Annotation of OpenXM_contrib/gc/gc_mark.h, Revision 1.1.1.2
1.1 maekawa 1: /*
2: * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
3: *
4: * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5: * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
6: *
7: * Permission is hereby granted to use or copy this program
8: * for any purpose, provided the above notices are retained on all copies.
9: * Permission to modify the code and to distribute modified code is granted,
10: * provided the above notices are retained, and a notice that the code was
11: * modified is included with the above copyright notice.
12: *
13: */
14: /* Boehm, November 7, 1994 4:56 pm PST */
15:
16: /*
17: * Declarations of mark stack. Needed by marker and client supplied mark
18: * routines. To be included after gc_priv.h.
19: */
20: #ifndef GC_MARK_H
21: # define GC_MARK_H
22:
23: /* A client supplied mark procedure. Returns new mark stack pointer. */
24: /* Primary effect should be to push new entries on the mark stack. */
25: /* Mark stack pointer values are passed and returned explicitly. */
26: /* Global variables decribing mark stack are not necessarily valid. */
27: /* (This usually saves a few cycles by keeping things in registers.) */
28: /* Assumed to scan about PROC_BYTES on average. If it needs to do */
29: /* much more work than that, it should do it in smaller pieces by */
30: /* pushing itself back on the mark stack. */
31: /* Note that it should always do some work (defined as marking some */
32: /* objects) before pushing more than one entry on the mark stack. */
33: /* This is required to ensure termination in the event of mark stack */
34: /* overflows. */
35: /* This procedure is always called with at least one empty entry on the */
36: /* mark stack. */
37: /* Currently we require that mark procedures look for pointers in a */
38: /* subset of the places the conservative marker would. It must be safe */
39: /* to invoke the normal mark procedure instead. */
40: # define PROC_BYTES 100
41: /* The real declarations of the following are in gc_priv.h, so that */
42: /* we can avoid scanning the following table. */
43: /*
44: typedef struct ms_entry * (*mark_proc)( word * addr, mark_stack_ptr,
45: mark_stack_limit, env );
46:
47: # define LOG_MAX_MARK_PROCS 6
48: # define MAX_MARK_PROCS (1 << LOG_MAX_MARK_PROCS)
49: extern mark_proc GC_mark_procs[MAX_MARK_PROCS];
50: */
51:
52: extern word GC_n_mark_procs;
53:
54: /* Object descriptors on mark stack or in objects. Low order two */
55: /* bits are tags distinguishing among the following 4 possibilities */
56: /* for the high order 30 bits. */
57: #define DS_TAG_BITS 2
58: #define DS_TAGS ((1 << DS_TAG_BITS) - 1)
59: #define DS_LENGTH 0 /* The entire word is a length in bytes that */
60: /* must be a multiple of 4. */
61: #define DS_BITMAP 1 /* 30 bits are a bitmap describing pointer */
62: /* fields. The msb is 1 iff the first word */
63: /* is a pointer. */
64: /* (This unconventional ordering sometimes */
65: /* makes the marker slightly faster.) */
66: /* Zeroes indicate definite nonpointers. Ones */
67: /* indicate possible pointers. */
68: /* Only usable if pointers are word aligned. */
69: # define BITMAP_BITS (WORDSZ - DS_TAG_BITS)
70: #define DS_PROC 2
71: /* The objects referenced by this object can be */
72: /* pushed on the mark stack by invoking */
73: /* PROC(descr). ENV(descr) is passed as the */
74: /* last argument. */
75: # define PROC(descr) \
76: (GC_mark_procs[((descr) >> DS_TAG_BITS) & (MAX_MARK_PROCS-1)])
77: # define ENV(descr) \
78: ((descr) >> (DS_TAG_BITS + LOG_MAX_MARK_PROCS))
79: # define MAX_ENV \
80: (((word)1 << (WORDSZ - DS_TAG_BITS - LOG_MAX_MARK_PROCS)) - 1)
81: # define MAKE_PROC(proc_index, env) \
82: (((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \
83: | DS_PROC)
84: #define DS_PER_OBJECT 3 /* The real descriptor is at the */
85: /* byte displacement from the beginning of the */
86: /* object given by descr & ~DS_TAGS */
87:
88: typedef struct ms_entry {
89: word * mse_start; /* First word of object */
90: word mse_descr; /* Descriptor; low order two bits are tags, */
91: /* identifying the upper 30 bits as one of the */
92: /* following: */
93: } mse;
94:
95: extern word GC_mark_stack_size;
96:
97: extern mse * GC_mark_stack_top;
98:
99: extern mse * GC_mark_stack;
100:
101: word GC_find_start();
102:
103: mse * GC_signal_mark_stack_overflow();
104:
105: # ifdef GATHERSTATS
106: # define ADD_TO_ATOMIC(sz) GC_atomic_in_use += (sz)
107: # define ADD_TO_COMPOSITE(sz) GC_composite_in_use += (sz)
108: # else
109: # define ADD_TO_ATOMIC(sz)
110: # define ADD_TO_COMPOSITE(sz)
111: # endif
112:
113: /* Push the object obj with corresponding heap block header hhdr onto */
114: /* the mark stack. */
115: # define PUSH_OBJ(obj, hhdr, mark_stack_top, mark_stack_limit) \
116: { \
117: register word _descr = (hhdr) -> hb_descr; \
118: \
119: if (_descr == 0) { \
120: ADD_TO_ATOMIC((hhdr) -> hb_sz); \
121: } else { \
122: ADD_TO_COMPOSITE((hhdr) -> hb_sz); \
123: mark_stack_top++; \
124: if (mark_stack_top >= mark_stack_limit) { \
125: mark_stack_top = GC_signal_mark_stack_overflow(mark_stack_top); \
126: } \
127: mark_stack_top -> mse_start = (obj); \
128: mark_stack_top -> mse_descr = _descr; \
129: } \
130: }
131:
132: #ifdef PRINT_BLACK_LIST
133: # define GC_FIND_START(current, hhdr, source) \
134: GC_find_start(current, hhdr, source)
135: #else
136: # define GC_FIND_START(current, hhdr, source) \
137: GC_find_start(current, hhdr)
138: #endif
139:
140: /* Push the contents of current onto the mark stack if it is a valid */
141: /* ptr to a currently unmarked object. Mark it. */
142: /* If we assumed a standard-conforming compiler, we could probably */
143: /* generate the exit_label transparently. */
144: # define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \
145: source, exit_label) \
146: { \
147: register int displ; /* Displacement in block; first bytes, then words */ \
148: register hdr * hhdr; \
149: register map_entry_type map_entry; \
150: \
151: GET_HDR(current,hhdr); \
152: if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { \
153: current = GC_FIND_START(current, hhdr, (word)source); \
154: if (current == 0) goto exit_label; \
155: hhdr = HDR(current); \
156: } \
157: displ = HBLKDISPL(current); \
158: map_entry = MAP_ENTRY((hhdr -> hb_map), displ); \
159: if (map_entry == OBJ_INVALID) { \
160: GC_ADD_TO_BLACK_LIST_NORMAL(current, source); goto exit_label; \
161: } \
162: displ = BYTES_TO_WORDS(displ); \
163: displ -= map_entry; \
164: \
165: { \
166: register word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(displ); \
167: register word mark_word = *mark_word_addr; \
168: register word mark_bit = (word)1 << modWORDSZ(displ); \
169: \
170: if (mark_word & mark_bit) { \
171: /* Mark bit is already set */ \
172: goto exit_label; \
173: } \
1.1.1.2 ! maekawa 174: GC_STORE_BACK_PTR((ptr_t)source, (ptr_t)HBLKPTR(current) \
! 175: + WORDS_TO_BYTES(displ)); \
1.1 maekawa 176: *mark_word_addr = mark_word | mark_bit; \
177: } \
178: PUSH_OBJ(((word *)(HBLKPTR(current)) + displ), hhdr, \
179: mark_stack_top, mark_stack_limit) \
180: exit_label: ; \
181: }
182:
183: #ifdef PRINT_BLACK_LIST
184: # define PUSH_ONE_CHECKED(p, ip, source) \
185: GC_push_one_checked(p, ip, (ptr_t)(source))
186: #else
187: # define PUSH_ONE_CHECKED(p, ip, source) \
188: GC_push_one_checked(p, ip)
189: #endif
190:
191: /*
192: * Push a single value onto mark stack. Mark from the object pointed to by p.
193: * P is considered valid even if it is an interior pointer.
194: * Previously marked objects are not pushed. Hence we make progress even
195: * if the mark stack overflows.
196: */
197: # define GC_PUSH_ONE_STACK(p, source) \
198: if ((ptr_t)(p) >= GC_least_plausible_heap_addr \
199: && (ptr_t)(p) < GC_greatest_plausible_heap_addr) { \
200: PUSH_ONE_CHECKED(p, TRUE, source); \
201: }
202:
203: /*
204: * As above, but interior pointer recognition as for
205: * normal for heap pointers.
206: */
207: # ifdef ALL_INTERIOR_POINTERS
208: # define AIP TRUE
209: # else
210: # define AIP FALSE
211: # endif
212: # define GC_PUSH_ONE_HEAP(p,source) \
213: if ((ptr_t)(p) >= GC_least_plausible_heap_addr \
214: && (ptr_t)(p) < GC_greatest_plausible_heap_addr) { \
215: PUSH_ONE_CHECKED(p,AIP,source); \
216: }
217:
218: /*
219: * Mark from one finalizable object using the specified
220: * mark proc. May not mark the object pointed to by
221: * real_ptr. That is the job of the caller, if appropriate
222: */
223: # define GC_MARK_FO(real_ptr, mark_proc) \
224: { \
225: (*(mark_proc))(real_ptr); \
226: while (!GC_mark_stack_empty()) GC_mark_from_mark_stack(); \
227: if (GC_mark_state != MS_NONE) { \
228: GC_set_mark_bit(real_ptr); \
229: while (!GC_mark_some((ptr_t)0)); \
230: } \
231: }
232:
233: extern GC_bool GC_mark_stack_too_small;
234: /* We need a larger mark stack. May be */
235: /* set by client supplied mark routines.*/
236:
237: typedef int mark_state_t; /* Current state of marking, as follows:*/
238: /* Used to remember where we are during */
239: /* concurrent marking. */
240:
241: /* We say something is dirty if it was */
242: /* written since the last time we */
243: /* retrieved dirty bits. We say it's */
244: /* grungy if it was marked dirty in the */
245: /* last set of bits we retrieved. */
246:
247: /* Invariant I: all roots and marked */
248: /* objects p are either dirty, or point */
249: /* to objects q that are either marked */
250: /* or a pointer to q appears in a range */
251: /* on the mark stack. */
252:
253: # define MS_NONE 0 /* No marking in progress. I holds. */
254: /* Mark stack is empty. */
255:
256: # define MS_PUSH_RESCUERS 1 /* Rescuing objects are currently */
257: /* being pushed. I holds, except */
258: /* that grungy roots may point to */
259: /* unmarked objects, as may marked */
260: /* grungy objects above scan_ptr. */
261:
262: # define MS_PUSH_UNCOLLECTABLE 2
263: /* I holds, except that marked */
264: /* uncollectable objects above scan_ptr */
265: /* may point to unmarked objects. */
266: /* Roots may point to unmarked objects */
267:
268: # define MS_ROOTS_PUSHED 3 /* I holds, mark stack may be nonempty */
269:
270: # define MS_PARTIALLY_INVALID 4 /* I may not hold, e.g. because of M.S. */
271: /* overflow. However marked heap */
272: /* objects below scan_ptr point to */
273: /* marked or stacked objects. */
274:
275: # define MS_INVALID 5 /* I may not hold. */
276:
277: extern mark_state_t GC_mark_state;
278:
279: #endif /* GC_MARK_H */
280:
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