[Bug tree-optimization/71866] [7 Regression] gcc locks up after fix for PR70159

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71866

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Jul 14 12:15:38 2016
New Revision: 238334

URL: https://gcc.gnu.org/viewcvs?rev=238334&root=gcc&view=rev
Log:
2016-07-14  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/71866
        * tree-ssa-pre.c (get_constant_for_value_id): Remove.
        (do_hoist_insertion): Avoid endless recursion when we
        didn't insert anything because we managed to simplify
        things down to a constant or SSA name.
        (fully_constant_expression): Re-write in terms of ...
        * tree-ssa-sccvn.h (vn_nary_simplify): ... this.  Declare.
        * tree-ssa-sccvn.c (vn_nary_simplify): New wrapper around
        vn_nary_build_or_lookup_1.
        (vn_nary_build_or_lookup_1): Added flag and renamed from ...
        (vn_nary_build_or_lookup): ... this which now wraps it.

        * gcc.dg/torture/pr71866.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr71866.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-pre.c
    trunk/gcc/tree-ssa-sccvn.c
    trunk/gcc/tree-ssa-sccvn.h