094435b6b6
This is a reland of e7e512da66
Original change's description:
> [turbofan] Add fast path for single-character String#startsWith()
>
> This CL adds a fast path to String#startsWith(s) if s is a
> single character string.
>
> Bug: v8:8400
> Change-Id: Ibd6a9d1e46d98f41c198d2b579208e25003eedb0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1525362
> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
> Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61504}
Bug: v8:8400
Change-Id: Ic2d60ccb8fdeb51373fcd025a7e970fda0c14d79
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1618342
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61637}
82 lines
2.1 KiB
JavaScript
82 lines
2.1 KiB
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 --opt
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(function() {
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function foo(string) { return string.startsWith('a'); }
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%PrepareFunctionForOptimization(foo);
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assertEquals(false, foo(''));
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assertEquals(true, foo('a'));
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assertEquals(false, foo('ba'));
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assertEquals(true, foo('abc'));
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%OptimizeFunctionOnNextCall(foo);
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assertEquals(false, foo(''));
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assertEquals(true, foo('a'));
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assertEquals(false, foo('ba'));
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assertEquals(true, foo('abc'));
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assertOptimized(foo);
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})();
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(function() {
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function f() { return "abc".startsWith(); }
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%PrepareFunctionForOptimization(f);
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assertEquals(false, f());
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assertEquals(false, f());
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%OptimizeFunctionOnNextCall(f);
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assertEquals(false, f());
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assertOptimized(f);
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})();
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(function() {
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function g(n) { return "abc".startsWith("a", n); }
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%PrepareFunctionForOptimization(g);
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assertEquals(true, g(-1));
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assertEquals(true, g(0));
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assertEquals(false, g(1));
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assertEquals(false, g(2));
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assertEquals(false, g(3));
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assertEquals(false, g(4));
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%OptimizeFunctionOnNextCall(g);
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assertEquals(true, g(-1));
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assertEquals(true, g(0));
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assertEquals(false, g(1));
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assertEquals(false, g(2));
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assertEquals(false, g(3));
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assertEquals(false, g(4));
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assertOptimized(g);
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})();
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(function() {
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function g(n) { return "cba".startsWith("a", n); }
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%PrepareFunctionForOptimization(g);
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assertEquals(false, g(-1));
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assertEquals(false, g(0));
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assertEquals(false, g(1));
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assertEquals(true, g(2));
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assertEquals(false, g(3));
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assertEquals(false, g(4));
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%OptimizeFunctionOnNextCall(g);
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assertEquals(false, g(-1));
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assertEquals(false, g(0));
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assertEquals(false, g(1));
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assertEquals(true, g(2));
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assertEquals(false, g(3));
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assertEquals(false, g(4));
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assertOptimized(g);
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})();
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(function() {
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function f(n) { return "cba".startsWith("a", n); }
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%PrepareFunctionForOptimization(f);
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f();
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f();
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%OptimizeFunctionOnNextCall(f);
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assertEquals(false, f(1073741824));
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})();
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