[Bug tree-optimization/127042] [17 Regression] widening mul synthesis generates arithmetic for a result known at compile time

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127042

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Target Milestone|---                         |17.0
   Last reconfirmed|                            |2026-08-24
             Target|avr                         |avr arm (thumb1)
            Summary|[avr] widening mul          |[17 Regression] widening
                   |synthesis generates         |mul synthesis generates
                   |arithmetic for a result     |arithmetic for a result
                   |known at compile time       |known at compile time
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.  arm thumb1 does not have a multiply widdening or multiply high
instruction so it shows the issue too.

`-O2 -mfloat-abi=soft -march=armv6 -mthumb`


  _7 = (unsigned int) x_4(D);
  _8 = _7 >> 16;