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gerrit-public.fairphone.software / platform / libcore / 319a3b994703aac84df7bcde272adfcb3cdbbbf0 / . / jdk / src / share / classes / sun / tools / asm / Label.java
blob: 9c892d2c6803827cfcec7fd11a88592856aee450 [file] [log] [blame]
J. Duke319a3b92007-12-01 00:00:00 +0000[diff] [blame^]1/*
2 * Copyright 1994-2004 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26package sun.tools.asm;
27
28import sun.tools.java.MemberDefinition;
29import java.io.OutputStream;
30
31/**
32 * A label instruction. This is a 0 size instruction.
33 * It is the only valid target of a branch instruction.
34 *
35 * WARNING: The contents of this source file are not part of any
36 * supported API. Code that depends on them does so at its own risk:
37 * they are subject to change or removal without notice.
38 */
39public final
40class Label extends Instruction {
41 static int labelCount = 0;
42 int ID;
43 int depth;
44 MemberDefinition locals[];
45
46 /**
47 * Constructor
48 */
49 public Label() {
50 super(0, opc_label, null);
51 this.ID = ++labelCount;
52 }
53
54 /**
55 * Get the final destination, eliminate jumps gotos, and jumps to
56 * labels that are immediately folowed by another label. The depth
57 * field is used to leave bread crumbs to avoid infinite loops.
58 */
59 Label getDestination() {
60 Label lbl = this;
61 if ((next != null) && (next != this) && (depth == 0)) {
62 depth = 1;
63
64 switch (next.opc) {
65 case opc_label:
66 lbl = ((Label)next).getDestination();
67 break;
68
69 case opc_goto:
70 lbl = ((Label)next.value).getDestination();
71 break;
72
73 case opc_ldc:
74 case opc_ldc_w:
75 if (next.value instanceof Integer) {
76 Instruction inst = next.next;
77 if (inst.opc == opc_label) {
78 inst = ((Label)inst).getDestination().next;
79 }
80
81 if (inst.opc == opc_ifeq) {
82 if (((Integer)next.value).intValue() == 0) {
83 lbl = (Label)inst.value;
84 } else {
85 lbl = new Label();
86 lbl.next = inst.next;
87 inst.next = lbl;
88 }
89 lbl = lbl.getDestination();
90 break;
91 }
92 if (inst.opc == opc_ifne) {
93 if (((Integer)next.value).intValue() == 0) {
94 lbl = new Label();
95 lbl.next = inst.next;
96 inst.next = lbl;
97 } else {
98 lbl = (Label)inst.value;
99 }
100 lbl = lbl.getDestination();
101 break;
102 }
103 }
104 break;
105 }
106 depth = 0;
107 }
108 return lbl;
109 }
110
111 public String toString() {
112 String s = "$" + ID + ":";
113 if (value != null)
114 s = s + " stack=" + value;
115 return s;
116 }
117}