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comparison graal/Compiler/src/com/sun/c1x/asm/Label.java @ 2507:9ec15d6914ca

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Pull over of compiler from maxine repository.
author Thomas Wuerthinger <thomas@wuerthinger.net>
date Wed, 27 Apr 2011 11:43:22 +0200
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2506:4a3bf8a5bf41 2507:9ec15d6914ca
1 /*
2 * Copyright (c) 2009, 2011, 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 package com.sun.c1x.asm;
24
25 import com.sun.c1x.util.*;
26
27 /**
28 * This class represents a label within assembly code.
29 *
30 * @author Marcelo Cintra
31 */
32 public final class Label {
33
34 private int position = -1;
35
36 /**
37 * References to instructions that jump to this unresolved label.
38 * These instructions need to be patched when the label is bound
39 * using the {@link #patchInstructions(AbstractAssembler)} method.
40 */
41 private IntList patchPositions = new IntList(4);
42
43 /**
44 * Returns the position of this label in the code buffer.
45 * @return the position
46 */
47 public int position() {
48 assert position >= 0 : "Unbound label is being referenced";
49 return position;
50 }
51
52 public Label() {
53 }
54
55 public Label(int position) {
56 bind(position);
57 }
58
59 /**
60 * Binds the label to the specified position.
61 * @param pos the position
62 */
63 public void bind(int pos) {
64 this.position = pos;
65 assert isBound();
66 }
67
68 public boolean isBound() {
69 return position >= 0;
70 }
71
72 public void addPatchAt(int branchLocation) {
73 assert !isBound() : "Label is already bound";
74 patchPositions.add(branchLocation);
75 }
76
77 public void patchInstructions(AbstractAssembler masm) {
78 assert isBound() : "Label should be bound";
79 int target = position;
80 for (int i = 0; i < patchPositions.size(); ++i) {
81 int pos = patchPositions.get(i);
82 masm.patchJumpTarget(pos, target);
83 }
84 }
85
86 @Override
87 public String toString() {
88 return "label";
89 }
90 }