[Bug tree-optimization/70497] Missed CSE of subregs on GIMPLE

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70497

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Tue May 10 08:20:43 2016
New Revision: 236066

URL: https://gcc.gnu.org/viewcvs?rev=236066&root=gcc&view=rev
Log:
2016-05-10  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/70497
        PR tree-optimization/28367
        * tree-ssa-sccvn.c (vn_nary_build_or_lookup): New function
        split out from ...
        (visit_reference_op_load): ... here.
        (vn_reference_lookup_3): Use it to handle subreg-like accesses
        with simplified BIT_FIELD_REFs.
        * tree-ssa-pre.c (eliminate_insert): Handle inserting BIT_FIELD_REFs.
        * tree-complex.c (extract_component): Handle BIT_FIELD_REFs
        correctly.

        * gcc.dg/torture/20160404-1.c: New testcase.
        * gcc.dg/tree-ssa/ssa-fre-54.c: Likewise.
        * gcc.dg/tree-ssa/ssa-fre-55.c: Likewise.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/20160404-1.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-54.c
    trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-55.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-complex.c
    trunk/gcc/tree-ssa-pre.c
    trunk/gcc/tree-ssa-sccvn.c