[Bug middle-end/40135] using alias-set zero for union accesses necessary because of RTL alias oracle

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40135

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
At least improved (but maybe not fixed) by

2010-02-16  Richard Guenther  <rguenther@suse.de>

        * alias.c (memrefs_conflict_p): Distinguish must-alias from don't know.
        (true_dependence): If memrefs_conflict_p computes must-alias
        trust it.  Move TBAA check after offset-based disambiguation.
        (canon_true_dependence): Likewise.