[llvm] [AArch64] Unrolling of loops with vector instructions. (PR #147420)

[Usman Nadeem via llvm-commits]

UsmanNadeem wrote:

It looks like this patch now also prevents the unroll of the original scalar loop when the alias/iter checks fail. Seems like all the variants of the loop share the `"llvm.loop.isvectorized"` metadata so none of the variants will be unrolled.

See example: https://godbolt.org/z/nn1fh67ns

https://github.com/llvm/llvm-project/pull/147420