[turbofan] Turn Math.clz32 into an inlinable 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/v8.h"
 
 #include "src/arguments.h"
 #include "src/assembler.h"
 #include "src/codegen.h"
 #include "src/runtime/runtime-utils.h"
@@ skipping 94 matching lines @@
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   isolate->counters()->math_exp()->Increment();
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   lazily_initialize_fast_exp();
   return *isolate->factory()->NewNumber(fast_exp(x));
 }
 
 
+RUNTIME_FUNCTION(Runtime_MathClz32) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  isolate->counters()->math_clz32()->Increment();
+
+  CONVERT_NUMBER_CHECKED(uint32_t, x, Uint32, args[0]);
+  return *isolate->factory()->NewNumberFromUint(
+      base::bits::CountLeadingZeros32(x));
+}
+
+
 RUNTIME_FUNCTION(Runtime_MathFloor) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   isolate->counters()->math_floor()->Increment();
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   return *isolate->factory()->NewNumber(Floor(x));
 }
 
 
@@ skipping 111 matching lines @@
 RUNTIME_FUNCTION(Runtime_IsMinusZero) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(Object, obj, 0);
   if (!obj->IsHeapNumber()) return isolate->heap()->false_value();
   HeapNumber* number = HeapNumber::cast(obj);
   return isolate->heap()->ToBoolean(IsMinusZero(number->value()));
 }
 }
 }  // namespace v8::internal