1 /* 2 * Copyright (c) 2020, 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 8237528 27 * @summary Verify there are no unnecessary checkcasts and conditions generated 28 * for the pattern matching in instanceof. 29 * @modules jdk.jdeps/com.sun.tools.classfile 30 * @compile --enable-preview -source ${jdk.version} NoUnnecessaryCast.java 31 * @run main/othervm --enable-preview NoUnnecessaryCast 32 */ 33 34 import java.io.File; 35 import java.io.IOException; 36 37 import com.sun.tools.classfile.Attribute; 38 import com.sun.tools.classfile.ClassFile; 39 import com.sun.tools.classfile.Code_attribute; 40 import com.sun.tools.classfile.Code_attribute.InvalidIndex; 41 import com.sun.tools.classfile.ConstantPool; 42 import com.sun.tools.classfile.ConstantPoolException; 43 import com.sun.tools.classfile.Descriptor.InvalidDescriptor; 44 import com.sun.tools.classfile.Instruction; 45 import com.sun.tools.classfile.Method; 46 import java.util.Arrays; 47 import java.util.stream.Collectors; 48 import java.util.stream.StreamSupport; 49 50 public class NoUnnecessaryCast { 51 public static void main(String[] args) 52 throws IOException, ConstantPoolException, InvalidDescriptor, InvalidIndex { 53 new NoUnnecessaryCast() 54 .checkClassFile(new File(System.getProperty("test.classes", "."), 55 NoUnnecessaryCast.class.getName() + ".class")); 56 } 57 58 void checkClassFile(File file) 59 throws IOException, ConstantPoolException, InvalidDescriptor, InvalidIndex { 60 ClassFile classFile = ClassFile.read(file); 61 ConstantPool constantPool = classFile.constant_pool; 62 63 Method method = Arrays.stream(classFile.methods) 64 .filter(m -> getName(m, constantPool) 65 .equals("test")) 66 .findAny() 67 .get(); 68 String expectedInstructions = """ 69 aload_1 70 astore_3 71 aload_3 72 instanceof 73 ifeq 74 aload_3 75 checkcast 76 astore_2 77 aload_2 78 invokevirtual 79 ifeq 80 iconst_1 81 goto 82 iconst_0 83 ireturn 84 """; 85 Code_attribute code = (Code_attribute) method.attributes 86 .get(Attribute.Code); 87 String actualInstructions = printCode(code); 88 if (!expectedInstructions.equals(actualInstructions)) { 89 throw new AssertionError("Unexpected instructions found:\n" + 90 actualInstructions); 91 } 92 } 93 94 String printCode(Code_attribute code) { 95 return StreamSupport.stream(code.getInstructions().spliterator(), false) 96 .map(Instruction::getMnemonic) 97 .collect(Collectors.joining("\n", "", "\n")); 98 } 99 100 String getName(Method m, ConstantPool constantPool) { 101 try { 102 return m.getName(constantPool); 103 } catch (ConstantPoolException ex) { 104 throw new IllegalStateException(ex); 105 } 106 } 107 108 boolean test(Object o) { 109 return o instanceof String s && s.isEmpty(); 110 } 111 }