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

src/compiler/js-builtin-reducer.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/compiler/js-builtin-reducer.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/simplified-operator.h"
 #include "src/objects-inl.h"
@@ skipping 111 matching lines @@
 Reduction JSBuiltinReducer::ReduceMathImul(Node* node) {
   JSCallReduction r(node);
   if (r.InputsMatchTwo(Type::Integral32(), Type::Integral32())) {
     // Math.imul(a:int32, b:int32) -> Int32Mul(a, b)
     Node* value = graph()->NewNode(machine()->Int32Mul(), r.left(), r.right());
     return Replace(value);
   }
   return NoChange();
 }
 
-// ES6 draft 08-24-14, section 20.2.2.16.
+// ES6 section 20.2.2.10 Math.ceil ( x )
 Reduction JSBuiltinReducer::ReduceMathCeil(Node* node) {
   JSCallReduction r(node);
   if (r.InputsMatchOne(Type::Number())) {
     // Math.ceil(a:number) -> NumberCeil(a)
     Node* value = graph()->NewNode(simplified()->NumberCeil(), r.left());
     return Replace(value);
   }
   return NoChange();
 }
 
+// ES6 section 20.2.2.11 Math.clz32 ( x )
+Reduction JSBuiltinReducer::ReduceMathClz32(Node* node) {
+  JSCallReduction r(node);
+  if (r.InputsMatchOne(Type::Unsigned32())) {
+    // Math.clz32(a:unsigned32) -> NumberClz32(a)
+    Node* value = graph()->NewNode(simplified()->NumberClz32(), r.left());
+    return Replace(value);
+  }
+  if (r.InputsMatchOne(Type::Number())) {
+    // Math.clz32(a:number) -> NumberClz32(NumberToUint32(a))
+    Node* value = graph()->NewNode(
+        simplified()->NumberClz32(),
+        graph()->NewNode(simplified()->NumberToUint32(), r.left()));
+    return Replace(value);
+  }
+  return NoChange();
+}
+
 // ES6 draft 08-24-14, section 20.2.2.16.
 Reduction JSBuiltinReducer::ReduceMathFloor(Node* node) {
   JSCallReduction r(node);
   if (r.InputsMatchOne(Type::Number())) {
     // Math.floor(a:number) -> NumberFloor(a)
     Node* value = graph()->NewNode(simplified()->NumberFloor(), r.left());
     return Replace(value);
   }
   return NoChange();
 }
@@ skipping 49 matching lines @@
 
   // Dispatch according to the BuiltinFunctionId if present.
   if (!r.HasBuiltinFunctionId()) return NoChange();
   switch (r.GetBuiltinFunctionId()) {
     case kMathMax:
       reduction = ReduceMathMax(node);
       break;
     case kMathImul:
       reduction = ReduceMathImul(node);
       break;
+    case kMathClz32:
+      reduction = ReduceMathClz32(node);
+      break;
     case kMathCeil:
       reduction = ReduceMathCeil(node);
       break;
     case kMathFloor:
       reduction = ReduceMathFloor(node);
       break;
     case kMathFround:
       reduction = ReduceMathFround(node);
       break;
     case kMathRound:
@@ skipping 33 matching lines @@
 }
 
 
 SimplifiedOperatorBuilder* JSBuiltinReducer::simplified() const {
   return jsgraph()->simplified();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8