Immediatelly promote marked objects

src/heap/heap-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
@@ skipping 375 matching lines @@
 
 bool Heap::InOldSpaceSlow(Address address) {
   return old_space_->ContainsSlow(address);
 }
 
 bool Heap::OldGenerationAllocationLimitReached() {
   if (!incremental_marking()->IsStopped()) return false;
   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);
 }
 
 void Heap::RecordWrite(Object* object, int offset, Object* o) {
   if (!InNewSpace(o) || !object->IsHeapObject() || InNewSpace(object)) {
     return;
   }
   RememberedSet<OLD_TO_NEW>::Insert(
       Page::FromAddress(reinterpret_cast<Address>(object)),
@@ skipping 324 matching lines @@
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_INL_H_