• Stefanos Baziotis (16/16) Aug 02 2019 As part of my GSoC project, I wanted to use SIMD intrinsics. But
• Guillaume Piolat (9/12) Aug 02 2019 Hello,
• Stefanos Baziotis (20/29) Aug 02 2019 Hello Guillaume,
• Guillaume Piolat (8/12) Aug 03 2019 Well yes what you did makes a lot of sense, since it's druntime
• Stefanos Baziotis (10/18) Aug 03 2019 Apart from memset, memcpy etc., I think that if we are to have a
• kinke (5/6) Aug 02 2019 Johan suggests implementing some small core.simd subset
• Stefanos Baziotis (2/6) Aug 03 2019 Yes, that could be done as well.

Stefanos Baziotis <sdi1600105 di.uoa.gr> writes:

As part of my GSoC project, I wanted to use SIMD intrinsics. But 
I could not find a way to write cross-compiler code. That 
includes core.simd, but also intel-intrinsics.
Specifically intel-intrinsics is a great library, but it could 
not be used in GDC (at least I did not find a way) and it seems 
LDC focused.

So, I wrote a mini SIMD module [1]. This is not very general as 
it was targeted only for the Dmem* utilities. But then I thought, 
why not make such a module in the druntime?

In the link, you can see for example a simple store function. 
Also, it shows
the best I got as far as how to answer the question "Is SIMD 
supported?" across
compilers.

[1] 
https://github.com/dlang/druntime/pull/2687/files#diff-c2fcd73761ae6659ef91245ce1195b6dR70

Guillaume Piolat <first.last gmail.com> writes:

On Friday, 2 August 2019 at 14:56:58 UTC, Stefanos Baziotis wrote:
 Specifically intel-intrinsics is a great library, but it could 
 not be used in GDC (at least I did not find a way) and it seems 
 LDC focused.

Hello,

The reason is that no one stepped up to add this support for GDC 
intel-intrinsics, but it is on the roadmap for next year. I can't 
contribute to D OSS all day, since I need to put out products 
made with D too ; so users of intel-intrinsics have to be patient 
or contribute themselves.

Do not underestimate the sheer amount of work needed to make 
"cross-compiler SIMD module".

Stefanos Baziotis <sdi1600105 di.uoa.gr> writes:

On Friday, 2 August 2019 at 20:38:37 UTC, Guillaume Piolat wrote:
 Hello,

 The reason is that no one stepped up to add this support for 
 GDC intel-intrinsics, but it is on the roadmap for next year. I 
 can't contribute to D OSS all day, since I need to put out 
 products made with D too ;

Hello Guillaume,

Don't take this as criticism to intel-intrinsics. On the 
contrary, I mention it here and there as it is the best SIMD 
library for D I know (apart from core.simd).

However, I feel like this should be part of druntime core and not 
an external
library since core.simd already exists but is not cross-compiler.

 Do not underestimate the sheer amount of work needed to make 
 "cross-compiler SIMD module".

I agree, although I probably don't know all the hurdles since I 
have not made one.
I proposed the idea and I'm willing to put time on it, if
the community wants it. It doesn't necessarily mean that I will 
be able to do it myself.

I invite people who have more experience (like you) to give 
advice and / or help.

 so users of intel-intrinsics have to be patient or contribute 
 themselves.

If the community is not positive on that, then my plan is to 
contribute
to intel-intrinsics.

Best,
Stefanos

Guillaume Piolat <first.last gmail.com> writes:

On Friday, 2 August 2019 at 20:59:04 UTC, Stefanos Baziotis wrote:
 However, I feel like this should be part of druntime core and 
 not an external
 library since core.simd already exists but is not 
 cross-compiler.


Well yes what you did makes a lot of sense, since it's druntime 
that will have to implement memcpy/memset/etc. So there is indeed 
a need for something in druntime.

(intel-intrinsics is Boost-licensed and one can use any part of 
it, but it's not like is has been "approved" in terms of DUB 
popularity (which I feel is a necessary first step, along with 
GDC support)).

Stefanos Baziotis <sdi1600105 di.uoa.gr> writes:

On Saturday, 3 August 2019 at 10:01:37 UTC, Guillaume Piolat 
wrote:
 On Friday, 2 August 2019 at 20:59:04 UTC, Stefanos Baziotis

 Well yes what you did makes a lot of sense, since it's druntime 
 that will have to implement memcpy/memset/etc. So there is 
 indeed a need for something in druntime.

Apart from memset, memcpy etc., I think that if we are to have a 
simd
module, that makes sense to be cross-compiler. On the other hand, 
people seem to
like the idea to add them separately on LDC and GDC versions. I 
don't know.

 (intel-intrinsics is Boost-licensed and one can use any part of 
 it, but it's not like is has been "approved" in terms of DUB 
 popularity (which I feel is a necessary first step, along with 
 GDC support)).

Well, it seems like a sane way to do SIMD. I hope it goes well.

Stefanos

kinke <noone nowhere.com> writes:

On Friday, 2 August 2019 at 14:56:58 UTC, Stefanos Baziotis wrote:
 But then I thought, why not make such a module in the druntime?

Johan suggests implementing some small core.simd subset 
(load/storeUnaligned, prefetch) in the LDC and GDC druntime 
flavours instead:
https://github.com/ldc-developers/ldc/issues/3121

Stefanos Baziotis <sdi1600105 di.uoa.gr> writes:

On Saturday, 3 August 2019 at 00:13:09 UTC, kinke wrote:
 Johan suggests implementing some small core.simd subset 
 (load/storeUnaligned, prefetch) in the LDC and GDC druntime 
 flavours instead:
 https://github.com/ldc-developers/ldc/issues/3121

Yes, that could be done as well.