Commit a9e965e0 authored by sternenseemann's avatar sternenseemann
Browse files

haskell.compiler.ghc91{0,2}: provide LLVM compatible assembler 

If we don't explicitly pass something as LLVMAS, GHC >= 9.10 will try to
invoke "clang" at runtime which fails.

Upstream change: https://gitlab.haskell.org/ghc/ghc/-/merge_requests/12005

I've tested pkgsCross.armv7l-hf-multiplatform.buildPackages.haskell.compiler.ghc9102
which was reported to be failing here:
https://github.com/NixOS/nixpkgs/pull/440271#issuecomment-3262885486
parent cdb8e81a

pkgs/development/compilers/ghc/common-hadrian.nix

+13 −0
Original line number Diff line number Diff line
@@ -536,6 +536,13 @@ stdenv.mkDerivation ( 
      export LLC="${getToolExe buildTargetLlvmPackages.llvm "llc"}"

      export OPT="${getToolExe buildTargetLlvmPackages.llvm "opt"}"

    ''

    # LLVMAS should be a "specific LLVM compatible assembler" which needs to understand

    # assembly produced by LLVM. The easiest way to be sure is to use clang from the same

    # version as llc and opt. Note that the naming chosen by GHC is misleading, clang can

    # be used as an assembler, llvm-as converts IR into machine code.

    + lib.optionalString (useLLVM && lib.versionAtLeast version "9.10") ''

      export LLVMAS="${getToolExe buildTargetLlvmPackages.clang "clang"}"

    ''

    + lib.optionalString (useLLVM && stdenv.targetPlatform.isDarwin) ''

      # LLVM backend on Darwin needs clang: https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/codegens.html#llvm-code-generator-fllvm

      # The executable we specify via $CLANG is used as an assembler (exclusively, it seems, but this isn't
@@ -544,6 +551,7 @@ stdenv.mkDerivation ( 
      # the assembly it is given, we need to make sure that it matches the LLVM version of $CC if possible.

      # It is unclear (at the time of writing 2024-09-01)  whether $CC should match the LLVM version we use

      # for llc and opt which would require using a custom darwin stdenv for targetCC.

      # 2025-09-06: The existence of LLVMAS suggests that matching $CC is fine (correct?) here.

      export CLANG="${

        if targetCC.isClang then

          toolPath "clang" targetCC
@@ -832,6 +840,11 @@ stdenv.mkDerivation ( 
        "LLVM llc command" "${getToolExe llvmPackages.llvm "llc"}" \

        "LLVM opt command" "${getToolExe llvmPackages.llvm "opt"}"

    ''

    # See comment for LLVMAS in preConfigure

    + lib.optionalString (useLLVM && lib.versionAtLeast version "9.10") ''

      ghc-settings-edit "$settingsFile" \

        "LLVM llvm-as command" "${getToolExe llvmPackages.clang "clang"}"

    ''

    + lib.optionalString (useLLVM && stdenv.targetPlatform.isDarwin) ''

      ghc-settings-edit "$settingsFile" \

        "LLVM clang command" "${