[Mono-dev] Edit and Continue / Function body rewrite

[David Srbecky]

Brian Crowell wrote:
> David Srbecky wrote:
>> The idea is that I will emit disk assembly using 
>> System.Reflection.Emit as usually, but later on I will re-emit body of 
>> some function and fetch changed data into memory. Once I got the data 
>> I can feed it to the .NET runtime - that should not be a problem.
> 
> Er, I don't know the full internals of the Mono runtime, but I suspect 
> this is not that easy to do. Correct me if I'm wrong, but I think one of 
> the main reasons assemblies cannot be unloaded is that it allows you to 
> make some very nice assumptions about the immutability of code-- for 
> example, that function pointers will not change. It may require patching 
> previously JITted code to reference a new function.
> 
> Of course, I'd be happy to be wrong about this. Obviously, since 
> Microsoft did it, there must be a way.
> 
> --Brian

Yes, you are right - changing running program is probably extremely 
difficult, but I want to use Microsoft runtime which has this 
functionality already implemented and available via really simple API. 
So this is not a problem.

The problem is that I need to get the new IL code and metadata for the 
new function from System.Reflection.Emit.

My question is how difficult is it to patch System.Reflection.Emit to 
support this.

David