fix double/long locals, fix jsr

remove stores without locads


git-svn-id: https://svn.code.sf.net/p/jode/code/trunk@514 379699f6-c40d-0410-875b-85095c16579e

jode/jode/obfuscator/LocalOptimizer.java

@@ -1,8 +1,28 @@
+/* LocalOptimizer 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.obfuscator;
 import java.util.*;
 import jode.bytecode.*;
+import jode.AssertError;
 
-public class LocalOptimizer {
+public class LocalOptimizer implements Opcodes {
 
     class LocalInfo {
 	LocalInfo shadow = null;
@@ -16,6 +36,7 @@ public class LocalOptimizer {
 
 	Vector usingInstrs = new Vector();
 	Vector conflictingLocals = new Vector();
+	int size;
 	int newSlot = -1;
 
 	LocalInfo(InstrInfo instr) {
@@ -53,15 +74,16 @@ public class LocalOptimizer {
     }
 
     class InstrInfo {
-	/**
-	 * Tell if the localsToRead variable has changed.
-	 */
-	boolean changed;
 	/**
 	 * The LocalInfo of the next Instruction, that may read a local, 
 	 * without prior writing.
 	 */
 	LocalInfo[] nextReads;
+	/**
+	 * The jsr to which the nextReads at this slot belongs to.
+	 * I think I don't like jsrs any more.
+	 */
+	Vector[] belongsToJsrs;
 	/**
 	 * The LocalInfo for this local
 	 */
@@ -74,9 +96,14 @@ public class LocalOptimizer {
 	 * The next info in the chain.
 	 */
 	InstrInfo nextInfo;
+	/**
+	 * If instruction is a jsr, this array contains the ret instructions.
+	 */
+	Instruction[] retInstrs;
     }
 
     InstrInfo firstInfo;
+    Stack changedInfos;
     Hashtable instrInfos;
     BytecodeInfo bc;
 
@@ -84,12 +111,63 @@ public class LocalOptimizer {
 	this.bc = bc;
     }
 
-    public void promoteReads(InstrInfo info, Instruction preInstr) {
+    /**
+     * This method determines which rets belong to a given jsr.  This
+     * is needed, since the predecessors must be exact.  
+     */
+    void findRets(InstrInfo jsrInfo) {
+	Vector rets = new Vector();
+	Stack instrStack = new Stack();
+	Instruction subInstr = jsrInfo.instr.succs[0];
+	if (subInstr.opcode != opc_astore)
+	    throw new AssertError("Non standard jsr");
+	int slot = subInstr.localSlot;
+	instrStack.push(subInstr.nextByAddr);
+	while (!instrStack.isEmpty()) {
+	    Instruction instr = (Instruction) instrStack.pop();
+	    if (instr.localSlot == slot) {
+		if (instr.opcode != opc_ret)
+		    throw new AssertError("Non standard jsr");
+		rets.addElement(instr);
+	    }
+	    if (!instr.alwaysJumps)
+		instrStack.push(instr.nextByAddr);
+	    if (instr.succs != null)
+		for (int i=0; i< instr.succs.length; i++)
+		    instrStack.push(instr.succs[i]);
+	}
+	jsrInfo.retInstrs = new Instruction[rets.size()];
+	rets.copyInto(jsrInfo.retInstrs);
+    }
+
+    /**
+     * Merges the given vector to a new vector.  Both vectors may
+     * be null in which case they are interpreted as empty vectors.
+     * The vectors will never changed, but the result may be one
+     * of the given vectors.
+     */
+    Vector merge(Vector v1, Vector v2) {
+	if (v1 == null || v1.isEmpty())
+	    return v2;
+	if (v2 == null || v2.isEmpty())
+	    return v1;
+	Vector result = (Vector) v1.clone();
+	Enumeration enum = v2.elements();
+	while (enum.hasMoreElements()) {
+	    Object elem = enum.nextElement();
+	    if (!result.contains(elem))
+		result.addElement(elem);
+	}
+	return result;
+    }
+
+    void promoteReads(InstrInfo info, Instruction preInstr, 
+		      Instruction belongingJsr) {
 	InstrInfo preInfo = (InstrInfo) instrInfos.get(preInstr);
 	int omitLocal = -1;
 	if (preInstr.localSlot != -1
-	    && preInstr.opcode >= BytecodeInfo.opc_istore
+	    && preInstr.opcode >= opc_istore
-	    && preInstr.opcode < BytecodeInfo.opc_iastore) {
+	    && preInstr.opcode <= opc_astore) {
 	    /* This is a store */
 	    omitLocal = preInstr.localSlot;
 	    if (info.nextReads[preInstr.localSlot] != null)
@@ -98,10 +176,30 @@ public class LocalOptimizer {
 	}
 	int maxlocals = bc.getMaxLocals();
 	for (int i=0; i< maxlocals; i++) {
+	    Vector newBelongs = info.belongsToJsrs[i];
+	    if (preInstr.opcode == opc_jsr
+		&& newBelongs != null) {
+		if (!info.belongsToJsrs[i].contains(preInstr))
+		    /* This was the wrong jsr */
+		    continue;
+		if (info.belongsToJsrs[i].size() == 1)
+		    newBelongs = null;
+		else {
+		    newBelongs = (Vector) info.belongsToJsrs[i].clone();
+		    newBelongs.removeElement(preInstr);
+		}
+	    }
+	    if (belongingJsr != null) {
+		if (newBelongs == null)
+		    newBelongs = new Vector();
+		newBelongs.addElement(belongingJsr);
+	    }
 	    if (info.nextReads[i] != null && i != omitLocal) {
+		preInfo.belongsToJsrs[i] 
+		    = merge(preInfo.belongsToJsrs[i], newBelongs);
 		if (preInfo.nextReads[i] == null) {
 		    preInfo.nextReads[i] = info.nextReads[i];
-		    preInfo.changed = true;
+		    changedInfos.push(preInfo);
 		} else {
 		    preInfo.nextReads[i]
 			.combineInto(info.nextReads[i]);
@@ -115,6 +213,7 @@ public class LocalOptimizer {
 	Handler[] handlers = bc.getExceptionHandlers();
 	/* Initialize the InstrInfos and LocalInfos
 	 */
+	changedInfos = new Stack();
 	instrInfos = new Hashtable();
 	{
 	    InstrInfo info = firstInfo = new InstrInfo();
@@ -123,13 +222,25 @@ public class LocalOptimizer {
 		instrInfos.put(instr, info);
 		info.instr = instr;
 		info.nextReads = new LocalInfo[maxlocals];
+		info.belongsToJsrs = new Vector[maxlocals];
 		if (instr.localSlot != -1) {
 		    info.local = new LocalInfo(info);
-		    if (instr.opcode < BytecodeInfo.opc_istore
+		    info.local.size = 1;
-			|| instr.opcode > BytecodeInfo.opc_iastore) {
+		    switch (instr.opcode) {
+		    case opc_lload: case opc_dload:
+			info.local.size = 2;
+			/* fall through */
+		    case opc_iload: case opc_fload: case opc_aload:
+		    case opc_ret:
+		    case opc_iinc:
 			/* this is a load instruction */
 			info.nextReads[instr.localSlot] = info.local;
-			info.changed = true;
+			changedInfos.push(info);
+			break;
+
+		    case opc_lstore: case opc_dstore:
+			info.local.size = 2;
+		    case opc_istore: case opc_fstore: case opc_astore:
 		    }
 		}
 		if ((instr = instr.nextByAddr) == null)
@@ -138,54 +249,71 @@ public class LocalOptimizer {
 	    }
 	}
 
+	for (InstrInfo info = firstInfo; info != null; info = info.nextInfo)
+	    if (info.instr.opcode == opc_jsr)
+		findRets(info);
+
 	/* find out which locals are the same.
 	 */
-	boolean changed = true;
+	while (!changedInfos.isEmpty()) {
-	while (changed) {
+	    InstrInfo info = (InstrInfo) changedInfos.pop();
-	    changed = false;
+	    Enumeration enum = info.instr.preds.elements();
-	    for (InstrInfo info = firstInfo;
+	    while (enum.hasMoreElements()) {
-		 info != null; info = info.nextInfo) {
+		Instruction preInstr
-		if (info.changed) {
+		    = (Instruction) enum.nextElement();
-		    info.changed = false;
+		if (preInstr.opcode == opc_jsr
-		    Enumeration enum = info.instr.preds.elements();
+		    && info.instr != preInstr.succs[0]) {
-		    while (enum.hasMoreElements()) {
+		    /* Prev expr is a jsr, continue with the
-			changed = true;
+		     * corresponding ret, instead with the jsr.
-			Instruction preInstr
+		     */
-			    = (Instruction) enum.nextElement();
+		    InstrInfo jsrInfo = 
-			promoteReads(info, preInstr);
+			(InstrInfo) instrInfos.get(preInstr);
-		    }
+		    for (int i= jsrInfo.retInstrs.length; i-- > 0; )
-		    for (int i=0; i<handlers.length; i++) {
+			promoteReads(info, jsrInfo.retInstrs[i], preInstr);
-			if (handlers[i].catcher == info.instr) {
+		} else
-			    for (Instruction preInstr = handlers[i].start;
+		    promoteReads(info, preInstr, null);
-				 preInstr != handlers[i].end; 
+	    }
-				 preInstr = preInstr.nextByAddr) {
+	    for (int i=0; i<handlers.length; i++) {
-				promoteReads(info, preInstr);
+		if (handlers[i].catcher == info.instr) {
-			    }
+		    for (Instruction preInstr = handlers[i].start;
-			}
+			 preInstr != handlers[i].end.nextByAddr; 
+			 preInstr = preInstr.nextByAddr) {
+			promoteReads(info, preInstr, null);
 		    }
 		}
 	    }
 	}
+	changedInfos = null;
+    }
 
-	/* Now calculate the conflict settings.
+    public void stripLocals() {
-	 */
 	for (InstrInfo info = firstInfo; info != null; info = info.nextInfo) {
-	    if (info.instr.localSlot != -1
+	    if (info.local != null && info.local.usingInstrs.size() == 1) {
-		&& info.instr.opcode >= BytecodeInfo.opc_istore
+		/* If this is a store, whose value is never read; it can
-		&& info.instr.opcode < BytecodeInfo.opc_iastore) {
+                 * be removed, i.e replaced by a pop. */
-		/* This is a store.  It conflicts with every local, whose
+		switch (info.instr.opcode) {
-		 * value will be read without write.
+		case opc_istore:
-		 */
+		case opc_fstore:
-		for (int i=0; i < maxlocals; i++) {
+		case opc_astore:
-		    if (i != info.instr.localSlot
+		    info.local = null;
-			&& info.nextReads[i] != null)
+		    info.instr.opcode = opc_pop;
-			info.local.conflictsWith(info.nextReads[i]);
+		    info.instr.length = 1;
+		    info.instr.localSlot = -1;
+		    break;
+		case opc_lstore:
+		case opc_dstore:
+		    info.local = null;
+		    info.instr.opcode = opc_pop2;
+		    info.instr.length = 1;
+		    info.instr.localSlot = -1;
+		    break;
+		default:
 		}
 	    }
 	}
     }
 
-    public void distributeLocals(Vector locals) {
+    void distributeLocals(Vector locals) {
 	if (locals.size() == 0)
 	    return;
 
@@ -217,8 +345,18 @@ public class LocalOptimizer {
 	for (int slot = 0; ; slot++) {
 	    Enumeration conflenum = bestLocal.conflictingLocals.elements();
 	    while (conflenum.hasMoreElements()) {
-		if (((LocalInfo)conflenum.nextElement()).newSlot == slot)
+		LocalInfo conflLocal = (LocalInfo)conflenum.nextElement();
+		if (bestLocal.size == 2 && conflLocal.newSlot == slot+1) {
+		    slot++;
+		    continue next_slot;
+		}
+		if (conflLocal.size == 2 && conflLocal.newSlot+1 == slot)
+		    continue next_slot;
+		if (conflLocal.newSlot == slot) {
+		    if (conflLocal.size == 2)
+			slot++;
 		    continue next_slot;
+		}
 	    }
 	    bestLocal.newSlot = slot;
 	    break;
@@ -241,6 +379,23 @@ public class LocalOptimizer {
 		firstInfo.nextReads[i].getReal().newSlot = i;
 	}
 
+	/* Now calculate the conflict settings.
+	 */
+	for (InstrInfo info = firstInfo; info != null; info = info.nextInfo) {
+	    if (info.instr.localSlot != -1
+		&& info.instr.opcode >= BytecodeInfo.opc_istore
+		&& info.instr.opcode <= BytecodeInfo.opc_astore) {
+		/* This is a store.  It conflicts with every local, whose
+		 * value will be read without write.
+		 */
+		for (int i=0; i < maxlocals; i++) {
+		    if (i != info.instr.localSlot
+			&& info.nextReads[i] != null)
+			info.local.conflictsWith(info.nextReads[i]);
+		}
+	    }
+	}
+
 	/* Now put the locals that need a color into a vector.
 	 */
 	Vector locals = new Vector();