Track large array buffer allocations.

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 19455 matching lines @@
 
 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));
+    }
     if (initialize) {
       data = isolate->array_buffer_allocator()->Allocate(allocated_length);
     } else {
       data = isolate->array_buffer_allocator()->AllocateUninitialized(
           allocated_length);
     }
     if (data == NULL) return false;
   } else {
     data = NULL;
   }
@@ skipping 923 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8