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[Bug fortran/32298] MINLOC / MAXLOC: off-by one for PARAMETER arrays
- From: "dfranke at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 16 Jun 2007 14:00:03 -0000
- Subject: [Bug fortran/32298] MINLOC / MAXLOC: off-by one for PARAMETER arrays
- References: <bug-32298-14685@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #2 from dfranke at gcc dot gnu dot org 2007-06-16 14:00 -------
A simplified testcase:
$> cat pr32298.f90
PROGRAM ERR_MINLOC
INTEGER, PARAMETER :: N = 7
DOUBLE PRECISION, DIMENSION (N), PARAMETER :: A &
= (/ 0.3D0, 0.455D0, 0.6D0, 0.7D0, 0.72D0, 0.76D0, 0.79D0 /)
INTEGER :: I, K
I = 7
K = MAXLOC (ABS (A - A(I)), 1)
PRINT *, I, K
END PROGRAM ERR_MINLOC
$> gfortran-svn -fdump-tree-original pr32298.f90
$> cat pr32298.f90.003t.original
[...]
pos.0 = 0;
{
int4 S.3;
S.3 = 0;
while (1)
{
if (S.3 > 6) goto L.1;
if (ABS_EXPR <A.2[S.3] - D.1011> > limit.1 || pos.0 == 0)
{
limit.1 = ABS_EXPR <A.2[S.3] - D.1011>;
pos.0 = S.3;
}
S.3 = S.3 + 1;
}
L.1:;
}
k = pos.0 + 1;
}
Variable pos.0 starts at 0 and thus triggers the right part of the or-clause
within the if-statement. Hence, it gets assigned the value of S.3, which
happens to be 0 within the first iteration. Within the second iteration of the
while, pos.0 still equals 0 which triggers the if-statement again - pos.0 will
now be set to 1 as S.3 was increased during the last iteration. At the end, K
ist set to pos.0 + 1, which (wrongly) equals 2 in this case.
Someone who intimiately knows the scalarizer should be able to fix this
easily?!
> (This might also affect MAXVAL/MINVAL, though I did not manage to cook
> up an example.)
I don't think so as MINVAL/MAXVAL do not track the respective positions.
--
dfranke at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dfranke at gcc dot gnu dot
| |org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32298