[Bug tree-optimization/87132] [9 Regression] Gcc miscompiles at -O2 on valid code

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87132

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Mon Sep 16 11:58:35 2019
New Revision: 275747

URL: https://gcc.gnu.org/viewcvs?rev=275747&root=gcc&view=rev
Log:
2019-09-16  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/91756
        PR tree-optimization/87132
        * tree-ssa-alias.h (enum translate_flags): New.
        (get_continuation_for_phi): Use it instead of simple bool flag.
        (walk_non_aliased_vuses): Likewise.
        * tree-ssa-alias.c (maybe_skip_until): Adjust.
        (get_continuation_for_phi): When looking across backedges only
        disallow valueization.
        (walk_non_aliased_vuses): Adjust.
        * tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid valueization
        if requested.

        * gcc.dg/tree-ssa/ssa-fre-81.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-81.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-alias.c
    trunk/gcc/tree-ssa-alias.h
    trunk/gcc/tree-ssa-sccvn.c