Merge branch 'feature/ci' into 'master'

Implement a CI system

Closes #89

See merge request !163

.gitlab-ci.yml

+---
+variables:
+# work around https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/2148
+# value should be "recursive" without workaround
+  GIT_SUBMODULE_STRATEGY: none
+
+before_script:
+- echo "Running make concurrently with $(nproc) cores, where possibly"
+# work around https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/2148
+- git submodule sync --recursive
+- git submodule update --init --recursive
+# end workaround
+# make sure we can apply the patches
+- git submodule foreach --recursive git reset --hard HEAD
+- patches/apply_patches.sh
+# detect number of processors, but make sure never to run with -j"", as the
+# build host would likely run out of memory
+- ": ${DUNECI_PARALLEL:=$(nproc || echo 1)}"
+- export DUNECI_PARALLEL
+
+git--gcc:
+  image: registry.dune-project.org/joe/dune-perftool-ci/perftool-base:git
+  script: duneci-standard-test
+
+git--clang:
+  image: registry.dune-project.org/joe/dune-perftool-ci/perftool-base:git
+  script: duneci-standard-test --opts=/duneci/opts.clang
+
+git--pacxx:
+  image: registry.dune-project.org/joe/dune-perftool-ci/pacxx-perftool-base:git
+  script: duneci-standard-test --opts=/duneci/opts.pacxx

dune/perftool/common/opcounter.hh

@@ -116,7 +116,12 @@ namespace oc {
 
     F _v;
 
-    struct Counters {
+    // The alignment is necessary to work around
+    // https://bugs.llvm.org/show_bug.cgi?id=34219:
+    // "SLP vectorizer: aligned store to unaligned address"
+    // The bug is present in 3.8.0 (tags/RELEASE_380/final 263969) and in
+    // clang version 6.0.0 (trunk 310993)
+    struct alignas(16) Counters {
 
       size_type addition_count;
       size_type multiplication_count;