[Bug tree-optimization/55936] [4.9/5/6 Regression] Missed VRP optimization

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55936

--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Mar  3 09:12:53 2016
New Revision: 233928

URL: https://gcc.gnu.org/viewcvs?rev=233928&root=gcc&view=rev
Log:
2016-03-03  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/55936
        * tree-vrp.c (compare_name_with_value): Add use_equiv_p
        parameter and guard unsafe equivalence use.
        (vrp_evaluate_conditional_warnv_with_ops): Always use
        safe equivalences but not via the quadratic compare_names
        helper.

        * gcc.dg/tree-ssa/vrp06.c: Remove XFAIL.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/vrp06.c
    trunk/gcc/tree-vrp.c