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Re: [RFC] VEC_SELECT sanity checking in genrecog
- From: Michael Meissner <meissner at linux dot vnet dot ibm dot com>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, Jakub Jelinek <jakub at redhat dot com>, Eric Botcazou <ebotcazou at adacore dot com>, Richard Biener <rguenther at suse dot de>, Bernd Schmidt <bschmidt at redhat dot com>, Jeff Law <law at redhat dot com>, gcc-patches at gcc dot gnu dot org, Bill Schmidt <wschmidt at linux dot vnet dot ibm dot com>
- Date: Fri, 3 Mar 2017 16:39:08 -0500
- Subject: Re: [RFC] VEC_SELECT sanity checking in genrecog
- Authentication-results: sourceware.org; auth=none
- References: <20170303162827.GD1849@tucnak> <20170303201957.GI31469@gate.crashing.org> <20170303204303.GA11106@ibm-tiger.the-meissners.org> <20170303205806.GL31469@gate.crashing.org>
On Fri, Mar 03, 2017 at 02:58:06PM -0600, Segher Boessenkool wrote:
> On Fri, Mar 03, 2017 at 03:43:03PM -0500, Michael Meissner wrote:
> > On Fri, Mar 03, 2017 at 02:19:57PM -0600, Segher Boessenkool wrote:
> > > On Fri, Mar 03, 2017 at 05:28:27PM +0100, Jakub Jelinek wrote:
> > > Yeah, it looks like these patterns should use VSX_D instead of VSX_LE.
> > > Mike, you know this code best, what do you think?
> >
> > Bill Schmidt added these, but he is gone for the day.
> >
> > No, these patterns need to use VSX_LE, but V1TI should be moved from VSX_LE to
> > VSX_LE_128. VSX_LE_128 is used for things like IEEE 128-bit floating point and
> > 128-bit integers that can't use vec_select. In fact there is this comment:
> >
> > ;; Little endian word swapping for 128-bit types that are either scalars or the
> > ;; special V1TI container class, which it is not appropriate to use vec_select
> > ;; for the type.
>
> Okay, but there are also these comments:
>
> ;; Iterator for the 2 64-bit vector types
> (define_mode_iterator VSX_D [V2DF V2DI])
>
> ;; Iterator for the 2 64-bit vector types + 128-bit types that are loaded with
> ;; lxvd2x to properly handle swapping words on little endian
> (define_mode_iterator VSX_LE [V2DF V2DI V1TI])
>
> so that removing V1TI from VSX_LE makes it exactly equal to VSX_D.
Yep, VSX_LE would now be redunant.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797