[Bug target/80861] ARM (VFPv3): Inefficient float-to-char conversion goes through memory

[wilco at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80861

Wilco <wilco at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-05-23
                 CC|                            |wilco at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Wilco <wilco at gcc dot gnu.org> ---
(In reply to Gergö Barany from comment #0)
> Created attachment 41407 [details]
> Input C file for triggering the bug
> 
> Consider the attached code:
> 
> $ cat tst.c
> char fn1(float p1) {
>   return (char) p1;
> }

Confirmed. This is due to the extend patterns allowing memory, but they aren't
marked as having a higher cost, so it decides the spill given register move
cost is larger than memory move cost. A quick workaround would be to add ??m to
the various extend patterns.