Collect array buffer allocation sizes for UMA in megabytes.

src/objects.cc

 // 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.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 19445 matching lines @@
   // are currently being constructed in the |ArrayBufferTracker|. The
   // registration method below handles the case of registering a buffer that has
   // already been promoted.
   array_buffer->set_backing_store(data);
 
   if (data && !is_external) {
     isolate->heap()->RegisterNewArrayBuffer(*array_buffer);
   }
 }
 
+namespace {
+
+inline int ConvertToMb(size_t size) {
+  return static_cast<int>(size / static_cast<size_t>(MB));
+}
+
+}  // namespace
 
 bool JSArrayBuffer::SetupAllocatingData(Handle<JSArrayBuffer> array_buffer,
                                         Isolate* isolate,
                                         size_t allocated_length,
                                         bool initialize, SharedFlag shared) {
   void* data;
   CHECK(isolate->array_buffer_allocator() != NULL);
   // Prevent creating array buffers when serializing.
   DCHECK(!isolate->serializer_enabled());
   if (allocated_length != 0) {
-    constexpr size_t kMinBigAllocation = 1 << 20;
-    if (allocated_length >= kMinBigAllocation) {
-      isolate->counters()->array_buffer_big_allocations()->AddSample(
-          sizeof(uint64_t) * kBitsPerByte -
-          base::bits::CountLeadingZeros64(allocated_length));
-    }
+    isolate->counters()->array_buffer_big_allocations()->AddSample(
+        ConvertToMb(allocated_length));
     if (initialize) {
       data = isolate->array_buffer_allocator()->Allocate(allocated_length);
     } else {
       data = isolate->array_buffer_allocator()->AllocateUninitialized(
           allocated_length);
     }
     if (data == NULL) {
       isolate->counters()->array_buffer_new_size_failures()->AddSample(
-          sizeof(uint64_t) * kBitsPerByte -
-          base::bits::CountLeadingZeros64(allocated_length));
+          ConvertToMb(allocated_length));
       return false;
     }
   } else {
     data = NULL;
   }
 
   JSArrayBuffer::Setup(array_buffer, isolate, false, data, allocated_length,
                        shared);
   return true;
 }
@@ skipping 918 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8