[turbofan] Turn Math.clz32 into an inlinable builtin.

src/math.js

 // Copyright 2012 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.
 
 var rngstate;  // Initialized to a Uint32Array during genesis.
 
 var $abs;
 var $exp;
 var $floor;
 var $max;
@@ skipping 234 matching lines @@
   }
   return %_MathSqrt(sum) * max;
 }
 
 // ES6 draft 09-27-13, section 20.2.2.16.
 function MathFroundJS(x) {
   return %MathFround(TO_NUMBER_INLINE(x));
 }
 
 // ES6 draft 07-18-14, section 20.2.2.11
-function MathClz32(x) {
-  x = ToUint32(TO_NUMBER_INLINE(x));
-  if (x == 0) return 32;
-  var result = 0;
-  // Binary search.
-  if ((x & 0xFFFF0000) === 0) { x <<= 16; result += 16; };
-  if ((x & 0xFF000000) === 0) { x <<=  8; result +=  8; };
-  if ((x & 0xF0000000) === 0) { x <<=  4; result +=  4; };
-  if ((x & 0xC0000000) === 0) { x <<=  2; result +=  2; };
-  if ((x & 0x80000000) === 0) { x <<=  1; result +=  1; };
-  return result;
+function MathClz32JS(x) {
+  return %_MathClz32(x >>> 0);
 }
 
 // ES6 draft 09-27-13, section 20.2.2.9.
 // Cube root approximation, refer to: http://metamerist.com/cbrt/cbrt.htm
 // Using initial approximation adapted from Kahan's cbrt and 4 iterations
 // of Newton's method.
 function MathCbrt(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
   if (x == 0 || !NUMBER_IS_FINITE(x)) return x;
   return x >= 0 ? CubeRoot(x) : -CubeRoot(-x);
@@ skipping 62 matching lines @@
   "min", MathMin,
   "imul", MathImul,
   "sign", MathSign,
   "trunc", MathTrunc,
   "tanh", MathTanh,
   "asinh", MathAsinh,
   "acosh", MathAcosh,
   "atanh", MathAtanh,
   "hypot", MathHypot,
   "fround", MathFroundJS,
-  "clz32", MathClz32,
+  "clz32", MathClz32JS,
   "cbrt", MathCbrt
 ));
 
 %SetInlineBuiltinFlag(MathAbs);
 %SetInlineBuiltinFlag(MathCeil);
+%SetInlineBuiltinFlag(MathClz32JS);
 %SetInlineBuiltinFlag(MathFloorJS);
 %SetInlineBuiltinFlag(MathRandom);
 %SetInlineBuiltinFlag(MathSqrtJS);
 
 // Expose to the global scope.
 $abs = MathAbs;
 $exp = MathExp;
 $floor = MathFloorJS;
 $max = MathMax;
 $min = MathMin;
 
 })();