- ghc-devs - Haskell.org

can't move to latest version of llvm on ghc 9.12.2
by George Colpitts 26 May '25

26 May '25

llvm 20 is out but unlike in earlier versions of ghc moving to it means you can no longer use llvm: compiling: ghc -fllvm hello.hs Loaded package environment from /Users/avie/.ghc/aarch64-darwin-9.12.2/environments/default [1 of 2] Compiling Main ( hello.hs, hello.o ) <no location info>: error: [GHC-66599] GHC was not configured with a supported LLVM toolchain Make sure you have installed LLVM between [13 and 20) and reinstall GHC to make -fllvm work from configure: configure: We only support llvm 13 upto 20 (non-inclusive) (found 20.1.1). Can we move to llvm 20 on HEAD and can we revert to the old behavior on ghc 9.12.3? Should I file an ER? Thanks

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GitLab account request
by Florian Ragwitz 17 May '25

17 May '25

Hi, I'd like for the gitlab.haskell.org account request for the account "rafl" to be approved, so that I can participate in issue discussions and submit changes for review, please. Thanks!

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GitLab Account creation request
by Iris 14 May '25

14 May '25

Dear GHC developers, I am interested in contributing to the GHC project and would like to have an account(iris) on the GitLab instance. Best regards, Iris

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LINE and COLUMN pragmas
by Alan & Kim Zimmerman 13 May '25

13 May '25

I recently discovered the `UsePosPragsBit` in the lexer, which can allow emitting the LINE and COLUMN pragmas as tokens instead of processing them directly in the Lexer, updating the position. When exact printing, this behaviour is not desirable. So I am putting together an MR to parse them if they appear, so they do not cause a parser crash, and they can then be exact printed. Question: Where should these pragmas appear in HsDecl Options are - TTG, XXHsDecl - A new HsDecl constructor, with all its concomitant matching everywhere - tuck it in elsewhere, e.g. in `AnnDecl` (or `XXAnnDecl`). Alan

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GHC 9.10.2 is now available
by Zubin Duggal 03 May '25

03 May '25

The GHC developers are very pleased to announce the availability of the release candidate for GHC 9.10.2. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.2 is a bug-fix release fixing over 50 issues of a variety of severities and scopes, including: * Significantly improved performance when dynamically loading Haskell symbols (#23415). * Fixing a bug where the simplifier sometimes destroyed join points during float out, which could impact performance (#24768). * Reduced memory fragmentation in the non-moving GC's segment allocator, improving resident set size by up to 26% for some applications (#24150). * Added new flags to control speculative evaluation (-fspec-eval and -fspec-eval-dictfun) to work around performance regressions (#25606). * Fixed several platform-specific issues, including segfaults with FFI on PowerPC (#23034) and improved code generation for AArch64 with multiway branches now using jump tables (#19912) * And many more! A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. Cheers, Zubin [release notes]: https://downloads.haskell.org/~ghc/9.10.2/docs/users_guide/9.10.2-notes.html [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.2 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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Marge
by Simon Peyton Jones 29 Apr '25

29 Apr '25

Colleagues Marge has failed to pick up !14242 for nearly 24 hrs. Is something stuck? Thanks Simon

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Questions regarding the RISCV native codegen & performance
by Daniel Trujillo Viedma 20 Apr '25

20 Apr '25

Hello, ghc-devs! My name is Daniel Trujillo, I'm a Haskell enthusiast from Spain and I'm trying to make my Master's thesis about accelerating Haskell programs with a custom ISA extension. Right now, my focus is in executing software written in Haskell within QEMU in order to get traces that tells me, basically, how many times each block (not exactly basic blocks, but sort of) of assembly code has been executed, with the hope of finding some patterns of RISCV instructions that I could implement together into 1 instruction. As you can see, my method is a bit crude, and I was wondering if the people involved with any of the different internal representations (STG, Cmm...) and/or native code generators (particularly RISCV) could provide me hints about assembly instructions that would have made the work easier, by removing the need of "massaging" the Cmm code to make CodeGen easier, or the need of particular optimizations, or in general, dirty tricks because of lacking of proper support of the standard RISCV ISA. And of course, I would also appreciate very much other hints from people involved in general performance (as oppossed to, for example, libraries for SIMD and parallel execution, or Haskell wrappers to lower-level code for performance reasons). P.D. I'm sorry if I broke any netiquette rule, but I'm very new to the email list, and haven't received yet any email from it. Looking forward to hear from you! Cheers, Dani.

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GHC 9.10.2-rc1 is now available
by Ben Gamari 19 Apr '25

19 Apr '25

The GHC developers are very pleased to announce the availability of the release candidate for GHC 9.10.2. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.2 is a bug-fix release fixing over 50 issues of a variety of severities and scopes. A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 1 May 2025. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. Cheers, - Ben [release notes]: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.10/docs/users_guide/9.10.2-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.2-rc1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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GSoC 2025 proposal : Documenting and Improving Cmm
by Diego Antonio Rosario Palomino 17 Apr '25

17 Apr '25

Hi all, I've posted a thread on Discourse outlining my GSoC 2025 proposal, which focuses on documenting and improving GHC's Cmm backend. It covers two possible directions (LLVM and SSA), along with some refinements I've been exploring. You can find the full details here: 👉 https://discourse.haskell.org/t/gsoc-2025-documenting-and-improving-cmm/118… Feedback is very welcome! Best regards, Diego Antonio Rosario Palomino

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GitLab maintenance this evening
by Ben Gamari 15 Apr '25

15 Apr '25

Hello all, Tonight GitLab will be down for maintenance between 17:00 EDT and 18:00 EDT as part of the on-going infrastructure migration. Cheers, - Ben

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