[Bug tree-optimization/68398] [6 Regression] coremark regression due to r229685

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68398

--- Comment #7 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Author: law
Date: Wed Jan 27 19:19:47 2016
New Revision: 232897

URL: https://gcc.gnu.org/viewcvs?rev=232897&root=gcc&view=rev
Log:
        PR tree-optimization/68398
        * params.def (PARAM_FSM_SCALE_PATH_STMTS): New parameter.
        (PARAM_FSM_SCALE_PATH_BLOCKS): Likewise.
        * tree-ssa-threadbackward.c (fsm_find_control_statement_thread_paths):
        Only count PHIs in the last block in the path.  The others will
        const/copy propagate away.  Add heuristic to allow more irreducible
        subloops to be created when it is likely profitable to do so.

        * tree-ssa-threadbackward.c (fsm_find_control_statement_thread_paths):
        Fix typo in comment.  Use gsi_after_labels and remove the GIMPLE_LABEL
        check from within the loop.  Use gsi_next_nondebug rather than
gsi_next.

        PR tree-optimization/68398
        * gcc.dg/tree-ssa/pr66752-3.c: Update expected output.
        * gcc.dg/tree-ssa/ssa-dom-thread-2c.c: Add extra statements on thread
        path to avoid new heuristic allowing more irreducible regions
        * gcc.dg/tree-ssa/ssa-dom-thread-2d.c: Likewise.
        * gcc.dg/tree-ssa/vrp46.c: Likewise.
        * gcc.dg/tree-ssa/ssa-dom-thread-7.c: Update expected output.
        * gcc.dg/tree-ssa/ssa-dom-thread-2g.c: New test.
        * gcc.dg/tree-ssa/ssa-dom-thread-2h.c: Likewise.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-2g.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-2h.c
      - copied, changed from r232894,
trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-2d.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/params.def
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/pr66752-3.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-2c.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-2d.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/vrp46.c
    trunk/gcc/tree-ssa-threadbackward.c