Revert "Track committed array buffer size rather than allocation length"

This reverts commit b0ced926.

Reason for revert: Build breakage - https://build.chromium.org/p/client.v8/builders/V8%20Linux/builds/20832

Original change's description:
> Track committed array buffer size rather than allocation length
> 
> WebAssembly creates ArrayBuffers with large allocations where only a small
> amount is committed. The uncommitted address space should not be counted as used
> memory. Doing so can lead to the GC spending unnecessary time collecting memory
> when there is not really pressure.
> 
> Bug: 
> Change-Id: Ife7b84e9858e87faabc360a61f887b2fda6d99db
> Reviewed-on: https://chromium-review.googlesource.com/710227
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Eric Holk <eholk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48462}

TBR=mlippautz@chromium.org,eholk@chromium.org

Change-Id: Ib7b28a7bbc8ffc11e0bf8c4bb16b2da61cbdbd5f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/712835Reviewed-by: Eric Holk <eholk@chromium.org>
Commit-Queue: Eric Holk <eholk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48466}

src/heap/array-buffer-tracker-inl.h

@@ -17,7 +17,7 @@ void ArrayBufferTracker::RegisterNew(Heap* heap, JSArrayBuffer* buffer) {
   void* data = buffer->backing_store();
   if (!data) return;
 
-  size_t length = static_cast<size_t>(buffer->byte_length()->Number());
+  size_t length = buffer->allocation_length();
   Page* page = Page::FromAddress(buffer->address());
   {
     base::LockGuard<base::RecursiveMutex> guard(page->mutex());
@@ -40,7 +40,7 @@ void ArrayBufferTracker::Unregister(Heap* heap, JSArrayBuffer* buffer) {
   if (!data) return;
 
   Page* page = Page::FromAddress(buffer->address());
-  size_t length = static_cast<size_t>(buffer->byte_length()->Number());
+  size_t length = buffer->allocation_length();
   {
     base::LockGuard<base::RecursiveMutex> guard(page->mutex());
     LocalArrayBufferTracker* tracker = page->local_tracker();
@@ -50,22 +50,6 @@ void ArrayBufferTracker::Unregister(Heap* heap, JSArrayBuffer* buffer) {
   heap->update_external_memory(-static_cast<intptr_t>(length));
 }
 
-void ArrayBufferTracker::IncreaseArrayBufferSize(Heap* heap,
-                                                 JSArrayBuffer* buffer,
-                                                 size_t delta) {
-  DCHECK_NOT_NULL(buffer->backing_store());
-
-  Page* const page = Page::FromAddress(buffer->address());
-  {
-    base::LockGuard<base::RecursiveMutex> guard(page->mutex());
-    LocalArrayBufferTracker* tracker = page->local_tracker();
-    DCHECK_NOT_NULL(tracker);
-    DCHECK(tracker->IsTracked(buffer));
-    tracker->IncreaseRetainedSize(delta);
-  }
-  heap->update_external_memory(delta);
-}
-
 template <typename Callback>
 void LocalArrayBufferTracker::Free(Callback should_free) {
   size_t freed_memory = 0;
@@ -73,7 +57,7 @@ void LocalArrayBufferTracker::Free(Callback should_free) {
   for (TrackingData::iterator it = array_buffers_.begin();
        it != array_buffers_.end();) {
     JSArrayBuffer* buffer = reinterpret_cast<JSArrayBuffer*>(*it);
-    const size_t length = static_cast<size_t>(buffer->byte_length()->Number());
+    const size_t length = buffer->allocation_length();
     if (should_free(buffer)) {
       freed_memory += length;
       buffer->FreeBackingStore();
@@ -122,11 +106,6 @@ void LocalArrayBufferTracker::Remove(JSArrayBuffer* buffer, size_t length) {
   array_buffers_.erase(it);
 }
 
-void LocalArrayBufferTracker::IncreaseRetainedSize(size_t delta) {
-  DCHECK_GE(retained_size_ + delta, retained_size_);
-  retained_size_ += delta;
-}
-
 }  // namespace internal
 }  // namespace v8
 

src/heap/array-buffer-tracker.h

@@ -33,10 +33,6 @@ class ArrayBufferTracker : public AllStatic {
   // access to the tracker by taking the page lock for the corresponding page.
   inline static void RegisterNew(Heap* heap, JSArrayBuffer* buffer);
   inline static void Unregister(Heap* heap, JSArrayBuffer* buffer);
-  // Tells the tracker that the array buffer has increased in size. The buffer
-  // must already be tracked.
-  inline static void IncreaseArrayBufferSize(Heap* heap, JSArrayBuffer* buffer,
-                                             size_t delta);
 
   // Frees all backing store pointers for dead JSArrayBuffers in new space.
   // Does not take any locks and can only be called during Scavenge.
@@ -77,7 +73,6 @@ class LocalArrayBufferTracker {
 
   inline void Add(JSArrayBuffer* buffer, size_t length);
   inline void Remove(JSArrayBuffer* buffer, size_t length);
-  inline void IncreaseRetainedSize(size_t delta);
 
   // Frees up array buffers.
   //

src/heap/heap.cc

@@ -2323,10 +2323,6 @@ void Heap::UnregisterArrayBuffer(JSArrayBuffer* buffer) {
   ArrayBufferTracker::Unregister(this, buffer);
 }
 
-void Heap::TrackIncreasedArrayBufferSize(JSArrayBuffer* buffer, size_t delta) {
-  ArrayBufferTracker::IncreaseArrayBufferSize(this, buffer, delta);
-}
-
 void Heap::ConfigureInitialOldGenerationSize() {
   if (!old_generation_size_configured_ && tracer()->SurvivalEventsRecorded()) {
     old_generation_allocation_limit_ =

src/heap/heap.h

@@ -1473,7 +1473,6 @@ class Heap {
   // unregistered buffer, too, and the name is confusing.
   void RegisterNewArrayBuffer(JSArrayBuffer* buffer);
   void UnregisterArrayBuffer(JSArrayBuffer* buffer);
-  void TrackIncreasedArrayBufferSize(JSArrayBuffer* buffer, size_t delta);
 
   // ===========================================================================
   // Allocation site tracking. =================================================

src/wasm/wasm-objects.cc

@@ -331,9 +331,8 @@ Handle<JSArrayBuffer> GrowMemoryBuffer(Isolate* isolate,
   const bool enable_guard_regions = old_buffer.is_null()
                                         ? trap_handler::UseTrapHandler()
                                         : old_buffer->has_guard_region();
-
-  const uint32_t size_increase = pages * WasmModule::kPageSize;
-  const uint32_t new_size = old_size + size_increase;
+  size_t new_size =
+      static_cast<size_t>(old_pages + pages) * WasmModule::kPageSize;
   if (enable_guard_regions && old_size != 0) {
     DCHECK_NOT_NULL(old_buffer->backing_store());
     if (new_size > FLAG_wasm_max_mem_pages * WasmModule::kPageSize ||
@@ -347,10 +346,6 @@ Handle<JSArrayBuffer> GrowMemoryBuffer(Isolate* isolate,
         ->AdjustAmountOfExternalAllocatedMemory(pages * WasmModule::kPageSize);
     Handle<Object> length_obj = isolate->factory()->NewNumberFromSize(new_size);
     old_buffer->set_byte_length(*length_obj);
-    if (!old_buffer->is_external()) {
-      isolate->heap()->TrackIncreasedArrayBufferSize(*old_buffer,
-                                                     size_increase);
-    }
     return old_buffer;
   } else {
     Handle<JSArrayBuffer> new_buffer;