caeb9004f0
If the array's map is the initial FastHoley array map, and the array prototype chain is undisturbed and empty of elements, then keyed loads can convert the load of a hole to undefined. BUG= Review URL: https://codereview.chromium.org/1100083002 Cr-Commit-Position: refs/heads/master@{#28056}
27 lines
811 B
JavaScript
27 lines
811 B
JavaScript
// Copyright 2015 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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// Flags: --nostress-opt
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// --nostress-opt is specified because the test corrupts the "pristine"
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// array prototype chain by storing an element, and this is tracked
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// per-isolate. A subsequent stress run would send the load generic,
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// and no more deoptimizations of foo would occur.
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function foo(a, i) { return a[i]; }
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var a = ['one', , 'three'];
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foo(a, 0);
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foo(a, 0);
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foo(a, 0);
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%OptimizeFunctionOnNextCall(foo);
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assertEquals(undefined, foo(a, 1));
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assertOptimized(foo);
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// Whereas if we disrupt the prototype chain...
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Array.prototype[1] = 'cow';
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assertEquals('cow', foo(a, 1));
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assertUnoptimized(foo);
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