[Bug tree-optimization/37242] missed FRE opportunity because of signedness of addition

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37242

--- Comment #28 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Tue Aug 20 12:02:56 2019
New Revision: 274746

URL: https://gcc.gnu.org/viewcvs?rev=274746&root=gcc&view=rev
Log:
2019-08-20  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/37242
        * tree-ssa-sccvn.c (visit_nary_op): Also CSE (T)(a + b)
        to (T)a + (T)b if we know that a + b does not overflow.

        * gcc.dg/tree-ssa/ssa-fre-80.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-80.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-sccvn.c