internal static bool IsClosure(ILTransformContext context, ILVariable variable, out ITypeDefinition closureType, out ILInstruction initializer)
{
closureType = null;
initializer = null;
if (variable.IsSingleDefinition && variable.StoreInstructions.SingleOrDefault() is StLoc inst) {
initializer = inst;
if (IsClosureInit(context, inst, out closureType)) {
return true;
}
}
closureType = variable.Type.GetDefinition();
if (context.Settings.LocalFunctions && closureType?.Kind == TypeKind.Struct && variable.HasInitialValue && IsPotentialClosure(context, closureType)) {
initializer = LocalFunctionDecompiler.GetStatement(variable.AddressInstructions.OrderBy(i => i.StartILOffset).First());
return true;
}
return false;
}
/// <summary>
/// catch E_189 : 0200007C System.Exception when (BlockContainer {
/// Block IL_0079 (incoming: 1) {
/// stloc S_30(ldloc E_189)
/// br IL_0085
/// }
///
/// Block IL_0085 (incoming: 1) {
/// stloc I_1(ldloc S_30)
/// where S_30 and I_1 are single definition
/// =>
/// copy-propagate E_189 to replace all uses of S_30 and I_1
/// </summary>
static void PropagateExceptionVariable(ILTransformContext context, TryCatchHandler handler)
{
var exceptionVariable = handler.Variable;
if (!exceptionVariable.IsSingleDefinition)
{
return;
}
context.StepStartGroup(nameof(PropagateExceptionVariable));
int i = 0;
while (i < exceptionVariable.LoadInstructions.Count)
{
var load = exceptionVariable.LoadInstructions[i];
if (!load.IsDescendantOf(handler))
{
i++;
continue;
}
// We are only interested in store "statements" copying the exception variable
// without modifying it.
var statement = LocalFunctionDecompiler.GetStatement(load);
if (!(statement is StLoc stloc))
{
i++;
continue;
}
// simple copy case:
// stloc b(ldloc a)
if (stloc.Value == load)
{
PropagateExceptionInstance(stloc);
}
// if the type of the cast-class instruction matches the exceptionType,
// this cast can be removed without losing any side-effects.
// Note: this would also hold true iff exceptionType were an exception derived
// from cc.Type, however, we are more restrictive to match the pattern exactly.
// stloc b(castclass exceptionType(ldloc a))
else if (stloc.Value is CastClass cc && cc.Type.Equals(exceptionVariable.Type) && cc.Argument == load)
{
stloc.Value = load;
PropagateExceptionInstance(stloc);
}