Use mutable heapnumbers to store doubles in fields.

src/hydrogen-instructions.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 2503 matching lines @@
       need_generic_(false) {
   SetOperandAt(0, context);
   SetOperandAt(1, object);
   set_representation(Representation::Tagged());
   SetGVNFlag(kDependsOnMaps);
   SmallMapList negative_lookups;
   for (int i = 0;
        i < types->length() && types_.length() < kMaxLoadPolymorphism;
        ++i) {
     Handle<Map> map = types->at(i);
+    // Deprecated maps are updated to the current map in the type oracle.
+    ASSERT(!map->is_deprecated());
     LookupResult lookup(map->GetIsolate());
     map->LookupDescriptor(NULL, *name, &lookup);
     if (lookup.IsFound()) {
       switch (lookup.type()) {
         case FIELD: {
           int index = lookup.GetLocalFieldIndexFromMap(*map);
           if (index < 0) {
             SetGVNFlag(kDependsOnInobjectFields);
           } else {
             SetGVNFlag(kDependsOnBackingStoreFields);
           }
+          if (FLAG_track_double_fields &&
+              lookup.representation().IsDouble()) {
+            // Since the value needs to be boxed, use a generic handler for
+            // loading doubles.
+            continue;
+          }
           types_.Add(types->at(i), zone);
           break;
         }
         case CONSTANT_FUNCTION:
           types_.Add(types->at(i), zone);
           break;
         case CALLBACKS:
           break;
         case TRANSITION:
         case INTERCEPTOR:
@@ skipping 1077 matching lines @@
 
 
 void HCheckFunction::Verify() {
   HInstruction::Verify();
   ASSERT(HasNoUses());
 }
 
 #endif
 
 } }  // namespace v8::internal