A getter or proxy trap that runs during a trusted build outside any
visit session now runs with the build's state set aside, as inside a
session. A conversion the getter starts, such as a recursive union
that opens and ends its own session, no longer clears the mark that
keeps the rest of the outer build from trusting its earlier match.
Buffer.from(text, "base64" | "base64url") decoded each four-character
group with four lookups and a sign test, then stored its three bytes one
at a time. The decoder now first takes complete groups two at a time:
each character's value comes from a table that holds it already shifted
into place within its group's 24 bits, a single bit test covers all
eight characters, and each group's three bytes go out in one four-byte
store whose last byte the next store overwrites. A group with any other
character (padding, whitespace, an invalid character) takes the
previous path, and the two-group step resumes after it, so line-wrapped
text keeps most of the gain. The destination already holds two spare
bytes, which cover the extra store byte.
readline split redirected input byte by byte, twice per chunk (once to
find whether the chunk ends a line, once to split it). Before splitting
it copied each chunk out of its Buffer and into a scratch buffer, decoded
it into a new string, and copied the unfinished line and the whole chunk
into a joined buffer. Now:
- one scan per chunk: memchr for a CR once, then LF to LF with memchr
when the chunk has none, and the LF, CR and CRLF split otherwise;
- the unfinished line joins only the first line of the chunk;
- an ASCII chunk with no partial UTF-8 sequence held from the previous
one is split where it is, and a chunk that is not shared memory is
read from its own storage. Lines are still copied into their strings
before the first is delivered.
Buffer.from(string, 'latin1' | 'ascii') encoded character by character;
an ASCII prefix, all of an ASCII string, is now copied with memcpy.
Line events, their order and the CRLF delay are unchanged. Corpus 8344
covers lines joined across chunks, a line longer than a chunk, empty
lines, mixed line endings and UTF-8 split across chunks. The new
line-reader workload reads a 67 MB log through readline over a file
stream.
`JSON.parse(text) as T` for a discriminated union of records took the
checked-dynamic route: it parsed the text into a dynamic tree, matched
and copied that tree into records, then freed it. The one-pass schema
parser now builds these unions directly, as record members, array
elements and whole documents. For an object, a shallow scan of its
members finds the discriminant's value, which selects the one record arm
that holds that literal, and the object is parsed with that arm's
schema. An object with a missing, non-string or unknown discriminant, or
any member the arm rejects, declines, and the checked route then gives
the result or the error as before.
The compiler admits unions whose record arms each name their string
literals, every literal naming one arm, plus null and undefined arms.
A read site's cache only remembered properties it found on the receiver
or its first prototype. Reads of properties an object lacks, which
validation libraries make constantly (zod reads ctx.skipChecks,
payload.memo, x.aborted and _zod.optin on every check), walked the whole
shape chain and then repeated the lookup on the generic path every time:
7.9 million such reads in one zod benchmark run.
- Read sites call a new probe, scr_js_get_probe, that answers undefined
for a key the receiver and its chain of plain shaped objects (at most
one prototype, ending in the default prototype) lack, and caches that
answer. The entry holds while the receiver's shape, its prototype link,
and that prototype's shape are unchanged. Its tag and placeholder
holder make the inline entry-0 test in compiled code miss, so the
answer always comes from the probe. Method reads keep
scr_js_load_probe, so a missing method still reaches the slow path and
its "is not a function" error. Names of Object.prototype members are
never cached as absent.
- Receivers of one shape with different prototypes (zod's internals
objects) each keep an entry instead of replacing one another.
- A site whose four-way record is full consults a per-thread table keyed
by shape and key before walking shapes, and fills it.
The native compiler now starts with the cycle collector's nursery trigger
at 1024 new candidates instead of 256. scr_cyc_set_nursery_threshold sets
the trigger that SCR_CYCLE_THRESHOLD sets, on the pattern of
scr_cyc_set_growth_cap; the environment variable still takes precedence.
The compiler sets it from a constructor in its host object, before its
modules initialize. Set from main, the trigger leaves the build's
collection work where it was: the cost depends on the collector's first
passes. Programs keep the default trigger.
A cold tsc-ts build takes 4% less wall time (12 paired runs) and its peak
RSS goes from 1.41 GB to 1.31 GB. The program's IR is unchanged.
A typed array such as a number[] reaches untyped code as a capsule of the
native array. A keyed read `xs[i]` there missed the inline cache, which
answers only dyn arrays, and went to the member helper, which converted
the index to a string; the capsule's key lookup then parsed the string
back into a number for every element.
Keyed sites now read an element of a native number[] capsule in place
when the index is an integer below the array's hole-free prefix, and
`length` sites read the native array's length. Other capsule elements
(holes, out-of-range and fractional indices, arrays of other element
types) are answered by the keyed probe through scr_dyn_index_get without
forming the key, or by the helper as before.
Node's afterWriteTick sets afterWriteTickInfo to null before it runs the
callbacks, whichever tick it is. The runtime cleared the queued batch
only when the running tick was that batch, so a write made from an
earlier tick's callback joined a later queued tick with the same
callback and completed ahead of nextTicks queued between them. Any
afterWrite tick now closes the batch, and such a write queues its own.
Node's onwrite queues one afterWrite nextTick for a synchronous write
completion and lets later synchronous completions with the same callback
join it (afterWriteTickInfo.count); writes without a callback share one.
The step then checks 'drain' once, calls the callback once per write and
runs finishMaybe once. The runtime queued a stream tick and a nextTick
entry per write, which ran the callbacks of later writes after nextTicks
queued between them. The queued afterWrite tick now counts the writes
that join it, as Node's does.
Every read or write of a symbol-keyed property on a checked-dynamic value
formatted the symbol's address into a new string to find its storage key,
and every conversion of a symbol to a checked value allocated a new box.
Programs that key hot properties by symbols, such as Effect's type ids
checked on each combinator, spent a large share of their time there.
The storage key is a function of the address, so a 256-entry per-thread
cache by address now returns the existing string, released at exit. A
symbol also keeps a weak pointer to its live box: conversions share it,
and the box clears the pointer when it is freed.
A JavaScript class whose instances track which fields they have copies
the instance's property bag into its view first, attributes included,
and then wrote each symbol-keyed field with an ordinary assignment. Once
the instance was frozen, its symbol entry was read-only and the copy
non-extensible, so any later reflection that rebuilt the view
(Object.isFrozen, a property read) threw "Cannot assign to a read only
symbol property".
String-keyed fields already use scr_dyn_obj_set_field, which replaces a
field's value whatever the attributes copied into the view. The new
scr_dyn_symbol_field_set does the same for symbol-keyed fields, and the
view uses it when it copies the bag or carries integrity attributes.
Each deferred stream step (afterWrite, emitReadable, resume and the
others) queued a ScrStreamTick and a process.nextTick entry, both from
libc calloc and free. They now come from the runtime's small-block
allocator, as do the nextTick entries scheduled through
scr_next_tick and scr_process_write_callback.
The stream unit emitted each event with a newly allocated name string.
The names it emits ("data", "end", "drain", "finish" and the others)
are now immortal static strings, so an emit allocates no name.
- A function whose whole body is `return [a, b]` or `return { a, b }`,
with number, boolean or string fields, is now inlined where its result
is only destructured (`const [head, tail] = split(text, at)`). The
parameters are declared from the arguments, then each field straight
into its destructured binding, in the literal's order; an unread field
still evaluates into a binding of its own. No record is built, and a
slice field read only through its length or char codes becomes a
scalar slice that copies nothing. Arguments may own their value, but
as for numeric records nothing inside an argument may hold a
temporary of its own.
- A scalar slice of a proven-ASCII string computes its range inline:
the bounds clamp over the byte length exactly as scr_str_slice_range
does, and no boundary can split a surrogate pair. Other strings keep
the runtime call, which gains the same ASCII fast path.
- value-records' tuples section, `[head, tail] = split(...)` read only
through lengths, goes from two heap slices per step to none.
A server with requestCert read a runtime rejectUnauthorized through
JavaScript truthiness, so null, 0 or "" let clients without a valid
certificate through, and tls.connect read it the same way. Both now treat
only false as off, as Node's options.rejectUnauthorized !== false does; a
standalone TLSSocket keeps Node's truthiness test.
An X509Certificate's methods read the record's raw Buffer, so writing
into the Buffer that certificate.raw answers changed later checks, the
PEM and the public key. The record now keeps a hidden copy of the DER
that the methods read, and raw stays the same Buffer at every read, as
in Node.
`s.unshift("e9", "hex")` on a native stream held as an untyped value
dropped the encoding argument and put the string's UTF-8 bytes at the
front. A byte-mode stream now takes a string chunk with an encoding as the
bytes Buffer.from(chunk, encoding) holds, as Node's
readableAddChunkUnshift converts it, and an unknown encoding throws
ERR_UNKNOWN_ENCODING. Object-mode streams keep the string as the entry.
fs.read and fs.readSync with arguments the compiler could not type
validated the length with `length |= 0` and then converted it again for
the read. A length with a valueOf method ran valueOf twice, and the read
used the second result. Node converts the length once.
scr_fs_read_validate now returns the converted length, and both reads
use it.
- The assert comparison methods read as function values (equal,
strictEqual, deepEqual, partialDeepStrictEqual and their negations)
throw Node's ERR_MISSING_ARGS TypeError, `The "actual" and "expected"
arguments must be specified`, when called with fewer than two
arguments, where `[assert.equal][0]()` passed.
- Untyped `instanceof Object` starts at the value's prototype, so
Object.prototype itself, whose prototype is null, is not an Object.
- Untyped `instanceof Function` follows the whole prototype chain through
objects and functions: an object whose prototype is a function, or a
function whose prototype was set to such an object, is a Function.
A union without recursion builds its matched arm without a visit
session, so its getters and proxy traps ran without marking the
conversion. A nested union then took its arm from the earlier match,
even when the getter returned another value. A getter or trap that runs
during a trusted build outside a session now marks it as well, and the
outermost trusted build clears the mark when it ends.
uintptr_t is 32 bits on wasm32, where the weak-collection hashes shifted it by 33 and 56 bits. The hashes now widen keys, owners and kinds to uint64_t before mixing; 64-bit targets compute the same values as before.
scr_unwind.c is linked into every Linux executable, and its references
to _Unwind_ForcedUnwind and _Unwind_GetCFA pulled the unwinder out of
libgcc_eh (or Zig's libunwind) even for programs that never raise, which
grew a static hello world past its size ceiling. The references are now
weak: programs that raise reference the personality routine from their
landing pads, and its unit links the unwinder in.
Chris Tate