[llvm] [AArch64] Fix regression from “Fold scalar-to-vector shuffles into DUP/FMOV" (PR #178227)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Do you have a test case for the issue this was hitting before? Was it stuck in a loop, or just taking a very long time?

https://github.com/llvm/llvm-project/pull/178227