private static void CleanPageTail(UIntPtr postPinnedAddr)
{
if (!PageTable.PageAligned(postPinnedAddr))
{
// If postPinnedAddr points to the first object on its page,
// then we are removing all objects (specifically the part
// of the object that the InteriorPtrTable tracks, the
// vtables) from the page, so we should clear the page's
// entry in the InteriorPtrTable.
UIntPtr page = PageTable.Page(postPinnedAddr);
UIntPtr firstObjPtr = InteriorPtrTable.First(page);
if (firstObjPtr > postPinnedAddr)
{
VTable.Assert
(firstObjPtr - PreHeader.Size >= postPinnedAddr,
"postPinnedAddr should not point to the "
+ "interior of an object (1)");
InteriorPtrTable.ClearFirst(page);
}
else if (!BumpAllocator.IsUnusedSpace(firstObjPtr))
{
UIntPtr firstObjSize =
InteriorPtrTable.ObjectSize(firstObjPtr);
VTable.Assert
(firstObjPtr + firstObjSize - PreHeader.Size
<= postPinnedAddr,
"postPinnedAddr should not point to the "
+ "interior of an object (2)");
}
UIntPtr byteCount = PageTable.PagePad(postPinnedAddr)
- postPinnedAddr;
Util.MemClear(postPinnedAddr, byteCount);
BumpAllocator.WriteUnusedMarker(postPinnedAddr);
if (GC.remsetType == RemSetType.Cards && byteCount > 0)
{
UIntPtr firstCard = CardTable.CardNo(postPinnedAddr);
UIntPtr lastCard =
CardTable.CardNo(postPinnedAddr + byteCount - 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
<= postPinnedAddr) ||
(objPtr >= postPinnedAddr),
"Object should be totally "
+ "above or below postPinnedAddr");
if (objPtr >= postPinnedAddr)
{
OffsetTable.ClearCards(firstCard, firstCard);
}
}
OffsetTable.ClearCards(firstCard + 1, lastCard);
}
}
}
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;
}