Reland 10216 - Optimize the equality check case of ICCompare stubs.

src/x64/ic-x64.cc

 // Copyright 2011 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 1623 matching lines @@
   HandleScope scope;
   Handle<Code> rewritten;
   State previous_state = GetState();
 
   State state = TargetState(previous_state, HasInlinedSmiCode(address()), x, y);
   if (state == GENERIC) {
     CompareStub stub(GetCondition(), strict(), NO_COMPARE_FLAGS);
     rewritten = stub.GetCode();
   } else {
     ICCompareStub stub(op_, state);
+    if (state == KNOWN_OBJECTS) {
+      stub.set_known_map(Handle<Map>(Handle<JSObject>::cast(x)->map()));
+    }
     rewritten = stub.GetCode();
   }
   set_target(*rewritten);
 
 #ifdef DEBUG
   if (FLAG_trace_ic) {
     PrintF("[CompareIC (%s->%s)#%s]\n",
            GetStateName(previous_state),
            GetStateName(state),
            Token::Name(op_));
@@ skipping 35 matching lines @@
   Condition cc = *jmp_address == Assembler::kJncShortOpcode
       ? not_zero
       : zero;
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64