[llvm] [AArch64] Optimization of repeated constant loads (#51483) (PR #86249)

[David Green via llvm-commits]

davemgreen wrote:

It looks like gcc will transform repeated constants to `or x, x, lsl 32` too:
https://gcc.godbolt.org/z/h6MqTja1s

Is it worth doing that first, then this could be simplified a little to just having to look at `str(or(x, x, lsl 32))`.

Can you add some testing too? Thanks

https://github.com/llvm/llvm-project/pull/86249