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Reland of [compiler] Make feedback vector cope with flag changes. (patchset #1 id:1 of https://codereview.chromium.org/1876103002/ )

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Reason for revert:
Did not fail on another roll including this CL ..

Original issue's description:
> Revert of [compiler] Make feedback vector cope with flag changes. (patchset #1 id:1 of https://codereview.chromium.org/1869693003/ )
>
> Reason for revert:
> Blocks current roll: https://codereview.chromium.org/1876713002/ according to bisect: https://codereview.chromium.org/1872353002/#ps80001
>
> Original issue's description:
> > [compiler] Make feedback vector cope with flag changes.
> >
> > This fixes corner cases where the layout of feedback vectors baked into
> > the snapshot is different from the expected layout, depending on some
> > runtime flags. We make sure the feedback vector is regenereated for
> > functions that are not compiled. Flag changes of this kind are only
> > allowed when code is not serialized.
> >
> > An alternative solution would be to not serialize the feedback vector
> > for such cases in the first place. That solution however would have a
> > higher overhead, as it would required the serializer to be able to
> > recognize feedback vectors while generating a snapshot.
> >
> > R=mvstanton@chromium.org
> > TEST=mjsunit/regress/regress-crbug-600995
> > BUG=chromium:600995
> > LOG=n
> >
> > Committed: https://crrev.com/460bff5fb6af2bd79e610f89afdf6da9dba3cf0c
> > Cr-Commit-Position: refs/heads/master@{#35339}
>
> TBR=mvstanton@chromium.org,mstarzinger@chromium.org
>
> BUG=chromium:600995
> LOG=N
> NOTRY=true
>
> Committed: https://crrev.com/78049e9c4837f053575d6c71e53ae12fec99f1aa
> Cr-Commit-Position: refs/heads/master@{#35392}

TBR=mvstanton@chromium.org,mstarzinger@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:600995

Review URL: https://codereview.chromium.org/1876973002

Cr-Commit-Position: refs/heads/master@{#35398}
This commit is contained in:
hablich 2016-04-11 11:56:25 -07:00 committed by Commit bot
parent 58429beb7b
commit b88d048adf
2 changed files with 15 additions and 3 deletions
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8
src/compiler.cc
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@ -524,9 +524,11 @@ void EnsureFeedbackVector(CompilationInfo* info) {
if (!info->has_shared_info()) return;
// If no type feedback vector exists, we create one now. At this point the
// AstNumbering pass has already run. Note that we should reuse any existing
// feedback vector rather than creating a new one.
if (info->shared_info()->feedback_vector()->is_empty()) {
// AstNumbering pass has already run. Note the snapshot can contain outdated
// vectors for a different configuration, hence we also recreate a new vector
// when the function is not compiled (i.e. no code was serialized).
if (info->shared_info()->feedback_vector()->is_empty() ||
!info->shared_info()->is_compiled()) {
Handle<TypeFeedbackMetadata> feedback_metadata = TypeFeedbackMetadata::New(
info->isolate(), info->literal()->feedback_vector_spec());
Handle<TypeFeedbackVector> feedback_vector =

10
test/mjsunit/regress/regress-crbug-600995.js Normal file
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@ -0,0 +1,10 @@
// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Flags: --noharmony-iterator-close
// The {Set} function will produce a different type feedback vector layout
// depending on whether Harmony iterator finalization is enabled or not.
new Set();