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_VALGRIND_MEMCHECK_H
35 # include <valgrind/memcheck.h>
36 # elif defined HAVE_MEMCHECK_H
37 # include <memcheck.h>
39 # include <valgrind.h>
42 /* Avoid #ifdef:s when we can help it. */
43 #define VALGRIND_DISCARD(x)
46 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
47 file open. Prefer either to valloc. */
49 # undef HAVE_MMAP_DEV_ZERO
51 # include <sys/mman.h>
53 # define MAP_FAILED -1
55 # if !defined (MAP_ANONYMOUS) && defined (MAP_ANON)
56 # define MAP_ANONYMOUS MAP_ANON
62 #ifdef HAVE_MMAP_DEV_ZERO
64 # include <sys/mman.h>
66 # define MAP_FAILED -1
73 #define USING_MALLOC_PAGE_GROUPS
78 This garbage-collecting allocator allocates objects on one of a set
79 of pages. Each page can allocate objects of a single size only;
80 available sizes are powers of two starting at four bytes. The size
81 of an allocation request is rounded up to the next power of two
82 (`order'), and satisfied from the appropriate page.
84 Each page is recorded in a page-entry, which also maintains an
85 in-use bitmap of object positions on the page. This allows the
86 allocation state of a particular object to be flipped without
87 touching the page itself.
89 Each page-entry also has a context depth, which is used to track
90 pushing and popping of allocation contexts. Only objects allocated
91 in the current (highest-numbered) context may be collected.
93 Page entries are arranged in an array of singly-linked lists. The
94 array is indexed by the allocation size, in bits, of the pages on
95 it; i.e. all pages on a list allocate objects of the same size.
96 Pages are ordered on the list such that all non-full pages precede
97 all full pages, with non-full pages arranged in order of decreasing
100 Empty pages (of all orders) are kept on a single page cache list,
101 and are considered first when new pages are required; they are
102 deallocated at the start of the next collection if they haven't
103 been recycled by then. */
105 /* Define GGC_DEBUG_LEVEL to print debugging information.
106 0: No debugging output.
107 1: GC statistics only.
108 2: Page-entry allocations/deallocations as well.
109 3: Object allocations as well.
110 4: Object marks as well. */
111 #define GGC_DEBUG_LEVEL (0)
113 #ifndef HOST_BITS_PER_PTR
114 #define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
118 /* A two-level tree is used to look up the page-entry for a given
119 pointer. Two chunks of the pointer's bits are extracted to index
120 the first and second levels of the tree, as follows:
124 msb +----------------+----+------+------+ lsb
130 The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
131 pages are aligned on system page boundaries. The next most
132 significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
133 index values in the lookup table, respectively.
135 For 32-bit architectures and the settings below, there are no
136 leftover bits. For architectures with wider pointers, the lookup
137 tree points to a list of pages, which must be scanned to find the
140 #define PAGE_L1_BITS (8)
141 #define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
142 #define PAGE_L1_SIZE ((size_t) 1 << PAGE_L1_BITS)
143 #define PAGE_L2_SIZE ((size_t) 1 << PAGE_L2_BITS)
145 #define LOOKUP_L1(p) \
146 (((size_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
148 #define LOOKUP_L2(p) \
149 (((size_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
151 /* The number of objects per allocation page, for objects on a page of
152 the indicated ORDER. */
153 #define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
155 /* The number of objects in P. */
156 #define OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
158 /* The size of an object on a page of the indicated ORDER. */
159 #define OBJECT_SIZE(ORDER) object_size_table[ORDER]
161 /* For speed, we avoid doing a general integer divide to locate the
162 offset in the allocation bitmap, by precalculating numbers M, S
163 such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
164 within the page which is evenly divisible by the object size Z. */
165 #define DIV_MULT(ORDER) inverse_table[ORDER].mult
166 #define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
167 #define OFFSET_TO_BIT(OFFSET, ORDER) \
168 (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
170 /* The number of extra orders, not corresponding to power-of-two sized
173 #define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
175 #define RTL_SIZE(NSLOTS) \
176 (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))
178 #define TREE_EXP_SIZE(OPS) \
179 (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
181 /* The Ith entry is the maximum size of an object to be stored in the
182 Ith extra order. Adding a new entry to this array is the *only*
183 thing you need to do to add a new special allocation size. */
185 static const size_t extra_order_size_table
[] = {
186 sizeof (struct tree_decl
),
187 sizeof (struct tree_list
),
189 RTL_SIZE (2), /* MEM, PLUS, etc. */
190 RTL_SIZE (9), /* INSN */
193 /* The total number of orders. */
195 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
197 /* We use this structure to determine the alignment required for
198 allocations. For power-of-two sized allocations, that's not a
199 problem, but it does matter for odd-sized allocations. */
201 struct max_alignment
{
209 /* The biggest alignment required. */
211 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
213 /* Compute the smallest nonnegative number which when added to X gives
216 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
218 /* Compute the smallest multiple of F that is >= X. */
220 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
222 /* The Ith entry is the number of objects on a page or order I. */
224 static unsigned objects_per_page_table
[NUM_ORDERS
];
226 /* The Ith entry is the size of an object on a page of order I. */
228 static size_t object_size_table
[NUM_ORDERS
];
230 /* The Ith entry is a pair of numbers (mult, shift) such that
231 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
232 for all k evenly divisible by OBJECT_SIZE(I). */
239 inverse_table
[NUM_ORDERS
];
241 /* A page_entry records the status of an allocation page. This
242 structure is dynamically sized to fit the bitmap in_use_p. */
243 typedef struct page_entry
245 /* The next page-entry with objects of the same size, or NULL if
246 this is the last page-entry. */
247 struct page_entry
*next
;
249 /* The number of bytes allocated. (This will always be a multiple
250 of the host system page size.) */
253 /* The address at which the memory is allocated. */
256 #ifdef USING_MALLOC_PAGE_GROUPS
257 /* Back pointer to the page group this page came from. */
258 struct page_group
*group
;
261 /* This is the index in the by_depth varray where this page table
263 unsigned long index_by_depth
;
265 /* Context depth of this page. */
266 unsigned short context_depth
;
268 /* The number of free objects remaining on this page. */
269 unsigned short num_free_objects
;
271 /* A likely candidate for the bit position of a free object for the
272 next allocation from this page. */
273 unsigned short next_bit_hint
;
275 /* The lg of size of objects allocated from this page. */
278 /* A bit vector indicating whether or not objects are in use. The
279 Nth bit is one if the Nth object on this page is allocated. This
280 array is dynamically sized. */
281 unsigned long in_use_p
[1];
284 #ifdef USING_MALLOC_PAGE_GROUPS
285 /* A page_group describes a large allocation from malloc, from which
286 we parcel out aligned pages. */
287 typedef struct page_group
289 /* A linked list of all extant page groups. */
290 struct page_group
*next
;
292 /* The address we received from malloc. */
295 /* The size of the block. */
298 /* A bitmask of pages in use. */
303 #if HOST_BITS_PER_PTR <= 32
305 /* On 32-bit hosts, we use a two level page table, as pictured above. */
306 typedef page_entry
**page_table
[PAGE_L1_SIZE
];
310 /* On 64-bit hosts, we use the same two level page tables plus a linked
311 list that disambiguates the top 32-bits. There will almost always be
312 exactly one entry in the list. */
313 typedef struct page_table_chain
315 struct page_table_chain
*next
;
317 page_entry
**table
[PAGE_L1_SIZE
];
322 /* The rest of the global variables. */
323 static struct globals
325 /* The Nth element in this array is a page with objects of size 2^N.
326 If there are any pages with free objects, they will be at the
327 head of the list. NULL if there are no page-entries for this
329 page_entry
*pages
[NUM_ORDERS
];
331 /* The Nth element in this array is the last page with objects of
332 size 2^N. NULL if there are no page-entries for this object
334 page_entry
*page_tails
[NUM_ORDERS
];
336 /* Lookup table for associating allocation pages with object addresses. */
339 /* The system's page size. */
343 /* Bytes currently allocated. */
346 /* Bytes currently allocated at the end of the last collection. */
347 size_t allocated_last_gc
;
349 /* Total amount of memory mapped. */
352 /* Bit N set if any allocations have been done at context depth N. */
353 unsigned long context_depth_allocations
;
355 /* Bit N set if any collections have been done at context depth N. */
356 unsigned long context_depth_collections
;
358 /* The current depth in the context stack. */
359 unsigned short context_depth
;
361 /* A file descriptor open to /dev/zero for reading. */
362 #if defined (HAVE_MMAP_DEV_ZERO)
366 /* A cache of free system pages. */
367 page_entry
*free_pages
;
369 #ifdef USING_MALLOC_PAGE_GROUPS
370 page_group
*page_groups
;
373 /* The file descriptor for debugging output. */
376 /* Current number of elements in use in depth below. */
377 unsigned int depth_in_use
;
379 /* Maximum number of elements that can be used before resizing. */
380 unsigned int depth_max
;
382 /* Each element of this arry is an index in by_depth where the given
383 depth starts. This structure is indexed by that given depth we
384 are interested in. */
387 /* Current number of elements in use in by_depth below. */
388 unsigned int by_depth_in_use
;
390 /* Maximum number of elements that can be used before resizing. */
391 unsigned int by_depth_max
;
393 /* Each element of this array is a pointer to a page_entry, all
394 page_entries can be found in here by increasing depth.
395 index_by_depth in the page_entry is the index into this data
396 structure where that page_entry can be found. This is used to
397 speed up finding all page_entries at a particular depth. */
398 page_entry
**by_depth
;
400 /* Each element is a pointer to the saved in_use_p bits, if any,
401 zero otherwise. We allocate them all together, to enable a
402 better runtime data access pattern. */
403 unsigned long **save_in_use
;
404 #ifdef GATHER_STATISTICS
407 /* Total memory allocated with ggc_alloc. */
408 unsigned long long total_allocated
;
409 /* Total overhead for memory to be allocated with ggc_alloc. */
410 unsigned long long total_overhead
;
412 /* Total allocations and overhead for sizes less than 32, 64 and 128.
413 These sizes are interesting because they are typical cache line
416 unsigned long long total_allocated_under32
;
417 unsigned long long total_overhead_under32
;
419 unsigned long long total_allocated_under64
;
420 unsigned long long total_overhead_under64
;
422 unsigned long long total_allocated_under128
;
423 unsigned long long total_overhead_under128
;
425 /* The allocations for each of the allocation orders. */
426 unsigned long long total_allocated_per_order
[NUM_ORDERS
];
428 /* The overhead for each of the allocation orders. */
429 unsigned long long total_overhead_per_order
[NUM_ORDERS
];
434 /* The size in bytes required to maintain a bitmap for the objects
436 #define BITMAP_SIZE(Num_objects) \
437 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
439 /* Allocate pages in chunks of this size, to throttle calls to memory
440 allocation routines. The first page is used, the rest go onto the
441 free list. This cannot be larger than HOST_BITS_PER_INT for the
442 in_use bitmask for page_group. */
443 #define GGC_QUIRE_SIZE 16
445 /* Initial guess as to how many page table entries we might need. */
446 #define INITIAL_PTE_COUNT 128
448 static int ggc_allocated_p (const void *);
449 static page_entry
*lookup_page_table_entry (const void *);
450 static void set_page_table_entry (void *, page_entry
*);
452 static char *alloc_anon (char *, size_t);
454 #ifdef USING_MALLOC_PAGE_GROUPS
455 static size_t page_group_index (char *, char *);
456 static void set_page_group_in_use (page_group
*, char *);
457 static void clear_page_group_in_use (page_group
*, char *);
459 static struct page_entry
* alloc_page (unsigned);
460 static void free_page (struct page_entry
*);
461 static void release_pages (void);
462 static void clear_marks (void);
463 static void sweep_pages (void);
464 static void ggc_recalculate_in_use_p (page_entry
*);
465 static void compute_inverse (unsigned);
466 static inline void adjust_depth (void);
467 static void move_ptes_to_front (int, int);
469 #ifdef ENABLE_GC_CHECKING
470 static void poison_pages (void);
473 void debug_print_page_list (int);
474 static void push_depth (unsigned int);
475 static void push_by_depth (page_entry
*, unsigned long *);
476 struct alloc_zone
*rtl_zone
= NULL
;
477 struct alloc_zone
*tree_zone
= NULL
;
478 struct alloc_zone
*garbage_zone
= NULL
;
480 /* Push an entry onto G.depth. */
483 push_depth (unsigned int i
)
485 if (G
.depth_in_use
>= G
.depth_max
)
488 G
.depth
= xrealloc (G
.depth
, G
.depth_max
* sizeof (unsigned int));
490 G
.depth
[G
.depth_in_use
++] = i
;
493 /* Push an entry onto G.by_depth and G.save_in_use. */
496 push_by_depth (page_entry
*p
, unsigned long *s
)
498 if (G
.by_depth_in_use
>= G
.by_depth_max
)
501 G
.by_depth
= xrealloc (G
.by_depth
,
502 G
.by_depth_max
* sizeof (page_entry
*));
503 G
.save_in_use
= xrealloc (G
.save_in_use
,
504 G
.by_depth_max
* sizeof (unsigned long *));
506 G
.by_depth
[G
.by_depth_in_use
] = p
;
507 G
.save_in_use
[G
.by_depth_in_use
++] = s
;
510 #if (GCC_VERSION < 3001)
511 #define prefetch(X) ((void) X)
513 #define prefetch(X) __builtin_prefetch (X)
516 #define save_in_use_p_i(__i) \
518 #define save_in_use_p(__p) \
519 (save_in_use_p_i (__p->index_by_depth))
521 /* Returns nonzero if P was allocated in GC'able memory. */
524 ggc_allocated_p (const void *p
)
529 #if HOST_BITS_PER_PTR <= 32
532 page_table table
= G
.lookup
;
533 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
538 if (table
->high_bits
== high_bits
)
542 base
= &table
->table
[0];
545 /* Extract the level 1 and 2 indices. */
549 return base
[L1
] && base
[L1
][L2
];
552 /* Traverse the page table and find the entry for a page.
553 Die (probably) if the object wasn't allocated via GC. */
555 static inline page_entry
*
556 lookup_page_table_entry (const void *p
)
561 #if HOST_BITS_PER_PTR <= 32
564 page_table table
= G
.lookup
;
565 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
566 while (table
->high_bits
!= high_bits
)
568 base
= &table
->table
[0];
571 /* Extract the level 1 and 2 indices. */
578 /* Set the page table entry for a page. */
581 set_page_table_entry (void *p
, page_entry
*entry
)
586 #if HOST_BITS_PER_PTR <= 32
590 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
591 for (table
= G
.lookup
; table
; table
= table
->next
)
592 if (table
->high_bits
== high_bits
)
595 /* Not found -- allocate a new table. */
596 table
= xcalloc (1, sizeof(*table
));
597 table
->next
= G
.lookup
;
598 table
->high_bits
= high_bits
;
601 base
= &table
->table
[0];
604 /* Extract the level 1 and 2 indices. */
608 if (base
[L1
] == NULL
)
609 base
[L1
] = xcalloc (PAGE_L2_SIZE
, sizeof (page_entry
*));
611 base
[L1
][L2
] = entry
;
614 /* Prints the page-entry for object size ORDER, for debugging. */
617 debug_print_page_list (int order
)
620 printf ("Head=%p, Tail=%p:\n", (void *) G
.pages
[order
],
621 (void *) G
.page_tails
[order
]);
625 printf ("%p(%1d|%3d) -> ", (void *) p
, p
->context_depth
,
626 p
->num_free_objects
);
634 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
635 (if non-null). The ifdef structure here is intended to cause a
636 compile error unless exactly one of the HAVE_* is defined. */
639 alloc_anon (char *pref ATTRIBUTE_UNUSED
, size_t size
)
641 #ifdef HAVE_MMAP_ANON
642 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
643 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
645 #ifdef HAVE_MMAP_DEV_ZERO
646 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
647 MAP_PRIVATE
, G
.dev_zero_fd
, 0);
650 if (page
== (char *) MAP_FAILED
)
652 perror ("virtual memory exhausted");
653 exit (FATAL_EXIT_CODE
);
656 /* Remember that we allocated this memory. */
657 G
.bytes_mapped
+= size
;
659 /* Pretend we don't have access to the allocated pages. We'll enable
660 access to smaller pieces of the area in ggc_alloc. Discard the
661 handle to avoid handle leak. */
662 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (page
, size
));
667 #ifdef USING_MALLOC_PAGE_GROUPS
668 /* Compute the index for this page into the page group. */
671 page_group_index (char *allocation
, char *page
)
673 return (size_t) (page
- allocation
) >> G
.lg_pagesize
;
676 /* Set and clear the in_use bit for this page in the page group. */
679 set_page_group_in_use (page_group
*group
, char *page
)
681 group
->in_use
|= 1 << page_group_index (group
->allocation
, page
);
685 clear_page_group_in_use (page_group
*group
, char *page
)
687 group
->in_use
&= ~(1 << page_group_index (group
->allocation
, page
));
691 /* Allocate a new page for allocating objects of size 2^ORDER,
692 and return an entry for it. The entry is not added to the
693 appropriate page_table list. */
695 static inline struct page_entry
*
696 alloc_page (unsigned order
)
698 struct page_entry
*entry
, *p
, **pp
;
702 size_t page_entry_size
;
704 #ifdef USING_MALLOC_PAGE_GROUPS
708 num_objects
= OBJECTS_PER_PAGE (order
);
709 bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
710 page_entry_size
= sizeof (page_entry
) - sizeof (long) + bitmap_size
;
711 entry_size
= num_objects
* OBJECT_SIZE (order
);
712 if (entry_size
< G
.pagesize
)
713 entry_size
= G
.pagesize
;
718 /* Check the list of free pages for one we can use. */
719 for (pp
= &G
.free_pages
, p
= *pp
; p
; pp
= &p
->next
, p
= *pp
)
720 if (p
->bytes
== entry_size
)
725 /* Recycle the allocated memory from this page ... */
729 #ifdef USING_MALLOC_PAGE_GROUPS
733 /* ... and, if possible, the page entry itself. */
734 if (p
->order
== order
)
737 memset (entry
, 0, page_entry_size
);
743 else if (entry_size
== G
.pagesize
)
745 /* We want just one page. Allocate a bunch of them and put the
746 extras on the freelist. (Can only do this optimization with
747 mmap for backing store.) */
748 struct page_entry
*e
, *f
= G
.free_pages
;
751 page
= alloc_anon (NULL
, G
.pagesize
* GGC_QUIRE_SIZE
);
753 /* This loop counts down so that the chain will be in ascending
755 for (i
= GGC_QUIRE_SIZE
- 1; i
>= 1; i
--)
757 e
= xcalloc (1, page_entry_size
);
759 e
->bytes
= G
.pagesize
;
760 e
->page
= page
+ (i
<< G
.lg_pagesize
);
768 page
= alloc_anon (NULL
, entry_size
);
770 #ifdef USING_MALLOC_PAGE_GROUPS
773 /* Allocate a large block of memory and serve out the aligned
774 pages therein. This results in much less memory wastage
775 than the traditional implementation of valloc. */
777 char *allocation
, *a
, *enda
;
778 size_t alloc_size
, head_slop
, tail_slop
;
779 int multiple_pages
= (entry_size
== G
.pagesize
);
782 alloc_size
= GGC_QUIRE_SIZE
* G
.pagesize
;
784 alloc_size
= entry_size
+ G
.pagesize
- 1;
785 allocation
= xmalloc (alloc_size
);
787 page
= (char *) (((size_t) allocation
+ G
.pagesize
- 1) & -G
.pagesize
);
788 head_slop
= page
- allocation
;
790 tail_slop
= ((size_t) allocation
+ alloc_size
) & (G
.pagesize
- 1);
792 tail_slop
= alloc_size
- entry_size
- head_slop
;
793 enda
= allocation
+ alloc_size
- tail_slop
;
795 /* We allocated N pages, which are likely not aligned, leaving
796 us with N-1 usable pages. We plan to place the page_group
797 structure somewhere in the slop. */
798 if (head_slop
>= sizeof (page_group
))
799 group
= (page_group
*)page
- 1;
802 /* We magically got an aligned allocation. Too bad, we have
803 to waste a page anyway. */
807 tail_slop
+= G
.pagesize
;
809 if (tail_slop
< sizeof (page_group
))
811 group
= (page_group
*)enda
;
812 tail_slop
-= sizeof (page_group
);
815 /* Remember that we allocated this memory. */
816 group
->next
= G
.page_groups
;
817 group
->allocation
= allocation
;
818 group
->alloc_size
= alloc_size
;
820 G
.page_groups
= group
;
821 G
.bytes_mapped
+= alloc_size
;
823 /* If we allocated multiple pages, put the rest on the free list. */
826 struct page_entry
*e
, *f
= G
.free_pages
;
827 for (a
= enda
- G
.pagesize
; a
!= page
; a
-= G
.pagesize
)
829 e
= xcalloc (1, page_entry_size
);
831 e
->bytes
= G
.pagesize
;
843 entry
= xcalloc (1, page_entry_size
);
845 entry
->bytes
= entry_size
;
847 entry
->context_depth
= G
.context_depth
;
848 entry
->order
= order
;
849 entry
->num_free_objects
= num_objects
;
850 entry
->next_bit_hint
= 1;
852 G
.context_depth_allocations
|= (unsigned long)1 << G
.context_depth
;
854 #ifdef USING_MALLOC_PAGE_GROUPS
855 entry
->group
= group
;
856 set_page_group_in_use (group
, page
);
859 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
860 increment the hint. */
861 entry
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
862 = (unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
);
864 set_page_table_entry (page
, entry
);
866 if (GGC_DEBUG_LEVEL
>= 2)
867 fprintf (G
.debug_file
,
868 "Allocating page at %p, object size=%lu, data %p-%p\n",
869 (void *) entry
, (unsigned long) OBJECT_SIZE (order
), page
,
870 page
+ entry_size
- 1);
875 /* Adjust the size of G.depth so that no index greater than the one
876 used by the top of the G.by_depth is used. */
883 if (G
.by_depth_in_use
)
885 top
= G
.by_depth
[G
.by_depth_in_use
-1];
887 /* Peel back indices in depth that index into by_depth, so that
888 as new elements are added to by_depth, we note the indices
889 of those elements, if they are for new context depths. */
890 while (G
.depth_in_use
> (size_t)top
->context_depth
+1)
895 /* For a page that is no longer needed, put it on the free page list. */
898 free_page (page_entry
*entry
)
900 if (GGC_DEBUG_LEVEL
>= 2)
901 fprintf (G
.debug_file
,
902 "Deallocating page at %p, data %p-%p\n", (void *) entry
,
903 entry
->page
, entry
->page
+ entry
->bytes
- 1);
905 /* Mark the page as inaccessible. Discard the handle to avoid handle
907 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (entry
->page
, entry
->bytes
));
909 set_page_table_entry (entry
->page
, NULL
);
911 #ifdef USING_MALLOC_PAGE_GROUPS
912 clear_page_group_in_use (entry
->group
, entry
->page
);
915 if (G
.by_depth_in_use
> 1)
917 page_entry
*top
= G
.by_depth
[G
.by_depth_in_use
-1];
919 /* If they are at the same depth, put top element into freed
921 if (entry
->context_depth
== top
->context_depth
)
923 int i
= entry
->index_by_depth
;
925 G
.save_in_use
[i
] = G
.save_in_use
[G
.by_depth_in_use
-1];
926 top
->index_by_depth
= i
;
930 /* We cannot free a page from a context deeper than the
939 entry
->next
= G
.free_pages
;
940 G
.free_pages
= entry
;
943 /* Release the free page cache to the system. */
949 page_entry
*p
, *next
;
953 /* Gather up adjacent pages so they are unmapped together. */
964 while (p
&& p
->page
== start
+ len
)
973 G
.bytes_mapped
-= len
;
978 #ifdef USING_MALLOC_PAGE_GROUPS
982 /* Remove all pages from free page groups from the list. */
984 while ((p
= *pp
) != NULL
)
985 if (p
->group
->in_use
== 0)
993 /* Remove all free page groups, and release the storage. */
995 while ((g
= *gp
) != NULL
)
999 G
.bytes_mapped
-= g
->alloc_size
;
1000 free (g
->allocation
);
1007 /* This table provides a fast way to determine ceil(log_2(size)) for
1008 allocation requests. The minimum allocation size is eight bytes. */
1010 static unsigned char size_lookup
[257] =
1012 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
1013 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1014 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1015 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1016 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1017 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1018 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1019 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1020 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1021 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1022 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1023 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1024 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1025 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1026 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1027 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1031 /* Typed allocation function. Does nothing special in this collector. */
1034 ggc_alloc_typed (enum gt_types_enum type ATTRIBUTE_UNUSED
, size_t size
)
1036 return ggc_alloc (size
);
1039 /* Zone allocation function. Does nothing special in this collector. */
1042 ggc_alloc_zone (size_t size
, struct alloc_zone
*zone ATTRIBUTE_UNUSED
)
1044 return ggc_alloc (size
);
1047 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1050 ggc_alloc (size_t size
)
1052 unsigned order
, word
, bit
, object_offset
;
1053 struct page_entry
*entry
;
1057 order
= size_lookup
[size
];
1061 while (size
> OBJECT_SIZE (order
))
1065 /* If there are non-full pages for this size allocation, they are at
1066 the head of the list. */
1067 entry
= G
.pages
[order
];
1069 /* If there is no page for this object size, or all pages in this
1070 context are full, allocate a new page. */
1071 if (entry
== NULL
|| entry
->num_free_objects
== 0)
1073 struct page_entry
*new_entry
;
1074 new_entry
= alloc_page (order
);
1076 new_entry
->index_by_depth
= G
.by_depth_in_use
;
1077 push_by_depth (new_entry
, 0);
1079 /* We can skip context depths, if we do, make sure we go all the
1080 way to the new depth. */
1081 while (new_entry
->context_depth
>= G
.depth_in_use
)
1082 push_depth (G
.by_depth_in_use
-1);
1084 /* If this is the only entry, it's also the tail. */
1086 G
.page_tails
[order
] = new_entry
;
1088 /* Put new pages at the head of the page list. */
1089 new_entry
->next
= entry
;
1091 G
.pages
[order
] = new_entry
;
1093 /* For a new page, we know the word and bit positions (in the
1094 in_use bitmap) of the first available object -- they're zero. */
1095 new_entry
->next_bit_hint
= 1;
1102 /* First try to use the hint left from the previous allocation
1103 to locate a clear bit in the in-use bitmap. We've made sure
1104 that the one-past-the-end bit is always set, so if the hint
1105 has run over, this test will fail. */
1106 unsigned hint
= entry
->next_bit_hint
;
1107 word
= hint
/ HOST_BITS_PER_LONG
;
1108 bit
= hint
% HOST_BITS_PER_LONG
;
1110 /* If the hint didn't work, scan the bitmap from the beginning. */
1111 if ((entry
->in_use_p
[word
] >> bit
) & 1)
1114 while (~entry
->in_use_p
[word
] == 0)
1116 while ((entry
->in_use_p
[word
] >> bit
) & 1)
1118 hint
= word
* HOST_BITS_PER_LONG
+ bit
;
1121 /* Next time, try the next bit. */
1122 entry
->next_bit_hint
= hint
+ 1;
1124 object_offset
= hint
* OBJECT_SIZE (order
);
1127 /* Set the in-use bit. */
1128 entry
->in_use_p
[word
] |= ((unsigned long) 1 << bit
);
1130 /* Keep a running total of the number of free objects. If this page
1131 fills up, we may have to move it to the end of the list if the
1132 next page isn't full. If the next page is full, all subsequent
1133 pages are full, so there's no need to move it. */
1134 if (--entry
->num_free_objects
== 0
1135 && entry
->next
!= NULL
1136 && entry
->next
->num_free_objects
> 0)
1138 G
.pages
[order
] = entry
->next
;
1140 G
.page_tails
[order
]->next
= entry
;
1141 G
.page_tails
[order
] = entry
;
1144 /* Calculate the object's address. */
1145 result
= entry
->page
+ object_offset
;
1147 #ifdef ENABLE_GC_CHECKING
1148 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1149 exact same semantics in presence of memory bugs, regardless of
1150 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1151 handle to avoid handle leak. */
1152 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, OBJECT_SIZE (order
)));
1154 /* `Poison' the entire allocated object, including any padding at
1156 memset (result
, 0xaf, OBJECT_SIZE (order
));
1158 /* Make the bytes after the end of the object unaccessible. Discard the
1159 handle to avoid handle leak. */
1160 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) result
+ size
,
1161 OBJECT_SIZE (order
) - size
));
1164 /* Tell Valgrind that the memory is there, but its content isn't
1165 defined. The bytes at the end of the object are still marked
1167 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, size
));
1169 /* Keep track of how many bytes are being allocated. This
1170 information is used in deciding when to collect. */
1171 G
.allocated
+= OBJECT_SIZE (order
);
1173 #ifdef GATHER_STATISTICS
1175 G
.stats
.total_overhead
+= OBJECT_SIZE (order
) - size
;
1176 G
.stats
.total_allocated
+= OBJECT_SIZE(order
);
1177 G
.stats
.total_overhead_per_order
[order
] += OBJECT_SIZE (order
) - size
;
1178 G
.stats
.total_allocated_per_order
[order
] += OBJECT_SIZE (order
);
1181 G
.stats
.total_overhead_under32
+= OBJECT_SIZE (order
) - size
;
1182 G
.stats
.total_allocated_under32
+= OBJECT_SIZE(order
);
1186 G
.stats
.total_overhead_under64
+= OBJECT_SIZE (order
) - size
;
1187 G
.stats
.total_allocated_under64
+= OBJECT_SIZE(order
);
1191 G
.stats
.total_overhead_under128
+= OBJECT_SIZE (order
) - size
;
1192 G
.stats
.total_allocated_under128
+= OBJECT_SIZE(order
);
1198 if (GGC_DEBUG_LEVEL
>= 3)
1199 fprintf (G
.debug_file
,
1200 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1201 (unsigned long) size
, (unsigned long) OBJECT_SIZE (order
), result
,
1207 /* If P is not marked, marks it and return false. Otherwise return true.
1208 P must have been allocated by the GC allocator; it mustn't point to
1209 static objects, stack variables, or memory allocated with malloc. */
1212 ggc_set_mark (const void *p
)
1218 /* Look up the page on which the object is alloced. If the object
1219 wasn't allocated by the collector, we'll probably die. */
1220 entry
= lookup_page_table_entry (p
);
1221 #ifdef ENABLE_CHECKING
1226 /* Calculate the index of the object on the page; this is its bit
1227 position in the in_use_p bitmap. */
1228 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1229 word
= bit
/ HOST_BITS_PER_LONG
;
1230 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1232 /* If the bit was previously set, skip it. */
1233 if (entry
->in_use_p
[word
] & mask
)
1236 /* Otherwise set it, and decrement the free object count. */
1237 entry
->in_use_p
[word
] |= mask
;
1238 entry
->num_free_objects
-= 1;
1240 if (GGC_DEBUG_LEVEL
>= 4)
1241 fprintf (G
.debug_file
, "Marking %p\n", p
);
1246 /* Return 1 if P has been marked, zero otherwise.
1247 P must have been allocated by the GC allocator; it mustn't point to
1248 static objects, stack variables, or memory allocated with malloc. */
1251 ggc_marked_p (const void *p
)
1257 /* Look up the page on which the object is alloced. If the object
1258 wasn't allocated by the collector, we'll probably die. */
1259 entry
= lookup_page_table_entry (p
);
1260 #ifdef ENABLE_CHECKING
1265 /* Calculate the index of the object on the page; this is its bit
1266 position in the in_use_p bitmap. */
1267 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1268 word
= bit
/ HOST_BITS_PER_LONG
;
1269 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1271 return (entry
->in_use_p
[word
] & mask
) != 0;
1274 /* Return the size of the gc-able object P. */
1277 ggc_get_size (const void *p
)
1279 page_entry
*pe
= lookup_page_table_entry (p
);
1280 return OBJECT_SIZE (pe
->order
);
1283 /* Subroutine of init_ggc which computes the pair of numbers used to
1284 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1286 This algorithm is taken from Granlund and Montgomery's paper
1287 "Division by Invariant Integers using Multiplication"
1288 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1292 compute_inverse (unsigned order
)
1297 size
= OBJECT_SIZE (order
);
1299 while (size
% 2 == 0)
1306 while (inv
* size
!= 1)
1307 inv
= inv
* (2 - inv
*size
);
1309 DIV_MULT (order
) = inv
;
1310 DIV_SHIFT (order
) = e
;
1313 /* Initialize the ggc-mmap allocator. */
1319 G
.pagesize
= getpagesize();
1320 G
.lg_pagesize
= exact_log2 (G
.pagesize
);
1322 #ifdef HAVE_MMAP_DEV_ZERO
1323 G
.dev_zero_fd
= open ("/dev/zero", O_RDONLY
);
1324 if (G
.dev_zero_fd
== -1)
1325 internal_error ("open /dev/zero: %m");
1329 G
.debug_file
= fopen ("ggc-mmap.debug", "w");
1331 G
.debug_file
= stdout
;
1335 /* StunOS has an amazing off-by-one error for the first mmap allocation
1336 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1337 believe, is an unaligned page allocation, which would cause us to
1338 hork badly if we tried to use it. */
1340 char *p
= alloc_anon (NULL
, G
.pagesize
);
1341 struct page_entry
*e
;
1342 if ((size_t)p
& (G
.pagesize
- 1))
1344 /* How losing. Discard this one and try another. If we still
1345 can't get something useful, give up. */
1347 p
= alloc_anon (NULL
, G
.pagesize
);
1348 if ((size_t)p
& (G
.pagesize
- 1))
1352 /* We have a good page, might as well hold onto it... */
1353 e
= xcalloc (1, sizeof (struct page_entry
));
1354 e
->bytes
= G
.pagesize
;
1356 e
->next
= G
.free_pages
;
1361 /* Initialize the object size table. */
1362 for (order
= 0; order
< HOST_BITS_PER_PTR
; ++order
)
1363 object_size_table
[order
] = (size_t) 1 << order
;
1364 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1366 size_t s
= extra_order_size_table
[order
- HOST_BITS_PER_PTR
];
1368 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1369 so that we're sure of getting aligned memory. */
1370 s
= ROUND_UP (s
, MAX_ALIGNMENT
);
1371 object_size_table
[order
] = s
;
1374 /* Initialize the objects-per-page and inverse tables. */
1375 for (order
= 0; order
< NUM_ORDERS
; ++order
)
1377 objects_per_page_table
[order
] = G
.pagesize
/ OBJECT_SIZE (order
);
1378 if (objects_per_page_table
[order
] == 0)
1379 objects_per_page_table
[order
] = 1;
1380 compute_inverse (order
);
1383 /* Reset the size_lookup array to put appropriately sized objects in
1384 the special orders. All objects bigger than the previous power
1385 of two, but no greater than the special size, should go in the
1387 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1392 o
= size_lookup
[OBJECT_SIZE (order
)];
1393 for (i
= OBJECT_SIZE (order
); size_lookup
[i
] == o
; --i
)
1394 size_lookup
[i
] = order
;
1399 G
.depth
= xmalloc (G
.depth_max
* sizeof (unsigned int));
1401 G
.by_depth_in_use
= 0;
1402 G
.by_depth_max
= INITIAL_PTE_COUNT
;
1403 G
.by_depth
= xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
1404 G
.save_in_use
= xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
1407 /* Start a new GGC zone. */
1410 new_ggc_zone (const char *name ATTRIBUTE_UNUSED
)
1415 /* Destroy a GGC zone. */
1417 destroy_ggc_zone (struct alloc_zone
*zone ATTRIBUTE_UNUSED
)
1421 /* Increment the `GC context'. Objects allocated in an outer context
1422 are never freed, eliminating the need to register their roots. */
1425 ggc_push_context (void)
1430 if (G
.context_depth
>= HOST_BITS_PER_LONG
)
1434 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1435 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1438 ggc_recalculate_in_use_p (page_entry
*p
)
1443 /* Because the past-the-end bit in in_use_p is always set, we
1444 pretend there is one additional object. */
1445 num_objects
= OBJECTS_IN_PAGE (p
) + 1;
1447 /* Reset the free object count. */
1448 p
->num_free_objects
= num_objects
;
1450 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1452 i
< CEIL (BITMAP_SIZE (num_objects
),
1453 sizeof (*p
->in_use_p
));
1458 /* Something is in use if it is marked, or if it was in use in a
1459 context further down the context stack. */
1460 p
->in_use_p
[i
] |= save_in_use_p (p
)[i
];
1462 /* Decrement the free object count for every object allocated. */
1463 for (j
= p
->in_use_p
[i
]; j
; j
>>= 1)
1464 p
->num_free_objects
-= (j
& 1);
1467 if (p
->num_free_objects
>= num_objects
)
1471 /* Decrement the `GC context'. All objects allocated since the
1472 previous ggc_push_context are migrated to the outer context. */
1475 ggc_pop_context (void)
1477 unsigned long omask
;
1478 unsigned int depth
, i
, e
;
1479 #ifdef ENABLE_CHECKING
1483 depth
= --G
.context_depth
;
1484 omask
= (unsigned long)1 << (depth
+ 1);
1486 if (!((G
.context_depth_allocations
| G
.context_depth_collections
) & omask
))
1489 G
.context_depth_allocations
|= (G
.context_depth_allocations
& omask
) >> 1;
1490 G
.context_depth_allocations
&= omask
- 1;
1491 G
.context_depth_collections
&= omask
- 1;
1493 /* The G.depth array is shortened so that the last index is the
1494 context_depth of the top element of by_depth. */
1495 if (depth
+1 < G
.depth_in_use
)
1496 e
= G
.depth
[depth
+1];
1498 e
= G
.by_depth_in_use
;
1500 /* We might not have any PTEs of depth depth. */
1501 if (depth
< G
.depth_in_use
)
1504 /* First we go through all the pages at depth depth to
1505 recalculate the in use bits. */
1506 for (i
= G
.depth
[depth
]; i
< e
; ++i
)
1510 #ifdef ENABLE_CHECKING
1513 /* Check that all of the pages really are at the depth that
1515 if (p
->context_depth
!= depth
)
1517 if (p
->index_by_depth
!= i
)
1521 prefetch (&save_in_use_p_i (i
+8));
1522 prefetch (&save_in_use_p_i (i
+16));
1523 if (save_in_use_p_i (i
))
1526 ggc_recalculate_in_use_p (p
);
1527 free (save_in_use_p_i (i
));
1528 save_in_use_p_i (i
) = 0;
1533 /* Then, we reset all page_entries with a depth greater than depth
1535 for (i
= e
; i
< G
.by_depth_in_use
; ++i
)
1537 page_entry
*p
= G
.by_depth
[i
];
1539 /* Check that all of the pages really are at the depth we
1541 #ifdef ENABLE_CHECKING
1542 if (p
->context_depth
<= depth
)
1544 if (p
->index_by_depth
!= i
)
1547 p
->context_depth
= depth
;
1552 #ifdef ENABLE_CHECKING
1553 for (order
= 2; order
< NUM_ORDERS
; order
++)
1557 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1559 if (p
->context_depth
> depth
)
1561 else if (p
->context_depth
== depth
&& save_in_use_p (p
))
1568 /* Unmark all objects. */
1575 for (order
= 2; order
< NUM_ORDERS
; order
++)
1579 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1581 size_t num_objects
= OBJECTS_IN_PAGE (p
);
1582 size_t bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
1584 #ifdef ENABLE_CHECKING
1585 /* The data should be page-aligned. */
1586 if ((size_t) p
->page
& (G
.pagesize
- 1))
1590 /* Pages that aren't in the topmost context are not collected;
1591 nevertheless, we need their in-use bit vectors to store GC
1592 marks. So, back them up first. */
1593 if (p
->context_depth
< G
.context_depth
)
1595 if (! save_in_use_p (p
))
1596 save_in_use_p (p
) = xmalloc (bitmap_size
);
1597 memcpy (save_in_use_p (p
), p
->in_use_p
, bitmap_size
);
1600 /* Reset reset the number of free objects and clear the
1601 in-use bits. These will be adjusted by mark_obj. */
1602 p
->num_free_objects
= num_objects
;
1603 memset (p
->in_use_p
, 0, bitmap_size
);
1605 /* Make sure the one-past-the-end bit is always set. */
1606 p
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
1607 = ((unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
));
1612 /* Free all empty pages. Partially empty pages need no attention
1613 because the `mark' bit doubles as an `unused' bit. */
1620 for (order
= 2; order
< NUM_ORDERS
; order
++)
1622 /* The last page-entry to consider, regardless of entries
1623 placed at the end of the list. */
1624 page_entry
* const last
= G
.page_tails
[order
];
1627 size_t live_objects
;
1628 page_entry
*p
, *previous
;
1638 page_entry
*next
= p
->next
;
1640 /* Loop until all entries have been examined. */
1643 num_objects
= OBJECTS_IN_PAGE (p
);
1645 /* Add all live objects on this page to the count of
1646 allocated memory. */
1647 live_objects
= num_objects
- p
->num_free_objects
;
1649 G
.allocated
+= OBJECT_SIZE (order
) * live_objects
;
1651 /* Only objects on pages in the topmost context should get
1653 if (p
->context_depth
< G
.context_depth
)
1656 /* Remove the page if it's empty. */
1657 else if (live_objects
== 0)
1660 G
.pages
[order
] = next
;
1662 previous
->next
= next
;
1664 /* Are we removing the last element? */
1665 if (p
== G
.page_tails
[order
])
1666 G
.page_tails
[order
] = previous
;
1671 /* If the page is full, move it to the end. */
1672 else if (p
->num_free_objects
== 0)
1674 /* Don't move it if it's already at the end. */
1675 if (p
!= G
.page_tails
[order
])
1677 /* Move p to the end of the list. */
1679 G
.page_tails
[order
]->next
= p
;
1681 /* Update the tail pointer... */
1682 G
.page_tails
[order
] = p
;
1684 /* ... and the head pointer, if necessary. */
1686 G
.pages
[order
] = next
;
1688 previous
->next
= next
;
1693 /* If we've fallen through to here, it's a page in the
1694 topmost context that is neither full nor empty. Such a
1695 page must precede pages at lesser context depth in the
1696 list, so move it to the head. */
1697 else if (p
!= G
.pages
[order
])
1699 previous
->next
= p
->next
;
1700 p
->next
= G
.pages
[order
];
1702 /* Are we moving the last element? */
1703 if (G
.page_tails
[order
] == p
)
1704 G
.page_tails
[order
] = previous
;
1713 /* Now, restore the in_use_p vectors for any pages from contexts
1714 other than the current one. */
1715 for (p
= G
.pages
[order
]; p
; p
= p
->next
)
1716 if (p
->context_depth
!= G
.context_depth
)
1717 ggc_recalculate_in_use_p (p
);
1721 #ifdef ENABLE_GC_CHECKING
1722 /* Clobber all free objects. */
1729 for (order
= 2; order
< NUM_ORDERS
; order
++)
1731 size_t size
= OBJECT_SIZE (order
);
1734 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1739 if (p
->context_depth
!= G
.context_depth
)
1740 /* Since we don't do any collection for pages in pushed
1741 contexts, there's no need to do any poisoning. And
1742 besides, the IN_USE_P array isn't valid until we pop
1746 num_objects
= OBJECTS_IN_PAGE (p
);
1747 for (i
= 0; i
< num_objects
; i
++)
1750 word
= i
/ HOST_BITS_PER_LONG
;
1751 bit
= i
% HOST_BITS_PER_LONG
;
1752 if (((p
->in_use_p
[word
] >> bit
) & 1) == 0)
1754 char *object
= p
->page
+ i
* size
;
1756 /* Keep poison-by-write when we expect to use Valgrind,
1757 so the exact same memory semantics is kept, in case
1758 there are memory errors. We override this request
1760 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (object
, size
));
1761 memset (object
, 0xa5, size
);
1763 /* Drop the handle to avoid handle leak. */
1764 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (object
, size
));
1772 /* Top level mark-and-sweep routine. */
1777 /* Avoid frequent unnecessary work by skipping collection if the
1778 total allocations haven't expanded much since the last
1780 float allocated_last_gc
=
1781 MAX (G
.allocated_last_gc
, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE
) * 1024);
1783 float min_expand
= allocated_last_gc
* PARAM_VALUE (GGC_MIN_EXPAND
) / 100;
1785 if (G
.allocated
< allocated_last_gc
+ min_expand
)
1788 timevar_push (TV_GC
);
1790 fprintf (stderr
, " {GC %luk -> ", (unsigned long) G
.allocated
/ 1024);
1792 /* Zero the total allocated bytes. This will be recalculated in the
1796 /* Release the pages we freed the last time we collected, but didn't
1797 reuse in the interim. */
1800 /* Indicate that we've seen collections at this context depth. */
1801 G
.context_depth_collections
= ((unsigned long)1 << (G
.context_depth
+ 1)) - 1;
1806 #ifdef ENABLE_GC_CHECKING
1812 G
.allocated_last_gc
= G
.allocated
;
1814 timevar_pop (TV_GC
);
1817 fprintf (stderr
, "%luk}", (unsigned long) G
.allocated
/ 1024);
1820 /* Print allocation statistics. */
1821 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
1823 : ((x) < 1024*1024*10 \
1825 : (x) / (1024*1024))))
1826 #define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
1829 ggc_print_statistics (void)
1831 struct ggc_statistics stats
;
1833 size_t total_overhead
= 0;
1835 /* Clear the statistics. */
1836 memset (&stats
, 0, sizeof (stats
));
1838 /* Make sure collection will really occur. */
1839 G
.allocated_last_gc
= 0;
1841 /* Collect and print the statistics common across collectors. */
1842 ggc_print_common_statistics (stderr
, &stats
);
1844 /* Release free pages so that we will not count the bytes allocated
1845 there as part of the total allocated memory. */
1848 /* Collect some information about the various sizes of
1851 "Memory still allocated at the end of the compilation process\n");
1852 fprintf (stderr
, "%-5s %10s %10s %10s\n",
1853 "Size", "Allocated", "Used", "Overhead");
1854 for (i
= 0; i
< NUM_ORDERS
; ++i
)
1861 /* Skip empty entries. */
1865 overhead
= allocated
= in_use
= 0;
1867 /* Figure out the total number of bytes allocated for objects of
1868 this size, and how many of them are actually in use. Also figure
1869 out how much memory the page table is using. */
1870 for (p
= G
.pages
[i
]; p
; p
= p
->next
)
1872 allocated
+= p
->bytes
;
1874 (OBJECTS_IN_PAGE (p
) - p
->num_free_objects
) * OBJECT_SIZE (i
);
1876 overhead
+= (sizeof (page_entry
) - sizeof (long)
1877 + BITMAP_SIZE (OBJECTS_IN_PAGE (p
) + 1));
1879 fprintf (stderr
, "%-5lu %10lu%c %10lu%c %10lu%c\n",
1880 (unsigned long) OBJECT_SIZE (i
),
1881 SCALE (allocated
), LABEL (allocated
),
1882 SCALE (in_use
), LABEL (in_use
),
1883 SCALE (overhead
), LABEL (overhead
));
1884 total_overhead
+= overhead
;
1886 fprintf (stderr
, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
1887 SCALE (G
.bytes_mapped
), LABEL (G
.bytes_mapped
),
1888 SCALE (G
.allocated
), LABEL(G
.allocated
),
1889 SCALE (total_overhead
), LABEL (total_overhead
));
1891 #ifdef GATHER_STATISTICS
1893 fprintf (stderr
, "\nTotal allocations and overheads during the compilation process\n");
1895 fprintf (stderr
, "Total Overhead: %10lld\n",
1896 G
.stats
.total_overhead
);
1897 fprintf (stderr
, "Total Allocated: %10lld\n",
1898 G
.stats
.total_allocated
);
1900 fprintf (stderr
, "Total Overhead under 32B: %10lld\n",
1901 G
.stats
.total_overhead_under32
);
1902 fprintf (stderr
, "Total Allocated under 32B: %10lld\n",
1903 G
.stats
.total_allocated_under32
);
1904 fprintf (stderr
, "Total Overhead under 64B: %10lld\n",
1905 G
.stats
.total_overhead_under64
);
1906 fprintf (stderr
, "Total Allocated under 64B: %10lld\n",
1907 G
.stats
.total_allocated_under64
);
1908 fprintf (stderr
, "Total Overhead under 128B: %10lld\n",
1909 G
.stats
.total_overhead_under128
);
1910 fprintf (stderr
, "Total Allocated under 128B: %10lld\n",
1911 G
.stats
.total_allocated_under128
);
1913 for (i
= 0; i
< NUM_ORDERS
; i
++)
1914 if (G
.stats
.total_allocated_per_order
[i
])
1916 fprintf (stderr
, "Total Overhead page size %7d: %10lld\n",
1917 OBJECT_SIZE (i
), G
.stats
.total_overhead_per_order
[i
]);
1918 fprintf (stderr
, "Total Allocated page size %7d: %10lld\n",
1919 OBJECT_SIZE (i
), G
.stats
.total_allocated_per_order
[i
]);
1927 struct ggc_pch_ondisk
1929 unsigned totals
[NUM_ORDERS
];
1931 size_t base
[NUM_ORDERS
];
1932 size_t written
[NUM_ORDERS
];
1935 struct ggc_pch_data
*
1938 return xcalloc (sizeof (struct ggc_pch_data
), 1);
1942 ggc_pch_count_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
1943 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
1948 order
= size_lookup
[size
];
1952 while (size
> OBJECT_SIZE (order
))
1956 d
->d
.totals
[order
]++;
1960 ggc_pch_total_size (struct ggc_pch_data
*d
)
1965 for (i
= 0; i
< NUM_ORDERS
; i
++)
1966 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
1971 ggc_pch_this_base (struct ggc_pch_data
*d
, void *base
)
1973 size_t a
= (size_t) base
;
1976 for (i
= 0; i
< NUM_ORDERS
; i
++)
1979 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
1985 ggc_pch_alloc_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
1986 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
1992 order
= size_lookup
[size
];
1996 while (size
> OBJECT_SIZE (order
))
2000 result
= (char *) d
->base
[order
];
2001 d
->base
[order
] += OBJECT_SIZE (order
);
2006 ggc_pch_prepare_write (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2007 FILE *f ATTRIBUTE_UNUSED
)
2009 /* Nothing to do. */
2013 ggc_pch_write_object (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2014 FILE *f
, void *x
, void *newx ATTRIBUTE_UNUSED
,
2015 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
2018 static const char emptyBytes
[256];
2021 order
= size_lookup
[size
];
2025 while (size
> OBJECT_SIZE (order
))
2029 if (fwrite (x
, size
, 1, f
) != 1)
2030 fatal_error ("can't write PCH file: %m");
2032 /* If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
2033 object out to OBJECT_SIZE(order). This happens for strings. */
2035 if (size
!= OBJECT_SIZE (order
))
2037 unsigned padding
= OBJECT_SIZE(order
) - size
;
2039 /* To speed small writes, we use a nulled-out array that's larger
2040 than most padding requests as the source for our null bytes. This
2041 permits us to do the padding with fwrite() rather than fseek(), and
2042 limits the chance the the OS may try to flush any outstanding
2044 if (padding
<= sizeof(emptyBytes
))
2046 if (fwrite (emptyBytes
, 1, padding
, f
) != padding
)
2047 fatal_error ("can't write PCH file");
2051 /* Larger than our buffer? Just default to fseek. */
2052 if (fseek (f
, padding
, SEEK_CUR
) != 0)
2053 fatal_error ("can't write PCH file");
2057 d
->written
[order
]++;
2058 if (d
->written
[order
] == d
->d
.totals
[order
]
2059 && fseek (f
, ROUND_UP_VALUE (d
->d
.totals
[order
] * OBJECT_SIZE (order
),
2062 fatal_error ("can't write PCH file: %m");
2066 ggc_pch_finish (struct ggc_pch_data
*d
, FILE *f
)
2068 if (fwrite (&d
->d
, sizeof (d
->d
), 1, f
) != 1)
2069 fatal_error ("can't write PCH file: %m");
2073 /* Move the PCH PTE entries just added to the end of by_depth, to the
2077 move_ptes_to_front (int count_old_page_tables
, int count_new_page_tables
)
2081 /* First, we swap the new entries to the front of the varrays. */
2082 page_entry
**new_by_depth
;
2083 unsigned long **new_save_in_use
;
2085 new_by_depth
= xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
2086 new_save_in_use
= xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
2088 memcpy (&new_by_depth
[0],
2089 &G
.by_depth
[count_old_page_tables
],
2090 count_new_page_tables
* sizeof (void *));
2091 memcpy (&new_by_depth
[count_new_page_tables
],
2093 count_old_page_tables
* sizeof (void *));
2094 memcpy (&new_save_in_use
[0],
2095 &G
.save_in_use
[count_old_page_tables
],
2096 count_new_page_tables
* sizeof (void *));
2097 memcpy (&new_save_in_use
[count_new_page_tables
],
2099 count_old_page_tables
* sizeof (void *));
2102 free (G
.save_in_use
);
2104 G
.by_depth
= new_by_depth
;
2105 G
.save_in_use
= new_save_in_use
;
2107 /* Now update all the index_by_depth fields. */
2108 for (i
= G
.by_depth_in_use
; i
> 0; --i
)
2110 page_entry
*p
= G
.by_depth
[i
-1];
2111 p
->index_by_depth
= i
-1;
2114 /* And last, we update the depth pointers in G.depth. The first
2115 entry is already 0, and context 0 entries always start at index
2116 0, so there is nothing to update in the first slot. We need a
2117 second slot, only if we have old ptes, and if we do, they start
2118 at index count_new_page_tables. */
2119 if (count_old_page_tables
)
2120 push_depth (count_new_page_tables
);
2124 ggc_pch_read (FILE *f
, void *addr
)
2126 struct ggc_pch_ondisk d
;
2129 unsigned long count_old_page_tables
;
2130 unsigned long count_new_page_tables
;
2132 count_old_page_tables
= G
.by_depth_in_use
;
2134 /* We've just read in a PCH file. So, every object that used to be
2135 allocated is now free. */
2137 #ifdef ENABLE_GC_CHECKING
2141 /* No object read from a PCH file should ever be freed. So, set the
2142 context depth to 1, and set the depth of all the currently-allocated
2143 pages to be 1 too. PCH pages will have depth 0. */
2144 if (G
.context_depth
!= 0)
2146 G
.context_depth
= 1;
2147 for (i
= 0; i
< NUM_ORDERS
; i
++)
2150 for (p
= G
.pages
[i
]; p
!= NULL
; p
= p
->next
)
2151 p
->context_depth
= G
.context_depth
;
2154 /* Allocate the appropriate page-table entries for the pages read from
2156 if (fread (&d
, sizeof (d
), 1, f
) != 1)
2157 fatal_error ("can't read PCH file: %m");
2159 for (i
= 0; i
< NUM_ORDERS
; i
++)
2161 struct page_entry
*entry
;
2167 if (d
.totals
[i
] == 0)
2170 bytes
= ROUND_UP (d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2171 num_objs
= bytes
/ OBJECT_SIZE (i
);
2172 entry
= xcalloc (1, (sizeof (struct page_entry
)
2174 + BITMAP_SIZE (num_objs
+ 1)));
2175 entry
->bytes
= bytes
;
2177 entry
->context_depth
= 0;
2179 entry
->num_free_objects
= 0;
2183 j
+ HOST_BITS_PER_LONG
<= num_objs
+ 1;
2184 j
+= HOST_BITS_PER_LONG
)
2185 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
] = -1;
2186 for (; j
< num_objs
+ 1; j
++)
2187 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
]
2188 |= 1L << (j
% HOST_BITS_PER_LONG
);
2190 for (pte
= entry
->page
;
2191 pte
< entry
->page
+ entry
->bytes
;
2193 set_page_table_entry (pte
, entry
);
2195 if (G
.page_tails
[i
] != NULL
)
2196 G
.page_tails
[i
]->next
= entry
;
2199 G
.page_tails
[i
] = entry
;
2201 /* We start off by just adding all the new information to the
2202 end of the varrays, later, we will move the new information
2203 to the front of the varrays, as the PCH page tables are at
2205 push_by_depth (entry
, 0);
2208 /* Now, we update the various data structures that speed page table
2210 count_new_page_tables
= G
.by_depth_in_use
- count_old_page_tables
;
2212 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
);
2214 /* Update the statistics. */
2215 G
.allocated
= G
.allocated_last_gc
= offs
- (char *)addr
;