Use const-ref instead of values for sese_l passed to functions.

diff --git a/gcc/graphite-sese-to-poly.c b/gcc/graphite-sese-to-poly.c
index 7992c28..a7fd5d9 100644
--- a/gcc/graphite-sese-to-poly.c
+++ b/gcc/graphite-sese-to-poly.c
@@ -465,7 +465,7 @@  build_loop_iteration_domains (scop_p scop, struct loop *loop,
 {
 
   tree nb_iters = number_of_latch_executions (loop);
-  sese_l region = scop->scop_info->region;
+  const sese_l& region = scop->scop_info->region;
   gcc_assert (loop_in_sese_p (loop, region));
 
   isl_set *inner = isl_set_copy (outer);
diff --git a/gcc/sese.c b/gcc/sese.c
index 74dc4ac..b0f54de 100644
--- a/gcc/sese.c
+++ b/gcc/sese.c
@@ -523,7 +523,7 @@  set_ifsese_condition (ifsese if_region, tree condition)
    when T depends on memory that may change in REGION.  */
 
 bool
-invariant_in_sese_p_rec (tree t, sese_l &region, bool *has_vdefs)
+invariant_in_sese_p_rec (tree t, const sese_l &region, bool *has_vdefs)
 {
   if (!defined_in_sese_p (t, region))
     return true;
@@ -596,7 +596,7 @@  scev_analyzable_p (tree def, sese_l &region)
    is not defined in the REGION is considered a parameter.  */
 
 tree
-scalar_evolution_in_region (sese_l &region, loop_p loop, tree t)
+scalar_evolution_in_region (const sese_l &region, loop_p loop, tree t)
 {
   gimple *def;
   struct loop *def_loop;
diff --git a/gcc/sese.h b/gcc/sese.h
index 626a077..99df354 100644
--- a/gcc/sese.h
+++ b/gcc/sese.h
@@ -109,9 +109,9 @@  extern void free_sese_info (sese_info_p);
 extern void sese_insert_phis_for_liveouts (sese_info_p, basic_block, edge, edge);
 extern void build_sese_loop_nests (sese_info_p);
 extern struct loop *outermost_loop_in_sese (sese_l &, basic_block);
-extern tree scalar_evolution_in_region (sese_l &, loop_p, tree);
+extern tree scalar_evolution_in_region (const sese_l &, loop_p, tree);
 extern bool scev_analyzable_p (tree, sese_l &);
-extern bool invariant_in_sese_p_rec (tree, sese_l &, bool *);
+extern bool invariant_in_sese_p_rec (tree, const sese_l &, bool *);
 
 /* Check that SESE contains LOOP.  */
 
@@ -133,7 +133,7 @@  sese_nb_params (sese_info_p region)
    EXIT blocks.  */
 
 static inline bool
-bb_in_region (basic_block bb, basic_block entry, basic_block exit)
+bb_in_region (const_basic_block bb, const_basic_block entry, const_basic_block exit)
 {
   /* FIXME: PR67842.  */
 #if 0
@@ -158,7 +158,7 @@  bb_in_region (basic_block bb, basic_block entry, basic_block exit)
    EXIT blocks.  */
 
 static inline bool
-bb_in_sese_p (basic_block bb, sese_l &r)
+bb_in_sese_p (basic_block bb, const sese_l &r)
 {
   return bb_in_region (bb, r.entry->dest, r.exit->dest);
 }
@@ -166,7 +166,7 @@  bb_in_sese_p (basic_block bb, sese_l &r)
 /* Returns true when STMT is defined in REGION.  */
 
 static inline bool
-stmt_in_sese_p (gimple *stmt, sese_l &r)
+stmt_in_sese_p (gimple *stmt, const sese_l &r)
 {
   basic_block bb = gimple_bb (stmt);
   return bb && bb_in_sese_p (bb, r);
@@ -175,7 +175,7 @@  stmt_in_sese_p (gimple *stmt, sese_l &r)
 /* Returns true when NAME is defined in REGION.  */
 
 static inline bool
-defined_in_sese_p (tree name, sese_l &r)
+defined_in_sese_p (tree name, const sese_l &r)
 {
   return stmt_in_sese_p (SSA_NAME_DEF_STMT (name), r);
 }
@@ -183,7 +183,7 @@  defined_in_sese_p (tree name, sese_l &r)
 /* Returns true when LOOP is in REGION.  */
 
 static inline bool
-loop_in_sese_p (struct loop *loop, sese_l &region)
+loop_in_sese_p (struct loop *loop, const sese_l &region)
 {
   return (bb_in_sese_p (loop->header, region)
 	  && bb_in_sese_p (loop->latch, region));