Add MemoryMarshal.GetArrayDataReference(Array)

[GrabYourPitchforks]

Resolves #35528.

This PR has a few distinct components:

• Introduce the overload Array.GetArrayDataReference(Array array). I opted to name the parameter array instead of arr for local consistency with the existing overload.
• Remove the existing GetRawSzArrayData and GetRawArrayData internal methods and migrate their callers to the new public APIs.
• In coreclr, define the metasigs for both overloads so that we can intrinsicify the new API in the future without creating ambiguity within the existing jitinterface.cpp helpers.
• In mono, intrinsicify and add interp support for both overloads. (Unlike coreclr, mono uses a consistent array layout across both szarray and mdarray, which made this possible.)
• Shore up the unit tests to cover both overloads.

/cc @buyaa-n, I thought this might interest you because it touches metasig.h, which you and I discussed a few weeks back. In this case, I'm introducing two signatures to metasig.h: one which takes a T[] and returns a ref T, and one which takes an Array and returns a ref byte. Note the use of DEFINE_METASIG_T instead of DEFINE_METASIG for the Array-consuming method. This is because we use the syntax C(ARRAY), which specifically refers to the System.Array class, and per comments at the very top of file, you need to use the _T version of the macro if you want to refer to specific classes. These new definitions are then used in corelib.h.

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Issue Details

---

Resolves #35528.

This PR has a few distinct components:

• Introduce the overload Array.GetArrayDataReference(Array array). I opted to name the parameter array instead of arr for local consistency with the existing overload.
• Remove the existing GetRawSzArrayData and GetRawArrayData internal methods and migrate their callers to the new public APIs.
• In coreclr, define the metasigs for both overloads so that we can intrinsicify the new API in the future without creating ambiguity within the existing jitinterface.cpp helpers.
• In mono, intrinsicify and add interp support for both overloads. (Unlike coreclr, mono uses a consistent array layout across both szarray and mdarray, which made this possible.)
• Shore up the unit tests to cover both overloads.

/cc @buyaa-n, I thought this might interest you because it touches metasig.h, which you and I discussed a few weeks back. In this case, I'm introducing two signatures to metasig.h: one which takes a T[] and returns a ref T, and one which takes an Array and returns a ref byte. Note the use of DEFINE_METASIG_T instead of DEFINE_METASIG for the Array-consuming method. This is because we use the syntax C(ARRAY), which specifically refers to the System.Array class, and per comments at the very top of file, you need to use the __T_ macro if you want to refer to specific classes. These new macros are then used in corelib.h.

Author:	GrabYourPitchforks
Assignees:	-
Labels:	area-System.Runtime
Milestone:	6.0.0

[jkotas]

CoreCLR part LGTM. Thanks!

[vargaz]

The mono changes look ok.

[GrabYourPitchforks]

@jkotas I thought I saw feedback from you earlier that I should add [NonVersionable] annotations, but looks like the feedback was deleted? Do you still want those annotations added, or did I imagine this?

[jkotas]

@jkotas I thought I saw feedback from you earlier that I should add [NonVersionable] annotations, but looks like the feedback was deleted?

Sorry for the confusion. I have deleted that feedback. GetArrayDataReference(Array array) cannot not be marked as [NonVersionable] since it it depends on MethodTable fields that are not guaranteed to be stable.

[GrabYourPitchforks]

Latest iteration:

• Address Marek's PR feedback
• Improve unit test coverage by exercising tests for arrays of varying rank