Print out how many AllocationMementos were found during mark-sweep.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 31ad1bacfb0f6eb72b8688de5b488bef3f9bea03..cff5c4fd9e73fe4fee1694c4dca9a718a1222f52 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -407,6 +407,8 @@ void MarkCompactCollector::CollectGarbage() {
   ASSERT(state_ == PREPARE_GC);
   ASSERT(encountered_weak_collections_ == Smi::FromInt(0));
 
+  heap()->allocation_mementos_found_ = 0;
+
   MarkLiveObjects();
   ASSERT(heap_->incremental_marking()->IsStopped());
 
@@ -449,6 +451,11 @@ void MarkCompactCollector::CollectGarbage() {
     marking_parity_ = EVEN_MARKING_PARITY;
   }
 
+  if (FLAG_trace_track_allocation_sites &&
+      heap()->allocation_mementos_found_ > 0) {
+    PrintF("AllocationMementos found during mark-sweep = %d\n",
+           heap()->allocation_mementos_found_);
+  }
   tracer_ = NULL;
 }
 
@@ -2002,6 +2009,15 @@ int MarkCompactCollector::DiscoverAndPromoteBlackObjectsOnPage(
       int size = object->Size();
       survivors_size += size;
 
+      if (FLAG_trace_track_allocation_sites &&
+          AllocationSite::CanTrack(object->map()->instance_type()) &&

[mvstanton, 2013/10/02 10:56:45]

The CanTrack might be redundant because by offering the method FindForJSObject
on AllocationMemento class we are implicitly admitting that AllocationMementos
can track JSObjects.

Therefore the only thing we care about is that the object is a JSObject.

[Hannes Payer (out of office), 2013/10/02 11:02:19]

Done.

+          object->IsJSObject()) {
+        if (AllocationMemento::FindForJSObject(JSObject::cast(object), true)
+            != NULL) {
+          heap()->allocation_mementos_found_++;
+        }
+      }
+
       offset++;
       current_cell >>= 1;
       // Aggressively promote young survivors to the old space.