

@@ -29,7 +29,6 @@ import {
   mangleClassStruct,
   mangleFnClosure,
   mangleFunction,
-  mangleWrapper,
   mangleVtStruct,
   mangleAsyncDirectSpawn,
 } from "../mangle.js";
@@ -839,21 +838,9 @@ export function emitCallExpr(
         host.declare("declare void @scr_dyn_this_push_dyn(ptr)");
         B.line(`call void @scr_dyn_this_push_dyn(ptr ${receiver?.name ?? "null"})`);
       };
-      const knownName =
-        e.callee.kind === "closure"
-          ? e.callee.fnName
-          : e.callee.kind === "varRef"
-            ? host.currentConstantCallbacks.get(e.callee.localId)
-            : undefined;
-      const candidate = knownName ? host.fnByName.get(knownName) : undefined;
-      const known = candidate && !candidate.async && !candidate.generator ? candidate : undefined;
-      let direct: string | undefined;
-      if (known) {
-        if (known.captures === undefined) {
-          host.fnValues.add(known.name);
-          direct = `@${mangleWrapper(known.name)}`;
-        } else direct = `@${host.callTarget(known.name)}`;
-      }
+      const target = host.knownCallbackTarget(e.callee);
+      const known = target?.known;
+      const direct = target?.direct;
       // A known closure body that borrows reference parameters is entered
       // directly with lent arguments, as a direct call to a borrowing body
       // is: an argument is read without a reference when neither a later
@@ -939,7 +926,13 @@ export function emitCallExpr(
       let pending = host.indirectMayThrow;
       let pendingGuard: string | undefined;
       let t: string;
-      if (direct && e.callee.kind === "closure") {
+      // A literal closure, or a binding an enclosing callback loop version
+      // proved to hold its known function, enters it directly.
+      if (
+        direct &&
+        (e.callee.kind === "closure" ||
+          (e.callee.kind === "varRef" && host.knownCallbacks.has(e.callee.localId)))
+      ) {
         t = invoke(lending ?? direct, !host.receiverReaders.ignores(known!));
         if (quiet) pending = false;
       } else {

packages/compiler/src/backend/llvm/expr-containers.ts

@@ -31,8 +31,10 @@ import {
   emitMapIterCount,
   emitMapIterEntry,
   emitMapIterSlot,
+  compactMapValues,
   mapEntryLayout,
   emitMapIterStart,
+  emitMapSize,
   emitNumberMapGetRef,
   emitNumberMapGetScalar,
   emitNumberMapHas,
@@ -102,13 +104,17 @@ export function tagInSet(
   return acc;
 }
 
+/** `element`: the array's element type, or null for arrays whose
+ * elements are not compact class references (dense-array-access.ts
+ * slotKind). */
 export function arrPush(
   host: LlvmEmitterContext,
   arr: string,
   acc: "f64" | "bool" | "ref",
   value: string,
+  element: IrType | null,
 ): string {
-  return emitDenseArrayPush(host, arr, acc, value);
+  return emitDenseArrayPush(host, arr, acc, element, value);
 }
 
 /** Move evaluated values through one bounded slot buffer per call site. */
@@ -116,6 +122,7 @@ export function emitArrayValues(
   host: LlvmEmitterContext,
   arr: string,
   acc: "f64" | "bool" | "ref",
+  element: IrType,
   values: LlValue[],
   prepend = false,
   sharedBuffer?: string,
@@ -129,7 +136,7 @@ export function emitArrayValues(
     return result;
   }
   if (values.length === 1) {
-    if (!prepend) return arrPush(host, arr, acc, values[0]!.name);
+    if (!prepend) return arrPush(host, arr, acc, values[0]!.name, element);
     const ty = acc === "f64" ? "double" : acc === "bool" ? "i1" : "ptr";
     host.declare(
       `declare double @scr_arr_unshift_${acc}(ptr, ${ty}${acc === "bool" ? " zeroext" : ""})`,
@@ -628,7 +635,7 @@ export function emitArrIntrinsic(
       // no-op zero-argument call.
       const vs = e.args.map((a) => host.emitExpr(a));
       host.emitPublishedArrayGuard(r.name, e.receiver.type, 1, f64Lit(0), f64Lit(vs.length));
-      return { name: emitArrayValues(host, r.name, acc, vs), type: e.type };
+      return { name: emitArrayValues(host, r.name, acc, elem, vs), type: e.type };
     }
     case "pushSpread": {
       // `a.push(...src)`: append src's elements in order (borrowed src,
@@ -660,7 +667,7 @@ export function emitArrIntrinsic(
       // from right to left so the final front order is source order.
       const vs = e.args.map((a) => host.emitExpr(a));
       host.emitPublishedArrayGuard(r.name, e.receiver.type, 4, f64Lit(0), f64Lit(vs.length));
-      return { name: emitArrayValues(host, r.name, acc, vs, true), type: e.type };
+      return { name: emitArrayValues(host, r.name, acc, elem, vs, true), type: e.type };
     }
     case "unshiftSpread": {
       // The runtime snapshots the borrowed source and handles self-spread.
@@ -702,7 +709,7 @@ export function emitArrIntrinsic(
       let slowLabel = "";
       if (method === "pop") {
         slowLabel = B.newLabel("remove.slow");
-        denseRaw = emitDenseArrayPop(host, r.name, acc, la, slowLabel);
+        denseRaw = emitDenseArrayPop(host, r.name, acc, elem, la, slowLabel);
         denseLabel = B.currentLabel();
         B.br(lp);
         B.startBlock(slowLabel);
@@ -771,7 +778,7 @@ export function emitArrIntrinsic(
       // by content, everything else by pointer). Strict equality. Arrays of
       // objects and strings scan inline (array-search.ts).
       const v = host.emitExpr(e.args[0]!);
-      const search = acc === "ref" ? arraySearchKind(elem) : null;
+      const search = acc === "ref" ? arraySearchKind(elem, host.compactArrayElem(elem)) : null;
       if (search !== null) {
         host.arraySearchKinds.add(search);
         const t = B.tmp();
@@ -789,7 +796,7 @@ export function emitArrIntrinsic(
       // Borrowed needle, SameValueZero (NaN matches NaN). For the inline
       // searches SameValueZero is strict equality.
       const v = host.emitExpr(e.args[0]!);
-      const search = acc === "ref" ? arraySearchKind(elem) : null;
+      const search = acc === "ref" ? arraySearchKind(elem, host.compactArrayElem(elem)) : null;
       if (search !== null) {
         host.arraySearchKinds.add(search);
         const at = B.tmp(),
@@ -1060,8 +1067,10 @@ function newCollection(host: LlvmEmitterContext, key: IrType, value: IrType): st
   const kind = mapKeyKindNum(key, arms);
   const m = B.tmp();
   host.declare(`declare ptr @scr_map_new(i32, i32, ptr)`);
+  // SCR_MAP_VAL_CREF (3): string keys and compact values (compactMapValues).
+  const valKind = compactMapValues(host, key, value) ? 3 : mapValKindNum(value);
   B.line(
-    `${m} = call ptr @scr_map_new(i32 ${kind}, i32 ${mapValKindNum(value)}, ptr ${collectionOps(host, key, value)})`,
+    `${m} = call ptr @scr_map_new(i32 ${kind}, i32 ${valKind}, ptr ${collectionOps(host, key, value)})`,
   );
   return m;
 }
@@ -1124,6 +1133,9 @@ export function emitMapLikeIntrinsic(
   const key = receiverType.kind === "map" ? receiverType.key : receiverType.elem;
   const kAcc = mapKeyAccess(key);
   const kTy = mapKeyParamType(kAcc);
+  // The map keeps compact values in 16-byte entries (SCR_MAP_VAL_CREF).
+  const compact = receiverType.kind === "map" && compactMapValues(host, key, receiverType.value);
+  const layout = mapEntryLayout(key, compact);
   const method = e.method;
   // A published Map or Set rejects mutation (the guard precedes the
   // operands, which each method evaluates itself).
@@ -1287,7 +1299,7 @@ export function emitMapLikeIntrinsic(
         if (numberKey !== null) {
           raw = emitNumberMapGetRef(host, r.name, numberKey, value);
         } else if (stringKey !== null) {
-          raw = emitStringMapGetRef(host, r.name, stringKey, value);
+          raw = emitStringMapGetRef(host, r.name, stringKey, value, compact);
         } else {
           host.declare(`declare ptr @scr_map_get_${kAcc}_ref(ptr, ${kTy})`);
           raw = B.tmp();
@@ -1365,7 +1377,7 @@ export function emitMapLikeIntrinsic(
         return host.wrapNullable(raw, raw, value, valueTag, e.type, undefTag);
       }
       if (stringKey !== null && isRefCounted(value)) {
-        const raw = emitStringMapGetRef(host, r.name, stringKey, value);
+        const raw = emitStringMapGetRef(host, r.name, stringKey, value, compact);
         return host.wrapNullable(raw, raw, value, valueTag, e.type, undefTag);
       }
       host.declare(`declare ptr @scr_map_get_${kAcc}_ref(ptr, ${kTy})`);
@@ -1413,7 +1425,8 @@ export function emitMapLikeIntrinsic(
     case "has": {
       const k = borrowInputs ? host.emitReadReceiver(e.args[0]!) : host.emitExpr(e.args[0]!);
       if (kAcc === "f64") return { name: emitNumberMapHas(host, r.name, k.name), type: e.type };
-      if (kAcc === "str") return { name: emitStringMapHas(host, r.name, k.name), type: e.type };
+      if (kAcc === "str")
+        return { name: emitStringMapHas(host, r.name, k.name, compact), type: e.type };
       host.declare(`declare zeroext i1 @scr_map_has_${kAcc}(ptr, ${kTy})`);
       const t = B.tmp();
       B.line(`${t} = call zeroext i1 @scr_map_has_${kAcc}(ptr ${r.name}, ${kTy} ${k.name})`);
@@ -1426,12 +1439,8 @@ export function emitMapLikeIntrinsic(
       B.line(`${t} = call zeroext i1 @scr_map_delete_${kAcc}(ptr ${r.name}, ${kTy} ${k.name})`);
       return { name: t, type: e.type };
     }
-    case "size": {
-      host.declare(`declare double @scr_map_size(ptr)`);
-      const t = B.tmp();
-      B.line(`${t} = call double @scr_map_size(ptr ${r.name})`);
-      return { name: t, type: e.type };
-    }
+    case "size":
+      return { name: emitMapSize(host, r.name), type: e.type };
     case "clear":
       host.declare(`declare void @scr_map_clear(ptr)`);
       B.line(`call void @scr_map_clear(ptr ${r.name})`);
@@ -1442,7 +1451,7 @@ export function emitMapLikeIntrinsic(
       return { name: emitMapIterStart(host, r.name), type: e.type };
     case "iterLive": {
       const i = host.emitExpr(e.args[0]!);
-      const entry = emitMapIterEntry(host, r.name, i.name, mapEntryLayout(key));
+      const entry = emitMapIterEntry(host, r.name, i.name, layout);
       const t = B.tmp();
       B.line(`${t} = icmp ne ptr ${entry}, null`);
       return { name: t, type: e.type };
@@ -1461,7 +1470,7 @@ export function emitMapLikeIntrinsic(
           kAcc === "str" ? "ref" : kAcc,
           key,
           { decl: `declare ${retTy} @${symbol}(ptr, double)`, symbol },
-          mapEntryLayout(key),
+          layout,
         );
         return host.own({ name: t, type: e.type });
       }
@@ -1488,7 +1497,7 @@ export function emitMapLikeIntrinsic(
           decl: `declare ${vAcc === "bool" ? "zeroext i1" : retTy} @${symbol}(ptr, double)`,
           symbol,
         },
-        mapEntryLayout(key),
+        layout,
       );
       return host.own({ name: t, type: e.type });
     }

packages/compiler/src/backend/llvm/expr-dynamic.ts

@@ -16,6 +16,7 @@ import { streamTypedRefEligible } from "../../ir/analysis.js";
 import {
   DYN,
   type IrExpr,
+  type IrType,
   isDynTypedRefType,
   isRefCounted,
   isUnitType,
@@ -221,6 +222,19 @@ export function emitDynamicExpr(
       host.own({ name: prepared, type: { kind: "dyn" } });
       host.emitPendingCheck();
       const args = e.args.map((a) => emitBorrowedInput(host, a));
+      // A closure registered as a 'message' listener gets a typed message
+      // entry: ports deliver messages of its parameter's layout without
+      // decoding them to checked-dynamic values first.
+      const listener = messageListenerArg(e);
+      if (listener !== null) {
+        const entry = host.dyn.messageListenerHelper(listener);
+        if (entry !== null) {
+          host.declare(`declare void @scr_dyn_func_set_message(ptr, ptr, ptr)`);
+          B.line(
+            `call void @scr_dyn_func_set_message(ptr ${args[1]!.name}, ptr @${host.dyn.dynFuncThunkHelper(listener)}, ptr @${entry})`,
+          );
+        }
+      }
       let argsPtr = "null";
       if (args.length > 0) {
         const arr = B.slot();
@@ -1282,9 +1296,7 @@ function emitUnionEqWrappedScalar(
     B.startBlock(same);
     const eq = B.tmp();
     if (arm.kind === "f64") {
-      host.declare(`declare double @scr_union_get_f64(ptr)`);
-      const v = B.tmp();
-      B.line(`${v} = call double @scr_union_get_f64(ptr ${union.name})`);
+      const v = host.unionGetF64(union.name);
       if (e.sameValue) {
         host.declare(`declare zeroext i1 @scr_num_same_value(double, double)`);
         B.line(`${eq} = call zeroext i1 @scr_num_same_value(double ${v}, double ${plain.name})`);
@@ -1292,9 +1304,7 @@ function emitUnionEqWrappedScalar(
         B.line(`${eq} = fcmp oeq double ${v}, ${plain.name}`);
       }
     } else {
-      host.declare(`declare zeroext i1 @scr_union_get_bool(ptr)`);
-      const v = B.tmp();
-      B.line(`${v} = call zeroext i1 @scr_union_get_bool(ptr ${union.name})`);
+      const v = host.unionGetBool(union.name);
       B.line(`${eq} = icmp eq i1 ${v}, ${plain.name}`);
     }
     B.line(`store i1 ${eq}, ptr ${slot}`);
@@ -1323,3 +1333,24 @@ export const INHERITED_OBJECT_MEMBERS: ReadonlySet<string> = new Set([
   "hasOwnProperty",
   "propertyIsEnumerable",
 ]);
+
+/** EventEmitter methods that register their second argument as a listener. */
+const LISTENER_METHODS: ReadonlySet<string> = new Set([
+  "on",
+  "once",
+  "addListener",
+  "prependListener",
+  "prependOnceListener",
+]);
+
+/** The closure type of `recv.on("message", listener)` and the other
+ * listener registrations with a typed closure for the 'message' event, or
+ * null. */
+function messageListenerArg(e: ExprOf<"dynInvoke">): (IrType & { kind: "func" }) | null {
+  if (!LISTENER_METHODS.has(e.method) || e.args.length !== 2) return null;
+  const [event, listener] = e.args;
+  if (event?.kind !== "dynFrom" || event.value.kind !== "strLit" || event.value.value !== "message")
+    return null;
+  if (listener?.kind !== "dynFrom" || listener.value.type.kind !== "func") return null;
+  return listener.value.type;
+}

packages/compiler/src/backend/llvm/expr-primitives.ts

@@ -32,7 +32,7 @@ import {
   emitPowerOfTwoRemainder,
   emitSignedIntegerRemainder,
 } from "./integer-remainder.js";
-import { emitDenseArrayGet, emitDenseArrayState, slotWidth } from "./dense-array-access.js";
+import { denseSlotWidth, emitDenseArrayGet, emitDenseArrayState } from "./dense-array-access.js";
 import { emitWrappingSum, markWrappingOperands } from "./wrapping-sums.js";
 
 export function emitLiteralExpr(
@@ -879,7 +879,7 @@ export function emitContainerExpr(
           buffer = B.tmp();
           B.entryAllocas.push(`${buffer} = alloca [${Math.min(e.elems.length, 64)} x i64]`);
         }
-        if (pending.length > 0) emitArrayValues(host, arr, acc, pending, false, buffer);
+        if (pending.length > 0) emitArrayValues(host, arr, acc, elem, pending, false, buffer);
         pending = [];
       };
       e.elems.forEach((el, i) => {
@@ -924,7 +924,7 @@ export function emitContainerExpr(
       }
       const bound = B.tmp();
       B.line(`${bound} = fsub double ${n.name}, ${f64Lit(1)}`);
-      B.countedLoop(bound, () => host.arrPush(arr, acc, fill), "ole");
+      B.countedLoop(bound, () => host.arrPush(arr, acc, fill, elem), "ole");
       return out;
     }
     case "arrayGet": {
@@ -962,7 +962,7 @@ export function emitContainerExpr(
         idx,
         e.index,
         "has",
-        slotWidth(elemAccess(e.arr.type.elem)),
+        denseSlotWidth(host, e.arr.type.elem),
       );
       return { name: t, type: e.type };
     }
@@ -977,7 +977,7 @@ export function emitContainerExpr(
         idx,
         e.index,
         "state",
-        slotWidth(elemAccess(e.arr.type.elem)),
+        denseSlotWidth(host, e.arr.type.elem),
       );
       return { name: t, type: e.type };
     }

packages/compiler/src/backend/llvm/expr-stream-callbacks.ts

@@ -15,23 +15,55 @@ export function streamDataAdapter(
   sym = `sc_ee_dad_${host.resolveThunks.size}`;
   host.resolveThunks.set(key, sym);
   const p = cbT.params[0];
-  if (
-    cbT.params.length > 1 ||
-    (p && p.kind !== "bytes" && p.kind !== "string" && p.kind !== "dyn" && p.kind !== "union")
-  ) {
+  if (cbT.params.length > 1) {
     throw new InternalCompilerError(
       "llvm emitter bug: stream data listener param shape (frontend must fence)",
     );
   }
+  // A `Buffer | string` union wraps the filled slot; any other union (or
+  // other type) converts from the chunk's checked-dynamic value.
+  const bytesOrString =
+    p?.kind === "union" &&
+    (() => {
+      const def = host.unionsById.get(p.unionId);
+      return (
+        def !== undefined &&
+        !host.nullableUnions.has(p.unionId) &&
+        def.arms.length === 2 &&
+        def.arms.some((a) => a.kind === "bytes" && a.elem === "u8") &&
+        def.arms.some((a) => a.kind === "string")
+      );
+    })();
   host.declare(`declare ptr @scr_box_get_ref(ptr)`);
   host.declare(`declare void @scr_closure_release(ptr)`);
+  // The emit ABI's three slots (scr_stream_emit_data): the bytes chunk,
+  // the string chunk, and an object-mode entry's value.
   const d: string[] = [
-    `define internal void @${sym}(ptr %cb, ptr %a0, ptr %a1) ${FN_ATTRS} { ; stream 'data' adapter ${typeKey(cbT)}`,
+    `define internal void @${sym}(ptr %cb, ptr %a0, ptr %a1, ptr %a2) ${FN_ATTRS} { ; stream 'data' adapter ${typeKey(cbT)}`,
     `entry:`,
     `  %capsp = getelementptr inbounds %ScrClosure, ptr %cb, i64 1`,
     `  %bx = load ptr, ptr %capsp`,
     `  %orig = call ptr @scr_box_get_ref(ptr %bx) ; the listener, +1`,
   ];
+  const finishTyped = (arg: string, argTy: string): void => {
+    d.push(
+      `  %fnp = getelementptr inbounds %ScrClosure, ptr %orig, i64 0, i32 1`,
+      `  %fn = load ptr, ptr %fnp`,
+    );
+    const retTy = host.llType(cbT.ret);
+    const argList = `ptr %orig, ${argTy} ${arg}`;
+    if (retTy === "void") {
+      d.push(`  call void %fn(${argList})`);
+    } else {
+      d.push(`  %ret = call ${retTy} %fn(${argList})`);
+      if (isRefCounted(cbT.ret)) {
+        d.push(
+          `  call void ${releaseSym(host.shapeHost, cbT.ret)}(ptr %ret) ; discarded listener result`,
+        );
+      }
+    }
+    d.push(`  call void @scr_closure_release(ptr %orig)`, `  ret void`);
+  };
   const finish = (arg: string | null): void => {
     d.push(
       `  %fnp = getelementptr inbounds %ScrClosure, ptr %orig, i64 0, i32 1`,
@@ -57,8 +89,8 @@ export function streamDataAdapter(
   } else if (p.kind === "bytes" || p.kind === "string") {
     const msg =
       p.kind === "bytes"
-        ? "a 'data' listener declaring a Buffer chunk received a string (the stream has an encoding set)"
-        : "a 'data' listener declaring a string chunk received a Buffer (call setEncoding, or declare the chunk as a Buffer)";
+        ? "a 'data' listener declaring a Buffer chunk received a string or an object-mode value (the stream has an encoding set, or is in object mode)"
+        : "a 'data' listener declaring a string chunk received a Buffer or an object-mode value (call setEncoding, or declare the chunk's type)";
     const slot = p.kind === "bytes" ? "%a0" : "%a1";
     host.declare(`declare void @scr_throw_error_msg(i32, ptr, ${host.sizeType})`);
     d.push(
@@ -73,7 +105,7 @@ export function streamDataAdapter(
     );
     finish("%r0");
     d.push(`}`, ``);
-  } else if (p.kind === "union") {
+  } else if (p.kind === "union" && bytesOrString) {
     // A `Buffer | string` chunk: wrap whichever slot the stream filled at
     // its arm of the (boxed) union.
     const def = host.unionsById.get(p.unionId);
@@ -94,6 +126,9 @@ export function streamDataAdapter(
     host.declare(`declare void @scr_bytes_release_v(ptr)`);
     host.declare(`declare ptr @scr_str_retain_v(ptr)`);
     host.declare(`declare void @scr_str_release_v(ptr)`);
+    host.declare(`declare void @scr_throw_error_msg(i32, ptr, ${host.sizeType})`);
+    const unionMsg =
+      "a 'data' listener declaring a Buffer | string chunk received an object-mode value that is neither (declare the chunk's type)";
     d.push(
       `  %uslot = alloca ptr`,
       `  %isb = icmp ne ptr %a0, null`,
@@ -104,6 +139,15 @@ export function streamDataAdapter(
       `  store ptr %ub, ptr %uslot`,
       `  br label %go`,
       `str:`,
+      // an object-mode value that is neither: the catchable error the
+      // one-type adapters throw
+      `  %nos = icmp eq ptr %a1, null`,
+      `  br i1 %nos, label %bad, label %strok`,
+      `bad:`,
+      `  call void @scr_throw_error_msg(i32 1, ptr ${host.cstr(unionMsg)}, ${host.sizeType} ${Buffer.byteLength(unionMsg, "utf8")})`,
+      `  call void @scr_closure_release(ptr %orig)`,
+      `  ret void`,
+      `strok:`,
       `  %rs = call ptr @scr_str_retain_v(ptr %a1)`,
       `  %us = call ptr @scr_union_new_ref(i32 ${strTag}, ptr %rs, ptr @scr_str_retain_v, ptr @scr_str_release_v, ptr null)`,
       `  store ptr %us, ptr %uslot`,
@@ -114,11 +158,20 @@ export function streamDataAdapter(
     finish("%uv");
     d.push(`}`, ``);
   } else {
-    // dyn: box by runtime tag — the JS lane's adapter parameter.
+    // dyn: the object-mode value, else box by runtime tag — the JS lane's
+    // adapter parameter. Any other type converts from that value.
     host.declare(`declare ptr @scr_dyn_new_buffer(ptr)`);
     host.declare(`declare ptr @scr_dyn_new_str(ptr)`);
+    host.declare(`declare ptr @scr_dyn_retain_v(ptr)`);
     d.push(
       `  %dslot = alloca ptr`,
+      `  %isv = icmp ne ptr %a2, null`,
+      `  br i1 %isv, label %val, label %chunk`,
+      `val:`,
+      `  %dvv = call ptr @scr_dyn_retain_v(ptr %a2)`,
+      `  store ptr %dvv, ptr %dslot`,
+      `  br label %go`,
+      `chunk:`,
       `  %isb = icmp ne ptr %a0, null`,
       `  br i1 %isb, label %buf, label %str`,
       `buf:`,
@@ -132,7 +185,25 @@ export function streamDataAdapter(
       `go:`,
       `  %dv = load ptr, ptr %dslot`,
     );
-    finish("%dv");
+    if (p.kind === "dyn") {
+      finish("%dv");
+    } else {
+      const helper = host.dyn.dynCheckHelper(p, false);
+      const ty = host.llType(p);
+      host.declare(`declare void @scr_dyn_release(ptr)`);
+      host.declare(`declare zeroext i1 @scr_exc_pending()`);
+      d.push(
+        `  %tv = call ${ty === "i1" ? "zeroext i1" : ty} @${helper}(ptr %dv, ptr null)`,
+        `  call void @scr_dyn_release(ptr %dv)`,
+        `  %pend = call zeroext i1 @scr_exc_pending()`,
+        `  br i1 %pend, label %fail, label %conv`,
+        `fail:`,
+        `  call void @scr_closure_release(ptr %orig)`,
+        `  ret void`,
+        `conv:`,
+      );
+      finishTyped("%tv", ty);
+    }
     d.push(`}`, ``);
   }
   host.resolveThunkDefs.push(...d);
@@ -164,12 +235,25 @@ export function streamDoneFnFor(
   const dataT = kind === "t" || kind === "l" ? doneT.params[1] : undefined;
   let bytesTag = -1;
   let strTag = -1;
+  // data of any type other than a union of Buffer, string, undefined and
+  // null (an object-mode Transform's value) completes through the
+  // value entry points with the data boxed.
+  let valueData = false;
   if (dataT !== undefined) {
-    if (dataT.kind !== "union")
-      throw new InternalCompilerError("llvm emitter bug: stream done data param not a union");
-    const def = host.unionsById.get(dataT.unionId);
-    bytesTag = def ? def.arms.findIndex((a) => a.kind === "bytes") : -1;
-    strTag = def ? def.arms.findIndex((a) => a.kind === "string") : -1;
+    const def = dataT.kind === "union" ? host.unionsById.get(dataT.unionId) : undefined;
+    valueData =
+      def === undefined ||
+      !def.arms.every(
+        (a) =>
+          (a.kind === "bytes" && a.elem === "u8") ||
+          a.kind === "string" ||
+          a.kind === "undefinedT" ||
+          a.kind === "nullT",
+      );
+    if (!valueData) {
+      bytesTag = def!.arms.findIndex((a) => a.kind === "bytes");
+      strTag = def!.arms.findIndex((a) => a.kind === "string");
+    }
   }
   const entry =
     kind === "w"
@@ -179,10 +263,16 @@ export function streamDoneFnFor(
         : kind === "d"
           ? "scr_stream_destroy_done"
           : kind === "t"
-            ? "scr_stream_transform_done"
-            : "scr_stream_flush_done";
-  const twoSlot = kind === "t" || kind === "l";
-  host.declare(`declare void @${entry}(ptr, ptr${twoSlot ? ", ptr, ptr" : ""})`);
+            ? valueData
+              ? "scr_stream_transform_done_value"
+              : "scr_stream_transform_done"
+            : valueData
+              ? "scr_stream_flush_done_value"
+              : "scr_stream_flush_done";
+  const twoSlot = (kind === "t" || kind === "l") && !valueData;
+  host.declare(
+    `declare void @${entry}(ptr, ptr${twoSlot ? ", ptr, ptr" : valueData ? ", ptr" : ""})`,
+  );
   host.declare(`declare ptr @scr_box_get_ref(ptr)`);
   host.declare(`declare void @scr_stream_release_v(ptr)`);
   host.declare(`declare ptr @scr_error_retain_v(ptr)`);
@@ -190,7 +280,7 @@ export function streamDoneFnFor(
   const params = [
     "ptr %self",
     ...(errT !== undefined ? ["ptr %e"] : []),
-    ...(dataT !== undefined ? ["ptr %d"] : []),
+    ...(dataT !== undefined ? [`${host.llType(dataT)} %d`] : []),
   ];
   const d: string[] = [
     `define internal void @${sym}(${params.join(", ")}) ${FN_ATTRS} { ; stream '${kind}' done ${typeKey(doneT)}`,
@@ -234,7 +324,15 @@ export function streamDoneFnFor(
     unwrap("%d", strTag, "@scr_str_retain_v", "%sslot");
   }
   d.push(`  %ev = load ptr, ptr %eslot`);
-  if (twoSlot) {
+  if (valueData) {
+    const conv = host.dyn.toDynHelper(dataT!);
+    host.declare(`declare void @scr_dyn_release(ptr)`);
+    d.push(
+      `  %dv = call ptr @${conv}(${host.llType(dataT!)} %d)`,
+      `  call void @${entry}(ptr %s, ptr %ev, ptr %dv) ; moves err; borrows s and the value`,
+      `  call void @scr_dyn_release(ptr %dv)`,
+    );
+  } else if (twoSlot) {
     d.push(
       `  %bv = load ptr, ptr %bslot`,
       `  %sv = load ptr, ptr %sslot`,
@@ -245,7 +343,8 @@ export function streamDoneFnFor(
   }
   d.push(`  call void @scr_stream_release_v(ptr %s)`);
   if (errT !== undefined) d.push(`  call void ${releaseSym(host.shapeHost, errT)}(ptr %e)`);
-  if (dataT !== undefined) d.push(`  call void ${releaseSym(host.shapeHost, dataT)}(ptr %d)`);
+  if (dataT !== undefined && isRefCounted(dataT))
+    d.push(`  call void ${releaseSym(host.shapeHost, dataT)}(ptr %d)`);
   d.push(`  ret void`, `}`, ``);
   host.resolveThunkDefs.push(...d);
   return sym;
@@ -611,18 +710,14 @@ export function streamCbThunkFor(
             : pos === 1;
     if (p.kind === "dyn") {
       if (isChunkPos) {
-        host.declare(`declare ptr @scr_dyn_new_buffer(ptr)`);
-        d.push(`  %dc${i} = call ptr @scr_dyn_new_buffer(ptr %chunk)`);
+        // the chunk's value: a Buffer, or an object-mode side's value
+        host.declare(`declare ptr @scr_stream_chunk_value(ptr, ptr)`);
+        d.push(`  %dc${i} = call ptr @scr_stream_chunk_value(ptr %s, ptr %chunk)`);
         passed.push(`ptr %dc${i}`);
       } else if (isEncPos) {
-        host.declare(`declare ptr @scr_str_new(ptr, ${host.sizeType})`);
-        host.declare(`declare ptr @scr_dyn_new_str(ptr)`);
-        host.declare(`declare void @scr_str_release(ptr)`);
-        d.push(
-          `  %es${i} = call ptr @scr_str_new(ptr ${host.cstr("buffer")}, ${host.sizeType} 6)`,
-          `  %ed${i} = call ptr @scr_dyn_new_str(ptr %es${i})`,
-          `  call void @scr_str_release(ptr %es${i})`,
-        );
+        // 'buffer', or the encoding argument an object-mode write passed
+        host.declare(`declare ptr @scr_stream_chunk_encoding_value(ptr)`);
+        d.push(`  %ed${i} = call ptr @scr_stream_chunk_encoding_value(ptr %s)`);
         passed.push(`ptr %ed${i}`);
       } else if (isErrPos) {
         // finished/pipeline succeed with UNDEFINED (Node calls the eos
@@ -673,15 +768,71 @@ export function streamCbThunkFor(
       }
       continue;
     }
-    if (isChunkPos) {
-      host.declare(`declare ptr @scr_bytes_retain_v(ptr)`);
-      d.push(`  %rc${i} = call ptr @scr_bytes_retain_v(ptr %chunk)`);
+    if (isChunkPos && p.kind === "bytes") {
+      // A Buffer, which an object-mode side's value must be (else a
+      // TypeError, thrown out of the write).
+      host.declare(`declare ptr @scr_stream_chunk_bytes(ptr, ptr)`);
+      d.push(
+        `  %rc${i} = call ptr @scr_stream_chunk_bytes(ptr %s, ptr %chunk)`,
+        `  %rcbad${i} = icmp eq ptr %rc${i}, null`,
+        `  br i1 %rcbad${i}, label %rcfail${i}, label %rcok${i}`,
+        `rcfail${i}:`,
+        ...(hasThis ? [`  call void @scr_stream_release_v(ptr %sr)`] : []),
+        `  ret void`,
+        `rcok${i}:`,
+      );
+      if (hasThis) host.declare(`declare void @scr_stream_release_v(ptr)`);
       passed.push(`ptr %rc${i}`);
-    } else if (isEncPos) {
-      // Node's encoding for decoded (Buffer) chunks is 'buffer'.
-      host.declare(`declare ptr @scr_str_new(ptr, ${host.sizeType})`);
-      d.push(`  %en${i} = call ptr @scr_str_new(ptr ${host.cstr("buffer")}, ${host.sizeType} 6)`);
+    } else if (isChunkPos) {
+      // Any other declared type converts from the chunk's value (an
+      // object-mode side's value, or the Buffer), or throws out of the
+      // write.
+      const helper = host.dyn.dynCheckHelper(p, false);
+      const ty = host.llType(p);
+      host.declare(`declare ptr @scr_stream_chunk_value(ptr, ptr)`);
+      host.declare(`declare void @scr_dyn_release(ptr)`);
+      host.declare(`declare zeroext i1 @scr_exc_pending()`);
+      if (hasThis) host.declare(`declare void @scr_stream_release_v(ptr)`);
+      d.push(
+        `  %cv${i} = call ptr @scr_stream_chunk_value(ptr %s, ptr %chunk)`,
+        `  %ct${i} = call ${ty === "i1" ? "zeroext i1" : ty} @${helper}(ptr %cv${i}, ptr null)`,
+        `  call void @scr_dyn_release(ptr %cv${i})`,
+        `  %ctbad${i} = call zeroext i1 @scr_exc_pending()`,
+        `  br i1 %ctbad${i}, label %ctfail${i}, label %ctok${i}`,
+        `ctfail${i}:`,
+        ...(hasThis ? [`  call void @scr_stream_release_v(ptr %sr)`] : []),
+        `  ret void`,
+        `ctok${i}:`,
+      );
+      passed.push(`${ty} %ct${i}`);
+    } else if (isEncPos && p.kind === "string") {
+      // Node's encoding for decoded (Buffer) chunks is 'buffer'; an
+      // object-mode side passes the write's encoding argument ("" for
+      // undefined and null).
+      host.declare(`declare ptr @scr_stream_chunk_encoding(ptr)`);
+      d.push(`  %en${i} = call ptr @scr_stream_chunk_encoding(ptr %s)`);
       passed.push(`ptr %en${i}`);
+    } else if (isEncPos) {
+      // Another declared type (string | null | undefined) converts from
+      // the encoding argument's value.
+      const helper = host.dyn.dynCheckHelper(p, false);
+      const ty = host.llType(p);
+      host.declare(`declare ptr @scr_stream_chunk_encoding_value(ptr)`);
+      host.declare(`declare void @scr_dyn_release(ptr)`);
+      host.declare(`declare zeroext i1 @scr_exc_pending()`);
+      if (hasThis) host.declare(`declare void @scr_stream_release_v(ptr)`);
+      d.push(
+        `  %ev${i} = call ptr @scr_stream_chunk_encoding_value(ptr %s)`,
+        `  %et${i} = call ${ty === "i1" ? "zeroext i1" : ty} @${helper}(ptr %ev${i}, ptr null)`,
+        `  call void @scr_dyn_release(ptr %ev${i})`,
+        `  %etbad${i} = call zeroext i1 @scr_exc_pending()`,
+        `  br i1 %etbad${i}, label %etfail${i}, label %etok${i}`,
+        `etfail${i}:`,
+        ...(hasThis ? [`  call void @scr_stream_release_v(ptr %sr)`] : []),
+        `  ret void`,
+        `etok${i}:`,
+      );
+      passed.push(`${ty} %et${i}`);
     } else if (isErrPos) {
       // destroy's error argument: `Error | null` — wrap type-directedly.
       // The finished/pipeline callback ("e") may declare `Error | null |

packages/compiler/src/backend/llvm/lib-filesystem.ts

@@ -163,7 +163,7 @@ function emitObjEntryPairs(host: LlvmEmitterContext, e: LibCallExpr): LlValue {
   B.line(`${row} = call ptr @${mangleRecordNew(rowT.shapeId)}()`);
   host.storeField(host.recordFieldPtr(row, rowT.shapeId, "0").ptr, STRING, key, false);
   host.storeField(host.recordFieldPtr(row, rowT.shapeId, "1").ptr, DYN, item, false);
-  host.arrPush(arr, "ref", row); // push takes ownership of the row
+  host.arrPush(arr, "ref", row, null); // push takes ownership of the row
   const next = B.tmp();
   B.line(`${next} = add ${size} ${i}, 1`);
   B.line(`store ${size} ${next}, ptr ${iSlot}`);
@@ -536,7 +536,7 @@ export function emitFilesystemLibCall(host: LlvmEmitterContext, e: LibCallExpr):
     const parent = B.tmp();
     B.line(`${parent} = call ptr @scr_fs_glob_parent(ptr ${snap}, ${host.sizeType} ${i}) ; +1`);
     B.line(`store ptr ${parent}, ptr ${host.recordFieldPtr(row, recT.shapeId, "parentPath").ptr}`);
-    host.arrPush(arr, "ref", row); // push takes ownership of the row
+    host.arrPush(arr, "ref", row, null); // push takes ownership of the row
     const i2 = B.tmp();
     B.line(`${i2} = add ${host.sizeType} ${i}, 1`);
     B.line(`store ${host.sizeType} ${i2}, ptr ${iSlot}`);
@@ -620,7 +620,7 @@ export function emitFilesystemLibCall(host: LlvmEmitterContext, e: LibCallExpr):
     B.line(
       `store ptr ${host.retainHeap(path.name, STRING)}, ptr ${host.recordFieldPtr(row, recT.shapeId, "parentPath").ptr}`,
     );
-    host.arrPush(arr, "ref", row); // push takes ownership of the row
+    host.arrPush(arr, "ref", row, null); // push takes ownership of the row
     const i2 = B.tmp();
     B.line(`${i2} = add ${host.sizeType} ${i}, 1`);
     B.line(`store ${host.sizeType} ${i2}, ptr ${iSlot}`);
@@ -955,7 +955,7 @@ export function emitPathUrlLibCall(host: LlvmEmitterContext, e: LibCallExpr): Ll
     B.startBlock(lj);
     const rows = B.tmp();
     B.line(`${rows} = load ptr, ptr ${rowsSlot}`);
-    host.arrPush(rows, "ref", row); // push takes ownership of the row
+    host.arrPush(rows, "ref", row, null); // push takes ownership of the row
     B.line(`call void @scr_arr_release(ptr ${rows})`);
     B.line(`call void @scr_str_release(ptr ${nm})`);
     const i2 = B.tmp();

packages/compiler/src/backend/llvm/lib-process.ts

@@ -924,32 +924,41 @@ export function emitErrorsEventsLibCall(host: LlvmEmitterContext, e: LibCallExpr
   }
   if (e.fn === "emitter.emitData") {
     // A user emit('data', chunk) on a stream-rooted receiver: fill the
-    // matching payload slot of the two-slot 'data' ABI, NULL the other.
+    // matching payload slot of the three-slot 'data' ABI (bytes, string,
+    // object-mode value), NULL the others; a checked-dynamic chunk fills
+    // them by tag (scr_stream_emit_value).
     const args = e.args.map((a) => host.emitExpr(a));
     const chunkT = e.args[2]!.type;
-    const both =
-      chunkT.kind === "string"
-        ? [`ptr null`, `ptr ${args[2]!.name}`]
-        : [`ptr ${args[2]!.name}`, `ptr null`];
-    host.declare(`declare zeroext i1 @scr_emitter_emit(ptr, ptr, ...)`);
     const t = B.tmp();
-    B.line(
-      `${t} = call zeroext i1 (ptr, ptr, ...) @scr_emitter_emit(ptr ${args[0]!.name}, ptr ${args[1]!.name}, ${both.join(", ")})`,
-    );
+    if (chunkT.kind === "dyn") {
+      host.declare(`declare zeroext i1 @scr_stream_emit_value(ptr, ptr, ptr)`);
+      B.line(
+        `${t} = call zeroext i1 @scr_stream_emit_value(ptr ${args[0]!.name}, ptr ${args[1]!.name}, ptr ${args[2]!.name})`,
+      );
+    } else {
+      const slots =
+        chunkT.kind === "string"
+          ? [`ptr null`, `ptr ${args[2]!.name}`, `ptr null`]
+          : [`ptr ${args[2]!.name}`, `ptr null`, `ptr null`];
+      host.declare(`declare zeroext i1 @scr_emitter_emit(ptr, ptr, ...)`);
+      B.line(
+        `${t} = call zeroext i1 (ptr, ptr, ...) @scr_emitter_emit(ptr ${args[0]!.name}, ptr ${args[1]!.name}, ${slots.join(", ")})`,
+      );
+    }
     host.emitPendingCheck();
     return e.type.kind === "void" ? { name: "", type: e.type } : { name: t, type: e.type };
   }
   if (e.fn === "emitter.onData" || e.fn === "emitter.onDataDyn") {
     // The stream-'data' registration: same runtime entries as
-    // emitter.on/onDyn, but the DATA adapter (the two-slot payload ABI
-    // — scr_stream_emit_data) behind the arity-2 fixed shim.
+    // emitter.on/onDyn, but the DATA adapter (the three-slot payload ABI
+    // — scr_stream_emit_data) behind the arity-3 fixed shim.
     const isDyn = e.fn === "emitter.onDataDyn";
     const cbT = e.args[isDyn ? 3 : 2]!.type;
     if (cbT.kind !== "func")
       throw new InternalCompilerError(`llvm emitter bug: ${e.fn} listener not a func`);
     const args = e.args.map((a) => host.emitExpr(a));
     const adapterFn = host.streamDataAdapter(cbT);
-    host.declare(`declare void @scr_ee_inv_fixed2(ptr, ptr)`);
+    host.declare(`declare void @scr_ee_inv_fixed3(ptr, ptr)`);
     const t = B.tmp();
     if (isDyn) {
       host.toHeap(args[3]!);
@@ -959,7 +968,7 @@ export function emitErrorsEventsLibCall(host: LlvmEmitterContext, e: LibCallExpr
       );
       B.line(
         `${t} = call ptr @scr_emitter_on_dyn(ptr ${args[0]!.name}, ptr ${args[1]!.name}, ` +
-          `ptr ${args[2]!.name}, ptr ${wrapped}, ptr @scr_ee_inv_fixed2, i1 ${args[4]!.name}, i1 ${args[5]!.name})`,
+          `ptr ${args[2]!.name}, ptr ${wrapped}, ptr @scr_ee_inv_fixed3, i1 ${args[4]!.name}, i1 ${args[5]!.name})`,
       );
     } else {
       host.declare(`declare ptr @scr_closure_retain_v(ptr)`);
@@ -972,7 +981,7 @@ export function emitErrorsEventsLibCall(host: LlvmEmitterContext, e: LibCallExpr
       );
       B.line(
         `${t} = call ptr @scr_emitter_on_via(ptr ${args[0]!.name}, ptr ${args[1]!.name}, ` +
-          `ptr ${args[2]!.name}, ptr ${wrapped}, ptr @scr_ee_inv_fixed2, i1 ${args[3]!.name}, i1 ${args[4]!.name})`,
+          `ptr ${args[2]!.name}, ptr ${wrapped}, ptr @scr_ee_inv_fixed3, i1 ${args[3]!.name}, i1 ${args[4]!.name})`,
       );
     }
     const out = host.own({ name: t, type: e.type });

packages/compiler/src/backend/llvm/lib-shared.ts

@@ -47,7 +47,7 @@ export const LIB_FN_SYMS: Record<string, string> = {
   "dyn.fromEntries": "scr_dyn_from_entries",
   "bytes.constructor": "scr_bytes_constructor",
   "bytes.construct": "scr_bytes_construct",
-  "bytes.instanceOf": "scr_bytes_instanceof",
+  "bytes.instanceOf": "scr_bytes_instanceof_at",
   "arrayBuffer.constructor": "scr_array_buffer_constructor",
   "sharedArrayBuffer.new": "scr_shared_array_buffer_new",
   "sharedArrayBuffer.is": "scr_shared_array_buffer_is",
@@ -578,6 +578,12 @@ export const LIB_FN_SYMS: Record<string, string> = {
   "crypto.cipherNew": "scr_crypto_cipher_new",
   "crypto.ecdhNew": "scr_crypto_ecdh_new",
   "crypto.ecdhConvertKey": "scr_crypto_ecdh_convert_key",
+  "crypto.dhNew": "scr_crypto_dh_new",
+  "crypto.checkPrimeSync": "scr_crypto_check_prime_sync",
+  "crypto.checkPrimeCb": "scr_crypto_check_prime_async",
+  "crypto.generatePrimeSync": "scr_crypto_generate_prime_sync",
+  "crypto.generatePrimeCb": "scr_crypto_generate_prime_async",
+  "crypto.dhGroupNew": "scr_crypto_dh_group_new",
   "crypto.hmacNewStr": "scr_crypto_hmac_new_str",
   "crypto.hmacNewBytes": "scr_crypto_hmac_new_bytes",
   "crypto.hashUpdateStr": "scr_crypto_hash_update_str",
@@ -615,11 +621,13 @@ export const LIB_FN_SYMS: Record<string, string> = {
   "crypto.generateKeySync": "scr_crypto_generate_key_sync",
   "crypto.keyObjectInput": "scr_crypto_key_object_input",
   "crypto.isKeyObject": "scr_crypto_is_key_object",
-  "webcrypto.importKey": "scr_webcrypto_import_key",
   "webcrypto.generateKey": "scr_webcrypto_generate_key",
+  "webcrypto.importKey": "scr_webcrypto_import_key",
   "webcrypto.exportKey": "scr_webcrypto_export_key",
   "webcrypto.encrypt": "scr_webcrypto_encrypt",
   "webcrypto.decrypt": "scr_webcrypto_decrypt",
+  "webcrypto.wrapKey": "scr_webcrypto_wrap_key",
+  "webcrypto.unwrapKey": "scr_webcrypto_unwrap_key",
   "webcrypto.deriveBits": "scr_webcrypto_derive_bits",
   "webcrypto.deriveKey": "scr_webcrypto_derive_key",
   "webcrypto.sign": "scr_webcrypto_sign",
@@ -1039,6 +1047,14 @@ export const LIB_FN_SYMS: Record<string, string> = {
   "crypto.x509ValidFromStr": "scr_crypto_x509_valid_from_str",
   "crypto.x509ValidTo": "scr_crypto_x509_valid_to",
   "crypto.x509ValidToStr": "scr_crypto_x509_valid_to_str",
+  "crypto.createPrivateKey": "scr_crypto_create_private_key",
+  "crypto.createPublicKey": "scr_crypto_create_public_key",
+  "crypto.generateKeyPairSync": "scr_crypto_generate_key_pair_sync",
+  "crypto.generateKeyPairCb": "scr_crypto_generate_key_pair_async",
+  "crypto.signOneshot": "scr_crypto_sign_oneshot",
+  "crypto.verifyOneshot": "scr_crypto_verify_oneshot",
+  "crypto.createSign": "scr_crypto_create_sign",
+  "crypto.createVerify": "scr_crypto_create_verify",
   "fs.writeFileModeSync": "scr_fs_write_file_mode",
   "fs.chownSync": "scr_fs_chown",
   "fs.lchownSync": "scr_fs_lchown",
@@ -1113,10 +1129,13 @@ export const LIB_FN_SYMS: Record<string, string> = {
   "readable.pushStr": "scr_stream_push_str",
   "readable.pushStrEnc": "scr_stream_push_str_enc",
   "readable.pushEncoding": "scr_stream_set_push_encoding",
+  "stream.objectMode": "scr_stream_object_mode",
+  "stream.chunkDone": "scr_stream_chunk_done",
   "readable.pushNull": "scr_stream_push_null",
   "readable.pushDyn": "scr_stream_push_dyn",
   "readable.unshift": "scr_stream_unshift",
   "readable.unshiftStr": "scr_stream_unshift_str",
+  "readable.unshiftDyn": "scr_stream_unshift_dyn",
   "readable.pause": "scr_stream_pause",
   "readable.resume": "scr_stream_resume",
   "readable.isPaused": "scr_stream_is_paused",
@@ -1584,6 +1603,9 @@ export function mockTimerSym(
 }
 
 export const USES_TIMERS_LIB_FNS = new Set<string>([
+  "crypto.generateKeyPairCb",
+  "crypto.checkPrimeCb",
+  "crypto.generatePrimeCb",
   "process.emitWarning",
   // Constructor-function streams defer their events on the stream ticks.
   "dyn.builtinStreamClass",
@@ -1595,6 +1617,8 @@ export const USES_TIMERS_LIB_FNS = new Set<string>([
   "webcrypto.generateKey",
   "webcrypto.encrypt",
   "webcrypto.decrypt",
+  "webcrypto.wrapKey",
+  "webcrypto.unwrapKey",
   "webcrypto.deriveBits",
   "webcrypto.deriveKey",
   "webcrypto.sign",
@@ -1667,6 +1691,7 @@ export const USES_TIMERS_LIB_FNS = new Set<string>([
   "readable.pushDyn",
   "readable.unshift",
   "readable.unshiftStr",
+  "readable.unshiftDyn",
   "readable.read",
   "readable.readDyn",
   "readable.setEncoding",
@@ -1698,6 +1723,7 @@ export const USES_TIMERS_LIB_FNS = new Set<string>([
   "console.write",
   "writable.writeU",
   "writable.writeDyn",
+  "writable.writeEnc",
   "writable.end",
   "writable.uncork",
   "stream.destroy",

packages/compiler/src/backend/llvm/lib-stream.ts

@@ -419,10 +419,34 @@ export function emitStreamLibCall(host: LlvmEmitterContext, e: LibCallExpr): LlV
     host.emitPendingCheck();
     return e.type.kind === "void" ? { name: "", type: e.type } : { name: t, type: e.type };
   }
+  if (e.fn === "writable.writeEnc") {
+    // (recv, flags, chunk[, encoding][, cb]) — flags: 1 encoding, 2
+    // callback (MOVES). Without an encoding the argument is undefined, or
+    // null when the callback took its place.
+    const flagsArg = e.args[1]!;
+    if (flagsArg.kind !== "numLit")
+      throw new InternalCompilerError("llvm emitter bug: writable.writeEnc flags not a literal");
+    const flags = flagsArg.value;
+    const args = e.args.map((a) => host.emitExpr(a));
+    let at = 3;
+    const enc = flags & 1 ? args[at++]!.name : writeEncNull(host, flags & 2 ? "null" : "undef");
+    let cb = "null";
+    if (flags & 2) {
+      host.toHeap(args[at]!);
+      cb = args[at]!.name;
+    }
+    host.declare(`declare zeroext i1 @scr_stream_write_enc(ptr, ptr, ptr, ptr)`);
+    const t = B.tmp();
+    B.line(
+      `${t} = call zeroext i1 @scr_stream_write_enc(ptr ${args[0]!.name}, ptr ${args[2]!.name}, ptr ${enc}, ptr ${cb})`,
+    );
+    host.emitPendingCheck();
+    return e.type.kind === "void" ? { name: "", type: e.type } : { name: t, type: e.type };
+  }
   if (e.fn === "writable.end") {
-    // (recv, flags[, chunk][, cb]) — flags: 1 bytes chunk, 2 string
-    // chunk, 8 dyn chunk (write first, Node's end(chunk) decomposition),
-    // 4 callback.
+    // (recv, flags[, chunk][, encoding][, cb]) — flags: 1 bytes chunk, 2
+    // string chunk, 8 dyn chunk (write first, Node's end(chunk)
+    // decomposition), 16 an encoding after the dyn chunk, 4 callback.
     const flagsArg = e.args[1]!;
     if (flagsArg.kind !== "numLit")
       throw new InternalCompilerError("llvm emitter bug: writable.end flags not a literal");
@@ -432,19 +456,27 @@ export function emitStreamLibCall(host: LlvmEmitterContext, e: LibCallExpr): LlV
     let chunkB = "null";
     let chunkS = "null";
     let chunkD: string | null = null;
+    let encD = "null";
     if (flags & 1) chunkB = args[at++]!.name;
     else if (flags & 2) chunkS = args[at++]!.name;
     else if (flags & 8) chunkD = args[at++]!.name;
+    if (flags & 16) encD = args[at++]!.name;
+    else if (chunkD !== null && flags & 4) encD = writeEncNull(host, "null");
     let cbName = "null";
     if (flags & 4) {
       host.toHeap(args[at]!);
       cbName = args[at]!.name;
     }
     if (chunkD !== null) {
-      host.declare(`declare zeroext i1 @scr_stream_write_dyn(ptr, ptr, ptr)`);
+      // end(chunk, cb) writes with a null encoding argument (Node's end
+      // shifts the callback out of it)
+      host.declare(`declare zeroext i1 @scr_stream_write_enc(ptr, ptr, ptr, ptr)`);
       B.line(
-        `${B.tmp()} = call zeroext i1 @scr_stream_write_dyn(ptr ${args[0]!.name}, ptr ${chunkD}, ptr null)`,
+        `${B.tmp()} = call zeroext i1 @scr_stream_write_enc(ptr ${args[0]!.name}, ptr ${chunkD}, ptr ${encD}, ptr null)`,
       );
+      // a write that throws (an unknown encoding) leaves the stream as it
+      // was: Node's end() throws before it ends the stream
+      host.emitPendingCheck();
     }
     host.declare(`declare ptr @scr_stream_end(ptr, ptr, ptr, ptr)`);
     const t = B.tmp();
@@ -771,3 +803,13 @@ export function emitStreamLibCall(host: LlvmEmitterContext, e: LibCallExpr): LlV
   // adapters; the handful of union-wrapped reads use the envGet shapes.
   return host.emitGenericLibCall(e);
 }
+
+/** The encoding argument a write passes when the call has none: undefined
+ * (a null pointer), or the null value when a callback took its place. */
+function writeEncNull(host: LlvmEmitterContext, which: "null" | "undef"): string {
+  if (which === "undef") return "null";
+  host.declare(`declare ptr @scr_dyn_new_null()`);
+  const t = host.B.tmp();
+  host.B.line(`${t} = call ptr @scr_dyn_new_null()`);
+  return t;
+}

packages/compiler/src/backend/llvm/lib-tls.ts

@@ -121,6 +121,13 @@ export function emitTlsLibCall(host: LlvmEmitterContext, e: LibCallExpr): LlValu
     case "tls.sockOnSecureConnect":
       host.toHeap(args[1]!);
       return finishRuntimeCall(host, e, "scr_tls_sock_on_secure_connect", a);
+    case "tls.sockOnSecure":
+      host.toHeap(args[1]!);
+      return finishRuntimeCall(host, e, "scr_tls_sock_on_secure", a);
+    case "tls.wrapSocket":
+      return finishRuntimeCall(host, e, "scr_tls_wrap_socket", [a[0]!, a[1]!, ptr()]);
+    case "tls.wrapSocketCtx":
+      return finishRuntimeCall(host, e, "scr_tls_wrap_socket", a);
     case "tls.sockOnSession": {
       const cb = args[1]!,
         type = callbackType(cb);

packages/compiler/src/backend/llvm/local-array-reads.test.ts

@@ -940,3 +940,17 @@ test("a dense read tests the hole-free prefix before the capacity", () => {
     expect(ir.lastIndexOf("local.array.range", firstCap)).toBeGreaterThan(firstFilled);
   }
 });
+
+test("an optional read at a proven integer index skips the double round trip", () => {
+  const module = fixture();
+  const call = module.functions[2]!.body[0]!;
+  if (call.kind !== "varDecl" || call.init?.kind !== "call") throw new Error("missing call");
+  call.init.args[1] = { kind: "bin", op: "|", left: ref("i", F64), right: num(0), type: F64, loc };
+  expect(candidates(module).get("value")?.borrow).toBe(true);
+  expect(validateModule(module)).toEqual([]);
+  // The int32 index is the dense offset on 64-bit targets; a 32-bit target
+  // converts the double, as a borrowed read does.
+  expect(workBody(module, 64)).not.toContain("local.array.exact");
+  expect(workBody(module, 64)).toContain("local.array.value");
+  expect(workBody(module, 32)).toContain("local.array.exact");
+});

packages/compiler/src/backend/llvm/local-array-reads.ts

@@ -15,6 +15,13 @@ import { ReferenceEffects } from "./reference-effects.js";
 import { SCR_ARR_FIELD, loadArrCount, scrArrStateAt } from "./common.js";
 import { exactInteger, widenInteger } from "./integer-values.js";
 import { READ_FALLBACK } from "./dense-array-access.js";
+import { compactRefLoadLines } from "./classes.js";
+
+/** The dense slot load of a reference read from an array of type
+ * `arrayType`: a pointer, or a compact class reference (SCR_ELEM_CREF). */
+function referenceLoad(host: LlvmEmitterContext, arrayType: IrType): "ptr" | "cref" {
+  return arrayType.kind === "array" && host.compactArrayElem(arrayType.elem) ? "cref" : "ptr";
+}
 
 export interface LocalArrayRead {
   type: IrType;
@@ -469,7 +476,7 @@ function emitDenseReferenceArrayRead(
   no: string,
   slow: string,
   join: string,
-  loadType: "ptr" | "i64" | "i8" = "ptr",
+  loadType: "ptr" | "cref" | "i64" | "i8" = "ptr",
 ): void {
   const B = host.B;
   const header = (field: number): string => {
@@ -555,7 +562,14 @@ function emitDenseReferenceArrayRead(
     const statePtr = B.tmp(),
       denseState = B.tmp(),
       densePresent = B.tmp();
-    scrArrStateAt(host, statePtr, data, cap, loadType === "i8" ? 1 : 8, offset);
+    scrArrStateAt(
+      host,
+      statePtr,
+      data,
+      cap,
+      loadType === "i8" ? 1 : loadType === "cref" ? 4 : 8,
+      offset,
+    );
     host.markMemoryPointer(statePtr, "array:present");
     B.line(`${denseState} = load i8, ptr ${statePtr}${host.fieldAliasAttachment(statePtr)}`);
     B.line(`${densePresent} = icmp eq i8 ${denseState}, 1`);
@@ -564,13 +578,20 @@ function emitDenseReferenceArrayRead(
   B.startBlock(valueLabel);
   const valuePtr = B.tmp(),
     raw = B.tmp();
-  // Boolean arrays store one byte per element; every other kind an 8-byte slot.
-  const slotType = loadType === "i8" ? "i8" : "i64";
+  // Boolean arrays store one byte per element, compact references four,
+  // every other kind an 8-byte slot.
+  const slotType = loadType === "i8" ? "i8" : loadType === "cref" ? "i32" : "i64";
   B.line(
     `${valuePtr} = getelementptr inbounds ${slotType}, ptr ${data}, ${host.sizeType} ${offset}`,
   );
   host.markMemoryPointer(valuePtr, "array:elements");
-  B.line(`${raw} = load ${loadType}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
+  if (loadType === "cref") {
+    const ref = B.tmp();
+    B.line(`${ref} = load i32, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
+    for (const line of compactRefLoadLines(ref, raw, `${raw}.r`)) B.line(line.trimStart());
+  } else {
+    B.line(`${raw} = load ${loadType}, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
+  }
   present(raw);
   B.br(join);
 }
@@ -586,6 +607,36 @@ export function emitBorrowedArrayRead(
   const B = host.B;
   const array = host.emitStableReceiver(read.arr, [read.index]);
   const loopIndex = host.emitIntegerLoopIndex(read.index);
+  if (loopIndex !== null && host.provenDenseIndex(read.arr, read.index)) {
+    // In a dense array loop's fast copy, the entry test proved the counter
+    // below the array's hole-free prefix: the slot holds a present value.
+    const dataPtr = B.tmp(),
+      data = B.tmp(),
+      valuePtr = B.tmp(),
+      value = B.tmp();
+    B.line(
+      `${dataPtr} = getelementptr inbounds %ScrArr, ptr ${array.name}, i32 0, i32 ${SCR_ARR_FIELD.data}`,
+    );
+    host.markMemoryPointer(dataPtr, "array:header");
+    B.line(`${data} = load ptr, ptr ${dataPtr}${host.fieldAliasAttachment(dataPtr)}`);
+    if (referenceLoad(host, read.arr.type) === "cref") {
+      // Compact references: 4-byte slots holding the address over 8.
+      const ref = B.tmp();
+      B.line(
+        `${valuePtr} = getelementptr inbounds i32, ptr ${data}, ${host.sizeType} ${loopIndex}`,
+      );
+      host.markMemoryPointer(valuePtr, "array:elements");
+      B.line(`${ref} = load i32, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
+      for (const line of compactRefLoadLines(ref, value, `${value}.r`)) B.line(line.trimStart());
+      B.line(`store ptr ${value}, ptr ${slot}`);
+      return;
+    }
+    B.line(`${valuePtr} = getelementptr inbounds i64, ptr ${data}, ${host.sizeType} ${loopIndex}`);
+    host.markMemoryPointer(valuePtr, "array:elements");
+    B.line(`${value} = load ptr, ptr ${valuePtr}${host.fieldAliasAttachment(valuePtr)}`);
+    B.line(`store ptr ${value}, ptr ${slot}`);
+    return;
+  }
   const index = host.emitExpr(read.index);
   // A proven integer index (an int32 local, say) needs no double
   // round-trip; a negative one compares above the capacity as unsigned.
@@ -604,6 +655,7 @@ export function emitBorrowedArrayRead(
     slow,
     slow,
     join,
+    referenceLoad(host, read.arr.type),
   );
   B.startBlock(slow);
   host.declare("declare ptr @scr_arr_borrow_ref(ptr, double)");
@@ -626,8 +678,15 @@ export function emitLocalArrayRead(
 ): { slot: string; type: IrType } | null {
   const B = host.B;
   const array = host.emitStableReceiver(read.array, [read.index]);
-  const integerIndex = inline ? host.emitIntegerLoopIndex(read.index) : null;
+  const loopIndex = inline ? host.emitIntegerLoopIndex(read.index) : null;
   const index = host.emitExpr(read.index);
+  // A proven integer index (a counter with a known range, say) needs no
+  // double round trip, as in a borrowed read.
+  const exact =
+    inline && loopIndex === null && host.sizeType === "i64"
+      ? exactInteger(host, index, read.index)
+      : null;
+  const integerIndex = loopIndex ?? (exact ? widenInteger(host, exact) : null);
   const nullable = read.type.kind === "union" ? host.nullableUnions.get(read.type.unionId) : null;
   if (nullable) {
     // A nullable union is the element pointer itself: borrowed from an
@@ -647,12 +706,12 @@ export function emitLocalArrayRead(
         array,
         index,
         integerIndex,
-        integerIndex !== null,
+        loopIndex !== null,
         store,
         no,
         slow,
         join,
-        "ptr",
+        referenceLoad(host, read.array.type),
       );
     else B.br(slow);
     B.startBlock(slow);
@@ -708,12 +767,12 @@ export function emitLocalArrayRead(
       array,
       index,
       integerIndex,
-      integerIndex !== null,
+      loopIndex !== null,
       storeValue,
       no,
       slow,
       join,
-      !scalar ? "ptr" : read.element.kind === "bool" ? "i8" : "i64",
+      !scalar ? referenceLoad(host, read.array.type) : read.element.kind === "bool" ? "i8" : "i64",
     );
   else B.br(slow);
   B.startBlock(slow);

packages/compiler/src/backend/llvm/map-number-lookup.test.ts

@@ -181,3 +181,63 @@ test("hashed number-key lookups probe inline and call the runtime only for wide
     );
   }
 });
+
+/** work(map): map.size, and keep(map): map returned as an owned value. */
+function sizeFixture(): IrModule {
+  const map: IrType = { kind: "map", key: F64, value: F64 };
+  const params = [{ localId: "map", name: "map", type: map }];
+  const locals = params.map((p) => ({ id: p.localId, name: p.name, type: p.type, mutable: true }));
+  const size: IrExpr = {
+    kind: "mapIntrinsic",
+    method: "size",
+    receiver: ref("map", map),
+    args: [],
+    type: F64,
+    loc,
+  };
+  return {
+    irVersion: 17,
+    sourceFile: loc.file,
+    entry: "main",
+    records: [],
+    unions: [],
+    functions: [
+      { name: "main", params: [], locals: [], returnType: VOID, body: [], loc },
+      {
+        name: "work",
+        params,
+        returnType: F64,
+        loc,
+        locals,
+        body: [{ kind: "return", value: size, loc }],
+      },
+      {
+        name: "keep",
+        params,
+        returnType: map,
+        loc,
+        locals,
+        body: [{ kind: "return", value: ref("map", map), loc }],
+      },
+    ],
+  };
+}
+
+test("Map.size and Map retains need no runtime call in release builds", () => {
+  const mod = sizeFixture();
+  expect(validateModule(mod)).toEqual([]);
+  for (const bits of [32, 64] as const) {
+    const module = emitLlvmModule(mod, { pointerBits: bits, inlineRc: "release" });
+    const fn = (name: string) =>
+      new RegExp(`^define internal [^\\n]*@sc_(?:b)?f_${name}(?:\\.i32)?\\([^]*?^}`, "m").exec(
+        module,
+      )![0];
+    // Field 9 is the live entry count (scr_map.h).
+    expect(module).toMatch(/^define internal double @sc_map_size\(ptr %m\)/m);
+    expect(module).toContain(`getelementptr inbounds %ScrMapIx, ptr %m, i32 0, i32 9`);
+    expect(fn("work")).toContain("call double @sc_map_size(");
+    expect(module).not.toContain("call double @scr_map_size(");
+    expect(fn("keep")).toContain("@sc_rc_retain_map(");
+    expect(module).not.toContain("call ptr @scr_map_retain_v(");
+  }
+});

packages/compiler/src/backend/llvm/map-number-lookup.ts

@@ -15,6 +15,12 @@
  * retain inline rather than through the runtime's indirect adapter call,
  * and scalar reads and has() share the one lookup.
  *
+ * A string-key map whose values are compact class instances
+ * (SCR_MAP_VAL_CREF, LlEmitter.compactArrayElem of the value type) keeps
+ * 16-byte { key, hash, val } entries with the value as an address over 8:
+ * its reads go through sc_map_entry_str_c and sc_map_iter_entry_c, and
+ * decode the 4-byte value.
+ *
  * The iteration steps behind for-of, forEach and the other entry walks read
  * the entries array through the internal sc_map_iter_entry and
  * sc_map_iter_count helpers: a live entry's key or value loads in place,
@@ -24,6 +30,7 @@
  */
 import type { IrType } from "../../ir/ir.js";
 import type { LlvmEmitterContext } from "./expr-context.js";
+import { mapKeyAccess } from "./shapes.js";
 
 export const NUMBER_MAP_ENTRY_DECL = "declare ptr @scr_map_entry_f64(ptr, double)";
 
@@ -47,18 +54,59 @@ export function emitNumberMapSlot(host: LlvmEmitterContext, entry: string, type:
 }
 
 export const STRING_MAP_ENTRY_DECL = "declare ptr @scr_map_entry_str(ptr, ptr)";
+/** Declared by reads of a compact-value map; its presence makes the emitter
+ * define sc_map_entry_str_c and sc_map_iter_entry_c (emit-module.ts). */
+export const STRING_MAP_ENTRY_C_DECL = "declare ptr @scr_map_entry_str_c(ptr, ptr)";
 
-/** The entry for a string `key`, or null when absent. Valid until the next mutation. */
-export function emitStringMapEntry(host: LlvmEmitterContext, map: string, key: string): string {
-  host.declare(STRING_MAP_ENTRY_DECL);
+/** Whether a Map with key type `key` and value type `value` keeps compact
+ * values (SCR_MAP_VAL_CREF): string keys and a value type whose instances
+ * are compact (LlEmitter.compactArrayElem). */
+export function compactMapValues(host: LlvmEmitterContext, key: IrType, value: IrType): boolean {
+  // SCR_MAP_KEY_STR (shapes.ts mapKeyKindNum 1): string access, not a union.
+  return key.kind !== "union" && mapKeyAccess(key) === "str" && host.compactArrayElem(value);
+}
+
+/** The entry for a string `key`, or null when absent. Valid until the next
+ * mutation. `compact`: the map keeps compact values (a %ScrMapCEntry). */
+export function emitStringMapEntry(
+  host: LlvmEmitterContext,
+  map: string,
+  key: string,
+  compact = false,
+): string {
+  host.declare(compact ? STRING_MAP_ENTRY_C_DECL : STRING_MAP_ENTRY_DECL);
   const entry = host.B.tmp();
-  host.B.line(`${entry} = call ptr @sc_map_entry_str(ptr ${map}, ptr ${key})`);
+  host.B.line(
+    `${entry} = call ptr @${compact ? "sc_map_entry_str_c" : "sc_map_entry_str"}(ptr ${map}, ptr ${key})`,
+  );
   return entry;
 }
 
+/** A found compact-value entry's value as a pointer: its 4-byte form, an
+ * address over 8 (scr_map.h ScrMapCEntry). */
+export function emitCompactMapSlot(host: LlvmEmitterContext, entry: string): string {
+  const B = host.B;
+  const slot = B.tmp(),
+    ref = B.tmp(),
+    wide = B.tmp(),
+    addr = B.tmp(),
+    value = B.tmp();
+  B.line(`${slot} = getelementptr inbounds %ScrMapCEntry, ptr ${entry}, i32 0, i32 2`);
+  B.line(`${ref} = load i32, ptr ${slot}`);
+  B.line(`${wide} = zext i32 ${ref} to i64`);
+  B.line(`${addr} = shl nuw nsw i64 ${wide}, 3`);
+  B.line(`${value} = inttoptr i64 ${addr} to ptr`);
+  return value;
+}
+
 /** Map.has / Set.has under a string key. */
-export function emitStringMapHas(host: LlvmEmitterContext, map: string, key: string): string {
-  const entry = emitStringMapEntry(host, map, key);
+export function emitStringMapHas(
+  host: LlvmEmitterContext,
+  map: string,
+  key: string,
+  compact = false,
+): string {
+  const entry = emitStringMapEntry(host, map, key, compact);
   const found = host.B.tmp();
   host.B.line(`${found} = icmp ne ptr ${entry}, null`);
   return found;
@@ -92,12 +140,18 @@ export function emitStringMapGetRef(
   map: string,
   key: string,
   value: IrType,
+  compact = false,
 ): string {
-  return emitMapEntryGetRef(host, emitStringMapEntry(host, map, key), value);
+  return emitMapEntryGetRef(host, emitStringMapEntry(host, map, key, compact), value, compact);
 }
 
 /** The +1 value of a found entry, or null for a missing (null) entry. */
-function emitMapEntryGetRef(host: LlvmEmitterContext, entry: string, value: IrType): string {
+function emitMapEntryGetRef(
+  host: LlvmEmitterContext,
+  entry: string,
+  value: IrType,
+  compact = false,
+): string {
   const B = host.B;
   const found = B.tmp();
   B.line(`${found} = icmp ne ptr ${entry}, null`);
@@ -106,7 +160,10 @@ function emitMapEntryGetRef(host: LlvmEmitterContext, entry: string, value: IrTy
     join = B.newLabel("mapn.join");
   B.condBr(found, hit, miss);
   B.startBlock(hit);
-  const retained = host.retainFrame(emitNumberMapSlot(host, entry, "ptr"), value);
+  const retained = host.retainFrame(
+    compact ? emitCompactMapSlot(host, entry) : emitNumberMapSlot(host, entry, "ptr"),
+    value,
+  );
   B.br(join);
   B.startBlock(miss);
   B.br(join);
@@ -199,20 +256,25 @@ export const SCR_MAP_NUM_DEAD = "9218868437227405313";
 
 /** The entry layout a Map or Set of key type `key` stores:
  * - "num": number keys, whose entries are { key, val } (scr_map.h ScrMapNumEntry);
+ * - "centry": string keys with compact values (compactMapValues), whose
+ *   entries are { key, hash, val } (ScrMapCEntry);
  * - "entry": every other typed key, whose entries are { key, val, hash };
  * - "either": checked (`unknown`) keys. A `Map<unknown, unknown>` or
  *   `Set<unknown>` cast from a checked value keeps the collection's own
- *   storage (scr_dyn_native_collection_check), which can have number keys. */
-export type MapEntryLayout = "num" | "entry" | "either";
+ *   storage (scr_dyn_native_collection_check), which can have number keys
+ *   or compact values. */
+export type MapEntryLayout = "num" | "centry" | "entry" | "either";
 
-export function mapEntryLayout(key: IrType): MapEntryLayout {
+export function mapEntryLayout(key: IrType, compact = false): MapEntryLayout {
+  if (compact) return "centry";
   return key.kind === "f64" ? "num" : key.kind === "dyn" ? "either" : "entry";
 }
 
 /** The entry at an iteration index, or null for a tombstone or an index at
  * or past the entry count (the scr_map_iter_live test). With the "either"
  * layout, the map's key kind (%ScrMapIx field 1, SCR_MAP_KEY_F64 = 0) picks
- * the step at run time. */
+ * the step at run time; in a program with compact class instances, so does
+ * its value kind (field 2, SCR_MAP_VAL_CREF = 3). */
 export function emitMapIterEntry(
   host: LlvmEmitterContext,
   map: string,
@@ -220,14 +282,20 @@ export function emitMapIterEntry(
   layout: MapEntryLayout,
 ): string {
   const B = host.B;
-  const step = (num: boolean): string => {
-    host.declare(num ? MAP_ITER_NUM_DECL : MAP_ITER_DECL);
+  const step = (kind: "num" | "centry" | "entry"): string => {
+    host.declare(kind === "num" ? MAP_ITER_NUM_DECL : MAP_ITER_DECL);
+    if (kind === "centry") host.declare(STRING_MAP_ENTRY_C_DECL);
     const entry = B.tmp();
-    const helper = num ? "sc_map_iter_entry_num" : "sc_map_iter_entry";
+    const helper =
+      kind === "num"
+        ? "sc_map_iter_entry_num"
+        : kind === "centry"
+          ? "sc_map_iter_entry_c"
+          : "sc_map_iter_entry";
     B.line(`${entry} = call ptr @${helper}(ptr ${map}, double ${index})`);
     return entry;
   };
-  if (layout !== "either") return step(layout === "num");
+  if (layout !== "either") return step(layout);
   host.declare(MAP_ITER_DECL);
   const kindPtr = B.tmp(),
     kind = B.tmp(),
@@ -240,16 +308,31 @@ export function emitMapIterEntry(
     join = B.newLabel("mapit.layout");
   B.condBr(isNum, numLabel, entryLabel);
   B.startBlock(numLabel);
-  const numEntry = step(true);
+  const numEntry = step("num");
   const numEnd = B.currentLabel();
   B.br(join);
   B.startBlock(entryLabel);
-  const otherEntry = step(false);
-  const entryEnd = B.currentLabel();
+  const arms: { value: string; label: string }[] = [{ value: numEntry, label: numEnd }];
+  if (host.shapeHost.compactRegion?.() === true) {
+    const valPtr = B.tmp(),
+      valKind = B.tmp(),
+      isCompact = B.tmp();
+    B.line(`${valPtr} = getelementptr inbounds %ScrMapIx, ptr ${map}, i32 0, i32 2`);
+    B.line(`${valKind} = load i8, ptr ${valPtr}`);
+    B.line(`${isCompact} = icmp eq i8 ${valKind}, 3`);
+    const compactLabel = B.newLabel("mapit.centry"),
+      wideLabel = B.newLabel("mapit.wide");
+    B.condBr(isCompact, compactLabel, wideLabel);
+    B.startBlock(compactLabel);
+    arms.push({ value: step("centry"), label: B.currentLabel() });
+    B.br(join);
+    B.startBlock(wideLabel);
+  }
+  arms.push({ value: step("entry"), label: B.currentLabel() });
   B.br(join);
   B.startBlock(join);
   const entry = B.tmp();
-  B.line(`${entry} = phi ptr [ ${numEntry}, %${numEnd} ], [ ${otherEntry}, %${entryEnd} ]`);
+  B.line(`${entry} = phi ptr ${arms.map((a) => `[ ${a.value}, %${a.label} ]`).join(", ")}`);
   return entry;
 }
 
@@ -270,6 +353,16 @@ export function emitMapIterCount(host: LlvmEmitterContext, map: string): string
   return count;
 }
 
+export const MAP_SIZE_DECL = "declare double @scr_map_size(ptr)";
+
+/** Map.size / Set.size: the live entry count, read inline (sc_map_size). */
+export function emitMapSize(host: LlvmEmitterContext, map: string): string {
+  host.declare(MAP_SIZE_DECL);
+  const size = host.B.tmp();
+  host.B.line(`${size} = call double @sc_map_size(ptr ${map})`);
+  return size;
+}
+
 /** The key (field 0) or value (field 1) of the live entry at an iteration
  * index, read inline: a number as double, a boolean as i1, and a string or
  * reference retained with `type`'s retain (+1), the adapter the collection
@@ -294,18 +387,24 @@ export function emitMapIterSlot(
     join = B.newLabel("mapit.join");
   B.condBr(found, hit, miss);
   B.startBlock(hit);
-  const slot = B.tmp();
-  B.line(`${slot} = getelementptr inbounds %ScrMapEntry, ptr ${entry}, i32 0, i32 ${field}`);
   const llTy = access === "f64" ? "double" : access === "bool" ? "i1" : "ptr";
-  let loaded = B.tmp();
-  if (access === "bool") {
-    const bits = loaded;
-    B.line(`${bits} = load i64, ptr ${slot}`);
-    loaded = B.tmp();
-    B.line(`${loaded} = icmp ne i64 ${bits}, 0`);
+  let loaded: string;
+  if (layout === "centry" && field === 1) {
+    // A compact value; its type's retain emits no counting.
+    loaded = host.retainFrame(emitCompactMapSlot(host, entry), type);
   } else {
-    B.line(`${loaded} = load ${llTy}, ptr ${slot}`);
-    if (access === "ref") loaded = host.retainFrame(loaded, type);
+    const slot = B.tmp();
+    B.line(`${slot} = getelementptr inbounds %ScrMapEntry, ptr ${entry}, i32 0, i32 ${field}`);
+    loaded = B.tmp();
+    if (access === "bool") {
+      const bits = loaded;
+      B.line(`${bits} = load i64, ptr ${slot}`);
+      loaded = B.tmp();
+      B.line(`${loaded} = icmp ne i64 ${bits}, 0`);
+    } else {
+      B.line(`${loaded} = load ${llTy}, ptr ${slot}`);
+      if (access === "ref") loaded = host.retainFrame(loaded, type);
+    }
   }
   const hitEnd = B.currentLabel();
   B.br(join);

packages/compiler/src/backend/llvm/map-read-lifetimes.ts

@@ -15,6 +15,7 @@ import {
   emitNumberMapGetScalar,
   emitStringMapGetScalar,
   emitStringMapGetRef,
+  compactMapValues,
 } from "./map-number-lookup.js";
 import { mapKeyAccess, mapKeyParamType } from "./shapes.js";
 import { rememberMapEntry } from "./map-entry-fusion.js";
@@ -323,7 +324,10 @@ export function emitStackMapRead(host: LlvmEmitterContext, read: LocalMapRead):
   } else if (isRefCounted(read.value)) {
     const stringKey = entryStringKey(key);
     let raw: string;
-    if (stringKey !== null) raw = emitStringMapGetRef(host, receiver.name, stringKey, read.value);
+    const mapType = read.receiver.type;
+    const compact = mapType.kind === "map" && compactMapValues(host, mapType.key, mapType.value);
+    if (stringKey !== null)
+      raw = emitStringMapGetRef(host, receiver.name, stringKey, read.value, compact);
     else {
       raw = B.tmp();
       host.declare(`declare ptr @scr_map_get_${access}_ref(ptr, ${keyType})`);

packages/compiler/src/backend/llvm/regex-matchers.test.ts

@@ -110,6 +110,25 @@ describe("regex literal matcher code", () => {
     expect(body("a\\d{1,3}")).not.toContain("<16 x i8>");
   });
 
+  test("fixed leading characters filter 16 start positions at once", () => {
+    // Both alternatives' first characters are tested at every offset and
+    // combined, and the reads reach seven characters past the block.
+    const text = body("agggtaaa|tttaccct", "gi");
+    expect(text.match(/load <16 x i8>/g)!.length).toBeGreaterThanOrEqual(16);
+    expect(text).toMatch(/and i16 /);
+    expect(text).toMatch(/or i16 /);
+    expect(text).toMatch(/add i32 %t\d+, 7\n/);
+    // A class sequence with a fixed count extends the filter.
+    expect(body("[cg]x{3}y")).toMatch(/and i16 /);
+    // An optional first character, a single first character and a
+    // variable-length start keep the first-character search.
+    expect(body("[ab]?cd")).not.toMatch(/and i16 /);
+    expect(body("[ab]*cd")).not.toMatch(/and i16 /);
+    expect(body("xy|zw")).toMatch(/and i16 /);
+    expect(body("[ab]|cd")).not.toMatch(/and i16 /);
+    expect(body("agggtaaa|tttaccct", "gi", false)).not.toContain("<16 x i8>");
+  });
+
   test("loops no continuation can share push no backtrack entries", () => {
     // \d+ then a dot; [^\]]+ then ]; the run at the end of the pattern.
     expect(body("\\d+\\.\\d+")).not.toContain("@scr_regex_stack_grow");

packages/compiler/src/backend/llvm/regex-matchers.ts

@@ -589,6 +589,90 @@ function firstOf(node: RxNode): FirstInfo {
   }
 }
 
+/** Positions the start filter tests and alternatives it keeps. */
+const PREFIX_LENGTH = 8;
+const PREFIX_ALTERNATIVES = 8;
+
+/** The character sets a match's first characters must belong to: every
+ * match of the node begins with the characters of some entry of `alts`,
+ * one set per character. `complete` means every match is exactly as long as
+ * its entry (so a following node continues the sequences). Null when the
+ * node gives no usable condition (an alternative that can start with
+ * anything, or too many alternatives). Assertions add no characters: the
+ * result stays a necessary condition. */
+interface Prefix {
+  alts: CharSet[][];
+  complete: boolean;
+}
+
+/** Each head followed by each tail, cut to PREFIX_LENGTH sets; null past
+ * PREFIX_ALTERNATIVES entries. */
+function crossPrefixes(heads: CharSet[][], tails: CharSet[][]): CharSet[][] | null {
+  if (heads.length * tails.length > PREFIX_ALTERNATIVES) return null;
+  const out: CharSet[][] = [];
+  for (const head of heads)
+    for (const tail of tails) out.push([...head, ...tail].slice(0, PREFIX_LENGTH));
+  return out;
+}
+
+/** Whether no entry was cut at PREFIX_LENGTH. */
+function uncut(alts: CharSet[][]): boolean {
+  return alts.every((alt) => alt.length < PREFIX_LENGTH);
+}
+
+function prefixOf(node: RxNode): Prefix | null {
+  switch (node.kind) {
+    case "set":
+      return { alts: [[node.set]], complete: true };
+    case "assert":
+      return { alts: [[]], complete: true };
+    case "cap":
+      return prefixOf(node.body);
+    case "alt": {
+      const alts: CharSet[][] = [];
+      let complete = true;
+      for (const alt of node.alts) {
+        const p = prefixOf(alt);
+        if (p === null) return null;
+        alts.push(...p.alts);
+        complete &&= p.complete;
+      }
+      return alts.length <= PREFIX_ALTERNATIVES ? { alts, complete } : null;
+    }
+    case "seq": {
+      let alts: CharSet[][] = [[]];
+      for (const item of node.items) {
+        const p = prefixOf(item);
+        if (p === null) return { alts, complete: false };
+        const joined = crossPrefixes(alts, p.alts);
+        if (joined === null) return { alts, complete: false };
+        alts = joined;
+        if (!p.complete || !uncut(alts)) return { alts, complete: false };
+      }
+      return { alts, complete: true };
+    }
+    case "rep": {
+      if (node.max === 0) return { alts: [[]], complete: true };
+      if (node.min === 0) return { alts: [[]], complete: false };
+      const body = prefixOf(node.body);
+      if (body === null) return null;
+      // The first `min` iterations are required; they extend the sequences
+      // while the body has a fixed length.
+      let alts = body.alts;
+      let covered = 1;
+      while (covered < node.min && body.complete && uncut(alts)) {
+        const joined = crossPrefixes(alts, body.alts);
+        if (joined === null) break;
+        alts = joined;
+        covered++;
+      }
+      const complete =
+        body.complete && covered === node.min && node.min === node.max && uncut(alts);
+      return { alts, complete };
+    }
+  }
+}
+
 /** Whether a node can match without consuming (assertions included). */
 function canMatchEmpty(node: RxNode): boolean {
   switch (node.kind) {
@@ -721,16 +805,74 @@ class RxGen {
     return wide;
   }
 
+  /** The vector plans of a start filter (prefixOf): per alternative, the
+   * plans of its first sets up to the first set without one. Null unless
+   * every alternative keeps at least two positions, where the filter is
+   * more selective than the first character alone. */
+  prefixPlans(prefix: Prefix | null): { ranges: number[][]; negate: boolean }[][] | null {
+    if (prefix === null || !this.vector) return null;
+    const plans: { ranges: number[][]; negate: boolean }[][] = [];
+    for (const alt of prefix.alts) {
+      const row: { ranges: number[][]; negate: boolean }[] = [];
+      for (const set of alt) {
+        const plan = this.vectorPlan(set);
+        if (plan === null) break;
+        row.push(plan);
+      }
+      if (row.length < 2) return null;
+      plans.push(row);
+    }
+    return plans.length === 0 ? null : plans;
+  }
+
+  /** Start positions s[index..index+16) where some alternative of the
+   * filter matches its first sets: an i16 mask. */
+  testPrefix(plans: { ranges: number[][]; negate: boolean }[][], index: string): string {
+    let any = "";
+    for (const row of plans) {
+      let all = "";
+      for (let k = 0; k < row.length; k++) {
+        let at = index;
+        if (k > 0) {
+          at = this.tmp();
+          this.line(`${at} = add i32 ${index}, ${k}`);
+        }
+        const bits = this.testVector(row[k]!, at);
+        if (all === "") all = bits;
+        else {
+          const both = this.tmp();
+          this.line(`${both} = and i16 ${all}, ${bits}`);
+          all = both;
+        }
+      }
+      if (any === "") any = all;
+      else {
+        const either = this.tmp();
+        this.line(`${either} = or i16 ${any}, ${all}`);
+        any = either;
+      }
+    }
+    return any;
+  }
+
   /** The first-character search: from %at, store the next position whose
-   * character is in `set` and branch to %attempt, or branch to %nomatch. */
-  emitSeek(set: CharSet): void {
+   * character is in `set` and branch to %attempt, or branch to %nomatch.
+   * With a start filter (`prefix`), the vector loop tests the filter's
+   * first sets of each alternative at 16 start positions at once and stops
+   * only where one of them matches all of its sets; a match can start
+   * nowhere else, so the attempts that remain are the ones that can
+   * succeed, in the same order. */
+  emitSeek(set: CharSet, prefix: Prefix | null = null): void {
     this.block("seek");
     const a = this.tmp();
     this.line(`${a} = load i32, ptr %at`);
+    const filter = this.prefixPlans(prefix);
     const plan = this.vectorPlan(set);
+    // The filter reads s[i + reach + 15] at its farthest.
+    const reach = filter === null ? 0 : Math.max(...filter.map((row) => row.length)) - 1;
     let from = "seek",
       start = a;
-    if (plan !== null) {
+    if (plan !== null || filter !== null) {
       const head = this.label("vsh"),
         load = this.label("vsl"),
         next = this.label("vsn"),
@@ -740,17 +882,21 @@ class RxGen {
       this.block(head);
       const i = this.tmp(),
         i16 = this.tmp(),
+        rest = this.tmp(),
         fits = this.tmp();
       this.line(`${i} = phi i32 [ ${a}, %seek ], [ ${i16}, %${next} ]`);
-      this.line(`${i16} = add i32 ${i}, 16`);
-      this.line(`${fits} = icmp sle i32 ${i16}, %len`);
+      // The characters left (0 <= i <= len, so this cannot wrap; i + 16
+      // can for subjects near 2^31 characters).
+      this.line(`${rest} = sub i32 %len, ${i}`);
+      this.line(`${fits} = icmp sge i32 ${rest}, ${16 + reach}`);
       this.line(`br i1 ${fits}, label %${load}, label %${tail}`);
       this.block(load);
-      const mask = this.testVector(plan, i),
+      const mask = filter !== null ? this.testPrefix(filter, i) : this.testVector(plan!, i),
         any = this.tmp();
       this.line(`${any} = icmp ne i16 ${mask}, 0`);
       this.line(`br i1 ${any}, label %${hit}, label %${next}`);
       this.block(next);
+      this.line(`${i16} = add i32 ${i}, 16`);
       this.line(`br label %${head}`);
       this.block(hit);
       const k = this.lowestBit(mask),
@@ -1001,10 +1147,10 @@ class RxGen {
       check = this.label("chk");
     this.block(entry);
     const p = this.loadPos(),
-      end = this.tmp(),
+      rest = this.tmp(),
       inb = this.tmp();
-    this.line(`${end} = add i32 ${p}, ${sets.length}`);
-    this.line(`${inb} = icmp sle i32 ${end}, %len`);
+    this.line(`${rest} = sub i32 %len, ${p}`);
+    this.line(`${inb} = icmp sge i32 ${rest}, ${sets.length}`);
     this.line(`br i1 ${inb}, label %${check}, label %fail`);
     this.block(check);
     let acc = "";
@@ -1023,6 +1169,8 @@ class RxGen {
         acc = both;
       }
     }
+    const end = this.tmp();
+    this.line(`${end} = add i32 ${p}, ${sets.length}`);
     // Storing before the branch is safe: every resume sets the position.
     this.storePos(end);
     this.line(`br i1 ${acc}, label %${succ}, label %fail`);
@@ -1229,10 +1377,11 @@ class RxGen {
       this.block(vhead);
       const kv = this.tmp(),
         kv16 = this.tmp(),
+        left = this.tmp(),
         fits = this.tmp();
       this.line(`${kv} = phi i32 [ 0, %${entry} ], [ ${kv16}, %${vnext} ]`);
-      this.line(`${kv16} = add i32 ${kv}, 16`);
-      this.line(`${fits} = icmp sle i32 ${kv16}, ${lim}`);
+      this.line(`${left} = sub i32 ${lim}, ${kv}`);
+      this.line(`${fits} = icmp sge i32 ${left}, 16`);
       this.line(`br i1 ${fits}, label %${vload}, label %${tail}`);
       this.block(vload);
       const vat = this.tmp();
@@ -1242,6 +1391,7 @@ class RxGen {
       this.line(`${all} = icmp eq i16 ${mask}, -1`);
       this.line(`br i1 ${all}, label %${vnext}, label %${vexit}`);
       this.block(vnext);
+      this.line(`${kv16} = add i32 ${kv}, 16`);
       this.line(`br label %${vhead}`);
       this.block(vexit);
       const missing = this.tmp();
@@ -1769,7 +1919,10 @@ export function compileRegexMatcher(
       fn.push(`  store i32 %off.n, ptr %at`);
       fn.push(`  br label %attempt`);
     } else {
-      gen.emitSeek(first.set);
+      // A start filter over the first few characters (a single first byte
+      // keeps memchr).
+      const prefix = prefixOf(root);
+      gen.emitSeek(first.set, gen.prefixPlans(prefix) === null ? null : prefix);
     }
   }
 

packages/compiler/src/backend/llvm/running-extrema.test.ts

@@ -0,0 +1,97 @@
+import { expect, test } from "vitest";
+import { BOOL, F64, type IrExpr, type IrFunction, type IrStmt } from "../../ir/ir.js";
+import { runningExtremumUpdates } from "./running-extrema.js";
+
+const loc = { file: "extrema.ts", start: 0, end: 0 };
+const ref = (localId: string): IrExpr => ({ kind: "varRef", localId, type: F64, loc });
+const num = (value: number): IrExpr => ({ kind: "numLit", value, type: F64, loc });
+const assign = (localId: string, value: IrExpr): IrStmt => ({
+  kind: "assign",
+  localId,
+  value,
+  loc,
+});
+const decl = (localId: string): IrStmt => ({ kind: "varDecl", localId, init: num(0), loc });
+const compare = (op: "<" | ">", left: IrExpr, right: IrExpr): IrExpr => ({
+  kind: "bin",
+  op,
+  left,
+  right,
+  type: BOOL,
+  loc,
+});
+/** `if (v > max) max = v;` */
+const update = (): IrStmt & { kind: "if" } => ({
+  kind: "if",
+  cond: compare(">", ref("v"), ref("max")),
+  then: [assign("max", ref("v"))],
+  else_: null,
+  loc,
+});
+const loop = (body: IrStmt[]): IrStmt => ({
+  kind: "while",
+  cond: compare(">", ref("n"), num(0)),
+  body,
+  loc,
+});
+const fn = (body: IrStmt[], captures: string[] = []): IrFunction => ({
+  name: "scan",
+  params: [],
+  locals: ["v", "max", "n"].map((id) => ({ id, name: id, type: F64, mutable: true })),
+  captures: captures.map((localId) => ({ localId, name: localId, type: F64 })),
+  returnType: F64,
+  body,
+  loc,
+});
+
+test("a loop's update of an accumulator declared outside it qualifies", () => {
+  const s = update();
+  expect(runningExtremumUpdates(fn([decl("max"), loop([decl("v"), s])])).has(s)).toBe(true);
+});
+
+test("the local may be on either side of the comparison", () => {
+  const s = update();
+  s.cond = compare("<", ref("max"), ref("v"));
+  expect(runningExtremumUpdates(fn([decl("max"), loop([s])])).has(s)).toBe(true);
+});
+
+test("a local declared in the loop is not an accumulator", () => {
+  const s = update();
+  expect(runningExtremumUpdates(fn([loop([decl("max"), s])])).size).toBe(0);
+});
+
+test("another write in the loop disqualifies the update", () => {
+  const s = update();
+  const body = [decl("max"), loop([assign("max", num(1)), s])];
+  expect(runningExtremumUpdates(fn(body)).size).toBe(0);
+});
+
+test("the assigned value must be the compared expression", () => {
+  const s = update();
+  s.then = [assign("max", num(5))];
+  expect(runningExtremumUpdates(fn([decl("max"), loop([s])])).size).toBe(0);
+});
+
+test("outside a loop only a captured binding qualifies", () => {
+  const captured = update();
+  expect(runningExtremumUpdates(fn([captured], ["max"])).has(captured)).toBe(true);
+  expect(runningExtremumUpdates(fn([update()])).size).toBe(0);
+});
+
+test("an else branch disqualifies the update", () => {
+  const s = update();
+  s.else_ = [assign("v", num(0))];
+  expect(runningExtremumUpdates(fn([decl("max"), loop([s])])).size).toBe(0);
+});
+
+test("an update nested in another branch does not qualify", () => {
+  const s = update();
+  const guard: IrStmt = {
+    kind: "if",
+    cond: compare(">", ref("v"), num(0)),
+    then: [s],
+    else_: null,
+    loc,
+  };
+  expect(runningExtremumUpdates(fn([decl("max"), loop([guard])])).size).toBe(0);
+});

packages/compiler/src/backend/llvm/running-extrema.ts

@@ -0,0 +1,110 @@
+// Running maximum and minimum updates, `if (v > max) { max = v; ... }`.
+// With the accumulator in a register LLVM turns such an update into a
+// select (`maxsd`, or a compare and mask), so every element waits on the
+// previous one's. The update gets rarer as a scan goes on, so a branch
+// predicts well; emitStmtBody gives these `if`s branch weights that say the
+// update is rarely taken, and LLVM keeps the branch. A clamp of a value read
+// in the same iteration is not an accumulator and keeps its select: its
+// branch would go whichever way the data goes. An update nested in another
+// branch keeps its select too: kept, its branch can stop LLVM from turning
+// the enclosing branch into selects, and that branch may follow the data.
+
+import type { IrExpr, IrFunction, IrStmt } from "../../ir/ir.js";
+import { everyExprChild, everyStmtChild } from "../../ir/traverse.js";
+
+type Loop = IrStmt & { kind: "for" | "while" | "doWhile" | "forOf" };
+
+const RELATIONAL = new Set(["<", "<=", ">", ">="]);
+
+/** The `if` statements of `fn` that update a running maximum or minimum:
+ * no `else`, a numeric `<`, `<=`, `>` or
+ * `>=` between a local and another expression, and a then-block that
+ * assigns that expression to the local. The local must carry across
+ * iterations: inside a loop the `if` is a statement of the innermost loop's
+ * body, the local is declared outside that loop, and the loop writes it only
+ * in this `if`; outside any loop the `if` is a statement of the function
+ * body and the local is a binding the function captures and writes only in
+ * this `if` (a callback that a loop elsewhere calls). */
+export function runningExtremumUpdates(fn: IrFunction): Set<IrStmt> {
+  const found = new Set<IrStmt>();
+  const captured = new Set((fn.captures ?? []).map((c) => c.localId));
+  const loops: Loop[] = [];
+  const candidates: { s: IrStmt; local: string; loop: Loop | undefined }[] = [];
+  const expr = (e: IrExpr): boolean => everyExprChild(e, expr, stmt);
+  const stmt = (s: IrStmt): boolean => {
+    if (s.kind === "if") {
+      const local = updatedExtremum(s);
+      if (local !== undefined) candidates.push({ s, local, loop: loops[loops.length - 1] });
+    }
+    const loop =
+      s.kind === "for" || s.kind === "while" || s.kind === "doWhile" || s.kind === "forOf";
+    if (loop) loops.push(s);
+    everyStmtChild(s, expr, stmt);
+    if (loop) loops.pop();
+    return true;
+  };
+  for (const s of fn.body) stmt(s);
+  for (const { s, local, loop } of candidates) {
+    const scope = loop ?? (captured.has(local) ? fn.body : undefined);
+    const body = loop ? loop.body : fn.body;
+    if (scope !== undefined && body.includes(s) && writes(scope, local) === 1) found.add(s);
+  }
+  return found;
+}
+
+/** The local an `if` updates to a new maximum or minimum, if it is one. */
+function updatedExtremum(s: IrStmt & { kind: "if" }): string | undefined {
+  if (s.else_ !== null && s.else_.length > 0) return undefined;
+  const c = s.cond;
+  if (c.kind !== "bin" || !RELATIONAL.has(c.op)) return undefined;
+  if (c.left.type.kind !== "f64" || c.right.type.kind !== "f64") return undefined;
+  for (const [local, other] of [
+    [c.left, c.right],
+    [c.right, c.left],
+  ]) {
+    if (local!.kind !== "varRef") continue;
+    const id = local!.localId;
+    const assigns = s.then.some(
+      (x) => x.kind === "assign" && x.localId === id && sameExpr(x.value, other!),
+    );
+    if (assigns) return id;
+  }
+  return undefined;
+}
+
+/** Declarations and writes of `local` under `scope`. A declaration counts
+ * as a write too, so a local declared inside a loop does not qualify. */
+function writes(scope: IrStmt | IrStmt[], local: string): number {
+  let n = 0;
+  const expr = (e: IrExpr): boolean => {
+    if ((e.kind === "assignExpr" || e.kind === "incDec") && e.localId === local) n++;
+    return everyExprChild(e, expr, stmt);
+  };
+  const stmt = (s: IrStmt): boolean => {
+    if ((s.kind === "assign" || s.kind === "varDecl" || s.kind === "forOf") && s.localId === local)
+      n++;
+    else if (s.kind === "tryCatch" && s.catchLocalId === local) n++;
+    return everyStmtChild(s, expr, stmt);
+  };
+  if (Array.isArray(scope)) for (const s of scope) stmt(s);
+  else stmt(scope);
+  return n;
+}
+
+/** Structural equality of two small expressions (`v`, `a[i]`), ignoring
+ * source locations and types; larger expressions do not compare equal. */
+function sameExpr(a: IrExpr, b: IrExpr): boolean {
+  let budget = 64;
+  const same = (x: unknown, y: unknown): boolean => {
+    if (--budget < 0) return false;
+    if (typeof x !== "object" || x === null || typeof y !== "object" || y === null) return x === y;
+    if (Array.isArray(x) !== Array.isArray(y)) return false;
+    const keys = Object.keys(x).filter((k) => k !== "loc" && k !== "type");
+    if (keys.length !== Object.keys(y).filter((k) => k !== "loc" && k !== "type").length)
+      return false;
+    return keys.every((k) =>
+      same((x as Record<string, unknown>)[k], (y as Record<string, unknown>)[k]),
+    );
+  };
+  return same(a, b);
+}

packages/compiler/src/backend/llvm/shapes.ts

@@ -71,6 +71,12 @@ export interface ShapeHost {
   /** The hierarchy root of a class (a program class or a runtime base),
    * or undefined for classes outside the class graph. */
   classRootOf?(className: string): string | undefined;
+  /** Whether arrays of `elem` hold 32-bit references to compact class
+   * instances (SCR_ELEM_CREF; LlEmitter.compactArrayElem). */
+  compactArrayElem?(elem: IrType): boolean;
+  /** Whether compact class instances live in the program-lifetime region
+   * (LlEmitter.compactRegion). */
+  compactRegion?(): boolean;
   /** Byte offset from an object pointer back to ScrCycHdr.buf. */
   readonly cycleBufOffset: number;
   declare(decl: string): void;
@@ -564,14 +570,16 @@ export function inlineRcFamily(host: ShapeHost, stem: string, op: RcOp): InlineR
 }
 
 /** Which RC fast paths an emission inlines. `speed` mirrors every family
- * with a fast path. `release` mirrors only the string retain and the dyn
- * retain and release: the operations that dominate dynamic-value and string
- * code, at almost no size cost. String releases stay calls in `release`
- * because string-heavy programs have many release sites. */
+ * with a fast path. `release` mirrors only the string and Map retains and
+ * the dyn retain and release: the operations that dominate dynamic-value,
+ * string and Map code (a Map read from an array or another Map), at almost
+ * no size cost. String releases stay calls in `release` because
+ * string-heavy programs have many release sites. */
 export type InlineRcMode = "release" | "speed";
 
 const RELEASE_RC_OPS = new Set([
   "str:retain",
+  "map:retain",
   "dyn:retain",
   "dyn:release",
   "js:retain",
@@ -1076,18 +1084,30 @@ export function arrNewCall(
 
 /** The %ScrArrOps descriptor (retain, release, trace, registry id) of a REF
  * element type, defined once per module and shared by all its arrays. It is
- * writable: the runtime stores its registry id on the first array. */
+ * writable: the runtime stores its registry id on the first array. Its tail
+ * padding is the runtime's flags word (0); arrays of compact class
+ * references (ShapeHost.compactArrayElem) spell the word out as
+ * SCR_ARR_OPS_COMPACT. */
 export function arrOps(host: ShapeHost, elem: IrType): string {
   const v = vAdapters(host, elem);
   const trace = traceArg(host, elem);
   const part = (sym: string): string => sym.replace(/^@/, "").replace(/[^A-Za-z0-9_.]/g, "_");
   const name = `@sc_arrops.${part(v.retain)}.${part(v.release)}.${part(trace)}`;
+  if (host.compactArrayElem?.(elem) === true) {
+    host.declare(
+      `${name}.c = internal global { ptr, ptr, ptr, i32, i32 } { ptr ${v.retain}, ptr ${v.release}, ptr ${trace}, i32 0, i32 ${SCR_ARR_OPS_COMPACT} }`,
+    );
+    return `${name}.c`;
+  }
   host.declare(
     `${name} = internal global %ScrArrOps { ptr ${v.retain}, ptr ${v.release}, ptr ${trace}, i32 0 }`,
   );
   return name;
 }
 
+/** scr_array.h SCR_ARR_OPS_COMPACT. */
+const SCR_ARR_OPS_COMPACT = 1;
+
 /* ── capture boxes ────────────────────────────────────────────────────── */
 
 /** Box construction call text (boxNewC's dispatch): plain-kind boxes for

packages/compiler/src/backend/native-link-info-core.ts

@@ -91,6 +91,15 @@ export interface NativeLinkFeatures {
   /** crypto.createECDH and ECDH.convertKey: scr_ecdh.c plus the mbedTLS
    * archive. */
   ecdh: boolean;
+  /** crypto.createDiffieHellman, getDiffieHellman and
+   * createDiffieHellmanGroup: scr_dh.c plus the mbedTLS archive. */
+  dh: boolean;
+  /** Asymmetric KeyObjects, crypto.sign/verify and Sign/Verify: scr_pki.c
+   * plus the mbedTLS archive. */
+  pki: boolean;
+  /** Ed25519 keys and signatures with pki: scr_ed25519.c (the vendored
+   * libsodium Ed25519). */
+  ed25519: boolean;
   /** perf_hooks event-loop metrics: scr_perf_loop.c. */
   perfLoop: boolean;
   tlsCa: boolean;

packages/compiler/src/backend/native/contracts.ts

@@ -6,6 +6,10 @@ export interface CcOptions {
    * LLVM backend's .ll — clang compiles IR text natively on the same
    * command line, so both ride this one seat. */
   cPath: string;
+  /** Where the program TU's bytes are read from, when that is not `cPath`: an invocation-private
+   * copy that a concurrent build of another program cannot replace. `cPath` stays the spelling
+   * clang sees (`__FILE__`, debug file names) and the one cache keys name. */
+  cSourcePath?: string;
   /** Path of the native executable to produce. */
   outPath: string;
   /** Additional identity for a translation unit whose complete non-system
@@ -250,6 +254,16 @@ export interface CcOptions {
   /** crypto.createECDH and ECDH.convertKey: compiles scr_ecdh.c and links
    * the mbedTLS archive (shared with tls). */
   ecdh?: boolean;
+  /** crypto.createDiffieHellman, getDiffieHellman and
+   * createDiffieHellmanGroup: compiles scr_dh.c and links the mbedTLS
+   * archive (shared with tls). */
+  dh?: boolean;
+  /** Asymmetric KeyObjects and signatures: compiles scr_pki.c and links
+   * the mbedTLS archive. */
+  pki?: boolean;
+  /** Ed25519 with pki: compiles scr_ed25519.c (the vendored libsodium
+   * Ed25519). */
+  ed25519?: boolean;
   /** crypto.subtle importKey/sign/verify/digest: compiles scr_webcrypto.c. */
   webcrypto?: boolean;
   /** perf_hooks event-loop metrics: compiles scr_perf_loop.c. */

packages/compiler/src/backend/native/executable.ts

@@ -114,6 +114,8 @@ interface RuntimeUnitContext {
   tlsCa: boolean;
   cipher: boolean;
   ecdh: boolean;
+  dh: boolean;
+  pki: boolean;
   lreObjects: readonly string[];
   zlibObjects: readonly string[];
   tlsArchive: string | null;
@@ -297,6 +299,8 @@ const RUNTIME_UNITS: readonly RuntimeUnit[] = [
   unit((u) => u.opts.foreignFfi, "scr_ffi_queue.c"),
   unit((u) => u.opts.nodeTest, "scr_test.c"),
   unit((u) => u.opts.webcrypto, "scr_webcrypto.c"),
+  unit((u) => u.opts.webcrypto === true && u.opts.pki === true, "scr_webcrypto_pki.c"),
+  unit((u) => u.opts.pki === true && u.opts.ed25519 === true, "scr_ed25519.c"),
   // The crypto global's object extends scr_async_dyn.c's.
   unit((u) => u.opts.webcrypto && u.opts.dynAsync, "scr_webcrypto_object.c"),
   // The CA-store unit rides its own gate OR the tls one: scr_tls.c
@@ -310,6 +314,8 @@ const RUNTIME_UNITS: readonly RuntimeUnit[] = [
           ...(u.tls ? [u.rt(join(u.rtDir, "scr_tls.c"))] : []),
           ...(u.cipher ? [u.rt(join(u.rtDir, "scr_cipher.c"))] : []),
           ...(u.ecdh ? [u.rt(join(u.rtDir, "scr_ecdh.c"))] : []),
+          ...(u.dh ? [u.rt(join(u.rtDir, "scr_dh.c"))] : []),
+          ...(u.pki ? [u.rt(join(u.rtDir, "scr_pki.c"))] : []),
           ...(u.cipher && u.opts.webcrypto ? [u.rt(join(u.rtDir, "scr_webcrypto_aes.c"))] : []),
           u.tlsArchive,
           // mbedTLS's win32 entropy poll is BCryptGenRandom (bcrypt.h).
@@ -375,10 +381,13 @@ export async function compileCInternal(
   const http = (opts.http ?? false) || nativeFetch;
   const tls = (opts.tls ?? false) || nativeFetch;
   const tlsCa = (opts.tlsCa ?? false) || tls;
-  // Symmetric ciphers and ECDH link the same mbedTLS archive as TLS.
+  // Symmetric ciphers, ECDH and DiffieHellman link the same mbedTLS
+  // archive as TLS.
   const cipher = opts.cipher ?? false;
   const ecdh = opts.ecdh ?? false;
-  const mbedtls = tls || cipher || ecdh;
+  const dh = opts.dh ?? false;
+  const pki = opts.pki ?? false;
+  const mbedtls = tls || cipher || ecdh || dh || pki;
   const driver = resolveCc();
   const darwinDebugSymbols = needsDarwinDebugSymbols(
     targetPlatform(driver),
@@ -484,7 +493,7 @@ export async function compileCInternal(
       const [compiler, runtimeHash, programBytes] = await Promise.all([
         resolvedTool(driver.argv[0] ?? "clang"),
         runtimeFingerprint(rtDir),
-        readFile(opts.cPath),
+        readFile(opts.cSourcePath ?? opts.cPath),
       ]);
       if (compiler !== null) {
         const effectiveCompiler =
@@ -736,6 +745,8 @@ export async function compileCInternal(
       tlsCa,
       cipher,
       ecdh,
+      dh,
+      pki,
       lreObjects,
       zlibObjects,
       tlsArchive,
@@ -864,7 +875,12 @@ export async function compileCInternal(
       );
     try {
       await materializeVendorPrerequisites(undefined, privateVendorRoot);
-      await buildExecutable((p) => p);
+      await buildExecutable(
+        (p) => p,
+        opts.cSourcePath === undefined
+          ? {}
+          : { programPath: opts.cSourcePath, compilerVisibleSource: opts.cPath },
+      );
     } finally {
       await rm(privateVendorRoot, { recursive: true, force: true }).catch(() => undefined);
     }
@@ -899,7 +915,9 @@ export async function compileCInternal(
         localArtifact === null
           ? runtimeFingerprint(rtDir)
           : Promise.resolve(localArtifact.runtimeHash),
-        localArtifact === null ? readFile(opts.cPath) : Promise.resolve(localArtifact.programBytes),
+        localArtifact === null
+          ? readFile(opts.cSourcePath ?? opts.cPath)
+          : Promise.resolve(localArtifact.programBytes),
       ]);
       compileMetadataStamp =
         compileMetadataKey === null
@@ -968,7 +986,7 @@ export async function compileCInternal(
       Promise.all([
         ccVersion(driver.argv, toolchainEnv, true),
         runtimeFingerprint(rtDir),
-        readFile(opts.cPath),
+        readFile(opts.cSourcePath ?? opts.cPath),
       ]));
   } catch (error) {
     // A version/fingerprint probe is an optimization boundary. If the compiler

packages/compiler/src/backend/runtime-abi.ts

@@ -2,8 +2,8 @@
  * of the link contract: a program object keeps this symbol undefined and the
  * matching runtime defines it, so incompatible manual links fail before the
  * program can start. */
-export const RUNTIME_ABI_VERSION = 25 as const;
-export const RUNTIME_ABI_MARKER = "scr_runtime_abi_v25" as const;
+export const RUNTIME_ABI_VERSION = 27 as const;
+export const RUNTIME_ABI_MARKER = "scr_runtime_abi_v27" as const;
 
 /** Object consumption is useful today, but the complete scr_* surface may
  * still change before 1.0. The versioned marker prevents accidental mixing;

packages/compiler/src/backend/runtime-pack-targets.test.ts

@@ -52,7 +52,7 @@ async function fixture(target: NativeTargetSpec, workers = false) {
       object_format: target.objectFormat,
       minimum_os: target.minimumOs,
     },
-    runtime_abi: { version: 25, marker: "scr_runtime_abi_v25" },
+    runtime_abi: { version: 27, marker: "scr_runtime_abi_v27" },
     compiler: { command: "fixture", identity: "fixture", target: target.llvmTriple },
     macros: { executable: [], excluded: ["SCR_LIB"], sanitizer: "external-toolchain-required" },
     flavors: {
@@ -125,6 +125,9 @@ const features = {
   tlsCa: false,
   cipher: false,
   ecdh: false,
+  dh: false,
+  pki: false,
+  ed25519: false,
   webcrypto: false,
   perfLoop: false,
 };

packages/compiler/src/backend/runtime-pack.test.ts

@@ -61,6 +61,9 @@ const BASE: NativeLinkFeatures = {
   tlsCa: false,
   cipher: false,
   ecdh: false,
+  dh: false,
+  pki: false,
+  ed25519: false,
   webcrypto: false,
   perfLoop: false,
 };
@@ -124,7 +127,7 @@ async function fixture(target: NativeTargetSpec = MACOS_ARM64_TARGET) {
       object_format: target.objectFormat,
       minimum_os: target.minimumOs,
     },
-    runtime_abi: { version: 25, marker: "scr_runtime_abi_v25" },
+    runtime_abi: { version: 27, marker: "scr_runtime_abi_v27" },
     compiler: {
       command: "clang",
       identity: "fixture clang",

packages/compiler/src/backend/target-diagnostics.ts

@@ -2,7 +2,12 @@ import { everyModuleNode, everyStmtList, transformStmtList } from "../ir/travers
 import type { LlvmUnsupportedError } from "./llvm/emitter.js";
 import type { ScrDiagnostic } from "../diagnostics/diagnostic.js";
 import { type IrModule, type SrcLoc } from "../ir/ir.js";
-import { moduleUsesFetch } from "../ir/runtime-features.js";
+import {
+  DH_LIB_FNS,
+  PKI_LIB_FNS,
+  moduleUsesFetch,
+  moduleUsesWebCryptoAsymmetric,
+} from "../ir/runtime-features.js";
 
 /** Reflection tables expose methods that the program never calls. On WASI,
  * keep their host-only implementations as explicit runtime refusals. Typed
@@ -208,10 +213,15 @@ export function moduleWasiUnavailableSurface(
         };
         return false;
       }
-      if (node.fn === "webcrypto.encrypt" || node.fn === "webcrypto.decrypt") {
+      if (
+        node.fn === "webcrypto.encrypt" ||
+        node.fn === "webcrypto.decrypt" ||
+        node.fn === "webcrypto.wrapKey" ||
+        node.fn === "webcrypto.unwrapKey"
+      ) {
         found = {
           surface:
-            "WebCrypto encrypt and decrypt (the wasm32-wasi runtime does not include the mbedTLS library)",
+            "WebCrypto encrypt, decrypt, wrapKey and unwrapKey (the wasm32-wasi runtime does not include the mbedTLS library)",
           loc,
         };
         return false;
@@ -223,6 +233,24 @@ export function moduleWasiUnavailableSurface(
         };
         return false;
       }
+      if (DH_LIB_FNS.has(node.fn)) {
+        found = {
+          surface:
+            node.fn === "crypto.dhNew" || node.fn === "crypto.dhGroupNew"
+              ? "DiffieHellman (the wasm32-wasi runtime does not include the mbedTLS library)"
+              : "checkPrime and generatePrime (the wasm32-wasi runtime does not include the mbedTLS library)",
+          loc,
+        };
+        return false;
+      }
+      if (PKI_LIB_FNS.has(node.fn)) {
+        found = {
+          surface:
+            "asymmetric keys and signatures (the wasm32-wasi runtime does not include the mbedTLS library)",
+          loc,
+        };
+        return false;
+      }
       if (node.fn === "os.networkInterfaces") {
         found = {
           surface: "network-interface enumeration (WASI Preview 1 has no interface API)",
@@ -249,5 +277,12 @@ export function moduleWasiUnavailableSurface(
   if (moduleUsesFetch(mod)) {
     return { surface: "network-backed fetch (WASI Preview 1 has no socket API)", loc: entryLoc };
   }
+  if (moduleUsesWebCryptoAsymmetric(mod)) {
+    return {
+      surface:
+        "WebCrypto ECDSA and RSA (the wasm32-wasi runtime does not include the mbedTLS library)",
+      loc: entryLoc,
+    };
+  }
   return null;
 }

packages/compiler/src/backend/warm-cache.ts

@@ -67,6 +67,9 @@ export async function warmNativeCaches(
         tls: false,
         cipher: false,
         ecdh: false,
+        dh: false,
+        pki: false,
+        ed25519: false,
         webcrypto: false,
         perfLoop: false,
         tlsCa: false,

packages/compiler/src/coverage/report.ts

@@ -318,12 +318,23 @@ export function renderCoverage(input: CoverageInput, opts: CoverageRenderOptions
   // statements the module carries): they compile, but executing one
   // throws its SC-coded error — the report lists them so a "compiling"
   // JS program never hides its dynamic gaps.
+  // Fences in a module's top-level code run when the module initializes:
+  // they are listed first, as sites that run at startup.
   const fences = input.runtimeFences ?? [];
-  if (fences.length > 0) {
+  const startup = fences.filter((d) => d.startup === true);
+  const later = fences.filter((d) => d.startup !== true);
+  if (startup.length > 0) {
     out.push(
-      `  ${c(YELLOW, "deferred to runtime")}   ${fences.length} site${fences.length === 1 ? "" : "s"} ${c(DIM, "(JS statements that throw their fence if executed)")}`,
+      `  ${c(YELLOW, "runs at startup")}   ${startup.length} site${startup.length === 1 ? "" : "s"} ${c(DIM, "(JS statements in module top-level code, which runs when the module loads)")}`,
     );
-    renderRows(groupBlockers(fences, "deferred"), YELLOW);
+    renderRows(groupBlockers(startup, "deferred"), YELLOW);
+    out.push("");
+  }
+  if (later.length > 0) {
+    out.push(
+      `  ${c(YELLOW, "deferred to runtime")}   ${later.length} site${later.length === 1 ? "" : "s"} ${c(DIM, "(JS statements that throw their fence if executed)")}`,
+    );
+    renderRows(groupBlockers(later, "deferred"), YELLOW);
     out.push("");
   }
 

packages/compiler/src/diagnostics/diagnostic.ts

@@ -92,6 +92,10 @@ export interface ScrDiagnostic {
    * the error may not reproduce under the project's tsc. Machine-readable
    * output reports these under the "environment" category. */
   typeWorld?: boolean;
+  /** A runtime fence in a module's top-level code, outside every function
+   * and class member body: it throws when the module initializes, which is
+   * program startup for a module the entry imports. */
+  startup?: true;
 }
 
 /** SC3002–SC3004 — native-helper target, installation, and execution

packages/compiler/src/diagnostics/envelope.ts

@@ -67,6 +67,9 @@ export interface LocatedDiagnostic extends SourcePosition {
   hint: string;
   /** The id of the root-cause group this site belongs to. */
   group: string;
+  /** Deferred scope only: the statement is module top-level code, so it
+   * runs when its module loads. */
+  startup?: true;
 }
 
 export interface DiagnosticGroup {
@@ -290,6 +293,7 @@ export function locateDiagnostic(
     message: diag.message,
     hint: hintOf(diag),
     group: groupId(diag, scope),
+    ...(scope === "deferred" && diag.startup === true ? { startup: true as const } : {}),
   };
 }
 

packages/compiler/src/executable/executable-cache.test.ts

@@ -65,6 +65,9 @@ const native: EarlyExecutableNativeFeatures = {
   tlsCa: false,
   cipher: false,
   ecdh: false,
+  dh: false,
+  pki: false,
+  ed25519: false,
   webcrypto: false,
   perfLoop: false,
 };
@@ -133,8 +136,15 @@ test("early executable cache restores the emitted TU, IR, and native feature gat
   const hit = await readEarlyExecutableCache(f.root, f.options);
   expect(hit?.native).toEqual(native);
   expect(hit?.executableRestored).toBe(false);
-  expect(await readFile(f.llvmPath, "utf8")).toBe("; generated llvm\n");
-  expect(await readFile(f.irPath, "utf8")).toContain("irVersion");
+  // The build compiles private copies beside the shared names and installs
+  // them there when it is done.
+  expect(hit?.llvmPath).toBe(f.llvmPath);
+  expect(hit?.irPath).toBe(f.irPath);
+  expect(hit?.llvmSourcePath).toMatch(/[/\\]\.scriptc-llvm-[^/\\]*\.ll$/);
+  expect(hit?.irSourcePath).toMatch(/[/\\]\.scriptc-ir-/);
+  expect(await readFile(hit!.llvmSourcePath!, "utf8")).toBe("; generated llvm\n");
+  expect(await readFile(hit!.irSourcePath!, "utf8")).toContain("irVersion");
+  await expect(stat(f.llvmPath)).rejects.toThrow();
   expect(await readFile(alternateC, "utf8")).toBe("/* user-owned native source */\n");
 });
 

packages/compiler/src/executable/executable-cache.ts

@@ -18,6 +18,7 @@ import { compilerReleaseVersion } from "../library/sidecar.js";
 import { nativeArtifactDependenciesStillMatch } from "../backend/native/artifact-stamps.js";
 import { type NativeArtifactDependency } from "../backend/native/contracts.js";
 import { optimizationKeyParts } from "../backend/optimization.js";
+import { privateSiblingPath } from "../backend/build-cache.js";
 import type { CompilerImplementationDependency } from "../library/compiler-self-identity.js";
 import {
   installDarwinDebugSymbols,
@@ -96,6 +97,9 @@ export interface EarlyExecutableNativeFeatures {
   tls: boolean;
   cipher: boolean;
   ecdh: boolean;
+  dh: boolean;
+  pki: boolean;
+  ed25519: boolean;
   perfLoop: boolean;
   tlsCa: boolean;
   webcrypto: boolean;
@@ -179,6 +183,15 @@ interface EarlyExecutableImplementationProof {
 export interface EarlyExecutableCacheHit {
   llvmPath: string;
   irPath?: string;
+  /** When the executable was not restored: private copies of the cached LLVM text and IR beside
+   * llvmPath and irPath, which the build compiles from and installs at those names when it is done
+   * (index.ts BuildSources). A restored executable needs no compile, and its files are installed at
+   * llvmPath and irPath. */
+  llvmSourcePath?: string;
+  irSourcePath?: string;
+  /** llvmPath (irPath) already holds the cached bytes: the build leaves it as it is. */
+  llvmPathCurrent?: true;
+  irPathCurrent?: true;
   /** True when the final executable was restored after native dependencies
    * validated. False restores only frontend artifacts and must call compileC. */
   executableRestored: boolean;
@@ -228,6 +241,9 @@ const BOOLEAN_NATIVE_KEYS = [
   "tlsCa",
   "cipher",
   "ecdh",
+  "dh",
+  "pki",
+  "ed25519",
   "webcrypto",
   "perfLoop",
 ] as const satisfies readonly (keyof EarlyExecutableNativeFeatures)[];
@@ -575,15 +591,6 @@ async function readExecutableCache(
       (await nativeArtifactDependenciesStillMatch(stamp.nativeDependencies));
     if (validateRoute !== undefined && !executableRestored) return null;
     const paths = outputPaths(options, stamp.native.backend);
-    if (!(await fileMatches(paths.llvmPath, stamp.files.translationUnit.digest))) {
-      await installBytes(translationUnit, paths.llvmPath);
-    }
-    if (
-      ir !== null &&
-      stamp.files.ir !== null &&
-      !(await fileMatches(paths.irPath, stamp.files.ir.digest))
-    )
-      await installBytes(ir, paths.irPath);
     if (executableRestored) {
       try {
         if (debugSymbols !== null) await installDarwinDebugSymbols(debugSymbols, options.outPath);
@@ -598,6 +605,32 @@ async function readExecutableCache(
         executableRestored = false;
       }
     }
+    // A build that compiles from the cached translation unit compiles its own copy: a concurrent
+    // build of another program with the same entry name may replace the shared names meanwhile.
+    let llvmSourcePath: string | undefined;
+    let irSourcePath: string | undefined;
+    let llvmPathCurrent = false;
+    let irPathCurrent = false;
+    if (executableRestored) {
+      if (!(await fileMatches(paths.llvmPath, stamp.files.translationUnit.digest)))
+        await installBytes(translationUnit, paths.llvmPath);
+      if (
+        ir !== null &&
+        stamp.files.ir !== null &&
+        !(await fileMatches(paths.irPath, stamp.files.ir.digest))
+      )
+        await installBytes(ir, paths.irPath);
+    } else {
+      // The extension keeps clang reading the copy as LLVM IR rather than as a linker input.
+      llvmSourcePath = `${privateSiblingPath(paths.llvmPath, "llvm")}.ll`;
+      await installBytes(translationUnit, llvmSourcePath);
+      llvmPathCurrent = await fileMatches(paths.llvmPath, stamp.files.translationUnit.digest);
+      if (ir !== null && stamp.files.ir !== null) {
+        irSourcePath = privateSiblingPath(paths.irPath, "ir");
+        await installBytes(ir, irSourcePath);
+        irPathCurrent = await fileMatches(paths.irPath, stamp.files.ir.digest);
+      }
+    }
     const now = new Date();
     await Promise.all(
       [
@@ -619,6 +652,10 @@ async function readExecutableCache(
         ? { performance: stamp.performance }
         : {}),
       ...(ir === null ? {} : { irPath: paths.irPath }),
+      ...(llvmSourcePath === undefined ? {} : { llvmSourcePath }),
+      ...(irSourcePath === undefined ? {} : { irSourcePath }),
+      ...(llvmPathCurrent ? { llvmPathCurrent: true as const } : {}),
+      ...(irPathCurrent ? { irPathCurrent: true as const } : {}),
     };
   } catch {
     return null;

packages/compiler/src/frontend/jsx-entities.ts

@@ -0,0 +1,258 @@
+/** The HTML entity names JSX text and attribute strings decode (HTML 4's
+ * 253 named character references, the set TypeScript's JSX emit decodes),
+ * by name. */
+export const JSX_ENTITIES: ReadonlyMap<string, number> = new Map<string, number>([
+  ["quot", 34],
+  ["amp", 38],
+  ["apos", 39],
+  ["lt", 60],
+  ["gt", 62],
+  ["nbsp", 160],
+  ["iexcl", 161],
+  ["cent", 162],
+  ["pound", 163],
+  ["curren", 164],
+  ["yen", 165],
+  ["brvbar", 166],
+  ["sect", 167],
+  ["uml", 168],
+  ["copy", 169],
+  ["ordf", 170],
+  ["laquo", 171],
+  ["not", 172],
+  ["shy", 173],
+  ["reg", 174],
+  ["macr", 175],
+  ["deg", 176],
+  ["plusmn", 177],
+  ["sup2", 178],
+  ["sup3", 179],
+  ["acute", 180],
+  ["micro", 181],
+  ["para", 182],
+  ["middot", 183],
+  ["cedil", 184],
+  ["sup1", 185],
+  ["ordm", 186],
+  ["raquo", 187],
+  ["frac14", 188],
+  ["frac12", 189],
+  ["frac34", 190],
+  ["iquest", 191],
+  ["Agrave", 192],
+  ["Aacute", 193],
+  ["Acirc", 194],
+  ["Atilde", 195],
+  ["Auml", 196],
+  ["Aring", 197],
+  ["AElig", 198],
+  ["Ccedil", 199],
+  ["Egrave", 200],
+  ["Eacute", 201],
+  ["Ecirc", 202],
+  ["Euml", 203],
+  ["Igrave", 204],
+  ["Iacute", 205],
+  ["Icirc", 206],
+  ["Iuml", 207],
+  ["ETH", 208],
+  ["Ntilde", 209],
+  ["Ograve", 210],
+  ["Oacute", 211],
+  ["Ocirc", 212],
+  ["Otilde", 213],
+  ["Ouml", 214],
+  ["times", 215],
+  ["Oslash", 216],
+  ["Ugrave", 217],
+  ["Uacute", 218],
+  ["Ucirc", 219],
+  ["Uuml", 220],
+  ["Yacute", 221],
+  ["THORN", 222],
+  ["szlig", 223],
+  ["agrave", 224],
+  ["aacute", 225],
+  ["acirc", 226],
+  ["atilde", 227],
+  ["auml", 228],
+  ["aring", 229],
+  ["aelig", 230],
+  ["ccedil", 231],
+  ["egrave", 232],
+  ["eacute", 233],
+  ["ecirc", 234],
+  ["euml", 235],
+  ["igrave", 236],
+  ["iacute", 237],
+  ["icirc", 238],
+  ["iuml", 239],
+  ["eth", 240],
+  ["ntilde", 241],
+  ["ograve", 242],
+  ["oacute", 243],
+  ["ocirc", 244],
+  ["otilde", 245],
+  ["ouml", 246],
+  ["divide", 247],
+  ["oslash", 248],
+  ["ugrave", 249],
+  ["uacute", 250],
+  ["ucirc", 251],
+  ["uuml", 252],
+  ["yacute", 253],
+  ["thorn", 254],
+  ["yuml", 255],
+  ["OElig", 338],
+  ["oelig", 339],
+  ["Scaron", 352],
+  ["scaron", 353],
+  ["Yuml", 376],
+  ["fnof", 402],
+  ["circ", 710],
+  ["tilde", 732],
+  ["Alpha", 913],
+  ["Beta", 914],
+  ["Gamma", 915],
+  ["Delta", 916],
+  ["Epsilon", 917],
+  ["Zeta", 918],
+  ["Eta", 919],
+  ["Theta", 920],
+  ["Iota", 921],
+  ["Kappa", 922],
+  ["Lambda", 923],
+  ["Mu", 924],
+  ["Nu", 925],
+  ["Xi", 926],
+  ["Omicron", 927],
+  ["Pi", 928],
+  ["Rho", 929],
+  ["Sigma", 931],
+  ["Tau", 932],
+  ["Upsilon", 933],
+  ["Phi", 934],
+  ["Chi", 935],
+  ["Psi", 936],
+  ["Omega", 937],
+  ["alpha", 945],
+  ["beta", 946],
+  ["gamma", 947],
+  ["delta", 948],
+  ["epsilon", 949],
+  ["zeta", 950],
+  ["eta", 951],
+  ["theta", 952],
+  ["iota", 953],
+  ["kappa", 954],
+  ["lambda", 955],
+  ["mu", 956],
+  ["nu", 957],
+  ["xi", 958],
+  ["omicron", 959],
+  ["pi", 960],
+  ["rho", 961],
+  ["sigmaf", 962],
+  ["sigma", 963],
+  ["tau", 964],
+  ["upsilon", 965],
+  ["phi", 966],
+  ["chi", 967],
+  ["psi", 968],
+  ["omega", 969],
+  ["thetasym", 977],
+  ["upsih", 978],
+  ["piv", 982],
+  ["ensp", 8194],
+  ["emsp", 8195],
+  ["thinsp", 8201],
+  ["zwnj", 8204],
+  ["zwj", 8205],
+  ["lrm", 8206],
+  ["rlm", 8207],
+  ["ndash", 8211],
+  ["mdash", 8212],
+  ["lsquo", 8216],
+  ["rsquo", 8217],
+  ["sbquo", 8218],
+  ["ldquo", 8220],
+  ["rdquo", 8221],
+  ["bdquo", 8222],
+  ["dagger", 8224],
+  ["Dagger", 8225],
+  ["bull", 8226],
+  ["hellip", 8230],
+  ["permil", 8240],
+  ["prime", 8242],
+  ["Prime", 8243],
+  ["lsaquo", 8249],
+  ["rsaquo", 8250],
+  ["oline", 8254],
+  ["frasl", 8260],
+  ["euro", 8364],
+  ["image", 8465],
+  ["weierp", 8472],
+  ["real", 8476],
+  ["trade", 8482],
+  ["alefsym", 8501],
+  ["larr", 8592],
+  ["uarr", 8593],
+  ["rarr", 8594],
+  ["darr", 8595],
+  ["harr", 8596],
+  ["crarr", 8629],
+  ["lArr", 8656],
+  ["uArr", 8657],
+  ["rArr", 8658],
+  ["dArr", 8659],
+  ["hArr", 8660],
+  ["forall", 8704],
+  ["part", 8706],
+  ["exist", 8707],
+  ["empty", 8709],
+  ["nabla", 8711],
+  ["isin", 8712],
+  ["notin", 8713],
+  ["ni", 8715],
+  ["prod", 8719],
+  ["sum", 8721],
+  ["minus", 8722],
+  ["lowast", 8727],
+  ["radic", 8730],
+  ["prop", 8733],
+  ["infin", 8734],
+  ["ang", 8736],
+  ["and", 8743],
+  ["or", 8744],
+  ["cap", 8745],
+  ["cup", 8746],
+  ["int", 8747],
+  ["there4", 8756],
+  ["sim", 8764],
+  ["cong", 8773],
+  ["asymp", 8776],
+  ["ne", 8800],
+  ["equiv", 8801],
+  ["le", 8804],
+  ["ge", 8805],
+  ["sub", 8834],
+  ["sup", 8835],
+  ["nsub", 8836],
+  ["sube", 8838],
+  ["supe", 8839],
+  ["oplus", 8853],
+  ["otimes", 8855],
+  ["perp", 8869],
+  ["sdot", 8901],
+  ["lceil", 8968],
+  ["rceil", 8969],
+  ["lfloor", 8970],
+  ["rfloor", 8971],
+  ["lang", 9001],
+  ["rang", 9002],
+  ["loz", 9674],
+  ["spades", 9824],
+  ["clubs", 9827],
+  ["hearts", 9829],
+  ["diams", 9830],
+]);

packages/compiler/src/frontend/jsx-source.test.ts

@@ -0,0 +1,244 @@
+import ts5 from "typescript5";
+import { afterAll, describe, expect, it } from "vitest";
+import { jsxEmitPlan, decodeEntities, jsxPragmas, jsxTextValue, lowerJsx } from "./jsx-source.js";
+import { closeSourceParser, parseSourceFile } from "./ts7/source-parser-node.js";
+
+afterAll(() => closeSourceParser());
+
+/** Evaluates a program whose last statement is `result = ...`, with `h` and
+ * `Fragment` recording the calls the JSX makes. */
+function evaluate(code: string): unknown {
+  const run = new Function(
+    "h",
+    "Fragment",
+    "React",
+    `"use strict"; let result; ${code}; return result;`,
+  ) as (...args: unknown[]) => unknown;
+  const h = (tag: unknown, props: unknown, ...children: unknown[]): unknown => ({
+    tag: typeof tag === "function" ? `fn:${tag.name}` : tag === Fragment ? "#fragment" : tag,
+    props,
+    children,
+  });
+  const Fragment = { fragment: true };
+  return run(h, Fragment, { createElement: h, Fragment });
+}
+
+/** TypeScript's own classic-runtime emit of the snippet. */
+function typescriptEmit(source: string, factory?: string): string {
+  return ts5.transpileModule(source, {
+    fileName: "case.tsx",
+    compilerOptions: {
+      target: ts5.ScriptTarget.ES2022,
+      module: ts5.ModuleKind.ESNext,
+      jsx: ts5.JsxEmit.React,
+      ...(factory === undefined ? {} : { jsxFactory: factory, jsxFragmentFactory: "Fragment" }),
+    },
+  }).outputText;
+}
+
+function rewrite(source: string, factory?: string): string {
+  const sf = parseSourceFile("/case.tsx", source, "tsx");
+  const plan = jsxEmitPlan(
+    {
+      jsx: "react",
+      ...(factory === undefined ? {} : { jsxFactory: factory, jsxFragmentFactory: "Fragment" }),
+    },
+    jsxPragmas(source),
+  );
+  return lowerJsx(sf, plan).text;
+}
+
+const cases: Record<string, string> = {
+  "attributes and text": `const name = "w"; const p = { id: 1 };
+result = <div class="hello" data-x='1' disabled {...p} title={name}>Hello {name}  &amp; &#x41; &copy;
+   second   line
+  {/* comment */}
+  {name}{" "}<b>bold</b>
+</div>;`,
+  fragments: `function Foo() {} Foo.Bar = function Bar() {};
+result = <><i /><Foo.Bar x={1} /></>;`,
+  namespaced: `result = <ns:tag a:b="c" />;`,
+  "keys and nested maps": `const p = { id: 1 };
+result = <div key="k" {...p}>{[1, 2].map((n) => <span key={n}>{n}</span>)}</div>;`,
+  "white space only": `result = [<div>   </div>, <div>
+</div>, <div>   a   {"b"}   c   </div>];`,
+  "spreads": `const p = { id: 1 }; const kids = [1, 2];
+result = [<div {...p} />, <div {...p} {...p} />, <div>{...kids}</div>, <div {...{ a: 1, b: 2 }} c={3} />, <div {...{ __proto__: null, a: 1 }} />];`,
+  "attribute strings": `result = <div title="a &amp; b &unknown; &#65; &#x1F600;" alt="line
+two" empty="" />;`,
+  "attribute values": `result = <div a={} b=<i /> c={<b>{1}</b>} d={[<p />]} />;`,
+  "member and this tags": `class X { Tag = function Tag() {}; render() { return <this.Tag x="1" />; } }
+result = new X().render();`,
+  "dashed and capitalized names": `function Comp() {}
+result = [<a-b />, <Comp $x="1" _y="2" z-w="3" />];`,
+  "nested JSX in expressions": `const items = ["a", "b"];
+result = <ul>
+  {items.length > 1 ? <li>{items[0]}</li> : null}
+  {items.map((item) =>
+    <li
+      key={item}
+      title={item}
+    >
+      {item}
+    </li>)}
+</ul>;`,
+};
+
+describe("lowerJsx", () => {
+  for (const [name, source] of Object.entries(cases)) {
+    it(`matches TypeScript's emit: ${name}`, () => {
+      const lowered = rewrite(source);
+      expect(evaluate(lowered)).toEqual(evaluate(typescriptEmit(source)));
+      expect(lowered.split("\n").length).toBe(source.split("\n").length);
+    });
+  }
+
+  it("uses jsxFactory and the pragmas", () => {
+    const source = `result = <><x a="1" /></>;`;
+    expect(evaluate(rewrite(source, "h"))).toEqual(evaluate(typescriptEmit(source, "h")));
+    const pragma = `/** @jsx h */\n/** @jsxFrag Fragment */\nresult = <><x /></>;`;
+    expect(rewrite(pragma)).toContain(`h(Fragment, null`);
+    expect(evaluate(rewrite(pragma))).toEqual(evaluate(typescriptEmit(pragma)));
+  });
+
+  it("keeps every byte outside JSX", () => {
+    const source = `const a = 1; // <not jsx>\nconst b = "<div>";\nresult = [a, b, <i />];\n`;
+    const lowered = rewrite(source);
+    expect(
+      lowered.startsWith(`const a = 1; // <not jsx>\nconst b = "<div>";\nresult = [a, b, `),
+    ).toBe(true);
+  });
+
+  it("maps rewritten positions back to the source", () => {
+    const source = `const x = 1;\nresult = <div a={x}>{x}</div>;\nconst y = 2;\n`;
+    const sf = parseSourceFile("/case.tsx", source, "tsx");
+    const lowered = lowerJsx(sf, { runtime: "classic", factory: "h", fragment: "Fragment" });
+    const after = lowered.text.indexOf("const y");
+    expect(lowered.originalPosition(after)).toBe(source.indexOf("const y"));
+    const copied = lowered.text.indexOf("{ a: x }") + "{ a: ".length;
+    expect(lowered.originalPosition(copied)).toBe(source.indexOf("{x}>") + 1);
+    expect(lowered.originalPosition(lowered.text.indexOf("h("))).toBe(source.indexOf("<div"));
+  });
+});
+
+/** Evaluates automatic-runtime output: each runtime import becomes a
+ * binding of a recording function (`jsx`, `jsxs`, `jsxDEV`, `createElement`)
+ * or of the fragment marker, under the local name the output chose. */
+function evaluateAutomatic(code: string): unknown {
+  const body = code
+    .replace(/import \{([^}]*)\} from "[^"]*";/g, (_match, list: string) =>
+      list
+        .split(",")
+        .map((item) => {
+          const [name, local] = item.trim().split(/\s+as\s+/);
+          return `const ${local} = runtime.${name};`;
+        })
+        .join(" "),
+    )
+    .replace(/(^|\s)export /gm, "$1");
+  const record =
+    (kind: string) =>
+    (...args: unknown[]): unknown => ({ kind, args: args.map(named) });
+  const runtime = {
+    jsx: record("jsx"),
+    jsxs: record("jsxs"),
+    jsxDEV: record("jsxDEV"),
+    createElement: record("createElement"),
+    Fragment: "#fragment",
+  };
+  const run = new Function("runtime", `"use strict"; let result; ${body}; return result;`) as (
+    runtime: unknown,
+  ) => unknown;
+  return run(runtime);
+}
+
+/** Functions compare by name: each evaluation declares its own. */
+function named(value: unknown): unknown {
+  if (typeof value === "function") return `fn:${value.name}`;
+  if (Array.isArray(value)) return value.map(named);
+  if (value !== null && typeof value === "object")
+    return Object.fromEntries(Object.entries(value).map(([key, item]) => [key, named(item)]));
+  return value;
+}
+
+function typescriptAutomatic(source: string, development: boolean): string {
+  return ts5.transpileModule(source, {
+    fileName: "/case.tsx",
+    compilerOptions: {
+      target: ts5.ScriptTarget.ES2022,
+      module: ts5.ModuleKind.ESNext,
+      jsx: development ? ts5.JsxEmit.ReactJSXDev : ts5.JsxEmit.ReactJSX,
+    },
+  }).outputText;
+}
+
+function rewriteAutomatic(source: string, development: boolean): string {
+  const sf = parseSourceFile("/case.tsx", source, "tsx");
+  const plan = jsxEmitPlan({ jsx: development ? "react-jsxdev" : "react-jsx" }, jsxPragmas(source));
+  return lowerJsx(sf, plan).text;
+}
+
+const automaticCases: Record<string, string> = {
+  ...cases,
+  "keys": `const p = { id: 1 };
+result = [<li key="a">x</li>, <li {...p} key="b" />, <li key="c" {...p} />, <li {...{ a: 1 }} key="d" />, <li {...{ ...p }} key="e" />];`,
+  "children shapes": `const kids = [1, 2];
+result = [<p />, <p>{}</p>, <p>
+</p>, <p>one</p>, <p>{1}{2}</p>, <p>{...kids}</p>, <p>  </p>, <><b /></>, <></>];`,
+  "names in use": `const _jsx = "taken"; const _jsxs = 1;
+result = [<p>{_jsx}</p>, <p>{_jsxs}{_jsx}</p>];`,
+};
+
+describe("lowerJsx with the automatic runtime", () => {
+  for (const [name, source] of Object.entries(automaticCases)) {
+    for (const development of [false, true]) {
+      it(`matches TypeScript's ${development ? "react-jsxdev" : "react-jsx"} emit: ${name}`, () => {
+        const lowered = rewriteAutomatic(`export {};\n${source}`, development);
+        const expected = typescriptAutomatic(`export {};\n${source}`, development);
+        expect(evaluateAutomatic(lowered)).toEqual(evaluateAutomatic(expected));
+        expect(lowered.split("\n").length).toBe(source.split("\n").length + 1);
+      });
+    }
+  }
+
+  it("imports the runtime functions on the first statement's line", () => {
+    const lowered = rewriteAutomatic(
+      `"use strict";\nexport const a = <><b key="k" /></>;\n`,
+      false,
+    );
+    expect(lowered).toBe(
+      `"use strict";import { jsx as _jsx, Fragment as _Fragment } from "react/jsx-runtime"; \nexport const a = _jsx(_Fragment, { children: _jsx("b", {}, "k") });\n`,
+    );
+  });
+
+  it("reads @jsxImportSource and @jsxRuntime", () => {
+    const pragma = `/** @jsxImportSource preact */\nexport const a = <b />;\n`;
+    expect(rewriteAutomatic(pragma, false)).toContain(`from "preact/jsx-runtime"`);
+    const classic = `/** @jsxRuntime classic */\n/** @jsx h */\nexport const a = <b />;\n`;
+    expect(rewriteAutomatic(classic, false)).toContain(`h("b", null)`);
+  });
+});
+
+describe("JSX text", () => {
+  it("trims lines as TypeScript does", () => {
+    expect(jsxTextValue("  a  \n   b  \n  ")).toBe("  a b");
+    expect(jsxTextValue("\n   \n")).toBeUndefined();
+    expect(jsxTextValue("   ")).toBe("   ");
+  });
+
+  it("decodes entities", () => {
+    expect(decodeEntities("&lt;&gt;&amp;&nbsp;&#65;&#x42;&bogus;&#x110000;")).toBe(
+      "<>& AB&bogus;&#x110000;",
+    );
+  });
+});
+
+describe("jsxPragmas", () => {
+  it("reads leading multi-line comments, first @jsx and last @jsxImportSource", () => {
+    expect(
+      jsxPragmas(
+        "#!/usr/bin/env node\n/** @jsx h\n * @jsx g */\n// @jsxFrag F\n/* @jsxImportSource a */ /* @jsxImportSource b */\nconst x = 1; /** @jsx late */",
+      ),
+    ).toEqual({ jsx: "h", jsxImportSource: "b" });
+  });
+});

packages/compiler/src/frontend/jsx-source.ts

@@ -0,0 +1,856 @@
+/* JSX lowering at the source level, before IR lowering.
+ *
+ * A program that contains JSX is checked as written: the checker types JSX
+ * with the project's jsx settings and reports the errors tsc reports. Each
+ * file that contains JSX is then rewritten with every JSX expression
+ * replaced by the calls TypeScript emits for it, and the rewritten program is
+ * what the lowering compiles, through the same import, call and object
+ * literal lowering as ordinary code.
+ *
+ * The rewrite copies every byte outside JSX expressions, and copies the
+ * expressions inside them (attribute values, children, spreads) with their
+ * own JSX rewritten. It keeps every line break of a JSX expression, between
+ * the arguments it emits, so a position keeps its line in the rewritten
+ * text. */
+
+import * as ts from "./ts7/adapter.js";
+import { jsxOptionName } from "./ts7/enums.js";
+import { JSX_ENTITIES } from "./jsx-entities.js";
+
+/** The project's jsx compiler options, as the tsconfig spells them. */
+export interface JsxOptions {
+  jsx?: string | number | undefined;
+  jsxFactory?: string | undefined;
+  jsxFragmentFactory?: string | undefined;
+  jsxImportSource?: string | undefined;
+  reactNamespace?: string | undefined;
+}
+
+/** The tsconfig name of a `jsx` option value (TS7 options carry JsxEmit
+ * numbers, parsed tsconfigs may carry the name). */
+export function jsxEmitName(value: string | number | undefined): string | undefined {
+  if (typeof value === "number") return jsxOptionName(value);
+  return value?.toLowerCase();
+}
+
+/** The `@jsx`, `@jsxFrag`, `@jsxImportSource` and `@jsxRuntime` pragmas of
+ * a file's leading comments, as TypeScript reads them: multi-line comments
+ * only, the first `@jsx` and `@jsxFrag` and the last `@jsxImportSource` and
+ * `@jsxRuntime`. */
+export interface JsxPragmas {
+  jsx?: string;
+  jsxFrag?: string;
+  jsxImportSource?: string;
+  jsxRuntime?: string;
+}
+
+export function jsxPragmas(text: string): JsxPragmas {
+  const pragmas: JsxPragmas = {};
+  for (const comment of leadingMultiLineComments(text)) {
+    const pattern = /@(\S+)(\s+(?:\S.*)?)?$/gm;
+    for (let match = pattern.exec(comment); match !== null; match = pattern.exec(comment)) {
+      const argument = match[2]?.trim().split(/\s+/)[0];
+      if (!argument) continue;
+      switch (match[1]!.toLowerCase()) {
+        case "jsx":
+          pragmas.jsx ??= argument;
+          break;
+        case "jsxfrag":
+          pragmas.jsxFrag ??= argument;
+          break;
+        case "jsximportsource":
+          pragmas.jsxImportSource = argument;
+          break;
+        case "jsxruntime":
+          pragmas.jsxRuntime = argument;
+          break;
+      }
+    }
+  }
+  return pragmas;
+}
+
+/** The `/* ... *\/` comments before a file's first token (after a shebang). */
+function leadingMultiLineComments(text: string): string[] {
+  const comments: string[] = [];
+  let i = text.startsWith("#!") ? text.indexOf("\n") : 0;
+  if (i < 0) return comments;
+  while (i < text.length) {
+    const ch = text.charCodeAt(i);
+    if (isLineBreak(ch) || isWhiteSpaceSingleLine(ch)) {
+      i++;
+    } else if (text.startsWith("//", i)) {
+      while (i < text.length && !isLineBreak(text.charCodeAt(i))) i++;
+    } else if (text.startsWith("/*", i)) {
+      const end = text.indexOf("*/", i + 2);
+      const close = end < 0 ? text.length : end + 2;
+      comments.push(text.slice(i, close));
+      i = close;
+    } else {
+      break;
+    }
+  }
+  return comments;
+}
+
+function isLineBreak(ch: number): boolean {
+  return ch === 10 || ch === 13 || ch === 0x2028 || ch === 0x2029;
+}
+
+function isWhiteSpaceSingleLine(ch: number): boolean {
+  return (
+    ch === 32 ||
+    ch === 9 ||
+    ch === 11 ||
+    ch === 12 ||
+    ch === 160 ||
+    ch === 133 ||
+    ch === 5760 ||
+    (ch >= 8192 && ch <= 8203) ||
+    ch === 8239 ||
+    ch === 8287 ||
+    ch === 12288 ||
+    ch === 65279
+  );
+}
+
+/** How a file's JSX is emitted, after its pragmas. */
+export type JsxEmitPlan =
+  | {
+      runtime: "classic";
+      /** The factory call (`h`, `React.createElement`). */
+      factory: string;
+      /** The fragment tag (`Fragment`, `React.Fragment`). */
+      fragment: string;
+    }
+  | {
+      runtime: "automatic";
+      /** The module `jsx-runtime` (or `jsx-dev-runtime`) is under, and that
+       * a `createElement` fallback imports from (`react`). */
+      importSource: string;
+      /** jsx: react-jsxdev: `jsxDEV` calls with source locations. */
+      development: boolean;
+    };
+
+/** The plan of a file: the automatic runtime with jsx: react-jsx or
+ * react-jsxdev, an import source or an `@jsxRuntime automatic` pragma (an
+ * `@jsxRuntime classic` pragma overrides all of them), the classic runtime
+ * otherwise. */
+export function jsxEmitPlan(options: JsxOptions, pragmas: JsxPragmas): JsxEmitPlan {
+  const mode = jsxEmitName(options.jsx);
+  const automatic =
+    pragmas.jsxRuntime !== "classic" &&
+    (mode === "react-jsx" ||
+      mode === "react-jsxdev" ||
+      options.jsxImportSource !== undefined ||
+      pragmas.jsxImportSource !== undefined ||
+      pragmas.jsxRuntime === "automatic");
+  if (automatic) {
+    return {
+      runtime: "automatic",
+      importSource: pragmas.jsxImportSource ?? options.jsxImportSource ?? "react",
+      development: mode === "react-jsxdev",
+    };
+  }
+  const namespace = options.reactNamespace ?? "React";
+  return {
+    runtime: "classic",
+    factory: pragmas.jsx ?? options.jsxFactory ?? `${namespace}.createElement`,
+    fragment: pragmas.jsxFrag ?? options.jsxFragmentFactory ?? `${namespace}.Fragment`,
+  };
+}
+
+/** True when the file contains a JSX expression. */
+export function containsJsx(sf: ts.SourceFile): boolean {
+  let found = false;
+  const visit = (node: ts.Node): void => {
+    if (found) return;
+    if (isJsxExpressionRoot(node)) {
+      found = true;
+      return;
+    }
+    ts.forEachChild(node, visit);
+  };
+  visit(sf);
+  return found;
+}
+
+/** The first JSX expression of the file (for diagnostics), or null. */
+export function firstJsx(sf: ts.SourceFile): ts.Node | null {
+  let found: ts.Node | null = null;
+  const visit = (node: ts.Node): void => {
+    if (found !== null) return;
+    if (isJsxExpressionRoot(node)) {
+      found = node;
+      return;
+    }
+    ts.forEachChild(node, visit);
+  };
+  visit(sf);
+  return found;
+}
+
+type JsxRoot = ts.JsxElement | ts.JsxSelfClosingElement | ts.JsxFragment;
+
+function isJsxExpressionRoot(node: ts.Node): node is JsxRoot {
+  return ts.isJsxElement(node) || ts.isJsxSelfClosingElement(node) || ts.isJsxFragment(node);
+}
+
+/** A file's text with its JSX lowered, and the way back from a position of
+ * that text to the source position it stands for. */
+export interface LoweredJsx {
+  text: string;
+  /** A rewritten-text offset as an offset of the original text: copied text
+   * keeps its offset; emitted call text maps to the JSX it stands for. */
+  originalPosition(pos: number): number;
+  /** An original-text offset in the rewritten text: copied text keeps its
+   * offset; a position inside replaced JSX maps to the call text emitted
+   * for the JSX at or before it (its end, for the `end` of a span). */
+  rewrittenPosition(pos: number, end: boolean): number;
+}
+
+/** The file's text with its JSX replaced by the calls TypeScript emits for
+ * the plan, and for the automatic runtime the imports of the runtime
+ * functions those calls use. */
+export function lowerJsx(sf: ts.SourceFile, plan: JsxEmitPlan): LoweredJsx {
+  return new JsxRewriter(sf, plan).file();
+}
+
+/** A run of rewritten text: `copied` text starts at `original`; emitted
+ * text stands for the source position `original`. */
+interface Segment {
+  rewritten: number;
+  original: number;
+  /** The copied length, 0 for emitted text. */
+  copied: number;
+}
+
+class JsxRewriter {
+  private readonly text: string;
+  /** Output pieces; `cursor` is the source position whose line breaks the
+   * output has reached. */
+  private readonly pieces: string[] = [];
+  private readonly segments: Segment[] = [];
+  private length = 0;
+  private cursor = 0;
+
+  constructor(
+    private readonly sf: ts.SourceFile,
+    private readonly plan: JsxEmitPlan,
+  ) {
+    this.text = sf.text;
+  }
+
+  file(): LoweredJsx {
+    const insertAt = this.plan.runtime === "automatic" ? this.prologueEnd() : -1;
+    this.copy(0, this.text.length);
+    if (insertAt >= 0) this.insertImports(insertAt);
+    const segments = this.segments;
+    const total = this.length;
+    return {
+      text: this.pieces.join(""),
+      originalPosition: (pos: number): number => {
+        let low = 0;
+        let high = segments.length - 1;
+        while (low < high) {
+          const mid = (low + high + 1) >> 1;
+          if (segments[mid]!.rewritten <= pos) low = mid;
+          else high = mid - 1;
+        }
+        const segment = segments[low];
+        if (segment === undefined) return pos;
+        return segment.copied > 0
+          ? segment.original + Math.min(pos - segment.rewritten, segment.copied)
+          : segment.original;
+      },
+      rewrittenPosition: (pos: number, end: boolean): number => {
+        // Segments are in source order: the last one starting at or before
+        // `pos` holds it, or is the emitted text for the JSX holding it.
+        let low = 0;
+        let high = segments.length - 1;
+        while (low < high) {
+          const mid = (low + high + 1) >> 1;
+          if (segments[mid]!.original <= pos) low = mid;
+          else high = mid - 1;
+        }
+        const segment = segments[low];
+        if (segment === undefined) return pos;
+        if (segment.copied > 0)
+          return segment.rewritten + Math.min(pos - segment.original, segment.copied);
+        return end ? (segments[low + 1]?.rewritten ?? total) : segment.rewritten;
+      },
+    };
+  }
+
+  /** Local names of the automatic runtime's functions, by module and
+   * export, in the order of first use (TypeScript's implicit imports). */
+  private readonly imports = new Map<string, Map<string, string>>();
+  private names: Set<string> | null = null;
+  private fileNameLocal: string | null = null;
+
+  /** The local name bound to `name` of `module`: `_name`, or `_name_1`,
+   * `_name_2`, ... past an identifier the file already uses. */
+  private importName(name: string, module: string): string {
+    let names = this.imports.get(module);
+    if (names === undefined) {
+      names = new Map();
+      this.imports.set(module, names);
+    }
+    let local = names.get(name);
+    if (local === undefined) {
+      local = this.uniqueName(`_${name}`);
+      names.set(name, local);
+    }
+    return local;
+  }
+
+  private uniqueName(base: string): string {
+    if (this.names === null) {
+      const names = new Set<string>();
+      const visit = (node: ts.Node): void => {
+        if (ts.isIdentifier(node)) names.add(node.text);
+        ts.forEachChild(node, visit);
+      };
+      visit(this.sf);
+      this.names = names;
+    }
+    let name = base;
+    for (let i = 1; this.names.has(name); i++) name = `${base}_${i}`;
+    this.names.add(name);
+    return name;
+  }
+
+  /** Where the runtime imports go: after the leading "use strict"-style
+   * directives, else before the first statement, so the inserted text
+   * shares that statement's line. */
+  private prologueEnd(): number {
+    const statements = this.sf.statements.nodes;
+    let end = -1;
+    for (const statement of statements) {
+      if (!ts.isExpressionStatement(statement) || !ts.isStringLiteral(statement.expression)) break;
+      end = statement.end;
+    }
+    if (end >= 0) return end;
+    const first = statements[0];
+    return first === undefined ? this.text.length : first.getStart(this.sf);
+  }
+
+  /** Inserts the imports (or, in a CommonJS file, the requires) of the
+   * runtime functions the file's JSX used, and react-jsxdev's file name
+   * constant, at `at`: imports in the reverse order of their modules' first
+   * use, as TypeScript inserts each after the prologue. */
+  private insertImports(at: number): void {
+    if (this.imports.size === 0 && this.fileNameLocal === null) return;
+    const esm = ts.isExternalModule(this.sf);
+    const parts: string[] = [];
+    for (const [module, names] of [...this.imports].reverse()) {
+      const specifier = JSON.stringify(module);
+      if (esm) {
+        const list = [...names].map(([name, local]) => `${name} as ${local}`).join(", ");
+        parts.push(`import { ${list} } from ${specifier};`);
+      } else if (/\.[cm]?jsx?$/.test(this.sf.fileName)) {
+        const list = [...names].map(([name, local]) => `${name}: ${local}`).join(", ");
+        parts.push(`const { ${list} } = require(${specifier});`);
+      }
+    }
+    if (this.fileNameLocal !== null)
+      parts.push(`const ${this.fileNameLocal} = ${JSON.stringify(this.sf.fileName)};`);
+    if (parts.length === 0) return;
+    const text = `${parts.join(" ")} `;
+    let index = 0;
+    let rewritten = 0;
+    for (; index < this.segments.length; index++) {
+      const segment = this.segments[index]!;
+      if (segment.copied > 0 && segment.original <= at && at <= segment.original + segment.copied) {
+        rewritten = segment.rewritten + (at - segment.original);
+        break;
+      }
+    }
+    // Split the copied segment holding `at` and shift what follows.
+    const holder = this.segments[index];
+    const joined = this.pieces.join("");
+    this.pieces.length = 0;
+    this.pieces.push(joined.slice(0, rewritten), text, joined.slice(rewritten));
+    const following: Segment[] = [{ rewritten, original: at, copied: 0 }];
+    if (holder !== undefined && holder.copied > 0) {
+      const head = at - holder.original;
+      const tail = holder.copied - head;
+      holder.copied = head;
+      if (tail > 0)
+        following.push({ rewritten: rewritten + text.length, original: at, copied: tail });
+    }
+    for (let i = index + 1; i < this.segments.length; i++)
+      this.segments[i]!.rewritten += text.length;
+    this.segments.splice(index + 1, 0, ...following);
+    if (holder !== undefined && holder.copied === 0) this.segments.splice(index, 1);
+    this.length += text.length;
+  }
+
+  /** Emits source text [start, end) unchanged. */
+  private copied(start: number, end: number): void {
+    if (end <= start) return;
+    this.segments.push({ rewritten: this.length, original: start, copied: end - start });
+    this.pieces.push(this.text.slice(start, end));
+    this.length += end - start;
+  }
+
+  /** Emits call text standing for the source position the cursor reached. */
+  private emit(...texts: string[]): void {
+    for (const text of texts) {
+      if (text.length === 0) continue;
+      const last = this.segments[this.segments.length - 1];
+      if (last === undefined || last.copied > 0 || last.original !== this.cursor)
+        this.segments.push({ rewritten: this.length, original: this.cursor, copied: 0 });
+      this.pieces.push(text);
+      this.length += text.length;
+    }
+  }
+
+  /** Copies the source range [start, end), with its JSX expressions
+   * replaced. */
+  private copy(start: number, end: number): void {
+    let at = start;
+    const visit = (node: ts.Node): void => {
+      if (node.end <= at || (node !== this.sf && node.getStart(this.sf) >= end)) return;
+      if (isJsxExpressionRoot(node)) {
+        const nodeStart = node.getStart(this.sf);
+        this.copied(at, nodeStart);
+        if (nodeStart > this.cursor) this.cursor = nodeStart;
+        this.element(node);
+        this.sync(node.end);
+        at = node.end;
+        return;
+      }
+      ts.forEachChild(node, visit);
+    };
+    // The cursor never moves back: a range copied after source that follows
+    // it (jsx()'s key argument, after the children) emits no line break
+    // twice.
+    if (start > this.cursor) this.cursor = start;
+    visit(this.enclosing(start, end));
+    this.copied(at, end);
+    if (end > this.cursor) this.cursor = end;
+  }
+
+  /** The smallest node around [start, end) whose children cover it. */
+  private enclosing(start: number, end: number): ts.Node {
+    let node: ts.Node = this.sf;
+    for (;;) {
+      let next: ts.Node | undefined;
+      ts.forEachChild(node, (child) => {
+        if (next === undefined && child.pos <= start && child.end >= end) next = child;
+      });
+      if (next === undefined || next === node) return node;
+      node = next;
+    }
+  }
+
+  /** Emits the line breaks of the source between the cursor and `pos`. */
+  private sync(pos: number): void {
+    for (let i = this.cursor; i < pos; i++) {
+      const ch = this.text.charCodeAt(i);
+      if (ch === 13 && this.text.charCodeAt(i + 1) === 10) {
+        this.cursor = i;
+        this.emit("\r\n");
+        i++;
+      } else if (isLineBreak(ch)) {
+        this.cursor = i;
+        this.emit(this.text[i]!);
+      }
+    }
+    if (pos > this.cursor) this.cursor = pos;
+  }
+
+  /** Copies an expression in a JSX expression's place. */
+  private expression(node: ts.Node): void {
+    const start = node.getStart(this.sf);
+    this.sync(start);
+    this.copy(start, node.end);
+  }
+
+  private element(node: JsxRoot): void {
+    const plan = this.plan;
+    if (plan.runtime === "classic") {
+      this.createElement(node, plan.factory, plan.fragment);
+      return;
+    }
+    const opening = ts.isJsxFragment(node)
+      ? null
+      : ts.isJsxElement(node)
+        ? node.openingElement
+        : node;
+    if (opening !== null && hasKeyAfterPropsSpread(opening.attributes)) {
+      // A key after a spread of props is not jsx()'s key argument: the
+      // element is the import source's createElement call.
+      this.createElement(node, this.importName("createElement", plan.importSource), "");
+      return;
+    }
+    this.automaticElement(node, opening, plan.importSource, plan.development);
+  }
+
+  /** The classic-runtime call: `factory(tag, props or null, ...children)`. */
+  private createElement(node: JsxRoot, factory: string, fragment: string): void {
+    const children = ts.isJsxSelfClosingElement(node) ? [] : node.children.nodes;
+    if (ts.isJsxFragment(node)) {
+      this.emit(`${factory}(${fragment}, null`);
+    } else {
+      const opening = ts.isJsxElement(node) ? node.openingElement : node;
+      this.emit(`${factory}(`);
+      this.tagName(opening.tagName);
+      this.emit(", ");
+      this.attributes(opening.attributes.properties.nodes, null);
+    }
+    for (const child of children) {
+      if (ts.isJsxText(child)) {
+        const value = jsxTextValue(child.text);
+        if (value === undefined) continue;
+        this.emit(", ");
+        this.sync(child.getStart(this.sf));
+        this.emit(JSON.stringify(value));
+      } else if (ts.isJsxExpression(child)) {
+        if (child.expression === undefined) continue;
+        this.emit(", ");
+        if (child.dotDotDotToken !== undefined) this.emit("...");
+        this.expression(child.expression);
+      } else if (isJsxExpressionRoot(child)) {
+        this.emit(", ");
+        this.sync(child.getStart(this.sf));
+        this.element(child);
+      }
+      this.sync(child.end);
+    }
+    this.sync(node.end);
+    this.emit(")");
+  }
+
+  /** The automatic-runtime call: `jsx(tag, props[, key])` with the
+   * children in props, `jsxs` for more than one child or a spread child, and
+   * react-jsxdev's `jsxDEV(tag, props, key, isStatic, source, self)`. */
+  private automaticElement(
+    node: JsxRoot,
+    opening: ts.JsxOpeningElement | ts.JsxSelfClosingElement | null,
+    importSource: string,
+    development: boolean,
+  ): void {
+    const children: readonly ts.JsxChild[] = ts.isJsxSelfClosingElement(node)
+      ? []
+      : node.children.nodes;
+    const semantic = children.filter(isSemanticJsxChild);
+    const first = semantic[0];
+    const isStatic =
+      semantic.length > 1 ||
+      (first !== undefined && ts.isJsxExpression(first) && first.dotDotDotToken !== undefined);
+    const module = `${importSource}/${development ? "jsx-dev-runtime" : "jsx-runtime"}`;
+    this.emit(`${this.importName(development ? "jsxDEV" : isStatic ? "jsxs" : "jsx", module)}(`);
+    // TypeScript's children prop: the one semantic child itself, else an
+    // array of every child that emits a value.
+    const single = semantic.length === 1 && !isStatic ? first! : null;
+    const listed = single === null ? children.filter((child) => jsxChildEmits(child)) : [];
+    const childrenProp =
+      children.length > 0 && (single !== null ? jsxChildEmits(single) : listed.length > 0)
+        ? (): void => {
+            this.emit("children: ");
+            if (single !== null) {
+              this.child(single);
+            } else {
+              this.emit("[");
+              listed.forEach((child, index) => {
+                if (index > 0) this.emit(", ");
+                this.child(child);
+                this.sync(child.end);
+              });
+              this.emit("]");
+            }
+          }
+        : null;
+    let key: ts.JsxAttribute | undefined;
+    if (opening === null) {
+      this.emit(this.importName("Fragment", module), ", ");
+      if (childrenProp === null) this.emit("{}");
+      else this.attributes([], childrenProp);
+    } else {
+      this.tagName(opening.tagName);
+      this.emit(", ");
+      const properties = opening.attributes.properties.nodes;
+      key = properties.find(
+        (property): property is ts.JsxAttribute =>
+          ts.isJsxAttribute(property) &&
+          ts.isIdentifier(property.name) &&
+          property.name.text === "key",
+      );
+      const attributes = properties.filter((property) => property !== key);
+      if (attributes.length === 0 && childrenProp === null) this.emit("{}");
+      else this.attributes(attributes, childrenProp);
+    }
+    if (key !== undefined) {
+      this.emit(", ");
+      this.attributeValue(key.initializer);
+    }
+    if (development) {
+      if (key === undefined) this.emit(", void 0");
+      const { line, column } = lineAndColumn(this.text, node.pos);
+      this.fileNameLocal ??= this.uniqueName("_jsxFileName");
+      this.emit(
+        `, ${isStatic}, { fileName: ${this.fileNameLocal}, lineNumber: ${line}, columnNumber: ${column} }, `,
+        jsxSelf(node),
+      );
+    }
+    this.sync(node.end);
+    this.emit(")");
+  }
+
+  /** A child's value in the children prop (it emits one: jsxChildEmits). */
+  private child(child: ts.JsxChild): void {
+    if (ts.isJsxText(child)) {
+      this.sync(child.getStart(this.sf));
+      this.emit(JSON.stringify(jsxTextValue(child.text)!));
+    } else if (ts.isJsxExpression(child)) {
+      if (child.dotDotDotToken !== undefined) this.emit("...");
+      this.expression(child.expression!);
+    } else {
+      this.sync(child.getStart(this.sf));
+      this.element(child as JsxRoot);
+    }
+  }
+
+  private tagName(tag: ts.JsxTagNameExpression): void {
+    this.sync(tag.getStart(this.sf));
+    if (ts.isIdentifier(tag) && isIntrinsicJsxName(tag.text)) {
+      this.emit(JSON.stringify(tag.text));
+    } else if (ts.isJsxNamespacedName(tag)) {
+      this.emit(JSON.stringify(`${tag.namespace.text}:${tag.name.text}`));
+    } else {
+      this.emit(this.text.slice(tag.getStart(this.sf), tag.end));
+    }
+    this.cursor = tag.end;
+  }
+
+  /** The props object of `properties`, then `children` (the automatic
+   * runtime's children prop), or `null` for no properties and no children
+   * prop. */
+  private attributes(
+    properties: readonly ts.JsxAttributeLike[],
+    children: (() => void) | null,
+  ): void {
+    if (properties.length === 0 && children === null) {
+      this.emit("null");
+      return;
+    }
+    if (properties.length === 0) {
+      this.emit("{ ");
+      children!();
+      this.emit(" }");
+      return;
+    }
+    this.emit("{ ");
+    let first = true;
+    const separate = (): void => {
+      if (!first) this.emit(", ");
+      first = false;
+    };
+    for (const attribute of properties) {
+      if (ts.isJsxSpreadAttribute(attribute)) {
+        const value = attribute.expression;
+        if (ts.isObjectLiteralExpression(value) && !hasProtoProperty(value)) {
+          // TypeScript inlines the properties of a spread object literal.
+          for (const property of value.properties.nodes) {
+            separate();
+            this.expression(property);
+          }
+        } else {
+          separate();
+          this.emit("...");
+          this.expression(value);
+        }
+      } else {
+        separate();
+        this.sync(attribute.getStart(this.sf));
+        this.emit(attributeName(attribute.name), ": ");
+        this.attributeValue(attribute.initializer);
+      }
+      this.sync(attribute.end);
+    }
+    if (children !== null) {
+      this.emit(", ");
+      children();
+    }
+    this.emit(" }");
+  }
+
+  private attributeValue(value: ts.JsxAttributeValue | undefined): void {
+    if (value === undefined) {
+      this.emit("true");
+    } else if (ts.isStringLiteral(value)) {
+      this.sync(value.getStart(this.sf));
+      this.emit(JSON.stringify(decodeEntities(value.text)));
+    } else if (ts.isJsxExpression(value)) {
+      if (value.expression === undefined) this.emit("true");
+      else this.expression(value.expression);
+    } else {
+      this.sync(value.getStart(this.sf));
+      this.element(value as JsxRoot);
+    }
+  }
+}
+
+/** A child TypeScript counts: an expression container with an expression,
+ * text that is not only white space spanning lines, or an element. */
+function isSemanticJsxChild(child: ts.JsxChild): boolean {
+  if (ts.isJsxExpression(child)) return child.expression !== undefined;
+  if (ts.isJsxText(child)) return !child.containsOnlyTriviaWhiteSpaces;
+  return true;
+}
+
+/** True when the child emits a value (text that trims to nothing and empty
+ * expression containers emit none). */
+function jsxChildEmits(child: ts.JsxChild): boolean {
+  if (ts.isJsxText(child)) return jsxTextValue(child.text) !== undefined;
+  if (ts.isJsxExpression(child)) return child.expression !== undefined;
+  return true;
+}
+
+/** A `key` attribute after a spread that is not an object literal free of
+ * spreads: TypeScript emits createElement for such an element. */
+function hasKeyAfterPropsSpread(attributes: ts.JsxAttributes): boolean {
+  let spread = false;
+  for (const property of attributes.properties.nodes) {
+    if (
+      ts.isJsxSpreadAttribute(property) &&
+      (!ts.isObjectLiteralExpression(property.expression) ||
+        property.expression.properties.nodes.some((p: ts.ObjectLiteralElementLike) =>
+          ts.isSpreadAssignment(p),
+        ))
+    ) {
+      spread = true;
+    } else if (
+      spread &&
+      ts.isJsxAttribute(property) &&
+      ts.isIdentifier(property.name) &&
+      property.name.text === "key"
+    ) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/** The 1-based line and column of `pos`, counting the line breaks
+ * TypeScript counts (\r\n, \n, \r, U+2028, U+2029) and UTF-16 units. */
+function lineAndColumn(text: string, pos: number): { line: number; column: number } {
+  let line = 1;
+  let start = 0;
+  for (let i = 0; i < pos; i++) {
+    const ch = text.charCodeAt(i);
+    if (ch === 13 && text.charCodeAt(i + 1) === 10) continue;
+    if (isLineBreak(ch)) {
+      line++;
+      start = i + 1;
+    }
+  }
+  return { line, column: pos - start + 1 };
+}
+
+/** react-jsxdev's `self` argument. TypeScript passes `this`; where `this`
+ * has no declared type (the top level of an ES module and a function that is
+ * not a method and declares no `this` parameter) the argument is the
+ * `undefined` such code observes when called without a receiver, since an
+ * untyped `this` does not type-check under noImplicitThis. */
+function jsxSelf(node: ts.Node): string {
+  for (let at = node.parent; at !== undefined; at = at.parent) {
+    if (ts.isArrowFunction(at)) continue;
+    if (
+      ts.isMethodDeclaration(at) ||
+      ts.isConstructorDeclaration(at) ||
+      ts.isGetAccessorDeclaration(at) ||
+      ts.isSetAccessorDeclaration(at) ||
+      ts.isPropertyDeclaration(at) ||
+      ts.isClassStaticBlockDeclaration(at)
+    )
+      return "this";
+    if (ts.isFunctionDeclaration(at) || ts.isFunctionExpression(at)) {
+      const declaresThis = at.parameters.nodes.some(
+        (parameter: ts.ParameterDeclaration) =>
+          ts.isIdentifier(parameter.name) && parameter.name.text === "this",
+      );
+      const objectMethod =
+        ts.isFunctionExpression(at) &&
+        at.parent !== undefined &&
+        ts.isPropertyAssignment(at.parent);
+      return declaresThis || objectMethod ? "this" : "undefined";
+    }
+    if (ts.isSourceFile(at)) return ts.isExternalModule(at) ? "undefined" : "this";
+  }
+  return "undefined";
+}
+
+/** TypeScript's intrinsic-element test: a lowercase first letter or a dash. */
+function isIntrinsicJsxName(name: string): boolean {
+  const ch = name.charCodeAt(0);
+  return (ch >= 97 && ch <= 122) || name.includes("-");
+}
+
+function attributeName(name: ts.JsxAttributeName): string {
+  if (ts.isJsxNamespacedName(name))
+    return JSON.stringify(`${name.namespace.text}:${name.name.text}`);
+  return /^[A-Z_]\w*$/i.test(name.text) ? name.text : JSON.stringify(name.text);
+}
+
+function hasProtoProperty(object: ts.ObjectLiteralExpression): boolean {
+  return object.properties.nodes.some(
+    (property: ts.ObjectLiteralElementLike) =>
+      ts.isPropertyAssignment(property) &&
+      ((ts.isIdentifier(property.name) && property.name.text === "__proto__") ||
+        (ts.isStringLiteral(property.name) && property.name.text === "__proto__")),
+  );
+}
+
+/** A JSX text child's string value: each line trimmed (the first line keeps
+ * its leading and the last line its trailing white space), lines without
+ * text dropped, the rest joined with one space and entities decoded.
+ * Undefined when nothing remains. */
+export function jsxTextValue(text: string): string | undefined {
+  let value: string | undefined;
+  let firstNonWhitespace = 0;
+  let lastNonWhitespace = -1;
+  const add = (line: string): void => {
+    const decoded = decodeEntities(line);
+    value = value === undefined ? decoded : `${value} ${decoded}`;
+  };
+  for (let i = 0; i < text.length; i++) {
+    const ch = text.charCodeAt(i);
+    if (isLineBreak(ch)) {
+      if (firstNonWhitespace !== -1 && lastNonWhitespace !== -1)
+        add(text.slice(firstNonWhitespace, lastNonWhitespace + 1));
+      firstNonWhitespace = -1;
+    } else if (!isWhiteSpaceSingleLine(ch)) {
+      lastNonWhitespace = i;
+      if (firstNonWhitespace === -1) firstNonWhitespace = i;
+    }
+  }
+  if (firstNonWhitespace !== -1) add(text.slice(firstNonWhitespace));
+  return value;
+}
+
+/** Decodes `&name;`, `&#ddd;` and `&#xhh;` references. Unknown names and
+ * numbers past U+10FFFF stay as written. */
+export function decodeEntities(text: string): string {
+  return text.replace(
+    /&((#((\d+)|x([\da-fA-F]+)))|(\w+));/g,
+    (
+      match: string,
+      _all: string | undefined,
+      _number: string | undefined,
+      _digits: string | undefined,
+      decimal: string | undefined,
+      hex: string | undefined,
+      word: string | undefined,
+    ) => {
+      const code = decimal
+        ? parseInt(decimal, 10)
+        : hex
+          ? parseInt(hex, 16)
+          : JSX_ENTITIES.get(word!);
+      return code === undefined || code > 0x10ffff ? match : String.fromCodePoint(code);
+    },
+  );
+}

packages/compiler/src/frontend/literal-values.test.ts

@@ -8,16 +8,15 @@ import {
 
 function harness() {
   const members = new Map<number, SemanticTypeData[]>();
-  const snapshot = new SemanticSnapshot(1, {
-    text(method, payload) {
-      const query = JSON.parse(payload) as { objectId: number };
-      if (method !== "getTypesOfType" || !members.has(query.objectId))
-        throw new Error(`unexpected request: ${method}`);
-      return JSON.stringify(members.get(query.objectId));
-    },
-    binary(method) {
+  const reply = (method: string, payload: string) => {
+    const query = JSON.parse(payload) as { objectId: number };
+    if (method !== "getTypesOfType" || !members.has(query.objectId))
       throw new Error(`unexpected request: ${method}`);
-    },
+    return JSON.stringify(members.get(query.objectId));
+  };
+  const snapshot = new SemanticSnapshot(1, {
+    text: reply,
+    binary: (method, payload) => new TextEncoder().encode(reply(method, payload)),
   });
   const project = snapshot.addProject("literal-values", () => undefined);
   let id = 0;

packages/compiler/src/frontend/lowering/builtins/crypto.ts

@@ -1,6 +1,7 @@
 import { lowerBuiltinByteInput, errorFirstBytesCallback, errorFirstCallback } from "./arguments.js";
 import { isKeyObjectValue } from "./key-object.js";
 import { lowerCreateEcdh } from "./ecdh.js";
+import { lowerCreateDiffieHellman, lowerGetDiffieHellman } from "./dh.js";
 import { boolLit, dynUndefinedExpr, nodeThrowExpr, varRef } from "../../../ir/build.js";
 import * as ts from "../../ts7/adapter.js";
 import { type Lowerer, own } from "../lowerer.js";
@@ -411,6 +412,9 @@ export function lowerCryptoModuleCall(
     };
   }
   if (bi.member === "createECDH") return lowerCreateEcdh(lowerer, expr);
+  if (bi.member === "createDiffieHellman") return lowerCreateDiffieHellman(lowerer, expr);
+  if (bi.member === "getDiffieHellman" || bi.member === "createDiffieHellmanGroup")
+    return lowerGetDiffieHellman(lowerer, expr);
   if (bi.member === "createHmac") {
     if (args.length < 1 || args.length > 3 || args.some(ts.isSpreadElement)) {
       lowerer.noLowering(
@@ -696,6 +700,10 @@ export function lowerCryptoModuleCall(
       loc,
     };
   }
+  const pki = lowerPkiCall(lowerer, expr, bi.member, args, loc);
+  if (pki) return pki;
+  const prime = lowerPrimeCall(lowerer, expr, bi.member, args, loc);
+  if (prime) return prime;
   if (bi.member === "createSecretKey") {
     if (args.length < 1 || args.length > 2 || args.some(ts.isSpreadElement))
       lowerer.noLowering(
@@ -861,11 +869,29 @@ const IMPLEMENTED_CIPHERS = new Set([
   "id-aes192-gcm",
   "id-aes256-gcm",
   "chacha20-poly1305",
+  ...["128", "192", "256"].flatMap((bits) =>
+    ["ecb", "cfb", "cfb8", "cfb1", "ofb"].map((mode) => `aes-${bits}-${mode}`),
+  ),
+  "des-ede3-cbc",
+  "des3",
+  "des-ede3",
+  "des-ede3-ecb",
+  "des-ede3-cfb",
+  "des-ede3-cfb8",
+  "des-ede3-cfb1",
+  "des-ede3-ofb",
+  "des-ede-cbc",
+  "des-ede",
+  "des-ede-ecb",
+  "des-ede-cfb",
+  "des-ede-ofb",
+  "chacha20",
 ]);
 
 const SUPPORTED_CIPHERS_HINT =
-  "the supported ciphers are aes-128-cbc, aes-192-cbc, aes-256-cbc, aes-128-ctr, aes-192-ctr, " +
-  "aes-256-ctr, aes-128-gcm, aes-192-gcm, aes-256-gcm, and chacha20-poly1305";
+  "the supported ciphers are aes-128, aes-192 and aes-256 in cbc, ctr, gcm, ecb, cfb, cfb8, cfb1 " +
+  "and ofb modes, des-ede3 in cbc, ecb, cfb, cfb8, cfb1 and ofb modes, des-ede in cbc, ecb, cfb " +
+  "and ofb modes, chacha20, and chacha20-poly1305";
 
 /** A literal cipher name that Node knows but the runtime does not
  * implement is refused at compile time. Unknown literal names keep Node's
@@ -1339,3 +1365,108 @@ export function isWebCryptoReceiver(lowerer: Lowerer, receiver: ts.Expression):
   }
   return false;
 }
+
+/** Node calls checkPrime's and generatePrime's callbacks with undefined as
+ * the error, where @types/node declares Error | null: whether this
+ * callback's error parameter can hold undefined. One that cannot receives
+ * null instead. */
+function takesUndefinedError(lowerer: Lowerer, callback: ts.Expression): boolean {
+  const type = lowerer.irTypeOf(callback);
+  if (type.kind !== "func") return true;
+  const error = type.params[0];
+  if (error === undefined || error.kind === "dyn" || error.kind === "undefinedT") return true;
+  if (error.kind !== "union") return false;
+  return !!lowerer.unions.get(error.unionId)?.arms.some((arm) => arm.kind === "undefinedT");
+}
+
+/** checkPrime, checkPrimeSync, generatePrime and generatePrimeSync
+ * (scr_dh.c): checked-dynamic arguments, which the runtime checks as Node
+ * does (a function in the options position is the callback), and the
+ * sync forms' boolean, ArrayBuffer or bigint converted to the call site's
+ * type. Null for other members. */
+function lowerPrimeCall(
+  lowerer: Lowerer,
+  expr: ts.CallExpression,
+  member: string,
+  args: readonly ts.Expression[],
+  loc: SrcLoc,
+): IrExpr | null {
+  const forms: Readonly<Record<string, readonly [IrLibFn, number, number, string]>> = {
+    checkPrimeSync: ["crypto.checkPrimeSync", 1, 2, "checkPrimeSync(candidate[, options])"],
+    checkPrime: ["crypto.checkPrimeCb", 1, 3, "checkPrime(candidate[, options], callback)"],
+    generatePrimeSync: ["crypto.generatePrimeSync", 1, 2, "generatePrimeSync(size[, options])"],
+    generatePrime: ["crypto.generatePrimeCb", 1, 3, "generatePrime(size[, options], callback)"],
+  };
+  const form = forms[member];
+  if (!form) return null;
+  const [fn, min, max, supported] = form;
+  if (args.length < min || args.length > max || args.some(ts.isSpreadElement))
+    lowerer.noLowering(
+      `crypto.${member} with ${args.length} arguments`,
+      expr,
+      `${supported} is supported`,
+    );
+  const values = Array.from({ length: max }, (_, i) => dynArg(lowerer, args[i], loc));
+  if (fn === "crypto.checkPrimeCb" || fn === "crypto.generatePrimeCb") {
+    const callback = args[args.length - 1];
+    const nullError = callback !== undefined && !takesUndefinedError(lowerer, callback);
+    values.push({ kind: "boolLit", value: nullError, type: BOOL, loc });
+    return { kind: "libCall", fn, args: values, type: VOID, loc };
+  }
+  const call: IrExpr = { kind: "libCall", fn, args: values, type: DYN, loc };
+  const result = lowerer.mapTypeOf(lowerer.typeOf(expr));
+  if (result === null || result.kind === "dyn") return call;
+  return lowerer.coerceInto(expr, call, result);
+}
+
+/** The asymmetric-key and signature members (scr_pki.c): checked-dynamic
+ * arguments, and the result converted to the call site's type
+ * (KeyObject, Sign and Verify are checked-dynamic handles; key pairs,
+ * signatures and verdicts convert to their records, Buffers and
+ * booleans). Null for other members. */
+function lowerPkiCall(
+  lowerer: Lowerer,
+  expr: ts.CallExpression,
+  member: string,
+  args: readonly ts.Expression[],
+  loc: SrcLoc,
+): IrExpr | null {
+  const forms: Readonly<Record<string, readonly [IrLibFn, number, number, string]>> = {
+    createPrivateKey: ["crypto.createPrivateKey", 1, 1, "createPrivateKey(key)"],
+    createPublicKey: ["crypto.createPublicKey", 1, 1, "createPublicKey(key)"],
+    generateKeyPairSync: ["crypto.generateKeyPairSync", 1, 2, "generateKeyPairSync(type, options)"],
+    generateKeyPair: [
+      "crypto.generateKeyPairCb",
+      2,
+      3,
+      "generateKeyPair(type, [options,] callback)",
+    ],
+    sign: ["crypto.signOneshot", 3, 3, "sign(algorithm, data, key)"],
+    verify: ["crypto.verifyOneshot", 4, 4, "verify(algorithm, data, key, signature)"],
+    createSign: ["crypto.createSign", 1, 1, "createSign(algorithm)"],
+    createVerify: ["crypto.createVerify", 1, 1, "createVerify(algorithm)"],
+  };
+  const form = forms[member];
+  if (!form) return null;
+  const [fn, min, max, supported] = form;
+  if (args.length < min || args.length > max)
+    lowerer.noLowering(
+      `crypto.${member} with ${args.length} arguments`,
+      expr,
+      `${supported} is supported`,
+    );
+  // generateKeyPair(type, callback): Node reads a function in the options
+  // position as the callback.
+  const shifted = fn === "crypto.generateKeyPairCb" && args.length === 2;
+  const values: IrExpr[] = [];
+  for (let i = 0; i < max; i++) {
+    const node = shifted ? (i === 1 ? undefined : i === 2 ? args[1] : args[i]) : args[i];
+    values.push(dynArg(lowerer, node, loc));
+  }
+  if (fn === "crypto.generateKeyPairCb")
+    return { kind: "libCall", fn, args: values, type: VOID, loc };
+  const call: IrExpr = { kind: "libCall", fn, args: values, type: DYN, loc };
+  const result = lowerer.mapTypeOf(lowerer.typeOf(expr));
+  if (result === null || result.kind === "dyn") return call;
+  return lowerer.coerceInto(expr, call, result);
+}

packages/compiler/src/frontend/lowering/builtins/dh.ts

@@ -0,0 +1,166 @@
+import * as ts from "../../ts7/adapter.js";
+import { nodeThrowExpr } from "../../../ir/build.js";
+import { type Lowerer } from "../lowerer.js";
+import { locOf } from "../../program.js";
+import { DYN, type IrExpr, type IrStmt } from "../../../ir/ir.js";
+import { v8CalleeText } from "./crypto.js";
+import { dynArguments, refuseUnmatchedOverload } from "./ecdh.js";
+
+/* node:crypto's DiffieHellman and DiffieHellmanGroup are native
+ * checked-dynamic handles (scr_dh.c): both types map to dyn, their methods
+ * dispatch through the handle, and these helpers lower
+ * createDiffieHellman, getDiffieHellman, createDiffieHellmanGroup and the
+ * method calls. The runtime applies Node's argument checks, so the
+ * constructors take any arguments; method calls are refused when their
+ * argument types leave the Buffer or string result undetermined. */
+
+/** Whether a checker type is node:crypto's DiffieHellman class or its
+ * DiffieHellmanGroup alias, or a union of them. */
+export function isDiffieHellmanType(lowerer: Lowerer, type: ts.Type): boolean {
+  if (type.isUnionType())
+    return ts.constituentTypes(type).every((part) => isDiffieHellmanType(lowerer, part));
+  const symbol = type.getAliasSymbol() ?? type.getSymbol();
+  if (!symbol || !lowerer.isStdlibSymbol(symbol)) return false;
+  const name = ts.symbolName(symbol);
+  return name === "DiffieHellman" || name === "DiffieHellmanGroup";
+}
+
+function isDiffieHellmanGroupType(type: ts.Type): boolean {
+  if (type.isUnionType()) return ts.constituentTypes(type).some(isDiffieHellmanGroupType);
+  const symbol = type.getAliasSymbol();
+  return !!symbol && ts.symbolName(symbol) === "DiffieHellmanGroup";
+}
+
+function newHandle(
+  lowerer: Lowerer,
+  call: ts.CallExpression,
+  fn: "crypto.dhNew" | "crypto.dhGroupNew",
+): IrExpr {
+  const loc = locOf(call);
+  const stmts: IrStmt[] = [];
+  const values = dynArguments(lowerer, call, fn === "crypto.dhNew" ? 4 : 1, stmts, "%dhInput");
+  return {
+    kind: "seqExpr",
+    stmts,
+    result: { kind: "libCall", fn, args: values, type: DYN, loc },
+    type: DYN,
+    loc,
+  };
+}
+
+/** crypto.createDiffieHellman(sizeOrKey, keyEncoding, generator,
+ * generatorEncoding): a native DiffieHellman handle. */
+export function lowerCreateDiffieHellman(lowerer: Lowerer, call: ts.CallExpression): IrExpr {
+  return newHandle(lowerer, call, "crypto.dhNew");
+}
+
+/** crypto.getDiffieHellman(groupName) and createDiffieHellmanGroup(name):
+ * a native DiffieHellmanGroup handle. */
+export function lowerGetDiffieHellman(lowerer: Lowerer, call: ts.CallExpression): IrExpr {
+  return newHandle(lowerer, call, "crypto.dhGroupNew");
+}
+
+const DH_METHODS = new Set([
+  "generateKeys",
+  "computeSecret",
+  "getPrime",
+  "getGenerator",
+  "getPublicKey",
+  "getPrivateKey",
+  "setPublicKey",
+  "setPrivateKey",
+]);
+
+/** Object.prototype methods, which a DiffieHellman inherits. */
+const OBJECT_METHODS = new Set([
+  "constructor",
+  "hasOwnProperty",
+  "isPrototypeOf",
+  "propertyIsEnumerable",
+  "toLocaleString",
+  "toString",
+  "valueOf",
+]);
+
+/** The argument that selects each method's Buffer or string result: the
+ * output encoding. */
+const OUTPUT_ENCODING_ARG: Record<string, number> = {
+  generateKeys: 0,
+  computeSecret: 2,
+  getPrime: 0,
+  getGenerator: 0,
+  getPublicKey: 0,
+  getPrivateKey: 0,
+};
+
+/** An output encoding typed any: the checker's chosen overload then types
+ * the result as a Buffer or a string that Node may not answer, so the call
+ * is refused rather than checked against that type at run time. */
+function refuseAnyOutputEncoding(lowerer: Lowerer, call: ts.CallExpression, name: string): void {
+  const index = OUTPUT_ENCODING_ARG[name];
+  const arg = index === undefined ? undefined : call.arguments.nodes[index];
+  if (!arg || (lowerer.typeOf(arg).flags & ts.TypeFlags.Any) === 0) return;
+  lowerer.noLowering(
+    `DiffieHellman.${name} with an output encoding typed any`,
+    arg,
+    "type the encoding as a BinaryToTextEncoding such as 'hex', or as null or undefined for a Buffer",
+  );
+}
+
+/** Calls on native DiffieHellman and DiffieHellmanGroup handles. Methods
+ * dispatch through the handle with checked-dynamic arguments. */
+export function lowerDiffieHellmanCall(lowerer: Lowerer, call: ts.CallExpression): IrExpr | null {
+  if (call.questionDotToken || !ts.isPropertyAccessExpression(call.expression)) return null;
+  const access = call.expression;
+  if (access.questionDotToken) return null;
+  const receiver = lowerer.typeOf(access.expression);
+  if (!isDiffieHellmanType(lowerer, receiver)) return null;
+  const name = access.name.text;
+  const loc = locOf(call);
+  const setter = name === "setPublicKey" || name === "setPrivateKey";
+  if (!DH_METHODS.has(name) || (setter && isDiffieHellmanGroupType(receiver))) {
+    if (OBJECT_METHODS.has(name))
+      lowerer.noLowering(
+        `DiffieHellman.${name}`,
+        call,
+        "generateKeys(), computeSecret(), getPrime(), getGenerator(), getPublicKey(), getPrivateKey(), " +
+          "setPublicKey(), setPrivateKey() and verifyError are supported",
+      );
+    // Node reads the member as undefined (a DiffieHellmanGroup has no key
+    // setters) and throws a TypeError once the receiver and arguments are
+    // evaluated.
+    const evaluated = [access.expression, ...call.arguments.nodes].map((node): IrStmt => ({
+      kind: "exprStmt",
+      expr: lowerer.lowerExpr(node),
+      loc,
+    }));
+    return {
+      kind: "seqExpr",
+      stmts: evaluated,
+      result: nodeThrowExpr(1, "", `${v8CalleeText(access)} is not a function`, DYN, loc),
+      type: DYN,
+      loc,
+    };
+  }
+  if (call.arguments.nodes.some(ts.isSpreadElement))
+    lowerer.noLowering(`DiffieHellman.${name} with spread arguments`, call);
+  refuseAnyOutputEncoding(lowerer, call, name);
+  refuseUnmatchedOverload(lowerer, call, `DiffieHellman.${name}`);
+  const invoke: IrExpr = {
+    kind: "dynInvoke",
+    recv: lowerer.lowerExprExpecting(access.expression, DYN),
+    method: name,
+    calleeName: v8CalleeText(access),
+    args: call.arguments.nodes.map((arg) => lowerer.lowerExprExpecting(arg, DYN)),
+    type: DYN,
+    loc,
+  };
+  // setPublicKey and setPrivateKey answer the receiver where @types/node
+  // declares void. Other results take the static representation of the
+  // declared overload the arguments match.
+  if (setter) return invoke;
+  const result = lowerer.irTypeOf(call);
+  return result.kind === "bytes" || result.kind === "string"
+    ? lowerer.coerceInto(call, invoke, result)
+    : invoke;
+}

packages/compiler/src/frontend/lowering/builtins/ecdh.ts

@@ -28,15 +28,16 @@ export function isEcdhType(lowerer: Lowerer, type: ts.Type): boolean {
   return !!symbol && ts.symbolName(symbol) === "ECDH" && lowerer.isStdlibSymbol(symbol);
 }
 
-/** The call's arguments as checked-dynamic values in hidden locals, the
- * first `count` of them padded with undefined, so every argument is
- * evaluated left to right before the runtime checks them. Surplus
- * arguments are evaluated and dropped. */
-function dynArguments(
+/** The call's arguments as checked-dynamic values in hidden locals named
+ * `local`, the first `count` of them padded with undefined, so every
+ * argument is evaluated left to right before the runtime checks them.
+ * Surplus arguments are evaluated and dropped. */
+export function dynArguments(
   lowerer: Lowerer,
   call: ts.CallExpression,
   count: number,
   stmts: IrStmt[],
+  local = "%ecdhInput",
 ): IrExpr[] {
   const args = call.arguments.nodes;
   const loc = locOf(call);
@@ -45,7 +46,7 @@ function dynArguments(
     const input: IrExpr = args[i]
       ? lowerer.lowerExprExpecting(args[i]!, DYN)
       : dynUndefinedExpr(loc);
-    const saved = lowerer.declareHiddenLocal("%ecdhInput", DYN);
+    const saved = lowerer.declareHiddenLocal(local, DYN);
     stmts.push({ kind: "varDecl", localId: saved.id, init: input, loc });
     values.push(varRef(saved.id, DYN, loc));
   }
@@ -137,7 +138,11 @@ function refuseViewKeyWithEncoding(lowerer: Lowerer, call: ts.CallExpression, na
  * not follow (getPublicKey("HEX") answers a string where the encoding-less
  * overload declares a Buffer), so the call is refused rather than checked
  * against that type at run time. Arguments typed any are accepted. */
-function refuseUnmatchedOverload(lowerer: Lowerer, call: ts.CallExpression, what: string): void {
+export function refuseUnmatchedOverload(
+  lowerer: Lowerer,
+  call: ts.CallExpression,
+  what: string,
+): void {
   const signature = lowerer.checker.getResolvedSignature(call);
   if (signature === undefined) return;
   const params = signature.getParameters();

packages/compiler/src/frontend/lowering/builtins/key-object.ts

@@ -4,10 +4,11 @@ import { locOf } from "../../program.js";
 import { BOOL, DYN, type IrExpr } from "../../../ir/ir.js";
 import { builtinImportOf } from "./module-bindings.js";
 
-/* node:crypto's secret KeyObject is a native checked-dynamic handle
- * (scr_lib.c): the KeyObject type maps to dyn, its getters and methods
- * dispatch through the handle, and these helpers lower the class's uses
- * that a dyn value cannot answer by itself. */
+/* node:crypto's KeyObject is a native checked-dynamic handle (secret keys
+ * in scr_lib.c, private and public keys in scr_pki.c), as are Sign and
+ * Verify: the types map to dyn, their getters and methods dispatch through
+ * the handle, and these helpers lower the uses that a dyn value cannot
+ * answer by itself. */
 
 /** Whether `node` names node:crypto's KeyObject class. */
 export function isKeyObjectClass(lowerer: Lowerer, node: ts.Expression): boolean {
@@ -37,15 +38,31 @@ export function lowerKeyObjectInstanceof(
 }
 
 const KEY_OBJECT_METHODS = new Set(["export", "equals", "toCryptoKey"]);
+const SIGNER_METHODS = new Set(["update", "sign", "verify"]);
 
-/** `key.export(...)`, `key.equals(...)` and `key.toCryptoKey(...)`: the
+/** Whether a value's checker type is node:crypto's Sign or Verify. */
+function isSignerValue(lowerer: Lowerer, node: ts.Expression): boolean {
+  const type = lowerer.typeOf(node);
+  const sym = type.getAliasSymbol() ?? type.getSymbol();
+  return (
+    !!sym &&
+    (ts.symbolName(sym) === "Sign" || ts.symbolName(sym) === "Verify") &&
+    lowerer.isStdlibSymbol(sym)
+  );
+}
+
+/** `key.export(...)`, `key.equals(...)` and `key.toCryptoKey(...)`, and
+ * the update/sign/verify methods of Sign and Verify (scr_pki.c): the
  * handle answers them as methods, so they dispatch through dynInvoke
  * rather than as a member read and a call. */
 export function lowerKeyObjectCall(lowerer: Lowerer, call: ts.CallExpression): IrExpr | null {
   if (call.questionDotToken || !ts.isPropertyAccessExpression(call.expression)) return null;
   const access = call.expression;
-  if (access.questionDotToken || !KEY_OBJECT_METHODS.has(access.name.text)) return null;
-  if (!isKeyObjectValue(lowerer, access.expression)) return null;
+  if (access.questionDotToken) return null;
+  const method = access.name.text;
+  const keyMethod = KEY_OBJECT_METHODS.has(method) && isKeyObjectValue(lowerer, access.expression);
+  if (!keyMethod && !(SIGNER_METHODS.has(method) && isSignerValue(lowerer, access.expression)))
+    return null;
   if (call.arguments.nodes.some(ts.isSpreadElement)) return null;
   return {
     kind: "dynInvoke",

packages/compiler/src/frontend/lowering/builtins/webcrypto.ts

@@ -7,10 +7,11 @@ import { stdlibGlobalNameOf } from "../surfaces.js";
 import { WEBCRYPTO_DYN_TYPES } from "../../type-mapper.js";
 import { isWebCryptoReceiver } from "./crypto.js";
 
-/* WebCrypto's secret-key slice (scr_webcrypto.c, with encrypt and
- * decrypt in scr_webcrypto_aes.c): `crypto.subtle`'s `importKey`,
- * `generateKey`, `exportKey`, `encrypt`, `decrypt`, `deriveBits`,
- * `deriveKey`, `sign`, `verify` and `digest`
+/* WebCrypto (scr_webcrypto.c, with encrypt and decrypt in
+ * scr_webcrypto_aes.c and the ECDSA, Ed25519, RSASSA-PKCS1-v1_5 and RSA-PSS
+ * algorithms in scr_webcrypto_pki.c): `crypto.subtle`'s `importKey`,
+ * `generateKey`, `exportKey`, `encrypt`, `decrypt`, `wrapKey`,
+ * `unwrapKey`, `deriveBits`, `deriveKey`, `sign`, `verify` and `digest`
  * called on the crypto global (also through
  * globalThis, node:crypto's webcrypto and node:crypto's subtle) lower to
  * runtime entry points that take the argument vector as one dyn array and
@@ -20,11 +21,13 @@ import { isWebCryptoReceiver } from "./crypto.js";
  * are handle reads. Other SubtleCrypto methods are refused by name. */
 
 const SUBTLE_LOWERED: ReadonlyMap<string, IrLibFn> = new Map([
-  ["importKey", "webcrypto.importKey"],
   ["generateKey", "webcrypto.generateKey"],
+  ["importKey", "webcrypto.importKey"],
   ["exportKey", "webcrypto.exportKey"],
   ["encrypt", "webcrypto.encrypt"],
   ["decrypt", "webcrypto.decrypt"],
+  ["wrapKey", "webcrypto.wrapKey"],
+  ["unwrapKey", "webcrypto.unwrapKey"],
   ["deriveBits", "webcrypto.deriveBits"],
   ["deriveKey", "webcrypto.deriveKey"],
   ["sign", "webcrypto.sign"],
@@ -33,7 +36,7 @@ const SUBTLE_LOWERED: ReadonlyMap<string, IrLibFn> = new Map([
 ]);
 
 const SUBTLE_HINT =
-  "the native WebCrypto surface is crypto.subtle's importKey, generateKey and exportKey for HMAC and AES keys (importKey also for PBKDF2 and HKDF keys), encrypt and decrypt with AES-GCM, AES-CBC or AES-CTR, deriveBits and deriveKey with PBKDF2 or HKDF, sign and verify with HMAC, and digest with SHA-1, SHA-256, SHA-384 or SHA-512, each called directly on crypto.subtle";
+  "the native WebCrypto surface is crypto.subtle's importKey, generateKey and exportKey for HMAC and AES keys (importKey also for PBKDF2 and HKDF keys), encrypt and decrypt with AES-GCM, AES-CBC or AES-CTR, wrapKey and unwrapKey of secret keys with AES-KW or those ciphers, deriveBits and deriveKey with PBKDF2 or HKDF, sign and verify with HMAC, generateKey, importKey, exportKey, sign and verify for ECDSA, Ed25519, RSASSA-PKCS1-v1_5 and RSA-PSS, and digest with SHA-1, SHA-256, SHA-384 or SHA-512, each called directly on crypto.subtle";
 
 /** Whether `node` is a SubtleCrypto object: `subtle` on a WebCrypto
  * Crypto object (the global, globalThis.crypto or node:crypto's

packages/compiler/src/frontend/lowering/caught-value-dispatch.ts

@@ -11,6 +11,7 @@ import {
 } from "../../ir/ir.js";
 import { everyStmtList, transformStmtList } from "../../ir/traverse.js";
 import { classInstanceOf } from "./class-dynamic-dispatch.js";
+import type { DispatchSites } from "./dispatch-sites.js";
 import type { ClassInfo } from "./lower-classes.js";
 import type { Lowerer } from "./lowerer.js";
 
@@ -26,25 +27,16 @@ export class CaughtValueDispatch {
   private readonly payloadHelpers = new Map<string, IrFunction>();
   private readonly payloadHelperFns = new Set<IrFunction>();
 
-  process(lowerer: Lowerer, functions: readonly IrFunction[]): boolean {
+  process(lowerer: Lowerer, functions: readonly IrFunction[], sites: DispatchSites): boolean {
     const consumers: IrFunction[] = [];
     for (const fn of functions) {
       if (fn === this.helper) continue;
-      let consumes = false;
-      everyStmtList(fn.body, {
-        stmt: (stmt) => {
-          if (stmt.kind === "throw" && stmt.value.type.kind === "object") {
-            const info = lowerer.classes.get(stmt.value.type.className);
-            if (info) this.thrownClasses.add(info.def.name);
-          }
-          return true;
-        },
-        expr: (expr) => {
-          if (expr.kind === "caughtToDyn") consumes = true;
-          return true;
-        },
-      });
-      if (consumes) consumers.push(fn);
+      const found = sites.of(fn);
+      for (const className of found.thrown) {
+        const info = lowerer.classes.get(className);
+        if (info) this.thrownClasses.add(info.def.name);
+      }
+      if (found.caughtValues) consumers.push(fn);
     }
     if (!this.helper && consumers.length === 0) return false;
     let changed = false;

packages/compiler/src/frontend/lowering/class-construction.ts

@@ -13,7 +13,8 @@ import {
   type IrType,
   type SrcLoc,
 } from "../../ir/ir.js";
-import { everyStmtList, transformExpr, transformStmtList } from "../../ir/traverse.js";
+import { transformExpr, transformStmtList } from "../../ir/traverse.js";
+import type { DispatchSites } from "./dispatch-sites.js";
 import type { Lowerer } from "./lowerer.js";
 import type { ParamShape } from "./call-signatures.js";
 import { classPrototypeData } from "./class-prototypes.js";
@@ -24,16 +25,21 @@ const PREFIX = "%class.construct:";
 const PACKED = `${PREFIX}packed`;
 const INSTANCEOF = "%class.instanceof:dynamic";
 
+/** `value instanceof callee` for an untyped constructor value, through one
+ * shared helper. `refusal` is the site's message for a runtime
+ * constructor with no instance test. */
 export function checkedClassInstanceOf(
   lowerer: Lowerer,
   value: IrExpr,
   callee: IrExpr,
+  refusal: string,
   loc: SrcLoc,
 ): IrExpr {
   if (!lowerer.liftedFns.some((fn) => fn.name === INSTANCEOF)) {
     const params = [
       { localId: "value", name: "value", type: DYN },
       { localId: "callee", name: "callee", type: DYN },
+      { localId: "refusal", name: "refusal", type: STRING },
     ];
     lowerer.liftedFns.push({
       name: INSTANCEOF,
@@ -46,7 +52,11 @@ export function checkedClassInstanceOf(
           value: {
             kind: "libCall",
             fn: "bytes.instanceOf",
-            args: [varRef("value", DYN, loc), varRef("callee", DYN, loc)],
+            args: [
+              varRef("value", DYN, loc),
+              varRef("callee", DYN, loc),
+              varRef("refusal", STRING, loc),
+            ],
             type: BOOL,
             loc,
           },
@@ -56,7 +66,13 @@ export function checkedClassInstanceOf(
       loc,
     });
   }
-  return { kind: "call", callee: INSTANCEOF, args: [value, callee], type: BOOL, loc };
+  return {
+    kind: "call",
+    callee: INSTANCEOF,
+    args: [value, callee, { kind: "strLit", value: refusal, type: STRING, loc }],
+    type: BOOL,
+    loc,
+  };
 }
 
 /** Checked construction dispatches to emitted native constructor thunks. */
@@ -254,22 +270,17 @@ export class ClassConstructionDispatch {
   private prototypeHelper: IrFunction | null = null;
   private readonly prototypes = new Set<string>();
 
-  process(lowerer: Lowerer, functions: readonly IrFunction[]): boolean {
+  process(lowerer: Lowerer, functions: readonly IrFunction[], sites: DispatchSites): boolean {
     const discover = (type: IrType): void => {
       if (type.kind === "classval") this.constructors.add(type.className);
       else if (type.kind === "union") lowerer.unions.get(type.unionId)?.arms.forEach(discover);
     };
     const prototypeReads = new Set<IrFunction>();
-    for (const fn of functions)
-      everyStmtList(fn.body, {
-        stmt: () => true,
-        expr: (expr) => {
-          if (expr.kind === "dynFrom") discover(expr.value.type);
-          if (expr.kind === "libCall" && expr.fn === "dyn.classBasePrototype")
-            prototypeReads.add(fn);
-          return true;
-        },
-      });
+    for (const fn of functions) {
+      const found = sites.of(fn);
+      found.values.forEach(discover);
+      if (found.basePrototypes) prototypeReads.add(fn);
+    }
     let changed = false;
     for (const fn of functions) {
       if (fn === this.prototypeHelper || !prototypeReads.has(fn)) continue;

packages/compiler/src/frontend/lowering/class-dynamic-dispatch.ts

@@ -1,4 +1,5 @@
 import { primitiveConstructorOr } from "./lower-exprs.js";
+import { InternalCompilerError } from "../../errors.js";
 import { dynUndefinedExpr, helperLoc, nodeThrowExpr, varRef } from "../../ir/build.js";
 import { constructedValue } from "./constructor-returns.js";
 import { eventTargetApiMembers, eventTargetInheritedMember } from "./lower-event-target.js";
@@ -77,6 +78,7 @@ import { isClassCallback } from "./class-callbacks.js";
 import { CaughtValueDispatch } from "./caught-value-dispatch.js";
 import { refreshDescriptorGuards } from "./class-descriptors.js";
 import { ClassConstructionDispatch } from "./class-construction.js";
+import { DispatchSites } from "./dispatch-sites.js";
 import {
   emitterRooted,
   lowerDynamicEmitterEmit,
@@ -226,7 +228,7 @@ const KEY_CALLS = new Map<string, "object" | "any" | "value">([
   ["dyn.keySetComputed", "value"],
 ]);
 
-function toPrimitiveHint(expr: IrExpr): ToPrimitiveHint | null {
+export function toPrimitiveHint(expr: IrExpr): ToPrimitiveHint | null {
   if (expr.kind === "toString") return expr.operand.type.kind === "dyn" ? "string" : null;
   if (expr.kind === "dynKeyGet") return expr.key.type.kind === "dyn" ? "string" : null;
   if (expr.kind !== "libCall") return null;
@@ -467,6 +469,79 @@ function sortAdded(lowerer: Lowerer, set: Set<string>, from: number): void {
   for (const name of added) set.add(name);
 }
 
+/** The receivers of one property-receiver list (propertyReceivers) by the
+ * names that can make them answer a member, as positions in the list. A
+ * receiver whose root answers names of its own (an emitter, a stream, an
+ * EventTarget or a Date) is in `rooted` instead. */
+interface ReceiverIndex {
+  plans: readonly PropertyReceiver[];
+  /** By a method or generic method its base chain declares. */
+  methods: Map<string, number[]>;
+  /** By a method, generic method or accessor its base chain declares (an
+   * accessor under its key and under its property name), or a field it has. */
+  members: Map<string, number[]>;
+  rooted: number[];
+}
+
+function receiverIndex(lowerer: Lowerer, plans: readonly PropertyReceiver[]): ReceiverIndex {
+  const methods = new Map<string, number[]>();
+  const members = new Map<string, number[]>();
+  const rooted: number[] = [];
+  const add = (table: Map<string, number[]>, name: string, position: number): void => {
+    const positions = table.get(name);
+    if (positions === undefined) table.set(name, [position]);
+    else if (positions[positions.length - 1] !== position) positions.push(position);
+  };
+  plans.forEach(({ info }, position) => {
+    if (
+      emitterRooted(lowerer, info) ||
+      info.builtinStream !== undefined ||
+      eventTargetApiMembers(info) !== null ||
+      dateRootOf(info) !== null
+    ) {
+      rooted.push(position);
+      return;
+    }
+    for (let c: ClassInfo | null = info; c; c = c.base) {
+      for (const name of c.methods.keys()) {
+        add(methods, name, position);
+        // A `get:`/`set:` key is an accessor of the property after the
+        // prefix, or a method whose quoted name has that prefix; the test
+        // looks up both.
+        add(members, name, position);
+        if (name.startsWith("get:") || name.startsWith("set:"))
+          add(members, name.slice(4), position);
+      }
+      if (c.genericMethods)
+        for (const name of c.genericMethods.keys()) {
+          add(methods, name, position);
+          add(members, name, position);
+        }
+    }
+    for (const name of info.fields.keys()) add(members, name, position);
+  });
+  for (const table of [methods, members])
+    for (const positions of table.values()) positions.sort((a, b) => a - b);
+  return { plans, methods, members, rooted };
+}
+
+/** The ascending union of two ascending position lists. */
+function mergePositions(left: readonly number[], right: readonly number[]): number[] {
+  const out: number[] = [];
+  let i = 0;
+  let j = 0;
+  while (i < left.length || j < right.length) {
+    const next =
+      j >= right.length || (i < left.length && left[i]! <= right[j]!) ? left[i++]! : right[j++]!;
+    if (out[out.length - 1] !== next) out.push(next);
+  }
+  return out;
+}
+
+/** SCRIPTC_CHECK_DISPATCH_CANDIDATES=1 checks every indexed receiver selection
+ * against a test of every receiver. */
+const CHECK_CANDIDATES = process.env["SCRIPTC_CHECK_DISPATCH_CANDIDATES"] === "1";
+
 export function classPropertiesHelper(lowerer: Lowerer, loc: SrcLoc, readOnly = false): IrFunction {
   const name = readOnly ? READ_PROPERTIES : "%dyn.class.properties";
   lowerer.shareHelper(name);
@@ -780,6 +855,8 @@ export class ClassDynamicDispatch {
   private readonly generatorDispatch = new GeneratorDynamicDispatch();
   private readonly caughtDispatch = new CaughtValueDispatch();
   private readonly constructionDispatch = new ClassConstructionDispatch();
+  /** What each function's body holds for this pass and its sub-passes. */
+  readonly sites = new DispatchSites();
   /** Property names a delete can remove (null: any name), for the field
    * creation tracking decision. */
   private deletedNames: Set<string> | null | undefined;
@@ -862,12 +939,13 @@ export class ClassDynamicDispatch {
       )
         fn.body.shift();
     }
-    let changed = this.caughtDispatch.process(lowerer, functions);
+    let changed = this.caughtDispatch.process(lowerer, functions, this.sites);
     changed = refreshErrorMethodDispatch(lowerer, functions) || changed;
     changed = refreshClassMethodValueSelections(lowerer) || changed;
     changed = refreshErrorPropertyDispatch(lowerer, functions) || changed;
-    changed = this.generatorDispatch.process(lowerer, functions, this.generated) || changed;
-    changed = this.constructionDispatch.process(lowerer, functions) || changed;
+    changed =
+      this.generatorDispatch.process(lowerer, functions, this.generated, this.sites) || changed;
+    changed = this.constructionDispatch.process(lowerer, functions, this.sites) || changed;
     const seenTypes = new Set<string>();
     const rewrite = new Set<IrFunction>();
     const toPrimitiveSites = new Set<IrFunction>();
@@ -891,100 +969,18 @@ export class ClassDynamicDispatch {
     };
     const boxedBefore = this.boxed.size;
     const boxedConstructorsBefore = this.boxedConstructors.size;
-    for (const fn of functions)
-      everyStmtList(fn.body, {
-        stmt: (statement) => {
-          // Field-creation instrumentation can box a base-constructor receiver
-          // even when only its derived instances otherwise cross the boundary.
-          if (
-            statement.kind === "fieldSet" &&
-            lowerer.classes.get(statement.className)?.def.tracksOwnFields &&
-            isClassOwnEnumerableFieldName(statement.field)
-          )
-            discover(statement.obj.type);
-          return true;
-        },
-        expr: (expr) => {
-          if (
-            expr.kind === "jsonStringify" ||
-            (expr.kind === "libCall" &&
-              (expr.fn === "json.stringifyValue" || expr.fn === "json.stringifyReplacer"))
-          ) {
-            this.serializesClasses = true;
-          }
-          if (
-            toPrimitiveHint(expr) !== null ||
-            (expr.kind === "libCall" && (expr.fn === "dyn.valueOf" || expr.fn === "dyn.toString"))
-          )
-            toPrimitiveSites.add(fn);
-          switch (expr.kind) {
-            case "dynFrom":
-              discover(expr.value.type);
-              break;
-            case "fieldIncDec":
-              if (
-                lowerer.classes.get(expr.className)?.def.tracksOwnFields &&
-                isClassOwnEnumerableFieldName(expr.field)
-              )
-                discover(expr.obj.type);
-              break;
-            case "call":
-              if (
-                (expr.callee === "%dyn.class.properties" ||
-                  expr.callee === "%dyn.class.readProperties") &&
-                expr.args[0]?.kind === "dynFrom" &&
-                isDynTypedRefType(expr.args[0].value.type)
-              )
-                rewrite.add(fn);
-              break;
-            case "dynHasKey":
-              hasKeySites.add(fn);
-              break;
-            case "caughtTest":
-              if (expr.test === "instanceof") caughtSites.add(fn);
-              break;
-            case "caughtNarrow":
-            case "caughtCheck":
-              if (expr.type.kind === "object") caughtSites.add(fn);
-              break;
-            case "dynKeyGet":
-            case "dynInvoke":
-              rewrite.add(fn);
-              break;
-            case "dynCheck":
-              if (isDynTypedRefType(expr.type)) rewrite.add(fn);
-              // A dynamic function checked into a native function type
-              // receives its arguments as dynamic values: class instances
-              // passed to it cross the boundary when it is called (a JS
-              // `list.map((rec) => rec.match(x))` callback with an untyped
-              // parameter).
-              if (expr.type.kind === "func") expr.type.params.forEach(discover);
-              break;
-            case "libCall":
-              if (
-                expr.fn === "bytes.construct" ||
-                expr.fn === "dyn.keySet" ||
-                expr.fn === "dyn.keySetComputed" ||
-                expr.fn === "dyn.iterator" ||
-                expr.fn === "dyn.arrayFromIterator" ||
-                expr.fn === "dyn.toString" ||
-                expr.fn === "dyn.stringConstructor" ||
-                expr.fn === "dyn.forInKeys" ||
-                expr.fn === "dyn.forInKeyStrings" ||
-                expr.fn === "dyn.hasKeyComputed" ||
-                expr.fn === "dyn.hasOwnComputed" ||
-                expr.fn === "dyn.propertyIsEnumerableComputed" ||
-                expr.fn === "dyn.defineProperty" ||
-                expr.fn === "dyn.getPrototype" ||
-                expr.fn === "dyn.reflectGet" ||
-                expr.fn === "dyn.reflectSet"
-              )
-                rewrite.add(fn);
-              break;
-          }
-          return true;
-        },
-      });
+    for (const fn of functions) {
+      const found = this.sites.of(fn);
+      // A class starts tracking its own fields during this pass.
+      for (const { type, fieldClass } of found.boxing)
+        if (fieldClass === undefined || lowerer.classes.get(fieldClass)?.def.tracksOwnFields)
+          discover(type);
+      if (found.serializes) this.serializesClasses = true;
+      if (found.conversions) toPrimitiveSites.add(fn);
+      if (found.dispatches) rewrite.add(fn);
+      if (found.keyTests) hasKeySites.add(fn);
+      if (found.caughtClassTests) caughtSites.add(fn);
+    }
     // The classes this pass found join the tables in a fixed order, not in
     // the order the scan met them.
     sortAdded(lowerer, this.boxed, boxedBefore);
@@ -1342,10 +1338,30 @@ export class ClassDynamicDispatch {
     }
     refreshDescriptorGuards(lowerer);
     const byMethod = new Map<string, ClassInfo[]>();
+    // A query asks every receiver about one name, and the program's dispatch
+    // sites ask about thousands: index the receivers by name once per list.
+    let index: ReceiverIndex | null = null;
+    const indexOf = (plans: readonly PropertyReceiver[]): ReceiverIndex =>
+      index?.plans === plans ? index : (index = receiverIndex(lowerer, plans));
+    /** The receivers of `plans` that can answer `name`, in list order: those
+     * `table` lists under it and the rooted ones. Emit-override
+     * specializations (`emit:<event>`) join a class's methods while bodies
+     * lower, so they keep every receiver. */
+    const receiversFor = (
+      plans: readonly PropertyReceiver[],
+      name: string,
+      table: "methods" | "members",
+    ): readonly PropertyReceiver[] => {
+      if (name.startsWith("emit:")) return plans;
+      const found = indexOf(plans);
+      const positions = (table === "methods" ? found.methods : found.members).get(name);
+      return mergePositions(positions ?? [], found.rooted).map((position) => plans[position]!);
+    };
     const candidates = (method: string): ClassInfo[] => {
       const found = byMethod.get(method);
       if (found) return found;
-      const matching = this.propertyReceivers(lowerer, true).flatMap(({ info }) => {
+      const plans = this.propertyReceivers(lowerer, true);
+      const test = ({ info }: PropertyReceiver): ClassInfo[] => {
         if (!info || info.fields.has(method) || info.builtinError) return [];
         if (emitterRooted(lowerer, info) && EMITTER_METHODS.has(method)) return [info];
         if (
@@ -1364,7 +1380,13 @@ export class ClassDynamicDispatch {
         return findMethodOn(lowerer, info, method) || findGenericMethodOn(lowerer, info, method)
           ? [info]
           : [];
-      });
+      };
+      const matching = receiversFor(plans, method, "methods").flatMap(test);
+      if (CHECK_CANDIDATES) {
+        const every = plans.flatMap(test);
+        if (every.length !== matching.length || every.some((info, i) => info !== matching[i]))
+          throw new InternalCompilerError(`indexed candidates for ${method} differ`);
+      }
       byMethod.set(method, matching);
       return matching;
     };
@@ -2898,24 +2920,40 @@ export class ClassDynamicDispatch {
           });
           changed = true;
         }
-      for (const plan of this.propertyReceivers(lowerer, true)) {
+      // Only the receivers that declare or hold the name, and the rooted
+      // ones, can pass the test, except for names it decides on every
+      // receiver. Fields added while bodies lower (the property bag and the
+      // attribute words) have compiler names, which take every receiver.
+      const plans = this.propertyReceivers(lowerer, true);
+      const anyReceiver =
+        !isClassOwnEnumerableFieldName(dispatch.name) ||
+        dispatch.name === "constructor" ||
+        dispatch.name === "stack";
+      const skips = (plan: PropertyReceiver): boolean =>
+        !isClassOwnEnumerableFieldName(dispatch.name) ||
+        (!(plan.info.builtinStream !== undefined && streamProperty(dispatch.name)) &&
+          !eventTargetInheritedMember(plan.info, dispatch.name) &&
+          !dateInheritedMember(lowerer, plan.info, dispatch.name) &&
+          !findMethodOn(lowerer, plan.info, dispatch.name) &&
+          !findGenericMethodOn(lowerer, plan.info, dispatch.name) &&
+          dispatch.name !== "constructor" &&
+          !plan.info.fields.has(dispatch.name) &&
+          !(dispatch.name === "stack" && lowerer.isSubclassOf(plan.info.def.name, "%Error")) &&
+          !findMethodOn(lowerer, plan.info, `get:${dispatch.name}`) &&
+          !findMethodOn(lowerer, plan.info, `set:${dispatch.name}`));
+      const selected = anyReceiver ? plans : receiversFor(plans, dispatch.name, "members");
+      if (
+        CHECK_CANDIDATES &&
+        plans.some(
+          (plan) => !dispatch.classes.has(plan.key) && !skips(plan) && !selected.includes(plan),
+        )
+      )
+        throw new InternalCompilerError(`indexed receivers for ${dispatch.name} differ`);
+      for (const plan of selected) {
         const { info } = plan;
         // Classes answered in an earlier pass skip the member lookups.
         if (dispatch.classes.has(plan.key)) continue;
-        if (
-          !isClassOwnEnumerableFieldName(dispatch.name) ||
-          (!(info.builtinStream !== undefined && streamProperty(dispatch.name)) &&
-            !eventTargetInheritedMember(info, dispatch.name) &&
-            !dateInheritedMember(lowerer, info, dispatch.name) &&
-            !findMethodOn(lowerer, info, dispatch.name) &&
-            !findGenericMethodOn(lowerer, info, dispatch.name) &&
-            dispatch.name !== "constructor" &&
-            !info.fields.has(dispatch.name) &&
-            !(dispatch.name === "stack" && lowerer.isSubclassOf(info.def.name, "%Error")) &&
-            !findMethodOn(lowerer, info, `get:${dispatch.name}`) &&
-            !findMethodOn(lowerer, info, `set:${dispatch.name}`))
-        )
-          continue;
+        if (skips(plan)) continue;
         dispatch.classes.add(plan.key);
         const loc = dispatch.fn.loc;
         const { receiver, condition } = this.propertyReceiver(plan, loc);

packages/compiler/src/frontend/lowering/class-protocols.ts

@@ -101,6 +101,8 @@ export class ClassProtocols {
     const sites: {
       source: ts.Expression;
       target: () => ts.Type | undefined;
+      /** The node whose contextual type `target` answers. */
+      contextual?: ts.Expression;
       assertion?: true;
     }[] = [];
     /** Expressions whose values are observed as whole objects. */
@@ -122,7 +124,8 @@ export class ClassProtocols {
     const callbackParams: { fn: ts.SignatureDeclaration; index: number; name: ts.Node }[] = [];
     const contextual = (expr: ts.Expression) => () => this.checker.getContextualType(expr);
     const flow = (expr: ts.Expression | undefined): void => {
-      if (expr !== undefined) sites.push({ source: expr, target: contextual(expr) });
+      if (expr !== undefined)
+        sites.push({ source: expr, target: contextual(expr), contextual: expr });
     };
     const write = (target: ts.Expression): void => {
       while (ts.isParenthesizedExpression(target) || ts.isNonNullExpression(target))
@@ -329,7 +332,11 @@ export class ClassProtocols {
         facts.loose.push({ node: looseArguments[i]!, call: looseCalls[i]!, symbols });
     }
     this.facts = facts;
-    const pending: { sourceType: ts.Type; target: () => ts.Type | undefined }[] = [];
+    const pending: {
+      sourceType: ts.Type;
+      target: () => ts.Type | undefined;
+      contextual?: ts.Expression;
+    }[] = [];
     /** Views a value of unknown origin is asserted to and that expose a
      * method of a class the view accepts (see methodViewSources). */
     const methodViews = new Set<ts.Symbol>();
@@ -352,7 +359,11 @@ export class ClassProtocols {
           }
         continue;
       }
-      pending.push({ sourceType, target: site.target });
+      pending.push(
+        site.contextual === undefined
+          ? { sourceType, target: site.target }
+          : { sourceType, target: site.target, contextual: site.contextual },
+      );
     }
     for (const { fn, index, name } of callbackParams) {
       attempt(() => {
@@ -377,6 +388,19 @@ export class ClassProtocols {
     // flows and origins are complete.
     const before = new Set(marked);
     const targets = new Map<number, ts.Type | undefined>();
+    // The fixpoint asks the target of each site whose source carries
+    // identity: one batch asks those of the sites that carry it now, and a
+    // site that starts to as marks grow asks its own.
+    attempt(() =>
+      this.checker.prefetchContextualTypes(
+        pending.flatMap((entry) =>
+          entry.contextual !== undefined &&
+          attempt(() => this.carriesIdentity(entry.sourceType, marked)) === true
+            ? [entry.contextual]
+            : [],
+        ),
+      ),
+    );
     let changed = true;
     while (changed) {
       changed = false;

packages/compiler/src/frontend/lowering/containers/callback-arguments.ts

@@ -53,6 +53,8 @@ export function lowerArrayCallback(
   bindUntyped = false,
   expectedReturn?: IrType,
 ): { fnArg: IrExpr & { type: IrType & { kind: "func" } }; arity: number } {
+  // `xs.map(((x) => x))`: a parenthesized callback is the function itself.
+  while (ts.isParenthesizedExpression(argNode)) argNode = argNode.expression;
   // The ambient `Boolean` as the callback (`flags.every(Boolean)`,
   // `xs.some(Boolean)`, `xs.map(Boolean)`): Boolean(value) answers the
   // ToBoolean of its FIRST argument and ignores the rest, so the callback

packages/compiler/src/frontend/lowering/deferred-module-initializers.test.ts

@@ -159,6 +159,15 @@ test("fills every empty copy with the exact file and span while preserving popul
   for (const untouched of [otherFile, otherStart, otherEnd]) expect(untouched.body).toEqual([]);
 });
 
+test("reports the functions whose placeholders it fills", () => {
+  const { initializers, pending, lowerer } = fixture();
+  const functions = [fn("init", [block(loc)]), fn("use", [read("registry")])];
+  pending.set("registry", [{ loc, lower: () => [value(4)] }]);
+  const filled: IrFunction[] = [];
+  expect(initializers.process(lowerer, functions, (f) => filled.push(f))).toBe(true);
+  expect(filled).toEqual([functions[0]]);
+});
+
 test("an update of the binding demands its initializer", () => {
   const { initializers, pending, lowerer } = fixture();
   const updated = block(loc),

packages/compiler/src/frontend/lowering/deferred-module-initializers.ts

@@ -129,7 +129,14 @@ export class DeferredModuleInitializers {
     return block;
   }
 
-  process(lowerer: Lowerer, functions: readonly IrFunction[]): boolean {
+  /** Materializes the initializers that reached bodies observe. `filled`
+   * receives each function whose body changes inside an unchanged statement
+   * list. */
+  process(
+    lowerer: Lowerer,
+    functions: readonly IrFunction[],
+    filled?: (fn: IrFunction) => void,
+  ): boolean {
     if (this.pending.size === 0) return false;
     // Scans keep only the reads of deferred bindings.
     for (const key of this.pending.keys()) {
@@ -192,7 +199,10 @@ export class DeferredModuleInitializers {
         }
         if (holders.length === 0) continue;
         // These bodies changed inside unchanged statement lists.
-        for (const fn of holders) this.scans.delete(fn);
+        for (const fn of holders) {
+          this.scans.delete(fn);
+          filled?.(fn);
+        }
         // An inserted body can introduce a placeholder needed by another
         // action in this pass. Unattached bodies are not part of the live IR.
         for (const nested of scanStatements(body).placeholders) add(nested, holders);

packages/compiler/src/frontend/lowering/dispatch-sites.test.ts

@@ -0,0 +1,60 @@
+import { expect, test, vi } from "vitest";
+import { DYN, F64, VOID, type IrFunction, type IrStmt, type SrcLoc } from "../../ir/ir.js";
+import * as traversal from "../../ir/traverse.js";
+import { DispatchSites } from "./dispatch-sites.js";
+
+const loc: SrcLoc = { file: "sites.ts", start: 0, end: 1 };
+const keyRead = (key: string): IrStmt => ({
+  kind: "exprStmt",
+  expr: {
+    kind: "dynKeyGet",
+    value: { kind: "varRef", localId: "value", type: DYN, loc },
+    key: { kind: "strLit", value: key, type: DYN, loc },
+    type: DYN,
+    loc,
+  },
+  loc,
+});
+const value = (n: number): IrStmt => ({
+  kind: "exprStmt",
+  expr: { kind: "numLit", value: n, type: F64, loc },
+  loc,
+});
+const fn = (body: IrStmt[]): IrFunction => ({
+  name: "f",
+  body,
+  params: [],
+  locals: [],
+  returnType: VOID,
+  loc,
+});
+
+test("reuses a function's sites while its statement list is unchanged", () => {
+  const sites = new DispatchSites();
+  const f = fn([value(1)]);
+  const walk = vi.spyOn(traversal, "everyStmtList");
+  try {
+    expect(sites.of(f).dispatches).toBe(false);
+    expect(sites.of(f).dispatches).toBe(false);
+    expect(walk).toHaveBeenCalledTimes(1);
+    // A statement added to the same list is found.
+    f.body.push(keyRead("next"));
+    expect(sites.of(f)).toMatchObject({ dispatches: true, generatorSteps: true });
+    // So is a replaced list.
+    f.body = [value(2)];
+    expect(sites.of(f)).toMatchObject({ dispatches: false, generatorSteps: false });
+    expect(walk).toHaveBeenCalledTimes(3);
+  } finally {
+    walk.mockRestore();
+  }
+});
+
+test("scans a body again once a change inside an unchanged list is reported", () => {
+  const sites = new DispatchSites();
+  const placeholder: Extract<IrStmt, { kind: "block" }> = { kind: "block", body: [], loc };
+  const f = fn([placeholder]);
+  expect(sites.of(f).dispatches).toBe(false);
+  placeholder.body.push(keyRead("map"));
+  sites.forget(f);
+  expect(sites.of(f)).toMatchObject({ dispatches: true, runtimeSteps: true });
+});