Add an option to remove exception filters.

[vargaz]

Its controlled by the --remove-filters command line option.

This works by rewriting:

catch (Exception ex) when (<cond>) {
  ..
}

into:

catch (Exception ex) {
  if (!<cond>)
    throw ex;
  ..
}

[MichalStrehovsky]

This test might be useful in this effort:

using System;

class P
{
    interface Q
    {
        static int s_counter;

        static void Main()
        {
            try
            {
                throw new Exception();
            }
            catch (ArgumentException) when (True())
            {
                Console.WriteLine("Unreached");
            }
            catch (Exception) when (Throw())
            {
                Console.WriteLine("Unreached");
                s_counter = -1;
            }
            catch (Exception) when (False())
            {
                Console.WriteLine("Unreached");
                s_counter = -1;
            }
            catch (Exception)
            {
                Console.WriteLine("Works as expected");
                s_counter |= 4;
            }

            if (s_counter == 7)
            {
                Console.WriteLine("Success");
            }
            else
            {
                Console.WriteLine("Fail");
            }
        }

        static bool Throw()
        {
            s_counter |= 1;
            throw new Exception();
        }

        static bool False()
        {
            s_counter |= 2;
            return false;
        }

        static bool True()
        {
            s_counter = -1;
            return true;
        }
    }
}

[marek-safar]

This needs to check if we are linking assembly otherwise do something else (e.g. issue warning).

[marek-safar]

I suspect that we'll need to run this code during the inner dev loop with an interpreter for consistency where hooking up linker would be a pain.

I'm wondering if we should take this as an opportunity to introduce a new task inside dotnet/runtime instead of injecting this functionality into linker. We have other similar needs for AOT pipeline which could be developed there instead of inside linker. It'd also allow us to run these steps heavily in parallel if we go with SRM instead of Cecil.

We would have run all of the following "steps" at the same time inside that task

• exception filters rewriter
• IL bodies remover
• pinvoke generator
• icalls generator

/cc @lewing

[vargaz]

This currently can't handle the case when there are more than 1 filter clause for the same try range.

Closing for now in favor of: mono/mono#20796