virtual stack regs.

[Uros Bizjak]

On 6/19/07, Rask Ingemann Lambertsen <rask@sygehus.dk> wrote:

> > 3) If they really are uninitialized, why is it a problem to assign zero
> > to them.
>
>    It is possible to mess up the substitution that the vregs pass performs.
> IIRC, it happened to me once because I accidentally put one of these virtual
> pseudo inside a (clobber) or (use) or something like that. I don't quite
> recall the details, but maybe the substitution fails if they appear outside
> an operand?

There is one annoying case in PR32374, where on-the-stack constructor
creates invalid memory clobber that includes virtual-stack-regs. These
are simply ignored by vregs pass and this confuses dataflow register
initialization.

Uros.