Implement AVX SetHighLow

[fiigii]

I missed Avx.SetHighLow in #17030 ...

@CarolEidt @tannergooding PTAL

[fiigii]

@CarolEidt can we merge this PR for 2.1 if it looks good to you?

[CarolEidt]

I would prefer not to merge this for 2.1. We are in the final stages of wrapping up as many bugs as possible for 2.1, and I'd prefer not to take the risk of new functionality & tests.

[fiigii]

But we have exposed this API in the corefx package.. sorry my bad.

[fiigii]

There was an oversight that Avx.SetHighLow was missed when I submitted PR #17030. I know that tomorrow is the ZBB date, and we have decided to stop enabling new intrinsic in the runtime.
However, the API of Avx.SetHighLow has been exposed in the CoreFX package. So, I suggest merging this PR for 2.1 to avoid propagating this mistake to CoreFX workflow. Meanwhile, this is just a simple "NoCodegen" helper-intrinsic, which will be converted to Avx.InsertVector128 in the importer, so I believe it won't has any codegen bug to disturb the ZBB plan.

@CarolEidt @AndyAyersMS @tannergooding @eerhardt Do you agree?

[tannergooding]

I think we will need to do one of:

• Take this PR
• Take a PR removing the API from CoreFX
• Do nothing and tell people using the preview to not use SetHighLow

[4creators]

IMO the best option currently is:

• Take a PR removing the API from CoreFX

as it explictly avoids any risks.

[CarolEidt]

Another possible option is to remove the tests from this PR and merge it. It may be better to have u functionality w/o tests than to risk adding further noise to existing test challenges.

Note that taking a PR to remove the API from CoreFX definitely does not avoid any risks. It's almost as easy to break things when removing something as when adding.

[fiigii]

Another possible option is to remove the tests from this PR and merge it.

Agree, will do.

[fiigii]

Removed the tests.

[4creators]

taking a PR to remove the API from CoreFX definitely does not avoid any risks

I do not agree as API is not used anywhere and in CoreFX we have only facade to S.P.C implementation.

However, I am equally OK with adding implementation of Avx.SetHighLow

[fiigii]

@CarolEidt Can we merge this PR?