[Bug rtl-optimization/58679] [4.9 regression] ICE in create_pre_exit, at mode-switching.c:421 with -mavx after r202915

[amylaar at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58679

--- Comment #10 from Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> ---
(In reply to Uroš Bizjak from comment #7)

> CC author. Hopefully, following part will be reverted:
> 
> 2013-10-25  Vladimir Makarov <vmakarov@redhat.com>
> 
>         [...]
>         * lra-spills.c (lra_final_code_change): Remove useless move insns.

For the return value sanity checks, we need only a subset of these moves
preserved.
Ones that are
- in the exit block, and
- likely_spilled_p, and
- pertain to the function result register, or a part of it.