[llvm] [LoopInterchange] Improve profitability check for vectorization (PR #133672)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

Proposal: Instead of doublicating all dependencies, use the flag to mean "all dependencies of this vector are forward dependencies". It is reset whenever a dependency does not guarantee that the Dst is executed after Src (in the same loop iteration). This includes if Dst and Src are in different basic blocks (unless you can prove dominance).

You could go as for as to encode it as `<` and `*` in another trailing element of the dependence vector.

https://github.com/llvm/llvm-project/pull/133672