GCC Middle and Back End API Reference
ggc.h
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1/* Garbage collection for the GNU compiler.
2
3 Copyright (C) 1998-2025 Free Software Foundation, Inc.
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it under
8the terms of the GNU General Public License as published by the Free
9Software Foundation; either version 3, or (at your option) any later
10version.
11
12GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or
14FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15for more details.
16
17You should have received a copy of the GNU General Public License
18along 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. */
35typedef 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. */
43typedef 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. */
47extern int gt_pch_note_object (void *, void *, gt_note_pointers,
48 size_t length_override = (size_t)-1);
49
50/* Used by the gt_pch_p_* routines. Register address of a callback
51 pointer. */
52extern void gt_pch_note_callback (void *, void *);
53
54/* Used by the gt_pch_n_* routines. Register that an object has a reorder
55 function. */
56extern void gt_pch_note_reorder (void *, void *, gt_handle_reorder);
57
58/* generated function to clear caches in gc memory. */
59extern void gt_clear_caches ();
60
61/* Mark the object in the first parameter and anything it points to. */
62typedef void (*gt_pointer_walker) (void *);
63
64/* Structures for the easy way to mark roots.
65 In an array, terminated by having base == NULL. */
73#define LAST_GGC_ROOT_TAB { NULL, 0, 0, NULL, NULL }
74/* Pointers to arrays of ggc_root_tab, terminated by NULL. */
75extern const struct ggc_root_tab * const gt_ggc_rtab[];
76extern const struct ggc_root_tab * const gt_ggc_deletable_rtab[];
77extern const struct ggc_root_tab * const gt_pch_scalar_rtab[];
78
79/* If EXPR is not NULL and previously unmarked, mark it and evaluate
80 to true. Otherwise evaluate to false. */
81#define ggc_test_and_set_mark(EXPR) \
82 ((EXPR) != NULL && ((void *) (EXPR)) != (void *) 1 && ! ggc_set_mark (EXPR))
83
84#define ggc_mark(EXPR) \
85 do { \
86 const void *const a__ = (EXPR); \
87 if (a__ != NULL && a__ != (void *) 1) \
88 ggc_set_mark (a__); \
89 } while (0)
90
91/* Actually set the mark on a particular region of memory, but don't
92 follow pointers. This function is called by ggc_mark_*. It
93 returns false if the object was not previously marked; true if
94 the object was already marked, or if, for any other reason,
95 pointers in this data structure should not be traversed. */
96extern bool ggc_set_mark (const void *);
97
98/* Return true if P has been marked, zero otherwise.
99 P must have been allocated by the GC allocator; it mustn't point to
100 static objects, stack variables, or memory allocated with malloc. */
101extern bool ggc_marked_p (const void *);
102
103/* PCH and GGC handling for strings, mostly trivial. */
104extern void gt_pch_n_S (const void *);
105extern void gt_pch_n_S2 (const void *, size_t);
106extern void gt_ggc_m_S (const void *);
107
108/* End of GTY machinery API. */
109
110/* Initialize the string pool. */
111extern void init_stringpool (void);
112
113/* Initialize the garbage collector. */
114extern void init_ggc (void);
115
116/* When true, identifier nodes are considered as GC roots. When
117 false, identifier nodes are treated like any other GC-allocated
118 object, and the identifier hash table is treated as a weak
119 hash. */
120extern bool ggc_protect_identifiers;
121
122/* Write out all GCed objects to F. */
123extern void gt_pch_save (FILE *f);
124
125
126/* Allocation. */
127
128/* The internal primitive. */
129extern void *ggc_internal_alloc (size_t, void (*)(void *), size_t,
130 size_t CXX_MEM_STAT_INFO);
131/* If the second argument is non-NULL, it can't be marked ATTRIBUTE_MALLOC,
132 because ggc_free performs finalization. Add an alias or wrapper used just
133 for the NULL finalizer which can be marked with ATTRIBUTE_MALLOC. */
134extern void *ggc_internal_alloc_no_dtor (size_t, void (*)(void *), size_t,
135 size_t CXX_MEM_STAT_INFO)
136 ATTRIBUTE_MALLOC;
137
138inline void *
143
144extern size_t ggc_round_alloc_size (size_t requested_size);
145
146/* Allocates cleared memory. */
147extern void *ggc_internal_cleared_alloc (size_t, void (*)(void *),
148 size_t, size_t
150extern void *ggc_internal_cleared_alloc_no_dtor (size_t, void (*)(void *),
151 size_t, size_t
153 ATTRIBUTE_MALLOC;
154
155inline void *
160
161/* Resize a block. */
162extern void *ggc_realloc (void *, size_t CXX_MEM_STAT_INFO);
163
164/* Free a block. To be used when known for certain it's not reachable. */
165extern void ggc_free (void *);
166
167extern void dump_ggc_loc_statistics ();
168
169/* Reallocator. */
170#define GGC_RESIZEVEC(T, P, N) \
171 ((T *) ggc_realloc ((P), (N) * sizeof (T) MEM_STAT_INFO))
172
173template<typename T>
174void
175finalize (void *p)
176{
177 static_cast<T *> (p)->~T ();
178}
179
180template<typename T>
181inline bool
183{
184#if GCC_VERSION >= 4003
185 return !__has_trivial_destructor (T);
186#else
187 return true;
188#endif
189}
190
191template<typename T>
192inline T *
194{
196 return static_cast<T *> (ggc_internal_alloc (sizeof (T), finalize<T>, 0, 1
198 else
199 return static_cast<T *> (ggc_internal_alloc_no_dtor (sizeof (T), NULL,
200 0, 1 PASS_MEM_STAT));
201}
202
203/* GGC allocation function that does not call finalizer for type
204 that have need_finalization_p equal to true. User is responsible
205 for calling of the destructor. */
206
207template<typename T>
208inline T *
210{
211 return static_cast<T *> (ggc_internal_alloc_no_dtor (sizeof (T), NULL, 0, 1
213}
214
215template<typename T>
216inline T *
218{
220 return static_cast<T *> (ggc_internal_cleared_alloc (sizeof (T),
221 finalize<T>, 0, 1
223 else
224 return static_cast<T *> (ggc_internal_cleared_alloc_no_dtor (sizeof (T),
225 NULL, 0, 1
227}
228
229template<typename T>
230inline T *
232{
234 return static_cast<T *> (ggc_internal_alloc (c * sizeof (T), finalize<T>,
235 sizeof (T), c PASS_MEM_STAT));
236 else
237 return static_cast<T *> (ggc_internal_alloc_no_dtor (c * sizeof (T),
238 NULL, 0, 0
240}
241
242template<typename T>
243inline T *
245{
247 return static_cast<T *> (ggc_internal_cleared_alloc (c * sizeof (T),
249 sizeof (T), c
251 else
252 return static_cast<T *> (ggc_internal_cleared_alloc_no_dtor (c
253 * sizeof (T),
254 NULL, 0, 0
256}
257
258inline void *
263
264/* Call destructor and free the garbage collected memory. */
265
266template <typename T>
267inline void
269{
270 ptr->~T ();
271 ggc_free (ptr);
272}
273
274/* Allocate a gc-able string, and fill it with LENGTH bytes from CONTENTS.
275 If LENGTH is -1, then CONTENTS is assumed to be a
276 null-terminated string and the memory sized accordingly. */
277extern const char *ggc_alloc_string (const char *contents, int length
279
280/* Make a copy of S, in GC-able memory. */
281#define ggc_strdup(S) ggc_alloc_string ((S), -1 MEM_STAT_INFO)
282
283/* Invoke the collector. Garbage collection occurs only when this
284 function is called, not during allocations. */
289extern void ggc_collect (enum ggc_collect mode = GGC_COLLECT_HEURISTIC);
290
291/* Return unused memory pages to the system. */
292extern void ggc_trim (void);
293
294/* Assume that all GGC memory is reachable and grow the limits for next collection. */
295extern void ggc_grow (void);
296
297/* Register an additional root table. This can be useful for some
298 plugins. Does nothing if the passed pointer is NULL. */
299extern void ggc_register_root_tab (const struct ggc_root_tab *);
300
301/* Read objects previously saved with gt_pch_save from F. */
302extern void gt_pch_restore (FILE *f);
303
304/* Statistics. */
305
306/* Print allocation statistics. */
307extern void ggc_print_statistics (void);
308
309extern void stringpool_statistics (void);
310
311/* Heuristics. */
312extern void init_ggc_heuristics (void);
313
314/* Report current heap memory use to stderr. */
315extern void report_heap_memory_use (void);
316
317#define ggc_alloc_rtvec_sized(NELT) \
318 (rtvec_def *) ggc_internal_alloc (sizeof (struct rtvec_def) \
319 + ((NELT) - 1) * sizeof (rtx)) \
320
321/* Memory statistics passing versions of some allocators. Too few of them to
322 make gengtype produce them, so just define the needed ones here. */
323inline struct rtx_def *
328
329inline union tree_node *
331{
332 return (union tree_node *) ggc_internal_alloc (s PASS_MEM_STAT);
333}
334
335inline union tree_node *
340
341inline gimple *
346
347inline void
348gt_ggc_mx (const char *s)
349{
350 ggc_test_and_set_mark (const_cast<char *> (s));
351}
352
353inline void
354gt_pch_nx (const char *)
355{
356}
357
358inline void gt_pch_nx (bool) { }
359inline void gt_pch_nx (char) { }
360inline void gt_pch_nx (signed char) { }
361inline void gt_pch_nx (unsigned char) { }
362inline void gt_pch_nx (short) { }
363inline void gt_pch_nx (unsigned short) { }
364inline void gt_pch_nx (int) { }
365inline void gt_pch_nx (unsigned int) { }
366inline void gt_pch_nx (long int) { }
367inline void gt_pch_nx (unsigned long int) { }
368inline void gt_pch_nx (long long int) { }
369inline void gt_pch_nx (unsigned long long int) { }
370
371inline void gt_ggc_mx (bool) { }
372inline void gt_ggc_mx (char) { }
373inline void gt_ggc_mx (signed char) { }
374inline void gt_ggc_mx (unsigned char) { }
375inline void gt_ggc_mx (short) { }
376inline void gt_ggc_mx (unsigned short) { }
377inline void gt_ggc_mx (int) { }
378inline void gt_ggc_mx (unsigned int) { }
379inline void gt_ggc_mx (long int) { }
380inline void gt_ggc_mx (unsigned long int) { }
381inline void gt_ggc_mx (long long int) { }
382inline void gt_ggc_mx (unsigned long long int) { }
383
384extern void ggc_common_finalize ();
385
386#endif
void(* gt_pointer_operator)(void *, void *, void *)
Definition coretypes.h:473
static struct token T
Definition gengtype-parse.cc:45
bool ggc_protect_identifiers
Definition ggc-common.cc:35
void ggc_grow(void)
Definition ggc-none.cc:121
union tree_node * ggc_alloc_tree_node_stat(size_t s CXX_MEM_STAT_INFO)
Definition ggc.h:330
const char * ggc_alloc_string(const char *contents, int length CXX_MEM_STAT_INFO)
Definition stringpool.cc:83
void dump_ggc_loc_statistics()
Definition ggc-common.cc:1277
void init_stringpool(void)
Definition stringpool.cc:48
void(* gt_pointer_walker)(void *)
Definition ggc.h:62
void init_ggc_heuristics(void)
Definition ggc-common.cc:1127
void finalize(void *p)
Definition ggc.h:175
void * ggc_alloc_atomic(size_t s CXX_MEM_STAT_INFO)
Definition ggc.h:259
int gt_pch_note_object(void *, void *, gt_note_pointers, size_t length_override=(size_t) -1)
Definition ggc-common.cc:297
void ggc_free(void *)
Definition genmatch.cc:52
#define ggc_test_and_set_mark(EXPR)
Definition ggc.h:81
void gt_ggc_m_S(const void *)
Definition ggc-page.cc:1491
void gt_pch_nx(const char *)
Definition ggc.h:354
T * ggc_alloc(ALONE_CXX_MEM_STAT_INFO)
Definition ggc.h:193
T * ggc_alloc_no_dtor(ALONE_CXX_MEM_STAT_INFO)
Definition ggc.h:209
void gt_pch_note_reorder(void *, void *, gt_handle_reorder)
Definition ggc-common.cc:348
void ggc_print_statistics(void)
Definition ggc-page.cc:2313
void * ggc_realloc(void *, size_t CXX_MEM_STAT_INFO)
bool ggc_set_mark(const void *)
Definition ggc-page.cc:1572
void gt_pch_restore(FILE *f)
Definition ggc-common.cc:774
T * ggc_cleared_vec_alloc(size_t c CXX_MEM_STAT_INFO)
Definition ggc.h:244
void gt_ggc_mx(const char *s)
Definition ggc.h:348
void(* gt_handle_reorder)(void *, void *, gt_pointer_operator, void *)
Definition ggc.h:43
void gt_clear_caches()
void ggc_delete(T *ptr)
Definition ggc.h:268
T * ggc_vec_alloc(size_t c CXX_MEM_STAT_INFO)
Definition ggc.h:231
bool need_finalization_p()
Definition ggc.h:182
void gt_pch_n_S(const void *)
Definition stringpool.cc:217
void(* gt_note_pointers)(void *, void *, gt_pointer_operator, void *)
Definition ggc.h:35
const struct ggc_root_tab *const gt_ggc_deletable_rtab[]
void ggc_common_finalize()
Definition ggc-common.cc:1342
size_t ggc_round_alloc_size(size_t requested_size)
Definition ggc-none.cc:38
void * ggc_internal_cleared_alloc(size_t, void(*)(void *), size_t, size_t CXX_MEM_STAT_INFO)
Definition genmatch.cc:38
void gt_pch_save(FILE *f)
Definition ggc-common.cc:541
void ggc_register_root_tab(const struct ggc_root_tab *)
Definition ggc-common.cc:60
void * ggc_internal_alloc_no_dtor(size_t, void(*)(void *), size_t, size_t CXX_MEM_STAT_INFO) ATTRIBUTE_MALLOC
void * ggc_internal_cleared_alloc_no_dtor(size_t, void(*)(void *), size_t, size_t CXX_MEM_STAT_INFO) ATTRIBUTE_MALLOC
Definition genmatch.cc:45
void ggc_trim(void)
Definition ggc-none.cc:126
void init_ggc(void)
Definition ggc-page.cc:1760
T * ggc_cleared_alloc(ALONE_CXX_MEM_STAT_INFO)
Definition ggc.h:217
struct rtx_def * ggc_alloc_rtx_def_stat(size_t s CXX_MEM_STAT_INFO)
Definition ggc.h:324
void gt_pch_note_callback(void *, void *)
Definition ggc-common.cc:330
gimple * ggc_alloc_cleared_gimple_statement_stat(size_t s CXX_MEM_STAT_INFO)
Definition ggc.h:342
ggc_collect
Definition ggc.h:285
@ GGC_COLLECT_FORCE
Definition ggc.h:287
@ GGC_COLLECT_HEURISTIC
Definition ggc.h:286
void stringpool_statistics(void)
Definition stringpool.cc:149
void report_heap_memory_use(void)
Definition ggc-common.cc:1325
const struct ggc_root_tab *const gt_ggc_rtab[]
void * ggc_internal_alloc(size_t, void(*)(void *), size_t, size_t CXX_MEM_STAT_INFO)
Definition ggc-none.cc:78
const struct ggc_root_tab *const gt_pch_scalar_rtab[]
bool ggc_marked_p(const void *)
Definition ggc-page.cc:1608
void gt_pch_n_S2(const void *, size_t)
Definition stringpool.cc:224
union tree_node * ggc_alloc_cleared_tree_node_stat(size_t s CXX_MEM_STAT_INFO)
Definition ggc.h:336
#define ALONE_CXX_MEM_STAT_INFO
Definition statistics.h:57
#define PASS_MEM_STAT
Definition statistics.h:54
#define CXX_MEM_STAT_INFO
Definition statistics.h:58
Definition ggc.h:66
size_t stride
Definition ggc.h:69
void * base
Definition ggc.h:67
gt_pointer_walker pchw
Definition ggc.h:71
gt_pointer_walker cb
Definition ggc.h:70
size_t nelt
Definition ggc.h:68
Definition gimple.h:221
Definition rtl.h:312
#define NULL
Definition system.h:50
static void finalize()
Definition toplev.cc:2047