On 6/27/24 11:25 AM, Tamar Christina wrote:
-----Original Message-----
From: Jason Merrill <ja...@redhat.com>
Sent: Tuesday, June 25, 2024 10:24 PM
To: Tamar Christina <tamar.christ...@arm.com>
Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>; nat...@acm.org
Subject: Re: [PATCH][c++ frontend]: check for missing condition for novector
[PR115623]
On 6/25/24 12:52, Tamar Christina wrote:
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?
Please.
How about this version:
This fixes it by issuing ignoring the pragma when there's no loop condition
the same way we do in the C frontend.
Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
Ok for master? and backport to GCC-14?
OK.
Thanks,
Tamar
gcc/cp/ChangeLog:
PR c++/115623
* semantics.cc (finish_for_cond): Add check for C++ cond.
gcc/testsuite/ChangeLog:
PR c++/115623
* g++.dg/vect/vect-novector-pragma_2.cc: New test.
-- inline copy of patch --
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index
08f5f245e7d11a76b975bb04c0075ded1b3ca8ba..4e1374c98130247eb10e3fe7571fec00834e9c05
100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -1501,7 +1501,7 @@ finish_for_cond (tree cond, tree for_stmt, bool ivdep,
tree unroll,
build_int_cst (integer_type_node,
annot_expr_unroll_kind),
unroll);
- if (novector && cond != error_mark_node)
+ if (novector && cond && cond != error_mark_node)
FOR_COND (for_stmt) = build3 (ANNOTATE_EXPR,
TREE_TYPE (FOR_COND (for_stmt)),
FOR_COND (for_stmt),
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..d2a8eee8d716188880281b4e34a694576b6783f0
--- /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;
+}
+
Jason
