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/* Chains of recurrences.

   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010

   Free Software Foundation, Inc.

   Contributed by Sebastian Pop <pop@cri.ensmp.fr>

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/>.  */

#ifndef GCC_TREE_CHREC_H

#define GCC_TREE_CHREC_H

/* The following trees are unique elements.  Thus the comparison of another

   element to these elements should be done on the pointer to these trees,

   and not on their value.  */

extern tree chrec_not_analyzed_yet;

extern GTY(()) tree chrec_dont_know;

extern GTY(()) tree chrec_known;

/* After having added an automatically generated element, please

   include it in the following function.  */

static inline bool

automatically_generated_chrec_p (const_tree chrec)

{

  return (chrec == chrec_dont_know

          || chrec == chrec_known);

}

/* The tree nodes aka. CHRECs.  */

static inline bool

tree_is_chrec (const_tree expr)

{

  if (TREE_CODE (expr) == POLYNOMIAL_CHREC

      || automatically_generated_chrec_p (expr))

    return true;

  else

    return false;

}

/* Chrec folding functions.  */

extern tree chrec_fold_plus (tree, tree, tree);

extern tree chrec_fold_minus (tree, tree, tree);

extern tree chrec_fold_multiply (tree, tree, tree);

extern tree chrec_convert (tree, tree, gimple);

extern tree chrec_convert_rhs (tree, tree, gimple);

extern tree chrec_convert_aggressive (tree, tree);

/* Operations.  */

extern tree chrec_apply (unsigned, tree, tree);

extern tree chrec_apply_map (tree, VEC (tree, heap) *);

extern tree chrec_replace_initial_condition (tree, tree);

extern tree initial_condition (tree);

extern tree initial_condition_in_loop_num (tree, unsigned);

extern tree evolution_part_in_loop_num (tree, unsigned);

extern tree hide_evolution_in_other_loops_than_loop (tree, unsigned);

extern tree reset_evolution_in_loop (unsigned, tree, tree);

extern tree chrec_merge (tree, tree);

extern void for_each_scev_op (tree *, bool (*) (tree *, void *), void *);

/* Observers.  */

extern bool eq_evolutions_p (const_tree, const_tree);

extern bool is_multivariate_chrec (const_tree);

extern bool chrec_is_positive (tree, bool *);

extern bool chrec_contains_symbols (const_tree);

extern bool chrec_contains_symbols_defined_in_loop (const_tree, unsigned);

extern bool chrec_contains_undetermined (const_tree);

extern bool tree_contains_chrecs (const_tree, int *);

extern bool evolution_function_is_affine_multivariate_p (const_tree, int);

extern bool evolution_function_is_univariate_p (const_tree);

extern unsigned nb_vars_in_chrec (tree);

extern bool evolution_function_is_invariant_p (tree, int);

extern bool scev_is_linear_expression (tree);

extern bool evolution_function_right_is_integer_cst (const_tree);

/* Determines whether CHREC is equal to zero.  */

static inline bool

chrec_zerop (const_tree chrec)

{

  if (chrec == NULL_TREE)

    return false;

  if (TREE_CODE (chrec) == INTEGER_CST)

    return integer_zerop (chrec);

  return false;

}

/* Determines whether CHREC is a loop invariant with respect to LOOP_NUM.

   Set the result in RES and return true when the property can be computed.  */

static inline bool

no_evolution_in_loop_p (tree chrec, unsigned loop_num, bool *res)

{

  tree scev;

  if (chrec == chrec_not_analyzed_yet

      || chrec == chrec_dont_know

      || chrec_contains_symbols_defined_in_loop (chrec, loop_num))

    return false;

  STRIP_NOPS (chrec);

  scev = hide_evolution_in_other_loops_than_loop (chrec, loop_num);

  *res = !tree_is_chrec (scev);

  return true;

}

/* Build a polynomial chain of recurrence.  */

static inline tree

build_polynomial_chrec (unsigned loop_num,

                        tree left,

                        tree right)

{

  bool val;

  if (left == chrec_dont_know

      || right == chrec_dont_know)

    return chrec_dont_know;

  if (!no_evolution_in_loop_p (left, loop_num, &val)

      || !val)

    return chrec_dont_know;

  /* Pointer types should occur only on the left hand side, i.e. in

     the base of the chrec, and not in the step.  */

  gcc_assert (!POINTER_TYPE_P (TREE_TYPE (right)));

  /* Types of left and right sides of a chrec should be compatible.  */

  if (POINTER_TYPE_P (TREE_TYPE (left)))

    gcc_assert (ptrofftype_p (TREE_TYPE (right)));

  else

    gcc_assert (TREE_TYPE (left) == TREE_TYPE (right));

  if (chrec_zerop (right))

    return left;

  return build3 (POLYNOMIAL_CHREC, TREE_TYPE (left),

                 build_int_cst (NULL_TREE, loop_num), left, right);

}

/* Determines whether the expression CHREC is a constant.  */

static inline bool

evolution_function_is_constant_p (const_tree chrec)

{

  if (chrec == NULL_TREE)

    return false;

  switch (TREE_CODE (chrec))

    {

    case INTEGER_CST:

    case REAL_CST:

      return true;

    default:

      return false;

    }

}

/* Determine whether CHREC is an affine evolution function in LOOPNUM.  */

static inline bool

evolution_function_is_affine_in_loop (const_tree chrec, int loopnum)

{

  if (chrec == NULL_TREE)

    return false;

  switch (TREE_CODE (chrec))

    {

    case POLYNOMIAL_CHREC:

      if (evolution_function_is_invariant_p (CHREC_LEFT (chrec), loopnum)

          && evolution_function_is_invariant_p (CHREC_RIGHT (chrec), loopnum))

        return true;

      else

        return false;

    default:

      return false;

    }

}

/* Determine whether CHREC is an affine evolution function or not.  */

static inline bool

evolution_function_is_affine_p (const_tree chrec)

{

  return chrec

    && TREE_CODE (chrec) == POLYNOMIAL_CHREC

    && evolution_function_is_invariant_p (CHREC_RIGHT (chrec),

                                          CHREC_VARIABLE (chrec))

    && (TREE_CODE (CHREC_RIGHT (chrec)) != POLYNOMIAL_CHREC

        || evolution_function_is_affine_p (CHREC_RIGHT (chrec)));

}

/* Determines whether EXPR does not contains chrec expressions.  */

static inline bool

tree_does_not_contain_chrecs (const_tree expr)

{

  return !tree_contains_chrecs (expr, NULL);

}

/* Returns the type of the chrec.  */

static inline tree

chrec_type (const_tree chrec)

{

  if (automatically_generated_chrec_p (chrec))

    return NULL_TREE;

  return TREE_TYPE (chrec);

}

static inline tree

chrec_fold_op (enum tree_code code, tree type, tree op0, tree op1)

{

  switch (code)

    {

    case PLUS_EXPR:

      return chrec_fold_plus (type, op0, op1);

    case MINUS_EXPR:

      return chrec_fold_minus (type, op0, op1);

    case MULT_EXPR:

      return chrec_fold_multiply (type, op0, op1);

    default:

      gcc_unreachable ();

    }

}

#endif  /* GCC_TREE_CHREC_H  */