diff options
| -rw-r--r-- | llvm/docs/PDB/CodeViewSymbols.rst | 39 |
1 files changed, 38 insertions, 1 deletions
diff --git a/llvm/docs/PDB/CodeViewSymbols.rst b/llvm/docs/PDB/CodeViewSymbols.rst index 96b2471c111..b056b804e5a 100644 --- a/llvm/docs/PDB/CodeViewSymbols.rst +++ b/llvm/docs/PDB/CodeViewSymbols.rst @@ -52,14 +52,52 @@ to appear in a PDB file. Public Symbols (which appear only in the Public Symbols -------------- +Public symbols are the CodeView equivalent of DWARF ``.debug_pubnames``. There +is one public symbol record for every function or variable in the program that +has a mangled name. The :doc:`Publics Stream <PublicStream>`, which contains these +records, additionally contains a hash table that allows one to quickly locate a +record by mangled name. + S_PUB32 (0x110e) ^^^^^^^^^^^^^^^^ +There is only type of public symbol, an ``S_PUB32`` which describes a mangled +name, a flag indicating what kind of symbol it is (e.g. function, variable), and +the symbol's address. The :ref:`dbi_section_map_substream` of the +:doc:`DBI Stream <DbiStream>` can be consulted to determine what module this address +corresponds to, and from there that module's :doc:`module debug stream <ModiStream>` +can be consulted to locate full information for the symbol with the given address. + .. _global_symbols: Global Symbols -------------- +While there is one :ref:`public symbol <public_symbols>` for every symbol in the +program with `external` linkage, there is one global symbol for every symbol in the +program with linkage (including internal linkage). As a result, global symbols do +not describe a mangled name *or* an address, since symbols with internal linkage +need not have any mangling at all, and also may not have an address. Thus, all +global symbols simply refer directly to the full symbol record via a module/offset +combination. + +Similarly to :ref:`public symbols <public_symbols>`, all global symbols are contained +in a single :doc:`Globals Stream <GlobalStream>`, which contains a hash table mapping +fully qualified name to the corresponding record in the globals stream (which as +mentioned, then contains information allowing one to locate the full record in the +corresponding module symbol stream). + +Note that a consequence and limitation of this design is that program-wide lookup +by anything other than an exact textually matching fully-qualified name of whatever +the compiler decided to emit is impractical. This differs from DWARF, where even +though we don't necessarily have O(1) lookup by basename within a given scope (including +O(1) scope, we at least have O(n) access within a given scope). + +.. important::
+ Program-wide lookup of names by anything other than an exact textually matching fully
+ qualified name is not possible.
+ + S_GDATA32 ^^^^^^^^^^ @@ -72,7 +110,6 @@ S_PROCREF (0x1125) S_LPROCREF (0x1127) ^^^^^^^^^^^^^^^^^^^ - S_GMANDATA (0x111d) ^^^^^^^^^^^^^^^^^^^ |
