This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
RE: [PATCH] Use rtx_refs_may_alias_p instead of alias_sets_conflict_p in
Does rtx_refs_may_alias_p include offset based disambiguation (with/without
tbaa flag). If yes, this patch is not correct, I need to work out
a better one.
Cheers,
Bingfeng
> -----Original Message-----
> From: Michael Matz [mailto:matz@suse.de]
> Sent: 04 August 2010 16:36
> To: Richard Guenther
> Cc: Diego Novillo; Bingfeng Mei; gcc-patches@gcc.gnu.org
> Subject: Re: [PATCH] Use rtx_refs_may_alias_p instead of
> alias_sets_conflict_p in
>
> Hi,
>
> On Wed, 4 Aug 2010, Richard Guenther wrote:
>
> > /* Given two nodes, analyze their RTL insns and add inter-loop mem
> deps
> > to ddg G. */
> > static void
> > add_inter_loop_mem_dep (ddg_ptr g, ddg_node_ptr from, ddg_node_ptr to)
> > {
> > if (!insn_alias_sets_conflict_p (from->insn, to->insn))
> > /* Do not create edge if memory references have disjoint alias
> sets. */
> > return;
> >
> > the comment ("inter-loop mem deps") suggests that using TBAA
> > is not valid here.
>
> Careful. type-based alias analysis can be used. It's offset-based
> disambiguation that cannot for cross-iteration references.
>
> Unfortunately I don't think the current interface we have make it
> possible
> to use TBAA but not also offset-based disambiguation.
>
>
> Ciao,
> Michael.