======================= libunwind LLVM Unwinder

Overview

libunwind is an implementation of the interface defined by the HP libunwind project. It was contributed by Apple as a way to enable clang++ to port to platforms that do not have a system unwinder. It is intended to be a small and fast implementation of the ABI, leaving off some features of HP's libunwind that never materialized (e.g. remote unwinding).

The unwinder has two levels of API. The high level APIs are the _Unwind_* functions which implement functionality required by __cxa_* exception functions. The low level APIs are the unw_* functions which are an interface defined by the old HP libunwind project.

Getting Started with libunwind

.. toctree:: :maxdepth: 2

BuildingLibunwind

Current Status

libunwind is a production-quality unwinder, with platform support for DWARF unwind info, SjLj, and ARM EHABI.

The low level libunwind API was designed to work either in-process (aka local) or to operate on another process (aka remote), but only the local path has been implemented. Remote unwinding remains as future work.

Platform and Compiler Support

libunwind is known to work on the following platforms:

============ ======================== ============ ======================== OS Arch Compilers Unwind Info ============ ======================== ============ ======================== Any i386, x86_64, ARM Clang SjLj Bare Metal ARM Clang, GCC EHABI FreeBSD i386, x86_64, ARM64 Clang DWARF CFI iOS ARM Clang SjLj Linux ARM Clang, GCC EHABI Linux i386, x86_64, ARM64 Clang, GCC DWARF CFI macOS i386, x86_64 Clang, GCC DWARF CFI NetBSD x86_64 Clang, GCC DWARF CFI Windows i386, x86_64, ARM, ARM64 Clang DWARF CFI ============ ======================== ============ ========================

The following minimum compiler versions are strongly recommended.

Clang 3.5 and above
GCC 4.7 and above.

Anything older may work.

Notes and Known Issues

TODO

Getting Involved

First please review our Developer's Policy and Getting started with LLVM.

Bug Reports

If you think you've found a bug in libunwind, please report it using the LLVM bug tracker. If you're not sure, you can ask for support on the Runtimes forum or on IRC. Please use the tag "libunwind" for new threads.

Patches

If you want to contribute a patch to libunwind, please start by reading the LLVM documentation about contributing.

Discussion and Questions

Send discussions and questions to the Runtimes forum_. Please add the tag "libunwind" to your post.