8279833: Loop optimization issue in String.encodeUTF8_UTF16

Reviewed-by: stuefe
Backport-of: ff8565931115d581afff679ea85b1a2d80c03b99

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2022, Oracle and/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
@@ -921,14 +921,17 @@ private static byte[] encodeUTF8_UTF16(byte[] val, boolean doReplace) {
         int sp = 0;
         int sl = val.length >> 1;
         byte[] dst = new byte[sl * 3];
-        char c;
-        while (sp < sl && (c = StringUTF16.getChar(val, sp)) < '\u0080') {
+        while (sp < sl) {
             // ascii fast loop;
+            char c = StringUTF16.getChar(val, sp);
+            if (c >= '\u0080') {
+                break;
+            }
             dst[dp++] = (byte)c;
             sp++;
         }
         while (sp < sl) {
-            c = StringUTF16.getChar(val, sp++);
+            char c = StringUTF16.getChar(val, sp++);
             if (c < 0x80) {
                 dst[dp++] = (byte)c;
             } else if (c < 0x800) {

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

@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2021, 2022, Oracle and/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.*;
+import org.openjdk.jmh.infra.Blackhole;
+
+import java.nio.charset.Charset;
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Fork(value = 3)
+@Warmup(iterations = 5, time = 2)
+@Measurement(iterations = 5, time = 3)
+@State(Scope.Thread)
+public class StringEncode {
+
+    @Param({"US-ASCII", "ISO-8859-1", "UTF-8", "MS932", "ISO-8859-6"})
+    private String charsetName;
+    private Charset charset;
+    private String asciiString;
+    private String utf16String;
+    private String longUtf16String;
+    private String longUtf16StartString;
+
+    @Setup
+    public void setup() {
+        charset = Charset.forName(charsetName);
+        asciiString = "ascii string";
+        utf16String = "UTF-\uFF11\uFF16 string";
+        longUtf16String =
+                 " Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aliquam ac sem eu\n" +
+                 " urna egestas placerat. Etiam finibus ipsum nulla, non mattis dolor cursus a.\n" +
+                 " Nulla nec nisl consectetur, lacinia neque id, accumsan ante. Curabitur et\n" +
+                 " sapien in magna porta ultricies. Sed vel pellentesque nibh. Pellentesque dictum\n" +
+                 " dignissim diam eu ultricies. Class aptent taciti sociosqu ad litora torquent\n" +
+                 " per conubia nostra, per inceptos himenaeos. Suspendisse erat diam, fringilla\n" +
+                 " sed massa sed, posuere viverra orci. Suspendisse tempor libero non gravida\n" +
+                 " efficitur. Vivamus lacinia risus non orci viverra, at consectetur odio laoreet.\n" +
+                 " Suspendisse potenti.\n" +
+                 "\n" +
+                 " Phasellus vel nisi iaculis, accumsan quam sed, bibendum eros. Sed venenatis\n" +
+                 " nulla tortor, et eleifend urna sodales id. Nullam tempus ac metus sit amet\n" +
+                 " sollicitudin. Nam sed ex diam. Praesent vitae eros et neque condimentum\n" +
+                 " consectetur eget non tortor. Praesent bibendum vel felis nec dignissim.\n" +
+                 " Maecenas a enim diam. Suspendisse quis ligula at nisi accumsan lacinia id\n" +
+                 " hendrerit sapien. Donec aliquam mattis lectus eu ultrices. Duis eu nisl\n" +
+                 " euismod, blandit mauris vel, placerat urna. Etiam malesuada enim purus,\n" +
+                 " tristique mollis odio blandit quis. Vivamus posuere.\n" +
+                 " \uFF11";
+        longUtf16StartString =
+                 " \uFF11" +
+                 " Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aliquam ac sem eu\n" +
+                 " urna egestas placerat. Etiam finibus ipsum nulla, non mattis dolor cursus a.\n" +
+                 " Nulla nec nisl consectetur, lacinia neque id, accumsan ante. Curabitur et\n" +
+                 " sapien in magna porta ultricies. Sed vel pellentesque nibh. Pellentesque dictum\n" +
+                 " dignissim diam eu ultricies. Class aptent taciti sociosqu ad litora torquent\n" +
+                 " per conubia nostra, per inceptos himenaeos. Suspendisse erat diam, fringilla\n" +
+                 " sed massa sed, posuere viverra orci. Suspendisse tempor libero non gravida\n" +
+                 " efficitur. Vivamus lacinia risus non orci viverra, at consectetur odio laoreet.\n" +
+                 " Suspendisse potenti.\n" +
+                 "\n" +
+                 " Phasellus vel nisi iaculis, accumsan quam sed, bibendum eros. Sed venenatis\n" +
+                 " nulla tortor, et eleifend urna sodales id. Nullam tempus ac metus sit amet\n" +
+                 " sollicitudin. Nam sed ex diam. Praesent vitae eros et neque condimentum\n" +
+                 " consectetur eget non tortor. Praesent bibendum vel felis nec dignissim.\n" +
+                 " Maecenas a enim diam. Suspendisse quis ligula at nisi accumsan lacinia id\n" +
+                 " hendrerit sapien. Donec aliquam mattis lectus eu ultrices. Duis eu nisl\n" +
+                 " euismod, blandit mauris vel, placerat urna. Etiam malesuada enim purus,\n" +
+                 " tristique mollis odio blandit quis. Vivamus posuere.\n";
+    }
+
+    @Benchmark
+    public byte[] encodeAsciiCharsetName() throws Exception {
+        return asciiString.getBytes(charset);
+    }
+
+    @Benchmark
+    public byte[] encodeAscii() throws Exception {
+        return asciiString.getBytes(charset);
+    }
+
+    @Benchmark
+    public void encodeMix(Blackhole bh) throws Exception {
+        bh.consume(asciiString.getBytes(charset));
+        bh.consume(utf16String.getBytes(charset));
+    }
+
+    @Benchmark
+    public byte[] encodeUTF16LongEnd() throws Exception {
+        return longUtf16String.getBytes(charset);
+    }
+
+    @Benchmark
+    public byte[] encodeUTF16LongStart() throws Exception {
+        return longUtf16StartString.getBytes(charset);
+    }
+
+    @Benchmark
+    public byte[] encodeUTF16() throws Exception {
+        return utf16String.getBytes(charset);
+    }
+}