[heap] ObjectStats: Use ieee754 log2

src/heap/object-stats.h

 // Copyright 2015 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.
 
 #ifndef V8_HEAP_OBJECT_STATS_H_
 #define V8_HEAP_OBJECT_STATS_H_
 
-#include <math.h>
-
+#include "src/base/ieee754.h"
 #include "src/heap/heap.h"
 #include "src/heap/objects-visiting.h"
 #include "src/objects.h"
 
 namespace v8 {
 namespace internal {
 
 class ObjectStats {
  public:
   explicit ObjectStats(Heap* heap) : heap_(heap) { ClearObjectStats(); }
@@ skipping 65 matching lines @@
 
  private:
   static const int kFirstBucketShift = 5;  // <=32
   static const int kLastBucketShift = 19;  // >512k
   static const int kFirstBucket = 1 << kFirstBucketShift;
   static const int kLastBucket = 1 << kLastBucketShift;
   static const int kNumberOfBuckets = kLastBucketShift - kFirstBucketShift;
 
   int HistogramIndexFromSize(size_t size) {
     if (size == 0) return 0;
-    int idx =
-        static_cast<int>(log2(static_cast<double>(size))) - kFirstBucketShift;
+    int idx = static_cast<int>(base::ieee754::log2(static_cast<double>(size))) -
+              kFirstBucketShift;
     return idx < 0 ? 0 : idx;
   }
 
   Heap* heap_;
   // Object counts and used memory by InstanceType.
   size_t object_counts_[OBJECT_STATS_COUNT];
   size_t object_counts_last_time_[OBJECT_STATS_COUNT];
   size_t object_sizes_[OBJECT_STATS_COUNT];
   size_t object_sizes_last_time_[OBJECT_STATS_COUNT];
   // Approximation of overallocated memory by InstanceType.
@@ skipping 19 matching lines @@
   static void RecordJSObjectDetails(ObjectStats* stats, Heap* heap,
                                     JSObject* object);
   static void RecordJSWeakCollectionDetails(ObjectStats* stats, Heap* heap,
                                             JSWeakCollection* obj);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_OBJECT_STATS_H_