gcc/analyzer/region-model.h

   1 /* Classes for modeling the state of memory.
   2    Copyright (C) 2019-2023 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_REGION_MODEL_H
  22 #define GCC_ANALYZER_REGION_MODEL_H
  23
  24 /* Implementation of the region-based ternary model described in:
  25      "A Memory Model for Static Analysis of C Programs"
  26       (Zhongxing Xu, Ted Kremenek, and Jian Zhang)
  27      http://lcs.ios.ac.cn/~xuzb/canalyze/memmodel.pdf  */
  28
  29 #include "bitmap.h"
  30 #include "selftest.h"
  31 #include "analyzer/svalue.h"
  32 #include "analyzer/region.h"
  33 #include "analyzer/known-function-manager.h"
  34 #include "analyzer/region-model-manager.h"
  35 #include "analyzer/pending-diagnostic.h"
  36
  37 using namespace ana;
  38
  39 namespace inchash
  40 {
  41   extern void add_path_var (path_var pv, hash &hstate);
  42 } // namespace inchash
  43
  44 namespace ana {
  45
  46 template <typename T>
  47 class one_way_id_map
  48 {
  49  public:
  50   one_way_id_map (int num_ids);
  51   void put (T src, T dst);
  52   T get_dst_for_src (T src) const;
  53   void dump_to_pp (pretty_printer *pp) const;
  54   void dump () const;
  55   void update (T *) const;
  56
  57  private:
  58   auto_vec<T> m_src_to_dst;
  59  };
  60
  61 /* class one_way_id_map.  */
  62
  63 /* one_way_id_map's ctor, which populates the map with dummy null values.  */
  64
  65 template <typename T>
  66 inline one_way_id_map<T>::one_way_id_map (int num_svalues)
  67 : m_src_to_dst (num_svalues)
  68 {
  69   for (int i = 0; i < num_svalues; i++)
  70     m_src_to_dst.quick_push (T::null ());
  71 }
  72
  73 /* Record that SRC is to be mapped to DST.  */
  74
  75 template <typename T>
  76 inline void
  77 one_way_id_map<T>::put (T src, T dst)
  78 {
  79   m_src_to_dst[src.as_int ()] = dst;
  80 }
  81
  82 /* Get the new value for SRC within the map.  */
  83
  84 template <typename T>
  85 inline T
  86 one_way_id_map<T>::get_dst_for_src (T src) const
  87 {
  88   if (src.null_p ())
  89     return src;
  90   return m_src_to_dst[src.as_int ()];
  91 }
  92
  93 /* Dump this map to PP.  */
  94
  95 template <typename T>
  96 inline void
  97 one_way_id_map<T>::dump_to_pp (pretty_printer *pp) const
  98 {
  99   pp_string (pp, "src to dst: {");
 100   unsigned i;
 101   T *dst;
 102   FOR_EACH_VEC_ELT (m_src_to_dst, i, dst)
 103     {
 104       if (i > 0)
 105         pp_string (pp, ", ");
 106       T src (T::from_int (i));
 107       src.print (pp);
 108       pp_string (pp, " -> ");
 109       dst->print (pp);
 110     }
 111   pp_string (pp, "}");
 112   pp_newline (pp);
 113 }
 114
 115 /* Dump this map to stderr.  */
 116
 117 template <typename T>
 118 DEBUG_FUNCTION inline void
 119 one_way_id_map<T>::dump () const
 120 {
 121   pretty_printer pp;
 122   pp.buffer->stream = stderr;
 123   dump_to_pp (&pp);
 124   pp_flush (&pp);
 125 }
 126
 127 /* Update *ID from the old value to its new value in this map.  */
 128
 129 template <typename T>
 130 inline void
 131 one_way_id_map<T>::update (T *id) const
 132 {
 133   *id = get_dst_for_src (*id);
 134 }
 135
 136 /* A mapping from region to svalue for use when tracking state.  */
 137
 138 class region_to_value_map
 139 {
 140 public:
 141   typedef hash_map<const region *, const svalue *> hash_map_t;
 142   typedef hash_map_t::iterator iterator;
 143
 144   region_to_value_map () : m_hash_map () {}
 145   region_to_value_map (const region_to_value_map &other)
 146   : m_hash_map (other.m_hash_map) {}
 147   region_to_value_map &operator= (const region_to_value_map &other);
 148
 149   bool operator== (const region_to_value_map &other) const;
 150   bool operator!= (const region_to_value_map &other) const
 151   {
 152     return !(*this == other);
 153   }
 154
 155   iterator begin () const { return m_hash_map.begin (); }
 156   iterator end () const { return m_hash_map.end (); }
 157
 158   const svalue * const *get (const region *reg) const
 159   {
 160     return const_cast <hash_map_t &> (m_hash_map).get (reg);
 161   }
 162   void put (const region *reg, const svalue *sval)
 163   {
 164     m_hash_map.put (reg, sval);
 165   }
 166   void remove (const region *reg)
 167   {
 168     m_hash_map.remove (reg);
 169   }
 170
 171   bool is_empty () const { return m_hash_map.is_empty (); }
 172
 173   void dump_to_pp (pretty_printer *pp, bool simple, bool multiline) const;
 174   void dump (bool simple) const;
 175
 176   bool can_merge_with_p (const region_to_value_map &other,
 177                          region_to_value_map *out) const;
 178
 179   void purge_state_involving (const svalue *sval);
 180
 181 private:
 182   hash_map_t m_hash_map;
 183 };
 184
 185 /* Various operations delete information from a region_model.
 186
 187    This struct tracks how many of each kind of entity were purged (e.g.
 188    for selftests, and for debugging).  */
 189
 190 struct purge_stats
 191 {
 192   purge_stats ()
 193   : m_num_svalues (0),
 194     m_num_regions (0),
 195     m_num_equiv_classes (0),
 196     m_num_constraints (0),
 197     m_num_bounded_ranges_constraints (0),
 198     m_num_client_items (0)
 199   {}
 200
 201   int m_num_svalues;
 202   int m_num_regions;
 203   int m_num_equiv_classes;
 204   int m_num_constraints;
 205   int m_num_bounded_ranges_constraints;
 206   int m_num_client_items;
 207 };
 208
 209 /* A base class for visiting regions and svalues, with do-nothing
 210    base implementations of the per-subclass vfuncs.  */
 211
 212 class visitor
 213 {
 214 public:
 215   virtual void visit_region_svalue (const region_svalue *) {}
 216   virtual void visit_constant_svalue (const constant_svalue *) {}
 217   virtual void visit_unknown_svalue (const unknown_svalue *) {}
 218   virtual void visit_poisoned_svalue (const poisoned_svalue *) {}
 219   virtual void visit_setjmp_svalue (const setjmp_svalue *) {}
 220   virtual void visit_initial_svalue (const initial_svalue *) {}
 221   virtual void visit_unaryop_svalue (const unaryop_svalue *) {}
 222   virtual void visit_binop_svalue (const binop_svalue *) {}
 223   virtual void visit_sub_svalue (const sub_svalue *) {}
 224   virtual void visit_repeated_svalue (const repeated_svalue *) {}
 225   virtual void visit_bits_within_svalue (const bits_within_svalue *) {}
 226   virtual void visit_unmergeable_svalue (const unmergeable_svalue *) {}
 227   virtual void visit_placeholder_svalue (const placeholder_svalue *) {}
 228   virtual void visit_widening_svalue (const widening_svalue *) {}
 229   virtual void visit_compound_svalue (const compound_svalue *) {}
 230   virtual void visit_conjured_svalue (const conjured_svalue *) {}
 231   virtual void visit_asm_output_svalue (const asm_output_svalue *) {}
 232   virtual void visit_const_fn_result_svalue (const const_fn_result_svalue *) {}
 233
 234   virtual void visit_region (const region *) {}
 235 };
 236
 237 struct append_regions_cb_data;
 238
 239 /* A region_model encapsulates a representation of the state of memory, with
 240    a tree of regions, along with their associated values.
 241    The representation is graph-like because values can be pointers to
 242    regions.
 243    It also stores:
 244    - a constraint_manager, capturing relationships between the values, and
 245    - dynamic extents, mapping dynamically-allocated regions to svalues (their
 246    capacities).  */
 247
 248 class region_model
 249 {
 250  public:
 251   typedef region_to_value_map dynamic_extents_t;
 252
 253   region_model (region_model_manager *mgr);
 254   region_model (const region_model &other);
 255   ~region_model ();
 256   region_model &operator= (const region_model &other);
 257
 258   bool operator== (const region_model &other) const;
 259   bool operator!= (const region_model &other) const
 260   {
 261     return !(*this == other);
 262   }
 263
 264   hashval_t hash () const;
 265
 266   void print (pretty_printer *pp) const;
 267
 268   void dump_to_pp (pretty_printer *pp, bool simple, bool multiline) const;
 269   void dump (FILE *fp, bool simple, bool multiline) const;
 270   void dump (bool simple) const;
 271
 272   void debug () const;
 273
 274   void validate () const;
 275
 276   void canonicalize ();
 277   bool canonicalized_p () const;
 278
 279   void
 280   on_stmt_pre (const gimple *stmt,
 281                bool *out_unknown_side_effects,
 282                region_model_context *ctxt);
 283
 284   void on_assignment (const gassign *stmt, region_model_context *ctxt);
 285   const svalue *get_gassign_result (const gassign *assign,
 286                                     region_model_context *ctxt);
 287   void on_asm_stmt (const gasm *asm_stmt, region_model_context *ctxt);
 288   bool on_call_pre (const gcall *stmt, region_model_context *ctxt);
 289   void on_call_post (const gcall *stmt,
 290                      bool unknown_side_effects,
 291                      region_model_context *ctxt);
 292
 293   void purge_state_involving (const svalue *sval, region_model_context *ctxt);
 294
 295   void impl_deallocation_call (const call_details &cd);
 296
 297   const svalue *maybe_get_copy_bounds (const region *src_reg,
 298                                        const svalue *num_bytes_sval);
 299   void update_for_int_cst_return (const call_details &cd,
 300                                   int retval,
 301                                   bool unmergeable);
 302   void update_for_zero_return (const call_details &cd,
 303                                bool unmergeable);
 304   void update_for_nonzero_return (const call_details &cd);
 305
 306   void handle_unrecognized_call (const gcall *call,
 307                                  region_model_context *ctxt);
 308   void get_reachable_svalues (svalue_set *out,
 309                               const svalue *extra_sval,
 310                               const uncertainty_t *uncertainty);
 311
 312   void on_return (const greturn *stmt, region_model_context *ctxt);
 313   void on_setjmp (const gcall *stmt, const exploded_node *enode,
 314                   region_model_context *ctxt);
 315   void on_longjmp (const gcall *longjmp_call, const gcall *setjmp_call,
 316                    int setjmp_stack_depth, region_model_context *ctxt);
 317
 318   void update_for_phis (const supernode *snode,
 319                         const cfg_superedge *last_cfg_superedge,
 320                         region_model_context *ctxt);
 321
 322   void handle_phi (const gphi *phi, tree lhs, tree rhs,
 323                    const region_model &old_state,
 324                    region_model_context *ctxt);
 325
 326   bool maybe_update_for_edge (const superedge &edge,
 327                               const gimple *last_stmt,
 328                               region_model_context *ctxt,
 329                               rejected_constraint **out);
 330
 331   void update_for_gcall (const gcall *call_stmt,
 332                          region_model_context *ctxt,
 333                          function *callee = NULL);
 334
 335   void update_for_return_gcall (const gcall *call_stmt,
 336                                 region_model_context *ctxt);
 337
 338   const region *push_frame (function *fun, const vec<const svalue *> *arg_sids,
 339                             region_model_context *ctxt);
 340   const frame_region *get_current_frame () const { return m_current_frame; }
 341   function * get_current_function () const;
 342   void pop_frame (tree result_lvalue,
 343                   const svalue **out_result,
 344                   region_model_context *ctxt,
 345                   bool eval_return_svalue = true);
 346   int get_stack_depth () const;
 347   const frame_region *get_frame_at_index (int index) const;
 348
 349   const region *get_lvalue (path_var pv, region_model_context *ctxt) const;
 350   const region *get_lvalue (tree expr, region_model_context *ctxt) const;
 351   const svalue *get_rvalue (path_var pv, region_model_context *ctxt) const;
 352   const svalue *get_rvalue (tree expr, region_model_context *ctxt) const;
 353
 354   const region *deref_rvalue (const svalue *ptr_sval, tree ptr_tree,
 355                               region_model_context *ctxt,
 356                               bool add_nonnull_constraint = true) const;
 357
 358   const svalue *get_rvalue_for_bits (tree type,
 359                                      const region *reg,
 360                                      const bit_range &bits,
 361                                      region_model_context *ctxt) const;
 362
 363   void set_value (const region *lhs_reg, const svalue *rhs_sval,
 364                   region_model_context *ctxt);
 365   void set_value (tree lhs, tree rhs, region_model_context *ctxt);
 366   void clobber_region (const region *reg);
 367   void purge_region (const region *reg);
 368   void fill_region (const region *reg, const svalue *sval);
 369   void zero_fill_region (const region *reg);
 370   void mark_region_as_unknown (const region *reg, uncertainty_t *uncertainty);
 371
 372   tristate eval_condition (const svalue *lhs,
 373                            enum tree_code op,
 374                            const svalue *rhs) const;
 375   tristate compare_initial_and_pointer (const initial_svalue *init,
 376                                         const region_svalue *ptr) const;
 377   tristate symbolic_greater_than (const binop_svalue *a,
 378                                   const svalue *b) const;
 379   tristate structural_equality (const svalue *a, const svalue *b) const;
 380   tristate eval_condition (tree lhs,
 381                            enum tree_code op,
 382                            tree rhs,
 383                            region_model_context *ctxt) const;
 384   bool add_constraint (tree lhs, enum tree_code op, tree rhs,
 385                        region_model_context *ctxt);
 386   bool add_constraint (tree lhs, enum tree_code op, tree rhs,
 387                        region_model_context *ctxt,
 388                        rejected_constraint **out);
 389
 390         const region *
 391         get_or_create_region_for_heap_alloc (const svalue *size_in_bytes,
 392                                 region_model_context *ctxt,
 393                                 bool update_state_machine = false,
 394                                 const call_details *cd = nullptr);
 395
 396   const region *create_region_for_alloca (const svalue *size_in_bytes,
 397                                           region_model_context *ctxt);
 398   void get_referenced_base_regions (auto_bitmap &out_ids) const;
 399
 400   tree get_representative_tree (const svalue *sval) const;
 401   tree get_representative_tree (const region *reg) const;
 402   path_var
 403   get_representative_path_var (const svalue *sval,
 404                                svalue_set *visited) const;
 405   path_var
 406   get_representative_path_var (const region *reg,
 407                                svalue_set *visited) const;
 408
 409   /* For selftests.  */
 410   constraint_manager *get_constraints ()
 411   {
 412     return m_constraints;
 413   }
 414
 415   store *get_store () { return &m_store; }
 416   const store *get_store () const { return &m_store; }
 417
 418   const dynamic_extents_t &
 419   get_dynamic_extents () const
 420   {
 421     return m_dynamic_extents;
 422   }
 423   const svalue *get_dynamic_extents (const region *reg) const;
 424   void set_dynamic_extents (const region *reg,
 425                             const svalue *size_in_bytes,
 426                             region_model_context *ctxt);
 427   void unset_dynamic_extents (const region *reg);
 428
 429   region_model_manager *get_manager () const { return m_mgr; }
 430   bounded_ranges_manager *get_range_manager () const
 431   {
 432     return m_mgr->get_range_manager ();
 433   }
 434
 435   void unbind_region_and_descendents (const region *reg,
 436                                       enum poison_kind pkind);
 437
 438   bool can_merge_with_p (const region_model &other_model,
 439                          const program_point &point,
 440                          region_model *out_model,
 441                          const extrinsic_state *ext_state = NULL,
 442                          const program_state *state_a = NULL,
 443                          const program_state *state_b = NULL) const;
 444
 445   tree get_fndecl_for_call (const gcall *call,
 446                             region_model_context *ctxt);
 447
 448   void get_regions_for_current_frame (auto_vec<const decl_region *> *out) const;
 449   static void append_regions_cb (const region *base_reg,
 450                                  struct append_regions_cb_data *data);
 451
 452   const svalue *get_store_value (const region *reg,
 453                                  region_model_context *ctxt) const;
 454
 455   bool region_exists_p (const region *reg) const;
 456
 457   void loop_replay_fixup (const region_model *dst_state);
 458
 459   const svalue *get_capacity (const region *reg) const;
 460
 461   const svalue *get_string_size (const svalue *sval) const;
 462   const svalue *get_string_size (const region *reg) const;
 463
 464   bool replay_call_summary (call_summary_replay &r,
 465                             const region_model &summary);
 466
 467   void maybe_complain_about_infoleak (const region *dst_reg,
 468                                       const svalue *copied_sval,
 469                                       const region *src_reg,
 470                                       region_model_context *ctxt);
 471
 472   void set_errno (const call_details &cd);
 473
 474   /* Implemented in sm-fd.cc  */
 475   void mark_as_valid_fd (const svalue *sval, region_model_context *ctxt);
 476
 477   /* Implemented in sm-malloc.cc  */
 478   void on_realloc_with_move (const call_details &cd,
 479                              const svalue *old_ptr_sval,
 480                              const svalue *new_ptr_sval);
 481
 482   /* Implemented in sm-malloc.cc.  */
 483   void
 484   transition_ptr_sval_non_null (region_model_context *ctxt,
 485       const svalue *new_ptr_sval);
 486
 487   /* Implemented in sm-taint.cc.  */
 488   void mark_as_tainted (const svalue *sval,
 489                         region_model_context *ctxt);
 490
 491   bool add_constraint (const svalue *lhs,
 492                        enum tree_code op,
 493                        const svalue *rhs,
 494                        region_model_context *ctxt);
 495
 496   const svalue *check_for_poison (const svalue *sval,
 497                                   tree expr,
 498                                   const region *src_region,
 499                                   region_model_context *ctxt) const;
 500
 501   void check_region_for_write (const region *dest_reg,
 502                                const svalue *sval_hint,
 503                                region_model_context *ctxt) const;
 504
 505   void check_for_null_terminated_string_arg (const call_details &cd,
 506                                              unsigned idx);
 507
 508 private:
 509   const region *get_lvalue_1 (path_var pv, region_model_context *ctxt) const;
 510   const svalue *get_rvalue_1 (path_var pv, region_model_context *ctxt) const;
 511
 512   path_var
 513   get_representative_path_var_1 (const svalue *sval,
 514                                  svalue_set *visited) const;
 515   path_var
 516   get_representative_path_var_1 (const region *reg,
 517                                  svalue_set *visited) const;
 518
 519   const known_function *get_known_function (tree fndecl,
 520                                             const call_details &cd) const;
 521   const known_function *get_known_function (enum internal_fn) const;
 522
 523   bool add_constraints_from_binop (const svalue *outer_lhs,
 524                                    enum tree_code outer_op,
 525                                    const svalue *outer_rhs,
 526                                    bool *out,
 527                                    region_model_context *ctxt);
 528
 529   void update_for_call_superedge (const call_superedge &call_edge,
 530                                   region_model_context *ctxt);
 531   void update_for_return_superedge (const return_superedge &return_edge,
 532                                     region_model_context *ctxt);
 533   bool apply_constraints_for_gcond (const cfg_superedge &edge,
 534                                     const gcond *cond_stmt,
 535                                     region_model_context *ctxt,
 536                                     rejected_constraint **out);
 537   bool apply_constraints_for_gswitch (const switch_cfg_superedge &edge,
 538                                       const gswitch *switch_stmt,
 539                                       region_model_context *ctxt,
 540                                       rejected_constraint **out);
 541   bool apply_constraints_for_exception (const gimple *last_stmt,
 542                                         region_model_context *ctxt,
 543                                         rejected_constraint **out);
 544
 545   int poison_any_pointers_to_descendents (const region *reg,
 546                                           enum poison_kind pkind);
 547
 548   void on_top_level_param (tree param,
 549                            bool nonnull,
 550                            region_model_context *ctxt);
 551
 552   bool called_from_main_p () const;
 553   const svalue *get_initial_value_for_global (const region *reg) const;
 554
 555   const region * get_region_for_poisoned_expr (tree expr) const;
 556
 557   void check_dynamic_size_for_taint (enum memory_space mem_space,
 558                                      const svalue *size_in_bytes,
 559                                      region_model_context *ctxt) const;
 560   void check_dynamic_size_for_floats (const svalue *size_in_bytes,
 561                                       region_model_context *ctxt) const;
 562
 563   void check_region_for_taint (const region *reg,
 564                                enum access_direction dir,
 565                                region_model_context *ctxt) const;
 566
 567   void check_for_writable_region (const region* dest_reg,
 568                                   region_model_context *ctxt) const;
 569   bool check_region_access (const region *reg,
 570                             enum access_direction dir,
 571                             const svalue *sval_hint,
 572                             region_model_context *ctxt) const;
 573   bool check_region_for_read (const region *src_reg,
 574                               region_model_context *ctxt) const;
 575   void check_region_size (const region *lhs_reg, const svalue *rhs_sval,
 576                           region_model_context *ctxt) const;
 577
 578   /* Implemented in bounds-checking.cc  */
 579   bool check_symbolic_bounds (const region *base_reg,
 580                               const svalue *sym_byte_offset,
 581                               const svalue *num_bytes_sval,
 582                               const svalue *capacity,
 583                               enum access_direction dir,
 584                               const svalue *sval_hint,
 585                               region_model_context *ctxt) const;
 586   bool check_region_bounds (const region *reg, enum access_direction dir,
 587                             const svalue *sval_hint,
 588                             region_model_context *ctxt) const;
 589
 590   void check_call_args (const call_details &cd) const;
 591   void check_external_function_for_access_attr (const gcall *call,
 592                                                 tree callee_fndecl,
 593                                                 region_model_context *ctxt) const;
 594
 595   /* Storing this here to avoid passing it around everywhere.  */
 596   region_model_manager *const m_mgr;
 597
 598   store m_store;
 599
 600   constraint_manager *m_constraints; // TODO: embed, rather than dynalloc?
 601
 602   const frame_region *m_current_frame;
 603
 604   /* Map from base region to size in bytes, for tracking the sizes of
 605      dynamically-allocated regions.
 606      This is part of the region_model rather than the region to allow for
 607      memory regions to be resized (e.g. by realloc).  */
 608   dynamic_extents_t m_dynamic_extents;
 609 };
 610
 611 /* Some region_model activity could lead to warnings (e.g. attempts to use an
 612    uninitialized value).  This abstract base class encapsulates an interface
 613    for the region model to use when emitting such warnings.
 614
 615    Having this as an abstract base class allows us to support the various
 616    operations needed by program_state in the analyzer within region_model,
 617    whilst keeping them somewhat modularized.  */
 618
 619 class region_model_context
 620 {
 621  public:
 622   /* Hook for clients to store pending diagnostics.
 623      Return true if the diagnostic was stored, or false if it was deleted.  */
 624   virtual bool warn (std::unique_ptr<pending_diagnostic> d) = 0;
 625
 626   /* Hook for clients to add a note to the last previously stored
 627      pending diagnostic.  */
 628   virtual void add_note (std::unique_ptr<pending_note> pn) = 0;
 629
 630   /* Hook for clients to add an event to the last previously stored
 631      pending diagnostic.  */
 632   virtual void add_event (std::unique_ptr<checker_event> event) = 0;
 633
 634   /* Hook for clients to be notified when an SVAL that was reachable
 635      in a previous state is no longer live, so that clients can emit warnings
 636      about leaks.  */
 637   virtual void on_svalue_leak (const svalue *sval) = 0;
 638
 639   /* Hook for clients to be notified when the set of explicitly live
 640      svalues changes, so that they can purge state relating to dead
 641      svalues.  */
 642   virtual void on_liveness_change (const svalue_set &live_svalues,
 643                                    const region_model *model) = 0;
 644
 645   virtual logger *get_logger () = 0;
 646
 647   /* Hook for clients to be notified when the condition
 648      "LHS OP RHS" is added to the region model.
 649      This exists so that state machines can detect tests on edges,
 650      and use them to trigger sm-state transitions (e.g. transitions due
 651      to ptrs becoming known to be NULL or non-NULL, rather than just
 652      "unchecked") */
 653   virtual void on_condition (const svalue *lhs,
 654                              enum tree_code op,
 655                              const svalue *rhs) = 0;
 656
 657   /* Hook for clients to be notified when the condition that
 658      SVAL is within RANGES is added to the region model.
 659      Similar to on_condition, but for use when handling switch statements.
 660      RANGES is non-empty.  */
 661   virtual void on_bounded_ranges (const svalue &sval,
 662                                   const bounded_ranges &ranges) = 0;
 663
 664   /* Hook for clients to be notified when a frame is popped from the stack.  */
 665   virtual void on_pop_frame (const frame_region *) = 0;
 666
 667   /* Hooks for clients to be notified when an unknown change happens
 668      to SVAL (in response to a call to an unknown function).  */
 669   virtual void on_unknown_change (const svalue *sval, bool is_mutable) = 0;
 670
 671   /* Hooks for clients to be notified when a phi node is handled,
 672      where RHS is the pertinent argument.  */
 673   virtual void on_phi (const gphi *phi, tree rhs) = 0;
 674
 675   /* Hooks for clients to be notified when the region model doesn't
 676      know how to handle the tree code of T at LOC.  */
 677   virtual void on_unexpected_tree_code (tree t,
 678                                         const dump_location_t &loc) = 0;
 679
 680   /* Hook for clients to be notified when a function_decl escapes.  */
 681   virtual void on_escaped_function (tree fndecl) = 0;
 682
 683   virtual uncertainty_t *get_uncertainty () = 0;
 684
 685   /* Hook for clients to purge state involving SVAL.  */
 686   virtual void purge_state_involving (const svalue *sval) = 0;
 687
 688   /* Hook for clients to split state with a non-standard path.  */
 689   virtual void bifurcate (std::unique_ptr<custom_edge_info> info) = 0;
 690
 691   /* Hook for clients to terminate the standard path.  */
 692   virtual void terminate_path () = 0;
 693
 694   virtual const extrinsic_state *get_ext_state () const = 0;
 695
 696   /* Hook for clients to access the a specific state machine in
 697      any underlying program_state.  */
 698   virtual bool
 699   get_state_map_by_name (const char *name,
 700                          sm_state_map **out_smap,
 701                          const state_machine **out_sm,
 702                          unsigned *out_sm_idx,
 703                          std::unique_ptr<sm_context> *out_sm_context) = 0;
 704
 705   /* Precanned ways for clients to access specific state machines.  */
 706   bool get_fd_map (sm_state_map **out_smap,
 707                    const state_machine **out_sm,
 708                    unsigned *out_sm_idx,
 709                    std::unique_ptr<sm_context> *out_sm_context)
 710   {
 711     return get_state_map_by_name ("file-descriptor", out_smap, out_sm,
 712                                   out_sm_idx, out_sm_context);
 713   }
 714   bool get_malloc_map (sm_state_map **out_smap,
 715                        const state_machine **out_sm,
 716                        unsigned *out_sm_idx)
 717   {
 718     return get_state_map_by_name ("malloc", out_smap, out_sm, out_sm_idx, NULL);
 719   }
 720   bool get_taint_map (sm_state_map **out_smap,
 721                       const state_machine **out_sm,
 722                       unsigned *out_sm_idx)
 723   {
 724     return get_state_map_by_name ("taint", out_smap, out_sm, out_sm_idx, NULL);
 725   }
 726
 727   bool possibly_tainted_p (const svalue *sval);
 728
 729   /* Get the current statement, if any.  */
 730   virtual const gimple *get_stmt () const = 0;
 731 };
 732
 733 /* A "do nothing" subclass of region_model_context.  */
 734
 735 class noop_region_model_context : public region_model_context
 736 {
 737 public:
 738   bool warn (std::unique_ptr<pending_diagnostic>) override { return false; }
 739   void add_note (std::unique_ptr<pending_note>) override;
 740   void add_event (std::unique_ptr<checker_event>) override;
 741   void on_svalue_leak (const svalue *) override {}
 742   void on_liveness_change (const svalue_set &,
 743                            const region_model *) override {}
 744   logger *get_logger () override { return NULL; }
 745   void on_condition (const svalue *lhs ATTRIBUTE_UNUSED,
 746                      enum tree_code op ATTRIBUTE_UNUSED,
 747                      const svalue *rhs ATTRIBUTE_UNUSED) override
 748   {
 749   }
 750   void on_bounded_ranges (const svalue &,
 751                           const bounded_ranges &) override
 752   {
 753   }
 754   void on_pop_frame (const frame_region *) override {}
 755   void on_unknown_change (const svalue *sval ATTRIBUTE_UNUSED,
 756                           bool is_mutable ATTRIBUTE_UNUSED) override
 757   {
 758   }
 759   void on_phi (const gphi *phi ATTRIBUTE_UNUSED,
 760                tree rhs ATTRIBUTE_UNUSED) override
 761   {
 762   }
 763   void on_unexpected_tree_code (tree, const dump_location_t &) override {}
 764
 765   void on_escaped_function (tree) override {}
 766
 767   uncertainty_t *get_uncertainty () override { return NULL; }
 768
 769   void purge_state_involving (const svalue *sval ATTRIBUTE_UNUSED) override {}
 770
 771   void bifurcate (std::unique_ptr<custom_edge_info> info) override;
 772   void terminate_path () override;
 773
 774   const extrinsic_state *get_ext_state () const override { return NULL; }
 775
 776   bool get_state_map_by_name (const char *,
 777                               sm_state_map **,
 778                               const state_machine **,
 779                               unsigned *,
 780                               std::unique_ptr<sm_context> *) override
 781   {
 782     return false;
 783   }
 784
 785   const gimple *get_stmt () const override { return NULL; }
 786 };
 787
 788 /* A subclass of region_model_context for determining if operations fail
 789    e.g. "can we generate a region for the lvalue of EXPR?".  */
 790
 791 class tentative_region_model_context : public noop_region_model_context
 792 {
 793 public:
 794   tentative_region_model_context () : m_num_unexpected_codes (0) {}
 795
 796   void on_unexpected_tree_code (tree, const dump_location_t &)
 797     final override
 798   {
 799     m_num_unexpected_codes++;
 800   }
 801
 802   bool had_errors_p () const { return m_num_unexpected_codes > 0; }
 803
 804 private:
 805   int m_num_unexpected_codes;
 806 };
 807
 808 /* Subclass of region_model_context that wraps another context, allowing
 809    for extra code to be added to the various hooks.  */
 810
 811 class region_model_context_decorator : public region_model_context
 812 {
 813  public:
 814   bool warn (std::unique_ptr<pending_diagnostic> d) override
 815   {
 816     return m_inner->warn (std::move (d));
 817   }
 818
 819   void add_note (std::unique_ptr<pending_note> pn) override
 820   {
 821     m_inner->add_note (std::move (pn));
 822   }
 823   void add_event (std::unique_ptr<checker_event> event) override;
 824
 825   void on_svalue_leak (const svalue *sval) override
 826   {
 827     m_inner->on_svalue_leak (sval);
 828   }
 829
 830   void on_liveness_change (const svalue_set &live_svalues,
 831                            const region_model *model) override
 832   {
 833     m_inner->on_liveness_change (live_svalues, model);
 834   }
 835
 836   logger *get_logger () override
 837   {
 838     return m_inner->get_logger ();
 839   }
 840
 841   void on_condition (const svalue *lhs,
 842                      enum tree_code op,
 843                      const svalue *rhs) override
 844   {
 845     m_inner->on_condition (lhs, op, rhs);
 846   }
 847
 848   void on_bounded_ranges (const svalue &sval,
 849                           const bounded_ranges &ranges) override
 850   {
 851     m_inner->on_bounded_ranges (sval, ranges);
 852   }
 853
 854   void on_pop_frame (const frame_region *frame_reg) override
 855   {
 856     m_inner->on_pop_frame (frame_reg);
 857   }
 858
 859   void on_unknown_change (const svalue *sval, bool is_mutable) override
 860   {
 861     m_inner->on_unknown_change (sval, is_mutable);
 862   }
 863
 864   void on_phi (const gphi *phi, tree rhs) override
 865   {
 866     m_inner->on_phi (phi, rhs);
 867   }
 868
 869   void on_unexpected_tree_code (tree t,
 870                                 const dump_location_t &loc) override
 871   {
 872     m_inner->on_unexpected_tree_code (t, loc);
 873   }
 874
 875   void on_escaped_function (tree fndecl) override
 876   {
 877     m_inner->on_escaped_function (fndecl);
 878   }
 879
 880   uncertainty_t *get_uncertainty () override
 881   {
 882     return m_inner->get_uncertainty ();
 883   }
 884
 885   void purge_state_involving (const svalue *sval) override
 886   {
 887     m_inner->purge_state_involving (sval);
 888   }
 889
 890   void bifurcate (std::unique_ptr<custom_edge_info> info) override
 891   {
 892     m_inner->bifurcate (std::move (info));
 893   }
 894
 895   void terminate_path () override
 896   {
 897     m_inner->terminate_path ();
 898   }
 899
 900   const extrinsic_state *get_ext_state () const override
 901   {
 902     return m_inner->get_ext_state ();
 903   }
 904
 905   bool get_state_map_by_name (const char *name,
 906                               sm_state_map **out_smap,
 907                               const state_machine **out_sm,
 908                               unsigned *out_sm_idx,
 909                               std::unique_ptr<sm_context> *out_sm_context)
 910     override
 911   {
 912     return m_inner->get_state_map_by_name (name, out_smap, out_sm, out_sm_idx,
 913                                            out_sm_context);
 914   }
 915
 916   const gimple *get_stmt () const override
 917   {
 918     return m_inner->get_stmt ();
 919   }
 920
 921 protected:
 922   region_model_context_decorator (region_model_context *inner)
 923   : m_inner (inner)
 924   {
 925     gcc_assert (m_inner);
 926   }
 927
 928   region_model_context *m_inner;
 929 };
 930
 931 /* Subclass of region_model_context_decorator with a hook for adding
 932    notes/events when saving diagnostics.  */
 933
 934 class annotating_context : public region_model_context_decorator
 935 {
 936 public:
 937   bool warn (std::unique_ptr<pending_diagnostic> d) override
 938   {
 939     if (m_inner->warn (std::move (d)))
 940       {
 941         add_annotations ();
 942         return true;
 943       }
 944     else
 945       return false;
 946   }
 947
 948   /* Hook to add new event(s)/note(s)  */
 949   virtual void add_annotations () = 0;
 950
 951 protected:
 952   annotating_context (region_model_context *inner)
 953   : region_model_context_decorator (inner)
 954   {
 955   }
 956 };
 957
 958 /* A bundle of data for use when attempting to merge two region_model
 959    instances to make a third.  */
 960
 961 struct model_merger
 962 {
 963   model_merger (const region_model *model_a,
 964                 const region_model *model_b,
 965                 const program_point &point,
 966                 region_model *merged_model,
 967                 const extrinsic_state *ext_state,
 968                 const program_state *state_a,
 969                 const program_state *state_b)
 970   : m_model_a (model_a), m_model_b (model_b),
 971     m_point (point),
 972     m_merged_model (merged_model),
 973     m_ext_state (ext_state),
 974     m_state_a (state_a), m_state_b (state_b)
 975   {
 976   }
 977
 978   void dump_to_pp (pretty_printer *pp, bool simple) const;
 979   void dump (FILE *fp, bool simple) const;
 980   void dump (bool simple) const;
 981
 982   region_model_manager *get_manager () const
 983   {
 984     return m_model_a->get_manager ();
 985   }
 986
 987   bool mergeable_svalue_p (const svalue *) const;
 988   const function_point &get_function_point () const
 989   {
 990     return m_point.get_function_point ();
 991   }
 992
 993   const region_model *m_model_a;
 994   const region_model *m_model_b;
 995   const program_point &m_point;
 996   region_model *m_merged_model;
 997
 998   const extrinsic_state *m_ext_state;
 999   const program_state *m_state_a;
1000   const program_state *m_state_b;
1001 };
1002
1003 /* A record that can (optionally) be written out when
1004    region_model::add_constraint fails.  */
1005
1006 class rejected_constraint
1007 {
1008 public:
1009   virtual ~rejected_constraint () {}
1010   virtual void dump_to_pp (pretty_printer *pp) const = 0;
1011
1012   const region_model &get_model () const { return m_model; }
1013
1014 protected:
1015   rejected_constraint (const region_model &model)
1016   : m_model (model)
1017   {}
1018
1019   region_model m_model;
1020 };
1021
1022 class rejected_op_constraint : public rejected_constraint
1023 {
1024 public:
1025   rejected_op_constraint (const region_model &model,
1026                           tree lhs, enum tree_code op, tree rhs)
1027   : rejected_constraint (model),
1028     m_lhs (lhs), m_op (op), m_rhs (rhs)
1029   {}
1030
1031   void dump_to_pp (pretty_printer *pp) const final override;
1032
1033   tree m_lhs;
1034   enum tree_code m_op;
1035   tree m_rhs;
1036 };
1037
1038 class rejected_default_case : public rejected_constraint
1039 {
1040 public:
1041   rejected_default_case (const region_model &model)
1042   : rejected_constraint (model)
1043   {}
1044
1045   void dump_to_pp (pretty_printer *pp) const final override;
1046 };
1047
1048 class rejected_ranges_constraint : public rejected_constraint
1049 {
1050 public:
1051   rejected_ranges_constraint (const region_model &model,
1052                               tree expr, const bounded_ranges *ranges)
1053   : rejected_constraint (model),
1054     m_expr (expr), m_ranges (ranges)
1055   {}
1056
1057   void dump_to_pp (pretty_printer *pp) const final override;
1058
1059 private:
1060   tree m_expr;
1061   const bounded_ranges *m_ranges;
1062 };
1063
1064 /* A bundle of state.  */
1065
1066 class engine
1067 {
1068 public:
1069   engine (const supergraph *sg = NULL, logger *logger = NULL);
1070   const supergraph *get_supergraph () { return m_sg; }
1071   region_model_manager *get_model_manager () { return &m_mgr; }
1072   known_function_manager *get_known_function_manager ()
1073   {
1074     return m_mgr.get_known_function_manager ();
1075   }
1076
1077   void log_stats (logger *logger) const;
1078
1079 private:
1080   const supergraph *m_sg;
1081   region_model_manager m_mgr;
1082 };
1083
1084 } // namespace ana
1085
1086 extern void debug (const region_model &rmodel);
1087
1088 namespace ana {
1089
1090 #if CHECKING_P
1091
1092 namespace selftest {
1093
1094 using namespace ::selftest;
1095
1096 /* An implementation of region_model_context for use in selftests, which
1097    stores any pending_diagnostic instances passed to it.  */
1098
1099 class test_region_model_context : public noop_region_model_context
1100 {
1101 public:
1102   bool warn (std::unique_ptr<pending_diagnostic> d) final override
1103   {
1104     m_diagnostics.safe_push (d.release ());
1105     return true;
1106   }
1107
1108   unsigned get_num_diagnostics () const { return m_diagnostics.length (); }
1109
1110   void on_unexpected_tree_code (tree t, const dump_location_t &)
1111     final override
1112   {
1113     internal_error ("unhandled tree code: %qs",
1114                     get_tree_code_name (TREE_CODE (t)));
1115   }
1116
1117 private:
1118   /* Implicitly delete any diagnostics in the dtor.  */
1119   auto_delete_vec<pending_diagnostic> m_diagnostics;
1120 };
1121
1122 /* Attempt to add the constraint (LHS OP RHS) to MODEL.
1123    Verify that MODEL remains satisfiable.  */
1124
1125 #define ADD_SAT_CONSTRAINT(MODEL, LHS, OP, RHS) \
1126   SELFTEST_BEGIN_STMT                                   \
1127     bool sat = (MODEL).add_constraint (LHS, OP, RHS, NULL);     \
1128     ASSERT_TRUE (sat);                                  \
1129   SELFTEST_END_STMT
1130
1131 /* Attempt to add the constraint (LHS OP RHS) to MODEL.
1132    Verify that the result is not satisfiable.  */
1133
1134 #define ADD_UNSAT_CONSTRAINT(MODEL, LHS, OP, RHS)       \
1135   SELFTEST_BEGIN_STMT                                   \
1136     bool sat = (MODEL).add_constraint (LHS, OP, RHS, NULL);     \
1137     ASSERT_FALSE (sat);                         \
1138   SELFTEST_END_STMT
1139
1140 /* Implementation detail of the ASSERT_CONDITION_* macros.  */
1141
1142 void assert_condition (const location &loc,
1143                        region_model &model,
1144                        const svalue *lhs, tree_code op, const svalue *rhs,
1145                        tristate expected);
1146
1147 void assert_condition (const location &loc,
1148                        region_model &model,
1149                        tree lhs, tree_code op, tree rhs,
1150                        tristate expected);
1151
1152 /* Assert that REGION_MODEL evaluates the condition "LHS OP RHS"
1153    as "true".  */
1154
1155 #define ASSERT_CONDITION_TRUE(REGION_MODEL, LHS, OP, RHS) \
1156   SELFTEST_BEGIN_STMT                                                   \
1157   assert_condition (SELFTEST_LOCATION, REGION_MODEL, LHS, OP, RHS,      \
1158                     tristate (tristate::TS_TRUE));              \
1159   SELFTEST_END_STMT
1160
1161 /* Assert that REGION_MODEL evaluates the condition "LHS OP RHS"
1162    as "false".  */
1163
1164 #define ASSERT_CONDITION_FALSE(REGION_MODEL, LHS, OP, RHS) \
1165   SELFTEST_BEGIN_STMT                                                   \
1166   assert_condition (SELFTEST_LOCATION, REGION_MODEL, LHS, OP, RHS,      \
1167                     tristate (tristate::TS_FALSE));             \
1168   SELFTEST_END_STMT
1169
1170 /* Assert that REGION_MODEL evaluates the condition "LHS OP RHS"
1171    as "unknown".  */
1172
1173 #define ASSERT_CONDITION_UNKNOWN(REGION_MODEL, LHS, OP, RHS) \
1174   SELFTEST_BEGIN_STMT                                                   \
1175   assert_condition (SELFTEST_LOCATION, REGION_MODEL, LHS, OP, RHS,      \
1176                     tristate (tristate::TS_UNKNOWN));           \
1177   SELFTEST_END_STMT
1178
1179 } /* end of namespace selftest.  */
1180
1181 #endif /* #if CHECKING_P */
1182
1183 } // namespace ana
1184
1185 #endif /* GCC_ANALYZER_REGION_MODEL_H */