[heap] Remove black pages and use black areas instead.

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index b94478cfdea48c27d25bb7f28a9df35bcbb46fb1..340b0cac0ad6e58aae9481f9ddc3e5dae8d2146b 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -1229,18 +1229,6 @@ bool PagedSpace::Expand() {
   // Pages created during bootstrapping may contain immortal immovable objects.
   if (!heap()->deserialization_complete()) p->MarkNeverEvacuate();
 
-  // When incremental marking was activated, old space pages are allocated
-  // black.
-  if (heap()->incremental_marking()->black_allocation() &&
-      identity() == OLD_SPACE) {
-    p->markbits()->SetAllBits();
-    p->SetFlag(Page::BLACK_PAGE);
-    if (FLAG_trace_incremental_marking) {
-      PrintIsolate(heap()->isolate(), "Added black page %p\n",
-                   static_cast<void*>(p));
-    }
-  }
-
   DCHECK(Capacity() <= heap()->MaxOldGenerationSize());
 
   p->InsertAfter(anchor_.prev_page());
@@ -1265,6 +1253,38 @@ void PagedSpace::ResetFreeListStatistics() {
   }
 }
 
+void PagedSpace::SetAllocationInfo(Address top, Address limit) {
+  SetTopAndLimit(top, limit);
+  if (top != nullptr && top != limit &&
+      heap()->incremental_marking()->black_allocation()) {
+    Page* page = Page::FromAddress(top);
+    page->markbits()->SetRange(page->AddressToMarkbitIndex(top),
+                               page->AddressToMarkbitIndex(limit));
+    page->IncrementLiveBytes(static_cast<int>(limit - top));
+  }
+}
+
+// Empty space allocation info, returning unused area to free list.
+void PagedSpace::EmptyAllocationInfo() {
+  // Mark the old linear allocation area with a free space map so it can be
+  // skipped when scanning the heap.
+  Address current_top = top();
+  Address current_limit = limit();
+  if (current_top == nullptr) {
+    DCHECK(current_limit == nullptr);
+    return;
+  }
+  int old_linear_size = static_cast<int>(current_limit - current_top);
+  Free(current_top, old_linear_size);

[ulan, 2016/07/19 13:23:32]

Let's move it after clearing the range, so that we do not free marked area.

[Hannes Payer (out of office), 2016/07/19 14:42:53]

Done.

+  SetTopAndLimit(NULL, NULL);
+  if (current_top != current_limit &&
+      heap()->incremental_marking()->black_allocation()) {
+    Page* page = Page::FromAddress(current_top);
+    page->markbits()->ClearRange(page->AddressToMarkbitIndex(current_top),
+                                 page->AddressToMarkbitIndex(current_limit));
+    page->IncrementLiveBytes(static_cast<int>(current_top - current_limit));

[ulan, 2016/07/19 13:23:32]

To avoid large unsigned to int conversions, let's do
-static_cast<int>(current_limit - current_top)

Alternatively, how about adding page->DecrementLiveBytes, so that the intention
is obvious from code?

[Hannes Payer (out of office), 2016/07/19 14:42:53]

Done.

Good idea. I do that in the follow-up CL that is doing the symmetric
decrementing of live bytes.

+  }
+}
 
 void PagedSpace::IncreaseCapacity(int size) {
   accounting_stats_.ExpandSpace(size);
@@ -1331,8 +1351,7 @@ void PagedSpace::Verify(ObjectVisitor* visitor) {
       // All the interior pointers should be contained in the heap.
       int size = object->Size();
       object->IterateBody(map->instance_type(), size, visitor);
-      if (!page->IsFlagSet(Page::BLACK_PAGE) &&
-          Marking::IsBlack(ObjectMarking::MarkBitFrom(object))) {
+      if (Marking::IsBlack(ObjectMarking::MarkBitFrom(object))) {
         black_size += size;
       }
 
@@ -2429,8 +2448,7 @@ HeapObject* FreeList::Allocate(int size_in_bytes) {
   // Mark the old linear allocation area with a free space map so it can be
   // skipped when scanning the heap.  This also puts it back in the free list
   // if it is big enough.
-  owner_->Free(owner_->top(), old_linear_size);
-  owner_->SetTopAndLimit(nullptr, nullptr);
+  owner_->EmptyAllocationInfo();
 
   owner_->heap()->incremental_marking()->OldSpaceStep(size_in_bytes -
                                                       old_linear_size);
@@ -2464,8 +2482,8 @@ HeapObject* FreeList::Allocate(int size_in_bytes) {
     // Keep the linear allocation area empty if requested to do so, just
     // return area back to the free list instead.
     owner_->Free(new_node->address() + size_in_bytes, bytes_left);
-    owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
-                           new_node->address() + size_in_bytes);
+    owner_->SetAllocationInfo(new_node->address() + size_in_bytes,
+                              new_node->address() + size_in_bytes);
   } else if (bytes_left > kThreshold &&
              owner_->heap()->incremental_marking()->IsMarkingIncomplete() &&
              FLAG_incremental_marking) {
@@ -2475,14 +2493,15 @@ HeapObject* FreeList::Allocate(int size_in_bytes) {
     // we want to do another increment until the linear area is used up.
     owner_->Free(new_node->address() + size_in_bytes + linear_size,
                  new_node_size - size_in_bytes - linear_size);
-    owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
-                           new_node->address() + size_in_bytes + linear_size);
+    owner_->SetAllocationInfo(
+        new_node->address() + size_in_bytes,
+        new_node->address() + size_in_bytes + linear_size);
   } else {
     DCHECK(bytes_left >= 0);
     // Normally we give the rest of the node to the allocator as its new
     // linear allocation area.
-    owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
-                           new_node->address() + new_node_size);
+    owner_->SetAllocationInfo(new_node->address() + size_in_bytes,
+                              new_node->address() + new_node_size);
   }
 
   owner_->AllocationStep(new_node->address(), size_in_bytes);
@@ -2872,6 +2891,11 @@ AllocationResult LargeObjectSpace::AllocateRaw(int object_size,
 
   heap()->incremental_marking()->OldSpaceStep(object_size);
   AllocationStep(object->address(), object_size);
+
+  if (heap()->incremental_marking()->black_allocation()) {
+    Marking::MarkBlack(ObjectMarking::MarkBitFrom(object));
+    MemoryChunk::IncrementLiveBytesFromGC(object, object_size);
+  }
   return object;
 }