/*
 * 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
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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.
/**
 * 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
/**
     * 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.
/**
     * 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;
    }
}