From 100b9d836fa7df0c7010c78743a93e69342e6a17 Mon Sep 17 00:00:00 2001
From: "hpayer@chromium.org"
 <hpayer@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Mon, 23 Jun 2014 08:50:54 +0000
Subject: [PATCH] An object should only be promoted to the old generation if it
 survived a scavenge operation.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/345523002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21915 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/heap-inl.h                   |  9 +++------
 src/mark-compact.cc              | 10 ++++++----
 src/mark-compact.h               |  2 +-
 test/cctest/test-api.cc          |  1 +
 test/cctest/test-heap.cc         |  1 +
 test/cctest/test-mark-compact.cc |  3 ++-
 6 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/heap-inl.h b/src/heap-inl.h
index 2de7616..22e4c97 100644
--- a/src/heap-inl.h
+++ b/src/heap-inl.h
@@ -388,15 +388,12 @@ bool Heap::OldGenerationAllocationLimitReached() {
 
 
 bool Heap::ShouldBePromoted(Address old_address, int object_size) {
-  // An object should be promoted if:
-  // - the object has survived a scavenge operation or
-  // - to space is already 25% full.
+  // An object should be promoted if the object has survived a
+  // scavenge operation.
   NewSpacePage* page = NewSpacePage::FromAddress(old_address);
   Address age_mark = new_space_.age_mark();
-  bool below_mark = page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK) &&
+  return page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK) &&
       (!page->ContainsLimit(age_mark) || old_address < age_mark);
-  return below_mark || (new_space_.Size() + object_size) >=
-                        (new_space_.EffectiveCapacity() >> 2);
 }
 
 
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 17b3c34..047e772 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -1975,7 +1975,7 @@ static void DiscoverGreyObjectsOnPage(MarkingDeque* marking_deque,
 }
 
 
-int MarkCompactCollector::DiscoverAndPromoteBlackObjectsOnPage(
+int MarkCompactCollector::DiscoverAndEvacuateBlackObjectsOnPage(
     NewSpace* new_space,
     NewSpacePage* p) {
   ASSERT(strcmp(Marking::kWhiteBitPattern, "00") == 0);
@@ -2008,8 +2008,10 @@ int MarkCompactCollector::DiscoverAndPromoteBlackObjectsOnPage(
 
       offset++;
       current_cell >>= 1;
-      // Aggressively promote young survivors to the old space.
-      if (TryPromoteObject(object, size)) {
+
+      // TODO(hpayer): Refactor EvacuateObject and call this function instead.
+      if (heap()->ShouldBePromoted(object->address(), size) &&
+          TryPromoteObject(object, size)) {
         continue;
       }
 
@@ -3049,7 +3051,7 @@ void MarkCompactCollector::EvacuateNewSpace() {
   NewSpacePageIterator it(from_bottom, from_top);
   while (it.has_next()) {
     NewSpacePage* p = it.next();
-    survivors_size += DiscoverAndPromoteBlackObjectsOnPage(new_space, p);
+    survivors_size += DiscoverAndEvacuateBlackObjectsOnPage(new_space, p);
   }
 
   heap_->IncrementYoungSurvivorsCounter(survivors_size);
diff --git a/src/mark-compact.h b/src/mark-compact.h
index ae6767f..4e85978 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -870,7 +870,7 @@ class MarkCompactCollector {
   // regions to each space's free list.
   void SweepSpaces();
 
-  int DiscoverAndPromoteBlackObjectsOnPage(NewSpace* new_space,
+  int DiscoverAndEvacuateBlackObjectsOnPage(NewSpace* new_space,
                                            NewSpacePage* p);
 
   void EvacuateNewSpace();
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index 229950f..cd38f91 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -19879,6 +19879,7 @@ TEST(PersistentHandleInNewSpaceVisitor) {
   CHECK_EQ(42, object1.WrapperClassId());
 
   CcTest::heap()->CollectAllGarbage(i::Heap::kNoGCFlags);
+  CcTest::heap()->CollectAllGarbage(i::Heap::kNoGCFlags);
 
   v8::Persistent<v8::Object> object2(isolate, v8::Object::New(isolate));
   CHECK_EQ(0, object2.WrapperClassId());
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index bb54b0a..f0682b2 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -4315,6 +4315,7 @@ TEST(ArrayShiftSweeping) {
       "var tmp = new Array(100000);"
       "array[0] = 10;"
       "gc();"
+      "gc();"
       "array.shift();"
       "array;");
 
diff --git a/test/cctest/test-mark-compact.cc b/test/cctest/test-mark-compact.cc
index b5fcdfa..1790a0d 100644
--- a/test/cctest/test-mark-compact.cc
+++ b/test/cctest/test-mark-compact.cc
@@ -92,7 +92,8 @@ TEST(Promotion) {
   CHECK(heap->InSpace(*array, NEW_SPACE));
 
   // Call mark compact GC, so array becomes an old object.
-  heap->CollectGarbage(OLD_POINTER_SPACE);
+  heap->CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);
+  heap->CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);
 
   // Array now sits in the old space
   CHECK(heap->InSpace(*array, OLD_POINTER_SPACE));
-- 
2.7.4