On Sat, Apr 02, 2022 at 06:53:55PM +0800, Xi Ruoyao wrote:
> I made a mistake in r12-7962 and it causes an ICE running g++.dg-struct-
> layout-1 tests. The fix and a reduced test are included in this patch.
> Ok for trunk?
>
> --------------------
>
> DECL_SIZE(x) is NULL if x is a flexible array member, but I forgot to
> check it in r12-7962. Then if we increase the size of a struct with
> flexible array member (by using aligned attribute), the code will
> dereference NULL trying to use the "size" of the flexible array member.
>
> gcc/
>
> * config/mips/mips.cc (mips_function_arg): Check if DECL_SIZE is
> NULL before dereferencing it.
>
> gcc/testsuite/
>
> * gcc.target/mips/pr102024-4.c: New test.
Ok, sorry for not catching that.
All other targets guard such integer_zerop (DECL_SIZE (...)) uses
with either DECL_SIZE (...) != NULL_TREE or DECL_BIT_FIELD, so this is the
only such spot.
> diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
> index a6dd1e9e7b6..079bb03968a 100644
> --- a/gcc/config/mips/mips.cc
> +++ b/gcc/config/mips/mips.cc
> @@ -6082,7 +6082,8 @@ mips_function_arg (cumulative_args_t cum_v, const
> function_arg_info &arg)
> an ABI change. */
> if (DECL_FIELD_CXX_ZERO_WIDTH_BIT_FIELD (field))
> continue;
> - if (integer_zerop (DECL_SIZE (field)))
> + if (DECL_SIZE (field)
> + && integer_zerop (DECL_SIZE (field)))
> {
> zero_width_field_abi_change = true;
> continue;
> diff --git a/gcc/testsuite/gcc.target/mips/pr102024-4.c
> b/gcc/testsuite/gcc.target/mips/pr102024-4.c
> new file mode 100644
> index 00000000000..2147cc769d0
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/mips/pr102024-4.c
> @@ -0,0 +1,10 @@
> +// { dg-do compile }
> +// { dg-options "-mabi=64 -mhard-float" }
> +
> +struct __attribute__((aligned(16))) test {
> + int x[0];
> + double b;
> + int f[];
> +};
> +
> +void check(struct test) {} // { dg-message "the ABI for passing a value
> containing zero-width fields before an adjacent 64-bit floating-point field
> was changed in GCC 12.1" }
> --
> 2.35.1
>
Jakub
