1 /*
   2  * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test
  26  * @bug 8015499
  27  * @summary javac, Gen is generating extra checkcast instructions in some corner cases
  28  * @modules jdk.jdeps/com.sun.tools.classfile
  29  *          jdk.compiler/com.sun.tools.javac.util
  30  * @run main DoubleCastTest
  31  */
  32 
  33 import java.util.List;
  34 import java.util.ArrayList;
  35 import com.sun.tools.classfile.*;
  36 import com.sun.tools.javac.util.Assert;
  37 
  38 public class DoubleCastTest {
  39     class C {
  40         Object x;
  41         Object m() { return null; }
  42         void m1(byte[] b) {}
  43         void m2() {
  44             Object o;
  45             Object[] os = null;
  46             m1((byte[])(o = null));
  47             m1((byte[])o);
  48             m1((byte[])(o == null ? o : o));
  49             m1((byte[])m());
  50             m1((byte[])os[0]);
  51             m1((byte[])this.x);
  52             m1((byte[])((byte []) (o = null)));
  53         }
  54     }
  55 
  56     public static void main(String... cmdline) throws Exception {
  57 
  58         ClassFile cls = ClassFile.read(DoubleCastTest.class.getResourceAsStream("DoubleCastTest$C.class"));
  59         for (Method m: cls.methods)
  60             check(m);
  61     }
  62 
  63     static void check(Method m) throws Exception {
  64         boolean last_is_cast = false;
  65         int last_ref = 0;
  66         Code_attribute ea = (Code_attribute)m.attributes.get(Attribute.Code);
  67         for (Instruction i : ea.getInstructions()) {
  68             if (i.getOpcode() == Opcode.CHECKCAST) {
  69                 Assert.check
  70                     (!(last_is_cast && last_ref == i.getUnsignedShort(1)),
  71                      "Double cast found - Test failed");
  72                 last_is_cast = true;
  73                 last_ref = i.getUnsignedShort(1);
  74             } else {
  75                 last_is_cast = false;
  76             }
  77         }
  78     }
  79 }