Revision: 19024
Author: [email protected]
Date: Mon Feb 3 12:20:15 2014 UTC
Log: Make memento checks more stable. Add filler at the end of new
space and check if object and memento are on the same new space page.
BUG=
[email protected], [email protected]
Review URL: https://codereview.chromium.org/152613002
http://code.google.com/p/v8/source/detail?r=19024
Modified:
/branches/bleeding_edge/src/heap-inl.h
/branches/bleeding_edge/src/heap.cc
/branches/bleeding_edge/src/mark-compact.cc
/branches/bleeding_edge/src/objects.cc
/branches/bleeding_edge/src/spaces.h
=======================================
--- /branches/bleeding_edge/src/heap-inl.h Sat Feb 1 10:35:36 2014 UTC
+++ /branches/bleeding_edge/src/heap-inl.h Mon Feb 3 12:20:15 2014 UTC
@@ -493,15 +493,21 @@
if (!FLAG_allocation_site_pretenuring ||
!AllocationSite::CanTrack(object->map()->instance_type())) return;
- // Either object is the last object in the from space, or there is
another
- // object of at least word size (the header map word) following it, so
- // suffices to compare ptr and top here.
- Address ptr = object->address() + object->Size();
- Address top = heap->new_space()->FromSpacePageHigh();
- ASSERT(ptr == top || ptr + HeapObject::kHeaderSize <= top);
- if (ptr == top) return;
+ // Check if there is potentially a memento behind the object. If
+ // the last word of the momento is on another page we return
+ // immediatelly. Note that we do not have to compare with the current
+ // top pointer of the from space page, since we always install filler
+ // objects above the top pointer of a from space page when performing
+ // a garbage collection.
+ Address object_address = object->address();
+ Address memento_address = object_address + object->Size();
+ Address last_memento_word_address = memento_address + kPointerSize;
+ if (!NewSpacePage::OnSamePage(object_address,
+ last_memento_word_address)) {
+ return;
+ }
- HeapObject* candidate = HeapObject::FromAddress(ptr);
+ HeapObject* candidate = HeapObject::FromAddress(memento_address);
if (candidate->map() != heap->allocation_memento_map()) return;
AllocationMemento* memento = AllocationMemento::cast(candidate);
=======================================
--- /branches/bleeding_edge/src/heap.cc Fri Jan 31 16:52:17 2014 UTC
+++ /branches/bleeding_edge/src/heap.cc Mon Feb 3 12:20:15 2014 UTC
@@ -767,6 +767,18 @@
// allocation attempts to go through.
allocation_timeout_ = Max(6, FLAG_gc_interval);
#endif
+
+ // There may be an allocation memento behind every object in new space.
+ // If we evacuate a not full new space or if we are on the last page of
+ // the new space, then there may be uninitialized memory behind the top
+ // pointer of the new space page. We store a filler object there to
+ // identify the unused space.
+ Address from_top = new_space_.top();
+ Address from_limit = new_space_.limit();
+ if (from_top < from_limit) {
+ int remaining_in_page = static_cast<int>(from_limit - from_top);
+ CreateFillerObjectAt(from_top, remaining_in_page);
+ }
if (collector == SCAVENGER && !incremental_marking()->IsStopped()) {
if (FLAG_trace_incremental_marking) {
=======================================
--- /branches/bleeding_edge/src/mark-compact.cc Sat Feb 1 10:35:36 2014 UTC
+++ /branches/bleeding_edge/src/mark-compact.cc Mon Feb 3 12:20:15 2014 UTC
@@ -3006,20 +3006,6 @@
// live objects.
new_space->Flip();
new_space->ResetAllocationInfo();
-
- // UpdateAllocationSiteFeedback expects that only objects at the end of
- // newspace are not guaranteed to have the next word clear. It relies on
- // FromSpacePageHigh to check whether an object is at the end of
newspace.
- // However, it is possible that newspace is being evacuated without it
being
- // full, e.g. to make the heap iterable, hence top will not equal high.
In
- // that case, fill up newspace with a filler to ensure the next word is
- // cleared.
- if (FLAG_allocation_site_pretenuring &&
- from_top < new_space->FromSpacePageHigh()) {
- Address limit = NewSpacePage::FromLimit(from_top)->area_end();
- int remaining_in_page = static_cast<int>(limit - from_top);
- heap()->CreateFillerObjectAt(from_top, remaining_in_page);
- }
int survivors_size = 0;
=======================================
--- /branches/bleeding_edge/src/objects.cc Fri Jan 31 16:52:17 2014 UTC
+++ /branches/bleeding_edge/src/objects.cc Mon Feb 3 12:20:15 2014 UTC
@@ -12837,16 +12837,27 @@
Heap* heap = GetHeap();
if (!heap->InNewSpace(this)) return this;
+
+ // Check if there is potentially a memento behind the object. If
+ // the last word of the momento is on another page we return
+ // immediatelly.
+ Address object_address = address();
+ Address memento_address = object_address + JSArray::kSize;
+ Address last_memento_word_address = memento_address + kPointerSize;
+ if (!NewSpacePage::OnSamePage(object_address,
+ last_memento_word_address)) {
+ return this;
+ }
// Either object is the last object in the new space, or there is another
// object of at least word size (the header map word) following it, so
// suffices to compare ptr and top here.
- Address ptr = address() + JSArray::kSize;
Address top = heap->NewSpaceTop();
- ASSERT(ptr == top || ptr + HeapObject::kHeaderSize <= top);
- if (ptr == top) return this;
+ ASSERT(memento_address == top ||
+ memento_address + HeapObject::kHeaderSize <= top);
+ if (memento_address == top) return this;
- HeapObject* candidate = HeapObject::FromAddress(ptr);
+ HeapObject* candidate = HeapObject::FromAddress(memento_address);
if (candidate->map() != heap->allocation_memento_map()) return this;
AllocationMemento* memento = AllocationMemento::cast(candidate);
=======================================
--- /branches/bleeding_edge/src/spaces.h Thu Jan 23 13:02:27 2014 UTC
+++ /branches/bleeding_edge/src/spaces.h Mon Feb 3 12:20:15 2014 UTC
@@ -2060,6 +2060,12 @@
static inline NewSpacePage* FromLimit(Address address_limit) {
return NewSpacePage::FromAddress(address_limit - 1);
}
+
+ // Checks if address1 and address2 are on the same new space page.
+ static inline bool OnSamePage(Address address1, Address address2) {
+ return NewSpacePage::FromAddress(address1) ==
+ NewSpacePage::FromAddress(address2);
+ }
private:
// Create a NewSpacePage object that is only used as anchor
@@ -2454,6 +2460,12 @@
ASSERT(to_space_.current_page()->ContainsLimit(top));
allocation_info_.set_top(top);
}
+
+ // Return the address of the allocation pointer limit in the active
semispace.
+ Address limit() {
+
ASSERT(to_space_.current_page()->ContainsLimit(allocation_info_.limit()));
+ return allocation_info_.limit();
+ }
// Return the address of the first object in the active semispace.
Address bottom() { return to_space_.space_start(); }
--
--
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