332 lines
11 KiB
C#
332 lines
11 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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class CodeGenerator {
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MethodBlocks methodBlocks;
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List<Block> blocks = new List<Block>();
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Stack<BlockState> stateStack = new Stack<BlockState>();
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List<ExceptionInfo> exceptions = new List<ExceptionInfo>();
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Dictionary<BaseBlock, bool> visited = new Dictionary<BaseBlock, bool>();
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List<BaseBlock> notProcessedYet = new List<BaseBlock>();
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class BlockState {
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public ScopeBlock scopeBlock;
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public BlockState(ScopeBlock scopeBlock) {
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this.scopeBlock = scopeBlock;
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}
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}
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class ExceptionInfo {
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public int tryStart;
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public int tryEnd;
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public int filterStart;
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public int handlerStart;
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public int handlerEnd;
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public ITypeDefOrRef catchType;
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public ExceptionHandlerType handlerType;
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public ExceptionInfo(int tryStart, int tryEnd, int filterStart,
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int handlerStart, int handlerEnd, ITypeDefOrRef catchType,
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ExceptionHandlerType handlerType) {
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if (tryStart > tryEnd || filterStart > handlerStart ||
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tryStart < 0 || tryEnd < 0 || filterStart < 0 || handlerStart < 0 || handlerEnd < 0)
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throw new ApplicationException("Invalid start/end/filter/handler indexes");
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this.tryStart = tryStart;
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this.tryEnd = tryEnd;
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this.filterStart = filterStart == handlerStart ? -1 : filterStart;
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this.handlerStart = handlerStart;
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this.handlerEnd = handlerEnd;
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this.catchType = catchType;
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this.handlerType = handlerType;
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}
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}
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public CodeGenerator(MethodBlocks methodBlocks) {
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this.methodBlocks = methodBlocks;
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}
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public void GetCode(out IList<Instruction> allInstructions, out IList<ExceptionHandler> allExceptionHandlers) {
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FixEmptyBlocks();
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LayOutBlocks();
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SortExceptions();
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LayOutInstructions(out allInstructions, out allExceptionHandlers);
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allInstructions.SimplifyBranches();
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allInstructions.OptimizeBranches();
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allInstructions.UpdateInstructionOffsets();
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}
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class BlockInfo {
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public int start;
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public int end;
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public BlockInfo(int start, int end) {
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this.start = start;
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this.end = end;
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}
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}
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void LayOutInstructions(out IList<Instruction> allInstructions, out IList<ExceptionHandler> allExceptionHandlers) {
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allInstructions = new List<Instruction>();
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allExceptionHandlers = new List<ExceptionHandler>();
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var blockInfos = new List<BlockInfo>();
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for (int i = 0; i < blocks.Count; i++) {
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var block = blocks[i];
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int startIndex = allInstructions.Count;
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for (int j = 0; j < block.Instructions.Count - 1; j++)
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allInstructions.Add(block.Instructions[j].Instruction);
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if (block.Targets != null) {
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var targets = new List<Instr>();
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foreach (var target in block.Targets)
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targets.Add(target.FirstInstr);
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block.LastInstr.UpdateTargets(targets);
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}
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allInstructions.Add(block.LastInstr.Instruction);
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var next = i + 1 < blocks.Count ? blocks[i + 1] : null;
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// If eg. ble next, then change it to bgt XYZ and fall through to next.
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if (block.Targets != null && block.CanFlipConditionalBranch() && block.Targets[0] == next) {
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block.FlipConditionalBranch();
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block.LastInstr.UpdateTargets(new List<Instr> { block.Targets[0].FirstInstr });
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}
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else if (block.FallThrough != null && block.FallThrough != next) {
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var instr = new Instr(OpCodes.Br.ToInstruction(block.FallThrough.FirstInstr.Instruction));
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instr.UpdateTargets(new List<Instr> { block.FallThrough.FirstInstr });
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allInstructions.Add(instr.Instruction);
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}
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int endIndex = allInstructions.Count - 1;
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blockInfos.Add(new BlockInfo(startIndex, endIndex));
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}
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foreach (var ex in exceptions) {
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var tryStart = GetBlockInfo(blockInfos, ex.tryStart).start;
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var tryEnd = GetBlockInfo(blockInfos, ex.tryEnd).end;
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var filterStart = ex.filterStart == -1 ? -1 : GetBlockInfo(blockInfos, ex.filterStart).start;
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var handlerStart = GetBlockInfo(blockInfos, ex.handlerStart).start;
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var handlerEnd = GetBlockInfo(blockInfos, ex.handlerEnd).end;
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var eh = new ExceptionHandler(ex.handlerType);
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eh.CatchType = ex.catchType;
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eh.TryStart = GetInstruction(allInstructions, tryStart);
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eh.TryEnd = GetInstruction(allInstructions, tryEnd + 1);
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eh.FilterStart = filterStart == -1 ? null : GetInstruction(allInstructions, filterStart);
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eh.HandlerStart = GetInstruction(allInstructions, handlerStart);
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eh.HandlerEnd = GetInstruction(allInstructions, handlerEnd + 1);
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allExceptionHandlers.Add(eh);
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}
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}
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static BlockInfo GetBlockInfo(List<BlockInfo> blockInfos, int index) {
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if (index >= blockInfos.Count)
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index = blockInfos.Count - 1;
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if (index < 0)
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index = 0;
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return blockInfos[index];
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}
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static Instruction GetInstruction(IList<Instruction> allInstructions, int i) {
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if (i < allInstructions.Count)
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return allInstructions[i];
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return null;
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}
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void SortExceptions() {
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exceptions.Sort((a, b) => {
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// Make sure nested try blocks are sorted before the outer try block.
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if (a.tryStart > b.tryStart) return -1; // a could be nested, but b is not
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if (a.tryStart < b.tryStart) return 1; // b could be nested, but a is not
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// same tryStart
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if (a.tryEnd < b.tryEnd) return -1; // a is nested
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if (a.tryEnd > b.tryEnd) return 1; // b is nested
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// same tryEnd (they share try block)
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int ai = a.filterStart == -1 ? a.handlerStart : a.filterStart;
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int bi = b.filterStart == -1 ? b.handlerStart : b.filterStart;
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if (ai < bi) return -1;
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if (ai > bi) return 1;
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// same start
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// if we're here, they should be identical since handlers can't overlap
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// when they share the try block!
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if (a.handlerEnd < b.handlerEnd) return -1;
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if (a.handlerEnd > b.handlerEnd) return 1;
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// same handler end
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return 0;
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});
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}
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void FixEmptyBlocks() {
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foreach (var block in methodBlocks.GetAllBlocks()) {
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if (block.Instructions.Count == 0) {
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block.Instructions.Add(new Instr(OpCodes.Nop.ToInstruction()));
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}
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}
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}
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// Write all blocks to the blocks list
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void LayOutBlocks() {
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if (methodBlocks.BaseBlocks.Count == 0)
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return;
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stateStack.Push(new BlockState(methodBlocks));
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ProcessBaseBlocks(methodBlocks.BaseBlocks, (block) => {
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return block.LastInstr.OpCode == OpCodes.Ret;
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});
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stateStack.Pop();
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foreach (var bb in notProcessedYet) {
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bool wasVisited;
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visited.TryGetValue(bb, out wasVisited);
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if (!wasVisited)
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throw new ApplicationException("A block wasn't processed");
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}
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}
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void ProcessBaseBlocks(List<BaseBlock> lb, Func<Block, bool> placeLast) {
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var bbs = new List<BaseBlock>();
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int lastIndex = -1;
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for (int i = 0; i < lb.Count; i++) {
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var bb = lb[i];
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var block = bb as Block;
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if (block != null && placeLast(block))
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lastIndex = i;
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bbs.Add(bb);
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}
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if (lastIndex != -1) {
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var block = (Block)bbs[lastIndex];
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bbs.RemoveAt(lastIndex);
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bbs.Add(block);
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}
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foreach (var bb in bbs)
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DoBaseBlock(bb);
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}
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// Returns the BaseBlock's ScopeBlock. The return value is either current ScopeBlock,
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// the ScopeBlock one step below current (current one's child), or null.
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ScopeBlock GetScopeBlock(BaseBlock bb) {
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BlockState current = stateStack.Peek();
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if (current.scopeBlock.IsOurBaseBlock(bb))
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return current.scopeBlock;
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return (ScopeBlock)current.scopeBlock.ToChild(bb);
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}
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void DoBaseBlock(BaseBlock bb) {
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BlockState current = stateStack.Peek();
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ScopeBlock newOne = GetScopeBlock(bb);
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if (newOne == null)
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return; // Not a BaseBlock somewhere inside this ScopeBlock
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if (newOne != current.scopeBlock)
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bb = newOne;
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bool hasVisited;
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if (!visited.TryGetValue(bb, out hasVisited))
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visited[bb] = hasVisited = false;
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if (hasVisited)
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return;
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visited[bb] = true;
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if (bb is Block)
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DoBlock(bb as Block);
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else if (bb is TryBlock)
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DoTryBlock(bb as TryBlock);
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else if (bb is FilterHandlerBlock)
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DoFilterHandlerBlock(bb as FilterHandlerBlock);
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else if (bb is HandlerBlock)
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DoHandlerBlock(bb as HandlerBlock);
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else if (bb is TryHandlerBlock) {
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// The try handler block is usually after the try block, but sometimes it isn't...
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// Handle that case here.
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visited.Remove(bb);
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notProcessedYet.Add(bb);
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}
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else
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throw new ApplicationException("Invalid block found");
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}
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void DoBlock(Block block) {
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blocks.Add(block);
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}
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void DoTryBlock(TryBlock tryBlock) {
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var tryStart = blocks.Count;
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stateStack.Push(new BlockState(tryBlock));
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ProcessBaseBlocks(tryBlock.BaseBlocks, (block) => {
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return block.LastInstr.OpCode == OpCodes.Leave ||
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block.LastInstr.OpCode == OpCodes.Leave_S;
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});
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stateStack.Pop();
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var tryEnd = blocks.Count - 1;
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if (tryBlock.TryHandlerBlocks.Count == 0)
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throw new ApplicationException("No handler blocks");
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foreach (var handlerBlock in tryBlock.TryHandlerBlocks) {
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visited[handlerBlock] = true;
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stateStack.Push(new BlockState(handlerBlock));
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var filterStart = blocks.Count;
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if (handlerBlock.FilterHandlerBlock.BaseBlocks != null)
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DoBaseBlock(handlerBlock.FilterHandlerBlock);
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var handlerStart = blocks.Count;
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DoBaseBlock(handlerBlock.HandlerBlock);
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var handlerEnd = blocks.Count - 1;
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exceptions.Add(new ExceptionInfo(tryStart, tryEnd, filterStart, handlerStart, handlerEnd, handlerBlock.CatchType, handlerBlock.HandlerType));
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stateStack.Pop();
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}
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}
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void DoFilterHandlerBlock(FilterHandlerBlock filterHandlerBlock) {
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stateStack.Push(new BlockState(filterHandlerBlock));
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ProcessBaseBlocks(filterHandlerBlock.BaseBlocks, (block) => {
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return block.LastInstr.OpCode == OpCodes.Endfilter; // MUST end with endfilter!
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});
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stateStack.Pop();
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}
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void DoHandlerBlock(HandlerBlock handlerBlock) {
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stateStack.Push(new BlockState(handlerBlock));
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ProcessBaseBlocks(handlerBlock.BaseBlocks, (block) => {
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return block.LastInstr.OpCode == OpCodes.Endfinally ||
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block.LastInstr.OpCode == OpCodes.Leave ||
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block.LastInstr.OpCode == OpCodes.Leave_S;
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});
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stateStack.Pop();
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}
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}
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}
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