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Delete from non-array end by trimming the backing store

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Review URL: https://codereview.chromium.org/1218663009

Cr-Commit-Position: refs/heads/master@{#29521}
This commit is contained in:
verwaest 2015-07-07 09:02:30 -07:00 committed by Commit bot
parent f043ab8618
commit 44dcc0a2c0
1 changed files with 37 additions and 0 deletions
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37
src/elements.cc
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@ -1037,12 +1037,39 @@ class FastElementsAccessor
typedef typename KindTraits::BackingStore BackingStore;
static void DeleteAtEnd(Handle<JSObject> obj,
Handle<BackingStore> backing_store, uint32_t entry) {
uint32_t length = static_cast<uint32_t>(backing_store->length());
Heap* heap = obj->GetHeap();
for (; entry > 0; entry--) {
if (!backing_store->is_the_hole(entry - 1)) break;
}
if (entry == 0) {
FixedArray* empty = heap->empty_fixed_array();
if (obj->HasFastArgumentsElements()) {
FixedArray::cast(obj->elements())->set(1, empty);
} else {
obj->set_elements(empty);
}
return;
}
heap->RightTrimFixedArray<Heap::CONCURRENT_TO_SWEEPER>(*backing_store,
length - entry);
}
static void DeleteCommon(Handle<JSObject> obj, uint32_t entry,
Handle<FixedArrayBase> store) {
DCHECK(obj->HasFastSmiOrObjectElements() ||
obj->HasFastDoubleElements() ||
obj->HasFastArgumentsElements());
Handle<BackingStore> backing_store = Handle<BackingStore>::cast(store);
if (!obj->IsJSArray() &&
entry == static_cast<uint32_t>(store->length()) - 1) {
DeleteAtEnd(obj, backing_store, entry);
return;
}
backing_store->set_the_hole(entry);
// TODO(verwaest): Move this out of elements.cc.
@ -1061,6 +1088,16 @@ class FastElementsAccessor
}
if ((entry > 0 && backing_store->is_the_hole(entry - 1)) ||
(entry + 1 < length && backing_store->is_the_hole(entry + 1))) {
if (!obj->IsJSArray()) {
uint32_t i;
for (i = entry + 1; i < length; i++) {
if (!backing_store->is_the_hole(i)) break;
}
if (i == length) {
DeleteAtEnd(obj, backing_store, entry);
return;
}
}
int num_used = 0;
for (int i = 0; i < backing_store->length(); ++i) {
if (!backing_store->is_the_hole(i)) ++num_used;