[llvm] [LLVM][AArch64][SVE] Mark DUP immediate instructions with isAsCheapAsAMove. (PR #133945)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> When you throw intervening function calls in to the mix, could it lead to more fills and spills?

The affected instructions are also marked with `isReMaterializable` so we should not need to spill them.  Whilst this chance might trigger more LICM I figure is that does trigger the need to spill the end result will be to spill one of these rematerialisable instructions first and so the affect would be the same as if the COPY/DUP had not been hoisted in the first place?

https://github.com/llvm/llvm-project/pull/133945