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Plan record views only where a checked target meets a live capsule source

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Targets come from the closure of checked conversion types and sources from
the closure of types boxed as live capsules; a conversion anywhere else
keeps its copy. Fewer types carry view guards, the compiler's own among
them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Malte Ubl
2026-10-27 06:39:04 -07:00
co-authored by Claude Opus 5.5
parent 7b91c5fe5c
commit ae74868e7a
1 changed files with 37 additions and 25 deletions
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packages/compiler/src/backend/llvm/record-views.ts
+37 -25
View File
@@ -14,8 +14,8 @@
* Only the target types of such conversions carry the words and the
* test. They are found from the IR, before any code is emitted: B is a
* record type a checked conversion can produce (the closure of dynCheck
* targets and of the types live capsules expose) and some other record
* type in the module has all of B's fields. A program without checked
* targets), and some other record type whose values reach untyped code as
* live capsules (the closure of live dynFrom types) has all of B's fields. A program without checked
* conversions has none, so its code is unchanged. */
import {
isDirentShape,
@@ -66,37 +66,49 @@ function covers(source: IrRecordShape, target: IrRecordShape): boolean {
export function planRecordViews(mod: IrModule, options: ViewOptions): RecordViews {
const shapes = new Map((mod.records ?? []).map((shape) => [shape.id, shape]));
const unions = new Map((mod.unions ?? []).map((union) => [union.id, union]));
const reachable = new Set<string>();
const seen = new Set<string>();
const visit = (t: IrType): void => {
const key = typeKey(t);
if (seen.has(key)) return;
seen.add(key);
switch (t.kind) {
case "record": {
reachable.add(t.shapeId);
for (const field of shapes.get(t.shapeId)?.fields ?? []) visit(field.type);
return;
// Targets: record types a checked conversion produces. Sources: record
// types whose values reach untyped code as live capsules. A view arises
// only where the two meet; elsewhere a conversion keeps its copy.
const closure = (roots: IrType[]): Set<string> => {
const out = new Set<string>();
const seen = new Set<string>();
const visit = (t: IrType): void => {
const key = typeKey(t);
if (seen.has(key)) return;
seen.add(key);
switch (t.kind) {
case "record": {
out.add(t.shapeId);
for (const field of shapes.get(t.shapeId)?.fields ?? []) visit(field.type);
return;
}
case "array":
visit(t.elem);
return;
case "union":
for (const arm of unions.get(t.unionId)?.arms ?? []) visit(arm);
return;
default:
return;
}
case "array":
visit(t.elem);
return;
case "union":
for (const arm of unions.get(t.unionId)?.arms ?? []) visit(arm);
return;
default:
return;
}
};
for (const root of roots) visit(root);
return out;
};
const checked: IrType[] = [];
const boxed: IrType[] = [];
for (const fn of mod.functions)
everyStmtList(fn.body, {
stmt: () => true,
expr: (e) => {
if (e.kind === "dynCheck") visit(e.type);
else if (e.kind === "dynFrom" && e.liveRef === true) visit(e.value.type);
if (e.kind === "dynCheck") checked.push(e.type);
else if (e.kind === "dynFrom" && e.liveRef === true) boxed.push(e.value.type);
return true;
},
});
if (checked.length === 0 || boxed.length === 0) return NO_RECORD_VIEWS;
const reachable = closure(checked);
const live = closure(boxed);
if (reachable.size === 0) return NO_RECORD_VIEWS;
const targets = new Set<string>();
const sources = new Map<string, string[]>();
@@ -106,7 +118,7 @@ export function planRecordViews(mod: IrModule, options: ViewOptions): RecordView
if (options.traced(id) || options.excluded(id)) continue;
const found: string[] = [];
for (const source of shapes.values()) {
if (source.id === id || !reachable.has(source.id) || !plainShape(source)) continue;
if (source.id === id || !live.has(source.id) || !plainShape(source)) continue;
if (covers(source, target)) found.push(source.id);
}
if (found.length === 0) continue;