[Bug tree-optimization/90883] Generated code is worse if returned struct is unnamed

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90883

--- Comment #27 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Fri Oct 11 13:10:15 2019
New Revision: 276882

URL: https://gcc.gnu.org/viewcvs?rev=276882&root=gcc&view=rev
Log:
2019-10-11  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/90883
        PR tree-optimization/91091
        * tree-ssa-sccvn.c (vn_reference_lookup_3): Use correct
        alias-sets both for recording VN table entries and continuing
        walking after translating through copies.  Handle same-sized
        reads from SSA names by returning the plain SSA name.
        (eliminate_dom_walker::eliminate_stmt): Properly handle
        non-size precision stores in redundant store elimination.

        * gcc.dg/torture/20191011-1.c: New testcase.
        * gcc.dg/tree-ssa/ssa-fre-82.c: Likewise.
        * gcc.dg/tree-ssa/ssa-fre-83.c: Likewise.
        * gcc.dg/tree-ssa/redundant-assign-zero-1.c: Disable FRE.
        * gcc.dg/tree-ssa/redundant-assign-zero-2.c: Likewise.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/20191011-1.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-82.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-83.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-1.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/redundant-assign-zero-2.c
    trunk/gcc/tree-ssa-sccvn.c