1/* Chains of recurrences.
2   Copyright (C) 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
3   Contributed by Sebastian Pop <pop@cri.ensmp.fr>
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it under
8the terms of the GNU General Public License as published by the Free
9Software Foundation; either version 2, or (at your option) any later
10version.
11
12GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or
14FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15for more details.
16
17You should have received a copy of the GNU General Public License
18along with GCC; see the file COPYING.  If not, write to the Free
19Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
2002110-1301, USA.  */
21
22#ifndef GCC_TREE_CHREC_H
23#define GCC_TREE_CHREC_H
24
25/* Accessors for the chains of recurrences.  */
26#define CHREC_VAR(NODE)           TREE_OPERAND (NODE, 0)
27#define CHREC_LEFT(NODE)          TREE_OPERAND (NODE, 1)
28#define CHREC_RIGHT(NODE)         TREE_OPERAND (NODE, 2)
29#define CHREC_VARIABLE(NODE)      TREE_INT_CST_LOW (CHREC_VAR (NODE))
30
31
32
33/* The following trees are unique elements.  Thus the comparison of another
34   element to these elements should be done on the pointer to these trees,
35   and not on their value.  */
36
37extern tree chrec_not_analyzed_yet;
38extern GTY(()) tree chrec_dont_know;
39extern GTY(()) tree chrec_known;
40
41/* After having added an automatically generated element, please
42   include it in the following function.  */
43
44static inline bool
45automatically_generated_chrec_p (tree chrec)
46{
47  return (chrec == chrec_not_analyzed_yet
48	  || chrec == chrec_dont_know
49	  || chrec == chrec_known);
50}
51
52/* The tree nodes aka. CHRECs.  */
53
54static inline bool
55tree_is_chrec (tree expr)
56{
57  if (TREE_CODE (expr) == POLYNOMIAL_CHREC
58      || automatically_generated_chrec_p (expr))
59    return true;
60  else
61    return false;
62}
63
64
65
66/* Chrec folding functions.  */
67extern tree chrec_fold_plus (tree, tree, tree);
68extern tree chrec_fold_minus (tree, tree, tree);
69extern tree chrec_fold_multiply (tree, tree, tree);
70extern tree chrec_convert (tree, tree, tree);
71extern tree chrec_convert_aggressive (tree, tree);
72
73/* Operations.  */
74extern tree chrec_apply (unsigned, tree, tree);
75extern tree chrec_replace_initial_condition (tree, tree);
76extern tree initial_condition (tree);
77extern tree initial_condition_in_loop_num (tree, unsigned);
78extern tree evolution_part_in_loop_num (tree, unsigned);
79extern tree hide_evolution_in_other_loops_than_loop (tree, unsigned);
80extern tree reset_evolution_in_loop (unsigned, tree, tree);
81extern tree chrec_merge (tree, tree);
82
83/* Observers.  */
84extern bool eq_evolutions_p (tree, tree);
85extern bool is_multivariate_chrec (tree);
86extern bool chrec_is_positive (tree, bool *);
87extern bool chrec_contains_symbols (tree);
88extern bool chrec_contains_symbols_defined_in_loop (tree, unsigned);
89extern bool chrec_contains_undetermined (tree);
90extern bool tree_contains_chrecs (tree, int *);
91extern bool evolution_function_is_affine_multivariate_p (tree);
92extern bool evolution_function_is_univariate_p (tree);
93extern unsigned nb_vars_in_chrec (tree);
94
95
96
97/* Build a polynomial chain of recurrence.  */
98
99static inline tree
100build_polynomial_chrec (unsigned loop_num,
101			tree left,
102			tree right)
103{
104  if (left == chrec_dont_know
105      || right == chrec_dont_know)
106    return chrec_dont_know;
107
108  gcc_assert (TREE_TYPE (left) == TREE_TYPE (right));
109
110  return build3 (POLYNOMIAL_CHREC, TREE_TYPE (left),
111		 build_int_cst (NULL_TREE, loop_num), left, right);
112}
113
114
115
116/* Observers.  */
117
118/* Determines whether CHREC is equal to zero.  */
119
120static inline bool
121chrec_zerop (tree chrec)
122{
123  if (chrec == NULL_TREE)
124    return false;
125
126  if (TREE_CODE (chrec) == INTEGER_CST)
127    return integer_zerop (chrec);
128
129  return false;
130}
131
132/* Determines whether the expression CHREC is a constant.  */
133
134static inline bool
135evolution_function_is_constant_p (tree chrec)
136{
137  if (chrec == NULL_TREE)
138    return false;
139
140  switch (TREE_CODE (chrec))
141    {
142    case INTEGER_CST:
143    case REAL_CST:
144      return true;
145
146    default:
147      return false;
148    }
149}
150
151extern bool evolution_function_is_invariant_p (tree, int);
152/* Determine whether the given tree is an affine evolution function or not.  */
153
154static inline bool
155evolution_function_is_affine_p (tree chrec)
156{
157  if (chrec == NULL_TREE)
158    return false;
159
160  switch (TREE_CODE (chrec))
161    {
162    case POLYNOMIAL_CHREC:
163      if (evolution_function_is_invariant_p (CHREC_LEFT (chrec),
164					     CHREC_VARIABLE (chrec))
165	  && evolution_function_is_invariant_p (CHREC_RIGHT (chrec),
166						CHREC_VARIABLE (chrec)))
167	return true;
168      else
169	return false;
170
171    default:
172      return false;
173    }
174}
175
176/* Determine whether the given tree is an affine or constant evolution
177   function.  */
178
179static inline bool
180evolution_function_is_affine_or_constant_p (tree chrec)
181{
182  return evolution_function_is_affine_p (chrec)
183    || evolution_function_is_constant_p (chrec);
184}
185
186/* Determines whether EXPR does not contains chrec expressions.  */
187
188static inline bool
189tree_does_not_contain_chrecs (tree expr)
190{
191  return !tree_contains_chrecs (expr, NULL);
192}
193
194/* Determines whether CHREC is a loop invariant with respect to LOOP_NUM.
195   Set the result in RES and return true when the property can be computed.  */
196
197static inline bool
198no_evolution_in_loop_p (tree chrec, unsigned loop_num, bool *res)
199{
200  tree scev;
201
202  if (chrec == chrec_not_analyzed_yet
203      || chrec == chrec_dont_know
204      || chrec_contains_symbols_defined_in_loop (chrec, loop_num))
205    return false;
206
207  scev = hide_evolution_in_other_loops_than_loop (chrec, loop_num);
208  *res = !tree_is_chrec (scev);
209  return true;
210}
211
212/* Returns the type of the chrec.  */
213
214static inline tree
215chrec_type (tree chrec)
216{
217  if (automatically_generated_chrec_p (chrec))
218    return NULL_TREE;
219
220  return TREE_TYPE (chrec);
221}
222
223
224#endif  /* GCC_TREE_CHREC_H  */
225