[Bug tree-optimization/80426] [7 Regression] Wrong constant folding

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80426

--- Comment #5 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
Created attachment 41214
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41214&action=edit
Tentative fix

Same fix as PR tree-opt/79666, but for the invariant part.