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comparison graal/com.oracle.max.asm/src/com/oracle/max/asm/Label.java @ 3733:e233f5660da4

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Added Java files from Maxine project.
author Thomas Wuerthinger <thomas.wuerthinger@oracle.com>
date Sat, 17 Dec 2011 19:59:18 +0100
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children bc8527f3071c
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3732:3e2e8b8abdaf 3733:e233f5660da4
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.oracle.max.asm;
24
25 import java.util.ArrayList;
26
27 /**
28 * This class represents a label within assembly code.
29 */
30 public final class Label {
31 private int position = -1;
32
33 /**
34 * References to instructions that jump to this unresolved label.
35 * These instructions need to be patched when the label is bound
36 * using the {@link #patchInstructions(AbstractAssembler)} method.
37 */
38 private ArrayList<Integer> patchPositions = new ArrayList<Integer>(4);
39
40 /**
41 * Returns the position of this label in the code buffer.
42 * @return the position
43 */
44 public int position() {
45 assert position >= 0 : "Unbound label is being referenced";
46 return position;
47 }
48
49 public Label() {
50 }
51
52 /**
53 * Binds the label to the specified position.
54 * @param pos the position
55 */
56 protected void bind(int pos) {
57 this.position = pos;
58 assert isBound();
59 }
60
61 public boolean isBound() {
62 return position >= 0;
63 }
64
65 public void addPatchAt(int branchLocation) {
66 assert !isBound() : "Label is already bound";
67 patchPositions.add(branchLocation);
68 }
69
70 protected void patchInstructions(AbstractAssembler masm) {
71 assert isBound() : "Label should be bound";
72 int target = position;
73 for (int i = 0; i < patchPositions.size(); ++i) {
74 int pos = patchPositions.get(i);
75 masm.patchJumpTarget(pos, target);
76 }
77 }
78
79 @Override
80 public String toString() {
81 return isBound() ? String.valueOf(position()) : "?";
82 }
83 }