[llvm] [SelectOpt] Support ADD and SUB with zext operands. (PR #115489)

[Alexander Kornienko via llvm-commits]

alexfh wrote:

Heads up: we see a number of test failures on aarch64 after this commit. Might be a miscompilation. A reduced test case is in the works.

https://github.com/llvm/llvm-project/pull/115489