[PATCH] Disable EHABI when -fno-exceptions option is chosen.

Renato Golin renato.golin at linaro.org
Fri Jan 31 08:31:47 PST 2014

On 31 January 2014 15:34, Evgeniy Stepanov <eugenis at google.com> wrote:

>   Why do we even need this flag, and not make the decision in the backend
> based on -munwind-tables?


This flag was introduced long ago when the EHABI was experimental (and not
working), so we actually had two flags controlling the emission of landing
pads and exception tables. Not to mess up too much, I've merged them into
the one that is today, but I agree we should merge it again with the other
options that control exception handling. Also, the EHABI is now in a state
of limbo, where it's enabled by default for monitoring and quality
improvements only, and therefore we need the specific disabling flag.

There is another refactoring that have shown up after enabling the EHABI by
default, is that it's not playing well with Dwarf stack unwinding via CFI
directives (Keith is working on that), so some work will be necessary in
that direction, too.

I'll have a look on the -munwind-tables option, but I'm guessing it has
more than just EH unwinding. Once EHABI becomes roughly production quality,
we'll have to re-visit all flags and make sure all tools' behaviours (not
just Clang) are consistent with other architectures.

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