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c-attribs.c: Fix warning about use of uninitialized variable nunits

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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 silence warning
and added an assert statement in order to check the invariant candidate.

gcc/c-family/ChangeLog:

2020-05-05  Stefan Schulze Frielinghaus  <stefansf@linux.ibm.com>

	* c-attribs.c (handle_vector_size_attribute): Add attribute
	nonnull for argument args in order to silence warning of
	uninitialized variable usage.  Since this is local to the
	compilation unit and thus cannot be checked at call sides by the
	compiler, added an assert statement in order to verify this.
This commit is contained in:
Stefan Schulze Frielinghaus 2020-04-26 09:42:29 +02:00
parent 733195e367
commit b776bdca93
2 changed files with 11 additions and 1 deletions
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8
gcc/c-family/ChangeLog
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@ -1,3 +1,11 @@
2020-05-05 Stefan Schulze Frielinghaus <stefansf@linux.ibm.com>
* c-attribs.c (handle_vector_size_attribute): Add attribute
nonnull for argument args in order to silence warning of
uninitialized variable usage. Since this is local to the
compilation unit and thus cannot be checked at call sides by the
compiler, added an assert statement in order to verify this.
2020-05-01 H.J. Lu <hongjiu.lu@intel.com>
PR target/93492

4
gcc/c-family/c-attribs.c
View File

@ -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 *);
@ -3697,6 +3697,8 @@ handle_vector_size_attribute (tree *node, tree name, tree args,
if (!type)
return NULL_TREE;
gcc_checking_assert (args != NULL);
tree new_type = build_vector_type (type, nunits);
/* Build back pointers if needed. */