Harmony: optimize Math.clz32.

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 e342acbcb83cb5538f08d11c8e48ba319a9bbaa2..d42d3824e2f37d2b9ee94888e0d4c8bbcc8eb286 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1106,6 +1106,7 @@ LInstruction* LChunkBuilder::DoUnaryMathOperation(HUnaryMathOperation* instr) {
     case kMathExp: return DoMathExp(instr);
     case kMathSqrt: return DoMathSqrt(instr);
     case kMathPowHalf: return DoMathPowHalf(instr);
+    case kMathClz32: return DoMathClz32(instr);
     default:
       UNREACHABLE();
       return NULL;
@@ -1143,6 +1144,13 @@ LInstruction* LChunkBuilder::DoMathLog(HUnaryMathOperation* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoMathClz32(HUnaryMathOperation* instr) {
+  LOperand* input = UseRegisterAtStart(instr->value());
+  LMathClz32* result = new(zone()) LMathClz32(input);
+  return DefineAsRegister(result);
+}
+
+
 LInstruction* LChunkBuilder::DoMathExp(HUnaryMathOperation* instr) {
   ASSERT(instr->representation().IsDouble());
   ASSERT(instr->value()->representation().IsDouble());