[Bug tree-optimization/85757] tree optimizers fail to fully clean up fixed-size memcpy

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85757

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu May 17 06:57:45 2018
New Revision: 260306

URL: https://gcc.gnu.org/viewcvs?rev=260306&root=gcc&view=rev
Log:
2018-05-17  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/85757
        * tree-ssa-dse.c (dse_classify_store): Record a PHI def and
        remove defs that only feed that PHI from further processing.

        * gcc.dg/tree-ssa/ssa-dse-34.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-34.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-dse.c