[llvm] r185808 - InstCombine: Fold X-C1 <u 2 -> (X & -2) == C1

[Jay Foad]

On 8 July 2013 12:53, David Majnemer <david.majnemer at gmail.com> wrote:

> InstCombine: Fold X-C1 <u 2 -> (X & -2) == C1
>

How about:

* Generalizing for any power of two, e.g. X-C1 <u 16 -> (X & -16) == C1 iff
(C1 & 15) == 0
* Implementing the complement, C1-X <u 2 -> (X | 1) == C1 iff (C1 & 1) == 1

Jay.
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