/*
* 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;
}
}