[llvm] [InstCombine] Fold max(max(x, c1) << c2, c3) —> max(x << c2, c3) when c3 >= c1 * 2 ^ c2 (PR #140526)

[via llvm-commits]

Charukesh827 wrote:

If we use this [Alive2 proof](https://alive2.llvm.org/ce/z/sS_Urz) then our aim "Fold max(max(x, c1) << c2, c3) —> max(x << c2, c3) when c3 >= c1 * 2 ^ c2" itself becomes false, Shouldn't we do the Alive2 experiment with only one x and all other constant(like [Alive2](https://alive2.llvm.org/ce/z/wR826y))?

https://github.com/llvm/llvm-project/pull/140526