Print out how many AllocationMementos were found on a scavenge of new

space. This is useful because the unrooted mementos affect heap
decisions like pretenuring mode, and helps to gauge the effectiveness
of allocation-site feedback.

R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/25273002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17027 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap-inl.h

@@ -525,6 +525,14 @@ void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {
     return;
   }
 
+  if (FLAG_trace_track_allocation_sites &&
+      AllocationSite::CanTrack(object->map()->instance_type()) &&
+      object->IsJSObject()) {
+    if (AllocationMemento::FindForJSObject(JSObject::cast(object)) != NULL) {
+      object->GetIsolate()->heap()->allocation_mementos_found_on_scavenge_++;
+    }
+  }
+
   // AllocationMementos are unrooted and shouldn't survive a scavenge
   ASSERT(object->map() != object->GetHeap()->allocation_memento_map());
   // Call the slow part of scavenge object.

src/heap.cc

@@ -86,6 +86,7 @@ Heap::Heap()
       contexts_disposed_(0),
       global_ic_age_(0),
       flush_monomorphic_ics_(false),
+      allocation_mementos_found_on_scavenge_(0),
       scan_on_scavenge_pages_(0),
       new_space_(this),
       old_pointer_space_(NULL),
@@ -1328,6 +1329,8 @@ class ScavengeWeakObjectRetainer : public WeakObjectRetainer {
 void Heap::Scavenge() {
   RelocationLock relocation_lock(this);
 
+  allocation_mementos_found_on_scavenge_ = 0;
+
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) VerifyNonPointerSpacePointers(this);
 #endif
@@ -1475,6 +1478,12 @@ void Heap::Scavenge() {
   gc_state_ = NOT_IN_GC;
 
   scavenges_since_last_idle_round_++;
+
+  if (FLAG_trace_track_allocation_sites &&
+      allocation_mementos_found_on_scavenge_ > 0) {
+    PrintF("AllocationMementos found during scavenge = %d\n",
+           allocation_mementos_found_on_scavenge_);
+  }
 }
 
 

src/heap.h

@@ -1886,6 +1886,9 @@ class Heap {
 
   bool flush_monomorphic_ics_;
 
+  // AllocationMementos found on scavenge.
+  int allocation_mementos_found_on_scavenge_;
+
   int scan_on_scavenge_pages_;
 
   NewSpace new_space_;

src/objects.cc

@@ -9057,7 +9057,6 @@ AllocationMemento* AllocationMemento::FindForJSObject(JSObject* object) {
   // involves carefully checking the object immediately after the JSArray
   // (if there is one) to see if it's an AllocationMemento.
   if (FLAG_track_allocation_sites && object->GetHeap()->InNewSpace(object)) {
-    ASSERT(object->GetHeap()->InToSpace(object));
     Address ptr_end = (reinterpret_cast<Address>(object) - kHeapObjectTag) +
         object->Size();
     if ((ptr_end + AllocationMemento::kSize) <=