private void SplitSinglePointOfReturn()
{
if (!_context.IsDebugBuild)
{
return;
}
var lastRetInstruction = Instructions.LastOrDefault();
if (lastRetInstruction?.OpCode != OpCodes.Ret)
{
return;
}
var ldlocInstruction = lastRetInstruction.Previous;
if (ldlocInstruction?.OpCode != OpCodes.Ldloc)
{
return;
}
var refsToLdloc = Instructions.Where(i => i.Operand == ldlocInstruction).ToList();
var leaveOriginalReturnPoint = false;
var insertedRet = 0;
foreach (var brInstruction in refsToLdloc)
{
var stlocInstruction = brInstruction.Previous;
if (brInstruction.OpCode == OpCodes.Br &&
stlocInstruction != null &&
stlocInstruction.OpCode == OpCodes.Stloc &&
stlocInstruction.Operand == ldlocInstruction.Operand)
{
_il.Remove(stlocInstruction);
_il.Replace(brInstruction, Instruction.Create(OpCodes.Ret));
++insertedRet;
}
else
{
leaveOriginalReturnPoint = true;
}
}
if (!leaveOriginalReturnPoint)
{
// If the compiler ever stops emitting no-op branch instructions
var stlocInstruction = ldlocInstruction.PrevSkipNops();
if (stlocInstruction != null && stlocInstruction.OpCode == OpCodes.Stloc && stlocInstruction.Operand == ldlocInstruction.Operand)
{
_il.Remove(stlocInstruction);
}
_il.RemoveNopsAround(ldlocInstruction);
_il.Remove(ldlocInstruction);
if (lastRetInstruction.Previous?.OpCode == OpCodes.Ret)
{
_il.Remove(lastRetInstruction);
}
}
if (insertedRet > 0)
{
_log.Debug($"Split single point of return: {insertedRet} ret inserted, original {(leaveOriginalReturnPoint ? "left" : "removed")}");
}
}
public string ConsumeArgString(Instruction instruction)
{
switch (instruction.OpCode.Code)
{
case Code.Ldstr:
_il.Remove(instruction);
return((string)instruction.Operand);
case Code.Ldnull:
throw new InstructionWeavingException(instruction, "A non-null string literal is expected");
default:
throw UnexpectedInstruction(instruction, "a string literal");
}
}