/// <summary>
/// Determines wheter the specified block is part of the state machine controller.
/// </summary>
/// <remarks>
/// We look for this pattern:
/// ...
/// ldloc.* stateVariable
/// ldc.i4.* stateNumber
/// beq* stateEntry
///
/// or
///
/// ....
/// ldloc.* stateVariable
/// (ldc.i4.* stateNumber) - can be missing
/// (sub) - can be missing
/// switch ....
///
/// or
///
/// ldloc.* stateVariable
/// ldc.i4.* stateNumber
/// bnq* default
/// stateEntry:
/// .........
///
/// or
///
/// ldfld stateField
/// ldc.i4.* stateNumber
/// ceq
/// ldc.i4.0
/// .....
/// brtrue* default
/// stateEntry:
/// ............
///
/// In some cases there is no state variable. Instead the state field is loaded.
///
/// Update:
/// Since C#6.0 this case is added:
///
/// ...
/// ldloc.1
/// brfalse.s IL_0012
/// ...
/// </remarks>
/// <param name="theBlock"></param>
/// <param name="stateNumber"></param>
/// <returns>False if the specified block is not part of the state machine controler, true - otherwise.</returns>
private bool IsStateMachineControllerBlock(ref InstructionBlock theBlock, out StateMachineControllerType controllerType, out int stateNumber)
{
theBlock = SkipBranchChain(theBlock);
Instruction currentInstruction = theBlock.Last;
if (theCFG.SwitchBlocksInformation.ContainsKey(theBlock))
{
controllerType = StateMachineControllerType.Switch;
if (currentInstruction.Previous.OpCode.Code == Code.Sub || currentInstruction.Previous.OpCode.Code == Code.Sub_Ovf)
{
currentInstruction = currentInstruction.Previous.Previous;
if (!StateMachineUtilities.TryGetOperandOfLdc(currentInstruction, out stateNumber))
{
return false;
}
}
else
{
stateNumber = 0;
}
}
else if (IsBeqInstruction(theBlock.Last)) //controllerType == StateMachineControllerType.Conditions
{
controllerType = StateMachineControllerType.Condition;
currentInstruction = theBlock.Last.Previous;
if (!StateMachineUtilities.TryGetOperandOfLdc(currentInstruction, out stateNumber))
{
return false;
}
}
else if (IsBrFalseInstruction(theBlock.Last))
{
controllerType = StateMachineControllerType.Condition;
currentInstruction = theBlock.Last;
stateNumber = 0;
}
else if (IsBneInstruction(theBlock.Last))
{
controllerType = StateMachineControllerType.NegativeCondition;
currentInstruction = theBlock.Last.Previous;
if (!StateMachineUtilities.TryGetOperandOfLdc(currentInstruction, out stateNumber))
{
return false;
}
}
else if (IsDebugControllerBlock(theBlock, out stateNumber))
{
controllerType = StateMachineControllerType.NegativeCondition;
return true;
}
else
{
controllerType = StateMachineControllerType.None;
stateNumber = 0;
return false;
}
VariableReference varReference;
if (ContainsStateFieldLoad(theBlock) ||
TryGetVariableFromInstruction(currentInstruction.Previous, out varReference) && varReference == stateVariable &&
!ContainsStateVariableSet(theBlock))
//In rare cases the state variable is used in a regular switch block. That's why we check whether there is an assignment of the variable
//in theBlock. If so then the block is not a controller block.
{
return true;
}
stateNumber = 0;
return false;
}
/// <summary>
/// Determines wheter the specified block is part of the state machine controller.
/// </summary>
/// <remarks>
/// We look for this pattern:
/// ...
/// ldloc.* stateVariable
/// ldc.i4.* stateNumber
/// beq* stateEntry
///
/// or
///
/// ....
/// ldloc.* stateVariable
/// (ldc.i4.* stateNumber) - can be missing
/// (sub) - can be missing
/// switch ....
///
/// or
///
/// ldloc.* stateVariable
/// ldc.i4.* stateNumber
/// bnq* default
/// stateEntry:
/// .........
///
/// or
///
/// ldfld stateField
/// ldc.i4.* stateNumber
/// ceq
/// ldc.i4.0
/// .....
/// brtrue* default
/// stateEntry:
/// ............
///
/// In some cases there is no state variable. Instead the state field is loaded.
/// </remarks>
/// <param name="theBlock"></param>
/// <param name="stateNumber"></param>
/// <returns>False if the specified block is not part of the state machine controler, true - otherwise.</returns>
private bool IsStateMachineControllerBlock(ref InstructionBlock theBlock, out StateMachineControllerType controllerType, out int stateNumber)
{
theBlock = SkipBranchChain(theBlock);
Instruction currentInstruction = theBlock.Last;
if (theCFG.SwitchBlocksInformation.ContainsKey(theBlock))
{
controllerType = StateMachineControllerType.Switch;
if (currentInstruction.Previous.OpCode.Code == Code.Sub || currentInstruction.Previous.OpCode.Code == Code.Sub_Ovf)
{
currentInstruction = currentInstruction.Previous.Previous;
if (!StateMachineUtilities.TryGetOperandOfLdc(currentInstruction, out stateNumber))
{
return(false);
}
}
else
{
stateNumber = 0;
}
}
else if (IsBeqInstruction(theBlock.Last)) //controllerType == StateMachineControllerType.Conditions
{
controllerType = StateMachineControllerType.Condition;
currentInstruction = theBlock.Last.Previous;
if (!StateMachineUtilities.TryGetOperandOfLdc(currentInstruction, out stateNumber))
{
return(false);
}
}
else if (IsBneInstruction(theBlock.Last))
{
controllerType = StateMachineControllerType.NegativeCondition;
currentInstruction = theBlock.Last.Previous;
if (!StateMachineUtilities.TryGetOperandOfLdc(currentInstruction, out stateNumber))
{
return(false);
}
}
else if (IsDebugControllerBlock(theBlock, out stateNumber))
{
controllerType = StateMachineControllerType.NegativeCondition;
return(true);
}
else
{
controllerType = StateMachineControllerType.None;
stateNumber = 0;
return(false);
}
VariableReference varReference;
if (ContainsStateFieldLoad(theBlock) ||
TryGetVariableFromInstruction(currentInstruction.Previous, out varReference) && varReference == stateVariable &&
!ContainsStateVariableSet(theBlock))
//In rare cases the state variable is used in a regular switch block. That's why we check whether there is an assignment of the variable
//in theBlock. If so then the block is not a controller block.
{
return(true);
}
stateNumber = 0;
return(false);
}
