[llvm] [InstCombine] Fold zero-guarded biased-shifted ctlz to drop the zero check (PR #210541)

[Lucas Ly Ba via llvm-commits]

lucasly-ba wrote:

simplifyWithOpReplaced already handles the flag flip, it just doesn't reach the ctlz here because the pattern is deeper than the recursion limit. So this is redundant

https://github.com/llvm/llvm-project/pull/210541