http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52176
--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-02-09
17:02:36 UTC ---
gfortran generates the following code (original dump). I think, it's
if ((real(kind=4)[0:] * restrict) __result->data == 0B) goto L.17;
L.17:;
D.2061 = __result->dim[0].ubound - __result->dim[0].lbound >= 0
? (__result->dim[0].ubound - __result->dim[0].lbound) + 1 : 0;
D.2062 = D.2061 != 2;
if ((real(kind=4)[0:] * restrict) __result->data == 0B)
...
else
if (D.2062)
where those equations are not used in an "if", if result->data == NULL.
However, in the optimized dump, one finds:
[air.F90 : 82:0] prephitmp.78_7 = [air.F90 : 82] __result_6(D)->data;
[air.F90 : 82:0] if (prephitmp.78_7 == 0B)
goto <bb 3>;
<bb 3>:
prephitmp.77_85 = __result_6(D)->dim[0].ubound;
[air.F90 : 82:0] D.2085_25 = prephitmp.77_79 - D.2057_9;
[air.F90 : 82:0] if (D.2085_25 >= 0)
...
[air.F90 : 82:0] if (prephitmp.78_7 == 0B)
goto <bb 8>;
else
goto <bb 9>;
Thus, the bounds are always accessed in the "if", even if the result->data ==
NULL. However, in terms of the result, it does not seem to matter as far as I
could see.
However, I think the issue above is not related to the warning I see. valgrind
can only track uninitialized variables which have been allocated ("malloc") but
in this case "result" is a local variable, which should be stack allocated.
>From the callee (state_vector, atmosphere.F90:187):
real ,dimension(:) ,allocatable :: x
x = this%air_puppet%coordinate()
I think one should see such a valgrind error for allocatable components of
allocatable/pointer derived types as then also "<var>.dim" is malloc'ed.
If my analysis is correct, I do not see why valgrind warns. Nor do I understand
the reordering of the middle end. But at least the case above looks as if it's
not a wrong-code issue.
