Do not left-trim arrays when concurrent sweeping is active.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index b26ca6a016af2588fa700f74966064c82c6ee859..2338095d8d059f1bfb03343d1ec17d7401bf75f1 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -664,6 +664,21 @@ bool MarkCompactCollector::IsConcurrentSweepingInProgress() {
 }
 
 
+bool MarkCompactCollector::CanMoveObjectStart(HeapObject* object) {
+  Address address = object->address();
+  bool is_in_old_pointer_space = heap_->InOldPointerSpace(address);
+  bool is_in_old_data_space = heap_->InOldDataSpace(address);
+
+  if (heap_->lo_space()->Contains(object)) return false;
+
+  // We cannot move the object start if the given old space page is
+  // concurrently swept.
+  return (!is_in_old_pointer_space && !is_in_old_data_space) ||
+      Page::FromAddress(address)->parallel_sweeping() <=
+          MemoryChunk::PARALLEL_SWEEPING_FINALIZE;
+  }

[Michael Starzinger, 2014/03/24 12:21:35]

nit: Indentation is off.

[Hannes Payer (out of office), 2014/03/25 11:41:08]

Done.

+
+
 void Marking::TransferMark(Address old_start, Address new_start) {
   // This is only used when resizing an object.
   ASSERT(MemoryChunk::FromAddress(old_start) ==
@@ -4086,6 +4101,7 @@ void MarkCompactCollector::SweepInParallel(PagedSpace* space) {
     if (p->TryParallelSweeping()) {
       SweepConservatively<SWEEP_IN_PARALLEL>(space, &private_free_list, p);
       free_list->Concatenate(&private_free_list);
+      p->set_parallel_sweeping(MemoryChunk::PARALLEL_SWEEPING_FINALIZE);
     }
   }
 }
@@ -4284,10 +4300,11 @@ void MarkCompactCollector::ParallelSweepSpaceComplete(PagedSpace* space) {
   PageIterator it(space);
   while (it.has_next()) {
     Page* p = it.next();
-    if (p->parallel_sweeping() == MemoryChunk::PARALLEL_SWEEPING_IN_PROGRESS) {
+    if (p->parallel_sweeping() == MemoryChunk::PARALLEL_SWEEPING_FINALIZE) {
       p->set_parallel_sweeping(MemoryChunk::PARALLEL_SWEEPING_DONE);
       p->MarkSweptConservatively();
     }
+    ASSERT(p->parallel_sweeping() == MemoryChunk::PARALLEL_SWEEPING_DONE);
   }
 }