| /* |
| * Copyright (c) 1994, 2004, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package sun.tools.asm; |
| |
| import sun.tools.java.MemberDefinition; |
| import java.io.OutputStream; |
| |
| /** |
| * A label instruction. This is a 0 size instruction. |
| * It is the only valid target of a branch instruction. |
| * |
| * WARNING: The contents of this source file are not part of any |
| * supported API. Code that depends on them does so at its own risk: |
| * they are subject to change or removal without notice. |
| */ |
| public final |
| class Label extends Instruction { |
| static int labelCount = 0; |
| int ID; |
| int depth; |
| MemberDefinition locals[]; |
| |
| /** |
| * Constructor |
| */ |
| public Label() { |
| super(0, opc_label, null); |
| this.ID = ++labelCount; |
| } |
| |
| /** |
| * Get the final destination, eliminate jumps gotos, and jumps to |
| * labels that are immediately folowed by another label. The depth |
| * field is used to leave bread crumbs to avoid infinite loops. |
| */ |
| Label getDestination() { |
| Label lbl = this; |
| if ((next != null) && (next != this) && (depth == 0)) { |
| depth = 1; |
| |
| switch (next.opc) { |
| case opc_label: |
| lbl = ((Label)next).getDestination(); |
| break; |
| |
| case opc_goto: |
| lbl = ((Label)next.value).getDestination(); |
| break; |
| |
| case opc_ldc: |
| case opc_ldc_w: |
| if (next.value instanceof Integer) { |
| Instruction inst = next.next; |
| if (inst.opc == opc_label) { |
| inst = ((Label)inst).getDestination().next; |
| } |
| |
| if (inst.opc == opc_ifeq) { |
| if (((Integer)next.value).intValue() == 0) { |
| lbl = (Label)inst.value; |
| } else { |
| lbl = new Label(); |
| lbl.next = inst.next; |
| inst.next = lbl; |
| } |
| lbl = lbl.getDestination(); |
| break; |
| } |
| if (inst.opc == opc_ifne) { |
| if (((Integer)next.value).intValue() == 0) { |
| lbl = new Label(); |
| lbl.next = inst.next; |
| inst.next = lbl; |
| } else { |
| lbl = (Label)inst.value; |
| } |
| lbl = lbl.getDestination(); |
| break; |
| } |
| } |
| break; |
| } |
| depth = 0; |
| } |
| return lbl; |
| } |
| |
| public String toString() { |
| String s = "$" + ID + ":"; |
| if (value != null) |
| s = s + " stack=" + value; |
| return s; |
| } |
| } |