1 /* Interprocedural semantic function equality pass
2 Copyright (C) 2014-2016 Free Software Foundation, Inc.
4 Contributed by Jan Hubicka <hubicka@ucw.cz> and Martin Liska <mliska@suse.cz>
6 This file is part of GCC.
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
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
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/>. */
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
31 /* Congruence class constructor for a new class with _ID. */
32 congruence_class (unsigned int _id): in_worklist (false), id(_id)
41 /* Dump function prints all class members to a FILE with an INDENT. */
42 void dump (FILE *file, unsigned int indent = 0) const;
44 /* Returns true if there's a member that is used from another group. */
45 bool is_class_used (void);
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). */
52 /* Vector of all group members. */
53 auto_vec <sem_item *> members;
55 /* Global unique class identifier. */
59 /* Semantic item type enum. */
66 /* Class is container for address references for a symtab_node. */
68 class symbol_compare_collection
72 symbol_compare_collection (symtab_node *node);
75 ~symbol_compare_collection ()
77 m_references.release ();
78 m_interposables.release ();
81 /* Vector of address references. */
82 vec<symtab_node *> m_references;
84 /* Vector of interposable references. */
85 vec<symtab_node *> m_interposables;
88 /* Hash traits for symbol_compare_collection map. */
90 struct symbol_compare_hash : nofree_ptr_hash <symbol_compare_collection>
96 hstate.add_int (v->m_references.length ());
98 for (unsigned i = 0; i < v->m_references.length (); i++)
99 hstate.add_int (v->m_references[i]->ultimate_alias_target ()->order);
101 hstate.add_int (v->m_interposables.length ());
103 for (unsigned i = 0; i < v->m_interposables.length (); i++)
104 hstate.add_int (v->m_interposables[i]->ultimate_alias_target ()->order);
106 return hstate.end ();
110 equal (value_type a, value_type b)
112 if (a->m_references.length () != b->m_references.length ()
113 || a->m_interposables.length () != b->m_interposables.length ())
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)
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]))
130 /* Semantic item usage pair. */
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);
137 /* Target semantic item where an item is used. */
140 /* Index of usage of such an item. */
144 /* Semantic item is a base class that encapsulates all shared functionality
145 for both semantic function and variable items. */
149 /* Semantic item constructor for a node of _TYPE, where STACK is used
150 for bitmap memory allocation. */
151 sem_item (sem_item_type _type, bitmap_obstack *stack);
153 /* Semantic item constructor for a node of _TYPE, where STACK is used
154 for bitmap memory allocation. The item is based on symtab node _NODE. */
155 sem_item (sem_item_type _type, symtab_node *_node, bitmap_obstack *stack);
157 virtual ~sem_item ();
159 /* Dump function for debugging purpose. */
160 DEBUG_FUNCTION void dump (void);
162 /* Initialize semantic item by info reachable during LTO WPA phase. */
163 virtual void init_wpa (void) = 0;
165 /* Semantic item initialization function. */
166 virtual void init (void) = 0;
168 /* Add reference to a semantic TARGET. */
169 void add_reference (sem_item *target);
171 /* Fast equality function based on knowledge known in WPA. */
172 virtual bool equals_wpa (sem_item *item,
173 hash_map <symtab_node *, sem_item *> &ignored_nodes) = 0;
175 /* Returns true if the item equals to ITEM given as arguemnt. */
176 virtual bool equals (sem_item *item,
177 hash_map <symtab_node *, sem_item *> &ignored_nodes) = 0;
179 /* References independent hash function. */
180 virtual hashval_t get_hash (void) = 0;
182 /* Set new hash value of the item. */
183 void set_hash (hashval_t hash);
185 /* Merges instance with an ALIAS_ITEM, where alias, thunk or redirection can
187 virtual bool merge (sem_item *alias_item) = 0;
189 /* Dump symbol to FILE. */
190 virtual void dump_to_file (FILE *file) = 0;
192 /* Update hash by address sensitive references. */
193 void update_hash_by_addr_refs (hash_map <symtab_node *,
194 sem_item *> &m_symtab_node_map);
196 /* Update hash by computed local hash values taken from different
198 void update_hash_by_local_refs (hash_map <symtab_node *,
199 sem_item *> &m_symtab_node_map);
201 /* Return base tree that can be used for compatible_types_p and
202 contains_polymorphic_type_p comparison. */
203 static bool get_base_types (tree *t1, tree *t2);
205 /* Return true if target supports alias symbols. */
206 bool target_supports_symbol_aliases_p (void);
214 /* Declaration tree node. */
217 /* Semantic references used that generate congruence groups. */
218 vec <sem_item *> refs;
220 /* Pointer to a congruence class the item belongs to. */
221 congruence_class *cls;
223 /* Index of the item in a class belonging to. */
224 unsigned int index_in_class;
226 /* List of semantic items where the instance is used. */
227 vec <sem_usage_pair *> usages;
229 /* A bitmap with indices of all classes referencing this item. */
230 bitmap usage_index_bitmap;
232 /* List of tree references (either FUNC_DECL or VAR_DECL). */
233 vec <tree> tree_refs;
235 /* A set with symbol table references. */
236 hash_set <symtab_node *> refs_set;
238 /* Temporary hash used where hash values of references are added. */
239 hashval_t global_hash;
241 /* Cached, once calculated hash for the item. */
243 /* Accumulate to HSTATE a hash of expression EXP. */
244 static void add_expr (const_tree exp, inchash::hash &hstate);
245 /* Accumulate to HSTATE a hash of type T. */
246 static void add_type (const_tree t, inchash::hash &hstate);
248 /* Compare properties of symbol that does not affect semantics of symbol
249 itself but affects semantics of its references.
250 If ADDRESS is true, do extra checking needed for IPA_REF_ADDR. */
251 static bool compare_referenced_symbol_properties (symtab_node *used_by,
256 /* Compare two attribute lists. */
257 static bool compare_attributes (const_tree list1, const_tree list2);
259 /* Hash properties compared by compare_referenced_symbol_properties. */
260 void hash_referenced_symbol_properties (symtab_node *ref,
261 inchash::hash &hstate,
264 /* For a given symbol table nodes N1 and N2, we check that FUNCTION_DECLs
265 point to a same function. Comparison can be skipped if IGNORED_NODES
266 contains these nodes. ADDRESS indicate if address is taken. */
267 bool compare_symbol_references (hash_map <symtab_node *, sem_item *>
269 symtab_node *n1, symtab_node *n2,
275 /* Indicated whether a hash value has been set or not. */
279 /* Initialize internal data structures. Bitmap STACK is used for
280 bitmap memory allocation process. */
281 void setup (bitmap_obstack *stack);
284 class sem_function: public sem_item
287 /* Semantic function constructor that uses STACK as bitmap memory stack. */
288 sem_function (bitmap_obstack *stack);
290 /* Constructor based on callgraph node _NODE.
291 Bitmap STACK is used for memory allocation. */
292 sem_function (cgraph_node *_node, bitmap_obstack *stack);
296 inline virtual void init_wpa (void)
300 virtual void init (void);
301 virtual bool equals_wpa (sem_item *item,
302 hash_map <symtab_node *, sem_item *> &ignored_nodes);
303 virtual hashval_t get_hash (void);
304 virtual bool equals (sem_item *item,
305 hash_map <symtab_node *, sem_item *> &ignored_nodes);
306 virtual bool merge (sem_item *alias_item);
308 /* Dump symbol to FILE. */
309 virtual void dump_to_file (FILE *file)
312 dump_function_to_file (decl, file, TDF_DETAILS);
315 /* Returns cgraph_node. */
316 inline cgraph_node *get_node (void)
318 return dyn_cast <cgraph_node *> (node);
321 /* Improve accumulated hash for HSTATE based on a gimple statement STMT. */
322 void hash_stmt (gimple *stmt, inchash::hash &inchash);
324 /* Return true if polymorphic comparison must be processed. */
325 bool compare_polymorphic_p (void);
327 /* For a given call graph NODE, the function constructs new
328 semantic function item. */
329 static sem_function *parse (cgraph_node *node, bitmap_obstack *stack);
331 /* Perform additional checks needed to match types of used function
333 bool compatible_parm_types_p (tree, tree);
335 /* Exception handling region tree. */
336 eh_region region_tree;
338 /* Number of function arguments. */
339 unsigned int arg_count;
341 /* Total amount of edges in the function. */
342 unsigned int edge_count;
344 /* Vector of sizes of all basic blocks. */
345 vec <unsigned int> bb_sizes;
347 /* Control flow graph checksum. */
348 hashval_t cfg_checksum;
350 /* GIMPLE codes hash value. */
351 hashval_t gcode_hash;
353 /* Total number of SSA names used in the function. */
354 unsigned ssa_names_size;
356 /* Array of structures for all basic blocks. */
357 vec <ipa_icf_gimple::sem_bb *> bb_sorted;
359 /* Return true if parameter I may be used. */
360 bool param_used_p (unsigned int i);
363 /* Calculates hash value based on a BASIC_BLOCK. */
364 hashval_t get_bb_hash (const ipa_icf_gimple::sem_bb *basic_block);
366 /* For given basic blocks BB1 and BB2 (from functions FUNC1 and FUNC),
367 true value is returned if phi nodes are semantically
368 equivalent in these blocks . */
369 bool compare_phi_node (basic_block bb1, basic_block bb2);
371 /* Basic blocks dictionary BB_DICT returns true if SOURCE index BB
372 corresponds to TARGET. */
373 bool bb_dict_test (vec<int> *bb_dict, int source, int target);
375 /* If cgraph edges E1 and E2 are indirect calls, verify that
376 ICF flags are the same. */
377 bool compare_edge_flags (cgraph_edge *e1, cgraph_edge *e2);
379 /* Processes function equality comparison. */
380 bool equals_private (sem_item *item);
382 /* Returns true if tree T can be compared as a handled component. */
383 static bool icf_handled_component_p (tree t);
385 /* Function checker stores binding between functions. */
386 ipa_icf_gimple::func_checker *m_checker;
388 /* COMPARED_FUNC is a function that we compare to. */
389 sem_function *m_compared_func;
390 }; // class sem_function
392 class sem_variable: public sem_item
395 /* Semantic variable constructor that uses STACK as bitmap memory stack. */
396 sem_variable (bitmap_obstack *stack);
398 /* Constructor based on callgraph node _NODE.
399 Bitmap STACK is used for memory allocation. */
401 sem_variable (varpool_node *_node, bitmap_obstack *stack);
403 inline virtual void init_wpa (void) {}
405 /* Semantic variable initialization function. */
406 inline virtual void init (void)
408 decl = get_node ()->decl;
411 virtual hashval_t get_hash (void);
412 virtual bool merge (sem_item *alias_item);
413 virtual void dump_to_file (FILE *file);
414 virtual bool equals (sem_item *item,
415 hash_map <symtab_node *, sem_item *> &ignored_nodes);
417 /* Fast equality variable based on knowledge known in WPA. */
418 virtual bool equals_wpa (sem_item *item,
419 hash_map <symtab_node *, sem_item *> &ignored_nodes);
421 /* Returns varpool_node. */
422 inline varpool_node *get_node (void)
424 return dyn_cast <varpool_node *> (node);
427 /* Parser function that visits a varpool NODE. */
428 static sem_variable *parse (varpool_node *node, bitmap_obstack *stack);
431 /* Compares trees T1 and T2 for semantic equality. */
432 static bool equals (tree t1, tree t2);
433 }; // class sem_variable
435 class sem_item_optimizer;
437 struct congruence_class_group
441 vec <congruence_class *> classes;
444 /* Congruence class set structure. */
445 struct congruence_class_group_hash : nofree_ptr_hash <congruence_class_group>
447 static inline hashval_t hash (const congruence_class_group *item)
452 static inline int equal (const congruence_class_group *item1,
453 const congruence_class_group *item2)
455 return item1->hash == item2->hash && item1->type == item2->type;
459 struct traverse_split_pair
461 sem_item_optimizer *optimizer;
462 class congruence_class *cls;
465 /* Semantic item optimizer includes all top-level logic
466 related to semantic equality comparison. */
467 class sem_item_optimizer
470 sem_item_optimizer ();
471 ~sem_item_optimizer ();
473 /* Function responsible for visiting all potential functions and
474 read-only variables that can be merged. */
475 void parse_funcs_and_vars (void);
477 /* Optimizer entry point which returns true in case it processes
478 a merge operation. True is returned if there's a merge operation
485 /* Verify congruence classes if checking is enabled. */
486 void checking_verify_classes (void);
488 /* Verify congruence classes. */
489 void verify_classes (void);
491 /* Write IPA ICF summary for symbols. */
492 void write_summary (void);
494 /* Read IPA ICF summary for symbols. */
495 void read_summary (void);
497 /* Callgraph removal hook called for a NODE with a custom DATA. */
498 static void cgraph_removal_hook (cgraph_node *node, void *data);
500 /* Varpool removal hook called for a NODE with a custom DATA. */
501 static void varpool_removal_hook (varpool_node *node, void *data);
503 /* Worklist of congruence classes that can potentially
504 refine classes of congruence. */
505 std::list<congruence_class *> worklist;
507 /* Remove semantic ITEM and release memory. */
508 void remove_item (sem_item *item);
510 /* Remove symtab NODE triggered by symtab removal hooks. */
511 void remove_symtab_node (symtab_node *node);
513 /* Register callgraph and varpool hooks. */
514 void register_hooks (void);
516 /* Unregister callgraph and varpool hooks. */
517 void unregister_hooks (void);
519 /* Adds a CLS to hashtable associated by hash value. */
520 void add_class (congruence_class *cls);
522 /* Gets a congruence class group based on given HASH value and TYPE. */
523 congruence_class_group *get_group_by_hash (hashval_t hash,
526 /* Because types can be arbitrarily large, avoid quadratic bottleneck. */
527 hash_map<const_tree, hashval_t> m_type_hash_cache;
530 /* For each semantic item, append hash values of references. */
531 void update_hash_by_addr_refs ();
533 /* Congruence classes are built by hash value. */
534 void build_hash_based_classes (void);
536 /* Semantic items in classes having more than one element and initialized.
537 In case of WPA, we load function body. */
538 void parse_nonsingleton_classes (void);
540 /* Equality function for semantic items is used to subdivide existing
541 classes. If IN_WPA, fast equality function is invoked. */
542 void subdivide_classes_by_equality (bool in_wpa = false);
544 /* Subdivide classes by address and interposable references
545 that members of the class reference.
546 Example can be a pair of functions that have an address
547 taken from a function. If these addresses are different the class
549 unsigned subdivide_classes_by_sensitive_refs();
551 /* Debug function prints all informations about congruence classes. */
552 void dump_cong_classes (void);
554 /* Build references according to call graph. */
555 void build_graph (void);
557 /* Iterative congruence reduction function. */
558 void process_cong_reduction (void);
560 /* After reduction is done, we can declare all items in a group
561 to be equal. PREV_CLASS_COUNT is start number of classes
562 before reduction. True is returned if there's a merge operation
564 bool merge_classes (unsigned int prev_class_count);
566 /* Adds a newly created congruence class CLS to worklist. */
567 void worklist_push (congruence_class *cls);
569 /* Pops a class from worklist. */
570 congruence_class *worklist_pop ();
572 /* Every usage of a congruence class CLS is a candidate that can split the
573 collection of classes. Bitmap stack BMSTACK is used for bitmap
575 void do_congruence_step (congruence_class *cls);
577 /* Tests if a class CLS used as INDEXth splits any congruence classes.
578 Bitmap stack BMSTACK is used for bitmap allocation. */
579 void do_congruence_step_for_index (congruence_class *cls, unsigned int index);
581 /* Makes pairing between a congruence class CLS and semantic ITEM. */
582 static void add_item_to_class (congruence_class *cls, sem_item *item);
584 /* Disposes split map traverse function. CLS is congruence
585 class, BSLOT is bitmap slot we want to release. DATA is mandatory,
586 but unused argument. */
587 static bool release_split_map (congruence_class * const &cls, bitmap const &b,
588 traverse_split_pair *pair);
590 /* Process split operation for a cognruence class CLS,
591 where bitmap B splits congruence class members. DATA is used
592 as argument of split pair. */
593 static bool traverse_congruence_split (congruence_class * const &cls,
595 traverse_split_pair *pair);
597 /* Reads a section from LTO stream file FILE_DATA. Input block for DATA
598 contains LEN bytes. */
599 void read_section (lto_file_decl_data *file_data, const char *data,
602 /* Removes all callgraph and varpool nodes that are marked by symtab
604 void filter_removed_items (void);
606 /* Vector of semantic items. */
607 vec <sem_item *> m_items;
609 /* A set containing all items removed by hooks. */
610 hash_set <symtab_node *> m_removed_items_set;
612 /* Hashtable of congruence classes */
613 hash_table <congruence_class_group_hash> m_classes;
615 /* Count of congruence classes. */
616 unsigned int m_classes_count;
618 /* Map data structure maps symtab nodes to semantic items. */
619 hash_map <symtab_node *, sem_item *> m_symtab_node_map;
621 /* Set to true if a splitter class is removed. */
622 bool splitter_class_removed;
624 /* Global unique class id counter. */
625 static unsigned int class_id;
627 /* Callgraph node removal hook holder. */
628 cgraph_node_hook_list *m_cgraph_node_hooks;
630 /* Varpool node removal hook holder. */
631 varpool_node_hook_list *m_varpool_node_hooks;
634 bitmap_obstack m_bmstack;
635 }; // class sem_item_optimizer
637 } // ipa_icf namespace