[Bug middle-end/82853] Optimize x % 3 == 0 without modulo

[andi-gcc at firstfloor dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82853

--- Comment #5 from Andi Kleen <andi-gcc at firstfloor dot org> ---
Also I'm not sure why you would want it in the middle end. It should all work
at the tree level