308 lines
8.0 KiB
C#
308 lines
8.0 KiB
C#
/*
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Copyright (C) 2011 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 Mono.Cecil;
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using Mono.Cecil.Cil;
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using de4dot.blocks;
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namespace de4dot {
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// A simple class that statically detects the values of some local variables
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class VariableValues {
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IList<Block> allBlocks;
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IList<VariableDefinition> locals;
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Dictionary<VariableDefinition, Variable> variableToValue = new Dictionary<VariableDefinition, Variable>();
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public class Variable {
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int writes = 0;
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object value;
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bool unknownValue = false;
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public bool isValid() {
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return !unknownValue && writes == 1;
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}
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public object Value {
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get {
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if (!isValid())
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throw new ApplicationException("Unknown variable value");
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return value;
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}
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set { this.value = value; }
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}
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public void addWrite() {
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writes++;
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}
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public void setUnknown() {
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unknownValue = true;
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}
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}
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public VariableValues(IList<VariableDefinition> locals, IList<Block> allBlocks) {
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this.locals = locals;
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this.allBlocks = allBlocks;
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init();
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}
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void init() {
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foreach (var variable in locals)
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variableToValue[variable] = new Variable();
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foreach (var block in allBlocks) {
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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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switch (instr.OpCode.Code) {
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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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var variable = Instr.getLocalVar(locals, instr);
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var val = variableToValue[variable];
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val.addWrite();
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object obj;
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if (!getValue(block, i, out obj))
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val.setUnknown();
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val.Value = obj;
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break;
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default:
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break;
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}
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}
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}
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}
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bool getValue(Block block, int index, out object obj) {
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while (true) {
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if (index <= 0) {
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obj = null;
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return false;
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}
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var instr = block.Instructions[--index];
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if (instr.OpCode == OpCodes.Nop)
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continue;
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switch (instr.OpCode.Code) {
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case Code.Ldc_I4:
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case Code.Ldc_I8:
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case Code.Ldc_R4:
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case Code.Ldc_R8:
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case Code.Ldstr:
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obj = instr.Operand;
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return true;
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case Code.Ldc_I4_S:
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obj = (int)(sbyte)instr.Operand;
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return true;
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case Code.Ldc_I4_0: obj = 0; return true;
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case Code.Ldc_I4_1: obj = 1; return true;
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case Code.Ldc_I4_2: obj = 2; return true;
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case Code.Ldc_I4_3: obj = 3; return true;
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case Code.Ldc_I4_4: obj = 4; return true;
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case Code.Ldc_I4_5: obj = 5; return true;
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case Code.Ldc_I4_6: obj = 6; return true;
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case Code.Ldc_I4_7: obj = 7; return true;
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case Code.Ldc_I4_8: obj = 8; return true;
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case Code.Ldc_I4_M1:obj = -1; return true;
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case Code.Ldnull: obj = null; return true;
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default:
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obj = null;
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return false;
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}
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}
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}
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public Variable getValue(VariableDefinition variable) {
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return variableToValue[variable];
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}
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}
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abstract class MethodReturnValueInliner {
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protected List<CallResult> callResults;
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List<Block> allBlocks;
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Blocks blocks;
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VariableValues variableValues;
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protected class CallResult {
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public Block block;
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public int callStartIndex;
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public int callEndIndex;
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public object[] args;
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public object returnValue;
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public CallResult(Block block, int callEndIndex) {
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this.block = block;
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this.callEndIndex = callEndIndex;
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}
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public MethodReference getMethodReference() {
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return (MethodReference)block.Instructions[callEndIndex].Operand;
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}
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}
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protected abstract void inlineAllCalls();
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// Returns null if method is not a method we should inline
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protected abstract CallResult createCallResult(MethodReference method, Block block, int callInstrIndex);
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public int decrypt(Blocks theBlocks) {
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try {
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blocks = theBlocks;
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callResults = new List<CallResult>();
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allBlocks = new List<Block>(blocks.MethodBlocks.getAllBlocks());
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findAllCallResults();
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inlineAllCalls();
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inlineReturnValues();
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return callResults.Count;
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}
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finally {
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blocks = null;
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callResults = null;
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allBlocks = null;
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variableValues = null;
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}
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}
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void getLocalVariableValue(VariableDefinition variable, out object value) {
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if (variableValues == null)
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variableValues = new VariableValues(blocks.Locals, allBlocks);
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var val = variableValues.getValue(variable);
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if (!val.isValid())
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throw new ApplicationException("Could not get value of local variable");
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value = val.Value;
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}
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void findAllCallResults() {
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foreach (var block in allBlocks)
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findCallResults(block);
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}
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void findCallResults(Block block) {
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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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if (instr.OpCode != OpCodes.Call)
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continue;
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var method = instr.Operand as MethodReference;
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if (method == null)
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continue;
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var callResult = createCallResult(method, block, i);
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if (callResult == null)
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continue;
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callResults.Add(callResult);
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findArgs(callResult);
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}
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}
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void findArgs(CallResult callResult) {
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var block = callResult.block;
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var method = callResult.getMethodReference();
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int numArgs = method.Parameters.Count + (method.HasThis ? 1 : 0);
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var args = new object[numArgs];
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int instrIndex = callResult.callEndIndex - 1;
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for (int i = numArgs - 1; i >= 0; i--)
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getArg(method, block, ref args[i], ref instrIndex);
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callResult.args = args;
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callResult.callStartIndex = instrIndex + 1;
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}
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void getArg(MethodReference method, Block block, ref object arg, ref int instrIndex) {
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while (true) {
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if (instrIndex < 0)
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throw new ApplicationException(string.Format("Could not find all arguments to method {0}", method));
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var instr = block.Instructions[instrIndex--];
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switch (instr.OpCode.Code) {
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case Code.Ldc_I4:
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case Code.Ldc_I8:
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case Code.Ldc_R4:
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case Code.Ldc_R8:
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case Code.Ldstr:
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arg = instr.Operand;
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break;
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case Code.Ldc_I4_S:
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arg = (int)(sbyte)instr.Operand;
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break;
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case Code.Ldc_I4_0: arg = 0; break;
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case Code.Ldc_I4_1: arg = 1; break;
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case Code.Ldc_I4_2: arg = 2; break;
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case Code.Ldc_I4_3: arg = 3; break;
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case Code.Ldc_I4_4: arg = 4; break;
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case Code.Ldc_I4_5: arg = 5; break;
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case Code.Ldc_I4_6: arg = 6; break;
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case Code.Ldc_I4_7: arg = 7; break;
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case Code.Ldc_I4_8: arg = 8; break;
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case Code.Ldc_I4_M1:arg = -1; break;
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case Code.Ldnull: arg = null; break;
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case Code.Nop:
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continue;
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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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getLocalVariableValue(Instr.getLocalVar(blocks.Locals, instr), out arg);
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break;
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case Code.Ldsfld:
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arg = instr.Operand;
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break;
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default:
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throw new ApplicationException(string.Format("Could not find all arguments to method {0}, instr: {1}", method, instr));
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}
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break;
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}
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}
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void inlineReturnValues() {
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callResults.Sort((a, b) => {
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int i1 = allBlocks.FindIndex((x) => a.block == x);
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int i2 = allBlocks.FindIndex((x) => b.block == x);
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if (i1 < i2) return -1;
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if (i1 > i2) return 1;
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if (a.callStartIndex < b.callStartIndex) return -1;
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if (a.callStartIndex > b.callStartIndex) return 1;
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return 0;
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});
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callResults.Reverse();
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inlineReturnValues(callResults);
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}
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protected abstract void inlineReturnValues(IList<CallResult> callResults);
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}
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}
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