/* Interprocedural semantic function equality pass Copyright (C) 2014-2020 Free Software Foundation, Inc. Contributed by Jan Hubicka and Martin Liska This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see . */ namespace ipa_icf { class sem_item; /* Congruence class encompasses a collection of either functions or read-only variables. These items are considered to be equivalent if not proved the opposite. */ class congruence_class { public: /* Congruence class constructor for a new class with _ID. */ congruence_class (unsigned int _id): in_worklist (false), id (_id), referenced_by_count (0) { } /* Destructor. */ ~congruence_class () { } /* Dump function prints all class members to a FILE with an INDENT. */ void dump (FILE *file, unsigned int indent = 0) const; /* Returns true if there's a member that is used from another group. */ bool is_class_used (void); /* Flag is used in case we want to remove a class from worklist and delete operation is quite expensive for the data structure (linked list). */ bool in_worklist; /* Vector of all group members. */ auto_vec members; /* Global unique class identifier. */ unsigned int id; /* Total number of references to items of this class. */ unsigned referenced_by_count; }; /* Semantic item type enum. */ enum sem_item_type { FUNC, VAR }; /* Class is container for address references for a symtab_node. */ class symbol_compare_collection { public: /* Constructor. */ symbol_compare_collection (symtab_node *node); /* Destructor. */ ~symbol_compare_collection () { m_references.release (); m_interposables.release (); } /* Vector of address references. */ vec m_references; /* Vector of interposable references. */ vec m_interposables; }; /* Hash traits for symbol_compare_collection map. */ struct symbol_compare_hash : nofree_ptr_hash { static hashval_t hash (value_type v) { inchash::hash hstate; hstate.add_int (v->m_references.length ()); for (unsigned i = 0; i < v->m_references.length (); i++) hstate.add_int (v->m_references[i]->ultimate_alias_target ()->order); hstate.add_int (v->m_interposables.length ()); for (unsigned i = 0; i < v->m_interposables.length (); i++) hstate.add_int (v->m_interposables[i]->ultimate_alias_target ()->order); return hstate.end (); } static bool equal (value_type a, value_type b) { if (a->m_references.length () != b->m_references.length () || a->m_interposables.length () != b->m_interposables.length ()) return false; for (unsigned i = 0; i < a->m_references.length (); i++) if (a->m_references[i]->equal_address_to (b->m_references[i]) != 1) return false; for (unsigned i = 0; i < a->m_interposables.length (); i++) if (!a->m_interposables[i]->semantically_equivalent_p (b->m_interposables[i])) return false; return true; } }; /* Semantic item usage pair. */ class sem_usage_pair { public: /* Constructor for key value pair, where _ITEM is key and _INDEX is a target. */ sem_usage_pair (sem_item *_item, unsigned int _index); /* Target semantic item where an item is used. */ sem_item *item; /* Index of usage of such an item. */ unsigned int index; }; struct sem_usage_pair_hash : pointer_hash { static inline hashval_t hash (sem_usage_pair *); static inline bool equal (sem_usage_pair *, sem_usage_pair *); }; inline hashval_t sem_usage_pair_hash::hash (sem_usage_pair *pair) { inchash::hash hstate; hstate.add_ptr (pair->item); hstate.add_int (pair->index); return hstate.end (); } inline bool sem_usage_pair_hash::equal (sem_usage_pair *p1, sem_usage_pair *p2) { return p1->item == p2->item && p1->index == p2->index; } struct sem_usage_hash : sem_usage_pair_hash, typed_delete_remove {}; typedef hash_map > ref_map; typedef std::pair symtab_pair; /* Semantic item is a base class that encapsulates all shared functionality for both semantic function and variable items. */ class sem_item { public: /* Semantic item constructor for a node of _TYPE, where STACK is used for bitmap memory allocation. */ sem_item (sem_item_type _type, bitmap_obstack *stack); /* Semantic item constructor for a node of _TYPE, where STACK is used for bitmap memory allocation. The item is based on symtab node _NODE. */ sem_item (sem_item_type _type, symtab_node *_node, bitmap_obstack *stack); virtual ~sem_item (); /* Dump function for debugging purpose. */ DEBUG_FUNCTION void dump (void); /* Semantic item initialization function. */ virtual void init (ipa_icf_gimple::func_checker *) = 0; /* Add reference to a semantic TARGET. */ void add_reference (ref_map *map, sem_item *target); /* Fast equality function based on knowledge known in WPA. */ virtual bool equals_wpa (sem_item *item, hash_map &ignored_nodes) = 0; /* Returns true if the item equals to ITEM given as argument. */ virtual bool equals (sem_item *item, hash_map &ignored_nodes) = 0; /* References independent hash function. */ virtual hashval_t get_hash (void) = 0; /* Set new hash value of the item. */ void set_hash (hashval_t hash); /* Merges instance with an ALIAS_ITEM, where alias, thunk or redirection can be applied. */ virtual bool merge (sem_item *alias_item) = 0; /* Dump symbol to FILE. */ virtual void dump_to_file (FILE *file) = 0; /* Update hash by address sensitive references. */ void update_hash_by_addr_refs (hash_map &m_symtab_node_map); /* Update hash by computed local hash values taken from different semantic items. */ void update_hash_by_local_refs (hash_map &m_symtab_node_map); /* Return base tree that can be used for compatible_types_p and contains_polymorphic_type_p comparison. */ static bool get_base_types (tree *t1, tree *t2); /* Return true if target supports alias symbols. */ bool target_supports_symbol_aliases_p (void); /* Item type. */ sem_item_type type; /* Symtab node. */ symtab_node *node; /* Declaration tree node. */ tree decl; /* Number of references to a semantic symbols (function calls, variable references). */ unsigned reference_count; /* Pointer to a congruence class the item belongs to. */ congruence_class *cls; /* Index of the item in a class belonging to. */ unsigned int index_in_class; /* A bitmap with indices of all classes referencing this item. */ bitmap usage_index_bitmap; /* List of tree references (either FUNC_DECL or VAR_DECL). */ vec tree_refs; /* A set with symbol table references. */ hash_set refs_set; /* Temporary hash used where hash values of references are added. */ hashval_t global_hash; /* Number of references to this symbol. */ unsigned referenced_by_count; protected: /* Cached, once calculated hash for the item. */ /* Compare properties of symbol that does not affect semantics of symbol itself but affects semantics of its references. If ADDRESS is true, do extra checking needed for IPA_REF_ADDR. */ static bool compare_referenced_symbol_properties (symtab_node *used_by, symtab_node *n1, symtab_node *n2, bool address); /* Hash properties compared by compare_referenced_symbol_properties. */ void hash_referenced_symbol_properties (symtab_node *ref, inchash::hash &hstate, bool address); /* For a given symbol table nodes N1 and N2, we check that FUNCTION_DECLs point to a same function. Comparison can be skipped if IGNORED_NODES contains these nodes. ADDRESS indicate if address is taken. */ bool compare_symbol_references (hash_map &ignored_nodes, symtab_node *n1, symtab_node *n2, bool address); protected: /* Hash of item. */ hashval_t m_hash; /* Indicated whether a hash value has been set or not. */ bool m_hash_set; private: /* Initialize internal data structures. Bitmap STACK is used for bitmap memory allocation process. */ void setup (bitmap_obstack *stack); /* Because types can be arbitrarily large, avoid quadratic bottleneck. */ static hash_map m_type_hash_cache; }; // class sem_item class sem_function: public sem_item { public: /* Semantic function constructor that uses STACK as bitmap memory stack. */ sem_function (bitmap_obstack *stack); /* Constructor based on callgraph node _NODE. Bitmap STACK is used for memory allocation. */ sem_function (cgraph_node *_node, bitmap_obstack *stack); ~sem_function (); virtual void init (ipa_icf_gimple::func_checker *); virtual bool equals_wpa (sem_item *item, hash_map &ignored_nodes); virtual hashval_t get_hash (void); virtual bool equals (sem_item *item, hash_map &ignored_nodes); virtual bool merge (sem_item *alias_item); /* Dump symbol to FILE. */ virtual void dump_to_file (FILE *file) { gcc_assert (file); dump_function_to_file (decl, file, TDF_DETAILS); } /* Returns cgraph_node. */ inline cgraph_node *get_node (void) { return dyn_cast (node); } /* Improve accumulated hash for HSTATE based on a gimple statement STMT. */ void hash_stmt (gimple *stmt, inchash::hash &inchash); /* Return true if polymorphic comparison must be processed. */ bool compare_polymorphic_p (void); /* For a given call graph NODE, the function constructs new semantic function item. */ static sem_function *parse (cgraph_node *node, bitmap_obstack *stack, ipa_icf_gimple::func_checker *checker); /* Perform additional checks needed to match types of used function parameters. */ bool compatible_parm_types_p (tree, tree); /* Exception handling region tree. */ eh_region region_tree; /* Number of function arguments. */ unsigned int arg_count; /* Total amount of edges in the function. */ unsigned int edge_count; /* Vector of sizes of all basic blocks. */ vec bb_sizes; /* Control flow graph checksum. */ hashval_t cfg_checksum; /* GIMPLE codes hash value. */ hashval_t gcode_hash; /* Vector of subpart of memory access types. */ vec memory_access_types; /* Total number of SSA names used in the function. */ unsigned ssa_names_size; /* Array of structures for all basic blocks. */ vec bb_sorted; /* Hash of canonical types used for memory references in the function. */ hashval_t m_alias_sets_hash; /* Return true if parameter I may be used. */ bool param_used_p (unsigned int i); private: /* Calculates hash value based on a BASIC_BLOCK. */ hashval_t get_bb_hash (const ipa_icf_gimple::sem_bb *basic_block); /* For given basic blocks BB1 and BB2 (from functions FUNC1 and FUNC), true value is returned if phi nodes are semantically equivalent in these blocks . */ bool compare_phi_node (basic_block bb1, basic_block bb2); /* Basic blocks dictionary BB_DICT returns true if SOURCE index BB corresponds to TARGET. */ bool bb_dict_test (vec *bb_dict, int source, int target); /* If cgraph edges E1 and E2 are indirect calls, verify that ICF flags are the same. */ bool compare_edge_flags (cgraph_edge *e1, cgraph_edge *e2); /* Processes function equality comparison. */ bool equals_private (sem_item *item); /* Function checker stores binding between functions. */ ipa_icf_gimple::func_checker *m_checker; /* COMPARED_FUNC is a function that we compare to. */ sem_function *m_compared_func; }; // class sem_function class sem_variable: public sem_item { public: /* Semantic variable constructor that uses STACK as bitmap memory stack. */ sem_variable (bitmap_obstack *stack); /* Constructor based on callgraph node _NODE. Bitmap STACK is used for memory allocation. */ sem_variable (varpool_node *_node, bitmap_obstack *stack); /* Semantic variable initialization function. */ virtual void init (ipa_icf_gimple::func_checker *); virtual hashval_t get_hash (void); virtual bool merge (sem_item *alias_item); virtual void dump_to_file (FILE *file); virtual bool equals (sem_item *item, hash_map &ignored_nodes); /* Fast equality variable based on knowledge known in WPA. */ virtual bool equals_wpa (sem_item *item, hash_map &ignored_nodes); /* Returns varpool_node. */ inline varpool_node *get_node (void) { return dyn_cast (node); } /* Parser function that visits a varpool NODE. */ static sem_variable *parse (varpool_node *node, bitmap_obstack *stack, ipa_icf_gimple::func_checker *checker); private: /* Compares trees T1 and T2 for semantic equality. */ static bool equals (tree t1, tree t2); }; // class sem_variable class sem_item_optimizer; struct congruence_class_group { hashval_t hash; sem_item_type type; vec classes; }; /* Congruence class set structure. */ struct congruence_class_hash : nofree_ptr_hash { static inline hashval_t hash (const congruence_class_group *item) { return item->hash; } static inline int equal (const congruence_class_group *item1, const congruence_class_group *item2) { return item1->hash == item2->hash && item1->type == item2->type; } }; struct traverse_split_pair { sem_item_optimizer *optimizer; class congruence_class *cls; }; /* Semantic item optimizer includes all top-level logic related to semantic equality comparison. */ class sem_item_optimizer { public: sem_item_optimizer (); ~sem_item_optimizer (); /* Function responsible for visiting all potential functions and read-only variables that can be merged. */ void parse_funcs_and_vars (void); /* Optimizer entry point which returns true in case it processes a merge operation. True is returned if there's a merge operation processed. */ bool execute (void); /* Dump function. */ void dump (void); /* Verify congruence classes if checking is enabled. */ void checking_verify_classes (void); /* Verify congruence classes. */ void verify_classes (void); /* Write IPA ICF summary for symbols. */ void write_summary (void); /* Read IPA ICF summary for symbols. */ void read_summary (void); /* Callgraph removal hook called for a NODE with a custom DATA. */ static void cgraph_removal_hook (cgraph_node *node, void *data); /* Varpool removal hook called for a NODE with a custom DATA. */ static void varpool_removal_hook (varpool_node *node, void *data); /* Worklist of congruence classes that can potentially refine classes of congruence. */ fibonacci_heap worklist; /* Remove semantic ITEM and release memory. */ void remove_item (sem_item *item); /* Remove symtab NODE triggered by symtab removal hooks. */ void remove_symtab_node (symtab_node *node); /* Register callgraph and varpool hooks. */ void register_hooks (void); /* Unregister callgraph and varpool hooks. */ void unregister_hooks (void); /* Adds a CLS to hashtable associated by hash value. */ void add_class (congruence_class *cls); /* Gets a congruence class group based on given HASH value and TYPE. */ congruence_class_group *get_group_by_hash (hashval_t hash, sem_item_type type); private: /* For each semantic item, append hash values of references. */ void update_hash_by_addr_refs (); /* Update hash by canonical types of memory accesses. */ void update_hash_by_memory_access_type (); /* Congruence classes are built by hash value. */ void build_hash_based_classes (void); /* Semantic items in classes having more than one element and initialized. In case of WPA, we load function body. */ unsigned int parse_nonsingleton_classes (void); /* Equality function for semantic items is used to subdivide existing classes. If IN_WPA, fast equality function is invoked. */ void subdivide_classes_by_equality (bool in_wpa = false); /* Subdivide classes by address and interposable references that members of the class reference. Example can be a pair of functions that have an address taken from a function. If these addresses are different the class is split. */ unsigned subdivide_classes_by_sensitive_refs(); /* Debug function prints all informations about congruence classes. */ void dump_cong_classes (void); /* Build references according to call graph. */ void build_graph (void); /* Iterative congruence reduction function. */ void process_cong_reduction (void); /* After reduction is done, we can declare all items in a group to be equal. PREV_CLASS_COUNT is start number of classes before reduction. True is returned if there's a merge operation processed. LOADED_SYMBOLS is number of symbols that were loaded in WPA. */ bool merge_classes (unsigned int prev_class_count, unsigned int loaded_symbols); /* Fixup points to analysis info. */ void fixup_points_to_sets (void); /* Fixup points to set PT. */ void fixup_pt_set (struct pt_solution *pt); /* Adds a newly created congruence class CLS to worklist. */ void worklist_push (congruence_class *cls); /* Pops a class from worklist. */ congruence_class *worklist_pop (); /* Every usage of a congruence class CLS is a candidate that can split the collection of classes. Bitmap stack BMSTACK is used for bitmap allocation. */ void do_congruence_step (congruence_class *cls); /* Tests if a class CLS used as INDEXth splits any congruence classes. Bitmap stack BMSTACK is used for bitmap allocation. */ bool do_congruence_step_for_index (congruence_class *cls, unsigned int index); /* Makes pairing between a congruence class CLS and semantic ITEM. */ static void add_item_to_class (congruence_class *cls, sem_item *item); /* Disposes split map traverse function. CLS is congruence class, BSLOT is bitmap slot we want to release. DATA is mandatory, but unused argument. */ static bool release_split_map (congruence_class * const &cls, bitmap const &b, traverse_split_pair *pair); /* Process split operation for a congruence class CLS, where bitmap B splits congruence class members. DATA is used as argument of split pair. */ static bool traverse_congruence_split (congruence_class * const &cls, bitmap const &b, traverse_split_pair *pair); /* Compare function for sorting pairs in do_congruence_step_f. */ static int sort_congruence_split (const void *, const void *); /* Reads a section from LTO stream file FILE_DATA. Input block for DATA contains LEN bytes. */ void read_section (lto_file_decl_data *file_data, const char *data, size_t len); /* Removes all callgraph and varpool nodes that are marked by symtab as deleted. */ void filter_removed_items (void); /* Vector of semantic items. */ vec m_items; /* A set containing all items removed by hooks. */ hash_set m_removed_items_set; /* Hashtable of congruence classes. */ hash_table m_classes; /* Count of congruence classes. */ unsigned int m_classes_count; /* Map data structure maps symtab nodes to semantic items. */ hash_map m_symtab_node_map; /* Set to true if a splitter class is removed. */ bool splitter_class_removed; /* Global unique class id counter. */ static unsigned int class_id; /* Callgraph node removal hook holder. */ cgraph_node_hook_list *m_cgraph_node_hooks; /* Varpool node removal hook holder. */ varpool_node_hook_list *m_varpool_node_hooks; /* Bitmap stack. */ bitmap_obstack m_bmstack; /* Vector of merged variables. Needed for fixup of points-to-analysis info. */ vec m_merged_variables; /* Hash map will all references. */ ref_map m_references; }; // class sem_item_optimizer } // ipa_icf namespace