some methods added to add/remove/show/modify instructions

git-svn-id: https://svn.code.sf.net/p/jode/code/trunk@487 379699f6-c40d-0410-875b-85095c16579e

jode/jode/bytecode/Instruction.java

@@ -1,5 +1,25 @@
+/* Instruction Copyright (C) 1999 Jochen Hoenicke.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id$
+ */
+
 package jode.bytecode;
 import java.util.Vector;
+import java.util.Enumeration;
 
 /**
  * This class represents an instruction in the byte code.
@@ -8,6 +28,7 @@ import java.util.Vector;
  * many of them, though.
  */
 public class Instruction implements Opcodes{
+    public BytecodeInfo codeinfo;
     /**
      * The opcode of the instruction.  We map some opcodes, e.g.
      * <pre>
@@ -68,6 +89,131 @@ public class Instruction implements Opcodes{
 
     /**
      * You can use this field to add some info to each instruction.
+     * After using, you must set it to null again.
      */
     public Object tmpInfo;
+
+    public Instruction(BytecodeInfo ci) {
+	this.codeinfo = ci;
+    }
+
+    public Instruction insertInstruction() {
+	Instruction newInstr = new Instruction(codeinfo);
+	newInstr.addr = addr;
+
+	newInstr.prevByAddr = prevByAddr;
+	if (prevByAddr != null)
+	    prevByAddr.nextByAddr = newInstr;
+	else
+	    codeinfo.firstInstr = newInstr;
+	newInstr.nextByAddr = this;
+	prevByAddr = newInstr;
+
+	/* promote the predecessors to newInstr */
+	Enumeration enum = preds.elements();
+	while (enum.hasMoreElements()) {
+	    Instruction pred = (Instruction) enum.nextElement();
+	    if (pred.succs != null)
+		for (int i=0; i < pred.succs.length; i++)
+		    if (pred.succs[i] == this)
+			pred.succs[i] = newInstr;
+	}
+	newInstr.preds = preds;
+	preds = new Vector();
+	preds.addElement(newInstr);
+
+	return newInstr;
+    }
+
+    public Instruction appendInstruction(boolean nextAlwaysJumps) {
+	Instruction newInstr = new Instruction(codeinfo);
+	newInstr.addr = addr;
+	newInstr.nextByAddr = nextByAddr;
+	if (nextByAddr != null)
+	    nextByAddr.prevByAddr = newInstr;
+	newInstr.prevByAddr = this;
+	newInstr.alwaysJumps = nextAlwaysJumps;
+
+	if (nextByAddr != null) {
+	    if (!this.alwaysJumps)
+		nextByAddr.preds.removeElement(this);
+	    if (!nextAlwaysJumps)
+		nextByAddr.preds.addElement(newInstr);
+	}
+
+	nextByAddr = newInstr;
+	if (!this.alwaysJumps)
+	    newInstr.preds.addElement(this);
+	return newInstr;
     }
+
+    /**
+     * Removes this instruction (as if it would be replaced by a nop).
+     */
+    public void removeInstruction() {
+	/* remove from chained list */
+	if (prevByAddr != null)
+	    prevByAddr.nextByAddr = nextByAddr;
+	else
+	    codeinfo.firstInstr = nextByAddr;
+
+	if (nextByAddr != null)
+	    nextByAddr.prevByAddr = prevByAddr;
+
+	/* remove predecessors of successors */
+	if (!alwaysJumps && nextByAddr != null)
+	    nextByAddr.preds.removeElement(this);
+	if (succs != null) {
+	    for (int i=0; i < succs.length; i++)
+		succs[i].preds.removeElement(this);
+	}
+
+	/* promote the predecessors to nextByAddr */
+	Enumeration enum = preds.elements();
+	while (enum.hasMoreElements()) {
+	    Instruction pred = (Instruction) enum.nextElement();
+	    if (pred.succs != null)
+		for (int i=0; i < pred.succs.length; i++)
+		    if (pred.succs[i] == this)
+			pred.succs[i] = nextByAddr;
+	    if (nextByAddr != null)
+		nextByAddr.preds.addElement(pred);
+	}
+
+	/* adjust exception handlers */
+	Handler[] handlers = codeinfo.getExceptionHandlers();
+	for (int i=0; i< handlers.length; i++) {
+	    if (handlers[i].start == this)
+		handlers[i].start = nextByAddr;
+	    if (handlers[i].end == this)
+		handlers[i].end = prevByAddr;
+	    if (handlers[i].catcher == this)
+		handlers[i].catcher = nextByAddr;
+
+	    if (handlers[i].start == null
+		|| handlers[i].end == null
+		|| handlers[i].end.nextByAddr == handlers[i].start) {
+		/* Remove the handler.
+		 * This is very seldom, so we can make it slow */
+		Handler[] newHandlers = new Handler[handlers.length - 1];
+		System.arraycopy(handlers, 0, newHandlers, 0, i);
+		System.arraycopy(handlers, i+1, newHandlers, i, 
+				 handlers.length - (i+1));
+		handlers = newHandlers;
+		codeinfo.setExceptionHandlers(newHandlers);
+		i--;
+	    }
+	}
+    }
+
+    public String toString() {
+	String result =  ""+addr+"_"+Integer.toHexString(hashCode());
+	for (Instruction instr = codeinfo.firstInstr;
+	     instr != null; instr = instr.nextByAddr) {
+	    if (instr == this)
+		return result;
+	}
+	return result+"*";
+    }
+}
+