| 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152 |
- Itanium Name Demangler Library
- ==============================
- Introduction
- ------------
- This directory contains the generic itanium name demangler library. The main
- purpose of the library is to demangle C++ symbols, i.e. convert the string
- "_Z1fv" into "f()". You can also use the CRTP base ManglingParser to perform
- some simple analysis on the mangled name, or (in LLVM) use the opaque
- ItaniumPartialDemangler to query the demangled AST.
- Why are there multiple copies of the this library in the source tree?
- ---------------------------------------------------------------------
- This directory is mirrored between libcxxabi/demangle and
- llvm/include/llvm/Demangle. The simple reason for this is that both projects
- need to demangle symbols, but neither can depend on each other. libcxxabi needs
- the demangler to implement __cxa_demangle, which is part of the itanium ABI
- spec. LLVM needs a copy for a bunch of places, but doesn't want to use the
- system's __cxa_demangle because it a) might not be available (i.e., on Windows),
- and b) probably isn't that up-to-date on the latest language features.
- The copy of the demangler in LLVM has some extra stuff that aren't needed in
- libcxxabi (ie, the MSVC demangler, ItaniumPartialDemangler), which depend on the
- shared generic components. Despite these differences, we want to keep the "core"
- generic demangling library identical between both copies to simplify development
- and testing.
- If you're working on the generic library, then do the work first in libcxxabi,
- then run the cp-to-llvm.sh script in src/demangle. This script takes as an
- argument the path to llvm, and re-copies the changes you made to libcxxabi over.
- Note that this script just blindly overwrites all changes to the generic library
- in llvm, so be careful.
- Because the core demangler needs to work in libcxxabi, everything needs to be
- declared in an anonymous namespace (see DEMANGLE_NAMESPACE_BEGIN), and you can't
- introduce any code that depends on the libcxx dylib.
- Hopefully, when LLVM becomes a monorepo, we can de-duplicate this code, and have
- both LLVM and libcxxabi depend on a shared demangler library.
- Testing
- -------
- The tests are split up between libcxxabi/test/{unit,}test_demangle.cpp, and
- llvm/unittest/Demangle. The llvm directory should only get tests for stuff not
- included in the core library. In the future though, we should probably move all
- the tests to LLVM.
- It is also a really good idea to run libFuzzer after non-trivial changes, see
- libcxxabi/fuzz/cxa_demangle_fuzzer.cpp and https://llvm.org/docs/LibFuzzer.html.
|
