918fe04351
PR-URL: https://github.com/nodejs/node/pull/58070 Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com> Reviewed-By: Darshan Sen <raisinten@gmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
57 lines
1.9 KiB
JavaScript
57 lines
1.9 KiB
JavaScript
// Copyright 2020 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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//
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// Flags: --allow-natives-syntax --expose-gc
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// Helper to convert setTimeout into an awaitable promise.
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function asyncTimeout(timeout) {
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return new Promise((resolve, reject)=>{
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setTimeout(resolve, timeout);
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})
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}
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function Foo() {}
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function getX(o) { return o.x; }
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(async function() {
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let o = new Foo();
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// Transition o:Foo to o:Foo{x}. This transition is important, as the o:Foo
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// map is the initial map for the Foo constructor, and so is strongly held by
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// it. We want o to be the only strong holder of its map.
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o.x = 42;
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%CompleteInobjectSlackTracking(new Foo());
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// Warm up 'getX' with 'Foo{x}' feedback for its o.x access.
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%PrepareFunctionForOptimization(getX);
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assertEquals(getX(o), 42);
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assertEquals(getX(o), 42);
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// Clear out 'o', which is the only strong holder of the Foo{x} map.
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let weak_o = new WeakRef(o);
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o = null;
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// Tick the message loop so that the weak ref can be collected.
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await asyncTimeout(0);
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// Collect the old 'o', which will also collect the 'Foo{x}' map.
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// We need to invoke GC asynchronously and wait for it to finish, so that
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// it doesn't need to scan the stack. Otherwise, some objects may not be
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// reclaimed because of conservative stack scanning and the test may not
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// work as intended.
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await gc({ type: 'major', execution: 'async' });
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// Make sure the old 'o' was collected.
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assertEquals(undefined, weak_o.deref());
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// Optimize the function with the current monomorphic 'Foo{x}' map o.x access,
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// where the 'Foo{x}' map is dead and therefore the map set is empty. Then,
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// create a new 'Foo{x}' object and pass that through. This compilation and
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// o.x access should still succeed despite the dead map.
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%OptimizeFunctionOnNextCall(getX);
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o = new Foo();
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o.x = 42;
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assertEquals(getX(o), 42);
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})();
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