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_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_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 /* Fast equality function based on knowledge known in WPA. */
175 virtual bool equals_wpa (sem_item
*item
,
176 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
) = 0;
178 /* Returns true if the item equals to ITEM given as arguemnt. */
179 virtual bool equals (sem_item
*item
,
180 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
) = 0;
182 /* References independent hash function. */
183 virtual hashval_t
get_hash (void) = 0;
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
;
241 /* Temporary hash used where hash values of references are added. */
242 hashval_t global_hash
;
244 /* Cached, once calculated hash for the item. */
246 /* Accumulate to HSTATE a hash of expression EXP. */
247 static void add_expr (const_tree exp
, inchash::hash
&hstate
);
248 /* Accumulate to HSTATE a hash of type T. */
249 static void add_type (const_tree t
, inchash::hash
&hstate
);
251 /* Compare properties of symbol that does not affect semantics of symbol
252 itself but affects semantics of its references.
253 If ADDRESS is true, do extra checking needed for IPA_REF_ADDR. */
254 static bool compare_referenced_symbol_properties (symtab_node
*used_by
,
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
,
273 /* Initialize internal data structures. Bitmap STACK is used for
274 bitmap memory allocation process. */
275 void setup (bitmap_obstack
*stack
);
278 class sem_function
: public sem_item
281 /* Semantic function constructor that uses STACK as bitmap memory stack. */
282 sem_function (bitmap_obstack
*stack
);
284 /* Constructor based on callgraph node _NODE with computed hash _HASH.
285 Bitmap STACK is used for memory allocation. */
286 sem_function (cgraph_node
*_node
, hashval_t _hash
, bitmap_obstack
*stack
);
290 inline virtual void init_wpa (void)
295 virtual void init (void);
296 virtual bool equals_wpa (sem_item
*item
,
297 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
298 virtual hashval_t
get_hash (void);
299 virtual bool equals (sem_item
*item
,
300 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
301 virtual bool merge (sem_item
*alias_item
);
303 /* Dump symbol to FILE. */
304 virtual void dump_to_file (FILE *file
)
307 dump_function_to_file (decl
, file
, TDF_DETAILS
);
310 /* Parses function arguments and result type. */
311 void parse_tree_args (void);
313 /* Returns cgraph_node. */
314 inline cgraph_node
*get_node (void)
316 return dyn_cast
<cgraph_node
*> (node
);
319 /* Improve accumulated hash for HSTATE based on a gimple statement STMT. */
320 void hash_stmt (gimple stmt
, inchash::hash
&inchash
);
322 /* Return true if polymorphic comparison must be processed. */
323 bool compare_polymorphic_p (void);
325 /* For a given call graph NODE, the function constructs new
326 semantic function item. */
327 static sem_function
*parse (cgraph_node
*node
, bitmap_obstack
*stack
);
329 /* Exception handling region tree. */
330 eh_region region_tree
;
332 /* Result type tree node. */
335 /* Array of argument tree types. */
336 vec
<tree
> arg_types
;
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
;
360 /* Calculates hash value based on a BASIC_BLOCK. */
361 hashval_t
get_bb_hash (const ipa_icf_gimple::sem_bb
*basic_block
);
363 /* For given basic blocks BB1 and BB2 (from functions FUNC1 and FUNC),
364 true value is returned if phi nodes are semantically
365 equivalent in these blocks . */
366 bool compare_phi_node (basic_block bb1
, basic_block bb2
);
368 /* Basic blocks dictionary BB_DICT returns true if SOURCE index BB
369 corresponds to TARGET. */
370 bool bb_dict_test (vec
<int> *bb_dict
, int source
, int target
);
372 /* If cgraph edges E1 and E2 are indirect calls, verify that
373 ICF flags are the same. */
374 bool compare_edge_flags (cgraph_edge
*e1
, cgraph_edge
*e2
);
376 /* Processes function equality comparison. */
377 bool equals_private (sem_item
*item
,
378 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
380 /* Returns true if tree T can be compared as a handled component. */
381 static bool icf_handled_component_p (tree t
);
383 /* Function checker stores binding between functions. */
384 ipa_icf_gimple::func_checker
*m_checker
;
386 /* COMPARED_FUNC is a function that we compare to. */
387 sem_function
*m_compared_func
;
388 }; // class sem_function
390 class sem_variable
: public sem_item
393 /* Semantic variable constructor that uses STACK as bitmap memory stack. */
394 sem_variable (bitmap_obstack
*stack
);
396 /* Constructor based on callgraph node _NODE with computed hash _HASH.
397 Bitmap STACK is used for memory allocation. */
399 sem_variable (varpool_node
*_node
, hashval_t _hash
, bitmap_obstack
*stack
);
401 inline virtual void init_wpa (void) {}
403 /* Semantic variable initialization function. */
404 inline virtual void init (void)
406 decl
= get_node ()->decl
;
409 virtual hashval_t
get_hash (void);
410 virtual bool merge (sem_item
*alias_item
);
411 virtual void dump_to_file (FILE *file
);
412 virtual bool equals (sem_item
*item
,
413 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
415 /* Fast equality variable based on knowledge known in WPA. */
416 virtual bool equals_wpa (sem_item
*item
,
417 hash_map
<symtab_node
*, sem_item
*> &ignored_nodes
);
419 /* Returns varpool_node. */
420 inline varpool_node
*get_node (void)
422 return dyn_cast
<varpool_node
*> (node
);
425 /* Parser function that visits a varpool NODE. */
426 static sem_variable
*parse (varpool_node
*node
, bitmap_obstack
*stack
);
429 /* Compares trees T1 and T2 for semantic equality. */
430 static bool equals (tree t1
, tree t2
);
431 }; // class sem_variable
433 class sem_item_optimizer
;
435 struct congruence_class_group
439 vec
<congruence_class
*> classes
;
442 /* Congruence class set structure. */
443 struct congruence_class_group_hash
: typed_noop_remove
<congruence_class_group
>
445 typedef congruence_class_group
*value_type
;
446 typedef congruence_class_group
*compare_type
;
448 static inline hashval_t
hash (const congruence_class_group
*item
)
453 static inline int equal (const congruence_class_group
*item1
,
454 const congruence_class_group
*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 which returns true in case it processes
479 a merge operation. True is returned if there's a merge operation
486 /* Verify congruence classes if checking is enabled. */
487 void verify_classes (void);
489 /* Write IPA ICF summary for symbols. */
490 void write_summary (void);
492 /* Read IPA IPA ICF summary for symbols. */
493 void read_summary (void);
495 /* Callgraph removal hook called for a NODE with a custom DATA. */
496 static void cgraph_removal_hook (cgraph_node
*node
, void *data
);
498 /* Varpool removal hook called for a NODE with a custom DATA. */
499 static void varpool_removal_hook (varpool_node
*node
, void *data
);
501 /* Worklist of congruence classes that can potentially
502 refine classes of congruence. */
503 std::list
<congruence_class
*> worklist
;
505 /* Remove semantic ITEM and release memory. */
506 void remove_item (sem_item
*item
);
508 /* Remove symtab NODE triggered by symtab removal hooks. */
509 void remove_symtab_node (symtab_node
*node
);
511 /* Register callgraph and varpool hooks. */
512 void register_hooks (void);
514 /* Unregister callgraph and varpool hooks. */
515 void unregister_hooks (void);
517 /* Adds a CLS to hashtable associated by hash value. */
518 void add_class (congruence_class
*cls
);
520 /* Gets a congruence class group based on given HASH value and TYPE. */
521 congruence_class_group
*get_group_by_hash (hashval_t hash
,
524 /* Because types can be arbitrarily large, avoid quadratic bottleneck. */
525 hash_map
<const_tree
, hashval_t
> m_type_hash_cache
;
528 /* For each semantic item, append hash values of references. */
529 void update_hash_by_addr_refs ();
531 /* Congruence classes are built by hash value. */
532 void build_hash_based_classes (void);
534 /* Semantic items in classes having more than one element and initialized.
535 In case of WPA, we load function body. */
536 void parse_nonsingleton_classes (void);
538 /* Equality function for semantic items is used to subdivide existing
539 classes. If IN_WPA, fast equality function is invoked. */
540 void subdivide_classes_by_equality (bool in_wpa
= false);
542 /* Subdivide classes by address and interposable references
543 that members of the class reference.
544 Example can be a pair of functions that have an address
545 taken from a function. If these addresses are different the class
547 unsigned subdivide_classes_by_sensitive_refs();
549 /* Debug function prints all informations about congruence classes. */
550 void dump_cong_classes (void);
552 /* Build references according to call graph. */
553 void build_graph (void);
555 /* Iterative congruence reduction function. */
556 void process_cong_reduction (void);
558 /* After reduction is done, we can declare all items in a group
559 to be equal. PREV_CLASS_COUNT is start number of classes
560 before reduction. True is returned if there's a merge operation
562 bool merge_classes (unsigned int prev_class_count
);
564 /* Adds a newly created congruence class CLS to worklist. */
565 void worklist_push (congruence_class
*cls
);
567 /* Pops a class from worklist. */
568 congruence_class
*worklist_pop ();
570 /* Every usage of a congruence class CLS is a candidate that can split the
571 collection of classes. Bitmap stack BMSTACK is used for bitmap
573 void do_congruence_step (congruence_class
*cls
);
575 /* Tests if a class CLS used as INDEXth splits any congruence classes.
576 Bitmap stack BMSTACK is used for bitmap allocation. */
577 void do_congruence_step_for_index (congruence_class
*cls
, unsigned int index
);
579 /* Makes pairing between a congruence class CLS and semantic ITEM. */
580 static void add_item_to_class (congruence_class
*cls
, sem_item
*item
);
582 /* Disposes split map traverse function. CLS is congruence
583 class, BSLOT is bitmap slot we want to release. DATA is mandatory,
584 but unused argument. */
585 static bool release_split_map (congruence_class
* const &cls
, bitmap
const &b
,
586 traverse_split_pair
*pair
);
588 /* Process split operation for a cognruence class CLS,
589 where bitmap B splits congruence class members. DATA is used
590 as argument of split pair. */
591 static bool traverse_congruence_split (congruence_class
* const &cls
,
593 traverse_split_pair
*pair
);
595 /* Reads a section from LTO stream file FILE_DATA. Input block for DATA
596 contains LEN bytes. */
597 void read_section (lto_file_decl_data
*file_data
, const char *data
,
600 /* Removes all callgraph and varpool nodes that are marked by symtab
602 void filter_removed_items (void);
604 /* Vector of semantic items. */
605 vec
<sem_item
*> m_items
;
607 /* A set containing all items removed by hooks. */
608 hash_set
<symtab_node
*> m_removed_items_set
;
610 /* Hashtable of congruence classes */
611 hash_table
<congruence_class_group_hash
> m_classes
;
613 /* Count of congruence classes. */
614 unsigned int m_classes_count
;
616 /* Map data structure maps symtab nodes to semantic items. */
617 hash_map
<symtab_node
*, sem_item
*> m_symtab_node_map
;
619 /* Set to true if a splitter class is removed. */
620 bool splitter_class_removed
;
622 /* Global unique class id counter. */
623 static unsigned int class_id
;
625 /* Callgraph node removal hook holder. */
626 cgraph_node_hook_list
*m_cgraph_node_hooks
;
628 /* Varpool node removal hook holder. */
629 varpool_node_hook_list
*m_varpool_node_hooks
;
632 bitmap_obstack m_bmstack
;
633 }; // class sem_item_optimizer
635 } // ipa_icf namespace