[heap] Fine-grained JSArrayBuffer tracking

include/v8.h

 // Copyright 2012 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.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 7325 matching lines @@
   static const int kContextEmbedderDataIndex = 5;
   static const int kFullStringRepresentationMask = 0x07;
   static const int kStringEncodingMask = 0x4;
   static const int kExternalTwoByteRepresentationTag = 0x02;
   static const int kExternalOneByteRepresentationTag = 0x06;
 
   static const int kIsolateEmbedderDataOffset = 0 * kApiPointerSize;
   static const int kAmountOfExternalAllocatedMemoryOffset =
       4 * kApiPointerSize;
   static const int kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset =
-      kAmountOfExternalAllocatedMemoryOffset + kApiInt64Size;
+      kAmountOfExternalAllocatedMemoryOffset + kApiPointerSize;
   static const int kIsolateRootsOffset =
-      kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset + kApiInt64Size +
+      kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset + kApiPointerSize +
       kApiPointerSize;
   static const int kUndefinedValueRootIndex = 4;
   static const int kTheHoleValueRootIndex = 5;
   static const int kNullValueRootIndex = 6;
   static const int kTrueValueRootIndex = 7;
   static const int kFalseValueRootIndex = 8;
   static const int kEmptyStringRootIndex = 9;
 
   // The external allocation limit should be below 256 MB on all architectures
   // to avoid that resource-constrained embedders run low on memory.
@@ skipping 1186 matching lines @@
 
 uint32_t Isolate::GetNumberOfDataSlots() {
   typedef internal::Internals I;
   return I::kNumIsolateDataSlots;
 }
 
 
 int64_t Isolate::AdjustAmountOfExternalAllocatedMemory(
     int64_t change_in_bytes) {
   typedef internal::Internals I;
-  int64_t* amount_of_external_allocated_memory =
-      reinterpret_cast<int64_t*>(reinterpret_cast<uint8_t*>(this) +
-                                 I::kAmountOfExternalAllocatedMemoryOffset);
-  int64_t* amount_of_external_allocated_memory_at_last_global_gc =
-      reinterpret_cast<int64_t*>(
+  intptr_t* amount_of_external_allocated_memory =
+      reinterpret_cast<intptr_t*>(reinterpret_cast<uint8_t*>(this) +
+                                  I::kAmountOfExternalAllocatedMemoryOffset);
+  intptr_t* amount_of_external_allocated_memory_at_last_global_gc =
+      reinterpret_cast<intptr_t*>(

[Michael Lippautz, 2016/05/11 08:22:51]

It's really unfortunate that we require this magic here but experience shows
that we should have this fast path in the header.

Note that we cast an atomic value to intptr_t and use it as a counter. Happy for
any suggestions.

           reinterpret_cast<uint8_t*>(this) +
           I::kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset);
-  int64_t amount = *amount_of_external_allocated_memory + change_in_bytes;
+  intptr_t amount = *amount_of_external_allocated_memory +
+                    static_cast<intptr_t>(change_in_bytes);
   if (change_in_bytes > 0 &&
       amount - *amount_of_external_allocated_memory_at_last_global_gc >
           I::kExternalAllocationLimit) {
     ReportExternalAllocationLimitReached();
   }
   *amount_of_external_allocated_memory = amount;
   return *amount_of_external_allocated_memory;
 }
 
 
@@ skipping 159 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_