[PATCH] D140935: [InstCombine] C - cttz(X) => ctlz(X) if C is bitwidth

[Nikita Popov via Phabricator via llvm-commits]

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In D140935#4025375 <https://reviews.llvm.org/D140935#4025375>, @RKSimon wrote:

> Won't this only work if only a single bit is set (pow2)?

That, and it's off by one (the constant needs to be bitwidth-1, not bitwidth). The right transform would be this: https://alive2.llvm.org/ce/z/v588Fk


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