Fix a bug with register use in optimized Math.round.

src/mips/lithium-codegen-mips.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 2910 matching lines @@
 
   // The following conversion will not work with numbers
   // outside of ]-2^32, 2^32[.
   DeoptimizeIf(ge, instr->environment(), scratch,
                Operand(HeapNumber::kExponentBias + 32));
 
   // Save the original sign for later comparison.
   __ And(scratch, result, Operand(HeapNumber::kSignMask));
 
   __ Move(double_scratch0(), 0.5);
-  __ add_d(input, input, double_scratch0());
+  __ add_d(double_scratch0(), input, double_scratch0());
 
   // Check sign of the result: if the sign changed, the input
   // value was in ]0.5, 0[ and the result should be -0.
-  __ mfc1(result, input.high());
+  __ mfc1(result, double_scratch0().high());
   __ Xor(result, result, Operand(scratch));
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     // ARM uses 'mi' here, which is 'lt'
     DeoptimizeIf(lt, instr->environment(), result,
                  Operand(zero_reg));
   } else {
     Label skip2;
     // ARM uses 'mi' here, which is 'lt'
     // Negating it results in 'ge'
     __ Branch(&skip2, ge, result, Operand(zero_reg));
     __ mov(result, zero_reg);
     __ Branch(&done);
     __ bind(&skip2);
   }
 
   Register except_flag = scratch;
 
   __ EmitFPUTruncate(kRoundToMinusInf,
                      double_scratch0().low(),
-                     input,
+                     double_scratch0(),
                      result,
                      except_flag);
 
   DeoptimizeIf(ne, instr->environment(), except_flag, Operand(zero_reg));
 
   __ mfc1(result, double_scratch0().low());
 
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     // Test for -0.
     __ Branch(&done, ne, result, Operand(zero_reg));
@@ skipping 1665 matching lines @@
   ASSERT(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal