First: I have another rather simple patch, which still needs to be
reviewed: http://gcc.gnu.org/ml/fortran/2012-05/msg00086.html
* * *
When a realloc on assignment is done, gfortran first obtains the
descriptor by calling realloc_lhs_loop_for_fcn_call and then does the
actual function call using gfc_conv_function_expr.
However, realloc_lhs_loop_for_fcn_call already causes that the RHS is
evaluated (via gfc_add_loop_ss_code). The double evaluation of an inner
function call, causes memory leaks - and double evaluation
(correctness/performance issue).
The following code solves the issue. I am not 100% sure that it
correctly does so, but it solved the problem and the testsuite passed.
(It might obsolete the check in "se->direct_byref" of
gfc_conv_procedure_call.)
The test case is a bit pointless as it will only fail if one uses
valgrind on it; thus, one could consider committing the patch even
without. However, it might not harm to have it in the test suite.
Build and regtested on x86-64-linux.
OK for the trunk and 4.6/4.7?
Tobias
2012-05-21 Tobias Burnus <bur...@net-b.de>
PR fortran/53389
* trans-array.c (gfc_add_loop_ss_code): Don't evaluate expression, if
ss->is_alloc_lhs is set.
2012-05-21 Tobias Burnus <bur...@net-b.de>
PR fortran/53389
* gfortran.dg/realloc_on_assign_15.f90: New.
diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index b24d1c3..02bb38d 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -2401,6 +2401,11 @@ gfc_add_loop_ss_code (gfc_loopinfo * loop, gfc_ss * ss, bool subscript,
bool skip_nested = false;
int n;
+ /* Don't evaluate the arguments for realloc_lhs_loop_for_fcn_call; otherwise,
+ arguments could get evaluated multiple times. */
+ if (ss->is_alloc_lhs)
+ return;
+
outer_loop = outermost_loop (loop);
/* TODO: This can generate bad code if there are ordering dependencies,
--- /dev/null 2012-05-21 07:36:22.011729607 +0200
+++ gcc/gcc/testsuite/gfortran.dg/realloc_on_assign_15.f90 2012-05-21 18:18:59.000000000 +0200
@@ -0,0 +1,40 @@
+! { dg-do run }
+!
+! PR fortran/53389
+!
+! The program was leaking memory before due to
+! realloc on assignment and nested functions.
+!
+module foo
+ implicit none
+ contains
+
+ function filler(array, val)
+ real, dimension(:), intent(in):: array
+ real, dimension(size(array)):: filler
+ real, intent(in):: val
+
+ filler=val
+
+ end function filler
+end module
+
+program test
+ use foo
+ implicit none
+
+ real, dimension(:), allocatable:: x, y
+ integer, parameter:: N=1000 !*1000
+ integer:: i
+
+! allocate( x(N) )
+ allocate( y(N) )
+ y=0.0
+
+ do i=1, N
+! print *,i
+ x=filler(filler(y, real(2*i)), real(i))
+ y=y+x
+ end do
+
+end program test
