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Remove unnecessary elements type check when allocating array in runtime.

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BUG=
TEST=--smi-only-arrays should be perf-neutral to allocating big arrays in a tight loop.

Review URL: https://chromiumcodereview.appspot.com/9356002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10711 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2012-02-15 12:13:55 +00:00
parent 941d884af4
commit b21ada9a98
2 changed files with 8 additions and 7 deletions
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9
src/builtins.cc
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@ -218,12 +218,13 @@ static MaybeObject* ArrayCodeGenericCommon(Arguments* args,
if (obj->IsSmi()) {
int len = Smi::cast(obj)->value();
if (len >= 0 && len < JSObject::kInitialMaxFastElementArray) {
Object* obj;
Object* fixed_array;
{ MaybeObject* maybe_obj = heap->AllocateFixedArrayWithHoles(len);
if (!maybe_obj->ToObject(&obj)) return maybe_obj;
if (!maybe_obj->ToObject(&fixed_array)) return maybe_obj;
}
MaybeObject* maybe_obj = array->SetContent(FixedArray::cast(obj));
if (maybe_obj->IsFailure()) return maybe_obj;
// We do not use SetContent to skip the unnecessary elements type check.
array->set_elements(FixedArray::cast(fixed_array));
array->set_length(Smi::cast(obj));
return array;
}
}

6
src/heap.cc
View File

@ -4361,10 +4361,10 @@ MaybeObject* Heap::AllocateJSArray(
Context* global_context = isolate()->context()->global_context();
JSFunction* array_function = global_context->array_function();
Map* map = array_function->initial_map();
if (elements_kind == FAST_ELEMENTS || !FLAG_smi_only_arrays) {
map = Map::cast(global_context->object_js_array_map());
} else if (elements_kind == FAST_DOUBLE_ELEMENTS) {
if (elements_kind == FAST_DOUBLE_ELEMENTS) {
map = Map::cast(global_context->double_js_array_map());
} else if (elements_kind == FAST_ELEMENTS || !FLAG_smi_only_arrays) {
map = Map::cast(global_context->object_js_array_map());
} else {
ASSERT(elements_kind == FAST_SMI_ONLY_ELEMENTS);
ASSERT(map == global_context->smi_js_array_map());