llvm-project/llvm/docs/CommandGuide/llvm-cxxmap.rst

llvm-cxxmap - Mangled name remapping tool
=========================================

.. program:: llvm-cxxmap

SYNOPSIS
--------

:program:`llvm-cxxmap` [*options*] *symbol-file-1* *symbol-file-2*

DESCRIPTION
-----------

The :program:`llvm-cxxmap` tool performs fuzzy matching of C++ mangled names,
based on a file describing name components that should be considered equivalent.

The symbol files should contain a list of C++ mangled names (one per line).
Blank lines and lines starting with ``#`` are ignored. The output is a list
of pairs of equivalent symbols, one per line, of the form

.. code-block:: none

  <symbol-1> <symbol-2>

where ``<symbol-1>`` is a symbol from *symbol-file-1* and ``<symbol-2>`` is
a symbol from *symbol-file-2*. Mappings for which the two symbols are identical
are omitted.

OPTIONS
-------

.. program:: llvm-cxxmap

.. option:: -remapping-file=file, -r=file

 Specify a file containing a list of equivalence rules that should be used
 to determine whether two symbols are equivalent. Required.
 See :ref:`remapping-file`.

.. option:: -output=file, -o=file

 Specify a file to write the list of matched names to. If unspecified, the
 list will be written to stdout.

.. option:: -Wambiguous

 Produce a warning if there are multiple equivalent (but distinct) symbols in
 *symbol-file-2*.

.. option:: -Wincomplete

 Produce a warning if *symbol-file-1* contains a symbol for which there is no
 equivalent symbol in *symbol-file-2*.

.. _remapping-file:

REMAPPING FILE
--------------

The remapping file is a text file containing lines of the form

.. code-block:: none

  fragmentkind fragment1 fragment2

where ``fragmentkind`` is one of ``name``, ``type``, or ``encoding``,
indicating whether the following mangled name fragments are
<`name <http://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangle.name>`_>s,
<`type <http://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangle.type>`_>s, or
<`encoding <http://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangle.encoding>`_>s,
respectively.
Blank lines and lines starting with ``#`` are ignored.

Unmangled C names can be expressed as an ``encoding`` that is a (length-prefixed)
<`source-name <http://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangle.source-name>`_>:

.. code-block:: none

  # C function "void foo_bar()" is remapped to C++ function "void foo::bar()".
  encoding 7foo_bar _Z3foo3barv

For convenience, built-in <substitution>s such as ``St`` and ``Ss``
are accepted as <name>s (even though they technically are not <name>s).

For example, to specify that ``absl::string_view`` and ``std::string_view``
should be treated as equivalent, the following remapping file could be used:

.. code-block:: none

  # absl::string_view is considered equivalent to std::string_view
  type N4absl11string_viewE St17basic_string_viewIcSt11char_traitsIcEE

  # std:: might be std::__1:: in libc++ or std::__cxx11:: in libstdc++
  name St St3__1
  name St St7__cxx11

.. note::

  Symbol remapping is currently only supported for C++ mangled names
  following the Itanium C++ ABI mangling scheme. This covers all C++ targets
  supported by Clang other than Windows targets.