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 /* The Ith entry is the maximum size of an object to be stored in the
177 Ith extra order. Adding a new entry to this array is the *only*
178 thing you need to do to add a new special allocation size. */
180 static const size_t extra_order_size_table
[] = {
181 sizeof (struct tree_decl
),
182 sizeof (struct tree_list
),
183 RTL_SIZE (2), /* REG, MEM, PLUS, etc. */
184 RTL_SIZE (10), /* INSN, CALL_INSN, JUMP_INSN */
187 /* The total number of orders. */
189 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
191 /* We use this structure to determine the alignment required for
192 allocations. For power-of-two sized allocations, that's not a
193 problem, but it does matter for odd-sized allocations. */
195 struct max_alignment
{
199 #ifdef HAVE_LONG_DOUBLE
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
PARAMS ((const void *));
420 static page_entry
*lookup_page_table_entry
PARAMS ((const void *));
421 static void set_page_table_entry
PARAMS ((void *, page_entry
*));
423 static char *alloc_anon
PARAMS ((char *, size_t));
425 #ifdef USING_MALLOC_PAGE_GROUPS
426 static size_t page_group_index
PARAMS ((char *, char *));
427 static void set_page_group_in_use
PARAMS ((page_group
*, char *));
428 static void clear_page_group_in_use
PARAMS ((page_group
*, char *));
430 static struct page_entry
* alloc_page
PARAMS ((unsigned));
431 static void free_page
PARAMS ((struct page_entry
*));
432 static void release_pages
PARAMS ((void));
433 static void clear_marks
PARAMS ((void));
434 static void sweep_pages
PARAMS ((void));
435 static void ggc_recalculate_in_use_p
PARAMS ((page_entry
*));
436 static void compute_inverse
PARAMS ((unsigned));
437 static inline void adjust_depth
PARAMS ((void));
438 static void move_ptes_to_front
PARAMS ((int, int));
440 #ifdef ENABLE_GC_CHECKING
441 static void poison_pages
PARAMS ((void));
444 void debug_print_page_list
PARAMS ((int));
445 static void push_depth
PARAMS ((unsigned int));
446 static void push_by_depth
PARAMS ((page_entry
*, unsigned long *));
448 /* Push an entry onto G.depth. */
454 if (G
.depth_in_use
>= G
.depth_max
)
457 G
.depth
= (unsigned int *) xrealloc ((char *) G
.depth
,
458 G
.depth_max
* sizeof (unsigned int));
460 G
.depth
[G
.depth_in_use
++] = i
;
463 /* Push an entry onto G.by_depth and G.save_in_use. */
470 if (G
.by_depth_in_use
>= G
.by_depth_max
)
473 G
.by_depth
= (page_entry
**) xrealloc ((char *) G
.by_depth
,
474 G
.by_depth_max
* sizeof (page_entry
*));
475 G
.save_in_use
= (unsigned long **) xrealloc ((char *) G
.save_in_use
,
476 G
.by_depth_max
* sizeof (unsigned long *));
478 G
.by_depth
[G
.by_depth_in_use
] = p
;
479 G
.save_in_use
[G
.by_depth_in_use
++] = s
;
482 #if (GCC_VERSION < 3001)
483 #define prefetch(X) ((void) X)
485 #define prefetch(X) __builtin_prefetch (X)
488 #define save_in_use_p_i(__i) \
490 #define save_in_use_p(__p) \
491 (save_in_use_p_i (__p->index_by_depth))
493 /* Returns nonzero if P was allocated in GC'able memory. */
502 #if HOST_BITS_PER_PTR <= 32
505 page_table table
= G
.lookup
;
506 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
511 if (table
->high_bits
== high_bits
)
515 base
= &table
->table
[0];
518 /* Extract the level 1 and 2 indices. */
522 return base
[L1
] && base
[L1
][L2
];
525 /* Traverse the page table and find the entry for a page.
526 Die (probably) if the object wasn't allocated via GC. */
528 static inline page_entry
*
529 lookup_page_table_entry(p
)
535 #if HOST_BITS_PER_PTR <= 32
538 page_table table
= G
.lookup
;
539 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
540 while (table
->high_bits
!= high_bits
)
542 base
= &table
->table
[0];
545 /* Extract the level 1 and 2 indices. */
552 /* Set the page table entry for a page. */
555 set_page_table_entry(p
, entry
)
562 #if HOST_BITS_PER_PTR <= 32
566 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
567 for (table
= G
.lookup
; table
; table
= table
->next
)
568 if (table
->high_bits
== high_bits
)
571 /* Not found -- allocate a new table. */
572 table
= (page_table
) xcalloc (1, sizeof(*table
));
573 table
->next
= G
.lookup
;
574 table
->high_bits
= high_bits
;
577 base
= &table
->table
[0];
580 /* Extract the level 1 and 2 indices. */
584 if (base
[L1
] == NULL
)
585 base
[L1
] = (page_entry
**) xcalloc (PAGE_L2_SIZE
, sizeof (page_entry
*));
587 base
[L1
][L2
] = entry
;
590 /* Prints the page-entry for object size ORDER, for debugging. */
593 debug_print_page_list (order
)
597 printf ("Head=%p, Tail=%p:\n", (PTR
) G
.pages
[order
],
598 (PTR
) G
.page_tails
[order
]);
602 printf ("%p(%1d|%3d) -> ", (PTR
) p
, p
->context_depth
,
603 p
->num_free_objects
);
611 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
612 (if non-null). The ifdef structure here is intended to cause a
613 compile error unless exactly one of the HAVE_* is defined. */
616 alloc_anon (pref
, size
)
617 char *pref ATTRIBUTE_UNUSED
;
620 #ifdef HAVE_MMAP_ANON
621 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
622 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
624 #ifdef HAVE_MMAP_DEV_ZERO
625 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
626 MAP_PRIVATE
, G
.dev_zero_fd
, 0);
629 if (page
== (char *) MAP_FAILED
)
631 perror ("virtual memory exhausted");
632 exit (FATAL_EXIT_CODE
);
635 /* Remember that we allocated this memory. */
636 G
.bytes_mapped
+= size
;
638 /* Pretend we don't have access to the allocated pages. We'll enable
639 access to smaller pieces of the area in ggc_alloc. Discard the
640 handle to avoid handle leak. */
641 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (page
, size
));
646 #ifdef USING_MALLOC_PAGE_GROUPS
647 /* Compute the index for this page into the page group. */
650 page_group_index (allocation
, page
)
651 char *allocation
, *page
;
653 return (size_t) (page
- allocation
) >> G
.lg_pagesize
;
656 /* Set and clear the in_use bit for this page in the page group. */
659 set_page_group_in_use (group
, page
)
663 group
->in_use
|= 1 << page_group_index (group
->allocation
, page
);
667 clear_page_group_in_use (group
, page
)
671 group
->in_use
&= ~(1 << page_group_index (group
->allocation
, page
));
675 /* Allocate a new page for allocating objects of size 2^ORDER,
676 and return an entry for it. The entry is not added to the
677 appropriate page_table list. */
679 static inline struct page_entry
*
683 struct page_entry
*entry
, *p
, **pp
;
687 size_t page_entry_size
;
689 #ifdef USING_MALLOC_PAGE_GROUPS
693 num_objects
= OBJECTS_PER_PAGE (order
);
694 bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
695 page_entry_size
= sizeof (page_entry
) - sizeof (long) + bitmap_size
;
696 entry_size
= num_objects
* OBJECT_SIZE (order
);
697 if (entry_size
< G
.pagesize
)
698 entry_size
= G
.pagesize
;
703 /* Check the list of free pages for one we can use. */
704 for (pp
= &G
.free_pages
, p
= *pp
; p
; pp
= &p
->next
, p
= *pp
)
705 if (p
->bytes
== entry_size
)
710 /* Recycle the allocated memory from this page ... */
714 #ifdef USING_MALLOC_PAGE_GROUPS
718 /* ... and, if possible, the page entry itself. */
719 if (p
->order
== order
)
722 memset (entry
, 0, page_entry_size
);
728 else if (entry_size
== G
.pagesize
)
730 /* We want just one page. Allocate a bunch of them and put the
731 extras on the freelist. (Can only do this optimization with
732 mmap for backing store.) */
733 struct page_entry
*e
, *f
= G
.free_pages
;
736 page
= alloc_anon (NULL
, G
.pagesize
* GGC_QUIRE_SIZE
);
738 /* This loop counts down so that the chain will be in ascending
740 for (i
= GGC_QUIRE_SIZE
- 1; i
>= 1; i
--)
742 e
= (struct page_entry
*) xcalloc (1, page_entry_size
);
744 e
->bytes
= G
.pagesize
;
745 e
->page
= page
+ (i
<< G
.lg_pagesize
);
753 page
= alloc_anon (NULL
, entry_size
);
755 #ifdef USING_MALLOC_PAGE_GROUPS
758 /* Allocate a large block of memory and serve out the aligned
759 pages therein. This results in much less memory wastage
760 than the traditional implementation of valloc. */
762 char *allocation
, *a
, *enda
;
763 size_t alloc_size
, head_slop
, tail_slop
;
764 int multiple_pages
= (entry_size
== G
.pagesize
);
767 alloc_size
= GGC_QUIRE_SIZE
* G
.pagesize
;
769 alloc_size
= entry_size
+ G
.pagesize
- 1;
770 allocation
= xmalloc (alloc_size
);
772 page
= (char *) (((size_t) allocation
+ G
.pagesize
- 1) & -G
.pagesize
);
773 head_slop
= page
- allocation
;
775 tail_slop
= ((size_t) allocation
+ alloc_size
) & (G
.pagesize
- 1);
777 tail_slop
= alloc_size
- entry_size
- head_slop
;
778 enda
= allocation
+ alloc_size
- tail_slop
;
780 /* We allocated N pages, which are likely not aligned, leaving
781 us with N-1 usable pages. We plan to place the page_group
782 structure somewhere in the slop. */
783 if (head_slop
>= sizeof (page_group
))
784 group
= (page_group
*)page
- 1;
787 /* We magically got an aligned allocation. Too bad, we have
788 to waste a page anyway. */
792 tail_slop
+= G
.pagesize
;
794 if (tail_slop
< sizeof (page_group
))
796 group
= (page_group
*)enda
;
797 tail_slop
-= sizeof (page_group
);
800 /* Remember that we allocated this memory. */
801 group
->next
= G
.page_groups
;
802 group
->allocation
= allocation
;
803 group
->alloc_size
= alloc_size
;
805 G
.page_groups
= group
;
806 G
.bytes_mapped
+= alloc_size
;
808 /* If we allocated multiple pages, put the rest on the free list. */
811 struct page_entry
*e
, *f
= G
.free_pages
;
812 for (a
= enda
- G
.pagesize
; a
!= page
; a
-= G
.pagesize
)
814 e
= (struct page_entry
*) xcalloc (1, page_entry_size
);
816 e
->bytes
= G
.pagesize
;
828 entry
= (struct page_entry
*) xcalloc (1, page_entry_size
);
830 entry
->bytes
= entry_size
;
832 entry
->context_depth
= G
.context_depth
;
833 entry
->order
= order
;
834 entry
->num_free_objects
= num_objects
;
835 entry
->next_bit_hint
= 1;
837 G
.context_depth_allocations
|= (unsigned long)1 << G
.context_depth
;
839 #ifdef USING_MALLOC_PAGE_GROUPS
840 entry
->group
= group
;
841 set_page_group_in_use (group
, page
);
844 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
845 increment the hint. */
846 entry
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
847 = (unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
);
849 set_page_table_entry (page
, entry
);
851 if (GGC_DEBUG_LEVEL
>= 2)
852 fprintf (G
.debug_file
,
853 "Allocating page at %p, object size=%lu, data %p-%p\n",
854 (PTR
) entry
, (unsigned long) OBJECT_SIZE (order
), page
,
855 page
+ entry_size
- 1);
860 /* Adjust the size of G.depth so that no index greater than the one
861 used by the top of the G.by_depth is used. */
868 if (G
.by_depth_in_use
)
870 top
= G
.by_depth
[G
.by_depth_in_use
-1];
872 /* Peel back indicies in depth that index into by_depth, so that
873 as new elements are added to by_depth, we note the indicies
874 of those elements, if they are for new context depths. */
875 while (G
.depth_in_use
> (size_t)top
->context_depth
+1)
880 /* For a page that is no longer needed, put it on the free page list. */
886 if (GGC_DEBUG_LEVEL
>= 2)
887 fprintf (G
.debug_file
,
888 "Deallocating page at %p, data %p-%p\n", (PTR
) entry
,
889 entry
->page
, entry
->page
+ entry
->bytes
- 1);
891 /* Mark the page as inaccessible. Discard the handle to avoid handle
893 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (entry
->page
, entry
->bytes
));
895 set_page_table_entry (entry
->page
, NULL
);
897 #ifdef USING_MALLOC_PAGE_GROUPS
898 clear_page_group_in_use (entry
->group
, entry
->page
);
901 if (G
.by_depth_in_use
> 1)
903 page_entry
*top
= G
.by_depth
[G
.by_depth_in_use
-1];
905 /* If they are at the same depth, put top element into freed
907 if (entry
->context_depth
== top
->context_depth
)
909 int i
= entry
->index_by_depth
;
911 G
.save_in_use
[i
] = G
.save_in_use
[G
.by_depth_in_use
-1];
912 top
->index_by_depth
= i
;
916 /* We cannot free a page from a context deeper than the
925 entry
->next
= G
.free_pages
;
926 G
.free_pages
= entry
;
929 /* Release the free page cache to the system. */
935 page_entry
*p
, *next
;
939 /* Gather up adjacent pages so they are unmapped together. */
950 while (p
&& p
->page
== start
+ len
)
959 G
.bytes_mapped
-= len
;
964 #ifdef USING_MALLOC_PAGE_GROUPS
968 /* Remove all pages from free page groups from the list. */
970 while ((p
= *pp
) != NULL
)
971 if (p
->group
->in_use
== 0)
979 /* Remove all free page groups, and release the storage. */
981 while ((g
= *gp
) != NULL
)
985 G
.bytes_mapped
-= g
->alloc_size
;
986 free (g
->allocation
);
993 /* This table provides a fast way to determine ceil(log_2(size)) for
994 allocation requests. The minimum allocation size is eight bytes. */
996 static unsigned char size_lookup
[257] =
998 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
999 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1000 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1001 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1002 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1003 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1004 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1005 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1006 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1007 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1008 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1009 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1010 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1011 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1012 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1013 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1017 /* Allocate a chunk of memory of SIZE bytes. If ZERO is nonzero, the
1018 memory is zeroed; otherwise, its contents are undefined. */
1024 unsigned order
, word
, bit
, object_offset
;
1025 struct page_entry
*entry
;
1029 order
= size_lookup
[size
];
1033 while (size
> OBJECT_SIZE (order
))
1037 /* If there are non-full pages for this size allocation, they are at
1038 the head of the list. */
1039 entry
= G
.pages
[order
];
1041 /* If there is no page for this object size, or all pages in this
1042 context are full, allocate a new page. */
1043 if (entry
== NULL
|| entry
->num_free_objects
== 0)
1045 struct page_entry
*new_entry
;
1046 new_entry
= alloc_page (order
);
1048 new_entry
->index_by_depth
= G
.by_depth_in_use
;
1049 push_by_depth (new_entry
, 0);
1051 /* We can skip context depths, if we do, make sure we go all the
1052 way to the new depth. */
1053 while (new_entry
->context_depth
>= G
.depth_in_use
)
1054 push_depth (G
.by_depth_in_use
-1);
1056 /* If this is the only entry, it's also the tail. */
1058 G
.page_tails
[order
] = new_entry
;
1060 /* Put new pages at the head of the page list. */
1061 new_entry
->next
= entry
;
1063 G
.pages
[order
] = new_entry
;
1065 /* For a new page, we know the word and bit positions (in the
1066 in_use bitmap) of the first available object -- they're zero. */
1067 new_entry
->next_bit_hint
= 1;
1074 /* First try to use the hint left from the previous allocation
1075 to locate a clear bit in the in-use bitmap. We've made sure
1076 that the one-past-the-end bit is always set, so if the hint
1077 has run over, this test will fail. */
1078 unsigned hint
= entry
->next_bit_hint
;
1079 word
= hint
/ HOST_BITS_PER_LONG
;
1080 bit
= hint
% HOST_BITS_PER_LONG
;
1082 /* If the hint didn't work, scan the bitmap from the beginning. */
1083 if ((entry
->in_use_p
[word
] >> bit
) & 1)
1086 while (~entry
->in_use_p
[word
] == 0)
1088 while ((entry
->in_use_p
[word
] >> bit
) & 1)
1090 hint
= word
* HOST_BITS_PER_LONG
+ bit
;
1093 /* Next time, try the next bit. */
1094 entry
->next_bit_hint
= hint
+ 1;
1096 object_offset
= hint
* OBJECT_SIZE (order
);
1099 /* Set the in-use bit. */
1100 entry
->in_use_p
[word
] |= ((unsigned long) 1 << bit
);
1102 /* Keep a running total of the number of free objects. If this page
1103 fills up, we may have to move it to the end of the list if the
1104 next page isn't full. If the next page is full, all subsequent
1105 pages are full, so there's no need to move it. */
1106 if (--entry
->num_free_objects
== 0
1107 && entry
->next
!= NULL
1108 && entry
->next
->num_free_objects
> 0)
1110 G
.pages
[order
] = entry
->next
;
1112 G
.page_tails
[order
]->next
= entry
;
1113 G
.page_tails
[order
] = entry
;
1116 /* Calculate the object's address. */
1117 result
= entry
->page
+ object_offset
;
1119 #ifdef ENABLE_GC_CHECKING
1120 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1121 exact same semantics in presence of memory bugs, regardless of
1122 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1123 handle to avoid handle leak. */
1124 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, OBJECT_SIZE (order
)));
1126 /* `Poison' the entire allocated object, including any padding at
1128 memset (result
, 0xaf, OBJECT_SIZE (order
));
1130 /* Make the bytes after the end of the object unaccessible. Discard the
1131 handle to avoid handle leak. */
1132 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) result
+ size
,
1133 OBJECT_SIZE (order
) - size
));
1136 /* Tell Valgrind that the memory is there, but its content isn't
1137 defined. The bytes at the end of the object are still marked
1139 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, size
));
1141 /* Keep track of how many bytes are being allocated. This
1142 information is used in deciding when to collect. */
1143 G
.allocated
+= OBJECT_SIZE (order
);
1145 if (GGC_DEBUG_LEVEL
>= 3)
1146 fprintf (G
.debug_file
,
1147 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1148 (unsigned long) size
, (unsigned long) OBJECT_SIZE (order
), result
,
1154 /* If P is not marked, marks it and return false. Otherwise return true.
1155 P must have been allocated by the GC allocator; it mustn't point to
1156 static objects, stack variables, or memory allocated with malloc. */
1166 /* Look up the page on which the object is alloced. If the object
1167 wasn't allocated by the collector, we'll probably die. */
1168 entry
= lookup_page_table_entry (p
);
1169 #ifdef ENABLE_CHECKING
1174 /* Calculate the index of the object on the page; this is its bit
1175 position in the in_use_p bitmap. */
1176 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1177 word
= bit
/ HOST_BITS_PER_LONG
;
1178 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1180 /* If the bit was previously set, skip it. */
1181 if (entry
->in_use_p
[word
] & mask
)
1184 /* Otherwise set it, and decrement the free object count. */
1185 entry
->in_use_p
[word
] |= mask
;
1186 entry
->num_free_objects
-= 1;
1188 if (GGC_DEBUG_LEVEL
>= 4)
1189 fprintf (G
.debug_file
, "Marking %p\n", p
);
1194 /* Return 1 if P has been marked, zero otherwise.
1195 P must have been allocated by the GC allocator; it mustn't point to
1196 static objects, stack variables, or memory allocated with malloc. */
1206 /* Look up the page on which the object is alloced. If the object
1207 wasn't allocated by the collector, we'll probably die. */
1208 entry
= lookup_page_table_entry (p
);
1209 #ifdef ENABLE_CHECKING
1214 /* Calculate the index of the object on the page; this is its bit
1215 position in the in_use_p bitmap. */
1216 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1217 word
= bit
/ HOST_BITS_PER_LONG
;
1218 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1220 return (entry
->in_use_p
[word
] & mask
) != 0;
1223 /* Return the size of the gc-able object P. */
1229 page_entry
*pe
= lookup_page_table_entry (p
);
1230 return OBJECT_SIZE (pe
->order
);
1233 /* Subroutine of init_ggc which computes the pair of numbers used to
1234 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1236 This algorithm is taken from Granlund and Montgomery's paper
1237 "Division by Invariant Integers using Multiplication"
1238 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1242 compute_inverse (order
)
1245 unsigned size
, inv
, e
;
1247 /* There can be only one object per "page" in a bucket for sizes
1248 larger than half a machine page; it will always have offset zero. */
1249 if (OBJECT_SIZE (order
) > G
.pagesize
/2)
1251 if (OBJECTS_PER_PAGE (order
) != 1)
1254 DIV_MULT (order
) = 1;
1255 DIV_SHIFT (order
) = 0;
1259 size
= OBJECT_SIZE (order
);
1261 while (size
% 2 == 0)
1268 while (inv
* size
!= 1)
1269 inv
= inv
* (2 - inv
*size
);
1271 DIV_MULT (order
) = inv
;
1272 DIV_SHIFT (order
) = e
;
1275 /* Initialize the ggc-mmap allocator. */
1281 G
.pagesize
= getpagesize();
1282 G
.lg_pagesize
= exact_log2 (G
.pagesize
);
1284 #ifdef HAVE_MMAP_DEV_ZERO
1285 G
.dev_zero_fd
= open ("/dev/zero", O_RDONLY
);
1286 if (G
.dev_zero_fd
== -1)
1291 G
.debug_file
= fopen ("ggc-mmap.debug", "w");
1293 G
.debug_file
= stdout
;
1297 /* StunOS has an amazing off-by-one error for the first mmap allocation
1298 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1299 believe, is an unaligned page allocation, which would cause us to
1300 hork badly if we tried to use it. */
1302 char *p
= alloc_anon (NULL
, G
.pagesize
);
1303 struct page_entry
*e
;
1304 if ((size_t)p
& (G
.pagesize
- 1))
1306 /* How losing. Discard this one and try another. If we still
1307 can't get something useful, give up. */
1309 p
= alloc_anon (NULL
, G
.pagesize
);
1310 if ((size_t)p
& (G
.pagesize
- 1))
1314 /* We have a good page, might as well hold onto it... */
1315 e
= (struct page_entry
*) xcalloc (1, sizeof (struct page_entry
));
1316 e
->bytes
= G
.pagesize
;
1318 e
->next
= G
.free_pages
;
1323 /* Initialize the object size table. */
1324 for (order
= 0; order
< HOST_BITS_PER_PTR
; ++order
)
1325 object_size_table
[order
] = (size_t) 1 << order
;
1326 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1328 size_t s
= extra_order_size_table
[order
- HOST_BITS_PER_PTR
];
1330 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1331 so that we're sure of getting aligned memory. */
1332 s
= ROUND_UP (s
, MAX_ALIGNMENT
);
1333 object_size_table
[order
] = s
;
1336 /* Initialize the objects-per-page and inverse tables. */
1337 for (order
= 0; order
< NUM_ORDERS
; ++order
)
1339 objects_per_page_table
[order
] = G
.pagesize
/ OBJECT_SIZE (order
);
1340 if (objects_per_page_table
[order
] == 0)
1341 objects_per_page_table
[order
] = 1;
1342 compute_inverse (order
);
1345 /* Reset the size_lookup array to put appropriately sized objects in
1346 the special orders. All objects bigger than the previous power
1347 of two, but no greater than the special size, should go in the
1349 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1354 o
= size_lookup
[OBJECT_SIZE (order
)];
1355 for (i
= OBJECT_SIZE (order
); size_lookup
[i
] == o
; --i
)
1356 size_lookup
[i
] = order
;
1361 G
.depth
= (unsigned int *) xmalloc (G
.depth_max
* sizeof (unsigned int));
1363 G
.by_depth_in_use
= 0;
1364 G
.by_depth_max
= INITIAL_PTE_COUNT
;
1365 G
.by_depth
= (page_entry
**) xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
1366 G
.save_in_use
= (unsigned long **) xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
1369 /* Increment the `GC context'. Objects allocated in an outer context
1370 are never freed, eliminating the need to register their roots. */
1378 if (G
.context_depth
>= HOST_BITS_PER_LONG
)
1382 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1383 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1386 ggc_recalculate_in_use_p (p
)
1392 /* Because the past-the-end bit in in_use_p is always set, we
1393 pretend there is one additional object. */
1394 num_objects
= OBJECTS_IN_PAGE (p
) + 1;
1396 /* Reset the free object count. */
1397 p
->num_free_objects
= num_objects
;
1399 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1401 i
< CEIL (BITMAP_SIZE (num_objects
),
1402 sizeof (*p
->in_use_p
));
1407 /* Something is in use if it is marked, or if it was in use in a
1408 context further down the context stack. */
1409 p
->in_use_p
[i
] |= save_in_use_p (p
)[i
];
1411 /* Decrement the free object count for every object allocated. */
1412 for (j
= p
->in_use_p
[i
]; j
; j
>>= 1)
1413 p
->num_free_objects
-= (j
& 1);
1416 if (p
->num_free_objects
>= num_objects
)
1420 /* Decrement the `GC context'. All objects allocated since the
1421 previous ggc_push_context are migrated to the outer context. */
1426 unsigned long omask
;
1427 unsigned int depth
, i
, e
;
1428 #ifdef ENABLE_CHECKING
1432 depth
= --G
.context_depth
;
1433 omask
= (unsigned long)1 << (depth
+ 1);
1435 if (!((G
.context_depth_allocations
| G
.context_depth_collections
) & omask
))
1438 G
.context_depth_allocations
|= (G
.context_depth_allocations
& omask
) >> 1;
1439 G
.context_depth_allocations
&= omask
- 1;
1440 G
.context_depth_collections
&= omask
- 1;
1442 /* The G.depth array is shortend so that the last index is the
1443 context_depth of the top element of by_depth. */
1444 if (depth
+1 < G
.depth_in_use
)
1445 e
= G
.depth
[depth
+1];
1447 e
= G
.by_depth_in_use
;
1449 /* We might not have any PTEs of depth depth. */
1450 if (depth
< G
.depth_in_use
)
1453 /* First we go through all the pages at depth depth to
1454 recalculate the in use bits. */
1455 for (i
= G
.depth
[depth
]; i
< e
; ++i
)
1459 #ifdef ENABLE_CHECKING
1462 /* Check that all of the pages really are at the depth that
1464 if (p
->context_depth
!= depth
)
1466 if (p
->index_by_depth
!= i
)
1470 prefetch (&save_in_use_p_i (i
+8));
1471 prefetch (&save_in_use_p_i (i
+16));
1472 if (save_in_use_p_i (i
))
1475 ggc_recalculate_in_use_p (p
);
1476 free (save_in_use_p_i (i
));
1477 save_in_use_p_i (i
) = 0;
1482 /* Then, we reset all page_entries with a depth greater than depth
1484 for (i
= e
; i
< G
.by_depth_in_use
; ++i
)
1486 page_entry
*p
= G
.by_depth
[i
];
1488 /* Check that all of the pages really are at the depth we
1490 #ifdef ENABLE_CHECKING
1491 if (p
->context_depth
<= depth
)
1493 if (p
->index_by_depth
!= i
)
1496 p
->context_depth
= depth
;
1501 #ifdef ENABLE_CHECKING
1502 for (order
= 2; order
< NUM_ORDERS
; order
++)
1506 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1508 if (p
->context_depth
> depth
)
1510 else if (p
->context_depth
== depth
&& save_in_use_p (p
))
1517 /* Unmark all objects. */
1524 for (order
= 2; order
< NUM_ORDERS
; order
++)
1528 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1530 size_t num_objects
= OBJECTS_IN_PAGE (p
);
1531 size_t bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
1533 #ifdef ENABLE_CHECKING
1534 /* The data should be page-aligned. */
1535 if ((size_t) p
->page
& (G
.pagesize
- 1))
1539 /* Pages that aren't in the topmost context are not collected;
1540 nevertheless, we need their in-use bit vectors to store GC
1541 marks. So, back them up first. */
1542 if (p
->context_depth
< G
.context_depth
)
1544 if (! save_in_use_p (p
))
1545 save_in_use_p (p
) = xmalloc (bitmap_size
);
1546 memcpy (save_in_use_p (p
), p
->in_use_p
, bitmap_size
);
1549 /* Reset reset the number of free objects and clear the
1550 in-use bits. These will be adjusted by mark_obj. */
1551 p
->num_free_objects
= num_objects
;
1552 memset (p
->in_use_p
, 0, bitmap_size
);
1554 /* Make sure the one-past-the-end bit is always set. */
1555 p
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
1556 = ((unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
));
1561 /* Free all empty pages. Partially empty pages need no attention
1562 because the `mark' bit doubles as an `unused' bit. */
1569 for (order
= 2; order
< NUM_ORDERS
; order
++)
1571 /* The last page-entry to consider, regardless of entries
1572 placed at the end of the list. */
1573 page_entry
* const last
= G
.page_tails
[order
];
1576 size_t live_objects
;
1577 page_entry
*p
, *previous
;
1587 page_entry
*next
= p
->next
;
1589 /* Loop until all entries have been examined. */
1592 num_objects
= OBJECTS_IN_PAGE (p
);
1594 /* Add all live objects on this page to the count of
1595 allocated memory. */
1596 live_objects
= num_objects
- p
->num_free_objects
;
1598 G
.allocated
+= OBJECT_SIZE (order
) * live_objects
;
1600 /* Only objects on pages in the topmost context should get
1602 if (p
->context_depth
< G
.context_depth
)
1605 /* Remove the page if it's empty. */
1606 else if (live_objects
== 0)
1609 G
.pages
[order
] = next
;
1611 previous
->next
= next
;
1613 /* Are we removing the last element? */
1614 if (p
== G
.page_tails
[order
])
1615 G
.page_tails
[order
] = previous
;
1620 /* If the page is full, move it to the end. */
1621 else if (p
->num_free_objects
== 0)
1623 /* Don't move it if it's already at the end. */
1624 if (p
!= G
.page_tails
[order
])
1626 /* Move p to the end of the list. */
1628 G
.page_tails
[order
]->next
= p
;
1630 /* Update the tail pointer... */
1631 G
.page_tails
[order
] = p
;
1633 /* ... and the head pointer, if necessary. */
1635 G
.pages
[order
] = next
;
1637 previous
->next
= next
;
1642 /* If we've fallen through to here, it's a page in the
1643 topmost context that is neither full nor empty. Such a
1644 page must precede pages at lesser context depth in the
1645 list, so move it to the head. */
1646 else if (p
!= G
.pages
[order
])
1648 previous
->next
= p
->next
;
1649 p
->next
= G
.pages
[order
];
1651 /* Are we moving the last element? */
1652 if (G
.page_tails
[order
] == p
)
1653 G
.page_tails
[order
] = previous
;
1662 /* Now, restore the in_use_p vectors for any pages from contexts
1663 other than the current one. */
1664 for (p
= G
.pages
[order
]; p
; p
= p
->next
)
1665 if (p
->context_depth
!= G
.context_depth
)
1666 ggc_recalculate_in_use_p (p
);
1670 #ifdef ENABLE_GC_CHECKING
1671 /* Clobber all free objects. */
1678 for (order
= 2; order
< NUM_ORDERS
; order
++)
1680 size_t size
= OBJECT_SIZE (order
);
1683 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1688 if (p
->context_depth
!= G
.context_depth
)
1689 /* Since we don't do any collection for pages in pushed
1690 contexts, there's no need to do any poisoning. And
1691 besides, the IN_USE_P array isn't valid until we pop
1695 num_objects
= OBJECTS_IN_PAGE (p
);
1696 for (i
= 0; i
< num_objects
; i
++)
1699 word
= i
/ HOST_BITS_PER_LONG
;
1700 bit
= i
% HOST_BITS_PER_LONG
;
1701 if (((p
->in_use_p
[word
] >> bit
) & 1) == 0)
1703 char *object
= p
->page
+ i
* size
;
1705 /* Keep poison-by-write when we expect to use Valgrind,
1706 so the exact same memory semantics is kept, in case
1707 there are memory errors. We override this request
1709 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (object
, size
));
1710 memset (object
, 0xa5, size
);
1712 /* Drop the handle to avoid handle leak. */
1713 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (object
, size
));
1721 /* Top level mark-and-sweep routine. */
1726 /* Avoid frequent unnecessary work by skipping collection if the
1727 total allocations haven't expanded much since the last
1729 float allocated_last_gc
=
1730 MAX (G
.allocated_last_gc
, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE
) * 1024);
1732 float min_expand
= allocated_last_gc
* PARAM_VALUE (GGC_MIN_EXPAND
) / 100;
1734 if (G
.allocated
< allocated_last_gc
+ min_expand
)
1737 timevar_push (TV_GC
);
1739 fprintf (stderr
, " {GC %luk -> ", (unsigned long) G
.allocated
/ 1024);
1741 /* Zero the total allocated bytes. This will be recalculated in the
1745 /* Release the pages we freed the last time we collected, but didn't
1746 reuse in the interim. */
1749 /* Indicate that we've seen collections at this context depth. */
1750 G
.context_depth_collections
= ((unsigned long)1 << (G
.context_depth
+ 1)) - 1;
1755 #ifdef ENABLE_GC_CHECKING
1761 G
.allocated_last_gc
= G
.allocated
;
1763 timevar_pop (TV_GC
);
1766 fprintf (stderr
, "%luk}", (unsigned long) G
.allocated
/ 1024);
1769 /* Print allocation statistics. */
1770 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
1772 : ((x) < 1024*1024*10 \
1774 : (x) / (1024*1024))))
1775 #define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
1778 ggc_print_statistics ()
1780 struct ggc_statistics stats
;
1782 size_t total_overhead
= 0;
1784 /* Clear the statistics. */
1785 memset (&stats
, 0, sizeof (stats
));
1787 /* Make sure collection will really occur. */
1788 G
.allocated_last_gc
= 0;
1790 /* Collect and print the statistics common across collectors. */
1791 ggc_print_common_statistics (stderr
, &stats
);
1793 /* Release free pages so that we will not count the bytes allocated
1794 there as part of the total allocated memory. */
1797 /* Collect some information about the various sizes of
1799 fprintf (stderr
, "\n%-5s %10s %10s %10s\n",
1800 "Size", "Allocated", "Used", "Overhead");
1801 for (i
= 0; i
< NUM_ORDERS
; ++i
)
1808 /* Skip empty entries. */
1812 overhead
= allocated
= in_use
= 0;
1814 /* Figure out the total number of bytes allocated for objects of
1815 this size, and how many of them are actually in use. Also figure
1816 out how much memory the page table is using. */
1817 for (p
= G
.pages
[i
]; p
; p
= p
->next
)
1819 allocated
+= p
->bytes
;
1821 (OBJECTS_IN_PAGE (p
) - p
->num_free_objects
) * OBJECT_SIZE (i
);
1823 overhead
+= (sizeof (page_entry
) - sizeof (long)
1824 + BITMAP_SIZE (OBJECTS_IN_PAGE (p
) + 1));
1826 fprintf (stderr
, "%-5lu %10lu%c %10lu%c %10lu%c\n",
1827 (unsigned long) OBJECT_SIZE (i
),
1828 SCALE (allocated
), LABEL (allocated
),
1829 SCALE (in_use
), LABEL (in_use
),
1830 SCALE (overhead
), LABEL (overhead
));
1831 total_overhead
+= overhead
;
1833 fprintf (stderr
, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
1834 SCALE (G
.bytes_mapped
), LABEL (G
.bytes_mapped
),
1835 SCALE (G
.allocated
), LABEL(G
.allocated
),
1836 SCALE (total_overhead
), LABEL (total_overhead
));
1841 struct ggc_pch_ondisk
1843 unsigned totals
[NUM_ORDERS
];
1845 size_t base
[NUM_ORDERS
];
1846 size_t written
[NUM_ORDERS
];
1849 struct ggc_pch_data
*
1852 return xcalloc (sizeof (struct ggc_pch_data
), 1);
1856 ggc_pch_count_object (d
, x
, size
)
1857 struct ggc_pch_data
*d
;
1858 void *x ATTRIBUTE_UNUSED
;
1864 order
= size_lookup
[size
];
1868 while (size
> OBJECT_SIZE (order
))
1872 d
->d
.totals
[order
]++;
1876 ggc_pch_total_size (d
)
1877 struct ggc_pch_data
*d
;
1882 for (i
= 0; i
< NUM_ORDERS
; i
++)
1883 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
1888 ggc_pch_this_base (d
, base
)
1889 struct ggc_pch_data
*d
;
1892 size_t a
= (size_t) base
;
1895 for (i
= 0; i
< NUM_ORDERS
; i
++)
1898 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
1904 ggc_pch_alloc_object (d
, x
, size
)
1905 struct ggc_pch_data
*d
;
1906 void *x ATTRIBUTE_UNUSED
;
1913 order
= size_lookup
[size
];
1917 while (size
> OBJECT_SIZE (order
))
1921 result
= (char *) d
->base
[order
];
1922 d
->base
[order
] += OBJECT_SIZE (order
);
1927 ggc_pch_prepare_write (d
, f
)
1928 struct ggc_pch_data
* d ATTRIBUTE_UNUSED
;
1929 FILE * f ATTRIBUTE_UNUSED
;
1931 /* Nothing to do. */
1935 ggc_pch_write_object (d
, f
, x
, newx
, size
)
1936 struct ggc_pch_data
* d ATTRIBUTE_UNUSED
;
1939 void *newx ATTRIBUTE_UNUSED
;
1945 order
= size_lookup
[size
];
1949 while (size
> OBJECT_SIZE (order
))
1953 if (fwrite (x
, size
, 1, f
) != 1)
1954 fatal_io_error ("can't write PCH file");
1956 /* In the current implementation, SIZE is always equal to
1957 OBJECT_SIZE (order) and so the fseek is never executed. */
1958 if (size
!= OBJECT_SIZE (order
)
1959 && fseek (f
, OBJECT_SIZE (order
) - size
, SEEK_CUR
) != 0)
1960 fatal_io_error ("can't write PCH file");
1962 d
->written
[order
]++;
1963 if (d
->written
[order
] == d
->d
.totals
[order
]
1964 && fseek (f
, ROUND_UP_VALUE (d
->d
.totals
[order
] * OBJECT_SIZE (order
),
1967 fatal_io_error ("can't write PCH file");
1971 ggc_pch_finish (d
, f
)
1972 struct ggc_pch_data
* d
;
1975 if (fwrite (&d
->d
, sizeof (d
->d
), 1, f
) != 1)
1976 fatal_io_error ("can't write PCH file");
1980 /* Move the PCH PTE entries just added to the end of by_depth, to the
1984 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
)
1985 int count_old_page_tables
;
1986 int count_new_page_tables
;
1990 /* First, we swap the new entries to the front of the varrays. */
1991 page_entry
**new_by_depth
;
1992 unsigned long **new_save_in_use
;
1994 new_by_depth
= (page_entry
**) xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
1995 new_save_in_use
= (unsigned long **) xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
1997 memcpy (&new_by_depth
[0],
1998 &G
.by_depth
[count_old_page_tables
],
1999 count_new_page_tables
* sizeof (void *));
2000 memcpy (&new_by_depth
[count_new_page_tables
],
2002 count_old_page_tables
* sizeof (void *));
2003 memcpy (&new_save_in_use
[0],
2004 &G
.save_in_use
[count_old_page_tables
],
2005 count_new_page_tables
* sizeof (void *));
2006 memcpy (&new_save_in_use
[count_new_page_tables
],
2008 count_old_page_tables
* sizeof (void *));
2011 free (G
.save_in_use
);
2013 G
.by_depth
= new_by_depth
;
2014 G
.save_in_use
= new_save_in_use
;
2016 /* Now update all the index_by_depth fields. */
2017 for (i
= G
.by_depth_in_use
; i
> 0; --i
)
2019 page_entry
*p
= G
.by_depth
[i
-1];
2020 p
->index_by_depth
= i
-1;
2023 /* And last, we update the depth pointers in G.depth. The first
2024 entry is already 0, and context 0 entries always start at index
2025 0, so there is nothing to update in the first slot. We need a
2026 second slot, only if we have old ptes, and if we do, they start
2027 at index count_new_page_tables. */
2028 if (count_old_page_tables
)
2029 push_depth (count_new_page_tables
);
2033 ggc_pch_read (f
, addr
)
2037 struct ggc_pch_ondisk d
;
2040 unsigned long count_old_page_tables
;
2041 unsigned long count_new_page_tables
;
2043 count_old_page_tables
= G
.by_depth_in_use
;
2045 /* We've just read in a PCH file. So, every object that used to be
2046 allocated is now free. */
2052 /* No object read from a PCH file should ever be freed. So, set the
2053 context depth to 1, and set the depth of all the currently-allocated
2054 pages to be 1 too. PCH pages will have depth 0. */
2055 if (G
.context_depth
!= 0)
2057 G
.context_depth
= 1;
2058 for (i
= 0; i
< NUM_ORDERS
; i
++)
2061 for (p
= G
.pages
[i
]; p
!= NULL
; p
= p
->next
)
2062 p
->context_depth
= G
.context_depth
;
2065 /* Allocate the appropriate page-table entries for the pages read from
2067 if (fread (&d
, sizeof (d
), 1, f
) != 1)
2068 fatal_io_error ("can't read PCH file");
2070 for (i
= 0; i
< NUM_ORDERS
; i
++)
2072 struct page_entry
*entry
;
2078 if (d
.totals
[i
] == 0)
2081 bytes
= ROUND_UP (d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2082 num_objs
= bytes
/ OBJECT_SIZE (i
);
2083 entry
= xcalloc (1, (sizeof (struct page_entry
)
2085 + BITMAP_SIZE (num_objs
+ 1)));
2086 entry
->bytes
= bytes
;
2088 entry
->context_depth
= 0;
2090 entry
->num_free_objects
= 0;
2094 j
+ HOST_BITS_PER_LONG
<= num_objs
+ 1;
2095 j
+= HOST_BITS_PER_LONG
)
2096 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
] = -1;
2097 for (; j
< num_objs
+ 1; j
++)
2098 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
]
2099 |= 1L << (j
% HOST_BITS_PER_LONG
);
2101 for (pte
= entry
->page
;
2102 pte
< entry
->page
+ entry
->bytes
;
2104 set_page_table_entry (pte
, entry
);
2106 if (G
.page_tails
[i
] != NULL
)
2107 G
.page_tails
[i
]->next
= entry
;
2110 G
.page_tails
[i
] = entry
;
2112 /* We start off by just adding all the new information to the
2113 end of the varrays, later, we will move the new information
2114 to the front of the varrays, as the PCH page tables are at
2116 push_by_depth (entry
, 0);
2119 /* Now, we update the various data structures that speed page table
2121 count_new_page_tables
= G
.by_depth_in_use
- count_old_page_tables
;
2123 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
);
2125 /* Update the statistics. */
2126 G
.allocated
= G
.allocated_last_gc
= offs
- (char *)addr
;