[llvm-dev] Compile for ARM SVE with the latest LLVM

[Will Lovett via llvm-dev]

Hi Itaru,

That’s a slightly complex question. We aim to upstream all codegen improvements, and once base SVE support is upstream we will find it easier to upstream things faster (or, in some cases, develop upstream ‘first’). However, this is a moving target, since we’re actively developing the downstream compiler, so it is likely there will always be a little delta.

Secondly, we have some functionality (such as tuned scalar and vector math and string libraries, or the Fortran frontend), for which the base functionality is available upstream, but is more easily available and tightly integrated in the product.

Finally, we have some functionality (such as our tuned BLAS/Lapack/FFT libraries) which we don’t have any current plans of making available publicly.

Hope that’s helpful,

Will.

Will Lovett
Technical Product Owner
Compilers & Libraries
Arm Allinea Studio

Sent from a mobile device, sorry for typos and brevity!
________________________________
From: Itaru Kitayama <itaru.kitayama at gmail.com>
Sent: Wednesday, September 18, 2019 7:25:57 AM
To: Will Lovett <Will.Lovett at arm.com>
Cc: Renato Golin <rengolin at gmail.com>; LLVM Dev <llvm-dev at lists.llvm.org>; Sander De Smalen <Sander.DeSmalen at arm.com>; Cullen Rhodes <Cullen.Rhodes at arm.com>
Subject: Re: [llvm-dev] Compile for ARM SVE with the latest LLVM

Will,
When you guys announce the SVE codegen support is merged in the trunk, hopefully in the near future, that means all of the features/functions
that can currently be found in the current release of Arm Compiler for Linux, correct? We were sitting down this afternoon and wondering about
this a bit thus I am asking.

On Thu, Sep 12, 2019 at 5:44 PM Will Lovett <Will.Lovett at arm.com<mailto:Will.Lovett at arm.com>> wrote:
Hi Itaru,

(and thanks for the replies on this Renato).

We (Arm HPC) initially put up that github branch as an aid to the discussions on upstream SVE support.  The branch was very old (LLVM-5 based!), and various aspects of our implementation have changed significantly, following discussions with the community.  For this reason, we felt that branch was unhelpful at this point, so have removed it.

The team are working hard on getting SVE codegen support into LLVM, but it’s not there yet.  For now, this leaves the following options for testing vectorization with SVE:

  *   Get an up to date GNU compiler, which has SVE vectorization support
  *   Use Arm Compiler for Linux (the new name for Arm Compiler for HPC)

If you’re interested in the latter option, feel free to give me a mail (will.lovett at arm dot com).  Depending on your use-case, there may be scope for arranging a license.

Thanks,

Will.


Will Lovett
Technical Product owner
Compilers & Libraries
Arm Allinea Studio

On 11/09/2019, 22:31, "llvm-dev on behalf of Itaru Kitayama via llvm-dev" <llvm-dev-bounces at lists.llvm.org<mailto:llvm-dev-bounces at lists.llvm.org> on behalf of llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:

Renato et al.
In the meantime, is there an out of tree branch I mean, other than LLVM trunk so I can test how much I can SVE vectorize my code with it?

Arm seemed to gave taken down the GitHub branch for sometime.

On Wed, Sep 11, 2019 at 20:41 Renato Golin <rengolin at gmail.com<mailto:rengolin at gmail.com>> wrote:
On Wed, 11 Sep 2019 at 06:13, Itaru Kitayama via llvm-dev
<llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:
> Hi,
> I'm still seeing the same ie trying to produce SVE instructions but
> resulted in NEONs with Clang as of Sep. 10th.
> http://lists.llvm.org/pipermail/llvm-dev/2019-March/130788.html

Hi Itaru-san,

IR SVE implementation is ongoing, CC'ing Graham who is leading that effort.

I'm hoping we can have something working before the next release is
branched (Dec/Jan), but I don't expect it to be fully featured (inline
asm, full ACLE, auto-vec in all NEON cases, etc).

cheers,
--renato
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