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Give shared helpers the location of their earliest use (#1740)

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This commit is contained in:
Chris Tate
2026-10-21 22:08:16 -05:00
committed by GitHub
parent e80be9c2e5 d5688d7dc5
commit b0802dccc2
2 changed files with 79 additions and 23 deletions
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packages/compiler/src/frontend/lowering/lowerer.ts
+78 -22
View File
@@ -36,7 +36,8 @@ import {
import { identityPreservingWidening } from "./coercions/identity.js";
import { scanDivergences } from "./divergences.js";
import { applyKeyOrderWitnesses, KeyOrderNotes } from "./key-order-witness.js";
import { observeRecordLiteralRebuilds } from "../../ir/traverse.js";
import { exprFunctionReference } from "../../ir/function-references.js";
import { everyStmtList, observeRecordLiteralRebuilds } from "../../ir/traverse.js";
import { checkedClassAssertion } from "./class-assertions.js";
import { narrowStoredClassValue, narrowGenericClassValue } from "./class-unions.js";
import {
@@ -3266,11 +3267,13 @@ export class Lowerer {
if (typeof helper === "string") this.sharedHelperNames.add(helper);
else this.sharedHelpers.add(helper);
}
/** Gives each shared helper the location of the entry file's start: the
* helpers marked by shareHelper, and those interned by key in the helper
* tables. */
private settleSharedHelperLocations(): void {
const loc: SrcLoc = { file: this.entry.fileName, start: 0, end: 0 };
/** Gives each shared helper (those marked by shareHelper, and those
* interned by key in the helper tables) one location for all its nodes:
* the earliest site in `functions` that uses it, by file and position, so
* reports such as --explain-dynamic point at a use whatever order bodies
* lowered in. A helper used only by other shared helpers takes their
* location; one with no use takes the entry file's start. */
private settleSharedHelperLocations(functions: readonly IrFunction[]): void {
const interned = new Set<string>([...this.sharedHelperNames, ...this.classMethodValueHelpers]);
for (const table of [
this.equalityHelpers,
@@ -3293,21 +3296,68 @@ export class Lowerer {
for (const name of table.values()) interned.add(name);
for (const fn of [...this.liftedFns, ...this.implicitFns])
if (interned.has(fn.name)) this.sharedHelpers.add(fn);
const seen = new Set<object>();
const visit = (node: unknown): void => {
if (typeof node !== "object" || node === null || seen.has(node)) return;
seen.add(node);
if (Array.isArray(node)) {
for (const item of node) visit(item);
return;
if (this.sharedHelpers.size === 0) return;
const shared = new Map([...this.sharedHelpers].map((fn) => [fn.name, fn]));
const earlier = (left: SrcLoc, right: SrcLoc): boolean =>
left.file < right.file || (left.file === right.file && left.start < right.start);
// The earliest use of each shared helper outside the shared helpers, and
// which shared helpers each shared helper uses.
const uses = new Map<string, SrcLoc>();
const usedBy = new Map<string, Set<string>>();
for (const fn of functions) {
const inShared = shared.has(fn.name) ? fn.name : undefined;
everyStmtList(fn.body, {
stmt: () => true,
expr: (expr) => {
const name = expr.kind === "call" ? expr.callee : exprFunctionReference(expr);
if (name === undefined || name === inShared || !shared.has(name)) return true;
if (inShared !== undefined) {
let users = usedBy.get(name);
if (users === undefined) usedBy.set(name, (users = new Set()));
users.add(inShared);
} else {
const current = uses.get(name);
if (current === undefined || earlier(expr.loc, current)) uses.set(name, expr.loc);
}
return true;
},
});
}
// Helpers reached only through other shared helpers take the earliest
// location among those, to a fixed point.
for (let changed = true; changed;) {
changed = false;
for (const [name, users] of usedBy) {
for (const user of users) {
const loc = uses.get(user);
const current = uses.get(name);
if (loc !== undefined && (current === undefined || earlier(loc, current))) {
uses.set(name, loc);
changed = true;
}
}
}
const record = node as Record<string, unknown>;
for (const key of Object.keys(record)) {
if (key === "loc") record[key] = loc;
else if (key !== "type") visit(record[key]);
}
};
for (const fn of this.sharedHelpers) visit(fn);
}
const fallback: SrcLoc = { file: this.entry.fileName, start: 0, end: 0 };
for (const fn of this.sharedHelpers) {
const use = uses.get(fn.name) ?? fallback;
const loc: SrcLoc = { file: use.file, start: use.start, end: use.end };
const seen = new Set<object>();
const visit = (node: unknown): void => {
if (typeof node !== "object" || node === null || seen.has(node)) return;
seen.add(node);
if (Array.isArray(node)) {
for (const item of node) visit(item);
return;
}
const record = node as Record<string, unknown>;
for (const key of Object.keys(record)) {
if (key === "loc") record[key] = loc;
else if (key !== "type") visit(record[key]);
}
};
visit(fn);
}
}
/** The first lifted function named `name`, the one
* `liftedFns.find((fn) => fn.name === name)` returns. */
@@ -7401,7 +7451,7 @@ export class Lowerer {
// Lambdas lifted while lowering any of the above (plus synthetic
// array-HOF loop functions, which ride the same list), and the
// implicit-any instances lowered eagerly at their first call sites.
this.settleSharedHelperLocations();
this.settleSharedHelperLocations([...functions, ...this.liftedFns, ...this.implicitFns]);
functions.push(...this.liftedFns);
functions.push(...this.implicitFns);
functions.push(...runtimeClassConstructs(this, functions));
@@ -8116,7 +8166,13 @@ export class Lowerer {
]);
observeRecordLiteralRebuilds(null);
for (const finalize of this.shapeOrderHelperFinalizers) finalize();
this.settleSharedHelperLocations();
this.settleSharedHelperLocations([
...orderedUnits,
...initFunctions,
...instanceFunctions,
...this.liftedFns,
...this.implicitFns,
]);
// Lifted and implicit functions are created in lowering order; they
// are assembled by name.
const functions = [
tests/harness/__snapshots__/coverage-explain-dynamic.txt
+1 -1
View File
@@ -1,8 +1,8 @@
dynamic tier (tier assignment, report-only; --tier=auto)
4 functions already operate on dynamic values (1 statement)
readName tests/coverage-fixtures/tier-demotions.ts:15:1: %dyn.error.stringConstructor at tests/coverage-fixtures/tier-demotions.ts:17:10
%dyn.error.stringConstructor.0 tests/coverage-fixtures/tier-demotions.ts:17:10: dynCall at tests/coverage-fixtures/tier-demotions.ts:17:10
%dyn.class.property.0 tests/coverage-fixtures/tier-demotions.ts:17:17: %dyn.class.readPropertiesOrEmpty at tests/coverage-fixtures/tier-demotions.ts:17:17
%dyn.error.stringConstructor.0 tests/coverage-fixtures/tier-demotions.ts:17:10: dynCall at tests/coverage-fixtures/tier-demotions.ts:17:10
%method.value:%%Error.toString tests/coverage-fixtures/tier-demotions.ts:17:10: dyn.this at tests/coverage-fixtures/tier-demotions.ts:17:10
2 demotion requests (refusals and fences the dynamic tier would replace)