Introduce instance type for transition arrays.

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 813 matching lines @@
   // If concurrent unmapping tasks are still running, we should wait for
   // them here.
   heap()->WaitUntilUnmappingOfFreeChunksCompleted();
 
   // Clear marking bits if incremental marking is aborted.
   if (was_marked_incrementally_ && heap_->ShouldAbortIncrementalMarking()) {
     heap()->incremental_marking()->Stop();
     ClearMarkbits();
     AbortWeakCollections();
     AbortWeakCells();
+    AbortTransitionArrays();
     AbortCompaction();
     was_marked_incrementally_ = false;
   }
 
   // Don't start compaction if we are in the middle of incremental
   // marking cycle. We did not collect any slots.
   if (!FLAG_never_compact && !was_marked_incrementally_) {
     StartCompaction(NON_INCREMENTAL_COMPACTION);
   }
 
@@ skipping 1478 matching lines @@
   // Process weak cells before MarkCodeForDeoptimization and
   // ClearNonLiveReferences  so that weak cells in dependent code arrays are
   // cleared or contain only live code objects.
   ProcessAndClearWeakCells();
 
   MarkDependentCodeListForDeoptimization(dependent_code_list);
 
   ClearNonLiveReferences();
 
   ClearWeakCollections();
-
-  heap_->set_encountered_weak_cells(Smi::FromInt(0));
 }
 
 
 void MarkCompactCollector::ClearNonLiveReferences() {
   GCTracer::Scope gc_scope(heap()->tracer(),
                            GCTracer::Scope::MC_NONLIVEREFERENCES);
+
+  ProcessAndClearTransitionArrays();
+
   // Iterate over the map space, setting map transitions that go from
   // a marked map to an unmarked map to null transitions.  This action
   // is carried out only on maps of JSObjects and related subtypes.
   HeapObjectIterator map_iterator(heap()->map_space());
   for (HeapObject* obj = map_iterator.Next(); obj != NULL;
        obj = map_iterator.Next()) {
     Map* map = Map::cast(obj);
     if (!map->CanTransition()) continue;
     MarkBit map_mark = Marking::MarkBitFrom(map);
     if (Marking::IsWhite(map_mark)) {
@@ skipping 298 matching lines @@
   Object* weak_cell_obj = heap()->encountered_weak_cells();
   while (weak_cell_obj != Smi::FromInt(0)) {
     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::ProcessAndClearTransitionArrays() {
+  HeapObject* undefined = heap()->undefined_value();
+  Object* obj = heap()->encountered_transition_arrays();
+  while (obj != Smi::FromInt(0)) {
+    TransitionArray* array = TransitionArray::cast(obj);
+    // TODO(ulan): move logic from ClearMapTransitions here.
+    obj = array->next_link();
+    array->set_next_link(undefined, SKIP_WRITE_BARRIER);
+  }
+  heap()->set_encountered_transition_arrays(Smi::FromInt(0));
+}
+
+
+void MarkCompactCollector::AbortTransitionArrays() {
+  HeapObject* undefined = heap()->undefined_value();
+  Object* obj = heap()->encountered_transition_arrays();
+  while (obj != Smi::FromInt(0)) {
+    TransitionArray* array = TransitionArray::cast(obj);
+    obj = array->next_link();
+    array->set_next_link(undefined, SKIP_WRITE_BARRIER);
+  }
+  heap()->set_encountered_transition_arrays(Smi::FromInt(0));
+}
+
+
 void MarkCompactCollector::RecordMigratedSlot(
     Object* value, Address slot, SlotsBuffer** evacuation_slots_buffer) {
   // When parallel compaction is in progress, store and slots buffer entries
   // require synchronization.
   if (heap_->InNewSpace(value)) {
     if (compaction_in_progress_) {
       heap_->store_buffer()->MarkSynchronized(slot);
     } else {
       heap_->store_buffer()->Mark(slot);
     }
@@ skipping 1500 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