[llvm-dev] LLVM GPU News Issue #1, December 11 2020

Fri Dec 11 11:17:00 PST 2020

Hi Jakub,

thanks for this effort, very interesting!

OpenMP offloading is actively developed and I was even thinking
to produce a irregular OpenMP newsletter. While I might still do,
I think we should have the OpenMP GPU content in here as well.
What is a good way to do that?

~ Johannes

On 12/11/20 11:26 AM, Jakub (Kuba) Kuderski via llvm-dev wrote:
> Hi folks,
>
> I'm starting a bi-weekly newsletter on all the GPU things under the LLVM
> umbrella: GPU backends in LLVM, GPU dialects in MLIR, middle-end work
> related to GPU compilation, external LLVM- and MLIR-based GPU compilers,
> relevant conference talks, etc. I'm going to publish new issues every other
> Friday on llvm-dev and a dedicated website:  https://llvm-gpu-news.github.io
> .
>
> The first issue is available at:
> https://llvm-gpu-news.github.io/2020/12/11/issue-1.html.
> I'm also pasting the content below, in case you prefer to read in your
> email client.
>
> The high-level goals are to surface common themes in GPU compilation for
> different hardware, and to raise awareness of the general LLVM
> community about important aspects of GPU compilation.
>
> -Jakub
>
> ====================================================================
>
> # LLVM GPU News Issue #1, December 11 2020
>
> Welcome to the first issue of LLVM GPU News, a bi-weekly newsletter on all
> the
> GPU things under the LLVM umbrella. This issues covers the period from
> November 27 to December 10 2020.
>
> We welcome your feedback and suggestions. Let us know if we missed anything
> interesting, or
> want us to bring attention to your (sub)project, revisions under review, or
> proposals.
> Please see the bottom of the page for details on how to submit suggestions
> and contribute.
>
> ## Industry News and Conference Talks
> *  [AMD published the RDNA 2 Instruction Set Architecture manual.](
> https://gpuopen.com/rdna2-isa-available/)
>     Some notable changes from the previous GCN ISA are:
>     *  ray tracing support,
>     *  new dot product ALU operations for accelerated inference and deep
> learning,
>     *  VGPR and LDS allocation-unit size were doubled,
>     *  legacy multiply-add instructions were removed (superseded by
> fused-multiply-add).
>
> ##  LLVM
>
> ### Discussions
> *  Jay Foad ran into [issues with preserved and required transitive
> analyses in the Legacy Pass Manager](
> http://lists.llvm.org/pipermail/llvm-dev/2020-November/146923.html)
>     in AMDGPU. Jay proposes to add a new pass preservation rule, but some
> existing passes currently violate it.
>     There are no replies as of writing.
> *  Arthur Eubanks is working [towards enabling the New Pass Manager](
> http://lists.llvm.org/pipermail/llvm-dev/2020-December/147004.html).
>     Arthur looked into AMDGPU support for the NPN and points out that
>     [passes that depended on `TargetMachine::adjustPassManager` need to be
> tweaked to work with the NPN](
> http://lists.llvm.org/pipermail/llvm-dev/2020-December/147130.html).
> *  João Paulo L. de Carvalho asked about
>     [modeling address space casts in the Scalar Evolution analysis](
> http://lists.llvm.org/pipermail/llvm-dev/2020-November/146927.html).
>     This prevents simple SYCL loops from being vectorized. There are no
> replies as of writing.
> *  Nichols A. Romero proposed to add Fortran tests to the LLVM Test Suite.
>     [The tests will focus on language features, high-performance proxy
> programs, and OpenMP multi-threading and GPU offloading.](
> http://lists.llvm.org/pipermail/llvm-dev/2020-November/146873.html)
>     The response seems overwhelmingly positive so far.
>
> ### Commits
> *  (In-review) Ongoing work and discussion on
>     [Adding convergence control operand bundle and intrinsics](
> https://reviews.llvm.org/D85603) to LLVM IR.
> *  [Clang Offload Bundler gained AMDGPU code object V4 ABI documentation.](
> https://reviews.llvm.org/D92434)
> *  Various fixes to AMDGPU assembler diagnostics: [\[1\]](
> https://reviews.llvm.org/D92084),
>     [\[2\]](https://reviews.llvm.org/D92115), [\[3\]](
> https://reviews.llvm.org/D92654).
> *  (In-review) [Don't sink ptrtoint/inttoptr sequences into non-noop
> address space casts.](https://reviews.llvm.org/D92210)
>     This resolves an [illegal memory access with atomic shared memory
> JuliaGPU bug](https://github.com/JuliaGPU/CUDA.jl/issues/558).
> *  [CUDA/HIP hostness function overloading fixes.](
> https://reviews.llvm.org/D80450)
>     A new `-fgpu-exclude-wrong-side-overloads` Clang flag controls the
> related behavior.
>
> ## MLIR
>
> ### Discussions
>
> ### Commits
> *  [`gpu.allocate` and `gpu.deallocate` ops were added to runtime function
> calls.](https://reviews.llvm.org/D91698)
> *  The `GpuAsyncRegionPass` learned to
>     [move `gpu.wait` ops from `async.execute` regions to its dependencies](
> https://reviews.llvm.org/D90346).
>     This prevents unnecessary host synchronization.
>
> ## External Compilers
>
> Please submit pointers to your mailing lists, forums, or newsletters if you
> want your LLVM-
> or MLIR-based GPU compiler project to be covered in future LLVM GPU News
> issues.
>
> ### CUDA
>
> ### JuliaGPU
>
> ### LLPC
>
> ### Mesa
>
> ### SYCL
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev