gcc/ipa-icf.h

   1 /* Interprocedural semantic function equality pass
   2    Copyright (C) 2014 Free Software Foundation, Inc.
   3
   4    Contributed by Jan Hubicka <hubicka@ucw.cz> and Martin Liska <mliska@suse.cz>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 namespace ipa_icf {
  23 class sem_item;
  24
  25 /* Congruence class encompasses a collection of either functions or
  26    read-only variables. These items are considered to be equivalent
  27    if not proved the oposite.  */
  28 class congruence_class
  29 {
  30 public:
  31   /* Congruence class constructor for a new class with _ID.  */
  32   congruence_class (unsigned int _id): in_worklist (false), id(_id)
  33   {
  34   }
  35
  36   /* Destructor.  */
  37   ~congruence_class ()
  38   {
  39   }
  40
  41   /* Dump function prints all class members to a FILE with an INDENT.  */
  42   void dump (FILE *file, unsigned int indent = 0) const;
  43
  44   /* Returns true if there's a member that is used from another group.  */
  45   bool is_class_used (void);
  46
  47   /* Flag is used in case we want to remove a class from worklist and
  48      delete operation is quite expensive for
  49      the data structure (linked list).  */
  50   bool in_worklist;
  51
  52   /* Vector of all group members.  */
  53   auto_vec <sem_item *> members;
  54
  55   /* Global unique class identifier.  */
  56   unsigned int id;
  57 };
  58
  59 /* Semantic item type enum.  */
  60 enum sem_item_type
  61 {
  62   FUNC,
  63   VAR
  64 };
  65
  66 /* Semantic item usage pair.  */
  67 class sem_usage_pair
  68 {
  69 public:
  70   /* Constructor for key value pair, where _ITEM is key and _INDEX is a target.  */
  71   sem_usage_pair (sem_item *_item, unsigned int _index);
  72
  73   /* Target semantic item where an item is used.  */
  74   sem_item *item;
  75
  76   /* Index of usage of such an item.  */
  77   unsigned int index;
  78 };
  79
  80 /* Semantic item is a base class that encapsulates all shared functionality
  81    for both semantic function and variable items.  */
  82 class sem_item
  83 {
  84 public:
  85   /* Semantic item constructor for a node of _TYPE, where STACK is used
  86      for bitmap memory allocation.  */
  87   sem_item (sem_item_type _type, bitmap_obstack *stack);
  88
  89   /* Semantic item constructor for a node of _TYPE, where STACK is used
  90      for bitmap memory allocation. The item is based on symtab node _NODE
  91      with computed _HASH.  */
  92   sem_item (sem_item_type _type, symtab_node *_node, hashval_t _hash,
  93             bitmap_obstack *stack);
  94
  95   virtual ~sem_item ();
  96
  97   /* Dump function for debugging purpose.  */
  98   DEBUG_FUNCTION void dump (void);
  99
 100   /* Initialize semantic item by info reachable during LTO WPA phase.  */
 101   virtual void init_wpa (void) = 0;
 102
 103   /* Semantic item initialization function.  */
 104   virtual void init (void) = 0;
 105
 106   /* Add reference to a semantic TARGET.  */
 107   void add_reference (sem_item *target);
 108
 109   /* Gets symbol name of the item.  */
 110   const char *name (void)
 111   {
 112     return node->name ();
 113   }
 114
 115   /* Gets assembler name of the item.  */
 116   const char *asm_name (void)
 117   {
 118     return node->asm_name ();
 119   }
 120
 121   /* Fast equality function based on knowledge known in WPA.  */
 122   virtual bool equals_wpa (sem_item *item,
 123                            hash_map <symtab_node *, sem_item *> &ignored_nodes) = 0;
 124
 125   /* Returns true if the item equals to ITEM given as arguemnt.  */
 126   virtual bool equals (sem_item *item,
 127                        hash_map <symtab_node *, sem_item *> &ignored_nodes) = 0;
 128
 129   /* References independent hash function.  */
 130   virtual hashval_t get_hash (void) = 0;
 131
 132   /* Merges instance with an ALIAS_ITEM, where alias, thunk or redirection can
 133      be applied.  */
 134   virtual bool merge (sem_item *alias_item) = 0;
 135
 136   /* Dump symbol to FILE.  */
 137   virtual void dump_to_file (FILE *file) = 0;
 138
 139   /* Return base tree that can be used for compatible_types_p and
 140      contains_polymorphic_type_p comparison.  */
 141   static bool get_base_types (tree *t1, tree *t2);
 142
 143   /* Return true if target supports alias symbols.  */
 144   bool target_supports_symbol_aliases_p (void);
 145
 146   /* Item type.  */
 147   sem_item_type type;
 148
 149   /* Symtab node.  */
 150   symtab_node *node;
 151
 152   /* Declaration tree node.  */
 153   tree decl;
 154
 155   /* Semantic references used that generate congruence groups.  */
 156   vec <sem_item *> refs;
 157
 158   /* Pointer to a congruence class the item belongs to.  */
 159   congruence_class *cls;
 160
 161   /* Index of the item in a class belonging to.  */
 162   unsigned int index_in_class;
 163
 164   /* List of semantic items where the instance is used.  */
 165   vec <sem_usage_pair *> usages;
 166
 167   /* A bitmap with indices of all classes referencing this item.  */
 168   bitmap usage_index_bitmap;
 169
 170   /* List of tree references (either FUNC_DECL or VAR_DECL).  */
 171   vec <tree> tree_refs;
 172
 173   /* A set with symbol table references.  */
 174   hash_set <symtab_node *> refs_set;
 175
 176 protected:
 177   /* Cached, once calculated hash for the item.  */
 178   hashval_t hash;
 179
 180 private:
 181   /* Initialize internal data structures. Bitmap STACK is used for
 182      bitmap memory allocation process.  */
 183   void setup (bitmap_obstack *stack);
 184 }; // class sem_item
 185
 186 class sem_function: public sem_item
 187 {
 188 public:
 189   /* Semantic function constructor that uses STACK as bitmap memory stack.  */
 190   sem_function (bitmap_obstack *stack);
 191
 192   /*  Constructor based on callgraph node _NODE with computed hash _HASH.
 193       Bitmap STACK is used for memory allocation.  */
 194   sem_function (cgraph_node *_node, hashval_t _hash, bitmap_obstack *stack);
 195
 196   ~sem_function ();
 197
 198   inline virtual void init_wpa (void)
 199   {
 200     parse_tree_args ();
 201   }
 202
 203   virtual void init (void);
 204   virtual bool equals_wpa (sem_item *item,
 205                            hash_map <symtab_node *, sem_item *> &ignored_nodes);
 206   virtual hashval_t get_hash (void);
 207   virtual bool equals (sem_item *item,
 208                        hash_map <symtab_node *, sem_item *> &ignored_nodes);
 209   virtual bool merge (sem_item *alias_item);
 210
 211   /* Dump symbol to FILE.  */
 212   virtual void dump_to_file (FILE *file)
 213   {
 214     gcc_assert (file);
 215     dump_function_to_file (decl, file, TDF_DETAILS);
 216   }
 217
 218   /* Parses function arguments and result type.  */
 219   void parse_tree_args (void);
 220
 221   /* Returns cgraph_node.  */
 222   inline cgraph_node *get_node (void)
 223   {
 224     return dyn_cast <cgraph_node *> (node);
 225   }
 226
 227   /* Improve accumulated hash for HSTATE based on a gimple statement STMT.  */
 228   void hash_stmt (inchash::hash *inchash, gimple stmt);
 229
 230   /* Return true if polymorphic comparison must be processed.  */
 231   bool compare_polymorphic_p (void);
 232
 233   /* For a given call graph NODE, the function constructs new
 234      semantic function item.  */
 235   static sem_function *parse (cgraph_node *node, bitmap_obstack *stack);
 236
 237   /* Exception handling region tree.  */
 238   eh_region region_tree;
 239
 240   /* Result type tree node.  */
 241   tree result_type;
 242
 243   /* Array of argument tree types.  */
 244   vec <tree> arg_types;
 245
 246   /* Number of function arguments.  */
 247   unsigned int arg_count;
 248
 249   /* Total amount of edges in the function.  */
 250   unsigned int edge_count;
 251
 252   /* Vector of sizes of all basic blocks.  */
 253   vec <unsigned int> bb_sizes;
 254
 255   /* Control flow graph checksum.  */
 256   hashval_t cfg_checksum;
 257
 258   /* GIMPLE codes hash value.  */
 259   hashval_t gcode_hash;
 260
 261   /* Total number of SSA names used in the function.  */
 262   unsigned ssa_names_size;
 263
 264   /* Array of structures for all basic blocks.  */
 265   vec <ipa_icf_gimple::sem_bb *> bb_sorted;
 266
 267 private:
 268   /* Calculates hash value based on a BASIC_BLOCK.  */
 269   hashval_t get_bb_hash (const ipa_icf_gimple::sem_bb *basic_block);
 270
 271   /* For given basic blocks BB1 and BB2 (from functions FUNC1 and FUNC),
 272      true value is returned if phi nodes are semantically
 273      equivalent in these blocks .  */
 274   bool compare_phi_node (basic_block bb1, basic_block bb2);
 275
 276   /* Basic blocks dictionary BB_DICT returns true if SOURCE index BB
 277      corresponds to TARGET.  */
 278   bool bb_dict_test (auto_vec<int> bb_dict, int source, int target);
 279
 280   /* Iterates all tree types in T1 and T2 and returns true if all types
 281      are compatible. If COMPARE_POLYMORPHIC is set to true,
 282      more strict comparison is executed.  */
 283   bool compare_type_list (tree t1, tree t2, bool compare_polymorphic);
 284
 285   /* If cgraph edges E1 and E2 are indirect calls, verify that
 286      ICF flags are the same.  */
 287   bool compare_edge_flags (cgraph_edge *e1, cgraph_edge *e2);
 288
 289   /* For a given symbol table nodes N1 and N2, we check that FUNCTION_DECLs
 290      point to a same function. Comparison can be skipped if IGNORED_NODES
 291      contains these nodes.  */
 292   bool compare_cgraph_references (hash_map <symtab_node *, sem_item *>
 293                                   &ignored_nodes,
 294                                   symtab_node *n1, symtab_node *n2);
 295
 296   /* Processes function equality comparison.  */
 297   bool equals_private (sem_item *item,
 298                        hash_map <symtab_node *, sem_item *> &ignored_nodes);
 299
 300   /* Returns true if tree T can be compared as a handled component.  */
 301   static bool icf_handled_component_p (tree t);
 302
 303   /* Function checker stores binding between functions.   */
 304   ipa_icf_gimple::func_checker *m_checker;
 305
 306   /* COMPARED_FUNC is a function that we compare to.  */
 307   sem_function *m_compared_func;
 308 }; // class sem_function
 309
 310 class sem_variable: public sem_item
 311 {
 312 public:
 313   /* Semantic variable constructor that uses STACK as bitmap memory stack.  */
 314   sem_variable (bitmap_obstack *stack);
 315
 316   /*  Constructor based on callgraph node _NODE with computed hash _HASH.
 317       Bitmap STACK is used for memory allocation.  */
 318
 319   sem_variable (varpool_node *_node, hashval_t _hash, bitmap_obstack *stack);
 320
 321   inline virtual void init_wpa (void) {}
 322
 323   /* Semantic variable initialization function.  */
 324   inline virtual void init (void)
 325   {
 326     decl = get_node ()->decl;
 327     ctor = ctor_for_folding (decl);
 328   }
 329
 330   virtual hashval_t get_hash (void);
 331   virtual bool merge (sem_item *alias_item);
 332   virtual void dump_to_file (FILE *file);
 333   virtual bool equals (sem_item *item,
 334                        hash_map <symtab_node *, sem_item *> &ignored_nodes);
 335
 336   /* Fast equality variable based on knowledge known in WPA.  */
 337   inline virtual bool equals_wpa (sem_item *item,
 338                                   hash_map <symtab_node *, sem_item *> & ARG_UNUSED(ignored_nodes))
 339   {
 340     gcc_assert (item->type == VAR);
 341     return true;
 342   }
 343
 344   /* Returns varpool_node.  */
 345   inline varpool_node *get_node (void)
 346   {
 347     return dyn_cast <varpool_node *> (node);
 348   }
 349
 350   /* Parser function that visits a varpool NODE.  */
 351   static sem_variable *parse (varpool_node *node, bitmap_obstack *stack);
 352
 353   /* Variable constructor.  */
 354   tree ctor;
 355
 356 private:
 357   /* Iterates though a constructor and identifies tree references
 358      we are interested in semantic function equality.  */
 359   void parse_tree_refs (tree t);
 360
 361   /* Compares trees T1 and T2 for semantic equality.  */
 362   static bool equals (tree t1, tree t2);
 363
 364   /* Compare that symbol sections are either NULL or have same name.  */
 365   bool compare_sections (sem_variable *alias);
 366
 367 }; // class sem_variable
 368
 369 class sem_item_optimizer;
 370
 371 struct congruence_class_group
 372 {
 373   hashval_t hash;
 374   sem_item_type type;
 375   vec <congruence_class *> classes;
 376 };
 377
 378 /* Congruence class set structure.  */
 379 struct congruence_class_group_hash: typed_noop_remove <congruence_class_group>
 380 {
 381   typedef congruence_class_group value_type;
 382   typedef congruence_class_group compare_type;
 383
 384   static inline hashval_t hash (const value_type *item)
 385   {
 386     return item->hash;
 387   }
 388
 389   static inline int equal (const value_type *item1, const compare_type *item2)
 390   {
 391     return item1->hash == item2->hash && item1->type == item2->type;
 392   }
 393 };
 394
 395 struct traverse_split_pair
 396 {
 397   sem_item_optimizer *optimizer;
 398   class congruence_class *cls;
 399 };
 400
 401 /* Semantic item optimizer includes all top-level logic
 402    related to semantic equality comparison.  */
 403 class sem_item_optimizer
 404 {
 405 public:
 406   sem_item_optimizer ();
 407   ~sem_item_optimizer ();
 408
 409   /* Function responsible for visiting all potential functions and
 410      read-only variables that can be merged.  */
 411   void parse_funcs_and_vars (void);
 412
 413   /* Optimizer entry point.  */
 414   void execute (void);
 415
 416   /* Dump function. */
 417   void dump (void);
 418
 419   /* Verify congruence classes if checking is enabled.  */
 420   void verify_classes (void);
 421
 422   /* Write IPA ICF summary for symbols.  */
 423   void write_summary (void);
 424
 425   /* Read IPA IPA ICF summary for symbols.  */
 426   void read_summary (void);
 427
 428   /* Callgraph removal hook called for a NODE with a custom DATA.  */
 429   static void cgraph_removal_hook (cgraph_node *node, void *data);
 430
 431   /* Varpool removal hook called for a NODE with a custom DATA.  */
 432   static void varpool_removal_hook (varpool_node *node, void *data);
 433
 434   /* Worklist of congruence classes that can potentially
 435      refine classes of congruence.  */
 436   std::list<congruence_class *> worklist;
 437
 438   /* Remove semantic ITEM and release memory.  */
 439   void remove_item (sem_item *item);
 440
 441   /* Remove symtab NODE triggered by symtab removal hooks.  */
 442   void remove_symtab_node (symtab_node *node);
 443
 444   /* Register callgraph and varpool hooks.  */
 445   void register_hooks (void);
 446
 447   /* Unregister callgraph and varpool hooks.  */
 448   void unregister_hooks (void);
 449
 450   /* Adds a CLS to hashtable associated by hash value.  */
 451   void add_class (congruence_class *cls);
 452
 453   /* Gets a congruence class group based on given HASH value and TYPE.  */
 454   congruence_class_group *get_group_by_hash (hashval_t hash,
 455       sem_item_type type);
 456
 457 private:
 458
 459   /* Congruence classes are built by hash value.  */
 460   void build_hash_based_classes (void);
 461
 462   /* Semantic items in classes having more than one element and initialized.
 463      In case of WPA, we load function body.  */
 464   void parse_nonsingleton_classes (void);
 465
 466   /* Equality function for semantic items is used to subdivide existing
 467      classes. If IN_WPA, fast equality function is invoked.  */
 468   void subdivide_classes_by_equality (bool in_wpa = false);
 469
 470   /* Debug function prints all informations about congruence classes.  */
 471   void dump_cong_classes (void);
 472
 473   /* Build references according to call graph.  */
 474   void build_graph (void);
 475
 476   /* Iterative congruence reduction function.  */
 477   void process_cong_reduction (void);
 478
 479   /* After reduction is done, we can declare all items in a group
 480      to be equal. PREV_CLASS_COUNT is start number of classes
 481      before reduction.  */
 482   void merge_classes (unsigned int prev_class_count);
 483
 484   /* Adds a newly created congruence class CLS to worklist.  */
 485   void worklist_push (congruence_class *cls);
 486
 487   /* Pops a class from worklist. */
 488   congruence_class *worklist_pop ();
 489
 490   /* Every usage of a congruence class CLS is a candidate that can split the
 491      collection of classes. Bitmap stack BMSTACK is used for bitmap
 492      allocation.  */
 493   void do_congruence_step (congruence_class *cls);
 494
 495   /* Tests if a class CLS used as INDEXth splits any congruence classes.
 496      Bitmap stack BMSTACK is used for bitmap allocation.  */
 497   void do_congruence_step_for_index (congruence_class *cls, unsigned int index);
 498
 499   /* Makes pairing between a congruence class CLS and semantic ITEM.  */
 500   static void add_item_to_class (congruence_class *cls, sem_item *item);
 501
 502   /* Disposes split map traverse function. CLS is congruence
 503      class, BSLOT is bitmap slot we want to release. DATA is mandatory,
 504      but unused argument.  */
 505   static bool release_split_map (congruence_class * const &cls, bitmap const &b,
 506                                  traverse_split_pair *pair);
 507
 508   /* Process split operation for a cognruence class CLS,
 509      where bitmap B splits congruence class members. DATA is used
 510      as argument of split pair.  */
 511   static bool traverse_congruence_split (congruence_class * const &cls,
 512                                          bitmap const &b,
 513                                          traverse_split_pair *pair);
 514
 515   /* Reads a section from LTO stream file FILE_DATA. Input block for DATA
 516      contains LEN bytes.  */
 517   void read_section (lto_file_decl_data *file_data, const char *data,
 518                      size_t len);
 519
 520   /* Removes all callgraph and varpool nodes that are marked by symtab
 521      as deleted.  */
 522   void filter_removed_items (void);
 523
 524   /* Vector of semantic items.  */
 525   vec <sem_item *> m_items;
 526
 527   /* A set containing all items removed by hooks.  */
 528   hash_set <symtab_node *> m_removed_items_set;
 529
 530   /* Hashtable of congruence classes */
 531   hash_table <congruence_class_group_hash> m_classes;
 532
 533   /* Count of congruence classes.  */
 534   unsigned int m_classes_count;
 535
 536   /* Map data structure maps symtab nodes to semantic items.  */
 537   hash_map <symtab_node *, sem_item *> m_symtab_node_map;
 538
 539   /* Set to true if a splitter class is removed.  */
 540   bool splitter_class_removed;
 541
 542   /* Global unique class id counter.  */
 543   static unsigned int class_id;
 544
 545   /* Callgraph node removal hook holder.  */
 546   cgraph_node_hook_list *m_cgraph_node_hooks;
 547
 548   /* Varpool node removal hook holder.  */
 549   varpool_node_hook_list *m_varpool_node_hooks;
 550
 551   /* Bitmap stack.  */
 552   bitmap_obstack m_bmstack;
 553 }; // class sem_item_optimizer
 554
 555 } // ipa_icf namespace