gcc/analyzer/region-model.h

   1 /* Classes for modeling the state of memory.
   2    Copyright (C) 2019-2021 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 "analyzer/svalue.h"
  30 #include "analyzer/region.h"
  31
  32 using namespace ana;
  33
  34 namespace inchash
  35 {
  36   extern void add_path_var (path_var pv, hash &hstate);
  37 } // namespace inchash
  38
  39 namespace ana {
  40
  41 template <typename T>
  42 class one_way_id_map
  43 {
  44  public:
  45   one_way_id_map (int num_ids);
  46   void put (T src, T dst);
  47   T get_dst_for_src (T src) const;
  48   void dump_to_pp (pretty_printer *pp) const;
  49   void dump () const;
  50   void update (T *) const;
  51
  52  private:
  53   auto_vec<T> m_src_to_dst;
  54  };
  55
  56 /* class one_way_id_map.  */
  57
  58 /* one_way_id_map's ctor, which populates the map with dummy null values.  */
  59
  60 template <typename T>
  61 inline one_way_id_map<T>::one_way_id_map (int num_svalues)
  62 : m_src_to_dst (num_svalues)
  63 {
  64   for (int i = 0; i < num_svalues; i++)
  65     m_src_to_dst.quick_push (T::null ());
  66 }
  67
  68 /* Record that SRC is to be mapped to DST.  */
  69
  70 template <typename T>
  71 inline void
  72 one_way_id_map<T>::put (T src, T dst)
  73 {
  74   m_src_to_dst[src.as_int ()] = dst;
  75 }
  76
  77 /* Get the new value for SRC within the map.  */
  78
  79 template <typename T>
  80 inline T
  81 one_way_id_map<T>::get_dst_for_src (T src) const
  82 {
  83   if (src.null_p ())
  84     return src;
  85   return m_src_to_dst[src.as_int ()];
  86 }
  87
  88 /* Dump this map to PP.  */
  89
  90 template <typename T>
  91 inline void
  92 one_way_id_map<T>::dump_to_pp (pretty_printer *pp) const
  93 {
  94   pp_string (pp, "src to dst: {");
  95   unsigned i;
  96   T *dst;
  97   FOR_EACH_VEC_ELT (m_src_to_dst, i, dst)
  98     {
  99       if (i > 0)
 100         pp_string (pp, ", ");
 101       T src (T::from_int (i));
 102       src.print (pp);
 103       pp_string (pp, " -> ");
 104       dst->print (pp);
 105     }
 106   pp_string (pp, "}");
 107   pp_newline (pp);
 108 }
 109
 110 /* Dump this map to stderr.  */
 111
 112 template <typename T>
 113 DEBUG_FUNCTION inline void
 114 one_way_id_map<T>::dump () const
 115 {
 116   pretty_printer pp;
 117   pp.buffer->stream = stderr;
 118   dump_to_pp (&pp);
 119   pp_flush (&pp);
 120 }
 121
 122 /* Update *ID from the old value to its new value in this map.  */
 123
 124 template <typename T>
 125 inline void
 126 one_way_id_map<T>::update (T *id) const
 127 {
 128   *id = get_dst_for_src (*id);
 129 }
 130
 131 /* A mapping from region to svalue for use when tracking state.  */
 132
 133 class region_to_value_map
 134 {
 135 public:
 136   typedef hash_map<const region *, const svalue *> hash_map_t;
 137   typedef hash_map_t::iterator iterator;
 138
 139   region_to_value_map () : m_hash_map () {}
 140   region_to_value_map (const region_to_value_map &other)
 141   : m_hash_map (other.m_hash_map) {}
 142   region_to_value_map &operator= (const region_to_value_map &other);
 143
 144   bool operator== (const region_to_value_map &other) const;
 145   bool operator!= (const region_to_value_map &other) const
 146   {
 147     return !(*this == other);
 148   }
 149
 150   iterator begin () const { return m_hash_map.begin (); }
 151   iterator end () const { return m_hash_map.end (); }
 152
 153   const svalue * const *get (const region *reg) const
 154   {
 155     return const_cast <hash_map_t &> (m_hash_map).get (reg);
 156   }
 157   void put (const region *reg, const svalue *sval)
 158   {
 159     m_hash_map.put (reg, sval);
 160   }
 161   void remove (const region *reg)
 162   {
 163     m_hash_map.remove (reg);
 164   }
 165
 166   bool is_empty () const { return m_hash_map.is_empty (); }
 167
 168   void dump_to_pp (pretty_printer *pp, bool simple, bool multiline) const;
 169   void dump (bool simple) const;
 170
 171   bool can_merge_with_p (const region_to_value_map &other,
 172                          region_to_value_map *out) const;
 173
 174   void purge_state_involving (const svalue *sval);
 175
 176 private:
 177   hash_map_t m_hash_map;
 178 };
 179
 180 /* Various operations delete information from a region_model.
 181
 182    This struct tracks how many of each kind of entity were purged (e.g.
 183    for selftests, and for debugging).  */
 184
 185 struct purge_stats
 186 {
 187   purge_stats ()
 188   : m_num_svalues (0),
 189     m_num_regions (0),
 190     m_num_equiv_classes (0),
 191     m_num_constraints (0),
 192     m_num_client_items (0)
 193   {}
 194
 195   int m_num_svalues;
 196   int m_num_regions;
 197   int m_num_equiv_classes;
 198   int m_num_constraints;
 199   int m_num_client_items;
 200 };
 201
 202 /* A base class for visiting regions and svalues, with do-nothing
 203    base implementations of the per-subclass vfuncs.  */
 204
 205 class visitor
 206 {
 207 public:
 208   virtual void visit_region_svalue (const region_svalue *) {}
 209   virtual void visit_constant_svalue (const constant_svalue *) {}
 210   virtual void visit_unknown_svalue (const unknown_svalue *) {}
 211   virtual void visit_poisoned_svalue (const poisoned_svalue *) {}
 212   virtual void visit_setjmp_svalue (const setjmp_svalue *) {}
 213   virtual void visit_initial_svalue (const initial_svalue *) {}
 214   virtual void visit_unaryop_svalue (const unaryop_svalue *) {}
 215   virtual void visit_binop_svalue (const binop_svalue *) {}
 216   virtual void visit_sub_svalue (const sub_svalue *) {}
 217   virtual void visit_repeated_svalue (const repeated_svalue *) {}
 218   virtual void visit_bits_within_svalue (const bits_within_svalue *) {}
 219   virtual void visit_unmergeable_svalue (const unmergeable_svalue *) {}
 220   virtual void visit_placeholder_svalue (const placeholder_svalue *) {}
 221   virtual void visit_widening_svalue (const widening_svalue *) {}
 222   virtual void visit_compound_svalue (const compound_svalue *) {}
 223   virtual void visit_conjured_svalue (const conjured_svalue *) {}
 224   virtual void visit_asm_output_svalue (const asm_output_svalue *) {}
 225
 226   virtual void visit_region (const region *) {}
 227 };
 228
 229 } // namespace ana
 230
 231 namespace ana {
 232
 233 /* A class responsible for owning and consolidating region and svalue
 234    instances.
 235    region and svalue instances are immutable as far as clients are
 236    concerned, so they are provided as "const" ptrs.  */
 237
 238 class region_model_manager
 239 {
 240 public:
 241   region_model_manager ();
 242   ~region_model_manager ();
 243
 244   /* svalue consolidation.  */
 245   const svalue *get_or_create_constant_svalue (tree cst_expr);
 246   const svalue *get_or_create_int_cst (tree type, poly_int64);
 247   const svalue *get_or_create_unknown_svalue (tree type);
 248   const svalue *get_or_create_setjmp_svalue (const setjmp_record &r,
 249                                              tree type);
 250   const svalue *get_or_create_poisoned_svalue (enum poison_kind kind,
 251                                                tree type);
 252   const svalue *get_or_create_initial_value (const region *reg);
 253   const svalue *get_ptr_svalue (tree ptr_type, const region *pointee);
 254   const svalue *get_or_create_unaryop (tree type, enum tree_code op,
 255                                        const svalue *arg);
 256   const svalue *get_or_create_cast (tree type, const svalue *arg);
 257   const svalue *get_or_create_binop (tree type,
 258                                      enum tree_code op,
 259                                      const svalue *arg0, const svalue *arg1);
 260   const svalue *get_or_create_sub_svalue (tree type,
 261                                           const svalue *parent_svalue,
 262                                           const region *subregion);
 263   const svalue *get_or_create_repeated_svalue (tree type,
 264                                                const svalue *outer_size,
 265                                                const svalue *inner_svalue);
 266   const svalue *get_or_create_bits_within (tree type,
 267                                            const bit_range &bits,
 268                                            const svalue *inner_svalue);
 269   const svalue *get_or_create_unmergeable (const svalue *arg);
 270   const svalue *get_or_create_widening_svalue (tree type,
 271                                                const program_point &point,
 272                                                const svalue *base_svalue,
 273                                                const svalue *iter_svalue);
 274   const svalue *get_or_create_compound_svalue (tree type,
 275                                                const binding_map &map);
 276   const svalue *get_or_create_conjured_svalue (tree type, const gimple *stmt,
 277                                                const region *id_reg);
 278   const svalue *
 279   get_or_create_asm_output_svalue (tree type,
 280                                    const gasm *asm_stmt,
 281                                    unsigned output_idx,
 282                                    const vec<const svalue *> &inputs);
 283
 284   const svalue *maybe_get_char_from_string_cst (tree string_cst,
 285                                                 tree byte_offset_cst);
 286
 287   /* region consolidation.  */
 288   const stack_region * get_stack_region () const { return &m_stack_region; }
 289   const heap_region *get_heap_region () const { return &m_heap_region; }
 290   const code_region *get_code_region () const { return &m_code_region; }
 291   const globals_region *get_globals_region () const
 292   {
 293     return &m_globals_region;
 294   }
 295   const function_region *get_region_for_fndecl (tree fndecl);
 296   const label_region *get_region_for_label (tree label);
 297   const decl_region *get_region_for_global (tree expr);
 298   const region *get_field_region (const region *parent, tree field);
 299   const region *get_element_region (const region *parent,
 300                                     tree element_type,
 301                                     const svalue *index);
 302   const region *get_offset_region (const region *parent,
 303                                    tree type,
 304                                    const svalue *byte_offset);
 305   const region *get_sized_region (const region *parent,
 306                                   tree type,
 307                                   const svalue *byte_size_sval);
 308   const region *get_cast_region (const region *original_region,
 309                                  tree type);
 310   const frame_region *get_frame_region (const frame_region *calling_frame,
 311                                         function *fun);
 312   const region *get_symbolic_region (const svalue *sval);
 313   const string_region *get_region_for_string (tree string_cst);
 314
 315   const region *
 316   get_region_for_unexpected_tree_code (region_model_context *ctxt,
 317                                        tree t,
 318                                        const dump_location_t &loc);
 319
 320   unsigned alloc_region_id () { return m_next_region_id++; }
 321
 322   store_manager *get_store_manager () { return &m_store_mgr; }
 323
 324   /* Dynamically-allocated region instances.
 325      The number of these within the analysis can grow arbitrarily.
 326      They are still owned by the manager.  */
 327   const region *create_region_for_heap_alloc ();
 328   const region *create_region_for_alloca (const frame_region *frame);
 329
 330   void log_stats (logger *logger, bool show_objs) const;
 331
 332   void enable_complexity_check (void) { m_check_complexity = true; }
 333   void disable_complexity_check (void) { m_check_complexity = false; }
 334
 335 private:
 336   bool too_complex_p (const complexity &c) const;
 337   bool reject_if_too_complex (svalue *sval);
 338
 339   const svalue *maybe_fold_unaryop (tree type, enum tree_code op,
 340                                     const svalue *arg);
 341   const svalue *maybe_fold_binop (tree type, enum tree_code op,
 342                                   const svalue *arg0, const svalue *arg1);
 343   const svalue *maybe_fold_sub_svalue (tree type,
 344                                        const svalue *parent_svalue,
 345                                        const region *subregion);
 346   const svalue *maybe_fold_repeated_svalue (tree type,
 347                                             const svalue *outer_size,
 348                                             const svalue *inner_svalue);
 349   const svalue *maybe_fold_bits_within_svalue (tree type,
 350                                                const bit_range &bits,
 351                                                const svalue *inner_svalue);
 352   const svalue *maybe_undo_optimize_bit_field_compare (tree type,
 353                                                        const compound_svalue *compound_sval,
 354                                                        tree cst, const svalue *arg1);
 355   const svalue *maybe_fold_asm_output_svalue (tree type,
 356                                               const vec<const svalue *> &inputs);
 357
 358   unsigned m_next_region_id;
 359   root_region m_root_region;
 360   stack_region m_stack_region;
 361   heap_region m_heap_region;
 362
 363   /* svalue consolidation.  */
 364   typedef hash_map<tree, constant_svalue *> constants_map_t;
 365   constants_map_t m_constants_map;
 366
 367   typedef hash_map<tree, unknown_svalue *> unknowns_map_t;
 368   unknowns_map_t m_unknowns_map;
 369   const unknown_svalue *m_unknown_NULL;
 370
 371   typedef hash_map<poisoned_svalue::key_t,
 372                    poisoned_svalue *> poisoned_values_map_t;
 373   poisoned_values_map_t m_poisoned_values_map;
 374
 375   typedef hash_map<setjmp_svalue::key_t,
 376                    setjmp_svalue *> setjmp_values_map_t;
 377   setjmp_values_map_t m_setjmp_values_map;
 378
 379   typedef hash_map<const region *, initial_svalue *> initial_values_map_t;
 380   initial_values_map_t m_initial_values_map;
 381
 382   typedef hash_map<region_svalue::key_t, region_svalue *> pointer_values_map_t;
 383   pointer_values_map_t m_pointer_values_map;
 384
 385   typedef hash_map<unaryop_svalue::key_t,
 386                    unaryop_svalue *> unaryop_values_map_t;
 387   unaryop_values_map_t m_unaryop_values_map;
 388
 389   typedef hash_map<binop_svalue::key_t, binop_svalue *> binop_values_map_t;
 390   binop_values_map_t m_binop_values_map;
 391
 392   typedef hash_map<sub_svalue::key_t, sub_svalue *> sub_values_map_t;
 393   sub_values_map_t m_sub_values_map;
 394
 395   typedef hash_map<repeated_svalue::key_t,
 396                    repeated_svalue *> repeated_values_map_t;
 397   repeated_values_map_t m_repeated_values_map;
 398
 399   typedef hash_map<bits_within_svalue::key_t,
 400                    bits_within_svalue *> bits_within_values_map_t;
 401   bits_within_values_map_t m_bits_within_values_map;
 402
 403   typedef hash_map<const svalue *,
 404                    unmergeable_svalue *> unmergeable_values_map_t;
 405   unmergeable_values_map_t m_unmergeable_values_map;
 406
 407   typedef hash_map<widening_svalue::key_t,
 408                    widening_svalue */*,
 409                    widening_svalue::key_t::hash_map_traits*/>
 410     widening_values_map_t;
 411   widening_values_map_t m_widening_values_map;
 412
 413   typedef hash_map<compound_svalue::key_t,
 414                    compound_svalue *> compound_values_map_t;
 415   compound_values_map_t m_compound_values_map;
 416
 417   typedef hash_map<conjured_svalue::key_t,
 418                    conjured_svalue *> conjured_values_map_t;
 419   conjured_values_map_t m_conjured_values_map;
 420
 421   typedef hash_map<asm_output_svalue::key_t,
 422                    asm_output_svalue *> asm_output_values_map_t;
 423   asm_output_values_map_t m_asm_output_values_map;
 424
 425   bool m_check_complexity;
 426
 427   /* Maximum complexity of svalues that weren't rejected.  */
 428   complexity m_max_complexity;
 429
 430   /* region consolidation.  */
 431
 432   code_region m_code_region;
 433   typedef hash_map<tree, function_region *> fndecls_map_t;
 434   typedef fndecls_map_t::iterator fndecls_iterator_t;
 435   fndecls_map_t m_fndecls_map;
 436
 437   typedef hash_map<tree, label_region *> labels_map_t;
 438   typedef labels_map_t::iterator labels_iterator_t;
 439   labels_map_t m_labels_map;
 440
 441   globals_region m_globals_region;
 442   typedef hash_map<tree, decl_region *> globals_map_t;
 443   typedef globals_map_t::iterator globals_iterator_t;
 444   globals_map_t m_globals_map;
 445
 446   consolidation_map<field_region> m_field_regions;
 447   consolidation_map<element_region> m_element_regions;
 448   consolidation_map<offset_region> m_offset_regions;
 449   consolidation_map<sized_region> m_sized_regions;
 450   consolidation_map<cast_region> m_cast_regions;
 451   consolidation_map<frame_region> m_frame_regions;
 452   consolidation_map<symbolic_region> m_symbolic_regions;
 453
 454   typedef hash_map<tree, string_region *> string_map_t;
 455   string_map_t m_string_map;
 456
 457   store_manager m_store_mgr;
 458
 459   /* "Dynamically-allocated" region instances.
 460      The number of these within the analysis can grow arbitrarily.
 461      They are still owned by the manager.  */
 462   auto_delete_vec<region> m_managed_dynamic_regions;
 463 };
 464
 465 struct append_ssa_names_cb_data;
 466
 467 /* Helper class for handling calls to functions with known behavior.
 468    Implemented in region-model-impl-calls.c.  */
 469
 470 class call_details
 471 {
 472 public:
 473   call_details (const gcall *call, region_model *model,
 474                 region_model_context *ctxt);
 475
 476   region_model_context *get_ctxt () const { return m_ctxt; }
 477   uncertainty_t *get_uncertainty () const;
 478   tree get_lhs_type () const { return m_lhs_type; }
 479   const region *get_lhs_region () const { return m_lhs_region; }
 480
 481   bool maybe_set_lhs (const svalue *result) const;
 482
 483   unsigned num_args () const;
 484
 485   tree get_arg_tree (unsigned idx) const;
 486   tree get_arg_type (unsigned idx) const;
 487   const svalue *get_arg_svalue (unsigned idx) const;
 488   const char *get_arg_string_literal (unsigned idx) const;
 489
 490   void dump_to_pp (pretty_printer *pp, bool simple) const;
 491   void dump (bool simple) const;
 492
 493   const svalue *get_or_create_conjured_svalue (const region *) const;
 494
 495 private:
 496   const gcall *m_call;
 497   region_model *m_model;
 498   region_model_context *m_ctxt;
 499   tree m_lhs_type;
 500   const region *m_lhs_region;
 501 };
 502
 503 /* A region_model encapsulates a representation of the state of memory, with
 504    a tree of regions, along with their associated values.
 505    The representation is graph-like because values can be pointers to
 506    regions.
 507    It also stores:
 508    - a constraint_manager, capturing relationships between the values, and
 509    - dynamic extents, mapping dynamically-allocated regions to svalues (their
 510    capacities).  */
 511
 512 class region_model
 513 {
 514  public:
 515   typedef region_to_value_map dynamic_extents_t;
 516
 517   region_model (region_model_manager *mgr);
 518   region_model (const region_model &other);
 519   ~region_model ();
 520   region_model &operator= (const region_model &other);
 521
 522   bool operator== (const region_model &other) const;
 523   bool operator!= (const region_model &other) const
 524   {
 525     return !(*this == other);
 526   }
 527
 528   hashval_t hash () const;
 529
 530   void print (pretty_printer *pp) const;
 531
 532   void dump_to_pp (pretty_printer *pp, bool simple, bool multiline) const;
 533   void dump (FILE *fp, bool simple, bool multiline) const;
 534   void dump (bool simple) const;
 535
 536   void debug () const;
 537
 538   void validate () const;
 539
 540   void canonicalize ();
 541   bool canonicalized_p () const;
 542
 543   void
 544   on_stmt_pre (const gimple *stmt,
 545                bool *out_terminate_path,
 546                bool *out_unknown_side_effects,
 547                region_model_context *ctxt);
 548
 549   void on_assignment (const gassign *stmt, region_model_context *ctxt);
 550   const svalue *get_gassign_result (const gassign *assign,
 551                                     region_model_context *ctxt);
 552   void on_asm_stmt (const gasm *asm_stmt, region_model_context *ctxt);
 553   bool on_call_pre (const gcall *stmt, region_model_context *ctxt,
 554                     bool *out_terminate_path);
 555   void on_call_post (const gcall *stmt,
 556                      bool unknown_side_effects,
 557                      region_model_context *ctxt);
 558
 559   void purge_state_involving (const svalue *sval, region_model_context *ctxt);
 560
 561   /* Specific handling for on_call_pre.  */
 562   void impl_call_alloca (const call_details &cd);
 563   void impl_call_analyzer_describe (const gcall *call,
 564                                     region_model_context *ctxt);
 565   void impl_call_analyzer_dump_capacity (const gcall *call,
 566                                          region_model_context *ctxt);
 567   void impl_call_analyzer_eval (const gcall *call,
 568                                 region_model_context *ctxt);
 569   void impl_call_builtin_expect (const call_details &cd);
 570   void impl_call_calloc (const call_details &cd);
 571   bool impl_call_error (const call_details &cd, unsigned min_args,
 572                         bool *out_terminate_path);
 573   void impl_call_fgets (const call_details &cd);
 574   void impl_call_fread (const call_details &cd);
 575   void impl_call_free (const call_details &cd);
 576   void impl_call_malloc (const call_details &cd);
 577   void impl_call_memcpy (const call_details &cd);
 578   void impl_call_memset (const call_details &cd);
 579   void impl_call_realloc (const call_details &cd);
 580   void impl_call_strcpy (const call_details &cd);
 581   void impl_call_strlen (const call_details &cd);
 582   void impl_call_operator_new (const call_details &cd);
 583   void impl_call_operator_delete (const call_details &cd);
 584   void impl_deallocation_call (const call_details &cd);
 585
 586   void handle_unrecognized_call (const gcall *call,
 587                                  region_model_context *ctxt);
 588   void get_reachable_svalues (svalue_set *out,
 589                               const svalue *extra_sval,
 590                               const uncertainty_t *uncertainty);
 591
 592   void on_return (const greturn *stmt, region_model_context *ctxt);
 593   void on_setjmp (const gcall *stmt, const exploded_node *enode,
 594                   region_model_context *ctxt);
 595   void on_longjmp (const gcall *longjmp_call, const gcall *setjmp_call,
 596                    int setjmp_stack_depth, region_model_context *ctxt);
 597
 598   void update_for_phis (const supernode *snode,
 599                         const cfg_superedge *last_cfg_superedge,
 600                         region_model_context *ctxt);
 601
 602   void handle_phi (const gphi *phi, tree lhs, tree rhs,
 603                    const region_model &old_state,
 604                    region_model_context *ctxt);
 605
 606   bool maybe_update_for_edge (const superedge &edge,
 607                               const gimple *last_stmt,
 608                               region_model_context *ctxt,
 609                               rejected_constraint **out);
 610
 611   const region *push_frame (function *fun, const vec<const svalue *> *arg_sids,
 612                             region_model_context *ctxt);
 613   const frame_region *get_current_frame () const { return m_current_frame; }
 614   function * get_current_function () const;
 615   void pop_frame (const region *result_dst,
 616                   const svalue **out_result,
 617                   region_model_context *ctxt);
 618   int get_stack_depth () const;
 619   const frame_region *get_frame_at_index (int index) const;
 620
 621   const region *get_lvalue (path_var pv, region_model_context *ctxt) const;
 622   const region *get_lvalue (tree expr, region_model_context *ctxt) const;
 623   const svalue *get_rvalue (path_var pv, region_model_context *ctxt) const;
 624   const svalue *get_rvalue (tree expr, region_model_context *ctxt) const;
 625
 626   const region *deref_rvalue (const svalue *ptr_sval, tree ptr_tree,
 627                                region_model_context *ctxt) const;
 628
 629   const svalue *get_rvalue_for_bits (tree type,
 630                                      const region *reg,
 631                                      const bit_range &bits,
 632                                      region_model_context *ctxt) const;
 633
 634   void set_value (const region *lhs_reg, const svalue *rhs_sval,
 635                   region_model_context *ctxt);
 636   void set_value (tree lhs, tree rhs, region_model_context *ctxt);
 637   void clobber_region (const region *reg);
 638   void purge_region (const region *reg);
 639   void fill_region (const region *reg, const svalue *sval);
 640   void zero_fill_region (const region *reg);
 641   void mark_region_as_unknown (const region *reg, uncertainty_t *uncertainty);
 642
 643   void copy_region (const region *dst_reg, const region *src_reg,
 644                     region_model_context *ctxt);
 645   tristate eval_condition (const svalue *lhs,
 646                            enum tree_code op,
 647                            const svalue *rhs) const;
 648   tristate eval_condition_without_cm (const svalue *lhs,
 649                                       enum tree_code op,
 650                                       const svalue *rhs) const;
 651   tristate compare_initial_and_pointer (const initial_svalue *init,
 652                                         const region_svalue *ptr) const;
 653   tristate eval_condition (tree lhs,
 654                            enum tree_code op,
 655                            tree rhs,
 656                            region_model_context *ctxt);
 657   bool add_constraint (tree lhs, enum tree_code op, tree rhs,
 658                        region_model_context *ctxt);
 659   bool add_constraint (tree lhs, enum tree_code op, tree rhs,
 660                        region_model_context *ctxt,
 661                        rejected_constraint **out);
 662
 663   const region *create_region_for_heap_alloc (const svalue *size_in_bytes);
 664   const region *create_region_for_alloca (const svalue *size_in_bytes);
 665
 666   tree get_representative_tree (const svalue *sval) const;
 667   path_var
 668   get_representative_path_var (const svalue *sval,
 669                                svalue_set *visited) const;
 670   path_var
 671   get_representative_path_var (const region *reg,
 672                                svalue_set *visited) const;
 673
 674   /* For selftests.  */
 675   constraint_manager *get_constraints ()
 676   {
 677     return m_constraints;
 678   }
 679
 680   store *get_store () { return &m_store; }
 681   const store *get_store () const { return &m_store; }
 682
 683   const dynamic_extents_t &
 684   get_dynamic_extents () const
 685   {
 686     return m_dynamic_extents;
 687   }
 688   const svalue *get_dynamic_extents (const region *reg) const;
 689   void set_dynamic_extents (const region *reg,
 690                             const svalue *size_in_bytes);
 691   void unset_dynamic_extents (const region *reg);
 692
 693   region_model_manager *get_manager () const { return m_mgr; }
 694
 695   void unbind_region_and_descendents (const region *reg,
 696                                       enum poison_kind pkind);
 697
 698   bool can_merge_with_p (const region_model &other_model,
 699                          const program_point &point,
 700                          region_model *out_model) const;
 701
 702   tree get_fndecl_for_call (const gcall *call,
 703                             region_model_context *ctxt);
 704
 705   void get_ssa_name_regions_for_current_frame
 706     (auto_vec<const decl_region *> *out) const;
 707   static void append_ssa_names_cb (const region *base_reg,
 708                                    struct append_ssa_names_cb_data *data);
 709
 710   const svalue *get_store_value (const region *reg,
 711                                  region_model_context *ctxt) const;
 712
 713   bool region_exists_p (const region *reg) const;
 714
 715   void loop_replay_fixup (const region_model *dst_state);
 716
 717   const svalue *get_capacity (const region *reg) const;
 718
 719  private:
 720   const region *get_lvalue_1 (path_var pv, region_model_context *ctxt) const;
 721   const svalue *get_rvalue_1 (path_var pv, region_model_context *ctxt) const;
 722
 723   path_var
 724   get_representative_path_var_1 (const svalue *sval,
 725                                  svalue_set *visited) const;
 726   path_var
 727   get_representative_path_var_1 (const region *reg,
 728                                  svalue_set *visited) const;
 729
 730   bool add_constraint (const svalue *lhs,
 731                        enum tree_code op,
 732                        const svalue *rhs,
 733                        region_model_context *ctxt);
 734   bool add_constraints_from_binop (const svalue *outer_lhs,
 735                                    enum tree_code outer_op,
 736                                    const svalue *outer_rhs,
 737                                    bool *out,
 738                                    region_model_context *ctxt);
 739
 740   void update_for_call_superedge (const call_superedge &call_edge,
 741                                   region_model_context *ctxt);
 742   void update_for_return_superedge (const return_superedge &return_edge,
 743                                     region_model_context *ctxt);
 744   void update_for_call_summary (const callgraph_superedge &cg_sedge,
 745                                 region_model_context *ctxt);
 746   bool apply_constraints_for_gcond (const cfg_superedge &edge,
 747                                     const gcond *cond_stmt,
 748                                     region_model_context *ctxt,
 749                                     rejected_constraint **out);
 750   bool apply_constraints_for_gswitch (const switch_cfg_superedge &edge,
 751                                       const gswitch *switch_stmt,
 752                                       region_model_context *ctxt,
 753                                       rejected_constraint **out);
 754   bool apply_constraints_for_exception (const gimple *last_stmt,
 755                                         region_model_context *ctxt,
 756                                         rejected_constraint **out);
 757
 758   int poison_any_pointers_to_descendents (const region *reg,
 759                                           enum poison_kind pkind);
 760
 761   void on_top_level_param (tree param, region_model_context *ctxt);
 762
 763   bool called_from_main_p () const;
 764   const svalue *get_initial_value_for_global (const region *reg) const;
 765
 766   const svalue *check_for_poison (const svalue *sval,
 767                                   tree expr,
 768                                   region_model_context *ctxt) const;
 769
 770   void check_for_writable_region (const region* dest_reg,
 771                                   region_model_context *ctxt) const;
 772   void check_region_access (const region *reg,
 773                             enum access_direction dir,
 774                             region_model_context *ctxt) const;
 775   void check_region_for_write (const region *dest_reg,
 776                                region_model_context *ctxt) const;
 777   void check_region_for_read (const region *src_reg,
 778                               region_model_context *ctxt) const;
 779
 780   /* Storing this here to avoid passing it around everywhere.  */
 781   region_model_manager *const m_mgr;
 782
 783   store m_store;
 784
 785   constraint_manager *m_constraints; // TODO: embed, rather than dynalloc?
 786
 787   const frame_region *m_current_frame;
 788
 789   /* Map from base region to size in bytes, for tracking the sizes of
 790      dynamically-allocated regions.
 791      This is part of the region_model rather than the region to allow for
 792      memory regions to be resized (e.g. by realloc).  */
 793   dynamic_extents_t m_dynamic_extents;
 794 };
 795
 796 /* Some region_model activity could lead to warnings (e.g. attempts to use an
 797    uninitialized value).  This abstract base class encapsulates an interface
 798    for the region model to use when emitting such warnings.
 799
 800    Having this as an abstract base class allows us to support the various
 801    operations needed by program_state in the analyzer within region_model,
 802    whilst keeping them somewhat modularized.  */
 803
 804 class region_model_context
 805 {
 806  public:
 807   /* Hook for clients to store pending diagnostics.
 808      Return true if the diagnostic was stored, or false if it was deleted.  */
 809   virtual bool warn (pending_diagnostic *d) = 0;
 810
 811   /* Hook for clients to be notified when an SVAL that was reachable
 812      in a previous state is no longer live, so that clients can emit warnings
 813      about leaks.  */
 814   virtual void on_svalue_leak (const svalue *sval) = 0;
 815
 816   /* Hook for clients to be notified when the set of explicitly live
 817      svalues changes, so that they can purge state relating to dead
 818      svalues.  */
 819   virtual void on_liveness_change (const svalue_set &live_svalues,
 820                                    const region_model *model) = 0;
 821
 822   virtual logger *get_logger () = 0;
 823
 824   /* Hook for clients to be notified when the condition
 825      "LHS OP RHS" is added to the region model.
 826      This exists so that state machines can detect tests on edges,
 827      and use them to trigger sm-state transitions (e.g. transitions due
 828      to ptrs becoming known to be NULL or non-NULL, rather than just
 829      "unchecked") */
 830   virtual void on_condition (const svalue *lhs,
 831                              enum tree_code op,
 832                              const svalue *rhs) = 0;
 833
 834   /* Hooks for clients to be notified when an unknown change happens
 835      to SVAL (in response to a call to an unknown function).  */
 836   virtual void on_unknown_change (const svalue *sval, bool is_mutable) = 0;
 837
 838   /* Hooks for clients to be notified when a phi node is handled,
 839      where RHS is the pertinent argument.  */
 840   virtual void on_phi (const gphi *phi, tree rhs) = 0;
 841
 842   /* Hooks for clients to be notified when the region model doesn't
 843      know how to handle the tree code of T at LOC.  */
 844   virtual void on_unexpected_tree_code (tree t,
 845                                         const dump_location_t &loc) = 0;
 846
 847   /* Hook for clients to be notified when a function_decl escapes.  */
 848   virtual void on_escaped_function (tree fndecl) = 0;
 849
 850   virtual uncertainty_t *get_uncertainty () = 0;
 851
 852   /* Hook for clients to purge state involving SVAL.  */
 853   virtual void purge_state_involving (const svalue *sval) = 0;
 854 };
 855
 856 /* A "do nothing" subclass of region_model_context.  */
 857
 858 class noop_region_model_context : public region_model_context
 859 {
 860 public:
 861   bool warn (pending_diagnostic *) OVERRIDE { return false; }
 862   void on_svalue_leak (const svalue *) OVERRIDE {}
 863   void on_liveness_change (const svalue_set &,
 864                            const region_model *) OVERRIDE {}
 865   logger *get_logger () OVERRIDE { return NULL; }
 866   void on_condition (const svalue *lhs ATTRIBUTE_UNUSED,
 867                      enum tree_code op ATTRIBUTE_UNUSED,
 868                      const svalue *rhs ATTRIBUTE_UNUSED) OVERRIDE
 869   {
 870   }
 871   void on_unknown_change (const svalue *sval ATTRIBUTE_UNUSED,
 872                           bool is_mutable ATTRIBUTE_UNUSED) OVERRIDE
 873   {
 874   }
 875   void on_phi (const gphi *phi ATTRIBUTE_UNUSED,
 876                tree rhs ATTRIBUTE_UNUSED) OVERRIDE
 877   {
 878   }
 879   void on_unexpected_tree_code (tree, const dump_location_t &) OVERRIDE {}
 880
 881   void on_escaped_function (tree) OVERRIDE {}
 882
 883   uncertainty_t *get_uncertainty () OVERRIDE { return NULL; }
 884
 885   void purge_state_involving (const svalue *sval ATTRIBUTE_UNUSED) OVERRIDE {}
 886 };
 887
 888 /* A subclass of region_model_context for determining if operations fail
 889    e.g. "can we generate a region for the lvalue of EXPR?".  */
 890
 891 class tentative_region_model_context : public noop_region_model_context
 892 {
 893 public:
 894   tentative_region_model_context () : m_num_unexpected_codes (0) {}
 895
 896   void on_unexpected_tree_code (tree, const dump_location_t &)
 897     FINAL OVERRIDE
 898   {
 899     m_num_unexpected_codes++;
 900   }
 901
 902   bool had_errors_p () const { return m_num_unexpected_codes > 0; }
 903
 904 private:
 905   int m_num_unexpected_codes;
 906 };
 907
 908 /* A bundle of data for use when attempting to merge two region_model
 909    instances to make a third.  */
 910
 911 struct model_merger
 912 {
 913   model_merger (const region_model *model_a,
 914                 const region_model *model_b,
 915                 const program_point &point,
 916                 region_model *merged_model)
 917   : m_model_a (model_a), m_model_b (model_b),
 918     m_point (point),
 919     m_merged_model (merged_model)
 920   {
 921   }
 922
 923   void dump_to_pp (pretty_printer *pp, bool simple) const;
 924   void dump (FILE *fp, bool simple) const;
 925   void dump (bool simple) const;
 926
 927   region_model_manager *get_manager () const
 928   {
 929     return m_model_a->get_manager ();
 930   }
 931
 932   const region_model *m_model_a;
 933   const region_model *m_model_b;
 934   const program_point &m_point;
 935   region_model *m_merged_model;
 936 };
 937
 938 /* A record that can (optionally) be written out when
 939    region_model::add_constraint fails.  */
 940
 941 struct rejected_constraint
 942 {
 943   rejected_constraint (const region_model &model,
 944                      tree lhs, enum tree_code op, tree rhs)
 945   : m_model (model), m_lhs (lhs), m_op (op), m_rhs (rhs)
 946   {}
 947
 948   void dump_to_pp (pretty_printer *pp) const;
 949
 950   region_model m_model;
 951   tree m_lhs;
 952   enum tree_code m_op;
 953   tree m_rhs;
 954 };
 955
 956 /* A bundle of state.  */
 957
 958 class engine
 959 {
 960 public:
 961   region_model_manager *get_model_manager () { return &m_mgr; }
 962
 963   void log_stats (logger *logger) const;
 964
 965 private:
 966   region_model_manager m_mgr;
 967
 968 };
 969
 970 } // namespace ana
 971
 972 extern void debug (const region_model &rmodel);
 973
 974 namespace ana {
 975
 976 #if CHECKING_P
 977
 978 namespace selftest {
 979
 980 using namespace ::selftest;
 981
 982 /* An implementation of region_model_context for use in selftests, which
 983    stores any pending_diagnostic instances passed to it.  */
 984
 985 class test_region_model_context : public noop_region_model_context
 986 {
 987 public:
 988   bool warn (pending_diagnostic *d) FINAL OVERRIDE
 989   {
 990     m_diagnostics.safe_push (d);
 991     return true;
 992   }
 993
 994   unsigned get_num_diagnostics () const { return m_diagnostics.length (); }
 995
 996   void on_unexpected_tree_code (tree t, const dump_location_t &)
 997     FINAL OVERRIDE
 998   {
 999     internal_error ("unhandled tree code: %qs",
1000                     get_tree_code_name (TREE_CODE (t)));
1001   }
1002
1003 private:
1004   /* Implicitly delete any diagnostics in the dtor.  */
1005   auto_delete_vec<pending_diagnostic> m_diagnostics;
1006 };
1007
1008 /* Attempt to add the constraint (LHS OP RHS) to MODEL.
1009    Verify that MODEL remains satisfiable.  */
1010
1011 #define ADD_SAT_CONSTRAINT(MODEL, LHS, OP, RHS) \
1012   SELFTEST_BEGIN_STMT                                   \
1013     bool sat = (MODEL).add_constraint (LHS, OP, RHS, NULL);     \
1014     ASSERT_TRUE (sat);                                  \
1015   SELFTEST_END_STMT
1016
1017 /* Attempt to add the constraint (LHS OP RHS) to MODEL.
1018    Verify that the result is not satisfiable.  */
1019
1020 #define ADD_UNSAT_CONSTRAINT(MODEL, LHS, OP, RHS)       \
1021   SELFTEST_BEGIN_STMT                                   \
1022     bool sat = (MODEL).add_constraint (LHS, OP, RHS, NULL);     \
1023     ASSERT_FALSE (sat);                         \
1024   SELFTEST_END_STMT
1025
1026 /* Implementation detail of the ASSERT_CONDITION_* macros.  */
1027
1028 void assert_condition (const location &loc,
1029                        region_model &model,
1030                        const svalue *lhs, tree_code op, const svalue *rhs,
1031                        tristate expected);
1032
1033 void assert_condition (const location &loc,
1034                        region_model &model,
1035                        tree lhs, tree_code op, tree rhs,
1036                        tristate expected);
1037
1038 /* Assert that REGION_MODEL evaluates the condition "LHS OP RHS"
1039    as "true".  */
1040
1041 #define ASSERT_CONDITION_TRUE(REGION_MODEL, LHS, OP, RHS) \
1042   SELFTEST_BEGIN_STMT                                                   \
1043   assert_condition (SELFTEST_LOCATION, REGION_MODEL, LHS, OP, RHS,      \
1044                     tristate (tristate::TS_TRUE));              \
1045   SELFTEST_END_STMT
1046
1047 /* Assert that REGION_MODEL evaluates the condition "LHS OP RHS"
1048    as "false".  */
1049
1050 #define ASSERT_CONDITION_FALSE(REGION_MODEL, LHS, OP, RHS) \
1051   SELFTEST_BEGIN_STMT                                                   \
1052   assert_condition (SELFTEST_LOCATION, REGION_MODEL, LHS, OP, RHS,      \
1053                     tristate (tristate::TS_FALSE));             \
1054   SELFTEST_END_STMT
1055
1056 /* Assert that REGION_MODEL evaluates the condition "LHS OP RHS"
1057    as "unknown".  */
1058
1059 #define ASSERT_CONDITION_UNKNOWN(REGION_MODEL, LHS, OP, RHS) \
1060   SELFTEST_BEGIN_STMT                                                   \
1061   assert_condition (SELFTEST_LOCATION, REGION_MODEL, LHS, OP, RHS,      \
1062                     tristate (tristate::TS_UNKNOWN));           \
1063   SELFTEST_END_STMT
1064
1065 } /* end of namespace selftest.  */
1066
1067 #endif /* #if CHECKING_P */
1068
1069 } // namespace ana
1070
1071 #endif /* GCC_ANALYZER_REGION_MODEL_H */