[llvm] [VP][EVL] Support select instruction with EVL-vectorization (PR #109614)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> > I’ve also been seriously thinking about this recently. But my thinking is whether it’s really necessary to create an EVL version for each recipe, especially after noticing VLOpt #108640.
> 
> If possible, I think it is better to avoid creating EVL that is larger than required. The first reason is that the VLOpt pass is not very mature and may miss some cases. The original intention of the pass is to fix the case introduced by vector GEP which has no EVL based version. In that case, there was no way for the compiler to use the correct VL at the IR level which makes that pass necessary. But if the compiler can avoid introducing larger than needed EVL, that is preferred, since it will create less work for the VLOpt pass, which will improve compiler times.

+1

https://github.com/llvm/llvm-project/pull/109614