The 06/25/2024 17:10, Jason Merrill wrote:
> On 6/25/24 04:01, Tamar Christina wrote:
> > Hi All,
> >
> > It looks like I forgot to check in the C++ frontend if a condition exist
> > for the
> > loop being adorned with novector. This causes a segfault because cond isn't
> > expected to be null.
> >
> > This fixes it by issuing the same kind of diagnostics we issue for the other
> > pragmas.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> >
> > Ok for master? and backport to GCC-14?
>
> Hmm, I'm not sure we want to error in this case; it's pointless, but
> indeed we aren't going to vectorize a loop that always loops. I'd think
> we should treat it the same as an explicit "true" condition. And
> perhaps the same for unroll/ivdep.
>
> Does the C front-end treat the null condition different from a constant
> true condition?
>
No, in the C front-end we error for ivdep and unroll, but for novector we
explicitly
suppress it by checking for novector && cond && cond != error_mark_node instead
of
just novector && cond != error_mark_node in the use site.
Do you want to handle it that way to be consistent?
Cheers,
Tamar
> > Thanks,
> > Tamar
> >
> > gcc/cp/ChangeLog:
> >
> > PR c++/115623
> > * parser.cc (cp_parser_c_for): Add check for C++ cond.
> >
> > gcc/testsuite/ChangeLog:
> >
> > PR c++/115623
> > * g++.dg/vect/vect-novector-pragma_2.cc: New test.
> >
> > ---
> > diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> > index
> > e7409b856f1127e303c6515a3bb2d61a10e7c378..24d7b0e4992fdff69951ac5955f304e473f53374
> > 100644
> > --- a/gcc/cp/parser.cc
> > +++ b/gcc/cp/parser.cc
> > @@ -14107,6 +14107,12 @@ cp_parser_c_for (cp_parser *parser, tree scope,
> > tree init, bool ivdep,
> > "%<GCC unroll%> pragma");
> > condition = error_mark_node;
> > }
> > + else if (novector)
> > + {
> > + cp_parser_error (parser, "missing loop condition in loop with "
> > + "%<GCC novector%> pragma");
> > + condition = error_mark_node;
> > + }
> > finish_for_cond (condition, stmt, ivdep, unroll, novector);
> > /* Look for the `;'. */
> > cp_parser_require (parser, CPP_SEMICOLON, RT_SEMICOLON);
> > diff --git a/gcc/testsuite/g++.dg/vect/vect-novector-pragma_2.cc
> > b/gcc/testsuite/g++.dg/vect/vect-novector-pragma_2.cc
> > new file mode 100644
> > index
> > 0000000000000000000000000000000000000000..05dba4db1c6544bc53cd05482d1b2e767052cf43
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/vect/vect-novector-pragma_2.cc
> > @@ -0,0 +1,10 @@
> > +/* { dg-do compile } */
> > +
> > +void f (char *a, int i)
> > +{
> > +#pragma GCC novector
> > + for (;;i++)
> > + a[i] *= 2;
> > +}
> > +
> > +/* { dg-error "missing loop condition in loop with 'GCC novector' pragma
> > before ';' token" "" { target *-*-* } 6 } */
> >
> >
> >
> >
>
--
