8282429: StringBuilder/StringBuffer.toString() skip compressing for UTF16 strings

src/java.base/share/classes/java/lang/AbstractStringBuilder.java

@@ -70,7 +70,7 @@ abstract class AbstractStringBuilder implements Appendable, CharSequence {
     /**
      *  The attribute indicates {@code value} is in UTF16 but may be compressible.
      *  An inflated byte array becomes compressible only when those non-latin1 chars are deleted.
-     *  Therefore, sett this attribute in all methods that delete chars.
+     *  Therefore, set this attribute in all methods that delete chars.
      */
     boolean maybeLatin1 = false;
 

test/micro/org/openjdk/bench/java/lang/StringBuilderToString.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.bench.java.lang;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@State(Scope.Thread)
+@Warmup(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
+@Measurement(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
+@Fork(3)
+public class StringBuilderToString {
+    @Param({"128", "256", "1024"})
+    public int MIXED_SIZE;
+
+    /**
+     * This microbench simulates how java.io.BufferedReader uses StringBuilder.
+     */
+    @Benchmark
+    public String toStringWithMixedChars() {
+        StringBuilder sb = new StringBuilder(MIXED_SIZE);
+        for (int i = 0; i < MIXED_SIZE - 4; ++i) {
+            sb.append('a');
+        }
+        sb.append('\u3042'); // can't be encoded in latin-1,
+        return sb.toString();
+    }
+}

test/micro/org/openjdk/bench/java/lang/StringBuilders.java

@@ -205,21 +205,6 @@ public String toStringCharWithString16() {
         return result.toString();
     }
 
-    @Param({"128", "256", "1024"})
-    public int MIXED_SIZE;
-
-    /**
-     * This microbench simulates how java.io.BufferedReader uses StringBuilder.
-     */
-    @Benchmark
-    public String toStringWithMixedChars() {
-        StringBuilder sb = new StringBuilder(MIXED_SIZE);
-        for (int i = 0; i < MIXED_SIZE - 4; ++i) {
-            sb.append('a');
-        }
-        sb.append('\u3042'); // can't be encoded in latin-1,
-        return sb.toString();
-    }
 
     @Benchmark
     public String toStringCharWithInt8() {