[Bug middle-end/116013] Missed optimization opportunity with andn involving consts

[bisqwit at iki dot fi]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116013

--- Comment #1 from Joel Yliluoma <bisqwit at iki dot fi> ---
Should be noted that this is not x86_64 specific; andn exists for other
platforms too, and even for platforms that don’t have it, changing
`~(expr|const)` into `~expr & ~const`   is unlikely to be a pessimization.