Implement LLVM x86 adx intrinsics

[TDecking]

See title. It also explots a small opportunity to deduplicate a bit of intrinsics code.

[TDecking]

This is likely the last extension I can develop for a while. The remaining ones are either not supprted by my computer or implemented in stdarch using inline assembly.

On a related note, I managed to rewrite some intrinsics in stdarch using generic intrinsics, which means that the next stdarch submodule update over at rust-lang will come with free and full support for x86 fma.

[RalfJung]

Oh that's cool, does that mean we can remove some of the intrinsics in Miri as they can no longer be reached via stdarch? :D

[TDecking]

The number is small, but yes, some code can be removed.

[RalfJung]

Good to know, I opened https://github.com/rust-lang/miri/issues/3691 to track that.

[RalfJung]

That works, thanks. :)

@bors r+

[bors]

:pushpin: Commit 6374a8746b41f8f16e8da72e0c720569f15d84e3 has been approved by RalfJung

It is now in the queue for this repository.

[bors]

:hourglass: Testing commit 6374a8746b41f8f16e8da72e0c720569f15d84e3 with merge 0904817476aa231644a87d164764c99f36457e4a...

[bors]

:broken_heart: Test failed - checks-actions

[RalfJung]

@bors r+

[bors]

:pushpin: Commit be9eece2afea54aad02dfa061b0fe628e4cc9270 has been approved by RalfJung

It is now in the queue for this repository.

[bors]

:hourglass: Testing commit be9eece2afea54aad02dfa061b0fe628e4cc9270 with merge be67edbfbff287a60f8c9ec3eb20dc5234a1f2ec...

[bors]

:sunny: Test successful - checks-actions Approved by: RalfJung Pushing be67edbfbff287a60f8c9ec3eb20dc5234a1f2ec to master...