[heap] Properly adjust live bytes for pages where we abort evacaution

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 0e8014014dbd612bf68bcfe0236f668312b1d81b..16dc3505f41ef484ec80c58225a891053534b55f 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -3502,14 +3502,21 @@ bool MarkCompactCollector::VisitLiveObjects(MemoryChunk* page,
 #endif  // VERIFY_HEAP
 
   LiveObjectIterator<kBlackObjects> it(page);
-  HeapObject* object = NULL;
-  while ((object = it.Next()) != NULL) {
+  HeapObject* object = nullptr;
+  while ((object = it.Next()) != nullptr) {
     DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
     if (!visitor->Visit(object)) {
       if (mode == kClearMarkbits) {
         page->markbits()->ClearRange(
             page->AddressToMarkbitIndex(page->area_start()),
             page->AddressToMarkbitIndex(object->address()));
+        LiveObjectIterator<kBlackObjects> it2(page);

[ulan, 2016/01/14 15:46:38]

Let's move this code into a separate function named something like
RecomputeLiveBytes().

[Michael Lippautz, 2016/01/14 16:01:46]

RecomputeLiveBytes it is.

+        int new_live_size = 0;
+        while ((object = it2.Next()) != nullptr) {
+          new_live_size += object->Size();
+        }
+        DCHECK_LT(new_live_size, page->LiveBytes());
+        page->IncrementLiveBytes(new_live_size - page->LiveBytes());

[ulan, 2016/01/14 15:46:38]

I think adding new page->SetLiveBytes(new_live_size) would be better.

Otherwise, we are passing negative number to IncrementLiveBytes.

[Michael Lippautz, 2016/01/14 16:01:45]

SetLiveBytes() it is.

       }
       return false;
     }