diff mbox

[GSoC] generation of Gimple loops with empty bodies

Message ID CABGF_gcs1qPGu+H2fjCnKqnP3=sH3etWkf3vynrgyiDD9qJhmA@mail.gmail.com
State New
Headers show

Commit Message

Roman Gareev July 8, 2014, 12:47 p.m. UTC
> Surprising. Is the symbol defined in libisl.so? You could use objdump to
> check?

If I am not mistaken, objdump shows that libisl.so contains it.

objdump -d libisl.so.10.2.2 | grep isl_ast_expr_get_val
0000000000060380 <isl_ast_expr_get_val>:
   60383: 74 4b                 je     603d0 <isl_ast_expr_get_val+0x50>
   60389: 75 0d                 jne    60398 <isl_ast_expr_get_val+0x18




I've attached the version, which uses map instead of hash table.

--
                                   Cheers, Roman Gareev

Comments

Tobias Grosser July 8, 2014, 1:18 p.m. UTC | #1
On 08/07/2014 14:47, Roman Gareev wrote:
>> Surprising. Is the symbol defined in libisl.so? You could use objdump to
>> >check?
> If I am not mistaken, objdump shows that libisl.so contains it.
>
> objdump -d libisl.so.10.2.2 | grep isl_ast_expr_get_val
> 0000000000060380 <isl_ast_expr_get_val>:
>     60383: 74 4b                 je     603d0 <isl_ast_expr_get_val+0x50>
>     60389: 75 0d                 jne    60398 <isl_ast_expr_get_val+0x18

I would use -x to see the headers. This should tell you if it is defined
or only used there.

> +#include "graphite-htab.h"

Is this still needed?

(Just a question, no need to act on it if it is still needed)

> +struct id_comp
> +{
> +  bool operator()(isl_id *id1, isl_id *id2) const
> +  {
> +    const char *name1 = isl_id_get_name (id1);
> +    const char *name2 = isl_id_get_name (id2);
> +    return strcmp (name1, name2) == 0;
> +  }
> +};
No need to provide this. Comparing by pointer should be fine.

> +
> +/* IVS_PARAMS_MAP maps ISL's scattering and parameter identifiers
> +   to corresponding trees.  */
> +typedef struct ivs_params {
> +  std::map<isl_id *, tree, id_comp> ivs_params_map;

What about calling it isl_id_to_tree?

> +  sese region;

Is this region needed?

> +static tree
> +gcc_expression_from_isl_expression (tree type, __isl_keep isl_ast_expr *,
> +				    ivs_params_p ip);

I would make those functions __isl_take the expression.

> +
> +/* Returns the tree variable from the name of isl_id, which is stored
> +   in the isl_ast_expr EXPR_ID that was given in ISL representation.  */

This takes a couple of turns. What about:

"Return the tree variable that corresponds to the given isl ast identifier
  expression (an isl_ast_expr of type isl_ast_expr_id)."

> +
> +static tree
> +gcc_expression_from_isl_ast_expr_id (__isl_keep isl_ast_expr *expr_id,
> +				     ivs_params_p ip)
> +{
> +  gcc_assert (isl_ast_expr_get_type (expr_id) == isl_ast_expr_id);
> +  isl_id *tmp_isl_id = isl_ast_expr_get_id (expr_id);
> +  std::map<isl_id *, tree, id_comp>::iterator res;
> +  res = ip->ivs_params_map.find (tmp_isl_id);
> +  isl_id_free (tmp_isl_id);
> +  gcc_assert (res != ip->ivs_params_map.end ());

Maybe add an assert message ala "Could not map isl_id to tree expression"?

> +  return res->second;
> +}
> +
> +/* Converts a isl_ast_expr_int expression E to a GCC expression tree of

Converts _aN_ isl_ast_expr_int ...
          ^^^^

> +   type TYPE.  */
> +
> +static tree
> +gcc_expression_from_isl_expr_int (tree type, __isl_keep isl_ast_expr *expr)
> +{
> +  gcc_assert (isl_ast_expr_get_type (expr) == isl_ast_expr_int);
> +  isl_int val;
> +  isl_int_init (val);
> +  if (isl_ast_expr_get_int (expr, &val) == -1)
> +    {
> +      isl_int_clear (val);

Sorry, but this still needs to be debugged. :-( I am too busy to do it
myself, so i am afraid you may just need to dig into it yourself. :-(

> +/* Converts a binary isl_ast_expr_op expression E to a GCC expression tree of
> +   type TYPE.  */
> +
> +static tree
> +binary_op_to_tree (tree type, __isl_keep isl_ast_expr *expr, ivs_params_p ip)
> +{
> +  isl_ast_expr *arg_expr = isl_ast_expr_get_op_arg (expr, 0);
> +  tree tree_lhs_expr = gcc_expression_from_isl_expression (type, arg_expr, ip);
> +  isl_ast_expr_free (arg_expr);

If the from_isl_expression functions become __isl_take this free becomes
unnecessary.

> +/* Converts a isl_ast_expr_op expression E with unknown number of arguments

Converts _an_ isl

> +/* Converts an isl_ast_expr_op expression E to a GCC expression tree of
> +   type TYPE.  */
> +
> +static tree
> +gcc_expression_from_isl_expr_op (tree type, __isl_keep isl_ast_expr *expr,
> +				 ivs_params_p ip)
> +{
> +  gcc_assert (isl_ast_expr_get_type (expr) == isl_ast_expr_op);
> +  switch (isl_ast_expr_get_op_type (expr))
> +    {
> +    /* These isl ast expressions are not supported yet.  */
> +    case isl_ast_op_error:
> +    case isl_ast_op_call:
> +    case isl_ast_op_and_then:
> +    case isl_ast_op_or_else:
> +    case isl_ast_op_pdiv_q:
> +    case isl_ast_op_pdiv_r:
> +    case isl_ast_op_select:
> +      gcc_unreachable ();
> +
> +    case isl_ast_op_max:
> +    case isl_ast_op_min:
> +      return nary_op_to_tree (type, expr, ip);
> +
> +    case isl_ast_op_add:
> +    case isl_ast_op_sub:
> +    case isl_ast_op_mul:
> +    case isl_ast_op_div:
> +    case isl_ast_op_fdiv_q:
> +    case isl_ast_op_and:
> +    case isl_ast_op_or:
> +    case isl_ast_op_eq:
> +    case isl_ast_op_le:
> +    case isl_ast_op_lt:
> +    case isl_ast_op_ge:
> +    case isl_ast_op_gt:
> +      return binary_op_to_tree (type, expr, ip);
> +
> +    case isl_ast_op_minus:
> +      return unary_op_to_tree (type, expr, ip);
> +
> +    case isl_ast_op_cond:
> +      return ternary_op_to_tree (type, expr, ip);
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return NULL_TREE;
> +}
> +
> +/* Converts a ISL AST expression E back to a GCC expression tree of

_an_

> +/* We use this function to get the upper bound because of the form,
> +   which is used by isl to represent loops:
> +
> +   for (iterator = init; cond; iterator += inc)
> +
> +   {
> +
> +     ...
> +
> +   }
> +
> +   The loop condition is an arbitrary expression, which contains the
> +   current loop iterator.

(e.g. iterator + 3 < B && C > iterator + A)

> +
> +   We have to know the upper bound of the iterator to generate a loop
> +   in Gimple form. It can be obtained from the special representation
> +   of the loop condition, which is generated by isl,
> +   if the ast_build_atomic_upper_bound option is set. In this case,
> +   isl generates a loop condition that consists of the current loop
> +   iterator, + an operator (< or <=) and an expression not involving
> +   the iterator, which is processed and returned by this function.  */

e.g (iterator <= upper-bound-expression-without-iterator)

> +static __isl_give isl_ast_expr *
> +get_upper_bound (__isl_keep isl_ast_node *node_for)
> +{
> +  gcc_assert (isl_ast_node_get_type (node_for) == isl_ast_node_for);
> +  isl_ast_expr *for_cond = isl_ast_node_for_get_cond (node_for);
> +  gcc_assert (isl_ast_expr_get_type (for_cond) == isl_ast_expr_op);
> +  isl_ast_expr *res;
> +  switch (isl_ast_expr_get_op_type (for_cond))
> +    {
> +    case isl_ast_op_le:
> +      res = isl_ast_expr_get_op_arg (for_cond, 1);
> +      break;
> +
> +    case isl_ast_op_lt:
> +      {
> +        // (iteraotr < ub) => (iterator <= ub - 1)

iterator

> +        isl_val *one = isl_val_int_from_si (isl_ast_expr_get_ctx (for_cond), 1);
> +        isl_ast_expr *ub = isl_ast_expr_get_op_arg (for_cond, 1);
> +        res = isl_ast_expr_sub (ub, isl_ast_expr_from_val (one));
> +        break;
> +      }
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +  isl_ast_expr_free (for_cond);
> +  return res;
> +}
> +
> +/* All loops generated by create_empty_loop_on_edge have the form of
> +   a post-test loop:
> +
> +   do
> +
> +   {
> +     body of the loop;
> +   } while (lower bound < upper bound);
> +
> +   We create a new if region protecting the loop to be executed, if
> +   the execution count is zero (lower bound > upper bound). In this case,
> +   it is subsequently removed by dead code elimination.  */

The last sentence is unclear. Are you saying the loop will be removed or
that the condition will be removed in case it is always true. Also, what
about cases where the condition remains?

> +/* Add tree representations and names of parameters to ivs_params  */
> +
> +static void
> +add_parameters_to_ivs_params (scop_p scop, ivs_params_p ip)
> +{
> +  sese region = SCOP_REGION (scop);
> +  int i;
> +  int nb_parameters = SESE_PARAMS (region).length ();
> +  gcc_assert (nb_parameters == (short) isl_set_dim (scop->context,
> +						    isl_dim_param));
> +
> +  for (i = 0; i < nb_parameters; i++)
> +    {
> +      tree param = SESE_PARAMS (region)[i];
> +      const char *name = get_name (param);
> +      int len;
> +      char *parameter;
> +
> +      if (!name)
> +	name = "T";
> +      len = strlen (name);
> +      parameter = XCNEWVEC (char, len + 1);
> +      snprintf (parameter, len, "%s", name);
> +      isl_id *tmp_id = isl_id_alloc (scop->ctx, parameter, NULL);
> +      ip->ivs_params_map[tmp_id] = param;
> +      free (parameter);
> +    }
> +}

I see now possibly why you compared the isl_id's by name above. At this
point, all parameters should already have ids assigned. We should use 
those very id's to add the param locations into this map.

>   /* Generates a build, which specifies the constraints on the parameters.  */
>
> -static isl_ast_build *
> +static __isl_give isl_ast_build *
>   generate_isl_context (scop_p scop)
>   {
>     isl_set *context_isl = isl_set_params (isl_set_copy (scop->context));
> @@ -77,7 +640,7 @@
>   /* Generates a schedule, which specifies an order used to
>      visit elements in a domain.  */
>
> -static isl_union_map *
> +static __isl_give isl_union_map *
>   generate_isl_schedule (scop_p scop)
>   {
>     int i;
> @@ -102,9 +665,16 @@
>     return schedule_isl;
>   }
>
> -static isl_ast_node *
> -scop_to_isl_ast (scop_p scop)
> +static __isl_give isl_ast_node *
> +scop_to_isl_ast (scop_p scop, ivs_params_p ip)

Those changes are unrelated and are part of the other patch, right?

>   {
> +  /* Generate loop upper bounds that consist of the current loop iterator,
> +  an operator (< or <=) and an expression not involving the iterator.
> +  If this option is not set, then the current loop iterator may appear several
> +  times in the upper bound. See the isl manual for more details.  */
> +  isl_options_set_ast_build_atomic_upper_bound (scop->ctx, true);
> +
> +  add_parameters_to_ivs_params (scop, ip);
>     isl_union_map *schedule_isl = generate_isl_schedule (scop);
>     isl_ast_build *context_isl = generate_isl_context (scop);
>     isl_ast_node *ast_isl = isl_ast_build_ast_from_schedule (context_isl,
> @@ -117,21 +687,62 @@
>      the given SCOP.  Return true if code generation succeeded.
>
>      FIXME: This is not yet a full implementation of the code generator
> -          with ISL ASTs. Generation of GIMPLE code is have to be added.  */
> +          with ISL ASTs. Generation of GIMPLE code has to be completed.  */
>
>   bool
>   graphite_regenerate_ast_isl (scop_p scop)
>   {
> +  loop_p context_loop;
> +  sese region = SCOP_REGION (scop);
> +  ifsese if_region = NULL;
> +  isl_ast_node *root_node;
> +  struct ivs_params ip;
> +
>     timevar_push (TV_GRAPHITE_CODE_GEN);
>     graphite_regenerate_error = false;
> -  isl_ast_node *root_node = scop_to_isl_ast (scop);
> +
> +  ip.region = region;

Is this needed? ip.region seems unused.

Cheers,
Tobias
diff mbox

Patch

Index: gcc/graphite-isl-ast-to-gimple.c
===================================================================
--- gcc/graphite-isl-ast-to-gimple.c	(revision 212294)
+++ gcc/graphite-isl-ast-to-gimple.c	(working copy)
@@ -42,16 +42,549 @@ 
 #include "cfgloop.h"
 #include "tree-data-ref.h"
 #include "sese.h"
+#include "tree-ssa-loop-manip.h"
+#include "tree-scalar-evolution.h"
+#include <map>
 
 #ifdef HAVE_cloog
 #include "graphite-poly.h"
 #include "graphite-isl-ast-to-gimple.h"
+#include "graphite-htab.h"
 
 /* This flag is set when an error occurred during the translation of
    ISL AST to Gimple.  */
 
 static bool graphite_regenerate_error;
 
+/* We always use signed 128, until isl is able to give information about
+types  */
+
+static tree *graphite_expression_size_type = &int128_integer_type_node;
+
+/* Converts a GMP constant VAL to a tree and returns it.  */
+
+static tree
+gmp_cst_to_tree (tree type, mpz_t val)
+{
+  tree t = type ? type : integer_type_node;
+  mpz_t tmp;
+
+  mpz_init (tmp);
+  mpz_set (tmp, val);
+  wide_int wi = wi::from_mpz (t, tmp, true);
+  mpz_clear (tmp);
+
+  return wide_int_to_tree (t, wi);
+}
+
+/* Verifies properties that GRAPHITE should maintain during translation.  */
+
+static inline void
+graphite_verify (void)
+{
+#ifdef ENABLE_CHECKING
+  verify_loop_structure ();
+  verify_loop_closed_ssa (true);
+#endif
+}
+
+/* The comparison function for ivs_params_map  */
+
+struct id_comp
+{
+  bool operator()(isl_id *id1, isl_id *id2) const
+  {
+    const char *name1 = isl_id_get_name (id1);
+    const char *name2 = isl_id_get_name (id2);
+    return strcmp (name1, name2) == 0;
+  }
+};
+
+/* IVS_PARAMS_MAP maps ISL's scattering and parameter identifiers
+   to corresponding trees.  */
+
+typedef struct ivs_params {
+  std::map<isl_id *, tree, id_comp> ivs_params_map;
+  sese region;
+} *ivs_params_p;
+
+/* Free all memory allocated for ISL's identifiers.  */
+
+void ivs_params_clear (ivs_params_p ip)
+{
+  std::map<isl_id *, tree, id_comp>::iterator it;
+  for (it = ip->ivs_params_map.begin (); it != ip->ivs_params_map.end (); it++)
+    {
+      isl_id_free (it->first);
+    }
+}
+
+static tree
+gcc_expression_from_isl_expression (tree type, __isl_keep isl_ast_expr *,
+				    ivs_params_p ip);
+
+/* Returns the tree variable from the name of isl_id, which is stored
+   in the isl_ast_expr EXPR_ID that was given in ISL representation.  */
+
+static tree
+gcc_expression_from_isl_ast_expr_id (__isl_keep isl_ast_expr *expr_id,
+				     ivs_params_p ip)
+{
+  gcc_assert (isl_ast_expr_get_type (expr_id) == isl_ast_expr_id);
+  isl_id *tmp_isl_id = isl_ast_expr_get_id (expr_id);
+  std::map<isl_id *, tree, id_comp>::iterator res;
+  res = ip->ivs_params_map.find (tmp_isl_id);
+  isl_id_free (tmp_isl_id);
+  gcc_assert (res != ip->ivs_params_map.end ());
+  return res->second;
+}
+
+/* Converts a isl_ast_expr_int expression E to a GCC expression tree of
+   type TYPE.  */
+
+static tree
+gcc_expression_from_isl_expr_int (tree type, __isl_keep isl_ast_expr *expr)
+{
+  gcc_assert (isl_ast_expr_get_type (expr) == isl_ast_expr_int);
+  isl_int val;
+  isl_int_init (val);
+  if (isl_ast_expr_get_int (expr, &val) == -1)
+    {
+      isl_int_clear (val);
+      return NULL_TREE;
+    }
+  else
+    return gmp_cst_to_tree (type, val);
+}
+
+/* Converts a binary isl_ast_expr_op expression E to a GCC expression tree of
+   type TYPE.  */
+
+static tree
+binary_op_to_tree (tree type, __isl_keep isl_ast_expr *expr, ivs_params_p ip)
+{
+  isl_ast_expr *arg_expr = isl_ast_expr_get_op_arg (expr, 0);
+  tree tree_lhs_expr = gcc_expression_from_isl_expression (type, arg_expr, ip);
+  isl_ast_expr_free (arg_expr);
+  arg_expr = isl_ast_expr_get_op_arg (expr, 1);
+  tree tree_rhs_expr = gcc_expression_from_isl_expression (type, arg_expr, ip);
+  isl_ast_expr_free (arg_expr);
+  switch (isl_ast_expr_get_op_type (expr))
+    {
+    case isl_ast_op_add:
+      return fold_build2 (PLUS_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_sub:
+      return fold_build2 (MINUS_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_mul:
+      return fold_build2 (MULT_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_div:
+      return fold_build2 (EXACT_DIV_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_fdiv_q:
+      return fold_build2 (FLOOR_DIV_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_and:
+      return fold_build2 (TRUTH_ANDIF_EXPR, type,
+			  tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_or:
+      return fold_build2 (TRUTH_ORIF_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_eq:
+      return fold_build2 (EQ_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_le:
+      return fold_build2 (LE_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_lt:
+      return fold_build2 (LT_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_ge:
+      return fold_build2 (GE_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    case isl_ast_op_gt:
+      return fold_build2 (GT_EXPR, type, tree_lhs_expr, tree_rhs_expr);
+
+    default:
+      gcc_unreachable ();
+    }
+}
+
+/* Converts a ternary isl_ast_expr_op expression E to a GCC expression tree of
+   type TYPE.  */
+
+static tree
+ternary_op_to_tree (tree type, __isl_keep isl_ast_expr *expr, ivs_params_p ip)
+{
+  gcc_assert (isl_ast_expr_get_op_type (expr) == isl_ast_op_minus);
+  isl_ast_expr *arg_expr = isl_ast_expr_get_op_arg (expr, 0);
+  tree tree_first_expr
+    = gcc_expression_from_isl_expression (type, arg_expr, ip);
+  isl_ast_expr_free (arg_expr);
+  arg_expr = isl_ast_expr_get_op_arg (expr, 1);
+  tree tree_second_expr
+    = gcc_expression_from_isl_expression (type, arg_expr, ip);
+  isl_ast_expr_free (arg_expr);
+  arg_expr = isl_ast_expr_get_op_arg (expr, 2);
+  tree tree_third_expr
+    = gcc_expression_from_isl_expression (type, arg_expr, ip);
+  isl_ast_expr_free (arg_expr);
+  return fold_build3 (COND_EXPR, type, tree_first_expr,
+		      tree_second_expr, tree_third_expr);
+}
+
+/* Converts a unary isl_ast_expr_op expression E to a GCC expression tree of
+   type TYPE.  */
+
+static tree
+unary_op_to_tree (tree type, __isl_keep isl_ast_expr *expr, ivs_params_p ip)
+{
+  gcc_assert (isl_ast_expr_get_op_type (expr) == isl_ast_op_minus);
+  isl_ast_expr *arg_expr = isl_ast_expr_get_op_arg (expr, 0);
+  tree tree_expr = gcc_expression_from_isl_expression (type, arg_expr, ip);
+  isl_ast_expr_free (arg_expr);
+  return fold_build1 (NEGATE_EXPR, type, tree_expr);
+}
+
+/* Converts a isl_ast_expr_op expression E with unknown number of arguments
+   to a GCC expression tree of type TYPE.  */
+
+static tree
+nary_op_to_tree (tree type, __isl_keep isl_ast_expr *expr, ivs_params_p ip)
+{
+  enum tree_code op_code;
+  switch (isl_ast_expr_get_op_type (expr))
+    {
+    case isl_ast_op_max:
+      op_code = MAX_EXPR;
+      break;
+
+    case isl_ast_op_min:
+      op_code = MIN_EXPR;
+      break;
+
+    default:
+      gcc_unreachable ();    
+    }
+  isl_ast_expr *arg_expr = isl_ast_expr_get_op_arg (expr, 0);
+  tree res = gcc_expression_from_isl_expression (type, arg_expr, ip);
+  isl_ast_expr_free (arg_expr);
+  int i;
+  for (i = 1; i < isl_ast_expr_get_op_n_arg (expr); i++)
+    {
+      arg_expr = isl_ast_expr_get_op_arg (expr, i);
+      tree t = gcc_expression_from_isl_expression (type, arg_expr, ip);
+      res = fold_build2 (op_code, type, res, t);
+      isl_ast_expr_free (arg_expr);
+    }
+  return res;
+}
+
+
+/* Converts an isl_ast_expr_op expression E to a GCC expression tree of
+   type TYPE.  */
+
+static tree
+gcc_expression_from_isl_expr_op (tree type, __isl_keep isl_ast_expr *expr,
+				 ivs_params_p ip)
+{
+  gcc_assert (isl_ast_expr_get_type (expr) == isl_ast_expr_op);
+  switch (isl_ast_expr_get_op_type (expr))
+    {
+    /* These isl ast expressions are not supported yet.  */
+    case isl_ast_op_error:
+    case isl_ast_op_call:
+    case isl_ast_op_and_then:
+    case isl_ast_op_or_else:
+    case isl_ast_op_pdiv_q:
+    case isl_ast_op_pdiv_r:
+    case isl_ast_op_select:
+      gcc_unreachable ();
+
+    case isl_ast_op_max:
+    case isl_ast_op_min:
+      return nary_op_to_tree (type, expr, ip);
+
+    case isl_ast_op_add:
+    case isl_ast_op_sub:
+    case isl_ast_op_mul:
+    case isl_ast_op_div:
+    case isl_ast_op_fdiv_q:
+    case isl_ast_op_and:
+    case isl_ast_op_or:
+    case isl_ast_op_eq:
+    case isl_ast_op_le:
+    case isl_ast_op_lt:
+    case isl_ast_op_ge:
+    case isl_ast_op_gt:
+      return binary_op_to_tree (type, expr, ip);
+
+    case isl_ast_op_minus:
+      return unary_op_to_tree (type, expr, ip);
+
+    case isl_ast_op_cond:
+      return ternary_op_to_tree (type, expr, ip);
+
+    default:
+      gcc_unreachable ();
+    }
+
+  return NULL_TREE;
+}
+
+/* Converts a ISL AST expression E back to a GCC expression tree of
+   type TYPE.  */
+
+static tree
+gcc_expression_from_isl_expression (tree type, __isl_keep isl_ast_expr *expr,
+				    ivs_params_p ip)
+{
+  switch (isl_ast_expr_get_type (expr))
+    {
+    case isl_ast_expr_id:
+      return gcc_expression_from_isl_ast_expr_id (expr, ip);
+
+    case isl_ast_expr_int:
+      return gcc_expression_from_isl_expr_int (type, expr);
+
+    case isl_ast_expr_op:
+      return gcc_expression_from_isl_expr_op (type, expr, ip);
+
+    default:
+      gcc_unreachable ();
+    }
+
+  return NULL_TREE;
+}
+
+/* Creates a new LOOP corresponding to isl_ast_node_for.  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
+   ISL's scattering name to the induction variable created for the
+   loop of STMT.  The new induction variable is inserted in the NEWIVS
+   vector and is of type TYPE.  */
+
+static struct loop *
+graphite_create_new_loop (edge entry_edge, __isl_keep isl_ast_node *node_for,
+			  loop_p outer, tree type, tree lb, tree ub,
+			  ivs_params_p ip)
+{
+  isl_ast_expr *for_inc = isl_ast_node_for_get_inc (node_for);
+  tree stride = gcc_expression_from_isl_expression (type, for_inc, ip);
+  isl_ast_expr_free (for_inc);
+  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);
+
+  isl_ast_expr *for_iterator = isl_ast_node_for_get_iterator (node_for);
+  isl_id *id = isl_ast_expr_get_id (for_iterator);
+  std::map<isl_id *, tree, id_comp>::iterator it;
+  it = ip->ivs_params_map.find (id);
+  if (it == ip->ivs_params_map.end ())
+    ip->ivs_params_map[id] = iv;
+  else
+    {
+      it->second = iv;
+      isl_id_free (id);
+    }
+  isl_ast_expr_free (for_iterator);
+  return loop;
+}
+
+static edge
+translate_isl_ast (loop_p context_loop, __isl_keep isl_ast_node *node,
+		   edge next_e, ivs_params_p ip);
+
+/* Create the loop for a isl_ast_node_for.
+
+   - NEXT_E is the edge where new generated code should be attached.  */
+
+static edge
+translate_isl_ast_for_loop (loop_p context_loop,
+			    __isl_keep isl_ast_node *node_for, edge next_e,
+			    tree type, tree lb, tree ub,
+			    ivs_params_p ip)
+{
+  gcc_assert (isl_ast_node_get_type (node_for) == isl_ast_node_for);
+  struct loop *loop = graphite_create_new_loop (next_e, node_for, context_loop,
+						type, lb, ub, ip);
+  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.  */
+  isl_ast_node *for_body = isl_ast_node_for_get_body (node_for);
+  next_e = translate_isl_ast (loop, for_body, to_body, ip);
+  isl_ast_node_free (for_body);
+  redirect_edge_succ_nodup (next_e, after);
+  set_immediate_dominator (CDI_DOMINATORS, next_e->dest, next_e->src);
+
+  /* TODO: Add checking for the loop parallelism.  */
+
+  return last_e;
+}
+
+/* We use this function to get the upper bound because of the form,
+   which is used by isl to represent loops:
+
+   for (iterator = init; cond; iterator += inc)
+
+   {
+
+     ...
+
+   }
+
+   The loop condition is an arbitrary expression, which contains the
+   current loop iterator.
+
+   We have to know the upper bound of the iterator to generate a loop
+   in Gimple form. It can be obtained from the special representation
+   of the loop condition, which is generated by isl,
+   if the ast_build_atomic_upper_bound option is set. In this case,
+   isl generates a loop condition that consists of the current loop
+   iterator, + an operator (< or <=) and an expression not involving
+   the iterator, which is processed and returned by this function.  */
+
+static __isl_give isl_ast_expr *
+get_upper_bound (__isl_keep isl_ast_node *node_for)
+{
+  gcc_assert (isl_ast_node_get_type (node_for) == isl_ast_node_for);
+  isl_ast_expr *for_cond = isl_ast_node_for_get_cond (node_for);
+  gcc_assert (isl_ast_expr_get_type (for_cond) == isl_ast_expr_op);
+  isl_ast_expr *res;
+  switch (isl_ast_expr_get_op_type (for_cond))
+    {
+    case isl_ast_op_le:
+      res = isl_ast_expr_get_op_arg (for_cond, 1);
+      break;
+
+    case isl_ast_op_lt:
+      {
+        // (iteraotr < ub) => (iterator <= ub - 1)
+        isl_val *one = isl_val_int_from_si (isl_ast_expr_get_ctx (for_cond), 1);
+        isl_ast_expr *ub = isl_ast_expr_get_op_arg (for_cond, 1);
+        res = isl_ast_expr_sub (ub, isl_ast_expr_from_val (one));
+        break;
+      }
+
+    default:
+      gcc_unreachable ();
+    }
+  isl_ast_expr_free (for_cond);
+  return res;
+}
+
+/* All loops generated by create_empty_loop_on_edge have the form of
+   a post-test loop:
+
+   do
+
+   {
+     body of the loop;
+   } while (lower bound < upper bound);
+
+   We create a new if region protecting the loop to be executed, if
+   the execution count is zero (lower bound > upper bound). In this case,
+   it is subsequently removed by dead code elimination.  */
+
+static edge
+graphite_create_new_loop_guard (edge entry_edge,
+				__isl_keep isl_ast_node *node_for, tree *type,
+				tree *lb, tree *ub, ivs_params_p ip)
+{
+  gcc_assert (isl_ast_node_get_type (node_for) == isl_ast_node_for);
+  tree cond_expr;
+  edge exit_edge;
+
+  *type = *graphite_expression_size_type;
+  isl_ast_expr *for_init = isl_ast_node_for_get_init (node_for);
+  *lb = gcc_expression_from_isl_expression (*type, for_init, ip);
+  isl_ast_expr_free (for_init);
+  isl_ast_expr *upper_bound = get_upper_bound (node_for);
+  *ub = gcc_expression_from_isl_expression (*type, upper_bound, ip);
+  isl_ast_expr_free (upper_bound);
+  
+  /* When ub is simply a constant or a parameter, use lb <= ub.  */
+  if (TREE_CODE (*ub) == INTEGER_CST || TREE_CODE (*ub) == SSA_NAME)
+    cond_expr = fold_build2 (LE_EXPR, boolean_type_node, *lb, *ub);
+  else
+    {
+      tree one = (POINTER_TYPE_P (*type)
+		  ? convert_to_ptrofftype (integer_one_node)
+		  : fold_convert (*type, integer_one_node));
+      /* 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^k-1 due to integer overflow, and the condition lb <= ub
+	 is true, even if we do not want this.  However lb < ub + 1 is false,
+	 as expected.  */
+      tree ub_one = fold_build2 (POINTER_TYPE_P (*type) ? POINTER_PLUS_EXPR
+				 : PLUS_EXPR, *type, *ub, one);
+
+      cond_expr = fold_build2 (LT_EXPR, boolean_type_node, *lb, ub_one);
+    }
+
+  exit_edge = create_empty_if_region_on_edge (entry_edge, cond_expr);
+
+  return exit_edge;
+}
+
+/* Translates an isl_ast_node_for to Gimple. */
+
+static edge
+translate_isl_ast_node_for (loop_p context_loop, __isl_keep isl_ast_node *node,
+			    edge next_e, ivs_params_p ip)
+{
+  gcc_assert (isl_ast_node_get_type (node) == isl_ast_node_for);
+  tree type, lb, ub;
+  edge last_e = graphite_create_new_loop_guard (next_e, node, &type,
+						&lb, &ub, ip);
+  edge true_e = get_true_edge_from_guard_bb (next_e->dest);
+
+  translate_isl_ast_for_loop (context_loop, node, true_e,
+			      type, lb, ub, ip);
+  return last_e;
+}
+
+/* Translates an ISL AST node NODE to GCC representation in the
+   context of a SESE.  */
+
+static edge
+translate_isl_ast (loop_p context_loop, __isl_keep isl_ast_node *node,
+		   edge next_e, ivs_params_p ip)
+{
+  switch (isl_ast_node_get_type (node))
+    {
+    case isl_ast_node_error:
+      gcc_unreachable ();
+
+    case isl_ast_node_for:
+      return translate_isl_ast_node_for (context_loop, node,
+					 next_e, ip);
+
+    case isl_ast_node_if:
+      return next_e;
+
+    case isl_ast_node_user:
+      return next_e;
+
+    case isl_ast_node_block:
+      return next_e;
+
+    default:
+      gcc_unreachable ();
+    }
+}
+
 /* Prints NODE to FILE.  */
 
 void
@@ -65,9 +598,39 @@ 
   isl_printer_free (prn);
 }
 
+/* Add tree representations and names of parameters to ivs_params  */
+
+static void
+add_parameters_to_ivs_params (scop_p scop, ivs_params_p ip)
+{
+  sese region = SCOP_REGION (scop);
+  int i;
+  int nb_parameters = SESE_PARAMS (region).length ();
+  gcc_assert (nb_parameters == (short) isl_set_dim (scop->context,
+						    isl_dim_param));
+
+  for (i = 0; i < nb_parameters; i++)
+    {
+      tree param = SESE_PARAMS (region)[i];
+      const char *name = get_name (param);
+      int len;
+      char *parameter;
+
+      if (!name)
+	name = "T";
+      len = strlen (name);
+      parameter = XCNEWVEC (char, len + 1);
+      snprintf (parameter, len, "%s", name);
+      isl_id *tmp_id = isl_id_alloc (scop->ctx, parameter, NULL);
+      ip->ivs_params_map[tmp_id] = param;
+      free (parameter);
+    }
+}
+
+
 /* Generates a build, which specifies the constraints on the parameters.  */
 
-static isl_ast_build *
+static __isl_give isl_ast_build *
 generate_isl_context (scop_p scop)
 {
   isl_set *context_isl = isl_set_params (isl_set_copy (scop->context));
@@ -77,7 +640,7 @@ 
 /* Generates a schedule, which specifies an order used to
    visit elements in a domain.  */
 
-static isl_union_map *
+static __isl_give isl_union_map *
 generate_isl_schedule (scop_p scop)
 {
   int i;
@@ -102,9 +665,16 @@ 
   return schedule_isl;
 }
 
-static isl_ast_node *
-scop_to_isl_ast (scop_p scop)
+static __isl_give isl_ast_node *
+scop_to_isl_ast (scop_p scop, ivs_params_p ip)
 {
+  /* Generate loop upper bounds that consist of the current loop iterator,
+  an operator (< or <=) and an expression not involving the iterator.
+  If this option is not set, then the current loop iterator may appear several
+  times in the upper bound. See the isl manual for more details.  */
+  isl_options_set_ast_build_atomic_upper_bound (scop->ctx, true);
+
+  add_parameters_to_ivs_params (scop, ip);
   isl_union_map *schedule_isl = generate_isl_schedule (scop);
   isl_ast_build *context_isl = generate_isl_context (scop);
   isl_ast_node *ast_isl = isl_ast_build_ast_from_schedule (context_isl,
@@ -117,21 +687,62 @@ 
    the given SCOP.  Return true if code generation succeeded.
 
    FIXME: This is not yet a full implementation of the code generator
-          with ISL ASTs. Generation of GIMPLE code is have to be added.  */
+          with ISL ASTs. Generation of GIMPLE code has to be completed.  */
 
 bool
 graphite_regenerate_ast_isl (scop_p scop)
 {
+  loop_p context_loop;
+  sese region = SCOP_REGION (scop);
+  ifsese if_region = NULL;
+  isl_ast_node *root_node;
+  struct ivs_params ip;
+
   timevar_push (TV_GRAPHITE_CODE_GEN);
   graphite_regenerate_error = false;
-  isl_ast_node *root_node = scop_to_isl_ast (scop);
+
+  ip.region = region;
+
+  root_node = scop_to_isl_ast (scop, &ip);
+
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
       fprintf (dump_file, "\nISL AST generated by ISL: \n");
       print_isl_ast_node (dump_file, root_node, scop->ctx);
+      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;
+
+  translate_isl_ast (context_loop, root_node, if_region->true_region->entry,
+		     &ip);
+  graphite_verify ();
+  scev_reset ();
+  recompute_all_dominators ();
+  graphite_verify ();
+
+  if (graphite_regenerate_error)
+    set_ifsese_condition (if_region, integer_zero_node);
+
+  free (if_region->true_region);
+  free (if_region->region);
+  free (if_region);
+
+  ivs_params_clear (&ip);
   isl_ast_node_free (root_node);
   timevar_pop (TV_GRAPHITE_CODE_GEN);
+  /* TODO: Add dump  */
   return !graphite_regenerate_error;
 }
 #endif