Multi-page growing and shrinking new-space

src/incremental-marking.cc

Index: src/incremental-marking.cc
diff --git a/src/incremental-marking.cc b/src/incremental-marking.cc
index bcd5523796df6794ff86722fff5ecd2915b4df15..9f4314a94f2de0ea934c4952080a2a2226059d33 100644
--- a/src/incremental-marking.cc
+++ b/src/incremental-marking.cc
@@ -87,10 +87,8 @@ class IncrementalMarkingMarkingVisitor : public ObjectVisitor {
       MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
       if (mark_bit.data_only()) {
         incremental_marking_->MarkBlackOrKeepGrey(mark_bit);
-      } else {
-        if (Marking::IsWhite(mark_bit)) {
-          incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
-        }
+      } else if (Marking::IsWhite(mark_bit)) {
+        incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
       }
     }
   }
@@ -153,7 +151,7 @@ void IncrementalMarking::SetOldSpacePageFlags(MemoryChunk* chunk,
 }
 
 
-void IncrementalMarking::SetNewSpacePageFlags(MemoryChunk* chunk,
+void IncrementalMarking::SetNewSpacePageFlags(NewSpacePage* chunk,
                                               bool is_marking) {
   chunk->SetFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING);
   if (is_marking) {
@@ -161,6 +159,7 @@ void IncrementalMarking::SetNewSpacePageFlags(MemoryChunk* chunk,
   } else {
     chunk->ClearFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING);
   }
+  chunk->SetFlag(MemoryChunk::SCAN_ON_SCAVENGE);

[Vyacheslav Egorov (Chromium), 2011/06/14 11:52:55]

I am not sure this should be here.

[Erik Corry, 2011/06/14 12:23:17]

I think it's correct.  Scan-on-scavenge means that this page will be scanned on
a new-space collection.  This is definitely the case for new-space pages.

[Lasse Reichstein, 2011/06/14 14:13:03]

Keeping it.

 }
 
 
@@ -173,14 +172,22 @@ void IncrementalMarking::DeactivateWriteBarrierForSpace(PagedSpace* space) {
 }
 
 
+void IncrementalMarking::DeactivateWriteBarrierForSpace(NewSpace* space) {

[Erik Corry, 2011/06/14 12:23:17]

This should really be called 'DeactivateIncrementalWriteBarrierForSpace' since
it does not deactivate the write barrier completely, only the remembered set.

[Lasse Reichstein, 2011/06/14 14:13:03]

search-and-replaced.

+  NewSpacePageIterator it(space->ToSpaceLow(), space->ToSpaceHigh());
+  while (it.has_next()) {
+    NewSpacePage* p = it.next();
+    SetNewSpacePageFlags(p, false);
+  }
+}
+
+
 void IncrementalMarking::DeactivateWriteBarrier() {
   DeactivateWriteBarrierForSpace(heap_->old_pointer_space());
   DeactivateWriteBarrierForSpace(heap_->old_data_space());
   DeactivateWriteBarrierForSpace(heap_->cell_space());
   DeactivateWriteBarrierForSpace(heap_->map_space());
   DeactivateWriteBarrierForSpace(heap_->code_space());
-
-  SetNewSpacePageFlags(heap_->new_space()->ActivePage(), false);
+  DeactivateWriteBarrierForSpace(heap_->new_space());
 
   LargePage* lop = heap_->lo_space()->first_page();
   while (lop->is_valid()) {
@@ -200,6 +207,16 @@ void IncrementalMarking::ClearMarkbits(PagedSpace* space) {
 }
 
 
+void IncrementalMarking::ClearMarkbits(NewSpace* space) {
+  NewSpacePageIterator it(space->ToSpaceLow(), space->ToSpaceHigh());

[Vyacheslav Egorov (Chromium), 2011/06/14 11:52:55]

I find iterator interface confusing as new space is no longer continuous.

[Erik Corry, 2011/06/14 12:23:17]

Agreed.  It would make more sense if it just took the space as an argument.

[Lasse Reichstein, 2011/06/14 14:13:03]

Actually that's why I want a page iterator to iterate over the pages of the
semispace without doing the book-keeping every time.

[Lasse Reichstein, 2011/06/14 14:13:03]

Changed to use NewSpacePageIterator(space), which does the same thing.

+  while (it.has_next()) {
+    NewSpacePage* p = it.next();
+    p->markbits()->Clear();
+    SetNewSpacePageFlags(p, true);
+  }
+}
+
+
 void IncrementalMarking::ClearMarkbits() {
   // TODO(gc): Clear the mark bits in the sweeper.
   ClearMarkbits(heap_->old_pointer_space());
@@ -207,9 +224,7 @@ void IncrementalMarking::ClearMarkbits() {
   ClearMarkbits(heap_->cell_space());
   ClearMarkbits(heap_->map_space());
   ClearMarkbits(heap_->code_space());
-  heap_->new_space()->ActivePage()->markbits()->Clear();
-
-  SetNewSpacePageFlags(heap_->new_space()->ActivePage(), true);
+  ClearMarkbits(heap_->new_space());
 
   LargePage* lop = heap_->lo_space()->first_page();
   while (lop->is_valid()) {
@@ -230,13 +245,23 @@ void IncrementalMarking::VerifyMarkbitsAreClean(PagedSpace* space) {
 }
 
 
+void IncrementalMarking::VerifyMarkbitsAreClean(NewSpace* space) {
+  NewSpacePageIterator it(space->ToSpaceLow(), space->ToSpaceHigh());
+
+  while (it.has_next()) {
+    NewSpacePage* p = it.next();
+    ASSERT(p->markbits()->IsClean());
+  }
+}
+
+
 void IncrementalMarking::VerifyMarkbitsAreClean() {
   VerifyMarkbitsAreClean(heap_->old_pointer_space());
   VerifyMarkbitsAreClean(heap_->old_data_space());
   VerifyMarkbitsAreClean(heap_->code_space());
   VerifyMarkbitsAreClean(heap_->cell_space());
   VerifyMarkbitsAreClean(heap_->map_space());
-  ASSERT(heap_->new_space()->ActivePage()->markbits()->IsClean());
+  VerifyMarkbitsAreClean(heap_->new_space());
 }
 #endif
 
@@ -348,7 +373,11 @@ void IncrementalMarking::StartMarking() {
 
 void IncrementalMarking::PrepareForScavenge() {
   if (!IsMarking()) return;
-  heap_->new_space()->InactivePage()->markbits()->Clear();
+  NewSpacePageIterator it(heap_->new_space()->FromSpaceLow(),
+                          heap_->new_space()->FromSpaceHigh());
+  while (it.has_next()) {
+    it.next()->markbits()->Clear();
+  }
 }