[heap] Record pretenuring feedback for moved pages

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 2eb9a1b79195f3c38e9b2c1df6f5daf84dac66f1..a60c892612276ec2657c4da7148ec796cc0d7d12 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -1837,8 +1837,15 @@ class MarkCompactCollector::EvacuateNewSpaceVisitor final
 class MarkCompactCollector::EvacuateNewSpacePageVisitor final
     : public MarkCompactCollector::HeapObjectVisitor {
  public:
-  explicit EvacuateNewSpacePageVisitor(Heap* heap)
-      : heap_(heap), promoted_size_(0), semispace_copied_size_(0) {}
+  enum VisitationMode { kNewToOld, kNewToNew };
+
+  explicit EvacuateNewSpacePageVisitor(
+      Heap* heap, base::HashMap* local_pretenuring_feedback)
+      : heap_(heap),
+        promoted_size_(0),
+        semispace_copied_size_(0),
+        local_pretenuring_feedback_(local_pretenuring_feedback),
+        mode_(VisitationMode::kNewToNew) {}
 
   static void MoveToOldSpace(Page* page, PagedSpace* owner) {
     page->Unlink();
@@ -1852,23 +1859,32 @@ class MarkCompactCollector::EvacuateNewSpacePageVisitor final
   }
 
   inline bool Visit(HeapObject* object) {
-    RecordMigratedSlotVisitor visitor(heap_->mark_compact_collector());
-    object->IterateBodyFast(&visitor);
-    promoted_size_ += object->Size();
+    heap_->UpdateAllocationSite<Heap::kCached>(object,
+                                               local_pretenuring_feedback_);
+    if (mode_ == kNewToOld) {
+      RecordMigratedSlotVisitor visitor(heap_->mark_compact_collector());
+      object->IterateBodyFast(&visitor);
+    }
     return true;
   }
 
   intptr_t promoted_size() { return promoted_size_; }
   intptr_t semispace_copied_size() { return semispace_copied_size_; }
 
-  void account_semispace_copied(intptr_t copied) {
-    semispace_copied_size_ += copied;
+  void account_semispace_copied(intptr_t bytes) {
+    semispace_copied_size_ += bytes;
   }
 
+  void account_promoted(intptr_t bytes) { promoted_size_ += bytes; }
+
+  void set_mode(VisitationMode mode) { mode_ = mode; }
+
  private:
   Heap* heap_;
   intptr_t promoted_size_;
   intptr_t semispace_copied_size_;
+  base::HashMap* local_pretenuring_feedback_;
+  VisitationMode mode_;
 };
 
 class MarkCompactCollector::EvacuateOldSpaceVisitor final
@@ -2925,7 +2941,7 @@ class MarkCompactCollector::Evacuator : public Malloced {
         local_pretenuring_feedback_(kInitialLocalPretenuringFeedbackCapacity),
         new_space_visitor_(collector->heap(), &compaction_spaces_,
                            &local_pretenuring_feedback_),
-        new_space_page_visitor(collector->heap()),
+        new_space_page_visitor(collector->heap(), &local_pretenuring_feedback_),
         old_space_visitor_(collector->heap(), &compaction_spaces_),
         duration_(0.0),
         bytes_compacted_(0) {}
@@ -2982,15 +2998,19 @@ bool MarkCompactCollector::Evacuator::EvacuatePage(Page* page) {
         DCHECK(success);
         break;
       case kPageNewToOld:
+        new_space_page_visitor.set_mode(EvacuateNewSpacePageVisitor::kNewToOld);
         success = collector_->VisitLiveObjects(page, &new_space_page_visitor,
                                                kKeepMarking);
+        new_space_page_visitor.account_promoted(page->LiveBytes());
         // ArrayBufferTracker will be updated during sweeping.
         DCHECK(success);
         break;
       case kPageNewToNew:
+        new_space_page_visitor.set_mode(EvacuateNewSpacePageVisitor::kNewToNew);
+        success = collector_->VisitLiveObjects(page, &new_space_page_visitor,

[Michael Lippautz, 2016/11/10 14:06:02]

Measured the impact on ToT splay w/ --gc-global. In this case we go from
0ms->0.2ms for full pages. The minor MC experiment shows that this (or some
variation) will be needed in the future.

+                                               kKeepMarking);
         new_space_page_visitor.account_semispace_copied(page->LiveBytes());
         // ArrayBufferTracker will be updated during sweeping.
-        success = true;
         break;
       case kObjectsOldToOld:
         success = collector_->VisitLiveObjects(page, &old_space_visitor_,
@@ -3015,8 +3035,6 @@ bool MarkCompactCollector::Evacuator::EvacuatePage(Page* page) {
               page, ArrayBufferTracker::kUpdateForwardedRemoveOthers);
         }
         break;
-      default:
-        UNREACHABLE();
     }
   }
   ReportCompactionProgress(evacuation_time, saved_live_bytes);