re PR fortran/56937 (Unnecessarily temporary with array-vector assignments)

2013-07-21  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/56937
	* dependency.c (gfc_dep_resolver):  Treat identical
	array subscripts as identical; don't unconditionally
	return a dependency if an array subscript is found.

2013-07-21  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/56937
	* gfortran.dg/dependency_42.f90:  New test.
	* gfortran.dg/dependency_43.f90:  New test.

From-SVN: r201094

gcc/fortran/ChangeLog

+2013-07-21  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/56937
+	* dependency.c (gfc_dep_resolver):  Treat identical
+	array subscripts as identical; don't unconditionally
+	return a dependency if an array subscript is found.
+
 2013-07-21  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/35862

gcc/fortran/dependency.c

@@ -2095,11 +2095,23 @@ gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 
 	  for (n=0; n < lref->u.ar.dimen; n++)
 	    {
-	      /* Assume dependency when either of array reference is vector
-		 subscript.  */
+	      /* Handle dependency when either of array reference is vector
+		 subscript. There is no dependency if the vector indices
+		 are equal or if indices are known to be different in a
+		 different dimension.  */
 	      if (lref->u.ar.dimen_type[n] == DIMEN_VECTOR
 		  || rref->u.ar.dimen_type[n] == DIMEN_VECTOR)
-		return 1;
+		{
+		  if (lref->u.ar.dimen_type[n] == DIMEN_VECTOR 
+		      && rref->u.ar.dimen_type[n] == DIMEN_VECTOR
+		      && gfc_dep_compare_expr (lref->u.ar.start[n],
+					       rref->u.ar.start[n]) == 0)
+		    this_dep = GFC_DEP_EQUAL;
+		  else
+		    this_dep = GFC_DEP_OVERLAP;
+
+		  goto update_fin_dep;
+		}
 
 	      if (lref->u.ar.dimen_type[n] == DIMEN_RANGE
 		  && rref->u.ar.dimen_type[n] == DIMEN_RANGE)
@@ -2164,6 +2176,8 @@ gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 
 	      /* Overlap codes are in order of priority.  We only need to
 		 know the worst one.*/
+
+	    update_fin_dep:
 	      if (this_dep > fin_dep)
 		fin_dep = this_dep;
 	    }

gcc/testsuite/ChangeLog

+2013-07-21  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/56937
+	* gfortran.dg/dependency_42.f90:  New test.
+	* gfortran.dg/dependency_43.f90:  New test.
+
 2013-07-21  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/35862

gcc/testsuite/gfortran.dg/dependency_42.f90

+! { dg-do run }
+! { dg-options "-Warray-temporaries" }
+! PR fortran/56937 - unnecessary temporaries with vector indices
+program main
+  real :: q(4), r(4), p(3)
+  integer :: idx(3)
+  p = [0.5, 1.0, 2.0]
+  idx = [4,3,1]
+  r = 1.0
+  r(idx) = r(idx) + p
+  q = 1.0
+  q(4) = q(4) + p(1)
+  q(3) = q(3) + p(2)
+  q(1) = q(1) + p(3)
+  if (any (q - r /= 0)) call abort
+end

gcc/testsuite/gfortran.dg/dependency_43.f90

+! { dg-do run }
+! { dg-options "-Warray-temporaries" }
+! PR fortran/56937 - unnecessary temporaries with vector indices
+program main
+  integer, dimension(3) :: i1, i2
+  real :: a(3,2)
+
+  data a / 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 /
+  i1 = [ 1, 2, 3 ]
+  i2 = [ 3, 2, 1 ]
+  a (i1,1) = a (i2,2)
+  if (a(1,1) /= 6.0 .or. a(2,1) /= 5.0 .or. a(3,1) /= 4.0) call abort
+  if (a(1,2) /= 4.0 .or. a(2,2) /= 5.0 .or. a(3,2) /= 6.0) call abort
+end program main