3 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
4 * Copyright (c) 1991-1995 by Xerox Corporation. All rights reserved.
6 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
7 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
9 * Permission is hereby granted to use or copy this program
10 * for any purpose, provided the above notices are retained on all copies.
11 * Permission to modify the code and to distribute modified code is granted,
12 * provided the above notices are retained, and a notice that the code was
13 * modified is included with the above copyright notice.
22 /* We put this here to minimize the risk of inlining. */
25 void GC_noop(void *p, ...) {}
30 /* Single argument version, robust against whole program analysis. */
34 static VOLATILE word sink;
39 /* mark_proc GC_mark_procs[MAX_MARK_PROCS] = {0} -- declared in gc_priv.h */
41 word GC_n_mark_procs = GC_RESERVED_MARK_PROCS;
43 /* Initialize GC_obj_kinds properly and standard free lists properly. */
44 /* This must be done statically since they may be accessed before */
45 /* GC_init is called. */
46 /* It's done here, since we need to deal with mark descriptors. */
47 struct obj_kind GC_obj_kinds[MAXOBJKINDS] = {
48 /* PTRFREE */ { &GC_aobjfreelist[0], 0 /* filled in dynamically */,
49 0 | DS_LENGTH, FALSE, FALSE },
50 /* NORMAL */ { &GC_objfreelist[0], 0,
51 # if defined(ADD_BYTE_AT_END) && ALIGNMENT > DS_TAGS
52 (word)(-ALIGNMENT) | DS_LENGTH,
56 TRUE /* add length to descr */, TRUE },
58 { &GC_uobjfreelist[0], 0,
59 0 | DS_LENGTH, TRUE /* add length to descr */, TRUE },
60 # ifdef ATOMIC_UNCOLLECTABLE
62 { &GC_auobjfreelist[0], 0,
63 0 | DS_LENGTH, FALSE /* add length to descr */, FALSE },
65 # ifdef STUBBORN_ALLOC
66 /*STUBBORN*/ { &GC_sobjfreelist[0], 0,
67 0 | DS_LENGTH, TRUE /* add length to descr */, TRUE },
71 # ifdef ATOMIC_UNCOLLECTABLE
72 # ifdef STUBBORN_ALLOC
78 # ifdef STUBBORN_ALLOC
86 # ifndef INITIAL_MARK_STACK_SIZE
87 # define INITIAL_MARK_STACK_SIZE (1*HBLKSIZE)
88 /* INITIAL_MARK_STACK_SIZE * sizeof(mse) should be a */
89 /* multiple of HBLKSIZE. */
90 /* The incremental collector actually likes a larger */
91 /* size, since it want to push all marked dirty objs */
92 /* before marking anything new. Currently we let it */
93 /* grow dynamically. */
97 * Limits of stack for GC_mark routine.
98 * All ranges between GC_mark_stack(incl.) and GC_mark_stack_top(incl.) still
99 * need to be marked from.
102 word GC_n_rescuing_pages; /* Number of dirty pages we marked from */
103 /* excludes ptrfree pages, etc. */
107 word GC_mark_stack_size = 0;
109 mse * GC_mark_stack_top;
111 static struct hblk * scan_ptr;
113 mark_state_t GC_mark_state = MS_NONE;
115 GC_bool GC_mark_stack_too_small = FALSE;
117 GC_bool GC_objects_are_marked = FALSE; /* Are there collectable marked */
118 /* objects in the heap? */
120 /* Is a collection in progress? Note that this can return true in the */
121 /* nonincremental case, if a collection has been abandoned and the */
122 /* mark state is now MS_INVALID. */
123 GC_bool GC_collection_in_progress()
125 return(GC_mark_state != MS_NONE);
128 /* clear all mark bits in the header */
129 void GC_clear_hdr_marks(hhdr)
132 BZERO(hhdr -> hb_marks, MARK_BITS_SZ*sizeof(word));
135 /* Set all mark bits in the header. Used for uncollectable blocks. */
136 void GC_set_hdr_marks(hhdr)
141 for (i = 0; i < MARK_BITS_SZ; ++i) {
142 hhdr -> hb_marks[i] = ONES;
147 * Clear all mark bits associated with block h.
150 static void clear_marks_for_block(h, dummy)
154 register hdr * hhdr = HDR(h);
156 if (IS_UNCOLLECTABLE(hhdr -> hb_obj_kind)) return;
157 /* Mark bit for these is cleared only once the object is */
158 /* explicitly deallocated. This either frees the block, or */
159 /* the bit is cleared once the object is on the free list. */
160 GC_clear_hdr_marks(hhdr);
163 /* Slow but general routines for setting/clearing/asking about mark bits */
164 void GC_set_mark_bit(p)
167 register struct hblk *h = HBLKPTR(p);
168 register hdr * hhdr = HDR(h);
169 register int word_no = (word *)p - (word *)h;
171 set_mark_bit_from_hdr(hhdr, word_no);
174 void GC_clear_mark_bit(p)
177 register struct hblk *h = HBLKPTR(p);
178 register hdr * hhdr = HDR(h);
179 register int word_no = (word *)p - (word *)h;
181 clear_mark_bit_from_hdr(hhdr, word_no);
184 GC_bool GC_is_marked(p)
187 register struct hblk *h = HBLKPTR(p);
188 register hdr * hhdr = HDR(h);
189 register int word_no = (word *)p - (word *)h;
191 return(mark_bit_from_hdr(hhdr, word_no));
196 * Clear mark bits in all allocated heap blocks. This invalidates
197 * the marker invariant, and sets GC_mark_state to reflect this.
198 * (This implicitly starts marking to reestablish the invariant.)
200 void GC_clear_marks()
202 GC_apply_to_all_blocks(clear_marks_for_block, (word)0);
203 GC_objects_are_marked = FALSE;
204 GC_mark_state = MS_INVALID;
207 /* Counters reflect currently marked objects: reset here */
208 GC_composite_in_use = 0;
209 GC_atomic_in_use = 0;
214 /* Initiate a garbage collection. Initiates a full collection if the */
215 /* mark state is invalid. */
217 void GC_initiate_gc()
219 if (GC_dirty_maintained) GC_read_dirty();
220 # ifdef STUBBORN_ALLOC
225 extern void GC_check_dirty();
227 if (GC_dirty_maintained) GC_check_dirty();
231 GC_n_rescuing_pages = 0;
233 if (GC_mark_state == MS_NONE) {
234 GC_mark_state = MS_PUSH_RESCUERS;
235 } else if (GC_mark_state != MS_INVALID) {
236 ABORT("unexpected state");
237 } /* else this is really a full collection, and mark */
238 /* bits are invalid. */
243 static void alloc_mark_stack();
245 /* Perform a small amount of marking. */
246 /* We try to touch roughly a page of memory. */
247 /* Return TRUE if we just finished a mark phase. */
248 /* Cold_gc_frame is an address inside a GC frame that */
249 /* remains valid until all marking is complete. */
250 /* A zero value indicates that it's OK to miss some */
251 /* register values. */
252 GC_bool GC_mark_some(cold_gc_frame)
256 /* Windows 98 appears to asynchronously create and remove writable */
257 /* memory mappings, for reasons we haven't yet understood. Since */
258 /* we look for writable regions to determine the root set, we may */
259 /* try to mark from an address range that disappeared since we */
260 /* started the collection. Thus we have to recover from faults here. */
261 /* This code does not appear to be necessary for Windows 95/NT/2000. */
262 /* Note that this code should never generate an incremental GC write */
266 switch(GC_mark_state) {
270 case MS_PUSH_RESCUERS:
271 if (GC_mark_stack_top
272 >= GC_mark_stack + GC_mark_stack_size
273 - INITIAL_MARK_STACK_SIZE/2) {
274 /* Go ahead and mark, even though that might cause us to */
275 /* see more marked dirty objects later on. Avoid this */
277 GC_mark_stack_too_small = TRUE;
278 GC_mark_from_mark_stack();
281 scan_ptr = GC_push_next_marked_dirty(scan_ptr);
284 GC_printf1("Marked from %lu dirty pages\n",
285 (unsigned long)GC_n_rescuing_pages);
287 GC_push_roots(FALSE, cold_gc_frame);
288 GC_objects_are_marked = TRUE;
289 if (GC_mark_state != MS_INVALID) {
290 GC_mark_state = MS_ROOTS_PUSHED;
296 case MS_PUSH_UNCOLLECTABLE:
297 if (GC_mark_stack_top
298 >= GC_mark_stack + INITIAL_MARK_STACK_SIZE/4) {
299 GC_mark_from_mark_stack();
302 scan_ptr = GC_push_next_marked_uncollectable(scan_ptr);
304 GC_push_roots(TRUE, cold_gc_frame);
305 GC_objects_are_marked = TRUE;
306 if (GC_mark_state != MS_INVALID) {
307 GC_mark_state = MS_ROOTS_PUSHED;
313 case MS_ROOTS_PUSHED:
314 if (GC_mark_stack_top >= GC_mark_stack) {
315 GC_mark_from_mark_stack();
318 GC_mark_state = MS_NONE;
319 if (GC_mark_stack_too_small) {
320 alloc_mark_stack(2*GC_mark_stack_size);
326 case MS_PARTIALLY_INVALID:
327 if (!GC_objects_are_marked) {
328 GC_mark_state = MS_PUSH_UNCOLLECTABLE;
331 if (GC_mark_stack_top >= GC_mark_stack) {
332 GC_mark_from_mark_stack();
335 if (scan_ptr == 0 && GC_mark_state == MS_INVALID) {
336 /* About to start a heap scan for marked objects. */
337 /* Mark stack is empty. OK to reallocate. */
338 if (GC_mark_stack_too_small) {
339 alloc_mark_stack(2*GC_mark_stack_size);
341 GC_mark_state = MS_PARTIALLY_INVALID;
343 scan_ptr = GC_push_next_marked(scan_ptr);
344 if (scan_ptr == 0 && GC_mark_state == MS_PARTIALLY_INVALID) {
345 GC_push_roots(TRUE, cold_gc_frame);
346 GC_objects_are_marked = TRUE;
347 if (GC_mark_state != MS_INVALID) {
348 GC_mark_state = MS_ROOTS_PUSHED;
353 ABORT("GC_mark_some: bad state");
357 } __except (GetExceptionCode() == EXCEPTION_ACCESS_VIOLATION ?
358 EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH) {
360 GC_printf0("Caught ACCESS_VIOLATION in marker. "
361 "Memory mapping disappeared.\n");
362 # endif /* PRINTSTATS */
363 /* We have bad roots on the stack. Discard mark stack. */
364 /* Rescan from marked objects. Redetermine roots. */
365 GC_invalidate_mark_state();
373 GC_bool GC_mark_stack_empty()
375 return(GC_mark_stack_top < GC_mark_stack);
379 word GC_prof_array[10];
380 # define PROF(n) GC_prof_array[n]++
385 /* Given a pointer to someplace other than a small object page or the */
386 /* first page of a large object, return a pointer either to the */
387 /* start of the large object or NIL. */
388 /* In the latter case black list the address current. */
389 /* Returns NIL without black listing if current points to a block */
390 /* with IGNORE_OFF_PAGE set. */
392 # ifdef PRINT_BLACK_LIST
393 ptr_t GC_find_start(current, hhdr, source)
396 ptr_t GC_find_start(current, hhdr)
399 register ptr_t current;
402 # ifdef ALL_INTERIOR_POINTERS
404 register ptr_t orig = current;
406 current = (ptr_t)HBLKPTR(current) + HDR_BYTES;
408 current = current - HBLKSIZE*(word)hhdr;
410 } while(IS_FORWARDING_ADDR_OR_NIL(hhdr));
411 /* current points to the start of the large object */
412 if (hhdr -> hb_flags & IGNORE_OFF_PAGE) return(0);
413 if ((word *)orig - (word *)current
414 >= (ptrdiff_t)(hhdr->hb_sz)) {
415 /* Pointer past the end of the block */
416 GC_ADD_TO_BLACK_LIST_NORMAL(orig, source);
421 GC_ADD_TO_BLACK_LIST_NORMAL(current, source);
425 GC_ADD_TO_BLACK_LIST_NORMAL(current, source);
431 void GC_invalidate_mark_state()
433 GC_mark_state = MS_INVALID;
434 GC_mark_stack_top = GC_mark_stack-1;
437 mse * GC_signal_mark_stack_overflow(msp)
440 GC_mark_state = MS_INVALID;
441 GC_mark_stack_too_small = TRUE;
443 GC_printf1("Mark stack overflow; current size = %lu entries\n",
446 return(msp-INITIAL_MARK_STACK_SIZE/8);
451 * Mark objects pointed to by the regions described by
452 * mark stack entries between GC_mark_stack and GC_mark_stack_top,
453 * inclusive. Assumes the upper limit of a mark stack entry
454 * is never 0. A mark stack entry never has size 0.
455 * We try to traverse on the order of a hblk of memory before we return.
456 * Caller is responsible for calling this until the mark stack is empty.
457 * Note that this is the most performance critical routine in the
458 * collector. Hence it contains all sorts of ugly hacks to speed
459 * things up. In particular, we avoid procedure calls on the common
460 * path, we take advantage of peculiarities of the mark descriptor
461 * encoding, we optionally maintain a cache for the block address to
462 * header mapping, we prefetch when an object is "grayed", etc.
464 void GC_mark_from_mark_stack()
466 mse * GC_mark_stack_reg = GC_mark_stack;
467 mse * GC_mark_stack_top_reg = GC_mark_stack_top;
468 mse * mark_stack_limit = &(GC_mark_stack[GC_mark_stack_size]);
469 int credit = HBLKSIZE; /* Remaining credit for marking work */
470 register word * current_p; /* Pointer to current candidate ptr. */
471 register word current; /* Candidate pointer. */
472 register word * limit; /* (Incl) limit of current candidate */
475 register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
476 register ptr_t least_ha = GC_least_plausible_heap_addr;
479 # define SPLIT_RANGE_WORDS 128 /* Must be power of 2. */
481 GC_objects_are_marked = TRUE;
483 # ifdef OS2 /* Use untweaked version to circumvent compiler problem */
484 while (GC_mark_stack_top_reg >= GC_mark_stack_reg && credit >= 0) {
486 while ((((ptr_t)GC_mark_stack_top_reg - (ptr_t)GC_mark_stack_reg) | credit)
489 current_p = GC_mark_stack_top_reg -> mse_start;
490 descr = GC_mark_stack_top_reg -> mse_descr;
492 /* current_p and descr describe the current object. */
493 /* *GC_mark_stack_top_reg is vacant. */
494 /* The following is 0 only for small objects described by a simple */
495 /* length descriptor. For many applications this is the common */
496 /* case, so we try to detect it quickly. */
497 if (descr & ((~(WORDS_TO_BYTES(SPLIT_RANGE_WORDS) - 1)) | DS_TAGS)) {
498 word tag = descr & DS_TAGS;
503 /* Process part of the range to avoid pushing too much on the */
505 GC_mark_stack_top_reg -> mse_start =
506 limit = current_p + SPLIT_RANGE_WORDS-1;
507 GC_mark_stack_top_reg -> mse_descr =
508 descr - WORDS_TO_BYTES(SPLIT_RANGE_WORDS-1);
509 /* Make sure that pointers overlapping the two ranges are */
511 limit = (word *)((char *)limit + sizeof(word) - ALIGNMENT);
514 GC_mark_stack_top_reg--;
516 credit -= WORDS_TO_BYTES(WORDSZ/2); /* guess */
518 if ((signed_word)descr < 0) {
519 current = *current_p;
520 if ((ptr_t)current >= least_ha && (ptr_t)current < greatest_ha) {
522 HC_PUSH_CONTENTS((ptr_t)current, GC_mark_stack_top_reg,
523 mark_stack_limit, current_p, exit1);
531 GC_mark_stack_top_reg--;
532 credit -= PROC_BYTES;
533 GC_mark_stack_top_reg =
535 (current_p, GC_mark_stack_top_reg,
536 mark_stack_limit, ENV(descr));
539 if ((signed_word)descr >= 0) {
540 /* Descriptor is in the object. */
541 descr = *(word *)((ptr_t)current_p + descr - DS_PER_OBJECT);
543 /* Descriptor is in type descriptor pointed to by first */
544 /* word in object. */
545 ptr_t type_descr = *(ptr_t *)current_p;
546 /* type_descr is either a valid pointer to the descriptor */
547 /* structure, or this object was on a free list. If it */
548 /* it was anything but the last object on the free list, */
549 /* we will misinterpret the next object on the free list as */
550 /* the type descriptor, and get a 0 GC descriptor, which */
551 /* is ideal. Unfortunately, we need to check for the last */
552 /* object case explicitly. */
553 if (0 == type_descr) {
554 /* Rarely executed. */
555 GC_mark_stack_top_reg--;
558 descr = *(word *)(type_descr
559 - (descr - (DS_PER_OBJECT - INDIR_PER_OBJ_BIAS)));
563 } else /* Small object with length descriptor */ {
564 GC_mark_stack_top_reg--;
565 limit = (word *)(((ptr_t)current_p) + (word)descr);
567 /* The simple case in which we're scanning a range. */
568 credit -= (ptr_t)limit - (ptr_t)current_p;
573 # ifndef SMALL_CONFIG
576 /* Try to prefetch the next pointer to be examined asap. */
577 /* Empirically, this also seems to help slightly without */
578 /* prefetches, at least on linux/X86. Presumably this loop */
579 /* ends up with less register pressure, and gcc thus ends up */
580 /* generating slightly better code. Overall gcc code quality */
581 /* for this loop is still not great. */
583 PREFETCH((ptr_t)limit - PREF_DIST*CACHE_LINE_SIZE);
585 limit = (word *)((char *)limit - ALIGNMENT);
586 if ((ptr_t)deferred >= least_ha && (ptr_t)deferred < greatest_ha) {
590 if (current_p > limit) goto next_object;
591 /* Unroll once, so we don't do too many of the prefetches */
592 /* based on limit. */
594 limit = (word *)((char *)limit - ALIGNMENT);
595 if ((ptr_t)deferred >= least_ha && (ptr_t)deferred < greatest_ha) {
599 if (current_p > limit) goto next_object;
603 while (current_p <= limit) {
604 /* Empirically, unrolling this loop doesn't help a lot. */
605 /* Since HC_PUSH_CONTENTS expands to a lot of code, */
607 current = *current_p;
608 PREFETCH((ptr_t)current_p + PREF_DIST*CACHE_LINE_SIZE);
609 if ((ptr_t)current >= least_ha && (ptr_t)current < greatest_ha) {
610 /* Prefetch the contents of the object we just pushed. It's */
611 /* likely we will need them soon. */
613 HC_PUSH_CONTENTS((ptr_t)current, GC_mark_stack_top_reg,
614 mark_stack_limit, current_p, exit2);
616 current_p = (word *)((char *)current_p + ALIGNMENT);
619 # ifndef SMALL_CONFIG
620 /* We still need to mark the entry we previously prefetched. */
621 /* We alrady know that it passes the preliminary pointer */
623 HC_PUSH_CONTENTS((ptr_t)deferred, GC_mark_stack_top_reg,
624 mark_stack_limit, current_p, exit4);
629 GC_mark_stack_top = GC_mark_stack_top_reg;
632 /* Allocate or reallocate space for mark stack of size s words */
633 /* May silently fail. */
634 static void alloc_mark_stack(n)
637 mse * new_stack = (mse *)GC_scratch_alloc(n * sizeof(struct ms_entry));
639 GC_mark_stack_too_small = FALSE;
640 if (GC_mark_stack_size != 0) {
641 if (new_stack != 0) {
642 word displ = (word)GC_mark_stack & (GC_page_size - 1);
643 signed_word size = GC_mark_stack_size * sizeof(struct ms_entry);
645 /* Recycle old space */
646 if (0 != displ) displ = GC_page_size - displ;
647 size = (size - displ) & ~(GC_page_size - 1);
649 GC_add_to_heap((struct hblk *)
650 ((word)GC_mark_stack + displ), (word)size);
652 GC_mark_stack = new_stack;
653 GC_mark_stack_size = n;
655 GC_printf1("Grew mark stack to %lu frames\n",
656 (unsigned long) GC_mark_stack_size);
660 GC_printf1("Failed to grow mark stack to %lu frames\n",
665 if (new_stack == 0) {
666 GC_err_printf0("No space for mark stack\n");
669 GC_mark_stack = new_stack;
670 GC_mark_stack_size = n;
672 GC_mark_stack_top = GC_mark_stack-1;
677 alloc_mark_stack(INITIAL_MARK_STACK_SIZE);
681 * Push all locations between b and t onto the mark stack.
682 * b is the first location to be checked. t is one past the last
683 * location to be checked.
684 * Should only be used if there is no possibility of mark stack
687 void GC_push_all(bottom, top)
691 register word length;
693 bottom = (ptr_t)(((word) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
694 top = (ptr_t)(((word) top) & ~(ALIGNMENT-1));
695 if (top == 0 || bottom == top) return;
697 if (GC_mark_stack_top >= GC_mark_stack + GC_mark_stack_size) {
698 ABORT("unexpected mark stack overflow");
700 length = top - bottom;
701 # if DS_TAGS > ALIGNMENT - 1
705 GC_mark_stack_top -> mse_start = (word *)bottom;
706 GC_mark_stack_top -> mse_descr = length;
710 * Analogous to the above, but push only those pages that may have been
711 * dirtied. A block h is assumed dirty if dirty_fn(h) != 0.
712 * We use push_fn to actually push the block.
713 * Will not overflow mark stack if push_fn pushes a small fixed number
714 * of entries. (This is invoked only if push_fn pushes a single entry,
715 * or if it marks each object before pushing it, thus ensuring progress
716 * in the event of a stack overflow.)
718 void GC_push_dirty(bottom, top, dirty_fn, push_fn)
721 int (*dirty_fn)(/* struct hblk * h */);
722 void (*push_fn)(/* ptr_t bottom, ptr_t top */);
724 register struct hblk * h;
726 bottom = (ptr_t)(((long) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
727 top = (ptr_t)(((long) top) & ~(ALIGNMENT-1));
729 if (top == 0 || bottom == top) return;
730 h = HBLKPTR(bottom + HBLKSIZE);
731 if (top <= (ptr_t) h) {
732 if ((*dirty_fn)(h-1)) {
733 (*push_fn)(bottom, top);
737 if ((*dirty_fn)(h-1)) {
738 (*push_fn)(bottom, (ptr_t)h);
740 while ((ptr_t)(h+1) <= top) {
741 if ((*dirty_fn)(h)) {
742 if ((word)(GC_mark_stack_top - GC_mark_stack)
743 > 3 * GC_mark_stack_size / 4) {
744 /* Danger of mark stack overflow */
745 (*push_fn)((ptr_t)h, top);
748 (*push_fn)((ptr_t)h, (ptr_t)(h+1));
753 if ((ptr_t)h != top) {
754 if ((*dirty_fn)(h)) {
755 (*push_fn)((ptr_t)h, top);
758 if (GC_mark_stack_top >= GC_mark_stack + GC_mark_stack_size) {
759 ABORT("unexpected mark stack overflow");
763 # ifndef SMALL_CONFIG
764 void GC_push_conditional(bottom, top, all)
770 if (GC_dirty_maintained) {
772 /* Pages that were never dirtied cannot contain pointers */
773 GC_push_dirty(bottom, top, GC_page_was_ever_dirty, GC_push_all);
775 GC_push_all(bottom, top);
778 GC_push_all(bottom, top);
781 GC_push_dirty(bottom, top, GC_page_was_dirty, GC_push_all);
787 void __cdecl GC_push_one(p)
794 if (0 != GC_push_proc) {
799 GC_PUSH_ONE_STACK(p, MARKED_FROM_REGISTER);
803 # define BASE(p) (word)GC_base((void *)(p))
805 # define BASE(p) (word)GC_base((char *)(p))
808 /* As above, but argument passed preliminary test. */
809 # if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
810 void GC_push_one_checked(p, interior_ptrs, source)
813 void GC_push_one_checked(p, interior_ptrs)
817 register GC_bool interior_ptrs;
824 if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
825 if (hhdr != 0 && interior_ptrs) {
828 displ = BYTES_TO_WORDS(HBLKDISPL(r));
833 register map_entry_type map_entry;
835 displ = HBLKDISPL(p);
836 map_entry = MAP_ENTRY((hhdr -> hb_map), displ);
837 if (map_entry == OBJ_INVALID) {
838 # ifndef ALL_INTERIOR_POINTERS
841 displ = BYTES_TO_WORDS(HBLKDISPL(r));
842 if (r == 0) hhdr = 0;
847 /* map already reflects interior pointers */
851 displ = BYTES_TO_WORDS(displ);
853 r = (word)((word *)(HBLKPTR(p)) + displ);
856 /* If hhdr != 0 then r == GC_base(p), only we did it faster. */
857 /* displ is the word index within the block. */
860 # ifdef PRINT_BLACK_LIST
861 GC_add_to_black_list_stack(p, source);
863 GC_add_to_black_list_stack(p);
866 GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
867 # undef source /* In case we had to define it. */
870 if (!mark_bit_from_hdr(hhdr, displ)) {
871 set_mark_bit_from_hdr(hhdr, displ);
872 GC_STORE_BACK_PTR(source, (ptr_t)r);
873 PUSH_OBJ((word *)r, hhdr, GC_mark_stack_top,
874 &(GC_mark_stack[GC_mark_stack_size]));
881 # define TRACE_ENTRIES 1000
889 } GC_trace_buf[TRACE_ENTRIES];
891 int GC_trace_buf_ptr = 0;
893 void GC_add_trace_entry(char *kind, word arg1, word arg2)
895 GC_trace_buf[GC_trace_buf_ptr].kind = kind;
896 GC_trace_buf[GC_trace_buf_ptr].gc_no = GC_gc_no;
897 GC_trace_buf[GC_trace_buf_ptr].words_allocd = GC_words_allocd;
898 GC_trace_buf[GC_trace_buf_ptr].arg1 = arg1 ^ 0x80000000;
899 GC_trace_buf[GC_trace_buf_ptr].arg2 = arg2 ^ 0x80000000;
901 if (GC_trace_buf_ptr >= TRACE_ENTRIES) GC_trace_buf_ptr = 0;
904 void GC_print_trace(word gc_no, GC_bool lock)
907 struct trace_entry *p;
910 for (i = GC_trace_buf_ptr-1; i != GC_trace_buf_ptr; i--) {
911 if (i < 0) i = TRACE_ENTRIES-1;
912 p = GC_trace_buf + i;
913 if (p -> gc_no < gc_no || p -> kind == 0) return;
914 printf("Trace:%s (gc:%d,words:%d) 0x%X, 0x%X\n",
915 p -> kind, p -> gc_no, p -> words_allocd,
916 (p -> arg1) ^ 0x80000000, (p -> arg2) ^ 0x80000000);
918 printf("Trace incomplete\n");
922 # endif /* TRACE_BUF */
925 * A version of GC_push_all that treats all interior pointers as valid
926 * and scans the entire region immediately, in case the contents
929 void GC_push_all_eager(bottom, top)
933 word * b = (word *)(((long) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
934 word * t = (word *)(((long) top) & ~(ALIGNMENT-1));
938 register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
939 register ptr_t least_ha = GC_least_plausible_heap_addr;
940 # define GC_greatest_plausible_heap_addr greatest_ha
941 # define GC_least_plausible_heap_addr least_ha
943 if (top == 0) return;
944 /* check all pointers in range and put in push if they appear */
946 lim = t - 1 /* longword */;
947 for (p = b; p <= lim; p = (word *)(((char *)p) + ALIGNMENT)) {
949 GC_PUSH_ONE_STACK(q, p);
951 # undef GC_greatest_plausible_heap_addr
952 # undef GC_least_plausible_heap_addr
957 * A version of GC_push_all that treats all interior pointers as valid
958 * and scans part of the area immediately, to make sure that saved
959 * register values are not lost.
960 * Cold_gc_frame delimits the stack section that must be scanned
961 * eagerly. A zero value indicates that no eager scanning is needed.
963 void GC_push_all_stack_partially_eager(bottom, top, cold_gc_frame)
968 # ifdef ALL_INTERIOR_POINTERS
969 # define EAGER_BYTES 1024
970 /* Push the hot end of the stack eagerly, so that register values */
971 /* saved inside GC frames are marked before they disappear. */
972 /* The rest of the marking can be deferred until later. */
973 if (0 == cold_gc_frame) {
974 GC_push_all_stack(bottom, top);
977 # ifdef STACK_GROWS_DOWN
978 GC_push_all_eager(bottom, cold_gc_frame);
979 GC_push_all(cold_gc_frame - sizeof(ptr_t), top);
980 # else /* STACK_GROWS_UP */
981 GC_push_all_eager(cold_gc_frame, top);
982 GC_push_all(bottom, cold_gc_frame + sizeof(ptr_t));
983 # endif /* STACK_GROWS_UP */
985 GC_push_all_eager(bottom, top);
988 GC_add_trace_entry("GC_push_all_stack", bottom, top);
991 #endif /* !THREADS */
993 void GC_push_all_stack(bottom, top)
997 # ifdef ALL_INTERIOR_POINTERS
998 GC_push_all(bottom, top);
1000 GC_push_all_eager(bottom, top);
1004 #ifndef SMALL_CONFIG
1005 /* Push all objects reachable from marked objects in the given block */
1006 /* of size 1 objects. */
1007 void GC_push_marked1(h, hhdr)
1009 register hdr * hhdr;
1011 word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
1016 register word mark_word;
1017 register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
1018 register ptr_t least_ha = GC_least_plausible_heap_addr;
1019 # define GC_greatest_plausible_heap_addr greatest_ha
1020 # define GC_least_plausible_heap_addr least_ha
1022 p = (word *)(h->hb_body);
1023 plim = (word *)(((word)h) + HBLKSIZE);
1025 /* go through all words in block */
1027 mark_word = *mark_word_addr++;
1029 while(mark_word != 0) {
1030 if (mark_word & 1) {
1032 GC_PUSH_ONE_HEAP(q, p + i);
1039 # undef GC_greatest_plausible_heap_addr
1040 # undef GC_least_plausible_heap_addr
1046 /* Push all objects reachable from marked objects in the given block */
1047 /* of size 2 objects. */
1048 void GC_push_marked2(h, hhdr)
1050 register hdr * hhdr;
1052 word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
1057 register word mark_word;
1058 register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
1059 register ptr_t least_ha = GC_least_plausible_heap_addr;
1060 # define GC_greatest_plausible_heap_addr greatest_ha
1061 # define GC_least_plausible_heap_addr least_ha
1063 p = (word *)(h->hb_body);
1064 plim = (word *)(((word)h) + HBLKSIZE);
1066 /* go through all words in block */
1068 mark_word = *mark_word_addr++;
1070 while(mark_word != 0) {
1071 if (mark_word & 1) {
1073 GC_PUSH_ONE_HEAP(q, p + i);
1075 GC_PUSH_ONE_HEAP(q, p + i);
1082 # undef GC_greatest_plausible_heap_addr
1083 # undef GC_least_plausible_heap_addr
1086 /* Push all objects reachable from marked objects in the given block */
1087 /* of size 4 objects. */
1088 /* There is a risk of mark stack overflow here. But we handle that. */
1089 /* And only unmarked objects get pushed, so it's not very likely. */
1090 void GC_push_marked4(h, hhdr)
1092 register hdr * hhdr;
1094 word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
1099 register word mark_word;
1100 register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
1101 register ptr_t least_ha = GC_least_plausible_heap_addr;
1102 # define GC_greatest_plausible_heap_addr greatest_ha
1103 # define GC_least_plausible_heap_addr least_ha
1105 p = (word *)(h->hb_body);
1106 plim = (word *)(((word)h) + HBLKSIZE);
1108 /* go through all words in block */
1110 mark_word = *mark_word_addr++;
1112 while(mark_word != 0) {
1113 if (mark_word & 1) {
1115 GC_PUSH_ONE_HEAP(q, p + i);
1117 GC_PUSH_ONE_HEAP(q, p + i + 1);
1119 GC_PUSH_ONE_HEAP(q, p + i + 2);
1121 GC_PUSH_ONE_HEAP(q, p + i + 3);
1128 # undef GC_greatest_plausible_heap_addr
1129 # undef GC_least_plausible_heap_addr
1132 #endif /* UNALIGNED */
1134 #endif /* SMALL_CONFIG */
1136 /* Push all objects reachable from marked objects in the given block */
1137 void GC_push_marked(h, hhdr)
1139 register hdr * hhdr;
1141 register int sz = hhdr -> hb_sz;
1142 register int descr = hhdr -> hb_descr;
1144 register int word_no;
1145 register word * lim;
1146 register mse * GC_mark_stack_top_reg;
1147 register mse * mark_stack_limit = &(GC_mark_stack[GC_mark_stack_size]);
1149 /* Some quick shortcuts: */
1150 if ((0 | DS_LENGTH) == descr) return;
1151 if (GC_block_empty(hhdr)/* nothing marked */) return;
1153 GC_n_rescuing_pages++;
1155 GC_objects_are_marked = TRUE;
1156 if (sz > MAXOBJSZ) {
1157 lim = (word *)h + HDR_WORDS;
1159 lim = (word *)(h + 1) - sz;
1163 # if !defined(SMALL_CONFIG)
1165 GC_push_marked1(h, hhdr);
1168 # if !defined(SMALL_CONFIG) && !defined(UNALIGNED)
1170 GC_push_marked2(h, hhdr);
1173 GC_push_marked4(h, hhdr);
1177 GC_mark_stack_top_reg = GC_mark_stack_top;
1178 for (p = (word *)h + HDR_WORDS, word_no = HDR_WORDS; p <= lim;
1179 p += sz, word_no += sz) {
1180 if (mark_bit_from_hdr(hhdr, word_no)) {
1181 /* Mark from fields inside the object */
1182 PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top_reg, mark_stack_limit);
1184 /* Subtract this object from total, since it was */
1185 /* added in twice. */
1186 GC_composite_in_use -= sz;
1190 GC_mark_stack_top = GC_mark_stack_top_reg;
1194 #ifndef SMALL_CONFIG
1195 /* Test whether any page in the given block is dirty */
1196 GC_bool GC_block_was_dirty(h, hhdr)
1198 register hdr * hhdr;
1200 register int sz = hhdr -> hb_sz;
1202 if (sz < MAXOBJSZ) {
1203 return(GC_page_was_dirty(h));
1205 register ptr_t p = (ptr_t)h;
1207 sz = WORDS_TO_BYTES(sz);
1208 while (p < (ptr_t)h + sz) {
1209 if (GC_page_was_dirty((struct hblk *)p)) return(TRUE);
1215 #endif /* SMALL_CONFIG */
1217 /* Similar to GC_push_next_marked, but return address of next block */
1218 struct hblk * GC_push_next_marked(h)
1221 register hdr * hhdr;
1223 h = GC_next_used_block(h);
1224 if (h == 0) return(0);
1226 GC_push_marked(h, hhdr);
1227 return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
1230 #ifndef SMALL_CONFIG
1231 /* Identical to above, but mark only from dirty pages */
1232 struct hblk * GC_push_next_marked_dirty(h)
1235 register hdr * hhdr;
1237 if (!GC_dirty_maintained) { ABORT("dirty bits not set up"); }
1239 h = GC_next_used_block(h);
1240 if (h == 0) return(0);
1242 # ifdef STUBBORN_ALLOC
1243 if (hhdr -> hb_obj_kind == STUBBORN) {
1244 if (GC_page_was_changed(h) && GC_block_was_dirty(h, hhdr)) {
1248 if (GC_block_was_dirty(h, hhdr)) break;
1251 if (GC_block_was_dirty(h, hhdr)) break;
1253 h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
1255 GC_push_marked(h, hhdr);
1256 return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
1260 /* Similar to above, but for uncollectable pages. Needed since we */
1261 /* do not clear marks for such pages, even for full collections. */
1262 struct hblk * GC_push_next_marked_uncollectable(h)
1265 register hdr * hhdr = HDR(h);
1268 h = GC_next_used_block(h);
1269 if (h == 0) return(0);
1271 if (hhdr -> hb_obj_kind == UNCOLLECTABLE) break;
1272 h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
1274 GC_push_marked(h, hhdr);
1275 return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));