JIT: Fix various HW intrinsic lowerings for unused values

[jakobbotsch]

Fix #91173

In the test case we disable CSE but then hoisting hoists out a HWINTRINSIC node that ends up not CSE'd. This results in a top level unused HWINTRINSIC node that lowering didn't handle in a transformation. There's a bunch of transformations that do not handle this correctly, so fix it in all of them.

I couldn't find a test case that does not require disabling CSE (and I didn't include the existing one since it never finishes with the bug fixed), but I wouldn't bet on that one doesn't exist, so I think we should backport this anyway.

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Issue Details

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Fix #91173

In the test case we disable CSE but then hoisting hoists out a HWINTRINSIC node that ends up not CSE'd. This results in a top level unused HWINTRINSIC node that lowering didn't handle in a transformation.

I couldn't find a test case that does not require disabling CSE (and I didn't include the existing one since it never finishes with the bug fixed), but I wouldn't bet on that one doesn't exist, so I think we should backport this anyway.

Author:	jakobbotsch
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[EgorBo]

Might makes sense to inspect other TryGetUse+ReplaceUse patterns where we don't handle the else case?

[jakobbotsch]

Might makes sense to inspect other TryGetUse+ReplaceUse patterns where we don't handle the else case?

Good idea, there's definitely more cases, e.g. in LowerHWIntrinsicGetElement.

[jakobbotsch]

/backport to release/8.0

[github-actions]

Started backporting to release/8.0: https://github.com/dotnet/runtime/actions/runs/6012524422