1/* Chains of recurrences.
2   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009
3   Free Software Foundation, Inc.
4   Contributed by Sebastian Pop <pop@cri.ensmp.fr>
5
6This file is part of GCC.
7
8GCC is free software; you can redistribute it and/or modify it under
9the terms of the GNU General Public License as published by the Free
10Software Foundation; either version 3, or (at your option) any later
11version.
12
13GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14WARRANTY; without even the implied warranty of MERCHANTABILITY or
15FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
16for more details.
17
18You should have received a copy of the GNU General Public License
19along with GCC; see the file COPYING3.  If not see
20<http://www.gnu.org/licenses/>.  */
21
22#ifndef GCC_TREE_CHREC_H
23#define GCC_TREE_CHREC_H
24
25/* The following trees are unique elements.  Thus the comparison of another
26   element to these elements should be done on the pointer to these trees,
27   and not on their value.  */
28
29extern tree chrec_not_analyzed_yet;
30extern GTY(()) tree chrec_dont_know;
31extern GTY(()) tree chrec_known;
32
33/* After having added an automatically generated element, please
34   include it in the following function.  */
35
36static inline bool
37automatically_generated_chrec_p (const_tree chrec)
38{
39  return (chrec == chrec_dont_know
40	  || chrec == chrec_known);
41}
42
43/* The tree nodes aka. CHRECs.  */
44
45static inline bool
46tree_is_chrec (const_tree expr)
47{
48  if (TREE_CODE (expr) == POLYNOMIAL_CHREC
49      || automatically_generated_chrec_p (expr))
50    return true;
51  else
52    return false;
53}
54
55
56
57/* Chrec folding functions.  */
58extern tree chrec_fold_plus (tree, tree, tree);
59extern tree chrec_fold_minus (tree, tree, tree);
60extern tree chrec_fold_multiply (tree, tree, tree);
61extern tree chrec_convert (tree, tree, gimple);
62extern tree chrec_convert_rhs (tree, tree, gimple);
63extern tree chrec_convert_aggressive (tree, tree);
64
65/* Operations.  */
66extern tree chrec_apply (unsigned, tree, tree);
67extern tree chrec_replace_initial_condition (tree, tree);
68extern tree initial_condition (tree);
69extern tree initial_condition_in_loop_num (tree, unsigned);
70extern tree evolution_part_in_loop_num (tree, unsigned);
71extern tree hide_evolution_in_other_loops_than_loop (tree, unsigned);
72extern tree reset_evolution_in_loop (unsigned, tree, tree);
73extern tree chrec_merge (tree, tree);
74extern void for_each_scev_op (tree *, bool (*) (tree *, void *), void *);
75
76/* Observers.  */
77extern bool eq_evolutions_p (const_tree, const_tree);
78extern bool is_multivariate_chrec (const_tree);
79extern bool chrec_is_positive (tree, bool *);
80extern bool chrec_contains_symbols (const_tree);
81extern bool chrec_contains_symbols_defined_in_loop (const_tree, unsigned);
82extern bool chrec_contains_undetermined (const_tree);
83extern bool tree_contains_chrecs (const_tree, int *);
84extern bool evolution_function_is_affine_multivariate_p (const_tree, int);
85extern bool evolution_function_is_univariate_p (const_tree);
86extern unsigned nb_vars_in_chrec (tree);
87extern bool evolution_function_is_invariant_p (tree, int);
88extern bool scev_is_linear_expression (tree);
89extern bool evolution_function_right_is_integer_cst (const_tree);
90
91/* Determines whether CHREC is equal to zero.  */
92
93static inline bool
94chrec_zerop (const_tree chrec)
95{
96  if (chrec == NULL_TREE)
97    return false;
98
99  if (TREE_CODE (chrec) == INTEGER_CST)
100    return integer_zerop (chrec);
101
102  return false;
103}
104
105/* Determines whether CHREC is a loop invariant with respect to LOOP_NUM.
106   Set the result in RES and return true when the property can be computed.  */
107
108static inline bool
109no_evolution_in_loop_p (tree chrec, unsigned loop_num, bool *res)
110{
111  tree scev;
112
113  if (chrec == chrec_not_analyzed_yet
114      || chrec == chrec_dont_know
115      || chrec_contains_symbols_defined_in_loop (chrec, loop_num))
116    return false;
117
118  STRIP_NOPS (chrec);
119  scev = hide_evolution_in_other_loops_than_loop (chrec, loop_num);
120  *res = !tree_is_chrec (scev);
121  return true;
122}
123
124/* Build a polynomial chain of recurrence.  */
125
126static inline tree
127build_polynomial_chrec (unsigned loop_num,
128			tree left,
129			tree right)
130{
131  bool val;
132
133  if (left == chrec_dont_know
134      || right == chrec_dont_know)
135    return chrec_dont_know;
136
137  if (!no_evolution_in_loop_p (left, loop_num, &val)
138      || !val)
139    return chrec_dont_know;
140
141  /* Pointer types should occur only on the left hand side, i.e. in
142     the base of the chrec, and not in the step.  */
143  gcc_assert (!POINTER_TYPE_P (TREE_TYPE (right)));
144
145  /* Types of left and right sides of a chrec should be compatible.  */
146  if (POINTER_TYPE_P (TREE_TYPE (left)))
147    gcc_assert (sizetype == TREE_TYPE (right));
148  else
149    gcc_assert (TREE_TYPE (left) == TREE_TYPE (right));
150
151  if (chrec_zerop (right))
152    return left;
153
154  return build3 (POLYNOMIAL_CHREC, TREE_TYPE (left),
155		 build_int_cst (NULL_TREE, loop_num), left, right);
156}
157
158/* Determines whether the expression CHREC is a constant.  */
159
160static inline bool
161evolution_function_is_constant_p (const_tree chrec)
162{
163  if (chrec == NULL_TREE)
164    return false;
165
166  switch (TREE_CODE (chrec))
167    {
168    case INTEGER_CST:
169    case REAL_CST:
170      return true;
171
172    default:
173      return false;
174    }
175}
176
177/* Determine whether CHREC is an affine evolution function in LOOPNUM.  */
178
179static inline bool
180evolution_function_is_affine_in_loop (const_tree chrec, int loopnum)
181{
182  if (chrec == NULL_TREE)
183    return false;
184
185  switch (TREE_CODE (chrec))
186    {
187    case POLYNOMIAL_CHREC:
188      if (evolution_function_is_invariant_p (CHREC_LEFT (chrec), loopnum)
189	  && evolution_function_is_invariant_p (CHREC_RIGHT (chrec), loopnum))
190	return true;
191      else
192	return false;
193
194    default:
195      return false;
196    }
197}
198
199/* Determine whether CHREC is an affine evolution function or not.  */
200
201static inline bool
202evolution_function_is_affine_p (const_tree chrec)
203{
204  if (chrec == NULL_TREE)
205    return false;
206
207  switch (TREE_CODE (chrec))
208    {
209    case POLYNOMIAL_CHREC:
210      if (evolution_function_is_invariant_p (CHREC_LEFT (chrec),
211					     CHREC_VARIABLE (chrec))
212	  && evolution_function_is_invariant_p (CHREC_RIGHT (chrec),
213						CHREC_VARIABLE (chrec)))
214	return true;
215      else
216	return false;
217
218    default:
219      return false;
220    }
221}
222
223/* Determines whether EXPR does not contains chrec expressions.  */
224
225static inline bool
226tree_does_not_contain_chrecs (const_tree expr)
227{
228  return !tree_contains_chrecs (expr, NULL);
229}
230
231/* Returns the type of the chrec.  */
232
233static inline tree
234chrec_type (const_tree chrec)
235{
236  if (automatically_generated_chrec_p (chrec))
237    return NULL_TREE;
238
239  return TREE_TYPE (chrec);
240}
241
242static inline tree
243chrec_fold_op (enum tree_code code, tree type, tree op0, tree op1)
244{
245  switch (code)
246    {
247    case PLUS_EXPR:
248      return chrec_fold_plus (type, op0, op1);
249
250    case MINUS_EXPR:
251      return chrec_fold_minus (type, op0, op1);
252
253    case MULT_EXPR:
254      return chrec_fold_multiply (type, op0, op1);
255
256    default:
257      gcc_unreachable ();
258    }
259
260}
261
262#endif  /* GCC_TREE_CHREC_H  */
263