Add map-based read barrier to WeakCell

src/ic/ia32/ic-compiler-ia32.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_IA32
 
 #include "src/ic/ic.h"
 #include "src/ic/ic-compiler.h"
@@ skipping 97 matching lines @@
   __ mov(map_reg, FieldOperand(receiver(), HeapObject::kMapOffset));
   for (int i = 0; i < receiver_maps->length(); ++i) {
     Handle<WeakCell> cell = Map::WeakCellForMap(receiver_maps->at(i));
     __ CmpWeakValue(map_reg, cell, scratch2());
     if (transitioned_maps->at(i).is_null()) {
       __ j(equal, handler_stubs->at(i));
     } else {
       Label next_map;
       __ j(not_equal, &next_map, Label::kNear);
       Handle<WeakCell> cell = Map::WeakCellForMap(transitioned_maps->at(i));
-      __ LoadWeakValue(transition_map(), cell, &miss);
+      __ LoadWeakValue(transition_map(), cell, scratch2(), &miss);
       __ jmp(handler_stubs->at(i), RelocInfo::CODE_TARGET);
       __ bind(&next_map);
     }
   }
   __ bind(&miss);
   TailCallBuiltin(masm(), MissBuiltin(kind()));
 
   // Return the generated code.
   return GetCode(kind(), Code::NORMAL, factory()->empty_string(), POLYMORPHIC);
 }
 
 
 #undef __
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32