[llvm] [InstCombine] Fold comparison of adding two z/sext booleans (PR #67895)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> @dtcxzyw I don't see how the lookup-table based implementation improves this code. It makes it impossible to understand or verify the logic behind the transform.

I will add a compile-time helper for this PR. Then we can write a constexpr binary function and match the truth tables.


https://github.com/llvm/llvm-project/pull/67895