Re: Incorrect bitfield aliasing with Tree SSA

["Daniel Berlin" <dberlin at dberlin dot org>]

On 6/16/07, Richard Kenner <kenner@vlsi1.ultra.nyu.edu> wrote:
> > You guys have come up with a very weird idea of what
> > non-addressability means.  These fields are all addressable, they
> > are just not directly addressable.
>
> Terminology is always tricky here.  "addressable" in this context means
> that no pointer can point directly to the field.

Which is, well, at least in aliasing and pointer tracking, a meaningless thing.

> So if I have
>         struct foo {int x; float y; } bar;
>         int *pi;
>         float *pf;
>
> and mark X as "nonaddressable", I know that an assigment to *pi can't
> affect bar.x.

But if you add

struct foo *foop = &bar.

foop->x = 5.

It can, even though we *claim* X is nonaddressable.

If you told me this is what you meant by "nonaddressable", i'd
probably call you crazy.

It is most certainly addressable, because you can form the address of it.