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/* An expandable hash tables datatype.

   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.

Libiberty is free software; you can redistribute it and/or

modify it under the terms of the GNU Library General Public

License as published by the Free Software Foundation; either

version 2 of the License, or (at your option) any later version.

Libiberty 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

Library General Public License for more details.

You should have received a copy of the GNU Library General Public

License along with libiberty; see the file COPYING.LIB.  If

not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,

Boston, MA 02110-1301, USA.  */

/* This package implements basic hash table functionality.  It is possible

   to search for an entry, create an entry and destroy an entry.

   Elements in the table are generic pointers.

   The size of the table is not fixed; if the occupancy of the table

   grows too high the hash table will be expanded.

   The abstract data implementation is based on generalized Algorithm D

   from Knuth's book "The art of computer programming".  Hash table is

   expanded by creation of new hash table and transferring elements from

   the old table to the new table. */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <sys/types.h>

#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

static unsigned int higher_prime_index (unsigned long);

static hashval_t htab_mod_1 (hashval_t, hashval_t, hashval_t, int);

static hashval_t htab_mod (hashval_t, htab_t);

static hashval_t htab_mod_m2 (hashval_t, htab_t);

static hashval_t hash_pointer (const void *);

static int eq_pointer (const void *, const void *);

static int htab_expand (htab_t);

static PTR *find_empty_slot_for_expand (htab_t, hashval_t);

/* At some point, we could make these be NULL, and modify the

   hash-table routines to handle NULL specially; that would avoid

   function-call overhead for the common case of hashing pointers.  */

htab_hash htab_hash_pointer = hash_pointer;

htab_eq htab_eq_pointer = eq_pointer;

/* 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 ();

}

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 (unsigned long n)

{

  unsigned int low = 0;

  unsigned int high = sizeof(prime_tab) / sizeof(prime_tab[0]);

  while (low != high)

    {

      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 > prime_tab[low].prime)

    {

      fprintf (stderr, "Cannot find prime bigger than %lu\n", n);

      abort ();

    }

  return low;

}

/* Returns a hash code for P.  */

static hashval_t

hash_pointer (const PTR p)

{

  return (hashval_t) ((long)p >> 3);

}

/* Returns non-zero if P1 and P2 are equal.  */

static int

eq_pointer (const PTR p1, const PTR p2)

{

  return p1 == p2;

}

/* The parens around the function names in the next two definitions

   are essential in order to prevent macro expansions of the name.

   The bodies, however, are expanded as expected, so they are not

   recursive definitions.  */

/* Return the current size of given hash table.  */

#define htab_size(htab)  ((htab)->size)

size_t

(htab_size) (htab_t htab)

{

  return htab_size (htab);

}

/* Return the current number of elements in given hash table. */

#define htab_elements(htab)  ((htab)->n_elements - (htab)->n_deleted)

size_t

(htab_elements) (htab_t htab)

{

  return htab_elements (htab);

}

/* Return X % Y.  */

static inline hashval_t

htab_mod_1 (hashval_t x, hashval_t y, hashval_t 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

htab_mod (hashval_t hash, htab_t 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.  */

static inline hashval_t

htab_mod_m2 (hashval_t hash, htab_t htab)

{

  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

   source length.  Created hash table is initiated as empty (all the

   hash table entries are HTAB_EMPTY_ENTRY).  The function returns the

   created hash table, or NULL if memory allocation fails.  */

htab_t

htab_create_alloc (size_t size, htab_hash hash_f, htab_eq eq_f,

                   htab_del del_f, htab_alloc alloc_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;

  result = (htab_t) (*alloc_f) (1, sizeof (struct htab));

  if (result == NULL)

    return NULL;

  result->entries = (PTR *) (*alloc_f) (size, sizeof (PTR));

  if (result->entries == NULL)

    {

      if (free_f != NULL)

        (*free_f) (result);

      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;

  result->alloc_f = alloc_f;

  result->free_f = free_f;

  return result;

}

/* As above, but use the variants of alloc_f and free_f which accept

   an extra argument.  */

htab_t

htab_create_alloc_ex (size_t size, htab_hash hash_f, htab_eq eq_f,

                      htab_del del_f, void *alloc_arg,

                      htab_alloc_with_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;

  result = (htab_t) (*alloc_f) (alloc_arg, 1, sizeof (struct htab));

  if (result == NULL)

    return NULL;

  result->entries = (PTR *) (*alloc_f) (alloc_arg, size, sizeof (PTR));

  if (result->entries == NULL)

    {

      if (free_f != NULL)

        (*free_f) (alloc_arg, result);

      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;

  result->alloc_arg = alloc_arg;

  result->alloc_with_arg_f = alloc_f;

  result->free_with_arg_f = free_f;

  return result;

}

/* Update the function pointers and allocation parameter in the htab_t.  */

void

htab_set_functions_ex (htab_t htab, htab_hash hash_f, htab_eq eq_f,

                       htab_del del_f, PTR alloc_arg,

                       htab_alloc_with_arg alloc_f, htab_free_with_arg free_f)

{

  htab->hash_f = hash_f;

  htab->eq_f = eq_f;

  htab->del_f = del_f;

  htab->alloc_arg = alloc_arg;

  htab->alloc_with_arg_f = alloc_f;

  htab->free_with_arg_f = free_f;

}

/* These functions exist solely for backward compatibility.  */

#undef htab_create

htab_t

htab_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f)

{

  return htab_create_alloc (size, hash_f, eq_f, del_f, xcalloc, free);

}

htab_t

htab_try_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f)

{

  return htab_create_alloc (size, hash_f, eq_f, del_f, calloc, free);

}

/* This function frees all memory allocated for given hash table.

   Naturally the hash table must already exist. */

void

htab_delete (htab_t htab)

{

  size_t size = htab_size (htab);

  PTR *entries = htab->entries;

  int i;

  if (htab->del_f)

    for (i = size - 1; i >= 0; i--)

      if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY)

        (*htab->del_f) (entries[i]);

  if (htab->free_f != NULL)

    {

      (*htab->free_f) (entries);

      (*htab->free_f) (htab);

    }

  else if (htab->free_with_arg_f != NULL)

    {

      (*htab->free_with_arg_f) (htab->alloc_arg, entries);

      (*htab->free_with_arg_f) (htab->alloc_arg, htab);

    }

}

/* This function clears all entries in the given hash table.  */

void

htab_empty (htab_t htab)

{

  size_t size = htab_size (htab);

  PTR *entries = htab->entries;

  int i;

  if (htab->del_f)

    for (i = size - 1; i >= 0; i--)

      if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY)

        (*htab->del_f) (entries[i]);

  /* Instead of clearing megabyte, downsize the table.  */

  if (size > 1024*1024 / sizeof (PTR))

    {

      int nindex = higher_prime_index (1024 / sizeof (PTR));

      int nsize = prime_tab[nindex].prime;

      if (htab->free_f != NULL)

        (*htab->free_f) (htab->entries);

      else if (htab->free_with_arg_f != NULL)

        (*htab->free_with_arg_f) (htab->alloc_arg, htab->entries);

      if (htab->alloc_with_arg_f != NULL)

        htab->entries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize,

                                                           sizeof (PTR *));

      else

        htab->entries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *));

     htab->size = nsize;

     htab->size_prime_index = nindex;

    }

  else

    memset (entries, 0, size * sizeof (PTR));

  htab->n_deleted = 0;

  htab->n_elements = 0;

}

/* Similar to htab_find_slot, but without several unwanted side effects:

    - Does not call htab->eq_f 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.  */

static PTR *

find_empty_slot_for_expand (htab_t htab, hashval_t hash)

{

  hashval_t index = htab_mod (hash, htab);

  size_t size = htab_size (htab);

  PTR *slot = htab->entries + index;

  hashval_t hash2;

  if (*slot == HTAB_EMPTY_ENTRY)

    return slot;

  else if (*slot == HTAB_DELETED_ENTRY)

    abort ();

  hash2 = htab_mod_m2 (hash, htab);

  for (;;)

    {

      index += hash2;

      if (index >= size)

        index -= size;

      slot = htab->entries + index;

      if (*slot == HTAB_EMPTY_ENTRY)

        return slot;

      else if (*slot == HTAB_DELETED_ENTRY)

        abort ();

    }

}

/* 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 failures are allowed,

   this function will return zero, indicating that the table could not be

   expanded.  If all goes well, it will return a non-zero value.  */

static int

htab_expand (htab_t htab)

{

  PTR *oentries;

  PTR *olimit;

  PTR *p;

  PTR *nentries;

  size_t nsize, osize, elts;

  unsigned int oindex, nindex;

  oentries = htab->entries;

  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 (elts * 2 > osize || (elts * 8 < osize && osize > 32))

    {

      nindex = higher_prime_index (elts * 2);

      nsize = prime_tab[nindex].prime;

    }

  else

    {

      nindex = oindex;

      nsize = osize;

    }

  if (htab->alloc_with_arg_f != NULL)

    nentries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize,

                                                  sizeof (PTR *));

  else

    nentries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *));

  if (nentries == NULL)

    return 0;

  htab->entries = nentries;

  htab->size = nsize;

  htab->size_prime_index = nindex;

  htab->n_elements -= htab->n_deleted;

  htab->n_deleted = 0;

  p = oentries;

  do

    {

      PTR x = *p;

      if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY)

        {

          PTR *q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x));

          *q = x;

        }

      p++;

    }

  while (p < olimit);

  if (htab->free_f != NULL)

    (*htab->free_f) (oentries);

  else if (htab->free_with_arg_f != NULL)

    (*htab->free_with_arg_f) (htab->alloc_arg, oentries);

  return 1;

}

/* This function searches for a hash table entry equal to the given

   element.  It cannot be used to insert or delete an element.  */

PTR

htab_find_with_hash (htab_t htab, const PTR element, hashval_t hash)

{

  hashval_t index, hash2;

  size_t size;

  PTR entry;

  htab->searches++;

  size = htab_size (htab);

  index = htab_mod (hash, htab);

  entry = htab->entries[index];

  if (entry == HTAB_EMPTY_ENTRY

      || (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element)))

    return entry;

  hash2 = htab_mod_m2 (hash, htab);

  for (;;)

    {

      htab->collisions++;

      index += hash2;

      if (index >= size)

        index -= size;

      entry = htab->entries[index];

      if (entry == HTAB_EMPTY_ENTRY

          || (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element)))

        return entry;

    }

}

/* Like htab_find_slot_with_hash, but compute the hash value from the

   element.  */

PTR

htab_find (htab_t htab, const PTR element)

{

  return htab_find_with_hash (htab, element, (*htab->hash_f) (element));

}

/* This function searches for a hash table slot containing an entry

   equal to the given element.  To delete an entry, call this with

   insert=NO_INSERT, then call htab_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.  */

PTR *

htab_find_slot_with_hash (htab_t htab, const PTR element,

                          hashval_t hash, enum insert_option insert)

{

  PTR *first_deleted_slot;

  hashval_t index, hash2;

  size_t size;

  PTR entry;

  size = htab_size (htab);

  if (insert == INSERT && size * 3 <= htab->n_elements * 4)

    {

      if (htab_expand (htab) == 0)

        return NULL;

      size = htab_size (htab);

    }

  index = htab_mod (hash, htab);

  htab->searches++;

  first_deleted_slot = NULL;

  entry = htab->entries[index];

  if (entry == HTAB_EMPTY_ENTRY)

    goto empty_entry;

  else if (entry == HTAB_DELETED_ENTRY)

    first_deleted_slot = &htab->entries[index];

  else if ((*htab->eq_f) (entry, element))

    return &htab->entries[index];

  hash2 = htab_mod_m2 (hash, htab);

  for (;;)

    {

      htab->collisions++;

      index += hash2;

      if (index >= size)

        index -= size;

      entry = htab->entries[index];

      if (entry == HTAB_EMPTY_ENTRY)

        goto empty_entry;

      else if (entry == HTAB_DELETED_ENTRY)

        {

          if (!first_deleted_slot)

            first_deleted_slot = &htab->entries[index];

        }

      else if ((*htab->eq_f) (entry, element))

        return &htab->entries[index];

    }

 empty_entry:

  if (insert == NO_INSERT)

    return NULL;

  if (first_deleted_slot)

    {

      htab->n_deleted--;

      *first_deleted_slot = HTAB_EMPTY_ENTRY;

      return first_deleted_slot;

    }