On Tue, Mar 08, 2022 at 10:25:45AM -0500, Marek Polacek wrote:
> On Tue, Mar 08, 2022 at 09:14:56AM -0600, Segher Boessenkool wrote:
> > On Tue, Mar 08, 2022 at 10:08:25AM -0500, Marek Polacek wrote:
> > > ...I don't see that. In fact copy_rtx does the same thing as
> > > copy_insn:
> > >
> > > case 'V':
> > > if (XVEC (orig, i) != NULL)
> > > {
> > > XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i));
> > >
> > > which will copy a zero-length vector too, right?
> >
> > It doesn't. It copies NULL as NULL. That is what that "if" is for.
>
> But XVEC (orig, i) is not null, it just has XVECLEN 0.
So where did *that* come from? This isn't correct RTL.
> > You can do similar in copy_insn_1?
>
> You mean copy_rtx? It already has the same XVEC (orig, i) != NULL check.
No, I mean do similar in copy_insn_1 as what copy_rtx already
(correctly) does.
> But like I said above, even if we didn't copy these XVECLEN 0 rtvecs,
> the crash would not go away.
An rtvec should never have length 0. Look at gen_rtvec for another
example.
You can get rid of the crash, sure. But it is a much better plan to try
and get rid of the actual problem! (And then add some more checking to
make sure this doesn't happen in the future.)
Segher
