/* A type-safe hash table template. Copyright (C) 2012-2015 Free Software Foundation, Inc. Contributed by Lawrence Crowl 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 . */ /* This file implements a typed hash table. The implementation borrows from libiberty's htab_t in hashtab.h. INTRODUCTION TO TYPES Users of the hash table generally need to be aware of three types. 1. The type being placed into the hash table. This type is called the value type. 2. The type used to describe how to handle the value type within the hash table. This descriptor type provides the hash table with several things. - A typedef named 'value_type' to the value type (from above). - A static member function named 'hash' that takes a value_type pointer and returns a hashval_t value. - A typedef named 'compare_type' that is used to test when an value is found. This type is the comparison type. Usually, it will be the same as value_type. If it is not the same type, you must generally explicitly compute hash values and pass them to the hash table. - A static member function named 'equal' that takes a value_type pointer and a compare_type pointer, and returns a bool. - A static function named 'remove' that takes an value_type pointer and frees the memory allocated by it. This function is used when individual elements of the table need to be disposed of (e.g., when deleting a hash table, removing elements from the table, etc). 3. The type of the hash table itself. (More later.) In very special circumstances, users may need to know about a fourth type. 4. The template type used to describe how hash table memory is allocated. This type is called the allocator type. It is parameterized on the value type. It provides four functions. - A static member function named 'data_alloc'. This function allocates the data elements in the table. - A static member function named 'data_free'. This function deallocates the data elements in the table. Hash table are instantiated with two type arguments. * The descriptor type, (2) above. * The allocator type, (4) above. In general, you will not need to provide your own allocator type. By default, hash tables will use the class template xcallocator, which uses malloc/free for allocation. DEFINING A DESCRIPTOR TYPE The first task in using the hash table is to describe the element type. We compose this into a few steps. 1. Decide on a removal policy for values stored in the table. This header provides class templates for the two most common policies. * typed_free_remove implements the static 'remove' member function by calling free(). * typed_noop_remove implements the static 'remove' member function by doing nothing. You can use these policies by simply deriving the descriptor type from one of those class template, with the appropriate argument. Otherwise, you need to write the static 'remove' member function in the descriptor class. 2. Choose a hash function. Write the static 'hash' member function. 3. Choose an equality testing function. In most cases, its two arguments will be value_type pointers. If not, the first argument must be a value_type pointer, and the second argument a compare_type pointer. AN EXAMPLE DESCRIPTOR TYPE Suppose you want to put some_type into the hash table. You could define the descriptor type as follows. struct some_type_hasher : typed_noop_remove // Deriving from typed_noop_remove means that we get a 'remove' that does // nothing. This choice is good for raw values. { typedef some_type value_type; typedef some_type compare_type; static inline hashval_t hash (const value_type *); static inline bool equal (const value_type *, const compare_type *); }; inline hashval_t some_type_hasher::hash (const value_type *e) { ... compute and return a hash value for E ... } inline bool some_type_hasher::equal (const value_type *p1, const compare_type *p2) { ... compare P1 vs P2. Return true if they are the 'same' ... } AN EXAMPLE HASH_TABLE DECLARATION To instantiate a hash table for some_type: hash_table some_type_hash_table; There is no need to mention some_type directly, as the hash table will obtain it using some_type_hasher::value_type. You can then used any of the functions in hash_table's public interface. See hash_table for details. The interface is very similar to libiberty's htab_t. EASY DESCRIPTORS FOR POINTERS The class template pointer_hash provides everything you need to hash pointers (as opposed to what they point to). So, to instantiate a hash table over pointers to whatever_type, hash_table > whatever_type_hash_table; HASH TABLE ITERATORS The hash table provides standard C++ iterators. For example, consider a hash table of some_info. We wish to consume each element of the table: extern void consume (some_info *); We define a convenience typedef and the hash table: typedef hash_table info_table_type; info_table_type info_table; Then we write the loop in typical C++ style: for (info_table_type::iterator iter = info_table.begin (); iter != info_table.end (); ++iter) if ((*iter).status == INFO_READY) consume (&*iter); Or with common sub-expression elimination: for (info_table_type::iterator iter = info_table.begin (); iter != info_table.end (); ++iter) { some_info &elem = *iter; if (elem.status == INFO_READY) consume (&elem); } One can also use a more typical GCC style: typedef some_info *some_info_p; some_info *elem_ptr; info_table_type::iterator iter; FOR_EACH_HASH_TABLE_ELEMENT (info_table, elem_ptr, some_info_p, iter) if (elem_ptr->status == INFO_READY) consume (elem_ptr); */ #ifndef TYPED_HASHTAB_H #define TYPED_HASHTAB_H #include "ggc.h" #include "hashtab.h" #include template class hash_map; template class hash_set; /* The ordinary memory allocator. */ /* FIXME (crowl): This allocator may be extracted for wider sharing later. */ template struct xcallocator { static Type *data_alloc (size_t count); static void data_free (Type *memory); }; /* Allocate memory for COUNT data blocks. */ template inline Type * xcallocator ::data_alloc (size_t count) { return static_cast (xcalloc (count, sizeof (Type))); } /* Free memory for data blocks. */ template inline void xcallocator ::data_free (Type *memory) { return ::free (memory); } /* Helpful type for removing with free. */ template struct typed_free_remove { static inline void remove (Type *p); }; /* Remove with free. */ template inline void typed_free_remove ::remove (Type *p) { free (p); } /* Helpful type for a no-op remove. */ template struct typed_noop_remove { static inline void remove (Type *p); }; /* Remove doing nothing. */ template inline void typed_noop_remove ::remove (Type *p ATTRIBUTE_UNUSED) { } /* Pointer hash with a no-op remove method. */ template struct pointer_hash : typed_noop_remove { typedef Type *value_type; typedef Type *compare_type; typedef int store_values_directly; static inline hashval_t hash (const value_type &); static inline bool equal (const value_type &existing, const compare_type &candidate); }; template inline hashval_t pointer_hash ::hash (const value_type &candidate) { /* This is a really poor hash function, but it is what the current code uses, so I am reusing it to avoid an additional axis in testing. */ return (hashval_t) ((intptr_t)candidate >> 3); } template inline bool pointer_hash ::equal (const value_type &existing, const compare_type &candidate) { return existing == candidate; } /* Hasher for entry in gc memory. */ template struct ggc_hasher { typedef T value_type; typedef T compare_type; typedef int store_values_directly; static void remove (T) {} static void ggc_mx (T p) { extern void gt_ggc_mx (T &); gt_ggc_mx (p); } static void pch_nx (T &p) { extern void gt_pch_nx (T &); gt_pch_nx (p); } static void pch_nx (T &p, gt_pointer_operator op, void *cookie) { op (&p, cookie); } }; /* Hasher for cache entry in gc memory. */ template struct ggc_cache_hasher { typedef T value_type; typedef T compare_type; typedef int store_values_directly; static void remove (T &) {} /* Entries are weakly held because this is for caches. */ static void ggc_mx (T &) {} static void pch_nx (T &p) { extern void gt_pch_nx (T &); gt_pch_nx (p); } static void pch_nx (T &p, gt_pointer_operator op, void *cookie) { op (&p, cookie); } /* Clear out entries if they are about to be gc'd. */ static void handle_cache_entry (T &e) { if (e != HTAB_EMPTY_ENTRY && e != HTAB_DELETED_ENTRY && !ggc_marked_p (e)) e = static_cast (HTAB_DELETED_ENTRY); } }; /* Table of primes and their inversion information. */ struct prime_ent { hashval_t prime; hashval_t inv; hashval_t inv_m2; /* inverse of prime-2 */ hashval_t shift; }; extern struct prime_ent const prime_tab[]; /* Functions for computing hash table indexes. */ extern unsigned int hash_table_higher_prime_index (unsigned long n) ATTRIBUTE_PURE; /* Return X % Y using multiplicative inverse values INV and SHIFT. The multiplicative inverses computed above are for 32-bit types, and requires that we be able to compute a highpart multiply. FIX: I am not at all convinced that 3 loads, 2 multiplications, 3 shifts, and 3 additions will be faster than 1 load and 1 modulus on modern systems running a compiler. */ inline hashval_t mul_mod (hashval_t x, hashval_t y, hashval_t inv, int shift) { hashval_t t1, t2, t3, t4, q, r; t1 = ((uint64_t)x * inv) >> 32; t2 = x - t1; t3 = t2 >> 1; t4 = t1 + t3; q = t4 >> shift; r = x - (q * y); return r; } /* Compute the primary table index for HASH given current prime index. */ inline hashval_t hash_table_mod1 (hashval_t hash, unsigned int index) { const struct prime_ent *p = &prime_tab[index]; gcc_checking_assert (sizeof (hashval_t) * CHAR_BIT <= 32); return mul_mod (hash, p->prime, p->inv, p->shift); } /* Compute the secondary table index for HASH given current prime index. */ inline hashval_t hash_table_mod2 (hashval_t hash, unsigned int index) { const struct prime_ent *p = &prime_tab[index]; gcc_checking_assert (sizeof (hashval_t) * CHAR_BIT <= 32); return 1 + mul_mod (hash, p->prime - 2, p->inv_m2, p->shift); } /* The below is some template meta programming to decide if we should use the hash table partial specialization that directly stores value_type instead of pointers to value_type. If the Descriptor type defines the type Descriptor::store_values_directly then values are stored directly otherwise pointers to them are stored. */ template struct notype { typedef void type; }; template struct storage_tester { static const bool value = false; }; template struct storage_tester::type> { static const bool value = true; }; template struct has_is_deleted { template struct helper {}; template static char test (helper *); template static int test (...); static const bool value = sizeof (test (0)) == sizeof (char); }; template::value> struct is_deleted_helper { static inline bool call (Type &v) { return Traits::is_deleted (v); } }; template struct is_deleted_helper { static inline bool call (Type *v) { return v == HTAB_DELETED_ENTRY; } }; template struct has_is_empty { template struct helper {}; template static char test (helper *); template static int test (...); static const bool value = sizeof (test (0)) == sizeof (char); }; template::value> struct is_empty_helper { static inline bool call (Type &v) { return Traits::is_empty (v); } }; template struct is_empty_helper { static inline bool call (Type *v) { return v == HTAB_EMPTY_ENTRY; } }; template struct has_mark_deleted { template struct helper {}; template static char test (helper *); template static int test (...); static const bool value = sizeof (test (0)) == sizeof (char); }; template::value> struct mark_deleted_helper { static inline void call (Type &v) { Traits::mark_deleted (v); } }; template struct mark_deleted_helper { static inline void call (Type *&v) { v = static_cast (HTAB_DELETED_ENTRY); } }; template struct has_mark_empty { template struct helper {}; template static char test (helper *); template static int test (...); static const bool value = sizeof (test (0)) == sizeof (char); }; template::value> struct mark_empty_helper { static inline void call (Type &v) { Traits::mark_empty (v); } }; template struct mark_empty_helper { static inline void call (Type *&v) { v = static_cast (HTAB_EMPTY_ENTRY); } }; /* User-facing hash table type. The table stores elements of type Descriptor::value_type, or pointers to objects of type value_type if the descriptor does not define the type store_values_directly. It hashes values with the hash member function. The table currently works with relatively weak hash functions. Use typed_pointer_hash when hashing pointers instead of objects. It compares elements with the equal member function. Two elements with the same hash may not be equal. Use typed_pointer_equal when hashing pointers instead of objects. It removes elements with the remove member function. This feature is useful for freeing memory. Derive from typed_null_remove when not freeing objects. Derive from typed_free_remove when doing a simple object free. Specify the template Allocator to allocate and free memory. The default is xcallocator. Storage is an implementation detail and should not be used outside the hash table code. */ template class Allocator= xcallocator, bool Storage = storage_tester::value> class hash_table { }; template class Allocator> class hash_table { typedef typename Descriptor::value_type value_type; typedef typename Descriptor::compare_type compare_type; public: hash_table (size_t); ~hash_table (); /* Current size (in entries) of the hash table. */ size_t size () const { return m_size; } /* Return the current number of elements in this hash table. */ size_t elements () const { return m_n_elements - m_n_deleted; } /* Return the current number of elements in this hash table. */ size_t elements_with_deleted () const { return m_n_elements; } /* This function clears all entries in the given hash table. */ void empty (); /* This function clears a specified SLOT in a hash table. It is useful when you've already done the lookup and don't want to do it again. */ void clear_slot (value_type **); /* This function searches for a hash table entry equal to the given COMPARABLE element starting with the given HASH value. It cannot be used to insert or delete an element. */ value_type *find_with_hash (const compare_type *, hashval_t); /* Like find_slot_with_hash, but compute the hash value from the element. */ value_type *find (const value_type *value) { return find_with_hash (value, Descriptor::hash (value)); } value_type **find_slot (const value_type *value, insert_option insert) { return find_slot_with_hash (value, Descriptor::hash (value), insert); } /* This function searches for a hash table slot containing an entry equal to the given COMPARABLE element and starting with the given HASH. To delete an entry, call this with insert=NO_INSERT, then call clear_slot on the slot returned (possibly after doing some checks). To insert an entry, call this with insert=INSERT, then write the value you want into the returned slot. When inserting an entry, NULL may be returned if memory allocation fails. */ value_type **find_slot_with_hash (const compare_type *comparable, hashval_t hash, enum insert_option insert); /* This function deletes an element with the given COMPARABLE value from hash table starting with the given HASH. If there is no matching element in the hash table, this function does nothing. */ void remove_elt_with_hash (const compare_type *, hashval_t); /* Like remove_elt_with_hash, but compute the hash value from the element. */ void remove_elt (const value_type *value) { remove_elt_with_hash (value, Descriptor::hash (value)); } /* This function scans over the entire hash table calling CALLBACK for each live entry. If CALLBACK returns false, the iteration stops. ARGUMENT is passed as CALLBACK's second argument. */ template void traverse_noresize (Argument argument); /* Like traverse_noresize, but does resize the table when it is too empty to improve effectivity of subsequent calls. */ template void traverse (Argument argument); class iterator { public: iterator () : m_slot (NULL), m_limit (NULL) {} iterator (value_type **slot, value_type **limit) : m_slot (slot), m_limit (limit) {} inline value_type *operator * () { return *m_slot; } void slide (); inline iterator &operator ++ (); bool operator != (const iterator &other) const { return m_slot != other.m_slot || m_limit != other.m_limit; } private: value_type **m_slot; value_type **m_limit; }; iterator begin () const { iterator iter (m_entries, m_entries + m_size); iter.slide (); return iter; } iterator end () const { return iterator (); } double collisions () const { return m_searches ? static_cast (m_collisions) / m_searches : 0; } private: value_type **find_empty_slot_for_expand (hashval_t); void expand (); /* Table itself. */ typename Descriptor::value_type **m_entries; size_t m_size; /* Current number of elements including also deleted elements. */ size_t m_n_elements; /* Current number of deleted elements in the table. */ size_t m_n_deleted; /* The following member is used for debugging. Its value is number of all calls of `htab_find_slot' for the hash table. */ unsigned int m_searches; /* The following member is used for debugging. Its value is number of collisions fixed for time of work with the hash table. */ unsigned int m_collisions; /* Current size (in entries) of the hash table, as an index into the table of primes. */ unsigned int m_size_prime_index; }; template class Allocator> hash_table::hash_table (size_t size) : m_n_elements (0), m_n_deleted (0), m_searches (0), m_collisions (0) { unsigned int size_prime_index; size_prime_index = hash_table_higher_prime_index (size); size = prime_tab[size_prime_index].prime; m_entries = Allocator ::data_alloc (size); gcc_assert (m_entries != NULL); m_size = size; m_size_prime_index = size_prime_index; } template class Allocator> hash_table::~hash_table () { for (size_t i = m_size - 1; i < m_size; i--) if (m_entries[i] != HTAB_EMPTY_ENTRY && m_entries[i] != HTAB_DELETED_ENTRY) Descriptor::remove (m_entries[i]); Allocator ::data_free (m_entries); } /* Similar to find_slot, but without several unwanted side effects: - Does not call equal when it finds an existing entry. - Does not change the count of elements/searches/collisions in the hash table. This function also assumes there are no deleted entries in the table. HASH is the hash value for the element to be inserted. */ template class Allocator> typename hash_table::value_type ** hash_table ::find_empty_slot_for_expand (hashval_t hash) { hashval_t index = hash_table_mod1 (hash, m_size_prime_index); size_t size = m_size; value_type **slot = m_entries + index; hashval_t hash2; if (*slot == HTAB_EMPTY_ENTRY) return slot; gcc_checking_assert (*slot != HTAB_DELETED_ENTRY); hash2 = hash_table_mod2 (hash, m_size_prime_index); for (;;) { index += hash2; if (index >= size) index -= size; slot = m_entries + index; if (*slot == HTAB_EMPTY_ENTRY) return slot; gcc_checking_assert (*slot != HTAB_DELETED_ENTRY); } } /* The following function changes size of memory allocated for the entries and repeatedly inserts the table elements. The occupancy of the table after the call will be about 50%. Naturally the hash table must already exist. Remember also that the place of the table entries is changed. If memory allocation fails, this function will abort. */ template class Allocator> void hash_table::expand () { value_type **oentries = m_entries; unsigned int oindex = m_size_prime_index; size_t osize = size (); value_type **olimit = oentries + osize; size_t elts = elements (); /* Resize only when table after removal of unused elements is either too full or too empty. */ unsigned int nindex; size_t nsize; if (elts * 2 > osize || (elts * 8 < osize && osize > 32)) { nindex = hash_table_higher_prime_index (elts * 2); nsize = prime_tab[nindex].prime; } else { nindex = oindex; nsize = osize; } value_type **nentries = Allocator ::data_alloc (nsize); gcc_assert (nentries != NULL); m_entries = nentries; m_size = nsize; m_size_prime_index = nindex; m_n_elements -= m_n_deleted; m_n_deleted = 0; value_type **p = oentries; do { value_type *x = *p; if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY) { value_type **q = find_empty_slot_for_expand (Descriptor::hash (x)); *q = x; } p++; } while (p < olimit); Allocator ::data_free (oentries); } template class Allocator> void hash_table::empty () { size_t size = m_size; value_type **entries = m_entries; int i; for (i = size - 1; i >= 0; i--) if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY) Descriptor::remove (entries[i]); /* Instead of clearing megabyte, downsize the table. */ if (size > 1024*1024 / sizeof (PTR)) { int nindex = hash_table_higher_prime_index (1024 / sizeof (PTR)); int nsize = prime_tab[nindex].prime; Allocator ::data_free (m_entries); m_entries = Allocator ::data_alloc (nsize); m_size = nsize; m_size_prime_index = nindex; } else memset (entries, 0, size * sizeof (value_type *)); m_n_deleted = 0; m_n_elements = 0; } /* This function clears a specified SLOT in a hash table. It is useful when you've already done the lookup and don't want to do it again. */ template class Allocator> void hash_table::clear_slot (value_type **slot) { gcc_checking_assert (!(slot < m_entries || slot >= m_entries + size () || *slot == HTAB_EMPTY_ENTRY || *slot == HTAB_DELETED_ENTRY)); Descriptor::remove (*slot); *slot = static_cast (HTAB_DELETED_ENTRY); m_n_deleted++; } /* This function searches for a hash table entry equal to the given COMPARABLE element starting with the given HASH value. It cannot be used to insert or delete an element. */ template class Allocator> typename hash_table::value_type * hash_table ::find_with_hash (const compare_type *comparable, hashval_t hash) { m_searches++; size_t size = m_size; hashval_t index = hash_table_mod1 (hash, m_size_prime_index); value_type *entry = m_entries[index]; if (entry == HTAB_EMPTY_ENTRY || (entry != HTAB_DELETED_ENTRY && Descriptor::equal (entry, comparable))) return entry; hashval_t hash2 = hash_table_mod2 (hash, m_size_prime_index); for (;;) { m_collisions++; index += hash2; if (index >= size) index -= size; entry = m_entries[index]; if (entry == HTAB_EMPTY_ENTRY || (entry != HTAB_DELETED_ENTRY && Descriptor::equal (entry, comparable))) return entry; } } /* This function searches for a hash table slot containing an entry equal to the given COMPARABLE element and starting with the given HASH. To delete an entry, call this with insert=NO_INSERT, then call clear_slot on the slot returned (possibly after doing some checks). To insert an entry, call this with insert=INSERT, then write the value you want into the returned slot. When inserting an entry, NULL may be returned if memory allocation fails. */ template class Allocator> typename hash_table::value_type ** hash_table ::find_slot_with_hash (const compare_type *comparable, hashval_t hash, enum insert_option insert) { if (insert == INSERT && m_size * 3 <= m_n_elements * 4) expand (); m_searches++; value_type **first_deleted_slot = NULL; hashval_t index = hash_table_mod1 (hash, m_size_prime_index); hashval_t hash2 = hash_table_mod2 (hash, m_size_prime_index); value_type *entry = m_entries[index]; size_t size = m_size; if (entry == HTAB_EMPTY_ENTRY) goto empty_entry; else if (entry == HTAB_DELETED_ENTRY) first_deleted_slot = &m_entries[index]; else if (Descriptor::equal (entry, comparable)) return &m_entries[index]; for (;;) { m_collisions++; index += hash2; if (index >= size) index -= size; entry = m_entries[index]; if (entry == HTAB_EMPTY_ENTRY) goto empty_entry; else if (entry == HTAB_DELETED_ENTRY) { if (!first_deleted_slot) first_deleted_slot = &m_entries[index]; } else if (Descriptor::equal (entry, comparable)) return &m_entries[index]; } empty_entry: if (insert == NO_INSERT) return NULL; if (first_deleted_slot) { m_n_deleted--; *first_deleted_slot = static_cast (HTAB_EMPTY_ENTRY); return first_deleted_slot; } m_n_elements++; return &m_entries[index]; } /* This function deletes an element with the given COMPARABLE value from hash table starting with the given HASH. If there is no matching element in the hash table, this function does nothing. */ template class Allocator> void hash_table ::remove_elt_with_hash (const compare_type *comparable, hashval_t hash) { value_type **slot = find_slot_with_hash (comparable, hash, NO_INSERT); if (*slot == HTAB_EMPTY_ENTRY) return; Descriptor::remove (*slot); *slot = static_cast (HTAB_DELETED_ENTRY); m_n_deleted++; } /* This function scans over the entire hash table calling CALLBACK for each live entry. If CALLBACK returns false, the iteration stops. ARGUMENT is passed as CALLBACK's second argument. */ template class Allocator> template::value_type **slot, Argument argument)> void hash_table::traverse_noresize (Argument argument) { value_type **slot = m_entries; value_type **limit = slot + size (); do { value_type *x = *slot; if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY) if (! Callback (slot, argument)) break; } while (++slot < limit); } /* Like traverse_noresize, but does resize the table when it is too empty to improve effectivity of subsequent calls. */ template class Allocator> template ::value_type **slot, Argument argument)> void hash_table::traverse (Argument argument) { size_t size = m_size; if (elements () * 8 < size && size > 32) expand (); traverse_noresize (argument); } /* Slide down the iterator slots until an active entry is found. */ template class Allocator> void hash_table::iterator::slide () { for ( ; m_slot < m_limit; ++m_slot ) { value_type *x = *m_slot; if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY) return; } m_slot = NULL; m_limit = NULL; } /* Bump the iterator. */ template class Allocator> inline typename hash_table::iterator & hash_table::iterator::operator ++ () { ++m_slot; slide (); return *this; } /* A partial specialization used when values should be stored directly. */ template class Allocator> class hash_table { typedef typename Descriptor::value_type value_type; typedef typename Descriptor::compare_type compare_type; public: explicit hash_table (size_t, bool ggc = false); ~hash_table (); /* Create a hash_table in gc memory. */ static hash_table * create_ggc (size_t n) { hash_table *table = ggc_alloc (); new (table) hash_table (n, true); return table; } /* Current size (in entries) of the hash table. */ size_t size () const { return m_size; } /* Return the current number of elements in this hash table. */ size_t elements () const { return m_n_elements - m_n_deleted; } /* Return the current number of elements in this hash table. */ size_t elements_with_deleted () const { return m_n_elements; } /* This function clears all entries in the given hash table. */ void empty (); /* This function clears a specified SLOT in a hash table. It is useful when you've already done the lookup and don't want to do it again. */ void clear_slot (value_type *); /* This function searches for a hash table entry equal to the given COMPARABLE element starting with the given HASH value. It cannot be used to insert or delete an element. */ value_type &find_with_hash (const compare_type &, hashval_t); /* Like find_slot_with_hash, but compute the hash value from the element. */ value_type &find (const value_type &value) { return find_with_hash (value, Descriptor::hash (value)); } value_type *find_slot (const value_type &value, insert_option insert) { return find_slot_with_hash (value, Descriptor::hash (value), insert); } /* This function searches for a hash table slot containing an entry equal to the given COMPARABLE element and starting with the given HASH. To delete an entry, call this with insert=NO_INSERT, then call clear_slot on the slot returned (possibly after doing some checks). To insert an entry, call this with insert=INSERT, then write the value you want into the returned slot. When inserting an entry, NULL may be returned if memory allocation fails. */ value_type *find_slot_with_hash (const compare_type &comparable, hashval_t hash, enum insert_option insert); /* This function deletes an element with the given COMPARABLE value from hash table starting with the given HASH. If there is no matching element in the hash table, this function does nothing. */ void remove_elt_with_hash (const compare_type &, hashval_t); /* Like remove_elt_with_hash, but compute the hash value from the element. */ void remove_elt (const value_type &value) { remove_elt_with_hash (value, Descriptor::hash (value)); } /* This function scans over the entire hash table calling CALLBACK for each live entry. If CALLBACK returns false, the iteration stops. ARGUMENT is passed as CALLBACK's second argument. */ template void traverse_noresize (Argument argument); /* Like traverse_noresize, but does resize the table when it is too empty to improve effectivity of subsequent calls. */ template void traverse (Argument argument); class iterator { public: iterator () : m_slot (NULL), m_limit (NULL) {} iterator (value_type *slot, value_type *limit) : m_slot (slot), m_limit (limit) {} inline value_type &operator * () { return *m_slot; } void slide (); inline iterator &operator ++ (); bool operator != (const iterator &other) const { return m_slot != other.m_slot || m_limit != other.m_limit; } private: value_type *m_slot; value_type *m_limit; }; iterator begin () const { iterator iter (m_entries, m_entries + m_size); iter.slide (); return iter; } iterator end () const { return iterator (); } double collisions () const { return m_searches ? static_cast (m_collisions) / m_searches : 0; } private: template friend void gt_ggc_mx (hash_table *); template friend void gt_pch_nx (hash_table *); template friend void hashtab_entry_note_pointers (void *, void *, gt_pointer_operator, void *); template friend void gt_pch_nx (hash_map *, gt_pointer_operator, void *); template friend void gt_pch_nx (hash_set *, gt_pointer_operator, void *); template friend void gt_pch_nx (hash_table *, gt_pointer_operator, void *); value_type *alloc_entries (size_t n) const; value_type *find_empty_slot_for_expand (hashval_t); void expand (); static bool is_deleted (value_type &v) { return is_deleted_helper::call (v); } static bool is_empty (value_type &v) { return is_empty_helper::call (v); } static void mark_deleted (value_type &v) { return mark_deleted_helper::call (v); } static void mark_empty (value_type &v) { return mark_empty_helper::call (v); } /* Table itself. */ typename Descriptor::value_type *m_entries; size_t m_size; /* Current number of elements including also deleted elements. */ size_t m_n_elements; /* Current number of deleted elements in the table. */ size_t m_n_deleted; /* The following member is used for debugging. Its value is number of all calls of `htab_find_slot' for the hash table. */ unsigned int m_searches; /* The following member is used for debugging. Its value is number of collisions fixed for time of work with the hash table. */ unsigned int m_collisions; /* Current size (in entries) of the hash table, as an index into the table of primes. */ unsigned int m_size_prime_index; /* if m_entries is stored in ggc memory. */ bool m_ggc; }; template class Allocator> hash_table::hash_table (size_t size, bool ggc) : m_n_elements (0), m_n_deleted (0), m_searches (0), m_collisions (0), m_ggc (ggc) { unsigned int size_prime_index; size_prime_index = hash_table_higher_prime_index (size); size = prime_tab[size_prime_index].prime; m_entries = alloc_entries (size); m_size = size; m_size_prime_index = size_prime_index; } template class Allocator> hash_table::~hash_table () { for (size_t i = m_size - 1; i < m_size; i--) if (!is_empty (m_entries[i]) && !is_deleted (m_entries[i])) Descriptor::remove (m_entries[i]); if (!m_ggc) Allocator ::data_free (m_entries); else ggc_free (m_entries); } /* This function returns an array of empty hash table elements. */ template class Allocator> inline typename hash_table::value_type * hash_table::alloc_entries (size_t n) const { value_type *nentries; if (!m_ggc) nentries = Allocator ::data_alloc (n); else nentries = ::ggc_cleared_vec_alloc (n); gcc_assert (nentries != NULL); for (size_t i = 0; i < n; i++) mark_empty (nentries[i]); return nentries; } /* Similar to find_slot, but without several unwanted side effects: - Does not call equal when it finds an existing entry. - Does not change the count of elements/searches/collisions in the hash table. This function also assumes there are no deleted entries in the table. HASH is the hash value for the element to be inserted. */ template class Allocator> typename hash_table::value_type * hash_table ::find_empty_slot_for_expand (hashval_t hash) { hashval_t index = hash_table_mod1 (hash, m_size_prime_index); size_t size = m_size; value_type *slot = m_entries + index; hashval_t hash2; if (is_empty (*slot)) return slot; #ifdef ENABLE_CHECKING gcc_checking_assert (!is_deleted (*slot)); #endif hash2 = hash_table_mod2 (hash, m_size_prime_index); for (;;) { index += hash2; if (index >= size) index -= size; slot = m_entries + index; if (is_empty (*slot)) return slot; #ifdef ENABLE_CHECKING gcc_checking_assert (!is_deleted (*slot)); #endif } } /* The following function changes size of memory allocated for the entries and repeatedly inserts the table elements. The occupancy of the table after the call will be about 50%. Naturally the hash table must already exist. Remember also that the place of the table entries is changed. If memory allocation fails, this function will abort. */ template class Allocator> void hash_table::expand () { value_type *oentries = m_entries; unsigned int oindex = m_size_prime_index; size_t osize = size (); value_type *olimit = oentries + osize; size_t elts = elements (); /* Resize only when table after removal of unused elements is either too full or too empty. */ unsigned int nindex; size_t nsize; if (elts * 2 > osize || (elts * 8 < osize && osize > 32)) { nindex = hash_table_higher_prime_index (elts * 2); nsize = prime_tab[nindex].prime; } else { nindex = oindex; nsize = osize; } value_type *nentries = alloc_entries (nsize); m_entries = nentries; m_size = nsize; m_size_prime_index = nindex; m_n_elements -= m_n_deleted; m_n_deleted = 0; value_type *p = oentries; do { value_type &x = *p; if (!is_empty (x) && !is_deleted (x)) { value_type *q = find_empty_slot_for_expand (Descriptor::hash (x)); *q = x; } p++; } while (p < olimit); if (!m_ggc) Allocator ::data_free (oentries); else ggc_free (oentries); } template class Allocator> void hash_table::empty () { size_t size = m_size; value_type *entries = m_entries; int i; for (i = size - 1; i >= 0; i--) if (!is_empty (entries[i]) && !is_deleted (entries[i])) Descriptor::remove (entries[i]); /* Instead of clearing megabyte, downsize the table. */ if (size > 1024*1024 / sizeof (PTR)) { int nindex = hash_table_higher_prime_index (1024 / sizeof (PTR)); int nsize = prime_tab[nindex].prime; if (!m_ggc) Allocator ::data_free (m_entries); else ggc_free (m_entries); m_entries = alloc_entries (nsize); m_size = nsize; m_size_prime_index = nindex; } else memset (entries, 0, size * sizeof (value_type)); m_n_deleted = 0; m_n_elements = 0; } /* This function clears a specified SLOT in a hash table. It is useful when you've already done the lookup and don't want to do it again. */ template class Allocator> void hash_table::clear_slot (value_type *slot) { gcc_checking_assert (!(slot < m_entries || slot >= m_entries + size () || is_empty (*slot) || is_deleted (*slot))); Descriptor::remove (*slot); mark_deleted (*slot); m_n_deleted++; } /* This function searches for a hash table entry equal to the given COMPARABLE element starting with the given HASH value. It cannot be used to insert or delete an element. */ template class Allocator> typename hash_table::value_type & hash_table ::find_with_hash (const compare_type &comparable, hashval_t hash) { m_searches++; size_t size = m_size; hashval_t index = hash_table_mod1 (hash, m_size_prime_index); value_type *entry = &m_entries[index]; if (is_empty (*entry) || (!is_deleted (*entry) && Descriptor::equal (*entry, comparable))) return *entry; hashval_t hash2 = hash_table_mod2 (hash, m_size_prime_index); for (;;) { m_collisions++; index += hash2; if (index >= size) index -= size; entry = &m_entries[index]; if (is_empty (*entry) || (!is_deleted (*entry) && Descriptor::equal (*entry, comparable))) return *entry; } } /* This function searches for a hash table slot containing an entry equal to the given COMPARABLE element and starting with the given HASH. To delete an entry, call this with insert=NO_INSERT, then call clear_slot on the slot returned (possibly after doing some checks). To insert an entry, call this with insert=INSERT, then write the value you want into the returned slot. When inserting an entry, NULL may be returned if memory allocation fails. */ template class Allocator> typename hash_table::value_type * hash_table ::find_slot_with_hash (const compare_type &comparable, hashval_t hash, enum insert_option insert) { if (insert == INSERT && m_size * 3 <= m_n_elements * 4) expand (); m_searches++; value_type *first_deleted_slot = NULL; hashval_t index = hash_table_mod1 (hash, m_size_prime_index); hashval_t hash2 = hash_table_mod2 (hash, m_size_prime_index); value_type *entry = &m_entries[index]; size_t size = m_size; if (is_empty (*entry)) goto empty_entry; else if (is_deleted (*entry)) first_deleted_slot = &m_entries[index]; else if (Descriptor::equal (*entry, comparable)) return &m_entries[index]; for (;;) { m_collisions++; index += hash2; if (index >= size) index -= size; entry = &m_entries[index]; if (is_empty (*entry)) goto empty_entry; else if (is_deleted (*entry)) { if (!first_deleted_slot) first_deleted_slot = &m_entries[index]; } else if (Descriptor::equal (*entry, comparable)) return &m_entries[index]; } empty_entry: if (insert == NO_INSERT) return NULL; if (first_deleted_slot) { m_n_deleted--; mark_empty (*first_deleted_slot); return first_deleted_slot; } m_n_elements++; return &m_entries[index]; } /* This function deletes an element with the given COMPARABLE value from hash table starting with the given HASH. If there is no matching element in the hash table, this function does nothing. */ template class Allocator> void hash_table ::remove_elt_with_hash (const compare_type &comparable, hashval_t hash) { value_type *slot = find_slot_with_hash (comparable, hash, NO_INSERT); if (is_empty (*slot)) return; Descriptor::remove (*slot); mark_deleted (*slot); m_n_deleted++; } /* This function scans over the entire hash table calling CALLBACK for each live entry. If CALLBACK returns false, the iteration stops. ARGUMENT is passed as CALLBACK's second argument. */ template class Allocator> template::value_type *slot, Argument argument)> void hash_table::traverse_noresize (Argument argument) { value_type *slot = m_entries; value_type *limit = slot + size (); do { value_type &x = *slot; if (!is_empty (x) && !is_deleted (x)) if (! Callback (slot, argument)) break; } while (++slot < limit); } /* Like traverse_noresize, but does resize the table when it is too empty to improve effectivity of subsequent calls. */ template class Allocator> template ::value_type *slot, Argument argument)> void hash_table::traverse (Argument argument) { size_t size = m_size; if (elements () * 8 < size && size > 32) expand (); traverse_noresize (argument); } /* Slide down the iterator slots until an active entry is found. */ template class Allocator> void hash_table::iterator::slide () { for ( ; m_slot < m_limit; ++m_slot ) { value_type &x = *m_slot; if (!is_empty (x) && !is_deleted (x)) return; } m_slot = NULL; m_limit = NULL; } /* Bump the iterator. */ template class Allocator> inline typename hash_table::iterator & hash_table::iterator::operator ++ () { ++m_slot; slide (); return *this; } /* Iterate through the elements of hash_table HTAB, using hash_table <....>::iterator ITER, storing each element in RESULT, which is of type TYPE. */ #define FOR_EACH_HASH_TABLE_ELEMENT(HTAB, RESULT, TYPE, ITER) \ for ((ITER) = (HTAB).begin (); \ (ITER) != (HTAB).end () ? (RESULT = *(ITER) , true) : false; \ ++(ITER)) /* ggc walking routines. */ template static inline void gt_ggc_mx (hash_table *h) { typedef hash_table table; if (!ggc_test_and_set_mark (h->m_entries)) return; for (size_t i = 0; i < h->m_size; i++) { if (table::is_empty (h->m_entries[i]) || table::is_deleted (h->m_entries[i])) continue; E::ggc_mx (h->m_entries[i]); } } template static inline void hashtab_entry_note_pointers (void *obj, void *h, gt_pointer_operator op, void *cookie) { hash_table *map = static_cast *> (h); gcc_checking_assert (map->m_entries == obj); for (size_t i = 0; i < map->m_size; i++) { typedef hash_table table; if (table::is_empty (map->m_entries[i]) || table::is_deleted (map->m_entries[i])) continue; D::pch_nx (map->m_entries[i], op, cookie); } } template static void gt_pch_nx (hash_table *h) { bool success = gt_pch_note_object (h->m_entries, h, hashtab_entry_note_pointers); gcc_checking_assert (success); for (size_t i = 0; i < h->m_size; i++) { if (hash_table::is_empty (h->m_entries[i]) || hash_table::is_deleted (h->m_entries[i])) continue; D::pch_nx (h->m_entries[i]); } } template static inline void gt_pch_nx (hash_table *h, gt_pointer_operator op, void *cookie) { op (&h->m_entries, cookie); } template inline void gt_cleare_cache (hash_table *h) { if (!h) return; for (typename hash_table::iterator iter = h->begin (); iter != h->end (); ++iter) H::handle_cache_entry (*iter); } #endif /* TYPED_HASHTAB_H */