[MONO] Refactored code into marshal-ilgen and marshal-shared.

[naricc]

This PR refactors the marshaling code into ilgen and shared parts. This is one step in a change that will let move the legacy marshaling code into to a component; marshal-shared has the parts that will be shared by both legacy and ilgen. The next step is to factor out the legacy marshaling code, and then move it into a component.

Once componentization is complete, the runtime size will be reduced by approximately 100 KB (on x64) when the legacy component is not needed.

contributes to: #61685

[naricc]

@lambdageek I believe this is ready for review.

[vargaz]

In general, marshal-shared.c still contains a lot of code, are you sure those are all going to be needed with the new style of marshaling ?

[naricc]

@vargaz

In general, marshal-shared.c still contains a lot of code, are you sure those are all going to be needed with the new style of marshaling ?

This seems to be the most I can do statically. All of these functions are referenced by something that needs to stay in the runtime. But it is possible that some of them cannot actually be called at runtime in the new mode, or that the functions could be broken into pieces and parts of them put into the legacy component.

Basically what I found that could be moved into legacy is these functions:

runtime/src/mono/mono/metadata/marshal-ilgen.c

Lines 6962 to 6971 in 0a2bc2f

	cb.emit_marshal_boolean = emit_marshal_boolean_ilgen;
	cb.emit_marshal_char = emit_marshal_char_ilgen;
	cb.emit_marshal_custom = emit_marshal_custom_ilgen;
	cb.emit_marshal_asany = emit_marshal_asany_ilgen;
	cb.emit_marshal_vtype = emit_marshal_vtype_ilgen;
	cb.emit_marshal_string = emit_marshal_string_ilgen;
	cb.emit_marshal_safehandle = emit_marshal_safehandle_ilgen;
	cb.emit_marshal_handleref = emit_marshal_handleref_ilgen;
	cb.emit_marshal_object = emit_marshal_object_ilgen;
	cb.emit_marshal_variant = emit_marshal_variant_ilgen;

, plus emit_marshal_ptr_ilgen, emit_marshal_array_ilgen, and static methods only reachable from those.

This represents a clear size savings and is easy to implement. We plan to look at ways to squeeze even more out later, but its somewhat more complicated and I don't know how much it will save.

[lambdageek]

Looking good, just need to address Zoltan's suggestions

[naricc]

@lambdageek @vargaz I've addressed all the suggestions/issues.

[lambdageek]

i'm surprised this needs to be shared.

in the lightweight marshaler this should never get called (again because conv should never be anything other than NONE)

[naricc]

I think, taking that into account I can probably remove it. But can I actually make that change in this PR? It seems like I need to seperate out the lightweight and ilgen first.

[lambdageek]

I think this will probably have to wait until we have the lightweight marshaling code separated out. right now I think conv_to_icall is getting called from both marshal-ilgen and marshal-shared, so it would be difficult to just have a single copy. after the split, it will hopefully be easier to refactor the code so that -ilgen and -lightweight each get their own copy and the -ligthweight one is trivial.

[lambdageek]

i'm a little surprised that any code that deals with marshaling conversions or anything like that needs to be shared. it seems like that stuff is only for the legacy marshaler not the lightweight marshaler.

[lambdageek]

I think once we have the lightweight marshaler separated out, we can delete a lot of code by un-sharing some of this stuff and implementing the lightweight marshaling versions as g_assert_not_reached() or no-ops or single simple cases.