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Re: [patch] Fix a problem in examination of may-alias sets with partitions
- From: Ira Rosen <IRAR at il dot ibm dot com>
- To: "Richard Guenther" <richard dot guenther at gmail dot com>
- Cc: gcc-patches at gnu dot org
- Date: Mon, 15 Jan 2007 15:56:03 +0200
- Subject: Re: [patch] Fix a problem in examination of may-alias sets with partitions
"Richard Guenther" <richard.guenther@gmail.com> wrote on 15/01/2007
15:40:52:
> On 1/15/07, Ira Rosen <IRAR@il.ibm.com> wrote:
> >
> > In function is_aliased_with (tree-ssa-alias.c) every entry of tag's
> > may-alias set is compared to a given symbol to find out whether this
symbol
> > belongs to the may-alias set. Since MEM-SSA has been merged, may-alias
set
> > can also contain MPTs. Therefore, we now also have to check whether the
> > symbol belongs to one of the MPTs of the may-alias set.
> >
> > The testcases vect-37.c, vect-57.c and vect-61.c are supposed not to
get
> > vectorized because of aliasing. With MEM-SSA, NMTs' may-alias sets in
these
> > tests contain MPTs, causing is_aliased_with() return a wrong answer,
and,
> > therefore, causing vectorization of the loops in the tests. Currently,
> > vect-57.c and vect-61.c xpass. vect-37.c was changed to expect pass in
the
> > MEM-SSA merge. This patch will restore the original behavior of
vect-37.c
> > and will make vect-57.c and vect-61.c to fail as they should.
>
> Maybe you should update these testcases so they FAIL if they get
vectorized...
>
But there is no real dependency in these tests. With flow-sensitive
interprocedural alias analysis they should get vectorized. Maybe, I should
open a missed-optimization pr for this.
Ira