173 lines
4.6 KiB
C
173 lines
4.6 KiB
C
/* String pool for GCC.
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Copyright (C) 2000, 2001 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 2, 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 COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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/* String text, identifier text and identifier node allocator. Strings
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allocated by ggc_alloc_string are stored in an obstack which is
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never shrunk. Identifiers are uniquely stored in a hash table.
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We have our own private 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 "ggc.h"
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#include "tree.h"
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#include "hashtable.h"
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/* The "" allocated string. */
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const char empty_string[] = "";
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/* Character strings, each containing a single decimal digit.
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Written this way to save space. */
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const char digit_vector[] = {
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'0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
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'5', 0, '6', 0, '7', 0, '8', 0, '9', 0
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};
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struct ht *ident_hash;
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static struct obstack string_stack;
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static hashnode alloc_node PARAMS ((hash_table *));
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static int mark_ident PARAMS ((struct cpp_reader *, hashnode, const PTR));
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static void mark_ident_hash PARAMS ((void *));
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/* Initialize the string pool. */
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void
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init_stringpool ()
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{
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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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gcc_obstack_init (&string_stack);
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ggc_add_root (&ident_hash, 1, sizeof ident_hash, mark_ident_hash);
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}
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/* Allocate a hash node. */
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static hashnode
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alloc_node (table)
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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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If the same string constant has been allocated before, that copy is
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returned this time too. */
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const char *
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ggc_alloc_string (contents, length)
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const char *contents;
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int length;
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{
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if (length == -1)
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length = strlen (contents);
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if (length == 0)
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return empty_string;
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if (length == 1 && ISDIGIT (contents[0]))
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return digit_string (contents[0] - '0');
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obstack_grow0 (&string_stack, contents, length);
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return obstack_finish (&string_stack);
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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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tree
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get_identifier (text)
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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 (text, length)
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const char *text;
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unsigned int 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 (text)
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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 ()
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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 (pfile, h, v)
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struct cpp_reader *pfile ATTRIBUTE_UNUSED;
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hashnode h;
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const PTR v ATTRIBUTE_UNUSED;
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{
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ggc_mark_nonnull_tree (HT_IDENT_TO_GCC_IDENT (h));
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return 1;
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}
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/* Mark all identifiers for GC. */
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static void
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mark_ident_hash (arg)
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PTR arg ATTRIBUTE_UNUSED;
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{
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ht_forall (ident_hash, mark_ident, NULL);
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}
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