[llvm] [GlobalIsel] Combine zext of trunc (episode II) (PR #108305)

[Jay Foad via llvm-commits]

Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/108305 at github.com>


jayfoad wrote:

> but the first combine in this PR only calls known bits on one register, which ought to be cheaper.

Maybe... but calling computeKnownBits on a G_CONSTANT should be pretty cheap anyway.

https://github.com/llvm/llvm-project/pull/108305