1/* Tracking equivalence classes and constraints at a point on an execution path.
2 Copyright (C) 2019-2025 Free Software Foundation, Inc.
3 Contributed by David Malcolm <dmalcolm@redhat.com>.
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it
8under the terms of the GNU General Public License as published by
9the Free Software Foundation; either version 3, or (at your option)
10any later version.
11
12GCC is distributed in the hope that it will be useful, but
13WITHOUT ANY WARRANTY; without even the implied warranty of
14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15General Public License for more details.
16
17You should have received a copy of the GNU General Public License
18along with GCC; see the file COPYING3. If not see
19<http://www.gnu.org/licenses/>. */
20
21#ifndef GCC_ANALYZER_CONSTRAINT_MANAGER_H
22#define GCC_ANALYZER_CONSTRAINT_MANAGER_H
23
24namespace ana {
25
26class constraint_manager;
27
28enum class bound_kind
29{
30 lower,
31 upper
32};
33
34/* One of the end-points of a range. */
35
36struct bound
37{
38 bound () : m_constant (NULL_TREE), m_closed (false) {}
39 bound (tree constant, bool closed)
40 : m_constant (constant), m_closed (closed) {}
41
42 void ensure_closed (enum bound_kind bound_kind);
43
44 const char * get_relation_as_str () const;
45
46 tree m_constant;
47 bool m_closed;
48};
49
50/* A range of values, used for determining if a value has been
51 constrained to just one possible constant value. */
52
53class range
54{
55public:
56 range () : m_lower_bound (), m_upper_bound () {}
57 range (const bound &lower, const bound &upper)
58 : m_lower_bound (lower), m_upper_bound (upper) {}
59
60 void dump_to_pp (pretty_printer *pp) const;
61 void dump () const;
62
63 tree constrained_to_single_element ();
64
65 tristate eval_condition (enum tree_code op,
66 tree rhs_const) const;
67 bool below_lower_bound (tree rhs_const) const;
68 bool above_upper_bound (tree rhs_const) const;
69
70 bool add_bound (bound b, enum bound_kind bound_kind);
71 bool add_bound (enum tree_code op, tree rhs_const);
72
73private:
74 bound m_lower_bound;
75 bound m_upper_bound;
76};
77
78/* A closed range of values with constant integer bounds
79 e.g. [3, 5] for the set {3, 4, 5}. */
80
81struct bounded_range
82{
83 bounded_range (const_tree lower, const_tree upper);
84
85 void dump_to_pp (pretty_printer *pp, bool show_types) const;
86 void dump (bool show_types) const;
87
88 std::unique_ptr<json::object> to_json () const;
89
90 std::unique_ptr<text_art::widget>
91 make_dump_widget (const text_art::dump_widget_info &dwi) const;
92
93 bool contains_p (tree cst) const;
94
95 bool intersects_p (const bounded_range &other,
96 bounded_range *out) const;
97
98 bool operator== (const bounded_range &other) const;
99 bool operator!= (const bounded_range &other) const
100 {
101 return !(*this == other);
102 }
103
104 static int cmp (const bounded_range &a, const bounded_range &b);
105
106 bool singleton_p () const
107 {
108 return tree_int_cst_equal (m_lower, m_upper);
109 }
110
111 tree m_lower;
112 tree m_upper;
113
114private:
115 static void set_json_attr (json::object &obj, const char *name, tree value);
116};
117
118/* A collection of bounded_range instances, suitable
119 for representing the ranges on a case label within a switch
120 statement. */
121
122struct bounded_ranges
123{
124public:
125 typedef bounded_ranges key_t;
126
127 bounded_ranges (const bounded_range &range);
128 bounded_ranges (const vec<bounded_range> &ranges);
129 bounded_ranges (enum tree_code op, tree rhs_const);
130
131 bool operator== (const bounded_ranges &other) const;
132
133 hashval_t get_hash () const { return m_hash; }
134
135 void dump_to_pp (pretty_printer *pp, bool show_types) const;
136 void dump (bool show_types) const;
137
138 std::unique_ptr<json::value> to_json () const;
139
140 void add_to_dump_widget (text_art::tree_widget &parent,
141 const text_art::dump_widget_info &dwi) const;
142
143 tristate eval_condition (enum tree_code op,
144 tree rhs_const,
145 bounded_ranges_manager *mgr) const;
146
147 bool contain_p (tree cst) const;
148 bool empty_p () const { return m_ranges.length () == 0; }
149
150 static int cmp (const bounded_ranges *a, const bounded_ranges *b);
151
152 unsigned get_count () const { return m_ranges.length (); }
153 const bounded_range &get_range (unsigned idx) const { return m_ranges[idx]; }
154
155private:
156 void canonicalize ();
157 void validate () const;
158
159 friend class bounded_ranges_manager;
160
161 auto_vec<bounded_range> m_ranges;
162 hashval_t m_hash;
163};
164
165} // namespace ana
166
167template <> struct default_hash_traits<bounded_ranges::key_t>
168: public member_function_hash_traits<bounded_ranges::key_t>
169{
170 static const bool empty_zero_p = true;
171};
172
173namespace ana {
174
175/* An object to own and consolidate bounded_ranges instances.
176 This also caches the mapping from switch_cfg_superedge
177 bounded_ranges instances, so that get_or_create_ranges_for_switch is
178 memoized. */
179
180class bounded_ranges_manager
181{
182public:
183 ~bounded_ranges_manager ();
184
185 const bounded_ranges *
186 get_or_create_ranges_for_switch (const switch_cfg_superedge *edge,
187 const gswitch *switch_stmt);
188
189 const bounded_ranges *get_or_create_empty ();
190 const bounded_ranges *get_or_create_point (const_tree value);
191 const bounded_ranges *get_or_create_range (const_tree lower_bound,
192 const_tree upper_bound);
193 const bounded_ranges *
194 get_or_create_union (const vec <const bounded_ranges *> &others);
195 const bounded_ranges *
196 get_or_create_intersection (const bounded_ranges *a,
197 const bounded_ranges *b);
198 const bounded_ranges *
199 get_or_create_inverse (const bounded_ranges *other, tree type);
200
201 void log_stats (logger *logger, bool show_objs) const;
202
203private:
204 const bounded_ranges *
205 create_ranges_for_switch (const switch_cfg_superedge &edge,
206 const gswitch *switch_stmt);
207
208 const bounded_ranges *
209 make_case_label_ranges (const gswitch *switch_stmt,
210 tree case_label);
211
212 const bounded_ranges *consolidate (bounded_ranges *);
213
214 struct hash_traits_t : public typed_noop_remove<bounded_ranges *>
215 {
216 typedef bounded_ranges *key_type;
217 typedef bounded_ranges *value_type;
218
219 static inline bool
220 equal (const key_type &k1, const key_type &k2)
221 {
222 return *k1 == *k2;
223 }
224 static inline hashval_t
225 hash (const key_type &k)
226 {
227 return k->get_hash ();
228 }
229 static inline bool is_empty (key_type k) { return k == NULL; }
230 static inline void mark_empty (key_type &k) { k = NULL; }
231 static inline bool is_deleted (key_type k)
232 {
233 return k == reinterpret_cast<key_type> (1);
234 }
235
236 static const bool empty_zero_p = true;
237 };
238 struct traits_t : public simple_hashmap_traits<hash_traits_t,
239 bounded_ranges *>
240 {
241 };
242 typedef hash_map<bounded_ranges *, bounded_ranges *, traits_t> map_t;
243 map_t m_map;
244
245 typedef hash_map<const switch_cfg_superedge *,
246 const bounded_ranges *> edge_cache_t;
247 edge_cache_t m_edge_cache;
248};
249
250/* An equivalence class within a constraint manager: a set of
251 svalues that are known to all be equal to each other,
252 together with an optional tree constant that they are equal to. */
253
254class equiv_class
255{
256public:
257 equiv_class ();
258 equiv_class (const equiv_class &other);
259
260 hashval_t hash () const;
261 bool operator== (const equiv_class &other);
262
263 void add (const svalue *sval);
264 bool del (const svalue *sval);
265
266 tree get_any_constant () const { return m_constant; }
267
268 const svalue *get_representative () const;
269
270 void canonicalize ();
271
272 void print (pretty_printer *pp) const;
273
274 std::unique_ptr<json::object> to_json () const;
275
276 std::unique_ptr<text_art::tree_widget>
277 make_dump_widget (const text_art::dump_widget_info &dwi,
278 unsigned id) const;
279
280 bool contains_non_constant_p () const;
281
282 /* An equivalence class can contain multiple constants (e.g. multiple
283 different zeroes, for different types); these are just for the last
284 constant added. */
285 tree m_constant;
286 const svalue *m_cst_sval;
287
288 // TODO: should this be a set rather than a vec?
289 auto_vec<const svalue *> m_vars;
290};
291
292/* The various kinds of constraint. */
293
294enum constraint_op
295{
296 CONSTRAINT_NE,
297 CONSTRAINT_LT,
298 CONSTRAINT_LE
299};
300
301const char *constraint_op_code (enum constraint_op c_op);
302
303/* An ID for an equiv_class within a constraint_manager. Internally, this
304 is an index into a vector of equiv_class * within the constraint_manager. */
305
306class equiv_class_id
307{
308public:
309 static equiv_class_id null () { return equiv_class_id (-1); }
310
311 equiv_class_id (unsigned idx) : m_idx (idx) {}
312 const equiv_class &get_obj (const constraint_manager &cm) const;
313 equiv_class &get_obj (constraint_manager &cm) const;
314
315 bool operator== (const equiv_class_id &other) const
316 {
317 return m_idx == other.m_idx;
318 }
319 bool operator!= (const equiv_class_id &other) const
320 {
321 return m_idx != other.m_idx;
322 }
323
324 bool null_p () const { return m_idx == -1; }
325
326 static equiv_class_id from_int (int idx) { return equiv_class_id (idx); }
327 int as_int () const { return m_idx; }
328
329 void print (pretty_printer *pp) const;
330
331 void update_for_removal (equiv_class_id other)
332 {
333 if (m_idx > other.m_idx)
334 m_idx--;
335 }
336
337 int m_idx;
338};
339
340/* A relationship between two equivalence classes in a constraint_manager. */
341
342class constraint
343{
344 public:
345 constraint (equiv_class_id lhs, enum constraint_op c_op, equiv_class_id rhs)
346 : m_lhs (lhs), m_op (c_op), m_rhs (rhs)
347 {
348 gcc_assert (!lhs.null_p ());
349 gcc_assert (!rhs.null_p ());
350 }
351
352 void print (pretty_printer *pp, const constraint_manager &cm) const;
353
354 std::unique_ptr<json::object> to_json () const;
355
356 std::unique_ptr<text_art::widget>
357 make_dump_widget (const text_art::dump_widget_info &dwi,
358 const constraint_manager &cm) const;
359
360 hashval_t hash () const;
361 bool operator== (const constraint &other) const;
362
363 /* Is this an ordering, rather than a "!=". */
364 bool is_ordering_p () const
365 {
366 return m_op != CONSTRAINT_NE;
367 }
368
369 bool implied_by (const constraint &other,
370 const constraint_manager &cm) const;
371
372 equiv_class_id m_lhs;
373 enum constraint_op m_op;
374 equiv_class_id m_rhs;
375};
376
377/* An abstract base class for use with constraint_manager::for_each_fact. */
378
379class fact_visitor
380{
381 public:
382 virtual ~fact_visitor () {}
383 virtual void on_fact (const svalue *lhs,
384 enum tree_code,
385 const svalue *rhs) = 0;
386 virtual void on_ranges (const svalue *lhs,
387 const bounded_ranges *ranges) = 0;
388};
389
390class bounded_ranges_constraint
391{
392public:
393 bounded_ranges_constraint (equiv_class_id ec_id,
394 const bounded_ranges *ranges)
395 : m_ec_id (ec_id), m_ranges (ranges)
396 {
397 }
398
399 void print (pretty_printer *pp, const constraint_manager &cm) const;
400
401 std::unique_ptr<json::object> to_json () const;
402
403 bool operator== (const bounded_ranges_constraint &other) const;
404 bool operator!= (const bounded_ranges_constraint &other) const
405 {
406 return !(*this == other);
407 }
408
409 void add_to_hash (inchash::hash *hstate) const;
410
411 std::unique_ptr<text_art::tree_widget>
412 make_dump_widget (const text_art::dump_widget_info &dwi) const;
413
414 equiv_class_id m_ec_id;
415 const bounded_ranges *m_ranges;
416};
417
418/* A collection of equivalence classes and constraints on them.
419
420 Given N svalues, this can be thought of as representing a subset of
421 N-dimensional space. When we call add_constraint,
422 we are effectively taking an intersection with that constraint. */
423
424class constraint_manager
425{
426public:
427 constraint_manager (region_model_manager *mgr) : m_mgr (mgr) {}
428 constraint_manager (const constraint_manager &other);
429 virtual ~constraint_manager () {}
430
431 constraint_manager& operator= (const constraint_manager &other);
432
433 hashval_t hash () const;
434 bool operator== (const constraint_manager &other) const;
435 bool operator!= (const constraint_manager &other) const
436 {
437 return !(*this == other);
438 }
439
440 void print (pretty_printer *pp) const;
441 void dump_to_pp (pretty_printer *pp, bool multiline) const;
442 void dump (FILE *fp) const;
443 void dump () const;
444
445 std::unique_ptr<json::object> to_json () const;
446
447 std::unique_ptr<text_art::tree_widget>
448 make_dump_widget (const text_art::dump_widget_info &dwi) const;
449
450 const equiv_class &get_equiv_class_by_index (unsigned idx) const
451 {
452 return *m_equiv_classes[idx];
453 }
454 equiv_class &get_equiv_class_by_index (unsigned idx)
455 {
456 return *m_equiv_classes[idx];
457 }
458
459 equiv_class &get_equiv_class (const svalue *sval)
460 {
461 equiv_class_id ec_id = get_or_add_equiv_class (sval);
462 return ec_id.get_obj (cm&: *this);
463 }
464
465 bool add_constraint (const svalue *lhs,
466 enum tree_code op,
467 const svalue *rhs);
468
469 bool add_constraint (equiv_class_id lhs_ec_id,
470 enum tree_code op,
471 equiv_class_id rhs_ec_id);
472
473 void add_unknown_constraint (equiv_class_id lhs_ec_id,
474 enum tree_code op,
475 equiv_class_id rhs_ec_id);
476
477 bool add_bounded_ranges (const svalue *sval,
478 const bounded_ranges *ranges);
479
480 bool get_equiv_class_by_svalue (const svalue *sval,
481 equiv_class_id *out) const;
482 bool sval_constrained_p (const svalue *sval) const;
483 equiv_class_id get_or_add_equiv_class (const svalue *sval);
484 tristate eval_condition (equiv_class_id lhs,
485 enum tree_code op,
486 equiv_class_id rhs) const;
487 tristate eval_condition (equiv_class_id lhs_ec,
488 enum tree_code op,
489 tree rhs_const) const;
490 tristate eval_condition (const svalue *lhs,
491 enum tree_code op,
492 const svalue *rhs) const;
493 range get_ec_bounds (equiv_class_id ec_id) const;
494
495 /* PurgeCriteria should have:
496 bool should_purge_p (const svalue *sval) const. */
497 template <typename PurgeCriteria>
498 void purge (const PurgeCriteria &p, purge_stats *stats);
499
500 void on_liveness_change (const svalue_set &live_svalues,
501 const region_model *model);
502 void purge_state_involving (const svalue *sval);
503
504 void canonicalize ();
505
506 static void merge (const constraint_manager &cm_a,
507 const constraint_manager &cm_b,
508 constraint_manager *out);
509
510 void for_each_fact (fact_visitor *) const;
511
512 void validate () const;
513
514 bounded_ranges_manager *get_range_manager () const;
515
516 bool replay_call_summary (call_summary_replay &r,
517 const constraint_manager &summary);
518
519 auto_delete_vec<equiv_class> m_equiv_classes;
520 auto_vec<constraint> m_constraints;
521 auto_vec<bounded_ranges_constraint> m_bounded_ranges_constraints;
522
523 private:
524 void add_constraint_internal (equiv_class_id lhs_id,
525 enum constraint_op c_op,
526 equiv_class_id rhs_id);
527 bool impossible_derived_conditions_p (const svalue *lhs,
528 const svalue *rhs) const;
529
530 region_model_manager *m_mgr;
531};
532
533} // namespace ana
534
535#endif /* GCC_ANALYZER_CONSTRAINT_MANAGER_H */
536

source code of gcc/analyzer/constraint-manager.h