c041296189
This introduces dedicated builtins - FulfillPromise, - RejectPromise, and - ResolvePromise, which perform the corresponding operations from the language specification, and removes the redundant entry points and the excessive inlining of these operations into other builtins. We also add the same logic on the C++ side, so that we don't need to go into JavaScript land when resolving/rejecting from the API. The C++ side has a complete implementation, including full support for the debugger and the current PromiseHook machinery. This is to avoid constantly crossing the boundary for those cases, and to also simplify the CSA side (and soon the TurboFan side), where we only do the fast-path and bail out to the runtime for the general handling. On top of this we introduce %_RejectPromise and %_ResolvePromise, which are entry points used by the bytecode and parser desugarings for async functions, and also used by the V8 Extras API. Thanks to this we can uniformly optimize these in TurboFan, where we have corresponding operators JSRejectPromise and JSResolvePromise, which currently just call into the builtins, but middle-term can be further optimized, i.e. to skip the "then" lookup for JSResolvePromise when we know something about the resolution. In TurboFan we can also already inline the default PromiseCapability [[Reject]] and [[Resolve]] functions, although this is not as effective as it can be right now, until we have inlining support for the Promise constructor (being worked on by petermarshall@ right now) and/or SFI based CALL_IC feedback. Overall this change is meant as a refactoring without significant performance impact anywhere; it seems to improve performance of simple async functions a bit, but otherwise is neutral. Bug: v8:7253 Change-Id: Id0b979f9b2843560e38cd8df4b02627dad4b6d8c Reviewed-on: https://chromium-review.googlesource.com/911632 Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org> Reviewed-by: Georg Neis <neis@chromium.org> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org> Cr-Commit-Position: refs/heads/master@{#51260}
28 lines
686 B
JavaScript
28 lines
686 B
JavaScript
// Copyright 2018 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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var resolve, value;
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(new Promise(r => resolve = r)).then(v => value = v);
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function foo() { resolve(1); }
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foo();
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foo();
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%OptimizeFunctionOnNextCall(foo);
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foo();
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setTimeout(_ => assertEquals(1, value));
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})();
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(function() {
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var reject, value;
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(new Promise((_, r) => reject = r)).catch(v => value = v);
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function foo() { reject(1); }
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foo();
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foo();
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%OptimizeFunctionOnNextCall(foo);
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foo();
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setTimeout(_ => assertEquals(1, value));
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})();
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