/// <summary>
/// Reads a single CIL instruction from a given data stream.
/// </summary>
/// <param name="stream">The source data stream.</param>
/// <param name="instruction">The instruction that was read, undefined if the method returns zero.</param>
/// <returns>A value indicating if an instruction was read, <c>false</c> if the end of the stream was reached.</returns>
public static bool ReadInstruction(Stream stream, out RawInstruction instruction)
{
Contract.Requires(stream != null && stream.CanRead);
int firstOpcodeByte = stream.ReadByte();
if (unchecked ((byte)firstOpcodeByte) != firstOpcodeByte)
{
instruction = default(RawInstruction);
return(false);
}
OpcodeValue opcodeValue;
if (OpcodeValueEnum.IsFirstOfTwoBytes((byte)firstOpcodeByte))
{
opcodeValue = (OpcodeValue)((firstOpcodeByte << 8) | stream.ReadUInt8());
}
else
{
opcodeValue = (OpcodeValue)firstOpcodeByte;
}
var opcode = Opcode.FromValue(opcodeValue);
if (opcode == Opcode.Switch)
{
// Read jump table
int[] jumpTable = new int[stream.ReadUInt32()];
for (int i = 0; i < jumpTable.Length; ++i)
{
jumpTable[i] = stream.ReadInt32();
}
instruction = RawInstruction.CreateSwitch(jumpTable);
}
else
{
NumericalOperand operand;
switch ((int)opcode.OperandKind.GetSizeInBytes())
{
case 0: operand = default(NumericalOperand); break;
case 1: operand = stream.ReadInt8(); break;
case 2: operand = stream.ReadInt16(); break;
case 4: operand = stream.ReadInt32(); break;
case 8: operand = stream.ReadInt64(); break;
default: throw new NotSupportedException("Unexpected opcode operand size");
}
instruction = new RawInstruction(opcode, operand);
}
return(true);
}
private void EmitCall(ImmutableArray <Variable> targets, FunctionMethod function, ImmutableArray <Variable> arguments)
{
var signature = function.Signature;
Contract.Assert(arguments.Length == signature.Inputs.Count);
Contract.Assert(targets.Length <= signature.Outputs.Count);
// Prepare the eventual return value store
if (signature.HasReturnValue && targets.Length == 1)
{
BeginEmitStore(targets[0]);
}
// Push the input arguments
for (int i = 0; i < arguments.Length; ++i)
{
var argument = arguments[i];
EmitLoad(argument);
EmitConvert(argument.StaticRepr, signature.Inputs[i]);
}
if (signature.OutParameterCount > 0)
{
// Push the pointers to the output arguments
for (int i = 0; i < signature.Outputs.Count; ++i)
{
if (i < targets.Length)
{
var target = targets[i];
var location = GetLocation(target);
if (declaration.Outputs.Contains(target) && declaration.Outputs.Length >= 2)
{
cil.Load(location); // Target is a ByRef parameter, so already a (managed) pointer
}
else
{
cil.LoadAddress(location);
}
}
else
{
throw new NotImplementedException("Ignored outputs of a multi-output function.");
}
}
}
// Call the function
var method = function.Method;
if (method is System.Reflection.Emit.MethodBuilder)
{
// We have to supply the parameter types ourselves since MethodBodyWriter
// can't call MethodBuilder.GetParameters() without receiving an exception.
cil.Call(Opcode.GetDefaultCall(method), method,
function.Signature.GetParameterCliTypes(), function.Signature.ReturnCliType);
}
else
{
// We're calling a builtin
var builtinCilOpcodeAttribute = method.GetCustomAttribute <BuiltinCilOpcodeAttribute>();
if (builtinCilOpcodeAttribute == null)
{
cil.Invoke(method);
}
else
{
// Calling the builtin is equivalent to emitting a sequence of CIL opcodes, so do that instead
foreach (var opcodeValue in builtinCilOpcodeAttribute.Opcodes)
{
var opcode = Opcode.FromValue((OpcodeValue)opcodeValue);
Contract.Assert(opcode != null);
cil.Instruction(opcode);
}
}
}
// Handle the return value, if any
if (signature.HasReturnValue)
{
if (targets.Length == 1)
{
EmitConvert(signature.Outputs[0], targets[0].StaticRepr);
EndEmitStore(targets[0]);
}
else
{
// Return value ignored.
Contract.Assert(targets.Length == 0);
cil.Pop();
}
}
}
