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[runtime] MigrateFastToFast: fix check for unboxed inobject doubles

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After the recent fast-property deletion changes, there can be a
non-empty out-of-object backing store (that previously held properties)
even though the next double property will be stored in-object.

BUG=chromium:718779

Review-Url: https://codereview.chromium.org/2861093004
Cr-Commit-Position: refs/heads/master@{#45146}
This commit is contained in:
jkummerow 2017-05-05 15:23:04 -07:00 committed by Commit bot
parent c3f0e2a5b0
commit ceba405f28
2 changed files with 23 additions and 3 deletions
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5
src/objects.cc
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@ -3473,9 +3473,8 @@ void MigrateFastToFast(Handle<JSObject> object, Handle<Map> new_map) {
// which there is still space, and which does not require a mutable double
// box (an out-of-object double).
if (details.location() == kDescriptor ||
(have_space &&
((FLAG_unbox_double_fields && object->properties()->length() == 0) ||
!details.representation().IsDouble()))) {
(have_space && ((FLAG_unbox_double_fields && target_index < 0) ||
!details.representation().IsDouble()))) {
object->synchronized_set_map(*new_map);
return;
}

21
test/mjsunit/regress/regress-crbug-718779.js Normal file
View File

@ -0,0 +1,21 @@
// Copyright 2017 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.
function __f_1()
{
__v_1.p2 = 2147483648;
__v_1.p3 = 3;
__v_1.p4 = 4;
__v_1.p5 = 2147483648;
__v_1.p6 = 6;
}
function __f_2()
{
delete __v_1.p6;
delete __v_1.p5;
}
var __v_1 = { };
__f_1(__v_1);
__f_2(__v_1);
__f_1(__v_1);