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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.


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