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,
   7  *   2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public License
  11  * as published by the Free Software Foundation; either version 3 of
  12  * the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  22  * 02110-1301 USA
  23  */
  24
  25 \f
  26
  27 #include "libguile/__scm.h"
  28
  29 #include "libguile/hooks.h"
  30 #include "libguile/threads.h"
  31
  32 \f
  33 typedef struct scm_t_cell
  34 {
  35   SCM word_0;
  36   SCM word_1;
  37 } scm_t_cell;
  38
  39 /* FIXME: deprecate. */
  40 #define PTR2SCM(x) (SCM_PACK_POINTER (x))
  41 #define SCM2PTR(x) ((scm_t_cell *) (SCM_UNPACK_POINTER (x)))
  42
  43 /* Low level cell data accessing macros.  These macros should only be used
  44  * from within code related to garbage collection issues, since they will
  45  * never check the cells they are applied to - not even if guile is compiled
  46  * in debug mode.  In particular these macros will even work for free cells,
  47  * which should never be encountered by user code.  */
  48
  49 #define SCM_GC_CELL_OBJECT(x, n) (((SCM *)SCM2PTR (x)) [n])
  50 #define SCM_GC_CELL_WORD(x, n)   (SCM_UNPACK (SCM_GC_CELL_OBJECT ((x), (n))))
  51
  52 #define SCM_GC_SET_CELL_OBJECT(x, n, v) ((((SCM *)SCM2PTR (x)) [n]) = (v))
  53 #define SCM_GC_SET_CELL_WORD(x, n, v)  \
  54   (SCM_GC_SET_CELL_OBJECT ((x), (n), SCM_PACK (v)))
  55
  56 #define SCM_GC_CELL_TYPE(x) (SCM_GC_CELL_OBJECT ((x), 0))
  57
  58
  59 /* Except for the garbage collector, no part of guile should ever run over a
  60  * free cell.  Thus, if guile is compiled in debug mode the SCM_CELL_* and
  61  * SCM_SET_CELL_* macros below report an error if they are applied to a free
  62  * cell.  Some other plausibility checks are also performed.  However, if
  63  * guile is not compiled in debug mode, there won't be any time penalty at all
  64  * when using these macros.  */
  65
  66 #if (SCM_DEBUG_CELL_ACCESSES == 1)
  67 #  define SCM_VALIDATE_CELL(cell, expr) (scm_assert_cell_valid (cell), (expr))
  68 #else
  69 #  define SCM_VALIDATE_CELL(cell, expr) (expr)
  70 #endif
  71
  72 #define SCM_CELL_WORD(x, n) \
  73   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_WORD ((x), (n)))
  74 #define SCM_CELL_WORD_0(x) SCM_CELL_WORD ((x), 0)
  75 #define SCM_CELL_WORD_1(x) SCM_CELL_WORD ((x), 1)
  76 #define SCM_CELL_WORD_2(x) SCM_CELL_WORD ((x), 2)
  77 #define SCM_CELL_WORD_3(x) SCM_CELL_WORD ((x), 3)
  78
  79 #define SCM_CELL_OBJECT(x, n) \
  80   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_OBJECT ((x), (n)))
  81 #define SCM_CELL_OBJECT_0(x) SCM_CELL_OBJECT ((x), 0)
  82 #define SCM_CELL_OBJECT_1(x) SCM_CELL_OBJECT ((x), 1)
  83 #define SCM_CELL_OBJECT_2(x) SCM_CELL_OBJECT ((x), 2)
  84 #define SCM_CELL_OBJECT_3(x) SCM_CELL_OBJECT ((x), 3)
  85
  86 #define SCM_SET_CELL_WORD(x, n, v) \
  87   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_WORD ((x), (n), (v)))
  88 #define SCM_SET_CELL_WORD_0(x, v) SCM_SET_CELL_WORD ((x), 0, (v))
  89 #define SCM_SET_CELL_WORD_1(x, v) SCM_SET_CELL_WORD ((x), 1, (v))
  90 #define SCM_SET_CELL_WORD_2(x, v) SCM_SET_CELL_WORD ((x), 2, (v))
  91 #define SCM_SET_CELL_WORD_3(x, v) SCM_SET_CELL_WORD ((x), 3, (v))
  92
  93 #define SCM_SET_CELL_OBJECT(x, n, v) \
  94   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_OBJECT ((x), (n), (v)))
  95 #define SCM_SET_CELL_OBJECT_0(x, v) SCM_SET_CELL_OBJECT ((x), 0, (v))
  96 #define SCM_SET_CELL_OBJECT_1(x, v) SCM_SET_CELL_OBJECT ((x), 1, (v))
  97 #define SCM_SET_CELL_OBJECT_2(x, v) SCM_SET_CELL_OBJECT ((x), 2, (v))
  98 #define SCM_SET_CELL_OBJECT_3(x, v) SCM_SET_CELL_OBJECT ((x), 3, (v))
  99
 100 #define SCM_CELL_OBJECT_LOC(x, n) (SCM_VALIDATE_CELL((x), &SCM_GC_CELL_OBJECT ((x), (n))))
 101 #define SCM_CARLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 0))
 102 #define SCM_CDRLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 1))
 103
 104 #define SCM_CELL_TYPE(x) SCM_CELL_WORD_0 (x)
 105 #define SCM_SET_CELL_TYPE(x, t) SCM_SET_CELL_WORD_0 ((x), (t))
 106
 107
 108 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 109 /* Set this to != 0 if every cell that is accessed shall be checked:
 110  */
 111 SCM_API int scm_debug_cell_accesses_p;
 112 SCM_API int scm_expensive_debug_cell_accesses_p;
 113 SCM_API int scm_debug_cells_gc_interval ;
 114 SCM_API void scm_i_expensive_validation_check (SCM cell);
 115 #endif
 116
 117 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_gc_admin_mutex;
 118
 119 #define scm_gc_running_p  0
 120 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_sweep_mutex;
 121
 122 #ifdef __ia64__
 123 void *scm_ia64_register_backing_store_base (void);
 124 void *scm_ia64_ar_bsp (const void *);
 125 #endif
 126
 127 \f
 128
 129 SCM_API unsigned long scm_gc_ports_collected;
 130
 131 SCM_API SCM scm_after_gc_hook;
 132
 133 SCM_API scm_t_c_hook scm_before_gc_c_hook;
 134 SCM_API scm_t_c_hook scm_before_mark_c_hook;
 135 SCM_API scm_t_c_hook scm_before_sweep_c_hook;
 136 SCM_API scm_t_c_hook scm_after_sweep_c_hook;
 137 SCM_API scm_t_c_hook scm_after_gc_c_hook;
 138
 139 \f
 140
 141 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 142 SCM_API void scm_assert_cell_valid (SCM);
 143 #endif
 144
 145 SCM_API SCM scm_set_debug_cell_accesses_x (SCM flag);
 146
 147
 148 SCM_API SCM scm_object_address (SCM obj);
 149 SCM_API SCM scm_gc_enable (void);
 150 SCM_API SCM scm_gc_disable (void);
 151 SCM_API SCM scm_gc_dump (void);
 152 SCM_API SCM scm_gc_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_gc_register_allocation (size_t size);
 159
 160 SCM_API void *scm_malloc (size_t size) SCM_MALLOC;
 161 SCM_API void *scm_calloc (size_t size) SCM_MALLOC;
 162 SCM_API void *scm_realloc (void *mem, size_t size);
 163 SCM_API char *scm_strdup (const char *str) SCM_MALLOC;
 164 SCM_API char *scm_strndup (const char *str, size_t n) SCM_MALLOC;
 165 SCM_API void scm_gc_register_collectable_memory (void *mem, size_t size,
 166                                                  const char *what);
 167 SCM_API void scm_gc_unregister_collectable_memory (void *mem, size_t size,
 168                                                    const char *what);
 169 SCM_API void *scm_gc_malloc_pointerless (size_t size, const char *what)
 170   SCM_MALLOC;
 171 SCM_API void *scm_gc_calloc (size_t size, const char *what)
 172   SCM_MALLOC;
 173 SCM_API void *scm_gc_malloc (size_t size, const char *what)
 174   SCM_MALLOC;
 175 SCM_API void *scm_gc_realloc (void *mem, size_t old_size,
 176                               size_t new_size, const char *what);
 177 SCM_API void scm_gc_free (void *mem, size_t size, const char *what);
 178 SCM_API char *scm_gc_strdup (const char *str, const char *what)
 179   SCM_MALLOC;
 180 SCM_API char *scm_gc_strndup (const char *str, size_t n, const char *what)
 181   SCM_MALLOC;
 182
 183 #define scm_gc_typed_calloc(t) ((t *) scm_gc_calloc (sizeof (t), #t))
 184
 185 #ifdef BUILDING_LIBGUILE
 186 #include "libguile/bdw-gc.h"
 187 #define SCM_GC_MALLOC(size) GC_MALLOC (size)
 188 #define SCM_GC_MALLOC_POINTERLESS(size) GC_MALLOC_ATOMIC (size)
 189 #else
 190 #define SCM_GC_MALLOC(size) scm_gc_malloc (size, NULL)
 191 #define SCM_GC_MALLOC_POINTERLESS(size) scm_gc_malloc_pointerless (size, NULL)
 192 #endif
 193
 194
 195 SCM_INLINE SCM scm_cell (scm_t_bits car, scm_t_bits cdr);
 196 SCM_INLINE SCM scm_double_cell (scm_t_bits car, scm_t_bits cbr,
 197                              scm_t_bits ccr, scm_t_bits cdr);
 198 SCM_INLINE SCM scm_words (scm_t_bits car, scm_t_uint32 n_words);
 199
 200 #if SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES
 201
 202 SCM_INLINE_IMPLEMENTATION SCM
 203 scm_cell (scm_t_bits car, scm_t_bits cdr)
 204 {
 205   SCM cell = SCM_PACK_POINTER (SCM_GC_MALLOC (sizeof (scm_t_cell)));
 206
 207   /* Initialize the type slot last so that the cell is ignored by the GC
 208      until it is completely initialized.  This is only relevant when the GC
 209      can actually run during this code, which it can't since the GC only runs
 210      when all other threads are stopped.  */
 211   SCM_GC_SET_CELL_WORD (cell, 1, cdr);
 212   SCM_GC_SET_CELL_WORD (cell, 0, car);
 213
 214   return cell;
 215 }
 216
 217 SCM_INLINE_IMPLEMENTATION SCM
 218 scm_double_cell (scm_t_bits car, scm_t_bits cbr,
 219                  scm_t_bits ccr, scm_t_bits cdr)
 220 {
 221   SCM z;
 222
 223   z = SCM_PACK_POINTER (SCM_GC_MALLOC (2 * sizeof (scm_t_cell)));
 224   /* Initialize the type slot last so that the cell is ignored by the
 225      GC until it is completely initialized.  This is only relevant
 226      when the GC can actually run during this code, which it can't
 227      since the GC only runs when all other threads are stopped.
 228   */
 229   SCM_GC_SET_CELL_WORD (z, 1, cbr);
 230   SCM_GC_SET_CELL_WORD (z, 2, ccr);
 231   SCM_GC_SET_CELL_WORD (z, 3, cdr);
 232   SCM_GC_SET_CELL_WORD (z, 0, car);
 233
 234   /* When this function is inlined, it's possible that the last
 235      SCM_GC_SET_CELL_WORD above will be adjacent to a following
 236      initialization of z.  E.g., it occurred in scm_make_real.  GCC
 237      from around version 3 (e.g., certainly 3.2) began taking
 238      advantage of strict C aliasing rules which say that it's OK to
 239      interchange the initialization above and the one below when the
 240      pointer types appear to differ sufficiently.  We don't want that,
 241      of course.  GCC allows this behaviour to be disabled with the
 242      -fno-strict-aliasing option, but would also need to be supplied
 243      by Guile users.  Instead, the following statements prevent the
 244      reordering.
 245    */
 246 #ifdef __GNUC__
 247   __asm__ volatile ("" : : : "memory");
 248 #else
 249   /* portable version, just in case any other compiler does the same
 250      thing.  */
 251   scm_remember_upto_here_1 (z);
 252 #endif
 253
 254   return z;
 255 }
 256
 257 SCM_INLINE_IMPLEMENTATION SCM
 258 scm_words (scm_t_bits car, scm_t_uint32 n_words)
 259 {
 260   SCM z;
 261
 262   z = SCM_PACK_POINTER (SCM_GC_MALLOC (sizeof (scm_t_bits) * n_words));
 263   SCM_GC_SET_CELL_WORD (z, 0, car);
 264
 265   /* FIXME: is the following concern even relevant with BDW-GC? */
 266
 267   /* When this function is inlined, it's possible that the last
 268      SCM_GC_SET_CELL_WORD above will be adjacent to a following
 269      initialization of z.  E.g., it occurred in scm_make_real.  GCC
 270      from around version 3 (e.g., certainly 3.2) began taking
 271      advantage of strict C aliasing rules which say that it's OK to
 272      interchange the initialization above and the one below when the
 273      pointer types appear to differ sufficiently.  We don't want that,
 274      of course.  GCC allows this behaviour to be disabled with the
 275      -fno-strict-aliasing option, but would also need to be supplied
 276      by Guile users.  Instead, the following statements prevent the
 277      reordering.
 278    */
 279 #ifdef __GNUC__
 280   __asm__ volatile ("" : : : "memory");
 281 #else
 282   /* portable version, just in case any other compiler does the same
 283      thing.  */
 284   scm_remember_upto_here_1 (z);
 285 #endif
 286
 287   return z;
 288 }
 289
 290 #endif /* SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES */
 291
 292 SCM_API void scm_remember_upto_here_1 (SCM obj);
 293 SCM_API void scm_remember_upto_here_2 (SCM obj1, SCM obj2);
 294 SCM_API void scm_remember_upto_here (SCM obj1, ...);
 295
 296 /* In GCC we can force a reference to an SCM by making it an input to an
 297    empty asm.  This avoids the code size and slowdown of an actual function
 298    call.  Unfortunately there doesn't seem to be any way to do the varargs
 299    scm_remember_upto_here like this.
 300
 301    __volatile__ ensures nothing will be moved across the asm, and it won't
 302    be optimized away (or only if proved unreachable).  Constraint "g" can be
 303    used on all processors and allows any memory or general register (or
 304    immediate) operand.  The actual asm syntax doesn't matter, we don't want
 305    to use it, just ensure the operand is still alive.  See "Extended Asm" in
 306    the GCC manual for more.  */
 307
 308 #ifdef __GNUC__
 309 #define scm_remember_upto_here_1(x)             \
 310   do {                                          \
 311     __asm__ __volatile__ ("" : : "g" (x));      \
 312   } while (0)
 313 #define scm_remember_upto_here_2(x, y)          \
 314   do {                                          \
 315     scm_remember_upto_here_1 (x);               \
 316     scm_remember_upto_here_1 (y);               \
 317   } while (0)
 318 #endif
 319
 320 SCM_API SCM scm_return_first (SCM elt, ...);
 321 SCM_API int scm_return_first_int (int x, ...);
 322 SCM_API SCM scm_permanent_object (SCM obj);
 323 SCM_API SCM scm_gc_protect_object (SCM obj);
 324 SCM_API SCM scm_gc_unprotect_object (SCM obj);
 325 SCM_API void scm_gc_register_root (SCM *p);
 326 SCM_API void scm_gc_unregister_root (SCM *p);
 327 SCM_API void scm_gc_register_roots (SCM *b, unsigned long n);
 328 SCM_API void scm_gc_unregister_roots (SCM *b, unsigned long n);
 329 SCM_INTERNAL void scm_gc_after_nonlocal_exit (void);
 330 SCM_INTERNAL void scm_storage_prehistory (void);
 331 SCM_INTERNAL void scm_init_gc_protect_object (void);
 332 SCM_INTERNAL void scm_init_gc (void);
 333
 334 #endif  /* SCM_GC_H */
 335
 336 /*
 337   Local Variables:
 338   c-file-style: "gnu"
 339   End:
 340 */