On Mon, Apr 14, 2025 at 08:28:55PM +0000, Qing Zhao wrote:
> C_MAYBE_CONST_EXPR is a C FE operator that will be removed by c_fully_fold.
> In c_fully_fold, it assumes that operands of function calls have already
> been folded. However, when we build call to .ACCESS_WITH_SIZE, all its
> operands are not fully folded. therefore the C FE specific operator is
> passed to middle-end.
>
> In order to fix this issue, fully fold the parameters before building the
> call to .ACCESS_WITH_SIZE.
>
> I am doing the bootstrap and regression testing on both X86 and aarch64 now.
> Okay for trunk if testing going well?
>
> thanks.
>
> Qing
>
> PR c/119717
>
> gcc/c/ChangeLog:
>
> * c-typeck.cc (build_access_with_size_for_counted_by): Fully fold the
> parameters for call to .ACCESS_WITH_SIZE.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/pr119717.c: New test.
> ---
> gcc/c/c-typeck.cc | 8 ++++++--
> gcc/testsuite/gcc.dg/pr119717.c | 24 ++++++++++++++++++++++++
> 2 files changed, 30 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/pr119717.c
>
> diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
> index 3870e8a1558..dd176d96a41 100644
> --- a/gcc/c/c-typeck.cc
> +++ b/gcc/c/c-typeck.cc
> @@ -3013,12 +3013,16 @@ build_access_with_size_for_counted_by (location_t
> loc, tree ref,
> gcc_assert (c_flexible_array_member_type_p (TREE_TYPE (ref)));
> /* The result type of the call is a pointer to the flexible array type. */
> tree result_type = c_build_pointer_type (TREE_TYPE (ref));
> + tree first_param
> + = c_fully_fold (array_to_pointer_conversion (loc, ref), FALSE, NULL);
> + tree second_param
> + = c_fully_fold (counted_by_ref, FALSE, NULL);
Why FALSE? Just use false. You can also use nullptr rather than NULL now.
> tree call
> = build_call_expr_internal_loc (loc, IFN_ACCESS_WITH_SIZE,
> result_type, 6,
> - array_to_pointer_conversion (loc, ref),
> - counted_by_ref,
> + first_param,
> + second_param,
> build_int_cst (integer_type_node, 1),
> build_int_cst (counted_by_type, 0),
> build_int_cst (integer_type_node, -1),
> diff --git a/gcc/testsuite/gcc.dg/pr119717.c b/gcc/testsuite/gcc.dg/pr119717.c
> new file mode 100644
> index 00000000000..e5eedc567b3
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr119717.c
> @@ -0,0 +1,24 @@
> +/* PR c/119717 */
> +/* { dg-additional-options "-std=c23" } */
> +/* { dg-do compile } */
> +
> +struct annotated {
> + unsigned count;
> + [[gnu::counted_by(count)]] char array[];
> +};
> +
> +[[gnu::noinline,gnu::noipa]]
> +static unsigned
> +size_of (bool x, struct annotated *a)
> +{
> + char *p = (x ? a : 0)->array;
> + return __builtin_dynamic_object_size (p, 1);
> +}
> +
> +int main()
> +{
> + struct annotated *p = __builtin_malloc(sizeof *p);
> + p->count = 0;
> + __builtin_printf ("the bdos whole is %ld\n", size_of (0, p));
> + return 0;
> +}
> --
> 2.31.1
>
Marek
