[PATCH] Fix ICE in strlen () > 0 folding (PR tree-optimization/89314)

[Richard Biener]

On Wed, Feb 13, 2019 at 12:14 AM Jakub Jelinek <jakub@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  <jakub@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