Added non-standard API to disable the "helpful" automatic leave/endfinally instructions.

refemit/ILGenerator.cs

@@ -91,6 +91,7 @@ namespace IKVM.Reflection.Emit
 		private ushort maxStack;
 		private int stackHeight;
 		private Scope scope;
+		private bool exceptionBlockAssistance = true;
 
 		private struct LabelFixup
 		{
@@ -171,10 +172,19 @@ namespace IKVM.Reflection.Emit
 			}
 		}
 
+		// non-standard API
+		public void __DisableExceptionBlockAssistance()
+		{
+			exceptionBlockAssistance = false;
+		}
+
 		public void BeginCatchBlock(Type exceptionType)
 		{
 			ExceptionBlock block = exceptionStack.Peek();
+			if (exceptionBlockAssistance)
+			{
 				Emit(OpCodes.Leave, block.labelEnd);
+			}
 			stackHeight = 0;
 			UpdateStack(1);
 			if (block.tryLength == 0)
@@ -221,7 +231,10 @@ namespace IKVM.Reflection.Emit
 		public void BeginFinallyBlock()
 		{
 			ExceptionBlock block = exceptionStack.Peek();
+			if (exceptionBlockAssistance)
+			{
 				Emit(OpCodes.Leave, block.labelEnd);
+			}
 			stackHeight = 0;
 			if (block.handlerOffset == 0)
 			{
@@ -230,9 +243,13 @@ namespace IKVM.Reflection.Emit
 			else
 			{
 				block.handlerLength = code.Position - block.handlerOffset;
+				Label labelEnd = new Label();
+				if (exceptionBlockAssistance)
+				{
 					MarkLabel(block.labelEnd);
-				Label labelEnd = DefineLabel();
+					labelEnd = DefineLabel();
 					Emit(OpCodes.Leave, labelEnd);
+				}
 				exceptionStack.Pop();
 				ExceptionBlock newBlock = new ExceptionBlock(exceptions.Count);
 				newBlock.labelEnd = labelEnd;
@@ -248,6 +265,8 @@ namespace IKVM.Reflection.Emit
 		public void EndExceptionBlock()
 		{
 			ExceptionBlock block = exceptionStack.Pop();
+			if (exceptionBlockAssistance)
+			{
 				if (block.exceptionType != null && block.exceptionType != FAULT)
 				{
 					Emit(OpCodes.Leave, block.labelEnd);
@@ -256,9 +275,10 @@ namespace IKVM.Reflection.Emit
 				{
 					Emit(OpCodes.Endfinally);
 				}
-			block.handlerLength = code.Position - block.handlerOffset;
 				MarkLabel(block.labelEnd);
 			}
+			block.handlerLength = code.Position - block.handlerOffset;
+		}
 
 		public void BeginScope()
 		{