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[/] [openrisc/] [trunk/] [gnu-old/] [gcc-4.2.2/] [gcc/] [pointer-set.c] - Rev 154
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/* Set operations on pointers Copyright (C) 2004, 2006, 2007 Free Software Foundation, Inc. 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 <http://www.gnu.org/licenses/>. */ #include "config.h" #include "system.h" #include "pointer-set.h" /* A pointer set is represented as a simple open-addressing hash table. Simplifications: The hash code is based on the value of the pointer, not what it points to. The number of buckets is always a power of 2. Null pointers are a reserved value. Deletion is not supported (yet). There is no mechanism for user control of hash function, equality comparison, initial size, or resizing policy. */ struct pointer_set_t { size_t log_slots; size_t n_slots; /* n_slots = 2^log_slots */ size_t n_elements; void **slots; }; /* Use the multiplicative method, as described in Knuth 6.4, to obtain a hash code for P in the range [0, MAX). MAX == 2^LOGMAX. Summary of this method: Multiply p by some number A that's relatively prime to 2^sizeof(size_t). The result is two words. Discard the most significant word, and return the most significant N bits of the least significant word. As suggested by Knuth, our choice for A is the integer part of (ULONG_MAX + 1.0) / phi, where phi is the golden ratio. We don't need to do anything special for full-width multiplication because we're only interested in the least significant word of the product, and unsigned arithmetic in C is modulo the word size. */ static inline size_t hash1 (const void *p, unsigned long max, unsigned long logmax) { #if HOST_BITS_PER_LONG == 32 const unsigned long A = 0x9e3779b9u; #elif HOST_BITS_PER_LONG == 64 const unsigned long A = 0x9e3779b97f4a7c16ul; #else const unsigned long A = (ULONG_MAX + 1.0L) * 0.6180339887498948482045868343656381177203L; #endif const unsigned long shift = HOST_BITS_PER_LONG - logmax; return ((A * (unsigned long) p) >> shift) & (max - 1); } /* Allocate an empty pointer set. */ struct pointer_set_t * pointer_set_create (void) { struct pointer_set_t *result = XNEW (struct pointer_set_t); result->n_elements = 0; result->log_slots = 8; result->n_slots = (size_t) 1 << result->log_slots; result->slots = XCNEWVEC (void *, result->n_slots); return result; } /* Reclaims all memory associated with PSET. */ void pointer_set_destroy (struct pointer_set_t *pset) { XDELETEVEC (pset->slots); XDELETE (pset); } /* Returns nonzero if PSET contains P. P must be nonnull. Collisions are resolved by linear probing. */ int pointer_set_contains (struct pointer_set_t *pset, void *p) { size_t n = hash1 (p, pset->n_slots, pset->log_slots); while (true) { if (pset->slots[n] == p) return 1; else if (pset->slots[n] == 0) return 0; else { ++n; if (n == pset->n_slots) n = 0; } } } /* Subroutine of pointer_set_insert. Return the insertion slot for P into an empty element of SLOTS, an array of length N_SLOTS. */ static inline size_t insert_aux (void *p, void **slots, size_t n_slots, size_t log_slots) { size_t n = hash1 (p, n_slots, log_slots); while (true) { if (slots[n] == p || slots[n] == 0) return n; else { ++n; if (n == n_slots) n = 0; } } } /* Inserts P into PSET if it wasn't already there. Returns nonzero if it was already there. P must be nonnull. */ int pointer_set_insert (struct pointer_set_t *pset, void *p) { size_t n; /* For simplicity, expand the set even if P is already there. This can be superfluous but can happen at most once. */ if (pset->n_elements > pset->n_slots / 4) { size_t new_log_slots = pset->log_slots + 1; size_t new_n_slots = pset->n_slots * 2; void **new_slots = XCNEWVEC (void *, new_n_slots); size_t i; for (i = 0; i < pset->n_slots; ++i) { void *value = pset->slots[i]; n = insert_aux (value, new_slots, new_n_slots, new_log_slots); new_slots[n] = value; } XDELETEVEC (pset->slots); pset->n_slots = new_n_slots; pset->log_slots = new_log_slots; pset->slots = new_slots; } n = insert_aux (p, pset->slots, pset->n_slots, pset->log_slots); if (pset->slots[n]) return 1; pset->slots[n] = p; ++pset->n_elements; return 0; } /* Pass each pointer in PSET to the function in FN, together with the fixed parameter DATA. If FN returns false, the iteration stops. */ void pointer_set_traverse (struct pointer_set_t *pset, bool (*fn) (void *, void *), void *data) { size_t i; for (i = 0; i < pset->n_slots; ++i) if (pset->slots[i] && !fn (pset->slots[i], data)) break; } /* A pointer map is represented the same way as a pointer_set, so the hash code is based on the address of the key, rather than its contents. Null keys are a reserved value. Deletion is not supported (yet). There is no mechanism for user control of hash function, equality comparison, initial size, or resizing policy. */ struct pointer_map_t { size_t log_slots; size_t n_slots; /* n_slots = 2^log_slots */ size_t n_elements; void **keys; void **values; }; /* Allocate an empty pointer map. */ struct pointer_map_t * pointer_map_create (void) { struct pointer_map_t *result = XNEW (struct pointer_map_t); result->n_elements = 0; result->log_slots = 8; result->n_slots = (size_t) 1 << result->log_slots; result->keys = XCNEWVEC (void *, result->n_slots); result->values = XCNEWVEC (void *, result->n_slots); return result; } /* Reclaims all memory associated with PMAP. */ void pointer_map_destroy (struct pointer_map_t *pmap) { XDELETEVEC (pmap->keys); XDELETEVEC (pmap->values); XDELETE (pmap); } /* Returns a pointer to the value to which P maps, if PMAP contains P. P must be nonnull. Return NULL if PMAP does not contain P. Collisions are resolved by linear probing. */ void ** pointer_map_contains (struct pointer_map_t *pmap, void *p) { size_t n = hash1 (p, pmap->n_slots, pmap->log_slots); while (true) { if (pmap->keys[n] == p) return &pmap->values[n]; else if (pmap->keys[n] == 0) return NULL; else { ++n; if (n == pmap->n_slots) n = 0; } } } /* Inserts P into PMAP if it wasn't already there. Returns a pointer to the value. P must be nonnull. */ void ** pointer_map_insert (struct pointer_map_t *pmap, void *p) { size_t n; /* For simplicity, expand the map even if P is already there. This can be superfluous but can happen at most once. */ if (pmap->n_elements > pmap->n_slots / 4) { size_t new_log_slots = pmap->log_slots + 1; size_t new_n_slots = pmap->n_slots * 2; void **new_keys = XCNEWVEC (void *, new_n_slots); void **new_values = XCNEWVEC (void *, new_n_slots); size_t i; for (i = 0; i < pmap->n_slots; ++i) if (pmap->keys[i]) { void *key = pmap->keys[i]; n = insert_aux (key, new_keys, new_n_slots, new_log_slots); new_keys[n] = key; new_values[n] = pmap->values[i]; } XDELETEVEC (pmap->keys); XDELETEVEC (pmap->values); pmap->n_slots = new_n_slots; pmap->log_slots = new_log_slots; pmap->keys = new_keys; pmap->values = new_values; } n = insert_aux (p, pmap->keys, pmap->n_slots, pmap->log_slots); if (!pmap->keys[n]) { ++pmap->n_elements; pmap->keys[n] = p; } return &pmap->values[n]; } /* Pass each pointer in PMAP to the function in FN, together with the pointer to the value and the fixed parameter DATA. If FN returns false, the iteration stops. */ void pointer_map_traverse (struct pointer_map_t *pmap, bool (*fn) (void *, void **, void *), void *data) { size_t i; for (i = 0; i < pmap->n_slots; ++i) if (pmap->keys[i] && !fn (pmap->keys[i], &pmap->values[i], data)) break; }
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