Reviewers: danno,
Description:
Handle map transitions in CALLBACKS when doing map tree traversal.
We will have such transitions in the future and this CL is necessary to keep
slack tracking working then.
Please review this at https://chromiumcodereview.appspot.com/9285008/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/objects.cc
Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index
426327c9caa686573939181a56f1b38f91000a99..e4cd7763dd0faf3f1f44c0617b257f3e694bfdfc
100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -4954,15 +4954,43 @@ class IntrusiveMapTransitionIterator {
Map* Next() {
ASSERT(IsIterating());
FixedArray* contents = ContentArray();
+ // Attention, tricky index manipulation ahead: Every entry in the
contents
+ // array consists of a value/details pair, so the index is typically
even.
+ // An exception is made for CALLBACKS entries: An even index means we
look
+ // at its getter, and an odd index means we look at its setter.
int index = Smi::cast(*ContentHeader())->value();
while (index < contents->length()) {
- int next_index = index + 2;
- PropertyDetails details(Smi::cast(contents->get(index + 1)));
- if (details.IsTransition()) {
- *ContentHeader() = Smi::FromInt(next_index);
- return static_cast<Map*>(contents->get(index));
+ PropertyDetails details(Smi::cast(contents->get(index | 1)));
+ switch (details.type()) {
+ case MAP_TRANSITION:
+ case CONSTANT_TRANSITION:
+ case ELEMENTS_TRANSITION:
+ // We definitely have a map transition.
+ *ContentHeader() = Smi::FromInt(index + 2);
+ return static_cast<Map*>(contents->get(index));
+ case CALLBACKS: {
+ // We might have a map transition in a getter or in a setter.
+ AccessorPair* accessors =
+ static_cast<AccessorPair*>(contents->get(index & ~1));
+ Object* accessor =
+ ((index & 1) == 0) ? accessors->getter() :
accessors->setter();
+ index++;
+ if (accessor->IsMap()) {
+ *ContentHeader() = Smi::FromInt(index);
+ return static_cast<Map*>(accessor);
+ }
+ break;
+ }
+ case NORMAL:
+ case FIELD:
+ case CONSTANT_FUNCTION:
+ case HANDLER:
+ case INTERCEPTOR:
+ case NULL_DESCRIPTOR:
+ // We definitely have no map transition.
+ index += 2;
+ break;
}
- index = next_index;
}
*ContentHeader() = descriptor_array_->GetHeap()->fixed_array_map();
return NULL;
--
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