Commit a2b66241 authored by sternenseemann's avatar sternenseemann
Browse files

{forceLlvmCodegenBackend,ghcWithPackages}: update clang -fllvm logic 

- The LLVM backend always needs an LLVM specific assembler, i.e. clang
  that ideally matches the version of LLVM actually used for codegen.

- The LLVM backend on Darwin requires some version of clang to be
  available. In light of LLVMAS, using a matching version seems to be
  best though this does risk messing with clang used for compiling C
  in the derivation.

  This mess can be avoided by compiling GHC with useLLVM = true which
  sets absolute paths in GHC's settings file. Due to closure size
  constraints, we can't really do that if NCG is available.
parent a9e965e0

pkgs/development/haskell-modules/make-package-set.nix

+8 −1
Original line number Diff line number Diff line
@@ -734,6 +734,13 @@ package-set { inherit pkgs lib callPackage; } self 
  */

  forceLlvmCodegenBackend = overrideCabal (drv: {

    configureFlags = drv.configureFlags or [ ] ++ [ "--ghc-option=-fllvm" ];

    buildTools = drv.buildTools or [ ] ++ [ self.ghc.llvmPackages.llvm ];

    buildTools =

      drv.buildTools or [ ]

      ++ [ self.ghc.llvmPackages.llvm ]

      # GHC >= 9.10 needs LLVM specific assembler, i.e. clang

      # On Darwin clang is always required

      ++ lib.optionals (lib.versionAtLeast self.ghc.version "9.10" || stdenv.hostPlatform.isDarwin) [

        self.ghc.llvmPackages.clang

      ];

  });

}

pkgs/development/haskell-modules/with-packages-wrapper.nix

+6 −2
Original line number Diff line number Diff line
@@ -68,10 +68,14 @@ let 
    )

  );

  hasLibraries = lib.any (x: x.isHaskellLibrary) paths;

  # CLang is needed on Darwin for -fllvm to work:

  # Clang is needed on Darwin for -fllvm to work.

  # GHC >= 9.10 needs an LLVM specific assembler which we use clang for.

  # https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/codegens.html#llvm-code-generator-fllvm

  llvm = lib.makeBinPath (

    [ ghc.llvmPackages.llvm ] ++ lib.optional stdenv.targetPlatform.isDarwin ghc.llvmPackages.clang

    [ ghc.llvmPackages.llvm ]

    ++ lib.optionals (lib.versionAtLeast ghc.version "9.10" || stdenv.targetPlatform.isDarwin) [

      ghc.llvmPackages.clang

    ]

  );

in