From e28ea96f43b77b868a086d52dc8c364e61fb16a4 Mon Sep 17 00:00:00 2001 From: Zachary Turner Date: Fri, 5 Apr 2019 16:43:42 +0000 Subject: [PATCH] Add documentation for PDB TPI/IPI Stream. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@357777 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/PDB/TpiStream.rst | 303 ++++++++++++++++++++++++++++++++++++++++- docs/PDB/index.rst | 13 +- 2 files changed, 311 insertions(+), 5 deletions(-) diff --git a/docs/PDB/TpiStream.rst b/docs/PDB/TpiStream.rst index 1e3297ebdc7..74f2c37b083 100644 --- a/docs/PDB/TpiStream.rst +++ b/docs/PDB/TpiStream.rst @@ -1,3 +1,304 @@ ===================================== -The PDB TPI Stream +The PDB TPI and IPI Streams ===================================== + +.. contents:: + :local: + +.. _tpi_intro: + +Introduction +============ + +The PDB TPI Stream (Index 2) and IPI Stream (Index 3) contain information about +all types used in the program. It is organized as a :ref:`header ` +followed by a list of :doc:`CodeView Type Records `. Types are +referenced from various streams and records throughout the PDB by their +:ref:`type index `. In general, the sequence of type records +following the :ref:`header ` forms a topologically sorted DAG +(directed acyclic graph), which means that a type record B can only refer to +the type A if ``A.TypeIndex < B.TypeIndex``. While there are rare cases where +this property will not hold (particularly when dealing with object files +compiled with MASM), an implementation should try very hard to make this +property hold, as it means the entire type graph can be constructed in a single +pass. + +.. important:: + Type records form a topologically sorted DAG (directed acyclic graph). + +.. _tpi_ipi: + +TPI vs IPI Stream +================= + +Recent versions of the PDB format (aka all versions covered by this document) +have 2 streams with identical layout, henceforth referred to as the TPI stream +and IPI stream. Subsequent contents of this document describing the on-disk +format apply equally whether it is for the TPI Stream or the IPI Stream. The +only difference between the two is in *which* CodeView records are allowed to +appear in each one, summarized by the following table: + ++----------------------+---------------------+ +| TPI Stream | IPI Stream | ++======================+=====================+ +| LF_POINTER | LF_FUNC_ID | ++----------------------+---------------------+ +| LF_MODIFIER | LF_MFUNC_ID | ++----------------------+---------------------+ +| LF_PROCEDURE | LF_BUILDINFO | ++----------------------+---------------------+ +| LF_MFUNCTION | LF_SUBSTR_LIST | ++----------------------+---------------------+ +| LF_LABEL | LF_STRING_ID | ++----------------------+---------------------+ +| LF_ARGLIST | LF_UDT_SRC_LINE | ++----------------------+---------------------+ +| LF_FIELDLIST | LF_UDT_MOD_SRC_LINE | ++----------------------+---------------------+ +| LF_ARRAY | | ++----------------------+---------------------+ +| LF_CLASS | | ++----------------------+---------------------+ +| LF_STRUCTURE | | ++----------------------+---------------------+ +| LF_INTERFACE | | ++----------------------+---------------------+ +| LF_UNION | | ++----------------------+---------------------+ +| LF_ENUM | | ++----------------------+---------------------+ +| LF_TYPESERVER2 | | ++----------------------+---------------------+ +| LF_VFTABLE | | ++----------------------+---------------------+ +| LF_VTSHAPE | | ++----------------------+---------------------+ +| LF_BITFIELD | | ++----------------------+---------------------+ +| LF_METHODLIST | | ++----------------------+---------------------+ +| LF_PRECOMP | | ++----------------------+---------------------+ +| LF_ENDPRECOMP | | ++----------------------+---------------------+ + +The usage of these records is described in more detail in +:doc:`CodeView Type Records `. + +.. _type_indices: + +Type Indices +============ + +A type index is a 32-bit integer that uniquely identifies a type inside of an +object file's ``.debug$T`` section or a PDB file's TPI or IPI stream. The +value of the type index for the first type record from the TPI stream is given +by the ``TypeIndexBegin`` member of the :ref:`TPI Stream Header ` +although in practice this value is always equal to 0x1000 (4096). + +Any type index with a high bit set is considered to come from the IPI stream, +although this appears to be more of a hack, and LLVM does not generate type +indices of this nature. They can, however, be observed in Microsoft PDBs +occasionally, so one should be prepared to handle them. Note that having the +high bit set is not a necessary condition to determine whether a type index +comes from the IPI stream, it is only sufficient. + +Once the high bit is cleared, any type index >= ``TypeIndexBegin`` is presumed +to come from the appropriate stream, and any type index less than this is a +bitmask which can be decomposed as follows: + +.. code-block:: none + + .---------------------------.------.----------. + | Unused | Mode | Kind | + '---------------------------'------'----------' + |+32 |+12 |+8 |+0 + + +- **Kind** - A value from the following enum: + +.. code-block:: c++ + + enum class SimpleTypeKind : uint32_t { + None = 0x0000, // uncharacterized type (no type) + Void = 0x0003, // void + NotTranslated = 0x0007, // type not translated by cvpack + HResult = 0x0008, // OLE/COM HRESULT + + SignedCharacter = 0x0010, // 8 bit signed + UnsignedCharacter = 0x0020, // 8 bit unsigned + NarrowCharacter = 0x0070, // really a char + WideCharacter = 0x0071, // wide char + Character16 = 0x007a, // char16_t + Character32 = 0x007b, // char32_t + + SByte = 0x0068, // 8 bit signed int + Byte = 0x0069, // 8 bit unsigned int + Int16Short = 0x0011, // 16 bit signed + UInt16Short = 0x0021, // 16 bit unsigned + Int16 = 0x0072, // 16 bit signed int + UInt16 = 0x0073, // 16 bit unsigned int + Int32Long = 0x0012, // 32 bit signed + UInt32Long = 0x0022, // 32 bit unsigned + Int32 = 0x0074, // 32 bit signed int + UInt32 = 0x0075, // 32 bit unsigned int + Int64Quad = 0x0013, // 64 bit signed + UInt64Quad = 0x0023, // 64 bit unsigned + Int64 = 0x0076, // 64 bit signed int + UInt64 = 0x0077, // 64 bit unsigned int + Int128Oct = 0x0014, // 128 bit signed int + UInt128Oct = 0x0024, // 128 bit unsigned int + Int128 = 0x0078, // 128 bit signed int + UInt128 = 0x0079, // 128 bit unsigned int + + Float16 = 0x0046, // 16 bit real + Float32 = 0x0040, // 32 bit real + Float32PartialPrecision = 0x0045, // 32 bit PP real + Float48 = 0x0044, // 48 bit real + Float64 = 0x0041, // 64 bit real + Float80 = 0x0042, // 80 bit real + Float128 = 0x0043, // 128 bit real + + Complex16 = 0x0056, // 16 bit complex + Complex32 = 0x0050, // 32 bit complex + Complex32PartialPrecision = 0x0055, // 32 bit PP complex + Complex48 = 0x0054, // 48 bit complex + Complex64 = 0x0051, // 64 bit complex + Complex80 = 0x0052, // 80 bit complex + Complex128 = 0x0053, // 128 bit complex + + Boolean8 = 0x0030, // 8 bit boolean + Boolean16 = 0x0031, // 16 bit boolean + Boolean32 = 0x0032, // 32 bit boolean + Boolean64 = 0x0033, // 64 bit boolean + Boolean128 = 0x0034, // 128 bit boolean + }; + +- **Mode** - A value from the following enum: + +.. code-block:: c++ + + enum class SimpleTypeMode : uint32_t { + Direct = 0, // Not a pointer + NearPointer = 1, // Near pointer + FarPointer = 2, // Far pointer + HugePointer = 3, // Huge pointer + NearPointer32 = 4, // 32 bit near pointer + FarPointer32 = 5, // 32 bit far pointer + NearPointer64 = 6, // 64 bit near pointer + NearPointer128 = 7 // 128 bit near pointer + }; + +Note that for pointers, the bitness is represented in the mode. So a ``void*`` +would have a type index with ``Mode=NearPointer32, Kind=Void`` if built for 32-bits +but a type index with ``Mode=NearPointer64, Kind=Void`` if built for 64-bits. + +By convention, the type index for ``std::nullptr_t`` is constructed the same way +as the type index for ``void*``, but using the bitless enumeration value +``NearPointer``. + + + +.. _tpi_header: + +Stream Header +============= +At offset 0 of the TPI Stream is a header with the following layout: + + +.. code-block:: c++ + + struct TpiStreamHeader { + uint32_t Version; + uint32_t HeaderSize; + uint32_t TypeIndexBegin; + uint32_t TypeIndexEnd; + uint32_t TypeRecordBytes; + + uint16_t HashStreamIndex; + uint16_t HashAuxStreamIndex; + uint32_t HashKeySize; + uint32_t NumHashBuckets; + + int32_t HashValueBufferOffset; + uint32_t HashValueBufferLength; + + int32_t IndexOffsetBufferOffset; + uint32_t IndexOffsetBufferLength; + + int32_t HashAdjBufferOffset; + uint32_t HashAdjBufferLength; + }; + +- **Version** - A value from the following enum. + +.. code-block:: c++ + + enum class TpiStreamVersion : uint32_t { + V40 = 19950410, + V41 = 19951122, + V50 = 19961031, + V70 = 19990903, + V80 = 20040203, + }; + +Similar to the :doc:`PDB Stream `, this value always appears to be +``V80``, and no other values have been observed. It is assumed that should +another value be observed, the layout described by this document may not be +accurate. + +- **HeaderSize** - ``sizeof(TpiStreamHeader)`` + +- **TypeIndexBegin** - The numeric value of the type index representing the + first type record in the TPI stream. This is usually the value 0x1000 as type + indices lower than this are reserved (see :ref:`Type Indices ` for + a discussion of reserved type indices). + +- **TypeIndexEnd** - One greater than the numeric value of the type index + representing the last type record in the TPI stream. The total number of type + records in the TPI stream can be computed as ``TypeIndexEnd - TypeIndexBegin``. + +- **TypeRecordBytes** - The number of bytes of type record data following the header. + +- **HashStreamIndex** - The index of a stream which contains a list of hashes for + every type record. This value may be -1, indicating that hash information is not + present. In practice a valid stream index is always observed, so any producer + implementation should be prepared to emit this stream to ensure compatibility with + tools which may expect it to be present. + +- **HashAuxStreamIndex** - Presumably the index of a stream which contains a separate + hash table, although this has not been observed in practice and it's unclear what it + might be used for. + +- **HashKeySize** - The size of a hash value (usually 4 bytes). + +- **NumHashBuckets** - The number of buckets used to generate the hash values in the + aforementioned hash streams. + +- **HashValueBufferOffset / HashValueBufferLength** - The offset and size within + the TPI Hash Stream of the list of hash values. It should be assumed that there + are either 0 hash values, or a number equal to the number of type records in the + TPI stream (``TypeIndexEnd - TypeEndBegin``). Thus, if ``HashBufferLength`` is + not equal to ``(TypeIndexEnd - TypeEndBegin) * HashKeySize`` we can consider the + PDB malformed. + +- **IndexOffsetBufferOffset / IndexOffsetBufferLength** - The offset and size + within the TPI Hash Stream of the Type Index Offsets Buffer. This is a list of + pairs of uint32_t's where the first value is a :ref:`Type Index ` + and the second value is the offset in the type record data of the type with this + index. This can be used to do a binary search followed bin a linear search to + get amortized O(log n) lookup by type index. + +- **HashAdjBufferOffset / HashAdjBufferLength** - + +.. _tpi_records: + +CodeView Type Record List +========================= +Following the header, there are ``TypeRecordBytes`` bytes of data that represent a +variable length array of :doc:`CodeView type records `. The number +of such records (e.g. the length of the array) can be determined by computing the +value ``Header.TypeIndexEnd - Header.TypeIndexBegin``. + +log(n) random access is provided by way of the Type Index Offsets array (if present) +described previously. \ No newline at end of file diff --git a/docs/PDB/index.rst b/docs/PDB/index.rst index 5300588b1d8..d1b4379dbf8 100644 --- a/docs/PDB/index.rst +++ b/docs/PDB/index.rst @@ -100,7 +100,8 @@ PDB file is as follows: | | | - Indices of public / global streams | | | | - Section Contribution Information | | | | - Source File Information | -| | | - FPO / PGO Data | +| | | - References to streams containing | +| | | FPO / PGO Data | +--------------------+------------------------------+-------------------------------------------+ | IPI Stream | - Fixed Stream Index 4 | - CodeView Type Records | | | | - Index of IPI Hash Stream | @@ -108,8 +109,8 @@ PDB file is as follows: | /LinkInfo | - Contained in PDB Stream | - Unknown | | | Named Stream map | | +--------------------+------------------------------+-------------------------------------------+ -| /src/headerblock | - Contained in PDB Stream | - Unknown | -| | Named Stream map | | +| /src/headerblock | - Contained in PDB Stream | - Summary of embedded source file content | +| | Named Stream map | (e.g. natvis files) | +--------------------+------------------------------+-------------------------------------------+ | /names | - Contained in PDB Stream | - PDB-wide global string table used for | | | Named Stream map | string de-duplication | @@ -120,7 +121,7 @@ PDB file is as follows: | Public Stream | - Contained in DBI Stream | - Public (Exported) Symbol Records | | | | - Index of Public Hash Stream | +--------------------+------------------------------+-------------------------------------------+ -| Global Stream | - Contained in DBI Stream | - Global Symbol Records | +| Global Stream | - Contained in DBI Stream | - Single combined master symbol-table | | | | - Index of Global Hash Stream | +--------------------+------------------------------+-------------------------------------------+ | TPI Hash Stream | - Contained in TPI Stream | - Hash table for looking up TPI records | @@ -129,6 +130,10 @@ PDB file is as follows: | IPI Hash Stream | - Contained in IPI Stream | - Hash table for looking up IPI records | | | | by name | +--------------------+------------------------------+-------------------------------------------+ +| * LINKER* Stream | - Last Stream in PDB File | - Executable section information | +| | | - Incremental linking thunks | +| | | - Linker version information | ++--------------------+------------------------------+-------------------------------------------+ More information about the structure of each of these can be found on the following pages: -- 2.50.1