283 lines
8.0 KiB
C#
283 lines
8.0 KiB
C#
/*
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Copyright (C) 2011-2015 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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namespace de4dot.blocks {
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public class Blocks {
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MethodDef method;
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IList<Local> locals;
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MethodBlocks methodBlocks;
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public MethodBlocks MethodBlocks {
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get { return methodBlocks; }
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}
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public IList<Local> Locals {
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get { return locals; }
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}
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public MethodDef Method {
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get { return method; }
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}
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public Blocks(MethodDef method) {
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this.method = method;
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UpdateBlocks();
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}
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public void UpdateBlocks() {
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var body = method.Body;
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locals = body.Variables;
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methodBlocks = new InstructionListParser(body.Instructions, body.ExceptionHandlers).Parse();
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}
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IEnumerable<ScopeBlock> GetAllScopeBlocks(ScopeBlock scopeBlock) {
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var list = new List<ScopeBlock>();
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list.Add(scopeBlock);
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list.AddRange(scopeBlock.GetAllScopeBlocks());
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return list;
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}
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public int RemoveDeadBlocks() {
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return new DeadBlocksRemover(methodBlocks).Remove();
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}
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public void GetCode(out IList<Instruction> allInstructions, out IList<ExceptionHandler> allExceptionHandlers) {
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new CodeGenerator(methodBlocks).GetCode(out allInstructions, out allExceptionHandlers);
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}
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struct LocalVariableInfo {
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public Block block;
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public int index;
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public LocalVariableInfo(Block block, int index) {
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this.block = block;
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this.index = index;
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}
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}
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public int OptimizeLocals() {
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if (locals.Count == 0)
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return 0;
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var usedLocals = new Dictionary<Local, List<LocalVariableInfo>>();
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foreach (var block in methodBlocks.GetAllBlocks()) {
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for (int i = 0; i < block.Instructions.Count; i++) {
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var instr = block.Instructions[i];
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Local local;
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switch (instr.OpCode.Code) {
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case Code.Ldloc:
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case Code.Ldloc_S:
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case Code.Ldloc_0:
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case Code.Ldloc_1:
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case Code.Ldloc_2:
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case Code.Ldloc_3:
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case Code.Stloc:
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case Code.Stloc_S:
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case Code.Stloc_0:
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case Code.Stloc_1:
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case Code.Stloc_2:
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case Code.Stloc_3:
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local = Instr.GetLocalVar(locals, instr);
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break;
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case Code.Ldloca_S:
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case Code.Ldloca:
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local = (Local)instr.Operand;
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break;
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default:
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local = null;
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break;
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}
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if (local == null)
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continue;
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List<LocalVariableInfo> list;
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if (!usedLocals.TryGetValue(local, out list))
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usedLocals[local] = list = new List<LocalVariableInfo>();
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list.Add(new LocalVariableInfo(block, i));
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if (usedLocals.Count == locals.Count)
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return 0;
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}
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}
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int newIndex = -1;
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var newLocals = new List<Local>(usedLocals.Count);
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var newLocalsDict = new Dictionary<Local, bool>(usedLocals.Count);
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foreach (var local in usedLocals.Keys) {
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newIndex++;
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newLocals.Add(local);
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newLocalsDict[local] = true;
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foreach (var info in usedLocals[local])
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info.block.Instructions[info.index] = new Instr(OptimizeLocalInstr(info.block.Instructions[info.index], local, (uint)newIndex));
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}
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// We can't remove all locals. Locals that reference another assembly will
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// cause the CLR to load that assembly before the method is executed if it
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// hasn't been loaded yet. This is a side effect the program may depend on.
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// At least one program has this dependency and will crash if we remove the
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// unused local. This took a while to figure out...
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var keptAssemblies = new Dictionary<string, bool>(StringComparer.Ordinal);
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foreach (var local in locals) {
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if (newLocalsDict.ContainsKey(local))
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continue;
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var defAsm = local.Type.DefinitionAssembly;
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if (defAsm == null)
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continue; // eg. fnptr
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if (defAsm == method.DeclaringType.Module.Assembly)
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continue; // this assembly is always loaded
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if (defAsm.IsCorLib())
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continue; // mscorlib is always loaded
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var asmName = defAsm.FullName;
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if (keptAssemblies.ContainsKey(asmName))
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continue;
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keptAssemblies[asmName] = true;
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newLocals.Add(local);
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}
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int numRemoved = locals.Count - newLocals.Count;
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locals.Clear();
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foreach (var local in newLocals)
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locals.Add(local);
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return numRemoved;
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}
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static Instruction OptimizeLocalInstr(Instr instr, Local local, uint newIndex) {
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switch (instr.OpCode.Code) {
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case Code.Ldloc:
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case Code.Ldloc_S:
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case Code.Ldloc_0:
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case Code.Ldloc_1:
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case Code.Ldloc_2:
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case Code.Ldloc_3:
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if (newIndex == 0)
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return OpCodes.Ldloc_0.ToInstruction();
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if (newIndex == 1)
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return OpCodes.Ldloc_1.ToInstruction();
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if (newIndex == 2)
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return OpCodes.Ldloc_2.ToInstruction();
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if (newIndex == 3)
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return OpCodes.Ldloc_3.ToInstruction();
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if (newIndex <= 0xFF)
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return OpCodes.Ldloc_S.ToInstruction(local);
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return OpCodes.Ldloc.ToInstruction(local);
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case Code.Stloc:
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case Code.Stloc_S:
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case Code.Stloc_0:
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case Code.Stloc_1:
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case Code.Stloc_2:
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case Code.Stloc_3:
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if (newIndex == 0)
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return OpCodes.Stloc_0.ToInstruction();
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if (newIndex == 1)
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return OpCodes.Stloc_1.ToInstruction();
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if (newIndex == 2)
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return OpCodes.Stloc_2.ToInstruction();
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if (newIndex == 3)
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return OpCodes.Stloc_3.ToInstruction();
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if (newIndex <= 0xFF)
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return OpCodes.Stloc_S.ToInstruction(local);
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return OpCodes.Stloc.ToInstruction(local);
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case Code.Ldloca_S:
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case Code.Ldloca:
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if (newIndex <= 0xFF)
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return OpCodes.Ldloca_S.ToInstruction(local);
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return OpCodes.Ldloca.ToInstruction(local);
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default:
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throw new ApplicationException("Invalid ld/st local instruction");
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}
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}
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public void RepartitionBlocks() {
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MergeNopBlocks();
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foreach (var scopeBlock in GetAllScopeBlocks(methodBlocks)) {
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try {
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scopeBlock.RepartitionBlocks();
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}
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catch (NullReferenceException) {
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//TODO: Send this message to the log
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Console.WriteLine("Null ref exception! Invalid metadata token in code? Method: {0:X8}: {1}", method.MDToken.Raw, method.FullName);
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return;
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}
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}
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}
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void MergeNopBlocks() {
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var allBlocks = methodBlocks.GetAllBlocks();
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var nopBlocks = new Dictionary<Block, bool>();
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foreach (var nopBlock in allBlocks) {
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if (nopBlock.IsNopBlock())
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nopBlocks[nopBlock] = true;
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}
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if (nopBlocks.Count == 0)
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return;
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for (int i = 0; i < 10; i++) {
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bool modified = false;
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foreach (var block in allBlocks) {
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Block nopBlockTarget;
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nopBlockTarget = GetNopBlockTarget(nopBlocks, block, block.FallThrough);
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if (nopBlockTarget != null) {
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block.SetNewFallThrough(nopBlockTarget);
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modified = true;
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}
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if (block.Targets != null) {
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for (int targetIndex = 0; targetIndex < block.Targets.Count; targetIndex++) {
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nopBlockTarget = GetNopBlockTarget(nopBlocks, block, block.Targets[targetIndex]);
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if (nopBlockTarget == null)
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continue;
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block.SetNewTarget(targetIndex, nopBlockTarget);
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modified = true;
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}
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}
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}
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if (!modified)
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break;
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}
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foreach (var nopBlock in nopBlocks.Keys)
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nopBlock.Parent.RemoveDeadBlock(nopBlock);
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}
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static Block GetNopBlockTarget(Dictionary<Block, bool> nopBlocks, Block source, Block nopBlock) {
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if (nopBlock == null || !nopBlocks.ContainsKey(nopBlock) || source == nopBlock.FallThrough)
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return null;
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if (nopBlock.Parent.BaseBlocks[0] == nopBlock)
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return null;
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var target = nopBlock.FallThrough;
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if (nopBlock.Parent != target.Parent)
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return null;
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return target;
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}
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}
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}
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