[Bug tree-optimization/67892] [5/6 Regression] Wrong code at -O1 and above

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67892

--- Comment #3 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Author: law
Date: Thu Oct 29 16:20:06 2015
New Revision: 229538

URL: https://gcc.gnu.org/viewcvs?rev=229538&root=gcc&view=rev
Log:
[PATCH][PR tree-optimization/67892] Use FSM threader to handle backedges

        PR tree-optimization/67892
        * tree-ssa-threadedge.c (simplify_controL_stmt_condition): Fix typo
        in comment.
        (thread_through_normal_block): If we have seen a backedge, then
        do nothing.  No longer call find_jump_threads_backwards here.
        (thread_across_edge): Use find_jump_threads_backwards to find
        jump threads if the old style threader was not successful.
        * tree-ssa-threadbackward.c (get_gimple_control_stmt): Use
        gsi_last_nondebug_bb.  Return NULL if the block does not end
        with a control statement.
        (find_jump_threads_backwards): Setup code moved here from
        tree-ssa-threadedge.c::thread_through_normal_block.  Accept
        single edge argument instead of name & block.
        * tree-ssa-threadbackward.h (find_jump_threads_backwards): Update
        prototype.

        PR tree-optimization/67892
        * gcc.dg/tree-ssa/pr21417: Update expected output.
        * gcc.dg/tree-ssa/ssa-dom-thread-2b.c: Likewise.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr21417.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-2b.c
    trunk/gcc/tree-ssa-threadbackward.c
    trunk/gcc/tree-ssa-threadbackward.h
    trunk/gcc/tree-ssa-threadedge.c