[heap] Pause black allocation during GCs

src/heap/spaces.cc

 // Copyright 2011 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/heap/spaces.h"
 
 #include <utility>
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
@@ skipping 831 matching lines @@
   DCHECK(heap()->incremental_marking()->black_allocation());
   DCHECK_EQ(Page::FromAddress(start), this);
   DCHECK_NE(start, end);
   DCHECK_EQ(Page::FromAddress(end - 1), this);
   MarkingState::Internal(this).bitmap()->SetRange(AddressToMarkbitIndex(start),
                                                   AddressToMarkbitIndex(end));
   MarkingState::Internal(this).IncrementLiveBytes(
       static_cast<int>(end - start));
 }
 
+void Page::DestroyBlackArea(Address start, Address end) {
+  DCHECK(heap()->incremental_marking()->black_allocation());
+  DCHECK_EQ(Page::FromAddress(start), this);
+  DCHECK_NE(start, end);
+  DCHECK_EQ(Page::FromAddress(end - 1), this);
+  MarkingState::Internal(this).bitmap()->ClearRange(
+      AddressToMarkbitIndex(start), AddressToMarkbitIndex(end));
+  MarkingState::Internal(this).IncrementLiveBytes(
+      -static_cast<int>(end - start));
+}
+
 void MemoryAllocator::PartialFreeMemory(MemoryChunk* chunk,
                                         Address start_free) {
   // We do not allow partial shrink for code.
   DCHECK(chunk->executable() == NOT_EXECUTABLE);
 
   intptr_t size;
   base::VirtualMemory* reservation = chunk->reserved_memory();
   DCHECK(reservation->IsReserved());
   size = static_cast<intptr_t>(reservation->size());
 
@@ skipping 544 matching lines @@
 void PagedSpace::MarkAllocationInfoBlack() {
   DCHECK(heap()->incremental_marking()->black_allocation());
   Address current_top = top();
   Address current_limit = limit();
   if (current_top != nullptr && current_top != current_limit) {
     Page::FromAllocationAreaAddress(current_top)
         ->CreateBlackArea(current_top, current_limit);
   }
 }
 
+void PagedSpace::UnmarkAllocationInfo() {
+  Address current_top = top();
+  Address current_limit = limit();
+  if (current_top != nullptr && current_top != current_limit) {
+    Page::FromAllocationAreaAddress(current_top)
+        ->DestroyBlackArea(current_top, current_limit);
+  }
+}
+
 // Empty space allocation info, returning unused area to free list.
 void PagedSpace::EmptyAllocationInfo() {
   // Mark the old linear allocation area with a free space map so it can be
   // skipped when scanning the heap.
   Address current_top = top();
   Address current_limit = limit();
   if (current_top == nullptr) {
     DCHECK(current_limit == nullptr);
     return;
   }
@@ skipping 1876 matching lines @@
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %" V8PRIdPTR "\n", mark_size,
          MarkingState::Internal(this).live_bytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8