Fix PR42681.

[official-gcc/Ramakrishna.git] / gcc / graphite-clast-to-gimple.c

/* Translation of CLAST (CLooG AST) to Gimple.
   Copyright (C) 2009 Free Software Foundation, Inc.
   Contributed by Sebastian Pop <sebastian.pop@amd.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 "tm.h"
#include "ggc.h"
#include "tree.h"
#include "rtl.h"
#include "basic-block.h"
#include "diagnostic.h"
#include "tree-flow.h"
#include "toplev.h"
#include "tree-dump.h"
#include "timevar.h"
#include "cfgloop.h"
#include "tree-chrec.h"
#include "tree-data-ref.h"
#include "tree-scalar-evolution.h"
#include "tree-pass.h"
#include "domwalk.h"
#include "value-prof.h"
#include "pointer-set.h"
#include "gimple.h"
#include "sese.h"

#ifdef HAVE_cloog
#include "cloog/cloog.h"
#include "ppl_c.h"
#include "graphite-ppl.h"
#include "graphite.h"
#include "graphite-poly.h"
#include "graphite-scop-detection.h"
#include "graphite-clast-to-gimple.h"
#include "graphite-dependences.h"

/* This flag is set when an error occurred during the translation of
   CLAST to Gimple.  */
static bool gloog_error;

/* Verifies properties that GRAPHITE should maintain during translation.  */

static inline void
graphite_verify (void)
{
#ifdef ENABLE_CHECKING
  verify_loop_structure ();
  verify_dominators (CDI_DOMINATORS);
  verify_dominators (CDI_POST_DOMINATORS);
  verify_ssa (false);
  verify_loop_closed_ssa ();
#endif
}

/* Stores the INDEX in a vector for a given clast NAME.  */

typedef struct clast_name_index {
  int index;
  const char *name;
} *clast_name_index_p;

/* Returns a pointer to a new element of type clast_name_index_p built
   from NAME and INDEX.  */

static inline clast_name_index_p
new_clast_name_index (const char *name, int index)
{
  clast_name_index_p res = XNEW (struct clast_name_index);

  res->name = name;
  res->index = index;
  return res;
}

/* For a given clast NAME, returns -1 if it does not correspond to any
   parameter, or otherwise, returns the index in the PARAMS or
   SCATTERING_DIMENSIONS vector.  */

static inline int
clast_name_to_index (const char *name, htab_t index_table)
{
  struct clast_name_index tmp;
  PTR *slot;

  tmp.name = name;
  slot = htab_find_slot (index_table, &tmp, NO_INSERT);

  if (slot && *slot)
    return ((struct clast_name_index *) *slot)->index;

  return -1;
}

/* Records in INDEX_TABLE the INDEX for NAME.  */

static inline void
save_clast_name_index (htab_t index_table, const char *name, int index)
{
  struct clast_name_index tmp;
  PTR *slot;

  tmp.name = name;
  slot = htab_find_slot (index_table, &tmp, INSERT);

  if (slot)
    {
      if (*slot)
        free (*slot);

      *slot = new_clast_name_index (name, index);
    }
}

/* Print to stderr the element ELT.  */

static inline void
debug_clast_name_index (clast_name_index_p elt)
{
  fprintf (stderr, "(index = %d, name = %s)\n", elt->index, elt->name);
}

/* Helper function for debug_rename_map.  */

static inline int
debug_clast_name_indexes_1 (void **slot, void *s ATTRIBUTE_UNUSED)
{
  struct clast_name_index *entry = (struct clast_name_index *) *slot;
  debug_clast_name_index (entry);
  return 1;
}

/* Print to stderr all the elements of MAP.  */

void
debug_clast_name_indexes (htab_t map)
{
  htab_traverse (map, debug_clast_name_indexes_1, NULL);
}

/* Computes a hash function for database element ELT.  */

static inline hashval_t
clast_name_index_elt_info (const void *elt)
{
  return htab_hash_pointer (((const struct clast_name_index *) elt)->name);
}

/* Compares database elements E1 and E2.  */

static inline int
eq_clast_name_indexes (const void *e1, const void *e2)
{
  const struct clast_name_index *elt1 = (const struct clast_name_index *) e1;
  const struct clast_name_index *elt2 = (const struct clast_name_index *) e2;

  return (elt1->name == elt2->name);
}


/* For a given loop DEPTH in the loop nest of the original black box
   PBB, return the old induction variable associated to that loop.  */

static inline tree
pbb_to_depth_to_oldiv (poly_bb_p pbb, int depth)
{
  gimple_bb_p gbb = PBB_BLACK_BOX (pbb);
  sese region = SCOP_REGION (PBB_SCOP (pbb));
  loop_p loop = gbb_loop_at_index (gbb, region, depth);

  return loop->single_iv;
}

/* For a given scattering dimension, return the new induction variable
   associated to it.  */

static inline tree
newivs_to_depth_to_newiv (VEC (tree, heap) *newivs, int depth)
{
  return VEC_index (tree, newivs, depth);
}

\f

/* Returns the tree variable from the name NAME that was given in
   Cloog representation.  */

static tree
clast_name_to_gcc (const char *name, sese region, VEC (tree, heap) *newivs,
                   htab_t newivs_index, htab_t params_index)
{
  int index;
  VEC (tree, heap) *params = SESE_PARAMS (region);

  if (params && params_index)
    {
      index = clast_name_to_index (name, params_index);

      if (index >= 0)
        return VEC_index (tree, params, index);
    }

  gcc_assert (newivs && newivs_index);
  index = clast_name_to_index (name, newivs_index);
  gcc_assert (index >= 0);

  return newivs_to_depth_to_newiv (newivs, index);
}

/* Returns the maximal precision type for expressions E1 and E2.  */

static inline tree
max_precision_type (tree e1, tree e2)
{
  tree type1 = TREE_TYPE (e1);
  tree type2 = TREE_TYPE (e2);
  return TYPE_PRECISION (type1) > TYPE_PRECISION (type2) ? type1 : type2;
}

static tree
clast_to_gcc_expression (tree, struct clast_expr *, sese, VEC (tree, heap) *,
                         htab_t, htab_t);

/* Converts a Cloog reduction expression R with reduction operation OP
   to a GCC expression tree of type TYPE.  */

static tree
clast_to_gcc_expression_red (tree type, enum tree_code op,
                             struct clast_reduction *r,
                             sese region, VEC (tree, heap) *newivs,
                             htab_t newivs_index, htab_t params_index)
{
  int i;
  tree res = clast_to_gcc_expression (type, r->elts[0], region, newivs,
                                      newivs_index, params_index);
  tree operand_type = (op == POINTER_PLUS_EXPR) ? sizetype : type;

  for (i = 1; i < r->n; i++)
    {
      tree t = clast_to_gcc_expression (operand_type, r->elts[i], region,
                                        newivs, newivs_index, params_index);
      res = fold_build2 (op, type, res, t);
    }

  return res;
}

/* Converts a Cloog AST expression E back to a GCC expression tree of
   type TYPE.  */

static tree
clast_to_gcc_expression (tree type, struct clast_expr *e,
                         sese region, VEC (tree, heap) *newivs,
                         htab_t newivs_index, htab_t params_index)
{
  switch (e->type)
    {
    case expr_term:
      {
        struct clast_term *t = (struct clast_term *) e;

        if (t->var)
          {
            if (value_one_p (t->val))
              {
                tree name = clast_name_to_gcc (t->var, region, newivs,
                                               newivs_index, params_index);
                return fold_convert (type, name);
              }

            else if (value_mone_p (t->val))
              {
                tree name = clast_name_to_gcc (t->var, region, newivs,
                                               newivs_index, params_index);
                name = fold_convert (type, name);
                return fold_build1 (NEGATE_EXPR, type, name);
              }
            else
              {
                tree name = clast_name_to_gcc (t->var, region, newivs,
                                               newivs_index, params_index);
                tree cst = gmp_cst_to_tree (type, t->val);
                name = fold_convert (type, name);
                if (!POINTER_TYPE_P (type))
                  return fold_build2 (MULT_EXPR, type, cst, name);

                gloog_error = true;
                return cst;
              }
          }
        else
          return gmp_cst_to_tree (type, t->val);
      }

    case expr_red:
      {
        struct clast_reduction *r = (struct clast_reduction *) e;

        switch (r->type)
          {
          case clast_red_sum:
            return clast_to_gcc_expression_red
              (type, POINTER_TYPE_P (type) ? POINTER_PLUS_EXPR : PLUS_EXPR,
               r, region, newivs, newivs_index, params_index);

          case clast_red_min:
            return clast_to_gcc_expression_red (type, MIN_EXPR, r, region,
                                                newivs, newivs_index,
                                                params_index);

          case clast_red_max:
            return clast_to_gcc_expression_red (type, MAX_EXPR, r, region,
                                                newivs, newivs_index,
                                                params_index);

          default:
            gcc_unreachable ();
          }
        break;
      }

    case expr_bin:
      {
        struct clast_binary *b = (struct clast_binary *) e;
        struct clast_expr *lhs = (struct clast_expr *) b->LHS;
        tree tl = clast_to_gcc_expression (type, lhs, region, newivs,
                                           newivs_index, params_index);
        tree tr = gmp_cst_to_tree (type, b->RHS);

        switch (b->type)
          {
          case clast_bin_fdiv:
            return fold_build2 (FLOOR_DIV_EXPR, type, tl, tr);

          case clast_bin_cdiv:
            return fold_build2 (CEIL_DIV_EXPR, type, tl, tr);

          case clast_bin_div:
            return fold_build2 (EXACT_DIV_EXPR, type, tl, tr);

          case clast_bin_mod:
            return fold_build2 (TRUNC_MOD_EXPR, type, tl, tr);

          default:
            gcc_unreachable ();
          }
      }

    default:
      gcc_unreachable ();
    }

  return NULL_TREE;
}

/* Returns the type for the expression E.  */

static tree
gcc_type_for_clast_expr (struct clast_expr *e,
                         sese region, VEC (tree, heap) *newivs,
                         htab_t newivs_index, htab_t params_index)
{
  switch (e->type)
    {
    case expr_term:
      {
        struct clast_term *t = (struct clast_term *) e;

        if (t->var)
          return TREE_TYPE (clast_name_to_gcc (t->var, region, newivs,
                                               newivs_index, params_index));
        else
          return NULL_TREE;
      }

    case expr_red:
      {
        struct clast_reduction *r = (struct clast_reduction *) e;

        if (r->n == 1)
          return gcc_type_for_clast_expr (r->elts[0], region, newivs,
                                          newivs_index, params_index);
        else
          {
            int i;
            for (i = 0; i < r->n; i++)
              {
                tree type = gcc_type_for_clast_expr (r->elts[i], region,
                                                     newivs, newivs_index,
                                                     params_index);
                if (type)
                  return type;
              }
            return NULL_TREE;
          }
      }

    case expr_bin:
      {
        struct clast_binary *b = (struct clast_binary *) e;
        struct clast_expr *lhs = (struct clast_expr *) b->LHS;
        return gcc_type_for_clast_expr (lhs, region, newivs,
                                        newivs_index, params_index);
      }

    default:
      gcc_unreachable ();
    }

  return NULL_TREE;
}

/* Returns the type for the equation CLEQ.  */

static tree
gcc_type_for_clast_eq (struct clast_equation *cleq,
                       sese region, VEC (tree, heap) *newivs,
                       htab_t newivs_index, htab_t params_index)
{
  tree type = gcc_type_for_clast_expr (cleq->LHS, region, newivs,
                                       newivs_index, params_index);
  if (type)
    return type;

  return gcc_type_for_clast_expr (cleq->RHS, region, newivs, newivs_index,
                                  params_index);
}

/* Translates a clast equation CLEQ to a tree.  */

static tree
graphite_translate_clast_equation (sese region,
                                   struct clast_equation *cleq,
                                   VEC (tree, heap) *newivs,
                                   htab_t newivs_index, htab_t params_index)
{
  enum tree_code comp;
  tree type = gcc_type_for_clast_eq (cleq, region, newivs, newivs_index,
                                     params_index);
  tree lhs = clast_to_gcc_expression (type, cleq->LHS, region, newivs,
                                      newivs_index, params_index);
  tree rhs = clast_to_gcc_expression (type, cleq->RHS, region, newivs,
                                      newivs_index, params_index);

  if (cleq->sign == 0)
    comp = EQ_EXPR;

  else if (cleq->sign > 0)
    comp = GE_EXPR;

  else
    comp = LE_EXPR;

  return fold_build2 (comp, boolean_type_node, lhs, rhs);
}

/* Creates the test for the condition in STMT.  */

static tree
graphite_create_guard_cond_expr (sese region, struct clast_guard *stmt,
                                 VEC (tree, heap) *newivs,
                                 htab_t newivs_index, htab_t params_index)
{
  tree cond = NULL;
  int i;

  for (i = 0; i < stmt->n; i++)
    {
      tree eq = graphite_translate_clast_equation (region, &stmt->eq[i],
                                                   newivs, newivs_index,
                                                   params_index);

      if (cond)
        cond = fold_build2 (TRUTH_AND_EXPR, TREE_TYPE (eq), cond, eq);
      else
        cond = eq;
    }

  return cond;
}

/* Creates a new if region corresponding to Cloog's guard.  */

static edge
graphite_create_new_guard (sese region, edge entry_edge,
                           struct clast_guard *stmt,
                           VEC (tree, heap) *newivs,
                           htab_t newivs_index, htab_t params_index)
{
  tree cond_expr = graphite_create_guard_cond_expr (region, stmt, newivs,
                                                    newivs_index, params_index);
  edge exit_edge = create_empty_if_region_on_edge (entry_edge, cond_expr);
  return exit_edge;
}

/* Walks a CLAST and returns the first statement in the body of a
   loop.  */

static struct clast_user_stmt *
clast_get_body_of_loop (struct clast_stmt *stmt)
{
  if (!stmt
      || CLAST_STMT_IS_A (stmt, stmt_user))
    return (struct clast_user_stmt *) stmt;

  if (CLAST_STMT_IS_A (stmt, stmt_for))
    return clast_get_body_of_loop (((struct clast_for *) stmt)->body);

  if (CLAST_STMT_IS_A (stmt, stmt_guard))
    return clast_get_body_of_loop (((struct clast_guard *) stmt)->then);

  if (CLAST_STMT_IS_A (stmt, stmt_block))
    return clast_get_body_of_loop (((struct clast_block *) stmt)->body);

  gcc_unreachable ();
}

/* Given a CLOOG_IV, returns the type that it should have in GCC land.
   If the information is not available, i.e. in the case one of the
   transforms created the loop, just return integer_type_node.  */

static tree
gcc_type_for_cloog_iv (const char *cloog_iv, gimple_bb_p gbb)
{
  struct ivtype_map_elt_s tmp;
  PTR *slot;

  tmp.cloog_iv = cloog_iv;
  slot = htab_find_slot (GBB_CLOOG_IV_TYPES (gbb), &tmp, NO_INSERT);

  if (slot && *slot)
    return ((ivtype_map_elt) *slot)->type;

  return integer_type_node;
}

/* Returns the induction variable for the loop that gets translated to
   STMT.  */

static tree
gcc_type_for_iv_of_clast_loop (struct clast_for *stmt_for)
{
  struct clast_stmt *stmt = (struct clast_stmt *) stmt_for;
  struct clast_user_stmt *body = clast_get_body_of_loop (stmt);
  const char *cloog_iv = stmt_for->iterator;
  CloogStatement *cs = body->statement;
  poly_bb_p pbb = (poly_bb_p) cloog_statement_usr (cs);

  return gcc_type_for_cloog_iv (cloog_iv, PBB_BLACK_BOX (pbb));
}

/* Creates a new LOOP corresponding to Cloog's STMT.  Inserts an
   induction variable for the new LOOP.  New LOOP is attached to CFG
   starting at ENTRY_EDGE.  LOOP is inserted into the loop tree and
   becomes the child loop of the OUTER_LOOP.  NEWIVS_INDEX binds
   CLooG's scattering name to the induction variable created for the
   loop of STMT.  The new induction variable is inserted in the NEWIVS
   vector.  */

static struct loop *
graphite_create_new_loop (sese region, edge entry_edge,
                          struct clast_for *stmt,
                          loop_p outer, VEC (tree, heap) **newivs,
                          htab_t newivs_index, htab_t params_index)
{
  tree type = gcc_type_for_iv_of_clast_loop (stmt);
  tree lb = clast_to_gcc_expression (type, stmt->LB, region, *newivs,
                                     newivs_index, params_index);
  tree ub = clast_to_gcc_expression (type, stmt->UB, region, *newivs,
                                     newivs_index, params_index);
  tree stride = gmp_cst_to_tree (type, stmt->stride);
  tree ivvar = create_tmp_var (type, "graphite_IV");
  tree iv, iv_after_increment;
  loop_p loop = create_empty_loop_on_edge
    (entry_edge, lb, stride, ub, ivvar, &iv, &iv_after_increment,
     outer ? outer : entry_edge->src->loop_father);

  add_referenced_var (ivvar);

  save_clast_name_index (newivs_index, stmt->iterator,
                         VEC_length (tree, *newivs));
  VEC_safe_push (tree, heap, *newivs, iv);
  return loop;
}

/* Inserts in MAP a tuple (OLD_NAME, NEW_NAME) for the induction
   variables of the loops around GBB in SESE.  */

static void
build_iv_mapping (htab_t map, sese region,
                  VEC (tree, heap) *newivs, htab_t newivs_index,
                  struct clast_user_stmt *user_stmt,
                  htab_t params_index)
{
  struct clast_stmt *t;
  int index = 0;
  CloogStatement *cs = user_stmt->statement;
  poly_bb_p pbb = (poly_bb_p) cloog_statement_usr (cs);

  for (t = user_stmt->substitutions; t; t = t->next, index++)
    {
      struct clast_expr *expr = (struct clast_expr *)
       ((struct clast_assignment *)t)->RHS;
      tree type = gcc_type_for_clast_expr (expr, region, newivs,
                                           newivs_index, params_index);
      tree old_name = pbb_to_depth_to_oldiv (pbb, index);
      tree e = clast_to_gcc_expression (type, expr, region, newivs,
                                        newivs_index, params_index);
      set_rename (map, old_name, e);
    }
}

/* Helper function for htab_traverse.  */

static int
copy_renames (void **slot, void *s)
{
  struct rename_map_elt_s *entry = (struct rename_map_elt_s *) *slot;
  htab_t res = (htab_t) s;
  tree old_name = entry->old_name;
  tree expr = entry->expr;
  struct rename_map_elt_s tmp;
  PTR *x;

  tmp.old_name = old_name;
  x = htab_find_slot (res, &tmp, INSERT);

  if (x && !*x)
    *x = new_rename_map_elt (old_name, expr);

  return 1;
}

/* Construct bb_pbb_def with BB and PBB. */

static bb_pbb_def *
new_bb_pbb_def (basic_block bb, poly_bb_p pbb)
{
  bb_pbb_def *bb_pbb_p;

  bb_pbb_p = XNEW (bb_pbb_def);
  bb_pbb_p->bb = bb;
  bb_pbb_p->pbb = pbb;

  return bb_pbb_p;
}

/* Mark BB with it's relevant PBB via hashing table BB_PBB_MAPPING.  */

static void
mark_bb_with_pbb (poly_bb_p pbb, basic_block bb, htab_t bb_pbb_mapping)
{
  bb_pbb_def tmp;
  PTR *x;

  tmp.bb = bb;
  x = htab_find_slot (bb_pbb_mapping, &tmp, INSERT);

  if (x && !*x)
    *x = new_bb_pbb_def (bb, pbb);
}

/* Find BB's related poly_bb_p in hash table BB_PBB_MAPPING.  */

static poly_bb_p
find_pbb_via_hash (htab_t bb_pbb_mapping, basic_block bb)
{
  bb_pbb_def tmp;
  PTR *slot;

  tmp.bb = bb;
  slot = htab_find_slot (bb_pbb_mapping, &tmp, NO_INSERT);

  if (slot && *slot)
    return ((bb_pbb_def *) *slot)->pbb;

  return NULL;
}

/* Check data dependency in LOOP at scattering level LEVEL.
   BB_PBB_MAPPING is a basic_block and it's related poly_bb_p
   mapping.  */

static bool
dependency_in_loop_p (loop_p loop, htab_t bb_pbb_mapping, int level)
{
  unsigned i,j;
  basic_block *bbs = get_loop_body_in_dom_order (loop);

  for (i = 0; i < loop->num_nodes; i++)
    {
      poly_bb_p pbb1 = find_pbb_via_hash (bb_pbb_mapping, bbs[i]);

      if (pbb1 == NULL)
       continue;

      for (j = 0; j < loop->num_nodes; j++)
       {
         poly_bb_p pbb2 = find_pbb_via_hash (bb_pbb_mapping, bbs[j]);

         if (pbb2 == NULL)
           continue;

         if (dependency_between_pbbs_p (pbb1, pbb2, level))
           {
             free (bbs);
             return true;
           }
       }
    }

  free (bbs);

  return false;
}

static edge
translate_clast (sese, loop_p, struct clast_stmt *, edge, htab_t,
                 VEC (tree, heap) **, htab_t, htab_t, int, htab_t);

/* Translates a clast user statement STMT to gimple.

   - REGION is the sese region we used to generate the scop.
   - NEXT_E is the edge where new generated code should be attached.
   - CONTEXT_LOOP is the loop in which the generated code will be placed
   - RENAME_MAP contains a set of tuples of new names associated to
     the original variables names.
   - BB_PBB_MAPPING is is a basic_block and it's related poly_bb_p mapping.
   - PARAMS_INDEX connects the cloog parameters with the gimple parameters in
     the sese region.  */
static edge
translate_clast_user (sese region, struct clast_user_stmt *stmt, edge next_e,
                      htab_t rename_map, VEC (tree, heap) **newivs,
                      htab_t newivs_index, htab_t bb_pbb_mapping,
                      htab_t params_index)
{
  gimple_bb_p gbb;
  basic_block new_bb;
  poly_bb_p pbb = (poly_bb_p) cloog_statement_usr (stmt->statement);
  gbb = PBB_BLACK_BOX (pbb);

  if (GBB_BB (gbb) == ENTRY_BLOCK_PTR)
    return next_e;

  build_iv_mapping (rename_map, region, *newivs, newivs_index, stmt,
                    params_index);
  next_e = copy_bb_and_scalar_dependences (GBB_BB (gbb), region,
                                           next_e, rename_map);
  new_bb = next_e->src;
  mark_bb_with_pbb (pbb, new_bb, bb_pbb_mapping);
  update_ssa (TODO_update_ssa);

  return next_e;
}

static tree gcc_type_for_iv_of_clast_loop (struct clast_for *);


/* Creates a new if region protecting the loop to be executed, if the execution
   count is zero (lb > ub).  */
static edge
graphite_create_new_loop_guard (sese region, edge entry_edge,
                                struct clast_for *stmt,
                                VEC (tree, heap) *newivs,
                                htab_t newivs_index, htab_t params_index)
{
  tree cond_expr;
  edge exit_edge;
  tree type = gcc_type_for_iv_of_clast_loop (stmt);
  tree lb = clast_to_gcc_expression (type, stmt->LB, region, newivs,
                                     newivs_index, params_index);
  tree ub = clast_to_gcc_expression (type, stmt->UB, region, newivs,
                                     newivs_index, params_index);

  /* XXX: Adding +1 and using LT_EXPR helps with loop latches that have a
     loop iteration count of "PARAMETER - 1".  For PARAMETER == 0 this becomes
     2^{32|64}, and the condition lb <= ub is true, even if we do not want this.
     However lb < ub + 1 is false, as expected.
     There might be a problem with cases where ub is 2^32.  */
  tree one;
  Value gmp_one;
  value_init (gmp_one);
  value_set_si (gmp_one, 1);
  one = gmp_cst_to_tree (type, gmp_one);
  value_clear (gmp_one);

  ub = fold_build2 (PLUS_EXPR, type, ub, one);
  cond_expr = fold_build2 (LT_EXPR, boolean_type_node, lb, ub);

  exit_edge = create_empty_if_region_on_edge (entry_edge, cond_expr);

  return exit_edge;
}


/* Create the loop for a clast for statement.

   - REGION is the sese region we used to generate the scop.
   - NEXT_E is the edge where new generated code should be attached.
   - RENAME_MAP contains a set of tuples of new names associated to
     the original variables names.
   - BB_PBB_MAPPING is is a basic_block and it's related poly_bb_p mapping.
   - PARAMS_INDEX connects the cloog parameters with the gimple parameters in
     the sese region.  */
static edge
translate_clast_for_loop (sese region, loop_p context_loop,
                          struct clast_for *stmt, edge next_e,
                          htab_t rename_map, VEC (tree, heap) **newivs,
                          htab_t newivs_index, htab_t bb_pbb_mapping,
                          int level, htab_t params_index)
{
  struct loop *loop = graphite_create_new_loop (region, next_e, stmt,
                                                context_loop, newivs,
                                                newivs_index, params_index);
  edge last_e = single_exit (loop);
  edge to_body = single_succ_edge (loop->header);
  basic_block after = to_body->dest;

  /* Create a basic block for loop close phi nodes.  */
  last_e = single_succ_edge (split_edge (last_e));

  /* Translate the body of the loop.  */
  next_e = translate_clast (region, loop, stmt->body, to_body, rename_map,
                            newivs, newivs_index, bb_pbb_mapping, level + 1,
                            params_index);
  redirect_edge_succ_nodup (next_e, after);
  set_immediate_dominator (CDI_DOMINATORS, next_e->dest, next_e->src);

   /* Remove from rename_map all the tuples containing variables
      defined in loop's body.  */
  insert_loop_close_phis (rename_map, loop);

  if (flag_loop_parallelize_all
      && !dependency_in_loop_p (loop, bb_pbb_mapping,
                                get_scattering_level (level)))
    loop->can_be_parallel = true;

  return last_e;
}

/* Translates a clast for statement STMT to gimple.  First a guard is created
   protecting the loop, if it is executed zero times.  In this guard we create
   the real loop structure.

   - REGION is the sese region we used to generate the scop.
   - NEXT_E is the edge where new generated code should be attached.
   - RENAME_MAP contains a set of tuples of new names associated to
     the original variables names.
   - BB_PBB_MAPPING is is a basic_block and it's related poly_bb_p mapping.
   - PARAMS_INDEX connects the cloog parameters with the gimple parameters in
     the sese region.  */
static edge
translate_clast_for (sese region, loop_p context_loop, struct clast_for *stmt,
                     edge next_e, htab_t rename_map, VEC (tree, heap) **newivs,
                     htab_t newivs_index, htab_t bb_pbb_mapping, int level,
                     htab_t params_index)
{
  edge last_e = graphite_create_new_loop_guard (region, next_e, stmt, *newivs,
                                           newivs_index, params_index);

  edge true_e = get_true_edge_from_guard_bb (next_e->dest);
  edge false_e = get_false_edge_from_guard_bb (next_e->dest);
  edge exit_true_e = single_succ_edge (true_e->dest);
  edge exit_false_e = single_succ_edge (false_e->dest);

  htab_t before_guard = htab_create (10, rename_map_elt_info,
                                     eq_rename_map_elts, free);
  htab_traverse (rename_map, copy_renames, before_guard);

  next_e = translate_clast_for_loop (region, context_loop, stmt, true_e,
                                     rename_map, newivs,
                                     newivs_index, bb_pbb_mapping, level,
                                     params_index);

  insert_guard_phis (last_e->src, exit_true_e, exit_false_e,
                     before_guard, rename_map);

  htab_delete (before_guard);

  return last_e;
}

/* Translates a clast guard statement STMT to gimple.

   - REGION is the sese region we used to generate the scop.
   - NEXT_E is the edge where new generated code should be attached.
   - CONTEXT_LOOP is the loop in which the generated code will be placed
   - RENAME_MAP contains a set of tuples of new names associated to
     the original variables names.
   - BB_PBB_MAPPING is is a basic_block and it's related poly_bb_p mapping.
   - PARAMS_INDEX connects the cloog parameters with the gimple parameters in
     the sese region.  */
static edge
translate_clast_guard (sese region, loop_p context_loop,
                       struct clast_guard *stmt, edge next_e,
                       htab_t rename_map, VEC (tree, heap) **newivs,
                       htab_t newivs_index, htab_t bb_pbb_mapping, int level,
                       htab_t params_index)
{
  edge last_e = graphite_create_new_guard (region, next_e, stmt, *newivs,
                                           newivs_index, params_index);

  edge true_e = get_true_edge_from_guard_bb (next_e->dest);
  edge false_e = get_false_edge_from_guard_bb (next_e->dest);
  edge exit_true_e = single_succ_edge (true_e->dest);
  edge exit_false_e = single_succ_edge (false_e->dest);

  htab_t before_guard = htab_create (10, rename_map_elt_info,
                                     eq_rename_map_elts, free);
  htab_traverse (rename_map, copy_renames, before_guard);

  next_e = translate_clast (region, context_loop, stmt->then, true_e,
                            rename_map, newivs, newivs_index, bb_pbb_mapping,
                            level, params_index);

  insert_guard_phis (last_e->src, exit_true_e, exit_false_e,
                     before_guard, rename_map);

  htab_delete (before_guard);

  return last_e;
}

/* Translates a CLAST statement STMT to GCC representation in the
   context of a SESE.

   - NEXT_E is the edge where new generated code should be attached.
   - CONTEXT_LOOP is the loop in which the generated code will be placed
   - RENAME_MAP contains a set of tuples of new names associated to
     the original variables names.
   - BB_PBB_MAPPING is is a basic_block and it's related poly_bb_p mapping.  */
static edge
translate_clast (sese region, loop_p context_loop, struct clast_stmt *stmt,
                 edge next_e, htab_t rename_map, VEC (tree, heap) **newivs,
                 htab_t newivs_index, htab_t bb_pbb_mapping, int level,
                 htab_t params_index)
{
  if (!stmt || gloog_error)
    return next_e;

  if (CLAST_STMT_IS_A (stmt, stmt_root))
    ; /* Do nothing.  */

  else if (CLAST_STMT_IS_A (stmt, stmt_user))
    next_e = translate_clast_user (region, (struct clast_user_stmt *) stmt,
                                   next_e, rename_map, newivs, newivs_index,
                                   bb_pbb_mapping, params_index);

  else if (CLAST_STMT_IS_A (stmt, stmt_for))
    next_e = translate_clast_for (region, context_loop,
                                  (struct clast_for *) stmt, next_e,
                                  rename_map, newivs, newivs_index,
                                  bb_pbb_mapping, level, params_index);

  else if (CLAST_STMT_IS_A (stmt, stmt_guard))
    next_e = translate_clast_guard (region, context_loop,
                                    (struct clast_guard *) stmt, next_e,
                                    rename_map, newivs, newivs_index,
                                    bb_pbb_mapping, level, params_index);

  else if (CLAST_STMT_IS_A (stmt, stmt_block))
    next_e = translate_clast (region, context_loop,
                              ((struct clast_block *) stmt)->body,
                              next_e, rename_map, newivs, newivs_index,
                              bb_pbb_mapping, level, params_index);
  else
    gcc_unreachable();

  recompute_all_dominators ();
  graphite_verify ();

  return translate_clast (region, context_loop, stmt->next, next_e,
                          rename_map, newivs, newivs_index,
                          bb_pbb_mapping, level, params_index);
}

/* Returns the first cloog name used in EXPR.  */

static const char *
find_cloog_iv_in_expr (struct clast_expr *expr)
{
  struct clast_term *term = (struct clast_term *) expr;

  if (expr->type == expr_term
      && !term->var)
    return NULL;

  if (expr->type == expr_term)
    return term->var;

  if (expr->type == expr_red)
    {
      int i;
      struct clast_reduction *red = (struct clast_reduction *) expr;

      for (i = 0; i < red->n; i++)
        {
          const char *res = find_cloog_iv_in_expr ((red)->elts[i]);

          if (res)
            return res;
        }
    }

  return NULL;
}

/* Build for a clast_user_stmt USER_STMT a map between the CLAST
   induction variables and the corresponding GCC old induction
   variables.  This information is stored on each GRAPHITE_BB.  */

static void
compute_cloog_iv_types_1 (poly_bb_p pbb, struct clast_user_stmt *user_stmt)
{
  gimple_bb_p gbb = PBB_BLACK_BOX (pbb);
  struct clast_stmt *t;
  int index = 0;

  for (t = user_stmt->substitutions; t; t = t->next, index++)
    {
      PTR *slot;
      struct ivtype_map_elt_s tmp;
      struct clast_expr *expr = (struct clast_expr *)
        ((struct clast_assignment *)t)->RHS;

      /* Create an entry (clast_var, type).  */
      tmp.cloog_iv = find_cloog_iv_in_expr (expr);
      if (!tmp.cloog_iv)
        continue;

      slot = htab_find_slot (GBB_CLOOG_IV_TYPES (gbb), &tmp, INSERT);

      if (slot && !*slot)
        {
          tree oldiv = pbb_to_depth_to_oldiv (pbb, index);
          tree type = oldiv ? TREE_TYPE (oldiv) : integer_type_node;
          *slot = new_ivtype_map_elt (tmp.cloog_iv, type);
        }
    }
}

/* Walk the CLAST tree starting from STMT and build for each
   clast_user_stmt a map between the CLAST induction variables and the
   corresponding GCC old induction variables.  This information is
   stored on each GRAPHITE_BB.  */

static void
compute_cloog_iv_types (struct clast_stmt *stmt)
{
  if (!stmt)
    return;

  if (CLAST_STMT_IS_A (stmt, stmt_root))
    goto next;

  if (CLAST_STMT_IS_A (stmt, stmt_user))
    {
      CloogStatement *cs = ((struct clast_user_stmt *) stmt)->statement;
      poly_bb_p pbb = (poly_bb_p) cloog_statement_usr (cs);
      gimple_bb_p gbb = PBB_BLACK_BOX (pbb);

      if (!GBB_CLOOG_IV_TYPES (gbb))
        GBB_CLOOG_IV_TYPES (gbb) = htab_create (10, ivtype_map_elt_info,
                                                eq_ivtype_map_elts, free);

      compute_cloog_iv_types_1 (pbb, (struct clast_user_stmt *) stmt);
      goto next;
    }

  if (CLAST_STMT_IS_A (stmt, stmt_for))
    {
      struct clast_stmt *s = ((struct clast_for *) stmt)->body;
      compute_cloog_iv_types (s);
      goto next;
    }

  if (CLAST_STMT_IS_A (stmt, stmt_guard))
    {
      struct clast_stmt *s = ((struct clast_guard *) stmt)->then;
      compute_cloog_iv_types (s);
      goto next;
    }

  if (CLAST_STMT_IS_A (stmt, stmt_block))
    {
      struct clast_stmt *s = ((struct clast_block *) stmt)->body;
      compute_cloog_iv_types (s);
      goto next;
    }

  gcc_unreachable ();

 next:
  compute_cloog_iv_types (stmt->next);
}

/* Free the SCATTERING domain list.  */

static void
free_scattering (CloogDomainList *scattering)
{
  while (scattering)
    {
      CloogDomain *dom = cloog_domain (scattering);
      CloogDomainList *next = cloog_next_domain (scattering);

      cloog_domain_free (dom);
      free (scattering);
      scattering = next;
    }
}

/* Initialize Cloog's parameter names from the names used in GIMPLE.
   Initialize Cloog's iterator names, using 'graphite_iterator_%d'
   from 0 to scop_nb_loops (scop).  */

static void
initialize_cloog_names (scop_p scop, CloogProgram *prog)
{
  sese region = SCOP_REGION (scop);
  int i;
  int nb_iterators = scop_max_loop_depth (scop);
  int nb_scattering = cloog_program_nb_scattdims (prog);
  int nb_parameters = VEC_length (tree, SESE_PARAMS (region));
  char **iterators = XNEWVEC (char *, nb_iterators * 2);
  char **scattering = XNEWVEC (char *, nb_scattering);
  char **parameters= XNEWVEC (char *, nb_parameters);

  cloog_program_set_names (prog, cloog_names_malloc ());

  for (i = 0; i < nb_parameters; i++)
    {
      tree param = VEC_index (tree, SESE_PARAMS(region), i);
      const char *name = get_name (param);
      int len;

      if (!name)
        name = "T";

      len = strlen (name);
      len += 17;
      parameters[i] = XNEWVEC (char, len + 1);
      snprintf (parameters[i], len, "%s_%d", name, SSA_NAME_VERSION (param));
    }

  cloog_names_set_nb_parameters (cloog_program_names (prog), nb_parameters);
  cloog_names_set_parameters (cloog_program_names (prog), parameters);

  for (i = 0; i < nb_iterators; i++)
    {
      int len = 4 + 16;
      iterators[i] = XNEWVEC (char, len);
      snprintf (iterators[i], len, "git_%d", i);
    }

  cloog_names_set_nb_iterators (cloog_program_names (prog),
                                nb_iterators);
  cloog_names_set_iterators (cloog_program_names (prog),
                             iterators);

  for (i = 0; i < nb_scattering; i++)
    {
      int len = 5 + 16;
      scattering[i] = XNEWVEC (char, len);
      snprintf (scattering[i], len, "scat_%d", i);
    }

  cloog_names_set_nb_scattering (cloog_program_names (prog),
                                 nb_scattering);
  cloog_names_set_scattering (cloog_program_names (prog),
                              scattering);
}

/* Build cloog program for SCoP.  */

static void
build_cloog_prog (scop_p scop, CloogProgram *prog)
{
  int i;
  int max_nb_loops = scop_max_loop_depth (scop);
  poly_bb_p pbb;
  CloogLoop *loop_list = NULL;
  CloogBlockList *block_list = NULL;
  CloogDomainList *scattering = NULL;
  int nbs = 2 * max_nb_loops + 1;
  int *scaldims;

  cloog_program_set_context
    (prog, new_Cloog_Domain_from_ppl_Pointset_Powerset (SCOP_CONTEXT (scop)));
  nbs = unify_scattering_dimensions (scop);
  scaldims = (int *) xmalloc (nbs * (sizeof (int)));
  cloog_program_set_nb_scattdims (prog, nbs);
  initialize_cloog_names (scop, prog);

  for (i = 0; VEC_iterate (poly_bb_p, SCOP_BBS (scop), i, pbb); i++)
    {
      CloogStatement *stmt;
      CloogBlock *block;

      /* Dead code elimination: when the domain of a PBB is empty,
         don't generate code for the PBB.  */
      if (ppl_Pointset_Powerset_C_Polyhedron_is_empty (PBB_DOMAIN (pbb)))
        continue;

      /* Build the new statement and its block.  */
      stmt = cloog_statement_alloc (pbb_index (pbb));
      block = cloog_block_alloc (stmt, 0, NULL, pbb_dim_iter_domain (pbb));
      cloog_statement_set_usr (stmt, pbb);

      /* Build loop list.  */
      {
        CloogLoop *new_loop_list = cloog_loop_malloc ();
        cloog_loop_set_next (new_loop_list, loop_list);
        cloog_loop_set_domain
          (new_loop_list,
           new_Cloog_Domain_from_ppl_Pointset_Powerset (PBB_DOMAIN (pbb)));
        cloog_loop_set_block (new_loop_list, block);
        loop_list = new_loop_list;
      }

      /* Build block list.  */
      {
        CloogBlockList *new_block_list = cloog_block_list_malloc ();

        cloog_block_list_set_next (new_block_list, block_list);
        cloog_block_list_set_block (new_block_list, block);
        block_list = new_block_list;
      }

      /* Build scattering list.  */
      {
        /* XXX: Replace with cloog_domain_list_alloc(), when available.  */
        CloogDomainList *new_scattering
          = (CloogDomainList *) xmalloc (sizeof (CloogDomainList));
        ppl_Polyhedron_t scat;
        CloogDomain *dom;

        scat = PBB_TRANSFORMED_SCATTERING (pbb);
        dom = new_Cloog_Domain_from_ppl_Polyhedron (scat);

        cloog_set_next_domain (new_scattering, scattering);
        cloog_set_domain (new_scattering, dom);
        scattering = new_scattering;
      }
    }

  cloog_program_set_loop (prog, loop_list);
  cloog_program_set_blocklist (prog, block_list);

  for (i = 0; i < nbs; i++)
    scaldims[i] = 0 ;

  cloog_program_set_scaldims (prog, scaldims);

  /* Extract scalar dimensions to simplify the code generation problem.  */
  cloog_program_extract_scalars (prog, scattering);

  /* Apply scattering.  */
  cloog_program_scatter (prog, scattering);
  free_scattering (scattering);

  /* Iterators corresponding to scalar dimensions have to be extracted.  */
  cloog_names_scalarize (cloog_program_names (prog), nbs,
                         cloog_program_scaldims (prog));

  /* Free blocklist.  */
  {
    CloogBlockList *next = cloog_program_blocklist (prog);

    while (next)
      {
        CloogBlockList *toDelete = next;
        next = cloog_block_list_next (next);
        cloog_block_list_set_next (toDelete, NULL);
        cloog_block_list_set_block (toDelete, NULL);
        cloog_block_list_free (toDelete);
      }
    cloog_program_set_blocklist (prog, NULL);
  }
}

/* Return the options that will be used in GLOOG.  */

static CloogOptions *
set_cloog_options (void)
{
  CloogOptions *options = cloog_options_malloc ();

  /* Change cloog output language to C.  If we do use FORTRAN instead, cloog
     will stop e.g. with "ERROR: unbounded loops not allowed in FORTRAN.", if
     we pass an incomplete program to cloog.  */
  options->language = LANGUAGE_C;

  /* Enable complex equality spreading: removes dummy statements
     (assignments) in the generated code which repeats the
     substitution equations for statements.  This is useless for
     GLooG.  */
  options->esp = 1;

  /* Enable C pretty-printing mode: normalizes the substitution
     equations for statements.  */
  options->cpp = 1;

  /* Allow cloog to build strides with a stride width different to one.
     This example has stride = 4:

     for (i = 0; i < 20; i += 4)
       A  */
  options->strides = 1;

  /* Disable optimizations and make cloog generate source code closer to the
     input.  This is useful for debugging,  but later we want the optimized
     code.

     XXX: We can not disable optimizations, as loop blocking is not working
     without them.  */
  if (0)
    {
      options->f = -1;
      options->l = INT_MAX;
    }

  return options;
}

/* Prints STMT to STDERR.  */

void
print_clast_stmt (FILE *file, struct clast_stmt *stmt)
{
  CloogOptions *options = set_cloog_options ();

  pprint (file, stmt, 0, options);
  cloog_options_free (options);
}

/* Prints STMT to STDERR.  */

void
debug_clast_stmt (struct clast_stmt *stmt)
{
  print_clast_stmt (stderr, stmt);
}

/* Translate SCOP to a CLooG program and clast.  These two
   representations should be freed together: a clast cannot be used
   without a program.  */

cloog_prog_clast
scop_to_clast (scop_p scop)
{
  CloogOptions *options = set_cloog_options ();
  cloog_prog_clast pc;

  /* Connect new cloog prog generation to graphite.  */
  pc.prog = cloog_program_malloc ();
  build_cloog_prog (scop, pc.prog);
  pc.prog = cloog_program_generate (pc.prog, options);
  pc.stmt = cloog_clast_create (pc.prog, options);

  cloog_options_free (options);
  return pc;
}

/* Prints to FILE the code generated by CLooG for SCOP.  */

void
print_generated_program (FILE *file, scop_p scop)
{
  CloogOptions *options = set_cloog_options ();
  cloog_prog_clast pc = scop_to_clast (scop);

  fprintf (file, "       (prog: \n");
  cloog_program_print (file, pc.prog);
  fprintf (file, "       )\n");

  fprintf (file, "       (clast: \n");
  pprint (file, pc.stmt, 0, options);
  fprintf (file, "       )\n");

  cloog_options_free (options);
  cloog_clast_free (pc.stmt);
  cloog_program_free (pc.prog);
}

/* Prints to STDERR the code generated by CLooG for SCOP.  */

void
debug_generated_program (scop_p scop)
{
  print_generated_program (stderr, scop);
}

/* Add CLooG names to parameter index.  The index is used to translate
   back from CLooG names to GCC trees.  */

static void
create_params_index (htab_t index_table, CloogProgram *prog) {
  CloogNames* names = cloog_program_names (prog);
  int nb_parameters = cloog_names_nb_parameters (names);
  char **parameters = cloog_names_parameters (names);
  int i;

  for (i = 0; i < nb_parameters; i++)
    save_clast_name_index (index_table, parameters[i], i);
}

/* GIMPLE Loop Generator: generates loops from STMT in GIMPLE form for
   the given SCOP.  Return true if code generation succeeded.
   BB_PBB_MAPPING is a basic_block and it's related poly_bb_p mapping.
*/

bool
gloog (scop_p scop, htab_t bb_pbb_mapping)
{
  edge new_scop_exit_edge = NULL;
  VEC (tree, heap) *newivs = VEC_alloc (tree, heap, 10);
  loop_p context_loop;
  sese region = SCOP_REGION (scop);
  ifsese if_region = NULL;
  htab_t rename_map, newivs_index, params_index;
  cloog_prog_clast pc;

  timevar_push (TV_GRAPHITE_CODE_GEN);
  gloog_error = false;

  pc = scop_to_clast (scop);

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "\nCLAST generated by CLooG: \n");
      print_clast_stmt (dump_file, pc.stmt);
      fprintf (dump_file, "\n");
    }

  recompute_all_dominators ();
  graphite_verify ();

  if_region = move_sese_in_condition (region);
  sese_insert_phis_for_liveouts (region,
                                 if_region->region->exit->src,
                                 if_region->false_region->exit,
                                 if_region->true_region->exit);
  recompute_all_dominators ();
  graphite_verify ();

  context_loop = SESE_ENTRY (region)->src->loop_father;
  compute_cloog_iv_types (pc.stmt);
  rename_map = htab_create (10, rename_map_elt_info, eq_rename_map_elts, free);
  newivs_index = htab_create (10, clast_name_index_elt_info,
                              eq_clast_name_indexes, free);
  params_index = htab_create (10, clast_name_index_elt_info,
                              eq_clast_name_indexes, free);

  create_params_index (params_index, pc.prog);

  new_scop_exit_edge = translate_clast (region, context_loop, pc.stmt,
                                        if_region->true_region->entry,
                                        rename_map, &newivs, newivs_index,
                                        bb_pbb_mapping, 1, params_index);
  graphite_verify ();
  sese_adjust_liveout_phis (region, rename_map,
                            if_region->region->exit->src,
                            if_region->false_region->exit,
                            if_region->true_region->exit);
  scev_reset_htab ();
  rename_nb_iterations (rename_map);
  recompute_all_dominators ();
  graphite_verify ();

  if (gloog_error)
    set_ifsese_condition (if_region, integer_zero_node);

  free (if_region->true_region);
  free (if_region->region);
  free (if_region);

  htab_delete (rename_map);
  htab_delete (newivs_index);
  htab_delete (params_index);
  VEC_free (tree, heap, newivs);
  cloog_clast_free (pc.stmt);
  cloog_program_free (pc.prog);
  timevar_pop (TV_GRAPHITE_CODE_GEN);

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      loop_p loop;
      loop_iterator li;
      int num_no_dependency = 0;

      FOR_EACH_LOOP (li, loop, 0)
        if (loop->can_be_parallel)
          num_no_dependency++;

      fprintf (dump_file, "\n%d loops carried no dependency.\n",
               num_no_dependency);
    }

  return !gloog_error;
}

#endif