internal static unsafe void VerifyFirst(UIntPtr previousObjectAddr,
UIntPtr objectAddr)
{
UIntPtr page = PageTable.Page(objectAddr);
if (previousObjectAddr != UIntPtr.Zero)
{
UIntPtr previousPage = PageTable.Page(previousObjectAddr);
UIntPtr pageCursor = previousPage + 1;
while (pageCursor < page)
{
uint cursorOffset = PageTable.Extra(pageCursor);
UIntPtr objAddr = (PageTable.PageAddr(pageCursor) +
cursorOffset - OFFSET_SKEW);
if (!(cursorOffset <= OFFSET_NO_DATA ||
BumpAllocator.IsUnusedSpace(objAddr) ||
Allocator.IsAlignment(objAddr) ||
BumpAllocator.IsRestOfPageZero(objAddr)))
{
VTable.DebugPrint
("cursorOffset={0:x} OFFSET_NO_DATA={1:x} objAddr={2:x} unused={3} isalign={4} iszero={5}\n",
__arglist((cursorOffset),
(OFFSET_NO_DATA),
((long)objAddr),
(BumpAllocator.IsUnusedSpace(objAddr)),
(Allocator.IsAlignment(objAddr)),
(BumpAllocator.IsRestOfPageZero(objAddr))));
}
VTable.Assert(cursorOffset <= OFFSET_NO_DATA ||
BumpAllocator.IsUnusedSpace(objAddr) ||
Allocator.IsAlignment(objAddr) ||
BumpAllocator.IsRestOfPageZero(objAddr),
"VerifyFirst 1");
pageCursor++;
}
}
uint offset = PageTable.Extra(page);
if (offset > OFFSET_NO_DATA)
{
UIntPtr firstAddr =
PageTable.PageAddr(page) + offset - OFFSET_SKEW;
if (!(firstAddr == objectAddr ||
(firstAddr + UIntPtr.Size == objectAddr &&
Allocator.IsAlignment(firstAddr))))
{
VTable.DebugPrint
("firstAddr={0:x} objectAddr={1:x} isalign={2}\n",
__arglist(((long)firstAddr),
((long)objectAddr),
(Allocator.IsAlignment(firstAddr))));
}
VTable.Assert(firstAddr == objectAddr ||
(firstAddr + 4 == objectAddr &&
Allocator.IsAlignment(firstAddr)),
"VerifyFirst 2");
}
}
internal static unsafe void ClearThreadStack(Thread thread)
{
short threadIndex = (short)thread.threadIndex;
UIntPtr endPage = PageTable.Page(CallStack.StackBase(thread));
UIntPtr startPage = endPage - 1;
VTable.Assert(PageTable.IsStackPage(PageTable.Type(startPage)));
VTable.Assert(PageTable.Extra(startPage) == threadIndex);
while (startPage > 0 &&
PageTable.IsStackPage(PageTable.Type(startPage - 1)) &&
PageTable.Extra(startPage - 1) == threadIndex)
{
startPage--;
}
UIntPtr startAddr = PageTable.PageAddr(startPage);
UIntPtr size = PageTable.RegionSize(endPage - startPage);
SetUnallocatedPages(startAddr, size);
}
/*
* Returns a pointer to the beginning of an object such that the
* pointer is less than or equal to addr. N.B. Before may return a
* pointer to an alignment or an unused space token.
*/
private static UIntPtr Before(UIntPtr addr)
{
UIntPtr page = PageTable.Page(addr);
uint offset = PageTable.Extra(page);
// OFFSET_NO_DATA and negative offsets should always fail this
// test.
if (PageTable.PageAddr(page) + (offset - OFFSET_SKEW) > addr)
{
// If the addr is an interior pointer of an object on a
// previous page, go back one entry.
--page;
offset = PageTable.Extra(page);
}
if (offset == OFFSET_NO_DATA)
{
// Scroll back until we find a page entry with real data in
// it. This handles the case of a large object allocated
// across pages.
do
{
--page;
offset = PageTable.Extra(page);
}while (offset == OFFSET_NO_DATA);
}
VTable.Assert(offset > OFFSET_NO_DATA, "No offset data");
// Unused: since we currently do not use negative offsets in the
// page table. This would be more efficient for really big
// objects, but the OFFSET_NO_DATA value works fine too.
/*
* // Scroll backwards using big steps. Offset will never be
* // OFFSET_NO_DATA in this loop.
* while (offset < OFFSET_NO_DATA) {
* entry += (offset - OFFSET_SKEW);
* offset = *entry;
* }
*/
return(PageTable.PageAddr(page) + (offset - OFFSET_SKEW));
}
/*
* Returns a pointer to the first object on the given page.
* N.B. If called on a page with no ~allocated~ first object it may
* return a pointer to the unused space token.
*/
internal static UIntPtr First(UIntPtr page)
{
uint offset = PageTable.Extra(page);
UIntPtr pageAddr = PageTable.PageAddr(page);
UIntPtr currAddr;
if (offset != OFFSET_NO_DATA)
{
currAddr = pageAddr + (offset - OFFSET_SKEW);
}
else
{
currAddr = Before(pageAddr);
VTable.Assert(currAddr <= pageAddr);
UIntPtr nextPageStart = PageTable.PagePad(currAddr + 1);
while (currAddr < pageAddr)
{
if (Allocator.IsAlignment(currAddr))
{
currAddr += UIntPtr.Size;
}
else if (BumpAllocator.IsUnusedSpace(currAddr))
{
currAddr = PageTable.PagePad(currAddr) + PreHeader.Size;
}
else
{
if (currAddr >= nextPageStart)
{
InteriorPtrTable.SetFirst(currAddr);
nextPageStart = PageTable.PagePad(currAddr + 1);
}
currAddr += ObjectSize(currAddr);
}
}
}
currAddr = Allocator.SkipAlignment(currAddr);
return(currAddr);
}
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);
}
