gcc/analyzer/constraint-manager.h

   1 /* Tracking equivalence classes and constraints at a point on an execution path.
   2    Copyright (C) 2019-2022 Free Software Foundation, Inc.
   3    Contributed by David Malcolm <dmalcolm@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it
   8 under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along 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
  24 namespace ana {
  25
  26 class constraint_manager;
  27
  28 enum bound_kind
  29 {
  30   BK_LOWER,
  31   BK_UPPER
  32 };
  33
  34 /* One of the end-points of a range.  */
  35
  36 struct 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
  53 class range
  54 {
  55 public:
  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
  73 private:
  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
  81 struct 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   json::object *to_json () const;
  89
  90   bool contains_p (tree cst) const;
  91
  92   bool intersects_p (const bounded_range &other,
  93                      bounded_range *out) const;
  94
  95   bool operator== (const bounded_range &other) const;
  96   bool operator!= (const bounded_range &other) const
  97   {
  98     return !(*this == other);
  99   }
 100
 101   static int cmp (const bounded_range &a, const bounded_range &b);
 102
 103   tree m_lower;
 104   tree m_upper;
 105
 106 private:
 107   static void set_json_attr (json::object *obj, const char *name, tree value);
 108 };
 109
 110 /* A collection of bounded_range instances, suitable
 111    for representing the ranges on a case label within a switch
 112    statement.  */
 113
 114 struct bounded_ranges
 115 {
 116 public:
 117   typedef bounded_ranges key_t;
 118
 119   bounded_ranges (const bounded_range &range);
 120   bounded_ranges (const vec<bounded_range> &ranges);
 121   bounded_ranges (enum tree_code op, tree rhs_const);
 122
 123   bool operator== (const bounded_ranges &other) const;
 124
 125   hashval_t get_hash () const { return m_hash; }
 126
 127   void dump_to_pp (pretty_printer *pp, bool show_types) const;
 128   void dump (bool show_types) const;
 129
 130   json::value *to_json () const;
 131
 132   tristate eval_condition (enum tree_code op,
 133                            tree rhs_const,
 134                            bounded_ranges_manager *mgr) const;
 135
 136   bool contain_p (tree cst) const;
 137   bool empty_p () const { return m_ranges.length () == 0; }
 138
 139   static int cmp (const bounded_ranges *a, const bounded_ranges *b);
 140
 141   unsigned get_count () const { return m_ranges.length (); }
 142   const bounded_range &get_range (unsigned idx) const { return m_ranges[idx]; }
 143
 144 private:
 145   void canonicalize ();
 146   void validate () const;
 147
 148   friend class bounded_ranges_manager;
 149
 150   auto_vec<bounded_range> m_ranges;
 151   hashval_t m_hash;
 152 };
 153
 154 } // namespace ana
 155
 156 template <> struct default_hash_traits<bounded_ranges::key_t>
 157 : public member_function_hash_traits<bounded_ranges::key_t>
 158 {
 159   static const bool empty_zero_p = true;
 160 };
 161
 162 namespace ana {
 163
 164 /* An object to own and consolidate bounded_ranges instances.
 165    This also caches the mapping from switch_cfg_superedge
 166    bounded_ranges instances, so that get_or_create_ranges_for_switch is
 167    memoized.  */
 168
 169 class bounded_ranges_manager
 170 {
 171 public:
 172   ~bounded_ranges_manager ();
 173
 174   const bounded_ranges *
 175   get_or_create_ranges_for_switch (const switch_cfg_superedge *edge,
 176                                    const gswitch *switch_stmt);
 177
 178   const bounded_ranges *get_or_create_empty ();
 179   const bounded_ranges *get_or_create_point (const_tree value);
 180   const bounded_ranges *get_or_create_range (const_tree lower_bound,
 181                                              const_tree upper_bound);
 182   const bounded_ranges *
 183   get_or_create_union (const vec <const bounded_ranges *> &others);
 184   const bounded_ranges *
 185   get_or_create_intersection (const bounded_ranges *a,
 186                               const bounded_ranges *b);
 187   const bounded_ranges *
 188   get_or_create_inverse (const bounded_ranges *other, tree type);
 189
 190   void log_stats (logger *logger, bool show_objs) const;
 191
 192 private:
 193   const bounded_ranges *
 194   create_ranges_for_switch (const switch_cfg_superedge &edge,
 195                             const gswitch *switch_stmt);
 196
 197   const bounded_ranges *
 198   make_case_label_ranges (const gswitch *switch_stmt,
 199                           tree case_label);
 200
 201   const bounded_ranges *consolidate (bounded_ranges *);
 202
 203   struct hash_traits_t : public typed_noop_remove<bounded_ranges *>
 204   {
 205     typedef bounded_ranges *key_type;
 206     typedef bounded_ranges *value_type;
 207
 208     static inline bool
 209     equal (const key_type &k1, const key_type &k2)
 210     {
 211       return *k1 == *k2;
 212     }
 213     static inline hashval_t
 214     hash (const key_type &k)
 215     {
 216       return k->get_hash ();
 217     }
 218     static inline bool is_empty (key_type k) { return k == NULL; }
 219     static inline void mark_empty (key_type &k) { k = NULL; }
 220     static inline bool is_deleted (key_type k)
 221     {
 222       return k == reinterpret_cast<key_type> (1);
 223     }
 224
 225     static const bool empty_zero_p = true;
 226   };
 227   struct traits_t : public simple_hashmap_traits<hash_traits_t,
 228                                                  bounded_ranges *>
 229   {
 230   };
 231   typedef hash_map<bounded_ranges *, bounded_ranges *, traits_t> map_t;
 232   map_t m_map;
 233
 234   typedef hash_map<const switch_cfg_superedge *,
 235                    const bounded_ranges *> edge_cache_t;
 236   edge_cache_t m_edge_cache;
 237 };
 238
 239 /* An equivalence class within a constraint manager: a set of
 240    svalues that are known to all be equal to each other,
 241    together with an optional tree constant that they are equal to.  */
 242
 243 class equiv_class
 244 {
 245 public:
 246   equiv_class ();
 247   equiv_class (const equiv_class &other);
 248
 249   hashval_t hash () const;
 250   bool operator== (const equiv_class &other);
 251
 252   void add (const svalue *sval);
 253   bool del (const svalue *sval);
 254
 255   tree get_any_constant () const { return m_constant; }
 256
 257   const svalue *get_representative () const;
 258
 259   void canonicalize ();
 260
 261   void print (pretty_printer *pp) const;
 262
 263   json::object *to_json () const;
 264
 265   bool contains_non_constant_p () const;
 266
 267   /* An equivalence class can contain multiple constants (e.g. multiple
 268      different zeroes, for different types); these are just for the last
 269      constant added.  */
 270   tree m_constant;
 271   const svalue *m_cst_sval;
 272
 273   // TODO: should this be a set rather than a vec?
 274   auto_vec<const svalue *> m_vars;
 275 };
 276
 277 /* The various kinds of constraint.  */
 278
 279 enum constraint_op
 280 {
 281   CONSTRAINT_NE,
 282   CONSTRAINT_LT,
 283   CONSTRAINT_LE
 284 };
 285
 286 const char *constraint_op_code (enum constraint_op c_op);
 287
 288 /* An ID for an equiv_class within a constraint_manager.  Internally, this
 289    is an index into a vector of equiv_class * within the constraint_manager.  */
 290
 291 class equiv_class_id
 292 {
 293 public:
 294   static equiv_class_id null () { return equiv_class_id (-1); }
 295
 296   equiv_class_id (unsigned idx) : m_idx (idx) {}
 297   const equiv_class &get_obj (const constraint_manager &cm) const;
 298   equiv_class &get_obj (constraint_manager &cm) const;
 299
 300   bool operator== (const equiv_class_id &other) const
 301   {
 302     return m_idx == other.m_idx;
 303   }
 304   bool operator!= (const equiv_class_id &other) const
 305   {
 306     return m_idx != other.m_idx;
 307   }
 308
 309   bool null_p () const { return m_idx == -1; }
 310
 311   static equiv_class_id from_int (int idx) { return equiv_class_id (idx); }
 312   int as_int () const { return m_idx; }
 313
 314   void print (pretty_printer *pp) const;
 315
 316   void update_for_removal (equiv_class_id other)
 317   {
 318     if (m_idx > other.m_idx)
 319       m_idx--;
 320   }
 321
 322   int m_idx;
 323 };
 324
 325 /* A relationship between two equivalence classes in a constraint_manager.  */
 326
 327 class constraint
 328 {
 329  public:
 330   constraint (equiv_class_id lhs, enum constraint_op c_op, equiv_class_id rhs)
 331   : m_lhs (lhs), m_op (c_op), m_rhs (rhs)
 332   {
 333     gcc_assert (!lhs.null_p ());
 334     gcc_assert (!rhs.null_p ());
 335   }
 336
 337   void print (pretty_printer *pp, const constraint_manager &cm) const;
 338
 339   json::object *to_json () const;
 340
 341   hashval_t hash () const;
 342   bool operator== (const constraint &other) const;
 343
 344   /* Is this an ordering, rather than a "!=".  */
 345   bool is_ordering_p () const
 346   {
 347     return m_op != CONSTRAINT_NE;
 348   }
 349
 350   bool implied_by (const constraint &other,
 351                    const constraint_manager &cm) const;
 352
 353   equiv_class_id m_lhs;
 354   enum constraint_op m_op;
 355   equiv_class_id m_rhs;
 356 };
 357
 358 /* An abstract base class for use with constraint_manager::for_each_fact.  */
 359
 360 class fact_visitor
 361 {
 362  public:
 363   virtual ~fact_visitor () {}
 364   virtual void on_fact (const svalue *lhs,
 365                         enum tree_code,
 366                         const svalue *rhs) = 0;
 367   virtual void on_ranges (const svalue *lhs,
 368                           const bounded_ranges *ranges) = 0;
 369 };
 370
 371 class bounded_ranges_constraint
 372 {
 373 public:
 374   bounded_ranges_constraint (equiv_class_id ec_id,
 375                              const bounded_ranges *ranges)
 376   : m_ec_id (ec_id), m_ranges (ranges)
 377   {
 378   }
 379
 380   void print (pretty_printer *pp, const constraint_manager &cm) const;
 381
 382   json::object *to_json () const;
 383
 384   bool operator== (const bounded_ranges_constraint &other) const;
 385   bool operator!= (const bounded_ranges_constraint &other) const
 386   {
 387     return !(*this == other);
 388   }
 389
 390   void add_to_hash (inchash::hash *hstate) const;
 391
 392   equiv_class_id m_ec_id;
 393   const bounded_ranges *m_ranges;
 394 };
 395
 396 /* A collection of equivalence classes and constraints on them.
 397
 398    Given N svalues, this can be thought of as representing a subset of
 399    N-dimensional space.  When we call add_constraint,
 400    we are effectively taking an intersection with that constraint.  */
 401
 402 class constraint_manager
 403 {
 404 public:
 405   constraint_manager (region_model_manager *mgr) : m_mgr (mgr) {}
 406   constraint_manager (const constraint_manager &other);
 407   virtual ~constraint_manager () {}
 408
 409   constraint_manager& operator= (const constraint_manager &other);
 410
 411   hashval_t hash () const;
 412   bool operator== (const constraint_manager &other) const;
 413   bool operator!= (const constraint_manager &other) const
 414   {
 415     return !(*this == other);
 416   }
 417
 418   void print (pretty_printer *pp) const;
 419   void dump_to_pp (pretty_printer *pp, bool multiline) const;
 420   void dump (FILE *fp) const;
 421   void dump () const;
 422
 423   json::object *to_json () const;
 424
 425   const equiv_class &get_equiv_class_by_index (unsigned idx) const
 426   {
 427     return *m_equiv_classes[idx];
 428   }
 429   equiv_class &get_equiv_class_by_index (unsigned idx)
 430   {
 431     return *m_equiv_classes[idx];
 432   }
 433
 434   equiv_class &get_equiv_class (const svalue *sval)
 435   {
 436     equiv_class_id ec_id = get_or_add_equiv_class (sval);
 437     return ec_id.get_obj (*this);
 438   }
 439
 440   bool add_constraint (const svalue *lhs,
 441                        enum tree_code op,
 442                        const svalue *rhs);
 443
 444   bool add_constraint (equiv_class_id lhs_ec_id,
 445                        enum tree_code op,
 446                        equiv_class_id rhs_ec_id);
 447
 448   void add_unknown_constraint (equiv_class_id lhs_ec_id,
 449                                enum tree_code op,
 450                                equiv_class_id rhs_ec_id);
 451
 452   bool add_bounded_ranges (const svalue *sval,
 453                            const bounded_ranges *ranges);
 454
 455   bool get_equiv_class_by_svalue (const svalue *sval,
 456                                     equiv_class_id *out) const;
 457   equiv_class_id get_or_add_equiv_class (const svalue *sval);
 458   tristate eval_condition (equiv_class_id lhs,
 459                            enum tree_code op,
 460                            equiv_class_id rhs) const;
 461   tristate eval_condition (equiv_class_id lhs_ec,
 462                            enum tree_code op,
 463                            tree rhs_const) const;
 464   tristate eval_condition (const svalue *lhs,
 465                            enum tree_code op,
 466                            const svalue *rhs) const;
 467   range get_ec_bounds (equiv_class_id ec_id) const;
 468
 469   /* PurgeCriteria should have:
 470      bool should_purge_p (const svalue *sval) const.  */
 471   template <typename PurgeCriteria>
 472   void purge (const PurgeCriteria &p, purge_stats *stats);
 473
 474   void on_liveness_change (const svalue_set &live_svalues,
 475                            const region_model *model);
 476   void purge_state_involving (const svalue *sval);
 477
 478   void canonicalize ();
 479
 480   static void merge (const constraint_manager &cm_a,
 481                      const constraint_manager &cm_b,
 482                      constraint_manager *out);
 483
 484   void for_each_fact (fact_visitor *) const;
 485
 486   void validate () const;
 487
 488   bounded_ranges_manager *get_range_manager () const;
 489
 490   bool replay_call_summary (call_summary_replay &r,
 491                             const constraint_manager &summary);
 492
 493   auto_delete_vec<equiv_class> m_equiv_classes;
 494   auto_vec<constraint> m_constraints;
 495   auto_vec<bounded_ranges_constraint> m_bounded_ranges_constraints;
 496
 497  private:
 498   void add_constraint_internal (equiv_class_id lhs_id,
 499                                 enum constraint_op c_op,
 500                                 equiv_class_id rhs_id);
 501
 502   region_model_manager *m_mgr;
 503 };
 504
 505 } // namespace ana
 506
 507 #endif /* GCC_ANALYZER_CONSTRAINT_MANAGER_H */