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check.c (gfc_check_move_alloc): Prevent error that avoids aliasing between to and from arguments from rejecting... 

2016-11-09  Paul Thomas  <pault@gcc.gnu.org>

	* check.c (gfc_check_move_alloc): Prevent error that avoids
	aliasing between to and from arguments from rejecting valid
	code.

2016-11-09  Paul Thomas  <pault@gcc.gnu.org>

	* gfortran.dg/move_alloc_18.f90: New test.

From-SVN: r241995
This commit is contained in:
Paul Thomas 2016-11-09 10:10:41 +00:00
parent e15861c2da
commit bfcb501d83
4 changed files with 67 additions and 6 deletions
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6
gcc/fortran/ChangeLog
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@ -1,3 +1,9 @@
2016-11-09 Paul Thomas <pault@gcc.gnu.org>
* check.c (gfc_check_move_alloc): Prevent error that avoids
aliasing between to and from arguments from rejecting valid
code.
2016-11-09 Janus Weil <janus@gcc.gnu.org>
PR fortran/71894

42
gcc/fortran/check.c
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@ -3342,14 +3342,44 @@ gfc_check_move_alloc (gfc_expr *from, gfc_expr *to)
return false;
}
/* F2003 12.4.1.7 */
if (to->expr_type == EXPR_VARIABLE && from->expr_type ==EXPR_VARIABLE
/* This is based losely on F2003 12.4.1.7. It is intended to prevent
the likes of to = sym->cmp1->cmp2 and from = sym->cmp1, where cmp1
and cmp2 are allocatable. After the allocation is transferred,
the 'to' chain is broken by the nullification of the 'from'. A bit
of reflection reveals that this can only occur for derived types
with recursive allocatable components. */
if (to->expr_type == EXPR_VARIABLE && from->expr_type == EXPR_VARIABLE
&& !strcmp (to->symtree->n.sym->name, from->symtree->n.sym->name))
{
gfc_error ("The FROM and TO arguments at %L are either the same object "
"or subobjects thereof and so violate aliasing restrictions "
"(F2003 12.4.1.7)", &to->where);
return false;
gfc_ref *to_ref, *from_ref;
to_ref = to->ref;
from_ref = from->ref;
bool aliasing = true;
for (; from_ref && to_ref;
from_ref = from_ref->next, to_ref = to_ref->next)
{
if (to_ref->type != from->ref->type)
aliasing = false;
else if (to_ref->type == REF_ARRAY
&& to_ref->u.ar.type != AR_FULL
&& from_ref->u.ar.type != AR_FULL)
/* Play safe; assume sections and elements are different. */
aliasing = false;
else if (to_ref->type == REF_COMPONENT
&& to_ref->u.c.component != from_ref->u.c.component)
aliasing = false;
if (!aliasing)
break;
}
if (aliasing)
{
gfc_error ("The FROM and TO arguments at %L violate aliasing "
"restrictions (F2003 12.4.1.7)", &to->where);
return false;
}
}
/* CLASS arguments: Make sure the vtab of from is present. */

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2016-11-09 Paul Thomas <pault@gcc.gnu.org>
* gfortran.dg/move_alloc_18.f90: New test.
2016-11-09 Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>
PR middle-end/78256

21
gcc/testsuite/gfortran.dg/move_alloc_18.f90 Normal file
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@ -0,0 +1,21 @@
! { dg-do compile }
!
! Test that the anti-aliasing restriction does not knock out valid code.
!
! Contributed by Andrew Balwin on
! https://groups.google.com/forum/#!topic/comp.lang.fortran/oiXdl1LPb_s
!
PROGRAM TEST
IMPLICIT NONE
TYPE FOOBAR
INTEGER, ALLOCATABLE :: COMP(:)
END TYPE
TYPE (FOOBAR) :: MY_ARRAY(6)
ALLOCATE (MY_ARRAY(1)%COMP(10))
CALL MOVE_ALLOC (MY_ARRAY(1)%COMP, MY_ARRAY(2)%COMP)
END PROGRAM TEST