274 lines
6.5 KiB
C
274 lines
6.5 KiB
C
/* String pool for GCC.
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Copyright (C) 2000-2020 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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/* String text, identifier text and identifier node allocator.
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Identifiers are uniquely stored in a hash table.
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We use cpplib's hash table implementation. libiberty's
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hashtab.c is not used because it requires 100% average space
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overhead per string, which is unacceptable. Also, this algorithm
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is faster. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tree.h"
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struct ht *ident_hash;
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static hashnode alloc_node (cpp_hash_table *);
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static int mark_ident (struct cpp_reader *, hashnode, const void *);
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static void *
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stringpool_ggc_alloc (size_t x)
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{
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return ggc_alloc_atomic (x);
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}
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/* Initialize the string pool. */
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void
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init_stringpool (void)
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{
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/* Clean up if we're called more than once.
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(We can't make this idempotent since identifiers contain state) */
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if (ident_hash)
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ht_destroy (ident_hash);
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/* Create with 16K (2^14) entries. */
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ident_hash = ht_create (14);
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ident_hash->alloc_node = alloc_node;
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ident_hash->alloc_subobject = stringpool_ggc_alloc;
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}
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/* Allocate a hash node. */
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static hashnode
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alloc_node (cpp_hash_table *table ATTRIBUTE_UNUSED)
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{
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return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
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}
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/* Allocate and return a string constant of length LENGTH, containing
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CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
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nul-terminated string, and the length is calculated using strlen. */
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const char *
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ggc_alloc_string (const char *contents, int length MEM_STAT_DECL)
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{
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if (length == -1)
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length = strlen (contents);
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if (!length)
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return "";
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char *result = (char *) ggc_alloc_atomic (length + 1);
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memcpy (result, contents, length);
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result[length] = '\0';
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return (const char *) result;
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}
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/* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
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If an identifier with that name has previously been referred to,
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the same node is returned this time. */
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#undef get_identifier
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tree
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get_identifier (const char *text)
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{
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hashnode ht_node = ht_lookup (ident_hash,
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(const unsigned char *) text,
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strlen (text), HT_ALLOC);
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/* ht_node can't be NULL here. */
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return HT_IDENT_TO_GCC_IDENT (ht_node);
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}
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/* Identical to get_identifier, except that the length is assumed
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known. */
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tree
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get_identifier_with_length (const char *text, size_t length)
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{
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hashnode ht_node = ht_lookup (ident_hash,
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(const unsigned char *) text,
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length, HT_ALLOC);
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/* ht_node can't be NULL here. */
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return HT_IDENT_TO_GCC_IDENT (ht_node);
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}
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/* If an identifier with the name TEXT (a null-terminated string) has
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previously been referred to, return that node; otherwise return
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NULL_TREE. */
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tree
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maybe_get_identifier (const char *text)
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{
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hashnode ht_node;
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ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
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strlen (text), HT_NO_INSERT);
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if (ht_node)
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return HT_IDENT_TO_GCC_IDENT (ht_node);
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return NULL_TREE;
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}
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/* Report some basic statistics about the string pool. */
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void
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stringpool_statistics (void)
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{
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ht_dump_statistics (ident_hash);
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}
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/* Mark an identifier for GC. */
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static int
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mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
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const void *v ATTRIBUTE_UNUSED)
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{
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gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
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return 1;
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}
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/* Return true if an identifier should be removed from the table. */
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static int
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maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
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const void *v ATTRIBUTE_UNUSED)
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{
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return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h));
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}
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/* Mark the trees hanging off the identifier node for GGC. These are
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handled specially (not using gengtype) because identifiers are only
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roots during one part of compilation. */
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void
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ggc_mark_stringpool (void)
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{
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ht_forall (ident_hash, mark_ident, NULL);
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}
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/* Purge the identifier hash of identifiers which are no longer
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referenced. */
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void
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ggc_purge_stringpool (void)
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{
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ht_purge (ident_hash, maybe_delete_ident, NULL);
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}
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/* Pointer-walking routine for strings (not very interesting, since
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strings don't contain pointers). */
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void
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gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
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gt_pointer_operator op ATTRIBUTE_UNUSED,
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void *cookie ATTRIBUTE_UNUSED)
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{
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}
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/* PCH pointer-walking routine for strings. */
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void
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gt_pch_n_S (const void *x)
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{
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gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x),
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>_pch_p_S);
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}
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/* User-callable entry point for marking string X. */
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void
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gt_pch_nx (const char *& x)
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{
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gt_pch_n_S (x);
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}
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void
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gt_pch_nx (unsigned char *& x)
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{
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gt_pch_n_S (x);
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}
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void
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gt_pch_nx (unsigned char& x ATTRIBUTE_UNUSED)
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{
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}
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void
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gt_pch_nx (unsigned char *x, gt_pointer_operator op, void *cookie)
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{
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op (x, cookie);
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}
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/* Handle saving and restoring the string pool for PCH. */
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/* SPD is saved in the PCH file and holds the information needed
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to restore the string pool. */
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struct GTY(()) string_pool_data {
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ht_identifier_ptr *
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GTY((length ("%h.nslots"),
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nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
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"%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
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entries;
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unsigned int nslots;
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unsigned int nelements;
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};
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static GTY(()) struct string_pool_data * spd;
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/* Save the stringpool data in SPD. */
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void
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gt_pch_save_stringpool (void)
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{
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spd = ggc_alloc<string_pool_data> ();
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spd->nslots = ident_hash->nslots;
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spd->nelements = ident_hash->nelements;
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spd->entries = ggc_vec_alloc<ht_identifier_ptr> (spd->nslots);
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memcpy (spd->entries, ident_hash->entries,
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spd->nslots * sizeof (spd->entries[0]));
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}
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/* Return the stringpool to its state before gt_pch_save_stringpool
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was called. */
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void
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gt_pch_fixup_stringpool (void)
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{
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}
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/* A PCH file has been restored, which loaded SPD; fill the real hash table
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from SPD. */
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void
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gt_pch_restore_stringpool (void)
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{
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ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
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spd = NULL;
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}
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#include "gt-stringpool.h"
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