New page local store buffer.

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/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 2863 matching lines @@
 void MarkCompactCollector::UpdateSlotsRecordedIn(SlotsBuffer* buffer) {
   while (buffer != NULL) {
     UpdateSlots(buffer);
     buffer = buffer->next();
   }
 }
 
 
 static void UpdatePointer(HeapObject** address, HeapObject* object) {
   MapWord map_word = object->map_word();
-  // The store buffer can still contain stale pointers in dead large objects.
+  // The store buffer can still contain stale pointers in large object
+  // or in map spaces.

[Hannes Payer (out of office), 2016/01/20 19:43:00]

Why map space?

[ulan, 2016/01/28 19:07:22]

Clarified the comment.
Since we only filter invalid slots in old space, the store buffer can
still contain stale pointers in large object and in map spaces. Ignore
these pointers here.

   // Ignore these pointers here.
   DCHECK(map_word.IsForwardingAddress() ||
-         object->GetHeap()->lo_space()->FindPage(
-             reinterpret_cast<Address>(address)) != NULL);
+         !object->GetHeap()->old_space()->Contains(
+             reinterpret_cast<Address>(address)));
   if (map_word.IsForwardingAddress()) {
     // Update the corresponding slot.
     *address = map_word.ToForwardingAddress();
   }
 }
 
 
 static String* UpdateReferenceInExternalStringTableEntry(Heap* heap,
                                                          Object** p) {
   MapWord map_word = HeapObject::cast(*p)->map_word();
@@ skipping 312 matching lines @@
         // - Rescan the page as slot recording in the migration buffer only
         //   happens upon moving (which we potentially didn't do).
         // - Leave the page in the list of pages of a space since we could not
         //   fully evacuate it.
         // - Mark them for rescanning for store buffer entries as we otherwise
         //   might have stale store buffer entries that become "valid" again
         //   after reusing the memory. Note that all existing store buffer
         //   entries of such pages are filtered before rescanning.
         DCHECK(p->IsEvacuationCandidate());
         p->SetFlag(Page::COMPACTION_WAS_ABORTED);
-        p->set_scan_on_scavenge(true);
         abandoned_pages++;
         break;
       case MemoryChunk::kCompactingFinalize:
         DCHECK(p->IsEvacuationCandidate());
         p->SetWasSwept();
         p->Unlink();
         break;
       case MemoryChunk::kCompactingDone:
         DCHECK(p->IsFlagSet(Page::POPULAR_PAGE));
         DCHECK(p->IsFlagSet(Page::RESCAN_ON_EVACUATION));
@@ skipping 269 matching lines @@
 
   LiveObjectIterator<kBlackObjects> it(page);
   HeapObject* object = nullptr;
   while ((object = it.Next()) != nullptr) {
     DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
     if (!visitor->Visit(object)) {
       if (mode == kClearMarkbits) {
         page->markbits()->ClearRange(
             page->AddressToMarkbitIndex(page->area_start()),
             page->AddressToMarkbitIndex(object->address()));
+        if (page->old_to_new_slots() != nullptr) {
+          page->old_to_new_slots()->RemoveRange(
+              0, static_cast<int>(object->address() - page->address()));
+        }
         RecomputeLiveBytes(page);
       }
       return false;
     }
   }
   if (mode == kClearMarkbits) {
     Bitmap::Clear(page);
   }
   return true;
 }
@@ skipping 145 matching lines @@
     SemiSpaceIterator to_it(heap()->new_space());
     for (HeapObject* object = to_it.Next(); object != NULL;
          object = to_it.Next()) {
       Map* map = object->map();
       object->IterateBody(map->instance_type(), object->SizeFromMap(map),
                           &updating_visitor);
     }
     // Update roots.
     heap_->IterateRoots(&updating_visitor, VISIT_ALL_IN_SWEEP_NEWSPACE);
 
-    StoreBufferRebuildScope scope(heap_, heap_->store_buffer(),
-                                  &Heap::ScavengeStoreBufferCallback);
     heap_->store_buffer()->IteratePointersToNewSpace(&UpdatePointer);
   }
 
   int npages = evacuation_candidates_.length();
   {
     GCTracer::Scope gc_scope(
         heap()->tracer(),
         GCTracer::Scope::MC_EVACUATE_UPDATE_POINTERS_BETWEEN_EVACUATED);
     for (int i = 0; i < npages; i++) {
       Page* p = evacuation_candidates_[i];
@@ skipping 81 matching lines @@
 }
 
 
 void MarkCompactCollector::ReleaseEvacuationCandidates() {
   int npages = evacuation_candidates_.length();
   for (int i = 0; i < npages; i++) {
     Page* p = evacuation_candidates_[i];
     if (!p->IsEvacuationCandidate()) continue;
     PagedSpace* space = static_cast<PagedSpace*>(p->owner());
     space->Free(p->area_start(), p->area_size());
-    p->set_scan_on_scavenge(false);
     p->ResetLiveBytes();
     CHECK(p->WasSwept());
     space->ReleasePage(p);
   }
   evacuation_candidates_.Rewind(0);
   compacting_ = false;
   heap()->FilterStoreBufferEntriesOnAboutToBeFreedPages();
   heap()->FreeQueuedChunks();
 }
 
@@ skipping 274 matching lines @@
     MarkBit mark_bit = Marking::MarkBitFrom(host);
     if (Marking::IsBlack(mark_bit)) {
       RelocInfo rinfo(isolate(), pc, RelocInfo::CODE_TARGET, 0, host);
       RecordRelocSlot(&rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8