gcc/ggc.h

   1 /* Garbage collection for the GNU compiler.
   2
   3    Copyright (C) 1998-2021 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_GGC_H
  22 #define GCC_GGC_H
  23
  24 /* Symbols are marked with `ggc' for `gcc gc' so as not to interfere with
  25    an external gc library that might be linked in.  */
  26
  27 /* Internal functions and data structures used by the GTY
  28    machinery, including the generated gt*.[hc] files.  */
  29
  30 #include "gtype-desc.h"
  31
  32 /* One of these applies its third parameter (with cookie in the fourth
  33    parameter) to each pointer in the object pointed to by the first
  34    parameter, using the second parameter.  */
  35 typedef void (*gt_note_pointers) (void *, void *, gt_pointer_operator,
  36                                   void *);
  37
  38 /* One of these is called before objects are re-ordered in memory.
  39    The first parameter is the original object, the second is the
  40    subobject that has had its pointers reordered, the third parameter
  41    can compute the new values of a pointer when given the cookie in
  42    the fourth parameter.  */
  43 typedef void (*gt_handle_reorder) (void *, void *, gt_pointer_operator,
  44                                    void *);
  45
  46 /* Used by the gt_pch_n_* routines.  Register an object in the hash table.  */
  47 extern int gt_pch_note_object (void *, void *, gt_note_pointers);
  48
  49 /* Used by the gt_pch_n_* routines.  Register that an object has a reorder
  50    function.  */
  51 extern void gt_pch_note_reorder (void *, void *, gt_handle_reorder);
  52
  53 /* generated function to clear caches in gc memory.  */
  54 extern void gt_clear_caches ();
  55
  56 /* Mark the object in the first parameter and anything it points to.  */
  57 typedef void (*gt_pointer_walker) (void *);
  58
  59 /* Structures for the easy way to mark roots.
  60    In an array, terminated by having base == NULL.  */
  61 struct ggc_root_tab {
  62   void *base;
  63   size_t nelt;
  64   size_t stride;
  65   gt_pointer_walker cb;
  66   gt_pointer_walker pchw;
  67 };
  68 #define LAST_GGC_ROOT_TAB { NULL, 0, 0, NULL, NULL }
  69 /* Pointers to arrays of ggc_root_tab, terminated by NULL.  */
  70 extern const struct ggc_root_tab * const gt_ggc_rtab[];
  71 extern const struct ggc_root_tab * const gt_ggc_deletable_rtab[];
  72 extern const struct ggc_root_tab * const gt_pch_scalar_rtab[];
  73
  74 /* If EXPR is not NULL and previously unmarked, mark it and evaluate
  75    to true.  Otherwise evaluate to false.  */
  76 #define ggc_test_and_set_mark(EXPR) \
  77   ((EXPR) != NULL && ((void *) (EXPR)) != (void *) 1 && ! ggc_set_mark (EXPR))
  78
  79 #define ggc_mark(EXPR)                          \
  80   do {                                          \
  81     const void *const a__ = (EXPR);             \
  82     if (a__ != NULL && a__ != (void *) 1)       \
  83       ggc_set_mark (a__);                       \
  84   } while (0)
  85
  86 /* Actually set the mark on a particular region of memory, but don't
  87    follow pointers.  This function is called by ggc_mark_*.  It
  88    returns zero if the object was not previously marked; nonzero if
  89    the object was already marked, or if, for any other reason,
  90    pointers in this data structure should not be traversed.  */
  91 extern int ggc_set_mark (const void *);
  92
  93 /* Return 1 if P has been marked, zero otherwise.
  94    P must have been allocated by the GC allocator; it mustn't point to
  95    static objects, stack variables, or memory allocated with malloc.  */
  96 extern int ggc_marked_p (const void *);
  97
  98 /* PCH and GGC handling for strings, mostly trivial.  */
  99 extern void gt_pch_n_S (const void *);
 100 extern void gt_ggc_m_S (const void *);
 101
 102 /* End of GTY machinery API.  */
 103
 104 /* Initialize the string pool.  */
 105 extern void init_stringpool (void);
 106
 107 /* Initialize the garbage collector.  */
 108 extern void init_ggc (void);
 109
 110 /* When true, identifier nodes are considered as GC roots.  When
 111    false, identifier nodes are treated like any other GC-allocated
 112    object, and the identifier hash table is treated as a weak
 113    hash.  */
 114 extern bool ggc_protect_identifiers;
 115
 116 /* Write out all GCed objects to F.  */
 117 extern void gt_pch_save (FILE *f);
 118
 119 \f
 120 /* Allocation.  */
 121
 122 /* The internal primitive.  */
 123 extern void *ggc_internal_alloc (size_t, void (*)(void *), size_t,
 124                                  size_t CXX_MEM_STAT_INFO)
 125      ATTRIBUTE_MALLOC;
 126
 127 inline void *
 128 ggc_internal_alloc (size_t s CXX_MEM_STAT_INFO)
 129 {
 130   return ggc_internal_alloc (s, NULL, 0, 1 PASS_MEM_STAT);
 131 }
 132
 133 extern size_t ggc_round_alloc_size (size_t requested_size);
 134
 135 /* Allocates cleared memory.  */
 136 extern void *ggc_internal_cleared_alloc (size_t, void (*)(void *),
 137                                          size_t, size_t
 138                                          CXX_MEM_STAT_INFO) ATTRIBUTE_MALLOC;
 139
 140 inline void *
 141 ggc_internal_cleared_alloc (size_t s CXX_MEM_STAT_INFO)
 142 {
 143   return ggc_internal_cleared_alloc (s, NULL, 0, 1 PASS_MEM_STAT);
 144 }
 145
 146 /* Resize a block.  */
 147 extern void *ggc_realloc (void *, size_t CXX_MEM_STAT_INFO);
 148
 149 /* Free a block.  To be used when known for certain it's not reachable.  */
 150 extern void ggc_free (void *);
 151
 152 extern void dump_ggc_loc_statistics ();
 153
 154 /* Reallocator.  */
 155 #define GGC_RESIZEVEC(T, P, N) \
 156     ((T *) ggc_realloc ((P), (N) * sizeof (T) MEM_STAT_INFO))
 157
 158 template<typename T>
 159 void
 160 finalize (void *p)
 161 {
 162   static_cast<T *> (p)->~T ();
 163 }
 164
 165 template<typename T>
 166 inline bool
 167 need_finalization_p ()
 168 {
 169 #if GCC_VERSION >= 4003
 170   return !__has_trivial_destructor (T);
 171 #else
 172   return true;
 173 #endif
 174 }
 175
 176 template<typename T>
 177 inline T *
 178 ggc_alloc (ALONE_CXX_MEM_STAT_INFO)
 179 {
 180   if (need_finalization_p<T> ())
 181     return static_cast<T *> (ggc_internal_alloc (sizeof (T), finalize<T>, 0, 1
 182                                                  PASS_MEM_STAT));
 183   else
 184     return static_cast<T *> (ggc_internal_alloc (sizeof (T), NULL, 0, 1
 185                                                  PASS_MEM_STAT));
 186 }
 187
 188 /* GGC allocation function that does not call finalizer for type
 189    that have need_finalization_p equal to true.  User is responsible
 190    for calling of the destructor.  */
 191
 192 template<typename T>
 193 inline T *
 194 ggc_alloc_no_dtor (ALONE_CXX_MEM_STAT_INFO)
 195 {
 196   return static_cast<T *> (ggc_internal_alloc (sizeof (T), NULL, 0, 1
 197                                                PASS_MEM_STAT));
 198 }
 199
 200 template<typename T>
 201 inline T *
 202 ggc_cleared_alloc (ALONE_CXX_MEM_STAT_INFO)
 203 {
 204   if (need_finalization_p<T> ())
 205     return static_cast<T *> (ggc_internal_cleared_alloc (sizeof (T),
 206                                                          finalize<T>, 0, 1
 207                                                          PASS_MEM_STAT));
 208   else
 209     return static_cast<T *> (ggc_internal_cleared_alloc (sizeof (T), NULL, 0, 1
 210                                                          PASS_MEM_STAT));
 211 }
 212
 213 template<typename T>
 214 inline T *
 215 ggc_vec_alloc (size_t c CXX_MEM_STAT_INFO)
 216 {
 217   if (need_finalization_p<T> ())
 218     return static_cast<T *> (ggc_internal_alloc (c * sizeof (T), finalize<T>,
 219                                                  sizeof (T), c PASS_MEM_STAT));
 220   else
 221     return static_cast<T *> (ggc_internal_alloc (c * sizeof (T), NULL, 0, 0
 222                                                  PASS_MEM_STAT));
 223 }
 224
 225 template<typename T>
 226 inline T *
 227 ggc_cleared_vec_alloc (size_t c CXX_MEM_STAT_INFO)
 228 {
 229   if (need_finalization_p<T> ())
 230     return static_cast<T *> (ggc_internal_cleared_alloc (c * sizeof (T),
 231                                                          finalize<T>,
 232                                                          sizeof (T), c
 233                                                          PASS_MEM_STAT));
 234   else
 235     return static_cast<T *> (ggc_internal_cleared_alloc (c * sizeof (T), NULL,
 236                                                          0, 0 PASS_MEM_STAT));
 237 }
 238
 239 inline void *
 240 ggc_alloc_atomic (size_t s CXX_MEM_STAT_INFO)
 241 {
 242     return ggc_internal_alloc (s PASS_MEM_STAT);
 243 }
 244
 245 /* Call destructor and free the garbage collected memory.  */
 246
 247 template <typename T>
 248 inline void
 249 ggc_delete (T *ptr)
 250 {
 251   ptr->~T ();
 252   ggc_free (ptr);
 253 }
 254
 255 /* Allocate a gc-able string, and fill it with LENGTH bytes from CONTENTS.
 256    If LENGTH is -1, then CONTENTS is assumed to be a
 257    null-terminated string and the memory sized accordingly.  */
 258 extern const char *ggc_alloc_string (const char *contents, int length
 259                                      CXX_MEM_STAT_INFO);
 260
 261 /* Make a copy of S, in GC-able memory.  */
 262 #define ggc_strdup(S) ggc_alloc_string ((S), -1 MEM_STAT_INFO)
 263
 264 /* Invoke the collector.  Garbage collection occurs only when this
 265    function is called, not during allocations.  */
 266 extern void ggc_collect (void);
 267
 268 /* Return unused memory pages to the system.  */
 269 extern void ggc_trim (void);
 270
 271 /* Assume that all GGC memory is reachable and grow the limits for next collection. */
 272 extern void ggc_grow (void);
 273
 274 /* Register an additional root table.  This can be useful for some
 275    plugins.  Does nothing if the passed pointer is NULL. */
 276 extern void ggc_register_root_tab (const struct ggc_root_tab *);
 277
 278 /* Read objects previously saved with gt_pch_save from F.  */
 279 extern void gt_pch_restore (FILE *f);
 280 \f
 281 /* Statistics.  */
 282
 283 /* Print allocation statistics.  */
 284 extern void ggc_print_statistics (void);
 285
 286 extern void stringpool_statistics (void);
 287
 288 /* Heuristics.  */
 289 extern void init_ggc_heuristics (void);
 290
 291 /* Report current heap memory use to stderr.  */
 292 extern void report_heap_memory_use (void);
 293
 294 #define ggc_alloc_rtvec_sized(NELT)                             \
 295   (rtvec_def *) ggc_internal_alloc (sizeof (struct rtvec_def)           \
 296                        + ((NELT) - 1) * sizeof (rtx))           \
 297
 298 /* Memory statistics passing versions of some allocators.  Too few of them to
 299    make gengtype produce them, so just define the needed ones here.  */
 300 inline struct rtx_def *
 301 ggc_alloc_rtx_def_stat (size_t s CXX_MEM_STAT_INFO)
 302 {
 303   return (struct rtx_def *) ggc_internal_alloc (s PASS_MEM_STAT);
 304 }
 305
 306 inline union tree_node *
 307 ggc_alloc_tree_node_stat (size_t s CXX_MEM_STAT_INFO)
 308 {
 309   return (union tree_node *) ggc_internal_alloc (s PASS_MEM_STAT);
 310 }
 311
 312 inline union tree_node *
 313 ggc_alloc_cleared_tree_node_stat (size_t s CXX_MEM_STAT_INFO)
 314 {
 315   return (union tree_node *) ggc_internal_cleared_alloc (s PASS_MEM_STAT);
 316 }
 317
 318 inline gimple *
 319 ggc_alloc_cleared_gimple_statement_stat (size_t s CXX_MEM_STAT_INFO)
 320 {
 321   return (gimple *) ggc_internal_cleared_alloc (s PASS_MEM_STAT);
 322 }
 323
 324 inline void
 325 gt_ggc_mx (const char *s)
 326 {
 327   ggc_test_and_set_mark (const_cast<char *> (s));
 328 }
 329
 330 inline void
 331 gt_pch_nx (const char *)
 332 {
 333 }
 334
 335 inline void
 336 gt_ggc_mx (int)
 337 {
 338 }
 339
 340 inline void
 341 gt_pch_nx (int)
 342 {
 343 }
 344
 345 inline void
 346 gt_pch_nx (unsigned int)
 347 {
 348 }
 349
 350 #endif