Improve generated MIPS code for conditional expressions and branches by delaying

runtime/vm/stub_code_mips.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 2177 matching lines @@
   __ CallRuntime(kBigintCompareRuntimeEntry, 2);
   __ TraceSimMsg("IdenticalWithNumberCheckStub return");
   // Result in V0, 0 means equal.
   __ LeaveStubFrame();
   __ b(&done);
   __ delay_slot()->mov(CMPRES1, V0);
 
   __ Bind(&reference_compare);
   __ subu(CMPRES1, left, right);
   __ Bind(&done);
-  // A branch or test after this comparison will check CMPRES1 == CMPRES2.
-  __ mov(CMPRES2, ZR);
+  // A branch or test after this comparison will check CMPRES1 == ZR.
 }
 
 
 // Called only from unoptimized code. All relevant registers have been saved.
 // RA: return address.
 // SP + 4: left operand.
 // SP + 0: right operand.
 // Returns: CMPRES1 is zero if equal, non-zero otherwise.
 void StubCode::GenerateUnoptimizedIdenticalWithNumberCheckStub(
     Assembler* assembler) {
@@ skipping 38 matching lines @@
   const Register right = T0;
   __ lw(left, Address(SP, 1 * kWordSize));
   __ lw(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp1, temp2);
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS