[builtins] Introduce proper Float64Log2 and Float64Log10 operators.

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 241 matching lines @@
       value = graph()->NewNode(
           common()->Select(MachineRepresentation::kNone),
           graph()->NewNode(simplified()->NumberLessThan(), input, value), input,
           value);
     }
     return Replace(value);
   }
   return NoChange();
 }
 
+// ES6 section 20.2.2.23 Math.log2 ( x )
+Reduction JSBuiltinReducer::ReduceMathLog2(Node* node) {
+  JSCallReduction r(node);
+  if (r.InputsMatchOne(Type::Number())) {
+    // Math.log2(a:number) -> NumberLog(a)
+    Node* value = graph()->NewNode(simplified()->NumberLog2(), r.left());
+    return Replace(value);
+  }
+  return NoChange();
+}
+
+// ES6 section 20.2.2.22 Math.log10 ( x )
+Reduction JSBuiltinReducer::ReduceMathLog10(Node* node) {
+  JSCallReduction r(node);
+  if (r.InputsMatchOne(Type::Number())) {
+    // Math.log10(a:number) -> NumberLog10(a)
+    Node* value = graph()->NewNode(simplified()->NumberLog10(), r.left());
+    return Replace(value);
+  }
+  return NoChange();
+}
+
 // ES6 section 20.2.2.28 Math.round ( x )
 Reduction JSBuiltinReducer::ReduceMathRound(Node* node) {
   JSCallReduction r(node);
   if (r.InputsMatchOne(Type::PlainPrimitive())) {
     // Math.round(a:plain-primitive) -> NumberRound(ToNumber(a))
     Node* input = ToNumber(r.GetJSCallInput(0));
     Node* value = graph()->NewNode(simplified()->NumberRound(), input);
     return Replace(value);
   }
   return NoChange();
@@ skipping 62 matching lines @@
       break;
     case kMathImul:
       reduction = ReduceMathImul(node);
       break;
     case kMathLog:
       reduction = ReduceMathLog(node);
       break;
     case kMathLog1p:
       reduction = ReduceMathLog1p(node);
       break;
+    case kMathLog2:
+      reduction = ReduceMathLog2(node);
+      break;
+    case kMathLog10:
+      reduction = ReduceMathLog10(node);
+      break;
     case kMathMax:
       reduction = ReduceMathMax(node);
       break;
     case kMathMin:
       reduction = ReduceMathMin(node);
       break;
     case kMathRound:
       reduction = ReduceMathRound(node);
       break;
     case kMathSqrt:
@@ skipping 40 matching lines @@
 }
 
 
 SimplifiedOperatorBuilder* JSBuiltinReducer::simplified() const {
   return jsgraph()->simplified();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8