Remove pop instrs and code that pushes the value
This commit is contained in:
de4dot
parent
f519d6f6d8
commit
d7c61c65fe
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@ -105,7 +105,7 @@ namespace de4dot.blocks {
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}
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public void remove(IEnumerable<int> indexes) {
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var instrsToDelete = new List<int>(indexes);
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var instrsToDelete = new List<int>(Utils.unique(indexes));
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instrsToDelete.Sort();
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instrsToDelete.Reverse();
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foreach (var index in instrsToDelete)
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@ -41,5 +41,13 @@ namespace de4dot.blocks {
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olist.Add(l);
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return olist;
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}
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public static IEnumerable<T> unique<T>(IEnumerable<T> values) {
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// HashSet is only available in .NET 3.5 and later.
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var dict = new Dictionary<T, bool>();
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foreach (var val in values)
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dict[val] = true;
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return dict.Keys;
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}
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}
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}
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@ -37,6 +37,7 @@
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<Compile Include="BlocksSorter.cs" />
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<Compile Include="cflow\BlockCflowDeobfuscator.cs" />
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<Compile Include="cflow\CflowUtils.cs" />
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<Compile Include="cflow\DeadCodeRemover.cs" />
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<Compile Include="cflow\InstructionEmulator.cs" />
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<Compile Include="cflow\Int32Value.cs" />
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<Compile Include="cflow\Int64Value.cs" />
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@ -38,6 +38,7 @@ namespace de4dot.blocks.cflow {
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public void deobfuscate() {
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var allBlocks = new List<Block>();
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var switchCflowDeobfuscator = new SwitchCflowDeobfuscator();
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var deadCodeRemover = new DeadCodeRemover();
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bool changed;
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do {
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changed = false;
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@ -57,6 +58,9 @@ namespace de4dot.blocks.cflow {
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switchCflowDeobfuscator.init(blocks, allBlocks);
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changed |= switchCflowDeobfuscator.deobfuscate();
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deadCodeRemover.init(allBlocks);
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changed |= deadCodeRemover.remove();
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} while (changed);
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}
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366
blocks/cflow/DeadCodeRemover.cs
Normal file
366
blocks/cflow/DeadCodeRemover.cs
Normal file
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@ -0,0 +1,366 @@
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/*
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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.Collections.Generic;
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using Mono.Cecil.Cil;
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namespace de4dot.blocks.cflow {
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class DeadCodeRemover {
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List<Block> allBlocks;
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List<int> allDeadInstructions = new List<int>();
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InstructionExpressionFinder instructionExpressionFinder = new InstructionExpressionFinder();
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public void init(List<Block> allBlocks) {
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this.allBlocks = allBlocks;
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}
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public bool remove() {
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bool changed = false;
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foreach (var block in allBlocks)
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changed |= remove(block);
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return changed;
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}
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bool remove(Block block) {
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allDeadInstructions.Clear();
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var instructions = block.Instructions;
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for (int i = 0; i < instructions.Count; i++) {
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var instr = instructions[i];
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if (instr.OpCode.Code != Code.Pop)
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continue;
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instructionExpressionFinder.init(block, false);
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if (!instructionExpressionFinder.find(i))
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continue;
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if (!okInstructions(block, instructionExpressionFinder.DeadInstructions))
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continue;
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allDeadInstructions.AddRange(instructionExpressionFinder.DeadInstructions);
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}
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block.remove(allDeadInstructions);
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return allDeadInstructions.Count > 0;
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}
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bool okInstructions(Block block, IEnumerable<int> indexes) {
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foreach (var index in indexes) {
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var instr = block.Instructions[index];
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switch (instr.OpCode.Code) {
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case Code.Add:
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case Code.Add_Ovf:
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case Code.Add_Ovf_Un:
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case Code.And:
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case Code.Arglist:
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case Code.Beq:
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case Code.Beq_S:
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case Code.Bge:
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case Code.Bge_S:
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case Code.Bge_Un:
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case Code.Bge_Un_S:
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case Code.Bgt:
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case Code.Bgt_S:
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case Code.Bgt_Un:
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case Code.Bgt_Un_S:
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case Code.Ble:
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case Code.Ble_S:
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case Code.Ble_Un:
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case Code.Ble_Un_S:
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case Code.Blt:
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case Code.Blt_S:
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case Code.Blt_Un:
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case Code.Blt_Un_S:
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case Code.Bne_Un:
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case Code.Bne_Un_S:
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case Code.Box:
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case Code.Br:
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case Code.Br_S:
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case Code.Break:
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case Code.Brfalse:
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case Code.Brfalse_S:
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case Code.Brtrue:
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case Code.Brtrue_S:
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case Code.Castclass:
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case Code.Ceq:
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case Code.Cgt:
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case Code.Cgt_Un:
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case Code.Ckfinite:
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case Code.Clt:
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case Code.Clt_Un:
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case Code.Constrained:
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case Code.Conv_I:
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case Code.Conv_I1:
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case Code.Conv_I2:
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case Code.Conv_I4:
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case Code.Conv_I8:
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case Code.Conv_Ovf_I:
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case Code.Conv_Ovf_I1:
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case Code.Conv_Ovf_I1_Un:
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case Code.Conv_Ovf_I2:
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case Code.Conv_Ovf_I2_Un:
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case Code.Conv_Ovf_I4:
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case Code.Conv_Ovf_I4_Un:
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case Code.Conv_Ovf_I8:
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case Code.Conv_Ovf_I8_Un:
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case Code.Conv_Ovf_I_Un:
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case Code.Conv_Ovf_U:
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case Code.Conv_Ovf_U1:
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case Code.Conv_Ovf_U1_Un:
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case Code.Conv_Ovf_U2:
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case Code.Conv_Ovf_U2_Un:
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case Code.Conv_Ovf_U4:
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case Code.Conv_Ovf_U4_Un:
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case Code.Conv_Ovf_U8:
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case Code.Conv_Ovf_U8_Un:
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case Code.Conv_Ovf_U_Un:
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case Code.Conv_R4:
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case Code.Conv_R8:
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case Code.Conv_R_Un:
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case Code.Conv_U:
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case Code.Conv_U1:
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case Code.Conv_U2:
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case Code.Conv_U4:
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case Code.Conv_U8:
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case Code.Div:
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case Code.Div_Un:
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case Code.Dup:
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case Code.Endfilter:
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case Code.Endfinally:
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case Code.Isinst:
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case Code.Jmp:
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case Code.Ldarg:
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case Code.Ldarg_0:
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case Code.Ldarg_1:
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case Code.Ldarg_2:
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case Code.Ldarg_3:
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case Code.Ldarg_S:
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case Code.Ldarga:
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case Code.Ldarga_S:
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case Code.Ldc_I4:
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case Code.Ldc_I4_0:
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case Code.Ldc_I4_1:
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case Code.Ldc_I4_2:
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case Code.Ldc_I4_3:
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case Code.Ldc_I4_4:
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case Code.Ldc_I4_5:
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case Code.Ldc_I4_6:
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case Code.Ldc_I4_7:
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case Code.Ldc_I4_8:
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case Code.Ldc_I4_M1:
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case Code.Ldc_I4_S:
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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.Ldelem_Any:
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case Code.Ldelem_I:
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case Code.Ldelem_I1:
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case Code.Ldelem_I2:
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case Code.Ldelem_I4:
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case Code.Ldelem_I8:
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case Code.Ldelem_R4:
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case Code.Ldelem_R8:
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case Code.Ldelem_Ref:
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case Code.Ldelem_U1:
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case Code.Ldelem_U2:
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case Code.Ldelem_U4:
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case Code.Ldelema:
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case Code.Ldfld:
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case Code.Ldflda:
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case Code.Ldftn:
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case Code.Ldind_I:
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case Code.Ldind_I1:
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case Code.Ldind_I2:
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case Code.Ldind_I4:
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case Code.Ldind_I8:
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case Code.Ldind_R4:
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case Code.Ldind_R8:
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case Code.Ldind_Ref:
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case Code.Ldind_U1:
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case Code.Ldind_U2:
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case Code.Ldind_U4:
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case Code.Ldlen:
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case Code.Ldloc:
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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.Ldloc_S:
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case Code.Ldloca:
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case Code.Ldloca_S:
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case Code.Ldnull:
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case Code.Ldobj:
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case Code.Ldsfld:
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case Code.Ldsflda:
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case Code.Ldstr:
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case Code.Ldtoken:
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case Code.Ldvirtftn:
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case Code.Leave:
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case Code.Leave_S:
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case Code.Localloc:
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case Code.Mkrefany:
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case Code.Mul:
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case Code.Mul_Ovf:
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case Code.Mul_Ovf_Un:
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case Code.Neg:
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case Code.Newarr:
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case Code.No:
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case Code.Nop:
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case Code.Not:
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case Code.Or:
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case Code.Pop:
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case Code.Readonly:
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case Code.Refanytype:
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case Code.Refanyval:
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case Code.Rem:
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case Code.Rem_Un:
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case Code.Ret:
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case Code.Rethrow:
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case Code.Shl:
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case Code.Shr:
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case Code.Shr_Un:
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case Code.Sizeof:
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case Code.Sub:
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case Code.Sub_Ovf:
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case Code.Sub_Ovf_Un:
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case Code.Switch:
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case Code.Tail:
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case Code.Throw:
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case Code.Unaligned:
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case Code.Unbox:
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case Code.Unbox_Any:
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case Code.Volatile:
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case Code.Xor:
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break;
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case Code.Call:
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case Code.Calli:
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case Code.Callvirt:
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case Code.Cpblk:
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case Code.Cpobj:
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case Code.Initblk:
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case Code.Initobj:
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case Code.Newobj:
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case Code.Starg:
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case Code.Starg_S:
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case Code.Stelem_Any:
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case Code.Stelem_I:
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case Code.Stelem_I1:
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case Code.Stelem_I2:
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case Code.Stelem_I4:
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case Code.Stelem_I8:
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case Code.Stelem_R4:
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case Code.Stelem_R8:
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case Code.Stelem_Ref:
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case Code.Stfld:
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case Code.Stind_I:
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case Code.Stind_I1:
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case Code.Stind_I2:
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case Code.Stind_I4:
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case Code.Stind_I8:
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case Code.Stind_R4:
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case Code.Stind_R8:
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case Code.Stind_Ref:
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case Code.Stloc:
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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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case Code.Stloc_S:
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case Code.Stobj:
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case Code.Stsfld:
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default:
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return false;
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}
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}
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return true;
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}
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class InstructionExpressionFinder {
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List<int> deadInstructions = new List<int>();
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Block block;
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bool methodHasReturnValue;
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public List<int> DeadInstructions {
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get { return deadInstructions; }
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}
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public void init(Block block, bool methodHasReturnValue) {
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deadInstructions.Clear();
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this.block = block;
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this.methodHasReturnValue = methodHasReturnValue;
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}
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public bool find(int index) {
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return find(ref index, true);
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}
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bool find(ref int index, bool addIt) {
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if (index < 0)
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return false;
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if (addIt)
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addIndex(index);
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var startInstr = block.Instructions[index];
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int startInstrPushes, startInstrPops;
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DotNetUtils.calculateStackUsage(startInstr.Instruction, false, out startInstrPushes, out startInstrPops);
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if (startInstrPops == 0)
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return true;
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if (startInstrPops < 0)
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return false; // Eg. leave
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while (index > 0) {
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var instr = block.Instructions[index - 1];
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if (startInstrPops == 0 && instr.OpCode.OpCodeType != OpCodeType.Prefix)
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break;
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index--;
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int pushes, pops;
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DotNetUtils.calculateStackUsage(instr.Instruction, methodHasReturnValue, out pushes, out pops);
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if (pops < 0)
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return false; // eg. leave
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if (pops > 0) { // if instr uses any args
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bool otherExpr = pops > 0 && pushes == 0;
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if (!find(ref index, addIt && !otherExpr))
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return false;
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}
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else {
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if (addIt)
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addIndex(index);
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}
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if (pushes > 0) {
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if (pushes > startInstrPops)
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return false;
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startInstrPops -= pushes;
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}
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}
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return startInstrPops == 0;
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}
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void addIndex(int index) {
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deadInstructions.Add(index);
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}
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}
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}
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}
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Reference in New Issue
Block a user