value range propagation for logical OR

[BCS]

Hello Andrei,

> Consider:
> 
> byte c = a | b;
> 
> Say you already know min_a, max_a, min_b, and max_b. How do you
> compute min_c and max_c? I thought of it for a bit and it seems quite
> tricky.
> 


x_bit_max == "the largest bit in x_max ^ x_min"
x_oth_max == x_bit_max - 1;

c_max = max(a_bit_max | b_oth_max, b_bit_max | a_oth_max) | (a_max & ~(a_bit_max 
| a_oth_max));




-- 
... <IXOYE><