Fix Smi-based MathMinMax on x64, and reenable smi mode.

src/x64/lithium-x64.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 1544 matching lines @@
     ASSERT(instr->representation().IsTagged());
     return DoArithmeticT(Token::ADD, instr);
   }
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoMathMinMax(HMathMinMax* instr) {
   LOperand* left = NULL;
   LOperand* right = NULL;
-  if (instr->representation().IsInteger32()) {
-    ASSERT(instr->left()->representation().IsInteger32());
-    ASSERT(instr->right()->representation().IsInteger32());
+  if (instr->representation().IsSmiOrInteger32()) {
+    ASSERT(instr->left()->representation().Equals(instr->representation()));
+    ASSERT(instr->right()->representation().Equals(instr->representation()));
     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());
   }
   LMathMinMax* minmax = new(zone()) LMathMinMax(left, right);
@@ skipping 985 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_X64