Use xorps to break the cvtsi2sd unnecessary dependence due to its partially written

src/ia32/lithium-codegen-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 3936 matching lines @@
     __ cvttsd2si(output_reg, Operand(input_reg));
     // Overflow is signalled with minint.
     __ cmp(output_reg, 0x80000000u);
     DeoptimizeIf(equal, instr->environment());
     __ jmp(&done, Label::kNear);
 
     // Non-zero negative reaches here.
     __ bind(&negative_sign);
     // Truncate, then compare and compensate.
     __ cvttsd2si(output_reg, Operand(input_reg));
-    __ cvtsi2sd(xmm_scratch, output_reg);
+    __ Cvtsi2sd(xmm_scratch, output_reg);
     __ ucomisd(input_reg, xmm_scratch);
     __ j(equal, &done, Label::kNear);
     __ sub(output_reg, Immediate(1));
     DeoptimizeIf(overflow, instr->environment());
 
     __ bind(&done);
   }
 }
 
 
@@ skipping 29 matching lines @@
   // CVTTSD2SI rounds towards zero, we use ceil(x - (-0.5)) and then
   // compare and compensate.
   __ movsd(input_temp, input_reg);  // Do not alter input_reg.
   __ subsd(input_temp, xmm_scratch);
   __ cvttsd2si(output_reg, Operand(input_temp));
   // Catch minint due to overflow, and to prevent overflow when compensating.
   __ cmp(output_reg, 0x80000000u);
   __ RecordComment("D2I conversion overflow");
   DeoptimizeIf(equal, instr->environment());
 
-  __ cvtsi2sd(xmm_scratch, output_reg);
+  __ Cvtsi2sd(xmm_scratch, output_reg);
   __ ucomisd(xmm_scratch, input_temp);
   __ j(equal, &done);
   __ sub(output_reg, Immediate(1));
   // No overflow because we already ruled out minint.
   __ jmp(&done);
 
   __ bind(&round_to_zero);
   // We return 0 for the input range [+0, 0.5[, or [-0.5, 0.5[ if
   // we can ignore the difference between a result of -0 and +0.
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
@@ skipping 949 matching lines @@
 }
 
 
 void LCodeGen::DoInteger32ToDouble(LInteger32ToDouble* instr) {
   LOperand* input = instr->value();
   LOperand* output = instr->result();
   ASSERT(input->IsRegister() || input->IsStackSlot());
   ASSERT(output->IsDoubleRegister());
   if (CpuFeatures::IsSupported(SSE2)) {
     CpuFeatureScope scope(masm(), SSE2);
-    __ cvtsi2sd(ToDoubleRegister(output), ToOperand(input));
+    __ Cvtsi2sd(ToDoubleRegister(output), ToOperand(input));
   } else if (input->IsRegister()) {
     Register input_reg = ToRegister(input);
     __ push(input_reg);
     X87Mov(ToX87Register(output), Operand(esp, 0), kX87IntOperand);
     __ pop(input_reg);
   } else {
     X87Mov(ToX87Register(output), ToOperand(input), kX87IntOperand);
   }
 }
 
@@ skipping 88 matching lines @@
   Label done;
 
   if (signedness == SIGNED_INT32) {
     // There was overflow, so bits 30 and 31 of the original integer
     // disagree. Try to allocate a heap number in new space and store
     // the value in there. If that fails, call the runtime system.
     __ SmiUntag(reg);
     __ xor_(reg, 0x80000000);
     if (CpuFeatures::IsSupported(SSE2)) {
       CpuFeatureScope feature_scope(masm(), SSE2);
-      __ cvtsi2sd(xmm0, Operand(reg));
+      __ Cvtsi2sd(xmm0, Operand(reg));
     } else {
       __ push(reg);
       __ fild_s(Operand(esp, 0));
       __ pop(reg);
     }
   } else {
     if (CpuFeatures::IsSupported(SSE2)) {
       CpuFeatureScope feature_scope(masm(), SSE2);
       __ LoadUint32(xmm0, reg,
                     ToDoubleRegister(LNumberTagU::cast(instr)->temp()));
@@ skipping 244 matching lines @@
       DeoptimizeIf(not_zero, env);
     }
     __ jmp(&done, Label::kNear);
   } else {
     ASSERT(mode == NUMBER_CANDIDATE_IS_SMI);
   }
 
   // Smi to XMM conversion
   __ bind(&load_smi);
   __ SmiUntag(input_reg);  // Untag smi before converting to float.
-  __ cvtsi2sd(result_reg, Operand(input_reg));
+  __ Cvtsi2sd(result_reg, Operand(input_reg));
   __ SmiTag(input_reg);  // Retag smi.
   __ bind(&done);
 }
 
 
 void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr, Label* done) {
   Register input_reg = ToRegister(instr->value());
 
 
   if (instr->truncating()) {
@@ skipping 988 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32