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

Tian, Xinmin via llvm-dev llvm-dev at lists.llvm.org
Thu Jul 14 21:55:24 PDT 2016


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. 


-----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

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