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

[rearnsha at gcc dot gnu.org]

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

--- Comment #27 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #26)

> A test generator for x % c1 == c2 expansion for unsigned, int, unsigned long
> long, long long, unsigned int128 and int128 types (assuming ilp32 or lp64)
> plus tests for those types.  Takes about 2 minutes to compile + run on a fast
> box and uses random (), so not really sure the tests should go into the
> testsuite.  Thoughts on that?  After all, the generator isn't extra smart and
> doesn't try to find problematic corner cases.

If you work on the 'guess' of a 10x slowdown when using simulators, that's
probably too long particularly if it's not delivering high value. 

Ultimately, it will depend on how much of that 2 minutes is during
generate/compile and how much during run time.