d2ea316f2a
Previously we had a special, unshared map on the native context that was
used for results of builtin iterators, which was different from the map
that is created from an object literal like `{value, done}`. This not
only leads to unnecessary polymorphism, but also makes it impossible
for user defined iterators to take the fast-paths that we have in
various places (i.e. in collections or promises).
With this change we now properly share the map for `{value, done}` and
use that for the builtin iterator result objects, as well as the
fast-paths.
Drive-by-fix: Remove the restrictions on map caching and transition
caching during bootstrapping. This no longer makes sense.
Bug: v8:9114, v8:9243
Change-Id: I19eb9071f7ec0ed58f8a6f87eed781bc790174b7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1609794
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61488}
27 lines
869 B
JavaScript
27 lines
869 B
JavaScript
// Copyright 2019 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: --allow-natives-syntax
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// The special IterResultObject map that builtins use should be the same
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// as the one produced by the `{value, done}` object literal.
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const user = {value:undefined, done:true};
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// Array iterator.
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const arrayResult = (new Array())[Symbol.iterator]().next();
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assertTrue(%HaveSameMap(user, arrayResult));
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// Map iterator.
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const mapResult = (new Map())[Symbol.iterator]().next();
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assertTrue(%HaveSameMap(user, mapResult));
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// Set iterator.
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const setResult = (new Set())[Symbol.iterator]().next();
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assertTrue(%HaveSameMap(user, setResult));
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// Generator.
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function* generator() {}
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const generatorResult = generator().next();
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assertTrue(%HaveSameMap(user, setResult));
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