Add String.indexOf() benchmark.

Test: vogar --benchmark art/benchmark/string-indexof/src/StringIndexOfBenchmark.java
Change-Id: I57c8c9c7ede2b0e86a6142e713b4e8be094c82ce
diff --git a/benchmark/string-indexof/info.txt b/benchmark/string-indexof/info.txt
new file mode 100644
index 0000000..cc04217
--- /dev/null
+++ b/benchmark/string-indexof/info.txt
@@ -0,0 +1 @@
+Benchmarks for repeating String.indexOf() instructions in a loop.
diff --git a/benchmark/string-indexof/src/StringIndexOfBenchmark.java b/benchmark/string-indexof/src/StringIndexOfBenchmark.java
new file mode 100644
index 0000000..481a27a
--- /dev/null
+++ b/benchmark/string-indexof/src/StringIndexOfBenchmark.java
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+public class StringIndexOfBenchmark {
+    public static final String string36 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";  // length = 36
+
+    public void timeIndexOf0(int count) {
+        final char c = '0';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOf1(int count) {
+        final char c = '1';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOf2(int count) {
+        final char c = '2';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOf3(int count) {
+        final char c = '3';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOf4(int count) {
+        final char c = '4';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOf7(int count) {
+        final char c = '7';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOf8(int count) {
+        final char c = '8';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOfF(int count) {
+        final char c = 'F';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOfG(int count) {
+        final char c = 'G';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOfV(int count) {
+        final char c = 'V';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOfW(int count) {
+        final char c = 'W';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    public void timeIndexOf_(int count) {
+        final char c = '_';
+        String s = string36;
+        for (int i = 0; i < count; ++i) {
+            $noinline$indexOf(s, c);
+        }
+    }
+
+    static int $noinline$indexOf(String s, char c) {
+        if (doThrow) { throw new Error(); }
+        return s.indexOf(c);
+    }
+
+    public static boolean doThrow = false;
+}