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RE: Vector modes and the corresponding width integer mode
- From: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- To: Bingfeng Mei <bmei at broadcom dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Fri, 12 Dec 2014 20:19:47 +0000
- Subject: RE: Vector modes and the corresponding width integer mode
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B0235320F84DFC at LEMAIL01 dot le dot imgtec dot org> <B71DF1153024A14EABB94E39368E44A6043086C3 at SJEXCHMB13 dot corp dot ad dot broadcom dot com>
Thanks for commenting. It's reassuring to know that at least some ports
do not have the corresponding integer modes. I have now also understood
some of the background to the extra integer modes in ARM NEON and as
far as I can tell the integer modes represent an opaque view of the
registers as required by the ABI but not for anything relating to
vectorization. I tried to follow some of the X86 code too but it's a bit
too complex to dip into and understand much. I hadn't got to PowerPC
Anyway I've ripped out the TImode handling from our current MSA
implementation and it did not immediately blow up.
> -----Original Message-----
> From: Bingfeng Mei [mailto:firstname.lastname@example.org]
> Sent: 12 December 2014 11:52
> To: Matthew Fortune; email@example.com
> Subject: RE: Vector modes and the corresponding width integer mode
> I don't think it is required. For example, PowerPC port supports
> V8SImode, but I don't see OImode. Just sometimes it could come handy to
> have the equal size scalar mode.
> > -----Original Message-----
> > From: firstname.lastname@example.org [mailto:email@example.com] On Behalf
> > Of Matthew Fortune
> > Sent: 11 December 2014 13:27
> > To: firstname.lastname@example.org
> > Subject: Vector modes and the corresponding width integer mode
> > Hi,
> > I'm working on MIPS SIMD support for MSA. Can anyone point me towards
> > information about the need for an integer mode of equal size to any
> > supported vector mode?
> > I.e. if I support V4SImode is there any core GCC requirement that
> > TImode is also supported?
> > Any guidance is appreciated. The MIPS port already has limited support
> > for TImode for 64-bit targets which makes it all the more difficult to
> > figure out if there is a relationship between vector modes and integer
> > modes.
> > Thanks,
> > Matthew