Use a special EnumLength field to indicate number of valid enum cache values.

src/x64/lithium-x64.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 1510 matching lines @@
 }
 
 
 LInstruction* LChunkBuilder::DoFixedArrayBaseLength(
     HFixedArrayBaseLength* instr) {
   LOperand* array = UseRegisterAtStart(instr->value());
   return DefineAsRegister(new(zone()) LFixedArrayBaseLength(array));
 }
 
 
+LInstruction* LChunkBuilder::DoMapEnumLength(HMapEnumLength* instr) {
+  LOperand* map = UseRegisterAtStart(instr->value());
+  return DefineAsRegister(new(zone()) LMapEnumLength(map));
+}
+
+
 LInstruction* LChunkBuilder::DoElementsKind(HElementsKind* instr) {
   LOperand* object = UseRegisterAtStart(instr->value());
   return DefineAsRegister(new(zone()) LElementsKind(object));
 }
 
 
 LInstruction* LChunkBuilder::DoValueOf(HValueOf* instr) {
   LOperand* object = UseRegister(instr->value());
   LValueOf* result = new(zone()) LValueOf(object);
   return DefineSameAsFirst(result);
@@ skipping 764 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_X64