mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-27 04:52:05 +08:00
af5f3db67c
(struct bstring, struct bcache): Move definition to "bcache.c". Replaced by opaque declaration. (bcache_xfree): Replace free_bcache. (bcache_xmalloc, bcache_memory_used): Declare. * bcache.c: Update copyright. (struct bstring, struct bcache): Moved to here from "bcache.h". Update comments. (bcache_xmalloc, bcache_memory_used): New functions. (bcache_xfree): Replace function free_bcache. * Makefile.in (objfiles.o): Add $(bcache_h). (objfiles_h): Remove $(bcache_h). (symfile.o): Add $(bcache_h). * symmisc.c: Update copyright. (print_symbol_bcache_statistics): Pass psymbol_cache by value. (print_objfile_statistics): Use bcache_memory_used. * symfile.c: Include "bcache.h". (reread_symbols): Use bcache_xfree. (reread_symbols): Use bcache_xmalloc and bcache_xfree. (add_psymbol_to_list): Pass psymbol_cache by value. (add_psymbol_with_dem_name_to_list): Ditto. * objfiles.h: Update copyright. (struct bcache): Declare opaque. Do not include "bcache.h". (struct objfile): Change psymbol_cache and macro_cache to ``struct bcache'' pointers. * dwarf2read.c (macro_start_file): Pass macro_cache by value. * objfiles.c: Include "bcache.h". Update copyright. (allocate_objfile): Use bcache_xmalloc to create psymbol_cache and macro_cache. (free_objfile): Use bcache_xfree.
91 lines
3.9 KiB
C
91 lines
3.9 KiB
C
/* Include file cached obstack implementation.
|
|
Written by Fred Fish <fnf@cygnus.com>
|
|
Rewritten by Jim Blandy <jimb@cygnus.com>
|
|
|
|
Copyright 1999, 2000, 2002 Free Software Foundation, Inc.
|
|
|
|
This file is part of GDB.
|
|
|
|
This program 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 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program 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 this program; if not, write to the Free Software
|
|
Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#ifndef BCACHE_H
|
|
#define BCACHE_H 1
|
|
|
|
/* A bcache is a data structure for factoring out duplication in
|
|
read-only structures. You give the bcache some string of bytes S.
|
|
If the bcache already contains a copy of S, it hands you back a
|
|
pointer to its copy. Otherwise, it makes a fresh copy of S, and
|
|
hands you back a pointer to that. In either case, you can throw
|
|
away your copy of S, and use the bcache's.
|
|
|
|
The "strings" in question are arbitrary strings of bytes --- they
|
|
can contain zero bytes. You pass in the length explicitly when you
|
|
call the bcache function.
|
|
|
|
This means that you can put ordinary C objects in a bcache.
|
|
However, if you do this, remember that structs can contain `holes'
|
|
between members, added for alignment. These bytes usually contain
|
|
garbage. If you try to bcache two objects which are identical from
|
|
your code's point of view, but have different garbage values in the
|
|
structure's holes, then the bcache will treat them as separate
|
|
strings, and you won't get the nice elimination of duplicates you
|
|
were hoping for. So, remember to memset your structures full of
|
|
zeros before bcaching them!
|
|
|
|
You shouldn't modify the strings you get from a bcache, because:
|
|
|
|
- You don't necessarily know who you're sharing space with. If I
|
|
stick eight bytes of text in a bcache, and then stick an
|
|
eight-byte structure in the same bcache, there's no guarantee
|
|
those two objects don't actually comprise the same sequence of
|
|
bytes. If they happen to, the bcache will use a single byte
|
|
string for both of them. Then, modifying the structure will
|
|
change the string. In bizarre ways.
|
|
|
|
- Even if you know for some other reason that all that's okay,
|
|
there's another problem. A bcache stores all its strings in a
|
|
hash table. If you modify a string's contents, you will probably
|
|
change its hash value. This means that the modified string is
|
|
now in the wrong place in the hash table, and future bcache
|
|
probes will never find it. So by mutating a string, you give up
|
|
any chance of sharing its space with future duplicates. */
|
|
|
|
|
|
struct bcache;
|
|
|
|
/* Find a copy of the LENGTH bytes at ADDR in BCACHE. If BCACHE has
|
|
never seen those bytes before, add a copy of them to BCACHE. In
|
|
either case, return a pointer to BCACHE's copy of that string. */
|
|
extern void *bcache (const void *addr, int length, struct bcache *bcache);
|
|
|
|
/* Free all the storage used by BCACHE. */
|
|
extern void bcache_xfree (struct bcache *bcache);
|
|
|
|
/* Create a new bcache object. */
|
|
extern struct bcache *bcache_xmalloc (void);
|
|
|
|
/* Print statistics on BCACHE's memory usage and efficacity at
|
|
eliminating duplication. TYPE should be a string describing the
|
|
kind of data BCACHE holds. Statistics are printed using
|
|
`printf_filtered' and its ilk. */
|
|
extern void print_bcache_statistics (struct bcache *bcache, char *type);
|
|
extern int bcache_memory_used (struct bcache *bcache);
|
|
|
|
/* The hash function */
|
|
extern unsigned long hash(const void *addr, int length);
|
|
|
|
#endif /* BCACHE_H */
|