diff --git a/gcc/graphite-dependences.c b/gcc/graphite-dependences.c
index b0f8680..f382233 100644
--- a/gcc/graphite-dependences.c
+++ b/gcc/graphite-dependences.c
@@ -426,22 +426,48 @@ subtract_commutative_associative_deps (scop_p scop,
 
 	*must_raw = isl_union_map_subtract (*must_raw, x_must_raw);
 	*may_raw = isl_union_map_subtract (*may_raw, x_may_raw);
-	*must_raw_no_source = isl_union_map_subtract (*must_raw_no_source,
-						      x_must_raw_no_source);
-	*may_raw_no_source = isl_union_map_subtract (*may_raw_no_source,
-						     x_may_raw_no_source);
+
+	if (must_raw_no_source)
+	  *must_raw_no_source = isl_union_map_subtract (*must_raw_no_source,
+						          x_must_raw_no_source);
+	else
+	  isl_union_map_free (x_must_raw_no_source);
+
+	if (may_raw_no_source)
+	  *may_raw_no_source = isl_union_map_subtract (*may_raw_no_source,
+						         x_may_raw_no_source);
+	else
+	  isl_union_map_free (x_may_raw_no_source);
+
 	*must_war = isl_union_map_subtract (*must_war, x_must_war);
 	*may_war = isl_union_map_subtract (*may_war, x_may_war);
-	*must_war_no_source = isl_union_map_subtract (*must_war_no_source,
-						      x_must_war_no_source);
-	*may_war_no_source = isl_union_map_subtract (*may_war_no_source,
-						     x_may_war_no_source);
+
+	if (must_war_no_source)
+	  *must_war_no_source = isl_union_map_subtract (*must_war_no_source,
+						          x_must_war_no_source);
+	else
+	  isl_union_map_free (x_must_war_no_source);
+
+	if (may_war_no_source)
+	  *may_war_no_source = isl_union_map_subtract (*may_war_no_source,
+						         x_may_war_no_source);
+	else
+	  isl_union_map_free (x_may_war_no_source);
+
 	*must_waw = isl_union_map_subtract (*must_waw, x_must_waw);
 	*may_waw = isl_union_map_subtract (*may_waw, x_may_waw);
-	*must_waw_no_source = isl_union_map_subtract (*must_waw_no_source,
-						      x_must_waw_no_source);
-	*may_waw_no_source = isl_union_map_subtract (*may_waw_no_source,
-						     x_may_waw_no_source);
+
+	if (must_waw_no_source)
+	  *must_waw_no_source = isl_union_map_subtract (*must_waw_no_source,
+						          x_must_waw_no_source);
+	else
+	  isl_union_map_free (x_must_waw_no_source);
+
+	if (may_waw_no_source)
+	  *may_waw_no_source = isl_union_map_subtract (*may_waw_no_source,
+						         x_may_waw_no_source);
+	else
+	  isl_union_map_free (x_may_waw_no_source);
       }
 
   isl_union_map_free (original);
diff --git a/gcc/testsuite/gfortran.dg/graphite/pr59586.f b/gcc/testsuite/gfortran.dg/graphite/pr59586.f
new file mode 100644
index 0000000..f33a1b1
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/graphite/pr59586.f
@@ -0,0 +1,11 @@
+! { dg-additional-options "-Ofast -floop-parallelize-all" }
+
+      subroutine subsm ( n, x, xp, xx)
+      integer        n, m, x(n),xp(n), xx(n), gg(n), dd_p
+      do 55 i=1, n
+         dd_p  = dd_p + (x(i) - xx(i))*gg(i)
+ 55   continue
+      if ( dd_p .gt. 0  ) then
+         call dcopy( n, xp, 1, x, 1 )
+      endif
+      end