Immediatelly promote marked objects

src/heap/heap-inl.h

Index: src/heap/heap-inl.h
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index f9c9235320b25df45a116cd08fd04fe7b4692451..b53b697e55799fa7f069f0ba21b6bb53153da9e5 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -393,10 +393,30 @@ bool Heap::OldGenerationAllocationLimitReached() {
   return OldGenerationSpaceAvailable() < 0;
 }
 
+PromotionMode Heap::CurrentPromotionMode() {
+  if (incremental_marking()->IsMarking()) {
+    return PROMOTE_MARKED;
+  } else {
+    return DEFAULT_PROMOTION;
+  }
+}
 
-bool Heap::ShouldBePromoted(Address old_address, int object_size) {
+bool Heap::ShouldBePromoted(Address old_address, int object_size,

[Hannes Payer (out of office), 2016/05/25 05:35:46]

How about templatizing this function based on mode?

[ulan, 2016/05/25 08:24:09]

The callers would have to check the mode at runtime and dispatch to correct
version of ShouldBePromoted. IMO we will not win much performance.

An alternative would be to templatize all the way up. 

+                            PromotionMode promotion_mode) {
   Page* page = Page::FromAddress(old_address);
   Address age_mark = new_space_.age_mark();
+
+  if (promotion_mode == FORCE_PROMOTION) {
+    return true;
+  }
+
+  if (promotion_mode == PROMOTE_MARKED) {
+    MarkBit mark_bit = Marking::MarkBitFrom(old_address);
+    if (!Marking::IsWhite(mark_bit)) {
+      return true;
+    }
+  }
+
   return page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK) &&
          (!page->ContainsLimit(age_mark) || old_address < age_mark);
 }