[llvm] [DA] Cache delinearization results. NFCI. (PR #164379)

[Ryotaro Kasuga via llvm-commits]

https://github.com/kasuga-fj commented:

Caching itself looks reasonable to me, but I have a high-level concern: DA and Delinearization are currently tightly coupled. Before making further improvements, I think it would be better to first move some of the related logic from DA to Delinearization.

https://github.com/llvm/llvm-project/pull/164379