Revert "Refactor transitioning stores."

src/x64/lithium-x64.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 "v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "lithium-allocator-inl.h"
 #include "x64/lithium-x64.h"
@@ skipping 2258 matching lines @@
       new(zone()) LTrapAllocationMemento(object, temp);
   return AssignEnvironment(result);
 }
 
 
 LInstruction* LChunkBuilder::DoStoreNamedField(HStoreNamedField* instr) {
   bool is_in_object = instr->access().IsInobject();
   bool is_external_location = instr->access().IsExternalMemory() &&
       instr->access().offset() == 0;
   bool needs_write_barrier = instr->NeedsWriteBarrier();
+  bool needs_write_barrier_for_map = instr->has_transition() &&
+      instr->NeedsWriteBarrierForMap();
 
   LOperand* obj;
   if (needs_write_barrier) {
     obj = is_in_object
         ? UseRegister(instr->object())
         : UseTempRegister(instr->object());
   } else if (is_external_location) {
     ASSERT(!is_in_object);
     ASSERT(!needs_write_barrier);
+    ASSERT(!needs_write_barrier_for_map);
     obj = UseRegisterOrConstant(instr->object());
   } else {
-    obj = UseRegisterAtStart(instr->object());
+    obj = needs_write_barrier_for_map
+        ? UseRegister(instr->object())
+        : UseRegisterAtStart(instr->object());
   }
 
   bool can_be_constant = instr->value()->IsConstant() &&
       HConstant::cast(instr->value())->NotInNewSpace() &&
       !instr->field_representation().IsDouble();
 
   LOperand* val;
   if (needs_write_barrier) {
     val = UseTempRegister(instr->value());
   } else if (is_external_location) {
     val = UseFixed(instr->value(), rax);
   } else if (can_be_constant) {
     val = UseRegisterOrConstant(instr->value());
   } else if (instr->field_representation().IsSmi()) {
     val = UseRegister(instr->value());
   } else if (instr->field_representation().IsDouble()) {
     val = UseRegisterAtStart(instr->value());
   } else {
     val = UseRegister(instr->value());
   }
 
   // We only need a scratch register if we have a write barrier or we
   // have a store into the properties array (not in-object-property).
-  LOperand* temp = (!is_in_object || needs_write_barrier)
-      ? TempRegister() : NULL;
+  LOperand* temp = (!is_in_object || needs_write_barrier ||
+      needs_write_barrier_for_map) ? TempRegister() : NULL;
 
   LInstruction* result = new(zone()) LStoreNamedField(obj, val, temp);
   if (!instr->access().IsExternalMemory() &&
       instr->field_representation().IsHeapObject() &&
       (val->IsConstantOperand()
        ? HConstant::cast(instr->value())->HasSmiValue()
        : !instr->value()->type().IsHeapObject())) {
     result = AssignEnvironment(result);
   }
   return result;
@@ skipping 262 matching lines @@
   LOperand* index = UseTempRegister(instr->index());
   LLoadFieldByIndex* load = new(zone()) LLoadFieldByIndex(object, index);
   LInstruction* result = DefineSameAsFirst(load);
   return AssignPointerMap(result);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64