private static UIntPtr FirstPtrFromInteriorTable(UIntPtr c)
{
UIntPtr cardAddr = CardTable.CardAddr(c);
UIntPtr nextCardAddr = CardTable.NextCardAddr(c);
UIntPtr page = PageTable.Page(cardAddr);
UIntPtr pageAddr = PageTable.PageAddr(page);
UIntPtr currAddr;
if (page == 0)
{
currAddr = PtrToNextObject(pageAddr,
(UIntPtr)PreHeader.Size, nextCardAddr);
}
else
{
short offset = PageTable.Extra(page);
currAddr = UIntPtr.Zero;
if (offset != InteriorPtrTable.OFFSET_NO_DATA)
{
currAddr = pageAddr + (offset - InteriorPtrTable.OFFSET_SKEW);
}
// In general, we expect currAddr <= cardAddr. Or in the extreme
// case, when the object starts from the page boundary,
// currAddr - Object.HEADER_BYTES <= cardAddr. The contrary
// cases has to be handled by searching previous pages.
if (currAddr == UIntPtr.Zero ||
(currAddr > cardAddr &&
currAddr - PreHeader.Size > cardAddr))
{
// look from previous pages, in case that an object on
// them spans to the current page. In that case, we should
// should use that object's ptr.
currAddr = InteriorPtrTable.Last(page - 1);
// Usually, Last() returns a pointer before or at the page
// boundary. However, there is one exception: when an object
// exactly fits to the last byte of the previous page, and the next
// object starts right from the page boundary (the first byte of
// the next page), then the pointer to this next object is returned.
// Example found: objPtr =3d09fa8, size=60, pageboundary=
// 3d0a000, next objPtr=3d0a008. Then returned pointer is
// 3d0a008, which is beyond the page boundary.
VTable.Assert(currAddr <= pageAddr ||
currAddr - PreHeader.Size <= pageAddr,
"object is expected before page or right at the beginning of it");
}
}
VTable.Assert(currAddr < nextCardAddr, "object is expected before next card");
while (currAddr < nextCardAddr)
{
if (Allocator.IsAlignment(currAddr))
{
currAddr += UIntPtr.Size;
}
else if (BumpAllocator.IsUnusedSpace(currAddr))
{
currAddr = PageTable.PagePad(currAddr) + PreHeader.Size;
}
else
{
UIntPtr size = InteriorPtrTable.ObjectSize(currAddr);
if (currAddr + size - PreHeader.Size > cardAddr)
{
return(currAddr);
}
currAddr += size;
}
}
VTable.Assert(false, "No obj ptr found by looking at interior table");
return(UIntPtr.Zero);
}
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);
}
}
}