6181889: Empty try/finally results in bytecodes being generated

Reviewed-by: mcimadamore

src/share/classes/com/sun/tools/javac/comp/Lower.java

@@ -3807,8 +3807,16 @@ public class Lower extends TreeTranslator {
 
     @Override
     public void visitTry(JCTry tree) {
+        /* special case of try without catchers and with finally emtpy.
+         * Don't give it a try, translate only the body.
+         */
         if (tree.resources.isEmpty()) {
-            super.visitTry(tree);
+            if (tree.catchers.isEmpty() &&
+                tree.finalizer.getStatements().isEmpty()) {
+                result = translate(tree.body);
+            } else {
+                super.visitTry(tree);
+            }
         } else {
             result = makeTwrTry(tree);
         }

test/tools/javac/T6181889/EmptyFinallyTest.java

+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.nio.file.Paths;
+
+/*
+ * Copyright (c) 2013, 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.
+ */
+
+/*
+ * @test
+ * @bug 6181889
+ * @summary Empty try/finally results in bytecodes being generated
+ */
+
+public class EmptyFinallyTest {
+    private static final String assertionErrorMsg =
+            "No \"Exception table\" should be generated in this case";
+
+    public static void main(String[] args) {
+        new EmptyFinallyTest().run();
+    }
+
+    void run() {
+        check("-c", Paths.get(System.getProperty("test.classes"),
+                "EmptyFinally.class").toString());
+    }
+
+    void check(String... params) {
+        StringWriter s;
+        String out;
+        try (PrintWriter pw = new PrintWriter(s = new StringWriter())) {
+            com.sun.tools.javap.Main.run(params, pw);
+            out = s.toString();
+        }
+        if (out.contains("Exception table")) {
+            throw new AssertionError(assertionErrorMsg);
+        }
+    }
+}
+
+class EmptyFinally {
+    void m() {
+        try {
+            System.out.println("EMPTY TRY!");
+        } finally {}
+    }
+}