Unwind Info
===========

Tells the runtime how to unwind the stack for exception handling and debugging
purposes. There are two formats in which the unwind info can be encoded: the
DWARF format and the newer "compact unwind" format.

The compact unwind format, as its name suggests, is more compact. However, it is
limited in what it can encode; the DWARF format is more general. As such, the
DWARF format continues to be used as a fallback.

The compact unwind takes different forms in object files vs binaries. In object
files, it can be found under the ``__compact_unwind`` section; the linker is
responsible for transforming the data there into the output form, which will be
written to the ``__unwind_info`` section.

The DWARF info is stored in the ``__eh_frame`` section (in both object files and
binaries). The ``__unwind_info`` section in output binaries will contain pointers
into the ``__eh_frame`` section.

Unwind info can be inspected via ``llvm-objdump --macho --unwind-info
--dwarf=frames``.

TODO: talk about personality functions and LSDAs