[llvm] AMDGPU/GlobalISel: Legalize G_ANYEXT s16 to s64 (PR #205470)

[via llvm-commits]

vangthao95 wrote:

> ok, so G_ANYEXT s16 to s64 really exists on true16. And it needs to be expanded to reg-sequence/merge-values at some point, now I am not sure what is the best place for it. Probably best to do it as late as possible since combines like anyext compared to tracking through merge-values. Legalizer is fine but I see we deal with 16->s64 extends in regbanklegalize so probably best to not make exceptions? what do you think

It would make sense to me to handle this in regbanklegalize since we also handle zext and sext there.

https://github.com/llvm/llvm-project/pull/205470