Track how many pages trigger fallback strategies in GC

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index de381aab356657374f1e62f083173045d949ded0..d4edcf153c4f9199ce9a50e135ce6d22cd8802d2 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -2032,6 +2032,7 @@ void MarkCompactCollector::EmptyMarkingDeque() {
 // overflowed objects in the heap so the overflow flag on the markings stack
 // is cleared.
 void MarkCompactCollector::RefillMarkingDeque() {
+  isolate()->CountUsage(v8::Isolate::UseCounterFeature::kMarkDequeOverflow);
   DCHECK(marking_deque_.overflowed());
 
   DiscoverGreyObjectsInNewSpace(heap(), &marking_deque_);
@@ -4508,6 +4509,30 @@ void MarkCompactCollector::RecordRelocSlot(RelocInfo* rinfo, Object* target) {
 }
 
 
+void MarkCompactCollector::EvictEvacuationCandidate(Page* page) {
+  if (FLAG_trace_fragmentation) {
+    PrintF("Page %p is too popular. Disabling evacuation.\n",
+           reinterpret_cast<void*>(page));
+  }
+
+  isolate()->CountUsage(v8::Isolate::UseCounterFeature::kSlotsBufferOverflow);
+
+  // TODO(gc) If all evacuation candidates are too popular we
+  // should stop slots recording entirely.
+  page->ClearEvacuationCandidate();
+
+  // We were not collecting slots on this page that point
+  // to other evacuation candidates thus we have to
+  // rescan the page after evacuation to discover and update all
+  // pointers to evacuated objects.
+  if (page->owner()->identity() == OLD_DATA_SPACE) {
+    evacuation_candidates_.RemoveElement(page);
+  } else {
+    page->SetFlag(Page::RESCAN_ON_EVACUATION);
+  }
+}
+
+
 void MarkCompactCollector::RecordCodeEntrySlot(Address slot, Code* target) {
   Page* target_page = Page::FromAddress(reinterpret_cast<Address>(target));
   if (target_page->IsEvacuationCandidate() &&