https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66459
Thomas Koenig <tkoenig at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2015-06-08 00:00:00 |2019-2-3
CC| |tkoenig at gcc dot gnu.org
Component|fortran |middle-end
--- Comment #4 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
The code that gfortran generates is correct, it is just that
the middle-end does not quite understand it and generates a
warning for it.
The -fdump-tree-original dump shows
if (*l)
{
{
[...]
w.dtype = {.elem_len=4, .rank=2, .type=1};
D.3881 = (integer(kind=8)) MAX_EXPR <*m, 0>;
D.3882 = NON_LVALUE_EXPR <__builtin_expect ((integer(kind=8))
(D.3881 == 0), 0, 46) ? 0 : __builtin_expect ((integer(kind=8))
(9223372036854775807 / D.3881 <= 0), 0, 41) ? 1 : 0>;
D.3883 = NON_LVALUE_EXPR <D.3881>;
D.3884 = (integer(kind=8)) MAX_EXPR <*n, 0>;
D.3885 = (__builtin_expect ((integer(kind=8)) (D.3884 == 0), 0, 46)
? 0 : __builtin_expect ((integer(kind=8)) (9223372036854775807 / D.3884 <
D.3883), 0, 41) ? 1 : 0) + D.3882;
D.3886 = D.3883 * D.3884;
D.3887 = D.3886;
D.3888 = (__builtin_expect ((integer(kind=8)) ((unsigned long)
D.3886 > 4611686018427387903), 0, 41) ? 1 : 0) + D.3885;
D.3889 = ~NON_LVALUE_EXPR <D.3883>;
if (D.3891)
{
size.0 = 0;
}
else
{
size.0 = (unsigned long) D.3886 * 4;
}
overflow.1 = D.3888;
if (__builtin_expect ((integer(kind=8)) (overflow.1 != 0), 0, 41))
{
_gfortran_runtime_error (&"Ganzzahl\xc3\xbcberlauf bei der
Berechnung des zu reservierenden Speichers"[1]{lb: 1 sz: 1});
}
else
{
if (__builtin_expect ((integer(kind=8)) (w.data != 0B), 0, 43))
{
_gfortran_runtime_error_at (&"At line 9 of file b.f"[1]{lb:
1 sz: 1}, &"Versuch, bereits reservierte Variable \xc2\xbb%s\xc2\xab zu
reservieren"[1]{lb: 1 sz: 1}, &"w"[1]{lb: 1 sz: 1});
}
else
{
w.data = (void * restrict) __builtin_malloc (MAX_EXPR
<size.0, 1>);
if (__builtin_expect ((integer(kind=8)) (w.data == 0B), 0,
42))
{
_gfortran_os_error (&"Reservierung w\xc3\xbcrde
Speichergrenze \xc3\xbcberschreiten"[1]{lb: 1 sz: 1});
}
}
}
w.dim[0].lbound = 1;
w.dim[0].ubound = (integer(kind=8)) *m;
w.dim[0].stride = 1;
w.dim[1].lbound = 1;
w.dim[1].ubound = (integer(kind=8)) *n;
w.dim[1].stride = D.3883;
w.offset = D.3889;
}
}
and then
if ((integer(kind=4)[0:] * restrict) w.data != 0B)
{
(*(integer(kind=4)[0:] * restrict) w.data)[(w.offset
+ (integer(kind=8)) i * w.dim[1].stride) + (integer(kind=8)) j] = 0;
Now, the thing is that, on leaving the if (*l) block, data has to be non-zero,
otherwise _gfortran_os_error would have been called (which is marked
with TREE_THIS_VOLATILE, hence noreturn). So, the variables
Is there something the Fortran front end can do better? If not, I think
this is better classified as a middle-end bug.
