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

[jakub at gcc dot gnu.org]

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

--- Comment #30 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Wed Sep 12 18:28:20 2018
New Revision: 264248

URL: https://gcc.gnu.org/viewcvs?rev=264248&root=gcc&view=rev
Log:
        PR middle-end/82853
        * expr.h (maybe_optimize_mod_cmp): Declare.
        * expr.c (mod_inv): New function.
        (maybe_optimize_mod_cmp): New function.
        (do_store_flag): Use it.
        * cfgexpand.c (expand_gimple_cond): Likewise.

        * gcc.target/i386/pr82853-1.c: New test.
        * gcc.target/i386/pr82853-2.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/i386/pr82853-1.c
    trunk/gcc/testsuite/gcc.target/i386/pr82853-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgexpand.c
    trunk/gcc/expr.c
    trunk/gcc/expr.h
    trunk/gcc/testsuite/ChangeLog