[llvm] [GlobalIsel] Visit ICmp (PR #105991)

[Nikita Popov via llvm-commits]

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In-Reply-To: <llvm.org/llvm/llvm-project/pull/105991 at github.com>


nikic wrote:

Sorry, my phrasing there was bad. It's not "a lot of expensive combines", it's one combine that is based on isKnownNonZero() analysis being introduced here, which in turn has a lot of recursive KnownBits calls.

FWIW from IR experience, we know that simplifyICmpInst and KnownBits-based icmp simplification take up a large fraction of InstCombine time for many programs, so the cost/benefit question here is not an idle concern.

https://github.com/llvm/llvm-project/pull/105991