[llvm] r182200 - isKnownToBeAPowerOfTwo: (X & Y) + Y is a power of 2 or zero if y is also.

David Majnemer david.majnemer at gmail.com
Sat May 18 15:03:28 PDT 2013


On Sat, May 18, 2013 at 1:13 PM, Duncan Sands <duncan.sands at gmail.com>wrote:

> Hi David,
>
>
> On 18/05/13 21:30, David Majnemer wrote:
>
>> Author: majnemer
>> Date: Sat May 18 14:30:37 2013
>> New Revision: 182200
>>
>> URL: http://llvm.org/viewvc/llvm-**project?rev=182200&view=rev<http://llvm.org/viewvc/llvm-project?rev=182200&view=rev>
>> Log:
>> isKnownToBeAPowerOfTwo: (X & Y) + Y is a power of 2 or zero if y is also.
>>
>
> if the + is nsw or nuw then the sum can't be zero.  I don't know if this is
> useful in practice.
>

I noticed this too, I'm trying to find if I can tickle something that would
make this happen.


>
> Ciao, Duncan.
>
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