[Bug other/50925] [4.7 Regression][avr] ICE at spill_failure, at reload1.c:2118

["denisc at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50925

denisc at gcc dot gnu.org changed:

           What    |Removed                     |Added
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                 CC|                            |denisc at gcc dot gnu.org

--- Comment #9 from denisc at gcc dot gnu.org 2011-12-05 18:31:53 UTC ---
(In reply to comment #8)
> I'm not going to be able to look at it anytime soon, but just some general
> thoughts:

I think that I'm ready to explain the bug.

>   1. Disabling caller-saves probably isn't appropriate.  Just looking at
> codesize isn't the way to evaluate caller-saves either as caller-saves is
> tasked with improving performance, possibly at the expense of codesize.

I'm agree. I don't want to disable caller-saves.

> 
>   2. The first thing someone needs to do is provide information as to why that
> insn needs reloads.  I don't know enough about the AVR to hazard as guess why
> that insn needs reloads.
> 
>   3. Find out where insn 172 comes from.  There are restrictions on the insns
> created by caller-save.  So if caller-save creates a bogus insn, then that
> needs to be investigated.

Generally, caller-save generate right insn.

1. AVR port have a specific dependency between frame_pointer_neede and 
gat_frame_size()