llvm dev - Jul 2016 - RFC: SIMD math-function library

Hi all,

Okay, the point is whether Intel will publish the source code for their 
SVML. If Intel will make SVML open-source, there would be not much 
advantage in incorporating SLEEF into LLVM, since it would be also 
fairly easy to port SVML to other architectures. If Intel will not 
open-source SVML, then there could be advantage in using SLEEF for x86 
by inlining the functions.

Is it possible to ask the person in charge what exactly Intel is going 
to contribute?

Naoki Shibata


On 2016/07/15 12:53, Hal Finkel wrote:
> Hi again,
>
> As this RFC implies, I've been using the SLEEF library proposed here
with Clang/LLVM for many years, and fully support its adoption into the LLVM
project.
>
> I'm CC'ing Matt and Xinmin from Intel who have started working on
contributing support for their SVML library to LLVM
(http://reviews.llvm.org/D19544), and I understand plan to contribute (some
subset of) the vector math functions themselves. I'm also excited about
Intel's planned contributions.
>
> Here's how I currently see the situation: Regardless of what Intel
contributes, we need a solution in this space for many different architectures.
From personal experience, SLEEF is relatively easy to port to different
architectures (i.e. different vector ISAs), and has already been ported to
several. The performance is good as is the accuracy. I think it would make a
great foundation for a vector-math-function runtime library for the LLVM
project. I don't know what routines Intel is planning to contribute, or for
what architectures they're tuned, but I expect we'll want to use those
implementations on x86 platforms where appropriate.
>
> Matt, Xinmin, what do you think?
>
> Thanks again,
> Hal

Naoki, 

Intel is planning open-source SVML library (most of them if it not 100%), 6
functions of SVML are open sourced for GCC and LLVM already. But,  Intel SVML is
x86 centric (SSE2, SSSE3, SSE4.1, SSE4.2, AVX, AVX2 ....}. Personally, I am not
sure if it would be fairly easy to port SVML to other architectures. SVML
library team may provide a better answer, I will double check with them.

Given that SLEEF supports many different architectures, I think it has a value
for LLVM, at least before all porting is done for SVML library to other
architectures by LLVM community after Intel open sourced it.

Thanks, 
Xinmin

-----Original Message-----
From: Naoki Shibata [mailto:shibatch.sf.net at gmail.com] 
Sent: Thursday, July 14, 2016 9:38 PM
To: Hal Finkel <hfinkel at anl.gov>
Cc: llvm-dev at lists.llvm.org; Chandler Carruth <chandlerc at gmail.com>;
Tian, Xinmin <xinmin.tian at intel.com>; Masten, Matt <matt.masten at
intel.com>
Subject: Re: RFC: SIMD math-function library


Hi all,

Okay, the point is whether Intel will publish the source code for their SVML. If
Intel will make SVML open-source, there would be not much advantage in
incorporating SLEEF into LLVM, since it would be also fairly easy to port SVML
to other architectures. If Intel will not open-source SVML, then there could be
advantage in using SLEEF for x86 by inlining the functions.

Is it possible to ask the person in charge what exactly Intel is going to
contribute?

Naoki Shibata


On 2016/07/15 12:53, Hal Finkel wrote:
> Hi again,
>
> As this RFC implies, I've been using the SLEEF library proposed here
with Clang/LLVM for many years, and fully support its adoption into the LLVM
project.
>
> I'm CC'ing Matt and Xinmin from Intel who have started working on
contributing support for their SVML library to LLVM
(http://reviews.llvm.org/D19544), and I understand plan to contribute (some
subset of) the vector math functions themselves. I'm also excited about
Intel's planned contributions.
>
> Here's how I currently see the situation: Regardless of what Intel
contributes, we need a solution in this space for many different architectures.
From personal experience, SLEEF is relatively easy to port to different
architectures (i.e. different vector ISAs), and has already been ported to
several. The performance is good as is the accuracy. I think it would make a
great foundation for a vector-math-function runtime library for the LLVM
project. I don't know what routines Intel is planning to contribute, or for
what architectures they're tuned, but I expect we'll want to use those
implementations on x86 platforms where appropriate.
>
> Matt, Xinmin, what do you think?
>
> Thanks again,
> Hal

Is it possible to see the source code of the open-sourced SVML? The diff 
file does not include the library. I searched the Internet but I could 
not find.

Regards,

Naoki Shibata


On 2016/07/15 13:55, Tian, Xinmin wrote:
> Naoki,
>
> Intel is planning open-source SVML library (most of them if it not 100%), 6
functions of SVML are open sourced for GCC and LLVM already. But,  Intel SVML is
x86 centric (SSE2, SSSE3, SSE4.1, SSE4.2, AVX, AVX2 ....}. Personally, I am not
sure if it would be fairly easy to port SVML to other architectures. SVML
library team may provide a better answer, I will double check with them.
>
> Given that SLEEF supports many different architectures, I think it has a
value for LLVM, at least before all porting is done for SVML library to other
architectures by LLVM community after Intel open sourced it.
>
> Thanks,
> Xinmin

Hi everyone,

I think that everyone is on the same page. We'll put together a patch for
review.

One remaining question: There seem two potential homes for this library:
parallel_libs and compiler-rt. Opinions on where the vectorized math functions
should live? My inclination is to target it for the new parallel_libs project,
in part because I feel like compiler-rt has too many things grouped together
already, and in part because vectorization is a form of parallel execution.
Thoughts?

Thanks again,
Hal

----- Original Message -----
> From: "Xinmin Tian" <xinmin.tian at intel.com>
> To: "Naoki Shibata" <shibatch.sf.net at gmail.com>,
"Hal Finkel" <hfinkel at anl.gov>
> Cc: llvm-dev at lists.llvm.org, "Chandler Carruth" <chandlerc
at gmail.com>, "Matt Masten" <matt.masten at intel.com>
> Sent: Thursday, July 14, 2016 11:55:24 PM
> Subject: RE: RFC: SIMD math-function library
> 
> Naoki,
> 
> Intel is planning open-source SVML library (most of them if it not
> 100%), 6 functions of SVML are open sourced for GCC and LLVM
> already. But,  Intel SVML is x86 centric (SSE2, SSSE3, SSE4.1,
> SSE4.2, AVX, AVX2 ....}. Personally, I am not sure if it would be
> fairly easy to port SVML to other architectures. SVML library team
> may provide a better answer, I will double check with them.
> 
> Given that SLEEF supports many different architectures, I think it
> has a value for LLVM, at least before all porting is done for SVML
> library to other architectures by LLVM community after Intel open
> sourced it.
> 
> Thanks,
> Xinmin
> 
> -----Original Message-----
> From: Naoki Shibata [mailto:shibatch.sf.net at gmail.com]
> Sent: Thursday, July 14, 2016 9:38 PM
> To: Hal Finkel <hfinkel at anl.gov>
> Cc: llvm-dev at lists.llvm.org; Chandler Carruth <chandlerc at
gmail.com>;
> Tian, Xinmin <xinmin.tian at intel.com>; Masten, Matt
> <matt.masten at intel.com>
> Subject: Re: RFC: SIMD math-function library
> 
> 
> Hi all,
> 
> Okay, the point is whether Intel will publish the source code for
> their SVML. If Intel will make SVML open-source, there would be not
> much advantage in incorporating SLEEF into LLVM, since it would be
> also fairly easy to port SVML to other architectures. If Intel will
> not open-source SVML, then there could be advantage in using SLEEF
> for x86 by inlining the functions.
> 
> Is it possible to ask the person in charge what exactly Intel is
> going to contribute?
> 
> Naoki Shibata
> 
> 
> On 2016/07/15 12:53, Hal Finkel wrote:
> > Hi again,
> >
> > As this RFC implies, I've been using the SLEEF library proposed
> > here with Clang/LLVM for many years, and fully support its
> > adoption into the LLVM project.
> >
> > I'm CC'ing Matt and Xinmin from Intel who have started working
on
> > contributing support for their SVML library to LLVM
> > (http://reviews.llvm.org/D19544), and I understand plan to
> > contribute (some subset of) the vector math functions themselves.
> > I'm also excited about Intel's planned contributions.
> >
> > Here's how I currently see the situation: Regardless of what Intel
> > contributes, we need a solution in this space for many different
> > architectures. From personal experience, SLEEF is relatively easy
> > to port to different architectures (i.e. different vector ISAs),
> > and has already been ported to several. The performance is good as
> > is the accuracy. I think it would make a great foundation for a
> > vector-math-function runtime library for the LLVM project. I don't
> > know what routines Intel is planning to contribute, or for what
> > architectures they're tuned, but I expect we'll want to use
those
> > implementations on x86 platforms where appropriate.
> >
> > Matt, Xinmin, what do you think?
> >
> > Thanks again,
> > Hal
> 
> 
-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory