[llvm-dev] RFC: SIMD math-function library

[Hal Finkel via llvm-dev]

Hi again,

To start the conversation (and review) of the technical elements, I've put together an initial patch: https://reviews.llvm.org/D24951

Thanks again,
Hal

----- Original Message -----
> From: "Hal Finkel via llvm-dev" <llvm-dev at lists.llvm.org>
> To: "Chandler Carruth" <chandlerc at gmail.com>, llvm-dev at lists.llvm.org
> Cc: "Naoki Shibata" <shibatch.sf.net at gmail.com>, "Matt Masten" <matt.masten at intel.com>
> Sent: Wednesday, July 27, 2016 10:46:22 AM
> Subject: Re: [llvm-dev] RFC: SIMD math-function library
> 
> 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
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> 

-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory