{ lib
, stdenv
, fetchFromGitHub
, pkgsBuildBuild
, pkg-config
, cmake
, ninja
, git
, libxml2
, libxcrypt
, libedit
, libffi
, libpfm
, mpfr
, zlib
, ncurses
, doxygen
, sphinx
, which
, sysctl
, python3Packages
, buildDocs ? true
, buildMan ? true
, buildTests ? true
, llvmTargetsToBuild ? [ "NATIVE" ] # "NATIVE" resolves into x86 or aarch64 depending on stdenv
, llvmProjectsToBuild ? [ "llvm" "mlir" ]
}:

let
  llvmNativeTarget =
    if stdenv.hostPlatform.isx86_64 then "X86"
    else if stdenv.hostPlatform.isAarch64 then "AArch64"
    else throw "Currently unsupported LLVM platform '${stdenv.hostPlatform.config}'";

  inferNativeTarget = t: if t == "NATIVE" then llvmNativeTarget else t;
  llvmTargetsToBuild' = [ "AMDGPU" "NVPTX" ] ++ builtins.map inferNativeTarget llvmTargetsToBuild;

  # This LLVM version can't seem to find pygments/pyyaml,
  # but a later update will likely fix this (openai-triton-2.1.0)
  python =
    if buildTests
    then python3Packages.python.withPackages (p: with p; [ psutil pygments pyyaml ])
    else python3Packages.python;

  isNative = stdenv.hostPlatform == stdenv.buildPlatform;
in stdenv.mkDerivation (finalAttrs: {
  pname = "openai-triton-llvm";
  version = "17.0.0-c5dede880d17";

  outputs = [
    "out"
  ] ++ lib.optionals buildDocs [
    "doc"
  ] ++ lib.optionals buildMan [
    "man"
  ];

  # See https://github.com/openai/triton/blob/main/python/setup.py
  # and https://github.com/ptillet/triton-llvm-releases/releases
  src = fetchFromGitHub {
    owner = "llvm";
    repo = "llvm-project";
    rev = "c5dede880d175f7229c9b2923f4753e12702305d";
    hash = "sha256-v4r3+7XVFK+Dzxt/rErZNJ9REqFO3JmGN4X4vZ+77ew=";
  };

  nativeBuildInputs = [
    pkg-config
    cmake
    ninja
    git
    python
  ] ++ lib.optionals (buildDocs || buildMan) [
    doxygen
    sphinx
    python3Packages.recommonmark
  ];

  buildInputs = [
    libxml2
    libxcrypt
    libedit
    libffi
    libpfm
    mpfr
  ];

  propagatedBuildInputs = [
    zlib
    ncurses
  ];

  sourceRoot = "${finalAttrs.src.name}/llvm";

  cmakeFlags = [
    (lib.cmakeFeature "LLVM_TARGETS_TO_BUILD" (lib.concatStringsSep ";" llvmTargetsToBuild'))
    (lib.cmakeFeature "LLVM_ENABLE_PROJECTS" (lib.concatStringsSep ";" llvmProjectsToBuild))
    (lib.cmakeFeature "LLVM_HOST_TRIPLE" stdenv.hostPlatform.config)
    (lib.cmakeFeature "LLVM_DEFAULT_TARGET_TRIPLE" stdenv.hostPlatform.config)
    (lib.cmakeBool "LLVM_INSTALL_UTILS" true)
    (lib.cmakeBool "LLVM_INCLUDE_DOCS" (buildDocs || buildMan))
    (lib.cmakeBool "MLIR_INCLUDE_DOCS" (buildDocs || buildMan))
    (lib.cmakeBool "LLVM_BUILD_DOCS" (buildDocs || buildMan))
    # Way too slow, only uses one core
    # (lib.cmakeBool "LLVM_ENABLE_DOXYGEN" (buildDocs || buildMan))
    (lib.cmakeBool "LLVM_ENABLE_SPHINX" (buildDocs || buildMan))
    (lib.cmakeBool "SPHINX_OUTPUT_HTML" buildDocs)
    (lib.cmakeBool "SPHINX_OUTPUT_MAN" buildMan)
    (lib.cmakeBool "SPHINX_WARNINGS_AS_ERRORS" false)
    (lib.cmakeBool "LLVM_INCLUDE_TESTS" buildTests)
    (lib.cmakeBool "MLIR_INCLUDE_TESTS" buildTests)
    (lib.cmakeBool "LLVM_BUILD_TESTS" buildTests)
  # Cross compilation code taken/modified from LLVM 16 derivation
  ] ++ lib.optionals (!isNative) (let
    nativeToolchainFlags = let
      nativeCC = pkgsBuildBuild.targetPackages.stdenv.cc;
      nativeBintools = nativeCC.bintools.bintools;
    in [
      (lib.cmakeFeature "CMAKE_C_COMPILER" "${nativeCC}/bin/${nativeCC.targetPrefix}cc")
      (lib.cmakeFeature "CMAKE_CXX_COMPILER" "${nativeCC}/bin/${nativeCC.targetPrefix}c++")
      (lib.cmakeFeature "CMAKE_AR" "${nativeBintools}/bin/${nativeBintools.targetPrefix}ar")
      (lib.cmakeFeature "CMAKE_STRIP" "${nativeBintools}/bin/${nativeBintools.targetPrefix}strip")
      (lib.cmakeFeature "CMAKE_RANLIB" "${nativeBintools}/bin/${nativeBintools.targetPrefix}ranlib")
    ];

    # We need to repass the custom GNUInstallDirs values, otherwise CMake
    # will choose them for us, leading to wrong results in llvm-config-native
    nativeInstallFlags = [
      (lib.cmakeFeature "CMAKE_INSTALL_PREFIX" (placeholder "out"))
      (lib.cmakeFeature "CMAKE_INSTALL_BINDIR" "${placeholder "out"}/bin")
      (lib.cmakeFeature "CMAKE_INSTALL_INCLUDEDIR" "${placeholder "out"}/include")
      (lib.cmakeFeature "CMAKE_INSTALL_LIBDIR" "${placeholder "out"}/lib")
      (lib.cmakeFeature "CMAKE_INSTALL_LIBEXECDIR" "${placeholder "out"}/libexec")
    ];
  in [
    (lib.cmakeBool "CMAKE_CROSSCOMPILING" true)
    (lib.cmakeFeature "CROSS_TOOLCHAIN_FLAGS_NATIVE" (lib.concatStringsSep ";"
      (lib.concatLists [ nativeToolchainFlags nativeInstallFlags ])))
  ]);

  postPatch = ''
    # `CMake Error: cannot write to file "/build/source/llvm/build/lib/cmake/mlir/MLIRTargets.cmake": Permission denied`
    chmod +w -R ../mlir
    patchShebangs ../mlir/test/mlir-reduce

    # FileSystem permissions tests fail with various special bits
    rm test/tools/llvm-objcopy/ELF/mirror-permissions-unix.test
    rm unittests/Support/Path.cpp

    substituteInPlace unittests/Support/CMakeLists.txt \
      --replace "Path.cpp" ""
  '' + lib.optionalString stdenv.isAarch64 ''
    # Not sure why this fails
    rm test/tools/llvm-exegesis/AArch64/latency-by-opcode-name.s
  '';

  postInstall = lib.optionalString (!isNative) ''
    cp -a NATIVE/bin/llvm-config $out/bin/llvm-config-native
  '';

  doCheck = buildTests;

  nativeCheckInputs = [ which ]
    ++ lib.optionals stdenv.isDarwin [ sysctl ];

  checkTarget = "check-all";
  requiredSystemFeatures = [ "big-parallel" ];

  meta = with lib; {
    description = "Collection of modular and reusable compiler and toolchain technologies";
    homepage = "https://github.com/llvm/llvm-project";
    license = with licenses; [ ncsa ];
    maintainers = with maintainers; [ SomeoneSerge Madouura ];
    platforms = with platforms; aarch64 ++ x86;
  };
})