[BOLT] create an LLVM OpenMP maintenance script

LLVM OpenMP is managed with other LLVM packages altogether in the official
repository while BOLT depends on only LLVM OpenMP.  The newly created
utility script cherry-picks commits that change LLVM OpenMP files from the
official LLVM repository.

Author: shintaro-iwasaki

maint/update-llvmomp.sh

@@ -0,0 +1,69 @@
+#!/bin/bash
+
+boltpath="$(pwd)"
+
+# Switch to the llvmomp branch
+git checkout llvmomp
+
+# Get the latest llvm-project
+if [ -d "${boltpath}/llvm-project" ]; then
+  cd "${boltpath}/llvm-project"
+  git pull
+  git checkout master
+else
+  git clone https://github.com/llvm/llvm-project.git "${boltpath}/llvm-project"
+fi
+
+# Find the corresponding latest commit of the llvmomp branch
+cd "$boltpath"
+if [ x"$(git log HEAD~..HEAD | grep cherry-pick:)" = x ]; then
+  # The last commit in llvm-mirror: d69d1aa131b4cf339bfac116e50da33a5f94b861
+  commit_id_begin="d69d1aa131b4cf339bfac116e50da33a5f94b861"
+else
+  # Extract the first "cherry-pick:" comment from the latest log.
+  commit_id_begin=$(git log HEAD~..HEAD | grep -Po "cherry-pick: \K[\w]+" | head -n 1)
+fi
+echo "last commit: $commit_id_begin"
+
+rm -rf "${boltpath}/llvm-project/patch_diff.tmp"
+rm -rf "${boltpath}/llvm-project/patch_log.tmp"
+rm -rf "${boltpath}/llvm-project/patch_changed_list.tmp"
+
+cd "${boltpath}/llvm-project/openmp"
+
+for commit_id in $(git rev-list --reverse ${commit_id_begin}..HEAD); do
+  echo "checking $commit_id"
+  # Check if OpenMP part is changed.
+  if [ x"$(git diff --name-only --relative ${commit_id}~..${commit_id})" != x ]; then
+    echo "\n#########################\n"
+    # Create a diff file
+    git diff --relative ${commit_id}~..${commit_id} > "${boltpath}/llvm-project/patch_diff.tmp"
+    # Create a list of changed files
+    git diff --name-only --relative ${commit_id}~..${commit_id} > "${boltpath}/llvm-project/patch_changed_list.tmp"
+    # Create a log file for this
+    git log ${commit_id}~..${commit_id} --pretty=format:"%B" > "${boltpath}/llvm-project/patch_log.tmp"
+    echo "" >> "${boltpath}/llvm-project/patch_log.tmp"
+    echo "cherry-pick: $commit_id" >> "${boltpath}/llvm-project/patch_log.tmp"
+    echo "https://github.com/llvm/llvm-project/commit/${commit_id}" >> "${boltpath}/llvm-project/patch_log.tmp"
+    author_info="$(git show --pretty="%aN <%aE>" $commit_id | head -n 1)"
+    timestamp_info="$(git show --pretty="%cd" $commit_id | head -n 1)"
+
+    # Go to the BOLT repository
+    cd "${boltpath}"
+
+    # Apply the diff to the llvmomp branch
+    git apply "${boltpath}/llvm-project/patch_diff.tmp"
+    for changed_file in $(cat "${boltpath}/llvm-project/patch_changed_list.tmp"); do
+      git add $changed_file
+    done
+
+    # Commit it.
+    cat "${boltpath}/llvm-project/patch_log.tmp"
+    git commit -F "${boltpath}/llvm-project/patch_log.tmp" --author="$author_info" --date="$timestamp_info"
+
+    # Go to the llvm-project repository.
+    cd "${boltpath}/llvm-project/openmp"
+  fi
+done
+
+echo "complete"