1 /*
 2  * Copyright (c) 2024, 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 import jdk.incubator.code.bytecode.impl.BranchCompactor;
25 import jdk.internal.classfile.components.ClassPrinter;
26 import org.junit.jupiter.api.Assertions;
27 import org.junit.jupiter.api.Test;
28 
29 import java.lang.classfile.Attributes;
30 import java.lang.classfile.ClassFile;
31 import java.lang.classfile.Instruction;
32 import java.lang.constant.ClassDesc;
33 import java.lang.constant.ConstantDescs;
34 import java.util.List;
35 
36 import static java.lang.classfile.Opcode.*;
37 
38 /*
39  * @test
40  * @modules jdk.incubator.code
41  * @modules java.base/jdk.internal.classfile.components
42  * @modules jdk.incubator.code/jdk.incubator.code.bytecode.impl
43  * @enablePreview
44  * @run junit TestBranchCompactor
45  */
46 public class TestBranchCompactor {
47 
48     @Test
49     public void testBranchCompactor() {
50         var cc = ClassFile.of(ClassFile.StackMapsOption.DROP_STACK_MAPS);
51         var clm = cc.parse(cc.build(ClassDesc.of("c"), clb -> clb.withMethodBody("m", ConstantDescs.MTD_void, 0,
52                 cb -> cb.transforming(new BranchCompactor(), cob -> {
53                     var l = cob.newLabel();
54                     cob.goto_(l) //compact
55                        .lineNumber(1)
56                        .labelBinding(l)
57                        .nop();
58 
59                     l = cob.newLabel();
60                     cob.goto_w(l) //compact
61                        .lineNumber(2)
62                        .labelBinding(l);
63 
64                     l = cob.newLabel();
65                     cob.goto_(l) //compact
66                        .labelBinding(l);
67 
68                     cob.iconst_0();
69                     l = cob.newLabel();
70                     cob.ifeq(l) //do not compact
71                        .labelBinding(l);
72 
73                     l = cob.newLabel();
74                     cob.goto_(l) //do not compact
75                        .nop()
76                        .labelBinding(l)
77                        .return_();
78                 }))));
79         var code = clm.methods().get(0).code().get();
80         ClassPrinter.toYaml(code, ClassPrinter.Verbosity.TRACE_ALL, System.out::print);
81         Assertions.assertEquals(
82                 List.of(NOP, ICONST_0, IFEQ, GOTO, NOP, RETURN), code.elementList().stream().mapMulti((e, ec) -> {if (e instanceof Instruction i) ec.accept(i.opcode());}).toList()
83         );
84         Assertions.assertEquals(2, code.findAttribute(Attributes.lineNumberTable()).get().lineNumbers().size());
85     }
86 }