[llvm] [AArch64] - Improve costing for Identity shuffles for SVE targets. (PR #165375)

[David Green via llvm-commits]

davemgreen wrote:

> it causes some other shuffle pattern costs to change

Do you have an example of where it changed the cost negatively? (I can imagine it could, but it would be interesting which cases are causing problems and if we could add testing for them).

https://github.com/llvm/llvm-project/pull/165375