[Bug rtl-optimization/66552] Missed optimization when shift amount is result of signed modulus

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66552

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Li Jia He from comment #5)
> Could we consider doing this optimization on gimple? I use the following
> code on gimple to produce optimized results on powerpc64.

It might make sense.  But fold-const.c might not be the correct location;
match.pd might be a better place for it.