[Bug rtl-optimization/85925] [7/8/9 regression] Mis-compilation at -02, masking with 257 goes wrong in combine

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85925

--- Comment #5 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
Created attachment 44982
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44982&action=edit
Tentative fix

I'm going to evaluate it on ARM and SPARC wrt pessimization.