On Tue, Apr 28, 2020 at 11:33:31AM +0200, Richard Biener wrote:
> On Tue, Apr 28, 2020 at 10:03 AM Stefan Schulze Frielinghaus via
> Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> >
> > In function handle_vector_size_attribute local variable nunits is
> > supposed to be initialized by function type_valid_for_vector_size.
> > However, in case ARGS is null the function may return with a non-null
> > value and leave nunits uninitialized. This results in warning/error:
> >
> > gcc/poly-int.h: In function 'tree_node*
> > handle_vector_size_attribute(tree_node**, tree, tree, int, bool*)':
> > gcc/poly-int.h:330:3: error: 'nunits' may be used uninitialized in this
> > function [-Werror=maybe-uninitialized]
> > 330 | ((void) (&(RES).coeffs[0] == (C *) 0), \
> > | ^
> > gcc/c-family/c-attribs.c:3695:26: note: 'nunits' was declared here
> > 3695 | unsigned HOST_WIDE_INT nunits;
> > |
> >
> > This is fixed by also checking whether ARGS is null or not.
> >
> > Bootstrapped and regtested on S/390. Ok for master?
>
> I think it's better to assert that it is not null for example by adding a
> nonnull attribute? Can you check if that works? If it doesn't the
> patch is OK.
Yes, that works, too. Please find an updated version attached. If you
think it is useful I could also add a gcc_assert (!args) for minimal
testing.
In function handle_vector_size_attribute local variable nunits is
supposed to be initialized by function type_valid_for_vector_size.
However, in case ARGS is null the function may return with a non-null
value and leave nunits uninitialized. This results in warning/error:
gcc/poly-int.h: In function 'tree_node*
handle_vector_size_attribute(tree_node**, tree, tree, int, bool*)':
gcc/poly-int.h:330:3: error: 'nunits' may be used uninitialized in this
function [-Werror=maybe-uninitialized]
330 | ((void) (&(RES).coeffs[0] == (C *) 0), \
| ^
gcc/c-family/c-attribs.c:3695:26: note: 'nunits' was declared here
3695 | unsigned HOST_WIDE_INT nunits;
|
Added attribute nonnull for argument args in order to state the
invariant and to silence warning.
gcc/c-family/ChangeLog:
2020-04-28 Stefan Schulze Frielinghaus <stefa...@linux.ibm.com>
* c-attribs.c (handle_vector_size_attribute): Add attribute
nonnull for argument args in order to state invariant and to
silence warning of uninitialized variable usage.
---
gcc/c-family/c-attribs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index ac936d5bbbb..e49a74c4048 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -117,7 +117,7 @@ static tree handle_tm_attribute (tree *, tree, tree, int,
bool *);
static tree handle_tm_wrap_attribute (tree *, tree, tree, int, bool *);
static tree handle_novops_attribute (tree *, tree, tree, int, bool *);
static tree handle_vector_size_attribute (tree *, tree, tree, int,
- bool *);
+ bool *) ATTRIBUTE_NONNULL(3);
static tree handle_nonnull_attribute (tree *, tree, tree, int, bool *);
static tree handle_nonstring_attribute (tree *, tree, tree, int, bool *);
static tree handle_nothrow_attribute (tree *, tree, tree, int, bool *);
--
2.25.3
