[Bug tree-optimization/96897] Failure to optimize not+not+dec+and+not to add+or

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96897

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
We already transform to
return ~(-2 - x) | x;

so this is really asking for
~(-2 - x) --> x + 1