Add map-based read barrier to WeakCell

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 819a30587a791c03a80983815f44965d8584f0ad..e0251280aefb8702a521d7324495af2ef929ec6d 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -2259,10 +2259,12 @@ void CallICStub::Generate(MacroAssembler* masm) {
   // to be a pointer.
   STATIC_ASSERT(WeakCell::kSize >= kPointerSize);
   STATIC_ASSERT(AllocationSite::kTransitionInfoOffset ==
-                    WeakCell::kValueOffset &&
-                WeakCell::kValueOffset == Symbol::kHashFieldSlot);
+                    WeakCell::kValueOffsetDontForgetTheReadBarrier &&
+                AllocationSite::kTransitionInfoOffset ==
+                    Symbol::kHashFieldSlot);
 
-  __ cmp(edi, FieldOperand(ecx, WeakCell::kValueOffset));
+  __ cmp(edi,
+         FieldOperand(ecx, WeakCell::kValueOffsetDontForgetTheReadBarrier));
   __ j(not_equal, &extra_checks_or_miss);
 
   // The compare above could have been a SMI/SMI comparison. Guard against this
@@ -3792,11 +3794,12 @@ void CompareICStub::GenerateObjects(MacroAssembler* masm) {
 void CompareICStub::GenerateKnownObjects(MacroAssembler* masm) {
   Label miss;
   Handle<WeakCell> cell = Map::WeakCellForMap(known_map_);
+  // Combine two Smi tests into one with bitwise and.
   __ mov(ecx, edx);
   __ and_(ecx, eax);
   __ JumpIfSmi(ecx, &miss, Label::kNear);
 
-  __ GetWeakValue(edi, cell);
+  __ GetWeakValueNoReadBarrier(edi, cell);
   __ mov(ecx, FieldOperand(eax, HeapObject::kMapOffset));
   __ mov(ebx, FieldOperand(edx, HeapObject::kMapOffset));
   __ cmp(ecx, edi);