1 /* Interprocedural semantic function equality pass 2 Copyright (C) 2014-2018 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. */ congruence_class(unsigned int _id)32 congruence_class (unsigned int _id): in_worklist (false), id(_id) 33 { 34 } 35 36 /* Destructor. */ ~congruence_class()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 /* Class is container for address references for a symtab_node. */ 67 68 class symbol_compare_collection 69 { 70 public: 71 /* Constructor. */ 72 symbol_compare_collection (symtab_node *node); 73 74 /* Destructor. */ ~symbol_compare_collection()75 ~symbol_compare_collection () 76 { 77 m_references.release (); 78 m_interposables.release (); 79 } 80 81 /* Vector of address references. */ 82 vec<symtab_node *> m_references; 83 84 /* Vector of interposable references. */ 85 vec<symtab_node *> m_interposables; 86 }; 87 88 /* Hash traits for symbol_compare_collection map. */ 89 90 struct symbol_compare_hash : nofree_ptr_hash <symbol_compare_collection> 91 { 92 static hashval_t hashsymbol_compare_hash93 hash (value_type v) 94 { 95 inchash::hash hstate; 96 hstate.add_int (v->m_references.length ()); 97 98 for (unsigned i = 0; i < v->m_references.length (); i++) 99 hstate.add_int (v->m_references[i]->ultimate_alias_target ()->order); 100 101 hstate.add_int (v->m_interposables.length ()); 102 103 for (unsigned i = 0; i < v->m_interposables.length (); i++) 104 hstate.add_int (v->m_interposables[i]->ultimate_alias_target ()->order); 105 106 return hstate.end (); 107 } 108 109 static bool equalsymbol_compare_hash110 equal (value_type a, value_type b) 111 { 112 if (a->m_references.length () != b->m_references.length () 113 || a->m_interposables.length () != b->m_interposables.length ()) 114 return false; 115 116 for (unsigned i = 0; i < a->m_references.length (); i++) 117 if (a->m_references[i]->equal_address_to (b->m_references[i]) != 1) 118 return false; 119 120 for (unsigned i = 0; i < a->m_interposables.length (); i++) 121 if (!a->m_interposables[i]->semantically_equivalent_p 122 (b->m_interposables[i])) 123 return false; 124 125 return true; 126 } 127 }; 128 129 130 /* Semantic item usage pair. */ 131 class sem_usage_pair 132 { 133 public: 134 /* Constructor for key value pair, where _ITEM is key and _INDEX is a target. */ 135 sem_usage_pair (sem_item *_item, unsigned int _index); 136 137 /* Target semantic item where an item is used. */ 138 sem_item *item; 139 140 /* Index of usage of such an item. */ 141 unsigned int index; 142 }; 143 144 typedef std::pair<symtab_node *, symtab_node *> symtab_pair; 145 146 /* Semantic item is a base class that encapsulates all shared functionality 147 for both semantic function and variable items. */ 148 class sem_item 149 { 150 public: 151 /* Semantic item constructor for a node of _TYPE, where STACK is used 152 for bitmap memory allocation. */ 153 sem_item (sem_item_type _type, bitmap_obstack *stack); 154 155 /* Semantic item constructor for a node of _TYPE, where STACK is used 156 for bitmap memory allocation. The item is based on symtab node _NODE. */ 157 sem_item (sem_item_type _type, symtab_node *_node, bitmap_obstack *stack); 158 159 virtual ~sem_item (); 160 161 /* Dump function for debugging purpose. */ 162 DEBUG_FUNCTION void dump (void); 163 164 /* Initialize semantic item by info reachable during LTO WPA phase. */ 165 virtual void init_wpa (void) = 0; 166 167 /* Semantic item initialization function. */ 168 virtual void init (void) = 0; 169 170 /* Add reference to a semantic TARGET. */ 171 void add_reference (sem_item *target); 172 173 /* Fast equality function based on knowledge known in WPA. */ 174 virtual bool equals_wpa (sem_item *item, 175 hash_map <symtab_node *, sem_item *> &ignored_nodes) = 0; 176 177 /* Returns true if the item equals to ITEM given as arguemnt. */ 178 virtual bool equals (sem_item *item, 179 hash_map <symtab_node *, sem_item *> &ignored_nodes) = 0; 180 181 /* References independent hash function. */ 182 virtual hashval_t get_hash (void) = 0; 183 184 /* Set new hash value of the item. */ 185 void set_hash (hashval_t hash); 186 187 /* Merges instance with an ALIAS_ITEM, where alias, thunk or redirection can 188 be applied. */ 189 virtual bool merge (sem_item *alias_item) = 0; 190 191 /* Dump symbol to FILE. */ 192 virtual void dump_to_file (FILE *file) = 0; 193 194 /* Update hash by address sensitive references. */ 195 void update_hash_by_addr_refs (hash_map <symtab_node *, 196 sem_item *> &m_symtab_node_map); 197 198 /* Update hash by computed local hash values taken from different 199 semantic items. */ 200 void update_hash_by_local_refs (hash_map <symtab_node *, 201 sem_item *> &m_symtab_node_map); 202 203 /* Return base tree that can be used for compatible_types_p and 204 contains_polymorphic_type_p comparison. */ 205 static bool get_base_types (tree *t1, tree *t2); 206 207 /* Return true if target supports alias symbols. */ 208 bool target_supports_symbol_aliases_p (void); 209 210 /* Item type. */ 211 sem_item_type type; 212 213 /* Symtab node. */ 214 symtab_node *node; 215 216 /* Declaration tree node. */ 217 tree decl; 218 219 /* Semantic references used that generate congruence groups. */ 220 vec <sem_item *> refs; 221 222 /* Pointer to a congruence class the item belongs to. */ 223 congruence_class *cls; 224 225 /* Index of the item in a class belonging to. */ 226 unsigned int index_in_class; 227 228 /* List of semantic items where the instance is used. */ 229 vec <sem_usage_pair *> usages; 230 231 /* A bitmap with indices of all classes referencing this item. */ 232 bitmap usage_index_bitmap; 233 234 /* List of tree references (either FUNC_DECL or VAR_DECL). */ 235 vec <tree> tree_refs; 236 237 /* A set with symbol table references. */ 238 hash_set <symtab_node *> refs_set; 239 240 /* Temporary hash used where hash values of references are added. */ 241 hashval_t global_hash; 242 protected: 243 /* Cached, once calculated hash for the item. */ 244 245 /* Accumulate to HSTATE a hash of expression EXP. */ 246 static void add_expr (const_tree exp, inchash::hash &hstate); 247 /* Accumulate to HSTATE a hash of type T. */ 248 static void add_type (const_tree t, inchash::hash &hstate); 249 250 /* Compare properties of symbol that does not affect semantics of symbol 251 itself but affects semantics of its references. 252 If ADDRESS is true, do extra checking needed for IPA_REF_ADDR. */ 253 static bool compare_referenced_symbol_properties (symtab_node *used_by, 254 symtab_node *n1, 255 symtab_node *n2, 256 bool address); 257 258 /* Compare two attribute lists. */ 259 static bool compare_attributes (const_tree list1, const_tree list2); 260 261 /* Hash properties compared by compare_referenced_symbol_properties. */ 262 void hash_referenced_symbol_properties (symtab_node *ref, 263 inchash::hash &hstate, 264 bool address); 265 266 /* For a given symbol table nodes N1 and N2, we check that FUNCTION_DECLs 267 point to a same function. Comparison can be skipped if IGNORED_NODES 268 contains these nodes. ADDRESS indicate if address is taken. */ 269 bool compare_symbol_references (hash_map <symtab_node *, sem_item *> 270 &ignored_nodes, 271 symtab_node *n1, symtab_node *n2, 272 bool address); 273 protected: 274 /* Hash of item. */ 275 hashval_t m_hash; 276 277 /* Indicated whether a hash value has been set or not. */ 278 bool m_hash_set; 279 280 private: 281 /* Initialize internal data structures. Bitmap STACK is used for 282 bitmap memory allocation process. */ 283 void setup (bitmap_obstack *stack); 284 }; // class sem_item 285 286 class sem_function: public sem_item 287 { 288 public: 289 /* Semantic function constructor that uses STACK as bitmap memory stack. */ 290 sem_function (bitmap_obstack *stack); 291 292 /* Constructor based on callgraph node _NODE. 293 Bitmap STACK is used for memory allocation. */ 294 sem_function (cgraph_node *_node, bitmap_obstack *stack); 295 296 ~sem_function (); 297 init_wpa(void)298 inline virtual void init_wpa (void) 299 { 300 } 301 302 virtual void init (void); 303 virtual bool equals_wpa (sem_item *item, 304 hash_map <symtab_node *, sem_item *> &ignored_nodes); 305 virtual hashval_t get_hash (void); 306 virtual bool equals (sem_item *item, 307 hash_map <symtab_node *, sem_item *> &ignored_nodes); 308 virtual bool merge (sem_item *alias_item); 309 310 /* Dump symbol to FILE. */ dump_to_file(FILE * file)311 virtual void dump_to_file (FILE *file) 312 { 313 gcc_assert (file); 314 dump_function_to_file (decl, file, TDF_DETAILS); 315 } 316 317 /* Returns cgraph_node. */ get_node(void)318 inline cgraph_node *get_node (void) 319 { 320 return dyn_cast <cgraph_node *> (node); 321 } 322 323 /* Improve accumulated hash for HSTATE based on a gimple statement STMT. */ 324 void hash_stmt (gimple *stmt, inchash::hash &inchash); 325 326 /* Return true if polymorphic comparison must be processed. */ 327 bool compare_polymorphic_p (void); 328 329 /* For a given call graph NODE, the function constructs new 330 semantic function item. */ 331 static sem_function *parse (cgraph_node *node, bitmap_obstack *stack); 332 333 /* Perform additional checks needed to match types of used function 334 paramters. */ 335 bool compatible_parm_types_p (tree, tree); 336 337 /* Exception handling region tree. */ 338 eh_region region_tree; 339 340 /* Number of function arguments. */ 341 unsigned int arg_count; 342 343 /* Total amount of edges in the function. */ 344 unsigned int edge_count; 345 346 /* Vector of sizes of all basic blocks. */ 347 vec <unsigned int> bb_sizes; 348 349 /* Control flow graph checksum. */ 350 hashval_t cfg_checksum; 351 352 /* GIMPLE codes hash value. */ 353 hashval_t gcode_hash; 354 355 /* Total number of SSA names used in the function. */ 356 unsigned ssa_names_size; 357 358 /* Array of structures for all basic blocks. */ 359 vec <ipa_icf_gimple::sem_bb *> bb_sorted; 360 361 /* Return true if parameter I may be used. */ 362 bool param_used_p (unsigned int i); 363 364 private: 365 /* Calculates hash value based on a BASIC_BLOCK. */ 366 hashval_t get_bb_hash (const ipa_icf_gimple::sem_bb *basic_block); 367 368 /* For given basic blocks BB1 and BB2 (from functions FUNC1 and FUNC), 369 true value is returned if phi nodes are semantically 370 equivalent in these blocks . */ 371 bool compare_phi_node (basic_block bb1, basic_block bb2); 372 373 /* Basic blocks dictionary BB_DICT returns true if SOURCE index BB 374 corresponds to TARGET. */ 375 bool bb_dict_test (vec<int> *bb_dict, int source, int target); 376 377 /* If cgraph edges E1 and E2 are indirect calls, verify that 378 ICF flags are the same. */ 379 bool compare_edge_flags (cgraph_edge *e1, cgraph_edge *e2); 380 381 /* Processes function equality comparison. */ 382 bool equals_private (sem_item *item); 383 384 /* Returns true if tree T can be compared as a handled component. */ 385 static bool icf_handled_component_p (tree t); 386 387 /* Function checker stores binding between functions. */ 388 ipa_icf_gimple::func_checker *m_checker; 389 390 /* COMPARED_FUNC is a function that we compare to. */ 391 sem_function *m_compared_func; 392 }; // class sem_function 393 394 class sem_variable: public sem_item 395 { 396 public: 397 /* Semantic variable constructor that uses STACK as bitmap memory stack. */ 398 sem_variable (bitmap_obstack *stack); 399 400 /* Constructor based on callgraph node _NODE. 401 Bitmap STACK is used for memory allocation. */ 402 403 sem_variable (varpool_node *_node, bitmap_obstack *stack); 404 init_wpa(void)405 inline virtual void init_wpa (void) {} 406 407 /* Semantic variable initialization function. */ init(void)408 inline virtual void init (void) 409 { 410 decl = get_node ()->decl; 411 } 412 413 virtual hashval_t get_hash (void); 414 virtual bool merge (sem_item *alias_item); 415 virtual void dump_to_file (FILE *file); 416 virtual bool equals (sem_item *item, 417 hash_map <symtab_node *, sem_item *> &ignored_nodes); 418 419 /* Fast equality variable based on knowledge known in WPA. */ 420 virtual bool equals_wpa (sem_item *item, 421 hash_map <symtab_node *, sem_item *> &ignored_nodes); 422 423 /* Returns varpool_node. */ get_node(void)424 inline varpool_node *get_node (void) 425 { 426 return dyn_cast <varpool_node *> (node); 427 } 428 429 /* Parser function that visits a varpool NODE. */ 430 static sem_variable *parse (varpool_node *node, bitmap_obstack *stack); 431 432 private: 433 /* Compares trees T1 and T2 for semantic equality. */ 434 static bool equals (tree t1, tree t2); 435 }; // class sem_variable 436 437 class sem_item_optimizer; 438 439 struct congruence_class_group 440 { 441 hashval_t hash; 442 sem_item_type type; 443 vec <congruence_class *> classes; 444 }; 445 446 /* Congruence class set structure. */ 447 struct congruence_class_hash : nofree_ptr_hash <congruence_class_group> 448 { hashcongruence_class_hash449 static inline hashval_t hash (const congruence_class_group *item) 450 { 451 return item->hash; 452 } 453 equalcongruence_class_hash454 static inline int equal (const congruence_class_group *item1, 455 const congruence_class_group *item2) 456 { 457 return item1->hash == item2->hash && item1->type == item2->type; 458 } 459 }; 460 461 struct traverse_split_pair 462 { 463 sem_item_optimizer *optimizer; 464 class congruence_class *cls; 465 }; 466 467 /* Semantic item optimizer includes all top-level logic 468 related to semantic equality comparison. */ 469 class sem_item_optimizer 470 { 471 public: 472 sem_item_optimizer (); 473 ~sem_item_optimizer (); 474 475 /* Function responsible for visiting all potential functions and 476 read-only variables that can be merged. */ 477 void parse_funcs_and_vars (void); 478 479 /* Optimizer entry point which returns true in case it processes 480 a merge operation. True is returned if there's a merge operation 481 processed. */ 482 bool execute (void); 483 484 /* Dump function. */ 485 void dump (void); 486 487 /* Verify congruence classes if checking is enabled. */ 488 void checking_verify_classes (void); 489 490 /* Verify congruence classes. */ 491 void verify_classes (void); 492 493 /* Write IPA ICF summary for symbols. */ 494 void write_summary (void); 495 496 /* Read IPA ICF summary for symbols. */ 497 void read_summary (void); 498 499 /* Callgraph removal hook called for a NODE with a custom DATA. */ 500 static void cgraph_removal_hook (cgraph_node *node, void *data); 501 502 /* Varpool removal hook called for a NODE with a custom DATA. */ 503 static void varpool_removal_hook (varpool_node *node, void *data); 504 505 /* Worklist of congruence classes that can potentially 506 refine classes of congruence. */ 507 std::list<congruence_class *> worklist; 508 509 /* Remove semantic ITEM and release memory. */ 510 void remove_item (sem_item *item); 511 512 /* Remove symtab NODE triggered by symtab removal hooks. */ 513 void remove_symtab_node (symtab_node *node); 514 515 /* Register callgraph and varpool hooks. */ 516 void register_hooks (void); 517 518 /* Unregister callgraph and varpool hooks. */ 519 void unregister_hooks (void); 520 521 /* Adds a CLS to hashtable associated by hash value. */ 522 void add_class (congruence_class *cls); 523 524 /* Gets a congruence class group based on given HASH value and TYPE. */ 525 congruence_class_group *get_group_by_hash (hashval_t hash, 526 sem_item_type type); 527 528 /* Because types can be arbitrarily large, avoid quadratic bottleneck. */ 529 hash_map<const_tree, hashval_t> m_type_hash_cache; 530 private: 531 532 /* For each semantic item, append hash values of references. */ 533 void update_hash_by_addr_refs (); 534 535 /* Congruence classes are built by hash value. */ 536 void build_hash_based_classes (void); 537 538 /* Semantic items in classes having more than one element and initialized. 539 In case of WPA, we load function body. */ 540 void parse_nonsingleton_classes (void); 541 542 /* Equality function for semantic items is used to subdivide existing 543 classes. If IN_WPA, fast equality function is invoked. */ 544 void subdivide_classes_by_equality (bool in_wpa = false); 545 546 /* Subdivide classes by address and interposable references 547 that members of the class reference. 548 Example can be a pair of functions that have an address 549 taken from a function. If these addresses are different the class 550 is split. */ 551 unsigned subdivide_classes_by_sensitive_refs(); 552 553 /* Debug function prints all informations about congruence classes. */ 554 void dump_cong_classes (void); 555 556 /* Build references according to call graph. */ 557 void build_graph (void); 558 559 /* Iterative congruence reduction function. */ 560 void process_cong_reduction (void); 561 562 /* After reduction is done, we can declare all items in a group 563 to be equal. PREV_CLASS_COUNT is start number of classes 564 before reduction. True is returned if there's a merge operation 565 processed. */ 566 bool merge_classes (unsigned int prev_class_count); 567 568 /* Fixup points to analysis info. */ 569 void fixup_points_to_sets (void); 570 571 /* Fixup points to set PT. */ 572 void fixup_pt_set (struct pt_solution *pt); 573 574 /* Adds a newly created congruence class CLS to worklist. */ 575 void worklist_push (congruence_class *cls); 576 577 /* Pops a class from worklist. */ 578 congruence_class *worklist_pop (); 579 580 /* Every usage of a congruence class CLS is a candidate that can split the 581 collection of classes. Bitmap stack BMSTACK is used for bitmap 582 allocation. */ 583 void do_congruence_step (congruence_class *cls); 584 585 /* Tests if a class CLS used as INDEXth splits any congruence classes. 586 Bitmap stack BMSTACK is used for bitmap allocation. */ 587 void do_congruence_step_for_index (congruence_class *cls, unsigned int index); 588 589 /* Makes pairing between a congruence class CLS and semantic ITEM. */ 590 static void add_item_to_class (congruence_class *cls, sem_item *item); 591 592 /* Disposes split map traverse function. CLS is congruence 593 class, BSLOT is bitmap slot we want to release. DATA is mandatory, 594 but unused argument. */ 595 static bool release_split_map (congruence_class * const &cls, bitmap const &b, 596 traverse_split_pair *pair); 597 598 /* Process split operation for a cognruence class CLS, 599 where bitmap B splits congruence class members. DATA is used 600 as argument of split pair. */ 601 static bool traverse_congruence_split (congruence_class * const &cls, 602 bitmap const &b, 603 traverse_split_pair *pair); 604 605 /* Compare function for sorting pairs in do_congruence_step_f. */ 606 static int sort_congruence_split (const void *, const void *); 607 608 /* Reads a section from LTO stream file FILE_DATA. Input block for DATA 609 contains LEN bytes. */ 610 void read_section (lto_file_decl_data *file_data, const char *data, 611 size_t len); 612 613 /* Removes all callgraph and varpool nodes that are marked by symtab 614 as deleted. */ 615 void filter_removed_items (void); 616 617 /* Vector of semantic items. */ 618 vec <sem_item *> m_items; 619 620 /* A set containing all items removed by hooks. */ 621 hash_set <symtab_node *> m_removed_items_set; 622 623 /* Hashtable of congruence classes. */ 624 hash_table <congruence_class_hash> m_classes; 625 626 /* Count of congruence classes. */ 627 unsigned int m_classes_count; 628 629 /* Map data structure maps symtab nodes to semantic items. */ 630 hash_map <symtab_node *, sem_item *> m_symtab_node_map; 631 632 /* Set to true if a splitter class is removed. */ 633 bool splitter_class_removed; 634 635 /* Global unique class id counter. */ 636 static unsigned int class_id; 637 638 /* Callgraph node removal hook holder. */ 639 cgraph_node_hook_list *m_cgraph_node_hooks; 640 641 /* Varpool node removal hook holder. */ 642 varpool_node_hook_list *m_varpool_node_hooks; 643 644 /* Bitmap stack. */ 645 bitmap_obstack m_bmstack; 646 647 /* Vector of merged variables. Needed for fixup of points-to-analysis 648 info. */ 649 vec <symtab_pair> m_merged_variables; 650 }; // class sem_item_optimizer 651 652 } // ipa_icf namespace 653