x64: Fix LMathMinMax for constant Smi right-hand operands

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index e77e657671e9b1d2b2a713a244f7d0a14a13b867..7a9e86edd10a4b0001e9dcd5d6647120b3235d22 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1435,15 +1435,16 @@ LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
 LInstruction* LChunkBuilder::DoMathMinMax(HMathMinMax* instr) {
   LOperand* left = NULL;
   LOperand* right = NULL;
-  if (instr->representation().IsSmiOrInteger32()) {
-    ASSERT(instr->left()->representation().Equals(instr->representation()));
-    ASSERT(instr->right()->representation().Equals(instr->representation()));
+  ASSERT(instr->left()->representation().Equals(instr->representation()));
+  ASSERT(instr->right()->representation().Equals(instr->representation()));
+  if (instr->representation().IsSmi()) {
+    left = UseRegisterAtStart(instr->BetterLeftOperand());
+    right = UseAtStart(instr->BetterRightOperand());
+  } else if (instr->representation().IsInteger32()) {
     left = UseRegisterAtStart(instr->BetterLeftOperand());
     right = UseOrConstantAtStart(instr->BetterRightOperand());
   } else {
     ASSERT(instr->representation().IsDouble());
-    ASSERT(instr->left()->representation().IsDouble());
-    ASSERT(instr->right()->representation().IsDouble());
     left = UseRegisterAtStart(instr->left());
     right = UseRegisterAtStart(instr->right());
   }