[llvm] [LoopIdiom] Use HashRecognize to optimize CRC (PR #143208)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

We now test type-mismatches in llvm-test-suite! https://github.com/llvm/llvm-test-suite/pull/261. I found a couple of weaknesses in the analysis, and some errors in the transform: I have now verified that, with https://github.com/llvm/llvm-project/pull/144878 and https://github.com/llvm/llvm-project/pull/144881, the newly-added tests in llvm-test-suite are optimized correctly. I'm feeling more confident about turning this optimization on by default: kindly let me know if you have other testing-related suggestions, so we can increase our confidence further.

https://github.com/llvm/llvm-project/pull/143208