Grab CI configuration from masterghc-8.6-ci

This is awfully ugly but is nevertheless significantly less error-prone
than cherry-picking all of the relevant commits manually.

22 files changed, 1431 insertions, 109 deletions

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 6dcb218770..31b64a1c22 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -15,21 +15,22 @@ aliases:
       name: submodules
       command: .circleci/fetch-submodules.sh
   - &buildenv
-    THREADS: 9
-    SKIP_PERF_TESTS: YES
+    # ideally we would simply set THREADS here instead of re-detecting it every
+    # time we need it below. Unfortunately, there is no way to set an environment
+    # variable with the result of a shell script.
+    SKIP_PERF_TESTS: NO
     VERBOSE: 2
   - &boot
     run:
       name: Boot
       command: |
         ./boot
-
-        cat <<EOF >> mk/build.mk
-        BuildFlavour=$BUILD_FLAVOUR
-        ifneq "\$(BuildFlavour)" ""
-        include mk/flavours/\$(BuildFlavour).mk
-        endif
-        EOF
+  - &set_git_identity
+      run:
+        name: Set Git Identity
+        command: |
+          git config user.email "ghc-circleci@haskell.org"
+          git config user.name "GHC CircleCI"
   - &configure_unix
     run:
       name: Configure
@@ -50,131 +51,197 @@ aliases:
   - &make
     run:
       name: Build
-      command: "make -j$THREADS V=0"
+      command: "make -j`mk/detect-cpu-count.sh` V=0"
   - &build_hadrian
     run:
       name: Build GHC using Hadrian
       command: |
         cabal update
-        hadrian/build.sh -j$THREADS
+        hadrian/build.sh -j`mk/detect-cpu-count.sh`
   - &test
     run:
       name: Test
       command: |
         mkdir -p test-results
-        make test SKIP_PERF_TESTS=YES JUNIT_FILE=../../test-results/junit.xml
+        METRICS_FILE=$(mktemp)
+        echo "export METRICS_FILE=$METRICS_FILE" >> $BASH_ENV
+        make test THREADS=`mk/detect-cpu-count.sh` SKIP_PERF_TESTS=$SKIP_PERF_TESTS TEST_ENV=$TEST_ENV JUNIT_FILE=../../test-results/junit.xml METRICS_FILE=$METRICS_FILE
   - &store_test_results
     store_test_results:
       path: test-results
+  - &push_perf_note
+    run:
+      name: Push Performance Git Notes
+      command: .circleci/push-test-metrics.sh
+  - &store_test_artifacts
+    store_artifacts:
+      # we might want to add the whole output of the test phase
+      # too at some point
+      path: test-results/junit.xml
   - &slowtest
     run:
       name: Full Test
-      command: make slowtest SKIP_PERF_TESTS=YES
+      command: |
+        mkdir -p test-results
+        make slowtest SKIP_PERF_TESTS=YES THREADS=`mk/detect-cpu-count.sh` JUNIT_FILE=../../test-results/junit.xml
   - &bindist
     run:
       name: Create bindist
       # Reduce compression effort to 3
-      command: make binary-dist TAR_COMP_OPTS="-2"
+      command: make binary-dist TAR_COMP_OPTS="-2" && mv ghc*.tar.xz ghc.tar.xz
       # Building bindist takes ~15 minutes without output, account for
       # that.
       no_output_timeout: "30m"
-  - &storeartifacts
-    run:
-      name: Store artifacts
-      command: |
-        curl https://ghc-artifacts.s3.amazonaws.com/tools/ghc-artifact-collector-$GHC_COLLECTOR_FLAVOR --output ghc-artifact-collector
-        chmod +x ghc-artifact-collector
-        ./ghc-artifact-collector ghc*.tar.xz
-  - &trigger_on_tags
-    filters:
-      tags:
-        only: /^ghc-.*/
+  - &store_bindist
+    store_artifacts:
+      path: ghc.tar.xz
+  - &only_release_tags
+    tags:
+      only: /^ghc-.*/
+  - &ignore_gitlab_branches
+    branches:
+      ignore: /^gitlab\/.*/
 
 jobs:
-  "validate-x86_64-linux":
-    resource_class: xlarge
+  "validate-x86_64-freebsd":
+    docker:
+      - image: ghcci/x86_64-freebsd
+    environment:
+      TARGET: FreeBSD
+      <<: *buildenv
+      GHC_COLLECTOR_FLAVOR: x86_64-freebsd
+      TEST_ENV: x86_64-freebsd
+    steps:
+      - checkout
+      - *set_git_identity
+      - *prepare
+      - *submodules
+      - *boot
+      - *configure_bsd
+      - *make
+      - *bindist
+      - *store_bindist
+      - *test
+      - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
+
+  "validate-x86_64-darwin":
+    macos:
+      xcode: "9.0"
+    environment:
+      # Disable sphinx PDF output as MacTeX apparently doesn't provide xelatex
+      BUILD_SPHINX_PDF: "NO"
+      MACOSX_DEPLOYMENT_TARGET: "10.7"
+      # Only Sierra and onwards supports clock_gettime. See #12858
+      ac_cv_func_clock_gettime: "no"
+      GHC_COLLECTOR_FLAVOR: x86_64-darwin
+      <<: *buildenv
+      TEST_ENV: x86_64-darwin
+    steps:
+      - checkout
+      - *set_git_identity
+      - *prepare
+      - *submodules
+      - *boot
+      - *configure_unix
+      - *make
+      - *bindist
+      - *store_bindist
+      - *test
+      - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
+
+  "validate-x86_64-linux-deb8":
     docker:
-      - image: ghcci/x86_64-linux:0.0.4
+      - image: ghcci/x86_64-linux-deb8:0.1
     environment:
       <<: *buildenv
       GHC_COLLECTOR_FLAVOR: x86_64-linux
+      TEST_ENV: x86_64-linux-deb8
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
       - *configure_unix
       - *make
       - *bindist
-      - *storeartifacts
+      - *store_bindist
       - *test
       - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
-  "validate-x86_64-freebsd":
-    resource_class: xlarge
+  "validate-x86_64-linux-deb9-integer-simple":
     docker:
-      - image: ghcci/x86_64-freebsd
+      - image: ghcci/x86_64-linux-deb9:0.2
     environment:
-      TARGET: FreeBSD
       <<: *buildenv
-      GHC_COLLECTOR_FLAVOR: x86_64-freebsd
+      INTEGER_LIBRARY: integer-simple
+      GHC_COLLECTOR_FLAVOR: x86_64-linux-deb9
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
-      - *configure_bsd
+      - *configure_unix
       - *make
       - *bindist
-      - *storeartifacts
+      - *store_bindist
       - *test
       - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
-  "validate-x86_64-darwin":
-    macos:
-      xcode: "9.0"
+  "validate-x86_64-linux-deb9":
+    docker:
+      - image: ghcci/x86_64-linux-deb9:0.1
     environment:
-      # Disable sphinx PDF output as MacTeX apparently doesn't provide xelatex
-      BUILD_SPHINX_PDF: "NO"
-      MACOSX_DEPLOYMENT_TARGET: "10.7"
-      # Only Sierra and onwards supports clock_gettime. See #12858
-      ac_cv_func_clock_gettime: "no"
-      GHC_COLLECTOR_FLAVOR: x86_64-darwin
       <<: *buildenv
+      GHC_COLLECTOR_FLAVOR: x86_64-linux-deb9
+      TEST_ENV: x86_64-linux-deb9
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
       - *configure_unix
       - *make
       - *bindist
-      - *storeartifacts
+      - *store_bindist
       - *test
       - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
-  "validate-hadrian-x86_64-linux":
-    resource_class: xlarge
+  "validate-hadrian-x86_64-linux-deb8":
     docker:
-      - image: ghcci/x86_64-linux:0.0.4
+      - image: ghcci/x86_64-linux-deb8:0.1
     environment:
       <<: *buildenv
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
       - *configure_unix
       - *build_hadrian
 
-  "validate-x86_64-linux-unreg":
-    resource_class: xlarge
+  "validate-x86_64-linux-deb8-unreg":
     docker:
-      - image: ghcci/x86_64-linux:0.0.4
+      - image: ghcci/x86_64-linux-deb8:0.1
     environment:
       <<: *buildenv
+      TEST_ENV: x86_64-linux-deb8-unreg
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
@@ -182,41 +249,44 @@ jobs:
       - *make
       - *test
       - *store_test_results
+      - *push_perf_note
+      - *store_test_artifacts
 
-  "validate-x86_64-linux-llvm":
-    resource_class: xlarge
+  "validate-x86_64-linux-deb9-llvm":
     docker:
-      - image: ghcci/x86_64-linux:0.0.4
+      - image: ghcci/x86_64-linux-deb9:0.2
     environment:
       <<: *buildenv
       BUILD_FLAVOUR: perf-llvm
+      TEST_ENV: x86_64-linux-deb9-llvm
     steps:
       - run:
-          name: Install LLVM
-          command: |
-            curl http://releases.llvm.org/6.0.0/clang+llvm-6.0.0-x86_64-linux-gnu-debian8.tar.xz | tar -xJC ..
-            echo "export PATH=`pwd`/../clang+llvm-6.0.0-x86_64-linux-gnu-debian8/bin:\$PATH" >> $BASH_ENV
-      - run:
           name: Verify that llc works
           command: llc
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
       - *configure_unix
       - *make
-      - *slowtest
+      - *test
+      - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
   # Nightly build with -DDEBUG using devel2 flavour
-  "validate-x86_64-linux-debug":
-    resource_class: xlarge
+  "validate-x86_64-linux-deb8-debug":
     docker:
-      - image: ghcci/x86_64-linux:0.0.4
+      - image: ghcci/x86_64-linux-deb8:0.1
     environment:
       BUILD_FLAVOUR: devel2
       <<: *buildenv
+      TEST_ENV: x86_64-linux-deb8-debug
+      SKIP_PERF_TESTS: YES
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
@@ -224,52 +294,106 @@ jobs:
       - *make
       - *test
       - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
+
+  "validate-i386-linux-deb9":
+    docker:
+      - image: ghcci/i386-linux-deb9:0.2
+    environment:
+      <<: *buildenv
+      GHC_COLLECTOR_FLAVOR: i386-linux-deb9
+      TEST_ENV: i386-linux-deb9
+    steps:
+      - checkout
+      - *set_git_identity
+      - *prepare
+      - *submodules
+      - *boot
+      - *configure_unix_32
+      - *make
+      - *bindist
+      - *store_bindist
+      - *test
+      - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
-  "validate-i386-linux":
-    resource_class: xlarge
+  "validate-i386-linux-deb8":
     docker:
-      - image: ghcci/i386-linux:0.0.5
+      - image: ghcci/i386-linux-deb8:0.1
     environment:
       <<: *buildenv
       GHC_COLLECTOR_FLAVOR: i386-linux
+      TEST_ENV: i386-linux-deb8
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
       - *configure_unix_32
       - *make
       - *bindist
-      - *storeartifacts
+      - *store_bindist
+      - *test
+      - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
+
+  "validate-x86_64-linux-centos7":
+    docker:
+      - image: ghcci/x86_64-linux-centos7:0.1
+    environment:
+      <<: *buildenv
+      GHC_COLLECTOR_FLAVOR: x86_64-centos7
+      LANG: en_US.UTF-8
+      TEST_ENV: x86_64-centos7
+      # Sphinx is too old
+      BUILD_SPHINX_PDF: NO
+    steps:
+      - checkout
+      - *set_git_identity
+      - *prepare
+      - *submodules
+      - *boot
+      - *configure_unix
+      - *make
+      - *bindist
+      - *store_bindist
       - *test
       - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
-  "validate-x86_64-fedora":
-    resource_class: xlarge
+  "validate-x86_64-linux-fedora27":
     docker:
-      - image: ghcci/x86_64-linux-fedora:0.0.15
+      - image: ghcci/x86_64-linux-fedora27:0.1
     environment:
       <<: *buildenv
       GHC_COLLECTOR_FLAVOR: x86_64-fedora
+      TEST_ENV: x86_64-linux-fedora27
     steps:
       - checkout
+      - *set_git_identity
       - *prepare
       - *submodules
       - *boot
       - *configure_unix
       - *make
       - *bindist
-      - *storeartifacts
+      - *store_bindist
       - *test
       - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
-  "slow-validate-x86_64-linux":
-    resource_class: xlarge
+  "slow-validate-x86_64-linux-deb8":
     docker:
-      - image: ghcci/x86_64-linux:0.0.4
+      - image: ghcci/x86_64-linux-deb8:0.1
     environment:
       <<: *buildenv
-      GHC_COLLECTOR_FLAVOR: x86_64-linux
+      GHC_COLLECTOR_FLAVOR: x86_64-linux-deb8
     steps:
       - checkout
       - *prepare
@@ -278,23 +402,43 @@ jobs:
       - *configure_unix
       - *make
       - *slowtest
+      - *store_test_results
+      - *store_test_artifacts
+      - *push_perf_note
 
 workflows:
   version: 2
   validate:
     jobs:
-    - validate-x86_64-linux:
-        *trigger_on_tags
+    - validate-x86_64-linux-deb8:
+        filters:
+          <<: [*only_release_tags, *ignore_gitlab_branches]
     # FreeBSD disabled: https://github.com/haskell/unix/issues/102
     # - validate-x86_64-freebsd
     - validate-x86_64-darwin:
-        *trigger_on_tags
-    - validate-x86_64-linux-llvm
-    - validate-i386-linux:
-        *trigger_on_tags
-    - validate-hadrian-x86_64-linux
-    - validate-x86_64-fedora:
-        *trigger_on_tags
+        filters:
+          <<: [*only_release_tags, *ignore_gitlab_branches]
+    - validate-x86_64-linux-deb8-llvm:
+        filters:
+          <<: *ignore_gitlab_branches
+    - validate-i386-linux-deb8:
+        filters:
+          <<: [*only_release_tags, *ignore_gitlab_branches]
+    - validate-x86_64-linux-deb9:
+        filters:
+          <<: [*only_release_tags, *ignore_gitlab_branches]
+    - validate-i386-linux-deb9:
+        filters:
+          <<: [*only_release_tags, *ignore_gitlab_branches]
+    - validate-x86_64-linux-centos7:
+        filters:
+          <<: [*only_release_tags, *ignore_gitlab_branches]
+    - validate-hadrian-x86_64-linux-deb8:
+        filters:
+          <<: *ignore_gitlab_branches
+    - validate-x86_64-linux-fedora27:
+        filters:
+          <<: [*only_release_tags, *ignore_gitlab_branches]
 
   nightly:
     triggers:
@@ -305,10 +449,12 @@ workflows:
               only:
                 - master
     jobs:
-    - validate-x86_64-linux-unreg
-    - validate-x86_64-linux-llvm
-    - validate-x86_64-linux-debug
-    - slow-validate-x86_64-linux
+    - validate-x86_64-linux-deb8-unreg
+    - validate-x86_64-linux-deb8-llvm
+    - validate-x86_64-linux-deb8-debug
+    - validate-x86_64-linux-deb9
+    - validate-x86_64-linux-deb9-integer-simple
+    - slow-validate-x86_64-linux-deb8
 
 notify:
   webhooks:
diff --git a/.circleci/images/aarch64-linux-deb9/Dockerfile b/.circleci/images/aarch64-linux-deb9/Dockerfile
new file mode 100644
index 0000000000..f871f75b2f
--- /dev/null
+++ b/.circleci/images/aarch64-linux-deb9/Dockerfile
@@ -0,0 +1,69 @@
+FROM aarch64/debian:stretch
+
+ENV LANG C.UTF-8
+
+# Core build utilities
+RUN apt-get update -qq
+RUN apt-get install -qy zlib1g-dev libtinfo-dev libsqlite3-0 libsqlite3-dev \
+    ca-certificates g++ git make automake autoconf gcc \
+    perl python3 texinfo xz-utils lbzip2 patch openssh-client sudo \
+    jq wget curl libnuma-dev
+
+# Documentation tools
+RUN apt-get install -qy python3-sphinx texlive-xetex texlive-latex-extra
+
+# Boot LLVM
+ENV PATH /usr/local/bin:$PATH
+ENV LLVM_TARBALL http://releases.llvm.org/6.0.0/clang+llvm-6.0.0-aarch64-linux-gnu.tar.xz
+RUN curl $LLVM_TARBALL | tar -xJC .. && \
+    mkdir /opt/llvm6 && \
+    cp -R clang+llvm*/* /opt/llvm6 && \
+    rm -R clang+llvm* && \
+    /opt/llvm6/bin/llc --version
+
+# GHC
+#RUN curl http://downloads.haskell.org/~ghc/8.6.2/ghc-8.6.2-aarch64-deb8-linux.tar.xz | tar -xJ && \
+COPY ghc-8.6.2-aarch64-unknown-linux.tar.xz .
+RUN cat ghc-8.6.2-aarch64-unknown-linux.tar.xz | tar -xJ && \
+    cd ghc-8.6.2 && \
+    ./configure --prefix=/usr/local LLC=/opt/llvm6/bin/llc OPT=/opt/llvm6/bin/opt && \
+    make install && \
+    cd .. && \
+    rm -Rf ghc-*
+RUN ghc --version
+
+# LLVM
+ENV LLVM_TARBALL http://releases.llvm.org/7.0.0/clang+llvm-7.0.0-aarch64-linux-gnu.tar.xz
+ENV LLC /opt/llvm7/bin/llc
+ENV OPT /opt/llvm7/bin/opt
+RUN curl $LLVM_TARBALL | tar -xJC .. && \
+    mkdir /opt/llvm7 && \
+    cp -R clang+llvm*/* /opt/llvm7 && \
+    rm -R clang+llvm* && \
+    $LLC --version
+
+# Cabal
+RUN git clone https://github.com/haskell/Cabal && \
+    cd Cabal && \
+    git checkout cabal-install-v2.4.1.0 && \
+    cd cabal-install && \
+    ./bootstrap.sh --global --no-doc
+
+RUN ls Cabal/cabal-install/dist/build
+
+ENV PATH /home/ghc/.local/bin:/opt/cabal/2.2/bin:/opt/ghc/8.4.2/bin:$PATH
+
+# Create a normal user.
+RUN adduser ghc --gecos "GHC builds" --disabled-password
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+
+# Build Haskell tools
+RUN cabal update && \
+    cabal install hscolour happy alex
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+WORKDIR /home/ghc/
+
+CMD ["bash"]
+
diff --git a/.circleci/images/i386-linux-deb8/Dockerfile b/.circleci/images/i386-linux-deb8/Dockerfile
new file mode 100644
index 0000000000..c8e51810c2
--- /dev/null
+++ b/.circleci/images/i386-linux-deb8/Dockerfile
@@ -0,0 +1,45 @@
+FROM i386/debian:jessie
+
+ENV LANG C.UTF-8
+
+RUN echo 'deb http://ppa.launchpad.net/hvr/ghc/ubuntu trusty main' > /etc/apt/sources.list.d/ghc.list
+RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F6F88286
+RUN apt-get update -qq
+
+# Core build utilities
+RUN apt-get install -qy zlib1g-dev libtinfo-dev libsqlite3-0 libsqlite3-dev \
+    ca-certificates g++ git make automake autoconf gcc \
+    perl python3 texinfo xz-utils lbzip2 patch openssh-client sudo \
+    jq wget curl
+
+# Documentation tools
+RUN apt-get install -qy python3-sphinx texlive-xetex texlive-latex-extra
+
+# Core build utilities
+RUN apt-get install -qy libgmp-dev:i386
+
+# Get i386 GHC bindist for 32 bit CI builds.
+RUN cd /tmp && curl https://downloads.haskell.org/~ghc/8.4.2/ghc-8.4.2-i386-deb8-linux.tar.xz | tar -Jx
+RUN cd /tmp/ghc-8.4.2 && setarch i386 ./configure --prefix=/opt/ghc-i386/8.4.2 CFLAGS=-m32 --target=i386-unknown-linux --build=i386-unknown-linux --host=i386-unknown-linux
+RUN cd /tmp/ghc-8.4.2 && make install
+RUN rm -rf /tmp/ghc-8.4.2
+ENV PATH /opt/ghc-i386/8.4.2/bin:$PATH
+
+# Get Cabal
+RUN cd /tmp && \
+    curl https://www.haskell.org/cabal/release/cabal-install-2.2.0.0/cabal-install-2.2.0.0-i386-unknown-linux.tar.gz | tar -zx && \
+    mv cabal /usr/local/bin/cabal
+
+# Create a normal user.
+RUN adduser ghc --gecos "GHC builds" --disabled-password
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+
+# Build Haskell tools
+RUN cabal update && \
+    cabal install hscolour happy alex
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+WORKDIR /home/ghc/
+
+CMD ["bash"]
diff --git a/.circleci/images/i386-linux-deb9/Dockerfile b/.circleci/images/i386-linux-deb9/Dockerfile
new file mode 100644
index 0000000000..c8e51810c2
--- /dev/null
+++ b/.circleci/images/i386-linux-deb9/Dockerfile
@@ -0,0 +1,45 @@
+FROM i386/debian:jessie
+
+ENV LANG C.UTF-8
+
+RUN echo 'deb http://ppa.launchpad.net/hvr/ghc/ubuntu trusty main' > /etc/apt/sources.list.d/ghc.list
+RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F6F88286
+RUN apt-get update -qq
+
+# Core build utilities
+RUN apt-get install -qy zlib1g-dev libtinfo-dev libsqlite3-0 libsqlite3-dev \
+    ca-certificates g++ git make automake autoconf gcc \
+    perl python3 texinfo xz-utils lbzip2 patch openssh-client sudo \
+    jq wget curl
+
+# Documentation tools
+RUN apt-get install -qy python3-sphinx texlive-xetex texlive-latex-extra
+
+# Core build utilities
+RUN apt-get install -qy libgmp-dev:i386
+
+# Get i386 GHC bindist for 32 bit CI builds.
+RUN cd /tmp && curl https://downloads.haskell.org/~ghc/8.4.2/ghc-8.4.2-i386-deb8-linux.tar.xz | tar -Jx
+RUN cd /tmp/ghc-8.4.2 && setarch i386 ./configure --prefix=/opt/ghc-i386/8.4.2 CFLAGS=-m32 --target=i386-unknown-linux --build=i386-unknown-linux --host=i386-unknown-linux
+RUN cd /tmp/ghc-8.4.2 && make install
+RUN rm -rf /tmp/ghc-8.4.2
+ENV PATH /opt/ghc-i386/8.4.2/bin:$PATH
+
+# Get Cabal
+RUN cd /tmp && \
+    curl https://www.haskell.org/cabal/release/cabal-install-2.2.0.0/cabal-install-2.2.0.0-i386-unknown-linux.tar.gz | tar -zx && \
+    mv cabal /usr/local/bin/cabal
+
+# Create a normal user.
+RUN adduser ghc --gecos "GHC builds" --disabled-password
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+
+# Build Haskell tools
+RUN cabal update && \
+    cabal install hscolour happy alex
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+WORKDIR /home/ghc/
+
+CMD ["bash"]
diff --git a/.circleci/images/linters/Dockerfile b/.circleci/images/linters/Dockerfile
new file mode 100644
index 0000000000..cd9aa30e69
--- /dev/null
+++ b/.circleci/images/linters/Dockerfile
@@ -0,0 +1,30 @@
+FROM debian:stretch
+
+ENV LANG C.UTF-8
+
+RUN apt-get update -qq; apt-get install -qy gnupg sudo git python3
+
+RUN echo 'deb http://ppa.launchpad.net/hvr/ghc/ubuntu xenial main' > /etc/apt/sources.list.d/ghc.list
+RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F6F88286
+RUN apt-get update -qq
+
+# Basic Haskell toolchain
+RUN apt-get install -qy cabal-install-2.2 ghc-8.4.2
+ENV PATH /home/ghc/.local/bin:/opt/cabal/2.2/bin:/opt/ghc/8.4.2/bin:$PATH
+
+# Create a normal user.
+RUN adduser ghc --gecos "GHC builds" --disabled-password
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+WORKDIR /home/ghc/
+
+# Build Linting tools
+RUN cabal update
+
+RUN git clone git://github.com/haskell-infra/git-haskell-org-hooks && \
+    cd git-haskell-org-hooks && \
+    cabal install
+
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+CMD ["bash"]
diff --git a/.circleci/images/powerpc64le-linux-deb9-cross/Dockerfile b/.circleci/images/powerpc64le-linux-deb9-cross/Dockerfile
new file mode 100644
index 0000000000..bf0bbf3ffd
--- /dev/null
+++ b/.circleci/images/powerpc64le-linux-deb9-cross/Dockerfile
@@ -0,0 +1,7 @@
+FROM ghcci/x86_64-linux-deb9
+
+ENV LANG C.UTF-8
+RUN apt-get install qemu-user && \
+    dpkg --add-architecture ppc64el && \
+    apt-get install crossbuild-essential-ppc64el libc6:ppc64el ncurses:ppc64el
+
diff --git a/.circleci/images/update-image b/.circleci/images/update-image
index 5a3cae506c..dd69122c1f 100755
--- a/.circleci/images/update-image
+++ b/.circleci/images/update-image
@@ -17,17 +17,18 @@ fi
 name=$1
 version=$2
 
-versions="$(curl -s https://registry.hub.docker.com/v1/repositories/$repo/$name/tags | jq -r .[].name)"
-if echo "$versions" | grep $version > /dev/null; then
-    echo "Version $version of $name already exists"
-    echo "Previous versions are:"
-    echo "$versions"
-    exit 1
-fi
+#versions="$(curl -s https://registry.hub.docker.com/v1/repositories/$repo/$name/tags | jq -r .[].name)"
+#if echo "$versions" | grep $version > /dev/null; then
+#    echo "Version $version of $name already exists"
+#    echo "Previous versions are:"
+#    echo "$versions"
+#    exit 1
+#fi
 
 docker build $name -t $repo/$name:$version
 docker push $repo/$name:$version
 
 repo_name="$repo/$name"
 sed -i -E -e "s%$repo_name"':[0-9]+(\.[0-9]+)*%'"$repo_name:$version%" ../config.yml
+sed -i -E -e "s%$repo_name"':[0-9]+(\.[0-9]+)*%'"$repo_name:$version%" ../../.gitlab-ci.yml
 echo "Built, pushed, and bumped $name:$version"
diff --git a/.circleci/images/x86_64-freebsd/Dockerfile b/.circleci/images/x86_64-freebsd/Dockerfile
index 9c51cc021c..1098d7a9ac 100644
--- a/.circleci/images/x86_64-freebsd/Dockerfile
+++ b/.circleci/images/x86_64-freebsd/Dockerfile
@@ -18,6 +18,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   software-properties-common \
   sudo \
   wget \
+  jq \
   xz-utils
 
 COPY build-toolchain.sh /tmp/
diff --git a/.circleci/images/x86_64-linux-centos7/Dockerfile b/.circleci/images/x86_64-linux-centos7/Dockerfile
new file mode 100644
index 0000000000..32acea5ca3
--- /dev/null
+++ b/.circleci/images/x86_64-linux-centos7/Dockerfile
@@ -0,0 +1,54 @@
+FROM centos:7
+
+ENV LANG C.UTF-8
+
+# Core build utilities
+RUN yum -y install coreutils binutils which git make \
+    automake autoconf gcc perl python3 texinfo xz lbzip2 \
+    patch openssh-clients sudo zlib-devel sqlite \
+    ncurses-compat-libs gmp-devel ncurses-devel gcc-c++ findutils \
+    curl wget jq
+
+# Python 3
+RUN yum install -y https://centos7.iuscommunity.org/ius-release.rpm; \
+    yum install -y python34u python34u-libs
+
+# Documentation tools
+RUN yum -y install python-sphinx \
+    texlive texlive-latex texlive-xetex \
+    texlive-collection-latex texlive-collection-latexrecommended \
+    texlive-xetex-def texlive-collection-xetex \
+    python-sphinx-latex dejavu-sans-fonts dejavu-serif-fonts \
+    dejavu-sans-mono-fonts
+
+# This is in the PATH when I ssh into the CircleCI machine but somehow
+# sphinx-build isn't found during configure unless we explicitly 
+# add it here as well; perhaps PATH is being overridden by CircleCI's
+# infrastructure?
+ENV PATH /usr/libexec/python3-sphinx:$PATH
+
+# systemd isn't running so remove it from nsswitch.conf
+# Failing to do this will result in testsuite failures due to
+# non-functional user lookup (#15230).
+RUN sed -i -e 's/systemd//g' /etc/nsswitch.conf
+
+# Install GHC and cabal
+RUN cd /tmp && curl https://downloads.haskell.org/~ghc/8.4.2/ghc-8.4.2-x86_64-deb8-linux.tar.xz | tar -Jx
+RUN cd /tmp/ghc-8.4.2 && ./configure --prefix=/opt/ghc/8.4.2
+RUN cd /tmp/ghc-8.4.2 && make install
+RUN mkdir -p /opt/cabal/bin
+RUN cd /opt/cabal/bin && curl https://www.haskell.org/cabal/release/cabal-install-2.2.0.0/cabal-install-2.2.0.0-x86_64-unknown-linux.tar.gz | tar -zx
+ENV PATH /opt/ghc/8.4.2/bin:/opt/cabal/bin:$PATH
+
+# Create a normal user.
+RUN adduser ghc --comment "GHC builds"
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+WORKDIR /home/ghc/
+
+# Install Alex, Happy, and HsColor with Cabal
+RUN cabal update && \
+    cabal install hscolour happy alex
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+CMD ["bash"]
diff --git a/.circleci/images/x86_64-linux-deb8/Dockerfile b/.circleci/images/x86_64-linux-deb8/Dockerfile
new file mode 100644
index 0000000000..0491ad9bba
--- /dev/null
+++ b/.circleci/images/x86_64-linux-deb8/Dockerfile
@@ -0,0 +1,35 @@
+FROM debian:jessie
+
+ENV LANG C.UTF-8
+
+RUN echo 'deb http://ppa.launchpad.net/hvr/ghc/ubuntu trusty main' > /etc/apt/sources.list.d/ghc.list
+RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F6F88286
+RUN apt-get update -qq
+
+# Core build utilities
+RUN apt-get install -qy zlib1g-dev libtinfo-dev libsqlite3-0 libsqlite3-dev \
+    ca-certificates g++ git make automake autoconf gcc \
+    perl python3 texinfo xz-utils lbzip2 patch openssh-client sudo \
+    jq wget curl
+
+# Documentation tools
+RUN apt-get install -qy python3-sphinx texlive-xetex texlive-latex-extra
+
+# Basic Haskell toolchain
+RUN apt-get install -qy cabal-install-2.2 ghc-8.4.2
+
+ENV PATH /home/ghc/.local/bin:/opt/cabal/2.2/bin:/opt/ghc/8.4.2/bin:$PATH
+
+# Create a normal user.
+RUN adduser ghc --gecos "GHC builds" --disabled-password
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+
+# Build Haskell tools
+RUN cabal update && \
+    cabal install hscolour happy alex
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+WORKDIR /home/ghc/
+
+CMD ["bash"]
diff --git a/.circleci/images/x86_64-linux-deb9/Dockerfile b/.circleci/images/x86_64-linux-deb9/Dockerfile
new file mode 100644
index 0000000000..5341abe6ef
--- /dev/null
+++ b/.circleci/images/x86_64-linux-deb9/Dockerfile
@@ -0,0 +1,46 @@
+FROM debian:stretch
+
+ENV LANG C.UTF-8
+
+RUN apt-get update -qq; apt-get install -qy gnupg
+
+RUN echo 'deb http://ppa.launchpad.net/hvr/ghc/ubuntu xenial main' > /etc/apt/sources.list.d/ghc.list
+RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F6F88286
+RUN apt-get update -qq
+
+# Core build utilities
+RUN apt-get install -qy zlib1g-dev libtinfo-dev libsqlite3-0 libsqlite3-dev \
+    ca-certificates g++ git make automake autoconf gcc \
+    perl python3 texinfo xz-utils lbzip2 patch openssh-client sudo \
+    jq wget curl
+
+# Documentation tools
+RUN apt-get install -qy python3-sphinx texlive-xetex texlive-latex-extra
+
+# Basic Haskell toolchain
+RUN apt-get install -qy cabal-install-2.2 ghc-8.4.2
+
+ENV PATH /home/ghc/.local/bin:/opt/cabal/2.2/bin:/opt/ghc/8.4.2/bin:$PATH
+
+# LLVM
+ENV LLVM_TARBALL http://releases.llvm.org/7.0.0/clang+llvm-7.0.0-x86_64-linux-gnu-ubuntu-16.04.tar.xz
+ENV PATH /opt/llvm/bin:$PATH
+RUN curl $LLVM_TARBALL | tar -xJC ..; \
+    mkdir /opt/llvm; \
+    cp -R clang+llvm*/* /opt/llvm; \
+    rm -R clang+llvm*; \
+    llc --version
+
+# Create a normal user.
+RUN adduser ghc --gecos "GHC builds" --disabled-password
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+
+# Build Haskell tools
+RUN cabal update && \
+    cabal install hscolour happy alex
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+WORKDIR /home/ghc/
+
+CMD ["bash"]
diff --git a/.circleci/images/x86_64-linux-fedora27/Dockerfile b/.circleci/images/x86_64-linux-fedora27/Dockerfile
new file mode 100644
index 0000000000..6fad77f1c5
--- /dev/null
+++ b/.circleci/images/x86_64-linux-fedora27/Dockerfile
@@ -0,0 +1,50 @@
+FROM fedora:27
+
+ENV LANG C.UTF-8
+
+# Core build utilities
+RUN dnf -y install coreutils binutils which git make \
+    automake autoconf gcc perl python3 texinfo xz lbzip2 \
+    patch openssh-clients sudo zlib-devel sqlite \
+    ncurses-compat-libs gmp-devel ncurses-devel gcc-c++ findutils \
+    curl wget jq
+
+# Documentation tools
+RUN dnf -y install python3-sphinx \
+    texlive texlive-latex texlive-xetex \
+    texlive-collection-latex texlive-collection-latexrecommended \
+    texlive-xetex-def texlive-collection-xetex \
+    python-sphinx-latex dejavu-sans-fonts dejavu-serif-fonts \
+    dejavu-sans-mono-fonts
+
+# This is in the PATH when I ssh into the CircleCI machine but somehow
+# sphinx-build isn't found during configure unless we explicitly 
+# add it here as well; perhaps PATH is being overridden by CircleCI's
+# infrastructure?
+ENV PATH /usr/libexec/python3-sphinx:$PATH
+
+# systemd isn't running so remove it from nsswitch.conf
+# Failing to do this will result in testsuite failures due to
+# non-functional user lookup (#15230).
+RUN sed -i -e 's/systemd//g' /etc/nsswitch.conf
+
+# Install GHC and cabal
+RUN cd /tmp && curl https://downloads.haskell.org/~ghc/8.4.2/ghc-8.4.2-x86_64-deb8-linux.tar.xz | tar -Jx
+RUN cd /tmp/ghc-8.4.2 && ./configure --prefix=/opt/ghc/8.4.2
+RUN cd /tmp/ghc-8.4.2 && make install
+RUN mkdir -p /opt/cabal/bin
+RUN cd /opt/cabal/bin && curl https://www.haskell.org/cabal/release/cabal-install-2.2.0.0/cabal-install-2.2.0.0-x86_64-unknown-linux.tar.gz | tar -zx
+ENV PATH /opt/ghc/8.4.2/bin:/opt/cabal/bin:$PATH
+
+# Create a normal user.
+RUN adduser ghc --comment "GHC builds"
+RUN echo "ghc ALL = NOPASSWD : ALL" > /etc/sudoers.d/ghc
+USER ghc
+WORKDIR /home/ghc/
+
+# Install Alex, Happy, and HsColor with Cabal
+RUN cabal update && \
+    cabal install hscolour happy alex
+ENV PATH /home/ghc/.cabal/bin:$PATH
+
+CMD ["bash"]
diff --git a/.circleci/prepare-system.sh b/.circleci/prepare-system.sh
index 7d8cac60a2..804e0fd890 100755
--- a/.circleci/prepare-system.sh
+++ b/.circleci/prepare-system.sh
@@ -11,6 +11,8 @@ hackage_index_state="@1522046735"
 
 if [[ -z ${BUILD_SPHINX_HTML:-} ]]; then BUILD_SPHINX_HTML=YES; fi
 if [[ -z ${BUILD_SPHINX_PDF:-} ]]; then BUILD_SPHINX_PDF=YES; fi
+if [[ -z ${INTEGER_LIBRARY:-} ]]; then INTEGER_LIBRARY=integer-gmp; fi
+if [[ -z ${BUILD_FLAVOUR:-} ]]; then BUILD_FLAVOUR=perf; fi
 
 cat > mk/build.mk <<EOF
 V=1
@@ -20,6 +22,14 @@ HSCOLOUR_SRCS=YES
 BUILD_SPHINX_HTML=$BUILD_SPHINX_HTML
 BUILD_SPHINX_PDF=$BUILD_SPHINX_PDF
 BeConservative=YES
+INTEGER_LIBRARY=$INTEGER_LIBRARY
+EOF
+
+cat <<EOF >> mk/build.mk
+BuildFlavour=$BUILD_FLAVOUR
+ifneq "\$(BuildFlavour)" ""
+include mk/flavours/\$(BuildFlavour).mk
+endif
 EOF
 
 case "$(uname)" in
@@ -27,15 +37,6 @@ case "$(uname)" in
     if [[ -n ${TARGET:-} ]]; then
       if [[ $TARGET = FreeBSD ]]; then
         # cross-compiling to FreeBSD
-        add-apt-repository -y ppa:hvr/ghc
-        apt-get update -qq
-        apt-get install -qy ghc-8.0.2 cabal-install-1.24 alex happy \
-                            ncurses-dev git make automake autoconf gcc perl \
-                            python3 texinfo xz-utils lbzip2 patch
-        cabal update
-        cabal install --reinstall hscolour --index-state=$hackage_index_state
-        ln -s $HOME/.cabal/bin/HsColour /usr/local/bin/HsColour
-
         echo 'HADDOCK_DOCS = NO' >> mk/build.mk
         echo 'WERROR=' >> mk/build.mk
         # https://circleci.com/docs/2.0/env-vars/#interpolating-environment-variables-to-set-other-environment-variables
@@ -43,10 +44,6 @@ case "$(uname)" in
       else
         fail "TARGET=$target not supported"
       fi
-    else
-      cabal update -v
-      cabal install --reinstall hscolour
-      sudo ln -s /home/ghc/.cabal/bin/HsColour /usr/local/bin/HsColour || true
     fi
     ;;
 
diff --git a/.circleci/push-test-metrics.sh b/.circleci/push-test-metrics.sh
new file mode 100755
index 0000000000..e383a4c4e7
--- /dev/null
+++ b/.circleci/push-test-metrics.sh
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# vim: sw=2 et
+set -euo pipefail
+
+fail() {
+  echo "ERROR: $*" >&2
+  exit 1
+}
+
+if [ "$CIRCLE_REPOSITORY_URL" != "git@github.com:ghc/ghc.git" ]; then
+  exit 0
+fi
+
+GHC_ORIGIN=git@git.haskell.org:ghc
+
+# Add git.haskell.org as a known host.
+echo "|1|F3mPVCE55+KfApNIMYQ3Dv39sGE=|1bRkvJEJhAN2R0LE/lAjFCEJGl0= ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBBUZS9jGBkE5UzpSo6irnIgcQcfzvbuIOsFc8+N61FwtZncRntbaKPuUimOFPgeaUZLl6Iajz6IIs7aduU0/v+I=" >> ~/.ssh/known_hosts
+echo "|1|2VUMjYSRVpT2qJPA0rA9ap9xILY=|5OThkI4ED9V0J+Es7D5FOD55Klk= ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC+3TLluLAO4lkW60W+N2DFkS+WoRFGqLwHzgd1ifxG9TIm31wChPY3E/hgMnJmgGqWCF4UDUemmyCycEaL7FtKfzjTAclg9EfpQnozyE3T5hIo2WL7SN5O8ttG/bYGuDnn14jLnWwJyN4oz/znWFiDG9e2Oc9YFNlQ+PK8ae5xR4gqBB7EOoj9J1EiPqG2OXRr5Mei3TLsRDU6fnz/e4oFJpKWWeN6M63oePv0qoaGjxcrATZUWsuWrxVMmYo9kP1xRuFJbAUw2m4uVP+793SW1zxySi1HBMtJG+gCDdZZSwYbkV1hassLWBHv1qPttncfX8Zek3Z3VolaTmfWJTo9" >> ~/.ssh/known_hosts
+
+# Check that a git notes dont already exist.
+# This is a percausion as we reset refs/notes/perf and we want to avoid data loss.
+if [ $(git notes --ref=perf list | wc -l) -ne 0 ]
+then
+  fail "Found an existing git note on HEAD. Expected no git note."
+fi
+
+# Assert that the METRICS_FILE exists and can be read.
+if [ "$METRICS_FILE" = "" ] || ! [ -r $METRICS_FILE ]
+then
+  fail "Metrics file not found: $METRICS_FILE"
+fi
+
+# Reset the git notes and append the metrics file to the notes, then push and return the result.
+# This is favoured over a git notes merge as it avoids potential data loss/duplication from the merge strategy.
+function reset_append_note_push {
+  git fetch -f $GHC_ORIGIN refs/notes/perf:refs/notes/perf || true
+  echo "git notes --ref=perf append -F $METRICS_FILE HEAD"
+  git notes --ref=perf append -F $METRICS_FILE HEAD
+  git push $GHC_ORIGIN refs/notes/perf
+}
+
+# Push the metrics file as a git note. This may fail if another task pushes a note first. In that case
+# the latest note is fetched and appended.
+MAX_RETRY=20
+until reset_append_note_push || [ $MAX_RETRY -le 0 ]
+do
+  ((MAX_RETRY--))
+  echo ""
+  echo "Failed to push git notes. Fetching, appending, and retrying... $MAX_RETRY retries left."
+done
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 0000000000..06d7589bca
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,401 @@
+variables:
+  GIT_SSL_NO_VERIFY: "1"
+
+before_script:
+  - python3 .gitlab/fix-submodules.py
+  - git submodule sync --recursive
+  - git submodule update --init --recursive
+  - git checkout .gitmodules
+
+stages:
+  - lint
+  - build
+  - full-build
+
+############################################################
+# Runner Tags
+############################################################
+#
+# * x86_64-linux: Any Docker-capable x86_64 Linux machine
+# * aarch64-linux: Any Docker-capable AArch64 Linux machine
+# * x86_64-windows: A x86_64 Windows machine
+# * lint: Any Docker-capable x86_64 Linux machine; distinct from
+#         x86_64-linux to ensure low-latency availability.
+#
+
+
+############################################################
+# Linting
+############################################################
+
+ghc-linters:
+  stage: lint
+  image: ghcci/linters:0.1
+  script:
+    - |
+      if [ -n "$CI_MERGE_REQUEST_ID" ]; then
+        base="$(git merge-base $CI_MERGE_REQUEST_BRANCH_NAME HEAD)"
+        validate-commit-msg .git $(git rev-list $base..$CI_COMMIT_SHA)
+        submodchecker .git $(git rev-list $base..$CI_COMMIT_SHA)
+        validate-whitespace .git $(git rev-list $base..$CI_COMMIT_SHA)
+        .gitlab/linters/check-makefiles.py $base $CI_COMMIT_SHA
+        .gitlab/linters/check-cpp.py $base $CI_COMMIT_SHA
+      fi
+  tags:
+    - lint
+
+############################################################
+# Validation via Pipelines (hadrian)
+############################################################
+
+.validate-hadrian:
+  allow_failure: true
+  script:
+    - git clean -xdf && git submodule foreach git clean -xdf
+    - bash .circleci/prepare-system.sh
+    - if [[ -d ./cabal-cache ]]; then cp -R ./.cabal-cache ~/.cabal-cache; fi
+    - ./boot
+    - ./configure $CONFIGURE_ARGS
+    - hadrian/build.cabal.sh -j`mk/detect-cpu-count.sh`
+  cache:
+    key: hadrian
+    paths:
+      - cabal-cache
+
+validate-x86_64-linux-deb8-hadrian:
+  extends: .validate-hadrian
+  stage: build
+  image: ghcci/x86_64-linux-deb8:0.1
+  before_script:
+    # workaround for docker permissions
+    - sudo chown ghc:ghc -R .
+    - python3 .gitlab/fix-submodules.py
+    - git submodule sync --recursive
+    - git submodule update --init --recursive
+    - git checkout .gitmodules
+  tags:
+    - x86_64-linux
+
+############################################################
+# Validation via Pipelines (make)
+############################################################
+
+.validate:
+  variables:
+    TEST_TYPE: test
+  before_script:
+    - git clean -xdf && git submodule foreach git clean -xdf
+  script:
+    - ./boot
+    - ./configure $CONFIGURE_ARGS
+    - |
+      THREADS=`mk/detect-cpu-count.sh`
+      make V=0 -j$THREADS
+    - |
+      make binary-dist TAR_COMP_OPTS="-1"
+      mv ghc-*.tar.xz ghc.tar.xz
+    - |
+      THREADS=`mk/detect-cpu-count.sh`
+      make $TEST_TYPE THREADS=$THREADS JUNIT_FILE=../../junit.xml
+  artifacts:
+    reports:
+      junit: junit.xml
+    expire_in: 2 week
+    paths:
+      - ghc.tar.xz
+      - junit.xml
+
+validate-x86_64-darwin:
+  extends: .validate
+  stage: full-build
+  allow_failure: true
+  tags:
+    - x86_64-darwin
+  variables:
+    GHC_VERSION: 8.6.3
+    MACOSX_DEPLOYMENT_TARGET: "10.7"
+    # Only Sierra and onwards supports clock_gettime. See #12858
+    ac_cv_func_clock_gettime: "no"
+    LANG: "en_US.UTF-8"
+  before_script:
+    - git clean -xdf && git submodule foreach git clean -xdf
+    - python .gitlab/fix-submodules.py
+    - git submodule sync --recursive
+    - git submodule update --init --recursive
+    - git checkout .gitmodules
+
+    - bash .gitlab/darwin-init.sh
+    - PATH="`pwd`/toolchain/bin:$PATH"
+      # Disable sphinx PDF output as MacTeX apparently doesn't provide xelatex
+    - echo "BUILD_SPHINX_PDF=NO" >> mk/build.mk
+    - echo "libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-intree-gmp" >> mk/build.mk
+  after_script:
+    - cp -Rf $HOME/.cabal cabal-cache
+  artifacts:
+    when: always
+    expire_in: 2 week
+  cache:
+    key: darwin
+    paths:
+      - cabal-cache
+      - toolchain
+
+.validate-linux:
+  extends: .validate
+  tags:
+    - x86_64-linux
+  before_script:
+    - git clean -xdf && git submodule foreach git clean -xdf
+    - python3 .gitlab/fix-submodules.py
+    - git submodule sync --recursive
+    - git submodule update --init --recursive
+    - git checkout .gitmodules
+
+    - bash .circleci/prepare-system.sh
+    # workaround for docker permissions
+    - sudo chown ghc:ghc -R .
+  after_script:
+    - cp -Rf $HOME/.cabal cabal-cache
+  cache:
+    key: linux
+    paths:
+      - cabal-cache
+      - toolchain
+
+validate-aarch64-linux-deb9:
+  extends: .validate-linux
+  stage: full-build
+  image: ghcci/aarch64-linux-deb9:0.1
+  allow_failure: true
+  artifacts:
+    when: always
+    expire_in: 2 week
+  cache:
+    key: linux-aarch64-deb9
+  tags:
+    - aarch64-linux
+
+nightly-aarch64-linux-deb9:
+  extends: validate-aarch64-linux-deb9
+  stage: full-build
+  artifacts:
+    expire_in: 2 year
+  variables:
+    TEST_TYPE: slowtest
+  only:
+    variables:
+      - $NIGHTLY
+
+validate-i386-linux-deb9:
+  extends: .validate-linux
+  stage: full-build
+  image: ghcci/i386-linux-deb9:0.1
+  allow_failure: true
+  artifacts:
+    when: always
+    expire_in: 2 week
+  cache:
+    key: linux-i386-deb9
+
+nightly-i386-linux-deb9:
+  extends: .validate-linux
+  stage: full-build
+  image: ghcci/i386-linux-deb9:0.1
+  allow_failure: true
+  variables:
+    TEST_TYPE: slowtest
+  artifacts:
+    when: always
+    expire_in: 2 week
+  only:
+    variables:
+      - $NIGHTLY
+  cache:
+    key: linux-i386-deb9
+
+validate-x86_64-linux-deb9:
+  extends: .validate-linux
+  stage: build
+  image: ghcci/x86_64-linux-deb9:0.2
+  artifacts:
+    when: always
+    expire_in: 2 week
+  cache:
+    key: linux-x86_64-deb9
+
+nightly-x86_64-linux-deb9:
+  extends: validate-x86_64-linux-deb9
+  stage: build
+  artifacts:
+    expire_in: 2 year
+  variables:
+    TEST_TYPE: slowtest
+  only:
+    variables:
+      - $NIGHTLY
+
+validate-x86_64-linux-deb9-llvm:
+  extends: .validate-linux
+  stage: full-build
+  allow_failure: true
+  image: ghcci/x86_64-linux-deb9:0.2
+  variables:
+    BUILD_FLAVOUR: perf-llvm
+  cache:
+    key: linux-x86_64-deb9
+
+validate-x86_64-linux-deb8:
+  extends: .validate-linux
+  stage: full-build
+  image: ghcci/x86_64-linux-deb8:0.1
+  cache:
+    key: linux-x86_64-deb8
+  artifacts:
+    when: always
+    expire_in: 2 week
+
+validate-x86_64-linux-fedora27:
+  extends: .validate-linux
+  stage: full-build
+  image: ghcci/x86_64-linux-fedora27:0.1
+  cache:
+    key: linux-x86_64-fedora27
+  artifacts:
+    when: always
+    expire_in: 2 week
+
+validate-x86_64-linux-deb9-integer-simple:
+  extends: .validate-linux
+  stage: full-build
+  variables:
+    INTEGER_LIBRARY: integer-simple
+  image: ghcci/x86_64-linux-deb9:0.2
+  cache:
+    key: linux-x86_64-deb9
+
+nightly-x86_64-linux-deb9-integer-simple:
+  extends: validate-x86_64-linux-deb9-integer-simple
+  stage: full-build
+  artifacts:
+    expire_in: 2 year
+  variables:
+    TEST_TYPE: slowtest
+  only:
+    variables:
+      - $NIGHTLY
+
+validate-x86_64-linux-deb9-unreg:
+  extends: .validate-linux
+  stage: full-build
+  variables:
+    CONFIGURE_ARGS: --enable-unregisterised
+  image: ghcci/x86_64-linux-deb9:0.2
+  cache:
+    key: linux-x86_64-deb9
+
+############################################################
+# Validation via Pipelines (Windows)
+############################################################
+
+.validate-windows:
+  before_script:
+    - git clean -xdf
+    - git submodule foreach git clean -xdf
+
+    # Use a local temporary directory to ensure that concurrent builds don't
+    # interfere with one another
+    - |
+      mkdir tmp
+      set TMP=%cd%\tmp
+      set TEMP=%cd%\tmp
+
+    - set PATH=C:\msys64\usr\bin;%PATH%
+    - python .gitlab/fix-submodules.py
+    - git submodule sync --recursive
+    - git submodule update --init --recursive
+    - git checkout .gitmodules
+    - bash .gitlab/win32-init.sh
+  after_script:
+    - rd /s /q tmp
+    - robocopy /np /nfl /ndl /e "%APPDATA%\cabal" cabal-cache
+    - bash -c 'make clean || true'
+  cache:
+    paths:
+      - cabal-cache
+      - ghc-8.6.2
+      - ghc-tarballs
+
+validate-x86_64-windows-hadrian:
+  extends: .validate-windows
+  stage: full-build
+  # due to #16073
+  allow_failure: true
+  variables:
+    GHC_VERSION: "8.6.2"
+    LANG: "en_US.UTF-8"
+  script:
+    - |
+      set MSYSTEM=MINGW64
+      python boot
+      bash -c './configure --with-ghc=`pwd`/toolchain/bin/ghc --enable-tarballs-autodownload HappyCmd=`pwd`/toolchain/bin/happy AlexCmd=`pwd`/toolchain/bin/alex'
+      mkdir -p _build
+      cp -R inplace/mingw _build/mingw
+    # FIXME: --no-lint due to #15950
+    - bash -c "PATH=`pwd`/toolchain/bin:$PATH hadrian/build.cabal.sh -j`mk/detect-cpu-count.sh` --flavour=Quick --no-lint"
+    - bash -c "PATH=`pwd`/toolchain/bin:$PATH hadrian/build.cabal.sh binary-dist"
+    - bash -c 'make V=0 test THREADS=`mk/detect-cpu-count.sh` JUNIT_FILE=../../junit.xml'
+  cache:
+    key: x86_64-windows
+  tags:
+    - x86_64-windows
+
+validate-x86_64-windows:
+  extends: .validate-windows
+  stage: build
+  # due to #16084
+  allow_failure: true
+  variables:
+    GHC_VERSION: "8.6.2"
+    LANG: "en_US.UTF-8"
+  script:
+    - |
+      set MSYSTEM=MINGW64
+      python boot
+      bash -c './configure --with-ghc=`pwd`/toolchain/bin/ghc --enable-tarballs-autodownload HappyCmd=`pwd`/toolchain/bin/happy AlexCmd=`pwd`/toolchain/bin/alex'
+    - bash -c "echo include mk/flavours/quick.mk > mk/build.mk"
+    - bash -c "PATH=`pwd`/toolchain/bin:$PATH make -j`mk/detect-cpu-count.sh`"
+    - bash -c 'make V=0 test THREADS=`mk/detect-cpu-count.sh` JUNIT_FILE=../../junit.xml'
+  cache:
+    key: x86_64-windows
+  tags:
+    - x86_64-windows
+
+############################################################
+# Validation via CircleCI
+############################################################
+
+.circleci:
+  stage: build
+  image: ghcci/x86_64-linux-deb8:0.1
+  artifacts:
+    when: always
+    expire_in: 2 week
+    reports:
+      junit: junit.xml
+    paths:
+      - ghc.tar.xz
+      - junit.xml
+  tags:
+    - circleci
+
+# All validation jobs keep the bindists and test results are artifacts,
+# when we get far enough to generate them.
+#
+# This requires updating the maximum artifacts size limit in Gitlab to
+# something like 200MB.
+
+.circleci-validate-x86_64-darwin:
+  extends: .circleci
+  stage: full-build
+  allow_failure: true
+  script: ".gitlab/circle-ci-job.sh validate-x86_64-darwin"
diff --git a/.gitlab/circle-ci-job.sh b/.gitlab/circle-ci-job.sh
new file mode 100755
index 0000000000..bbb00e062a
--- /dev/null
+++ b/.gitlab/circle-ci-job.sh
@@ -0,0 +1,110 @@
+# Circle CI "backend" for Gitlab CI
+# =================================
+#
+# Usage example:
+#   .gitlab/circle-ci-job.sh validate-x86_64-linux
+#
+# There are two things to configure to get artifacts to be
+# uploaded to gitlab properly:
+#
+# - At https://<gitlab host>/admin/application_settings, expand the
+#   Continuous Integration and Deployment section and set the
+#   "Maximum artifacts size (MB)" field to something large enough
+#   to contain the bindists (the test reports are tiny in comparison).
+#   500MB seems to work fine, but 200MB might be sufficient.
+#
+# - If gitlab is exposed behind some form of proxy (e.g nginx), make sure
+#   the maximum client request body size is large enough to contain all the
+#   artifacts of a build. For nginx, this would be the following configuration
+#   option: https://nginx.org/en/docs/http/ngx_http_core_module.html#client_max_body_size
+#   (which can be set with services.nginx.clientMaxBodySize on nixos).
+
+#!/usr/bin/env sh
+
+set -e
+
+GHCCI_URL="localhost:8888"
+
+[ $# -gt 0 ] || (echo You need to pass the Circle CI job type as argument to this script; exit 1)
+[ ${CI_RUNNER_ID:-} ] || (echo "CI_RUNNER_ID is not set"; exit 1)
+[ ${CI_JOB_ID:-} ] || (echo "CI_JOB_ID is not set"; exit 1)
+[ ${CI_COMMIT_SHA:-} ] || (echo "CI_COMMIT_SHA is not set"; exit 1)
+[ ${CI_REPOSITORY_URL:-} ] || (echo "CI_REPOSITORY_URL is not set"; exit 1)
+[ ${CI_PIPELINE_ID:-} ] || (echo "CI_PIPELINE_ID is not set"; exit 1)
+# the first argument to this script is the Circle CI job type:
+# validate-x86_64-linux, validate-i386-linux, ...
+CIRCLE_JOB="circleci-$1"
+
+gitlab_user=$(echo $CI_REPOSITORY_URL | cut -d/ -f4)
+gitlab_repo=$(echo $CI_REPOSITORY_URL | cut -d/ -f5 | cut -d. -f1)
+
+BODY="{ \"jobType\": \"$CIRCLE_JOB\", \"source\": { \"user\": \"$gitlab_user\", \"project\":\"$gitlab_repo\", \"commit\":\"$CI_COMMIT_SHA\" }, \"pipelineID\": $CI_PIPELINE_ID, \"runnerID\": $CI_RUNNER_ID, \"jobID\": $CI_JOB_ID }"
+
+
+RESP=$(curl -s -XPOST -H "Content-Type: application/json" -d "$BODY" \
+	    http://${GHCCI_URL}/job)
+
+if [ $? -eq 0 ]; then
+    build_num=$(echo $RESP | jq '.build_num')
+    circle_url=$(echo $RESP | jq '.url')
+else
+    echo "Couldn't submit job"
+    echo $RESP
+    exit 1
+fi
+
+echo Circle CI build number: $build_num
+echo Circle CI build page: $circle_url
+
+outcome="null"
+STATUS_URL="http://${GHCCI_URL}/job/${build_num}"
+STATUS_RESP=""
+
+while [ "$outcome" == "null" ]; do
+    sleep 30s
+    STATUS_RESP=$(curl -s $STATUS_URL)
+    if [ $? -eq 0 ]; then
+	new_outcome=$(echo $STATUS_RESP | jq '.outcome')
+	jq_exitcode=$?
+	if [ "$new_outcome" == "null" ] && [ $jq_exitcode -ne 0 ]; then
+	    echo "Couldn't read 'outcome' field in JSON:"
+	    echo $STATUS_RESP
+	    echo "Skipping"
+	else
+	    outcome="$new_outcome"
+	fi
+    else
+	echo "curl failed:"
+	echo $STATUS_RESP
+	echo "Skipping"
+    fi
+done
+
+if [ "$outcome" == "\"success\"" ]; then
+    echo The build passed
+    artifactsBody=$(curl -s http://${GHCCI_URL}/job/${build_num}/artifacts)
+    (echo $artifactsBody | jq '.[] | .url' | xargs wget -q) || echo "No artifacts"
+    exit 0
+else
+    echo The build failed
+
+    artifactsBody=$(curl -s http://${GHCCI_URL}/job/${build_num}/artifacts)
+    (echo $artifactsBody | jq '.[] | .url' | xargs wget -q) || echo "No artifacts"
+
+    failing_step=$(echo $STATUS_RESP | jq '.steps | .[] | .actions | .[] | select(.status != "success")')
+    failing_step_name=$(echo $failing_step | jq '.name' | sed -e 's/^"//' -e 's/"$//' -e 's/\\r\\n/\n/')
+    echo "Failing step: $failing_step_name"
+
+    failing_cmds=$(echo $failing_step | jq '.bash_command' | sed -e 's/^"//' -e 's/"$//' -e 's/\\r\\n/\n/')
+    echo "Failing command(s):"
+    echo $failing_cmds
+
+    log_url=$(echo $failing_step | jq '.output_url' | sed -e 's/^"//' -e 's/"$//' -e 's/\\r\\n/\n/')
+    echo "Log url: $log_url"
+
+    last_log_lines=$(curl -s $log_url | gunzip | jq '.[] | select(.type == "out") | .message' | sed -e 's/^"//' -e 's/"$//' -e 's/\\r\\n/\n/' | tail -50)
+    echo End of the build log:
+    echo $last_log_lines
+
+    exit 1
+fi
diff --git a/.gitlab/darwin-init.sh b/.gitlab/darwin-init.sh
new file mode 100644
index 0000000000..ba5de9db35
--- /dev/null
+++ b/.gitlab/darwin-init.sh
@@ -0,0 +1,41 @@
+#!/bin/bash
+
+set -e
+
+toolchain=`pwd`/toolchain
+PATH="$toolchain/bin:$PATH"
+
+if [ -d "`pwd`/cabal-cache" ]; then
+    cp -Rf cabal-cache $HOME/.cabal
+fi
+
+if [ ! -e $toolchain/bin/ghc ]; then
+    mkdir -p tmp
+    cd tmp
+    ghc_tarball="https://downloads.haskell.org/~ghc/$GHC_VERSION/ghc-$GHC_VERSION-x86_64-apple-darwin.tar.xz"
+    echo "Fetching GHC from $ghc_tarball"
+    curl $ghc_tarball | tar -xJ
+    cd ghc-$GHC_VERSION
+    ./configure --prefix=$toolchain
+    make install
+    cd ../..
+    rm -Rf tmp
+fi
+
+if [ ! -e $toolchain/bin/cabal ]; then
+    cabal_tarball="https://downloads.haskell.org/~cabal/cabal-install-latest/cabal-install-2.4.1.0-x86_64-apple-darwin-sierra.tar.xz"
+    echo "Fetching cabal-install from $cabal_tarball"
+    curl $cabal_tarball | tar -xz
+    mv cabal $toolchain/bin
+fi
+
+if [ ! -e $toolchain/bin/happy ]; then
+    cabal update
+    cabal new-install happy --symlink-bindir=$toolchain/bin
+fi
+
+if [ ! -e $toolchain/bin/alex ]; then
+    cabal update
+    cabal new-install alex --symlink-bindir=$toolchain/bin
+fi
+
diff --git a/.gitlab/fix-submodules.py b/.gitlab/fix-submodules.py
new file mode 100644
index 0000000000..2ff8e41974
--- /dev/null
+++ b/.gitlab/fix-submodules.py
@@ -0,0 +1,8 @@
+#!/usr/bin/python
+
+import re
+
+x = open('.gitmodules').read()
+x = re.sub(r"url *= *\.\.", "url = https://gitlab.haskell.org/ghc", x)
+open('.gitmodules', 'w').write(x)
+
diff --git a/.gitlab/linters/check-cpp.py b/.gitlab/linters/check-cpp.py
new file mode 100755
index 0000000000..c89451399e
--- /dev/null
+++ b/.gitlab/linters/check-cpp.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+
+# A linter to warn for ASSERT macros which are separated from their argument
+# list by a space, which Clang's CPP barfs on
+
+from linter import run_linters, RegexpLinter
+
+linters = [
+    RegexpLinter(r'WARN\s+\(',
+                 message='CPP macros should not have a space between the macro name and their argument list'),
+    RegexpLinter(r'ASSERT\s+\(',
+                 message='CPP macros should not have a space between the macro name and their argument list'),
+    RegexpLinter(r'ASSERT2\s+\(',
+                 message='CPP macros should not have a space between the macro name and their argument list'),
+    RegexpLinter(r'#ifdef\s+',
+                 message='`#if defined(x)` is preferred to `#ifdef x`'),
+    RegexpLinter(r'#if\s+defined\s+',
+                 message='`#if defined(x)` is preferred to `#if defined x`'),
+    RegexpLinter(r'#ifndef\s+',
+                 message='`#if !defined(x)` is preferred to `#ifndef x`'),
+]
+
+if __name__ == '__main__':
+    run_linters(linters)
diff --git a/.gitlab/linters/check-makefiles.py b/.gitlab/linters/check-makefiles.py
new file mode 100755
index 0000000000..c97838beb5
--- /dev/null
+++ b/.gitlab/linters/check-makefiles.py
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+"""
+Warn for use of `--interactive` inside Makefiles (#11468).
+
+Encourage the use of `$(TEST_HC_OPTS_INTERACTIVE)` instead of
+`$(TEST_HC_OPTS) --interactive -ignore-dot-ghci -v0`. It's too easy to
+forget one of those flags when adding a new test.
+"""
+
+from linter import run_linters, RegexpLinter
+
+linters = [
+    RegexpLinter(r'--interactive',
+                 message = "Warning: Use `$(TEST_HC_OPTS_INTERACTIVE)` instead of `--interactive -ignore-dot-ghci -v0`.")
+]
+
+if __name__ == '__main__':
+    run_linters(linters) #$, subdir='testsuite')
diff --git a/.gitlab/linters/linter.py b/.gitlab/linters/linter.py
new file mode 100644
index 0000000000..ec4f3581a8
--- /dev/null
+++ b/.gitlab/linters/linter.py
@@ -0,0 +1,109 @@
+"""
+Utilities for linters
+"""
+
+import os
+import sys
+import re
+import textwrap
+import subprocess
+from typing import List, Optional
+from collections import namedtuple
+
+def lint_failure(file, line_no, line_content, message):
+    """ Print a lint failure message. """
+    wrapper = textwrap.TextWrapper(initial_indent='  ',
+                                   subsequent_indent='    ')
+    body = wrapper.fill(message)
+    msg = '''
+    {file}:
+
+             |
+      {line_no:5d}  |  {line_content}
+             |
+
+    {body}
+    '''.format(file=file, line_no=line_no,
+               line_content=line_content,
+               body=body)
+
+    print(textwrap.dedent(msg))
+
+def get_changed_files(base_commit, head_commit,
+                      subdir: str = '.'):
+    """ Get the files changed by the given range of commits. """
+    cmd = ['git', 'diff', '--name-only',
+           base_commit, head_commit, '--', subdir]
+    files = subprocess.check_output(cmd)
+    return files.decode('UTF-8').split('\n')
+
+Warning = namedtuple('Warning', 'path,line_no,line_content,message')
+
+class Linter(object):
+    """
+    A :class:`Linter` must implement :func:`lint`, which looks at the
+    given path and calls :func:`add_warning` for any lint issues found.
+    """
+    def __init__(self):
+        self.warnings = [] # type: List[Warning]
+
+    def add_warning(self, w: Warning):
+        self.warnings.append(w)
+
+    def lint(self, path):
+        pass
+
+class LineLinter(Linter):
+    """
+    A :class:`LineLinter` must implement :func:`lint_line`, which looks at
+    the given line from a file and calls :func:`add_warning` for any lint
+    issues found.
+    """
+    def lint(self, path):
+        if os.path.isfile(path):
+            with open(path, 'r') as f:
+                for line_no, line in enumerate(f):
+                    self.lint_line(path, line_no+1, line)
+
+    def lint_line(self, path, line_no, line):
+        pass
+
+class RegexpLinter(LineLinter):
+    """
+    A :class:`RegexpLinter` produces the given warning message for
+    all lines matching the given regular expression.
+    """
+    def __init__(self, regex, message):
+        LineLinter.__init__(self)
+        self.re = re.compile(regex)
+        self.message = message
+
+    def lint_line(self, path, line_no, line):
+        if self.re.search(line):
+            w = Warning(path=path, line_no=line_no, line_content=line[:-1],
+                        message=self.message)
+            self.add_warning(w)
+
+def run_linters(linters: List[Linter],
+                subdir: str = '.') -> None:
+    import argparse
+    parser = argparse.ArgumentParser()
+    parser.add_argument('base', help='Base commit')
+    parser.add_argument('head', help='Head commit')
+    args = parser.parse_args()
+
+    for path in get_changed_files(args.base, args.head, subdir):
+        if path.startswith('.gitlab/linters'):
+            continue
+        for linter in linters:
+            linter.lint(path)
+
+    warnings = [warning
+                for linter in linters
+                for warning in linter.warnings]
+    warnings = sorted(warnings, key=lambda x: (x.path, x.line_no))
+    for w in warnings:
+        lint_failure(w.path, w.line_no, w.line_content, w.message)
+
+    if len(warnings) > 0:
+        sys.exit(1)
diff --git a/.gitlab/win32-init.sh b/.gitlab/win32-init.sh
new file mode 100644
index 0000000000..dce9be8d16
--- /dev/null
+++ b/.gitlab/win32-init.sh
@@ -0,0 +1,34 @@
+#!/bin/bash
+
+set -e
+
+toolchain=`pwd`/toolchain
+PATH="$toolchain/bin:/mingw64/bin:$PATH"
+
+if [ -d "`pwd`/cabal-cache" ]; then
+    cp -Rf cabal-cache $APPDATA/cabal
+fi
+
+if [ ! -e $toolchain/bin/ghc ]; then
+    curl https://downloads.haskell.org/~ghc/$GHC_VERSION/ghc-$GHC_VERSION-x86_64-unknown-mingw32.tar.xz | tar -xJ
+    mv ghc-$GHC_VERSION toolchain
+fi
+
+if [ ! -e $toolchain/bin/cabal ]; then
+    curl https://www.haskell.org/cabal/release/cabal-install-2.2.0.0/cabal-install-2.2.0.0-i386-unknown-mingw32.zip > /tmp/cabal.zip
+    unzip /tmp/cabal.zip
+    mv cabal.exe $toolchain/bin
+fi
+
+if [ ! -e $toolchain/bin/happy ]; then
+    cabal update
+    cabal install happy
+    cp $APPDATA/cabal/bin/happy $toolchain/bin
+fi
+
+if [ ! -e $toolchain/bin/alex ]; then
+    cabal update
+    cabal install alex
+    cp $APPDATA/cabal/bin/alex $toolchain/bin
+fi
+