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/* String pool for GCC.
Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008
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
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
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
<>. */
/* 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 "tm.h"
#include "ggc.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. */
const char digit_vector[] = {
'0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
'5', 0, '6', 0, '7', 0, '8', 0, '9', 0
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 (x);
/* Initialize the string pool. */
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)
/* 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 (const char *contents, int length)
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 = GGC_NEWVAR (char, length + 1);
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
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. */
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
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. */
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. */
ggc_mark_stringpool (void)
ht_forall (ident_hash, mark_ident, NULL);
/* Purge the identifier hash of identifiers which are no longer
referenced. */
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). */
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. */
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 string_pool_data GTY(())
struct ht_identifier * *
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")))
unsigned int nslots;
unsigned int nelements;
static GTY(()) struct string_pool_data * spd;
/* Save the stringpool data in SPD. */
gt_pch_save_stringpool (void)
spd = GGC_NEW (struct string_pool_data);
spd->nslots = ident_hash->nslots;
spd->nelements = ident_hash->nelements;
spd->entries = GGC_NEWVEC (struct ht_identifier *, 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. */
gt_pch_fixup_stringpool (void)
/* A PCH file has been restored, which loaded SPD; fill the real hash table
from SPD. */
gt_pch_restore_stringpool (void)
ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
spd = NULL;
#include "gt-stringpool.h"