source: branches/PersistentDataStructures/HeuristicLab.ExtLibs/HeuristicLab.Cecil/0.9.5/Mono.Cecil-0.9.5/Mono.Cecil/Mono.Cecil.Cil/CodeWriter.cs

//
// CodeWriter.cs
//
// Author:
//   Jb Evain (jbevain@gmail.com)
//
// Copyright (c) 2008 - 2011 Jb Evain
//
// 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.Collections.Generic;

using Mono.Collections.Generic;

using Mono.Cecil.Metadata;
using Mono.Cecil.PE;

using RVA = System.UInt32;

#if !READ_ONLY

namespace Mono.Cecil.Cil {

  sealed class CodeWriter : ByteBuffer {

    readonly RVA code_base;
    internal readonly MetadataBuilder metadata;
    readonly Dictionary<uint, MetadataToken> standalone_signatures;

    RVA current;
    MethodBody body;

    public CodeWriter (MetadataBuilder metadata)
      : base (0)
    {
      this.code_base = metadata.text_map.GetNextRVA (TextSegment.CLIHeader);
      this.current = code_base;
      this.metadata = metadata;
      this.standalone_signatures = new Dictionary<uint, MetadataToken> ();
    }

    public RVA WriteMethodBody (MethodDefinition method)
    {
      var rva = BeginMethod ();

      if (IsUnresolved (method)) {
        if (method.rva == 0)
          return 0;

        WriteUnresolvedMethodBody (method);
      } else {
        if (IsEmptyMethodBody (method.Body))
          return 0;

        WriteResolvedMethodBody (method);
      }

      Align (4);

      EndMethod ();
      return rva;
    }

    static bool IsEmptyMethodBody (MethodBody body)
    {
      return body.instructions.IsNullOrEmpty ()
        && body.variables.IsNullOrEmpty ();
    }

    static bool IsUnresolved (MethodDefinition method)
    {
      return method.HasBody && method.HasImage && method.body == null;
    }

    void WriteUnresolvedMethodBody (MethodDefinition method)
    {
      var code_reader = metadata.module.Read (method, (_, reader) => reader.code);

      MethodSymbols symbols;
      var buffer = code_reader.PatchRawMethodBody (method, this, out symbols);

      WriteBytes (buffer);

      if (symbols.instructions.IsNullOrEmpty ())
        return;

      symbols.method_token = method.token;
      symbols.local_var_token = GetLocalVarToken (buffer, symbols);

      var symbol_writer = metadata.symbol_writer;
      if (symbol_writer != null)
        symbol_writer.Write (symbols);
    }

    static MetadataToken GetLocalVarToken (ByteBuffer buffer, MethodSymbols symbols)
    {
      if (symbols.variables.IsNullOrEmpty ())
        return MetadataToken.Zero;

      buffer.position = 8;
      return new MetadataToken (buffer.ReadUInt32 ());
    }

    void WriteResolvedMethodBody (MethodDefinition method)
    {
      body = method.Body;
      ComputeHeader ();
      if (RequiresFatHeader ())
        WriteFatHeader ();
      else
        WriteByte ((byte) (0x2 | (body.CodeSize << 2))); // tiny

      WriteInstructions ();

      if (body.HasExceptionHandlers)
        WriteExceptionHandlers ();

      var symbol_writer = metadata.symbol_writer;
      if (symbol_writer != null)
        symbol_writer.Write (body);
    }

    void WriteFatHeader ()
    {
      var body = this.body;
      byte flags = 0x3; // fat
      if (body.InitLocals)
        flags |= 0x10;  // init locals
      if (body.HasExceptionHandlers)
        flags |= 0x8; // more sections

      WriteByte (flags);
      WriteByte (0x30);
      WriteInt16 ((short) body.max_stack_size);
      WriteInt32 (body.code_size);
      body.local_var_token = body.HasVariables
        ? GetStandAloneSignature (body.Variables)
        : MetadataToken.Zero;
      WriteMetadataToken (body.local_var_token);
    }

    void WriteInstructions ()
    {
      var instructions = body.Instructions;
      var items = instructions.items;
      var size = instructions.size;

      for (int i = 0; i < size; i++) {
        var instruction = items [i];
        WriteOpCode (instruction.opcode);
        WriteOperand (instruction);
      }
    }

    void WriteOpCode (OpCode opcode)
    {
      if (opcode.Size == 1) {
        WriteByte (opcode.Op2);
      } else {
        WriteByte (opcode.Op1);
        WriteByte (opcode.Op2);
      }
    }

    void WriteOperand (Instruction instruction)
    {
      var opcode = instruction.opcode;
      var operand_type = opcode.OperandType;
      if (operand_type == OperandType.InlineNone)
        return;

      var operand = instruction.operand;
      if (operand == null)
        throw new ArgumentException ();

      switch (operand_type) {
      case OperandType.InlineSwitch: {
        var targets = (Instruction []) operand;
        WriteInt32 (targets.Length);
        var diff = instruction.Offset + opcode.Size + (4 * (targets.Length + 1));
        for (int i = 0; i < targets.Length; i++)
          WriteInt32 (GetTargetOffset (targets [i]) - diff);
        break;
      }
      case OperandType.ShortInlineBrTarget: {
        var target = (Instruction) operand;
        WriteSByte ((sbyte) (GetTargetOffset (target) - (instruction.Offset + opcode.Size + 1)));
        break;
      }
      case OperandType.InlineBrTarget: {
        var target = (Instruction) operand;
        WriteInt32 (GetTargetOffset (target) - (instruction.Offset + opcode.Size + 4));
        break;
      }
      case OperandType.ShortInlineVar:
        WriteByte ((byte) GetVariableIndex ((VariableDefinition) operand));
        break;
      case OperandType.ShortInlineArg:
        WriteByte ((byte) GetParameterIndex ((ParameterDefinition) operand));
        break;
      case OperandType.InlineVar:
        WriteInt16 ((short) GetVariableIndex ((VariableDefinition) operand));
        break;
      case OperandType.InlineArg:
        WriteInt16 ((short) GetParameterIndex ((ParameterDefinition) operand));
        break;
      case OperandType.InlineSig:
        WriteMetadataToken (GetStandAloneSignature ((CallSite) operand));
        break;
      case OperandType.ShortInlineI:
        if (opcode == OpCodes.Ldc_I4_S)
          WriteSByte ((sbyte) operand);
        else
          WriteByte ((byte) operand);
        break;
      case OperandType.InlineI:
        WriteInt32 ((int) operand);
        break;
      case OperandType.InlineI8:
        WriteInt64 ((long) operand);
        break;
      case OperandType.ShortInlineR:
        WriteSingle ((float) operand);
        break;
      case OperandType.InlineR:
        WriteDouble ((double) operand);
        break;
      case OperandType.InlineString:
        WriteMetadataToken (
          new MetadataToken (
            TokenType.String,
            GetUserStringIndex ((string) operand)));
        break;
      case OperandType.InlineType:
      case OperandType.InlineField:
      case OperandType.InlineMethod:
      case OperandType.InlineTok:
        WriteMetadataToken (metadata.LookupToken ((IMetadataTokenProvider) operand));
        break;
      default:
        throw new ArgumentException ();
      }
    }

    int GetTargetOffset (Instruction instruction)
    {
      if (instruction == null) {
        var last = body.instructions [body.instructions.size - 1];
        return last.offset + last.GetSize ();
      }

      return instruction.offset;
    }

    uint GetUserStringIndex (string @string)
    {
      if (@string == null)
        return 0;

      return metadata.user_string_heap.GetStringIndex (@string);
    }

    static int GetVariableIndex (VariableDefinition variable)
    {
      return variable.Index;
    }

    int GetParameterIndex (ParameterDefinition parameter)
    {
      if (body.method.HasThis) {
        if (parameter == body.this_parameter)
          return 0;

        return parameter.Index + 1;
      }

      return parameter.Index;
    }

    bool RequiresFatHeader ()
    {
      var body = this.body;
      return body.CodeSize >= 64
        || body.InitLocals
        || body.HasVariables
        || body.HasExceptionHandlers
        || body.MaxStackSize > 8;
    }

    void ComputeHeader ()
    {
      int offset = 0;
      var instructions = body.instructions;
      var items = instructions.items;
      var count = instructions.size;
      var stack_size = 0;
      var max_stack = 0;
      Dictionary<Instruction, int> stack_sizes = null;

      if (body.HasExceptionHandlers)
        ComputeExceptionHandlerStackSize (ref stack_sizes);

      for (int i = 0; i < count; i++) {
        var instruction = items [i];
        instruction.offset = offset;
        offset += instruction.GetSize ();

        ComputeStackSize (instruction, ref stack_sizes, ref stack_size, ref max_stack);
      }

      body.code_size = offset;
      body.max_stack_size = max_stack;
    }

    void ComputeExceptionHandlerStackSize (ref Dictionary<Instruction, int> stack_sizes)
    {
      var exception_handlers = body.ExceptionHandlers;

      for (int i = 0; i < exception_handlers.Count; i++) {
        var exception_handler = exception_handlers [i];

        switch (exception_handler.HandlerType) {
        case ExceptionHandlerType.Catch:
          AddExceptionStackSize (exception_handler.HandlerStart, ref stack_sizes);
          break;
        case ExceptionHandlerType.Filter:
          AddExceptionStackSize (exception_handler.FilterStart, ref stack_sizes);
          AddExceptionStackSize (exception_handler.HandlerStart, ref stack_sizes);
          break;
        }
      }
    }

    static void AddExceptionStackSize (Instruction handler_start, ref Dictionary<Instruction, int> stack_sizes)
    {
      if (handler_start == null)
        return;

      if (stack_sizes == null)
        stack_sizes = new Dictionary<Instruction, int> ();

      stack_sizes [handler_start] = 1;
    }

    static void ComputeStackSize (Instruction instruction, ref Dictionary<Instruction, int> stack_sizes, ref int stack_size, ref int max_stack)
    {
      int computed_size;
      if (stack_sizes != null && stack_sizes.TryGetValue (instruction, out computed_size))
        stack_size = computed_size;

      max_stack = System.Math.Max (max_stack, stack_size);
      ComputeStackDelta (instruction, ref stack_size);
      max_stack = System.Math.Max (max_stack, stack_size);

      CopyBranchStackSize (instruction, ref stack_sizes, stack_size);
      ComputeStackSize (instruction, ref stack_size);
    }

    static void CopyBranchStackSize (Instruction instruction, ref Dictionary<Instruction, int> stack_sizes, int stack_size)
    {
      if (stack_size == 0)
        return;

      switch (instruction.opcode.OperandType) {
      case OperandType.ShortInlineBrTarget:
      case OperandType.InlineBrTarget:
        CopyBranchStackSize (ref stack_sizes, (Instruction) instruction.operand, stack_size);
        break;
      case OperandType.InlineSwitch:
        var targets = (Instruction[]) instruction.operand;
        for (int i = 0; i < targets.Length; i++)
          CopyBranchStackSize (ref stack_sizes, targets [i], stack_size);
        break;
      }
    }

    static void CopyBranchStackSize (ref Dictionary<Instruction, int> stack_sizes, Instruction target, int stack_size)
    {
      if (stack_sizes == null)
        stack_sizes = new Dictionary<Instruction, int> ();

      int branch_stack_size = stack_size;

      int computed_size;
      if (stack_sizes.TryGetValue (target, out computed_size))
        branch_stack_size = System.Math.Max (branch_stack_size, computed_size);

      stack_sizes [target] = branch_stack_size;
    }

    static void ComputeStackSize (Instruction instruction, ref int stack_size)
    {
      switch (instruction.opcode.FlowControl) {
      case FlowControl.Branch:
      case FlowControl.Break:
      case FlowControl.Throw:
      case FlowControl.Return:
        stack_size = 0;
        break;
      }
    }

    static void ComputeStackDelta (Instruction instruction, ref int stack_size)
    {
      switch (instruction.opcode.FlowControl) {
      case FlowControl.Call: {
        var method = (IMethodSignature) instruction.operand;
        stack_size -= (method.HasParameters ? method.Parameters.Count : 0)
          + (method.HasThis && instruction.opcode.Code != Code.Newobj ? 1 : 0);
        stack_size += (method.ReturnType.etype == ElementType.Void ? 0 : 1)
          + (method.HasThis && instruction.opcode.Code == Code.Newobj ? 1 : 0);
        break;
      }
      default:
        ComputePopDelta (instruction.opcode.StackBehaviourPop, ref stack_size);
        ComputePushDelta (instruction.opcode.StackBehaviourPush, ref stack_size);
        break;
      }
    }

    static void ComputePopDelta (StackBehaviour pop_behavior, ref int stack_size)
    {
      switch (pop_behavior) {
      case StackBehaviour.Popi:
      case StackBehaviour.Popref:
      case StackBehaviour.Pop1:
        stack_size--;
        break;
      case StackBehaviour.Pop1_pop1:
      case StackBehaviour.Popi_pop1:
      case StackBehaviour.Popi_popi:
      case StackBehaviour.Popi_popi8:
      case StackBehaviour.Popi_popr4:
      case StackBehaviour.Popi_popr8:
      case StackBehaviour.Popref_pop1:
      case StackBehaviour.Popref_popi:
        stack_size -= 2;
        break;
      case StackBehaviour.Popi_popi_popi:
      case StackBehaviour.Popref_popi_popi:
      case StackBehaviour.Popref_popi_popi8:
      case StackBehaviour.Popref_popi_popr4:
      case StackBehaviour.Popref_popi_popr8:
      case StackBehaviour.Popref_popi_popref:
        stack_size -= 3;
        break;
      case StackBehaviour.PopAll:
        stack_size = 0;
        break;
      }
    }

    static void ComputePushDelta (StackBehaviour push_behaviour, ref int stack_size)
    {
      switch (push_behaviour) {
      case StackBehaviour.Push1:
      case StackBehaviour.Pushi:
      case StackBehaviour.Pushi8:
      case StackBehaviour.Pushr4:
      case StackBehaviour.Pushr8:
      case StackBehaviour.Pushref:
        stack_size++;
        break;
      case StackBehaviour.Push1_push1:
        stack_size += 2;
        break;
      }
    }

    void WriteExceptionHandlers ()
    {
      Align (4);

      var handlers = body.ExceptionHandlers;

      if (handlers.Count < 0x15 && !RequiresFatSection (handlers))
        WriteSmallSection (handlers);
      else
        WriteFatSection (handlers);
    }

    static bool RequiresFatSection (Collection<ExceptionHandler> handlers)
    {
      for (int i = 0; i < handlers.Count; i++) {
        var handler = handlers [i];

        if (IsFatRange (handler.TryStart, handler.TryEnd))
          return true;

        if (IsFatRange (handler.HandlerStart, handler.HandlerEnd))
          return true;

        if (handler.HandlerType == ExceptionHandlerType.Filter
          && IsFatRange (handler.FilterStart, handler.HandlerStart))
          return true;
      }

      return false;
    }

    static bool IsFatRange (Instruction start, Instruction end)
    {
      if (end == null)
        return true;

      return end.Offset - start.Offset > 255 || start.Offset > 65535;
    }

    void WriteSmallSection (Collection<ExceptionHandler> handlers)
    {
      const byte eh_table = 0x1;

      WriteByte (eh_table);
      WriteByte ((byte) (handlers.Count * 12 + 4));
      WriteBytes (2);

      WriteExceptionHandlers (
        handlers,
        i => WriteUInt16 ((ushort) i),
        i => WriteByte ((byte) i));
    }

    void WriteFatSection (Collection<ExceptionHandler> handlers)
    {
      const byte eh_table = 0x1;
      const byte fat_format = 0x40;

      WriteByte (eh_table | fat_format);

      int size = handlers.Count * 24 + 4;
      WriteByte ((byte) (size & 0xff));
      WriteByte ((byte) ((size >> 8) & 0xff));
      WriteByte ((byte) ((size >> 16) & 0xff));

      WriteExceptionHandlers (handlers, WriteInt32, WriteInt32);
    }

    void WriteExceptionHandlers (Collection<ExceptionHandler> handlers, Action<int> write_entry, Action<int> write_length)
    {
      for (int i = 0; i < handlers.Count; i++) {
        var handler = handlers [i];

        write_entry ((int) handler.HandlerType);

        write_entry (handler.TryStart.Offset);
        write_length (GetTargetOffset (handler.TryEnd) - handler.TryStart.Offset);

        write_entry (handler.HandlerStart.Offset);
        write_length (GetTargetOffset (handler.HandlerEnd) - handler.HandlerStart.Offset);

        WriteExceptionHandlerSpecific (handler);
      }
    }

    void WriteExceptionHandlerSpecific (ExceptionHandler handler)
    {
      switch (handler.HandlerType) {
      case ExceptionHandlerType.Catch:
        WriteMetadataToken (metadata.LookupToken (handler.CatchType));
        break;
      case ExceptionHandlerType.Filter:
        WriteInt32 (handler.FilterStart.Offset);
        break;
      default:
        WriteInt32 (0);
        break;
      }
    }

    public MetadataToken GetStandAloneSignature (Collection<VariableDefinition> variables)
    {
      var signature = metadata.GetLocalVariableBlobIndex (variables);

      return GetStandAloneSignatureToken (signature);
    }

    public MetadataToken GetStandAloneSignature (CallSite call_site)
    {
      var signature = metadata.GetCallSiteBlobIndex (call_site);
      var token = GetStandAloneSignatureToken (signature);
      call_site.MetadataToken = token;
      return token;
    }

    MetadataToken GetStandAloneSignatureToken (uint signature)
    {
      MetadataToken token;
      if (standalone_signatures.TryGetValue (signature, out token))
        return token;

      token = new MetadataToken (TokenType.Signature, metadata.AddStandAloneSignature (signature));
      standalone_signatures.Add (signature, token);
      return token;
    }

    RVA BeginMethod ()
    {
      return current;
    }

    void WriteMetadataToken (MetadataToken token)
    {
      WriteUInt32 (token.ToUInt32 ());
    }

    void Align (int align)
    {
      align--;
      WriteBytes (((position + align) & ~align) - position);
    }

    void EndMethod ()
    {
      current = (RVA) (code_base + position);
    }
  }
}

#endif