1da91b8389
This relands commit e71b802279.
This can now back in as the fix for chromium:787301 had enough time to
be tested in Canary.
Original change's description:
> [deoptimizer] Staged materialization of objects.
>
> The existing object materialization in the deoptimizer has the following problems:
>
> - Objects do not necessarily verify during materialization (because during the
> depth first walk we might have inconsistent objects).
>
> - Stack can overflow (because we just materialize using recursive calls).
>
> - We generalize object fields.
>
>
> This CL re-implements the materialization algorithm to solve this problem. The
> new implementation creates the objects in two steps:
>
> 1. We allocate space for all the objects. In general, we allocate ByteArrays
> of the right size. For leaf objects that cannot participate in cycles,
> we build and initialize the materialized objects completely.
>
> For JS objects, we insert markers into the byte array at the positions
> where unboxed doubles are expected.
>
> 2. We initialize all the objects with the proper field values and change the
> map from the ByteArray map to the correct map. This requires some sync
> with the concurrent marker (Heap::NotifyObjectLayoutChange).
>
> When initializing the JS object fields, we make sure that we respect
> the unboxed double marker.
>
> Bug: chromium:770106, v8:3836
> Change-Id: I1ec466a9d19db9538df4ba915516d4c3ca825632
> Reviewed-on: https://chromium-review.googlesource.com/777559
> Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49821}
Bug: chromium:770106, v8:3836
Change-Id: Ied6c4e0fbae52713e55ae6dc13794a7521dbb8a5
Reviewed-on: https://chromium-review.googlesource.com/817745
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49982}
23 lines
496 B
JavaScript
23 lines
496 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 C() {}
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%CompleteInobjectSlackTracking(new C());
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function f() {
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// Create a non-escaping object.
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var o = new C();
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// Add an out-of-object double property.
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o.x = 0.5;
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%DeoptimizeNow();
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return o.x + 0.25;
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}
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f();
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f();
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%OptimizeFunctionOnNextCall(f);
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assertEquals(0.75, f());
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