internal unsafe override void Visit(UIntPtr *loc)
{
UIntPtr addr = *loc;
UIntPtr page = PageTable.Page(addr);
PageType pageType = PageTable.Type(page);
if (!PageTable.IsZombiePage(pageType))
{
VTable.Assert(PageTable.IsGcPage(pageType) ||
PageTable.IsNonGcPage(pageType) ||
PageTable.IsStackPage(pageType) ||
PageTable.IsSharedPage(pageType),
"Semispace:ForwardOnlyReferenceVisitor");
return;
}
PageType gen = PageTable.ZombieToLive(pageType);
UIntPtr vtableAddr = Allocator.GetObjectVTable(addr);
UIntPtr vtablePageIndex = PageTable.Page(vtableAddr);
if (PageTable.Type(vtablePageIndex) == gen)
{
// The vtable field is really a forwarding pointer
*loc = vtableAddr;
}
else
{
// The object was not live
*loc = UIntPtr.Zero;
}
}
internal void ProcessPinnedPages(ReferenceVisitor ptrVisitor)
{
if (pinnedPageList == null || pinnedPageList.Count == 0)
{
return;
}
pinnedPageList.Sort(comparer);
int limit = pinnedPageList.Count;
for (int i = 0; i < limit; i++)
{
UIntPtr page = (UIntPtr)pinnedPageList[i];
PageType fromSpaceType = PageTable.Type(page);
VTable.Assert(PageTable.IsZombiePage(fromSpaceType),
"Semispace:RegisterPinnedReference:2");
PageType toSpaceType =
PageTable.ZombieToLive(fromSpaceType);
PageTable.SetType(page, toSpaceType);
}
int pageIndex = 0;
while (pageIndex < limit)
{
UIntPtr startPage = (UIntPtr)pinnedPageList[pageIndex];
UIntPtr endPage = startPage + 1;
pageIndex++;
while (pageIndex < limit &&
(UIntPtr)pinnedPageList[pageIndex] == endPage)
{
pageIndex++;
endPage++;
}
UIntPtr objectAddr = FirstPinnedObjectAddr(startPage);
UIntPtr pastAddr = PostPinnedObjectAddr(endPage);
while (objectAddr < pastAddr)
{
if (Allocator.IsAlignment(objectAddr))
{
objectAddr += UIntPtr.Size;
}
else if (BumpAllocator.IsUnusedSpace(objectAddr))
{
objectAddr = (PageTable.PagePad(objectAddr) +
PreHeader.Size);
}
else
{
Object obj = Magic.fromAddress(objectAddr);
objectAddr += ptrVisitor.VisitReferenceFields(obj);
}
}
}
}
// BUGBUG: We are allocating an ArrayList while the collector
// is running. If the ArrayList gets big enough to be
// allocated in the older generation, then the RemSet has the
// potential to overflow since the boxed integers will reside
// in the young generation. We should eventually eliminate
// the use of ArrayList in this class as well as avoid boxing
// the page indices.
internal unsafe override void Visit(UIntPtr *loc)
{
UIntPtr addr = *loc;
UIntPtr page = PageTable.Page(addr);
PageType pageType = PageTable.Type(page);
if (!PageTable.IsZombiePage(pageType))
{
VTable.Assert(PageTable.IsGcPage(pageType) ||
PageTable.IsNonGcPage(pageType) ||
PageTable.IsStackPage(pageType) ||
PageTable.IsSharedPage(pageType) ||
VTable.BuildC2Mods,
"Semispace:RegisterPinnedReference:1");
return;
}
PageType gen = PageTable.ZombieToLive(pageType);
UIntPtr pinnedObjectAddr = InteriorPtrTable.Find(addr);
if (pinnedPageList == null)
{
pinnedPageList = new ArrayList();
comparer = new UIntPtrComparer();
}
Object pinnedObject = Magic.fromAddress(pinnedObjectAddr);
UIntPtr objectSize =
ObjectLayout.ObjectSize(pinnedObjectAddr,
pinnedObject.vtable);
UIntPtr beforeObjectAddr = pinnedObjectAddr - PreHeader.Size;
UIntPtr pastObjectAddr = beforeObjectAddr + objectSize;
UIntPtr firstPage = PageTable.Page(beforeObjectAddr);
UIntPtr lastPage = PageTable.Page(pastObjectAddr - 1);
for (UIntPtr i = firstPage; i <= lastPage; i++)
{
if (!pinnedPageList.Contains(i))
{
Trace.Log(Trace.Area.Pointer,
"RegPin: ptr={0} page={1} gen={2}",
__arglist(pinnedObjectAddr, i, gen));
GenerationalCollector.gcPromotedTable[(int)gen - 1] +=
PageTable.PageSize;
pinnedPageList.Add(i);
}
}
}
internal unsafe override void Visit(UIntPtr *loc)
{
UIntPtr objAddr = *loc;
UIntPtr page = PageTable.Page(objAddr);
Trace.Log(Trace.Area.Pointer,
"FwdRef: loc={0}, addr={1}, page={2}",
__arglist(loc, objAddr, page));
PageType pageType = PageTable.Type(page);
if (!PageTable.IsZombiePage(pageType))
{
VTable.Assert(PageTable.IsGcPage(pageType) ||
PageTable.IsNonGcPage(pageType) ||
PageTable.IsStackPage(pageType) ||
PageTable.IsSharedPage(pageType),
"Semispace:ForwardReferenceVisitor");
return;
}
PageType gen = PageTable.ZombieToLive(pageType);
VTable.Assert(gen > MIN_GENERATION);
Object obj = Magic.fromAddress(objAddr);
UIntPtr vtableAddr = *obj.VTableFieldAddr;
UIntPtr vtablePageIndex = PageTable.Page(vtableAddr);
if (PageTable.Type(vtablePageIndex) == gen)
{
// The vtable field is really a forwarding pointer
Trace.Log(Trace.Area.Pointer,
"FwdRef: VT fwd: {0} -> {1}",
__arglist(objAddr, vtableAddr));
*loc = vtableAddr;
return;
}
Object newObject = copyScanners[(int)gen].Copy(obj);
*loc = Magic.addressOf(newObject);
}
private Object CopyLarge(Object obj, UIntPtr size)
{
// Don't copy large objects.
// Change the page type instead.
UIntPtr startAddr = Magic.addressOf(obj) - PreHeader.Size;
UIntPtr startPage = PageTable.Page(startAddr);
UIntPtr endPage = PageTable.Page(startAddr + size - 1) + 1;
VTable.Assert(this.pageType ==
PageTable.ZombieToLive(PageTable.Type(startPage)));
PageTable.SetType(startPage, (endPage - startPage),
this.pageType);
UIntPtr sizeOfPages = PageTable.PageSize * (endPage - startPage);
Trace.Log(Trace.Area.Pointer,
"FwdRef: large object: {0} gen: {1} pagesize: {2}",
__arglist(Magic.addressOf(obj), this.pageType,
sizeOfPages));
GenerationalGCData.gcPromotedTable[(int)this.pageType - 1] +=
sizeOfPages;
this.AddWork(startAddr, startAddr + size);
return(obj);
}
internal void CleanPinnedPages()
{
if (pinnedPageList == null || pinnedPageList.Count == 0)
{
return;
}
int pageIndex = 0;
int limit = pinnedPageList.Count;
UIntPtr lastPostPinnedAddr = UIntPtr.Zero;
while (pageIndex < limit)
{
UIntPtr startPage = (UIntPtr)pinnedPageList[pageIndex];
UIntPtr endPage = startPage + 1;
pageIndex++;
while (pageIndex < limit &&
(UIntPtr)pinnedPageList[pageIndex] == endPage)
{
pageIndex++;
endPage++;
}
// Zero out the area between the start of the page and
// the first object on the page
UIntPtr firstObjectAddr = FirstPinnedObjectAddr(startPage);
UIntPtr firstAddr = firstObjectAddr - PreHeader.Size;
UIntPtr trashAddr = PageTable.PageAddr(startPage);
if (firstAddr < trashAddr)
{
// The first object "spills" into the previous page,
// presumably by no more than HEADER_BYTES bytes
VTable.Assert(
PageTable.Page(firstAddr) == startPage - 1,
"Semispace:RegisterPinnedReference:3");
// Prepare to zero the preceding page unless it also
// had pinned data on it
trashAddr = PageTable.PageAddr(startPage - 1);
InteriorPtrTable.ClearFirst(startPage - 1);
if (trashAddr >= lastPostPinnedAddr)
{
// Need to mark the spilled-onto page live to
// keep the spilled data around
PageType fromSpaceType =
PageTable.Type(startPage - 1);
VTable.Assert(
PageTable.IsZombiePage(fromSpaceType),
"Semispace:RegisterPinnedReference:4");
PageType toSpaceType =
PageTable.ZombieToLive(fromSpaceType);
PageTable.SetType(startPage - 1, toSpaceType);
}
}
// If lastPostPinnedAddr is on the page that trashAddr
// starts, pinned data from the last run of pinned pages
// and pinned data from this run of pinned data are on the
// same page, so just write alignment tokens from
// lastPostPinnedAddr to the first pinned object.
// Otherwise, write an unused marker at lastPostPinnedAddr
// since the rest of its page must be copied or dead.
if (trashAddr < lastPostPinnedAddr)
{
trashAddr = lastPostPinnedAddr;
}
else
{
CleanPageTail(lastPostPinnedAddr);
}
if (GC.remsetType == RemSetType.Cards &&
trashAddr < firstAddr)
{
UIntPtr firstCard = CardTable.CardNo(trashAddr);
UIntPtr lastCard = CardTable.CardNo(firstAddr - 1);
if (!OffsetTable.NoObjectPtrToTheCard(firstCard))
{
UIntPtr offset = OffsetTable.GetOffset(firstCard);
UIntPtr objPtr =
CardTable.CardAddr(firstCard) + offset;
UIntPtr size = OffsetTable.ObjectSize(objPtr);
VTable.Assert
((objPtr + size - PreHeader.Size <= trashAddr) ||
(objPtr >= trashAddr),
"Object should be totally "
+ "above or below trashAddr");
if (objPtr >= trashAddr)
{
// The offset in this card needs to be updated
OffsetTable.ClearCards(firstCard, firstCard);
}
}
OffsetTable.ClearCards(firstCard + 1, lastCard - 1);
if (lastCard != CardTable.CardNo(firstObjectAddr))
{
OffsetTable.ClearCards(lastCard, lastCard);
}
else
{
VTable.Assert(OffsetTable.GetOffset(lastCard)
>= (firstObjectAddr
- CardTable.CardAddr(lastCard)),
"wrong offset");
}
}
{
// trashAddr should go back at most one page.
UIntPtr trashPage = PageTable.Page(trashAddr);
UIntPtr firstObjectAddrPage =
PageTable.Page(firstObjectAddr);
VTable.Assert((trashPage == firstObjectAddrPage - 1) ||
(trashPage == firstObjectAddrPage));
}
// If the InteriorPtrTable already had a value, then this is
// redundant, but if the call to First above has to compute
// the value, then (since it won't store it in the table) we
// should store it. Why? At this point the previous page
// would be "connected" to this one. After this collection
// the previous page will be unused or re-used and unrelated
// to this page and subsequent calls to First would then
// rely on it making the leap between unrelated pages.
InteriorPtrTable.SetFirst(firstObjectAddr);
while (trashAddr < firstAddr)
{
Allocator.WriteAlignment(trashAddr);
trashAddr += UIntPtr.Size;
}
// Zero out the area between the last whole object on
// the last page and the end of the last page
UIntPtr pastAddr = PostPinnedObjectAddr(endPage);
UIntPtr newEndPage =
PageTable.Page(PageTable.PagePad(pastAddr));
while (endPage < newEndPage)
{
// The last object spills into the next page(s), so
// mark those page(s) live
PageType fromPageType = PageTable.Type(endPage);
if (PageTable.IsZombiePage(fromPageType))
{
PageType toSpaceType =
PageTable.ZombieToLive(fromPageType);
PageTable.SetType(endPage, toSpaceType);
}
else
{
// final page might be live already because
// something else on it was pinned.
// pageIndex has already been incremented,
// so it points to the start of the next
// set of contiguous pages
VTable.Assert(
PageTable.IsLiveGcPage(fromPageType) &&
pageIndex < limit &&
endPage ==
(UIntPtr)pinnedPageList[pageIndex],
"Semispace:RegisterPinnedReference:5");
}
++endPage;
}
lastPostPinnedAddr = pastAddr;
}
CleanPageTail(lastPostPinnedAddr);
pinnedPageList = null;
comparer = null;
}