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Add support for WASM backend #2351

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bffc217
Use libffi-wasm when building for wasi32
hamishmack May 5, 2025
1c3ca40
Update dummy-ghc code
hamishmack May 6, 2025
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1 change: 1 addition & 0 deletions ci.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,7 @@
|| (system == "aarch64-darwin" && !builtins.elem compiler-nix-name ["ghc902" "ghc928" "ghc948" "ghc966" "ghc967" "ghc96720250227" "ghc982" "ghc983" "ghc984"])
)) {
inherit (lib.systems.examples) ghcjs;
inherit (lib.systems.examples) wasi32;
} // lib.optionalAttrs (nixpkgsName == "unstable"
&& (__match ".*llvm" compiler-nix-name == null)
&& ((system == "x86_64-linux" && !builtins.elem compiler-nix-name ["ghc902" "ghc928" "ghc966" "ghc967" "ghc96720250227"]) # Not sure why GHC 9.6.6 TH code now wants `log1pf`
Expand Down
69 changes: 57 additions & 12 deletions compiler/ghc/default.nix
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Expand Up @@ -21,7 +21,7 @@ let self =
libffi ? null

, # we don't need LLVM for x86, aarch64, or ghcjs
useLLVM ? with stdenv.targetPlatform; !(isx86 || isAarch64 || isGhcjs)
useLLVM ? with stdenv.targetPlatform; !(isx86 || isAarch64 || isGhcjs || isWasm)
, # LLVM is conceptually a run-time-only dependency, but for
# non-x86, we need LLVM to bootstrap later stages, so it becomes a
# build-time dependency too.
Expand Down Expand Up @@ -117,14 +117,45 @@ let
INTEGER_LIBRARY = ${if enableIntegerSimple then "integer-simple" else "integer-gmp"}
'';

libffi-wasm = buildPackages.runCommand "libffi-wasm" {
nativeBuildInputs = [
(buildPackages.haskell-nix.tool "ghc912" "libffi-wasm" {
src = buildPackages.haskell-nix.sources.libffi-wasm;
})
buildPackages.clang
targetPackages.buildPackages.clang
targetPackages.buildPackages.llvm
targetPackages.buildPackages.binaryen
];
outputs = ["dev" "out"];
NIX_NO_SELF_RPATH = true;
} ''
mkdir cbits
cp ${buildPackages.haskell-nix.sources.libffi-wasm}/cbits/* cbits/
libffi-wasm
wasm32-unknown-wasi-clang -Wall -Wextra -mcpu=mvp -Oz -DNDEBUG -Icbits -c cbits/ffi.c -o cbits/ffi.o
wasm32-unknown-wasi-clang -Wall -Wextra -mcpu=mvp -Oz -DNDEBUG -Icbits -c cbits/ffi_call.c -o cbits/ffi_call.o
wasm32-unknown-wasi-clang -Wall -Wextra -mcpu=mvp -Oz -DNDEBUG -Icbits -c cbits/ffi_closure.c -o cbits/ffi_closure.o

mkdir -p $dev/include
cp cbits/*.h $dev/include
mkdir -p $out/lib
llvm-ar -r $out/lib/libffi.a cbits/*.o

wasm32-unknown-wasi-clang -Wall -Wextra -mcpu=mvp -Oz -DNDEBUG -Icbits -fPIC -fvisibility=default -shared -Wl,--keep-section=target_features,--strip-debug cbits/*.c -o libffi.so
wasm-opt --low-memory-unused --converge --debuginfo --flatten --rereloop --gufa -O4 -Oz libffi.so -o $out/lib/libffi.so
'';

# TODO check if this possible fix for segfaults works or not.
targetLibffi =
# on native platforms targetPlatform.{libffi, gmp} do not exist; thus fall back
# to the non-targetPlatform version in those cases.
let targetLibffi = targetPackages.libffi or libffi; in
# we need to set `dontDisableStatic` for musl for libffi to work.
if stdenv.targetPlatform.isMusl
then targetLibffi.overrideAttrs (_old: { dontDisableStatic = true; })
then targetLibffi.overrideAttrs (_old: { dontDisableStatic = true; })
else if stdenv.targetPlatform.isWasm
then libffi-wasm
else targetLibffi;

targetGmp = targetPackages.gmp or gmp;
Expand Down Expand Up @@ -195,13 +226,14 @@ let
# `--with` flags for libraries needed for RTS linker
configureFlags = [
"--datadir=$doc/share/doc/ghc"
] ++ lib.optionals (!targetPlatform.isGhcjs && !targetPlatform.isAndroid) ["--with-curses-includes=${targetPackages.ncurses.dev}/include" "--with-curses-libraries=${targetPackages.ncurses.out}/lib"
] ++ lib.optionals (targetLibffi != null && !targetPlatform.isGhcjs) ["--with-system-libffi" "--with-ffi-includes=${targetLibffi.dev}/include" "--with-ffi-libraries=${targetLibffi.out}/lib"
] ++ lib.optionals (!enableIntegerSimple && !targetPlatform.isGhcjs) [
] ++ lib.optionals (!targetPlatform.isGhcjs && !targetPlatform.isWasm && !targetPlatform.isAndroid) ["--with-curses-includes=${targetPackages.ncurses.dev}/include" "--with-curses-libraries=${targetPackages.ncurses.out}/lib"
] ++ lib.optionals (targetLibffi != null && !targetPlatform.isGhcjs && !targetPlatform.isWasm) ["--with-system-libffi" "--with-ffi-includes=${targetLibffi.dev}/include" "--with-ffi-libraries=${targetLibffi.out}/lib"
] ++ lib.optionals (targetPlatform.isWasm) ["--with-system-libffi"
] ++ lib.optionals (!enableIntegerSimple && !targetPlatform.isGhcjs && !targetPlatform.isWasm) [
"--with-gmp-includes=${targetGmp.dev}/include" "--with-gmp-libraries=${targetGmp.out}/lib"
] ++ lib.optionals (targetPlatform == hostPlatform && hostPlatform.libc != "glibc" && !targetPlatform.isWindows) [
"--with-iconv-includes=${libiconv}/include" "--with-iconv-libraries=${libiconv}/lib"
] ++ lib.optionals (targetPlatform != hostPlatform && !targetPlatform.isGhcjs) [
] ++ lib.optionals (targetPlatform != hostPlatform && !targetPlatform.isGhcjs && !targetPlatform.isWasm) [
"--with-iconv-includes=${targetIconv}/include" "--with-iconv-libraries=${targetIconv}/lib"
] ++ lib.optionals (targetPlatform != hostPlatform) [
"--enable-bootstrap-with-devel-snapshot"
Expand Down Expand Up @@ -229,9 +261,9 @@ let
;

# Splicer will pull out correct variations
libDeps = platform: lib.optional (enableTerminfo && !targetPlatform.isGhcjs && !targetPlatform.isAndroid) [ targetPackages.ncurses targetPackages.ncurses.dev ]
libDeps = platform: lib.optional (enableTerminfo && !targetPlatform.isGhcjs && !targetPlatform.isWasm && !targetPlatform.isAndroid) [ targetPackages.ncurses targetPackages.ncurses.dev ]
++ lib.optional (!targetPlatform.isGhcjs) targetLibffi
++ lib.optional (!enableIntegerSimple && !targetPlatform.isGhcjs) gmp
++ lib.optional (!enableIntegerSimple && !targetPlatform.isGhcjs && !targetPlatform.isWasm) gmp
++ lib.optional (platform.libc != "glibc" && !targetPlatform.isWindows) libiconv
++ lib.optional (enableNUMA && platform.isLinux && !platform.isAarch32 && !platform.isAndroid) numactl
++ lib.optional enableDWARF (lib.getLib elfutils);
Expand Down Expand Up @@ -306,12 +338,12 @@ let
# For build flavours and flavour transformers
# see https://gitlab.haskell.org/ghc/ghc/blob/master/hadrian/doc/flavours.md
hadrianArgs = "--flavour=${
(if targetPlatform.isGhcjs then "quick" else "default")
(if targetPlatform.isGhcjs || targetPlatform.isWasm then "quick" else "default")
+ lib.optionalString (!enableShared) "+no_dynamic_ghc"
+ lib.optionalString useLLVM "+llvm"
+ lib.optionalString enableDWARF "+debug_info"
+ lib.optionalString ((enableNativeBignum && hadrianHasNativeBignumFlavour) || targetPlatform.isGhcjs) "+native_bignum"
+ lib.optionalString targetPlatform.isGhcjs "+no_profiled_libs"
+ lib.optionalString ((enableNativeBignum && hadrianHasNativeBignumFlavour) || targetPlatform.isGhcjs || targetPlatform.isWasm) "+native_bignum"
+ lib.optionalString (targetPlatform.isGhcjs || targetPlatform.isWasm) "+no_profiled_libs"
} --docs=no-sphinx -j --verbose"
# This is needed to prevent $GCC from emitting out of line atomics.
# Those would then result in __aarch64_ldadd1_sync and others being referenced, which
Expand Down Expand Up @@ -425,9 +457,22 @@ haskell-nix.haskellLib.makeCompilerDeps (stdenv.mkDerivation (rec {
export EM_CACHE=$(mktemp -d)
mv config.sub.ghcjs config.sub
'')
+ lib.optionalString (targetPlatform.isWasm) ''
export CC="${targetCC}/bin/${targetCC.targetPrefix}cc"
export CXX="${targetCC}/bin/${targetCC.targetPrefix}c++"
export LD="${buildPackages.llvmPackages.lld}/bin/wasm-ld"
export AS="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}as"
export AR="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ar"
export NM="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}nm"
export RANLIB="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ranlib"
export READELF="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}readelf"
export STRIP="${bintoolsFor.strip}/bin/${bintoolsFor.strip.targetPrefix}strip"
export NIX_CFLAGS_COMPILE_FOR_BUILD+=" -I${libffi.dev}/include -L${libffi.out}/lib"
export NIX_CFLAGS_COMPILE_FOR_TARGET+=" -I${targetLibffi.dev}/include -L${targetLibffi.out}/lib"
''
# GHC is a bit confused on its cross terminology, as these would normally be
# the *host* tools.
+ lib.optionalString (!targetPlatform.isGhcjs) (''
+ lib.optionalString (!targetPlatform.isGhcjs && !targetPlatform.isWasm) (''
export CC="${targetCC}/bin/${targetCC.targetPrefix}cc"
export CXX="${targetCC}/bin/${targetCC.targetPrefix}c++"
''
Expand Down
37 changes: 19 additions & 18 deletions flake.lock
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11 changes: 4 additions & 7 deletions flake.nix
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Expand Up @@ -49,13 +49,6 @@
url = "github:input-output-hk/cardano-shell";
flake = false;
};
"ghc-8.6.5-iohk" = {
type = "github";
owner = "input-output-hk";
repo = "ghc";
ref = "release/8.6.5-iohk";
flake = false;
};
hpc-coveralls = {
url = "github:sevanspowell/hpc-coveralls";
flake = false;
Expand All @@ -72,6 +65,10 @@
url = "github:stable-haskell/iserv-proxy?ref=iserv-syms";
flake = false;
};
libffi-wasm = {
url = "gitlab:haskell-wasm/libffi-wasm?host=gitlab.haskell.org";
flake = false;
};
};

outputs =
Expand Down
4 changes: 4 additions & 0 deletions lib/call-cabal-project-to-nix.nix
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Expand Up @@ -330,6 +330,8 @@ let
then "OSMinGW32"
else if pkgs.stdenv.targetPlatform.isGhcjs
then "OSGhcjs"
else if pkgs.stdenv.targetPlatform.isWasi
then "OSWasi"
else throw "Unknown target os ${pkgs.stdenv.targetPlatform.config}"
}")'
echo ',("target arch","${
Expand All @@ -345,6 +347,8 @@ let
then "ArchAArch32"
else if pkgs.stdenv.targetPlatform.isJavaScript
then "ArchJavaScript"
else if pkgs.stdenv.targetPlatform.isWasm
then "ArchWasm32"
else throw "Unknown target arch ${pkgs.stdenv.targetPlatform.config}"
}")'
echo ',("target platform string","${platformString pkgs.stdenv.targetPlatform}")'
Expand Down
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