[PATCH] std::experimental::simd

[Dr. Matthias Kretz]

On Dienstag, 7. Januar 2020 12:16:57 CET Andrew Pinski wrote:
> On Tue, Jan 7, 2020 at 3:01 AM Matthias Kretz <m.kretz@gsi.de> wrote:
> > Is there any chance left we can get this done for 10.1? If not, can we
> > please get it ready for 10.2 ASAP?
> > 
> > Cheers,
> > 
> >   Matthias
> > 
> > On Montag, 14. Oktober 2019 14:12:12 CET Matthias Kretz wrote:
> > > Let me try again to get this patch ready. It will need a few
> > > iterations...
> > > This patch is without documentation and testsuite. I can add them on
> > > request but would prefer a follow-up patch after getting this one
> > > right.
> > > 
> > > I recommend to review starting from simd.h + simd_scalar.h, then
> > > simd_builtin.h, simd_x86.h, and simd_fixed_size.h. I sure when we get
> > > this
> > > far we are a few iterations further.
> > > 
> > > Regarding the license. The license header is currently just a copy from
> > > my
> > > repo, but we can change it to the libstdc++ license. The paperwork with
> > > the
> > > FSF is done.
> 
> Seems like it would be better if we put the x86 and aarch64/arm
> specific parts in their own headers.

Yes. I'm already working on it. It makes me unhappy in some of the generic 
parts of the code, but I think it's still a worthwhile reorganization. Last 
state is here: https://github.com/VcDevel/std-simd/tree/master/experimental/
bits
I'll prepare a new patch.

> Also all of the x86 conversion should be removed as
> __builtin_convertvector  is supported now.

simd_x86_conversions.h is about PR85048 (and more missing optimizations). I'd 
prefer to implement simd_x86_conversions.h in the compiler, but I'd need some 
guidance. I'd like the first release of std::experimental::simd to have high 
performance - because that's the main reason for using it. I'd rather wait a 
release than taint the impression of its usefulness.

> libstdc++v3 is only ever supported by the version that comes with the
> compiler.

Right, that's an artifact of having active users of this code. I'll clean it 
up.

Thanks for the feedback,
  Matthias

-- 
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 Dr. Matthias Kretz           │ SDE — Software Development for Experiments
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 SIMD Expert,                 │ 📧 m.kretz@gsi.de
 ISO C++ Committee Member     │ 🔗 mattkretz.github.io
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