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Not working intermediate version. I think I go back to 1.3 now.

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git-svn-id: https://svn.code.sf.net/p/jode/code/trunk@615 379699f6-c40d-0410-875b-85095c16579e
stable
jochen 26 years ago
parent 33e7bd56cd
commit 1096d57991
1 changed files with 314 additions and 63 deletions
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  1. 377
      jode/jode/obfuscator/LocalOptimizer.java

377
jode/jode/obfuscator/LocalOptimizer.java
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@ -21,9 +21,22 @@ package jode.obfuscator;
import java.util.*;
import jode.bytecode.*;
import jode.AssertError;
import jode.Obfuscator;
/**
* This class takes some bytecode and tries to minimize the number
* of locals used. It will also remove unnecessary stores.
*
* This class can only work on verified code. There should also be
* no deadcode, since we can't be sure that deadcode behaves okay.
*/
public class LocalOptimizer implements Opcodes {
/**
* This class keeps track of which locals must be the same, which
* name and type each local (if there is a local variable table) and
* which other locals have an intersecting life time.
*/
class LocalInfo {
LocalInfo shadow = null;
@ -34,11 +47,21 @@ public class LocalOptimizer implements Opcodes {
return real;
}
String name;
String type;
Vector usingInstrs = new Vector();
Vector conflictingLocals = new Vector();
int size;
int newSlot = -1;
/**
* If this local is used as returnAddress, this gives the
* ret that uses it.
*/
InstrInfo retInfo;
LocalInfo() {
}
LocalInfo(InstrInfo instr) {
usingInstrs.addElement(instr);
}
@ -64,6 +87,16 @@ public class LocalOptimizer implements Opcodes {
if (this == l)
return;
shadow = l;
if (shadow.name == null) {
shadow.name = name;
shadow.type = type;
}
if (retInfo != null) {
if (retInfo != shadow.retInfo)
Obfuscator.err.println
("Warning: Multiple rets on one jsr?");
shadow.retInfo = retInfo;
}
Enumeration enum = usingInstrs.elements();
while (enum.hasMoreElements()) {
InstrInfo instr = (InstrInfo) enum.nextElement();
@ -73,21 +106,44 @@ public class LocalOptimizer implements Opcodes {
}
}
/**
* This class contains information for each instruction.
*/
class InstrInfo {
/**
* The LocalInfo of the next Instruction, that may read a local,
* without prior writing.
* The LocalInfo that this instruction manipulates, or null
* if this is not an ret, iinc, load or store instruction.
*/
LocalInfo local;
/**
* For each slot, this contains the LocalInfo of the next
* Instruction, that may read from that slot, without prior
* writing.
*/
LocalInfo[] nextReads;
/**
* For each slot if get() is true, no instruction may read
* this slot, since it may contain different locals, depending
* on flow.
*/
BitSet conflictingLocals;
/**
* If instruction is the destination of a jsr, this contains
* the single allowed ret instructions, or null if there is
* no ret at all.
*/
Instruction retInstr;
/**
* If instruction is a jsr, this contains the slots
* used by the sub routine
*/
BitSet usedBySub;
/**
* 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
*/
LocalInfo local;
/**
* The Instruction of this info
*/
@ -96,39 +152,63 @@ public class LocalOptimizer implements Opcodes {
* 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;
boolean produceLVT;
int maxlocals;
int paramCount;
public LocalOptimizer(BytecodeInfo bc) {
public LocalOptimizer(BytecodeInfo bc, int paramCount) {
this.bc = bc;
this.paramCount = paramCount;
}
/**
* 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();
void analyzeSubRoutine(InstrInfo subInfo) {
Stack instrStack = new Stack();
Instruction subInstr = jsrInfo.instr.succs[0];
if (subInstr.opcode != opc_astore)
Instruction subInstr = subInfo.instr;
if (subInfo.usedBySub != null)
return;
subInfo.usedBySub = new BitSet(maxlocals);
if (subInstr.opcode != opc_astore) {
/* Grrr, the bytecode verifier doesn't test if a
* jsr starts with astore. So it is possible to
* do something else before putting the ret address
* into a local. It would be even possible to pop
* the address, and never return.
*/
throw new AssertError("Non standard jsr");
}
int slot = subInstr.localSlot;
subInfo.usedBySub.set(slot);
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.opcode >= opc_istore
&& instr.opcode <= opc_astore)
/* Return address is overwritten, we will never
* return.
*/
continue;
if (instr.opcode != opc_ret
|| (subInfo.retInstr != null
&& subInfo.retInstr != instr))
/* This can't happen in legal bytecode. */
throw new AssertError("Illegal bytecode");
subInfo.retInstr = instr;
} else if (instr.localSlot != -1) {
subInfo.usedBySub.set(instr.localSlot);
}
if (!instr.alwaysJumps)
instrStack.push(instr.nextByAddr);
@ -136,8 +216,6 @@ public class LocalOptimizer implements Opcodes {
for (int i=0; i< instr.succs.length; i++)
instrStack.push(instr.succs[i]);
}
jsrInfo.retInstrs = new Instruction[rets.size()];
rets.copyInto(jsrInfo.retInstrs);
}
/**
@ -161,8 +239,8 @@ public class LocalOptimizer implements Opcodes {
return result;
}
void promoteReads(InstrInfo info, Instruction preInstr,
Instruction belongingJsr) {
void promoteSubRoutineReads(InstrInfo info, Instruction preInstr,
InstrInfo jsrInfo) {
InstrInfo preInfo = (InstrInfo) instrInfos.get(preInstr);
int omitLocal = -1;
if (preInstr.localSlot != -1
@ -174,29 +252,38 @@ public class LocalOptimizer implements Opcodes {
preInfo.local.combineInto
(info.nextReads[preInstr.localSlot]);
}
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);
for (int i=0; i < maxlocals; i++) {
if (info.nextReads[i] != null && i != omitLocal
&& (jsrInfo == null || !jsrInfo.usedBySub.get(i))) {
if (preInfo.nextReads[i] == null) {
preInfo.nextReads[i] = info.nextReads[i];
changedInfos.push(preInfo);
} else {
preInfo.nextReads[i]
.combineInto(info.nextReads[i]);
}
}
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);
}
}
void promoteNotModifiedReads(InstrInfo info, Instruction preInstr,
InstrInfo jsrInfo) {
InstrInfo preInfo = (InstrInfo) instrInfos.get(preInstr);
int omitLocal = -1;
if (preInstr.localSlot != -1
&& preInstr.opcode >= opc_istore
&& preInstr.opcode <= opc_astore) {
/* This is a store */
omitLocal = preInstr.localSlot;
if (info.nextReads[preInstr.localSlot] != null)
preInfo.local.combineInto
(info.nextReads[preInstr.localSlot]);
}
for (int i=0; i < maxlocals; i++) {
if (info.nextReads[i] != null && i != omitLocal
&& (jsrInfo == null || !jsrInfo.usedBySub.get(i))) {
if (preInfo.nextReads[i] == null) {
preInfo.nextReads[i] = info.nextReads[i];
changedInfos.push(preInfo);
@ -208,9 +295,36 @@ public class LocalOptimizer implements Opcodes {
}
}
void promoteReads(InstrInfo info, Instruction preInstr) {
promoteNotModifiedReads(info, preInstr, null);
}
public LocalVariableInfo findLVTEntry(LocalVariableInfo[] lvt,
Instruction instr) {
int addr = instr.addr;
if (instr.opcode >= opc_istore
&& instr.opcode <= opc_astore)
addr += instr.length;
LocalVariableInfo match = null;
for (int i=0; i < lvt.length; i++) {
if (lvt[i].slot == instr.localSlot
&& lvt[i].start.addr <= addr
&& lvt[i].end.addr > addr) {
if (match != null)
/* Multiple matches..., give no info */
return null;
match = lvt[i];
}
}
return match;
}
public void calcLocalInfo() {
int maxlocals = bc.getMaxLocals();
maxlocals = bc.getMaxLocals();
Handler[] handlers = bc.getExceptionHandlers();
LocalVariableInfo[] lvt = bc.getLocalVariableTable();
if (lvt != null)
produceLVT = true;
/* Initialize the InstrInfos and LocalInfos
*/
changedInfos = new Stack();
@ -225,22 +339,35 @@ public class LocalOptimizer implements Opcodes {
info.belongsToJsrs = new Vector[maxlocals];
if (instr.localSlot != -1) {
info.local = new LocalInfo(info);
if (lvt != null) {
LocalVariableInfo lvi = findLVTEntry(lvt, instr);
if (lvi != null) {
info.local.name = lvi.name;
info.local.type = lvi.type;
}
}
info.local.size = 1;
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;
changedInfos.push(info);
break;
case opc_ret:
/* this is a ret instruction */
info.local.retInfo = info;
info.nextReads[instr.localSlot] = info.local;
changedInfos.push(info);
break;
case opc_lstore: case opc_dstore:
info.local.size = 2;
case opc_istore: case opc_fstore: case opc_astore:
//case opc_istore: case opc_fstore: case opc_astore:
}
}
if ((instr = instr.nextByAddr) == null)
@ -249,9 +376,9 @@ public class LocalOptimizer implements Opcodes {
}
}
for (InstrInfo info = firstInfo; info != null; info = info.nextInfo)
if (info.instr.opcode == opc_jsr)
findRets(info);
// for (InstrInfo info = firstInfo; info != null; info = info.nextInfo)
// if (info.instr.opcode == opc_jsr)
// analyzeSubRoutine(info.succs[0]);
/* find out which locals are the same.
*/
@ -262,20 +389,42 @@ public class LocalOptimizer implements Opcodes {
Instruction prevInstr = instr.prevByAddr;
if (prevInstr != null) {
if (prevInstr.opcode == opc_jsr) {
/* Prev instr is a jsr, continue with the
* corresponding ret, instead with the jsr.
/* Prev instr is a jsr, promote reads to the
* corresponding ret.
*/
InstrInfo jsrInfo =
(InstrInfo) instrInfos.get(prevInstr);
for (int i = jsrInfo.retInstrs.length; i-- > 0; )
promoteReads(info, jsrInfo.retInstrs[i], prevInstr);
(InstrInfo) instrInfos.get(prevInstr.succs[0]);
if (jsrInfo.retInstr != null)
promoteReads(info, jsrInfo.retInstr);
/* Now promote reads that aren't modified by the
* subroutine to prevInstr
*/
promoteSubRoutineReads(info, prevInstr, jsrInfo);
} else if (!prevInstr.alwaysJumps)
promoteReads(info, prevInstr, null);
promoteReads(info, prevInstr);
}
if (instr.preds != null) {
for (int i = 0; i < instr.preds.length; i++)
promoteReads(info, instr.preds[i], null);
for (int i = 0; i < instr.preds.length; i++) {
if (instr.preds[i].opcode == opc_jsr) {
if (info.instr.opcode != opc_astore) {
/* XXX Grrr, the bytecode verifier doesn't
* test if a jsr starts with astore. So
* it is possible to do something else
* before putting the ret address into a
* local. */
throw new AssertError("Non standard jsr");
}
LocalInfo local = info.nextReads[info.instr.localSlot];
if (local != null && local.retInfo != null) {
info.retInstr = local.retInfo.instr;
/*XXX*/
}
}
promoteReads(info, instr.preds[i]);
}
}
for (int i=0; i < handlers.length; i++) {
@ -283,7 +432,7 @@ public class LocalOptimizer implements Opcodes {
for (Instruction preInstr = handlers[i].start;
preInstr != handlers[i].end.nextByAddr;
preInstr = preInstr.nextByAddr) {
promoteReads(info, preInstr, null);
promoteReads(info, preInstr);
}
}
}
@ -373,8 +522,6 @@ public class LocalOptimizer implements Opcodes {
* algorithm (the optimal solution is NP complete, but this
* should be a good approximation).
*/
int maxlocals = bc.getMaxLocals();
/* first give the params the same slot as they had before.
* The params should be the locals in firstInfo.nextReads
@ -415,19 +562,123 @@ public class LocalOptimizer implements Opcodes {
*/
distributeLocals(locals);
/* Update the instructions.
/* Update the instructions and calculate new maxlocals.
*/
maxlocals = paramCount;
for (InstrInfo info = firstInfo; info != null; info = info.nextInfo) {
if (info.local != null)
if (info.local != null) {
if (info.local.newSlot+info.local.size > maxlocals)
maxlocals = info.local.newSlot + info.local.size;
info.instr.localSlot = info.local.newSlot;
}
}
bc.setMaxLocals(maxlocals);
/* Update LocalVariableTable
*/
if (produceLVT)
buildNewLVT();
}
private LocalInfo CONFLICT = new LocalInfo();
void promoteValues(InstrInfo info, Instruction nextInstr) {
Instruction instr = info.instr;
InstrInfo nextInfo = (InstrInfo) instrInfos.get(nextInstr);
for (int i=0; i< maxlocals; i++) {
LocalInfo local = info.nextReads[i];
if (local != null)
local = local.getReal();
if (instr.localSlot == i
&& instr.opcode >= opc_istore
&& instr.opcode <= opc_astore)
local = info.local;
if (nextInfo.nextReads[i] == null)
nextInfo.nextReads[i] = local;
else if (local != null
&& local != nextInfo.nextReads[i].getReal())
nextInfo.nextReads[i] = CONFLICT;
}
}
public void buildNewLVT() {
/* We reuse the nextReads array for a differen purpose.
* For every slot we remember in this array, which local is
* there
* find out how long they remain there value.
*/
Stack changedInfo = new Stack();
Handler[] handlers = bc.getExceptionHandlers();
for (InstrInfo info = firstInfo;
info != null; info = info.nextInfo)
changedInfo.push(info);
while (!changedInfo.isEmpty()) {
InstrInfo info = (InstrInfo) changedInfo.pop();
Instruction instr = info.instr;
if (!instr.alwaysJumps) {
Instruction nextInstr = instr.nextByAddr;
promoteValues(info, instr.nextByAddr);
}
if (instr.succs != null) {
for (int i = 0; i < instr.succs.length; i++)
promoteValues(info, instr.succs[i]);
}
for (int i=0; i < handlers.length; i++) {
if (handlers[i].start.addr >= instr.addr
&& handlers[i].end.addr <= instr.addr)
promoteValues(info, handlers[i].catcher);
}
}
Vector lvtEntries = new Vector();
LocalVariableInfo[] lvi = new LocalVariableInfo[maxlocals];
LocalInfo[] currentLocal = new LocalInfo[maxlocals];
Instruction lastInstr = null;
for (InstrInfo info = firstInfo; info != null; info = info.nextInfo) {
for (int i=0; i< maxlocals; i++) {
LocalInfo lcl = info.nextReads[i];
if (lcl == CONFLICT)
lcl = null;
else if (lcl != null)
lcl = lcl.getReal();
if (lcl != currentLocal[i]) {
if (lvi[i] != null) {
lvi[i].end = info.instr.prevByAddr;
lvtEntries.addElement(lvi[i]);
}
lvi[i] = null;
currentLocal[i] = lcl;
if (currentLocal[i] != null
&& currentLocal[i].name != null) {
lvi[i] = new LocalVariableInfo();
lvi[i].name = currentLocal[i].name;
lvi[i].type = currentLocal[i].type;
lvi[i].start = info.instr;
lvi[i].slot = i;
}
changedInfo.push(info);
}
}
lastInstr = info.instr;
}
for (int i=0; i< maxlocals; i++) {
if (lvi[i] != null) {
lvi[i].end = lastInstr;
lvtEntries.addElement(lvi[i]);
}
}
LocalVariableInfo[] lvt = new LocalVariableInfo[lvtEntries.size()];
lvtEntries.copyInto(lvt);
bc.setLocalVariableTable(lvt);
}
public void dumpLocals() {
Vector locals = new Vector();
for (InstrInfo info = firstInfo; info != null; info = info.nextInfo) {
// System.err.print("addr: "+info.instr.addr+ " locals: ");
// for (int i=0; i<bc.info.getMaxLocals(); i++)
// for (int i=0; i<maxlocals; i++)
// if (info.nextReads[i] == null)
// System.err.print("-,");
// else

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