Handle negative input in inlined Math.round on Intel CPUs.

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 39079d338927b11bf32cada962334653dd9a0484..d5cf125eb0b8e6abab408489d494cecae76f16d9 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1145,7 +1145,16 @@ LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
                                                                   input);
     return MarkAsCall(DefineFixedDouble(result, xmm1), instr);
   } else {
-    LOperand* input = UseRegisterAtStart(instr->value());
+    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* context = UseAny(instr->context());  // Deferred use by MathAbs.
     if (op == kMathPowHalf) {
       LOperand* temp = TempRegister();