[Bug tree-optimization/79725] Sinking opportunity missed if blocked by dead stmt

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79725

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Mon Apr 24 07:48:47 2017
New Revision: 247091

URL: https://gcc.gnu.org/viewcvs?rev=247091&root=gcc&view=rev
Log:
2017-04-24  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/79725
        * tree-ssa-sink.c (statement_sink_location): Return whether
        failure reason was zero uses.  Move that check later.
        (sink_code_in_bb): Deal with zero uses by removing the stmt
        if possible.

        * gcc.dg/tree-ssa/ssa-sink-15.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-15.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-sink.c