Add Javascript backend

Add JS backend adapted from the GHCJS project by Luite Stegeman.

Some features haven't been ported or implemented yet. Tests for these
features have been disabled with an associated gitlab ticket.

Bump array submodule

Work funded by IOG.

Co-authored-by: Jeffrey Young <jeffrey.young@iohk.io>
Co-authored-by: Luite Stegeman <stegeman@gmail.com>
Co-authored-by: Josh Meredith <joshmeredith2008@gmail.com>

3 files changed, 194 insertions, 27 deletions

diff --git a/.gitlab/ci.sh b/.gitlab/ci.sh
index 217440bbaf..b840500aa4 100755
--- a/.gitlab/ci.sh
+++ b/.gitlab/ci.sh
@@ -65,6 +65,7 @@ Environment variables affecting both build systems:
                     "decreases", or "all")
   HERMETIC          Take measures to avoid looking at anything in \$HOME
   CONFIGURE_ARGS    Arguments passed to configure script.
+  CONFIGURE_WRAPPER Wrapper for the configure script (e.g. Emscripten's emconfigure).
   ENABLE_NUMA       Whether to enable numa support for the build (disabled by default)
   INSTALL_CONFIGURE_ARGS
                     Arguments passed to the binary distribution configure script
@@ -249,6 +250,11 @@ function setup() {
       cp -Rf "$CABAL_CACHE"/* "$CABAL_DIR"
   fi
 
+  case "${CONFIGURE_WRAPPER:-}" in
+    emconfigure) time_it "setup" setup_emscripten ;;
+    *) ;;
+  esac
+
   case $toolchain_source in
     extracted) time_it "setup" setup_toolchain ;;
     *) ;;
@@ -365,6 +371,14 @@ function setup_toolchain() {
   $cabal_install alex --constraint="alex>=$MIN_ALEX_VERSION"
 }
 
+function setup_emscripten() {
+  git clone https://github.com/emscripten-core/emsdk.git
+  cd emsdk
+  ./emsdk install latest
+  ./emsdk activate latest
+  cd ..
+}
+
 function cleanup_submodules() {
   start_section "clean submodules"
   if [ -d .git ]; then
@@ -402,6 +416,11 @@ EOF
 }
 
 function configure() {
+  case "${CONFIGURE_WRAPPER:-}" in
+    emconfigure) source emsdk/emsdk_env.sh ;;
+    *) ;;
+  esac
+
   if [[ -z "${NO_BOOT:-}" ]]; then
     start_section "booting"
     run python3 boot
@@ -421,7 +440,7 @@ function configure() {
   start_section "configuring"
   # See https://stackoverflow.com/questions/7577052 for a rationale for the
   # args[@] symbol-soup below.
-  run ./configure \
+  run ${CONFIGURE_WRAPPER:-} ./configure \
     --enable-tarballs-autodownload \
     "${args[@]+"${args[@]}"}" \
     GHC="$GHC" \
@@ -528,6 +547,11 @@ function make_install_destdir() {
 
 # install the binary distribution in directory $1 to $2.
 function install_bindist() {
+  case "${CONFIGURE_WRAPPER:-}" in
+    emconfigure) source emsdk/emsdk_env.sh ;;
+    *) ;;
+  esac
+
   local bindist="$1"
   local instdir="$2"
   pushd "$bindist"
@@ -545,7 +569,7 @@ function install_bindist() {
           args+=( "--target=$CROSS_TARGET" "--host=$CROSS_TARGET" )
       fi
 
-      run ./configure \
+      run ${CONFIGURE_WRAPPER:-} ./configure \
           --prefix="$instdir" \
           "${args[@]+"${args[@]}"}"
       make_install_destdir "$TOP"/destdir "$instdir"
@@ -575,19 +599,17 @@ function test_hadrian() {
   fi
 
 
-  if [ -n "${CROSS_TARGET:-}" ]; then
-    if [ -n "${CROSS_EMULATOR:-}" ]; then
-      local instdir="$TOP/_build/install"
-      local test_compiler="$instdir/bin/${cross_prefix}ghc$exe"
-      install_bindist _build/bindist/ghc-*/ "$instdir"
-      echo 'main = putStrLn "hello world"' > expected
-      run "$test_compiler" -package ghc "$TOP/.gitlab/hello.hs" -o hello
-      $CROSS_EMULATOR ./hello > actual
-      run diff expected actual
-    else
-      info "Cannot test cross-compiled build without CROSS_EMULATOR being set."
-      return
-    fi
+  if [[ "${CROSS_EMULATOR:-}" == "NOT_SET" ]]; then
+    info "Cannot test cross-compiled build without CROSS_EMULATOR being set."
+    return
+  elif [ -n "${CROSS_TARGET:-}" ]; then
+    local instdir="$TOP/_build/install"
+    local test_compiler="$instdir/bin/${cross_prefix}ghc$exe"
+    install_bindist _build/bindist/ghc-*/ "$instdir"
+    echo 'main = putStrLn "hello world"' > expected
+    run "$test_compiler" -package ghc "$TOP/.gitlab/hello.hs" -o hello
+    ${CROSS_EMULATOR:-} ./hello > actual
+    run diff expected actual
   elif [[ -n "${REINSTALL_GHC:-}" ]]; then
     run_hadrian \
       test \
@@ -598,10 +620,11 @@ function test_hadrian() {
       "runtest.opts+=${RUNTEST_ARGS:-}" || fail "hadrian cabal-install test"
   else
     local instdir="$TOP/_build/install"
-    local test_compiler="$instdir/bin/ghc$exe"
+    local test_compiler="$instdir/bin/${cross_prefix}ghc$exe"
     install_bindist _build/bindist/ghc-*/ "$instdir"
 
-    if [[ "${WINDOWS_HOST}" == "no" ]]; then
+    if [[ "${WINDOWS_HOST}" == "no" ]] && [ -z "${CROSS_TARGET:-}" ]
+    then
       run_hadrian \
         test \
         --test-root-dirs=testsuite/tests/stage1 \
@@ -610,10 +633,14 @@ function test_hadrian() {
       info "STAGE1_TEST=$?"
     fi
 
-    # Ensure the resulting compiler has the correct bignum-flavour
-    test_compiler_backend=$(${test_compiler} -e "GHC.Num.Backend.backendName")
-    if [ $test_compiler_backend != "\"$BIGNUM_BACKEND\"" ]; then
-      fail "Test compiler has a different BIGNUM_BACKEND ($test_compiler_backend) thean requested ($BIGNUM_BACKEND)"
+    # Ensure the resulting compiler has the correct bignum-flavour,
+    # except for cross-compilers as they may not support the interpreter
+    if [ -z "${CROSS_TARGET:-}" ]
+    then
+      test_compiler_backend=$(${test_compiler} -e "GHC.Num.Backend.backendName")
+      if [ $test_compiler_backend != "\"$BIGNUM_BACKEND\"" ]; then
+        fail "Test compiler has a different BIGNUM_BACKEND ($test_compiler_backend) thean requested ($BIGNUM_BACKEND)"
+      fi
     fi
 
     # If we are doing a release job, check the compiler can build a profiled executable
diff --git a/.gitlab/gen_ci.hs b/.gitlab/gen_ci.hs
index db338b88d4..bf2ad41025 100755
--- a/.gitlab/gen_ci.hs
+++ b/.gitlab/gen_ci.hs
@@ -109,6 +109,11 @@ bignumString :: BignumBackend -> String
 bignumString Gmp = "gmp"
 bignumString Native = "native"
 
+data CrossEmulator
+  = NoEmulator
+  | NoEmulatorNeeded
+  | Emulator String
+
 -- | A BuildConfig records all the options which can be modified to affect the
 -- bindists produced by the compiler.
 data BuildConfig
@@ -120,7 +125,8 @@ data BuildConfig
                 , withAssertions :: Bool
                 , withNuma       :: Bool
                 , crossTarget    :: Maybe String
-                , crossEmulator  :: Maybe String
+                , crossEmulator  :: CrossEmulator
+                , configureWrapper :: Maybe String
                 , fullyStatic    :: Bool
                 , tablesNextToCode :: Bool
                 , threadSanitiser :: Bool
@@ -163,7 +169,8 @@ vanilla = BuildConfig
   , withAssertions = False
   , withNuma = False
   , crossTarget = Nothing
-  , crossEmulator = Nothing
+  , crossEmulator = NoEmulator
+  , configureWrapper = Nothing
   , fullyStatic = False
   , tablesNextToCode = True
   , threadSanitiser = False
@@ -195,11 +202,13 @@ staticNativeInt :: BuildConfig
 staticNativeInt = static { bignumBackend = Native }
 
 crossConfig :: String       -- ^ target triple
-            -> Maybe String -- ^ emulator for testing
+            -> CrossEmulator -- ^ emulator for testing
+            -> Maybe String -- ^ Configure wrapper
             -> BuildConfig
-crossConfig triple emulator =
+crossConfig triple emulator configure_wrapper =
     vanilla { crossTarget = Just triple
             , crossEmulator = emulator
+            , configureWrapper = configure_wrapper
             }
 
 llvm :: BuildConfig
@@ -636,8 +645,14 @@ job arch opsys buildConfig = (jobName, Job {..})
       , "BUILD_FLAVOUR" =: flavourString jobFlavour
       , "BIGNUM_BACKEND" =: bignumString (bignumBackend buildConfig)
       , "CONFIGURE_ARGS" =: configureArgsStr buildConfig
+      , maybe mempty ("CONFIGURE_WRAPPER" =:) (configureWrapper buildConfig)
       , maybe mempty ("CROSS_TARGET" =:) (crossTarget buildConfig)
-      , maybe mempty ("CROSS_EMULATOR" =:) (crossEmulator buildConfig)
+      , case crossEmulator buildConfig of
+          NoEmulator       -> case crossTarget buildConfig of
+            Nothing -> mempty
+            Just _  -> "CROSS_EMULATOR" =: "NOT_SET" -- we need an emulator but it isn't set. Won't run the testsuite
+          Emulator s       -> "CROSS_EMULATOR" =: s
+          NoEmulatorNeeded -> mempty
       , if withNuma buildConfig then "ENABLE_NUMA" =: "1" else mempty
       ]
 
@@ -813,7 +828,11 @@ jobs = Map.fromList $ concatMap flattenJobGroup $
      , standardBuilds I386 (Linux Debian9)
      , allowFailureGroup (standardBuildsWithConfig Amd64 (Linux Alpine) static)
      , disableValidate (allowFailureGroup (standardBuildsWithConfig Amd64 (Linux Alpine) staticNativeInt))
-     , validateBuilds Amd64 (Linux Debian11) (crossConfig "aarch64-linux-gnu" (Just "qemu-aarch64 -L /usr/aarch64-linux-gnu"))
+     , validateBuilds Amd64 (Linux Debian11) (crossConfig "aarch64-linux-gnu" (Emulator "qemu-aarch64 -L /usr/aarch64-linux-gnu") Nothing)
+     , validateBuilds Amd64 (Linux Debian11) (crossConfig "js-unknown-ghcjs" NoEmulatorNeeded (Just "emconfigure")
+        )
+        { bignumBackend = Native
+        }
      ]
 
   where
diff --git a/.gitlab/jobs.yaml b/.gitlab/jobs.yaml
index 07e91da267..fafb8c9357 100644
--- a/.gitlab/jobs.yaml
+++ b/.gitlab/jobs.yaml
@@ -1328,6 +1328,67 @@
       "XZ_OPT": "-9"
     }
   },
+  "nightly-x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate": {
+    "after_script": [
+      ".gitlab/ci.sh save_cache",
+      ".gitlab/ci.sh clean",
+      "cat ci_timings"
+    ],
+    "allow_failure": false,
+    "artifacts": {
+      "expire_in": "8 weeks",
+      "paths": [
+        "ghc-x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate.tar.xz",
+        "junit.xml"
+      ],
+      "reports": {
+        "junit": "junit.xml"
+      },
+      "when": "always"
+    },
+    "cache": {
+      "key": "x86_64-linux-deb11-$CACHE_REV",
+      "paths": [
+        "cabal-cache",
+        "toolchain"
+      ]
+    },
+    "dependencies": [],
+    "image": "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb11:$DOCKER_REV",
+    "needs": [
+      {
+        "artifacts": false,
+        "job": "hadrian-ghc-in-ghci"
+      }
+    ],
+    "rules": [
+      {
+        "if": "($CI_MERGE_REQUEST_LABELS !~ /.*fast-ci.*/) && ($RELEASE_JOB != \"yes\") && ($NIGHTLY) && (\"true\" == \"true\") && (\"true\" == \"true\") && (\"true\" == \"true\") && (\"true\" == \"true\")",
+        "when": "on_success"
+      }
+    ],
+    "script": [
+      "sudo chown ghc:ghc -R .",
+      ".gitlab/ci.sh setup",
+      ".gitlab/ci.sh configure",
+      ".gitlab/ci.sh build_hadrian",
+      ".gitlab/ci.sh test_hadrian"
+    ],
+    "stage": "full-build",
+    "tags": [
+      "x86_64-linux"
+    ],
+    "variables": {
+      "BIGNUM_BACKEND": "native",
+      "BIN_DIST_NAME": "ghc-x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate",
+      "BUILD_FLAVOUR": "validate",
+      "CONFIGURE_ARGS": "--with-intree-gmp",
+      "CONFIGURE_WRAPPER": "emconfigure",
+      "CROSS_TARGET": "js-unknown-ghcjs",
+      "TEST_ENV": "x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate",
+      "XZ_OPT": "-9"
+    }
+  },
   "nightly-x86_64-linux-deb11-validate": {
     "after_script": [
       ".gitlab/ci.sh save_cache",
@@ -3810,6 +3871,66 @@
       "TEST_ENV": "x86_64-linux-deb11-cross_aarch64-linux-gnu-validate"
     }
   },
+  "x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate": {
+    "after_script": [
+      ".gitlab/ci.sh save_cache",
+      ".gitlab/ci.sh clean",
+      "cat ci_timings"
+    ],
+    "allow_failure": false,
+    "artifacts": {
+      "expire_in": "2 weeks",
+      "paths": [
+        "ghc-x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate.tar.xz",
+        "junit.xml"
+      ],
+      "reports": {
+        "junit": "junit.xml"
+      },
+      "when": "always"
+    },
+    "cache": {
+      "key": "x86_64-linux-deb11-$CACHE_REV",
+      "paths": [
+        "cabal-cache",
+        "toolchain"
+      ]
+    },
+    "dependencies": [],
+    "image": "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb11:$DOCKER_REV",
+    "needs": [
+      {
+        "artifacts": false,
+        "job": "hadrian-ghc-in-ghci"
+      }
+    ],
+    "rules": [
+      {
+        "if": "($CI_MERGE_REQUEST_LABELS !~ /.*fast-ci.*/) && ($RELEASE_JOB != \"yes\") && ($NIGHTLY == null) && (\"true\" == \"true\") && (\"true\" == \"true\") && (\"true\" == \"true\") && (\"true\" == \"true\")",
+        "when": "on_success"
+      }
+    ],
+    "script": [
+      "sudo chown ghc:ghc -R .",
+      ".gitlab/ci.sh setup",
+      ".gitlab/ci.sh configure",
+      ".gitlab/ci.sh build_hadrian",
+      ".gitlab/ci.sh test_hadrian"
+    ],
+    "stage": "full-build",
+    "tags": [
+      "x86_64-linux"
+    ],
+    "variables": {
+      "BIGNUM_BACKEND": "native",
+      "BIN_DIST_NAME": "ghc-x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate",
+      "BUILD_FLAVOUR": "validate",
+      "CONFIGURE_ARGS": "--with-intree-gmp",
+      "CONFIGURE_WRAPPER": "emconfigure",
+      "CROSS_TARGET": "js-unknown-ghcjs",
+      "TEST_ENV": "x86_64-linux-deb11-int_native-cross_js-unknown-ghcjs-validate"
+    }
+  },
   "x86_64-linux-deb11-validate": {
     "after_script": [
       ".gitlab/ci.sh save_cache",