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Fix setting array length to zero for slow elements.

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R=verwaest@chromium.org
BUG=chromium:146910
TEST=mjsunit/regress/regress-crbug-146910

Review URL: https://codereview.chromium.org/10937026

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12547 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
mstarzinger@chromium.org 2012-09-19 11:52:33 +00:00
parent ab94a69d3d
commit c012afb6d4
2 changed files with 75 additions and 37 deletions
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74
src/elements.cc
View File

@ -1268,7 +1268,30 @@ class DictionaryElementsAccessor
JSArray* array,
Object* length_object,
uint32_t length) {
if (length == 0) {
Heap* heap = array->GetHeap();
int capacity = dict->Capacity();
uint32_t new_length = length;
uint32_t old_length = static_cast<uint32_t>(array->length()->Number());
if (new_length < old_length) {
// Find last non-deletable element in range of elements to be
// deleted and adjust range accordingly.
for (int i = 0; i < capacity; i++) {
Object* key = dict->KeyAt(i);
if (key->IsNumber()) {
uint32_t number = static_cast<uint32_t>(key->Number());
if (new_length <= number && number < old_length) {
PropertyDetails details = dict->DetailsAt(i);
if (details.IsDontDelete()) new_length = number + 1;
}
}
}
if (new_length != length) {
MaybeObject* maybe_object = heap->NumberFromUint32(new_length);
if (!maybe_object->To(&length_object)) return maybe_object;
}
}
if (new_length == 0) {
// If the length of a slow array is reset to zero, we clear
// the array and flush backing storage. This has the added
// benefit that the array returns to fast mode.
@ -1276,45 +1299,22 @@ class DictionaryElementsAccessor
MaybeObject* maybe_obj = array->ResetElements();
if (!maybe_obj->ToObject(&obj)) return maybe_obj;
} else {
uint32_t new_length = length;
uint32_t old_length = static_cast<uint32_t>(array->length()->Number());
if (new_length < old_length) {
// Find last non-deletable element in range of elements to be
// deleted and adjust range accordingly.
Heap* heap = array->GetHeap();
int capacity = dict->Capacity();
for (int i = 0; i < capacity; i++) {
Object* key = dict->KeyAt(i);
if (key->IsNumber()) {
uint32_t number = static_cast<uint32_t>(key->Number());
if (new_length <= number && number < old_length) {
PropertyDetails details = dict->DetailsAt(i);
if (details.IsDontDelete()) new_length = number + 1;
}
// Remove elements that should be deleted.
int removed_entries = 0;
Object* the_hole_value = heap->the_hole_value();
for (int i = 0; i < capacity; i++) {
Object* key = dict->KeyAt(i);
if (key->IsNumber()) {
uint32_t number = static_cast<uint32_t>(key->Number());
if (new_length <= number && number < old_length) {
dict->SetEntry(i, the_hole_value, the_hole_value);
removed_entries++;
}
}
if (new_length != length) {
MaybeObject* maybe_object = heap->NumberFromUint32(new_length);
if (!maybe_object->To(&length_object)) return maybe_object;
}
// Remove elements that should be deleted.
int removed_entries = 0;
Object* the_hole_value = heap->the_hole_value();
for (int i = 0; i < capacity; i++) {
Object* key = dict->KeyAt(i);
if (key->IsNumber()) {
uint32_t number = static_cast<uint32_t>(key->Number());
if (new_length <= number && number < old_length) {
dict->SetEntry(i, the_hole_value, the_hole_value);
removed_entries++;
}
}
}
// Update the number of elements.
dict->ElementsRemoved(removed_entries);
}
// Update the number of elements.
dict->ElementsRemoved(removed_entries);
}
return length_object;
}

38
test/mjsunit/regress/regress-crbug-146910.js Normal file
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@ -0,0 +1,38 @@
// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
var x = [];
assertSame(0, x.length);
assertSame(undefined, x[0]);
Object.defineProperty(x, '0', { value: 7, configurable: false });
assertSame(1, x.length);
assertSame(7, x[0]);
x.length = 0;
assertSame(1, x.length);
assertSame(7, x[0]);