[Bug target/85961] scratch register rsi used after function call

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85961

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jsm28 at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Alexander Monakov from comment #3)
> You'd need to disable IPA-RA after forcing -O2 with the pragma, i.e.:
> 
> #pragma GCC optimize "O2"
> #pragma GCC optimize "no-ipa-ra"
> 
> We already have logic to disable IPA-RA when instrumentation/profiling is
> active, but it's done once in toplev.c. Here the pragma re-enables IPA-RA
> after toplev.c:process_options() has disabled it.
> 
> Do we want to adjust it given that "pragma optimized" is documented as "not
> suitable for production use"?

Hmm, given that -pg -O2 on the command-line doesn't get you IPA-RA
enabled I would argue that the #pragma optimize behavior is bogus ...

The issue here is that all "special" processing in toplev.c is lost.
I'm not sure why we do all this in process_options () rather than
in finish_options () because that is called again after applying optimize
options AFAICS.

So - all process_options () option post-processing should go away and be moved
to finish_options ()?

Note that process_options () is only called from do_compile and we do
the postprocessing after lang_hooks.post_options which is applied only
after finish_options () post-processing...