1 /* Interprocedural semantic function equality pass
2 Copyright (C) 2014-2015 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_hashmap_traits
: default_hashmap_traits
93 hash (const symbol_compare_collection
*v
)
96 hstate
.add_int (v
->m_references
.length ());
98 for (unsigned i
= 0; i
< v
->m_references
.length (); i
++)
99 hstate
.add_ptr (v
->m_references
[i
]->ultimate_alias_target ());
101 hstate
.add_int (v
->m_interposables
.length ());
103 for (unsigned i
= 0; i
< v
->m_interposables
.length (); i
++)
104 hstate
.add_ptr (v
->m_interposables
[i
]->ultimate_alias_target ());
106 return hstate
.end ();
110 equal_keys (const symbol_compare_collection
*a
,
111 const symbol_compare_collection
*b
)
113 if (a
->m_references
.length () != b
->m_references
.length ()
114 || a
->m_interposables
.length () != b
->m_interposables
.length ())
117 for (unsigned i
= 0; i
< a
->m_references
.length (); i
++)
118 if (a
->m_references
[i
]->equal_address_to (b
->m_references
[i
]) != 1)
121 for (unsigned i
= 0; i
< a
->m_interposables
.length (); i
++)
122 if (!a
->m_interposables
[i
]->semantically_equivalent_p
123 (b
->m_interposables
[i
]))
131 /* Semantic item usage pair. */
135 /* Constructor for key value pair, where _ITEM is key and _INDEX is a target. */
136 sem_usage_pair (sem_item
*_item
, unsigned int _index
);
138 /* Target semantic item where an item is used. */
141 /* Index of usage of such an item. */
145 /* Semantic item is a base class that encapsulates all shared functionality
146 for both semantic function and variable items. */
150 /* Semantic item constructor for a node of _TYPE, where STACK is used
151 for bitmap memory allocation. */
152 sem_item (sem_item_type _type
, bitmap_obstack
*stack
);
154 /* Semantic item constructor for a node of _TYPE, where STACK is used
155 for bitmap memory allocation. The item is based on symtab node _NODE
156 with computed _HASH. */
157 sem_item (sem_item_type _type
, symtab_node
*_node
, hashval_t _hash
,
158 bitmap_obstack
*stack
);
160 virtual ~sem_item ();
162 /* Dump function for debugging purpose. */
163 DEBUG_FUNCTION
void dump (void);
165 /* Initialize semantic item by info reachable during LTO WPA phase. */
166 virtual void init_wpa (void) = 0;
168 /* Semantic item initialization function. */
169 virtual void init (void) = 0;
171 /* Add reference to a semantic TARGET. */
172 void add_reference (sem_item
*target
);
174 /* Gets symbol name of the item. */
175 const char *name (void)
177 return node
->name ();
180 /* Gets assembler name of the item. */
181 const char *asm_name (void)
183 return node
->asm_name ();
186 /* Fast equality function based on knowledge known in WPA. */
187 virtual bool equals_wpa (sem_item
*item
,
188 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
) = 0;
190 /* Returns true if the item equals to ITEM given as arguemnt. */
191 virtual bool equals (sem_item
*item
,
192 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
) = 0;
194 /* References independent hash function. */
195 virtual hashval_t
get_hash (void) = 0;
197 /* Merges instance with an ALIAS_ITEM, where alias, thunk or redirection can
199 virtual bool merge (sem_item
*alias_item
) = 0;
201 /* Dump symbol to FILE. */
202 virtual void dump_to_file (FILE *file
) = 0;
204 /* Return base tree that can be used for compatible_types_p and
205 contains_polymorphic_type_p comparison. */
206 static bool get_base_types (tree
*t1
, tree
*t2
);
208 /* Return true if target supports alias symbols. */
209 bool target_supports_symbol_aliases_p (void);
217 /* Declaration tree node. */
220 /* Semantic references used that generate congruence groups. */
221 vec
<sem_item
*> refs
;
223 /* Pointer to a congruence class the item belongs to. */
224 congruence_class
*cls
;
226 /* Index of the item in a class belonging to. */
227 unsigned int index_in_class
;
229 /* List of semantic items where the instance is used. */
230 vec
<sem_usage_pair
*> usages
;
232 /* A bitmap with indices of all classes referencing this item. */
233 bitmap usage_index_bitmap
;
235 /* List of tree references (either FUNC_DECL or VAR_DECL). */
236 vec
<tree
> tree_refs
;
238 /* A set with symbol table references. */
239 hash_set
<symtab_node
*> refs_set
;
242 /* Cached, once calculated hash for the item. */
246 /* Initialize internal data structures. Bitmap STACK is used for
247 bitmap memory allocation process. */
248 void setup (bitmap_obstack
*stack
);
251 class sem_function
: public sem_item
254 /* Semantic function constructor that uses STACK as bitmap memory stack. */
255 sem_function (bitmap_obstack
*stack
);
257 /* Constructor based on callgraph node _NODE with computed hash _HASH.
258 Bitmap STACK is used for memory allocation. */
259 sem_function (cgraph_node
*_node
, hashval_t _hash
, bitmap_obstack
*stack
);
263 inline virtual void init_wpa (void)
268 virtual void init (void);
269 virtual bool equals_wpa (sem_item
*item
,
270 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
271 virtual hashval_t
get_hash (void);
272 virtual bool equals (sem_item
*item
,
273 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
274 virtual bool merge (sem_item
*alias_item
);
276 /* Dump symbol to FILE. */
277 virtual void dump_to_file (FILE *file
)
280 dump_function_to_file (decl
, file
, TDF_DETAILS
);
283 /* Parses function arguments and result type. */
284 void parse_tree_args (void);
286 /* Returns cgraph_node. */
287 inline cgraph_node
*get_node (void)
289 return dyn_cast
<cgraph_node
*> (node
);
292 /* Improve accumulated hash for HSTATE based on a gimple statement STMT. */
293 void hash_stmt (inchash::hash
*inchash
, gimple stmt
);
295 /* Return true if polymorphic comparison must be processed. */
296 bool compare_polymorphic_p (void);
298 /* For a given call graph NODE, the function constructs new
299 semantic function item. */
300 static sem_function
*parse (cgraph_node
*node
, bitmap_obstack
*stack
);
302 /* Exception handling region tree. */
303 eh_region region_tree
;
305 /* Result type tree node. */
308 /* Array of argument tree types. */
309 vec
<tree
> arg_types
;
311 /* Number of function arguments. */
312 unsigned int arg_count
;
314 /* Total amount of edges in the function. */
315 unsigned int edge_count
;
317 /* Vector of sizes of all basic blocks. */
318 vec
<unsigned int> bb_sizes
;
320 /* Control flow graph checksum. */
321 hashval_t cfg_checksum
;
323 /* GIMPLE codes hash value. */
324 hashval_t gcode_hash
;
326 /* Total number of SSA names used in the function. */
327 unsigned ssa_names_size
;
329 /* Array of structures for all basic blocks. */
330 vec
<ipa_icf_gimple::sem_bb
*> bb_sorted
;
333 /* Calculates hash value based on a BASIC_BLOCK. */
334 hashval_t
get_bb_hash (const ipa_icf_gimple::sem_bb
*basic_block
);
336 /* For given basic blocks BB1 and BB2 (from functions FUNC1 and FUNC),
337 true value is returned if phi nodes are semantically
338 equivalent in these blocks . */
339 bool compare_phi_node (basic_block bb1
, basic_block bb2
);
341 /* Basic blocks dictionary BB_DICT returns true if SOURCE index BB
342 corresponds to TARGET. */
343 bool bb_dict_test (vec
<int> *bb_dict
, int source
, int target
);
345 /* Iterates all tree types in T1 and T2 and returns true if all types
346 are compatible. If COMPARE_POLYMORPHIC is set to true,
347 more strict comparison is executed. */
348 bool compare_type_list (tree t1
, tree t2
, bool compare_polymorphic
);
350 /* If cgraph edges E1 and E2 are indirect calls, verify that
351 ICF flags are the same. */
352 bool compare_edge_flags (cgraph_edge
*e1
, cgraph_edge
*e2
);
354 /* For a given symbol table nodes N1 and N2, we check that FUNCTION_DECLs
355 point to a same function. Comparison can be skipped if IGNORED_NODES
356 contains these nodes. */
357 bool compare_cgraph_references (hash_map
<symtab_node
*, sem_item
*>
359 symtab_node
*n1
, symtab_node
*n2
);
361 /* Processes function equality comparison. */
362 bool equals_private (sem_item
*item
,
363 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
365 /* Returns true if tree T can be compared as a handled component. */
366 static bool icf_handled_component_p (tree t
);
368 /* Function checker stores binding between functions. */
369 ipa_icf_gimple::func_checker
*m_checker
;
371 /* COMPARED_FUNC is a function that we compare to. */
372 sem_function
*m_compared_func
;
373 }; // class sem_function
375 class sem_variable
: public sem_item
378 /* Semantic variable constructor that uses STACK as bitmap memory stack. */
379 sem_variable (bitmap_obstack
*stack
);
381 /* Constructor based on callgraph node _NODE with computed hash _HASH.
382 Bitmap STACK is used for memory allocation. */
384 sem_variable (varpool_node
*_node
, hashval_t _hash
, bitmap_obstack
*stack
);
386 inline virtual void init_wpa (void) {}
388 /* Semantic variable initialization function. */
389 inline virtual void init (void)
391 decl
= get_node ()->decl
;
392 ctor
= ctor_for_folding (decl
);
395 virtual hashval_t
get_hash (void);
396 virtual bool merge (sem_item
*alias_item
);
397 virtual void dump_to_file (FILE *file
);
398 virtual bool equals (sem_item
*item
,
399 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
401 /* Fast equality variable based on knowledge known in WPA. */
402 inline virtual bool equals_wpa (sem_item
*item
,
403 hash_map
<symtab_node
*, sem_item
*> & ARG_UNUSED(ignored_nodes
))
405 gcc_assert (item
->type
== VAR
);
409 /* Returns varpool_node. */
410 inline varpool_node
*get_node (void)
412 return dyn_cast
<varpool_node
*> (node
);
415 /* Parser function that visits a varpool NODE. */
416 static sem_variable
*parse (varpool_node
*node
, bitmap_obstack
*stack
);
418 /* Variable constructor. */
422 /* Iterates though a constructor and identifies tree references
423 we are interested in semantic function equality. */
424 void parse_tree_refs (tree t
);
426 /* Compares trees T1 and T2 for semantic equality. */
427 static bool equals (tree t1
, tree t2
);
429 /* Compare that symbol sections are either NULL or have same name. */
430 bool compare_sections (sem_variable
*alias
);
432 }; // class sem_variable
434 class sem_item_optimizer
;
436 struct congruence_class_group
440 vec
<congruence_class
*> classes
;
443 /* Congruence class set structure. */
444 struct congruence_class_group_hash
: typed_noop_remove
<congruence_class_group
>
446 typedef congruence_class_group value_type
;
447 typedef congruence_class_group compare_type
;
449 static inline hashval_t
hash (const value_type
*item
)
454 static inline int equal (const value_type
*item1
, const compare_type
*item2
)
456 return item1
->hash
== item2
->hash
&& item1
->type
== item2
->type
;
460 struct traverse_split_pair
462 sem_item_optimizer
*optimizer
;
463 class congruence_class
*cls
;
466 /* Semantic item optimizer includes all top-level logic
467 related to semantic equality comparison. */
468 class sem_item_optimizer
471 sem_item_optimizer ();
472 ~sem_item_optimizer ();
474 /* Function responsible for visiting all potential functions and
475 read-only variables that can be merged. */
476 void parse_funcs_and_vars (void);
478 /* Optimizer entry point. */
484 /* Verify congruence classes if checking is enabled. */
485 void verify_classes (void);
487 /* Write IPA ICF summary for symbols. */
488 void write_summary (void);
490 /* Read IPA IPA ICF summary for symbols. */
491 void read_summary (void);
493 /* Callgraph removal hook called for a NODE with a custom DATA. */
494 static void cgraph_removal_hook (cgraph_node
*node
, void *data
);
496 /* Varpool removal hook called for a NODE with a custom DATA. */
497 static void varpool_removal_hook (varpool_node
*node
, void *data
);
499 /* Worklist of congruence classes that can potentially
500 refine classes of congruence. */
501 std::list
<congruence_class
*> worklist
;
503 /* Remove semantic ITEM and release memory. */
504 void remove_item (sem_item
*item
);
506 /* Remove symtab NODE triggered by symtab removal hooks. */
507 void remove_symtab_node (symtab_node
*node
);
509 /* Register callgraph and varpool hooks. */
510 void register_hooks (void);
512 /* Unregister callgraph and varpool hooks. */
513 void unregister_hooks (void);
515 /* Adds a CLS to hashtable associated by hash value. */
516 void add_class (congruence_class
*cls
);
518 /* Gets a congruence class group based on given HASH value and TYPE. */
519 congruence_class_group
*get_group_by_hash (hashval_t hash
,
524 /* Congruence classes are built by hash value. */
525 void build_hash_based_classes (void);
527 /* Semantic items in classes having more than one element and initialized.
528 In case of WPA, we load function body. */
529 void parse_nonsingleton_classes (void);
531 /* Equality function for semantic items is used to subdivide existing
532 classes. If IN_WPA, fast equality function is invoked. */
533 void subdivide_classes_by_equality (bool in_wpa
= false);
535 /* Subdivide classes by address and interposable references
536 that members of the class reference.
537 Example can be a pair of functions that have an address
538 taken from a function. If these addresses are different the class
540 unsigned subdivide_classes_by_sensitive_refs();
542 /* Debug function prints all informations about congruence classes. */
543 void dump_cong_classes (void);
545 /* Build references according to call graph. */
546 void build_graph (void);
548 /* Iterative congruence reduction function. */
549 void process_cong_reduction (void);
551 /* After reduction is done, we can declare all items in a group
552 to be equal. PREV_CLASS_COUNT is start number of classes
554 void merge_classes (unsigned int prev_class_count
);
556 /* Adds a newly created congruence class CLS to worklist. */
557 void worklist_push (congruence_class
*cls
);
559 /* Pops a class from worklist. */
560 congruence_class
*worklist_pop ();
562 /* Every usage of a congruence class CLS is a candidate that can split the
563 collection of classes. Bitmap stack BMSTACK is used for bitmap
565 void do_congruence_step (congruence_class
*cls
);
567 /* Tests if a class CLS used as INDEXth splits any congruence classes.
568 Bitmap stack BMSTACK is used for bitmap allocation. */
569 void do_congruence_step_for_index (congruence_class
*cls
, unsigned int index
);
571 /* Makes pairing between a congruence class CLS and semantic ITEM. */
572 static void add_item_to_class (congruence_class
*cls
, sem_item
*item
);
574 /* Disposes split map traverse function. CLS is congruence
575 class, BSLOT is bitmap slot we want to release. DATA is mandatory,
576 but unused argument. */
577 static bool release_split_map (congruence_class
* const &cls
, bitmap
const &b
,
578 traverse_split_pair
*pair
);
580 /* Process split operation for a cognruence class CLS,
581 where bitmap B splits congruence class members. DATA is used
582 as argument of split pair. */
583 static bool traverse_congruence_split (congruence_class
* const &cls
,
585 traverse_split_pair
*pair
);
587 /* Reads a section from LTO stream file FILE_DATA. Input block for DATA
588 contains LEN bytes. */
589 void read_section (lto_file_decl_data
*file_data
, const char *data
,
592 /* Removes all callgraph and varpool nodes that are marked by symtab
594 void filter_removed_items (void);
596 /* Vector of semantic items. */
597 vec
<sem_item
*> m_items
;
599 /* A set containing all items removed by hooks. */
600 hash_set
<symtab_node
*> m_removed_items_set
;
602 /* Hashtable of congruence classes */
603 hash_table
<congruence_class_group_hash
> m_classes
;
605 /* Count of congruence classes. */
606 unsigned int m_classes_count
;
608 /* Map data structure maps symtab nodes to semantic items. */
609 hash_map
<symtab_node
*, sem_item
*> m_symtab_node_map
;
611 /* Set to true if a splitter class is removed. */
612 bool splitter_class_removed
;
614 /* Global unique class id counter. */
615 static unsigned int class_id
;
617 /* Callgraph node removal hook holder. */
618 cgraph_node_hook_list
*m_cgraph_node_hooks
;
620 /* Varpool node removal hook holder. */
621 varpool_node_hook_list
*m_varpool_node_hooks
;
624 bitmap_obstack m_bmstack
;
625 }; // class sem_item_optimizer
627 } // ipa_icf namespace