diff options
| -rw-r--r-- | src/pugixml.cpp | 41 |
1 files changed, 23 insertions, 18 deletions
diff --git a/src/pugixml.cpp b/src/pugixml.cpp index 1d0f5e8..10208e7 100644 --- a/src/pugixml.cpp +++ b/src/pugixml.cpp @@ -760,7 +760,12 @@ PUGI__NS_BEGIN { if (value) { - ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(compact_alignment - 1)) >> compact_alignment_log2) - start; + // value is guaranteed to be compact-aligned; this is not + // our decoding is based on this aligned to compact alignment downwards (see operator T*) + // so for negative offsets (e.g. -3) we need to adjust the diff by compact_alignment - 1 to + // compensate for arithmetic shift behavior for negative values + ptrdiff_t diff = reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this); + ptrdiff_t offset = ((diff + int(compact_alignment - 1)) >> compact_alignment_log2) - start; if (static_cast<uintptr_t>(offset) <= 253) _data = static_cast<unsigned char>(offset + 1); @@ -783,7 +788,7 @@ PUGI__NS_BEGIN { uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(compact_alignment - 1); - return reinterpret_cast<T*>(base + ((_data - (1 - start)) << compact_alignment_log2)); + return reinterpret_cast<T*>(base + ((_data - 1 + start) << compact_alignment_log2)); } else return compact_get_value<header_offset, T>(this); @@ -804,7 +809,7 @@ PUGI__NS_BEGIN template <typename T, int header_offset> class compact_pointer_parent { public: - compact_pointer_parent(): _data0(0), _data1(0) + compact_pointer_parent(): _data(0) { } @@ -817,12 +822,16 @@ PUGI__NS_BEGIN { if (value) { - ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(compact_alignment - 1)) >> compact_alignment_log2) + 65533; + // value is guaranteed to be compact-aligned; this is not + // our decoding is based on this aligned to compact alignment downwards (see operator T*) + // so for negative offsets (e.g. -3) we need to adjust the diff by compact_alignment - 1 to + // compensate for arithmetic shift behavior for negative values + ptrdiff_t diff = reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this); + ptrdiff_t offset = ((diff + int(compact_alignment - 1)) >> compact_alignment_log2) + 65533; if (static_cast<uintptr_t>(offset) <= 65533) { - _data0 = static_cast<unsigned char>(offset + 1); - _data1 = static_cast<unsigned char>((offset + 1) >> 8); + _data = static_cast<unsigned short>(offset + 1); } else { @@ -833,28 +842,25 @@ PUGI__NS_BEGIN if (page->compact_shared_parent == value) { - _data0 = 254; - _data1 = 255; + _data = 65534; } else { compact_set_value<header_offset>(this, value); - _data0 = 255; - _data1 = 255; + _data = 65535; } } } else { - _data0 = 0; - _data1 = 0; + _data = 0; } } operator T*() const { - int data = _data0 + (_data1 << 8); + int data = _data; if (data) { @@ -862,7 +868,7 @@ PUGI__NS_BEGIN { uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(compact_alignment - 1); - return reinterpret_cast<T*>(base + ((data - (1 + 65533)) << compact_alignment_log2)); + return reinterpret_cast<T*>(base + ((data - 1 - 65533) << compact_alignment_log2)); } else if (data == 65534) return static_cast<T*>(compact_get_page(this, header_offset)->compact_shared_parent); @@ -879,8 +885,7 @@ PUGI__NS_BEGIN } private: - unsigned char _data0; - unsigned char _data1; + uint16_t _data; }; template <int header_offset> class compact_string @@ -901,12 +906,12 @@ PUGI__NS_BEGIN { xml_memory_page* page = compact_get_page(this, header_offset); - if (page->compact_string_base == 0) + if (PUGI__UNLIKELY(page->compact_string_base == 0)) page->compact_string_base = value; ptrdiff_t offset = value - page->compact_string_base; - if (static_cast<uintptr_t>(offset) >= 16777213) + if (PUGI__UNLIKELY(static_cast<uintptr_t>(offset) >= 16777213)) { compact_set_value<header_offset>(this, value); |