Tweak register allocation for Math.round and do not use roundsd.

src/ia32/lithium-ia32.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 296 matching lines @@
   value()->PrintTo(stream);
 }
 
 
 void LMathPowHalf::PrintDataTo(StringStream* stream) {
   stream->Add("/pow_half ");
   value()->PrintTo(stream);
 }
 
 
+void LMathRound::PrintDataTo(StringStream* stream) {
+  stream->Add("/round ");
+  value()->PrintTo(stream);
+}
+
+
 void LLoadContextSlot::PrintDataTo(StringStream* stream) {
   context()->PrintTo(stream);
   stream->Add("[%d]", slot_index());
 }
 
 
 void LStoreContextSlot::PrintDataTo(StringStream* stream) {
   context()->PrintTo(stream);
   stream->Add("[%d] <- ", slot_index());
   value()->PrintTo(stream);
@@ skipping 811 matching lines @@
     LOperand* temp2 = TempRegister();
     LMathExp* result = new(zone()) LMathExp(value, temp1, temp2);
     return DefineAsRegister(result);
   } else if (op == kMathSin || op == kMathCos || op == kMathTan) {
     LOperand* context = UseFixed(instr->context(), esi);
     LOperand* input = UseFixedDouble(instr->value(), xmm1);
     LUnaryMathOperation* result = new(zone()) LUnaryMathOperation(context,
                                                                   input);
     return MarkAsCall(DefineFixedDouble(result, xmm1), instr);
   } else {
-    LOperand* input;
-    if (op == kMathRound &&
-        (!CpuFeatures::IsSupported(SSE4_1) ||
-         instr->CheckFlag(HValue::kBailoutOnMinusZero))) {
-      // Math.round implemented without roundsd.  Input may be overwritten.
-      ASSERT(instr->value()->representation().IsDouble());
-      input = UseTempRegister(instr->value());
-    } else {
-      input = UseRegisterAtStart(instr->value());
-    }
+    LOperand* input = UseRegisterAtStart(instr->value());
     LOperand* context = UseAny(instr->context());  // Deferred use by MathAbs.
     if (op == kMathPowHalf) {
       LOperand* temp = TempRegister();
       LMathPowHalf* result = new(zone()) LMathPowHalf(context, input, temp);
       return DefineSameAsFirst(result);
+    } else if (op == kMathRound) {
+      LOperand* temp = FixedTemp(xmm4);
+      LMathRound* result = new(zone()) LMathRound(context, input, temp);
+      return AssignEnvironment(DefineAsRegister(result));
     }
     LUnaryMathOperation* result = new(zone()) LUnaryMathOperation(context,
                                                                   input);
     switch (op) {
       case kMathAbs:
         return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
       case kMathFloor:
         return AssignEnvironment(DefineAsRegister(result));
-      case kMathRound:
-        return AssignEnvironment(DefineAsRegister(result));
       case kMathSqrt:
         return DefineSameAsFirst(result);
       default:
         UNREACHABLE();
         return NULL;
     }
   }
 }
 
 
@@ skipping 1389 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_IA32