/usr/include/gc/gc_mark.h is in libgc-dev 1:7.4.2-7.3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 | /*
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 2001 by Hewlett-Packard Company. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*
*/
/*
* This contains interfaces to the GC marker that are likely to be useful to
* clients that provide detailed heap layout information to the collector.
* This interface should not be used by normal C or C++ clients.
* It will be useful to runtimes for other languages.
*
* This is an experts-only interface! There are many ways to break the
* collector in subtle ways by using this functionality.
*/
#ifndef GC_MARK_H
#define GC_MARK_H
#ifndef GC_H
# include "gc.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif
/* A client supplied mark procedure. Returns new mark stack pointer. */
/* Primary effect should be to push new entries on the mark stack. */
/* Mark stack pointer values are passed and returned explicitly. */
/* Global variables describing mark stack are not necessarily valid. */
/* (This usually saves a few cycles by keeping things in registers.) */
/* Assumed to scan about GC_PROC_BYTES on average. If it needs to do */
/* much more work than that, it should do it in smaller pieces by */
/* pushing itself back on the mark stack. */
/* Note that it should always do some work (defined as marking some */
/* objects) before pushing more than one entry on the mark stack. */
/* This is required to ensure termination in the event of mark stack */
/* overflows. */
/* This procedure is always called with at least one empty entry on the */
/* mark stack. */
/* Currently we require that mark procedures look for pointers in a */
/* subset of the places the conservative marker would. It must be safe */
/* to invoke the normal mark procedure instead. */
/* WARNING: Such a mark procedure may be invoked on an unused object */
/* residing on a free list. Such objects are cleared, except for a */
/* free list link field in the first word. Thus mark procedures may */
/* not count on the presence of a type descriptor, and must handle this */
/* case correctly somehow. */
#define GC_PROC_BYTES 100
#ifdef GC_BUILD
struct GC_ms_entry;
#else
struct GC_ms_entry { void *opaque; };
#endif
typedef struct GC_ms_entry * (*GC_mark_proc)(GC_word * /* addr */,
struct GC_ms_entry * /* mark_stack_ptr */,
struct GC_ms_entry * /* mark_stack_limit */,
GC_word /* env */);
#define GC_LOG_MAX_MARK_PROCS 6
#define GC_MAX_MARK_PROCS (1 << GC_LOG_MAX_MARK_PROCS)
/* In a few cases it's necessary to assign statically known indices to */
/* certain mark procs. Thus we reserve a few for well known clients. */
/* (This is necessary if mark descriptors are compiler generated.) */
#define GC_RESERVED_MARK_PROCS 8
#define GC_GCJ_RESERVED_MARK_PROC_INDEX 0
/* Object descriptors on mark stack or in objects. Low order two */
/* bits are tags distinguishing among the following 4 possibilities */
/* for the high order 30 bits. */
#define GC_DS_TAG_BITS 2
#define GC_DS_TAGS ((1 << GC_DS_TAG_BITS) - 1)
#define GC_DS_LENGTH 0 /* The entire word is a length in bytes that */
/* must be a multiple of 4. */
#define GC_DS_BITMAP 1 /* 30 (62) bits are a bitmap describing pointer */
/* fields. The msb is 1 if the first word */
/* is a pointer. */
/* (This unconventional ordering sometimes */
/* makes the marker slightly faster.) */
/* Zeroes indicate definite nonpointers. Ones */
/* indicate possible pointers. */
/* Only usable if pointers are word aligned. */
#define GC_DS_PROC 2
/* The objects referenced by this object can be */
/* pushed on the mark stack by invoking */
/* PROC(descr). ENV(descr) is passed as the */
/* last argument. */
#define GC_MAKE_PROC(proc_index, env) \
(((((env) << GC_LOG_MAX_MARK_PROCS) \
| (proc_index)) << GC_DS_TAG_BITS) | GC_DS_PROC)
#define GC_DS_PER_OBJECT 3 /* The real descriptor is at the */
/* byte displacement from the beginning of the */
/* object given by descr & ~DS_TAGS */
/* If the descriptor is negative, the real */
/* descriptor is at (*<object_start>) - */
/* (descr & ~DS_TAGS) - GC_INDIR_PER_OBJ_BIAS */
/* The latter alternative can be used if each */
/* object contains a type descriptor in the */
/* first word. */
/* Note that in the multi-threaded environments */
/* per-object descriptors must be located in */
/* either the first two or last two words of */
/* the object, since only those are guaranteed */
/* to be cleared while the allocation lock is */
/* held. */
#define GC_INDIR_PER_OBJ_BIAS 0x10
GC_API void * GC_least_plausible_heap_addr;
GC_API void * GC_greatest_plausible_heap_addr;
/* Bounds on the heap. Guaranteed valid */
/* Likely to include future heap expansion. */
/* Hence usually includes not-yet-mapped */
/* memory. */
/* Handle nested references in a custom mark procedure. */
/* Check if obj is a valid object. If so, ensure that it is marked. */
/* If it was not previously marked, push its contents onto the mark */
/* stack for future scanning. The object will then be scanned using */
/* its mark descriptor. */
/* Returns the new mark stack pointer. */
/* Handles mark stack overflows correctly. */
/* Since this marks first, it makes progress even if there are mark */
/* stack overflows. */
/* Src is the address of the pointer to obj, which is used only */
/* for back pointer-based heap debugging. */
/* It is strongly recommended that most objects be handled without mark */
/* procedures, e.g. with bitmap descriptors, and that mark procedures */
/* be reserved for exceptional cases. That will ensure that */
/* performance of this call is not extremely performance critical. */
/* (Otherwise we would need to inline GC_mark_and_push completely, */
/* which would tie the client code to a fixed collector version.) */
/* Note that mark procedures should explicitly call FIXUP_POINTER() */
/* if required. */
GC_API struct GC_ms_entry * GC_CALL GC_mark_and_push(void * /* obj */,
struct GC_ms_entry * /* mark_stack_ptr */,
struct GC_ms_entry * /* mark_stack_limit */,
void ** /* src */);
#define GC_MARK_AND_PUSH(obj, msp, lim, src) \
((GC_word)(obj) >= (GC_word)GC_least_plausible_heap_addr && \
(GC_word)(obj) <= (GC_word)GC_greatest_plausible_heap_addr ? \
GC_mark_and_push(obj, msp, lim, src) : (msp))
GC_API size_t GC_debug_header_size;
/* The size of the header added to objects allocated through */
/* the GC_debug routines. */
/* Defined as a variable so that client mark procedures don't */
/* need to be recompiled for collector version changes. */
#define GC_USR_PTR_FROM_BASE(p) ((void *)((char *)(p) + GC_debug_header_size))
/* And some routines to support creation of new "kinds", e.g. with */
/* custom mark procedures, by language runtimes. */
/* The _inner versions assume the caller holds the allocation lock. */
/* Return a new free list array. */
GC_API void ** GC_CALL GC_new_free_list(void);
GC_API void ** GC_CALL GC_new_free_list_inner(void);
/* Return a new kind, as specified. */
GC_API unsigned GC_CALL GC_new_kind(void ** /* free_list */,
GC_word /* mark_descriptor_template */,
int /* add_size_to_descriptor */,
int /* clear_new_objects */) GC_ATTR_NONNULL(1);
/* The last two parameters must be zero or one. */
GC_API unsigned GC_CALL GC_new_kind_inner(void ** /* free_list */,
GC_word /* mark_descriptor_template */,
int /* add_size_to_descriptor */,
int /* clear_new_objects */) GC_ATTR_NONNULL(1);
/* Return a new mark procedure identifier, suitable for use as */
/* the first argument in GC_MAKE_PROC. */
GC_API unsigned GC_CALL GC_new_proc(GC_mark_proc);
GC_API unsigned GC_CALL GC_new_proc_inner(GC_mark_proc);
/* Allocate an object of a given kind. By default, there are only */
/* a few kinds: composite (pointer-free), atomic, uncollectible, etc. */
/* We claim it is possible for clever client code that understands the */
/* GC internals to add more, e.g. to communicate object layout */
/* information to the collector. Note that in the multi-threaded */
/* contexts, this is usually unsafe for kinds that have the descriptor */
/* in the object itself, since there is otherwise a window in which */
/* the descriptor is not correct. Even in the single-threaded case, */
/* we need to be sure that cleared objects on a free list don't */
/* cause a GC crash if they are accidentally traced. */
GC_API GC_ATTR_MALLOC void * GC_CALL GC_generic_malloc(size_t /* lb */,
int /* k */);
GC_API GC_ATTR_MALLOC void * GC_CALL GC_generic_malloc_ignore_off_page(
size_t /* lb */, int /* k */);
/* As above, but pointers to past the */
/* first page of the resulting object */
/* are ignored. */
typedef void (GC_CALLBACK * GC_describe_type_fn)(void * /* p */,
char * /* out_buf */);
/* A procedure which */
/* produces a human-readable */
/* description of the "type" of object */
/* p into the buffer out_buf of length */
/* GC_TYPE_DESCR_LEN. This is used by */
/* the debug support when printing */
/* objects. */
/* These functions should be as robust */
/* as possible, though we do avoid */
/* invoking them on objects on the */
/* global free list. */
#define GC_TYPE_DESCR_LEN 40
GC_API void GC_CALL GC_register_describe_type_fn(int /* kind */,
GC_describe_type_fn);
/* Register a describe_type function */
/* to be used when printing objects */
/* of a particular kind. */
/* Clear some of the inaccessible part of the stack. Returns its */
/* argument, so it can be used in a tail call position, hence clearing */
/* another frame. Argument may be NULL. */
GC_API void * GC_CALL GC_clear_stack(void *);
/* Set and get the client notifier on collections. The client function */
/* is called at the start of every full GC (called with the allocation */
/* lock held). May be 0. This is a really tricky interface to use */
/* correctly. Unless you really understand the collector internals, */
/* the callback should not, directly or indirectly, make any GC_ or */
/* potentially blocking calls. In particular, it is not safe to */
/* allocate memory using the garbage collector from within the callback */
/* function. Both the setter and getter acquire the GC lock. */
typedef void (GC_CALLBACK * GC_start_callback_proc)(void);
GC_API void GC_CALL GC_set_start_callback(GC_start_callback_proc);
GC_API GC_start_callback_proc GC_CALL GC_get_start_callback(void);
/* Slow/general mark bit manipulation. The caller must hold the */
/* allocation lock. GC_is_marked returns 1 (TRUE) or 0. */
GC_API int GC_CALL GC_is_marked(const void *) GC_ATTR_NONNULL(1);
GC_API void GC_CALL GC_clear_mark_bit(const void *) GC_ATTR_NONNULL(1);
GC_API void GC_CALL GC_set_mark_bit(const void *) GC_ATTR_NONNULL(1);
/* Push everything in the given range onto the mark stack. */
/* (GC_push_conditional pushes either all or only dirty pages depending */
/* on the third argument.) */
GC_API void GC_CALL GC_push_all(char * /* bottom */, char * /* top */);
GC_API void GC_CALL GC_push_conditional(char * /* bottom */, char * /* top */,
int /* bool all */);
/* Set and get the client push-other-roots procedure. A client */
/* supplied procedure should also call the original procedure. */
/* Note that both the setter and getter require some external */
/* synchronization to avoid data race. */
typedef void (GC_CALLBACK * GC_push_other_roots_proc)(void);
GC_API void GC_CALL GC_set_push_other_roots(GC_push_other_roots_proc);
GC_API GC_push_other_roots_proc GC_CALL GC_get_push_other_roots(void);
#ifdef __cplusplus
} /* end of extern "C" */
#endif
#endif /* GC_MARK_H */
|