Move field index into property details, freeing up the value slot of fields.

src/objects-inl.h

 // 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 40 matching lines @@
 
 namespace v8 {
 namespace internal {
 
 PropertyDetails::PropertyDetails(Smi* smi) {
   value_ = smi->value();
 }
 
 
 Smi* PropertyDetails::AsSmi() {
-  return Smi::FromInt(value_);
+  // Ensure the upper 2 bits have the same value by sign extending it. This is
+  // necessary to be able to use the 31st bit of the property details.
+  int value = value_ << 1;
+  return Smi::FromInt(value >> 1);
 }
 
 
 PropertyDetails PropertyDetails::AsDeleted() {
   Smi* smi = Smi::FromInt(value_ | DeletedField::encode(1));
   return PropertyDetails(smi);
 }
 
 
 #define TYPE_CHECKER(type, instancetype)                                \
@@ skipping 2248 matching lines @@
   return PropertyDetails(Smi::cast(details));
 }
 
 
 PropertyType DescriptorArray::GetType(int descriptor_number) {
   return GetDetails(descriptor_number).type();
 }
 
 
 int DescriptorArray::GetFieldIndex(int descriptor_number) {
-  return Descriptor::IndexFromValue(GetValue(descriptor_number));
+  return GetDetails(descriptor_number).field_index();
 }
 
 
 JSFunction* DescriptorArray::GetConstantFunction(int descriptor_number) {
   return JSFunction::cast(GetValue(descriptor_number));
 }
 
 
 Object* DescriptorArray::GetCallbacksObject(int descriptor_number) {
   ASSERT(GetType(descriptor_number) == CALLBACKS);
@@ skipping 3876 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_