Improve generated code for HDoCompareObjectEqAndBranch on ia32/x64

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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 2037 matching lines @@
         }
       }
     }
     EmitBranch(true_block, false_block, cc);
   }
 }
 
 
 void LCodeGen::DoCmpObjectEqAndBranch(LCmpObjectEqAndBranch* instr) {
   Register left = ToRegister(instr->left());
-  Register right = ToRegister(instr->right());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
   int true_block = chunk_->LookupDestination(instr->true_block_id());
 
-  __ cmpq(left, right);
+  if (instr->right()->IsConstantOperand()) {
+    __ Cmp(left, ToHandle(LConstantOperand::cast(instr->right())));
+  } else {
+    __ cmpq(left, ToRegister(instr->right()));
+  }
   EmitBranch(true_block, false_block, equal);
 }
 
 
 void LCodeGen::DoCmpConstantEqAndBranch(LCmpConstantEqAndBranch* instr) {
   Register left = ToRegister(instr->left());
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   __ cmpq(left, Immediate(instr->hydrogen()->right()));
@@ skipping 3587 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64