Commit fb5a523d authored by Emily's avatar Emily
Browse files

haskell.compiler.ghc902Binary: bump LLVM by wrapping `opt(1)` 

Implement a wrapper script to translate the `opt(1)` arguments passed
by the GHC 9.0.2 binary distribution to the equivalent arguments
for the new LLVM pass manager passed by GHC ≥ 9.10 and our
soon‐to‐be‐patched compilers. This ensures that the bootstrap
of GHC 9.4 continues to work on AArch64.

On an earlier version of this change, I built `haskell.compiler.ghc948`
on both `aarch64-linux` and `aarch64-darwin`, and
`haskell.compiler.ghc924` on `aarch64-linux` only (it is already
broken on Darwin). I confirmed that we get functionally identical
store outputs before and after this change, modulo self‐references:

    $ cp -a result-before/ before
    $ cp -a result-after/ after
    $ chmod -R +w before after
    $ LANG=C find before -type f -exec \
        remove-references-to \
        -t $(readlink result-before) \
        -t $(readlink result-before-doc) \
        '{}' ';'
    $ LANG=C find after -type f -exec \
        remove-references-to \
        -t $(readlink result-after) \
        -t $(readlink result-after-doc) \
        '{}' ';'
    # Darwin only: normalize build user UIDs in the archive files…
    $ LANG=C find before -name '*.a' -exec \
        sed -i 's/ 360 / 351 /g' '{}' ';'
    $ diff -r before after
    # Linux only: the `package.cache` files differ, presumably due to
    # an unrelated reproducibility issue.

Therefore, bumping this LLVM dependency did not affect the end result
of the bootstrap for the only compilers it is used for.
parent 1bda5b19

pkgs/development/compilers/ghc/9.0.2-binary.nix

+15 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
  numactl,

  libffi,

  llvmPackages,

  replaceVarsWith,

  coreutils,

  targetPackages,
@@ -214,6 +215,20 @@ let 
    coreutils # for cat

  ]

  ++ lib.optionals useLLVM [

    # Allow the use of newer LLVM versions; see the script for details.

    (replaceVarsWith {

      name = "subopt";

      src = ./subopt.bash;

      dir = "bin";

      isExecutable = true;

      preBuild = ''

        name=opt

      '';

      replacements = {

        inherit (stdenv) shell;

        opt = lib.getExe' llvmPackages.llvm "opt";

      };

    })

    (lib.getBin llvmPackages.llvm)

  ]

  # On darwin, we need unwrapped bintools as well (for otool)

pkgs/development/compilers/ghc/subopt.bash

0 → 100644
+80 −0
Original line number Diff line number Diff line 
#!@shell@



# This script wraps the LLVM `opt(1)` executable and maps the options

# passed by old versions of GHC to the equivalents passed by newer

# versions that support recent versions of LLVM.

#

# It achieves the same effect as the following GHC change externally:

# <https://gitlab.haskell.org/ghc/ghc/-/merge_requests/8999>.

#

# This is used solely for bootstrapping newer GHCs from the GHC 9.0.2

# binary on AArch64, as that is the only architecture supported by that

# binary distribution that requires LLVM, and our later binary packages

# all use the native code generator for all supported platforms.

#

# No attempt is made to support custom LLVM optimization flags, or the

# undocumented flag to disable TBAA, or avoid

# <https://gitlab.haskell.org/ghc/ghc/-/issues/23870>, as these are not

# required to bootstrap GHC and at worst will produce an error message.

#

# It is called `subopt` to reflect the fact that it uses `opt(1)` as a

# subprocess, and the fact that the GHC build system situation

# requiring this hack is suboptimal.



set -e



expect() {

  if [[ $1 != $2 ]]; then

    printf >&2 'subopt: got %q; expected %q\n' "$1" "$2"

    return 2

  fi

}



if [[ $NIX_DEBUG -ge 1 ]]; then

  printf >&2 'subopt: before:'

  printf >&2 ' %q' "$@"

  printf >&2 '\n'

fi



args=()



while [[ $# -gt 0 ]]; do

  case "$1" in

    -enable-new-pm=0)

      shift 1

      ;;

    -mem2reg)

      expect "$2" -globalopt

      expect "$3" -lower-expect

      expect "$4" -enable-tbaa

      expect "$5" -tbaa

      args+=('-passes=function(require<tbaa>),function(mem2reg),globalopt,function(lower-expect)')

      shift 5

      ;;

    -O1)

      expect "$2" -globalopt

      expect "$3" -enable-tbaa

      expect "$4" -tbaa

      args+=('-passes=default<O1>')

      shift 4

      ;;

    -O2)

      expect "$2" -enable-tbaa

      expect "$3" -tbaa

      args+=('-passes=default<O2>')

      shift 3

      ;;

    *)

      args+=("$1")

      shift 1

      ;;

  esac

done



if [[ $NIX_DEBUG -ge 1 ]]; then

  printf >&2 'subopt: after:'

  printf >&2 ' %q' "${args[@]}"

  printf >&2 '\n'

fi



exec @opt@ "${args[@]}"

pkgs/top-level/haskell-packages.nix

+2 −1
Original line number Diff line number Diff line
@@ -70,8 +70,9 @@ in 
      bb = pkgsBuildBuild.haskell;

    in

    {

      # Required to bootstrap 9.4.8.

      ghc902Binary = callPackage ../development/compilers/ghc/9.0.2-binary.nix {

        llvmPackages = pkgs.llvmPackages_12;

        llvmPackages = pkgs.llvmPackages_20;

      };



      ghc924Binary = callPackage ../development/compilers/ghc/9.2.4-binary.nix { };