[NativeAOT] Address some COOP native helpers that could cause suspension pauses.

[VSadov]

Fixes: #73655

Fixes common cases of unbounded data copying in COOP mode, that may cause suspension pauses.
(Such pauses were actually observed while testing and measuring suspension changes)

Also moves Buffer.Memmove<T> to shared code to be used by both CoreCLR and NativeAOT.

I think Mono may use it too and benefit form interruptibility, in theory, but I am not sure.
For blobs containing GC references, we perform GC-atomic card-updating copies in chunks which are not necessarily aligned to array elements. I am not sure if Mono BulkMoveWithWriteBarrier can be used like this.

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Issue Details

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Fixes: #73655

Fixes common cases of unbounded data copying in COOP mode, that may cause suspension pauses.
(It was actually observed while testing and measuring suspension changes)

Also moves Buffer.Memmove<T> to shared code to be used by both CoreCLR and NativeAOT.

I think Mono may use it too and benefit form interruptibility, but I am not sure.
For blobs containing GC references, we perform GC-atomic card-updating copies in chunks aligned to GC words, but not to array elements. I am not sure if Mono BulkMoveWithWriteBarrier can be used like this.

Author:	VSadov
Assignees:	-
Labels:	area-NativeAOT-coreclr
Milestone:	-

[VSadov]

/azp run runtime-extra-platforms

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Azure Pipelines successfully started running 1 pipeline(s).

[jkotas]

Thanks!

[VSadov]

Thanks!

[VSadov]

@BrzVlad Re: BulkMoveWithWriteBarrier . Just wonder - can Mono change BulkMoveWithWriteBarrier to the same shape as in CoreCLR and NativeAOT?
If that is possible, Mono could also benefit from the shared implementation of Buffer.Memmove<T>

[BrzVlad]

@VSadov Yeah, it is fairly straightforward. I opened issue #78498 so I remember to do it sometime in the future.