diff options
Diffstat (limited to 'libiberty/hashtab.c')
| -rw-r--r-- | libiberty/hashtab.c | 233 |
1 files changed, 171 insertions, 62 deletions
diff --git a/libiberty/hashtab.c b/libiberty/hashtab.c index 2639428..6e7a44b 100644 --- a/libiberty/hashtab.c +++ b/libiberty/hashtab.c @@ -1,5 +1,6 @@ /* An expandable hash tables datatype. - Copyright (C) 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. + Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004 + Free Software Foundation, Inc. Contributed by Vladimir Makarov (vmakarov@cygnus.com). This file is part of the libiberty library. @@ -40,20 +41,29 @@ Boston, MA 02111-1307, USA. */ #ifdef HAVE_STDLIB_H #include <stdlib.h> #endif - #ifdef HAVE_STRING_H #include <string.h> #endif - #ifdef HAVE_MALLOC_H #include <malloc.h> #endif +#ifdef HAVE_LIMITS_H +#include <limits.h> +#endif +#ifdef HAVE_STDINT_H +#include <stdint.h> +#endif #include <stdio.h> #include "libiberty.h" +#include "ansidecl.h" #include "hashtab.h" +#ifndef CHAR_BIT +#define CHAR_BIT 8 +#endif + /* This macro defines reserved value for empty table entry. */ #define EMPTY_ENTRY ((PTR) 0) @@ -63,7 +73,10 @@ Boston, MA 02111-1307, USA. */ #define DELETED_ENTRY ((PTR) 1) -static unsigned long higher_prime_number PARAMS ((unsigned long)); +static unsigned int higher_prime_index PARAMS ((unsigned long)); +static hashval_t htab_mod_1 PARAMS ((hashval_t, hashval_t, hashval_t, int)); +static hashval_t htab_mod PARAMS ((hashval_t, htab_t)); +static hashval_t htab_mod_m2 PARAMS ((hashval_t, htab_t)); static hashval_t hash_pointer PARAMS ((const void *)); static int eq_pointer PARAMS ((const void *, const void *)); static int htab_expand PARAMS ((htab_t)); @@ -75,69 +88,117 @@ static PTR *find_empty_slot_for_expand PARAMS ((htab_t, hashval_t)); htab_hash htab_hash_pointer = hash_pointer; htab_eq htab_eq_pointer = eq_pointer; -/* The following function returns a nearest prime number which is - greater than N, and near a power of two. */ +/* Table of primes and multiplicative inverses. + + Note that these are not minimally reduced inverses. Unlike when generating + code to divide by a constant, we want to be able to use the same algorithm + all the time. All of these inverses (are implied to) have bit 32 set. + + For the record, here's the function that computed the table; it's a + vastly simplified version of the function of the same name from gcc. */ + +#if 0 +unsigned int +ceil_log2 (unsigned int x) +{ + int i; + for (i = 31; i >= 0 ; --i) + if (x > (1u << i)) + return i+1; + abort (); +} -static unsigned long -higher_prime_number (n) +unsigned int +choose_multiplier (unsigned int d, unsigned int *mlp, unsigned char *shiftp) +{ + unsigned long long mhigh; + double nx; + int lgup, post_shift; + int pow, pow2; + int n = 32, precision = 32; + + lgup = ceil_log2 (d); + pow = n + lgup; + pow2 = n + lgup - precision; + + nx = ldexp (1.0, pow) + ldexp (1.0, pow2); + mhigh = nx / d; + + *shiftp = lgup - 1; + *mlp = mhigh; + return mhigh >> 32; +} +#endif + +struct prime_ent +{ + hashval_t prime; + hashval_t inv; + hashval_t inv_m2; /* inverse of prime-2 */ + hashval_t shift; +}; + +static struct prime_ent const prime_tab[] = { + { 7, 0x24924925, 0x9999999b, 2 }, + { 13, 0x3b13b13c, 0x745d1747, 3 }, + { 31, 0x08421085, 0x1a7b9612, 4 }, + { 61, 0x0c9714fc, 0x15b1e5f8, 5 }, + { 127, 0x02040811, 0x0624dd30, 6 }, + { 251, 0x05197f7e, 0x073260a5, 7 }, + { 509, 0x01824366, 0x02864fc8, 8 }, + { 1021, 0x00c0906d, 0x014191f7, 9 }, + { 2039, 0x0121456f, 0x0161e69e, 10 }, + { 4093, 0x00300902, 0x00501908, 11 }, + { 8191, 0x00080041, 0x00180241, 12 }, + { 16381, 0x000c0091, 0x00140191, 13 }, + { 32749, 0x002605a5, 0x002a06e6, 14 }, + { 65521, 0x000f00e2, 0x00110122, 15 }, + { 131071, 0x00008001, 0x00018003, 16 }, + { 262139, 0x00014002, 0x0001c004, 17 }, + { 524287, 0x00002001, 0x00006001, 18 }, + { 1048573, 0x00003001, 0x00005001, 19 }, + { 2097143, 0x00004801, 0x00005801, 20 }, + { 4194301, 0x00000c01, 0x00001401, 21 }, + { 8388593, 0x00001e01, 0x00002201, 22 }, + { 16777213, 0x00000301, 0x00000501, 23 }, + { 33554393, 0x00001381, 0x00001481, 24 }, + { 67108859, 0x00000141, 0x000001c1, 25 }, + { 134217689, 0x000004e1, 0x00000521, 26 }, + { 268435399, 0x00000391, 0x000003b1, 27 }, + { 536870909, 0x00000019, 0x00000029, 28 }, + { 1073741789, 0x0000008d, 0x00000095, 29 }, + { 2147483647, 0x00000003, 0x00000007, 30 }, + /* Avoid "decimal constant so large it is unsigned" for 4294967291. */ + { 0xfffffffb, 0x00000006, 0x00000008, 31 } +}; + +/* The following function returns an index into the above table of the + nearest prime number which is greater than N, and near a power of two. */ + +static unsigned int +higher_prime_index (n) unsigned long n; { - /* These are primes that are near, but slightly smaller than, a - power of two. */ - static const unsigned long primes[] = { - (unsigned long) 7, - (unsigned long) 13, - (unsigned long) 31, - (unsigned long) 61, - (unsigned long) 127, - (unsigned long) 251, - (unsigned long) 509, - (unsigned long) 1021, - (unsigned long) 2039, - (unsigned long) 4093, - (unsigned long) 8191, - (unsigned long) 16381, - (unsigned long) 32749, - (unsigned long) 65521, - (unsigned long) 131071, - (unsigned long) 262139, - (unsigned long) 524287, - (unsigned long) 1048573, - (unsigned long) 2097143, - (unsigned long) 4194301, - (unsigned long) 8388593, - (unsigned long) 16777213, - (unsigned long) 33554393, - (unsigned long) 67108859, - (unsigned long) 134217689, - (unsigned long) 268435399, - (unsigned long) 536870909, - (unsigned long) 1073741789, - (unsigned long) 2147483647, - /* 4294967291L */ - ((unsigned long) 2147483647) + ((unsigned long) 2147483644), - }; - - const unsigned long *low = &primes[0]; - const unsigned long *high = &primes[sizeof(primes) / sizeof(primes[0])]; + unsigned int low = 0; + unsigned int high = sizeof(prime_tab) / sizeof(prime_tab[0]); while (low != high) { - const unsigned long *mid = low + (high - low) / 2; - if (n > *mid) + unsigned int mid = low + (high - low) / 2; + if (n > prime_tab[mid].prime) low = mid + 1; else high = mid; } /* If we've run out of primes, abort. */ - if (n > *low) + if (n > prime_tab[low].prime) { fprintf (stderr, "Cannot find prime bigger than %lu\n", n); abort (); } - return *low; + return low; } /* Returns a hash code for P. */ @@ -177,6 +238,36 @@ htab_elements (htab) return htab->n_elements - htab->n_deleted; } +/* Return X % Y. */ + +static inline hashval_t +htab_mod_1 (x, y, inv, shift) + hashval_t x, y, inv; + int shift; +{ + /* The multiplicative inverses computed above are for 32-bit types, and + requires that we be able to compute a highpart multiply. */ +#ifdef UNSIGNED_64BIT_TYPE + __extension__ typedef UNSIGNED_64BIT_TYPE ull; + if (sizeof (hashval_t) * CHAR_BIT <= 32) + { + hashval_t t1, t2, t3, t4, q, r; + + t1 = ((ull)x * inv) >> 32; + t2 = x - t1; + t3 = t2 >> 1; + t4 = t1 + t3; + q = t4 >> shift; + r = x - (q * y); + + return r; + } +#endif + + /* Otherwise just use the native division routines. */ + return x % y; +} + /* Compute the primary hash for HASH given HTAB's current size. */ static inline hashval_t @@ -184,7 +275,8 @@ htab_mod (hash, htab) hashval_t hash; htab_t htab; { - return hash % htab_size (htab); + const struct prime_ent *p = &prime_tab[htab->size_prime_index]; + return htab_mod_1 (hash, p->prime, p->inv, p->shift); } /* Compute the secondary hash for HASH given HTAB's current size. */ @@ -194,7 +286,8 @@ htab_mod_m2 (hash, htab) hashval_t hash; htab_t htab; { - return 1 + hash % (htab_size (htab) - 2); + const struct prime_ent *p = &prime_tab[htab->size_prime_index]; + return 1 + htab_mod_1 (hash, p->prime - 2, p->inv_m2, p->shift); } /* This function creates table with length slightly longer than given @@ -212,8 +305,11 @@ htab_create_alloc (size, hash_f, eq_f, del_f, alloc_f, free_f) htab_free free_f; { htab_t result; + unsigned int size_prime_index; + + size_prime_index = higher_prime_index (size); + size = prime_tab[size_prime_index].prime; - size = higher_prime_number (size); result = (htab_t) (*alloc_f) (1, sizeof (struct htab)); if (result == NULL) return NULL; @@ -225,6 +321,7 @@ htab_create_alloc (size, hash_f, eq_f, del_f, alloc_f, free_f) return NULL; } result->size = size; + result->size_prime_index = size_prime_index; result->hash_f = hash_f; result->eq_f = eq_f; result->del_f = del_f; @@ -248,8 +345,11 @@ htab_create_alloc_ex (size, hash_f, eq_f, del_f, alloc_arg, alloc_f, htab_free_with_arg free_f; { htab_t result; + unsigned int size_prime_index; + + size_prime_index = higher_prime_index (size); + size = prime_tab[size_prime_index].prime; - size = higher_prime_number (size); result = (htab_t) (*alloc_f) (alloc_arg, 1, sizeof (struct htab)); if (result == NULL) return NULL; @@ -261,6 +361,7 @@ htab_create_alloc_ex (size, hash_f, eq_f, del_f, alloc_arg, alloc_f, return NULL; } result->size = size; + result->size_prime_index = size_prime_index; result->hash_f = hash_f; result->eq_f = eq_f; result->del_f = del_f; @@ -412,19 +513,27 @@ htab_expand (htab) PTR *olimit; PTR *p; PTR *nentries; - size_t nsize; + size_t nsize, osize, elts; + unsigned int oindex, nindex; oentries = htab->entries; - olimit = oentries + htab->size; + oindex = htab->size_prime_index; + osize = htab->size; + olimit = oentries + osize; + elts = htab_elements (htab); /* Resize only when table after removal of unused elements is either too full or too empty. */ - if ((htab->n_elements - htab->n_deleted) * 2 > htab->size - || ((htab->n_elements - htab->n_deleted) * 8 < htab->size - && htab->size > 32)) - nsize = higher_prime_number ((htab->n_elements - htab->n_deleted) * 2); + if (elts * 2 > osize || (elts * 8 < osize && osize > 32)) + { + nindex = higher_prime_index (elts * 2); + nsize = prime_tab[nindex].prime; + } else - nsize = htab->size; + { + nindex = oindex; + nsize = osize; + } if (htab->alloc_with_arg_f != NULL) nentries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize, @@ -435,7 +544,7 @@ htab_expand (htab) return 0; htab->entries = nentries; htab->size = nsize; - + htab->size_prime_index = nindex; htab->n_elements -= htab->n_deleted; htab->n_deleted = 0; |