Harmony: optimize Math.clz32.

src/a64/lithium-codegen-a64.cc

 // Copyright 2013 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 3834 matching lines @@
 
 void LCodeGen::DoMathLog(LMathLog* instr) {
   ASSERT(instr->IsMarkedAsCall());
   ASSERT(ToDoubleRegister(instr->value()).is(d0));
   __ CallCFunction(ExternalReference::math_log_double_function(isolate()),
                    0, 1);
   ASSERT(ToDoubleRegister(instr->result()).Is(d0));
 }
 
 
+void LCodeGen::DoMathClz32(LMathClz32* instr) {
+  Register input = ToRegister32(instr->value());
+  Register result = ToRegister32(instr->result());
+  __ Clz(result, input);
+}
+
+
 void LCodeGen::DoMathPowHalf(LMathPowHalf* instr) {
   DoubleRegister input = ToDoubleRegister(instr->value());
   DoubleRegister result = ToDoubleRegister(instr->result());
   Label done;
 
   // Math.pow(x, 0.5) differs from fsqrt(x) in the following cases:
   //  Math.pow(-Infinity, 0.5) == +Infinity
   //  Math.pow(-0.0, 0.5) == +0.0
 
   // Catch -infinity inputs first.
@@ skipping 1818 matching lines @@
   __ Bind(&out_of_object);
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal