Incorrect bitfield aliasing with Tree SSA

[Daniel Berlin]

On 6/18/07, Richard Kenner <kenner@vlsi1.ultra.nyu.edu> wrote:
> > > you have the fields A and C conflicting, which is wrong.
> >
> > Well, that is where structure-field aliasing comes in.  The two cannot
> > even alias for addressable fields:
>
> At tree level I'll take your word for it, but what about RTL level?
> Is that nonconflicting status passed to RTL?  What *is* the problem
> with just using the parent alias set?
>

At the RTL level, nothing.
If you ever wanted to make the RTL level do *better* than it does now,
you'd run into the same problem the tree level does.

> I continue to strongly feel that the field type shouldn't be used
> for ANYTHING!

Then you will continue to get worse code generation than you could, in
addition to bugs like we have now.

HTH,
Dan
>