111 lines
3.8 KiB
C#
111 lines
3.8 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.IO;
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using System.Linq;
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using System.Reflection;
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using System.Reflection.Emit;
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using NLog;
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using Torch.Managers.PatchManager.MSIL;
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namespace Torch.Managers.PatchManager.Transpile
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{
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internal class MethodContext
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{
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private static readonly Logger _log = LogManager.GetCurrentClassLogger();
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public readonly MethodBase Method;
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private readonly byte[] _msilBytes;
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internal Dictionary<int, MsilLabel> Labels { get; } = new Dictionary<int, MsilLabel>();
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private readonly List<MsilInstruction> _instructions = new List<MsilInstruction>();
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public IReadOnlyList<MsilInstruction> Instructions => _instructions;
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internal ITokenResolver TokenResolver { get; }
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internal MsilLabel LabelAt(int i)
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{
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if (Labels.TryGetValue(i, out MsilLabel label))
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return label;
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Labels.Add(i, label = new MsilLabel());
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return label;
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}
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public MethodContext(MethodBase method)
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{
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Method = method;
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_msilBytes = Method.GetMethodBody().GetILAsByteArray();
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TokenResolver = new NormalTokenResolver(method);
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}
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public void Read()
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{
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ReadInstructions();
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ResolveLabels();
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}
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private void ReadInstructions()
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{
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Labels.Clear();
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_instructions.Clear();
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using (var memory = new MemoryStream(_msilBytes))
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using (var reader = new BinaryReader(memory))
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while (memory.Length > memory.Position)
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{
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var instructionValue = (short)memory.ReadByte();
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if (Prefixes.Contains(instructionValue))
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instructionValue = (short)((instructionValue << 8) | memory.ReadByte());
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if (!OpCodeLookup.TryGetValue(instructionValue, out OpCode opcode))
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throw new Exception($"Unknown opcode {instructionValue:X}");
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var instruction = new MsilInstruction(opcode)
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{
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Offset = (int) memory.Position
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};
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_instructions.Add(instruction);
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instruction.Operand?.Read(this, reader);
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}
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}
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private void ResolveLabels()
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{
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foreach (var label in Labels)
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{
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int min = 0, max = _instructions.Count - 1;
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while (min <= max)
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{
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var mid = min + ((max - min) / 2);
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if (label.Key < _instructions[mid].Offset)
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max = mid - 1;
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else
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min = mid + 1;
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}
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_instructions[min]?.Labels?.Add(label.Value);
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}
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}
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public string ToHumanMsil()
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{
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return string.Join("\n", _instructions.Select(x => x.Offset + "\t" + x));
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}
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private static readonly Dictionary<short, OpCode> OpCodeLookup;
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private static readonly HashSet<short> Prefixes;
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static MethodContext()
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{
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OpCodeLookup = new Dictionary<short, OpCode>();
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Prefixes = new HashSet<short>();
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foreach (FieldInfo field in typeof(OpCodes).GetFields(BindingFlags.Static | BindingFlags.Public))
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{
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var opcode = (OpCode)field.GetValue(null);
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if (opcode.OpCodeType != OpCodeType.Nternal)
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OpCodeLookup.Add(opcode.Value, opcode);
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if ((ushort) opcode.Value > 0xFF)
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{
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Prefixes.Add((short) ((ushort) opcode.Value >> 8));
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}
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}
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}
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}
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}
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