262 lines
8.1 KiB
C#
262 lines
8.1 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.Collections.Generic;
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using Mono.Cecil;
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using Mono.Cecil.Cil;
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namespace de4dot.blocks.cflow {
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class BlockCflowDeobfuscator {
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Blocks blocks;
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Block block;
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InstructionEmulator instructionEmulator = new InstructionEmulator();
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public void init(Blocks blocks, Block block) {
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this.blocks = blocks;
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this.block = block;
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instructionEmulator.init(blocks.Method.HasThis, false, blocks.Method.Parameters, blocks.Locals);
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}
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// Returns true if code was updated, false otherwise
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public bool deobfuscate() {
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var instructions = block.Instructions;
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if (instructions.Count == 0)
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return false;
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for (int i = 0; i < instructions.Count - 1; i++) {
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var instr = instructions[i].Instruction;
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instructionEmulator.emulate(instr);
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}
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switch (block.LastInstr.OpCode.Code) {
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case Code.Beq:
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case Code.Beq_S: return emulate_Beq();
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case Code.Bge:
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case Code.Bge_S: return emulate_Bge();
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case Code.Bge_Un:
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case Code.Bge_Un_S: return emulate_Bge_Un();
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case Code.Bgt:
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case Code.Bgt_S: return emulate_Bgt();
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case Code.Bgt_Un:
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case Code.Bgt_Un_S: return emulate_Bgt_Un();
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case Code.Ble:
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case Code.Ble_S: return emulate_Ble();
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case Code.Ble_Un:
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case Code.Ble_Un_S: return emulate_Ble_Un();
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case Code.Blt:
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case Code.Blt_S: return emulate_Blt();
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case Code.Blt_Un:
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case Code.Blt_Un_S: return emulate_Blt_Un();
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case Code.Bne_Un:
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case Code.Bne_Un_S: return emulate_Bne_Un();
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case Code.Brfalse:
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case Code.Brfalse_S:return emulate_Brfalse();
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case Code.Brtrue:
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case Code.Brtrue_S: return emulate_Brtrue();
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case Code.Switch: return emulate_Switch();
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default:
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return false;
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}
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}
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bool emulateBranch(int stackArgs, Bool3 cond) {
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if (cond == Bool3.Unknown)
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return false;
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return emulateBranch(stackArgs, cond == Bool3.True);
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}
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bool emulateBranch(int stackArgs, bool isTaken) {
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popPushedArgs(stackArgs);
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block.replaceBccWithBranch(isTaken);
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return true;
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}
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void popPushedArgs(int stackArgs) {
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// Pop the arguments to the bcc instruction. The dead code remover will get rid of the
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// pop and any pushed arguments. Insert the pops just before the bcc instr.
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for (int i = 0; i < stackArgs; i++)
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block.insert(block.Instructions.Count - 1, Instruction.Create(OpCodes.Pop));
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}
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bool emulate_Beq() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareEq((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareEq((Int64Value)val1, (Int64Value)val2));
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else if (val1.isNull() && val2.isNull())
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return emulateBranch(2, true);
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else
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return false;
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}
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bool emulate_Bne_Un() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareNeq((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareNeq((Int64Value)val1, (Int64Value)val2));
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else if (val1.isNull() && val2.isNull())
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return emulateBranch(2, false);
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else
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return false;
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}
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bool emulate_Bge() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareGe((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareGe((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Bge_Un() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareGe_Un((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareGe_Un((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Bgt() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareGt((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareGt((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Bgt_Un() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareGt_Un((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareGt_Un((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Ble() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareLe((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareLe((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Ble_Un() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareLe_Un((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareLe_Un((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Blt() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareLt((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareLt((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Blt_Un() {
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var val2 = instructionEmulator.pop();
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var val1 = instructionEmulator.pop();
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if (val1.isInt32() && val2.isInt32())
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return emulateBranch(2, Int32Value.compareLt_Un((Int32Value)val1, (Int32Value)val2));
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else if (val1.isInt64() && val2.isInt64())
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return emulateBranch(2, Int64Value.compareLt_Un((Int64Value)val1, (Int64Value)val2));
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else
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return false;
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}
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bool emulate_Brfalse() {
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var val1 = instructionEmulator.pop();
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if (val1.isInt32())
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return emulateBranch(1, Int32Value.compareFalse((Int32Value)val1));
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else if (val1.isInt64())
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return emulateBranch(1, Int64Value.compareFalse((Int64Value)val1));
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else if (val1.isNull())
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return emulateBranch(1, true);
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else
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return false;
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}
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bool emulate_Brtrue() {
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var val1 = instructionEmulator.pop();
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if (val1.isInt32())
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return emulateBranch(1, Int32Value.compareTrue((Int32Value)val1));
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else if (val1.isInt64())
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return emulateBranch(1, Int64Value.compareTrue((Int64Value)val1));
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else if (val1.isNull())
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return emulateBranch(1, false);
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else
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return false;
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}
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bool emulate_Switch() {
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var val1 = instructionEmulator.pop();
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if (!val1.isInt32())
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return false;
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var target = CflowUtils.getSwitchTarget(block.Targets, block.FallThrough, (Int32Value)val1);
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if (target == null)
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return false;
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popPushedArgs(1);
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block.replaceSwitchWithBranch(target);
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return true;
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}
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}
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}
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