[cdac] Basic ISOSDacInterface::GetMethodDescData

[lambdageek]

Currently only works on non-generic non-R2R methods (and probably only ones that are still Tier0)

TODO:

• Separate the contracts: Precode, Code Versions, ReJIT and ExecutionManager are separate ideas
• Contract markdown
• Extract a LoaderAllocator contract
• Use the cached LoaderModule members from MethodDescChunk and FnPtrTypeDesc
• Unit tests
• Backport the data descriptor and precode descriptor changes to .net 9 [feature/9.0-cdac-backports] Data descriptor changes for GetMethodDescName #106463

contributes to #99302

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[davidwrighton]

I think we'll want to have a LoaderAllocator contract. There is a bunch of ... stuff... on there, and I feel like we'll likely need something there.

[elinor-fung]

For this particular API (checking if the module is collectible), it seems like it should cut out the LoaderAllocator concept? Since once you're at the Module (instead of a MethodDesc), the module's IsCollectible should match the module's loader allocator's IsCollectible.

[davidwrighton]

We're going to need the ability to walk the list of IL versions, and Native code versions, and query various details about these things. This doesn't feel like the right api. Could you get it onto the CodeVersions contract?

[lambdageek]

This just extracts the address from the MethodDescCodeData. All the logic for working with the versioning state is in CodeVersions.

It's not that different from

  TargetPointer modAddr =  RuntimeTypeSystem.GetModule(TypeHandle th);
  ModuleHandle mod = Loader.GetModuleHandle(modAddr);

RTS gives you a pointer and Loader turns it into a handle that you can use for queries. Similarly RTS will give a pointer to the versioning state and CodeVersions will consume it in some manner.

Currently the versioning state is consumed entirely internally in the CodeVersions contract, but in the future it could be exposed via a handle or through some data API (see GetSpecificNativeCodeVersion and IsActiveNativeCodeVersion implementations)

[elinor-fung]

For this particular API (checking if the module is collectible), it seems like it should cut out the LoaderAllocator concept? Since once you're at the Module (instead of a MethodDesc), the module's IsCollectible should match the module's loader allocator's IsCollectible.