ivopts improvement

[Zdenek Dvorak]

Hi,

> > (since the use_uses_inced_iv test is meaningless).
> 
> To me it seems use_uses_inced_iv has meaning:
> - it models something: it states whether the comparison is using
>   the iv increment result or the iv phi result.

but that has nothing to do with the value of the iv.  For instance,
in the following:

a = phi (0, a')
b = phi (1, b')
c = phi (1, c')

a' = a + 1;
tmp = b;

compare (a'/tmp/c, something)

b' = tmp + 1;
c' = c + 1;

a', tmp and c are completely equivalent, yet your code for some reason claims
to handle c and the other two differently.

Zdenek