libguile/gc.h

   1 /* classes: h_files */
   2
   3 #ifndef SCM_GC_H
   4 #define SCM_GC_H
   5
   6 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * as published by the Free Software Foundation; either version 3 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  21  * 02110-1301 USA
  22  */
  23
  24 \f
  25
  26 #include "libguile/__scm.h"
  27
  28 #include "libguile/hooks.h"
  29 #include "libguile/threads.h"
  30
  31 \f
  32 typedef struct scm_t_cell
  33 {
  34   SCM word_0;
  35   SCM word_1;
  36 } scm_t_cell;
  37
  38 /* FIXME: deprecate. */
  39 #define PTR2SCM(x) (SCM_PACK_POINTER (x))
  40 #define SCM2PTR(x) ((scm_t_cell *) (SCM_UNPACK_POINTER (x)))
  41
  42 /* Low level cell data accessing macros.  These macros should only be used
  43  * from within code related to garbage collection issues, since they will
  44  * never check the cells they are applied to - not even if guile is compiled
  45  * in debug mode.  In particular these macros will even work for free cells,
  46  * which should never be encountered by user code.  */
  47
  48 #define SCM_GC_CELL_OBJECT(x, n) (((SCM *)SCM2PTR (x)) [n])
  49 #define SCM_GC_CELL_WORD(x, n)   (SCM_UNPACK (SCM_GC_CELL_OBJECT ((x), (n))))
  50
  51 #define SCM_GC_SET_CELL_OBJECT(x, n, v) ((((SCM *)SCM2PTR (x)) [n]) = (v))
  52 #define SCM_GC_SET_CELL_WORD(x, n, v)  \
  53   (SCM_GC_SET_CELL_OBJECT ((x), (n), SCM_PACK (v)))
  54
  55 #define SCM_GC_CELL_TYPE(x) (SCM_GC_CELL_OBJECT ((x), 0))
  56
  57
  58 /* Except for the garbage collector, no part of guile should ever run over a
  59  * free cell.  Thus, if guile is compiled in debug mode the SCM_CELL_* and
  60  * SCM_SET_CELL_* macros below report an error if they are applied to a free
  61  * cell.  Some other plausibility checks are also performed.  However, if
  62  * guile is not compiled in debug mode, there won't be any time penalty at all
  63  * when using these macros.  */
  64
  65 #if (SCM_DEBUG_CELL_ACCESSES == 1)
  66 #  define SCM_VALIDATE_CELL(cell, expr) (scm_assert_cell_valid (cell), (expr))
  67 #else
  68 #  define SCM_VALIDATE_CELL(cell, expr) (expr)
  69 #endif
  70
  71 #define SCM_CELL_WORD(x, n) \
  72   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_WORD ((x), (n)))
  73 #define SCM_CELL_WORD_0(x) SCM_CELL_WORD ((x), 0)
  74 #define SCM_CELL_WORD_1(x) SCM_CELL_WORD ((x), 1)
  75 #define SCM_CELL_WORD_2(x) SCM_CELL_WORD ((x), 2)
  76 #define SCM_CELL_WORD_3(x) SCM_CELL_WORD ((x), 3)
  77
  78 #define SCM_CELL_OBJECT(x, n) \
  79   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_OBJECT ((x), (n)))
  80 #define SCM_CELL_OBJECT_0(x) SCM_CELL_OBJECT ((x), 0)
  81 #define SCM_CELL_OBJECT_1(x) SCM_CELL_OBJECT ((x), 1)
  82 #define SCM_CELL_OBJECT_2(x) SCM_CELL_OBJECT ((x), 2)
  83 #define SCM_CELL_OBJECT_3(x) SCM_CELL_OBJECT ((x), 3)
  84
  85 #define SCM_SET_CELL_WORD(x, n, v) \
  86   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_WORD ((x), (n), (v)))
  87 #define SCM_SET_CELL_WORD_0(x, v) SCM_SET_CELL_WORD ((x), 0, (v))
  88 #define SCM_SET_CELL_WORD_1(x, v) SCM_SET_CELL_WORD ((x), 1, (v))
  89 #define SCM_SET_CELL_WORD_2(x, v) SCM_SET_CELL_WORD ((x), 2, (v))
  90 #define SCM_SET_CELL_WORD_3(x, v) SCM_SET_CELL_WORD ((x), 3, (v))
  91
  92 #define SCM_SET_CELL_OBJECT(x, n, v) \
  93   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_OBJECT ((x), (n), (v)))
  94 #define SCM_SET_CELL_OBJECT_0(x, v) SCM_SET_CELL_OBJECT ((x), 0, (v))
  95 #define SCM_SET_CELL_OBJECT_1(x, v) SCM_SET_CELL_OBJECT ((x), 1, (v))
  96 #define SCM_SET_CELL_OBJECT_2(x, v) SCM_SET_CELL_OBJECT ((x), 2, (v))
  97 #define SCM_SET_CELL_OBJECT_3(x, v) SCM_SET_CELL_OBJECT ((x), 3, (v))
  98
  99 #define SCM_CELL_OBJECT_LOC(x, n) (SCM_VALIDATE_CELL((x), &SCM_GC_CELL_OBJECT ((x), (n))))
 100 #define SCM_CARLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 0))
 101 #define SCM_CDRLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 1))
 102
 103 #define SCM_CELL_TYPE(x) SCM_CELL_WORD_0 (x)
 104 #define SCM_SET_CELL_TYPE(x, t) SCM_SET_CELL_WORD_0 ((x), (t))
 105
 106
 107 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 108 /* Set this to != 0 if every cell that is accessed shall be checked:
 109  */
 110 SCM_API int scm_debug_cell_accesses_p;
 111 SCM_API int scm_expensive_debug_cell_accesses_p;
 112 SCM_API int scm_debug_cells_gc_interval ;
 113 SCM_API void scm_i_expensive_validation_check (SCM cell);
 114 #endif
 115
 116 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_gc_admin_mutex;
 117
 118 #define scm_gc_running_p  0
 119 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_sweep_mutex;
 120
 121 #ifdef __ia64__
 122 void *scm_ia64_register_backing_store_base (void);
 123 void *scm_ia64_ar_bsp (const void *);
 124 #endif
 125
 126 \f
 127
 128 SCM_API unsigned long scm_gc_ports_collected;
 129
 130 SCM_API SCM scm_after_gc_hook;
 131
 132 SCM_API scm_t_c_hook scm_before_gc_c_hook;
 133 SCM_API scm_t_c_hook scm_before_mark_c_hook;
 134 SCM_API scm_t_c_hook scm_before_sweep_c_hook;
 135 SCM_API scm_t_c_hook scm_after_sweep_c_hook;
 136 SCM_API scm_t_c_hook scm_after_gc_c_hook;
 137
 138 \f
 139
 140 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 141 SCM_API void scm_assert_cell_valid (SCM);
 142 #endif
 143
 144 SCM_API SCM scm_set_debug_cell_accesses_x (SCM flag);
 145
 146
 147 SCM_API SCM scm_object_address (SCM obj);
 148 SCM_API SCM scm_gc_enable (void);
 149 SCM_API SCM scm_gc_disable (void);
 150 SCM_API SCM scm_gc_dump (void);
 151 SCM_API SCM scm_gc_stats (void);
 152 SCM_API SCM scm_gc_live_object_stats (void);
 153 SCM_API SCM scm_gc (void);
 154 SCM_INTERNAL void scm_i_gc (const char *what);
 155 SCM_API void scm_gc_mark (SCM p);
 156 SCM_API void scm_gc_sweep (void);
 157
 158 SCM_API void *scm_malloc (size_t size) SCM_MALLOC;
 159 SCM_API void *scm_calloc (size_t size) SCM_MALLOC;
 160 SCM_API void *scm_realloc (void *mem, size_t size);
 161 SCM_API char *scm_strdup (const char *str) SCM_MALLOC;
 162 SCM_API char *scm_strndup (const char *str, size_t n) SCM_MALLOC;
 163 SCM_API void scm_gc_register_collectable_memory (void *mem, size_t size,
 164                                                  const char *what);
 165 SCM_API void scm_gc_unregister_collectable_memory (void *mem, size_t size,
 166                                                    const char *what);
 167 SCM_API void *scm_gc_malloc_pointerless (size_t size, const char *what)
 168   SCM_MALLOC;
 169 SCM_API void *scm_gc_calloc (size_t size, const char *what)
 170   SCM_MALLOC;
 171 SCM_API void *scm_gc_malloc (size_t size, const char *what)
 172   SCM_MALLOC;
 173 SCM_API void *scm_gc_realloc (void *mem, size_t old_size,
 174                               size_t new_size, const char *what);
 175 SCM_API void scm_gc_free (void *mem, size_t size, const char *what);
 176 SCM_API char *scm_gc_strdup (const char *str, const char *what)
 177   SCM_MALLOC;
 178 SCM_API char *scm_gc_strndup (const char *str, size_t n, const char *what)
 179   SCM_MALLOC;
 180
 181
 182 #ifdef BUILDING_LIBGUILE
 183 #include "libguile/bdw-gc.h"
 184 #define SCM_GC_MALLOC(size) GC_MALLOC (size)
 185 #define SCM_GC_MALLOC_POINTERLESS(size) GC_MALLOC_ATOMIC (size)
 186 #else
 187 #define SCM_GC_MALLOC(size) scm_gc_malloc (size, NULL)
 188 #define SCM_GC_MALLOC_POINTERLESS(size) scm_gc_malloc_pointerless (size, NULL)
 189 #endif
 190
 191
 192 SCM_INLINE SCM scm_cell (scm_t_bits car, scm_t_bits cdr);
 193 SCM_INLINE SCM scm_double_cell (scm_t_bits car, scm_t_bits cbr,
 194                              scm_t_bits ccr, scm_t_bits cdr);
 195 SCM_INLINE SCM scm_words (scm_t_bits car, scm_t_uint16 n_words);
 196
 197 #if SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES
 198
 199 SCM_INLINE_IMPLEMENTATION SCM
 200 scm_cell (scm_t_bits car, scm_t_bits cdr)
 201 {
 202   SCM cell = SCM_PACK_POINTER (SCM_GC_MALLOC (sizeof (scm_t_cell)));
 203
 204   /* Initialize the type slot last so that the cell is ignored by the GC
 205      until it is completely initialized.  This is only relevant when the GC
 206      can actually run during this code, which it can't since the GC only runs
 207      when all other threads are stopped.  */
 208   SCM_GC_SET_CELL_WORD (cell, 1, cdr);
 209   SCM_GC_SET_CELL_WORD (cell, 0, car);
 210
 211   return cell;
 212 }
 213
 214 SCM_INLINE_IMPLEMENTATION SCM
 215 scm_double_cell (scm_t_bits car, scm_t_bits cbr,
 216                  scm_t_bits ccr, scm_t_bits cdr)
 217 {
 218   SCM z;
 219
 220   z = SCM_PACK_POINTER (SCM_GC_MALLOC (2 * sizeof (scm_t_cell)));
 221   /* Initialize the type slot last so that the cell is ignored by the
 222      GC until it is completely initialized.  This is only relevant
 223      when the GC can actually run during this code, which it can't
 224      since the GC only runs when all other threads are stopped.
 225   */
 226   SCM_GC_SET_CELL_WORD (z, 1, cbr);
 227   SCM_GC_SET_CELL_WORD (z, 2, ccr);
 228   SCM_GC_SET_CELL_WORD (z, 3, cdr);
 229   SCM_GC_SET_CELL_WORD (z, 0, car);
 230
 231   /* When this function is inlined, it's possible that the last
 232      SCM_GC_SET_CELL_WORD above will be adjacent to a following
 233      initialization of z.  E.g., it occurred in scm_make_real.  GCC
 234      from around version 3 (e.g., certainly 3.2) began taking
 235      advantage of strict C aliasing rules which say that it's OK to
 236      interchange the initialization above and the one below when the
 237      pointer types appear to differ sufficiently.  We don't want that,
 238      of course.  GCC allows this behaviour to be disabled with the
 239      -fno-strict-aliasing option, but would also need to be supplied
 240      by Guile users.  Instead, the following statements prevent the
 241      reordering.
 242    */
 243 #ifdef __GNUC__
 244   __asm__ volatile ("" : : : "memory");
 245 #else
 246   /* portable version, just in case any other compiler does the same
 247      thing.  */
 248   scm_remember_upto_here_1 (z);
 249 #endif
 250
 251   return z;
 252 }
 253
 254 SCM_INLINE_IMPLEMENTATION SCM
 255 scm_words (scm_t_bits car, scm_t_uint16 n_words)
 256 {
 257   SCM z;
 258
 259   z = SCM_PACK_POINTER (SCM_GC_MALLOC (sizeof (scm_t_bits) * n_words));
 260   SCM_GC_SET_CELL_WORD (z, 0, car);
 261
 262   /* FIXME: is the following concern even relevant with BDW-GC? */
 263
 264   /* When this function is inlined, it's possible that the last
 265      SCM_GC_SET_CELL_WORD above will be adjacent to a following
 266      initialization of z.  E.g., it occurred in scm_make_real.  GCC
 267      from around version 3 (e.g., certainly 3.2) began taking
 268      advantage of strict C aliasing rules which say that it's OK to
 269      interchange the initialization above and the one below when the
 270      pointer types appear to differ sufficiently.  We don't want that,
 271      of course.  GCC allows this behaviour to be disabled with the
 272      -fno-strict-aliasing option, but would also need to be supplied
 273      by Guile users.  Instead, the following statements prevent the
 274      reordering.
 275    */
 276 #ifdef __GNUC__
 277   __asm__ volatile ("" : : : "memory");
 278 #else
 279   /* portable version, just in case any other compiler does the same
 280      thing.  */
 281   scm_remember_upto_here_1 (z);
 282 #endif
 283
 284   return z;
 285 }
 286
 287 #endif /* SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES */
 288
 289 SCM_API void scm_remember_upto_here_1 (SCM obj);
 290 SCM_API void scm_remember_upto_here_2 (SCM obj1, SCM obj2);
 291 SCM_API void scm_remember_upto_here (SCM obj1, ...);
 292
 293 /* In GCC we can force a reference to an SCM by making it an input to an
 294    empty asm.  This avoids the code size and slowdown of an actual function
 295    call.  Unfortunately there doesn't seem to be any way to do the varargs
 296    scm_remember_upto_here like this.
 297
 298    __volatile__ ensures nothing will be moved across the asm, and it won't
 299    be optimized away (or only if proved unreachable).  Constraint "g" can be
 300    used on all processors and allows any memory or general register (or
 301    immediate) operand.  The actual asm syntax doesn't matter, we don't want
 302    to use it, just ensure the operand is still alive.  See "Extended Asm" in
 303    the GCC manual for more.  */
 304
 305 #ifdef __GNUC__
 306 #define scm_remember_upto_here_1(x)             \
 307   do {                                          \
 308     __asm__ __volatile__ ("" : : "g" (x));      \
 309   } while (0)
 310 #define scm_remember_upto_here_2(x, y)          \
 311   do {                                          \
 312     scm_remember_upto_here_1 (x);               \
 313     scm_remember_upto_here_1 (y);               \
 314   } while (0)
 315 #endif
 316
 317 SCM_API SCM scm_return_first (SCM elt, ...);
 318 SCM_API int scm_return_first_int (int x, ...);
 319 SCM_API SCM scm_permanent_object (SCM obj);
 320 SCM_API SCM scm_gc_protect_object (SCM obj);
 321 SCM_API SCM scm_gc_unprotect_object (SCM obj);
 322 SCM_API void scm_gc_register_root (SCM *p);
 323 SCM_API void scm_gc_unregister_root (SCM *p);
 324 SCM_API void scm_gc_register_roots (SCM *b, unsigned long n);
 325 SCM_API void scm_gc_unregister_roots (SCM *b, unsigned long n);
 326 SCM_API SCM scm_protects;
 327 SCM_INTERNAL void scm_storage_prehistory (void);
 328 SCM_INTERNAL void scm_init_gc_protect_object (void);
 329 SCM_INTERNAL void scm_init_gc (void);
 330
 331 #endif  /* SCM_GC_H */
 332
 333 /*
 334   Local Variables:
 335   c-file-style: "gnu"
 336   End:
 337 */