Add mistagging-readbarrier to weak cell

src/ia32/lithium-ia32.cc

 // Copyright 2012 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 <sstream>
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_IA32
 
@@ skipping 2153 matching lines @@
   }
   LInstruction* result = new(zone()) LStoreContextSlot(context, value, temp);
   if (instr->RequiresHoleCheck() && instr->DeoptimizesOnHole()) {
     result = AssignEnvironment(result);
   }
   return result;
 }
 
 
 LInstruction* LChunkBuilder::DoLoadNamedField(HLoadNamedField* instr) {
-  LOperand* obj = (instr->access().IsExternalMemory() &&
-                   instr->access().offset() == 0)
-      ? UseRegisterOrConstantAtStart(instr->object())
-      : UseRegisterAtStart(instr->object());
+  LOperand* obj;
+  if (instr->access().read_barrier()) {
+    DCHECK(!instr->access().IsExternalMemory());
+    obj = UseRegister(instr->object());
+  } else {
+    // With no read barrier we can have the same register for the object and
+    // the field.
+    obj = (instr->access().IsExternalMemory() && instr->access().offset() == 0)
+              ? UseRegisterOrConstantAtStart(instr->object())
+              : UseRegisterAtStart(instr->object());
+  }
   return DefineAsRegister(new(zone()) LLoadNamedField(obj));
 }
 
 
 LInstruction* LChunkBuilder::DoLoadNamedGeneric(HLoadNamedGeneric* instr) {
   LOperand* context = UseFixed(instr->context(), esi);
   LOperand* object =
       UseFixed(instr->object(), LoadDescriptor::ReceiverRegister());
   LOperand* vector = NULL;
   if (instr->HasVectorAndSlot()) {
@@ skipping 525 matching lines @@
   LOperand* function = UseRegisterAtStart(instr->function());
   LAllocateBlockContext* result =
       new(zone()) LAllocateBlockContext(context, function);
   return MarkAsCall(DefineFixed(result, esi), instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32