https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96678
--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> --- At least for C, there is: <parm_decl 0x7ffff7633000 src type <pointer_type 0x7ffff74ea888 type <real_type 0x7ffff74ea348 double DF with the flag C_ARRAY_PARAMETER is set (to "1"). (For C++: DECL_ARRAY_PARAMETER_P.) Side note: * sizeof(Grid) → 800 * sizeof(src) → sizeof(double*) Thus, the size of Grid seems to be lost by going to a function argument.