8024039: javac, previous solution for JDK-8022186 was incorrect

Reviewed-by: jjg

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

@@ -49,7 +49,6 @@ import static com.sun.tools.javac.code.Kinds.*;
 import static com.sun.tools.javac.code.TypeTag.*;
 import static com.sun.tools.javac.jvm.ByteCodes.*;
 import static com.sun.tools.javac.tree.JCTree.Tag.*;
-import javax.lang.model.type.TypeKind;
 
 /** This pass translates away some syntactic sugar: inner classes,
  *  class literals, assertions, foreach loops, etc.
@@ -3830,16 +3829,27 @@ public class Lower extends TreeTranslator {
 
     @Override
     public void visitTry(JCTry tree) {
+        if (tree.resources.isEmpty()) {
             /* special case of try without catchers and with finally emtpy.
              * Don't give it a try, translate only the body.
              */
-        if (tree.resources.isEmpty()) {
             if (tree.catchers.isEmpty() &&
                 tree.finalizer.getStatements().isEmpty()) {
                 result = translate(tree.body);
+            } else {
+                /* also if the body is empty we only need to generate the finalizer
+                 * provided that it's not empty.
+                 */
+                if (tree.body.getStatements().isEmpty()) {
+                    if (tree.finalizer.getStatements().isEmpty()) {
+                        result = translate(tree.body);
+                    } else {
+                        result = translate(tree.finalizer);
+                    }
                 } else {
                     super.visitTry(tree);
                 }
+            }
         } else {
             result = makeTwrTry(tree);
         }

langtools/src/share/classes/com/sun/tools/javac/jvm/Gen.java

@@ -1478,15 +1478,9 @@ public class Gen extends JCTree.Visitor {
             code.statBegin(TreeInfo.endPos(body));
             genFinalizer(env);
             code.statBegin(TreeInfo.endPos(env.tree));
-            Chain exitChain;
+            Chain exitChain = code.branch(goto_);
-            if (startpc != endpc) {
-                exitChain = code.branch(goto_);
-            } else {
-                exitChain = code.branch(dontgoto);
-            }
             endFinalizerGap(env);
-            if (startpc != endpc) {
+            if (startpc != endpc) for (List<JCCatch> l = catchers; l.nonEmpty(); l = l.tail) {
-                for (List<JCCatch> l = catchers; l.nonEmpty(); l = l.tail) {
                 // start off with exception on stack
                 code.entryPoint(stateTry, l.head.param.sym.type);
                 genCatch(l.head, env, startpc, endpc, gaps);
@@ -1498,7 +1492,6 @@ public class Gen extends JCTree.Visitor {
                 }
                 endFinalizerGap(env);
             }
-
             if (hasFinalizer) {
                 // Create a new register segement to avoid allocating
                 // the same variables in finalizers and other statements.
@@ -1555,7 +1548,6 @@ public class Gen extends JCTree.Visitor {
                     code.markDead();
                 }
             }
-            }
             // Resolve all breaks.
             code.resolve(exitChain);
 

langtools/test/tools/javac/T8024039/NoDeadCodeGenerationOnTrySmtTest.java

@@ -0,0 +1,124 @@
+/*
+ * 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 8024039
+ * @summary javac, previous solution for JDK-8022186 was incorrect
+ * @library /tools/javac/lib
+ * @build ToolBox
+ * @run main NoDeadCodeGenerationOnTrySmtTest
+ */
+
+import java.io.File;
+import java.nio.file.Paths;
+
+import com.sun.tools.classfile.ClassFile;
+import com.sun.tools.classfile.Code_attribute;
+import com.sun.tools.classfile.Code_attribute.Exception_data;
+import com.sun.tools.classfile.Method;
+import com.sun.tools.javac.util.Assert;
+
+public class NoDeadCodeGenerationOnTrySmtTest {
+
+    static final String testSource =
+        "public class Test {\n" +
+        "    void m1(int arg) {\n" +
+        "        synchronized (new Integer(arg)) {\n" +
+        "            {\n" +
+        "                label0:\n" +
+        "                do {\n" +
+        "                    break label0;\n" +
+        "                } while (arg != 0);\n" +
+        "            }\n" +
+        "        }\n" +
+        "    }\n" +
+
+        "    void m2(int arg) {\n" +
+        "        synchronized (new Integer(arg)) {\n" +
+        "            {\n" +
+        "                label0:\n" +
+        "                {\n" +
+        "                    break label0;\n" +
+        "                }\n" +
+        "            }\n" +
+        "        }\n" +
+        "    }\n" +
+        "}";
+
+    static final int[][] expectedExceptionTable = {
+    //  {from,         to,         target,      type},
+        {11,           13,         16,          0},
+        {16,           19,         16,          0}
+    };
+
+    static final String[] methodsToLookFor = {"m1", "m2"};
+
+    public static void main(String[] args) throws Exception {
+        new NoDeadCodeGenerationOnTrySmtTest().run();
+    }
+
+    void run() throws Exception {
+        compileTestClass();
+        checkClassFile(new File(Paths.get(System.getProperty("user.dir"),
+                "Test.class").toUri()), methodsToLookFor);
+    }
+
+    void compileTestClass() throws Exception {
+        ToolBox.JavaToolArgs javacSuccessArgs =
+                new ToolBox.JavaToolArgs().setSources(testSource);
+        ToolBox.javac(javacSuccessArgs);
+    }
+
+    void checkClassFile(final File cfile, String[] methodsToFind) throws Exception {
+        ClassFile classFile = ClassFile.read(cfile);
+        int numberOfmethodsFound = 0;
+        for (String methodToFind : methodsToFind) {
+            for (Method method : classFile.methods) {
+                if (method.getName(classFile.constant_pool).equals(methodToFind)) {
+                    numberOfmethodsFound++;
+                    Code_attribute code = (Code_attribute) method.attributes.get("Code");
+                    Assert.check(code.exception_table_langth == expectedExceptionTable.length,
+                            "The ExceptionTable found has a length different to the expected one");
+                    int i = 0;
+                    for (Exception_data entry: code.exception_table) {
+                        Assert.check(entry.start_pc == expectedExceptionTable[i][0] &&
+                                entry.end_pc == expectedExceptionTable[i][1] &&
+                                entry.handler_pc == expectedExceptionTable[i][2] &&
+                                entry.catch_type == expectedExceptionTable[i][3],
+                                "Exception table entry at pos " + i + " differ from expected.");
+                        i++;
+                    }
+                }
+            }
+        }
+        Assert.check(numberOfmethodsFound == 2, "Some seek methods were not found");
+    }
+
+    void error(String msg) {
+        throw new AssertionError(msg);
+    }
+
+}