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Date: Tue, 28 Sep 2021 14:38:08 +0200 (CEST)
From: Richard Biener <rguenther@suse.de>
To: Ilya Leoshkevich <iii@linux.ibm.com>
cc: gcc-patches@gcc.gnu.org, Andreas Krebbel <krebbel@gcc.gnu.org>
Subject: Re: [PATCH v3 3/3] reassoc: Test rank biasing
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On Tue, 28 Sep 2021, Ilya Leoshkevich wrote:

> On Tue, 2021-09-28 at 13:28 +0200, Richard Biener wrote:
> > On Sun, 26 Sep 2021, Ilya Leoshkevich wrote:
> > 
> > > Add both positive and negative tests.
> > 
> > The tests will likely be quite fragile with respect to what is
> > actually vectorized on which target.  If you move the tests
> > to gcc.dg/vect/ you could at least do
> > 
> > /* { dg-require-effective-target vect_int } */
> > 
> > do you need to look for the exact GIMPLE IL or is it enough to
> > verify we are vectorizing the reduction?
> 
> Actually I don't think vectorization is that important here, and I
> only check how many times sum_x = sum_y + _z appears.  So I use
> (?:vect_)?, which may or may not be there.
> 
> An alternative I considered was to use -fno-tree-vectorize to get
> smaller regexes, but I thought it would be nice to know that
> vectorization does not mess up reassociation results.

Ah, OK.  So lets go ahead with the patch unchanged, but be prepared
to deal with eventual fallout here on weird targets.

Thanks,
Richard.