utils/release: Add merge-git.sh

Summary:
This script allows you to use git to backport a commit to a stable
branch while generating the exact same commit message (ignoring
whitespace) that you would get from using the merge.sh script with svn.

Reviewers: hansw

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D47760

llvm-svn: 334568

utils/release/merge-git.sh

@@ -0,0 +1,92 @@
+#!/bin/bash
+#===-- merge-git.sh - Merge commit to the stable branch --------------------===#
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License.
+#
+#===------------------------------------------------------------------------===#
+#
+# This script will merge an svn revision to a git repo using git-svn while
+# preserving the svn commit message.
+# 
+# NOTE: This script has only been tested with the per-project git repositories
+# and not with the monorepo.
+#
+# In order to use this script, you must:
+# 1) Checkout the stable branch you would like to merge the revision into.
+# 2) Correctly configure the branch as an svn-remote by adding the following to
+# your .git/config file for your git repo (replace xy with the major/minor
+# version of the release branch. e.g. release_50 or release_60):
+#
+#[svn-remote "release_xy"]
+#url = https://llvm.org/svn/llvm-project/llvm/branches/release_xy
+#fetch = :refs/remotes/origin/release_xy
+#
+# Once the script completes successfully, you can push your changes with
+# git-svn dcommit
+#
+#===------------------------------------------------------------------------===#
+
+
+usage() {
+    echo "usage: `basename $0` [OPTIONS]"
+    echo "  -rev NUM       The revision to merge into the project"
+}
+
+while [ $# -gt 0 ]; do
+    case $1 in
+        -rev | --rev | -r )
+            shift
+            rev=$1
+            ;;
+        -h | -help | --help )
+            usage
+            ;;
+        * )
+            echo "unknown option: $1"
+            echo ""
+            usage
+            exit 1
+            ;;
+    esac
+    shift
+done
+
+if [ -z "$rev" ]; then
+    echo "error: need to specify a revision"
+    echo
+    usage
+    exit 1
+fi
+
+# Rebuild revision map
+git svn find-rev r$rev origin/master &>/dev/null
+
+git_hash=`git svn find-rev r$rev origin/master`
+
+if [ -z "$git_hash" ]; then
+    echo "error: could not determine git commit for r$rev"
+    exit 1
+fi
+
+commit_msg=`svn log -r $rev https://llvm.org/svn/llvm-project/`
+ammend="--amend"
+
+git cherry-pick $git_hash
+if [ $? -ne 0 ]; then
+  echo ""
+  echo "** cherry-pick failed enter 'e' to exit or 'c' when you have finished resolving the conflicts:"
+  read option
+  case $option in
+    c)
+      ammend=""
+      ;;
+    *)
+      exit 1
+      ;;
+  esac
+fi
+         
+git commit $ammend -m "Merging r$rev:" -m "$commit_msg"