Add internal intrinsics for instance-based calli

[steveharter]

Contributes to #112994. The next step in this process will use these intrinsics.

Adds support for both CoreClr JIT and R2R to modify the function pointer signature to add HasThis | ExplicitThis so specific function pointer signatures can be called on an instance method.

Local testing verified both:

• R2R\crossgen2 created the native code with the HasThis | ExplicitThis signature and thus prevented JIT.
• The non-R2R runtime cases replaced the IL of the method and added HasThis | ExplicitThis to the signature.

The tests added here currently don't verify the intrinsics, but an earlier version did (see the first commit). Once the next step of hooking into reflection is done, these tests will cover the new intrinsics added here. In particular, the new tests address missing test cases of calling an instance-based method with non-primitive return types such as Guid, DateTime and TimeSpan that would fail if reflection called these methods with function pointers \ Calli without HasThis | ExplicitThis.

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[Copilot]

Copilot reviewed 12 out of 14 changed files in this pull request and generated 3 comments.

Files not reviewed (2)

• src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj: Language not supported
• src/coreclr/tools/aot/ILCompiler.ReadyToRun/ILCompiler.ReadyToRun.csproj: Language not supported

[MichalPetryka]

Wouldn't it be simpler to just write those stubs in IL instead of having to implement them in every VM?
Like this.

[jkotas]

Wouldn't it be simpler to just write those stubs in IL instead of having to implement them in every VM?

We would need to invent build infrastructure to merge this IL into CoreLib....

[jkotas]

LGMT otherwise. Thank you!

[jkotas]

Thanks!

[AaronRobinsonMSFT]

Thanks!

[steveharter]

/ba-g infra timeout on building Libraries Test Run release coreclr linux_musl x64 Debug