Hi!
On Tue, Mar 08, 2022 at 10:08:25AM -0500, Marek Polacek wrote:
> On Mon, Mar 07, 2022 at 07:19:09PM -0600, Segher Boessenkool wrote:
> > On Mon, Mar 07, 2022 at 07:03:17PM -0500, Marek Polacek via Gcc-patches
> > wrote:
> > > In r270550, Jakub fixed classify_insn to handle asm goto: if the asm can
> > > jump to a label, the insn should be a JUMP_INSN.
> > >
> > > However, as the following testcase shows, non-null ASM_OPERANDS_LABEL_VEC
> > > doesn't guarantee that the rtx has any actual labels it can branch to.
> >
> > But it should.
>
> Ok, that would make sense. However...
>
> > > Here, the rtvec has 0 elements because of the __thread variable: we
> > > perform
> > > ix86_rewrite_tls_address which calls copy_isns and that allocates the
> > > rtvec:
> > >
> > > XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i));
> >
> > So fix *that* instead? Everywhere else does not use length zero RTL
> > vectors. copy_rtx makes sure to do the right thing here, for example.
>
> ...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.
You can do similar in copy_insn_1?
Segher
