Synchronize on concurrent store buffer entries.

src/heap/mark-compact.cc

 // 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.
 
 #include "src/heap/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 29 matching lines @@
 
 MarkCompactCollector::MarkCompactCollector(Heap* heap)
     :  // NOLINT
 #ifdef DEBUG
       state_(IDLE),
 #endif
       marking_parity_(ODD_MARKING_PARITY),
       compacting_(false),
       was_marked_incrementally_(false),
       sweeping_in_progress_(false),
+      parallel_compaction_in_progress_(false),
       pending_sweeper_jobs_semaphore_(0),
       pending_compaction_jobs_semaphore_(0),
       evacuation_(false),
       migration_slots_buffer_(NULL),
       heap_(heap),
       marking_deque_memory_(NULL),
       marking_deque_memory_committed_(0),
       code_flusher_(NULL),
       have_code_to_deoptimize_(false) {
 }
@@ skipping 2623 matching lines @@
     WeakCell* weak_cell = reinterpret_cast<WeakCell*>(weak_cell_obj);
     weak_cell_obj = weak_cell->next();
     weak_cell->clear_next(heap());
   }
   heap()->set_encountered_weak_cells(Smi::FromInt(0));
 }
 
 
 void MarkCompactCollector::RecordMigratedSlot(Object* value, Address slot) {
   if (heap_->InNewSpace(value)) {
-    heap_->store_buffer()->Mark(slot);
+    if (parallel_compaction_in_progress_) {
+      heap_->store_buffer()->MarkSynchronized(slot);
+    } else {
+      heap_->store_buffer()->Mark(slot);
+    }
   } else if (value->IsHeapObject() && IsOnEvacuationCandidate(value)) {
     SlotsBuffer::AddTo(&slots_buffer_allocator_, &migration_slots_buffer_,
                        reinterpret_cast<Object**>(slot),
                        SlotsBuffer::IGNORE_OVERFLOW);
   }
 }
 
 
 // We scavenge new space simultaneously with sweeping. This is done in two
 // passes.
@@ skipping 602 matching lines @@
     }
 
     // Clear marking bits for current cell.
     *cell = 0;
   }
   p->ResetLiveBytes();
 }
 
 
 void MarkCompactCollector::EvacuatePagesInParallel() {
+  parallel_compaction_in_progress_ = true;
   V8::GetCurrentPlatform()->CallOnBackgroundThread(
       new CompactionTask(heap()), v8::Platform::kShortRunningTask);
 }
 
 
+void MarkCompactCollector::WaitUntilCompactionCompleted() {
+  pending_compaction_jobs_semaphore_.Wait();
+  parallel_compaction_in_progress_ = false;
+}
+
+
 void MarkCompactCollector::EvacuatePages() {
   int npages = evacuation_candidates_.length();
   int abandoned_pages = 0;
   for (int i = 0; i < npages; i++) {
     Page* p = evacuation_candidates_[i];
     DCHECK(p->IsEvacuationCandidate() ||
            p->IsFlagSet(Page::RESCAN_ON_EVACUATION));
     DCHECK(static_cast<int>(p->parallel_sweeping()) ==
            MemoryChunk::SWEEPING_DONE);
     PagedSpace* space = static_cast<PagedSpace*>(p->owner());
@@ skipping 288 matching lines @@
     EvacuationScope evacuation_scope(this);
     EvacuateNewSpace();
   }
 
   {
     GCTracer::Scope gc_scope(heap()->tracer(),
                              GCTracer::Scope::MC_EVACUATE_PAGES);
     EvacuationScope evacuation_scope(this);
     if (FLAG_parallel_compaction) {
       EvacuatePagesInParallel();
-      pending_compaction_jobs_semaphore_.Wait();
+      WaitUntilCompactionCompleted();
     } else {
       EvacuatePages();
     }
   }
 
   // Second pass: find pointers to new space and update them.
   PointersUpdatingVisitor updating_visitor(heap());
 
   {
     GCTracer::Scope gc_scope(heap()->tracer(),
@@ skipping 1090 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }  // namespace internal
 }  // namespace v8