1/* Chains of recurrences.
2   Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
3   Contributed by Sebastian Pop <s.pop@laposte.net>
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);
72extern tree chrec_type (tree);
73
74/* Operations.  */
75extern tree chrec_apply (unsigned, tree, tree);
76extern tree chrec_replace_initial_condition (tree, tree);
77extern tree initial_condition (tree);
78extern tree initial_condition_in_loop_num (tree, unsigned);
79extern tree evolution_part_in_loop_num (tree, unsigned);
80extern tree hide_evolution_in_other_loops_than_loop (tree, unsigned);
81extern tree reset_evolution_in_loop (unsigned, tree, tree);
82extern tree chrec_merge (tree, tree);
83
84/* Observers.  */
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  return build (POLYNOMIAL_CHREC, TREE_TYPE (left),
109		build_int_cst (NULL_TREE, loop_num), left, right);
110}
111
112
113
114/* Observers.  */
115
116/* Determines whether CHREC is equal to zero.  */
117
118static inline bool
119chrec_zerop (tree chrec)
120{
121  if (chrec == NULL_TREE)
122    return false;
123
124  if (TREE_CODE (chrec) == INTEGER_CST)
125    return integer_zerop (chrec);
126
127  return false;
128}
129
130/* Determines whether the expression CHREC is a constant.  */
131
132static inline bool
133evolution_function_is_constant_p (tree chrec)
134{
135  if (chrec == NULL_TREE)
136    return false;
137
138  switch (TREE_CODE (chrec))
139    {
140    case INTEGER_CST:
141    case REAL_CST:
142      return true;
143
144    default:
145      return false;
146    }
147}
148
149extern bool evolution_function_is_invariant_p (tree, int);
150/* Determine whether the given tree is an affine evolution function or not.  */
151
152static inline bool
153evolution_function_is_affine_p (tree chrec)
154{
155  if (chrec == NULL_TREE)
156    return false;
157
158  switch (TREE_CODE (chrec))
159    {
160    case POLYNOMIAL_CHREC:
161      if (evolution_function_is_invariant_p (CHREC_LEFT (chrec),
162					     CHREC_VARIABLE (chrec))
163	  && evolution_function_is_invariant_p (CHREC_RIGHT (chrec),
164						CHREC_VARIABLE (chrec)))
165	return true;
166      else
167	return false;
168
169    default:
170      return false;
171    }
172}
173
174/* Determine whether the given tree is an affine or constant evolution
175   function.  */
176
177static inline bool
178evolution_function_is_affine_or_constant_p (tree chrec)
179{
180  return evolution_function_is_affine_p (chrec)
181    || evolution_function_is_constant_p (chrec);
182}
183
184/* Determines whether EXPR does not contains chrec expressions.  */
185
186static inline bool
187tree_does_not_contain_chrecs (tree expr)
188{
189  return !tree_contains_chrecs (expr, NULL);
190}
191
192/* Determines whether CHREC is a loop invariant with respect to LOOP_NUM.
193   Set the result in RES and return true when the property can be computed.  */
194
195static inline bool
196no_evolution_in_loop_p (tree chrec, unsigned loop_num, bool *res)
197{
198  tree scev;
199
200  if (chrec == chrec_not_analyzed_yet
201      || chrec == chrec_dont_know
202      || chrec_contains_symbols_defined_in_loop (chrec, loop_num))
203    return false;
204
205  scev = hide_evolution_in_other_loops_than_loop (chrec, loop_num);
206  *res = !tree_is_chrec (scev);
207  return true;
208}
209
210#endif  /* GCC_TREE_CHREC_H  */
211