[Bug tree-optimization/100051] missed optimization for dead code elimination at -Os, -O2 and -O3 (vs. -O1)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100051

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:d1d01a66012a93cc8cb7dafbe1b5ec453ec96b59

commit r12-145-gd1d01a66012a93cc8cb7dafbe1b5ec453ec96b59
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Apr 13 10:12:03 2021 +0200

    tree-optimization/100051 - disambiguate access size vs decl

    This adds disambiguation of the access size vs. the decl size
    in the pointer based vs. decl based disambiguator.  We have
    a TBAA based check like this already but that's fend off when
    seeing alias-sets of zero or when -fno-strict-aliasing is in
    effect.  Also the perceived dynamic type could be smaller than
    the actual access.

    2021-04-13  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/100051
            * tree-ssa-alias.c (indirect_ref_may_alias_decl_p): Add
            disambiguator based on access size vs. decl size.

            * gcc.dg/tree-ssa/ssa-fre-92.c: New testcase.