/*
Copyright (C) 2011 de4dot@gmail.com
This file is part of de4dot.
de4dot 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 3 of the License, or
(at your option) any later version.
de4dot 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 de4dot. If not, see .
*/
using System;
using System.Collections.Generic;
using Mono.Cecil;
using Mono.Cecil.Cil;
namespace de4dot.blocks {
public class Blocks {
MethodDefinition method;
IList locals;
MethodBlocks methodBlocks;
public MethodBlocks MethodBlocks {
get { return methodBlocks; }
}
public IList Locals {
get { return locals; }
}
public MethodDefinition Method {
get { return method; }
}
public Blocks(MethodDefinition method) {
var body = method.Body;
this.method = method;
this.locals = body.Variables;
methodBlocks = new InstructionListParser(body.Instructions, body.ExceptionHandlers).parse();
}
IEnumerable getAllScopeBlocks(ScopeBlock scopeBlock) {
var list = new List();
list.Add(scopeBlock);
list.AddRange(scopeBlock.getAllScopeBlocks());
return list;
}
public int removeDeadBlocks() {
return new DeadBlocksRemover(methodBlocks).remove();
}
public void getCode(out IList allInstructions, out IList allExceptionHandlers) {
new CodeGenerator(methodBlocks).getCode(out allInstructions, out allExceptionHandlers);
}
struct LocalVariableInfo {
public Block block;
public int index;
public LocalVariableInfo(Block block, int index) {
this.block = block;
this.index = index;
}
}
public int optimizeLocals() {
if (locals.Count == 0)
return 0;
var usedLocals = new Dictionary>();
foreach (var block in methodBlocks.getAllBlocks()) {
for (int i = 0; i < block.Instructions.Count; i++) {
var instr = block.Instructions[i];
VariableDefinition local;
switch (instr.OpCode.Code) {
case Code.Ldloc:
case Code.Ldloc_S:
case Code.Ldloc_0:
case Code.Ldloc_1:
case Code.Ldloc_2:
case Code.Ldloc_3:
case Code.Stloc:
case Code.Stloc_S:
case Code.Stloc_0:
case Code.Stloc_1:
case Code.Stloc_2:
case Code.Stloc_3:
local = Instr.getLocalVar(locals, instr);
break;
case Code.Ldloca_S:
case Code.Ldloca:
local = (VariableDefinition)instr.Operand;
break;
default:
local = null;
break;
}
if (local == null)
continue;
List list;
if (!usedLocals.TryGetValue(local, out list))
usedLocals[local] = list = new List();
list.Add(new LocalVariableInfo(block, i));
if (usedLocals.Count == locals.Count)
return 0;
}
}
int newIndex = -1;
var newLocals = new List(usedLocals.Count);
foreach (var local in usedLocals.Keys) {
newIndex++;
newLocals.Add(local);
foreach (var info in usedLocals[local])
info.block.Instructions[info.index] = new Instr(optimizeLocalInstr(info.block.Instructions[info.index], local, (uint)newIndex));
}
int numRemoved = locals.Count - newLocals.Count;
locals.Clear();
foreach (var local in newLocals)
locals.Add(local);
return numRemoved;
}
static Instruction optimizeLocalInstr(Instr instr, VariableDefinition local, uint newIndex) {
switch (instr.OpCode.Code) {
case Code.Ldloc:
case Code.Ldloc_S:
case Code.Ldloc_0:
case Code.Ldloc_1:
case Code.Ldloc_2:
case Code.Ldloc_3:
if (newIndex == 0)
return Instruction.Create(OpCodes.Ldloc_0);
if (newIndex == 1)
return Instruction.Create(OpCodes.Ldloc_1);
if (newIndex == 2)
return Instruction.Create(OpCodes.Ldloc_2);
if (newIndex == 3)
return Instruction.Create(OpCodes.Ldloc_3);
if (newIndex <= 0xFF)
return Instruction.Create(OpCodes.Ldloc_S, local);
return Instruction.Create(OpCodes.Ldloc, local);
case Code.Stloc:
case Code.Stloc_S:
case Code.Stloc_0:
case Code.Stloc_1:
case Code.Stloc_2:
case Code.Stloc_3:
if (newIndex == 0)
return Instruction.Create(OpCodes.Stloc_0);
if (newIndex == 1)
return Instruction.Create(OpCodes.Stloc_1);
if (newIndex == 2)
return Instruction.Create(OpCodes.Stloc_2);
if (newIndex == 3)
return Instruction.Create(OpCodes.Stloc_3);
if (newIndex <= 0xFF)
return Instruction.Create(OpCodes.Stloc_S, local);
return Instruction.Create(OpCodes.Stloc, local);
case Code.Ldloca_S:
case Code.Ldloca:
if (newIndex <= 0xFF)
return Instruction.Create(OpCodes.Ldloca_S, local);
return Instruction.Create(OpCodes.Ldloca, local);
default:
throw new ApplicationException("Invalid ld/st local instruction");
}
}
public void repartitionBlocks() {
mergeNopBlocks();
foreach (var scopeBlock in getAllScopeBlocks(methodBlocks)) {
try {
scopeBlock.repartitionBlocks();
}
catch (NullReferenceException) {
//TODO: Send this message to the log
Console.WriteLine("Null ref exception! Invalid metadata token in code? Method: {0:X8}: {1}", method.MetadataToken.ToUInt32(), method.FullName);
return;
}
}
}
void mergeNopBlocks() {
var allBlocks = methodBlocks.getAllBlocks();
var nopBlocks = new Dictionary();
foreach (var nopBlock in allBlocks) {
if (nopBlock.isNopBlock())
nopBlocks[nopBlock] = true;
}
if (nopBlocks.Count == 0)
return;
for (int i = 0; i < 10; i++) {
bool changed = false;
foreach (var block in allBlocks) {
Block nopBlockTarget;
nopBlockTarget = getNopBlockTarget(nopBlocks, block, block.FallThrough);
if (nopBlockTarget != null) {
block.setNewFallThrough(nopBlockTarget);
changed = true;
}
if (block.Targets != null) {
for (int targetIndex = 0; targetIndex < block.Targets.Count; targetIndex++) {
nopBlockTarget = getNopBlockTarget(nopBlocks, block, block.Targets[targetIndex]);
if (nopBlockTarget == null)
continue;
block.setNewTarget(targetIndex, nopBlockTarget);
changed = true;
}
}
}
if (!changed)
break;
}
foreach (var nopBlock in nopBlocks.Keys)
nopBlock.Parent.removeDeadBlock(nopBlock);
}
static Block getNopBlockTarget(Dictionary nopBlocks, Block source, Block nopBlock) {
if (nopBlock == null || !nopBlocks.ContainsKey(nopBlock) || source == nopBlock.FallThrough)
return null;
if (nopBlock.Parent.BaseBlocks[0] == nopBlock)
return null;
var target = nopBlock.FallThrough;
if (nopBlock.Parent != target.Parent)
return null;
return target;
}
}
}