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/* String pool for GCC.

   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010

   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/>.  */

/* String text, identifier text and identifier node allocator.

   Identifiers are uniquely stored in a hash table.

   We use cpplib's hash table implementation.  libiberty's

   hashtab.c is not used because it requires 100% average space

   overhead per string, which is unacceptable.  Also, this algorithm

   is faster.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "ggc.h"

#include "ggc-internal.h"

#include "tree.h"

#include "symtab.h"

#include "cpplib.h"

/* The "" allocated string.  */

const char empty_string[] = "";

/* Character strings, each containing a single decimal digit.

   Written this way to save space.  */

static const char digit_vector[] = {

  '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,

  '5', 0, '6', 0, '7', 0, '8', 0, '9', 0

};

#define digit_string(d) (digit_vector + ((d) * 2))

struct ht *ident_hash;

static hashnode alloc_node (hash_table *);

static int mark_ident (struct cpp_reader *, hashnode, const void *);

static void *

stringpool_ggc_alloc (size_t x)

{

  return ggc_alloc_atomic (x);

}

/* Initialize the string pool.  */

void

init_stringpool (void)

{

  /* Create with 16K (2^14) entries.  */

  ident_hash = ht_create (14);

  ident_hash->alloc_node = alloc_node;

  ident_hash->alloc_subobject = stringpool_ggc_alloc;

}

/* Allocate a hash node.  */

static hashnode

alloc_node (hash_table *table ATTRIBUTE_UNUSED)

{

  return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));

}

/* Allocate and return a string constant of length LENGTH, containing

   CONTENTS.  If LENGTH is -1, CONTENTS is assumed to be a

   nul-terminated string, and the length is calculated using strlen.  */

const char *

ggc_alloc_string_stat (const char *contents, int length MEM_STAT_DECL)

{

  char *result;

  if (length == -1)

    length = strlen (contents);

  if (length == 0)

    return empty_string;

  if (length == 1 && ISDIGIT (contents[0]))

    return digit_string (contents[0] - '0');

  result = (char *) ggc_alloc_atomic_stat (length + 1 PASS_MEM_STAT);

  memcpy (result, contents, length);

  result[length] = '\0';

  return (const char *) result;

}

/* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).

   If an identifier with that name has previously been referred to,

   the same node is returned this time.  */

#undef get_identifier

tree

get_identifier (const char *text)

{

  hashnode ht_node = ht_lookup (ident_hash,

                                (const unsigned char *) text,

                                strlen (text), HT_ALLOC);

  /* ht_node can't be NULL here.  */

  return HT_IDENT_TO_GCC_IDENT (ht_node);

}

/* Identical to get_identifier, except that the length is assumed

   known.  */

tree

get_identifier_with_length (const char *text, size_t length)

{

  hashnode ht_node = ht_lookup (ident_hash,

                                (const unsigned char *) text,

                                length, HT_ALLOC);

  /* ht_node can't be NULL here.  */

  return HT_IDENT_TO_GCC_IDENT (ht_node);

}

/* If an identifier with the name TEXT (a null-terminated string) has

   previously been referred to, return that node; otherwise return

   NULL_TREE.  */

tree

maybe_get_identifier (const char *text)

{

  hashnode ht_node;

  ht_node = ht_lookup (ident_hash, (const unsigned char *) text,

                       strlen (text), HT_NO_INSERT);

  if (ht_node)

    return HT_IDENT_TO_GCC_IDENT (ht_node);

  return NULL_TREE;

}

/* Report some basic statistics about the string pool.  */

void

stringpool_statistics (void)

{

  ht_dump_statistics (ident_hash);

}

/* Mark an identifier for GC.  */

static int

mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,

            const void *v ATTRIBUTE_UNUSED)

{

  gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));

  return 1;

}

/* Return true if an identifier should be removed from the table.  */

static int

maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,

                    const void *v ATTRIBUTE_UNUSED)

{

  return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h));

}

/* Mark the trees hanging off the identifier node for GGC.  These are

   handled specially (not using gengtype) because identifiers are only

   roots during one part of compilation.  */

void

ggc_mark_stringpool (void)

{

  ht_forall (ident_hash, mark_ident, NULL);

}

/* Purge the identifier hash of identifiers which are no longer

   referenced.  */

void

ggc_purge_stringpool (void)

{

  ht_purge (ident_hash, maybe_delete_ident, NULL);

}

/* Pointer-walking routine for strings (not very interesting, since

   strings don't contain pointers).  */

void

gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,

            gt_pointer_operator op ATTRIBUTE_UNUSED,

            void *cookie ATTRIBUTE_UNUSED)

{

}

/* PCH pointer-walking routine for strings.  */

void

gt_pch_n_S (const void *x)

{

  gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x),

                      &gt_pch_p_S, gt_types_enum_last);

}

/* Handle saving and restoring the string pool for PCH.  */

/* SPD is saved in the PCH file and holds the information needed

   to restore the string pool.  */

struct GTY(()) string_pool_data {

  ht_identifier_ptr *

    GTY((length ("%h.nslots"),

         nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",

                     "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))

    entries;

  unsigned int nslots;

  unsigned int nelements;

};

static GTY(()) struct string_pool_data * spd;

/* Save the stringpool data in SPD.  */

void

gt_pch_save_stringpool (void)

{

  spd = ggc_alloc_string_pool_data ();

  spd->nslots = ident_hash->nslots;

  spd->nelements = ident_hash->nelements;

  spd->entries = ggc_alloc_vec_ht_identifier_ptr (spd->nslots);

  memcpy (spd->entries, ident_hash->entries,

          spd->nslots * sizeof (spd->entries[0]));

}

/* Return the stringpool to its state before gt_pch_save_stringpool

   was called.  */

void

gt_pch_fixup_stringpool (void)

{

}

/* A PCH file has been restored, which loaded SPD; fill the real hash table

   from SPD.  */

void

gt_pch_restore_stringpool (void)

{

  ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);

  spd = NULL;

}

#include "gt-stringpool.h"