private void CreateExceptionHandlers(CilCompilationUnit unit, CilInstructionCollection result)
{
foreach (var subGraph in unit.ControlFlowGraph.SubGraphs)
{
var ehFrame = (EHFrame)subGraph.UserData[EHFrame.EHFrameProperty];
ExceptionHandlerType type;
switch (ehFrame.Type)
{
case EHType.CATCH:
type = ExceptionHandlerType.Exception;
break;
case EHType.FILTER:
type = ExceptionHandlerType.Filter;
break;
case EHType.FAULT:
type = ExceptionHandlerType.Fault;
break;
case EHType.FINALLY:
type = ExceptionHandlerType.Finally;
break;
default:
throw new ArgumentOutOfRangeException();
}
// Find first and last nodes of try block.
var tryBody = (ICollection <Node>)subGraph.UserData[ControlFlowGraph.TryBlockProperty];
var(tryStartNode, tryEndNode) = FindMinMaxNodes(tryBody);
// Find first and last nodes of handler block.
var handlerBody = (ICollection <Node>)subGraph.UserData[ControlFlowGraph.HandlerBlockProperty];
var(handlerStartNode, handlerEndNode) = FindMinMaxNodes(handlerBody);
// Create handler.
var handler = new ExceptionHandler(type)
{
TryStart = _blockEntries[tryStartNode],
TryEnd = result.GetByOffset(_blockExits[tryEndNode].Offset + _blockExits[tryEndNode].Size)
?? throw new CilCodeGeneratorException(
$"Could not infer end of try block in {_context.MethodBody.Method.Name}."),
HandlerStart = _blockEntries[handlerStartNode],
HandlerEnd = result.GetByOffset(_blockExits[handlerEndNode].Offset + _blockExits[handlerEndNode].Size)
?? throw new CilCodeGeneratorException(
$"Could not infer end of handler block in {_context.MethodBody.Method.Name}."),
CatchType = ehFrame.CatchType
};
_context.ExceptionHandlers.Add(ehFrame, handler);
}
}
private ICilLabel GetHandlerEndLabel(CilInstructionCollection result, Node endNode, string type)
{
var instruction = result.GetByOffset(_blockExits[endNode].Offset + _blockExits[endNode].Size);
if (instruction is null)
{
throw new CilCodeGeneratorException(
$"Could not infer end of {type} block in {_context.MethodBody.Owner.Name}.");
}
return(new CilInstructionLabel(instruction));
}