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Re: [Patch Ping] [RFC] Alias export patch
- From: Daniel Berlin <dberlin at dberlin dot org>
- To: Andrey Belevantsev <abel at ispras dot ru>
- Cc: Richard Guenther <richard dot guenther at gmail dot com>, Andrew MacLeod <amacleod at redhat dot com>, Diego Novillo <dnovillo at redhat dot com>, Dmitry Melnik <dm at ispras dot ru>, gcc-patches at gcc dot gnu dot org
- Date: Mon, 05 Jun 2006 08:20:11 -0400
- Subject: Re: [Patch Ping] [RFC] Alias export patch
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Andrey Belevantsev wrote:
> Richard Guenther wrote:
>> I wonder how/if you deal with the problem that the tree loop optimizers
>> (ivopts mostly) generate new pointers as induction variables but we don't
>> run may_alias after them, so possibly all interesting (performance wise)
>> pointers do not have updated points-to information? Do your numbers
>> (not performance) improve if you specify -fno-tree-loop-optimize?
> Since the patch was created, we wanted to insert an additional
> pass_may_alias before going out of ssa to cope with this problem.
> However, as ivopts does not keep the points-to information updated, this
> does not work -- gcc ICEs in verify_ssa.
Last time i looked at this issue, it was because none of the aliasing
infrastructure (tree-ssa-alias, tree-ssa-structalias) was updated when
MEM_REF was introduced, and thus, doesn't treat MEM_REF like a pointer
This causes some incorrect things to happen, and verify_ssa notices.