1 /* "Bag-of-pages" garbage collector for the GNU compiler.
2 Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008
3 Free Software Foundation, Inc.
5 This file is part of GCC.
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
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
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/>. */
23 #include "coretypes.h"
33 #include "tree-flow.h"
35 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
36 file open. Prefer either to valloc. */
38 # undef HAVE_MMAP_DEV_ZERO
40 # include <sys/mman.h>
42 # define MAP_FAILED -1
44 # if !defined (MAP_ANONYMOUS) && defined (MAP_ANON)
45 # define MAP_ANONYMOUS MAP_ANON
51 #ifdef HAVE_MMAP_DEV_ZERO
53 # include <sys/mman.h>
55 # define MAP_FAILED -1
62 #define USING_MALLOC_PAGE_GROUPS
67 This garbage-collecting allocator allocates objects on one of a set
68 of pages. Each page can allocate objects of a single size only;
69 available sizes are powers of two starting at four bytes. The size
70 of an allocation request is rounded up to the next power of two
71 (`order'), and satisfied from the appropriate page.
73 Each page is recorded in a page-entry, which also maintains an
74 in-use bitmap of object positions on the page. This allows the
75 allocation state of a particular object to be flipped without
76 touching the page itself.
78 Each page-entry also has a context depth, which is used to track
79 pushing and popping of allocation contexts. Only objects allocated
80 in the current (highest-numbered) context may be collected.
82 Page entries are arranged in an array of singly-linked lists. The
83 array is indexed by the allocation size, in bits, of the pages on
84 it; i.e. all pages on a list allocate objects of the same size.
85 Pages are ordered on the list such that all non-full pages precede
86 all full pages, with non-full pages arranged in order of decreasing
89 Empty pages (of all orders) are kept on a single page cache list,
90 and are considered first when new pages are required; they are
91 deallocated at the start of the next collection if they haven't
92 been recycled by then. */
94 /* Define GGC_DEBUG_LEVEL to print debugging information.
95 0: No debugging output.
96 1: GC statistics only.
97 2: Page-entry allocations/deallocations as well.
98 3: Object allocations as well.
99 4: Object marks as well. */
100 #define GGC_DEBUG_LEVEL (0)
102 #ifndef HOST_BITS_PER_PTR
103 #define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
107 /* A two-level tree is used to look up the page-entry for a given
108 pointer. Two chunks of the pointer's bits are extracted to index
109 the first and second levels of the tree, as follows:
113 msb +----------------+----+------+------+ lsb
119 The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
120 pages are aligned on system page boundaries. The next most
121 significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
122 index values in the lookup table, respectively.
124 For 32-bit architectures and the settings below, there are no
125 leftover bits. For architectures with wider pointers, the lookup
126 tree points to a list of pages, which must be scanned to find the
129 #define PAGE_L1_BITS (8)
130 #define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
131 #define PAGE_L1_SIZE ((size_t) 1 << PAGE_L1_BITS)
132 #define PAGE_L2_SIZE ((size_t) 1 << PAGE_L2_BITS)
134 #define LOOKUP_L1(p) \
135 (((size_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
137 #define LOOKUP_L2(p) \
138 (((size_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
140 /* The number of objects per allocation page, for objects on a page of
141 the indicated ORDER. */
142 #define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
144 /* The number of objects in P. */
145 #define OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
147 /* The size of an object on a page of the indicated ORDER. */
148 #define OBJECT_SIZE(ORDER) object_size_table[ORDER]
150 /* For speed, we avoid doing a general integer divide to locate the
151 offset in the allocation bitmap, by precalculating numbers M, S
152 such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
153 within the page which is evenly divisible by the object size Z. */
154 #define DIV_MULT(ORDER) inverse_table[ORDER].mult
155 #define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
156 #define OFFSET_TO_BIT(OFFSET, ORDER) \
157 (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
159 /* The number of extra orders, not corresponding to power-of-two sized
162 #define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
164 #define RTL_SIZE(NSLOTS) \
165 (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))
167 #define TREE_EXP_SIZE(OPS) \
168 (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
170 /* The Ith entry is the maximum size of an object to be stored in the
171 Ith extra order. Adding a new entry to this array is the *only*
172 thing you need to do to add a new special allocation size. */
174 static const size_t extra_order_size_table[] = {
175 sizeof (struct stmt_ann_d),
176 sizeof (struct var_ann_d),
177 sizeof (struct tree_decl_non_common),
178 sizeof (struct tree_field_decl),
179 sizeof (struct tree_parm_decl),
180 sizeof (struct tree_var_decl),
181 sizeof (struct tree_list),
182 sizeof (struct tree_ssa_name),
183 sizeof (struct function),
184 sizeof (struct basic_block_def),
185 sizeof (bitmap_element),
186 sizeof (bitmap_head),
187 /* PHI nodes with one to three arguments are already covered by the
189 sizeof (struct tree_phi_node) + sizeof (struct phi_arg_d) * 3,
191 RTL_SIZE (2), /* MEM, PLUS, etc. */
192 RTL_SIZE (9), /* INSN */
195 /* The total number of orders. */
197 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
199 /* We use this structure to determine the alignment required for
200 allocations. For power-of-two sized allocations, that's not a
201 problem, but it does matter for odd-sized allocations. */
203 struct max_alignment {
211 /* The biggest alignment required. */
213 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
215 /* Compute the smallest nonnegative number which when added to X gives
218 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
220 /* Compute the smallest multiple of F that is >= X. */
222 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
224 /* The Ith entry is the number of objects on a page or order I. */
226 static unsigned objects_per_page_table[NUM_ORDERS];
228 /* The Ith entry is the size of an object on a page of order I. */
230 static size_t object_size_table[NUM_ORDERS];
232 /* The Ith entry is a pair of numbers (mult, shift) such that
233 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
234 for all k evenly divisible by OBJECT_SIZE(I). */
241 inverse_table[NUM_ORDERS];
243 /* A page_entry records the status of an allocation page. This
244 structure is dynamically sized to fit the bitmap in_use_p. */
245 typedef struct page_entry
247 /* The next page-entry with objects of the same size, or NULL if
248 this is the last page-entry. */
249 struct page_entry *next;
251 /* The previous page-entry with objects of the same size, or NULL if
252 this is the first page-entry. The PREV pointer exists solely to
253 keep the cost of ggc_free manageable. */
254 struct page_entry *prev;
256 /* The number of bytes allocated. (This will always be a multiple
257 of the host system page size.) */
260 /* The address at which the memory is allocated. */
263 #ifdef USING_MALLOC_PAGE_GROUPS
264 /* Back pointer to the page group this page came from. */
265 struct page_group *group;
268 /* This is the index in the by_depth varray where this page table
270 unsigned long index_by_depth;
272 /* Context depth of this page. */
273 unsigned short context_depth;
275 /* The number of free objects remaining on this page. */
276 unsigned short num_free_objects;
278 /* A likely candidate for the bit position of a free object for the
279 next allocation from this page. */
280 unsigned short next_bit_hint;
282 /* The lg of size of objects allocated from this page. */
285 /* A bit vector indicating whether or not objects are in use. The
286 Nth bit is one if the Nth object on this page is allocated. This
287 array is dynamically sized. */
288 unsigned long in_use_p[1];
291 #ifdef USING_MALLOC_PAGE_GROUPS
292 /* A page_group describes a large allocation from malloc, from which
293 we parcel out aligned pages. */
294 typedef struct page_group
296 /* A linked list of all extant page groups. */
297 struct page_group *next;
299 /* The address we received from malloc. */
302 /* The size of the block. */
305 /* A bitmask of pages in use. */
310 #if HOST_BITS_PER_PTR <= 32
312 /* On 32-bit hosts, we use a two level page table, as pictured above. */
313 typedef page_entry **page_table[PAGE_L1_SIZE];
317 /* On 64-bit hosts, we use the same two level page tables plus a linked
318 list that disambiguates the top 32-bits. There will almost always be
319 exactly one entry in the list. */
320 typedef struct page_table_chain
322 struct page_table_chain *next;
324 page_entry **table[PAGE_L1_SIZE];
329 /* The rest of the global variables. */
330 static struct globals
332 /* The Nth element in this array is a page with objects of size 2^N.
333 If there are any pages with free objects, they will be at the
334 head of the list. NULL if there are no page-entries for this
336 page_entry *pages[NUM_ORDERS];
338 /* The Nth element in this array is the last page with objects of
339 size 2^N. NULL if there are no page-entries for this object
341 page_entry *page_tails[NUM_ORDERS];
343 /* Lookup table for associating allocation pages with object addresses. */
346 /* The system's page size. */
350 /* Bytes currently allocated. */
353 /* Bytes currently allocated at the end of the last collection. */
354 size_t allocated_last_gc;
356 /* Total amount of memory mapped. */
359 /* Bit N set if any allocations have been done at context depth N. */
360 unsigned long context_depth_allocations;
362 /* Bit N set if any collections have been done at context depth N. */
363 unsigned long context_depth_collections;
365 /* The current depth in the context stack. */
366 unsigned short context_depth;
368 /* A file descriptor open to /dev/zero for reading. */
369 #if defined (HAVE_MMAP_DEV_ZERO)
373 /* A cache of free system pages. */
374 page_entry *free_pages;
376 #ifdef USING_MALLOC_PAGE_GROUPS
377 page_group *page_groups;
380 /* The file descriptor for debugging output. */
383 /* Current number of elements in use in depth below. */
384 unsigned int depth_in_use;
386 /* Maximum number of elements that can be used before resizing. */
387 unsigned int depth_max;
389 /* Each element of this arry is an index in by_depth where the given
390 depth starts. This structure is indexed by that given depth we
391 are interested in. */
394 /* Current number of elements in use in by_depth below. */
395 unsigned int by_depth_in_use;
397 /* Maximum number of elements that can be used before resizing. */
398 unsigned int by_depth_max;
400 /* Each element of this array is a pointer to a page_entry, all
401 page_entries can be found in here by increasing depth.
402 index_by_depth in the page_entry is the index into this data
403 structure where that page_entry can be found. This is used to
404 speed up finding all page_entries at a particular depth. */
405 page_entry **by_depth;
407 /* Each element is a pointer to the saved in_use_p bits, if any,
408 zero otherwise. We allocate them all together, to enable a
409 better runtime data access pattern. */
410 unsigned long **save_in_use;
412 #ifdef ENABLE_GC_ALWAYS_COLLECT
413 /* List of free objects to be verified as actually free on the
418 struct free_object *next;
422 #ifdef GATHER_STATISTICS
425 /* Total memory allocated with ggc_alloc. */
426 unsigned long long total_allocated;
427 /* Total overhead for memory to be allocated with ggc_alloc. */
428 unsigned long long total_overhead;
430 /* Total allocations and overhead for sizes less than 32, 64 and 128.
431 These sizes are interesting because they are typical cache line
434 unsigned long long total_allocated_under32;
435 unsigned long long total_overhead_under32;
437 unsigned long long total_allocated_under64;
438 unsigned long long total_overhead_under64;
440 unsigned long long total_allocated_under128;
441 unsigned long long total_overhead_under128;
443 /* The allocations for each of the allocation orders. */
444 unsigned long long total_allocated_per_order[NUM_ORDERS];
446 /* The overhead for each of the allocation orders. */
447 unsigned long long total_overhead_per_order[NUM_ORDERS];
452 /* The size in bytes required to maintain a bitmap for the objects
454 #define BITMAP_SIZE(Num_objects) \
455 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
457 /* Allocate pages in chunks of this size, to throttle calls to memory
458 allocation routines. The first page is used, the rest go onto the
459 free list. This cannot be larger than HOST_BITS_PER_INT for the
460 in_use bitmask for page_group. Hosts that need a different value
461 can override this by defining GGC_QUIRE_SIZE explicitly. */
462 #ifndef GGC_QUIRE_SIZE
464 # define GGC_QUIRE_SIZE 256
466 # define GGC_QUIRE_SIZE 16
470 /* Initial guess as to how many page table entries we might need. */
471 #define INITIAL_PTE_COUNT 128
473 static int ggc_allocated_p (const void *);
474 static page_entry *lookup_page_table_entry (const void *);
475 static void set_page_table_entry (void *, page_entry *);
477 static char *alloc_anon (char *, size_t);
479 #ifdef USING_MALLOC_PAGE_GROUPS
480 static size_t page_group_index (char *, char *);
481 static void set_page_group_in_use (page_group *, char *);
482 static void clear_page_group_in_use (page_group *, char *);
484 static struct page_entry * alloc_page (unsigned);
485 static void free_page (struct page_entry *);
486 static void release_pages (void);
487 static void clear_marks (void);
488 static void sweep_pages (void);
489 static void ggc_recalculate_in_use_p (page_entry *);
490 static void compute_inverse (unsigned);
491 static inline void adjust_depth (void);
492 static void move_ptes_to_front (int, int);
494 void debug_print_page_list (int);
495 static void push_depth (unsigned int);
496 static void push_by_depth (page_entry *, unsigned long *);
498 /* Push an entry onto G.depth. */
501 push_depth (unsigned int i)
503 if (G.depth_in_use >= G.depth_max)
506 G.depth = xrealloc (G.depth, G.depth_max * sizeof (unsigned int));
508 G.depth[G.depth_in_use++] = i;
511 /* Push an entry onto G.by_depth and G.save_in_use. */
514 push_by_depth (page_entry *p, unsigned long *s)
516 if (G.by_depth_in_use >= G.by_depth_max)
519 G.by_depth = xrealloc (G.by_depth,
520 G.by_depth_max * sizeof (page_entry *));
521 G.save_in_use = xrealloc (G.save_in_use,
522 G.by_depth_max * sizeof (unsigned long *));
524 G.by_depth[G.by_depth_in_use] = p;
525 G.save_in_use[G.by_depth_in_use++] = s;
528 #if (GCC_VERSION < 3001)
529 #define prefetch(X) ((void) X)
531 #define prefetch(X) __builtin_prefetch (X)
534 #define save_in_use_p_i(__i) \
536 #define save_in_use_p(__p) \
537 (save_in_use_p_i (__p->index_by_depth))
539 /* Returns nonzero if P was allocated in GC'able memory. */
542 ggc_allocated_p (const void *p)
547 #if HOST_BITS_PER_PTR <= 32
550 page_table table = G.lookup;
551 size_t high_bits = (size_t) p & ~ (size_t) 0xffffffff;
556 if (table->high_bits == high_bits)
560 base = &table->table[0];
563 /* Extract the level 1 and 2 indices. */
567 return base[L1] && base[L1][L2];
570 /* Traverse the page table and find the entry for a page.
571 Die (probably) if the object wasn't allocated via GC. */
573 static inline page_entry *
574 lookup_page_table_entry (const void *p)
579 #if HOST_BITS_PER_PTR <= 32
582 page_table table = G.lookup;
583 size_t high_bits = (size_t) p & ~ (size_t) 0xffffffff;
584 while (table->high_bits != high_bits)
586 base = &table->table[0];
589 /* Extract the level 1 and 2 indices. */
596 /* Set the page table entry for a page. */
599 set_page_table_entry (void *p, page_entry *entry)
604 #if HOST_BITS_PER_PTR <= 32
608 size_t high_bits = (size_t) p & ~ (size_t) 0xffffffff;
609 for (table = G.lookup; table; table = table->next)
610 if (table->high_bits == high_bits)
613 /* Not found -- allocate a new table. */
614 table = xcalloc (1, sizeof(*table));
615 table->next = G.lookup;
616 table->high_bits = high_bits;
619 base = &table->table[0];
622 /* Extract the level 1 and 2 indices. */
626 if (base[L1] == NULL)
627 base[L1] = XCNEWVEC (page_entry *, PAGE_L2_SIZE);
629 base[L1][L2] = entry;
632 /* Prints the page-entry for object size ORDER, for debugging. */
635 debug_print_page_list (int order)
638 printf ("Head=%p, Tail=%p:\n", (void *) G.pages[order],
639 (void *) G.page_tails[order]);
643 printf ("%p(%1d|%3d) -> ", (void *) p, p->context_depth,
644 p->num_free_objects);
652 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
653 (if non-null). The ifdef structure here is intended to cause a
654 compile error unless exactly one of the HAVE_* is defined. */
657 alloc_anon (char *pref ATTRIBUTE_UNUSED, size_t size)
659 #ifdef HAVE_MMAP_ANON
660 char *page = mmap (pref, size, PROT_READ | PROT_WRITE,
661 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
663 #ifdef HAVE_MMAP_DEV_ZERO
664 char *page = mmap (pref, size, PROT_READ | PROT_WRITE,
665 MAP_PRIVATE, G.dev_zero_fd, 0);
668 if (page == (char *) MAP_FAILED)
670 perror ("virtual memory exhausted");
671 exit (FATAL_EXIT_CODE);
674 /* Remember that we allocated this memory. */
675 G.bytes_mapped += size;
677 /* Pretend we don't have access to the allocated pages. We'll enable
678 access to smaller pieces of the area in ggc_alloc. Discard the
679 handle to avoid handle leak. */
680 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (page, size));
685 #ifdef USING_MALLOC_PAGE_GROUPS
686 /* Compute the index for this page into the page group. */
689 page_group_index (char *allocation, char *page)
691 return (size_t) (page - allocation) >> G.lg_pagesize;
694 /* Set and clear the in_use bit for this page in the page group. */
697 set_page_group_in_use (page_group *group, char *page)
699 group->in_use |= 1 << page_group_index (group->allocation, page);
703 clear_page_group_in_use (page_group *group, char *page)
705 group->in_use &= ~(1 << page_group_index (group->allocation, page));
709 /* Allocate a new page for allocating objects of size 2^ORDER,
710 and return an entry for it. The entry is not added to the
711 appropriate page_table list. */
713 static inline struct page_entry *
714 alloc_page (unsigned order)
716 struct page_entry *entry, *p, **pp;
720 size_t page_entry_size;
722 #ifdef USING_MALLOC_PAGE_GROUPS
726 num_objects = OBJECTS_PER_PAGE (order);
727 bitmap_size = BITMAP_SIZE (num_objects + 1);
728 page_entry_size = sizeof (page_entry) - sizeof (long) + bitmap_size;
729 entry_size = num_objects * OBJECT_SIZE (order);
730 if (entry_size < G.pagesize)
731 entry_size = G.pagesize;
736 /* Check the list of free pages for one we can use. */
737 for (pp = &G.free_pages, p = *pp; p; pp = &p->next, p = *pp)
738 if (p->bytes == entry_size)
743 /* Recycle the allocated memory from this page ... */
747 #ifdef USING_MALLOC_PAGE_GROUPS
751 /* ... and, if possible, the page entry itself. */
752 if (p->order == order)
755 memset (entry, 0, page_entry_size);
761 else if (entry_size == G.pagesize)
763 /* We want just one page. Allocate a bunch of them and put the
764 extras on the freelist. (Can only do this optimization with
765 mmap for backing store.) */
766 struct page_entry *e, *f = G.free_pages;
769 page = alloc_anon (NULL, G.pagesize * GGC_QUIRE_SIZE);
771 /* This loop counts down so that the chain will be in ascending
773 for (i = GGC_QUIRE_SIZE - 1; i >= 1; i--)
775 e = xcalloc (1, page_entry_size);
777 e->bytes = G.pagesize;
778 e->page = page + (i << G.lg_pagesize);
786 page = alloc_anon (NULL, entry_size);
788 #ifdef USING_MALLOC_PAGE_GROUPS
791 /* Allocate a large block of memory and serve out the aligned
792 pages therein. This results in much less memory wastage
793 than the traditional implementation of valloc. */
795 char *allocation, *a, *enda;
796 size_t alloc_size, head_slop, tail_slop;
797 int multiple_pages = (entry_size == G.pagesize);
800 alloc_size = GGC_QUIRE_SIZE * G.pagesize;
802 alloc_size = entry_size + G.pagesize - 1;
803 allocation = xmalloc (alloc_size);
805 page = (char *) (((size_t) allocation + G.pagesize - 1) & -G.pagesize);
806 head_slop = page - allocation;
808 tail_slop = ((size_t) allocation + alloc_size) & (G.pagesize - 1);
810 tail_slop = alloc_size - entry_size - head_slop;
811 enda = allocation + alloc_size - tail_slop;
813 /* We allocated N pages, which are likely not aligned, leaving
814 us with N-1 usable pages. We plan to place the page_group
815 structure somewhere in the slop. */
816 if (head_slop >= sizeof (page_group))
817 group = (page_group *)page - 1;
820 /* We magically got an aligned allocation. Too bad, we have
821 to waste a page anyway. */
825 tail_slop += G.pagesize;
827 gcc_assert (tail_slop >= sizeof (page_group));
828 group = (page_group *)enda;
829 tail_slop -= sizeof (page_group);
832 /* Remember that we allocated this memory. */
833 group->next = G.page_groups;
834 group->allocation = allocation;
835 group->alloc_size = alloc_size;
837 G.page_groups = group;
838 G.bytes_mapped += alloc_size;
840 /* If we allocated multiple pages, put the rest on the free list. */
843 struct page_entry *e, *f = G.free_pages;
844 for (a = enda - G.pagesize; a != page; a -= G.pagesize)
846 e = xcalloc (1, page_entry_size);
848 e->bytes = G.pagesize;
860 entry = xcalloc (1, page_entry_size);
862 entry->bytes = entry_size;
864 entry->context_depth = G.context_depth;
865 entry->order = order;
866 entry->num_free_objects = num_objects;
867 entry->next_bit_hint = 1;
869 G.context_depth_allocations |= (unsigned long)1 << G.context_depth;
871 #ifdef USING_MALLOC_PAGE_GROUPS
872 entry->group = group;
873 set_page_group_in_use (group, page);
876 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
877 increment the hint. */
878 entry->in_use_p[num_objects / HOST_BITS_PER_LONG]
879 = (unsigned long) 1 << (num_objects % HOST_BITS_PER_LONG);
881 set_page_table_entry (page, entry);
883 if (GGC_DEBUG_LEVEL >= 2)
884 fprintf (G.debug_file,
885 "Allocating page at %p, object size=%lu, data %p-%p\n",
886 (void *) entry, (unsigned long) OBJECT_SIZE (order), page,
887 page + entry_size - 1);
892 /* Adjust the size of G.depth so that no index greater than the one
893 used by the top of the G.by_depth is used. */
900 if (G.by_depth_in_use)
902 top = G.by_depth[G.by_depth_in_use-1];
904 /* Peel back indices in depth that index into by_depth, so that
905 as new elements are added to by_depth, we note the indices
906 of those elements, if they are for new context depths. */
907 while (G.depth_in_use > (size_t)top->context_depth+1)
912 /* For a page that is no longer needed, put it on the free page list. */
915 free_page (page_entry *entry)
917 if (GGC_DEBUG_LEVEL >= 2)
918 fprintf (G.debug_file,
919 "Deallocating page at %p, data %p-%p\n", (void *) entry,
920 entry->page, entry->page + entry->bytes - 1);
922 /* Mark the page as inaccessible. Discard the handle to avoid handle
924 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (entry->page, entry->bytes));
926 set_page_table_entry (entry->page, NULL);
928 #ifdef USING_MALLOC_PAGE_GROUPS
929 clear_page_group_in_use (entry->group, entry->page);
932 if (G.by_depth_in_use > 1)
934 page_entry *top = G.by_depth[G.by_depth_in_use-1];
935 int i = entry->index_by_depth;
937 /* We cannot free a page from a context deeper than the current
939 gcc_assert (entry->context_depth == top->context_depth);
941 /* Put top element into freed slot. */
943 G.save_in_use[i] = G.save_in_use[G.by_depth_in_use-1];
944 top->index_by_depth = i;
950 entry->next = G.free_pages;
951 G.free_pages = entry;
954 /* Release the free page cache to the system. */
960 page_entry *p, *next;
964 /* Gather up adjacent pages so they are unmapped together. */
975 while (p && p->page == start + len)
984 G.bytes_mapped -= len;
989 #ifdef USING_MALLOC_PAGE_GROUPS
993 /* Remove all pages from free page groups from the list. */
995 while ((p = *pp) != NULL)
996 if (p->group->in_use == 0)
1004 /* Remove all free page groups, and release the storage. */
1005 gp = &G.page_groups;
1006 while ((g = *gp) != NULL)
1010 G.bytes_mapped -= g->alloc_size;
1011 free (g->allocation);
1018 /* This table provides a fast way to determine ceil(log_2(size)) for
1019 allocation requests. The minimum allocation size is eight bytes. */
1020 #define NUM_SIZE_LOOKUP 512
1021 static unsigned char size_lookup[NUM_SIZE_LOOKUP] =
1023 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
1024 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1025 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1026 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1027 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1028 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1029 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1030 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1031 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1032 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1033 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1034 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1035 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1036 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1037 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1038 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1039 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1040 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1041 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1042 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1043 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1044 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1045 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1046 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1047 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1048 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1049 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1050 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1051 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1052 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1053 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1054 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
1057 /* Typed allocation function. Does nothing special in this collector. */
1060 ggc_alloc_typed_stat (enum gt_types_enum type ATTRIBUTE_UNUSED, size_t size
1063 return ggc_alloc_stat (size PASS_MEM_STAT);
1066 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1069 ggc_alloc_stat (size_t size MEM_STAT_DECL)
1071 size_t order, word, bit, object_offset, object_size;
1072 struct page_entry *entry;
1075 if (size < NUM_SIZE_LOOKUP)
1077 order = size_lookup[size];
1078 object_size = OBJECT_SIZE (order);
1083 while (size > (object_size = OBJECT_SIZE (order)))
1087 /* If there are non-full pages for this size allocation, they are at
1088 the head of the list. */
1089 entry = G.pages[order];
1091 /* If there is no page for this object size, or all pages in this
1092 context are full, allocate a new page. */
1093 if (entry == NULL || entry->num_free_objects == 0)
1095 struct page_entry *new_entry;
1096 new_entry = alloc_page (order);
1098 new_entry->index_by_depth = G.by_depth_in_use;
1099 push_by_depth (new_entry, 0);
1101 /* We can skip context depths, if we do, make sure we go all the
1102 way to the new depth. */
1103 while (new_entry->context_depth >= G.depth_in_use)
1104 push_depth (G.by_depth_in_use-1);
1106 /* If this is the only entry, it's also the tail. If it is not
1107 the only entry, then we must update the PREV pointer of the
1108 ENTRY (G.pages[order]) to point to our new page entry. */
1110 G.page_tails[order] = new_entry;
1112 entry->prev = new_entry;
1114 /* Put new pages at the head of the page list. By definition the
1115 entry at the head of the list always has a NULL pointer. */
1116 new_entry->next = entry;
1117 new_entry->prev = NULL;
1119 G.pages[order] = new_entry;
1121 /* For a new page, we know the word and bit positions (in the
1122 in_use bitmap) of the first available object -- they're zero. */
1123 new_entry->next_bit_hint = 1;
1130 /* First try to use the hint left from the previous allocation
1131 to locate a clear bit in the in-use bitmap. We've made sure
1132 that the one-past-the-end bit is always set, so if the hint
1133 has run over, this test will fail. */
1134 unsigned hint = entry->next_bit_hint;
1135 word = hint / HOST_BITS_PER_LONG;
1136 bit = hint % HOST_BITS_PER_LONG;
1138 /* If the hint didn't work, scan the bitmap from the beginning. */
1139 if ((entry->in_use_p[word] >> bit) & 1)
1142 while (~entry->in_use_p[word] == 0)
1145 #if GCC_VERSION >= 3004
1146 bit = __builtin_ctzl (~entry->in_use_p[word]);
1148 while ((entry->in_use_p[word] >> bit) & 1)
1152 hint = word * HOST_BITS_PER_LONG + bit;
1155 /* Next time, try the next bit. */
1156 entry->next_bit_hint = hint + 1;
1158 object_offset = hint * object_size;
1161 /* Set the in-use bit. */
1162 entry->in_use_p[word] |= ((unsigned long) 1 << bit);
1164 /* Keep a running total of the number of free objects. If this page
1165 fills up, we may have to move it to the end of the list if the
1166 next page isn't full. If the next page is full, all subsequent
1167 pages are full, so there's no need to move it. */
1168 if (--entry->num_free_objects == 0
1169 && entry->next != NULL
1170 && entry->next->num_free_objects > 0)
1172 /* We have a new head for the list. */
1173 G.pages[order] = entry->next;
1175 /* We are moving ENTRY to the end of the page table list.
1176 The new page at the head of the list will have NULL in
1177 its PREV field and ENTRY will have NULL in its NEXT field. */
1178 entry->next->prev = NULL;
1181 /* Append ENTRY to the tail of the list. */
1182 entry->prev = G.page_tails[order];
1183 G.page_tails[order]->next = entry;
1184 G.page_tails[order] = entry;
1187 /* Calculate the object's address. */
1188 result = entry->page + object_offset;
1189 #ifdef GATHER_STATISTICS
1190 ggc_record_overhead (OBJECT_SIZE (order), OBJECT_SIZE (order) - size,
1191 result PASS_MEM_STAT);
1194 #ifdef ENABLE_GC_CHECKING
1195 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1196 exact same semantics in presence of memory bugs, regardless of
1197 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1198 handle to avoid handle leak. */
1199 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, object_size));
1201 /* `Poison' the entire allocated object, including any padding at
1203 memset (result, 0xaf, object_size);
1205 /* Make the bytes after the end of the object unaccessible. Discard the
1206 handle to avoid handle leak. */
1207 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *) result + size,
1208 object_size - size));
1211 /* Tell Valgrind that the memory is there, but its content isn't
1212 defined. The bytes at the end of the object are still marked
1214 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, size));
1216 /* Keep track of how many bytes are being allocated. This
1217 information is used in deciding when to collect. */
1218 G.allocated += object_size;
1220 /* For timevar statistics. */
1221 timevar_ggc_mem_total += object_size;
1223 #ifdef GATHER_STATISTICS
1225 size_t overhead = object_size - size;
1227 G.stats.total_overhead += overhead;
1228 G.stats.total_allocated += object_size;
1229 G.stats.total_overhead_per_order[order] += overhead;
1230 G.stats.total_allocated_per_order[order] += object_size;
1234 G.stats.total_overhead_under32 += overhead;
1235 G.stats.total_allocated_under32 += object_size;
1239 G.stats.total_overhead_under64 += overhead;
1240 G.stats.total_allocated_under64 += object_size;
1244 G.stats.total_overhead_under128 += overhead;
1245 G.stats.total_allocated_under128 += object_size;
1250 if (GGC_DEBUG_LEVEL >= 3)
1251 fprintf (G.debug_file,
1252 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1253 (unsigned long) size, (unsigned long) object_size, result,
1259 /* Mark function for strings. */
1262 gt_ggc_m_S (const void *p)
1267 unsigned long offset;
1269 if (!p || !ggc_allocated_p (p))
1272 /* Look up the page on which the object is alloced. . */
1273 entry = lookup_page_table_entry (p);
1276 /* Calculate the index of the object on the page; this is its bit
1277 position in the in_use_p bitmap. Note that because a char* might
1278 point to the middle of an object, we need special code here to
1279 make sure P points to the start of an object. */
1280 offset = ((const char *) p - entry->page) % object_size_table[entry->order];
1283 /* Here we've seen a char* which does not point to the beginning
1284 of an allocated object. We assume it points to the middle of
1286 gcc_assert (offset == offsetof (struct tree_string, str));
1287 p = ((const char *) p) - offset;
1288 gt_ggc_mx_lang_tree_node ((void *) p);
1292 bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
1293 word = bit / HOST_BITS_PER_LONG;
1294 mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
1296 /* If the bit was previously set, skip it. */
1297 if (entry->in_use_p[word] & mask)
1300 /* Otherwise set it, and decrement the free object count. */
1301 entry->in_use_p[word] |= mask;
1302 entry->num_free_objects -= 1;
1304 if (GGC_DEBUG_LEVEL >= 4)
1305 fprintf (G.debug_file, "Marking %p\n", p);
1310 /* If P is not marked, marks it and return false. Otherwise return true.
1311 P must have been allocated by the GC allocator; it mustn't point to
1312 static objects, stack variables, or memory allocated with malloc. */
1315 ggc_set_mark (const void *p)
1321 /* Look up the page on which the object is alloced. If the object
1322 wasn't allocated by the collector, we'll probably die. */
1323 entry = lookup_page_table_entry (p);
1326 /* Calculate the index of the object on the page; this is its bit
1327 position in the in_use_p bitmap. */
1328 bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
1329 word = bit / HOST_BITS_PER_LONG;
1330 mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
1332 /* If the bit was previously set, skip it. */
1333 if (entry->in_use_p[word] & mask)
1336 /* Otherwise set it, and decrement the free object count. */
1337 entry->in_use_p[word] |= mask;
1338 entry->num_free_objects -= 1;
1340 if (GGC_DEBUG_LEVEL >= 4)
1341 fprintf (G.debug_file, "Marking %p\n", p);
1346 /* Return 1 if P has been marked, zero otherwise.
1347 P must have been allocated by the GC allocator; it mustn't point to
1348 static objects, stack variables, or memory allocated with malloc. */
1351 ggc_marked_p (const void *p)
1357 /* Look up the page on which the object is alloced. If the object
1358 wasn't allocated by the collector, we'll probably die. */
1359 entry = lookup_page_table_entry (p);
1362 /* Calculate the index of the object on the page; this is its bit
1363 position in the in_use_p bitmap. */
1364 bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
1365 word = bit / HOST_BITS_PER_LONG;
1366 mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
1368 return (entry->in_use_p[word] & mask) != 0;
1371 /* Return the size of the gc-able object P. */
1374 ggc_get_size (const void *p)
1376 page_entry *pe = lookup_page_table_entry (p);
1377 return OBJECT_SIZE (pe->order);
1380 /* Release the memory for object P. */
1385 page_entry *pe = lookup_page_table_entry (p);
1386 size_t order = pe->order;
1387 size_t size = OBJECT_SIZE (order);
1389 #ifdef GATHER_STATISTICS
1390 ggc_free_overhead (p);
1393 if (GGC_DEBUG_LEVEL >= 3)
1394 fprintf (G.debug_file,
1395 "Freeing object, actual size=%lu, at %p on %p\n",
1396 (unsigned long) size, p, (void *) pe);
1398 #ifdef ENABLE_GC_CHECKING
1399 /* Poison the data, to indicate the data is garbage. */
1400 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (p, size));
1401 memset (p, 0xa5, size);
1403 /* Let valgrind know the object is free. */
1404 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (p, size));
1406 #ifdef ENABLE_GC_ALWAYS_COLLECT
1407 /* In the completely-anal-checking mode, we do *not* immediately free
1408 the data, but instead verify that the data is *actually* not
1409 reachable the next time we collect. */
1411 struct free_object *fo = XNEW (struct free_object);
1413 fo->next = G.free_object_list;
1414 G.free_object_list = fo;
1418 unsigned int bit_offset, word, bit;
1420 G.allocated -= size;
1422 /* Mark the object not-in-use. */
1423 bit_offset = OFFSET_TO_BIT (((const char *) p) - pe->page, order);
1424 word = bit_offset / HOST_BITS_PER_LONG;
1425 bit = bit_offset % HOST_BITS_PER_LONG;
1426 pe->in_use_p[word] &= ~(1UL << bit);
1428 if (pe->num_free_objects++ == 0)
1432 /* If the page is completely full, then it's supposed to
1433 be after all pages that aren't. Since we've freed one
1434 object from a page that was full, we need to move the
1435 page to the head of the list.
1437 PE is the node we want to move. Q is the previous node
1438 and P is the next node in the list. */
1440 if (q && q->num_free_objects == 0)
1446 /* If PE was at the end of the list, then Q becomes the
1447 new end of the list. If PE was not the end of the
1448 list, then we need to update the PREV field for P. */
1450 G.page_tails[order] = q;
1454 /* Move PE to the head of the list. */
1455 pe->next = G.pages[order];
1457 G.pages[order]->prev = pe;
1458 G.pages[order] = pe;
1461 /* Reset the hint bit to point to the only free object. */
1462 pe->next_bit_hint = bit_offset;
1468 /* Subroutine of init_ggc which computes the pair of numbers used to
1469 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1471 This algorithm is taken from Granlund and Montgomery's paper
1472 "Division by Invariant Integers using Multiplication"
1473 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1477 compute_inverse (unsigned order)
1482 size = OBJECT_SIZE (order);
1484 while (size % 2 == 0)
1491 while (inv * size != 1)
1492 inv = inv * (2 - inv*size);
1494 DIV_MULT (order) = inv;
1495 DIV_SHIFT (order) = e;
1498 /* Initialize the ggc-mmap allocator. */
1504 G.pagesize = getpagesize();
1505 G.lg_pagesize = exact_log2 (G.pagesize);
1507 #ifdef HAVE_MMAP_DEV_ZERO
1508 G.dev_zero_fd = open ("/dev/zero", O_RDONLY);
1509 if (G.dev_zero_fd == -1)
1510 internal_error ("open /dev/zero: %m");
1514 G.debug_file = fopen ("ggc-mmap.debug", "w");
1516 G.debug_file = stdout;
1520 /* StunOS has an amazing off-by-one error for the first mmap allocation
1521 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1522 believe, is an unaligned page allocation, which would cause us to
1523 hork badly if we tried to use it. */
1525 char *p = alloc_anon (NULL, G.pagesize);
1526 struct page_entry *e;
1527 if ((size_t)p & (G.pagesize - 1))
1529 /* How losing. Discard this one and try another. If we still
1530 can't get something useful, give up. */
1532 p = alloc_anon (NULL, G.pagesize);
1533 gcc_assert (!((size_t)p & (G.pagesize - 1)));
1536 /* We have a good page, might as well hold onto it... */
1537 e = XCNEW (struct page_entry);
1538 e->bytes = G.pagesize;
1540 e->next = G.free_pages;
1545 /* Initialize the object size table. */
1546 for (order = 0; order < HOST_BITS_PER_PTR; ++order)
1547 object_size_table[order] = (size_t) 1 << order;
1548 for (order = HOST_BITS_PER_PTR; order < NUM_ORDERS; ++order)
1550 size_t s = extra_order_size_table[order - HOST_BITS_PER_PTR];
1552 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1553 so that we're sure of getting aligned memory. */
1554 s = ROUND_UP (s, MAX_ALIGNMENT);
1555 object_size_table[order] = s;
1558 /* Initialize the objects-per-page and inverse tables. */
1559 for (order = 0; order < NUM_ORDERS; ++order)
1561 objects_per_page_table[order] = G.pagesize / OBJECT_SIZE (order);
1562 if (objects_per_page_table[order] == 0)
1563 objects_per_page_table[order] = 1;
1564 compute_inverse (order);
1567 /* Reset the size_lookup array to put appropriately sized objects in
1568 the special orders. All objects bigger than the previous power
1569 of two, but no greater than the special size, should go in the
1571 for (order = HOST_BITS_PER_PTR; order < NUM_ORDERS; ++order)
1576 i = OBJECT_SIZE (order);
1577 if (i >= NUM_SIZE_LOOKUP)
1580 for (o = size_lookup[i]; o == size_lookup [i]; --i)
1581 size_lookup[i] = order;
1586 G.depth = XNEWVEC (unsigned int, G.depth_max);
1588 G.by_depth_in_use = 0;
1589 G.by_depth_max = INITIAL_PTE_COUNT;
1590 G.by_depth = XNEWVEC (page_entry *, G.by_depth_max);
1591 G.save_in_use = XNEWVEC (unsigned long *, G.by_depth_max);
1594 /* Start a new GGC zone. */
1597 new_ggc_zone (const char *name ATTRIBUTE_UNUSED)
1602 /* Destroy a GGC zone. */
1604 destroy_ggc_zone (struct alloc_zone *zone ATTRIBUTE_UNUSED)
1608 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1609 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1612 ggc_recalculate_in_use_p (page_entry *p)
1617 /* Because the past-the-end bit in in_use_p is always set, we
1618 pretend there is one additional object. */
1619 num_objects = OBJECTS_IN_PAGE (p) + 1;
1621 /* Reset the free object count. */
1622 p->num_free_objects = num_objects;
1624 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1626 i < CEIL (BITMAP_SIZE (num_objects),
1627 sizeof (*p->in_use_p));
1632 /* Something is in use if it is marked, or if it was in use in a
1633 context further down the context stack. */
1634 p->in_use_p[i] |= save_in_use_p (p)[i];
1636 /* Decrement the free object count for every object allocated. */
1637 for (j = p->in_use_p[i]; j; j >>= 1)
1638 p->num_free_objects -= (j & 1);
1641 gcc_assert (p->num_free_objects < num_objects);
1644 /* Unmark all objects. */
1651 for (order = 2; order < NUM_ORDERS; order++)
1655 for (p = G.pages[order]; p != NULL; p = p->next)
1657 size_t num_objects = OBJECTS_IN_PAGE (p);
1658 size_t bitmap_size = BITMAP_SIZE (num_objects + 1);
1660 /* The data should be page-aligned. */
1661 gcc_assert (!((size_t) p->page & (G.pagesize - 1)));
1663 /* Pages that aren't in the topmost context are not collected;
1664 nevertheless, we need their in-use bit vectors to store GC
1665 marks. So, back them up first. */
1666 if (p->context_depth < G.context_depth)
1668 if (! save_in_use_p (p))
1669 save_in_use_p (p) = xmalloc (bitmap_size);
1670 memcpy (save_in_use_p (p), p->in_use_p, bitmap_size);
1673 /* Reset reset the number of free objects and clear the
1674 in-use bits. These will be adjusted by mark_obj. */
1675 p->num_free_objects = num_objects;
1676 memset (p->in_use_p, 0, bitmap_size);
1678 /* Make sure the one-past-the-end bit is always set. */
1679 p->in_use_p[num_objects / HOST_BITS_PER_LONG]
1680 = ((unsigned long) 1 << (num_objects % HOST_BITS_PER_LONG));
1685 /* Free all empty pages. Partially empty pages need no attention
1686 because the `mark' bit doubles as an `unused' bit. */
1693 for (order = 2; order < NUM_ORDERS; order++)
1695 /* The last page-entry to consider, regardless of entries
1696 placed at the end of the list. */
1697 page_entry * const last = G.page_tails[order];
1700 size_t live_objects;
1701 page_entry *p, *previous;
1711 page_entry *next = p->next;
1713 /* Loop until all entries have been examined. */
1716 num_objects = OBJECTS_IN_PAGE (p);
1718 /* Add all live objects on this page to the count of
1719 allocated memory. */
1720 live_objects = num_objects - p->num_free_objects;
1722 G.allocated += OBJECT_SIZE (order) * live_objects;
1724 /* Only objects on pages in the topmost context should get
1726 if (p->context_depth < G.context_depth)
1729 /* Remove the page if it's empty. */
1730 else if (live_objects == 0)
1732 /* If P was the first page in the list, then NEXT
1733 becomes the new first page in the list, otherwise
1734 splice P out of the forward pointers. */
1736 G.pages[order] = next;
1738 previous->next = next;
1740 /* Splice P out of the back pointers too. */
1742 next->prev = previous;
1744 /* Are we removing the last element? */
1745 if (p == G.page_tails[order])
1746 G.page_tails[order] = previous;
1751 /* If the page is full, move it to the end. */
1752 else if (p->num_free_objects == 0)
1754 /* Don't move it if it's already at the end. */
1755 if (p != G.page_tails[order])
1757 /* Move p to the end of the list. */
1759 p->prev = G.page_tails[order];
1760 G.page_tails[order]->next = p;
1762 /* Update the tail pointer... */
1763 G.page_tails[order] = p;
1765 /* ... and the head pointer, if necessary. */
1767 G.pages[order] = next;
1769 previous->next = next;
1771 /* And update the backpointer in NEXT if necessary. */
1773 next->prev = previous;
1779 /* If we've fallen through to here, it's a page in the
1780 topmost context that is neither full nor empty. Such a
1781 page must precede pages at lesser context depth in the
1782 list, so move it to the head. */
1783 else if (p != G.pages[order])
1785 previous->next = p->next;
1787 /* Update the backchain in the next node if it exists. */
1789 p->next->prev = previous;
1791 /* Move P to the head of the list. */
1792 p->next = G.pages[order];
1794 G.pages[order]->prev = p;
1796 /* Update the head pointer. */
1799 /* Are we moving the last element? */
1800 if (G.page_tails[order] == p)
1801 G.page_tails[order] = previous;
1810 /* Now, restore the in_use_p vectors for any pages from contexts
1811 other than the current one. */
1812 for (p = G.pages[order]; p; p = p->next)
1813 if (p->context_depth != G.context_depth)
1814 ggc_recalculate_in_use_p (p);
1818 #ifdef ENABLE_GC_CHECKING
1819 /* Clobber all free objects. */
1826 for (order = 2; order < NUM_ORDERS; order++)
1828 size_t size = OBJECT_SIZE (order);
1831 for (p = G.pages[order]; p != NULL; p = p->next)
1836 if (p->context_depth != G.context_depth)
1837 /* Since we don't do any collection for pages in pushed
1838 contexts, there's no need to do any poisoning. And
1839 besides, the IN_USE_P array isn't valid until we pop
1843 num_objects = OBJECTS_IN_PAGE (p);
1844 for (i = 0; i < num_objects; i++)
1847 word = i / HOST_BITS_PER_LONG;
1848 bit = i % HOST_BITS_PER_LONG;
1849 if (((p->in_use_p[word] >> bit) & 1) == 0)
1851 char *object = p->page + i * size;
1853 /* Keep poison-by-write when we expect to use Valgrind,
1854 so the exact same memory semantics is kept, in case
1855 there are memory errors. We override this request
1857 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (object,
1859 memset (object, 0xa5, size);
1861 /* Drop the handle to avoid handle leak. */
1862 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (object, size));
1869 #define poison_pages()
1872 #ifdef ENABLE_GC_ALWAYS_COLLECT
1873 /* Validate that the reportedly free objects actually are. */
1876 validate_free_objects (void)
1878 struct free_object *f, *next, *still_free = NULL;
1880 for (f = G.free_object_list; f ; f = next)
1882 page_entry *pe = lookup_page_table_entry (f->object);
1885 bit = OFFSET_TO_BIT ((char *)f->object - pe->page, pe->order);
1886 word = bit / HOST_BITS_PER_LONG;
1887 bit = bit % HOST_BITS_PER_LONG;
1890 /* Make certain it isn't visible from any root. Notice that we
1891 do this check before sweep_pages merges save_in_use_p. */
1892 gcc_assert (!(pe->in_use_p[word] & (1UL << bit)));
1894 /* If the object comes from an outer context, then retain the
1895 free_object entry, so that we can verify that the address
1896 isn't live on the stack in some outer context. */
1897 if (pe->context_depth != G.context_depth)
1899 f->next = still_free;
1906 G.free_object_list = still_free;
1909 #define validate_free_objects()
1912 /* Top level mark-and-sweep routine. */
1917 /* Avoid frequent unnecessary work by skipping collection if the
1918 total allocations haven't expanded much since the last
1920 float allocated_last_gc =
1921 MAX (G.allocated_last_gc, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE) * 1024);
1923 float min_expand = allocated_last_gc * PARAM_VALUE (GGC_MIN_EXPAND) / 100;
1925 if (G.allocated < allocated_last_gc + min_expand && !ggc_force_collect)
1928 timevar_push (TV_GC);
1930 fprintf (stderr, " {GC %luk -> ", (unsigned long) G.allocated / 1024);
1931 if (GGC_DEBUG_LEVEL >= 2)
1932 fprintf (G.debug_file, "BEGIN COLLECTING\n");
1934 /* Zero the total allocated bytes. This will be recalculated in the
1938 /* Release the pages we freed the last time we collected, but didn't
1939 reuse in the interim. */
1942 /* Indicate that we've seen collections at this context depth. */
1943 G.context_depth_collections = ((unsigned long)1 << (G.context_depth + 1)) - 1;
1947 #ifdef GATHER_STATISTICS
1948 ggc_prune_overhead_list ();
1951 validate_free_objects ();
1954 G.allocated_last_gc = G.allocated;
1956 timevar_pop (TV_GC);
1959 fprintf (stderr, "%luk}", (unsigned long) G.allocated / 1024);
1960 if (GGC_DEBUG_LEVEL >= 2)
1961 fprintf (G.debug_file, "END COLLECTING\n");
1964 /* Print allocation statistics. */
1965 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
1967 : ((x) < 1024*1024*10 \
1969 : (x) / (1024*1024))))
1970 #define STAT_LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
1973 ggc_print_statistics (void)
1975 struct ggc_statistics stats;
1977 size_t total_overhead = 0;
1979 /* Clear the statistics. */
1980 memset (&stats, 0, sizeof (stats));
1982 /* Make sure collection will really occur. */
1983 G.allocated_last_gc = 0;
1985 /* Collect and print the statistics common across collectors. */
1986 ggc_print_common_statistics (stderr, &stats);
1988 /* Release free pages so that we will not count the bytes allocated
1989 there as part of the total allocated memory. */
1992 /* Collect some information about the various sizes of
1995 "Memory still allocated at the end of the compilation process\n");
1996 fprintf (stderr, "%-5s %10s %10s %10s\n",
1997 "Size", "Allocated", "Used", "Overhead");
1998 for (i = 0; i < NUM_ORDERS; ++i)
2005 /* Skip empty entries. */
2009 overhead = allocated = in_use = 0;
2011 /* Figure out the total number of bytes allocated for objects of
2012 this size, and how many of them are actually in use. Also figure
2013 out how much memory the page table is using. */
2014 for (p = G.pages[i]; p; p = p->next)
2016 allocated += p->bytes;
2018 (OBJECTS_IN_PAGE (p) - p->num_free_objects) * OBJECT_SIZE (i);
2020 overhead += (sizeof (page_entry) - sizeof (long)
2021 + BITMAP_SIZE (OBJECTS_IN_PAGE (p) + 1));
2023 fprintf (stderr, "%-5lu %10lu%c %10lu%c %10lu%c\n",
2024 (unsigned long) OBJECT_SIZE (i),
2025 SCALE (allocated), STAT_LABEL (allocated),
2026 SCALE (in_use), STAT_LABEL (in_use),
2027 SCALE (overhead), STAT_LABEL (overhead));
2028 total_overhead += overhead;
2030 fprintf (stderr, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
2031 SCALE (G.bytes_mapped), STAT_LABEL (G.bytes_mapped),
2032 SCALE (G.allocated), STAT_LABEL(G.allocated),
2033 SCALE (total_overhead), STAT_LABEL (total_overhead));
2035 #ifdef GATHER_STATISTICS
2037 fprintf (stderr, "\nTotal allocations and overheads during the compilation process\n");
2039 fprintf (stderr, "Total Overhead: %10lld\n",
2040 G.stats.total_overhead);
2041 fprintf (stderr, "Total Allocated: %10lld\n",
2042 G.stats.total_allocated);
2044 fprintf (stderr, "Total Overhead under 32B: %10lld\n",
2045 G.stats.total_overhead_under32);
2046 fprintf (stderr, "Total Allocated under 32B: %10lld\n",
2047 G.stats.total_allocated_under32);
2048 fprintf (stderr, "Total Overhead under 64B: %10lld\n",
2049 G.stats.total_overhead_under64);
2050 fprintf (stderr, "Total Allocated under 64B: %10lld\n",
2051 G.stats.total_allocated_under64);
2052 fprintf (stderr, "Total Overhead under 128B: %10lld\n",
2053 G.stats.total_overhead_under128);
2054 fprintf (stderr, "Total Allocated under 128B: %10lld\n",
2055 G.stats.total_allocated_under128);
2057 for (i = 0; i < NUM_ORDERS; i++)
2058 if (G.stats.total_allocated_per_order[i])
2060 fprintf (stderr, "Total Overhead page size %7lu: %10lld\n",
2061 (unsigned long) OBJECT_SIZE (i),
2062 G.stats.total_overhead_per_order[i]);
2063 fprintf (stderr, "Total Allocated page size %7lu: %10lld\n",
2064 (unsigned long) OBJECT_SIZE (i),
2065 G.stats.total_allocated_per_order[i]);
2073 struct ggc_pch_ondisk
2075 unsigned totals[NUM_ORDERS];
2077 size_t base[NUM_ORDERS];
2078 size_t written[NUM_ORDERS];
2081 struct ggc_pch_data *
2084 return XCNEW (struct ggc_pch_data);
2088 ggc_pch_count_object (struct ggc_pch_data *d, void *x ATTRIBUTE_UNUSED,
2089 size_t size, bool is_string ATTRIBUTE_UNUSED,
2090 enum gt_types_enum type ATTRIBUTE_UNUSED)
2094 if (size < NUM_SIZE_LOOKUP)
2095 order = size_lookup[size];
2099 while (size > OBJECT_SIZE (order))
2103 d->d.totals[order]++;
2107 ggc_pch_total_size (struct ggc_pch_data *d)
2112 for (i = 0; i < NUM_ORDERS; i++)
2113 a += ROUND_UP (d->d.totals[i] * OBJECT_SIZE (i), G.pagesize);
2118 ggc_pch_this_base (struct ggc_pch_data *d, void *base)
2120 size_t a = (size_t) base;
2123 for (i = 0; i < NUM_ORDERS; i++)
2126 a += ROUND_UP (d->d.totals[i] * OBJECT_SIZE (i), G.pagesize);
2132 ggc_pch_alloc_object (struct ggc_pch_data *d, void *x ATTRIBUTE_UNUSED,
2133 size_t size, bool is_string ATTRIBUTE_UNUSED,
2134 enum gt_types_enum type ATTRIBUTE_UNUSED)
2139 if (size < NUM_SIZE_LOOKUP)
2140 order = size_lookup[size];
2144 while (size > OBJECT_SIZE (order))
2148 result = (char *) d->base[order];
2149 d->base[order] += OBJECT_SIZE (order);
2154 ggc_pch_prepare_write (struct ggc_pch_data *d ATTRIBUTE_UNUSED,
2155 FILE *f ATTRIBUTE_UNUSED)
2157 /* Nothing to do. */
2161 ggc_pch_write_object (struct ggc_pch_data *d ATTRIBUTE_UNUSED,
2162 FILE *f, void *x, void *newx ATTRIBUTE_UNUSED,
2163 size_t size, bool is_string ATTRIBUTE_UNUSED)
2166 static const char emptyBytes[256];
2168 if (size < NUM_SIZE_LOOKUP)
2169 order = size_lookup[size];
2173 while (size > OBJECT_SIZE (order))
2177 if (fwrite (x, size, 1, f) != 1)
2178 fatal_error ("can't write PCH file: %m");
2180 /* If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
2181 object out to OBJECT_SIZE(order). This happens for strings. */
2183 if (size != OBJECT_SIZE (order))
2185 unsigned padding = OBJECT_SIZE(order) - size;
2187 /* To speed small writes, we use a nulled-out array that's larger
2188 than most padding requests as the source for our null bytes. This
2189 permits us to do the padding with fwrite() rather than fseek(), and
2190 limits the chance the OS may try to flush any outstanding writes. */
2191 if (padding <= sizeof(emptyBytes))
2193 if (fwrite (emptyBytes, 1, padding, f) != padding)
2194 fatal_error ("can't write PCH file");
2198 /* Larger than our buffer? Just default to fseek. */
2199 if (fseek (f, padding, SEEK_CUR) != 0)
2200 fatal_error ("can't write PCH file");
2204 d->written[order]++;
2205 if (d->written[order] == d->d.totals[order]
2206 && fseek (f, ROUND_UP_VALUE (d->d.totals[order] * OBJECT_SIZE (order),
2209 fatal_error ("can't write PCH file: %m");
2213 ggc_pch_finish (struct ggc_pch_data *d, FILE *f)
2215 if (fwrite (&d->d, sizeof (d->d), 1, f) != 1)
2216 fatal_error ("can't write PCH file: %m");
2220 /* Move the PCH PTE entries just added to the end of by_depth, to the
2224 move_ptes_to_front (int count_old_page_tables, int count_new_page_tables)
2228 /* First, we swap the new entries to the front of the varrays. */
2229 page_entry **new_by_depth;
2230 unsigned long **new_save_in_use;
2232 new_by_depth = XNEWVEC (page_entry *, G.by_depth_max);
2233 new_save_in_use = XNEWVEC (unsigned long *, G.by_depth_max);
2235 memcpy (&new_by_depth[0],
2236 &G.by_depth[count_old_page_tables],
2237 count_new_page_tables * sizeof (void *));
2238 memcpy (&new_by_depth[count_new_page_tables],
2240 count_old_page_tables * sizeof (void *));
2241 memcpy (&new_save_in_use[0],
2242 &G.save_in_use[count_old_page_tables],
2243 count_new_page_tables * sizeof (void *));
2244 memcpy (&new_save_in_use[count_new_page_tables],
2246 count_old_page_tables * sizeof (void *));
2249 free (G.save_in_use);
2251 G.by_depth = new_by_depth;
2252 G.save_in_use = new_save_in_use;
2254 /* Now update all the index_by_depth fields. */
2255 for (i = G.by_depth_in_use; i > 0; --i)
2257 page_entry *p = G.by_depth[i-1];
2258 p->index_by_depth = i-1;
2261 /* And last, we update the depth pointers in G.depth. The first
2262 entry is already 0, and context 0 entries always start at index
2263 0, so there is nothing to update in the first slot. We need a
2264 second slot, only if we have old ptes, and if we do, they start
2265 at index count_new_page_tables. */
2266 if (count_old_page_tables)
2267 push_depth (count_new_page_tables);
2271 ggc_pch_read (FILE *f, void *addr)
2273 struct ggc_pch_ondisk d;
2276 unsigned long count_old_page_tables;
2277 unsigned long count_new_page_tables;
2279 count_old_page_tables = G.by_depth_in_use;
2281 /* We've just read in a PCH file. So, every object that used to be
2282 allocated is now free. */
2284 #ifdef ENABLE_GC_CHECKING
2287 /* Since we free all the allocated objects, the free list becomes
2288 useless. Validate it now, which will also clear it. */
2289 validate_free_objects();
2291 /* No object read from a PCH file should ever be freed. So, set the
2292 context depth to 1, and set the depth of all the currently-allocated
2293 pages to be 1 too. PCH pages will have depth 0. */
2294 gcc_assert (!G.context_depth);
2295 G.context_depth = 1;
2296 for (i = 0; i < NUM_ORDERS; i++)
2299 for (p = G.pages[i]; p != NULL; p = p->next)
2300 p->context_depth = G.context_depth;
2303 /* Allocate the appropriate page-table entries for the pages read from
2305 if (fread (&d, sizeof (d), 1, f) != 1)
2306 fatal_error ("can't read PCH file: %m");
2308 for (i = 0; i < NUM_ORDERS; i++)
2310 struct page_entry *entry;
2316 if (d.totals[i] == 0)
2319 bytes = ROUND_UP (d.totals[i] * OBJECT_SIZE (i), G.pagesize);
2320 num_objs = bytes / OBJECT_SIZE (i);
2321 entry = xcalloc (1, (sizeof (struct page_entry)
2323 + BITMAP_SIZE (num_objs + 1)));
2324 entry->bytes = bytes;
2326 entry->context_depth = 0;
2328 entry->num_free_objects = 0;
2332 j + HOST_BITS_PER_LONG <= num_objs + 1;
2333 j += HOST_BITS_PER_LONG)
2334 entry->in_use_p[j / HOST_BITS_PER_LONG] = -1;
2335 for (; j < num_objs + 1; j++)
2336 entry->in_use_p[j / HOST_BITS_PER_LONG]
2337 |= 1L << (j % HOST_BITS_PER_LONG);
2339 for (pte = entry->page;
2340 pte < entry->page + entry->bytes;
2342 set_page_table_entry (pte, entry);
2344 if (G.page_tails[i] != NULL)
2345 G.page_tails[i]->next = entry;
2348 G.page_tails[i] = entry;
2350 /* We start off by just adding all the new information to the
2351 end of the varrays, later, we will move the new information
2352 to the front of the varrays, as the PCH page tables are at
2354 push_by_depth (entry, 0);
2357 /* Now, we update the various data structures that speed page table
2359 count_new_page_tables = G.by_depth_in_use - count_old_page_tables;
2361 move_ptes_to_front (count_old_page_tables, count_new_page_tables);
2363 /* Update the statistics. */
2364 G.allocated = G.allocated_last_gc = offs - (char *)addr;