On Wed, Feb 13, 2019 at 12:14 AM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> fold_binary_loc verifies that strlen argument is a pointer, but doesn't
> verify what the pointee is.
> The following patch just always converts it to the right pointer type
> (const char *) and dereferences only that.
> Another option would be punt if the pointee (TYPE_MAIN_VARIANT) is not
> char_type_node, but then e.g. unsigned_char_type_node or
> signed_char_type_node (or maybe char8_t) wouldn't be that bad.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
> 2019-02-12 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/89314
> * fold-const.c (fold_binary_loc): Cast strlen argument to
> const char * before dereferencing it. Formatting fixes.
>
> * gcc.dg/pr89314.c: New test.
>
> --- gcc/fold-const.c.jj 2019-02-11 18:04:18.000000000 +0100
> +++ gcc/fold-const.c 2019-02-12 21:11:21.491388038 +0100
> @@ -10740,20 +10740,24 @@ fold_binary_loc (location_t loc, enum tr
> strlen(ptr) != 0 => *ptr != 0
> Other cases should reduce to one of these two (or a constant)
> due to the return value of strlen being unsigned. */
> - if (TREE_CODE (arg0) == CALL_EXPR
> - && integer_zerop (arg1))
> + if (TREE_CODE (arg0) == CALL_EXPR && integer_zerop (arg1))
> {
> tree fndecl = get_callee_fndecl (arg0);
>
> if (fndecl
> && fndecl_built_in_p (fndecl, BUILT_IN_STRLEN)
> && call_expr_nargs (arg0) == 1
> - && TREE_CODE (TREE_TYPE (CALL_EXPR_ARG (arg0, 0))) ==
> POINTER_TYPE)
> + && (TREE_CODE (TREE_TYPE (CALL_EXPR_ARG (arg0, 0)))
> + == POINTER_TYPE))
> {
> - tree iref = build_fold_indirect_ref_loc (loc,
> - CALL_EXPR_ARG (arg0, 0));
> + tree ptrtype
> + = build_pointer_type (build_qualified_type (char_type_node,
> + TYPE_QUAL_CONST));
> + tree ptr = fold_convert_loc (loc, ptrtype,
> + CALL_EXPR_ARG (arg0, 0));
> + tree iref = build_fold_indirect_ref_loc (loc, ptr);
> return fold_build2_loc (loc, code, type, iref,
> - build_int_cst (TREE_TYPE (iref), 0));
> + build_int_cst (TREE_TYPE (iref), 0));
> }
> }
>
> --- gcc/testsuite/gcc.dg/pr89314.c.jj 2019-02-12 21:15:11.624589045 +0100
> +++ gcc/testsuite/gcc.dg/pr89314.c 2019-02-12 21:14:49.138960233 +0100
> @@ -0,0 +1,13 @@
> +/* PR tree-optimization/89314 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -Wbuiltin-declaration-mismatch -Wextra" } */
> +
> +extern __SIZE_TYPE__ strlen (const float *); /* { dg-warning "mismatch in
> argument 1 type of built-in function" } */
> +void bar (void);
> +
> +void
> +foo (float *s)
> +{
> + if (strlen (s) > 0)
> + bar ();
> +}
>
> Jakub
