[Bug tree-optimization/115825] [11/12/13/14 Regression] Loop unrolling increases code size with -Os

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115825

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |7.1.0
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2024-07-08
     Ever confirmed|0                           |1
   Target Milestone|---                         |11.5
             Target|avr                         |avr aarch64 x86_64
            Summary|Loop unrolling increases    |[11/12/13/14 Regression]
                   |code size with -Os          |Loop unrolling increases
                   |                            |code size with -Os
      Known to work|                            |6.3.0
                 CC|                            |pinskia at gcc dot gnu.org

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> For avr, we get:
> 
> size: 5-4, last_iteration: 5-4
>   Loop size: 5
>   Estimated size after unrolling: 5
> 
> So something is under-estimating the size after unrolling.

Maybe volatile stores should be increased with its size.

Note you get the same increase in size on aarch64 and x86_64 too.
started to happen between GCC 6 and GCC 7 even.

Confirmed.