While playing with -Warray-temporaries, I noticed that the warning is emitted
twice for RESHAPE as illustrated by the following example:
[macbook] f90/bug% cat pr36928_red.f90
! { dg-do compile }
! { dg-options "-Warray-temporaries" }
! PR 36928 - optimize array interleaving array temporaries
program main
integer :: i, m, n
real, dimension(4,5) :: b
real, dimension(5,4) :: c
b = reshape([(i, i=1,20)],[4,5])
m = 5
n = 4
c = reshape(b, [m,n])
end program main
[macbook] f90/bug% gfc -Warray-temporaries pr36928_red.f90
pr36928_red.f90:11.17:
c = reshape(b, [m,n])
1
Warning: Creating array temporary at (1)
pr36928_red.f90:11.17:
c = reshape(b, [m,n])
1
Warning: Creating array temporary at (1)
(see the polyhedron test capacita.f90 for "real life" code). If I read
correctly the dump
...
atmp.3.dtype = 265;
atmp.3.dim[0].stride = 1;
atmp.3.dim[0].lbound = 0;
atmp.3.dim[0].ubound = 1;
atmp.3.data = (void * restrict) &A.4;
atmp.3.offset = 0;
(*(integer(kind=4)[2] * restrict) atmp.3.data)[0] = m;
(*(integer(kind=4)[2] * restrict) atmp.3.data)[1] = n;
atmp.6.dtype = 521;
atmp.6.dim[0].stride = 1;
atmp.6.dim[0].lbound = 0;
atmp.6.dim[0].ubound = 1;
atmp.6.data = (void * restrict) &A.7;
atmp.6.offset = 0;
{
integer(kind=8) S.8;
S.8 = 0;
while (1)
{
if (S.8 > 1) goto L.1;
(*(integer(kind=8)[2] * restrict) atmp.6.data)[S.8] =
(integer(kind=8)) (*(integer(kind=4)[2] * restrict) atmp.3.data)[S.8];
S.8 = S.8 + 1;
}
L.1:;
}
_gfortran_reshape_r4 (&parm.1, &parm.2, &atmp.6, 0B, 0B);
}
}
}
there are two temporaries atmp.3 and atmp.6, and I don't see any reason why the
second one should be needed (all the arguments are INTENT(IN), isn't it?).
--
Summary: Useless temporary with RESHAPE
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dominiq at lps dot ens dot fr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44442
