1===================================== 2CodeView Type Records 3===================================== 4 5 6.. contents:: 7 :local: 8 9.. _types_intro: 10 11Introduction 12============ 13 14This document describes the usage and serialization format of the various 15CodeView type records that LLVM understands. This document does not describe 16every single CodeView type record that is defined. In some cases, this is 17because the records are clearly deprecated and can only appear in very old 18software (e.g. the 16-bit types). On other cases, it is because the records 19have never been observed in practice. This could be because they are only 20generated for non-C++ code (e.g. Visual Basic, C#), or because they have been 21made obsolete by newer records, or any number of other reasons. However, the 22records we describe here should cover 99% of type records that one can expect 23to encounter when dealing with modern C++ toolchains. 24 25Record Categories 26================= 27 28We can think of a sequence of CodeView type records as an array of variable length 29`leaf records`. Each such record describes its own length as part of a fixed-size 30header, as well as the kind of record it is. Leaf records are either padded to 4 31bytes (if this type stream appears in a TPI/IPI stream of a PDB) or not padded at 32all (if this type stream appears in the ``.debug$T`` section of an object file). 33Padding is implemented by inserting a decreasing sequence of `<_padding_records>` 34that terminates with ``LF_PAD0``. 35 36The final category of record is a ``member record``. One particular leaf type -- 37``LF_FIELDLIST`` -- contains a series of embedded records. While the outer 38``LF_FIELDLIST`` describes its length (like any other leaf record), the embedded 39records -- called ``member records`` do not. 40 41.. _leaf_types: 42 43Leaf Records 44------------ 45 46All leaf records begin with the following 4 byte prefix: 47 48.. code-block:: c++ 49 50 struct RecordHeader { 51 uint16_t RecordLen; // Record length, not including this 2 byte field. 52 uint16_t RecordKind; // Record kind enum. 53 }; 54 55LF_POINTER (0x1002) 56^^^^^^^^^^^^^^^^^^^ 57 58**Usage:** Describes a pointer to another type. 59 60**Layout:** 61 62.. code-block:: none 63 64 .--------------------.-- +0 65 | Referent Type | 66 .--------------------.-- +4 67 | Attributes | 68 .--------------------.-- +8 69 | Member Ptr Info | Only present if |Attributes| indicates this is a member pointer. 70 .--------------------.-- +E 71 72Attributes is a bitfield with the following layout: 73 74.. code-block:: none 75 76 .-----------------------------------------------------------------------------------------------------. 77 | Unused | Flags | Size | Modifiers | Mode | Kind | 78 .-----------------------------------------------------------------------------------------------------. 79 | | | | | | | 80 0x100 +0x16 +0x13 +0xD +0x8 +0x5 +0x0 81 82where the various fields are defined by the following enums: 83 84.. code-block:: c++ 85 86 enum class PointerKind : uint8_t { 87 Near16 = 0x00, // 16 bit pointer 88 Far16 = 0x01, // 16:16 far pointer 89 Huge16 = 0x02, // 16:16 huge pointer 90 BasedOnSegment = 0x03, // based on segment 91 BasedOnValue = 0x04, // based on value of base 92 BasedOnSegmentValue = 0x05, // based on segment value of base 93 BasedOnAddress = 0x06, // based on address of base 94 BasedOnSegmentAddress = 0x07, // based on segment address of base 95 BasedOnType = 0x08, // based on type 96 BasedOnSelf = 0x09, // based on self 97 Near32 = 0x0a, // 32 bit pointer 98 Far32 = 0x0b, // 16:32 pointer 99 Near64 = 0x0c // 64 bit pointer 100 }; 101 enum class PointerMode : uint8_t { 102 Pointer = 0x00, // "normal" pointer 103 LValueReference = 0x01, // "old" reference 104 PointerToDataMember = 0x02, // pointer to data member 105 PointerToMemberFunction = 0x03, // pointer to member function 106 RValueReference = 0x04 // r-value reference 107 }; 108 enum class PointerModifiers : uint8_t { 109 None = 0x00, // "normal" pointer 110 Flat32 = 0x01, // "flat" pointer 111 Volatile = 0x02, // pointer is marked volatile 112 Const = 0x04, // pointer is marked const 113 Unaligned = 0x08, // pointer is marked unaligned 114 Restrict = 0x10, // pointer is marked restrict 115 }; 116 enum class PointerFlags : uint8_t { 117 WinRTSmartPointer = 0x01, // pointer is a WinRT smart pointer 118 LValueRefThisPointer = 0x02, // pointer is a 'this' pointer of a member function with ref qualifier (e.g. void X::foo() &) 119 RValueRefThisPointer = 0x04 // pointer is a 'this' pointer of a member function with ref qualifier (e.g. void X::foo() &&) 120 }; 121 122The ``Size`` field of the Attributes bitmask is a 1-byte value indicating the 123pointer size. For example, a `void*` would have a size of either 4 or 8 depending 124on the target architecture. On the other hand, if ``Mode`` indicates that this is 125a pointer to member function or pointer to data member, then the size can be any 126implementation defined number. 127 128The ``Member Ptr Info`` field of the ``LF_POINTER`` record is only present if the 129attributes indicate that this is a pointer to member. 130 131Note that "plain" pointers to primitive types are not represented by ``LF_POINTER`` 132records, they are indicated by special reserved :ref:`TypeIndex values <type_indices>`. 133 134 135 136LF_MODIFIER (0x1001) 137^^^^^^^^^^^^^^^^^^^^ 138 139LF_PROCEDURE (0x1008) 140^^^^^^^^^^^^^^^^^^^^^ 141 142LF_MFUNCTION (0x1009) 143^^^^^^^^^^^^^^^^^^^^^ 144 145LF_LABEL (0x000e) 146^^^^^^^^^^^^^^^^^ 147 148LF_ARGLIST (0x1201) 149^^^^^^^^^^^^^^^^^^^ 150 151LF_FIELDLIST (0x1203) 152^^^^^^^^^^^^^^^^^^^^^ 153 154LF_ARRAY (0x1503) 155^^^^^^^^^^^^^^^^^ 156 157LF_CLASS (0x1504) 158^^^^^^^^^^^^^^^^^ 159 160LF_STRUCTURE (0x1505) 161^^^^^^^^^^^^^^^^^^^^^ 162 163LF_INTERFACE (0x1519) 164^^^^^^^^^^^^^^^^^^^^^ 165 166LF_UNION (0x1506) 167^^^^^^^^^^^^^^^^^ 168 169LF_ENUM (0x1507) 170^^^^^^^^^^^^^^^^ 171 172LF_TYPESERVER2 (0x1515) 173^^^^^^^^^^^^^^^^^^^^^^^ 174 175LF_VFTABLE (0x151d) 176^^^^^^^^^^^^^^^^^^^ 177 178LF_VTSHAPE (0x000a) 179^^^^^^^^^^^^^^^^^^^ 180 181LF_BITFIELD (0x1205) 182^^^^^^^^^^^^^^^^^^^^ 183 184LF_FUNC_ID (0x1601) 185^^^^^^^^^^^^^^^^^^^ 186 187LF_MFUNC_ID (0x1602) 188^^^^^^^^^^^^^^^^^^^^ 189 190LF_BUILDINFO (0x1603) 191^^^^^^^^^^^^^^^^^^^^^ 192 193LF_SUBSTR_LIST (0x1604) 194^^^^^^^^^^^^^^^^^^^^^^^ 195 196LF_STRING_ID (0x1605) 197^^^^^^^^^^^^^^^^^^^^^ 198 199LF_UDT_SRC_LINE (0x1606) 200^^^^^^^^^^^^^^^^^^^^^^^^ 201 202LF_UDT_MOD_SRC_LINE (0x1607) 203^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 204 205LF_METHODLIST (0x1206) 206^^^^^^^^^^^^^^^^^^^^^^ 207 208LF_PRECOMP (0x1509) 209^^^^^^^^^^^^^^^^^^^ 210 211LF_ENDPRECOMP (0x0014) 212^^^^^^^^^^^^^^^^^^^^^^ 213 214.. _member_types: 215 216Member Records 217-------------- 218 219LF_BCLASS (0x1400) 220^^^^^^^^^^^^^^^^^^ 221 222LF_BINTERFACE (0x151a) 223^^^^^^^^^^^^^^^^^^^^^^ 224 225LF_VBCLASS (0x1401) 226^^^^^^^^^^^^^^^^^^^ 227 228LF_IVBCLASS (0x1402) 229^^^^^^^^^^^^^^^^^^^^ 230 231LF_VFUNCTAB (0x1409) 232^^^^^^^^^^^^^^^^^^^^ 233 234LF_STMEMBER (0x150e) 235^^^^^^^^^^^^^^^^^^^^ 236 237LF_METHOD (0x150f) 238^^^^^^^^^^^^^^^^^^ 239 240LF_MEMBER (0x150d) 241^^^^^^^^^^^^^^^^^^ 242 243LF_NESTTYPE (0x1510) 244^^^^^^^^^^^^^^^^^^^^ 245 246LF_ONEMETHOD (0x1511) 247^^^^^^^^^^^^^^^^^^^^^ 248 249LF_ENUMERATE (0x1502) 250^^^^^^^^^^^^^^^^^^^^^ 251 252LF_INDEX (0x1404) 253^^^^^^^^^^^^^^^^^ 254 255.. _padding_records: 256 257Padding Records 258--------------- 259 260LF_PADn (0xf0 + n) 261^^^^^^^^^^^^^^^^^^ 262