Index: src/ic.cc |
diff --git a/src/ic.cc b/src/ic.cc |
index da2211b7b686abc9f28a586fcaba986f4b90eaec..c999e58cf42e76afcf4f123a8830743260449877 100644 |
--- a/src/ic.cc |
+++ b/src/ic.cc |
@@ -855,28 +855,6 @@ MaybeObject* LoadIC::Load(State state, |
return Smi::FromInt(String::cast(*string)->length()); |
} |
- // Use specialized code for getting the length of arrays. |
- if (object->IsJSArray() && |
- name->Equals(isolate()->heap()->length_string())) { |
- Handle<Code> stub; |
- if (state == UNINITIALIZED) { |
- stub = pre_monomorphic_stub(); |
- } else if (state == PREMONOMORPHIC) { |
- ArrayLengthStub array_length_stub(kind()); |
- stub = array_length_stub.GetCode(isolate()); |
- } else if (state != MEGAMORPHIC) { |
- ASSERT(state != GENERIC); |
- stub = megamorphic_stub(); |
- } |
- if (!stub.is_null()) { |
- set_target(*stub); |
-#ifdef DEBUG |
- if (FLAG_trace_ic) PrintF("[LoadIC : +#length /array]\n"); |
-#endif |
- } |
- return JSArray::cast(*object)->length(); |
- } |
- |
// Use specialized code for getting prototype of functions. |
if (object->IsJSFunction() && |
name->Equals(isolate()->heap()->prototype_string()) && |
@@ -1052,6 +1030,34 @@ void IC::PatchCache(State state, |
// Only move to megamorphic if the target changes. |
if (target() != *code) { |
if (target()->is_load_stub()) { |
+ bool is_map_transition = false; |
danno
2013/03/13 11:49:48
How about refactoring this code into a method "IsT
Dmitry Lomov (no reviews)
2013/03/13 16:14:31
Done.
|
+ { |
+ // Stay monomorpic if: |
+ // 1. Target handler is identical to a new handler |
+ // 2. New map can transition to a receiver map |
+ AssertNoAllocation no_allocation; |
+ Code* old_handler = target()->FindFirstCode(); |
+ if (old_handler == *code) { |
+ Map* old_map = target()->FindFirstMap(); |
+ Map* receiver_map = receiver->map(); |
+ ElementsKind receiver_elements_kind = |
+ receiver_map->elements_kind(); |
+ bool more_general_transition = |
+ IsMoreGeneralElementsKindTransition( |
+ old_map->elements_kind(), receiver_elements_kind); |
+ Map* transitioned_old_map = more_general_transition |
+ ? old_map->LookupElementsTransitionMap(receiver_elements_kind) |
+ : NULL; |
Toon Verwaest
2013/03/13 11:56:48
I think we could make this more generic by followi
|
+ |
+ if (transitioned_old_map == receiver_map) { |
+ is_map_transition = true; |
+ } |
+ } |
+ } |
+ if (is_map_transition) { |
+ UpdateMonomorphicIC(receiver, code, name); |
+ break; |
+ } |
if (UpdatePolymorphicIC(state, strict_mode, receiver, name, code)) { |
break; |
} |
@@ -1162,6 +1168,7 @@ void LoadIC::UpdateCaches(LookupResult* lookup, |
if (code.is_null()) return; |
} |
+ |
danno
2013/03/13 11:49:48
nit: remove extra whitespace
Dmitry Lomov (no reviews)
2013/03/13 16:14:31
Done.
|
PatchCache(state, kNonStrictMode, receiver, name, code); |
TRACE_IC("LoadIC", name, state, target()); |
} |
@@ -1223,6 +1230,12 @@ Handle<Code> LoadIC::ComputeLoadHandler(LookupResult* lookup, |
if (!holder->HasFastProperties()) break; |
return isolate()->stub_cache()->ComputeLoadViaGetter( |
name, receiver, holder, Handle<JSFunction>::cast(getter)); |
+ } else if (receiver->IsJSArray() && |
+ name->Equals(isolate()->heap()->length_string())) { |
+ PropertyIndex lengthIndex = |
+ PropertyIndex::NewHeaderIndex(JSArray::kLengthOffset / kPointerSize); |
+ return isolate()->stub_cache()->ComputeLoadField( |
+ name, receiver, holder, lengthIndex); |
} |
// TODO(dcarney): Handle correctly. |
if (callback->IsDeclaredAccessorInfo()) break; |