private static UIntPtr PostPinnedObjectAddr(UIntPtr endPage) { UIntPtr endAddr = PageTable.PageAddr(endPage); UIntPtr postLastObjectAddr = InteriorPtrTable.Last(endPage - 1); if (postLastObjectAddr < endAddr && !BumpAllocator.IsUnusedSpace(postLastObjectAddr)) { // If the next object straddles into the next page, // return the location just past the object Object lastObject = Magic.fromAddress(postLastObjectAddr); UIntPtr lastObjectSize = ObjectLayout.ObjectSize(postLastObjectAddr, lastObject.vtable); postLastObjectAddr += lastObjectSize; } return(postLastObjectAddr - PreHeader.Size); }
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); }