Leszek Swirski
636546215e
Implement an experimental bytecode `ArrayDestructure <outputs> <count>` guarded by the `--array-destructure-bytecode` flag to optimize destructuring patterns of the form `let [x, y, ...] = iterable;`. Key highlights across execution tiers: - Builtin: Adds `Builtin::kArrayDestructure` builtin which returns N iterated elements out of an iterator in a FixedArray, with a fast path for JSArray iteration. - Ignition: Adds `ArrayDestructure` bytecode handler which calls the `Builtin::kArrayDestructure` and copies the result to a RegList. The values from that RegList are then written out into the target bytecode registers as needed, handling destructuring holes and default values. - Sparkplug: Calls the `Builtin::kArrayDestructure` builtin and emits direct FixedArray reads for the multi-register output. - Maglev: Adds IR node `JSArrayDestructure` and graph builder reduction (`VisitArrayDestructure`), which for now also calls the `Builtin::kArrayDestructure` builtin with direct inline FixedArray loads that populate the abstract interpreter state. Since the builtin can lazy deopt the Maglev code, we have a lazy deopt continuation that populates the RegList (`kArrayDestructureLazyDeoptContinuation`). - TurboFan: Adds operator `JSArrayDestructure` in `JSOperatorBuilder` which has N outputs that are read through Projections, and generic lowering in `JSGenericLowering::LowerJSArrayDestructure` which for now does effectively the same thing as Maglev, turning the Projections into FixedArray reads and adding the lazy deopt continuation. TAG=agy Conversation-Id: 7fc7c031-68c6-4ddc-bdff-6ce4e63adc59 Change-Id: I1bbe22f3cab2c147a4d6519cb88052ca8176c4cd Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7994076 Commit-Queue: Darius Mercadier <dmercadier@chromium.org> Auto-Submit: Leszek Swirski <leszeks@chromium.org> Reviewed-by: Darius Mercadier <dmercadier@chromium.org> Commit-Queue: Leszek Swirski <leszeks@chromium.org> Cr-Commit-Position: refs/heads/main@{#108353}
27 lines
481 B
JavaScript
27 lines
481 B
JavaScript
// Copyright 2026 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Flags: --array-destructure-bytecode
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let log = [];
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function* gen() {
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log.push("gen 1");
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yield 1;
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log.push("gen 2");
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yield 2;
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}
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let obj = {
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set foo(val) {
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log.push("set foo: " + val);
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}
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};
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let y;
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[obj.foo, y] = gen();
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assertEquals(["gen 1", "set foo: 1", "gen 2"], log);
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assertEquals(2, y);
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