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RE: Vector modes and the corresponding width integer mode


Hi Bingfeng,

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
yet either.

Anyway I've ripped out the TImode handling from our current MSA
implementation and it did not immediately blow up.

Thanks,
Matthew

> -----Original Message-----
> From: Bingfeng Mei [mailto:bmei@broadcom.com]
> Sent: 12 December 2014 11:52
> To: Matthew Fortune; gcc@gcc.gnu.org
> 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.
> 
> Cheers,
> Bingfeng
> 
> > -----Original Message-----
> > From: gcc-owner@gcc.gnu.org [mailto:gcc-owner@gcc.gnu.org] On Behalf
> > Of Matthew Fortune
> > Sent: 11 December 2014 13:27
> > To: gcc@gcc.gnu.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


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