GCC 4.2.0 release.

1 files changed, 2090 insertions, 0 deletions

diff --git a/contrib/gcc/tree-vectorizer.c b/contrib/gcc/tree-vectorizer.c
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+/* Loop Vectorization
+   Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+   Contributed by Dorit Naishlos <dorit@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 2, 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 COPYING.  If not, write to the Free
+Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA.  */
+
+/* Loop Vectorization Pass.
+
+   This pass tries to vectorize loops. This first implementation focuses on
+   simple inner-most loops, with no conditional control flow, and a set of
+   simple operations which vector form can be expressed using existing
+   tree codes (PLUS, MULT etc).
+
+   For example, the vectorizer transforms the following simple loop:
+
+	short a[N]; short b[N]; short c[N]; int i;
+
+	for (i=0; i<N; i++){
+	  a[i] = b[i] + c[i];
+	}
+
+   as if it was manually vectorized by rewriting the source code into:
+
+	typedef int __attribute__((mode(V8HI))) v8hi;
+	short a[N];  short b[N]; short c[N];   int i;
+	v8hi *pa = (v8hi*)a, *pb = (v8hi*)b, *pc = (v8hi*)c;
+	v8hi va, vb, vc;
+
+	for (i=0; i<N/8; i++){
+	  vb = pb[i];
+	  vc = pc[i];
+	  va = vb + vc;
+	  pa[i] = va;
+	}
+
+	The main entry to this pass is vectorize_loops(), in which
+   the vectorizer applies a set of analyses on a given set of loops,
+   followed by the actual vectorization transformation for the loops that
+   had successfully passed the analysis phase.
+
+	Throughout this pass we make a distinction between two types of
+   data: scalars (which are represented by SSA_NAMES), and memory references
+   ("data-refs"). These two types of data require different handling both 
+   during analysis and transformation. The types of data-refs that the 
+   vectorizer currently supports are ARRAY_REFS which base is an array DECL 
+   (not a pointer), and INDIRECT_REFS through pointers; both array and pointer
+   accesses are required to have a  simple (consecutive) access pattern.
+
+   Analysis phase:
+   ===============
+	The driver for the analysis phase is vect_analyze_loop_nest().
+   It applies a set of analyses, some of which rely on the scalar evolution 
+   analyzer (scev) developed by Sebastian Pop.
+
+	During the analysis phase the vectorizer records some information
+   per stmt in a "stmt_vec_info" struct which is attached to each stmt in the 
+   loop, as well as general information about the loop as a whole, which is
+   recorded in a "loop_vec_info" struct attached to each loop.
+
+   Transformation phase:
+   =====================
+	The loop transformation phase scans all the stmts in the loop, and
+   creates a vector stmt (or a sequence of stmts) for each scalar stmt S in
+   the loop that needs to be vectorized. It insert the vector code sequence
+   just before the scalar stmt S, and records a pointer to the vector code
+   in STMT_VINFO_VEC_STMT (stmt_info) (stmt_info is the stmt_vec_info struct 
+   attached to S). This pointer will be used for the vectorization of following
+   stmts which use the def of stmt S. Stmt S is removed if it writes to memory;
+   otherwise, we rely on dead code elimination for removing it.
+
+	For example, say stmt S1 was vectorized into stmt VS1:
+
+   VS1: vb = px[i];
+   S1:	b = x[i];    STMT_VINFO_VEC_STMT (stmt_info (S1)) = VS1
+   S2:  a = b;
+
+   To vectorize stmt S2, the vectorizer first finds the stmt that defines
+   the operand 'b' (S1), and gets the relevant vector def 'vb' from the
+   vector stmt VS1 pointed to by STMT_VINFO_VEC_STMT (stmt_info (S1)). The
+   resulting sequence would be:
+
+   VS1: vb = px[i];
+   S1:	b = x[i];	STMT_VINFO_VEC_STMT (stmt_info (S1)) = VS1
+   VS2: va = vb;
+   S2:  a = b;          STMT_VINFO_VEC_STMT (stmt_info (S2)) = VS2
+
+	Operands that are not SSA_NAMEs, are data-refs that appear in 
+   load/store operations (like 'x[i]' in S1), and are handled differently.
+
+   Target modeling:
+   =================
+	Currently the only target specific information that is used is the
+   size of the vector (in bytes) - "UNITS_PER_SIMD_WORD". Targets that can 
+   support different sizes of vectors, for now will need to specify one value 
+   for "UNITS_PER_SIMD_WORD". More flexibility will be added in the future.
+
+	Since we only vectorize operations which vector form can be
+   expressed using existing tree codes, to verify that an operation is
+   supported, the vectorizer checks the relevant optab at the relevant
+   machine_mode (e.g, add_optab->handlers[(int) V8HImode].insn_code). If
+   the value found is CODE_FOR_nothing, then there's no target support, and
+   we can't vectorize the stmt.
+
+   For additional information on this project see:
+   http://gcc.gnu.org/projects/tree-ssa/vectorization.html
+*/
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "ggc.h"
+#include "tree.h"
+#include "target.h"
+#include "rtl.h"
+#include "basic-block.h"
+#include "diagnostic.h"
+#include "tree-flow.h"
+#include "tree-dump.h"
+#include "timevar.h"
+#include "cfgloop.h"
+#include "cfglayout.h"
+#include "expr.h"
+#include "optabs.h"
+#include "params.h"
+#include "toplev.h"
+#include "tree-chrec.h"
+#include "tree-data-ref.h"
+#include "tree-scalar-evolution.h"
+#include "input.h"
+#include "tree-vectorizer.h"
+#include "tree-pass.h"
+
+/*************************************************************************
+  Simple Loop Peeling Utilities
+ *************************************************************************/
+static struct loop *slpeel_tree_duplicate_loop_to_edge_cfg 
+  (struct loop *, struct loops *, edge);
+static void slpeel_update_phis_for_duplicate_loop 
+  (struct loop *, struct loop *, bool after);
+static void slpeel_update_phi_nodes_for_guard1 
+  (edge, struct loop *, bool, basic_block *, bitmap *); 
+static void slpeel_update_phi_nodes_for_guard2 
+  (edge, struct loop *, bool, basic_block *);
+static edge slpeel_add_loop_guard (basic_block, tree, basic_block, basic_block);
+
+static void rename_use_op (use_operand_p);
+static void rename_variables_in_bb (basic_block);
+static void rename_variables_in_loop (struct loop *);
+
+/*************************************************************************
+  General Vectorization Utilities
+ *************************************************************************/
+static void vect_set_dump_settings (void);
+
+/* vect_dump will be set to stderr or dump_file if exist.  */
+FILE *vect_dump;
+
+/* vect_verbosity_level set to an invalid value 
+   to mark that it's uninitialized.  */
+enum verbosity_levels vect_verbosity_level = MAX_VERBOSITY_LEVEL;
+
+/* Number of loops, at the beginning of vectorization.  */
+unsigned int vect_loops_num;
+
+/* Loop location.  */
+static LOC vect_loop_location;
+
+/* Bitmap of virtual variables to be renamed.  */
+bitmap vect_vnames_to_rename;
+
+/*************************************************************************
+  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)
+{
+  tree phi;
+  block_stmt_iterator bsi;
+  tree stmt;
+  use_operand_p use_p;
+  ssa_op_iter iter;
+  edge e;
+  edge_iterator ei;
+  struct loop *loop = bb->loop_father;
+
+  for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+    {
+      stmt = bsi_stmt (bsi);
+      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, 
+				 (SSA_OP_ALL_USES | SSA_OP_ALL_KILLS))
+	rename_use_op (use_p);
+    }
+
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    {
+      if (!flow_bb_inside_loop_p (loop, e->dest))
+	continue;
+      for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
+        rename_use_op (PHI_ARG_DEF_PTR_FROM_EDGE (phi, e));
+    }
+}
+
+
+/* Renames variables in new generated LOOP.  */
+
+static void
+rename_variables_in_loop (struct loop *loop)
+{
+  unsigned i;
+  basic_block *bbs;
+
+  bbs = get_loop_body (loop);
+
+  for (i = 0; i < loop->num_nodes; i++)
+    rename_variables_in_bb (bbs[i]);
+
+  free (bbs);
+}
+
+
+/* Update the PHI nodes of NEW_LOOP.
+
+   NEW_LOOP is a duplicate of ORIG_LOOP.
+   AFTER indicates whether NEW_LOOP executes before or after ORIG_LOOP:
+   AFTER is true if NEW_LOOP executes after ORIG_LOOP, and false if it
+   executes before it.  */
+
+static void
+slpeel_update_phis_for_duplicate_loop (struct loop *orig_loop,
+				       struct loop *new_loop, bool after)
+{
+  tree new_ssa_name;
+  tree phi_new, phi_orig;
+  tree def;
+  edge orig_loop_latch = loop_latch_edge (orig_loop);
+  edge orig_entry_e = loop_preheader_edge (orig_loop);
+  edge new_loop_exit_e = new_loop->single_exit;
+  edge new_loop_entry_e = loop_preheader_edge (new_loop);
+  edge entry_arg_e = (after ? orig_loop_latch : orig_entry_e);
+
+  /*
+     step 1. For each loop-header-phi:
+             Add the first phi argument for the phi in NEW_LOOP
+            (the one associated with the entry of NEW_LOOP)
+
+     step 2. For each loop-header-phi:
+             Add the second phi argument for the phi in NEW_LOOP
+            (the one associated with the latch of NEW_LOOP)
+
+     step 3. Update the phis in the successor block of NEW_LOOP.
+
+        case 1: NEW_LOOP was placed before ORIG_LOOP:
+                The successor block of NEW_LOOP is the header of ORIG_LOOP.
+                Updating the phis in the successor block can therefore be done
+                along with the scanning of the loop header phis, because the
+                header blocks of ORIG_LOOP and NEW_LOOP have exactly the same
+                phi nodes, organized in the same order.
+
+        case 2: NEW_LOOP was placed after ORIG_LOOP:
+                The successor block of NEW_LOOP is the original exit block of 
+                ORIG_LOOP - the phis to be updated are the loop-closed-ssa phis.
+                We postpone updating these phis to a later stage (when
+                loop guards are added).
+   */
+
+
+  /* Scan the phis in the headers of the old and new loops
+     (they are organized in exactly the same order).  */
+
+  for (phi_new = phi_nodes (new_loop->header),
+       phi_orig = phi_nodes (orig_loop->header);
+       phi_new && phi_orig;
+       phi_new = PHI_CHAIN (phi_new), phi_orig = PHI_CHAIN (phi_orig))
+    {
+      /* step 1.  */
+      def = PHI_ARG_DEF_FROM_EDGE (phi_orig, entry_arg_e);
+      add_phi_arg (phi_new, def, new_loop_entry_e);
+
+      /* step 2.  */
+      def = PHI_ARG_DEF_FROM_EDGE (phi_orig, orig_loop_latch);
+      if (TREE_CODE (def) != SSA_NAME)
+        continue;
+
+      new_ssa_name = get_current_def (def);
+      if (!new_ssa_name)
+	{
+	  /* This only happens if there are no definitions
+	     inside the loop. use the phi_result in this case.  */
+	  new_ssa_name = PHI_RESULT (phi_new);
+	}
+
+      /* An ordinary ssa name defined in the loop.  */
+      add_phi_arg (phi_new, new_ssa_name, loop_latch_edge (new_loop));
+
+      /* step 3 (case 1).  */
+      if (!after)
+        {
+          gcc_assert (new_loop_exit_e == orig_entry_e);
+          SET_PHI_ARG_DEF (phi_orig,
+                           new_loop_exit_e->dest_idx,
+                           new_ssa_name);
+        }
+    }
+}
+
+
+/* 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/merg1_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/merg1_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,
+                                    bitmap *defs)
+{
+  tree orig_phi, new_phi;
+  tree 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;
+  tree name;
+
+  /* Create new bb between loop and new_merge_bb.  */
+  *new_exit_bb = split_edge (loop->single_exit);
+  add_bb_to_loop (*new_exit_bb, loop->outer);
+
+  new_exit_e = EDGE_SUCC (*new_exit_bb, 0);
+
+  for (orig_phi = phi_nodes (orig_bb), update_phi = phi_nodes (update_bb);
+       orig_phi && update_phi;
+       orig_phi = PHI_CHAIN (orig_phi), update_phi = PHI_CHAIN (update_phi))
+    {
+      /* Virtual phi; Mark it for renaming. We actually want to call
+	 mar_sym_for_renaming, but since all ssa renaming datastructures
+	 are going to be freed before we get to call ssa_upate, we just
+	 record this name for now in a bitmap, and will mark it for
+	 renaming later.  */
+      name = PHI_RESULT (orig_phi);
+      if (!is_gimple_reg (SSA_NAME_VAR (name)))
+        bitmap_set_bit (vect_vnames_to_rename, SSA_NAME_VERSION (name));
+
+      /** 1. Handle new-merge-point phis  **/
+
+      /* 1.1. Generate new phi node in NEW_MERGE_BB:  */
+      new_phi = create_phi_node (SSA_NAME_VAR (PHI_RESULT (orig_phi)),
+                                 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));
+      guard_arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, loop_preheader_edge (loop));
+
+      add_phi_arg (new_phi, loop_arg, new_exit_e);
+      add_phi_arg (new_phi, guard_arg, guard_edge);
+
+      /* 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);
+      SET_PHI_ARG_DEF (update_phi, e->dest_idx, 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_phi = create_phi_node (SSA_NAME_VAR (PHI_RESULT (orig_phi)),
+                                 *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, loop->single_exit);
+
+      /* 2.3. Update phi in successor of NEW_EXIT_BB:  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi2, new_exit_e) == loop_arg);
+      SET_PHI_ARG_DEF (update_phi2, new_exit_e->dest_idx, 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;
+        }
+      gcc_assert (get_current_def (current_new_name) == NULL_TREE);
+
+      set_current_def (current_new_name, PHI_RESULT (new_phi));
+      bitmap_set_bit (*defs, SSA_NAME_VERSION (current_new_name));
+    }
+
+  set_phi_nodes (new_merge_bb, phi_reverse (phi_nodes (new_merge_bb)));
+}
+
+
+/* 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/merg1_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)
+{
+  tree orig_phi, new_phi;
+  tree 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;
+
+  /* Create new bb between loop and new_merge_bb.  */
+  *new_exit_bb = split_edge (loop->single_exit);
+  add_bb_to_loop (*new_exit_bb, loop->outer);
+
+  new_exit_e = EDGE_SUCC (*new_exit_bb, 0);
+
+  for (update_phi = phi_nodes (update_bb); update_phi; 
+       update_phi = PHI_CHAIN (update_phi))
+    {
+      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_phi = create_phi_node (SSA_NAME_VAR (PHI_RESULT (orig_phi)),
+                                 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);
+      add_phi_arg (new_phi, guard_arg, guard_edge);
+
+      /* 1.3. Update phi in successor block.  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi, e) == orig_def);
+      SET_PHI_ARG_DEF (update_phi, e->dest_idx, 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_phi = create_phi_node (SSA_NAME_VAR (PHI_RESULT (orig_phi)),
+                                 *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, loop->single_exit);
+
+      /* 2.3. Update phi in successor of NEW_EXIT_BB:  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi2, new_exit_e) == loop_arg);
+      SET_PHI_ARG_DEF (update_phi2, new_exit_e->dest_idx, 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_phi = create_phi_node (SSA_NAME_VAR (PHI_RESULT (orig_phi)),
+                                 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));
+
+      /* 3.4. Update phi in successor of GUARD_BB:  */
+      gcc_assert (PHI_ARG_DEF_FROM_EDGE (update_phi2, guard_edge)
+                                                                == guard_arg);
+      SET_PHI_ARG_DEF (update_phi2, guard_edge->dest_idx, PHI_RESULT (new_phi));
+    }
+
+  set_phi_nodes (new_merge_bb, phi_reverse (phi_nodes (new_merge_bb)));
+}
+
+
+/* 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, cond_stmt, cond;
+  tree orig_cond;
+  edge exit_edge = loop->single_exit;
+  block_stmt_iterator loop_cond_bsi;
+  block_stmt_iterator incr_bsi;
+  bool insert_after;
+  tree begin_label = tree_block_label (loop->latch);
+  tree exit_label = tree_block_label (loop->single_exit->dest);
+  tree init = build_int_cst (TREE_TYPE (niters), 0);
+  tree step = build_int_cst (TREE_TYPE (niters), 1);
+  tree then_label;
+  tree else_label;
+  LOC loop_loc;
+
+  orig_cond = get_loop_exit_condition (loop);
+  gcc_assert (orig_cond);
+  loop_cond_bsi = bsi_for_stmt (orig_cond);
+
+  standard_iv_increment_position (loop, &incr_bsi, &insert_after);
+  create_iv (init, step, NULL_TREE, loop,
+             &incr_bsi, insert_after, &indx_before_incr, &indx_after_incr);
+
+  if (exit_edge->flags & EDGE_TRUE_VALUE) /* 'then' edge exits the loop.  */
+    {
+      cond = build2 (GE_EXPR, boolean_type_node, indx_after_incr, niters);
+      then_label = build1 (GOTO_EXPR, void_type_node, exit_label);
+      else_label = build1 (GOTO_EXPR, void_type_node, begin_label);
+    }
+  else /* 'then' edge loops back.  */
+    {
+      cond = build2 (LT_EXPR, boolean_type_node, indx_after_incr, niters);
+      then_label = build1 (GOTO_EXPR, void_type_node, begin_label);
+      else_label = build1 (GOTO_EXPR, void_type_node, exit_label);
+    }
+
+  cond_stmt = build3 (COND_EXPR, TREE_TYPE (orig_cond), cond,
+		     then_label, else_label);
+  bsi_insert_before (&loop_cond_bsi, cond_stmt, BSI_SAME_STMT);
+
+  /* Remove old loop exit test:  */
+  bsi_remove (&loop_cond_bsi, true);
+
+  loop_loc = find_loop_location (loop);
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      if (loop_loc != UNKNOWN_LOC)
+        fprintf (dump_file, "\nloop at %s:%d: ",
+                 LOC_FILE (loop_loc), LOC_LINE (loop_loc));
+      print_generic_expr (dump_file, cond_stmt, TDF_SLIM);
+    }
+
+  loop->nb_iterations = niters;
+}
+
+
+/* Given LOOP this function generates a new copy of it and puts it 
+   on E which is either the entry or exit of LOOP.  */
+
+static struct loop *
+slpeel_tree_duplicate_loop_to_edge_cfg (struct loop *loop, struct loops *loops, 
+					edge e)
+{
+  struct loop *new_loop;
+  basic_block *new_bbs, *bbs;
+  bool at_exit;
+  bool was_imm_dom;
+  basic_block exit_dest; 
+  tree phi, phi_arg;
+
+  at_exit = (e == loop->single_exit); 
+  if (!at_exit && e != loop_preheader_edge (loop))
+    return NULL;
+
+  bbs = get_loop_body (loop);
+
+  /* Check whether duplication is possible.  */
+  if (!can_copy_bbs_p (bbs, loop->num_nodes))
+    {
+      free (bbs);
+      return NULL;
+    }
+
+  /* Generate new loop structure.  */
+  new_loop = duplicate_loop (loops, loop, loop->outer);
+  if (!new_loop)
+    {
+      free (bbs);
+      return NULL;
+    }
+
+  exit_dest = loop->single_exit->dest;
+  was_imm_dom = (get_immediate_dominator (CDI_DOMINATORS, 
+					  exit_dest) == loop->header ? 
+		 true : false);
+
+  new_bbs = XNEWVEC (basic_block, loop->num_nodes);
+
+  copy_bbs (bbs, loop->num_nodes, new_bbs,
+	    &loop->single_exit, 1, &new_loop->single_exit, NULL,
+	    e->src);
+
+  /* Duplicating phi args at exit bbs as coming 
+     also from exit of duplicated loop.  */
+  for (phi = phi_nodes (exit_dest); phi; phi = PHI_CHAIN (phi))
+    {
+      phi_arg = PHI_ARG_DEF_FROM_EDGE (phi, loop->single_exit);
+      if (phi_arg)
+	{
+	  edge new_loop_exit_edge;
+
+	  if (EDGE_SUCC (new_loop->header, 0)->dest == new_loop->latch)
+	    new_loop_exit_edge = EDGE_SUCC (new_loop->header, 1);
+	  else
+	    new_loop_exit_edge = EDGE_SUCC (new_loop->header, 0);
+  
+	  add_phi_arg (phi, phi_arg, new_loop_exit_edge);	
+	}
+    }    
+   
+  if (at_exit) /* Add the loop copy at exit.  */
+    {
+      redirect_edge_and_branch_force (e, new_loop->header);
+      set_immediate_dominator (CDI_DOMINATORS, new_loop->header, e->src);
+      if (was_imm_dom)
+	set_immediate_dominator (CDI_DOMINATORS, exit_dest, new_loop->header);
+    }
+  else /* Add the copy at entry.  */
+    {
+      edge new_exit_e;
+      edge entry_e = loop_preheader_edge (loop);
+      basic_block preheader = entry_e->src;
+           
+      if (!flow_bb_inside_loop_p (new_loop, 
+				  EDGE_SUCC (new_loop->header, 0)->dest))
+        new_exit_e = EDGE_SUCC (new_loop->header, 0);
+      else
+	new_exit_e = EDGE_SUCC (new_loop->header, 1); 
+
+      redirect_edge_and_branch_force (new_exit_e, loop->header);
+      set_immediate_dominator (CDI_DOMINATORS, loop->header,
+			       new_exit_e->src);
+
+      /* We have to add phi args to the loop->header here as coming 
+	 from new_exit_e edge.  */
+      for (phi = phi_nodes (loop->header); phi; phi = PHI_CHAIN (phi))
+	{
+	  phi_arg = PHI_ARG_DEF_FROM_EDGE (phi, entry_e);
+	  if (phi_arg)
+	    add_phi_arg (phi, phi_arg, new_exit_e);	
+	}    
+
+      redirect_edge_and_branch_force (entry_e, new_loop->header);
+      set_immediate_dominator (CDI_DOMINATORS, new_loop->header, preheader);
+    }
+
+  free (new_bbs);
+  free (bbs);
+
+  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.  */
+
+static edge
+slpeel_add_loop_guard (basic_block guard_bb, tree cond, basic_block exit_bb,
+		        basic_block dom_bb)
+{
+  block_stmt_iterator bsi;
+  edge new_e, enter_e;
+  tree cond_stmt, then_label, else_label;
+
+  enter_e = EDGE_SUCC (guard_bb, 0);
+  enter_e->flags &= ~EDGE_FALLTHRU;
+  enter_e->flags |= EDGE_FALSE_VALUE;
+  bsi = bsi_last (guard_bb);
+
+  then_label = build1 (GOTO_EXPR, void_type_node,
+                       tree_block_label (exit_bb));
+  else_label = build1 (GOTO_EXPR, void_type_node,
+                       tree_block_label (enter_e->dest));
+  cond_stmt = build3 (COND_EXPR, void_type_node, cond,
+   		     then_label, else_label);
+  bsi_insert_after (&bsi, cond_stmt, BSI_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);
+  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 (struct loop *loop, edge e)
+{
+  edge exit_e = loop->single_exit;
+  edge entry_e = loop_preheader_edge (loop);
+  tree orig_cond = get_loop_exit_condition (loop);
+  block_stmt_iterator loop_exit_bsi = bsi_last (exit_e->src);
+
+  if (need_ssa_update_p ())
+    return false;
+
+  if (loop->inner
+      /* All loops have an outer scope; the only case loop->outer is NULL is for
+         the function itself.  */
+      || !loop->outer
+      || loop->num_nodes != 2
+      || !empty_block_p (loop->latch)
+      || !loop->single_exit
+      /* Verify that new loop exit condition can be trivially modified.  */
+      || (!orig_cond || orig_cond != bsi_stmt (loop_exit_bsi))
+      || (e != exit_e && e != entry_e))
+    return false;
+
+  return true;
+}
+
+#ifdef ENABLE_CHECKING
+void
+slpeel_verify_cfg_after_peeling (struct loop *first_loop,
+                                 struct loop *second_loop)
+{
+  basic_block loop1_exit_bb = first_loop->single_exit->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_loopt->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_loopt->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_loopt->exit is after the
+     second_loop.  */
+  /* TODO */
+}
+#endif
+
+/* 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.
+
+   Input:
+   - LOOP: the loop to be peeled.
+   - 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).
+
+   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.
+
+   FORNOW only simple loops are supported (see slpeel_can_duplicate_loop_p).
+   FORNOW the resulting code will not be in loop-closed-ssa form.
+*/
+
+struct loop*
+slpeel_tree_peel_loop_to_edge (struct loop *loop, struct loops *loops, 
+			       edge e, tree first_niters, 
+			       tree niters, bool update_first_loop_count)
+{
+  struct loop *new_loop = NULL, *first_loop, *second_loop;
+  edge skip_e;
+  tree pre_condition;
+  bitmap definitions;
+  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;
+  edge exit_e = loop->single_exit;
+  LOC loop_loc;
+  
+  if (!slpeel_can_duplicate_loop_p (loop, e))
+    return NULL;
+  
+  /* We have to initialize cfg_hooks. Then, when calling
+   cfg_hooks->split_edge, the function tree_split_edge 
+   is actually called and, when calling cfg_hooks->duplicate_block,
+   the function tree_duplicate_bb is called.  */
+  tree_register_cfg_hooks ();
+
+
+  /* 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, loops, e)))
+    {
+      loop_loc = find_loop_location (loop);
+      if (dump_file && (dump_flags & TDF_DETAILS))
+        {
+          if (loop_loc != UNKNOWN_LOC)
+            fprintf (dump_file, "\n%s:%d: note: ",
+                     LOC_FILE (loop_loc), LOC_LINE (loop_loc));
+          fprintf (dump_file, "tree_duplicate_loop_to_edge_cfg failed.\n");
+        }
+      return NULL;
+    }
+  
+  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;
+    }
+
+  definitions = ssa_names_to_replace ();
+  slpeel_update_phis_for_duplicate_loop (loop, new_loop, e == exit_e);
+  rename_variables_in_loop (new_loop);
+
+
+  /* 2. Add the guard that controls whether the first loop is executed.
+        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:
+   */
+
+  bb_before_first_loop = split_edge (loop_preheader_edge (first_loop));
+  add_bb_to_loop (bb_before_first_loop, first_loop->outer);
+  bb_before_second_loop = split_edge (first_loop->single_exit);
+  add_bb_to_loop (bb_before_second_loop, first_loop->outer);
+
+  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,
+                                  bb_before_second_loop, bb_before_first_loop);
+  slpeel_update_phi_nodes_for_guard1 (skip_e, first_loop,
+				      first_loop == new_loop,
+				      &new_exit_bb, &definitions);
+
+
+  /* 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 (second_loop->single_exit);
+  add_bb_to_loop (bb_after_second_loop, second_loop->outer);
+
+  pre_condition = 
+	fold_build2 (EQ_EXPR, boolean_type_node, first_niters, niters);
+  skip_e = slpeel_add_loop_guard (bb_between_loops, pre_condition,
+                                  bb_after_second_loop, bb_before_first_loop);
+  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);
+
+  BITMAP_FREE (definitions);
+  delete_update_ssa ();
+
+  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.  */
+
+LOC
+find_loop_location (struct loop *loop)
+{
+  tree node = NULL_TREE;
+  basic_block bb;
+  block_stmt_iterator si;
+
+  if (!loop)
+    return UNKNOWN_LOC;
+
+  node = get_loop_exit_condition (loop);
+
+  if (node && EXPR_P (node) && EXPR_HAS_LOCATION (node)
+      && EXPR_FILENAME (node) && EXPR_LINENO (node))
+    return EXPR_LOC (node);
+
+  /* If we got here the loop is probably not "well formed",
+     try to estimate the loop location */
+
+  if (!loop->header)
+    return UNKNOWN_LOC;
+
+  bb = loop->header;
+
+  for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+    {
+      node = bsi_stmt (si);
+      if (node && EXPR_P (node) && EXPR_HAS_LOCATION (node))
+        return EXPR_LOC (node);
+    }
+
+  return UNKNOWN_LOC;
+}
+
+
+/*************************************************************************
+  Vectorization Debug Information.
+ *************************************************************************/
+
+/* Function vect_set_verbosity_level.
+
+   Called from toplev.c upon detection of the
+   -ftree-vectorizer-verbose=N option.  */
+
+void
+vect_set_verbosity_level (const char *val)
+{
+   unsigned int vl;
+
+   vl = atoi (val);
+   if (vl < MAX_VERBOSITY_LEVEL)
+     vect_verbosity_level = vl;
+   else
+     vect_verbosity_level = MAX_VERBOSITY_LEVEL - 1;
+}
+
+
+/* Function vect_set_dump_settings.
+
+   Fix the verbosity level of the vectorizer if the
+   requested level was not set explicitly using the flag
+   -ftree-vectorizer-verbose=N.
+   Decide where to print the debugging information (dump_file/stderr).
+   If the user defined the verbosity level, but there is no dump file,
+   print to stderr, otherwise print to the dump file.  */
+
+static void
+vect_set_dump_settings (void)
+{
+  vect_dump = dump_file;
+
+  /* Check if the verbosity level was defined by the user:  */
+  if (vect_verbosity_level != MAX_VERBOSITY_LEVEL)
+    {
+      /* If there is no dump file, print to stderr.  */
+      if (!dump_file)
+        vect_dump = stderr;
+      return;
+    }
+
+  /* User didn't specify verbosity level:  */
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    vect_verbosity_level = REPORT_DETAILS;
+  else if (dump_file && (dump_flags & TDF_STATS))
+    vect_verbosity_level = REPORT_UNVECTORIZED_LOOPS;
+  else
+    vect_verbosity_level = REPORT_NONE;
+
+  gcc_assert (dump_file || vect_verbosity_level == REPORT_NONE);
+}
+
+
+/* Function debug_loop_details.
+
+   For vectorization debug dumps.  */
+
+bool
+vect_print_dump_info (enum verbosity_levels vl)
+{
+  if (vl > vect_verbosity_level)
+    return false;
+
+  if (!current_function_decl || !vect_dump)
+    return false;
+
+  if (vect_loop_location == UNKNOWN_LOC)
+    fprintf (vect_dump, "\n%s:%d: note: ",
+		 DECL_SOURCE_FILE (current_function_decl),
+		 DECL_SOURCE_LINE (current_function_decl));
+  else
+    fprintf (vect_dump, "\n%s:%d: note: ", 
+	     LOC_FILE (vect_loop_location), LOC_LINE (vect_loop_location));
+
+  return true;
+}
+
+
+/*************************************************************************
+  Vectorization Utilities.
+ *************************************************************************/
+
+/* Function new_stmt_vec_info.
+
+   Create and initialize a new stmt_vec_info struct for STMT.  */
+
+stmt_vec_info
+new_stmt_vec_info (tree stmt, loop_vec_info loop_vinfo)
+{
+  stmt_vec_info res;
+  res = (stmt_vec_info) xcalloc (1, sizeof (struct _stmt_vec_info));
+
+  STMT_VINFO_TYPE (res) = undef_vec_info_type;
+  STMT_VINFO_STMT (res) = stmt;
+  STMT_VINFO_LOOP_VINFO (res) = loop_vinfo;
+  STMT_VINFO_RELEVANT_P (res) = 0;
+  STMT_VINFO_LIVE_P (res) = 0;
+  STMT_VINFO_VECTYPE (res) = NULL;
+  STMT_VINFO_VEC_STMT (res) = NULL;
+  STMT_VINFO_IN_PATTERN_P (res) = false;
+  STMT_VINFO_RELATED_STMT (res) = NULL;
+  STMT_VINFO_DATA_REF (res) = NULL;
+  if (TREE_CODE (stmt) == PHI_NODE)
+    STMT_VINFO_DEF_TYPE (res) = vect_unknown_def_type;
+  else
+    STMT_VINFO_DEF_TYPE (res) = vect_loop_def;
+  STMT_VINFO_SAME_ALIGN_REFS (res) = VEC_alloc (dr_p, heap, 5);
+
+  return res;
+}
+
+
+/* Function new_loop_vec_info.
+
+   Create and initialize a new loop_vec_info struct for LOOP, as well as
+   stmt_vec_info structs for all the stmts in LOOP.  */
+
+loop_vec_info
+new_loop_vec_info (struct loop *loop)
+{
+  loop_vec_info res;
+  basic_block *bbs;
+  block_stmt_iterator si;
+  unsigned int i;
+
+  res = (loop_vec_info) xcalloc (1, sizeof (struct _loop_vec_info));
+
+  bbs = get_loop_body (loop);
+
+  /* Create stmt_info for all stmts in the loop.  */
+  for (i = 0; i < loop->num_nodes; i++)
+    {
+      basic_block bb = bbs[i];
+      tree phi;
+
+      for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+        {
+          stmt_ann_t ann = get_stmt_ann (phi);
+          set_stmt_info (ann, new_stmt_vec_info (phi, res));
+        }
+
+      for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+	{
+	  tree stmt = bsi_stmt (si);
+	  stmt_ann_t ann;
+
+	  ann = stmt_ann (stmt);
+	  set_stmt_info (ann, new_stmt_vec_info (stmt, res));
+	}
+    }
+
+  LOOP_VINFO_LOOP (res) = loop;
+  LOOP_VINFO_BBS (res) = bbs;
+  LOOP_VINFO_EXIT_COND (res) = NULL;
+  LOOP_VINFO_NITERS (res) = NULL;
+  LOOP_VINFO_VECTORIZABLE_P (res) = 0;
+  LOOP_PEELING_FOR_ALIGNMENT (res) = 0;
+  LOOP_VINFO_VECT_FACTOR (res) = 0;
+  LOOP_VINFO_DATAREFS (res) = VEC_alloc (data_reference_p, heap, 10);
+  LOOP_VINFO_DDRS (res) = VEC_alloc (ddr_p, heap, 10 * 10);
+  LOOP_VINFO_UNALIGNED_DR (res) = NULL;
+  LOOP_VINFO_MAY_MISALIGN_STMTS (res)
+    = VEC_alloc (tree, heap, PARAM_VALUE (PARAM_VECT_MAX_VERSION_CHECKS));
+
+  return res;
+}
+
+
+/* Function destroy_loop_vec_info.
+ 
+   Free LOOP_VINFO struct, as well as all the stmt_vec_info structs of all the 
+   stmts in the loop.  */
+
+void
+destroy_loop_vec_info (loop_vec_info loop_vinfo)
+{
+  struct loop *loop;
+  basic_block *bbs;
+  int nbbs;
+  block_stmt_iterator si;
+  int j;
+
+  if (!loop_vinfo)
+    return;
+
+  loop = LOOP_VINFO_LOOP (loop_vinfo);
+
+  bbs = LOOP_VINFO_BBS (loop_vinfo);
+  nbbs = loop->num_nodes;
+
+  for (j = 0; j < nbbs; j++)
+    {
+      basic_block bb = bbs[j];
+      tree phi;
+      stmt_vec_info stmt_info;
+
+      for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+        {
+          stmt_ann_t ann = stmt_ann (phi);
+
+          stmt_info = vinfo_for_stmt (phi);
+          free (stmt_info);
+          set_stmt_info (ann, NULL);
+        }
+
+      for (si = bsi_start (bb); !bsi_end_p (si); )
+	{
+	  tree stmt = bsi_stmt (si);
+	  stmt_ann_t ann = stmt_ann (stmt);
+	  stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
+
+	  if (stmt_info)
+	    {
+	      /* Check if this is a "pattern stmt" (introduced by the 
+		 vectorizer during the pattern recognition pass).  */
+	      bool remove_stmt_p = false;
+	      tree orig_stmt = STMT_VINFO_RELATED_STMT (stmt_info);
+	      if (orig_stmt)
+		{
+		  stmt_vec_info orig_stmt_info = vinfo_for_stmt (orig_stmt);
+		  if (orig_stmt_info
+		      && STMT_VINFO_IN_PATTERN_P (orig_stmt_info))
+		    remove_stmt_p = true; 
+		}
+			
+	      /* Free stmt_vec_info.  */
+	      VEC_free (dr_p, heap, STMT_VINFO_SAME_ALIGN_REFS (stmt_info));
+	      free (stmt_info);
+	      set_stmt_info (ann, NULL);
+
+	      /* Remove dead "pattern stmts".  */
+	      if (remove_stmt_p)
+	        bsi_remove (&si, true);
+	    }
+	  bsi_next (&si);
+	}
+    }
+
+  free (LOOP_VINFO_BBS (loop_vinfo));
+  free_data_refs (LOOP_VINFO_DATAREFS (loop_vinfo));
+  free_dependence_relations (LOOP_VINFO_DDRS (loop_vinfo));
+  VEC_free (tree, heap, LOOP_VINFO_MAY_MISALIGN_STMTS (loop_vinfo));
+
+  free (loop_vinfo);
+}
+
+
+/* Function vect_force_dr_alignment_p.
+
+   Returns whether the alignment of a DECL can be forced to be aligned
+   on ALIGNMENT bit boundary.  */
+
+bool 
+vect_can_force_dr_alignment_p (tree decl, unsigned int alignment)
+{
+  if (TREE_CODE (decl) != VAR_DECL)
+    return false;
+
+  if (DECL_EXTERNAL (decl))
+    return false;
+
+  if (TREE_ASM_WRITTEN (decl))
+    return false;
+
+  if (TREE_STATIC (decl))
+    return (alignment <= MAX_OFILE_ALIGNMENT);
+  else
+    /* This is not 100% correct.  The absolute correct stack alignment
+       is STACK_BOUNDARY.  We're supposed to hope, but not assume, that
+       PREFERRED_STACK_BOUNDARY is honored by all translation units.
+       However, until someone implements forced stack alignment, SSE
+       isn't really usable without this.  */  
+    return (alignment <= PREFERRED_STACK_BOUNDARY); 
+}
+
+
+/* Function get_vectype_for_scalar_type.
+
+   Returns the vector type corresponding to SCALAR_TYPE as supported
+   by the target.  */
+
+tree
+get_vectype_for_scalar_type (tree scalar_type)
+{
+  enum machine_mode inner_mode = TYPE_MODE (scalar_type);
+  int nbytes = GET_MODE_SIZE (inner_mode);
+  int nunits;
+  tree vectype;
+
+  if (nbytes == 0 || nbytes >= UNITS_PER_SIMD_WORD)
+    return NULL_TREE;
+
+  /* FORNOW: Only a single vector size per target (UNITS_PER_SIMD_WORD)
+     is expected.  */
+  nunits = UNITS_PER_SIMD_WORD / nbytes;
+
+  vectype = build_vector_type (scalar_type, nunits);
+  if (vect_print_dump_info (REPORT_DETAILS))
+    {
+      fprintf (vect_dump, "get vectype with %d units of type ", nunits);
+      print_generic_expr (vect_dump, scalar_type, TDF_SLIM);
+    }
+
+  if (!vectype)
+    return NULL_TREE;
+
+  if (vect_print_dump_info (REPORT_DETAILS))
+    {
+      fprintf (vect_dump, "vectype: ");
+      print_generic_expr (vect_dump, vectype, TDF_SLIM);
+    }
+
+  if (!VECTOR_MODE_P (TYPE_MODE (vectype))
+      && !INTEGRAL_MODE_P (TYPE_MODE (vectype)))
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "mode not supported by target.");
+      return NULL_TREE;
+    }
+
+  return vectype;
+}
+
+
+/* Function vect_supportable_dr_alignment
+
+   Return whether the data reference DR is supported with respect to its
+   alignment.  */
+
+enum dr_alignment_support
+vect_supportable_dr_alignment (struct data_reference *dr)
+{
+  tree vectype = STMT_VINFO_VECTYPE (vinfo_for_stmt (DR_STMT (dr)));
+  enum machine_mode mode = (int) TYPE_MODE (vectype);
+
+  if (aligned_access_p (dr))
+    return dr_aligned;
+
+  /* Possibly unaligned access.  */
+  
+  if (DR_IS_READ (dr))
+    {
+      if (vec_realign_load_optab->handlers[mode].insn_code != CODE_FOR_nothing
+	  && (!targetm.vectorize.builtin_mask_for_load
+	      || targetm.vectorize.builtin_mask_for_load ()))
+	return dr_unaligned_software_pipeline;
+
+      if (movmisalign_optab->handlers[mode].insn_code != CODE_FOR_nothing)
+	/* Can't software pipeline the loads, but can at least do them.  */
+	return dr_unaligned_supported;
+    }
+
+  /* Unsupported.  */
+  return dr_unaligned_unsupported;
+}
+
+
+/* Function vect_is_simple_use.
+
+   Input:
+   LOOP - the loop that is being vectorized.
+   OPERAND - operand of a stmt in LOOP.
+   DEF - the defining stmt in case OPERAND is an SSA_NAME.
+
+   Returns whether a stmt with OPERAND can be vectorized.
+   Supportable operands are constants, loop invariants, and operands that are
+   defined by the current iteration of the loop. Unsupportable operands are 
+   those that are defined by a previous iteration of the loop (as is the case
+   in reduction/induction computations).  */
+
+bool
+vect_is_simple_use (tree operand, loop_vec_info loop_vinfo, tree *def_stmt,
+		    tree *def, enum vect_def_type *dt)
+{ 
+  basic_block bb;
+  stmt_vec_info stmt_vinfo;
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+
+  *def_stmt = NULL_TREE;
+  *def = NULL_TREE;
+  
+  if (vect_print_dump_info (REPORT_DETAILS))
+    {
+      fprintf (vect_dump, "vect_is_simple_use: operand ");
+      print_generic_expr (vect_dump, operand, TDF_SLIM);
+    }
+    
+  if (TREE_CODE (operand) == INTEGER_CST || TREE_CODE (operand) == REAL_CST)
+    {
+      *dt = vect_constant_def;
+      return true;
+    }
+    
+  if (TREE_CODE (operand) != SSA_NAME)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "not ssa-name.");
+      return false;
+    }
+    
+  *def_stmt = SSA_NAME_DEF_STMT (operand);
+  if (*def_stmt == NULL_TREE )
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "no def_stmt.");
+      return false;
+    }
+
+  if (vect_print_dump_info (REPORT_DETAILS))
+    {
+      fprintf (vect_dump, "def_stmt: ");
+      print_generic_expr (vect_dump, *def_stmt, TDF_SLIM);
+    }
+
+  /* empty stmt is expected only in case of a function argument.
+     (Otherwise - we expect a phi_node or a modify_expr).  */
+  if (IS_EMPTY_STMT (*def_stmt))
+    {
+      tree arg = TREE_OPERAND (*def_stmt, 0);
+      if (TREE_CODE (arg) == INTEGER_CST || TREE_CODE (arg) == REAL_CST)
+        {
+          *def = operand;
+          *dt = vect_invariant_def;
+          return true;
+        }
+
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "Unexpected empty stmt.");
+      return false;
+    }
+
+  bb = bb_for_stmt (*def_stmt);
+  if (!flow_bb_inside_loop_p (loop, bb))
+    *dt = vect_invariant_def;
+  else
+    {
+      stmt_vinfo = vinfo_for_stmt (*def_stmt);
+      *dt = STMT_VINFO_DEF_TYPE (stmt_vinfo);
+    }
+
+  if (*dt == vect_unknown_def_type)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "Unsupported pattern.");
+      return false;
+    }
+
+  /* stmts inside the loop that have been identified as performing
+     a reduction operation cannot have uses in the loop.  */
+  if (*dt == vect_reduction_def && TREE_CODE (*def_stmt) != PHI_NODE)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "reduction used in loop.");
+      return false;
+    }
+
+  if (vect_print_dump_info (REPORT_DETAILS))
+    fprintf (vect_dump, "type of def: %d.",*dt);
+
+  switch (TREE_CODE (*def_stmt))
+    {
+    case PHI_NODE:
+      *def = PHI_RESULT (*def_stmt);
+      gcc_assert (*dt == vect_induction_def || *dt == vect_reduction_def
+                  || *dt == vect_invariant_def);
+      break;
+
+    case MODIFY_EXPR:
+      *def = TREE_OPERAND (*def_stmt, 0);
+      gcc_assert (*dt == vect_loop_def || *dt == vect_invariant_def);
+      break;
+
+    default:
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "unsupported defining stmt: ");
+      return false;
+    }
+
+  if (*dt == vect_induction_def)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "induction not supported.");
+      return false;
+    }
+
+  return true;
+}
+
+
+/* Function reduction_code_for_scalar_code
+
+   Input:
+   CODE - tree_code of a reduction operations.
+
+   Output:
+   REDUC_CODE - the corresponding tree-code to be used to reduce the
+      vector of partial results into a single scalar result (which
+      will also reside in a vector).
+
+   Return TRUE if a corresponding REDUC_CODE was found, FALSE otherwise.  */
+
+bool
+reduction_code_for_scalar_code (enum tree_code code,
+                                enum tree_code *reduc_code)
+{
+  switch (code)
+  {
+  case MAX_EXPR:
+    *reduc_code = REDUC_MAX_EXPR;
+    return true;
+
+  case MIN_EXPR:
+    *reduc_code = REDUC_MIN_EXPR;
+    return true;
+
+  case PLUS_EXPR:
+    *reduc_code = REDUC_PLUS_EXPR;
+    return true;
+
+  default:
+    return false;
+  }
+}
+
+
+/* Function vect_is_simple_reduction
+
+   Detect a cross-iteration def-use cucle that represents a simple
+   reduction computation. We look for the following pattern:
+
+   loop_header:
+     a1 = phi < a0, a2 >
+     a3 = ...
+     a2 = operation (a3, a1)
+  
+   such that:
+   1. operation is commutative and associative and it is safe to 
+      change the order of the computation.
+   2. no uses for a2 in the loop (a2 is used out of the loop)
+   3. no uses of a1 in the loop besides the reduction operation.
+
+   Condition 1 is tested here.
+   Conditions 2,3 are tested in vect_mark_stmts_to_be_vectorized.  */
+
+tree
+vect_is_simple_reduction (struct loop *loop, tree phi)
+{
+  edge latch_e = loop_latch_edge (loop);
+  tree loop_arg = PHI_ARG_DEF_FROM_EDGE (phi, latch_e);
+  tree def_stmt, def1, def2;
+  enum tree_code code;
+  int op_type;
+  tree operation, op1, op2;
+  tree type;
+
+  if (TREE_CODE (loop_arg) != SSA_NAME)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: not ssa_name: ");
+          print_generic_expr (vect_dump, loop_arg, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  def_stmt = SSA_NAME_DEF_STMT (loop_arg);
+  if (!def_stmt)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "reduction: no def_stmt.");
+      return NULL_TREE;
+    }
+
+  if (TREE_CODE (def_stmt) != MODIFY_EXPR)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          print_generic_expr (vect_dump, def_stmt, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  operation = TREE_OPERAND (def_stmt, 1);
+  code = TREE_CODE (operation);
+  if (!commutative_tree_code (code) || !associative_tree_code (code))
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: not commutative/associative: ");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  op_type = TREE_CODE_LENGTH (code);
+  if (op_type != binary_op)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: not binary operation: ");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  op1 = TREE_OPERAND (operation, 0);
+  op2 = TREE_OPERAND (operation, 1);
+  if (TREE_CODE (op1) != SSA_NAME || TREE_CODE (op2) != SSA_NAME)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: uses not ssa_names: ");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  /* Check that it's ok to change the order of the computation.  */
+  type = TREE_TYPE (operation);
+  if (TYPE_MAIN_VARIANT (type) != TYPE_MAIN_VARIANT (TREE_TYPE (op1))
+      || TYPE_MAIN_VARIANT (type) != TYPE_MAIN_VARIANT (TREE_TYPE (op2)))
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: multiple types: operation type: ");
+          print_generic_expr (vect_dump, type, TDF_SLIM);
+          fprintf (vect_dump, ", operands types: ");
+          print_generic_expr (vect_dump, TREE_TYPE (op1), TDF_SLIM);
+          fprintf (vect_dump, ",");
+          print_generic_expr (vect_dump, TREE_TYPE (op2), TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  /* CHECKME: check for !flag_finite_math_only too?  */
+  if (SCALAR_FLOAT_TYPE_P (type) && !flag_unsafe_math_optimizations)
+    {
+      /* Changing the order of operations changes the semantics.  */
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: unsafe fp math optimization: ");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+  else if (INTEGRAL_TYPE_P (type) && TYPE_OVERFLOW_TRAPS (type))
+    {
+      /* Changing the order of operations changes the semantics.  */
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: unsafe int math optimization: ");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  /* reduction is safe. we're dealing with one of the following:
+     1) integer arithmetic and no trapv
+     2) floating point arithmetic, and special flags permit this optimization.
+   */
+  def1 = SSA_NAME_DEF_STMT (op1);
+  def2 = SSA_NAME_DEF_STMT (op2);
+  if (!def1 || !def2)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: no defs for operands: ");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+
+  if (TREE_CODE (def1) == MODIFY_EXPR
+      && flow_bb_inside_loop_p (loop, bb_for_stmt (def1))
+      && def2 == phi)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "detected reduction:");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return def_stmt;
+    }
+  else if (TREE_CODE (def2) == MODIFY_EXPR
+      && flow_bb_inside_loop_p (loop, bb_for_stmt (def2))
+      && def1 == phi)
+    {
+      /* Swap operands (just for simplicity - so that the rest of the code
+	 can assume that the reduction variable is always the last (second)
+	 argument).  */
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "detected reduction: need to swap operands:");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      swap_tree_operands (def_stmt, &TREE_OPERAND (operation, 0), 
+				    &TREE_OPERAND (operation, 1));
+      return def_stmt;
+    }
+  else
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        {
+          fprintf (vect_dump, "reduction: unknown pattern.");
+          print_generic_expr (vect_dump, operation, TDF_SLIM);
+        }
+      return NULL_TREE;
+    }
+}
+
+
+/* Function vect_is_simple_iv_evolution.
+
+   FORNOW: A simple evolution of an induction variables in the loop is
+   considered a polynomial evolution with constant step.  */
+
+bool
+vect_is_simple_iv_evolution (unsigned loop_nb, tree access_fn, tree * init, 
+			     tree * step)
+{
+  tree init_expr;
+  tree step_expr;
+  
+  tree evolution_part = evolution_part_in_loop_num (access_fn, loop_nb);
+
+  /* When there is no evolution in this loop, the evolution function
+     is not "simple".  */  
+  if (evolution_part == NULL_TREE)
+    return false;
+  
+  /* When the evolution is a polynomial of degree >= 2
+     the evolution function is not "simple".  */
+  if (tree_is_chrec (evolution_part))
+    return false;
+  
+  step_expr = evolution_part;
+  init_expr = unshare_expr (initial_condition_in_loop_num (access_fn,
+                                                           loop_nb));
+
+  if (vect_print_dump_info (REPORT_DETAILS))
+    {
+      fprintf (vect_dump, "step: ");
+      print_generic_expr (vect_dump, step_expr, TDF_SLIM);
+      fprintf (vect_dump, ",  init: ");
+      print_generic_expr (vect_dump, init_expr, TDF_SLIM);
+    }
+
+  *init = init_expr;
+  *step = step_expr;
+
+  if (TREE_CODE (step_expr) != INTEGER_CST)
+    {
+      if (vect_print_dump_info (REPORT_DETAILS))
+        fprintf (vect_dump, "step unknown.");
+      return false;
+    }
+
+  return true;
+}
+
+
+/* Function vectorize_loops.
+   
+   Entry Point to loop vectorization phase.  */
+
+void
+vectorize_loops (struct loops *loops)
+{
+  unsigned int i;
+  unsigned int num_vectorized_loops = 0;
+
+  /* Fix the verbosity level if not defined explicitly by the user.  */
+  vect_set_dump_settings ();
+
+  /* Allocate the bitmap that records which virtual variables that 
+     need to be renamed.  */
+  vect_vnames_to_rename = BITMAP_ALLOC (NULL);
+
+  /*  ----------- Analyze loops. -----------  */
+
+  /* If some loop was duplicated, it gets bigger number 
+     than all previously defined loops. This fact allows us to run 
+     only over initial loops skipping newly generated ones.  */
+  vect_loops_num = loops->num;
+  for (i = 1; i < vect_loops_num; i++)
+    {
+      loop_vec_info loop_vinfo;
+      struct loop *loop = loops->parray[i];
+
+      if (!loop)
+        continue;
+
+      vect_loop_location = find_loop_location (loop);
+      loop_vinfo = vect_analyze_loop (loop);
+      loop->aux = loop_vinfo;
+
+      if (!loop_vinfo || !LOOP_VINFO_VECTORIZABLE_P (loop_vinfo))
+	continue;
+
+      vect_transform_loop (loop_vinfo, loops);
+      num_vectorized_loops++;
+    }
+  vect_loop_location = UNKNOWN_LOC;
+
+  if (vect_print_dump_info (REPORT_VECTORIZED_LOOPS))
+    fprintf (vect_dump, "vectorized %u loops in function.\n",
+	     num_vectorized_loops);
+
+  /*  ----------- Finalize. -----------  */
+
+  BITMAP_FREE (vect_vnames_to_rename);
+
+  for (i = 1; i < vect_loops_num; i++)
+    {
+      struct loop *loop = loops->parray[i];
+      loop_vec_info loop_vinfo;
+
+      if (!loop)
+	continue;
+      loop_vinfo = loop->aux;
+      destroy_loop_vec_info (loop_vinfo);
+      loop->aux = NULL;
+    }
+}