163b5d705e
This reverts commit bf4cc9ee15.
Reason for revert: Breaks windows with msvc and linux with gcc
https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20msvc/builds/841
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20gcc%204.8/builds/17265
Original change's description:
> [esnext] load `iterator.next` only once at beginning of iteration
>
> https://github.com/tc39/ecma262/pull/988 gained concensus during the
> september 2017 TC39 meetings. This moves the load of the "next" method
> to the very beginning of the iteration protocol, rather than during
> each iteration step.
>
> This impacts:
>
> - yield*
> - for-of loops
> - spread arguments
> - array spreads
>
> In the v8 implementation, this also affects async iteration versions of
> these things (the sole exception being the Async-From-Sync iterator,
> which requires a few more changes to work with this, likely done in a
> followup patch).
>
> This change introduces a new AST node, ResolvedProperty, which can be used
> as a callee by Call nodes to produce the same bytecode as Property calls,
> without observably re-loading the property. This is used in several
> AST-desugarings involving the iteration protocol.
>
> BUG=v8:6861, v8:5699
> R=rmcilroy@chromium.org, neis@chromium.org, adamk@chromium.org
>
> Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
> Change-Id: Ib81106a0182687fc5efea0bc32302ad06376773b
> Reviewed-on: https://chromium-review.googlesource.com/687997
> Commit-Queue: Caitlin Potter <caitp@igalia.com>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50452}
TBR=rmcilroy@chromium.org,adamk@chromium.org,neis@chromium.org,caitp@igalia.com,caitp@chromium.org
Change-Id: I1797c0d596dfd6850d6f0f505f591a7a990dd1f1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6861, v8:5699
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/857616
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50454}
43 lines
822 B
JavaScript
43 lines
822 B
JavaScript
// Copyright 2017 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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(function modifyNext() {
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'use strict';
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var a = [];
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var ai = a[Symbol.iterator]();
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var original_next = ai.__proto__['next'];
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function maxWithZero(...args) {
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return Math.max(0, ...args);
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}
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function testMax(x, y) {
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return maxWithZero(x, y);
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}
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testMax(1, 2);
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testMax(1, 2);
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%OptimizeFunctionOnNextCall(testMax);
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var r = testMax(1, 2);
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assertEquals(2, r);
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var called = 0;
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Object.defineProperty(ai.__proto__, 'next', {
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get: function() {
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called++;
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return original_next;
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}
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});
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var r2 = testMax(1, 2);
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assertEquals(3, called);
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assertEquals(2, r2);
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})();
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