tree-chrec.h   [plain text]

/* Chains of recurrences.
   Copyright (C) 2003 Free Software Foundation, Inc.
   Contributed by Sebastian Pop <s.pop@laposte.net>

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, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#ifndef GCC_TREE_CHREC_H
#define GCC_TREE_CHREC_H

/* Accessors for the chains of recurrences.  */
#define CHREC_VAR(NODE)           TREE_OPERAND (NODE, 0)
#define CHREC_LEFT(NODE)          TREE_OPERAND (NODE, 1)
#define CHREC_RIGHT(NODE)         TREE_OPERAND (NODE, 2)
#define CHREC_VARIABLE(NODE)      TREE_INT_CST_LOW (CHREC_VAR (NODE))
#define CHREC_LOW(NODE)           TREE_OPERAND (INTERVAL_CHREC_CHECK (NODE), 0)
#define CHREC_UP(NODE)            TREE_OPERAND (INTERVAL_CHREC_CHECK (NODE), 1)



/* 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 tree chrec_top;
extern tree chrec_bot;

/* After having added an automatically generated element, please
   include it in the following function.  */

static inline bool
automatically_generated_chrec_p (tree chrec)
{
  return (chrec == chrec_not_analyzed_yet 
	  || chrec == chrec_top
	  || chrec == chrec_bot);
}

/* The tree nodes aka. CHRECs.  */

static inline bool
tree_is_chrec (tree expr)
{
  if (TREE_CODE (expr) == INTERVAL_CHREC
      || TREE_CODE (expr) == POLYNOMIAL_CHREC
      || TREE_CODE (expr) == EXPONENTIAL_CHREC
      || TREE_CODE (expr) == PEELED_CHREC)
    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);
extern tree count_ev_in_wider_type (tree, tree);
extern tree chrec_type (tree);

/* Operations.  */
extern tree simplify_peeled_chrec (tree);
extern tree chrec_apply (unsigned, tree, tree);
extern tree chrec_replace_initial_condition (tree, tree);
extern tree update_initial_condition_to_origin (tree);
extern tree initial_condition (tree);
extern tree evolution_part_in_loop_num (tree, unsigned);
extern tree hide_evolution_in_other_loops_than_loop (tree, unsigned);
extern tree hide_evolution_in_loop (tree, unsigned);
extern tree reset_evolution_in_loop (unsigned, tree, tree);
extern tree chrec_merge (tree, tree);
extern tree chrec_fold_automatically_generated_operands (tree, tree);

/* Observers.  */
extern bool is_multivariate_chrec (tree);
extern bool is_pure_sum_chrec (tree);
extern bool chrec_is_positive (tree, bool *);
extern bool chrec_contains_symbols (tree);
extern bool chrec_contains_symbols_defined_in_loop (tree, unsigned);
extern bool chrec_contains_undetermined (tree);
extern bool chrec_contains_intervals (tree);
extern bool tree_contains_chrecs (tree);
extern bool evolution_function_is_affine_multivariate_p (tree);
extern bool evolution_function_is_univariate_p (tree);



/* Constructors.  */

/* Build an interval.  */

static inline tree 
build_interval_chrec (tree low, 
		      tree up)
{
  if (automatically_generated_chrec_p (low)
      || automatically_generated_chrec_p (up))
    return chrec_fold_automatically_generated_operands (low, up);
  
  if (integer_zerop (tree_fold_minus (chrec_type (low), up, low)))
    return low;
  else
    return build (INTERVAL_CHREC, TREE_TYPE (low), low, up);
}

/* Build a polynomial chain of recurrence.  */

static inline tree 
build_polynomial_chrec (unsigned loop_num, 
			tree left, 
			tree right)
{
  return build (POLYNOMIAL_CHREC, TREE_TYPE (left), 
		build_int_2 (loop_num, 0), left, right);
}

/* Build an exponential chain of recurrence.  */

static inline tree 
build_exponential_chrec (unsigned loop_num, 
			 tree left, 
			 tree right)
{
  return build (EXPONENTIAL_CHREC, TREE_TYPE (left), 
		build_int_2 (loop_num, 0), left, right);
}

/* Build a peeled chain of recurrence.  */

static inline tree 
build_peeled_chrec (unsigned loop_num, 
		    tree left, 
		    tree right)
{
  return build (PEELED_CHREC, TREE_TYPE (left),
		build_int_2 (loop_num, 0), left, right);
}

/* Build a chrec top interval for type.  */

static inline tree 
build_chrec_top_type (tree type)
{
  /* Disabled for now: it is not used, and libjava fails to build on
     amd64.  */
  return chrec_top;

  if (type != NULL_TREE)
    {
      enum tree_code code = TREE_CODE (type);
 
      if ((code == INTEGER_TYPE
	   || code == ENUMERAL_TYPE
	   || code == BOOLEAN_TYPE
	   || code == CHAR_TYPE
	   || code == REAL_TYPE)
	  && TYPE_MIN_VALUE (type) != NULL_TREE 
	  && TYPE_MAX_VALUE (type) != NULL_TREE)
	return build_interval_chrec (TYPE_MIN_VALUE (type), 
				     TYPE_MAX_VALUE (type));
    }

  return chrec_top;
}



/* Observers.  */

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

static inline bool 
chrec_zerop (tree chrec)
{
  if (chrec == NULL_TREE)
    return false;
  
  if (TREE_CODE (chrec) == INTEGER_CST)
    return integer_zerop (chrec);
  
  if (TREE_CODE (chrec) == INTERVAL_CHREC)
    return (integer_zerop (CHREC_LOW (chrec))
	    && integer_zerop (CHREC_UP (chrec)));
  
  return false;
}

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

static inline bool 
evolution_function_is_constant_p (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 the given tree is an affine evolution function or not.  */

static inline bool 
evolution_function_is_affine_p (tree chrec)
{
  if (chrec == NULL_TREE)
    return false;
  
  switch (TREE_CODE (chrec))
    {
    case POLYNOMIAL_CHREC:
      if (evolution_function_is_constant_p (CHREC_LEFT (chrec))
	  && evolution_function_is_constant_p (CHREC_RIGHT (chrec)))
	return true;
      else
	return false;
      
    case EXPONENTIAL_CHREC:
    case INTERVAL_CHREC:
    default:
      return false;
    }
}

/* Determine whether the given tree is an affine or constant evolution
   function.  */

static inline bool 
evolution_function_is_affine_or_constant_p (tree chrec)
{
  return evolution_function_is_affine_p (chrec) 
    || evolution_function_is_constant_p (chrec);
}

/* Determine whether the given tree is a multivariate evolution.  */

static inline bool
evolution_function_is_multivariate (tree chrec)
{
  return !evolution_function_is_univariate_p (chrec);
}

/* Determine whether the given tree is an affine peeled chrec.  */

static inline bool 
evolution_function_is_peeled_affine_p (tree chrec)
{
  if (chrec == NULL_TREE)
    return false;
  
  if (TREE_CODE (chrec) == PEELED_CHREC)
    return (evolution_function_is_affine_or_constant_p (CHREC_LEFT (chrec)) 
	    && evolution_function_is_affine_p (CHREC_RIGHT (chrec)));

  return false;
}

/* Determines which expressions are simpler to be {handled | kept} in a 
   symbolic form.  */

static inline bool
chrec_should_remain_symbolic (tree evfun)
{
  if (evfun == NULL_TREE
      || evfun == chrec_top)
    return true;
  
  return false;
}

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

static inline bool
tree_does_not_contain_chrecs (tree expr)
{
  return !tree_contains_chrecs (expr);
}

/* 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_top
      || chrec_contains_symbols_defined_in_loop (chrec, loop_num))
    return false;

  scev = hide_evolution_in_other_loops_than_loop (chrec, loop_num);
  *res = (TREE_CODE (scev) != POLYNOMIAL_CHREC
	  && TREE_CODE (scev) != EXPONENTIAL_CHREC);
  return true;
}

#endif  /* GCC_TREE_CHREC_H  */