[llvm] [LLVM][IR] Add native vector support to ConstantInt & ConstantFP. (PR #74502)

[Nikita Popov via llvm-commits]

nikic wrote:

Something important I forgot: Can you please test what happens with `<2 x i8> <i8 42, i8 42>` in `use-constant-int-for-fixed-length-splat` mode? This needs to create the same representation as `<2 x i8> splat (i8 42)`, to maintain a canonical form of constants.

(This applies to a lesser degree to the scalable case -- in that case it's "just" a missed constant folding opportunity.)

https://github.com/llvm/llvm-project/pull/74502