Do not give up early on access path oracle

[Richard Biener]

On Mon, 17 Jun 2019, Jan Hubicka wrote:

> > 
> > Hmm, !maybe_eq () -> ! max_size1 == size1 -> max_size != size1 thus
> > I think && is correct if you want to disambiguate a[1].v2 and a[i].v1
> > 
> > But yes, if you don't want that then || is cheaper.  Probably add
> > another testcase with one of the accesses with a constant index?
> 
> Hmm, OK, without unions I do not see how I could disambiguate something
> with || and not &&.
> Do we care about the testcase with union and constant accesses I sent?

Wouldn't it be as simple as

struct S { int i; int j; };

struct S a[10];

and a[i].i vs. a[1].j?  The first has offset = 0, max_size = sizeof(a)-4
while the second has offset = 12, max_size = 4 and thus they overlap.

Richard.