Switch UnreachableObjectsFilter to use Marking instead of InstrusiveMarking.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 9fa79ca74629a406ea6a27181bfa296c23f47cee..3f4d236a38a06b0205b11777d5b7709ca4f6eaa7 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -63,6 +63,7 @@ MarkCompactCollector::MarkCompactCollector() :  // NOLINT
       compacting_(false),
       was_marked_incrementally_(false),
       collect_maps_(FLAG_collect_maps),
+      markbits_are_tainted_(false),
       tracer_(NULL),
       migration_slots_buffer_(NULL),
 #ifdef DEBUG
@@ -330,7 +331,7 @@ void MarkCompactCollector::VerifyMarkbitsAreClean() {
 #endif
 
 
-static void ClearMarkbits(PagedSpace* space) {
+static void ClearMarkbitsInPagedSpace(PagedSpace* space) {
   PageIterator it(space);
 
   while (it.has_next()) {
@@ -339,7 +340,7 @@ static void ClearMarkbits(PagedSpace* space) {
 }
 
 
-static void ClearMarkbits(NewSpace* space) {
+static void ClearMarkbitsInNewSpace(NewSpace* space) {
   NewSpacePageIterator it(space->ToSpaceStart(), space->ToSpaceEnd());
 
   while (it.has_next()) {
@@ -348,20 +349,24 @@ static void ClearMarkbits(NewSpace* space) {
 }
 
 
-static void ClearMarkbits(Heap* heap) {
-  ClearMarkbits(heap->code_space());
-  ClearMarkbits(heap->map_space());
-  ClearMarkbits(heap->old_pointer_space());
-  ClearMarkbits(heap->old_data_space());
-  ClearMarkbits(heap->cell_space());
-  ClearMarkbits(heap->new_space());
+void MarkCompactCollector::ClearMarkbits() {
+  if (!markbits_are_tainted_) return;
 
-  LargeObjectIterator it(heap->lo_space());
+  ClearMarkbitsInPagedSpace(heap()->code_space());
+  ClearMarkbitsInPagedSpace(heap()->map_space());
+  ClearMarkbitsInPagedSpace(heap()->old_pointer_space());
+  ClearMarkbitsInPagedSpace(heap()->old_data_space());
+  ClearMarkbitsInPagedSpace(heap()->cell_space());
+  ClearMarkbitsInNewSpace(heap()->new_space());
+
+  LargeObjectIterator it(heap()->lo_space());
   for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
     MarkBit mark_bit = Marking::MarkBitFrom(obj);
     mark_bit.Clear();
     mark_bit.Next().Clear();
   }
+
+  markbits_are_tainted_ = false;

[Erik Corry, 2011/10/19 17:56:07]

Here you could use SetMarkbitsTainted(false)

 }
 
 
@@ -504,9 +509,9 @@ void MarkCompactCollector::Prepare(GCTracer* tracer) {
   // Clear marking bits for precise sweeping to collect all garbage.
   if (was_marked_incrementally_ && PreciseSweepingRequired()) {
     heap()->incremental_marking()->Abort();
-    ClearMarkbits(heap_);
     AbortCompaction();
     was_marked_incrementally_ = false;
+    TaintMarkbits();
   }
 
   // Don't start compaction if we are in the middle of incremental
@@ -515,6 +520,8 @@ void MarkCompactCollector::Prepare(GCTracer* tracer) {
     StartCompaction();
   }
 
+  ClearMarkbits();
+
   PagedSpaces spaces;
   for (PagedSpace* space = spaces.next();
        space != NULL;