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// Copyright (c) 2011 AlphaSierraPapa for the SharpDevelop Team
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
using System;
using System.Diagnostics;
using System.IO;
using ICSharpCode.Decompiler.Disassembler;
using Mono.Cecil;
using Mono.Cecil.Cil;
namespace ICSharpCode.Decompiler.FlowAnalysis
{
public enum SpecialOpCode
{
/// <summary>
/// No special op code: SsaInstruction has a normal IL instruction
/// </summary>
None,
/// <summary>
/// Φ function: chooses the appropriate variable based on which CFG edge was used to enter this block
/// </summary>
Phi,
/// <summary>
/// Variable is read from before passing it by ref.
/// This instruction constructs a managed reference to the variable.
/// </summary>
PrepareByRefCall,
/// <summary>
/// This instruction constructs a managed reference to the variable.
/// The variable is not really read from.
/// </summary>
PrepareByOutCall,
/// <summary>
/// This instruction constructs a managed reference to the variable.
/// The reference is used for a field access on a value type.
/// </summary>
PrepareForFieldAccess,
/// <summary>
/// Variable is written to after passing it by ref or out.
/// </summary>
WriteAfterByRefOrOutCall,
/// <summary>
/// Variable is not initialized.
/// </summary>
Uninitialized,
/// <summary>
/// Value is passed in as parameter
/// </summary>
Parameter,
/// <summary>
/// Value is a caught exception.
/// TypeOperand is set to the exception type.
/// </summary>
Exception,
/// <summary>
/// Initialize a value type. Unlike the real initobj instruction, this one does not take an address
/// but assigns to the target variable.
/// TypeOperand is set to the type being created.
/// </summary>
InitObj
}
public sealed class SsaInstruction
{
public readonly SsaBlock ParentBlock;
public readonly SpecialOpCode SpecialOpCode;
/// <summary>
/// The original IL instruction.
/// May be null for "invented" instructions (SpecialOpCode != None).
/// </summary>
public readonly Instruction Instruction;
/// <summary>
/// Prefixes in front of the IL instruction.
/// </summary>
public readonly Instruction[] Prefixes;
/// <summary>
/// Gets the type operand. This is used only in combination with some special opcodes.
/// </summary>
public readonly TypeReference TypeOperand;
public SsaVariable Target;
public SsaVariable[] Operands;
static readonly SsaVariable[] emptyVariableArray = {};
static readonly Instruction[] emptyInstructionArray = {};
public SsaInstruction(SsaBlock parentBlock, Instruction instruction, SsaVariable target, SsaVariable[] operands,
Instruction[] prefixes = null, SpecialOpCode specialOpCode = SpecialOpCode.None,
TypeReference typeOperand = null)
{
this.ParentBlock = parentBlock;
this.Instruction = instruction;
this.Prefixes = prefixes ?? emptyInstructionArray;
this.Target = target;
this.Operands = operands ?? emptyVariableArray;
this.SpecialOpCode = specialOpCode;
this.TypeOperand = typeOperand;
Debug.Assert((typeOperand != null) == (specialOpCode == SpecialOpCode.Exception || specialOpCode == SpecialOpCode.InitObj));
}
/// <summary>
/// Gets whether this instruction is a simple assignment from one variable to another.
/// </summary>
public bool IsMoveInstruction {
get {
return Target != null && Operands.Length == 1 && Instruction != null && OpCodeInfo.Get(Instruction.OpCode).IsMoveInstruction;
}
}
public void ReplaceVariableInOperands(SsaVariable oldVar, SsaVariable newVar)
{
for (int i = 0; i < this.Operands.Length; i++) {
if (this.Operands[i] == oldVar)
this.Operands[i] = newVar;
}
}
public override string ToString()
{
StringWriter w = new StringWriter();
WriteTo(w);
return w.ToString();
}
public void WriteTo(TextWriter writer)
{
foreach (Instruction prefix in this.Prefixes) {
Disassembler.DisassemblerHelpers.WriteTo(prefix, new PlainTextOutput(writer));
writer.WriteLine();
}
if (Instruction != null && Instruction.Offset >= 0) {
writer.Write(CecilExtensions.OffsetToString(Instruction.Offset));
writer.Write(": ");
}
if (Target != null) {
writer.Write(Target.ToString());
writer.Write(" = ");
}
if (IsMoveInstruction) {
writer.Write(Operands[0].ToString());
if (Instruction != null) {
writer.Write(" (" + Instruction.OpCode.Name + ")");
}
} else {
if (Instruction == null) {
writer.Write(SpecialOpCode.ToString());
} else {
writer.Write(Instruction.OpCode.Name);
if(null != Instruction.Operand) {
writer.Write(' ');
Disassembler.DisassemblerHelpers.WriteOperand(new PlainTextOutput(writer), Instruction.Operand);
writer.Write(' ');
}
}
if (TypeOperand != null) {
writer.Write(' ');
writer.Write(TypeOperand.ToString());
writer.Write(' ');
}
if (Operands.Length > 0) {
writer.Write('(');
for (int i = 0; i < Operands.Length; i++) {
if (i > 0)
writer.Write(", ");
writer.Write(Operands[i].ToString());
}
writer.Write(')');
}
}
}
}
}
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