value range propagation for _bitwise_ OR

[Andrei Alexandrescu]

On 04/10/2010 04:21 PM, Adam D. Ruppe wrote:
> On Sat, Apr 10, 2010 at 04:05:06PM -0500, Andrei Alexandrescu wrote:
>> The minimum for unsigned numbers is very simple: min(mina, minb).
>
> mina = 1
> minb = 0
>
> min(1, 0) == 0
>
> But, 1|0 == 1
>
> max(mina, minb) looks to work though. Consider that ORing can only set bits -
> it can never take a one and spit out a zero. Therefore, x|y>= x&&  x|y>= y,
> which only works on the max(mina, minb) function.

Sorry, I meant max of the two minima.

Andrei