MIPS: Harmony: optimize Math.clz32.

Port r19487 (bd8c70f)

BUG=v8:2938
LOG=N
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/172533002

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19499 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-codegen-mips.cc

@@ -3796,6 +3796,13 @@ void LCodeGen::DoMathLog(LMathLog* instr) {
 }
 
 
+void LCodeGen::DoMathClz32(LMathClz32* instr) {
+  Register input = ToRegister(instr->value());
+  Register result = ToRegister(instr->result());
+  __ Clz(result, input);
+}
+
+
 void LCodeGen::DoInvokeFunction(LInvokeFunction* instr) {
   ASSERT(ToRegister(instr->context()).is(cp));
   ASSERT(ToRegister(instr->function()).is(a1));

src/mips/lithium-mips.cc

@@ -1101,6 +1101,7 @@ 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;
@@ -1116,6 +1117,13 @@ 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());

src/mips/lithium-mips.h

@@ -125,6 +125,7 @@ class LCodeGen;
   V(MapEnumLength)                              \
   V(MathAbs)                                    \
   V(MathExp)                                    \
+  V(MathClz32)                                  \
   V(MathFloor)                                  \
   V(MathFloorOfDiv)                             \
   V(MathLog)                                    \
@@ -802,6 +803,18 @@ class LMathLog V8_FINAL : public LTemplateInstruction<1, 1, 0> {
 };
 
 
+class LMathClz32 V8_FINAL : public LTemplateInstruction<1, 1, 0> {
+ public:
+  explicit LMathClz32(LOperand* value) {
+    inputs_[0] = value;
+  }
+
+  LOperand* value() { return inputs_[0]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(MathClz32, "math-clz32")
+};
+
+
 class LMathExp V8_FINAL : public LTemplateInstruction<1, 1, 3> {
  public:
   LMathExp(LOperand* value,
@@ -2578,6 +2591,7 @@ class LChunkBuilder V8_FINAL : public LChunkBuilderBase {
   LInstruction* DoMathExp(HUnaryMathOperation* instr);
   LInstruction* DoMathSqrt(HUnaryMathOperation* instr);
   LInstruction* DoMathPowHalf(HUnaryMathOperation* instr);
+  LInstruction* DoMathClz32(HUnaryMathOperation* instr);
 
  private:
   enum Status {