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[runtime] Always normalize prototype maps that aren't marked as 'should be fast' yet

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This makes the test in the bug ~10x faster. It could inadvertently make other things slower, so revert eagerly if included in a range where performance tanks.

BUG=chromium:666852

Review-Url: https://codereview.chromium.org/2525573002
Cr-Commit-Position: refs/heads/master@{#41178}
This commit is contained in:
verwaest 2016-11-22 05:24:53 -08:00 committed by Commit bot
parent a0e9160066
commit 30d2fb6b50
2 changed files with 10 additions and 16 deletions
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23
src/objects.cc
View File

@ -12547,19 +12547,10 @@ void Map::CompleteInobjectSlackTracking() {
static bool PrototypeBenefitsFromNormalization(Handle<JSObject> object) {
DisallowHeapAllocation no_gc;
if (!object->HasFastProperties()) return false;
Map* map = object->map();
if (map->is_prototype_map()) return false;
DescriptorArray* descriptors = map->instance_descriptors();
for (int i = 0; i < map->NumberOfOwnDescriptors(); i++) {
PropertyDetails details = descriptors->GetDetails(i);
if (details.location() == kDescriptor) continue;
if (details.representation().IsHeapObject() ||
details.representation().IsTagged()) {
FieldIndex index = FieldIndex::ForDescriptor(map, i);
if (object->RawFastPropertyAt(index)->IsJSFunction()) return true;
}
}
return false;
if (object->IsJSGlobalProxy()) return false;
if (object->GetIsolate()->bootstrapper()->IsActive()) return false;
return !object->map()->is_prototype_map() ||
!object->map()->should_be_fast_prototype_map();
}
// static
@ -12574,8 +12565,10 @@ void JSObject::MakePrototypesFast(Handle<Object> receiver,
if (!current->IsJSObject()) return;
Handle<JSObject> current_obj = Handle<JSObject>::cast(current);
Map* current_map = current_obj->map();
if (current_map->is_prototype_map() &&
!current_map->should_be_fast_prototype_map()) {
if (current_map->is_prototype_map()) {
// If the map is already marked as should be fast, we're done. Its
// prototypes will have been marked already as well.
if (current_map->should_be_fast_prototype_map()) return;
Handle<Map> map(current_map);
Map::SetShouldBeFastPrototypeMap(map, true, isolate);
JSObject::OptimizeAsPrototype(current_obj, FAST_PROTOTYPE);

3
test/mjsunit/fast-prototype.js
View File

@ -101,11 +101,12 @@ for (var i = 0; i < 4; i++) {
var x = {a: 1, b: 2, c: 3};
var o = { __proto__: x };
assertTrue(%HasFastProperties(x));
assertFalse(%HasFastProperties(x));
for (key in x) {
assertTrue(key == 'a');
break;
}
assertTrue(%HasFastProperties(x));
delete x.b;
for (key in x) {
assertTrue(key == 'a');