[llvm-dev] RISC-V LLVM status update

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Wed Sep 6 07:33:39 PDT 2017

On 21 August 2017 at 11:06, Alex Bradbury <asb at asbradbury.org> wrote:
> As you will have seen from previous postings, I've been working on upstream
> LLVM support for the RISC-V instruction set architecture. The initial RFC
> <http://lists.llvm.org/pipermail/llvm-dev/2016-August/103748.html>
> provides a good overview of my approach. Thanks to funding from a third party,
> I've recently been able to return to this effort as my main focus. Now feels
> like a good time to give an update on where the RISCV backend is at, and how
> you can help.
> ## Current status
> * A full, regularly rebased patchset can be found here
> <https://github.com/lowRISC/riscv-llvm>.
> * 16 of these patches have been put up for review so far. 7 have been
> committed, and 8 are awaiting review.
> * The vast majority of the GCC torture suite compiles and runs at O0,
> targeting RV32I. 1315 out of 1352 compile and run (32 compile-time failures, 5
> run-time failures).
> * I intend to keep <http://www.lowrisc.org/llvm/status> updated with status,
> test results etc.
> ## Next steps and getting involved
> The plan has always been to work from the MC-layer upwards towards reliable
> RV32I codegen. This then provides a stable 'core' of the backend where it's
> easy for further development work to be parallelised, and for others to make
> contributions. I think we're now at that point.
> I would really like to avoid setting up a new 'downstream', and to use this
> opportunity to pull in new people to upstream LLVM development.  However
> collaboration is made rather difficult for now due to the large gap between
> the patches that have been reviewed and committed upstream vs the complete
> patchset. If you would like to help, reviewing the remaining patches
> <https://reviews.llvm.org/differential/?authors=asb&order=updated> is an
> incredibly valuable way to do so. If you would like to be listed as a reviewer
> for future patches, just let me know (and feel free to add yourself for
> existing patches).

I'll be continuing to do all that I can get the patchset reviewed for
upstream merging, but given review activity seems to have slowed to a
halt again I've gone ahead and set up a repository for downstream
collaboration, to accept pull requests from others etc. See the README
at <https://github.com/lowRISC/riscv-llvm-integration> for more
information. The intent is that this is a temporary measure, to allow
productive collaboration while upstream RISC-V support remains blocked
on lack of reviewers.



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