Initial checkin of GCC 4.9.0 from trunk (r208799).

Change-Id: I48a3c08bb98542aa215912a75f03c0890e497dba

1 files changed, 2447 insertions, 0 deletions

diff --git a/gcc-4.9/gcc/tree-vect-loop-manip.c b/gcc-4.9/gcc/tree-vect-loop-manip.c
new file mode 100644
index 000000000..77d945e6a
--- /dev/null
+++ b/gcc-4.9/gcc/tree-vect-loop-manip.c
@@ -0,0 +1,2447 @@
+/* Vectorizer Specific Loop Manipulations
+   Copyright (C) 2003-2014 Free Software Foundation, Inc.
+   Contributed by Dorit Naishlos <dorit@il.ibm.com>
+   and Ira Rosen <irar@il.ibm.com>
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "dumpfile.h"
+#include "tm.h"
+#include "tree.h"
+#include "basic-block.h"
+#include "gimple-pretty-print.h"
+#include "tree-ssa-alias.h"
+#include "internal-fn.h"
+#include "gimple-expr.h"
+#include "is-a.h"
+#include "gimple.h"
+#include "gimplify.h"
+#include "gimple-iterator.h"
+#include "gimplify-me.h"
+#include "gimple-ssa.h"
+#include "tree-cfg.h"
+#include "tree-phinodes.h"
+#include "ssa-iterators.h"
+#include "stringpool.h"
+#include "tree-ssanames.h"
+#include "tree-ssa-loop-manip.h"
+#include "tree-into-ssa.h"
+#include "tree-ssa.h"
+#include "tree-pass.h"
+#include "cfgloop.h"
+#include "diagnostic-core.h"
+#include "tree-scalar-evolution.h"
+#include "tree-vectorizer.h"
+#include "langhooks.h"
+
+/*************************************************************************
+  Simple Loop Peeling Utilities
+
+  Utilities to support loop peeling for vectorization purposes.
+ *************************************************************************/
+
+
+/* Renames the use *OP_P.  */
+
+static void
+rename_use_op (use_operand_p op_p)
+{
+  tree new_name;
+
+  if (TREE_CODE (USE_FROM_PTR (op_p)) != SSA_NAME)
+    return;
+
+  new_name = get_current_def (USE_FROM_PTR (op_p));
+
+  /* Something defined outside of the loop.  */
+  if (!new_name)
+    return;
+
+  /* An ordinary ssa name defined in the loop.  */
+
+  SET_USE (op_p, new_name);
+}
+
+
+/* Renames the variables in basic block BB.  */
+
+static void
+rename_variables_in_bb (basic_block bb)
+{
+  gimple_stmt_iterator gsi;
+  gimple stmt;
+  use_operand_p use_p;
+  ssa_op_iter iter;
+  edge e;
+  edge_iterator ei;
+  struct loop *loop = bb->loop_father;
+
+  for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      stmt = gsi_stmt (gsi);
+      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)
+	rename_use_op (use_p);
+    }
+
+  FOR_EACH_EDGE (e, ei, bb->preds)
+    {
+      if (!flow_bb_inside_loop_p (loop, e->src))
+	continue;
+      for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+        rename_use_op (PHI_ARG_DEF_PTR_FROM_EDGE (gsi_stmt (gsi), e));
+    }
+}
+
+
+typedef struct
+{
+  tree from, to;
+  basic_block bb;
+} adjust_info;
+
+/* A stack of values to be adjusted in debug stmts.  We have to
+   process them LIFO, so that the closest substitution applies.  If we
+   processed them FIFO, without the stack, we might substitute uses
+   with a PHI DEF that would soon become non-dominant, and when we got
+   to the suitable one, it wouldn't have anything to substitute any
+   more.  */
+static vec<adjust_info, va_heap> adjust_vec;
+
+/* Adjust any debug stmts that referenced AI->from values to use the
+   loop-closed AI->to, if the references are dominated by AI->bb and
+   not by the definition of AI->from.  */
+
+static void
+adjust_debug_stmts_now (adjust_info *ai)
+{
+  basic_block bbphi = ai->bb;
+  tree orig_def = ai->from;
+  tree new_def = ai->to;
+  imm_use_iterator imm_iter;
+  gimple stmt;
+  basic_block bbdef = gimple_bb (SSA_NAME_DEF_STMT (orig_def));
+
+  gcc_assert (dom_info_available_p (CDI_DOMINATORS));
+
+  /* Adjust any debug stmts that held onto non-loop-closed
+     references.  */
+  FOR_EACH_IMM_USE_STMT (stmt, imm_iter, orig_def)
+    {
+      use_operand_p use_p;
+      basic_block bbuse;
+
+      if (!is_gimple_debug (stmt))
+	continue;
+
+      gcc_assert (gimple_debug_bind_p (stmt));
+
+      bbuse = gimple_bb (stmt);
+
+      if ((bbuse == bbphi
+	   || dominated_by_p (CDI_DOMINATORS, bbuse, bbphi))
+	  && !(bbuse == bbdef
+	       || dominated_by_p (CDI_DOMINATORS, bbuse, bbdef)))
+	{
+	  if (new_def)
+	    FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
+	      SET_USE (use_p, new_def);
+	  else
+	    {
+	      gimple_debug_bind_reset_value (stmt);
+	      update_stmt (stmt);
+	    }
+	}
+    }
+}
+
+/* Adjust debug stmts as scheduled before.  */
+
+static void
+adjust_vec_debug_stmts (void)
+{
+  if (!MAY_HAVE_DEBUG_STMTS)
+    return;
+
+  gcc_assert (adjust_vec.exists ());
+
+  while (!adjust_vec.is_empty ())
+    {
+      adjust_debug_stmts_now (&adjust_vec.last ());
+      adjust_vec.pop ();
+    }
+
+  adjust_vec.release ();
+}
+
+/* Adjust any debug stmts that referenced FROM values to use the
+   loop-closed TO, if the references are dominated by BB and not by
+   the definition of FROM.  If adjust_vec is non-NULL, adjustments
+   will be postponed until adjust_vec_debug_stmts is called.  */
+
+static void
+adjust_debug_stmts (tree from, tree to, basic_block bb)
+{
+  adjust_info ai;
+
+  if (MAY_HAVE_DEBUG_STMTS
+      && TREE_CODE (from) == SSA_NAME
+      && ! SSA_NAME_IS_DEFAULT_DEF (from)
+      && ! virtual_operand_p (from))
+    {
+      ai.from = from;
+      ai.to = to;
+      ai.bb = bb;
+
+      if (adjust_vec.exists ())
+	adjust_vec.safe_push (ai);
+      else
+	adjust_debug_stmts_now (&ai);
+    }
+}
+
+/* Change E's phi arg in UPDATE_PHI to NEW_DEF, and record information
+   to adjust any debug stmts that referenced the old phi arg,
+   presumably non-loop-closed references left over from other
+   transformations.  */
+
+static void
+adjust_phi_and_debug_stmts (gimple update_phi, edge e, tree new_def)
+{
+  tree orig_def = PHI_ARG_DEF_FROM_EDGE (update_phi, e);
+
+  SET_PHI_ARG_DEF (update_phi, e->dest_idx, new_def);
+
+  if (MAY_HAVE_DEBUG_STMTS)
+    adjust_debug_stmts (orig_def, PHI_RESULT (update_phi),
+			gimple_bb (update_phi));
+}
+
+
+/* Update PHI nodes for a guard of the LOOP.
+
+   Input:
+   - LOOP, GUARD_EDGE: LOOP is a loop for which we added guard code that
+        controls whether LOOP is to be executed.  GUARD_EDGE is the edge that
+        originates from the guard-bb, skips LOOP and reaches the (unique) exit
+        bb of LOOP.  This loop-exit-bb is an empty bb with one successor.
+        We denote this bb NEW_MERGE_BB because before the guard code was added
+        it had a single predecessor (the LOOP header), and now it became a merge
+        point of two paths - the path that ends with the LOOP exit-edge, and
+        the path that ends with GUARD_EDGE.
+   - NEW_EXIT_BB: New basic block that is added by this function between LOOP
+        and NEW_MERGE_BB. It is used to place loop-closed-ssa-form exit-phis.
+
+   ===> The CFG before the guard-code was added:
+        LOOP_header_bb:
+          loop_body
+          if (exit_loop) goto update_bb
+          else           goto LOOP_header_bb
+        update_bb:
+
+   ==> The CFG after the guard-code was added:
+        guard_bb:
+          if (LOOP_guard_condition) goto new_merge_bb
+          else                      goto LOOP_header_bb
+        LOOP_header_bb:
+          loop_body
+          if (exit_loop_condition) goto new_merge_bb
+          else                     goto LOOP_header_bb
+        new_merge_bb:
+          goto update_bb
+        update_bb:
+
+   ==> The CFG after this function:
+        guard_bb:
+          if (LOOP_guard_condition) goto new_merge_bb
+          else                      goto LOOP_header_bb
+        LOOP_header_bb:
+          loop_body
+          if (exit_loop_condition) goto new_exit_bb
+          else                     goto LOOP_header_bb
+        new_exit_bb:
+        new_merge_bb:
+          goto update_bb
+        update_bb:
+
+   This function:
+   1. creates and updates the relevant phi nodes to account for the new
+      incoming edge (GUARD_EDGE) into NEW_MERGE_BB. This involves:
+      1.1. Create phi nodes at NEW_MERGE_BB.
+      1.2. Update the phi nodes at the successor of NEW_MERGE_BB (denoted
+           UPDATE_BB).  UPDATE_BB was the exit-bb of LOOP before NEW_MERGE_BB
+   2. preserves loop-closed-ssa-form by creating the required phi nodes
+      at the exit of LOOP (i.e, in NEW_EXIT_BB).
+
+   There are two flavors to this function:
+
+   slpeel_update_phi_nodes_for_guard1:
+     Here the guard controls whether we enter or skip LOOP, where LOOP is a
+     prolog_loop (loop1 below), and the new phis created in NEW_MERGE_BB are
+     for variables that have phis in the loop header.
+
+   slpeel_update_phi_nodes_for_guard2:
+     Here the guard controls whether we enter or skip LOOP, where LOOP is an
+     epilog_loop (loop2 below), and the new phis created in NEW_MERGE_BB are
+     for variables that have phis in the loop exit.
+
+   I.E., the overall structure is:
+
+        loop1_preheader_bb:
+                guard1 (goto loop1/merge1_bb)
+        loop1
+        loop1_exit_bb:
+                guard2 (goto merge1_bb/merge2_bb)
+        merge1_bb
+        loop2
+        loop2_exit_bb
+        merge2_bb
+        next_bb
+
+   slpeel_update_phi_nodes_for_guard1 takes care of creating phis in
+   loop1_exit_bb and merge1_bb. These are entry phis (phis for the vars
+   that have phis in loop1->header).
+
+   slpeel_update_phi_nodes_for_guard2 takes care of creating phis in
+   loop2_exit_bb and merge2_bb. These are exit phis (phis for the vars
+   that have phis in next_bb). It also adds some of these phis to
+   loop1_exit_bb.
+
+   slpeel_update_phi_nodes_for_guard1 is always called before
+   slpeel_update_phi_nodes_for_guard2. They are both needed in order
+   to create correct data-flow and loop-closed-ssa-form.
+
+   Generally slpeel_update_phi_nodes_for_guard1 creates phis for variables
+   that change between iterations of a loop (and therefore have a phi-node
+   at the loop entry), whereas slpeel_update_phi_nodes_for_guard2 creates
+   phis for variables that are used out of the loop (and therefore have
+   loop-closed exit phis). Some variables may be both updated between
+   iterations and used after the loop. This is why in loop1_exit_bb we
+   may need both entry_phis (created by slpeel_update_phi_nodes_for_guard1)
+   and exit phis (created by slpeel_update_phi_nodes_for_guard2).
+
+   - IS_NEW_LOOP: if IS_NEW_LOOP is true, then LOOP is a newly created copy of
+     an original loop. i.e., we have:
+
+           orig_loop
+           guard_bb (goto LOOP/new_merge)
+           new_loop <-- LOOP
+           new_exit
+           new_merge
+           next_bb
+
+     If IS_NEW_LOOP is false, then LOOP is an original loop, in which case we
+     have:
+
+           new_loop
+           guard_bb (goto LOOP/new_merge)
+           orig_loop <-- LOOP
+           new_exit
+           new_merge
+           next_bb
+
+     The SSA names defined in the original loop have a current
+     reaching definition that that records the corresponding new
+     ssa-name used in the new duplicated loop copy.
+  */
+
+/* Function slpeel_update_phi_nodes_for_guard1
+
+   Input:
+   - GUARD_EDGE, LOOP, IS_NEW_LOOP, NEW_EXIT_BB - as explained above.
+   - DEFS - a bitmap of ssa names to mark new names for which we recorded
+            information.
+
+   In the context of the overall structure, we have:
+
+        loop1_preheader_bb:
+                guard1 (goto loop1/merge1_bb)
+LOOP->  loop1
+        loop1_exit_bb:
+                guard2 (goto merge1_bb/merge2_bb)
+        merge1_bb
+        loop2
+        loop2_exit_bb
+        merge2_bb
+        next_bb
+
+   For each name updated between loop iterations (i.e - for each name that has
+   an entry (loop-header) phi in LOOP) we create a new phi in:
+   1. merge1_bb (to account for the edge from guard1)
+   2. loop1_exit_bb (an exit-phi to keep LOOP in loop-closed form)
+*/
+
+static void
+slpeel_update_phi_nodes_for_guard1 (edge guard_edge, struct loop *loop,
+                                    bool is_new_loop, basic_block *new_exit_bb)
+{
+  gimple orig_phi, new_phi;
+  gimple update_phi, update_phi2;
+  tree guard_arg, loop_arg;
+  basic_block new_merge_bb = guard_edge->dest;
+  edge e = EDGE_SUCC (new_merge_bb, 0);
+  basic_block update_bb = e->dest;
+  basic_block orig_bb = loop->header;
+  edge new_exit_e;
+  tree current_new_name;
+  gimple_stmt_iterator gsi_orig, gsi_update;
+
+  /* Create new bb between loop and new_merge_bb.  */
+  *new_exit_bb = split_edge (single_exit (loop));
+
+  new_exit_e = EDGE_SUCC (*new_exit_bb, 0);
+
+  for (gsi_orig = gsi_start_phis (orig_bb),
+       gsi_update = gsi_start_phis (update_bb);
+       !gsi_end_p (gsi_orig) && !gsi_end_p (gsi_update);
+       gsi_next (&gsi_orig), gsi_next (&gsi_update))
+    {
+      source_location loop_locus, guard_locus;
+      tree new_res;
+      orig_phi = gsi_stmt (gsi_orig);
+      update_phi = gsi_stmt (gsi_update);
+
+      /** 1. Handle new-merge-point phis  **/
+
+      /* 1.1. Generate new phi node in NEW_MERGE_BB:  */
+      new_res = copy_ssa_name (PHI_RESULT (orig_phi), NULL);
+      new_phi = create_phi_node (new_res, new_merge_bb);
+
+      /* 1.2. NEW_MERGE_BB has two incoming edges: GUARD_EDGE and the exit-edge
+            of LOOP. Set the two phi args in NEW_PHI for these edges:  */
+      loop_arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, EDGE_SUCC (loop->latch, 0));
+      loop_locus = gimple_phi_arg_location_from_edge (orig_phi,
+						      EDGE_SUCC (loop->latch,
+								 0));
+      guard_arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, loop_preheader_edge (loop));
+      guard_locus
+	= gimple_phi_arg_location_from_edge (orig_phi,
+					     loop_preheader_edge (loop));
+
+      add_phi_arg (new_phi, loop_arg, new_exit_e, loop_locus);
+      add_phi_arg (new_phi, guard_arg, guard_edge, guard_locus);
+
+      /* 1.3. Update phi in successor block.  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi, e) == loop_arg
+                  || PHI_ARG_DEF_FROM_EDGE (update_phi, e) == guard_arg);
+      adjust_phi_and_debug_stmts (update_phi, e, PHI_RESULT (new_phi));
+      update_phi2 = new_phi;
+
+
+      /** 2. Handle loop-closed-ssa-form phis  **/
+
+      if (virtual_operand_p (PHI_RESULT (orig_phi)))
+	continue;
+
+      /* 2.1. Generate new phi node in NEW_EXIT_BB:  */
+      new_res = copy_ssa_name (PHI_RESULT (orig_phi), NULL);
+      new_phi = create_phi_node (new_res, *new_exit_bb);
+
+      /* 2.2. NEW_EXIT_BB has one incoming edge: the exit-edge of the loop.  */
+      add_phi_arg (new_phi, loop_arg, single_exit (loop), loop_locus);
+
+      /* 2.3. Update phi in successor of NEW_EXIT_BB:  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi2, new_exit_e) == loop_arg);
+      adjust_phi_and_debug_stmts (update_phi2, new_exit_e,
+				  PHI_RESULT (new_phi));
+
+      /* 2.4. Record the newly created name with set_current_def.
+         We want to find a name such that
+                name = get_current_def (orig_loop_name)
+         and to set its current definition as follows:
+                set_current_def (name, new_phi_name)
+
+         If LOOP is a new loop then loop_arg is already the name we're
+         looking for. If LOOP is the original loop, then loop_arg is
+         the orig_loop_name and the relevant name is recorded in its
+         current reaching definition.  */
+      if (is_new_loop)
+        current_new_name = loop_arg;
+      else
+        {
+          current_new_name = get_current_def (loop_arg);
+	  /* current_def is not available only if the variable does not
+	     change inside the loop, in which case we also don't care
+	     about recording a current_def for it because we won't be
+	     trying to create loop-exit-phis for it.  */
+	  if (!current_new_name)
+	    continue;
+        }
+      tree new_name = get_current_def (current_new_name);
+      /* Because of peeled_chrec optimization it is possible that we have
+	 set this earlier.  Verify the PHI has the same value.  */
+      if (new_name)
+	{
+	  gimple phi = SSA_NAME_DEF_STMT (new_name);
+	  gcc_assert (gimple_code (phi) == GIMPLE_PHI
+		      && gimple_bb (phi) == *new_exit_bb
+		      && (PHI_ARG_DEF_FROM_EDGE (phi, single_exit (loop))
+			  == loop_arg));
+	  continue;
+	}
+
+      set_current_def (current_new_name, PHI_RESULT (new_phi));
+    }
+}
+
+
+/* Function slpeel_update_phi_nodes_for_guard2
+
+   Input:
+   - GUARD_EDGE, LOOP, IS_NEW_LOOP, NEW_EXIT_BB - as explained above.
+
+   In the context of the overall structure, we have:
+
+        loop1_preheader_bb:
+                guard1 (goto loop1/merge1_bb)
+        loop1
+        loop1_exit_bb:
+                guard2 (goto merge1_bb/merge2_bb)
+        merge1_bb
+LOOP->  loop2
+        loop2_exit_bb
+        merge2_bb
+        next_bb
+
+   For each name used out side the loop (i.e - for each name that has an exit
+   phi in next_bb) we create a new phi in:
+   1. merge2_bb (to account for the edge from guard_bb)
+   2. loop2_exit_bb (an exit-phi to keep LOOP in loop-closed form)
+   3. guard2 bb (an exit phi to keep the preceding loop in loop-closed form),
+      if needed (if it wasn't handled by slpeel_update_phis_nodes_for_phi1).
+*/
+
+static void
+slpeel_update_phi_nodes_for_guard2 (edge guard_edge, struct loop *loop,
+                                    bool is_new_loop, basic_block *new_exit_bb)
+{
+  gimple orig_phi, new_phi;
+  gimple update_phi, update_phi2;
+  tree guard_arg, loop_arg;
+  basic_block new_merge_bb = guard_edge->dest;
+  edge e = EDGE_SUCC (new_merge_bb, 0);
+  basic_block update_bb = e->dest;
+  edge new_exit_e;
+  tree orig_def, orig_def_new_name;
+  tree new_name, new_name2;
+  tree arg;
+  gimple_stmt_iterator gsi;
+
+  /* Create new bb between loop and new_merge_bb.  */
+  *new_exit_bb = split_edge (single_exit (loop));
+
+  new_exit_e = EDGE_SUCC (*new_exit_bb, 0);
+
+  for (gsi = gsi_start_phis (update_bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      tree new_res;
+      update_phi = gsi_stmt (gsi);
+      orig_phi = update_phi;
+      orig_def = PHI_ARG_DEF_FROM_EDGE (orig_phi, e);
+      /* This loop-closed-phi actually doesn't represent a use
+         out of the loop - the phi arg is a constant.  */
+      if (TREE_CODE (orig_def) != SSA_NAME)
+        continue;
+      orig_def_new_name = get_current_def (orig_def);
+      arg = NULL_TREE;
+
+      /** 1. Handle new-merge-point phis  **/
+
+      /* 1.1. Generate new phi node in NEW_MERGE_BB:  */
+      new_res = copy_ssa_name (PHI_RESULT (orig_phi), NULL);
+      new_phi = create_phi_node (new_res, new_merge_bb);
+
+      /* 1.2. NEW_MERGE_BB has two incoming edges: GUARD_EDGE and the exit-edge
+            of LOOP. Set the two PHI args in NEW_PHI for these edges:  */
+      new_name = orig_def;
+      new_name2 = NULL_TREE;
+      if (orig_def_new_name)
+        {
+          new_name = orig_def_new_name;
+	  /* Some variables have both loop-entry-phis and loop-exit-phis.
+	     Such variables were given yet newer names by phis placed in
+	     guard_bb by slpeel_update_phi_nodes_for_guard1. I.e:
+	     new_name2 = get_current_def (get_current_def (orig_name)).  */
+          new_name2 = get_current_def (new_name);
+        }
+
+      if (is_new_loop)
+        {
+          guard_arg = orig_def;
+          loop_arg = new_name;
+        }
+      else
+        {
+          guard_arg = new_name;
+          loop_arg = orig_def;
+        }
+      if (new_name2)
+        guard_arg = new_name2;
+
+      add_phi_arg (new_phi, loop_arg, new_exit_e, UNKNOWN_LOCATION);
+      add_phi_arg (new_phi, guard_arg, guard_edge, UNKNOWN_LOCATION);
+
+      /* 1.3. Update phi in successor block.  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi, e) == orig_def);
+      adjust_phi_and_debug_stmts (update_phi, e, PHI_RESULT (new_phi));
+      update_phi2 = new_phi;
+
+
+      /** 2. Handle loop-closed-ssa-form phis  **/
+
+      /* 2.1. Generate new phi node in NEW_EXIT_BB:  */
+      new_res = copy_ssa_name (PHI_RESULT (orig_phi), NULL);
+      new_phi = create_phi_node (new_res, *new_exit_bb);
+
+      /* 2.2. NEW_EXIT_BB has one incoming edge: the exit-edge of the loop.  */
+      add_phi_arg (new_phi, loop_arg, single_exit (loop), UNKNOWN_LOCATION);
+
+      /* 2.3. Update phi in successor of NEW_EXIT_BB:  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi2, new_exit_e) == loop_arg);
+      adjust_phi_and_debug_stmts (update_phi2, new_exit_e,
+				  PHI_RESULT (new_phi));
+
+
+      /** 3. Handle loop-closed-ssa-form phis for first loop  **/
+
+      /* 3.1. Find the relevant names that need an exit-phi in
+	 GUARD_BB, i.e. names for which
+	 slpeel_update_phi_nodes_for_guard1 had not already created a
+	 phi node. This is the case for names that are used outside
+	 the loop (and therefore need an exit phi) but are not updated
+	 across loop iterations (and therefore don't have a
+	 loop-header-phi).
+
+	 slpeel_update_phi_nodes_for_guard1 is responsible for
+	 creating loop-exit phis in GUARD_BB for names that have a
+	 loop-header-phi.  When such a phi is created we also record
+	 the new name in its current definition.  If this new name
+	 exists, then guard_arg was set to this new name (see 1.2
+	 above).  Therefore, if guard_arg is not this new name, this
+	 is an indication that an exit-phi in GUARD_BB was not yet
+	 created, so we take care of it here.  */
+      if (guard_arg == new_name2)
+	continue;
+      arg = guard_arg;
+
+      /* 3.2. Generate new phi node in GUARD_BB:  */
+      new_res = copy_ssa_name (PHI_RESULT (orig_phi), NULL);
+      new_phi = create_phi_node (new_res, guard_edge->src);
+
+      /* 3.3. GUARD_BB has one incoming edge:  */
+      gcc_assert (EDGE_COUNT (guard_edge->src->preds) == 1);
+      add_phi_arg (new_phi, arg, EDGE_PRED (guard_edge->src, 0),
+		   UNKNOWN_LOCATION);
+
+      /* 3.4. Update phi in successor of GUARD_BB:  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi2, guard_edge)
+                                                                == guard_arg);
+      adjust_phi_and_debug_stmts (update_phi2, guard_edge,
+				  PHI_RESULT (new_phi));
+    }
+}
+
+
+/* Make the LOOP iterate NITERS times. This is done by adding a new IV
+   that starts at zero, increases by one and its limit is NITERS.
+
+   Assumption: the exit-condition of LOOP is the last stmt in the loop.  */
+
+void
+slpeel_make_loop_iterate_ntimes (struct loop *loop, tree niters)
+{
+  tree indx_before_incr, indx_after_incr;
+  gimple cond_stmt;
+  gimple orig_cond;
+  edge exit_edge = single_exit (loop);
+  gimple_stmt_iterator loop_cond_gsi;
+  gimple_stmt_iterator incr_gsi;
+  bool insert_after;
+  tree init = build_int_cst (TREE_TYPE (niters), 0);
+  tree step = build_int_cst (TREE_TYPE (niters), 1);
+  source_location loop_loc;
+  enum tree_code code;
+
+  orig_cond = get_loop_exit_condition (loop);
+  gcc_assert (orig_cond);
+  loop_cond_gsi = gsi_for_stmt (orig_cond);
+
+  standard_iv_increment_position (loop, &incr_gsi, &insert_after);
+  create_iv (init, step, NULL_TREE, loop,
+             &incr_gsi, insert_after, &indx_before_incr, &indx_after_incr);
+
+  indx_after_incr = force_gimple_operand_gsi (&loop_cond_gsi, indx_after_incr,
+					      true, NULL_TREE, true,
+					      GSI_SAME_STMT);
+  niters = force_gimple_operand_gsi (&loop_cond_gsi, niters, true, NULL_TREE,
+				     true, GSI_SAME_STMT);
+
+  code = (exit_edge->flags & EDGE_TRUE_VALUE) ? GE_EXPR : LT_EXPR;
+  cond_stmt = gimple_build_cond (code, indx_after_incr, niters, NULL_TREE,
+				 NULL_TREE);
+
+  gsi_insert_before (&loop_cond_gsi, cond_stmt, GSI_SAME_STMT);
+
+  /* Remove old loop exit test:  */
+  gsi_remove (&loop_cond_gsi, true);
+  free_stmt_vec_info (orig_cond);
+
+  loop_loc = find_loop_location (loop);
+  if (dump_enabled_p ())
+    {
+      if (LOCATION_LOCUS (loop_loc) != UNKNOWN_LOCATION)
+	dump_printf (MSG_NOTE, "\nloop at %s:%d: ", LOCATION_FILE (loop_loc),
+		     LOCATION_LINE (loop_loc));
+      dump_gimple_stmt (MSG_NOTE, TDF_SLIM, cond_stmt, 0);
+      dump_printf (MSG_NOTE, "\n");
+    }
+  loop->nb_iterations = niters;
+}
+
+/* Helper routine of slpeel_tree_duplicate_loop_to_edge_cfg.
+   For all PHI arguments in FROM->dest and TO->dest from those
+   edges ensure that TO->dest PHI arguments have current_def
+   to that in from.  */
+
+static void
+slpeel_duplicate_current_defs_from_edges (edge from, edge to)
+{
+  gimple_stmt_iterator gsi_from, gsi_to;
+
+  for (gsi_from = gsi_start_phis (from->dest),
+       gsi_to = gsi_start_phis (to->dest);
+       !gsi_end_p (gsi_from) && !gsi_end_p (gsi_to);
+       gsi_next (&gsi_from), gsi_next (&gsi_to))
+    {
+      gimple from_phi = gsi_stmt (gsi_from);
+      gimple to_phi = gsi_stmt (gsi_to);
+      tree from_arg = PHI_ARG_DEF_FROM_EDGE (from_phi, from);
+      tree to_arg = PHI_ARG_DEF_FROM_EDGE (to_phi, to);
+      if (TREE_CODE (from_arg) == SSA_NAME
+	  && TREE_CODE (to_arg) == SSA_NAME
+	  && get_current_def (to_arg) == NULL_TREE)
+	set_current_def (to_arg, get_current_def (from_arg));
+    }
+}
+
+
+/* Given LOOP this function generates a new copy of it and puts it
+   on E which is either the entry or exit of LOOP.  If SCALAR_LOOP is
+   non-NULL, assume LOOP and SCALAR_LOOP are equivalent and copy the
+   basic blocks from SCALAR_LOOP instead of LOOP, but to either the
+   entry or exit of LOOP.  */
+
+struct loop *
+slpeel_tree_duplicate_loop_to_edge_cfg (struct loop *loop,
+					struct loop *scalar_loop, edge e)
+{
+  struct loop *new_loop;
+  basic_block *new_bbs, *bbs;
+  bool at_exit;
+  bool was_imm_dom;
+  basic_block exit_dest;
+  edge exit, new_exit;
+
+  exit = single_exit (loop);
+  at_exit = (e == exit);
+  if (!at_exit && e != loop_preheader_edge (loop))
+    return NULL;
+
+  if (scalar_loop == NULL)
+    scalar_loop = loop;
+
+  bbs = XNEWVEC (basic_block, scalar_loop->num_nodes + 1);
+  get_loop_body_with_size (scalar_loop, bbs, scalar_loop->num_nodes);
+
+  /* Check whether duplication is possible.  */
+  if (!can_copy_bbs_p (bbs, scalar_loop->num_nodes))
+    {
+      free (bbs);
+      return NULL;
+    }
+
+  /* Generate new loop structure.  */
+  new_loop = duplicate_loop (scalar_loop, loop_outer (scalar_loop));
+  duplicate_subloops (scalar_loop, new_loop);
+
+  exit_dest = exit->dest;
+  was_imm_dom = (get_immediate_dominator (CDI_DOMINATORS,
+					  exit_dest) == loop->header ?
+		 true : false);
+
+  /* Also copy the pre-header, this avoids jumping through hoops to
+     duplicate the loop entry PHI arguments.  Create an empty
+     pre-header unconditionally for this.  */
+  basic_block preheader = split_edge (loop_preheader_edge (scalar_loop));
+  edge entry_e = single_pred_edge (preheader);
+  bbs[scalar_loop->num_nodes] = preheader;
+  new_bbs = XNEWVEC (basic_block, scalar_loop->num_nodes + 1);
+
+  exit = single_exit (scalar_loop);
+  copy_bbs (bbs, scalar_loop->num_nodes + 1, new_bbs,
+	    &exit, 1, &new_exit, NULL,
+	    e->src, true);
+  exit = single_exit (loop);
+  basic_block new_preheader = new_bbs[scalar_loop->num_nodes];
+
+  add_phi_args_after_copy (new_bbs, scalar_loop->num_nodes + 1, NULL);
+
+  if (scalar_loop != loop)
+    {
+      /* If we copied from SCALAR_LOOP rather than LOOP, SSA_NAMEs from
+	 SCALAR_LOOP will have current_def set to SSA_NAMEs in the new_loop,
+	 but LOOP will not.  slpeel_update_phi_nodes_for_guard{1,2} expects
+	 the LOOP SSA_NAMEs (on the exit edge and edge from latch to
+	 header) to have current_def set, so copy them over.  */
+      slpeel_duplicate_current_defs_from_edges (single_exit (scalar_loop),
+						exit);
+      slpeel_duplicate_current_defs_from_edges (EDGE_SUCC (scalar_loop->latch,
+							   0),
+						EDGE_SUCC (loop->latch, 0));
+    }
+
+  if (at_exit) /* Add the loop copy at exit.  */
+    {
+      if (scalar_loop != loop)
+	{
+	  gimple_stmt_iterator gsi;
+	  new_exit = redirect_edge_and_branch (new_exit, exit_dest);
+
+	  for (gsi = gsi_start_phis (exit_dest); !gsi_end_p (gsi);
+	       gsi_next (&gsi))
+	    {
+	      gimple phi = gsi_stmt (gsi);
+	      tree orig_arg = PHI_ARG_DEF_FROM_EDGE (phi, e);
+	      location_t orig_locus
+		= gimple_phi_arg_location_from_edge (phi, e);
+
+	      add_phi_arg (phi, orig_arg, new_exit, orig_locus);
+	    }
+	}
+      redirect_edge_and_branch_force (e, new_preheader);
+      flush_pending_stmts (e);
+      set_immediate_dominator (CDI_DOMINATORS, new_preheader, e->src);
+      if (was_imm_dom)
+	set_immediate_dominator (CDI_DOMINATORS, exit_dest, new_exit->src);
+
+      /* And remove the non-necessary forwarder again.  Keep the other
+         one so we have a proper pre-header for the loop at the exit edge.  */
+      redirect_edge_pred (single_succ_edge (preheader),
+			  single_pred (preheader));
+      delete_basic_block (preheader);
+      set_immediate_dominator (CDI_DOMINATORS, scalar_loop->header,
+			       loop_preheader_edge (scalar_loop)->src);
+    }
+  else /* Add the copy at entry.  */
+    {
+      if (scalar_loop != loop)
+	{
+	  /* Remove the non-necessary forwarder of scalar_loop again.  */
+	  redirect_edge_pred (single_succ_edge (preheader),
+			      single_pred (preheader));
+	  delete_basic_block (preheader);
+	  set_immediate_dominator (CDI_DOMINATORS, scalar_loop->header,
+				   loop_preheader_edge (scalar_loop)->src);
+	  preheader = split_edge (loop_preheader_edge (loop));
+	  entry_e = single_pred_edge (preheader);
+	}
+
+      redirect_edge_and_branch_force (entry_e, new_preheader);
+      flush_pending_stmts (entry_e);
+      set_immediate_dominator (CDI_DOMINATORS, new_preheader, entry_e->src);
+
+      redirect_edge_and_branch_force (new_exit, preheader);
+      flush_pending_stmts (new_exit);
+      set_immediate_dominator (CDI_DOMINATORS, preheader, new_exit->src);
+
+      /* And remove the non-necessary forwarder again.  Keep the other
+         one so we have a proper pre-header for the loop at the exit edge.  */
+      redirect_edge_pred (single_succ_edge (new_preheader),
+			  single_pred (new_preheader));
+      delete_basic_block (new_preheader);
+      set_immediate_dominator (CDI_DOMINATORS, new_loop->header,
+			       loop_preheader_edge (new_loop)->src);
+    }
+
+  for (unsigned i = 0; i < scalar_loop->num_nodes + 1; i++)
+    rename_variables_in_bb (new_bbs[i]);
+
+  if (scalar_loop != loop)
+    {
+      /* Update new_loop->header PHIs, so that on the preheader
+	 edge they are the ones from loop rather than scalar_loop.  */
+      gimple_stmt_iterator gsi_orig, gsi_new;
+      edge orig_e = loop_preheader_edge (loop);
+      edge new_e = loop_preheader_edge (new_loop);
+
+      for (gsi_orig = gsi_start_phis (loop->header),
+	   gsi_new = gsi_start_phis (new_loop->header);
+	   !gsi_end_p (gsi_orig) && !gsi_end_p (gsi_new);
+	   gsi_next (&gsi_orig), gsi_next (&gsi_new))
+	{
+	  gimple orig_phi = gsi_stmt (gsi_orig);
+	  gimple new_phi = gsi_stmt (gsi_new);
+	  tree orig_arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, orig_e);
+	  location_t orig_locus
+	    = gimple_phi_arg_location_from_edge (orig_phi, orig_e);
+
+	  add_phi_arg (new_phi, orig_arg, new_e, orig_locus);
+	}
+    }
+
+  free (new_bbs);
+  free (bbs);
+
+#ifdef ENABLE_CHECKING
+  verify_dominators (CDI_DOMINATORS);
+#endif
+
+  return new_loop;
+}
+
+
+/* Given the condition statement COND, put it as the last statement
+   of GUARD_BB; EXIT_BB is the basic block to skip the loop;
+   Assumes that this is the single exit of the guarded loop.
+   Returns the skip edge, inserts new stmts on the COND_EXPR_STMT_LIST.  */
+
+static edge
+slpeel_add_loop_guard (basic_block guard_bb, tree cond,
+		       gimple_seq cond_expr_stmt_list,
+		       basic_block exit_bb, basic_block dom_bb,
+		       int probability)
+{
+  gimple_stmt_iterator gsi;
+  edge new_e, enter_e;
+  gimple cond_stmt;
+  gimple_seq gimplify_stmt_list = NULL;
+
+  enter_e = EDGE_SUCC (guard_bb, 0);
+  enter_e->flags &= ~EDGE_FALLTHRU;
+  enter_e->flags |= EDGE_FALSE_VALUE;
+  gsi = gsi_last_bb (guard_bb);
+
+  cond = force_gimple_operand_1 (cond, &gimplify_stmt_list, is_gimple_condexpr,
+				 NULL_TREE);
+  if (gimplify_stmt_list)
+    gimple_seq_add_seq (&cond_expr_stmt_list, gimplify_stmt_list);
+  cond_stmt = gimple_build_cond_from_tree (cond, NULL_TREE, NULL_TREE);
+  if (cond_expr_stmt_list)
+    gsi_insert_seq_after (&gsi, cond_expr_stmt_list, GSI_NEW_STMT);
+
+  gsi = gsi_last_bb (guard_bb);
+  gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);
+
+  /* Add new edge to connect guard block to the merge/loop-exit block.  */
+  new_e = make_edge (guard_bb, exit_bb, EDGE_TRUE_VALUE);
+
+  new_e->count = guard_bb->count;
+  new_e->probability = probability;
+  new_e->count = apply_probability (enter_e->count, probability);
+  enter_e->count -= new_e->count;
+  enter_e->probability = inverse_probability (probability);
+  set_immediate_dominator (CDI_DOMINATORS, exit_bb, dom_bb);
+  return new_e;
+}
+
+
+/* This function verifies that the following restrictions apply to LOOP:
+   (1) it is innermost
+   (2) it consists of exactly 2 basic blocks - header, and an empty latch.
+   (3) it is single entry, single exit
+   (4) its exit condition is the last stmt in the header
+   (5) E is the entry/exit edge of LOOP.
+ */
+
+bool
+slpeel_can_duplicate_loop_p (const struct loop *loop, const_edge e)
+{
+  edge exit_e = single_exit (loop);
+  edge entry_e = loop_preheader_edge (loop);
+  gimple orig_cond = get_loop_exit_condition (loop);
+  gimple_stmt_iterator loop_exit_gsi = gsi_last_bb (exit_e->src);
+
+  if (loop->inner
+      /* All loops have an outer scope; the only case loop->outer is NULL is for
+         the function itself.  */
+      || !loop_outer (loop)
+      || loop->num_nodes != 2
+      || !empty_block_p (loop->latch)
+      || !single_exit (loop)
+      /* Verify that new loop exit condition can be trivially modified.  */
+      || (!orig_cond || orig_cond != gsi_stmt (loop_exit_gsi))
+      || (e != exit_e && e != entry_e))
+    return false;
+
+  return true;
+}
+
+#ifdef ENABLE_CHECKING
+static void
+slpeel_verify_cfg_after_peeling (struct loop *first_loop,
+                                 struct loop *second_loop)
+{
+  basic_block loop1_exit_bb = single_exit (first_loop)->dest;
+  basic_block loop2_entry_bb = loop_preheader_edge (second_loop)->src;
+  basic_block loop1_entry_bb = loop_preheader_edge (first_loop)->src;
+
+  /* A guard that controls whether the second_loop is to be executed or skipped
+     is placed in first_loop->exit.  first_loop->exit therefore has two
+     successors - one is the preheader of second_loop, and the other is a bb
+     after second_loop.
+   */
+  gcc_assert (EDGE_COUNT (loop1_exit_bb->succs) == 2);
+
+  /* 1. Verify that one of the successors of first_loop->exit is the preheader
+        of second_loop.  */
+
+  /* The preheader of new_loop is expected to have two predecessors:
+     first_loop->exit and the block that precedes first_loop.  */
+
+  gcc_assert (EDGE_COUNT (loop2_entry_bb->preds) == 2
+              && ((EDGE_PRED (loop2_entry_bb, 0)->src == loop1_exit_bb
+                   && EDGE_PRED (loop2_entry_bb, 1)->src == loop1_entry_bb)
+               || (EDGE_PRED (loop2_entry_bb, 1)->src ==  loop1_exit_bb
+                   && EDGE_PRED (loop2_entry_bb, 0)->src == loop1_entry_bb)));
+
+  /* Verify that the other successor of first_loop->exit is after the
+     second_loop.  */
+  /* TODO */
+}
+#endif
+
+/* If the run time cost model check determines that vectorization is
+   not profitable and hence scalar loop should be generated then set
+   FIRST_NITERS to prologue peeled iterations. This will allow all the
+   iterations to be executed in the prologue peeled scalar loop.  */
+
+static void
+set_prologue_iterations (basic_block bb_before_first_loop,
+			 tree *first_niters,
+			 struct loop *loop,
+			 unsigned int th,
+			 int probability)
+{
+  edge e;
+  basic_block cond_bb, then_bb;
+  tree var, prologue_after_cost_adjust_name;
+  gimple_stmt_iterator gsi;
+  gimple newphi;
+  edge e_true, e_false, e_fallthru;
+  gimple cond_stmt;
+  gimple_seq stmts = NULL;
+  tree cost_pre_condition = NULL_TREE;
+  tree scalar_loop_iters =
+    unshare_expr (LOOP_VINFO_NITERS_UNCHANGED (loop_vec_info_for_loop (loop)));
+
+  e = single_pred_edge (bb_before_first_loop);
+  cond_bb = split_edge (e);
+
+  e = single_pred_edge (bb_before_first_loop);
+  then_bb = split_edge (e);
+  set_immediate_dominator (CDI_DOMINATORS, then_bb, cond_bb);
+
+  e_false = make_single_succ_edge (cond_bb, bb_before_first_loop,
+				   EDGE_FALSE_VALUE);
+  set_immediate_dominator (CDI_DOMINATORS, bb_before_first_loop, cond_bb);
+
+  e_true = EDGE_PRED (then_bb, 0);
+  e_true->flags &= ~EDGE_FALLTHRU;
+  e_true->flags |= EDGE_TRUE_VALUE;
+
+  e_true->probability = probability;
+  e_false->probability = inverse_probability (probability);
+  e_true->count = apply_probability (cond_bb->count, probability);
+  e_false->count = cond_bb->count - e_true->count;
+  then_bb->frequency = EDGE_FREQUENCY (e_true);
+  then_bb->count = e_true->count;
+
+  e_fallthru = EDGE_SUCC (then_bb, 0);
+  e_fallthru->count = then_bb->count;
+
+  gsi = gsi_last_bb (cond_bb);
+  cost_pre_condition =
+    fold_build2 (LE_EXPR, boolean_type_node, scalar_loop_iters,
+	         build_int_cst (TREE_TYPE (scalar_loop_iters), th));
+  cost_pre_condition =
+    force_gimple_operand_gsi_1 (&gsi, cost_pre_condition, is_gimple_condexpr,
+				NULL_TREE, false, GSI_CONTINUE_LINKING);
+  cond_stmt = gimple_build_cond_from_tree (cost_pre_condition,
+					   NULL_TREE, NULL_TREE);
+  gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);
+
+  var = create_tmp_var (TREE_TYPE (scalar_loop_iters),
+			"prologue_after_cost_adjust");
+  prologue_after_cost_adjust_name =
+    force_gimple_operand (scalar_loop_iters, &stmts, false, var);
+
+  gsi = gsi_last_bb (then_bb);
+  if (stmts)
+    gsi_insert_seq_after (&gsi, stmts, GSI_NEW_STMT);
+
+  newphi = create_phi_node (var, bb_before_first_loop);
+  add_phi_arg (newphi, prologue_after_cost_adjust_name, e_fallthru,
+	       UNKNOWN_LOCATION);
+  add_phi_arg (newphi, *first_niters, e_false, UNKNOWN_LOCATION);
+
+  *first_niters = PHI_RESULT (newphi);
+}
+
+/* Function slpeel_tree_peel_loop_to_edge.
+
+   Peel the first (last) iterations of LOOP into a new prolog (epilog) loop
+   that is placed on the entry (exit) edge E of LOOP. After this transformation
+   we have two loops one after the other - first-loop iterates FIRST_NITERS
+   times, and second-loop iterates the remainder NITERS - FIRST_NITERS times.
+   If the cost model indicates that it is profitable to emit a scalar
+   loop instead of the vector one, then the prolog (epilog) loop will iterate
+   for the entire unchanged scalar iterations of the loop.
+
+   Input:
+   - LOOP: the loop to be peeled.
+   - SCALAR_LOOP: if non-NULL, the alternate loop from which basic blocks
+	should be copied.
+   - E: the exit or entry edge of LOOP.
+        If it is the entry edge, we peel the first iterations of LOOP. In this
+        case first-loop is LOOP, and second-loop is the newly created loop.
+        If it is the exit edge, we peel the last iterations of LOOP. In this
+        case, first-loop is the newly created loop, and second-loop is LOOP.
+   - NITERS: the number of iterations that LOOP iterates.
+   - FIRST_NITERS: the number of iterations that the first-loop should iterate.
+   - UPDATE_FIRST_LOOP_COUNT:  specified whether this function is responsible
+        for updating the loop bound of the first-loop to FIRST_NITERS.  If it
+        is false, the caller of this function may want to take care of this
+        (this can be useful if we don't want new stmts added to first-loop).
+   - TH: cost model profitability threshold of iterations for vectorization.
+   - CHECK_PROFITABILITY: specify whether cost model check has not occurred
+                          during versioning and hence needs to occur during
+			  prologue generation or whether cost model check
+			  has not occurred during prologue generation and hence
+			  needs to occur during epilogue generation.
+   - BOUND1 is the upper bound on number of iterations of the first loop (if known)
+   - BOUND2 is the upper bound on number of iterations of the second loop (if known)
+
+
+   Output:
+   The function returns a pointer to the new loop-copy, or NULL if it failed
+   to perform the transformation.
+
+   The function generates two if-then-else guards: one before the first loop,
+   and the other before the second loop:
+   The first guard is:
+     if (FIRST_NITERS == 0) then skip the first loop,
+     and go directly to the second loop.
+   The second guard is:
+     if (FIRST_NITERS == NITERS) then skip the second loop.
+
+   If the optional COND_EXPR and COND_EXPR_STMT_LIST arguments are given
+   then the generated condition is combined with COND_EXPR and the
+   statements in COND_EXPR_STMT_LIST are emitted together with it.
+
+   FORNOW only simple loops are supported (see slpeel_can_duplicate_loop_p).
+   FORNOW the resulting code will not be in loop-closed-ssa form.
+*/
+
+static struct loop *
+slpeel_tree_peel_loop_to_edge (struct loop *loop, struct loop *scalar_loop,
+			       edge e, tree *first_niters,
+			       tree niters, bool update_first_loop_count,
+			       unsigned int th, bool check_profitability,
+			       tree cond_expr, gimple_seq cond_expr_stmt_list,
+			       int bound1, int bound2)
+{
+  struct loop *new_loop = NULL, *first_loop, *second_loop;
+  edge skip_e;
+  tree pre_condition = NULL_TREE;
+  basic_block bb_before_second_loop, bb_after_second_loop;
+  basic_block bb_before_first_loop;
+  basic_block bb_between_loops;
+  basic_block new_exit_bb;
+  gimple_stmt_iterator gsi;
+  edge exit_e = single_exit (loop);
+  source_location loop_loc;
+  /* There are many aspects to how likely the first loop is going to be executed.
+     Without histogram we can't really do good job.  Simply set it to
+     2/3, so the first loop is not reordered to the end of function and
+     the hot path through stays short.  */
+  int first_guard_probability = 2 * REG_BR_PROB_BASE / 3;
+  int second_guard_probability = 2 * REG_BR_PROB_BASE / 3;
+  int probability_of_second_loop;
+
+  if (!slpeel_can_duplicate_loop_p (loop, e))
+    return NULL;
+
+  /* We might have a queued need to update virtual SSA form.  As we
+     delete the update SSA machinery below after doing a regular
+     incremental SSA update during loop copying make sure we don't
+     lose that fact.
+     ???  Needing to update virtual SSA form by renaming is unfortunate
+     but not all of the vectorizer code inserting new loads / stores
+     properly assigns virtual operands to those statements.  */
+  update_ssa (TODO_update_ssa_only_virtuals);
+ 
+  /* If the loop has a virtual PHI, but exit bb doesn't, create a virtual PHI
+     in the exit bb and rename all the uses after the loop.  This simplifies
+     the *guard[12] routines, which assume loop closed SSA form for all PHIs
+     (but normally loop closed SSA form doesn't require virtual PHIs to be
+     in the same form).  Doing this early simplifies the checking what
+     uses should be renamed.  */
+  for (gsi = gsi_start_phis (loop->header); !gsi_end_p (gsi); gsi_next (&gsi))
+    if (virtual_operand_p (gimple_phi_result (gsi_stmt (gsi))))
+      {
+	gimple phi = gsi_stmt (gsi);
+	for (gsi = gsi_start_phis (exit_e->dest);
+	     !gsi_end_p (gsi); gsi_next (&gsi))
+	  if (virtual_operand_p (gimple_phi_result (gsi_stmt (gsi))))
+	    break;
+	if (gsi_end_p (gsi))
+	  {
+	    tree new_vop = copy_ssa_name (PHI_RESULT (phi), NULL);
+	    gimple new_phi = create_phi_node (new_vop, exit_e->dest);
+	    tree vop = PHI_ARG_DEF_FROM_EDGE (phi, EDGE_SUCC (loop->latch, 0));
+	    imm_use_iterator imm_iter;
+	    gimple stmt;
+	    use_operand_p use_p;
+
+	    add_phi_arg (new_phi, vop, exit_e, UNKNOWN_LOCATION);
+	    gimple_phi_set_result (new_phi, new_vop);
+	    FOR_EACH_IMM_USE_STMT (stmt, imm_iter, vop)
+	      if (stmt != new_phi && gimple_bb (stmt) != loop->header)
+		FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
+		  SET_USE (use_p, new_vop);
+	  }
+	break;
+      }
+
+  /* 1. Generate a copy of LOOP and put it on E (E is the entry/exit of LOOP).
+        Resulting CFG would be:
+
+        first_loop:
+        do {
+        } while ...
+
+        second_loop:
+        do {
+        } while ...
+
+        orig_exit_bb:
+   */
+
+  if (!(new_loop = slpeel_tree_duplicate_loop_to_edge_cfg (loop, scalar_loop,
+							   e)))
+    {
+      loop_loc = find_loop_location (loop);
+      dump_printf_loc (MSG_MISSED_OPTIMIZATION, loop_loc,
+                       "tree_duplicate_loop_to_edge_cfg failed.\n");
+      return NULL;
+    }
+
+  if (MAY_HAVE_DEBUG_STMTS)
+    {
+      gcc_assert (!adjust_vec.exists ());
+      adjust_vec.create (32);
+    }
+
+  if (e == exit_e)
+    {
+      /* NEW_LOOP was placed after LOOP.  */
+      first_loop = loop;
+      second_loop = new_loop;
+    }
+  else
+    {
+      /* NEW_LOOP was placed before LOOP.  */
+      first_loop = new_loop;
+      second_loop = loop;
+    }
+
+  /* 2.  Add the guard code in one of the following ways:
+
+     2.a Add the guard that controls whether the first loop is executed.
+         This occurs when this function is invoked for prologue or epilogue
+	 generation and when the cost model check can be done at compile time.
+
+         Resulting CFG would be:
+
+         bb_before_first_loop:
+         if (FIRST_NITERS == 0) GOTO bb_before_second_loop
+                                GOTO first-loop
+
+         first_loop:
+         do {
+         } while ...
+
+         bb_before_second_loop:
+
+         second_loop:
+         do {
+         } while ...
+
+         orig_exit_bb:
+
+     2.b Add the cost model check that allows the prologue
+         to iterate for the entire unchanged scalar
+         iterations of the loop in the event that the cost
+         model indicates that the scalar loop is more
+         profitable than the vector one. This occurs when
+	 this function is invoked for prologue generation
+	 and the cost model check needs to be done at run
+	 time.
+
+         Resulting CFG after prologue peeling would be:
+
+         if (scalar_loop_iterations <= th)
+           FIRST_NITERS = scalar_loop_iterations
+
+         bb_before_first_loop:
+         if (FIRST_NITERS == 0) GOTO bb_before_second_loop
+                                GOTO first-loop
+
+         first_loop:
+         do {
+         } while ...
+
+         bb_before_second_loop:
+
+         second_loop:
+         do {
+         } while ...
+
+         orig_exit_bb:
+
+     2.c Add the cost model check that allows the epilogue
+         to iterate for the entire unchanged scalar
+         iterations of the loop in the event that the cost
+         model indicates that the scalar loop is more
+         profitable than the vector one. This occurs when
+	 this function is invoked for epilogue generation
+	 and the cost model check needs to be done at run
+	 time.  This check is combined with any pre-existing
+	 check in COND_EXPR to avoid versioning.
+
+         Resulting CFG after prologue peeling would be:
+
+         bb_before_first_loop:
+         if ((scalar_loop_iterations <= th)
+             ||
+             FIRST_NITERS == 0) GOTO bb_before_second_loop
+                                GOTO first-loop
+
+         first_loop:
+         do {
+         } while ...
+
+         bb_before_second_loop:
+
+         second_loop:
+         do {
+         } while ...
+
+         orig_exit_bb:
+  */
+
+  bb_before_first_loop = split_edge (loop_preheader_edge (first_loop));
+  /* Loop copying insterted a forwarder block for us here.  */
+  bb_before_second_loop = single_exit (first_loop)->dest;
+
+  probability_of_second_loop = (inverse_probability (first_guard_probability)
+			        + combine_probabilities (second_guard_probability,
+                                                         first_guard_probability));
+  /* Theoretically preheader edge of first loop and exit edge should have
+     same frequencies.  Loop exit probablities are however easy to get wrong.
+     It is safer to copy value from original loop entry.  */
+  bb_before_second_loop->frequency
+     = combine_probabilities (bb_before_first_loop->frequency,
+                              probability_of_second_loop);
+  bb_before_second_loop->count
+     = apply_probability (bb_before_first_loop->count,
+			  probability_of_second_loop);
+  single_succ_edge (bb_before_second_loop)->count
+     = bb_before_second_loop->count;
+
+  /* Epilogue peeling.  */
+  if (!update_first_loop_count)
+    {
+      loop_vec_info loop_vinfo = loop_vec_info_for_loop (loop);
+      tree scalar_loop_iters = LOOP_VINFO_NITERSM1 (loop_vinfo);
+      unsigned limit = LOOP_VINFO_VECT_FACTOR (loop_vinfo) - 1;
+      if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
+	limit = limit + 1;
+      if (check_profitability
+	  && th > limit)
+	limit = th;
+      pre_condition =
+	fold_build2 (LT_EXPR, boolean_type_node, scalar_loop_iters,
+		     build_int_cst (TREE_TYPE (scalar_loop_iters), limit));
+      if (cond_expr)
+	{
+	  pre_condition =
+	    fold_build2 (TRUTH_OR_EXPR, boolean_type_node,
+			 pre_condition,
+			 fold_build1 (TRUTH_NOT_EXPR, boolean_type_node,
+				      cond_expr));
+	}
+    }
+
+  /* Prologue peeling.  */
+  else
+    {
+      if (check_profitability)
+	set_prologue_iterations (bb_before_first_loop, first_niters,
+				 loop, th, first_guard_probability);
+
+      pre_condition =
+	fold_build2 (LE_EXPR, boolean_type_node, *first_niters,
+		     build_int_cst (TREE_TYPE (*first_niters), 0));
+    }
+
+  skip_e = slpeel_add_loop_guard (bb_before_first_loop, pre_condition,
+				  cond_expr_stmt_list,
+                                  bb_before_second_loop, bb_before_first_loop,
+				  inverse_probability (first_guard_probability));
+  scale_loop_profile (first_loop, first_guard_probability,
+		      check_profitability && (int)th > bound1 ? th : bound1);
+  slpeel_update_phi_nodes_for_guard1 (skip_e, first_loop,
+				      first_loop == new_loop,
+				      &new_exit_bb);
+
+
+  /* 3. Add the guard that controls whether the second loop is executed.
+        Resulting CFG would be:
+
+        bb_before_first_loop:
+        if (FIRST_NITERS == 0) GOTO bb_before_second_loop (skip first loop)
+                               GOTO first-loop
+
+        first_loop:
+        do {
+        } while ...
+
+        bb_between_loops:
+        if (FIRST_NITERS == NITERS) GOTO bb_after_second_loop (skip second loop)
+                                    GOTO bb_before_second_loop
+
+        bb_before_second_loop:
+
+        second_loop:
+        do {
+        } while ...
+
+        bb_after_second_loop:
+
+        orig_exit_bb:
+   */
+
+  bb_between_loops = new_exit_bb;
+  bb_after_second_loop = split_edge (single_exit (second_loop));
+
+  pre_condition =
+	fold_build2 (EQ_EXPR, boolean_type_node, *first_niters, niters);
+  skip_e = slpeel_add_loop_guard (bb_between_loops, pre_condition, NULL,
+                                  bb_after_second_loop, bb_before_first_loop,
+				  inverse_probability (second_guard_probability));
+  scale_loop_profile (second_loop, probability_of_second_loop, bound2);
+  slpeel_update_phi_nodes_for_guard2 (skip_e, second_loop,
+                                     second_loop == new_loop, &new_exit_bb);
+
+  /* 4. Make first-loop iterate FIRST_NITERS times, if requested.
+   */
+  if (update_first_loop_count)
+    slpeel_make_loop_iterate_ntimes (first_loop, *first_niters);
+
+  delete_update_ssa ();
+
+  adjust_vec_debug_stmts ();
+
+  return new_loop;
+}
+
+/* Function vect_get_loop_location.
+
+   Extract the location of the loop in the source code.
+   If the loop is not well formed for vectorization, an estimated
+   location is calculated.
+   Return the loop location if succeed and NULL if not.  */
+
+source_location
+find_loop_location (struct loop *loop)
+{
+  gimple stmt = NULL;
+  basic_block bb;
+  gimple_stmt_iterator si;
+
+  if (!loop)
+    return UNKNOWN_LOCATION;
+
+  stmt = get_loop_exit_condition (loop);
+
+  if (stmt
+      && LOCATION_LOCUS (gimple_location (stmt)) > BUILTINS_LOCATION)
+    return gimple_location (stmt);
+
+  /* If we got here the loop is probably not "well formed",
+     try to estimate the loop location */
+
+  if (!loop->header)
+    return UNKNOWN_LOCATION;
+
+  bb = loop->header;
+
+  for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
+    {
+      stmt = gsi_stmt (si);
+      if (LOCATION_LOCUS (gimple_location (stmt)) > BUILTINS_LOCATION)
+        return gimple_location (stmt);
+    }
+
+  return UNKNOWN_LOCATION;
+}
+
+
+/* Function vect_can_advance_ivs_p
+
+   In case the number of iterations that LOOP iterates is unknown at compile
+   time, an epilog loop will be generated, and the loop induction variables
+   (IVs) will be "advanced" to the value they are supposed to take just before
+   the epilog loop.  Here we check that the access function of the loop IVs
+   and the expression that represents the loop bound are simple enough.
+   These restrictions will be relaxed in the future.  */
+
+bool
+vect_can_advance_ivs_p (loop_vec_info loop_vinfo)
+{
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  basic_block bb = loop->header;
+  gimple phi;
+  gimple_stmt_iterator gsi;
+
+  /* Analyze phi functions of the loop header.  */
+
+  if (dump_enabled_p ())
+    dump_printf_loc (MSG_NOTE, vect_location, "vect_can_advance_ivs_p:\n");
+  for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      tree evolution_part;
+
+      phi = gsi_stmt (gsi);
+      if (dump_enabled_p ())
+	{
+          dump_printf_loc (MSG_NOTE, vect_location, "Analyze phi: ");
+          dump_gimple_stmt (MSG_NOTE, TDF_SLIM, phi, 0);
+          dump_printf (MSG_NOTE, "\n");
+	}
+
+      /* Skip virtual phi's. The data dependences that are associated with
+         virtual defs/uses (i.e., memory accesses) are analyzed elsewhere.  */
+
+      if (virtual_operand_p (PHI_RESULT (phi)))
+	{
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                             "virtual phi. skip.\n");
+	  continue;
+	}
+
+      /* Skip reduction phis.  */
+
+      if (STMT_VINFO_DEF_TYPE (vinfo_for_stmt (phi)) == vect_reduction_def)
+        {
+          if (dump_enabled_p ())
+            dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                             "reduc phi. skip.\n");
+          continue;
+        }
+
+      /* Analyze the evolution function.  */
+
+      evolution_part
+	= STMT_VINFO_LOOP_PHI_EVOLUTION_PART (vinfo_for_stmt (phi));
+      if (evolution_part == NULL_TREE)
+        {
+	  if (dump_enabled_p ())
+	    dump_printf (MSG_MISSED_OPTIMIZATION,
+			 "No access function or evolution.\n");
+	  return false;
+        }
+
+      /* FORNOW: We do not transform initial conditions of IVs
+	 which evolution functions are a polynomial of degree >= 2.  */
+
+      if (tree_is_chrec (evolution_part))
+	return false;
+    }
+
+  return true;
+}
+
+
+/*   Function vect_update_ivs_after_vectorizer.
+
+     "Advance" the induction variables of LOOP to the value they should take
+     after the execution of LOOP.  This is currently necessary because the
+     vectorizer does not handle induction variables that are used after the
+     loop.  Such a situation occurs when the last iterations of LOOP are
+     peeled, because:
+     1. We introduced new uses after LOOP for IVs that were not originally used
+        after LOOP: the IVs of LOOP are now used by an epilog loop.
+     2. LOOP is going to be vectorized; this means that it will iterate N/VF
+        times, whereas the loop IVs should be bumped N times.
+
+     Input:
+     - LOOP - a loop that is going to be vectorized. The last few iterations
+              of LOOP were peeled.
+     - NITERS - the number of iterations that LOOP executes (before it is
+                vectorized). i.e, the number of times the ivs should be bumped.
+     - UPDATE_E - a successor edge of LOOP->exit that is on the (only) path
+                  coming out from LOOP on which there are uses of the LOOP ivs
+		  (this is the path from LOOP->exit to epilog_loop->preheader).
+
+                  The new definitions of the ivs are placed in LOOP->exit.
+                  The phi args associated with the edge UPDATE_E in the bb
+                  UPDATE_E->dest are updated accordingly.
+
+     Assumption 1: Like the rest of the vectorizer, this function assumes
+     a single loop exit that has a single predecessor.
+
+     Assumption 2: The phi nodes in the LOOP header and in update_bb are
+     organized in the same order.
+
+     Assumption 3: The access function of the ivs is simple enough (see
+     vect_can_advance_ivs_p).  This assumption will be relaxed in the future.
+
+     Assumption 4: Exactly one of the successors of LOOP exit-bb is on a path
+     coming out of LOOP on which the ivs of LOOP are used (this is the path
+     that leads to the epilog loop; other paths skip the epilog loop).  This
+     path starts with the edge UPDATE_E, and its destination (denoted update_bb)
+     needs to have its phis updated.
+ */
+
+static void
+vect_update_ivs_after_vectorizer (loop_vec_info loop_vinfo, tree niters,
+				  edge update_e)
+{
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  basic_block exit_bb = single_exit (loop)->dest;
+  gimple phi, phi1;
+  gimple_stmt_iterator gsi, gsi1;
+  basic_block update_bb = update_e->dest;
+
+  gcc_checking_assert (vect_can_advance_ivs_p (loop_vinfo));
+
+  /* Make sure there exists a single-predecessor exit bb:  */
+  gcc_assert (single_pred_p (exit_bb));
+
+  for (gsi = gsi_start_phis (loop->header), gsi1 = gsi_start_phis (update_bb);
+       !gsi_end_p (gsi) && !gsi_end_p (gsi1);
+       gsi_next (&gsi), gsi_next (&gsi1))
+    {
+      tree init_expr;
+      tree step_expr, off;
+      tree type;
+      tree var, ni, ni_name;
+      gimple_stmt_iterator last_gsi;
+      stmt_vec_info stmt_info;
+
+      phi = gsi_stmt (gsi);
+      phi1 = gsi_stmt (gsi1);
+      if (dump_enabled_p ())
+        {
+          dump_printf_loc (MSG_NOTE, vect_location,
+                           "vect_update_ivs_after_vectorizer: phi: ");
+	  dump_gimple_stmt (MSG_NOTE, TDF_SLIM, phi, 0);
+          dump_printf (MSG_NOTE, "\n");
+        }
+
+      /* Skip virtual phi's.  */
+      if (virtual_operand_p (PHI_RESULT (phi)))
+	{
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                             "virtual phi. skip.\n");
+	  continue;
+	}
+
+      /* Skip reduction phis.  */
+      stmt_info = vinfo_for_stmt (phi);
+      if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def)
+        {
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                             "reduc phi. skip.\n");
+          continue;
+        }
+
+      type = TREE_TYPE (gimple_phi_result (phi));
+      step_expr = STMT_VINFO_LOOP_PHI_EVOLUTION_PART (stmt_info);
+      step_expr = unshare_expr (step_expr);
+
+      /* FORNOW: We do not support IVs whose evolution function is a polynomial
+         of degree >= 2 or exponential.  */
+      gcc_assert (!tree_is_chrec (step_expr));
+
+      init_expr = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop));
+
+      off = fold_build2 (MULT_EXPR, TREE_TYPE (step_expr),
+			 fold_convert (TREE_TYPE (step_expr), niters),
+			 step_expr);
+      if (POINTER_TYPE_P (type))
+	ni = fold_build_pointer_plus (init_expr, off);
+      else
+	ni = fold_build2 (PLUS_EXPR, type,
+			  init_expr, fold_convert (type, off));
+
+      var = create_tmp_var (type, "tmp");
+
+      last_gsi = gsi_last_bb (exit_bb);
+      ni_name = force_gimple_operand_gsi (&last_gsi, ni, false, var,
+					  true, GSI_SAME_STMT);
+
+      /* Fix phi expressions in the successor bb.  */
+      adjust_phi_and_debug_stmts (phi1, update_e, ni_name);
+    }
+}
+
+/* Function vect_do_peeling_for_loop_bound
+
+   Peel the last iterations of the loop represented by LOOP_VINFO.
+   The peeled iterations form a new epilog loop.  Given that the loop now
+   iterates NITERS times, the new epilog loop iterates
+   NITERS % VECTORIZATION_FACTOR times.
+
+   The original loop will later be made to iterate
+   NITERS / VECTORIZATION_FACTOR times (this value is placed into RATIO).
+
+   COND_EXPR and COND_EXPR_STMT_LIST are combined with a new generated
+   test.  */
+
+void
+vect_do_peeling_for_loop_bound (loop_vec_info loop_vinfo,
+				tree ni_name, tree ratio_mult_vf_name,
+				unsigned int th, bool check_profitability)
+{
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  struct loop *scalar_loop = LOOP_VINFO_SCALAR_LOOP (loop_vinfo);
+  struct loop *new_loop;
+  edge update_e;
+  basic_block preheader;
+  int loop_num;
+  int max_iter;
+  tree cond_expr = NULL_TREE;
+  gimple_seq cond_expr_stmt_list = NULL;
+
+  if (dump_enabled_p ())
+    dump_printf_loc (MSG_NOTE, vect_location,
+                     "=== vect_do_peeling_for_loop_bound ===\n");
+
+  initialize_original_copy_tables ();
+
+  loop_num  = loop->num;
+
+  new_loop
+    = slpeel_tree_peel_loop_to_edge (loop, scalar_loop, single_exit (loop),
+				     &ratio_mult_vf_name, ni_name, false,
+				     th, check_profitability,
+				     cond_expr, cond_expr_stmt_list,
+				     0, LOOP_VINFO_VECT_FACTOR (loop_vinfo));
+  gcc_assert (new_loop);
+  gcc_assert (loop_num == loop->num);
+#ifdef ENABLE_CHECKING
+  slpeel_verify_cfg_after_peeling (loop, new_loop);
+#endif
+
+  /* A guard that controls whether the new_loop is to be executed or skipped
+     is placed in LOOP->exit.  LOOP->exit therefore has two successors - one
+     is the preheader of NEW_LOOP, where the IVs from LOOP are used.  The other
+     is a bb after NEW_LOOP, where these IVs are not used.  Find the edge that
+     is on the path where the LOOP IVs are used and need to be updated.  */
+
+  preheader = loop_preheader_edge (new_loop)->src;
+  if (EDGE_PRED (preheader, 0)->src == single_exit (loop)->dest)
+    update_e = EDGE_PRED (preheader, 0);
+  else
+    update_e = EDGE_PRED (preheader, 1);
+
+  /* Update IVs of original loop as if they were advanced
+     by ratio_mult_vf_name steps.  */
+  vect_update_ivs_after_vectorizer (loop_vinfo, ratio_mult_vf_name, update_e);
+
+  /* For vectorization factor N, we need to copy last N-1 values in epilogue
+     and this means N-2 loopback edge executions.
+
+     PEELING_FOR_GAPS works by subtracting last iteration and thus the epilogue
+     will execute at least LOOP_VINFO_VECT_FACTOR times.  */
+  max_iter = (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
+	      ? LOOP_VINFO_VECT_FACTOR (loop_vinfo) * 2
+	      : LOOP_VINFO_VECT_FACTOR (loop_vinfo)) - 2;
+  if (check_profitability)
+    max_iter = MAX (max_iter, (int) th - 1);
+  record_niter_bound (new_loop, double_int::from_shwi (max_iter), false, true);
+  dump_printf (MSG_NOTE,
+               "Setting upper bound of nb iterations for epilogue "
+               "loop to %d\n", max_iter);
+
+  /* After peeling we have to reset scalar evolution analyzer.  */
+  scev_reset ();
+
+  free_original_copy_tables ();
+}
+
+
+/* Function vect_gen_niters_for_prolog_loop
+
+   Set the number of iterations for the loop represented by LOOP_VINFO
+   to the minimum between LOOP_NITERS (the original iteration count of the loop)
+   and the misalignment of DR - the data reference recorded in
+   LOOP_VINFO_UNALIGNED_DR (LOOP_VINFO).  As a result, after the execution of
+   this loop, the data reference DR will refer to an aligned location.
+
+   The following computation is generated:
+
+   If the misalignment of DR is known at compile time:
+     addr_mis = int mis = DR_MISALIGNMENT (dr);
+   Else, compute address misalignment in bytes:
+     addr_mis = addr & (vectype_align - 1)
+
+   prolog_niters = min (LOOP_NITERS, ((VF - addr_mis/elem_size)&(VF-1))/step)
+
+   (elem_size = element type size; an element is the scalar element whose type
+   is the inner type of the vectype)
+
+   When the step of the data-ref in the loop is not 1 (as in interleaved data
+   and SLP), the number of iterations of the prolog must be divided by the step
+   (which is equal to the size of interleaved group).
+
+   The above formulas assume that VF == number of elements in the vector. This
+   may not hold when there are multiple-types in the loop.
+   In this case, for some data-references in the loop the VF does not represent
+   the number of elements that fit in the vector.  Therefore, instead of VF we
+   use TYPE_VECTOR_SUBPARTS.  */
+
+static tree
+vect_gen_niters_for_prolog_loop (loop_vec_info loop_vinfo, tree loop_niters, int *bound)
+{
+  struct data_reference *dr = LOOP_VINFO_UNALIGNED_DR (loop_vinfo);
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  tree var;
+  gimple_seq stmts;
+  tree iters, iters_name;
+  edge pe;
+  basic_block new_bb;
+  gimple dr_stmt = DR_STMT (dr);
+  stmt_vec_info stmt_info = vinfo_for_stmt (dr_stmt);
+  tree vectype = STMT_VINFO_VECTYPE (stmt_info);
+  int vectype_align = TYPE_ALIGN (vectype) / BITS_PER_UNIT;
+  tree niters_type = TREE_TYPE (loop_niters);
+  int nelements = TYPE_VECTOR_SUBPARTS (vectype);
+
+  pe = loop_preheader_edge (loop);
+
+  if (LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) > 0)
+    {
+      int npeel = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);
+
+      if (dump_enabled_p ())
+        dump_printf_loc (MSG_NOTE, vect_location,
+                         "known peeling = %d.\n", npeel);
+
+      iters = build_int_cst (niters_type, npeel);
+      *bound = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);
+    }
+  else
+    {
+      gimple_seq new_stmts = NULL;
+      bool negative = tree_int_cst_compare (DR_STEP (dr), size_zero_node) < 0;
+      tree offset = negative
+	  ? size_int (-TYPE_VECTOR_SUBPARTS (vectype) + 1) : NULL_TREE;
+      tree start_addr = vect_create_addr_base_for_vector_ref (dr_stmt,
+						&new_stmts, offset, loop);
+      tree type = unsigned_type_for (TREE_TYPE (start_addr));
+      tree vectype_align_minus_1 = build_int_cst (type, vectype_align - 1);
+      HOST_WIDE_INT elem_size =
+                int_cst_value (TYPE_SIZE_UNIT (TREE_TYPE (vectype)));
+      tree elem_size_log = build_int_cst (type, exact_log2 (elem_size));
+      tree nelements_minus_1 = build_int_cst (type, nelements - 1);
+      tree nelements_tree = build_int_cst (type, nelements);
+      tree byte_misalign;
+      tree elem_misalign;
+
+      new_bb = gsi_insert_seq_on_edge_immediate (pe, new_stmts);
+      gcc_assert (!new_bb);
+
+      /* Create:  byte_misalign = addr & (vectype_align - 1)  */
+      byte_misalign =
+        fold_build2 (BIT_AND_EXPR, type, fold_convert (type, start_addr), 
+                     vectype_align_minus_1);
+
+      /* Create:  elem_misalign = byte_misalign / element_size  */
+      elem_misalign =
+        fold_build2 (RSHIFT_EXPR, type, byte_misalign, elem_size_log);
+
+      /* Create:  (niters_type) (nelements - elem_misalign)&(nelements - 1)  */
+      if (negative)
+	iters = fold_build2 (MINUS_EXPR, type, elem_misalign, nelements_tree);
+      else
+	iters = fold_build2 (MINUS_EXPR, type, nelements_tree, elem_misalign);
+      iters = fold_build2 (BIT_AND_EXPR, type, iters, nelements_minus_1);
+      iters = fold_convert (niters_type, iters);
+      *bound = nelements;
+    }
+
+  /* Create:  prolog_loop_niters = min (iters, loop_niters) */
+  /* If the loop bound is known at compile time we already verified that it is
+     greater than vf; since the misalignment ('iters') is at most vf, there's
+     no need to generate the MIN_EXPR in this case.  */
+  if (TREE_CODE (loop_niters) != INTEGER_CST)
+    iters = fold_build2 (MIN_EXPR, niters_type, iters, loop_niters);
+
+  if (dump_enabled_p ())
+    {
+      dump_printf_loc (MSG_NOTE, vect_location,
+                       "niters for prolog loop: ");
+      dump_generic_expr (MSG_NOTE, TDF_SLIM, iters);
+      dump_printf (MSG_NOTE, "\n");
+    }
+
+  var = create_tmp_var (niters_type, "prolog_loop_niters");
+  stmts = NULL;
+  iters_name = force_gimple_operand (iters, &stmts, false, var);
+
+  /* Insert stmt on loop preheader edge.  */
+  if (stmts)
+    {
+      basic_block new_bb = gsi_insert_seq_on_edge_immediate (pe, stmts);
+      gcc_assert (!new_bb);
+    }
+
+  return iters_name;
+}
+
+
+/* Function vect_update_init_of_dr
+
+   NITERS iterations were peeled from LOOP.  DR represents a data reference
+   in LOOP.  This function updates the information recorded in DR to
+   account for the fact that the first NITERS iterations had already been
+   executed.  Specifically, it updates the OFFSET field of DR.  */
+
+static void
+vect_update_init_of_dr (struct data_reference *dr, tree niters)
+{
+  tree offset = DR_OFFSET (dr);
+
+  niters = fold_build2 (MULT_EXPR, sizetype,
+			fold_convert (sizetype, niters),
+			fold_convert (sizetype, DR_STEP (dr)));
+  offset = fold_build2 (PLUS_EXPR, sizetype,
+			fold_convert (sizetype, offset), niters);
+  DR_OFFSET (dr) = offset;
+}
+
+
+/* Function vect_update_inits_of_drs
+
+   NITERS iterations were peeled from the loop represented by LOOP_VINFO.
+   This function updates the information recorded for the data references in
+   the loop to account for the fact that the first NITERS iterations had
+   already been executed.  Specifically, it updates the initial_condition of
+   the access_function of all the data_references in the loop.  */
+
+static void
+vect_update_inits_of_drs (loop_vec_info loop_vinfo, tree niters)
+{
+  unsigned int i;
+  vec<data_reference_p> datarefs = LOOP_VINFO_DATAREFS (loop_vinfo);
+  struct data_reference *dr;
+ 
+ if (dump_enabled_p ())
+    dump_printf_loc (MSG_NOTE, vect_location,
+                     "=== vect_update_inits_of_dr ===\n");
+
+  FOR_EACH_VEC_ELT (datarefs, i, dr)
+    vect_update_init_of_dr (dr, niters);
+}
+
+
+/* Function vect_do_peeling_for_alignment
+
+   Peel the first 'niters' iterations of the loop represented by LOOP_VINFO.
+   'niters' is set to the misalignment of one of the data references in the
+   loop, thereby forcing it to refer to an aligned location at the beginning
+   of the execution of this loop.  The data reference for which we are
+   peeling is recorded in LOOP_VINFO_UNALIGNED_DR.  */
+
+void
+vect_do_peeling_for_alignment (loop_vec_info loop_vinfo, tree ni_name,
+			       unsigned int th, bool check_profitability)
+{
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  struct loop *scalar_loop = LOOP_VINFO_SCALAR_LOOP (loop_vinfo);
+  tree niters_of_prolog_loop;
+  tree wide_prolog_niters;
+  struct loop *new_loop;
+  int max_iter;
+  int bound = 0;
+
+  if (dump_enabled_p ())
+    dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, vect_location,
+                     "loop peeled for vectorization to enhance"
+                     " alignment\n");
+
+  initialize_original_copy_tables ();
+
+  gimple_seq stmts = NULL;
+  gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts);
+  niters_of_prolog_loop = vect_gen_niters_for_prolog_loop (loop_vinfo,
+							   ni_name,
+							   &bound);
+
+  /* Peel the prolog loop and iterate it niters_of_prolog_loop.  */
+  new_loop =
+    slpeel_tree_peel_loop_to_edge (loop, scalar_loop,
+				   loop_preheader_edge (loop),
+				   &niters_of_prolog_loop, ni_name, true,
+				   th, check_profitability, NULL_TREE, NULL,
+				   bound, 0);
+
+  gcc_assert (new_loop);
+#ifdef ENABLE_CHECKING
+  slpeel_verify_cfg_after_peeling (new_loop, loop);
+#endif
+  /* For vectorization factor N, we need to copy at most N-1 values 
+     for alignment and this means N-2 loopback edge executions.  */
+  max_iter = LOOP_VINFO_VECT_FACTOR (loop_vinfo) - 2;
+  if (check_profitability)
+    max_iter = MAX (max_iter, (int) th - 1);
+  record_niter_bound (new_loop, double_int::from_shwi (max_iter), false, true);
+  dump_printf (MSG_NOTE,
+               "Setting upper bound of nb iterations for prologue "
+               "loop to %d\n", max_iter);
+
+  /* Update number of times loop executes.  */
+  LOOP_VINFO_NITERS (loop_vinfo) = fold_build2 (MINUS_EXPR,
+		TREE_TYPE (ni_name), ni_name, niters_of_prolog_loop);
+  LOOP_VINFO_NITERSM1 (loop_vinfo) = fold_build2 (MINUS_EXPR,
+		TREE_TYPE (ni_name),
+		LOOP_VINFO_NITERSM1 (loop_vinfo), niters_of_prolog_loop);
+
+  if (types_compatible_p (sizetype, TREE_TYPE (niters_of_prolog_loop)))
+    wide_prolog_niters = niters_of_prolog_loop;
+  else
+    {
+      gimple_seq seq = NULL;
+      edge pe = loop_preheader_edge (loop);
+      tree wide_iters = fold_convert (sizetype, niters_of_prolog_loop);
+      tree var = create_tmp_var (sizetype, "prolog_loop_adjusted_niters");
+      wide_prolog_niters = force_gimple_operand (wide_iters, &seq, false,
+                                                 var);
+      if (seq)
+	{
+	  /* Insert stmt on loop preheader edge.  */
+          basic_block new_bb = gsi_insert_seq_on_edge_immediate (pe, seq);
+          gcc_assert (!new_bb);
+        }
+    }
+
+  /* Update the init conditions of the access functions of all data refs.  */
+  vect_update_inits_of_drs (loop_vinfo, wide_prolog_niters);
+
+  /* After peeling we have to reset scalar evolution analyzer.  */
+  scev_reset ();
+
+  free_original_copy_tables ();
+}
+
+
+/* Function vect_create_cond_for_align_checks.
+
+   Create a conditional expression that represents the alignment checks for
+   all of data references (array element references) whose alignment must be
+   checked at runtime.
+
+   Input:
+   COND_EXPR  - input conditional expression.  New conditions will be chained
+                with logical AND operation.
+   LOOP_VINFO - two fields of the loop information are used.
+                LOOP_VINFO_PTR_MASK is the mask used to check the alignment.
+                LOOP_VINFO_MAY_MISALIGN_STMTS contains the refs to be checked.
+
+   Output:
+   COND_EXPR_STMT_LIST - statements needed to construct the conditional
+                         expression.
+   The returned value is the conditional expression to be used in the if
+   statement that controls which version of the loop gets executed at runtime.
+
+   The algorithm makes two assumptions:
+     1) The number of bytes "n" in a vector is a power of 2.
+     2) An address "a" is aligned if a%n is zero and that this
+        test can be done as a&(n-1) == 0.  For example, for 16
+        byte vectors the test is a&0xf == 0.  */
+
+static void
+vect_create_cond_for_align_checks (loop_vec_info loop_vinfo,
+                                   tree *cond_expr,
+				   gimple_seq *cond_expr_stmt_list)
+{
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  vec<gimple> may_misalign_stmts
+    = LOOP_VINFO_MAY_MISALIGN_STMTS (loop_vinfo);
+  gimple ref_stmt;
+  int mask = LOOP_VINFO_PTR_MASK (loop_vinfo);
+  tree mask_cst;
+  unsigned int i;
+  tree int_ptrsize_type;
+  char tmp_name[20];
+  tree or_tmp_name = NULL_TREE;
+  tree and_tmp_name;
+  gimple and_stmt;
+  tree ptrsize_zero;
+  tree part_cond_expr;
+
+  /* Check that mask is one less than a power of 2, i.e., mask is
+     all zeros followed by all ones.  */
+  gcc_assert ((mask != 0) && ((mask & (mask+1)) == 0));
+
+  int_ptrsize_type = signed_type_for (ptr_type_node);
+
+  /* Create expression (mask & (dr_1 || ... || dr_n)) where dr_i is the address
+     of the first vector of the i'th data reference. */
+
+  FOR_EACH_VEC_ELT (may_misalign_stmts, i, ref_stmt)
+    {
+      gimple_seq new_stmt_list = NULL;
+      tree addr_base;
+      tree addr_tmp_name;
+      tree new_or_tmp_name;
+      gimple addr_stmt, or_stmt;
+      stmt_vec_info stmt_vinfo = vinfo_for_stmt (ref_stmt);
+      tree vectype = STMT_VINFO_VECTYPE (stmt_vinfo);
+      bool negative = tree_int_cst_compare
+	(DR_STEP (STMT_VINFO_DATA_REF (stmt_vinfo)), size_zero_node) < 0;
+      tree offset = negative
+	? size_int (-TYPE_VECTOR_SUBPARTS (vectype) + 1) : NULL_TREE;
+
+      /* create: addr_tmp = (int)(address_of_first_vector) */
+      addr_base =
+	vect_create_addr_base_for_vector_ref (ref_stmt, &new_stmt_list,
+					      offset, loop);
+      if (new_stmt_list != NULL)
+	gimple_seq_add_seq (cond_expr_stmt_list, new_stmt_list);
+
+      sprintf (tmp_name, "addr2int%d", i);
+      addr_tmp_name = make_temp_ssa_name (int_ptrsize_type, NULL, tmp_name);
+      addr_stmt = gimple_build_assign_with_ops (NOP_EXPR, addr_tmp_name,
+						addr_base, NULL_TREE);
+      gimple_seq_add_stmt (cond_expr_stmt_list, addr_stmt);
+
+      /* The addresses are OR together.  */
+
+      if (or_tmp_name != NULL_TREE)
+        {
+          /* create: or_tmp = or_tmp | addr_tmp */
+          sprintf (tmp_name, "orptrs%d", i);
+	  new_or_tmp_name = make_temp_ssa_name (int_ptrsize_type, NULL, tmp_name);
+	  or_stmt = gimple_build_assign_with_ops (BIT_IOR_EXPR,
+						  new_or_tmp_name,
+						  or_tmp_name, addr_tmp_name);
+	  gimple_seq_add_stmt (cond_expr_stmt_list, or_stmt);
+          or_tmp_name = new_or_tmp_name;
+        }
+      else
+        or_tmp_name = addr_tmp_name;
+
+    } /* end for i */
+
+  mask_cst = build_int_cst (int_ptrsize_type, mask);
+
+  /* create: and_tmp = or_tmp & mask  */
+  and_tmp_name = make_temp_ssa_name (int_ptrsize_type, NULL, "andmask");
+
+  and_stmt = gimple_build_assign_with_ops (BIT_AND_EXPR, and_tmp_name,
+					   or_tmp_name, mask_cst);
+  gimple_seq_add_stmt (cond_expr_stmt_list, and_stmt);
+
+  /* Make and_tmp the left operand of the conditional test against zero.
+     if and_tmp has a nonzero bit then some address is unaligned.  */
+  ptrsize_zero = build_int_cst (int_ptrsize_type, 0);
+  part_cond_expr = fold_build2 (EQ_EXPR, boolean_type_node,
+				and_tmp_name, ptrsize_zero);
+  if (*cond_expr)
+    *cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
+			      *cond_expr, part_cond_expr);
+  else
+    *cond_expr = part_cond_expr;
+}
+
+/* Function vect_create_cond_for_alias_checks.
+
+   Create a conditional expression that represents the run-time checks for
+   overlapping of address ranges represented by a list of data references
+   relations passed as input.
+
+   Input:
+   COND_EXPR  - input conditional expression.  New conditions will be chained
+                with logical AND operation.  If it is NULL, then the function
+                is used to return the number of alias checks.
+   LOOP_VINFO - field LOOP_VINFO_MAY_ALIAS_STMTS contains the list of ddrs
+	        to be checked.
+
+   Output:
+   COND_EXPR - conditional expression.
+
+   The returned COND_EXPR is the conditional expression to be used in the if
+   statement that controls which version of the loop gets executed at runtime.
+*/
+
+void
+vect_create_cond_for_alias_checks (loop_vec_info loop_vinfo, tree * cond_expr)
+{
+  vec<dr_with_seg_len_pair_t> comp_alias_ddrs =
+    LOOP_VINFO_COMP_ALIAS_DDRS (loop_vinfo);
+  tree part_cond_expr;
+
+  /* Create expression
+     ((store_ptr_0 + store_segment_length_0) <= load_ptr_0)
+     || (load_ptr_0 + load_segment_length_0) <= store_ptr_0))
+     &&
+     ...
+     &&
+     ((store_ptr_n + store_segment_length_n) <= load_ptr_n)
+     || (load_ptr_n + load_segment_length_n) <= store_ptr_n))  */
+
+  if (comp_alias_ddrs.is_empty ())
+    return;
+
+  for (size_t i = 0, s = comp_alias_ddrs.length (); i < s; ++i)
+    {
+      const dr_with_seg_len& dr_a = comp_alias_ddrs[i].first;
+      const dr_with_seg_len& dr_b = comp_alias_ddrs[i].second;
+      tree segment_length_a = dr_a.seg_len;
+      tree segment_length_b = dr_b.seg_len;
+
+      tree addr_base_a
+	= fold_build_pointer_plus (DR_BASE_ADDRESS (dr_a.dr), dr_a.offset);
+      tree addr_base_b
+	= fold_build_pointer_plus (DR_BASE_ADDRESS (dr_b.dr), dr_b.offset);
+
+      if (dump_enabled_p ())
+	{
+	  dump_printf_loc (MSG_NOTE, vect_location,
+			   "create runtime check for data references ");
+	  dump_generic_expr (MSG_NOTE, TDF_SLIM, DR_REF (dr_a.dr));
+	  dump_printf (MSG_NOTE, " and ");
+	  dump_generic_expr (MSG_NOTE, TDF_SLIM, DR_REF (dr_b.dr));
+	  dump_printf (MSG_NOTE, "\n");
+	}
+
+      tree seg_a_min = addr_base_a;
+      tree seg_a_max = fold_build_pointer_plus (addr_base_a, segment_length_a);
+      /* For negative step, we need to adjust address range by TYPE_SIZE_UNIT
+	 bytes, e.g., int a[3] -> a[1] range is [a+4, a+16) instead of
+	 [a, a+12) */
+      if (tree_int_cst_compare (DR_STEP (dr_a.dr), size_zero_node) < 0)
+	{
+	  tree unit_size = TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (dr_a.dr)));
+	  seg_a_min = fold_build_pointer_plus (seg_a_max, unit_size);
+	  seg_a_max = fold_build_pointer_plus (addr_base_a, unit_size);
+	}
+
+      tree seg_b_min = addr_base_b;
+      tree seg_b_max = fold_build_pointer_plus (addr_base_b, segment_length_b);
+      if (tree_int_cst_compare (DR_STEP (dr_b.dr), size_zero_node) < 0)
+	{
+	  tree unit_size = TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (dr_b.dr)));
+	  seg_b_min = fold_build_pointer_plus (seg_b_max, unit_size);
+	  seg_b_max = fold_build_pointer_plus (addr_base_b, unit_size);
+	}
+
+      part_cond_expr =
+      	fold_build2 (TRUTH_OR_EXPR, boolean_type_node,
+	  fold_build2 (LE_EXPR, boolean_type_node, seg_a_max, seg_b_min),
+	  fold_build2 (LE_EXPR, boolean_type_node, seg_b_max, seg_a_min));
+
+      if (*cond_expr)
+	*cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
+				  *cond_expr, part_cond_expr);
+      else
+	*cond_expr = part_cond_expr;
+    }
+
+  if (dump_enabled_p ())
+    dump_printf_loc (MSG_NOTE, vect_location,
+		     "created %u versioning for alias checks.\n",
+		     comp_alias_ddrs.length ());
+
+  comp_alias_ddrs.release ();
+}
+
+
+/* Function vect_loop_versioning.
+
+   If the loop has data references that may or may not be aligned or/and
+   has data reference relations whose independence was not proven then
+   two versions of the loop need to be generated, one which is vectorized
+   and one which isn't.  A test is then generated to control which of the
+   loops is executed.  The test checks for the alignment of all of the
+   data references that may or may not be aligned.  An additional
+   sequence of runtime tests is generated for each pairs of DDRs whose
+   independence was not proven.  The vectorized version of loop is
+   executed only if both alias and alignment tests are passed.
+
+   The test generated to check which version of loop is executed
+   is modified to also check for profitability as indicated by the
+   cost model initially.
+
+   The versioning precondition(s) are placed in *COND_EXPR and
+   *COND_EXPR_STMT_LIST.  */
+
+void
+vect_loop_versioning (loop_vec_info loop_vinfo,
+		      unsigned int th, bool check_profitability)
+{
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  struct loop *scalar_loop = LOOP_VINFO_SCALAR_LOOP (loop_vinfo);
+  basic_block condition_bb;
+  gimple_stmt_iterator gsi, cond_exp_gsi;
+  basic_block merge_bb;
+  basic_block new_exit_bb;
+  edge new_exit_e, e;
+  gimple orig_phi, new_phi;
+  tree cond_expr = NULL_TREE;
+  gimple_seq cond_expr_stmt_list = NULL;
+  tree arg;
+  unsigned prob = 4 * REG_BR_PROB_BASE / 5;
+  gimple_seq gimplify_stmt_list = NULL;
+  tree scalar_loop_iters = LOOP_VINFO_NITERS (loop_vinfo);
+  bool version_align = LOOP_REQUIRES_VERSIONING_FOR_ALIGNMENT (loop_vinfo);
+  bool version_alias = LOOP_REQUIRES_VERSIONING_FOR_ALIAS (loop_vinfo);
+
+  if (check_profitability)
+    {
+      cond_expr = fold_build2 (GT_EXPR, boolean_type_node, scalar_loop_iters,
+			       build_int_cst (TREE_TYPE (scalar_loop_iters), th));
+      cond_expr = force_gimple_operand_1 (cond_expr, &cond_expr_stmt_list,
+					  is_gimple_condexpr, NULL_TREE);
+    }
+
+  if (version_align)
+    vect_create_cond_for_align_checks (loop_vinfo, &cond_expr,
+				       &cond_expr_stmt_list);
+
+  if (version_alias)
+    vect_create_cond_for_alias_checks (loop_vinfo, &cond_expr);
+
+  cond_expr = force_gimple_operand_1 (cond_expr, &gimplify_stmt_list,
+				      is_gimple_condexpr, NULL_TREE);
+  gimple_seq_add_seq (&cond_expr_stmt_list, gimplify_stmt_list);
+
+  initialize_original_copy_tables ();
+  if (scalar_loop)
+    {
+      edge scalar_e;
+      basic_block preheader, scalar_preheader;
+
+      /* We don't want to scale SCALAR_LOOP's frequencies, we need to
+	 scale LOOP's frequencies instead.  */
+      loop_version (scalar_loop, cond_expr, &condition_bb,
+		    prob, REG_BR_PROB_BASE, REG_BR_PROB_BASE - prob, true);
+      scale_loop_frequencies (loop, prob, REG_BR_PROB_BASE);
+      /* CONDITION_BB was created above SCALAR_LOOP's preheader,
+	 while we need to move it above LOOP's preheader.  */
+      e = loop_preheader_edge (loop);
+      scalar_e = loop_preheader_edge (scalar_loop);
+      gcc_assert (empty_block_p (e->src)
+		  && single_pred_p (e->src));
+      gcc_assert (empty_block_p (scalar_e->src)
+		  && single_pred_p (scalar_e->src));
+      gcc_assert (single_pred_p (condition_bb));
+      preheader = e->src;
+      scalar_preheader = scalar_e->src;
+      scalar_e = find_edge (condition_bb, scalar_preheader);
+      e = single_pred_edge (preheader);
+      redirect_edge_and_branch_force (single_pred_edge (condition_bb),
+				      scalar_preheader);
+      redirect_edge_and_branch_force (scalar_e, preheader);
+      redirect_edge_and_branch_force (e, condition_bb);
+      set_immediate_dominator (CDI_DOMINATORS, condition_bb,
+			       single_pred (condition_bb));
+      set_immediate_dominator (CDI_DOMINATORS, scalar_preheader,
+			       single_pred (scalar_preheader));
+      set_immediate_dominator (CDI_DOMINATORS, preheader,
+			       condition_bb);
+    }
+  else
+    loop_version (loop, cond_expr, &condition_bb,
+		  prob, prob, REG_BR_PROB_BASE - prob, true);
+
+  if (LOCATION_LOCUS (vect_location) != UNKNOWN_LOCATION
+      && dump_enabled_p ())
+    {
+      if (version_alias)
+        dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, vect_location,
+                         "loop versioned for vectorization because of "
+			 "possible aliasing\n");
+      if (version_align)
+        dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, vect_location,
+                         "loop versioned for vectorization to enhance "
+			 "alignment\n");
+
+    }
+  free_original_copy_tables ();
+
+  /* Loop versioning violates an assumption we try to maintain during
+     vectorization - that the loop exit block has a single predecessor.
+     After versioning, the exit block of both loop versions is the same
+     basic block (i.e. it has two predecessors). Just in order to simplify
+     following transformations in the vectorizer, we fix this situation
+     here by adding a new (empty) block on the exit-edge of the loop,
+     with the proper loop-exit phis to maintain loop-closed-form.
+     If loop versioning wasn't done from loop, but scalar_loop instead,
+     merge_bb will have already just a single successor.  */
+
+  merge_bb = single_exit (loop)->dest;
+  if (scalar_loop == NULL || EDGE_COUNT (merge_bb->preds) >= 2)
+    {
+      gcc_assert (EDGE_COUNT (merge_bb->preds) >= 2);
+      new_exit_bb = split_edge (single_exit (loop));
+      new_exit_e = single_exit (loop);
+      e = EDGE_SUCC (new_exit_bb, 0);
+
+      for (gsi = gsi_start_phis (merge_bb); !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  tree new_res;
+	  orig_phi = gsi_stmt (gsi);
+	  new_res = copy_ssa_name (PHI_RESULT (orig_phi), NULL);
+	  new_phi = create_phi_node (new_res, new_exit_bb);
+	  arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, e);
+	  add_phi_arg (new_phi, arg, new_exit_e,
+		       gimple_phi_arg_location_from_edge (orig_phi, e));
+	  adjust_phi_and_debug_stmts (orig_phi, e, PHI_RESULT (new_phi));
+	}
+    }
+
+  /* End loop-exit-fixes after versioning.  */
+
+  if (cond_expr_stmt_list)
+    {
+      cond_exp_gsi = gsi_last_bb (condition_bb);
+      gsi_insert_seq_before (&cond_exp_gsi, cond_expr_stmt_list,
+			     GSI_SAME_STMT);
+    }
+  update_ssa (TODO_update_ssa);
+}