vectorizer: add _bb_vec_info::region_stmts and reverse_region_stmts

gcc/ChangeLog:

	* coretypes.h (struct iterator_range): New type.
	* tree-vect-patterns.c (vect_determine_precisions): Use
	range-based iterator.
	(vect_pattern_recog): Likewise.
	* tree-vect-slp.c (_bb_vec_info):  Likewise.
	(_bb_vec_info::~_bb_vec_info): Likewise.
	(vect_slp_check_for_constructors): Likewise.
	* tree-vectorizer.h:Add new iterators
	and functions that use it.

gcc/coretypes.h

@@ -363,6 +363,23 @@ struct kv_pair
 template<typename T1, typename T2>
 using first_type = T1;
 
+/* Iterator pair used for a collection iteration with range-based loops.  */
+
+template<typename T>
+struct iterator_range
+{
+public:
+  iterator_range (const T &begin, const T &end)
+    : m_begin (begin), m_end (end) {}
+
+  T begin () const { return m_begin; }
+  T end () const { return m_end; }
+
+private:
+  T m_begin;
+  T m_end;
+};
+
 #else
 
 struct _dont_use_rtx_here_;

gcc/tree-vect-patterns.c

@@ -5120,20 +5120,12 @@ vect_determine_precisions (vec_info *vinfo)
   else
     {
       bb_vec_info bb_vinfo = as_a <bb_vec_info> (vinfo);
-      gimple_stmt_iterator si = bb_vinfo->region_end;
-      gimple *stmt;
-      do
+      for (gimple *stmt : bb_vinfo->reverse_region_stmts ())
 	{
-	  if (!gsi_stmt (si))
-	    si = gsi_last_bb (bb_vinfo->bb);
-	  else
-	    gsi_prev (&si);
-	  stmt = gsi_stmt (si);
 	  stmt_vec_info stmt_info = vinfo->lookup_stmt (stmt);
 	  if (stmt_info && STMT_VINFO_VECTORIZABLE (stmt_info))
 	    vect_determine_stmt_precisions (vinfo, stmt_info);
 	}
-      while (stmt != gsi_stmt (bb_vinfo->region_begin));
     }
 }
 
@@ -5492,10 +5484,8 @@ vect_pattern_recog (vec_info *vinfo)
   else
     {
       bb_vec_info bb_vinfo = as_a <bb_vec_info> (vinfo);
-      for (si = bb_vinfo->region_begin;
-	   gsi_stmt (si) != gsi_stmt (bb_vinfo->region_end); gsi_next (&si))
+      for (gimple *stmt : bb_vinfo->region_stmts ())
 	{
-	  gimple *stmt = gsi_stmt (si);
 	  stmt_vec_info stmt_info = bb_vinfo->lookup_stmt (stmt);
 	  if (!stmt_info || !STMT_VINFO_VECTORIZABLE (stmt_info))
 	    continue;

gcc/tree-vect-slp.c

@@ -2588,12 +2588,8 @@ _bb_vec_info::_bb_vec_info (gimple_stmt_iterator region_begin_in,
     region_begin (region_begin_in),
     region_end (region_end_in)
 {
-  gimple_stmt_iterator gsi;
-
-  for (gsi = region_begin; gsi_stmt (gsi) != gsi_stmt (region_end);
-       gsi_next (&gsi))
+  for (gimple *stmt : this->region_stmts ())
     {
-      gimple *stmt = gsi_stmt (gsi);
       gimple_set_uid (stmt, 0);
       if (is_gimple_debug (stmt))
 	continue;
@@ -2609,10 +2605,9 @@ _bb_vec_info::_bb_vec_info (gimple_stmt_iterator region_begin_in,
 
 _bb_vec_info::~_bb_vec_info ()
 {
-  for (gimple_stmt_iterator si = region_begin;
-       gsi_stmt (si) != gsi_stmt (region_end); gsi_next (&si))
+  for (gimple *stmt : this->region_stmts ())
     /* Reset region marker.  */
-    gimple_set_uid (gsi_stmt (si), -1);
+    gimple_set_uid (stmt, -1);
 
   bb->aux = NULL;
 }
@@ -3050,16 +3045,13 @@ vect_bb_vectorization_profitable_p (bb_vec_info bb_vinfo)
 static void
 vect_slp_check_for_constructors (bb_vec_info bb_vinfo)
 {
-  gimple_stmt_iterator gsi;
-
-  for (gsi = bb_vinfo->region_begin;
-       gsi_stmt (gsi) != gsi_stmt (bb_vinfo->region_end); gsi_next (&gsi))
+  for (gimple *stmt : bb_vinfo->region_stmts ())
     {
-      gassign *stmt = dyn_cast <gassign *> (gsi_stmt (gsi));
-      if (!stmt || gimple_assign_rhs_code (stmt) != CONSTRUCTOR)
+      gassign *assign = dyn_cast<gassign *> (stmt);
+      if (!assign || gimple_assign_rhs_code (assign) != CONSTRUCTOR)
 	continue;
 
-      tree rhs = gimple_assign_rhs1 (stmt);
+      tree rhs = gimple_assign_rhs1 (assign);
       if (!VECTOR_TYPE_P (TREE_TYPE (rhs))
 	  || maybe_ne (TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs)),
 		       CONSTRUCTOR_NELTS (rhs))
@@ -3067,7 +3059,7 @@ vect_slp_check_for_constructors (bb_vec_info bb_vinfo)
 	  || uniform_vector_p (rhs))
 	continue;
 
-      stmt_vec_info stmt_info = bb_vinfo->lookup_stmt (stmt);
+      stmt_vec_info stmt_info = bb_vinfo->lookup_stmt (assign);
       BB_VINFO_GROUPED_STORES (bb_vinfo).safe_push (stmt_info);
     }
 }

gcc/tree-vectorizer.h

@@ -792,9 +792,91 @@ loop_vec_info_for_loop (class loop *loop)
 typedef class _bb_vec_info : public vec_info
 {
 public:
+
+  /* GIMPLE statement iterator going from region_begin to region_end.  */
+
+  struct const_iterator
+  {
+    const_iterator (gimple_stmt_iterator _gsi) : gsi (_gsi) {}
+
+    const const_iterator &
+    operator++ ()
+    {
+      gsi_next (&gsi); return *this;
+    }
+
+    gimple *operator* () const { return gsi_stmt (gsi); }
+
+    bool
+    operator== (const const_iterator &other) const
+    {
+      return gsi_stmt (gsi) == gsi_stmt (other.gsi);
+    }
+
+    bool
+    operator!= (const const_iterator &other) const
+    {
+      return !(*this == other);
+    }
+
+    gimple_stmt_iterator gsi;
+  };
+
+  /* GIMPLE statement iterator going from region_end to region_begin.  */
+
+  struct const_reverse_iterator
+  {
+    const_reverse_iterator (gimple_stmt_iterator _gsi) : gsi (_gsi) {}
+
+    const const_reverse_iterator &
+    operator++ ()
+    {
+      gsi_prev (&gsi); return *this;
+    }
+
+    gimple *operator* () const { return gsi_stmt (gsi); }
+
+    bool
+    operator== (const const_reverse_iterator &other) const
+    {
+      return gsi_stmt (gsi) == gsi_stmt (other.gsi);
+    }
+
+    bool
+    operator!= (const const_reverse_iterator &other) const
+    {
+      return !(*this == other);
+    }
+
+    gimple_stmt_iterator gsi;
+  };
+
   _bb_vec_info (gimple_stmt_iterator, gimple_stmt_iterator, vec_info_shared *);
   ~_bb_vec_info ();
 
+  /* Returns iterator_range for range-based loop.  */
+
+  iterator_range<const_iterator>
+  region_stmts ()
+  {
+    return iterator_range<const_iterator> (region_begin, region_end);
+  }
+
+  /* Returns iterator_range for range-based loop in a reverse order.  */
+
+  iterator_range<const_reverse_iterator>
+  reverse_region_stmts ()
+  {
+    const_reverse_iterator begin = region_end;
+    if (*begin == NULL)
+      begin = const_reverse_iterator (gsi_last_bb (region_end.bb));
+    else
+      ++begin;
+
+    const_reverse_iterator end = region_begin;
+    return iterator_range<const_reverse_iterator> (begin, ++end);
+  }
+
   basic_block bb;
   gimple_stmt_iterator region_begin;
   gimple_stmt_iterator region_end;