[PATCH] D116915: [DAGCombiner][AArch64] Enhance to support for scalar CSINC

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

Thanks. And the CopyFromReg? This is currently converting `add(csel(C, 1, cc), CopyFromReg(x))` into `csinc(add(x, C), x)`. I'm not sure why it would be limited to a CopyFromReg. I would expect to convert any `add(csel(C, 1, cc), y)` (or `add(y, csel(C, 1, cc))` as add is commutative).

In order to be profitable this seems to also be relying on the fact that the add(x, C) will turn into an ADDri, which wouldn't be true for all constants. It might be neutral for larger constants? It's probably worth adding a test or two.


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