[heap] Fine-grained JSArrayBuffer tracking

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 113518da02e71c6286ad5d120435a61bc2240bb4..cad94170276f50d53e6f5eb4d7564ab10a491779 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -14,7 +14,7 @@
 #include "src/frames-inl.h"
 #include "src/gdb-jit.h"
 #include "src/global-handles.h"
-#include "src/heap/array-buffer-tracker.h"
+#include "src/heap/array-buffer-tracker-inl.h"
 #include "src/heap/gc-tracer.h"
 #include "src/heap/incremental-marking.h"
 #include "src/heap/mark-compact-inl.h"
@@ -870,6 +870,10 @@ void MarkCompactCollector::Prepare() {
        space = spaces.next()) {
     space->PrepareForMarkCompact();
   }
+  if (!was_marked_incrementally_) {
+    heap()->old_space()->ForAllPages([](Page* p) { p->ResetTracker(); });
+  }
+  heap()->account_amount_of_external_allocated_freed_memory();
 
 #ifdef VERIFY_HEAP
   if (!was_marked_incrementally_ && FLAG_verify_heap) {
@@ -1725,20 +1729,12 @@ class MarkCompactCollector::EvacuateNewSpaceVisitor final
     if (heap_->ShouldBePromoted(object->address(), size) &&
         TryEvacuateObject(compaction_spaces_->Get(OLD_SPACE), object,
                           &target_object)) {
-      // If we end up needing more special cases, we should factor this out.

[Hannes Payer (out of office), 2016/05/20 12:21:17]

Nice!

-      if (V8_UNLIKELY(target_object->IsJSArrayBuffer())) {
-        heap_->array_buffer_tracker()->Promote(
-            JSArrayBuffer::cast(target_object));
-      }
       promoted_size_ += size;
       return true;
     }
     HeapObject* target = nullptr;
     AllocationSpace space = AllocateTargetObject(object, &target);
     MigrateObject(HeapObject::cast(target), object, size, space);
-    if (V8_UNLIKELY(target->IsJSArrayBuffer())) {
-      heap_->array_buffer_tracker()->MarkLive(JSArrayBuffer::cast(target));
-    }
     semispace_copied_size_ += size;
     return true;
   }
@@ -1863,10 +1859,6 @@ class MarkCompactCollector::EvacuateNewSpacePageVisitor final
   }
 
   inline bool Visit(HeapObject* object) {
-    if (V8_UNLIKELY(object->IsJSArrayBuffer())) {
-      object->GetHeap()->array_buffer_tracker()->Promote(
-          JSArrayBuffer::cast(object));
-    }
     RecordMigratedSlotVisitor visitor(heap_->mark_compact_collector());
     object->IterateBodyFast(&visitor);
     promoted_size_ += object->Size();
@@ -1907,6 +1899,9 @@ class MarkCompactCollector::EvacuateRecordOnlyVisitor final
   inline bool Visit(HeapObject* object) {
     RecordMigratedSlotVisitor visitor(heap_->mark_compact_collector());
     object->IterateBody(&visitor);
+    if (V8_UNLIKELY(object->IsJSArrayBuffer())) {
+      heap_->array_buffer_tracker()->MarkLive(JSArrayBuffer::cast(object));
+    }
     return true;
   }
 
@@ -3233,21 +3228,27 @@ bool MarkCompactCollector::Evacuator::EvacuatePage(Page* page) {
   switch (ComputeEvacuationMode(page)) {
     case kObjectsNewToOld:
       result = EvacuateSinglePage<kClearMarkbits>(page, &new_space_visitor_);
+      page->ScanAndFreeDeadArrayBuffers<
+          LocalArrayBufferTracker::kForwardingPointer>();
       DCHECK(result);
       USE(result);
       break;
     case kPageNewToOld:
       result = EvacuateSinglePage<kKeepMarking>(page, &new_space_page_visitor);
+      // ArrayBufferTracker will be updated during sweeping.
       DCHECK(result);
       USE(result);
       break;
     case kObjectsOldToOld:
       result = EvacuateSinglePage<kClearMarkbits>(page, &old_space_visitor_);
+      page->ScanAndFreeDeadArrayBuffers<
+          LocalArrayBufferTracker::kForwardingPointer>();
       if (!result) {
         // Aborted compaction page. We can record slots here to have them
         // processed in parallel later on.
         EvacuateRecordOnlyVisitor record_visitor(collector_->heap());
         result = EvacuateSinglePage<kKeepMarking>(page, &record_visitor);
+        page->ScanAndFreeDeadArrayBuffers<LocalArrayBufferTracker::kMarkBit>();
         DCHECK(result);
         USE(result);
         // We need to return failure here to indicate that we want this page
@@ -3489,6 +3490,7 @@ int MarkCompactCollector::Sweeper::RawSweep(PagedSpace* space, Page* p,
     freed_bytes = space->UnaccountedFree(free_start, size);
     max_freed_bytes = Max(freed_bytes, max_freed_bytes);
   }
+  p->FreeDeadArrayBuffers();
   p->concurrent_sweeping_state().SetValue(Page::kSweepingDone);
   return FreeList::GuaranteedAllocatable(static_cast<int>(max_freed_bytes));
 }
@@ -3631,11 +3633,6 @@ void MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
       }
     }
 
-    // EvacuateNewSpaceAndCandidates iterates over new space objects and for
-    // ArrayBuffers either re-registers them as live or promotes them. This is
-    // needed to properly free them.
-    heap()->array_buffer_tracker()->FreeDead(false);
-
     // Deallocate evacuated candidate pages.
     ReleaseEvacuationCandidates();
   }