1 /* "Bag-of-pages" garbage collector for the GNU compiler.
2 Copyright (C) 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 2, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
33 #ifdef ENABLE_VALGRIND_CHECKING
34 # ifdef HAVE_MEMCHECK_H
35 # include <memcheck.h>
37 # include <valgrind.h>
40 /* Avoid #ifdef:s when we can help it. */
41 #define VALGRIND_DISCARD(x)
44 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
45 file open. Prefer either to valloc. */
47 # undef HAVE_MMAP_DEV_ZERO
49 # include <sys/mman.h>
51 # define MAP_FAILED -1
53 # if !defined (MAP_ANONYMOUS) && defined (MAP_ANON)
54 # define MAP_ANONYMOUS MAP_ANON
60 #ifdef HAVE_MMAP_DEV_ZERO
62 # include <sys/mman.h>
64 # define MAP_FAILED -1
71 #define USING_MALLOC_PAGE_GROUPS
76 This garbage-collecting allocator allocates objects on one of a set
77 of pages. Each page can allocate objects of a single size only;
78 available sizes are powers of two starting at four bytes. The size
79 of an allocation request is rounded up to the next power of two
80 (`order'), and satisfied from the appropriate page.
82 Each page is recorded in a page-entry, which also maintains an
83 in-use bitmap of object positions on the page. This allows the
84 allocation state of a particular object to be flipped without
85 touching the page itself.
87 Each page-entry also has a context depth, which is used to track
88 pushing and popping of allocation contexts. Only objects allocated
89 in the current (highest-numbered) context may be collected.
91 Page entries are arranged in an array of singly-linked lists. The
92 array is indexed by the allocation size, in bits, of the pages on
93 it; i.e. all pages on a list allocate objects of the same size.
94 Pages are ordered on the list such that all non-full pages precede
95 all full pages, with non-full pages arranged in order of decreasing
98 Empty pages (of all orders) are kept on a single page cache list,
99 and are considered first when new pages are required; they are
100 deallocated at the start of the next collection if they haven't
101 been recycled by then. */
103 /* Define GGC_DEBUG_LEVEL to print debugging information.
104 0: No debugging output.
105 1: GC statistics only.
106 2: Page-entry allocations/deallocations as well.
107 3: Object allocations as well.
108 4: Object marks as well. */
109 #define GGC_DEBUG_LEVEL (0)
111 #ifndef HOST_BITS_PER_PTR
112 #define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
116 /* A two-level tree is used to look up the page-entry for a given
117 pointer. Two chunks of the pointer's bits are extracted to index
118 the first and second levels of the tree, as follows:
122 msb +----------------+----+------+------+ lsb
128 The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
129 pages are aligned on system page boundaries. The next most
130 significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
131 index values in the lookup table, respectively.
133 For 32-bit architectures and the settings below, there are no
134 leftover bits. For architectures with wider pointers, the lookup
135 tree points to a list of pages, which must be scanned to find the
138 #define PAGE_L1_BITS (8)
139 #define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
140 #define PAGE_L1_SIZE ((size_t) 1 << PAGE_L1_BITS)
141 #define PAGE_L2_SIZE ((size_t) 1 << PAGE_L2_BITS)
143 #define LOOKUP_L1(p) \
144 (((size_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
146 #define LOOKUP_L2(p) \
147 (((size_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
149 /* The number of objects per allocation page, for objects on a page of
150 the indicated ORDER. */
151 #define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
153 /* The number of objects in P. */
154 #define OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
156 /* The size of an object on a page of the indicated ORDER. */
157 #define OBJECT_SIZE(ORDER) object_size_table[ORDER]
159 /* For speed, we avoid doing a general integer divide to locate the
160 offset in the allocation bitmap, by precalculating numbers M, S
161 such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
162 within the page which is evenly divisible by the object size Z. */
163 #define DIV_MULT(ORDER) inverse_table[ORDER].mult
164 #define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
165 #define OFFSET_TO_BIT(OFFSET, ORDER) \
166 (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
168 /* The number of extra orders, not corresponding to power-of-two sized
171 #define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
173 #define RTL_SIZE(NSLOTS) \
174 (sizeof (struct rtx_def) + ((NSLOTS) - 1) * sizeof (rtunion))
176 #define TREE_EXP_SIZE(OPS) \
177 (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
179 /* The Ith entry is the maximum size of an object to be stored in the
180 Ith extra order. Adding a new entry to this array is the *only*
181 thing you need to do to add a new special allocation size. */
183 static const size_t extra_order_size_table
[] = {
184 sizeof (struct tree_decl
),
185 sizeof (struct tree_list
),
187 RTL_SIZE (2), /* REG, MEM, PLUS, etc. */
188 RTL_SIZE (10), /* INSN, CALL_INSN, JUMP_INSN */
191 /* The total number of orders. */
193 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
195 /* We use this structure to determine the alignment required for
196 allocations. For power-of-two sized allocations, that's not a
197 problem, but it does matter for odd-sized allocations. */
199 struct max_alignment
{
207 /* The biggest alignment required. */
209 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
211 /* Compute the smallest nonnegative number which when added to X gives
214 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
216 /* Compute the smallest multiple of F that is >= X. */
218 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
220 /* The Ith entry is the number of objects on a page or order I. */
222 static unsigned objects_per_page_table
[NUM_ORDERS
];
224 /* The Ith entry is the size of an object on a page of order I. */
226 static size_t object_size_table
[NUM_ORDERS
];
228 /* The Ith entry is a pair of numbers (mult, shift) such that
229 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
230 for all k evenly divisible by OBJECT_SIZE(I). */
237 inverse_table
[NUM_ORDERS
];
239 /* A page_entry records the status of an allocation page. This
240 structure is dynamically sized to fit the bitmap in_use_p. */
241 typedef struct page_entry
243 /* The next page-entry with objects of the same size, or NULL if
244 this is the last page-entry. */
245 struct page_entry
*next
;
247 /* The number of bytes allocated. (This will always be a multiple
248 of the host system page size.) */
251 /* The address at which the memory is allocated. */
254 #ifdef USING_MALLOC_PAGE_GROUPS
255 /* Back pointer to the page group this page came from. */
256 struct page_group
*group
;
259 /* This is the index in the by_depth varray where this page table
261 unsigned long index_by_depth
;
263 /* Context depth of this page. */
264 unsigned short context_depth
;
266 /* The number of free objects remaining on this page. */
267 unsigned short num_free_objects
;
269 /* A likely candidate for the bit position of a free object for the
270 next allocation from this page. */
271 unsigned short next_bit_hint
;
273 /* The lg of size of objects allocated from this page. */
276 /* A bit vector indicating whether or not objects are in use. The
277 Nth bit is one if the Nth object on this page is allocated. This
278 array is dynamically sized. */
279 unsigned long in_use_p
[1];
282 #ifdef USING_MALLOC_PAGE_GROUPS
283 /* A page_group describes a large allocation from malloc, from which
284 we parcel out aligned pages. */
285 typedef struct page_group
287 /* A linked list of all extant page groups. */
288 struct page_group
*next
;
290 /* The address we received from malloc. */
293 /* The size of the block. */
296 /* A bitmask of pages in use. */
301 #if HOST_BITS_PER_PTR <= 32
303 /* On 32-bit hosts, we use a two level page table, as pictured above. */
304 typedef page_entry
**page_table
[PAGE_L1_SIZE
];
308 /* On 64-bit hosts, we use the same two level page tables plus a linked
309 list that disambiguates the top 32-bits. There will almost always be
310 exactly one entry in the list. */
311 typedef struct page_table_chain
313 struct page_table_chain
*next
;
315 page_entry
**table
[PAGE_L1_SIZE
];
320 /* The rest of the global variables. */
321 static struct globals
323 /* The Nth element in this array is a page with objects of size 2^N.
324 If there are any pages with free objects, they will be at the
325 head of the list. NULL if there are no page-entries for this
327 page_entry
*pages
[NUM_ORDERS
];
329 /* The Nth element in this array is the last page with objects of
330 size 2^N. NULL if there are no page-entries for this object
332 page_entry
*page_tails
[NUM_ORDERS
];
334 /* Lookup table for associating allocation pages with object addresses. */
337 /* The system's page size. */
341 /* Bytes currently allocated. */
344 /* Bytes currently allocated at the end of the last collection. */
345 size_t allocated_last_gc
;
347 /* Total amount of memory mapped. */
350 /* Bit N set if any allocations have been done at context depth N. */
351 unsigned long context_depth_allocations
;
353 /* Bit N set if any collections have been done at context depth N. */
354 unsigned long context_depth_collections
;
356 /* The current depth in the context stack. */
357 unsigned short context_depth
;
359 /* A file descriptor open to /dev/zero for reading. */
360 #if defined (HAVE_MMAP_DEV_ZERO)
364 /* A cache of free system pages. */
365 page_entry
*free_pages
;
367 #ifdef USING_MALLOC_PAGE_GROUPS
368 page_group
*page_groups
;
371 /* The file descriptor for debugging output. */
374 /* Current number of elements in use in depth below. */
375 unsigned int depth_in_use
;
377 /* Maximum number of elements that can be used before resizing. */
378 unsigned int depth_max
;
380 /* Each element of this arry is an index in by_depth where the given
381 depth starts. This structure is indexed by that given depth we
382 are interested in. */
385 /* Current number of elements in use in by_depth below. */
386 unsigned int by_depth_in_use
;
388 /* Maximum number of elements that can be used before resizing. */
389 unsigned int by_depth_max
;
391 /* Each element of this array is a pointer to a page_entry, all
392 page_entries can be found in here by increasing depth.
393 index_by_depth in the page_entry is the index into this data
394 structure where that page_entry can be found. This is used to
395 speed up finding all page_entries at a particular depth. */
396 page_entry
**by_depth
;
398 /* Each element is a pointer to the saved in_use_p bits, if any,
399 zero otherwise. We allocate them all together, to enable a
400 better runtime data access pattern. */
401 unsigned long **save_in_use
;
405 /* The size in bytes required to maintain a bitmap for the objects
407 #define BITMAP_SIZE(Num_objects) \
408 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
410 /* Allocate pages in chunks of this size, to throttle calls to memory
411 allocation routines. The first page is used, the rest go onto the
412 free list. This cannot be larger than HOST_BITS_PER_INT for the
413 in_use bitmask for page_group. */
414 #define GGC_QUIRE_SIZE 16
416 /* Initial guess as to how many page table entries we might need. */
417 #define INITIAL_PTE_COUNT 128
419 static int ggc_allocated_p (const void *);
420 static page_entry
*lookup_page_table_entry (const void *);
421 static void set_page_table_entry (void *, page_entry
*);
423 static char *alloc_anon (char *, size_t);
425 #ifdef USING_MALLOC_PAGE_GROUPS
426 static size_t page_group_index (char *, char *);
427 static void set_page_group_in_use (page_group
*, char *);
428 static void clear_page_group_in_use (page_group
*, char *);
430 static struct page_entry
* alloc_page (unsigned);
431 static void free_page (struct page_entry
*);
432 static void release_pages (void);
433 static void clear_marks (void);
434 static void sweep_pages (void);
435 static void ggc_recalculate_in_use_p (page_entry
*);
436 static void compute_inverse (unsigned);
437 static inline void adjust_depth (void);
438 static void move_ptes_to_front (int, int);
440 #ifdef ENABLE_GC_CHECKING
441 static void poison_pages (void);
444 void debug_print_page_list (int);
445 static void push_depth (unsigned int);
446 static void push_by_depth (page_entry
*, unsigned long *);
448 /* Push an entry onto G.depth. */
451 push_depth (unsigned int i
)
453 if (G
.depth_in_use
>= G
.depth_max
)
456 G
.depth
= (unsigned int *) xrealloc ((char *) G
.depth
,
457 G
.depth_max
* sizeof (unsigned int));
459 G
.depth
[G
.depth_in_use
++] = i
;
462 /* Push an entry onto G.by_depth and G.save_in_use. */
465 push_by_depth (page_entry
*p
, unsigned long *s
)
467 if (G
.by_depth_in_use
>= G
.by_depth_max
)
470 G
.by_depth
= (page_entry
**) xrealloc ((char *) G
.by_depth
,
471 G
.by_depth_max
* sizeof (page_entry
*));
472 G
.save_in_use
= (unsigned long **) xrealloc ((char *) G
.save_in_use
,
473 G
.by_depth_max
* sizeof (unsigned long *));
475 G
.by_depth
[G
.by_depth_in_use
] = p
;
476 G
.save_in_use
[G
.by_depth_in_use
++] = s
;
479 #if (GCC_VERSION < 3001)
480 #define prefetch(X) ((void) X)
482 #define prefetch(X) __builtin_prefetch (X)
485 #define save_in_use_p_i(__i) \
487 #define save_in_use_p(__p) \
488 (save_in_use_p_i (__p->index_by_depth))
490 /* Returns nonzero if P was allocated in GC'able memory. */
493 ggc_allocated_p (const void *p
)
498 #if HOST_BITS_PER_PTR <= 32
501 page_table table
= G
.lookup
;
502 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
507 if (table
->high_bits
== high_bits
)
511 base
= &table
->table
[0];
514 /* Extract the level 1 and 2 indices. */
518 return base
[L1
] && base
[L1
][L2
];
521 /* Traverse the page table and find the entry for a page.
522 Die (probably) if the object wasn't allocated via GC. */
524 static inline page_entry
*
525 lookup_page_table_entry (const void *p
)
530 #if HOST_BITS_PER_PTR <= 32
533 page_table table
= G
.lookup
;
534 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
535 while (table
->high_bits
!= high_bits
)
537 base
= &table
->table
[0];
540 /* Extract the level 1 and 2 indices. */
547 /* Set the page table entry for a page. */
550 set_page_table_entry (void *p
, page_entry
*entry
)
555 #if HOST_BITS_PER_PTR <= 32
559 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
560 for (table
= G
.lookup
; table
; table
= table
->next
)
561 if (table
->high_bits
== high_bits
)
564 /* Not found -- allocate a new table. */
565 table
= (page_table
) xcalloc (1, sizeof(*table
));
566 table
->next
= G
.lookup
;
567 table
->high_bits
= high_bits
;
570 base
= &table
->table
[0];
573 /* Extract the level 1 and 2 indices. */
577 if (base
[L1
] == NULL
)
578 base
[L1
] = (page_entry
**) xcalloc (PAGE_L2_SIZE
, sizeof (page_entry
*));
580 base
[L1
][L2
] = entry
;
583 /* Prints the page-entry for object size ORDER, for debugging. */
586 debug_print_page_list (int order
)
589 printf ("Head=%p, Tail=%p:\n", (void *) G
.pages
[order
],
590 (void *) G
.page_tails
[order
]);
594 printf ("%p(%1d|%3d) -> ", (void *) p
, p
->context_depth
,
595 p
->num_free_objects
);
603 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
604 (if non-null). The ifdef structure here is intended to cause a
605 compile error unless exactly one of the HAVE_* is defined. */
608 alloc_anon (char *pref ATTRIBUTE_UNUSED
, size_t size
)
610 #ifdef HAVE_MMAP_ANON
611 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
612 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
614 #ifdef HAVE_MMAP_DEV_ZERO
615 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
616 MAP_PRIVATE
, G
.dev_zero_fd
, 0);
619 if (page
== (char *) MAP_FAILED
)
621 perror ("virtual memory exhausted");
622 exit (FATAL_EXIT_CODE
);
625 /* Remember that we allocated this memory. */
626 G
.bytes_mapped
+= size
;
628 /* Pretend we don't have access to the allocated pages. We'll enable
629 access to smaller pieces of the area in ggc_alloc. Discard the
630 handle to avoid handle leak. */
631 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (page
, size
));
636 #ifdef USING_MALLOC_PAGE_GROUPS
637 /* Compute the index for this page into the page group. */
640 page_group_index (char *allocation
, char *page
)
642 return (size_t) (page
- allocation
) >> G
.lg_pagesize
;
645 /* Set and clear the in_use bit for this page in the page group. */
648 set_page_group_in_use (page_group
*group
, char *page
)
650 group
->in_use
|= 1 << page_group_index (group
->allocation
, page
);
654 clear_page_group_in_use (page_group
*group
, char *page
)
656 group
->in_use
&= ~(1 << page_group_index (group
->allocation
, page
));
660 /* Allocate a new page for allocating objects of size 2^ORDER,
661 and return an entry for it. The entry is not added to the
662 appropriate page_table list. */
664 static inline struct page_entry
*
665 alloc_page (unsigned order
)
667 struct page_entry
*entry
, *p
, **pp
;
671 size_t page_entry_size
;
673 #ifdef USING_MALLOC_PAGE_GROUPS
677 num_objects
= OBJECTS_PER_PAGE (order
);
678 bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
679 page_entry_size
= sizeof (page_entry
) - sizeof (long) + bitmap_size
;
680 entry_size
= num_objects
* OBJECT_SIZE (order
);
681 if (entry_size
< G
.pagesize
)
682 entry_size
= G
.pagesize
;
687 /* Check the list of free pages for one we can use. */
688 for (pp
= &G
.free_pages
, p
= *pp
; p
; pp
= &p
->next
, p
= *pp
)
689 if (p
->bytes
== entry_size
)
694 /* Recycle the allocated memory from this page ... */
698 #ifdef USING_MALLOC_PAGE_GROUPS
702 /* ... and, if possible, the page entry itself. */
703 if (p
->order
== order
)
706 memset (entry
, 0, page_entry_size
);
712 else if (entry_size
== G
.pagesize
)
714 /* We want just one page. Allocate a bunch of them and put the
715 extras on the freelist. (Can only do this optimization with
716 mmap for backing store.) */
717 struct page_entry
*e
, *f
= G
.free_pages
;
720 page
= alloc_anon (NULL
, G
.pagesize
* GGC_QUIRE_SIZE
);
722 /* This loop counts down so that the chain will be in ascending
724 for (i
= GGC_QUIRE_SIZE
- 1; i
>= 1; i
--)
726 e
= (struct page_entry
*) xcalloc (1, page_entry_size
);
728 e
->bytes
= G
.pagesize
;
729 e
->page
= page
+ (i
<< G
.lg_pagesize
);
737 page
= alloc_anon (NULL
, entry_size
);
739 #ifdef USING_MALLOC_PAGE_GROUPS
742 /* Allocate a large block of memory and serve out the aligned
743 pages therein. This results in much less memory wastage
744 than the traditional implementation of valloc. */
746 char *allocation
, *a
, *enda
;
747 size_t alloc_size
, head_slop
, tail_slop
;
748 int multiple_pages
= (entry_size
== G
.pagesize
);
751 alloc_size
= GGC_QUIRE_SIZE
* G
.pagesize
;
753 alloc_size
= entry_size
+ G
.pagesize
- 1;
754 allocation
= xmalloc (alloc_size
);
756 page
= (char *) (((size_t) allocation
+ G
.pagesize
- 1) & -G
.pagesize
);
757 head_slop
= page
- allocation
;
759 tail_slop
= ((size_t) allocation
+ alloc_size
) & (G
.pagesize
- 1);
761 tail_slop
= alloc_size
- entry_size
- head_slop
;
762 enda
= allocation
+ alloc_size
- tail_slop
;
764 /* We allocated N pages, which are likely not aligned, leaving
765 us with N-1 usable pages. We plan to place the page_group
766 structure somewhere in the slop. */
767 if (head_slop
>= sizeof (page_group
))
768 group
= (page_group
*)page
- 1;
771 /* We magically got an aligned allocation. Too bad, we have
772 to waste a page anyway. */
776 tail_slop
+= G
.pagesize
;
778 if (tail_slop
< sizeof (page_group
))
780 group
= (page_group
*)enda
;
781 tail_slop
-= sizeof (page_group
);
784 /* Remember that we allocated this memory. */
785 group
->next
= G
.page_groups
;
786 group
->allocation
= allocation
;
787 group
->alloc_size
= alloc_size
;
789 G
.page_groups
= group
;
790 G
.bytes_mapped
+= alloc_size
;
792 /* If we allocated multiple pages, put the rest on the free list. */
795 struct page_entry
*e
, *f
= G
.free_pages
;
796 for (a
= enda
- G
.pagesize
; a
!= page
; a
-= G
.pagesize
)
798 e
= (struct page_entry
*) xcalloc (1, page_entry_size
);
800 e
->bytes
= G
.pagesize
;
812 entry
= (struct page_entry
*) xcalloc (1, page_entry_size
);
814 entry
->bytes
= entry_size
;
816 entry
->context_depth
= G
.context_depth
;
817 entry
->order
= order
;
818 entry
->num_free_objects
= num_objects
;
819 entry
->next_bit_hint
= 1;
821 G
.context_depth_allocations
|= (unsigned long)1 << G
.context_depth
;
823 #ifdef USING_MALLOC_PAGE_GROUPS
824 entry
->group
= group
;
825 set_page_group_in_use (group
, page
);
828 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
829 increment the hint. */
830 entry
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
831 = (unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
);
833 set_page_table_entry (page
, entry
);
835 if (GGC_DEBUG_LEVEL
>= 2)
836 fprintf (G
.debug_file
,
837 "Allocating page at %p, object size=%lu, data %p-%p\n",
838 (void *) entry
, (unsigned long) OBJECT_SIZE (order
), page
,
839 page
+ entry_size
- 1);
844 /* Adjust the size of G.depth so that no index greater than the one
845 used by the top of the G.by_depth is used. */
852 if (G
.by_depth_in_use
)
854 top
= G
.by_depth
[G
.by_depth_in_use
-1];
856 /* Peel back indicies in depth that index into by_depth, so that
857 as new elements are added to by_depth, we note the indicies
858 of those elements, if they are for new context depths. */
859 while (G
.depth_in_use
> (size_t)top
->context_depth
+1)
864 /* For a page that is no longer needed, put it on the free page list. */
867 free_page (page_entry
*entry
)
869 if (GGC_DEBUG_LEVEL
>= 2)
870 fprintf (G
.debug_file
,
871 "Deallocating page at %p, data %p-%p\n", (void *) entry
,
872 entry
->page
, entry
->page
+ entry
->bytes
- 1);
874 /* Mark the page as inaccessible. Discard the handle to avoid handle
876 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (entry
->page
, entry
->bytes
));
878 set_page_table_entry (entry
->page
, NULL
);
880 #ifdef USING_MALLOC_PAGE_GROUPS
881 clear_page_group_in_use (entry
->group
, entry
->page
);
884 if (G
.by_depth_in_use
> 1)
886 page_entry
*top
= G
.by_depth
[G
.by_depth_in_use
-1];
888 /* If they are at the same depth, put top element into freed
890 if (entry
->context_depth
== top
->context_depth
)
892 int i
= entry
->index_by_depth
;
894 G
.save_in_use
[i
] = G
.save_in_use
[G
.by_depth_in_use
-1];
895 top
->index_by_depth
= i
;
899 /* We cannot free a page from a context deeper than the
908 entry
->next
= G
.free_pages
;
909 G
.free_pages
= entry
;
912 /* Release the free page cache to the system. */
918 page_entry
*p
, *next
;
922 /* Gather up adjacent pages so they are unmapped together. */
933 while (p
&& p
->page
== start
+ len
)
942 G
.bytes_mapped
-= len
;
947 #ifdef USING_MALLOC_PAGE_GROUPS
951 /* Remove all pages from free page groups from the list. */
953 while ((p
= *pp
) != NULL
)
954 if (p
->group
->in_use
== 0)
962 /* Remove all free page groups, and release the storage. */
964 while ((g
= *gp
) != NULL
)
968 G
.bytes_mapped
-= g
->alloc_size
;
969 free (g
->allocation
);
976 /* This table provides a fast way to determine ceil(log_2(size)) for
977 allocation requests. The minimum allocation size is eight bytes. */
979 static unsigned char size_lookup
[257] =
981 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
982 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
983 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
984 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
985 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
986 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
987 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
988 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
989 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
990 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
991 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
992 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
993 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
994 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
995 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
996 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1000 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1003 ggc_alloc (size_t size
)
1005 unsigned order
, word
, bit
, object_offset
;
1006 struct page_entry
*entry
;
1010 order
= size_lookup
[size
];
1014 while (size
> OBJECT_SIZE (order
))
1018 /* If there are non-full pages for this size allocation, they are at
1019 the head of the list. */
1020 entry
= G
.pages
[order
];
1022 /* If there is no page for this object size, or all pages in this
1023 context are full, allocate a new page. */
1024 if (entry
== NULL
|| entry
->num_free_objects
== 0)
1026 struct page_entry
*new_entry
;
1027 new_entry
= alloc_page (order
);
1029 new_entry
->index_by_depth
= G
.by_depth_in_use
;
1030 push_by_depth (new_entry
, 0);
1032 /* We can skip context depths, if we do, make sure we go all the
1033 way to the new depth. */
1034 while (new_entry
->context_depth
>= G
.depth_in_use
)
1035 push_depth (G
.by_depth_in_use
-1);
1037 /* If this is the only entry, it's also the tail. */
1039 G
.page_tails
[order
] = new_entry
;
1041 /* Put new pages at the head of the page list. */
1042 new_entry
->next
= entry
;
1044 G
.pages
[order
] = new_entry
;
1046 /* For a new page, we know the word and bit positions (in the
1047 in_use bitmap) of the first available object -- they're zero. */
1048 new_entry
->next_bit_hint
= 1;
1055 /* First try to use the hint left from the previous allocation
1056 to locate a clear bit in the in-use bitmap. We've made sure
1057 that the one-past-the-end bit is always set, so if the hint
1058 has run over, this test will fail. */
1059 unsigned hint
= entry
->next_bit_hint
;
1060 word
= hint
/ HOST_BITS_PER_LONG
;
1061 bit
= hint
% HOST_BITS_PER_LONG
;
1063 /* If the hint didn't work, scan the bitmap from the beginning. */
1064 if ((entry
->in_use_p
[word
] >> bit
) & 1)
1067 while (~entry
->in_use_p
[word
] == 0)
1069 while ((entry
->in_use_p
[word
] >> bit
) & 1)
1071 hint
= word
* HOST_BITS_PER_LONG
+ bit
;
1074 /* Next time, try the next bit. */
1075 entry
->next_bit_hint
= hint
+ 1;
1077 object_offset
= hint
* OBJECT_SIZE (order
);
1080 /* Set the in-use bit. */
1081 entry
->in_use_p
[word
] |= ((unsigned long) 1 << bit
);
1083 /* Keep a running total of the number of free objects. If this page
1084 fills up, we may have to move it to the end of the list if the
1085 next page isn't full. If the next page is full, all subsequent
1086 pages are full, so there's no need to move it. */
1087 if (--entry
->num_free_objects
== 0
1088 && entry
->next
!= NULL
1089 && entry
->next
->num_free_objects
> 0)
1091 G
.pages
[order
] = entry
->next
;
1093 G
.page_tails
[order
]->next
= entry
;
1094 G
.page_tails
[order
] = entry
;
1097 /* Calculate the object's address. */
1098 result
= entry
->page
+ object_offset
;
1100 #ifdef ENABLE_GC_CHECKING
1101 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1102 exact same semantics in presence of memory bugs, regardless of
1103 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1104 handle to avoid handle leak. */
1105 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, OBJECT_SIZE (order
)));
1107 /* `Poison' the entire allocated object, including any padding at
1109 memset (result
, 0xaf, OBJECT_SIZE (order
));
1111 /* Make the bytes after the end of the object unaccessible. Discard the
1112 handle to avoid handle leak. */
1113 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) result
+ size
,
1114 OBJECT_SIZE (order
) - size
));
1117 /* Tell Valgrind that the memory is there, but its content isn't
1118 defined. The bytes at the end of the object are still marked
1120 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, size
));
1122 /* Keep track of how many bytes are being allocated. This
1123 information is used in deciding when to collect. */
1124 G
.allocated
+= OBJECT_SIZE (order
);
1126 if (GGC_DEBUG_LEVEL
>= 3)
1127 fprintf (G
.debug_file
,
1128 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1129 (unsigned long) size
, (unsigned long) OBJECT_SIZE (order
), result
,
1135 /* If P is not marked, marks it and return false. Otherwise return true.
1136 P must have been allocated by the GC allocator; it mustn't point to
1137 static objects, stack variables, or memory allocated with malloc. */
1140 ggc_set_mark (const void *p
)
1146 /* Look up the page on which the object is alloced. If the object
1147 wasn't allocated by the collector, we'll probably die. */
1148 entry
= lookup_page_table_entry (p
);
1149 #ifdef ENABLE_CHECKING
1154 /* Calculate the index of the object on the page; this is its bit
1155 position in the in_use_p bitmap. */
1156 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1157 word
= bit
/ HOST_BITS_PER_LONG
;
1158 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1160 /* If the bit was previously set, skip it. */
1161 if (entry
->in_use_p
[word
] & mask
)
1164 /* Otherwise set it, and decrement the free object count. */
1165 entry
->in_use_p
[word
] |= mask
;
1166 entry
->num_free_objects
-= 1;
1168 if (GGC_DEBUG_LEVEL
>= 4)
1169 fprintf (G
.debug_file
, "Marking %p\n", p
);
1174 /* Return 1 if P has been marked, zero otherwise.
1175 P must have been allocated by the GC allocator; it mustn't point to
1176 static objects, stack variables, or memory allocated with malloc. */
1179 ggc_marked_p (const void *p
)
1185 /* Look up the page on which the object is alloced. If the object
1186 wasn't allocated by the collector, we'll probably die. */
1187 entry
= lookup_page_table_entry (p
);
1188 #ifdef ENABLE_CHECKING
1193 /* Calculate the index of the object on the page; this is its bit
1194 position in the in_use_p bitmap. */
1195 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1196 word
= bit
/ HOST_BITS_PER_LONG
;
1197 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1199 return (entry
->in_use_p
[word
] & mask
) != 0;
1202 /* Return the size of the gc-able object P. */
1205 ggc_get_size (const void *p
)
1207 page_entry
*pe
= lookup_page_table_entry (p
);
1208 return OBJECT_SIZE (pe
->order
);
1211 /* Subroutine of init_ggc which computes the pair of numbers used to
1212 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1214 This algorithm is taken from Granlund and Montgomery's paper
1215 "Division by Invariant Integers using Multiplication"
1216 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1220 compute_inverse (unsigned order
)
1222 unsigned size
, inv
, e
;
1224 /* There can be only one object per "page" in a bucket for sizes
1225 larger than half a machine page; it will always have offset zero. */
1226 if (OBJECT_SIZE (order
) > G
.pagesize
/2)
1228 if (OBJECTS_PER_PAGE (order
) != 1)
1231 DIV_MULT (order
) = 1;
1232 DIV_SHIFT (order
) = 0;
1236 size
= OBJECT_SIZE (order
);
1238 while (size
% 2 == 0)
1245 while (inv
* size
!= 1)
1246 inv
= inv
* (2 - inv
*size
);
1248 DIV_MULT (order
) = inv
;
1249 DIV_SHIFT (order
) = e
;
1252 /* Initialize the ggc-mmap allocator. */
1258 G
.pagesize
= getpagesize();
1259 G
.lg_pagesize
= exact_log2 (G
.pagesize
);
1261 #ifdef HAVE_MMAP_DEV_ZERO
1262 G
.dev_zero_fd
= open ("/dev/zero", O_RDONLY
);
1263 if (G
.dev_zero_fd
== -1)
1264 internal_error ("open /dev/zero: %m");
1268 G
.debug_file
= fopen ("ggc-mmap.debug", "w");
1270 G
.debug_file
= stdout
;
1274 /* StunOS has an amazing off-by-one error for the first mmap allocation
1275 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1276 believe, is an unaligned page allocation, which would cause us to
1277 hork badly if we tried to use it. */
1279 char *p
= alloc_anon (NULL
, G
.pagesize
);
1280 struct page_entry
*e
;
1281 if ((size_t)p
& (G
.pagesize
- 1))
1283 /* How losing. Discard this one and try another. If we still
1284 can't get something useful, give up. */
1286 p
= alloc_anon (NULL
, G
.pagesize
);
1287 if ((size_t)p
& (G
.pagesize
- 1))
1291 /* We have a good page, might as well hold onto it... */
1292 e
= (struct page_entry
*) xcalloc (1, sizeof (struct page_entry
));
1293 e
->bytes
= G
.pagesize
;
1295 e
->next
= G
.free_pages
;
1300 /* Initialize the object size table. */
1301 for (order
= 0; order
< HOST_BITS_PER_PTR
; ++order
)
1302 object_size_table
[order
] = (size_t) 1 << order
;
1303 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1305 size_t s
= extra_order_size_table
[order
- HOST_BITS_PER_PTR
];
1307 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1308 so that we're sure of getting aligned memory. */
1309 s
= ROUND_UP (s
, MAX_ALIGNMENT
);
1310 object_size_table
[order
] = s
;
1313 /* Initialize the objects-per-page and inverse tables. */
1314 for (order
= 0; order
< NUM_ORDERS
; ++order
)
1316 objects_per_page_table
[order
] = G
.pagesize
/ OBJECT_SIZE (order
);
1317 if (objects_per_page_table
[order
] == 0)
1318 objects_per_page_table
[order
] = 1;
1319 compute_inverse (order
);
1322 /* Reset the size_lookup array to put appropriately sized objects in
1323 the special orders. All objects bigger than the previous power
1324 of two, but no greater than the special size, should go in the
1326 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1331 o
= size_lookup
[OBJECT_SIZE (order
)];
1332 for (i
= OBJECT_SIZE (order
); size_lookup
[i
] == o
; --i
)
1333 size_lookup
[i
] = order
;
1338 G
.depth
= (unsigned int *) xmalloc (G
.depth_max
* sizeof (unsigned int));
1340 G
.by_depth_in_use
= 0;
1341 G
.by_depth_max
= INITIAL_PTE_COUNT
;
1342 G
.by_depth
= (page_entry
**) xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
1343 G
.save_in_use
= (unsigned long **) xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
1346 /* Increment the `GC context'. Objects allocated in an outer context
1347 are never freed, eliminating the need to register their roots. */
1350 ggc_push_context (void)
1355 if (G
.context_depth
>= HOST_BITS_PER_LONG
)
1359 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1360 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1363 ggc_recalculate_in_use_p (page_entry
*p
)
1368 /* Because the past-the-end bit in in_use_p is always set, we
1369 pretend there is one additional object. */
1370 num_objects
= OBJECTS_IN_PAGE (p
) + 1;
1372 /* Reset the free object count. */
1373 p
->num_free_objects
= num_objects
;
1375 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1377 i
< CEIL (BITMAP_SIZE (num_objects
),
1378 sizeof (*p
->in_use_p
));
1383 /* Something is in use if it is marked, or if it was in use in a
1384 context further down the context stack. */
1385 p
->in_use_p
[i
] |= save_in_use_p (p
)[i
];
1387 /* Decrement the free object count for every object allocated. */
1388 for (j
= p
->in_use_p
[i
]; j
; j
>>= 1)
1389 p
->num_free_objects
-= (j
& 1);
1392 if (p
->num_free_objects
>= num_objects
)
1396 /* Decrement the `GC context'. All objects allocated since the
1397 previous ggc_push_context are migrated to the outer context. */
1400 ggc_pop_context (void)
1402 unsigned long omask
;
1403 unsigned int depth
, i
, e
;
1404 #ifdef ENABLE_CHECKING
1408 depth
= --G
.context_depth
;
1409 omask
= (unsigned long)1 << (depth
+ 1);
1411 if (!((G
.context_depth_allocations
| G
.context_depth_collections
) & omask
))
1414 G
.context_depth_allocations
|= (G
.context_depth_allocations
& omask
) >> 1;
1415 G
.context_depth_allocations
&= omask
- 1;
1416 G
.context_depth_collections
&= omask
- 1;
1418 /* The G.depth array is shortend so that the last index is the
1419 context_depth of the top element of by_depth. */
1420 if (depth
+1 < G
.depth_in_use
)
1421 e
= G
.depth
[depth
+1];
1423 e
= G
.by_depth_in_use
;
1425 /* We might not have any PTEs of depth depth. */
1426 if (depth
< G
.depth_in_use
)
1429 /* First we go through all the pages at depth depth to
1430 recalculate the in use bits. */
1431 for (i
= G
.depth
[depth
]; i
< e
; ++i
)
1435 #ifdef ENABLE_CHECKING
1438 /* Check that all of the pages really are at the depth that
1440 if (p
->context_depth
!= depth
)
1442 if (p
->index_by_depth
!= i
)
1446 prefetch (&save_in_use_p_i (i
+8));
1447 prefetch (&save_in_use_p_i (i
+16));
1448 if (save_in_use_p_i (i
))
1451 ggc_recalculate_in_use_p (p
);
1452 free (save_in_use_p_i (i
));
1453 save_in_use_p_i (i
) = 0;
1458 /* Then, we reset all page_entries with a depth greater than depth
1460 for (i
= e
; i
< G
.by_depth_in_use
; ++i
)
1462 page_entry
*p
= G
.by_depth
[i
];
1464 /* Check that all of the pages really are at the depth we
1466 #ifdef ENABLE_CHECKING
1467 if (p
->context_depth
<= depth
)
1469 if (p
->index_by_depth
!= i
)
1472 p
->context_depth
= depth
;
1477 #ifdef ENABLE_CHECKING
1478 for (order
= 2; order
< NUM_ORDERS
; order
++)
1482 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1484 if (p
->context_depth
> depth
)
1486 else if (p
->context_depth
== depth
&& save_in_use_p (p
))
1493 /* Unmark all objects. */
1500 for (order
= 2; order
< NUM_ORDERS
; order
++)
1504 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1506 size_t num_objects
= OBJECTS_IN_PAGE (p
);
1507 size_t bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
1509 #ifdef ENABLE_CHECKING
1510 /* The data should be page-aligned. */
1511 if ((size_t) p
->page
& (G
.pagesize
- 1))
1515 /* Pages that aren't in the topmost context are not collected;
1516 nevertheless, we need their in-use bit vectors to store GC
1517 marks. So, back them up first. */
1518 if (p
->context_depth
< G
.context_depth
)
1520 if (! save_in_use_p (p
))
1521 save_in_use_p (p
) = xmalloc (bitmap_size
);
1522 memcpy (save_in_use_p (p
), p
->in_use_p
, bitmap_size
);
1525 /* Reset reset the number of free objects and clear the
1526 in-use bits. These will be adjusted by mark_obj. */
1527 p
->num_free_objects
= num_objects
;
1528 memset (p
->in_use_p
, 0, bitmap_size
);
1530 /* Make sure the one-past-the-end bit is always set. */
1531 p
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
1532 = ((unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
));
1537 /* Free all empty pages. Partially empty pages need no attention
1538 because the `mark' bit doubles as an `unused' bit. */
1545 for (order
= 2; order
< NUM_ORDERS
; order
++)
1547 /* The last page-entry to consider, regardless of entries
1548 placed at the end of the list. */
1549 page_entry
* const last
= G
.page_tails
[order
];
1552 size_t live_objects
;
1553 page_entry
*p
, *previous
;
1563 page_entry
*next
= p
->next
;
1565 /* Loop until all entries have been examined. */
1568 num_objects
= OBJECTS_IN_PAGE (p
);
1570 /* Add all live objects on this page to the count of
1571 allocated memory. */
1572 live_objects
= num_objects
- p
->num_free_objects
;
1574 G
.allocated
+= OBJECT_SIZE (order
) * live_objects
;
1576 /* Only objects on pages in the topmost context should get
1578 if (p
->context_depth
< G
.context_depth
)
1581 /* Remove the page if it's empty. */
1582 else if (live_objects
== 0)
1585 G
.pages
[order
] = next
;
1587 previous
->next
= next
;
1589 /* Are we removing the last element? */
1590 if (p
== G
.page_tails
[order
])
1591 G
.page_tails
[order
] = previous
;
1596 /* If the page is full, move it to the end. */
1597 else if (p
->num_free_objects
== 0)
1599 /* Don't move it if it's already at the end. */
1600 if (p
!= G
.page_tails
[order
])
1602 /* Move p to the end of the list. */
1604 G
.page_tails
[order
]->next
= p
;
1606 /* Update the tail pointer... */
1607 G
.page_tails
[order
] = p
;
1609 /* ... and the head pointer, if necessary. */
1611 G
.pages
[order
] = next
;
1613 previous
->next
= next
;
1618 /* If we've fallen through to here, it's a page in the
1619 topmost context that is neither full nor empty. Such a
1620 page must precede pages at lesser context depth in the
1621 list, so move it to the head. */
1622 else if (p
!= G
.pages
[order
])
1624 previous
->next
= p
->next
;
1625 p
->next
= G
.pages
[order
];
1627 /* Are we moving the last element? */
1628 if (G
.page_tails
[order
] == p
)
1629 G
.page_tails
[order
] = previous
;
1638 /* Now, restore the in_use_p vectors for any pages from contexts
1639 other than the current one. */
1640 for (p
= G
.pages
[order
]; p
; p
= p
->next
)
1641 if (p
->context_depth
!= G
.context_depth
)
1642 ggc_recalculate_in_use_p (p
);
1646 #ifdef ENABLE_GC_CHECKING
1647 /* Clobber all free objects. */
1654 for (order
= 2; order
< NUM_ORDERS
; order
++)
1656 size_t size
= OBJECT_SIZE (order
);
1659 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1664 if (p
->context_depth
!= G
.context_depth
)
1665 /* Since we don't do any collection for pages in pushed
1666 contexts, there's no need to do any poisoning. And
1667 besides, the IN_USE_P array isn't valid until we pop
1671 num_objects
= OBJECTS_IN_PAGE (p
);
1672 for (i
= 0; i
< num_objects
; i
++)
1675 word
= i
/ HOST_BITS_PER_LONG
;
1676 bit
= i
% HOST_BITS_PER_LONG
;
1677 if (((p
->in_use_p
[word
] >> bit
) & 1) == 0)
1679 char *object
= p
->page
+ i
* size
;
1681 /* Keep poison-by-write when we expect to use Valgrind,
1682 so the exact same memory semantics is kept, in case
1683 there are memory errors. We override this request
1685 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (object
, size
));
1686 memset (object
, 0xa5, size
);
1688 /* Drop the handle to avoid handle leak. */
1689 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (object
, size
));
1697 /* Top level mark-and-sweep routine. */
1702 /* Avoid frequent unnecessary work by skipping collection if the
1703 total allocations haven't expanded much since the last
1705 float allocated_last_gc
=
1706 MAX (G
.allocated_last_gc
, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE
) * 1024);
1708 float min_expand
= allocated_last_gc
* PARAM_VALUE (GGC_MIN_EXPAND
) / 100;
1710 if (G
.allocated
< allocated_last_gc
+ min_expand
)
1713 timevar_push (TV_GC
);
1715 fprintf (stderr
, " {GC %luk -> ", (unsigned long) G
.allocated
/ 1024);
1717 /* Zero the total allocated bytes. This will be recalculated in the
1721 /* Release the pages we freed the last time we collected, but didn't
1722 reuse in the interim. */
1725 /* Indicate that we've seen collections at this context depth. */
1726 G
.context_depth_collections
= ((unsigned long)1 << (G
.context_depth
+ 1)) - 1;
1731 #ifdef ENABLE_GC_CHECKING
1737 G
.allocated_last_gc
= G
.allocated
;
1739 timevar_pop (TV_GC
);
1742 fprintf (stderr
, "%luk}", (unsigned long) G
.allocated
/ 1024);
1745 /* Print allocation statistics. */
1746 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
1748 : ((x) < 1024*1024*10 \
1750 : (x) / (1024*1024))))
1751 #define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
1754 ggc_print_statistics (void)
1756 struct ggc_statistics stats
;
1758 size_t total_overhead
= 0;
1760 /* Clear the statistics. */
1761 memset (&stats
, 0, sizeof (stats
));
1763 /* Make sure collection will really occur. */
1764 G
.allocated_last_gc
= 0;
1766 /* Collect and print the statistics common across collectors. */
1767 ggc_print_common_statistics (stderr
, &stats
);
1769 /* Release free pages so that we will not count the bytes allocated
1770 there as part of the total allocated memory. */
1773 /* Collect some information about the various sizes of
1775 fprintf (stderr
, "\n%-5s %10s %10s %10s\n",
1776 "Size", "Allocated", "Used", "Overhead");
1777 for (i
= 0; i
< NUM_ORDERS
; ++i
)
1784 /* Skip empty entries. */
1788 overhead
= allocated
= in_use
= 0;
1790 /* Figure out the total number of bytes allocated for objects of
1791 this size, and how many of them are actually in use. Also figure
1792 out how much memory the page table is using. */
1793 for (p
= G
.pages
[i
]; p
; p
= p
->next
)
1795 allocated
+= p
->bytes
;
1797 (OBJECTS_IN_PAGE (p
) - p
->num_free_objects
) * OBJECT_SIZE (i
);
1799 overhead
+= (sizeof (page_entry
) - sizeof (long)
1800 + BITMAP_SIZE (OBJECTS_IN_PAGE (p
) + 1));
1802 fprintf (stderr
, "%-5lu %10lu%c %10lu%c %10lu%c\n",
1803 (unsigned long) OBJECT_SIZE (i
),
1804 SCALE (allocated
), LABEL (allocated
),
1805 SCALE (in_use
), LABEL (in_use
),
1806 SCALE (overhead
), LABEL (overhead
));
1807 total_overhead
+= overhead
;
1809 fprintf (stderr
, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
1810 SCALE (G
.bytes_mapped
), LABEL (G
.bytes_mapped
),
1811 SCALE (G
.allocated
), LABEL(G
.allocated
),
1812 SCALE (total_overhead
), LABEL (total_overhead
));
1817 struct ggc_pch_ondisk
1819 unsigned totals
[NUM_ORDERS
];
1821 size_t base
[NUM_ORDERS
];
1822 size_t written
[NUM_ORDERS
];
1825 struct ggc_pch_data
*
1828 return xcalloc (sizeof (struct ggc_pch_data
), 1);
1832 ggc_pch_count_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
1838 order
= size_lookup
[size
];
1842 while (size
> OBJECT_SIZE (order
))
1846 d
->d
.totals
[order
]++;
1850 ggc_pch_total_size (struct ggc_pch_data
*d
)
1855 for (i
= 0; i
< NUM_ORDERS
; i
++)
1856 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
1861 ggc_pch_this_base (struct ggc_pch_data
*d
, void *base
)
1863 size_t a
= (size_t) base
;
1866 for (i
= 0; i
< NUM_ORDERS
; i
++)
1869 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
1875 ggc_pch_alloc_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
1882 order
= size_lookup
[size
];
1886 while (size
> OBJECT_SIZE (order
))
1890 result
= (char *) d
->base
[order
];
1891 d
->base
[order
] += OBJECT_SIZE (order
);
1896 ggc_pch_prepare_write (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
1897 FILE *f ATTRIBUTE_UNUSED
)
1899 /* Nothing to do. */
1903 ggc_pch_write_object (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
1904 FILE *f
, void *x
, void *newx ATTRIBUTE_UNUSED
,
1910 order
= size_lookup
[size
];
1914 while (size
> OBJECT_SIZE (order
))
1918 if (fwrite (x
, size
, 1, f
) != 1)
1919 fatal_error ("can't write PCH file: %m");
1921 /* In the current implementation, SIZE is always equal to
1922 OBJECT_SIZE (order) and so the fseek is never executed. */
1923 if (size
!= OBJECT_SIZE (order
)
1924 && fseek (f
, OBJECT_SIZE (order
) - size
, SEEK_CUR
) != 0)
1925 fatal_error ("can't write PCH file: %m");
1927 d
->written
[order
]++;
1928 if (d
->written
[order
] == d
->d
.totals
[order
]
1929 && fseek (f
, ROUND_UP_VALUE (d
->d
.totals
[order
] * OBJECT_SIZE (order
),
1932 fatal_error ("can't write PCH file: %m");
1936 ggc_pch_finish (struct ggc_pch_data
*d
, FILE *f
)
1938 if (fwrite (&d
->d
, sizeof (d
->d
), 1, f
) != 1)
1939 fatal_error ("can't write PCH file: %m");
1943 /* Move the PCH PTE entries just added to the end of by_depth, to the
1947 move_ptes_to_front (int count_old_page_tables
, int count_new_page_tables
)
1951 /* First, we swap the new entries to the front of the varrays. */
1952 page_entry
**new_by_depth
;
1953 unsigned long **new_save_in_use
;
1955 new_by_depth
= (page_entry
**) xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
1956 new_save_in_use
= (unsigned long **) xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
1958 memcpy (&new_by_depth
[0],
1959 &G
.by_depth
[count_old_page_tables
],
1960 count_new_page_tables
* sizeof (void *));
1961 memcpy (&new_by_depth
[count_new_page_tables
],
1963 count_old_page_tables
* sizeof (void *));
1964 memcpy (&new_save_in_use
[0],
1965 &G
.save_in_use
[count_old_page_tables
],
1966 count_new_page_tables
* sizeof (void *));
1967 memcpy (&new_save_in_use
[count_new_page_tables
],
1969 count_old_page_tables
* sizeof (void *));
1972 free (G
.save_in_use
);
1974 G
.by_depth
= new_by_depth
;
1975 G
.save_in_use
= new_save_in_use
;
1977 /* Now update all the index_by_depth fields. */
1978 for (i
= G
.by_depth_in_use
; i
> 0; --i
)
1980 page_entry
*p
= G
.by_depth
[i
-1];
1981 p
->index_by_depth
= i
-1;
1984 /* And last, we update the depth pointers in G.depth. The first
1985 entry is already 0, and context 0 entries always start at index
1986 0, so there is nothing to update in the first slot. We need a
1987 second slot, only if we have old ptes, and if we do, they start
1988 at index count_new_page_tables. */
1989 if (count_old_page_tables
)
1990 push_depth (count_new_page_tables
);
1994 ggc_pch_read (FILE *f
, void *addr
)
1996 struct ggc_pch_ondisk d
;
1999 unsigned long count_old_page_tables
;
2000 unsigned long count_new_page_tables
;
2002 count_old_page_tables
= G
.by_depth_in_use
;
2004 /* We've just read in a PCH file. So, every object that used to be
2005 allocated is now free. */
2011 /* No object read from a PCH file should ever be freed. So, set the
2012 context depth to 1, and set the depth of all the currently-allocated
2013 pages to be 1 too. PCH pages will have depth 0. */
2014 if (G
.context_depth
!= 0)
2016 G
.context_depth
= 1;
2017 for (i
= 0; i
< NUM_ORDERS
; i
++)
2020 for (p
= G
.pages
[i
]; p
!= NULL
; p
= p
->next
)
2021 p
->context_depth
= G
.context_depth
;
2024 /* Allocate the appropriate page-table entries for the pages read from
2026 if (fread (&d
, sizeof (d
), 1, f
) != 1)
2027 fatal_error ("can't read PCH file: %m");
2029 for (i
= 0; i
< NUM_ORDERS
; i
++)
2031 struct page_entry
*entry
;
2037 if (d
.totals
[i
] == 0)
2040 bytes
= ROUND_UP (d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2041 num_objs
= bytes
/ OBJECT_SIZE (i
);
2042 entry
= xcalloc (1, (sizeof (struct page_entry
)
2044 + BITMAP_SIZE (num_objs
+ 1)));
2045 entry
->bytes
= bytes
;
2047 entry
->context_depth
= 0;
2049 entry
->num_free_objects
= 0;
2053 j
+ HOST_BITS_PER_LONG
<= num_objs
+ 1;
2054 j
+= HOST_BITS_PER_LONG
)
2055 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
] = -1;
2056 for (; j
< num_objs
+ 1; j
++)
2057 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
]
2058 |= 1L << (j
% HOST_BITS_PER_LONG
);
2060 for (pte
= entry
->page
;
2061 pte
< entry
->page
+ entry
->bytes
;
2063 set_page_table_entry (pte
, entry
);
2065 if (G
.page_tails
[i
] != NULL
)
2066 G
.page_tails
[i
]->next
= entry
;
2069 G
.page_tails
[i
] = entry
;
2071 /* We start off by just adding all the new information to the
2072 end of the varrays, later, we will move the new information
2073 to the front of the varrays, as the PCH page tables are at
2075 push_by_depth (entry
, 0);
2078 /* Now, we update the various data structures that speed page table
2080 count_new_page_tables
= G
.by_depth_in_use
- count_old_page_tables
;
2082 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
);
2084 /* Update the statistics. */
2085 G
.allocated
= G
.allocated_last_gc
= offs
- (char *)addr
;