Revision: 13558
Author: [email protected]
Date: Wed Jan 30 07:07:58 2013
Log: Also allow the empty object map to keep transitions.
With the old implementation, due to the map-check being inadequate, such
transitions were already added for cross-context field stores. It is not
necessary anymore to not store transitions, since we properly clear
non-live transitions. Globally enabling this feature will help find more
bugs.
BUG=v8:2518
[email protected]
Review URL: https://chromiumcodereview.appspot.com/12092063
http://code.google.com/p/v8/source/detail?r=13558
Modified:
/branches/bleeding_edge/src/isolate.h
/branches/bleeding_edge/src/objects.cc
=======================================
--- /branches/bleeding_edge/src/isolate.h Wed Jan 30 04:19:32 2013
+++ /branches/bleeding_edge/src/isolate.h Wed Jan 30 07:07:58 2013
@@ -531,11 +531,6 @@
void set_save_context(SaveContext* save) {
thread_local_top_.save_context_ = save;
}
-
- // Access to the map of "new Object()".
- Map* empty_object_map() {
- return context()->native_context()->object_function()->map();
- }
// Access to current thread id.
ThreadId thread_id() { return thread_local_top_.thread_id_; }
=======================================
--- /branches/bleeding_edge/src/objects.cc Thu Jan 24 03:55:05 2013
+++ /branches/bleeding_edge/src/objects.cc Wed Jan 30 07:07:58 2013
@@ -1601,10 +1601,7 @@
if (!maybe_values->To(&values)) return maybe_values;
}
- // Only allow map transition if the object isn't the global object.
- TransitionFlag flag = isolate->empty_object_map() != map()
- ? INSERT_TRANSITION
- : OMIT_TRANSITION;
+ TransitionFlag flag = INSERT_TRANSITION;
Map* new_map;
MaybeObject* maybe_new_map = map()->CopyAddDescriptor(&new_field, flag);
@@ -1630,15 +1627,11 @@
// Allocate new instance descriptors with (name, function) added
ConstantFunctionDescriptor d(name, function, attributes, 0);
- Heap* heap = GetHeap();
TransitionFlag flag =
- // Do not add transitions to the empty object map (map of "new
Object()"),
- // nor to global objects.
- (map() == heap->isolate()->empty_object_map() || IsGlobalObject() ||
+ // Do not add transitions to global objects.
+ (IsGlobalObject() ||
// Don't add transitions to special properties with non-trivial
// attributes.
- // TODO(verwaest): Once we support attribute changes, these
transitions
- // should be kept as well.
attributes != NONE)
? OMIT_TRANSITION
: INSERT_TRANSITION;
@@ -1841,10 +1834,8 @@
if (!HasFastProperties()) return result;
- // This method should only be used to convert existing transitions.
Objects
- // with the map of "new Object()" cannot have transitions in the first
place.
+ // This method should only be used to convert existing transitions.
Map* new_map = map();
- ASSERT(new_map != GetIsolate()->empty_object_map());
// TODO(verwaest): From here on we lose existing map transitions, causing
// invalid back pointers. This will change once we can store multiple
@@ -2415,10 +2406,8 @@
}
bool allow_store_transition =
- // Only remember the map transition if the object's map is NOT equal
to
- // the global object_function's map and there is not an already
existing
+ // Only remember the map transition if there is not an already
existing
// non-matching element transition.
- (GetIsolate()->empty_object_map() != map()) &&
!start_map->IsUndefined() && !start_map->is_shared() &&
IsFastElementsKind(from_kind);
--
--
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