https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93524
Bug ID: 93524
Summary: [ISO C Binding][F2018] CFI_allocate – elem_size
mishandled + sm wrongly set?
Product: gcc
Version: unknown
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
Target Milestone: ---
CFI_cdesc_t structure type has:
size_t elem_len;
If the object is scalar, the value is the storage size in bytes of the
object;
otherwise, the value20is the storage size in bytes of an element of the
object.
CFI_establish has:
elem_len
If type is equal to CFI_type_struct, CFI_type_other, or a Fortran character
type
code, elem_len shall be greater than zero and equal to the storage size in
bytes
of an element of the object. Otherwise, elem_len will be ignored.
(Similarly: CFI_allocate and CFI_select_part, although they only have character
and not other/struct.)
EXPECTED:
1. For establish/allocate/select_part, the elem_len is handled properly.
(Check all three, the testcase only uses the first two.)
2. The CFI_allocate + CFI_contiguous work nice together.
Regarding 1: Is seems as if establish handles it correctly but allocate
fails if it's argument is elem_len = 0 – even if the descriptor has the
proper elem_len = 4.
Regaring 2: Currently, is_contiguous is 0 because:
{base_addr = 0x408910, elem_len = 4, version = 1, rank = 3, attribute =
1,
type = 1027,
dim = {{lower_bound = -10, extent = 21, sm = 4},
{lower_bound = 0, extent = 6, sm = 84},
{lower_bound = 3, extent = 8, sm = 24}}}
Here, the contiguous check works fine for dim=0 as sm=4 == elem_len.
It also works for dim=1 as sm[1]=84 == sm[0]=4 * extent[0]=21 => 84 == 84
But for dim=2, sm[2]=24 != sm[1]=84 * extent[1]=6 => 24 != 504
That looks like a bug in allocate – but I might have also misunderstood
something in is_contiguous.
Test case; note the bounds of the second Fortran function are wrong because
PR 92189
==> hello_world.c <==
#include <stdlib.h> // For size_t
#include <ISO_Fortran_binding.h>
void my_fortran_sub_1 (CFI_cdesc_t *dv);
void my_fortran_sub_2 (CFI_cdesc_t *dv);
int main ()
{
CFI_CDESC_T (3) a;
CFI_cdesc_t *dv = (CFI_cdesc_t *) &a;
// dv, base_addr, attribute, type, elem_len, rank,
extents
CFI_establish (dv, NULL, CFI_attribute_allocatable, CFI_type_float, 0, 3,
NULL);
if (dv->base_addr != NULL)
return 1; // shall not be allocated
CFI_index_t lower_bounds[] = {-10, 0, 3};
CFI_index_t upper_bounds[] = {10, 5, 10};
size_t elem_len = 0; // only needed for strings
if (CFI_SUCCESS != CFI_allocate (dv, lower_bounds, upper_bounds, elem_len))
return 2;
if (!CFI_is_contiguous (dv))
return 2; // allocatables shall be contiguous,unless a strided section is
used
my_fortran_sub_1 (dv);
my_fortran_sub_2 (dv);
CFI_deallocate (dv);
return 0;
}
==> hello_world.f90 <==
subroutine my_fortran_sub_1 (A) bind(C)
real :: A(:, :, :)
print *, 'Lower bounds: ', lbound(A) ! Lower bounds: 1 1 1
print *, 'Upper bounds: ', ubound(A) ! Upper bounds: 21 6 8
end
subroutine my_fortran_sub_2 (A) bind(C)
real, ALLOCATABLE :: A(:, :, :)
print *, 'Lower bounds: ', lbound(A)
print *, 'Upper bounds: ', ubound(A)
end subroutine my_fortran_sub_2
