Use mutable heapnumbers to store doubles in fields.

src/ia32/lithium-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2154 matching lines @@
     value = UseRegister(instr->value());
     temp = NULL;
   }
   LInstruction* result = new(zone()) LStoreContextSlot(context, value, temp);
   return instr->RequiresHoleCheck() ? AssignEnvironment(result) : result;
 }
 
 
 LInstruction* LChunkBuilder::DoLoadNamedField(HLoadNamedField* instr) {
   LOperand* obj = UseRegisterAtStart(instr->object());
-  LOperand* temp = instr->representation().IsDouble() ? TempRegister() : NULL;
-  ASSERT(temp == NULL || FLAG_track_double_fields);
-  return DefineAsRegister(new(zone()) LLoadNamedField(obj, temp));
+  return DefineAsRegister(new(zone()) LLoadNamedField(obj));
 }
 
 
 LInstruction* LChunkBuilder::DoLoadNamedFieldPolymorphic(
     HLoadNamedFieldPolymorphic* instr) {
   ASSERT(instr->representation().IsTagged());
   if (instr->need_generic()) {
     LOperand* context = UseFixed(instr->context(), esi);
     LOperand* obj = UseFixed(instr->object(), edx);
     LLoadNamedFieldPolymorphic* result =
@@ skipping 232 matching lines @@
       HConstant::cast(instr->value())->NotInNewSpace() &&
       !(FLAG_track_double_fields && instr->field_representation().IsDouble());
 
   LOperand* val;
   if (needs_write_barrier) {
     val = UseTempRegister(instr->value());
   } else if (can_be_constant) {
     val = UseRegisterOrConstant(instr->value());
   } else if (FLAG_track_fields && instr->field_representation().IsSmi()) {
     val = UseTempRegister(instr->value());
+  } else if (FLAG_track_double_fields &&
+             instr->field_representation().IsDouble()) {
+    if (CpuFeatures::IsSafeForSnapshot(SSE2)) {
+      val = UseRegisterAtStart(instr->value());
+    } else {
+      val = UseX87TopOfStack(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 = (!instr->is_in_object() || needs_write_barrier ||
-      needs_write_barrier_for_map) ? TempRegister() : NULL;
+                    needs_write_barrier_for_map) ? TempRegister() : NULL;
 
   // We need a temporary register for write barrier of the map field.
   LOperand* temp_map = needs_write_barrier_for_map ? TempRegister() : NULL;
 
   LStoreNamedField* result =
       new(zone()) LStoreNamedField(obj, val, temp, temp_map);
-  if ((FLAG_track_fields && instr->field_representation().IsSmi()) ||
-      (FLAG_track_double_fields && instr->field_representation().IsDouble())) {
+  if (FLAG_track_fields && instr->field_representation().IsSmi()) {
     return AssignEnvironment(result);
   }
   return result;
 }
 
 
 LInstruction* LChunkBuilder::DoStoreNamedGeneric(HStoreNamedGeneric* instr) {
   LOperand* context = UseFixed(instr->context(), esi);
   LOperand* object = UseFixed(instr->object(), edx);
   LOperand* value = UseFixed(instr->value(), eax);
@@ skipping 309 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32