From: Jason Merrill <jason@redhat.com>
To: Tamar Christina <tamar.christina@arm.com>, gcc-patches@gcc.gnu.org
Cc: nd@arm.com, nathan@acm.org
Subject: Re: [PATCH][c++ frontend]: check for missing condition for novector [PR115623]
Date: Tue, 25 Jun 2024 12:10:53 -0400 [thread overview]
Message-ID: <54838cdd-21ef-4eb1-9f8c-e94a469bdca3@redhat.com> (raw)
In-Reply-To: <patch-18582-tamar@arm.com>
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?
> 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 } */
>
>
>
>
next prev parent reply other threads:[~2024-06-25 16:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-25 8:01 Tamar Christina
2024-06-25 16:10 ` Jason Merrill [this message]
2024-06-25 16:52 ` Tamar Christina
2024-06-25 21:23 ` Jason Merrill
2024-06-27 15:25 ` Tamar Christina
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