[builtins] Migrate Math.clz32 to a TurboFan builtin.

src/runtime/runtime-maths.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/assembler.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/bootstrapper.h"
@@ skipping 90 matching lines @@
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   isolate->counters()->math_exp_runtime()->Increment();
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   lazily_initialize_fast_exp(isolate);
   return *isolate->factory()->NewNumber(fast_exp(x, isolate));
 }
 
 
-RUNTIME_FUNCTION(Runtime_MathClz32) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 1);
-  isolate->counters()->math_clz32_runtime()->Increment();
-
-  CONVERT_NUMBER_CHECKED(uint32_t, x, Uint32, args[0]);
-  return *isolate->factory()->NewNumberFromUint(
-      base::bits::CountLeadingZeros32(x));
-}
-
-
 // Slow version of Math.pow.  We check for fast paths for special cases.
 // Used if VFP3 is not available.
 RUNTIME_FUNCTION(Runtime_MathPow) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   isolate->counters()->math_pow_runtime()->Increment();
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
 
   // If the second argument is a smi, it is much faster to call the
@@ skipping 79 matching lines @@
     base::RandomNumberGenerator::XorShift128(&state0, &state1);
     array[i] = base::RandomNumberGenerator::ToDouble(state0, state1);
   }
   // Persist current state.
   array[kState0Offset] = uint64_to_double(state0);
   array[kState1Offset] = uint64_to_double(state1);
   return *typed_array;
 }
 }  // namespace internal
 }  // namespace v8