Reviewers: danno, Michael Starzinger, titzer, ulan,
Description:
Implemented lazy sweeping of new space.
BUG=
Please review this at https://codereview.chromium.org/18998004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/heap.cc
M src/mark-compact.cc
M src/store-buffer.h
M src/store-buffer.cc
Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index
ebf1487e1487a7aea99d4fa5e11c8c4b285ec4a6..f8737c45b98acde1af9393e035efc09f47048d49
100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -1375,7 +1375,7 @@ void Heap::Scavenge() {
StoreBufferRebuildScope scope(this,
store_buffer(),
&ScavengeStoreBufferCallback);
- store_buffer()->IteratePointersToNewSpace(&ScavengeObject);
+ store_buffer()->IteratePointersToNewSpace(&ScavengeObject, false);
}
// Copy objects reachable from simple cells by scavenging cell values
Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index
980c039792652b442045708b8e2c9d12502594af..62c980e3076d93908cb8ef4278500b94efabcf16
100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -2930,9 +2930,6 @@ void MarkCompactCollector::EvacuateNewSpace() {
object->address(),
size,
NEW_SPACE);
- } else {
- // Mark dead objects in the new space with null in their map field.
- Memory::Address_at(object->address()) = NULL;
}
}
@@ -3354,7 +3351,7 @@ void
MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
StoreBufferRebuildScope scope(heap_,
heap_->store_buffer(),
&Heap::ScavengeStoreBufferCallback);
- heap_->store_buffer()->IteratePointersToNewSpace(&UpdatePointer);
+ heap_->store_buffer()->IteratePointersToNewSpace(&UpdatePointer, true);
}
{ GCTracer::Scope gc_scope(tracer_,
Index: src/store-buffer.cc
diff --git a/src/store-buffer.cc b/src/store-buffer.cc
index
0386280de65b0948c22c54638cbba4c0e3646457..0649bc72b772bb2be5e32c63124472510e610278
100644
--- a/src/store-buffer.cc
+++ b/src/store-buffer.cc
@@ -364,7 +364,8 @@ void StoreBuffer::VerifyPointers(PagedSpace* space,
reinterpret_cast<PagedSpace*>(page->owner()),
page,
region_callback,
- &DummyScavengePointer);
+ &DummyScavengePointer,
+ false);
}
}
@@ -412,13 +413,22 @@ void StoreBuffer::GCEpilogue() {
void StoreBuffer::FindPointersToNewSpaceInRegion(
- Address start, Address end, ObjectSlotCallback slot_callback) {
+ Address start,
+ Address end,
+ ObjectSlotCallback slot_callback,
+ bool clear_maps) {
for (Address slot_address = start;
slot_address < end;
slot_address += kPointerSize) {
Object** slot = reinterpret_cast<Object**>(slot_address);
if (heap_->InNewSpace(*slot)) {
HeapObject* object = reinterpret_cast<HeapObject*>(*slot);
+ Address& map_field = Memory::Address_at(object->address());
+ // The new space object was not promoted if it still contains a map
+ // pointer. Clear the map field now lazily.
+ if (clear_maps && heap_->map_space()->Contains(map_field)) {
+ map_field = NULL;
+ }
ASSERT(object->IsHeapObject());
slot_callback(reinterpret_cast<HeapObject**>(slot), object);
if (heap_->InNewSpace(*slot)) {
@@ -446,7 +456,8 @@ static inline Address MapEndAlign(Address addr) {
void StoreBuffer::FindPointersToNewSpaceInMaps(
Address start,
Address end,
- ObjectSlotCallback slot_callback) {
+ ObjectSlotCallback slot_callback,
+ bool clear_maps) {
ASSERT(MapStartAlign(start) == start);
ASSERT(MapEndAlign(end) == end);
@@ -460,7 +471,8 @@ void StoreBuffer::FindPointersToNewSpaceInMaps(
FindPointersToNewSpaceInRegion(pointer_fields_start,
pointer_fields_end,
- slot_callback);
+ slot_callback,
+ clear_maps);
map_address += Map::kSize;
}
}
@@ -469,7 +481,8 @@ void StoreBuffer::FindPointersToNewSpaceInMaps(
void StoreBuffer::FindPointersToNewSpaceInMapsRegion(
Address start,
Address end,
- ObjectSlotCallback slot_callback) {
+ ObjectSlotCallback slot_callback,
+ bool clear_maps) {
Address map_aligned_start = MapStartAlign(start);
Address map_aligned_end = MapEndAlign(end);
@@ -478,7 +491,8 @@ void StoreBuffer::FindPointersToNewSpaceInMapsRegion(
FindPointersToNewSpaceInMaps(map_aligned_start,
map_aligned_end,
- slot_callback);
+ slot_callback,
+ clear_maps);
}
@@ -500,7 +514,8 @@ void StoreBuffer::FindPointersToNewSpaceOnPage(
PagedSpace* space,
Page* page,
RegionCallback region_callback,
- ObjectSlotCallback slot_callback) {
+ ObjectSlotCallback slot_callback,
+ bool clear_maps) {
Address visitable_start = page->area_start();
Address end_of_page = page->area_end();
@@ -520,7 +535,8 @@ void StoreBuffer::FindPointersToNewSpaceOnPage(
// After calling this the special garbage section may have moved.
(this->*region_callback)(visitable_start,
visitable_end,
- slot_callback);
+ slot_callback,
+ clear_maps);
if (visitable_end >= space->top() && visitable_end <
space->limit()) {
visitable_end = space->limit();
visitable_start = visitable_end;
@@ -551,13 +567,15 @@ void StoreBuffer::FindPointersToNewSpaceOnPage(
if (visitable_start != visitable_end) {
(this->*region_callback)(visitable_start,
visitable_end,
- slot_callback);
+ slot_callback,
+ clear_maps);
}
}
void StoreBuffer::IteratePointersInStoreBuffer(
- ObjectSlotCallback slot_callback) {
+ ObjectSlotCallback slot_callback,
+ bool clear_maps) {
Address* limit = old_top_;
old_top_ = old_start_;
{
@@ -570,6 +588,12 @@ void StoreBuffer::IteratePointersInStoreBuffer(
Object* object = *slot;
if (heap_->InFromSpace(object)) {
HeapObject* heap_object = reinterpret_cast<HeapObject*>(object);
+ Address& map_field = Memory::Address_at(heap_object->address());
+ // The new space object was not promoted if it still contains a map
+ // pointer. Clear the map field now lazily.
+ if (clear_maps && heap_->map_space()->Contains(map_field)) {
+ map_field = NULL;
+ }
slot_callback(reinterpret_cast<HeapObject**>(slot), heap_object);
if (heap_->InNewSpace(*slot)) {
EnterDirectlyIntoStoreBuffer(reinterpret_cast<Address>(slot));
@@ -581,7 +605,8 @@ void StoreBuffer::IteratePointersInStoreBuffer(
}
-void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback
slot_callback) {
+void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback
slot_callback,
+ bool clear_maps) {
// We do not sort or remove duplicated entries from the store buffer
because
// we expect that callback will rebuild the store buffer thus removing
// all duplicates and pointers to old space.
@@ -590,7 +615,7 @@ void
StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
// TODO(gc): we want to skip slots on evacuation candidates
// but we can't simply figure that out from slot address
// because slot can belong to a large object.
- IteratePointersInStoreBuffer(slot_callback);
+ IteratePointersInStoreBuffer(slot_callback, clear_maps);
// We are done scanning all the pointers that were in the store buffer,
but
// there may be some pages marked scan_on_scavenge that have pointers to
new
@@ -619,7 +644,7 @@ void
StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
ASSERT(array->IsFixedArray());
Address start = array->address();
Address end = start + array->Size();
- FindPointersToNewSpaceInRegion(start, end, slot_callback);
+ FindPointersToNewSpaceInRegion(start, end, slot_callback,
clear_maps);
} else {
Page* page = reinterpret_cast<Page*>(chunk);
PagedSpace* owner = reinterpret_cast<PagedSpace*>(page->owner());
@@ -629,7 +654,8 @@ void
StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
(owner == heap_->map_space() ?
&StoreBuffer::FindPointersToNewSpaceInMapsRegion :
&StoreBuffer::FindPointersToNewSpaceInRegion),
- slot_callback);
+ slot_callback,
+ clear_maps);
}
}
}
Index: src/store-buffer.h
diff --git a/src/store-buffer.h b/src/store-buffer.h
index
520cbc01626b698607928dbd83638ba220096fb2..ca92a6a7b31e15731e7f2102e47c095b394f0336
100644
--- a/src/store-buffer.h
+++ b/src/store-buffer.h
@@ -43,8 +43,10 @@ class StoreBuffer;
typedef void (*ObjectSlotCallback)(HeapObject** from, HeapObject* to);
-typedef void (StoreBuffer::*RegionCallback)(
- Address start, Address end, ObjectSlotCallback slot_callback);
+typedef void (StoreBuffer::*RegionCallback)(Address start,
+ Address end,
+ ObjectSlotCallback
slot_callback,
+ bool clear_maps);
// Used to implement the write barrier by collecting addresses of pointers
// between spaces.
@@ -81,7 +83,7 @@ class StoreBuffer {
// Iterates over all pointers that go from old space to new space. It
will
// delete the store buffer as it starts so the callback should reenter
// surviving old-to-new pointers into the store buffer to rebuild it.
- void IteratePointersToNewSpace(ObjectSlotCallback callback);
+ void IteratePointersToNewSpace(ObjectSlotCallback callback, bool
clear_maps);
static const int kStoreBufferOverflowBit = 1 << (14 + kPointerSizeLog2);
static const int kStoreBufferSize = kStoreBufferOverflowBit;
@@ -166,7 +168,8 @@ class StoreBuffer {
void FindPointersToNewSpaceInRegion(Address start,
Address end,
- ObjectSlotCallback slot_callback);
+ ObjectSlotCallback slot_callback,
+ bool clear_maps);
// For each region of pointers on a page in use from an old space call
// visit_pointer_region callback.
@@ -182,20 +185,24 @@ class StoreBuffer {
void FindPointersToNewSpaceInMaps(
Address start,
Address end,
- ObjectSlotCallback slot_callback);
+ ObjectSlotCallback slot_callback,
+ bool clear_maps);
void FindPointersToNewSpaceInMapsRegion(
Address start,
Address end,
- ObjectSlotCallback slot_callback);
+ ObjectSlotCallback slot_callback,
+ bool clear_maps);
void FindPointersToNewSpaceOnPage(
PagedSpace* space,
Page* page,
RegionCallback region_callback,
- ObjectSlotCallback slot_callback);
+ ObjectSlotCallback slot_callback,
+ bool clear_maps);
- void IteratePointersInStoreBuffer(ObjectSlotCallback slot_callback);
+ void IteratePointersInStoreBuffer(ObjectSlotCallback slot_callback,
+ bool clear_maps);
#ifdef VERIFY_HEAP
void VerifyPointers(PagedSpace* space, RegionCallback region_callback);
--
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