Add script/bench-history.sh
diff --git a/script/bench-history.sh b/script/bench-history.sh
new file mode 100755
index 0000000..689550e
--- /dev/null
+++ b/script/bench-history.sh
@@ -0,0 +1,44 @@
+#!/bin/bash -eu
+# Copyright 2019 The Wuffs Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# ----------------
+
+# This script measures Wuffs benchmarks over recent commits. For example:
+#
+# PACKAGE=deflate FOCUS=wuffs_deflate_decode_100k script/bench-history.sh
+
+num_commits=${NUM_COMMITS:-100}
+cc=${CC:-gcc}
+package=${PACKAGE:-gif}
+focus=${FOCUS:-wuffs_gif_decode_1000k_full_init}
+iterscale=${ITERSCALE:-50}
+reps=${REPS:-20}
+
+# ----
+
+save=`git log -1 --pretty=format:"%H"`
+
+i=0
+while [ $i -lt $num_commits ]; do
+ this_hash=`git log -1 --pretty=format:"%h"`
+ $cc -O3 -o bench-history.out test/c/std/$package.c
+ this_metric=`./bench-history.out -bench -focus=$focus -iterscale=$iterscale -reps=$reps | benchstat /dev/stdin | sed -ne '/^name.*speed$/,$ p' | grep $focus`
+ echo $this_hash $this_metric
+ git checkout --quiet HEAD^
+ i=$((i + 1))
+done
+
+rm -f ./bench-history.out
+git checkout --quiet $save
