[PATCH] D115629: [RISCV] Use binvi and bexti to fold and (not (srl X, C)), 1

[Jianjian Guan via Phabricator via llvm-commits]

jacquesguan added a comment.

In D115629#3189585 <https://reviews.llvm.org/D115629#3189585>, @craig.topper wrote:

> Have you seen real cases of this pattern? InstCombine canonicalizes this to (xor (and (srl X, C), 1), 1) before we get to SelectionDAG.

Yes. As you said, InstCombine do canonicalize this to `xor (and (srl X, C), 1), 1` , but DAGCombine will also fold `(xor (and x, y), y) -> (and (not x), y)`. So we still get `and (not (srl X, C)), 1` in SelectionDAG. I will add another case `xor (and (srl X, C), 1), 1` to show this.


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