[Bug rtl-optimization/117532] [15 Regression] Miscompile with -Os and -O0/1/2/3

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117532

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Miscompile with -Os and     |[15 Regression] Miscompile
                   |-O0/1/2/3                   |with -Os and -O0/1/2/3
     Ever confirmed|0                           |1
           Priority|P3                          |P1
          Component|c                           |rtl-optimization
   Target Milestone|---                         |15.0
   Last reconfirmed|                            |2024-11-11
      Known to work|                            |14.2.0
             Target|                            |x86_64-*-*
           Keywords|                            |needs-bisection, wrong-code
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  GIMPLE IL is the samme, possibly a target issue though.

        xorb    $-1, %sil

while this properly inverts the 'char' it fails to invert the higher bits
(or properly zero extends it).