[llvm] [LoopVectorize] Add test for fixed vs scalable vectorization IR shapes (PR #161489)

[via llvm-commits]

2001SameerSharma wrote:

I checked the existing llvm/test/Transforms/LoopVectorize tests. There are tests that run with scalable vectorization enabled and others with it disabled, but I didn’t find one that runs the same loop under both modes on AArch64 and compares the IR shapes while ensuring semantic equivalence. This test adds that explicit coverage.

https://github.com/llvm/llvm-project/pull/161489