1 /* "Bag-of-pages" garbage collector for the GNU compiler.
2 Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
24 #include "coretypes.h"
34 #include "tree-flow.h"
35 #ifdef ENABLE_VALGRIND_CHECKING
36 # ifdef HAVE_VALGRIND_MEMCHECK_H
37 # include <valgrind/memcheck.h>
38 # elif defined HAVE_MEMCHECK_H
39 # include <memcheck.h>
41 # include <valgrind.h>
44 /* Avoid #ifdef:s when we can help it. */
45 #define VALGRIND_DISCARD(x)
48 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
49 file open. Prefer either to valloc. */
51 # undef HAVE_MMAP_DEV_ZERO
53 # include <sys/mman.h>
55 # define MAP_FAILED -1
57 # if !defined (MAP_ANONYMOUS) && defined (MAP_ANON)
58 # define MAP_ANONYMOUS MAP_ANON
64 #ifdef HAVE_MMAP_DEV_ZERO
66 # include <sys/mman.h>
68 # define MAP_FAILED -1
75 #define USING_MALLOC_PAGE_GROUPS
80 This garbage-collecting allocator allocates objects on one of a set
81 of pages. Each page can allocate objects of a single size only;
82 available sizes are powers of two starting at four bytes. The size
83 of an allocation request is rounded up to the next power of two
84 (`order'), and satisfied from the appropriate page.
86 Each page is recorded in a page-entry, which also maintains an
87 in-use bitmap of object positions on the page. This allows the
88 allocation state of a particular object to be flipped without
89 touching the page itself.
91 Each page-entry also has a context depth, which is used to track
92 pushing and popping of allocation contexts. Only objects allocated
93 in the current (highest-numbered) context may be collected.
95 Page entries are arranged in an array of singly-linked lists. The
96 array is indexed by the allocation size, in bits, of the pages on
97 it; i.e. all pages on a list allocate objects of the same size.
98 Pages are ordered on the list such that all non-full pages precede
99 all full pages, with non-full pages arranged in order of decreasing
102 Empty pages (of all orders) are kept on a single page cache list,
103 and are considered first when new pages are required; they are
104 deallocated at the start of the next collection if they haven't
105 been recycled by then. */
107 /* Define GGC_DEBUG_LEVEL to print debugging information.
108 0: No debugging output.
109 1: GC statistics only.
110 2: Page-entry allocations/deallocations as well.
111 3: Object allocations as well.
112 4: Object marks as well. */
113 #define GGC_DEBUG_LEVEL (0)
115 #ifndef HOST_BITS_PER_PTR
116 #define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
120 /* A two-level tree is used to look up the page-entry for a given
121 pointer. Two chunks of the pointer's bits are extracted to index
122 the first and second levels of the tree, as follows:
126 msb +----------------+----+------+------+ lsb
132 The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
133 pages are aligned on system page boundaries. The next most
134 significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
135 index values in the lookup table, respectively.
137 For 32-bit architectures and the settings below, there are no
138 leftover bits. For architectures with wider pointers, the lookup
139 tree points to a list of pages, which must be scanned to find the
142 #define PAGE_L1_BITS (8)
143 #define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
144 #define PAGE_L1_SIZE ((size_t) 1 << PAGE_L1_BITS)
145 #define PAGE_L2_SIZE ((size_t) 1 << PAGE_L2_BITS)
147 #define LOOKUP_L1(p) \
148 (((size_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
150 #define LOOKUP_L2(p) \
151 (((size_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
153 /* The number of objects per allocation page, for objects on a page of
154 the indicated ORDER. */
155 #define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
157 /* The number of objects in P. */
158 #define OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
160 /* The size of an object on a page of the indicated ORDER. */
161 #define OBJECT_SIZE(ORDER) object_size_table[ORDER]
163 /* For speed, we avoid doing a general integer divide to locate the
164 offset in the allocation bitmap, by precalculating numbers M, S
165 such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
166 within the page which is evenly divisible by the object size Z. */
167 #define DIV_MULT(ORDER) inverse_table[ORDER].mult
168 #define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
169 #define OFFSET_TO_BIT(OFFSET, ORDER) \
170 (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
172 /* The number of extra orders, not corresponding to power-of-two sized
175 #define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
177 #define RTL_SIZE(NSLOTS) \
178 (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))
180 #define TREE_EXP_SIZE(OPS) \
181 (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
183 /* The Ith entry is the maximum size of an object to be stored in the
184 Ith extra order. Adding a new entry to this array is the *only*
185 thing you need to do to add a new special allocation size. */
187 static const size_t extra_order_size_table
[] = {
188 sizeof (struct stmt_ann_d
),
189 sizeof (struct tree_decl
),
190 sizeof (struct tree_list
),
192 RTL_SIZE (2), /* MEM, PLUS, etc. */
193 RTL_SIZE (9), /* INSN */
196 /* The total number of orders. */
198 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
200 /* We use this structure to determine the alignment required for
201 allocations. For power-of-two sized allocations, that's not a
202 problem, but it does matter for odd-sized allocations. */
204 struct max_alignment
{
212 /* The biggest alignment required. */
214 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
216 /* Compute the smallest nonnegative number which when added to X gives
219 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
221 /* Compute the smallest multiple of F that is >= X. */
223 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
225 /* The Ith entry is the number of objects on a page or order I. */
227 static unsigned objects_per_page_table
[NUM_ORDERS
];
229 /* The Ith entry is the size of an object on a page of order I. */
231 static size_t object_size_table
[NUM_ORDERS
];
233 /* The Ith entry is a pair of numbers (mult, shift) such that
234 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
235 for all k evenly divisible by OBJECT_SIZE(I). */
242 inverse_table
[NUM_ORDERS
];
244 /* A page_entry records the status of an allocation page. This
245 structure is dynamically sized to fit the bitmap in_use_p. */
246 typedef struct page_entry
248 /* The next page-entry with objects of the same size, or NULL if
249 this is the last page-entry. */
250 struct page_entry
*next
;
252 /* The previous page-entry with objects of the same size, or NULL if
253 this is the first page-entry. The PREV pointer exists solely to
254 keep the cost of ggc_free manageable. */
255 struct page_entry
*prev
;
257 /* The number of bytes allocated. (This will always be a multiple
258 of the host system page size.) */
261 /* The address at which the memory is allocated. */
264 #ifdef USING_MALLOC_PAGE_GROUPS
265 /* Back pointer to the page group this page came from. */
266 struct page_group
*group
;
269 /* This is the index in the by_depth varray where this page table
271 unsigned long index_by_depth
;
273 /* Context depth of this page. */
274 unsigned short context_depth
;
276 /* The number of free objects remaining on this page. */
277 unsigned short num_free_objects
;
279 /* A likely candidate for the bit position of a free object for the
280 next allocation from this page. */
281 unsigned short next_bit_hint
;
283 /* The lg of size of objects allocated from this page. */
286 /* A bit vector indicating whether or not objects are in use. The
287 Nth bit is one if the Nth object on this page is allocated. This
288 array is dynamically sized. */
289 unsigned long in_use_p
[1];
292 #ifdef USING_MALLOC_PAGE_GROUPS
293 /* A page_group describes a large allocation from malloc, from which
294 we parcel out aligned pages. */
295 typedef struct page_group
297 /* A linked list of all extant page groups. */
298 struct page_group
*next
;
300 /* The address we received from malloc. */
303 /* The size of the block. */
306 /* A bitmask of pages in use. */
311 #if HOST_BITS_PER_PTR <= 32
313 /* On 32-bit hosts, we use a two level page table, as pictured above. */
314 typedef page_entry
**page_table
[PAGE_L1_SIZE
];
318 /* On 64-bit hosts, we use the same two level page tables plus a linked
319 list that disambiguates the top 32-bits. There will almost always be
320 exactly one entry in the list. */
321 typedef struct page_table_chain
323 struct page_table_chain
*next
;
325 page_entry
**table
[PAGE_L1_SIZE
];
330 /* The rest of the global variables. */
331 static struct globals
333 /* The Nth element in this array is a page with objects of size 2^N.
334 If there are any pages with free objects, they will be at the
335 head of the list. NULL if there are no page-entries for this
337 page_entry
*pages
[NUM_ORDERS
];
339 /* The Nth element in this array is the last page with objects of
340 size 2^N. NULL if there are no page-entries for this object
342 page_entry
*page_tails
[NUM_ORDERS
];
344 /* Lookup table for associating allocation pages with object addresses. */
347 /* The system's page size. */
351 /* Bytes currently allocated. */
354 /* Bytes currently allocated at the end of the last collection. */
355 size_t allocated_last_gc
;
357 /* Total amount of memory mapped. */
360 /* Bit N set if any allocations have been done at context depth N. */
361 unsigned long context_depth_allocations
;
363 /* Bit N set if any collections have been done at context depth N. */
364 unsigned long context_depth_collections
;
366 /* The current depth in the context stack. */
367 unsigned short context_depth
;
369 /* A file descriptor open to /dev/zero for reading. */
370 #if defined (HAVE_MMAP_DEV_ZERO)
374 /* A cache of free system pages. */
375 page_entry
*free_pages
;
377 #ifdef USING_MALLOC_PAGE_GROUPS
378 page_group
*page_groups
;
381 /* The file descriptor for debugging output. */
384 /* Current number of elements in use in depth below. */
385 unsigned int depth_in_use
;
387 /* Maximum number of elements that can be used before resizing. */
388 unsigned int depth_max
;
390 /* Each element of this arry is an index in by_depth where the given
391 depth starts. This structure is indexed by that given depth we
392 are interested in. */
395 /* Current number of elements in use in by_depth below. */
396 unsigned int by_depth_in_use
;
398 /* Maximum number of elements that can be used before resizing. */
399 unsigned int by_depth_max
;
401 /* Each element of this array is a pointer to a page_entry, all
402 page_entries can be found in here by increasing depth.
403 index_by_depth in the page_entry is the index into this data
404 structure where that page_entry can be found. This is used to
405 speed up finding all page_entries at a particular depth. */
406 page_entry
**by_depth
;
408 /* Each element is a pointer to the saved in_use_p bits, if any,
409 zero otherwise. We allocate them all together, to enable a
410 better runtime data access pattern. */
411 unsigned long **save_in_use
;
413 #ifdef ENABLE_GC_ALWAYS_COLLECT
414 /* List of free objects to be verified as actually free on the
419 struct free_object
*next
;
423 #ifdef GATHER_STATISTICS
426 /* Total memory allocated with ggc_alloc. */
427 unsigned long long total_allocated
;
428 /* Total overhead for memory to be allocated with ggc_alloc. */
429 unsigned long long total_overhead
;
431 /* Total allocations and overhead for sizes less than 32, 64 and 128.
432 These sizes are interesting because they are typical cache line
435 unsigned long long total_allocated_under32
;
436 unsigned long long total_overhead_under32
;
438 unsigned long long total_allocated_under64
;
439 unsigned long long total_overhead_under64
;
441 unsigned long long total_allocated_under128
;
442 unsigned long long total_overhead_under128
;
444 /* The allocations for each of the allocation orders. */
445 unsigned long long total_allocated_per_order
[NUM_ORDERS
];
447 /* The overhead for each of the allocation orders. */
448 unsigned long long total_overhead_per_order
[NUM_ORDERS
];
453 /* The size in bytes required to maintain a bitmap for the objects
455 #define BITMAP_SIZE(Num_objects) \
456 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
458 /* Allocate pages in chunks of this size, to throttle calls to memory
459 allocation routines. The first page is used, the rest go onto the
460 free list. This cannot be larger than HOST_BITS_PER_INT for the
461 in_use bitmask for page_group. Hosts that need a different value
462 can override this by defining GGC_QUIRE_SIZE explicitly. */
463 #ifndef GGC_QUIRE_SIZE
465 # define GGC_QUIRE_SIZE 256
467 # define GGC_QUIRE_SIZE 16
471 /* Initial guess as to how many page table entries we might need. */
472 #define INITIAL_PTE_COUNT 128
474 static int ggc_allocated_p (const void *);
475 static page_entry
*lookup_page_table_entry (const void *);
476 static void set_page_table_entry (void *, page_entry
*);
478 static char *alloc_anon (char *, size_t);
480 #ifdef USING_MALLOC_PAGE_GROUPS
481 static size_t page_group_index (char *, char *);
482 static void set_page_group_in_use (page_group
*, char *);
483 static void clear_page_group_in_use (page_group
*, char *);
485 static struct page_entry
* alloc_page (unsigned);
486 static void free_page (struct page_entry
*);
487 static void release_pages (void);
488 static void clear_marks (void);
489 static void sweep_pages (void);
490 static void ggc_recalculate_in_use_p (page_entry
*);
491 static void compute_inverse (unsigned);
492 static inline void adjust_depth (void);
493 static void move_ptes_to_front (int, int);
495 void debug_print_page_list (int);
496 static void push_depth (unsigned int);
497 static void push_by_depth (page_entry
*, unsigned long *);
498 struct alloc_zone
*rtl_zone
= NULL
;
499 struct alloc_zone
*tree_zone
= NULL
;
500 struct alloc_zone
*garbage_zone
= NULL
;
502 /* Push an entry onto G.depth. */
505 push_depth (unsigned int i
)
507 if (G
.depth_in_use
>= G
.depth_max
)
510 G
.depth
= xrealloc (G
.depth
, G
.depth_max
* sizeof (unsigned int));
512 G
.depth
[G
.depth_in_use
++] = i
;
515 /* Push an entry onto G.by_depth and G.save_in_use. */
518 push_by_depth (page_entry
*p
, unsigned long *s
)
520 if (G
.by_depth_in_use
>= G
.by_depth_max
)
523 G
.by_depth
= xrealloc (G
.by_depth
,
524 G
.by_depth_max
* sizeof (page_entry
*));
525 G
.save_in_use
= xrealloc (G
.save_in_use
,
526 G
.by_depth_max
* sizeof (unsigned long *));
528 G
.by_depth
[G
.by_depth_in_use
] = p
;
529 G
.save_in_use
[G
.by_depth_in_use
++] = s
;
532 #if (GCC_VERSION < 3001)
533 #define prefetch(X) ((void) X)
535 #define prefetch(X) __builtin_prefetch (X)
538 #define save_in_use_p_i(__i) \
540 #define save_in_use_p(__p) \
541 (save_in_use_p_i (__p->index_by_depth))
543 /* Returns nonzero if P was allocated in GC'able memory. */
546 ggc_allocated_p (const void *p
)
551 #if HOST_BITS_PER_PTR <= 32
554 page_table table
= G
.lookup
;
555 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
560 if (table
->high_bits
== high_bits
)
564 base
= &table
->table
[0];
567 /* Extract the level 1 and 2 indices. */
571 return base
[L1
] && base
[L1
][L2
];
574 /* Traverse the page table and find the entry for a page.
575 Die (probably) if the object wasn't allocated via GC. */
577 static inline page_entry
*
578 lookup_page_table_entry (const void *p
)
583 #if HOST_BITS_PER_PTR <= 32
586 page_table table
= G
.lookup
;
587 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
588 while (table
->high_bits
!= high_bits
)
590 base
= &table
->table
[0];
593 /* Extract the level 1 and 2 indices. */
600 /* Set the page table entry for a page. */
603 set_page_table_entry (void *p
, page_entry
*entry
)
608 #if HOST_BITS_PER_PTR <= 32
612 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
613 for (table
= G
.lookup
; table
; table
= table
->next
)
614 if (table
->high_bits
== high_bits
)
617 /* Not found -- allocate a new table. */
618 table
= xcalloc (1, sizeof(*table
));
619 table
->next
= G
.lookup
;
620 table
->high_bits
= high_bits
;
623 base
= &table
->table
[0];
626 /* Extract the level 1 and 2 indices. */
630 if (base
[L1
] == NULL
)
631 base
[L1
] = xcalloc (PAGE_L2_SIZE
, sizeof (page_entry
*));
633 base
[L1
][L2
] = entry
;
636 /* Prints the page-entry for object size ORDER, for debugging. */
639 debug_print_page_list (int order
)
642 printf ("Head=%p, Tail=%p:\n", (void *) G
.pages
[order
],
643 (void *) G
.page_tails
[order
]);
647 printf ("%p(%1d|%3d) -> ", (void *) p
, p
->context_depth
,
648 p
->num_free_objects
);
656 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
657 (if non-null). The ifdef structure here is intended to cause a
658 compile error unless exactly one of the HAVE_* is defined. */
661 alloc_anon (char *pref ATTRIBUTE_UNUSED
, size_t size
)
663 #ifdef HAVE_MMAP_ANON
664 char *page
= mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
665 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
667 #ifdef HAVE_MMAP_DEV_ZERO
668 char *page
= mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
669 MAP_PRIVATE
, G
.dev_zero_fd
, 0);
672 if (page
== (char *) MAP_FAILED
)
674 perror ("virtual memory exhausted");
675 exit (FATAL_EXIT_CODE
);
678 /* Remember that we allocated this memory. */
679 G
.bytes_mapped
+= size
;
681 /* Pretend we don't have access to the allocated pages. We'll enable
682 access to smaller pieces of the area in ggc_alloc. Discard the
683 handle to avoid handle leak. */
684 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (page
, size
));
689 #ifdef USING_MALLOC_PAGE_GROUPS
690 /* Compute the index for this page into the page group. */
693 page_group_index (char *allocation
, char *page
)
695 return (size_t) (page
- allocation
) >> G
.lg_pagesize
;
698 /* Set and clear the in_use bit for this page in the page group. */
701 set_page_group_in_use (page_group
*group
, char *page
)
703 group
->in_use
|= 1 << page_group_index (group
->allocation
, page
);
707 clear_page_group_in_use (page_group
*group
, char *page
)
709 group
->in_use
&= ~(1 << page_group_index (group
->allocation
, page
));
713 /* Allocate a new page for allocating objects of size 2^ORDER,
714 and return an entry for it. The entry is not added to the
715 appropriate page_table list. */
717 static inline struct page_entry
*
718 alloc_page (unsigned order
)
720 struct page_entry
*entry
, *p
, **pp
;
724 size_t page_entry_size
;
726 #ifdef USING_MALLOC_PAGE_GROUPS
730 num_objects
= OBJECTS_PER_PAGE (order
);
731 bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
732 page_entry_size
= sizeof (page_entry
) - sizeof (long) + bitmap_size
;
733 entry_size
= num_objects
* OBJECT_SIZE (order
);
734 if (entry_size
< G
.pagesize
)
735 entry_size
= G
.pagesize
;
740 /* Check the list of free pages for one we can use. */
741 for (pp
= &G
.free_pages
, p
= *pp
; p
; pp
= &p
->next
, p
= *pp
)
742 if (p
->bytes
== entry_size
)
747 /* Recycle the allocated memory from this page ... */
751 #ifdef USING_MALLOC_PAGE_GROUPS
755 /* ... and, if possible, the page entry itself. */
756 if (p
->order
== order
)
759 memset (entry
, 0, page_entry_size
);
765 else if (entry_size
== G
.pagesize
)
767 /* We want just one page. Allocate a bunch of them and put the
768 extras on the freelist. (Can only do this optimization with
769 mmap for backing store.) */
770 struct page_entry
*e
, *f
= G
.free_pages
;
773 page
= alloc_anon (NULL
, G
.pagesize
* GGC_QUIRE_SIZE
);
775 /* This loop counts down so that the chain will be in ascending
777 for (i
= GGC_QUIRE_SIZE
- 1; i
>= 1; i
--)
779 e
= xcalloc (1, page_entry_size
);
781 e
->bytes
= G
.pagesize
;
782 e
->page
= page
+ (i
<< G
.lg_pagesize
);
790 page
= alloc_anon (NULL
, entry_size
);
792 #ifdef USING_MALLOC_PAGE_GROUPS
795 /* Allocate a large block of memory and serve out the aligned
796 pages therein. This results in much less memory wastage
797 than the traditional implementation of valloc. */
799 char *allocation
, *a
, *enda
;
800 size_t alloc_size
, head_slop
, tail_slop
;
801 int multiple_pages
= (entry_size
== G
.pagesize
);
804 alloc_size
= GGC_QUIRE_SIZE
* G
.pagesize
;
806 alloc_size
= entry_size
+ G
.pagesize
- 1;
807 allocation
= xmalloc (alloc_size
);
809 page
= (char *) (((size_t) allocation
+ G
.pagesize
- 1) & -G
.pagesize
);
810 head_slop
= page
- allocation
;
812 tail_slop
= ((size_t) allocation
+ alloc_size
) & (G
.pagesize
- 1);
814 tail_slop
= alloc_size
- entry_size
- head_slop
;
815 enda
= allocation
+ alloc_size
- tail_slop
;
817 /* We allocated N pages, which are likely not aligned, leaving
818 us with N-1 usable pages. We plan to place the page_group
819 structure somewhere in the slop. */
820 if (head_slop
>= sizeof (page_group
))
821 group
= (page_group
*)page
- 1;
824 /* We magically got an aligned allocation. Too bad, we have
825 to waste a page anyway. */
829 tail_slop
+= G
.pagesize
;
831 gcc_assert (tail_slop
>= sizeof (page_group
));
832 group
= (page_group
*)enda
;
833 tail_slop
-= sizeof (page_group
);
836 /* Remember that we allocated this memory. */
837 group
->next
= G
.page_groups
;
838 group
->allocation
= allocation
;
839 group
->alloc_size
= alloc_size
;
841 G
.page_groups
= group
;
842 G
.bytes_mapped
+= alloc_size
;
844 /* If we allocated multiple pages, put the rest on the free list. */
847 struct page_entry
*e
, *f
= G
.free_pages
;
848 for (a
= enda
- G
.pagesize
; a
!= page
; a
-= G
.pagesize
)
850 e
= xcalloc (1, page_entry_size
);
852 e
->bytes
= G
.pagesize
;
864 entry
= xcalloc (1, page_entry_size
);
866 entry
->bytes
= entry_size
;
868 entry
->context_depth
= G
.context_depth
;
869 entry
->order
= order
;
870 entry
->num_free_objects
= num_objects
;
871 entry
->next_bit_hint
= 1;
873 G
.context_depth_allocations
|= (unsigned long)1 << G
.context_depth
;
875 #ifdef USING_MALLOC_PAGE_GROUPS
876 entry
->group
= group
;
877 set_page_group_in_use (group
, page
);
880 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
881 increment the hint. */
882 entry
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
883 = (unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
);
885 set_page_table_entry (page
, entry
);
887 if (GGC_DEBUG_LEVEL
>= 2)
888 fprintf (G
.debug_file
,
889 "Allocating page at %p, object size=%lu, data %p-%p\n",
890 (void *) entry
, (unsigned long) OBJECT_SIZE (order
), page
,
891 page
+ entry_size
- 1);
896 /* Adjust the size of G.depth so that no index greater than the one
897 used by the top of the G.by_depth is used. */
904 if (G
.by_depth_in_use
)
906 top
= G
.by_depth
[G
.by_depth_in_use
-1];
908 /* Peel back indices in depth that index into by_depth, so that
909 as new elements are added to by_depth, we note the indices
910 of those elements, if they are for new context depths. */
911 while (G
.depth_in_use
> (size_t)top
->context_depth
+1)
916 /* For a page that is no longer needed, put it on the free page list. */
919 free_page (page_entry
*entry
)
921 if (GGC_DEBUG_LEVEL
>= 2)
922 fprintf (G
.debug_file
,
923 "Deallocating page at %p, data %p-%p\n", (void *) entry
,
924 entry
->page
, entry
->page
+ entry
->bytes
- 1);
926 /* Mark the page as inaccessible. Discard the handle to avoid handle
928 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (entry
->page
, entry
->bytes
));
930 set_page_table_entry (entry
->page
, NULL
);
932 #ifdef USING_MALLOC_PAGE_GROUPS
933 clear_page_group_in_use (entry
->group
, entry
->page
);
936 if (G
.by_depth_in_use
> 1)
938 page_entry
*top
= G
.by_depth
[G
.by_depth_in_use
-1];
939 int i
= entry
->index_by_depth
;
941 /* We cannot free a page from a context deeper than the current
943 gcc_assert (entry
->context_depth
== top
->context_depth
);
945 /* Put top element into freed slot. */
947 G
.save_in_use
[i
] = G
.save_in_use
[G
.by_depth_in_use
-1];
948 top
->index_by_depth
= i
;
954 entry
->next
= G
.free_pages
;
955 G
.free_pages
= entry
;
958 /* Release the free page cache to the system. */
964 page_entry
*p
, *next
;
968 /* Gather up adjacent pages so they are unmapped together. */
979 while (p
&& p
->page
== start
+ len
)
988 G
.bytes_mapped
-= len
;
993 #ifdef USING_MALLOC_PAGE_GROUPS
997 /* Remove all pages from free page groups from the list. */
999 while ((p
= *pp
) != NULL
)
1000 if (p
->group
->in_use
== 0)
1008 /* Remove all free page groups, and release the storage. */
1009 gp
= &G
.page_groups
;
1010 while ((g
= *gp
) != NULL
)
1014 G
.bytes_mapped
-= g
->alloc_size
;
1015 free (g
->allocation
);
1022 /* This table provides a fast way to determine ceil(log_2(size)) for
1023 allocation requests. The minimum allocation size is eight bytes. */
1025 static unsigned char size_lookup
[257] =
1027 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
1028 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1029 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1030 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1031 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1032 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1033 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1034 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1035 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1036 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1037 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1038 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1039 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1040 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1041 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1042 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1046 /* Typed allocation function. Does nothing special in this collector. */
1049 ggc_alloc_typed_stat (enum gt_types_enum type ATTRIBUTE_UNUSED
, size_t size
1052 return ggc_alloc_stat (size PASS_MEM_STAT
);
1055 /* Zone allocation function. Does nothing special in this collector. */
1058 ggc_alloc_zone_stat (size_t size
, struct alloc_zone
*zone ATTRIBUTE_UNUSED
1061 return ggc_alloc_stat (size PASS_MEM_STAT
);
1064 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1067 ggc_alloc_stat (size_t size MEM_STAT_DECL
)
1069 size_t order
, word
, bit
, object_offset
, object_size
;
1070 struct page_entry
*entry
;
1075 order
= size_lookup
[size
];
1076 object_size
= OBJECT_SIZE (order
);
1081 while (size
> (object_size
= OBJECT_SIZE (order
)))
1085 /* If there are non-full pages for this size allocation, they are at
1086 the head of the list. */
1087 entry
= G
.pages
[order
];
1089 /* If there is no page for this object size, or all pages in this
1090 context are full, allocate a new page. */
1091 if (entry
== NULL
|| entry
->num_free_objects
== 0)
1093 struct page_entry
*new_entry
;
1094 new_entry
= alloc_page (order
);
1096 new_entry
->index_by_depth
= G
.by_depth_in_use
;
1097 push_by_depth (new_entry
, 0);
1099 /* We can skip context depths, if we do, make sure we go all the
1100 way to the new depth. */
1101 while (new_entry
->context_depth
>= G
.depth_in_use
)
1102 push_depth (G
.by_depth_in_use
-1);
1104 /* If this is the only entry, it's also the tail. If it is not
1105 the only entry, then we must update the PREV pointer of the
1106 ENTRY (G.pages[order]) to point to our new page entry. */
1108 G
.page_tails
[order
] = new_entry
;
1110 entry
->prev
= new_entry
;
1112 /* Put new pages at the head of the page list. By definition the
1113 entry at the head of the list always has a NULL pointer. */
1114 new_entry
->next
= entry
;
1115 new_entry
->prev
= NULL
;
1117 G
.pages
[order
] = new_entry
;
1119 /* For a new page, we know the word and bit positions (in the
1120 in_use bitmap) of the first available object -- they're zero. */
1121 new_entry
->next_bit_hint
= 1;
1128 /* First try to use the hint left from the previous allocation
1129 to locate a clear bit in the in-use bitmap. We've made sure
1130 that the one-past-the-end bit is always set, so if the hint
1131 has run over, this test will fail. */
1132 unsigned hint
= entry
->next_bit_hint
;
1133 word
= hint
/ HOST_BITS_PER_LONG
;
1134 bit
= hint
% HOST_BITS_PER_LONG
;
1136 /* If the hint didn't work, scan the bitmap from the beginning. */
1137 if ((entry
->in_use_p
[word
] >> bit
) & 1)
1140 while (~entry
->in_use_p
[word
] == 0)
1143 #if GCC_VERSION >= 3004
1144 bit
= __builtin_ctzl (~entry
->in_use_p
[word
]);
1146 while ((entry
->in_use_p
[word
] >> bit
) & 1)
1150 hint
= word
* HOST_BITS_PER_LONG
+ bit
;
1153 /* Next time, try the next bit. */
1154 entry
->next_bit_hint
= hint
+ 1;
1156 object_offset
= hint
* object_size
;
1159 /* Set the in-use bit. */
1160 entry
->in_use_p
[word
] |= ((unsigned long) 1 << bit
);
1162 /* Keep a running total of the number of free objects. If this page
1163 fills up, we may have to move it to the end of the list if the
1164 next page isn't full. If the next page is full, all subsequent
1165 pages are full, so there's no need to move it. */
1166 if (--entry
->num_free_objects
== 0
1167 && entry
->next
!= NULL
1168 && entry
->next
->num_free_objects
> 0)
1170 /* We have a new head for the list. */
1171 G
.pages
[order
] = entry
->next
;
1173 /* We are moving ENTRY to the end of the page table list.
1174 The new page at the head of the list will have NULL in
1175 its PREV field and ENTRY will have NULL in its NEXT field. */
1176 entry
->next
->prev
= NULL
;
1179 /* Append ENTRY to the tail of the list. */
1180 entry
->prev
= G
.page_tails
[order
];
1181 G
.page_tails
[order
]->next
= entry
;
1182 G
.page_tails
[order
] = entry
;
1185 /* Calculate the object's address. */
1186 result
= entry
->page
+ object_offset
;
1187 #ifdef GATHER_STATISTICS
1188 ggc_record_overhead (OBJECT_SIZE (order
), OBJECT_SIZE (order
) - size
,
1189 result PASS_MEM_STAT
);
1192 #ifdef ENABLE_GC_CHECKING
1193 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1194 exact same semantics in presence of memory bugs, regardless of
1195 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1196 handle to avoid handle leak. */
1197 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, object_size
));
1199 /* `Poison' the entire allocated object, including any padding at
1201 memset (result
, 0xaf, object_size
);
1203 /* Make the bytes after the end of the object unaccessible. Discard the
1204 handle to avoid handle leak. */
1205 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) result
+ size
,
1206 object_size
- size
));
1209 /* Tell Valgrind that the memory is there, but its content isn't
1210 defined. The bytes at the end of the object are still marked
1212 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, size
));
1214 /* Keep track of how many bytes are being allocated. This
1215 information is used in deciding when to collect. */
1216 G
.allocated
+= object_size
;
1218 #ifdef GATHER_STATISTICS
1220 size_t overhead
= object_size
- size
;
1222 G
.stats
.total_overhead
+= overhead
;
1223 G
.stats
.total_allocated
+= object_size
;
1224 G
.stats
.total_overhead_per_order
[order
] += overhead
;
1225 G
.stats
.total_allocated_per_order
[order
] += object_size
;
1229 G
.stats
.total_overhead_under32
+= overhead
;
1230 G
.stats
.total_allocated_under32
+= object_size
;
1234 G
.stats
.total_overhead_under64
+= overhead
;
1235 G
.stats
.total_allocated_under64
+= object_size
;
1239 G
.stats
.total_overhead_under128
+= overhead
;
1240 G
.stats
.total_allocated_under128
+= object_size
;
1245 if (GGC_DEBUG_LEVEL
>= 3)
1246 fprintf (G
.debug_file
,
1247 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1248 (unsigned long) size
, (unsigned long) object_size
, result
,
1254 /* If P is not marked, marks it and return false. Otherwise return true.
1255 P must have been allocated by the GC allocator; it mustn't point to
1256 static objects, stack variables, or memory allocated with malloc. */
1259 ggc_set_mark (const void *p
)
1265 /* Look up the page on which the object is alloced. If the object
1266 wasn't allocated by the collector, we'll probably die. */
1267 entry
= lookup_page_table_entry (p
);
1270 /* Calculate the index of the object on the page; this is its bit
1271 position in the in_use_p bitmap. */
1272 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1273 word
= bit
/ HOST_BITS_PER_LONG
;
1274 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1276 /* If the bit was previously set, skip it. */
1277 if (entry
->in_use_p
[word
] & mask
)
1280 /* Otherwise set it, and decrement the free object count. */
1281 entry
->in_use_p
[word
] |= mask
;
1282 entry
->num_free_objects
-= 1;
1284 if (GGC_DEBUG_LEVEL
>= 4)
1285 fprintf (G
.debug_file
, "Marking %p\n", p
);
1290 /* Return 1 if P has been marked, zero otherwise.
1291 P must have been allocated by the GC allocator; it mustn't point to
1292 static objects, stack variables, or memory allocated with malloc. */
1295 ggc_marked_p (const void *p
)
1301 /* Look up the page on which the object is alloced. If the object
1302 wasn't allocated by the collector, we'll probably die. */
1303 entry
= lookup_page_table_entry (p
);
1306 /* Calculate the index of the object on the page; this is its bit
1307 position in the in_use_p bitmap. */
1308 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1309 word
= bit
/ HOST_BITS_PER_LONG
;
1310 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1312 return (entry
->in_use_p
[word
] & mask
) != 0;
1315 /* Return the size of the gc-able object P. */
1318 ggc_get_size (const void *p
)
1320 page_entry
*pe
= lookup_page_table_entry (p
);
1321 return OBJECT_SIZE (pe
->order
);
1324 /* Release the memory for object P. */
1329 page_entry
*pe
= lookup_page_table_entry (p
);
1330 size_t order
= pe
->order
;
1331 size_t size
= OBJECT_SIZE (order
);
1333 #ifdef GATHER_STATISTICS
1334 ggc_free_overhead (p
);
1337 if (GGC_DEBUG_LEVEL
>= 3)
1338 fprintf (G
.debug_file
,
1339 "Freeing object, actual size=%lu, at %p on %p\n",
1340 (unsigned long) size
, p
, (void *) pe
);
1342 #ifdef ENABLE_GC_CHECKING
1343 /* Poison the data, to indicate the data is garbage. */
1344 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (p
, size
));
1345 memset (p
, 0xa5, size
);
1347 /* Let valgrind know the object is free. */
1348 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (p
, size
));
1350 #ifdef ENABLE_GC_ALWAYS_COLLECT
1351 /* In the completely-anal-checking mode, we do *not* immediately free
1352 the data, but instead verify that the data is *actually* not
1353 reachable the next time we collect. */
1355 struct free_object
*fo
= xmalloc (sizeof (struct free_object
));
1357 fo
->next
= G
.free_object_list
;
1358 G
.free_object_list
= fo
;
1362 unsigned int bit_offset
, word
, bit
;
1364 G
.allocated
-= size
;
1366 /* Mark the object not-in-use. */
1367 bit_offset
= OFFSET_TO_BIT (((const char *) p
) - pe
->page
, order
);
1368 word
= bit_offset
/ HOST_BITS_PER_LONG
;
1369 bit
= bit_offset
% HOST_BITS_PER_LONG
;
1370 pe
->in_use_p
[word
] &= ~(1UL << bit
);
1372 if (pe
->num_free_objects
++ == 0)
1376 /* If the page is completely full, then it's supposed to
1377 be after all pages that aren't. Since we've freed one
1378 object from a page that was full, we need to move the
1379 page to the head of the list.
1381 PE is the node we want to move. Q is the previous node
1382 and P is the next node in the list. */
1384 if (q
&& q
->num_free_objects
== 0)
1390 /* If PE was at the end of the list, then Q becomes the
1391 new end of the list. If PE was not the end of the
1392 list, then we need to update the PREV field for P. */
1394 G
.page_tails
[order
] = q
;
1398 /* Move PE to the head of the list. */
1399 pe
->next
= G
.pages
[order
];
1401 G
.pages
[order
]->prev
= pe
;
1402 G
.pages
[order
] = pe
;
1405 /* Reset the hint bit to point to the only free object. */
1406 pe
->next_bit_hint
= bit_offset
;
1412 /* Subroutine of init_ggc which computes the pair of numbers used to
1413 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1415 This algorithm is taken from Granlund and Montgomery's paper
1416 "Division by Invariant Integers using Multiplication"
1417 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1421 compute_inverse (unsigned order
)
1426 size
= OBJECT_SIZE (order
);
1428 while (size
% 2 == 0)
1435 while (inv
* size
!= 1)
1436 inv
= inv
* (2 - inv
*size
);
1438 DIV_MULT (order
) = inv
;
1439 DIV_SHIFT (order
) = e
;
1442 /* Initialize the ggc-mmap allocator. */
1448 G
.pagesize
= getpagesize();
1449 G
.lg_pagesize
= exact_log2 (G
.pagesize
);
1451 #ifdef HAVE_MMAP_DEV_ZERO
1452 G
.dev_zero_fd
= open ("/dev/zero", O_RDONLY
);
1453 if (G
.dev_zero_fd
== -1)
1454 internal_error ("open /dev/zero: %m");
1458 G
.debug_file
= fopen ("ggc-mmap.debug", "w");
1460 G
.debug_file
= stdout
;
1464 /* StunOS has an amazing off-by-one error for the first mmap allocation
1465 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1466 believe, is an unaligned page allocation, which would cause us to
1467 hork badly if we tried to use it. */
1469 char *p
= alloc_anon (NULL
, G
.pagesize
);
1470 struct page_entry
*e
;
1471 if ((size_t)p
& (G
.pagesize
- 1))
1473 /* How losing. Discard this one and try another. If we still
1474 can't get something useful, give up. */
1476 p
= alloc_anon (NULL
, G
.pagesize
);
1477 gcc_assert (!((size_t)p
& (G
.pagesize
- 1)));
1480 /* We have a good page, might as well hold onto it... */
1481 e
= xcalloc (1, sizeof (struct page_entry
));
1482 e
->bytes
= G
.pagesize
;
1484 e
->next
= G
.free_pages
;
1489 /* Initialize the object size table. */
1490 for (order
= 0; order
< HOST_BITS_PER_PTR
; ++order
)
1491 object_size_table
[order
] = (size_t) 1 << order
;
1492 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1494 size_t s
= extra_order_size_table
[order
- HOST_BITS_PER_PTR
];
1496 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1497 so that we're sure of getting aligned memory. */
1498 s
= ROUND_UP (s
, MAX_ALIGNMENT
);
1499 object_size_table
[order
] = s
;
1502 /* Initialize the objects-per-page and inverse tables. */
1503 for (order
= 0; order
< NUM_ORDERS
; ++order
)
1505 objects_per_page_table
[order
] = G
.pagesize
/ OBJECT_SIZE (order
);
1506 if (objects_per_page_table
[order
] == 0)
1507 objects_per_page_table
[order
] = 1;
1508 compute_inverse (order
);
1511 /* Reset the size_lookup array to put appropriately sized objects in
1512 the special orders. All objects bigger than the previous power
1513 of two, but no greater than the special size, should go in the
1515 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1520 o
= size_lookup
[OBJECT_SIZE (order
)];
1521 for (i
= OBJECT_SIZE (order
); size_lookup
[i
] == o
; --i
)
1522 size_lookup
[i
] = order
;
1527 G
.depth
= xmalloc (G
.depth_max
* sizeof (unsigned int));
1529 G
.by_depth_in_use
= 0;
1530 G
.by_depth_max
= INITIAL_PTE_COUNT
;
1531 G
.by_depth
= xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
1532 G
.save_in_use
= xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
1535 /* Start a new GGC zone. */
1538 new_ggc_zone (const char *name ATTRIBUTE_UNUSED
)
1543 /* Destroy a GGC zone. */
1545 destroy_ggc_zone (struct alloc_zone
*zone ATTRIBUTE_UNUSED
)
1549 /* Increment the `GC context'. Objects allocated in an outer context
1550 are never freed, eliminating the need to register their roots. */
1553 ggc_push_context (void)
1558 gcc_assert (G
.context_depth
< HOST_BITS_PER_LONG
);
1561 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1562 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1565 ggc_recalculate_in_use_p (page_entry
*p
)
1570 /* Because the past-the-end bit in in_use_p is always set, we
1571 pretend there is one additional object. */
1572 num_objects
= OBJECTS_IN_PAGE (p
) + 1;
1574 /* Reset the free object count. */
1575 p
->num_free_objects
= num_objects
;
1577 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1579 i
< CEIL (BITMAP_SIZE (num_objects
),
1580 sizeof (*p
->in_use_p
));
1585 /* Something is in use if it is marked, or if it was in use in a
1586 context further down the context stack. */
1587 p
->in_use_p
[i
] |= save_in_use_p (p
)[i
];
1589 /* Decrement the free object count for every object allocated. */
1590 for (j
= p
->in_use_p
[i
]; j
; j
>>= 1)
1591 p
->num_free_objects
-= (j
& 1);
1594 gcc_assert (p
->num_free_objects
< num_objects
);
1597 /* Decrement the `GC context'. All objects allocated since the
1598 previous ggc_push_context are migrated to the outer context. */
1601 ggc_pop_context (void)
1603 unsigned long omask
;
1604 unsigned int depth
, i
, e
;
1605 #ifdef ENABLE_CHECKING
1609 depth
= --G
.context_depth
;
1610 omask
= (unsigned long)1 << (depth
+ 1);
1612 if (!((G
.context_depth_allocations
| G
.context_depth_collections
) & omask
))
1615 G
.context_depth_allocations
|= (G
.context_depth_allocations
& omask
) >> 1;
1616 G
.context_depth_allocations
&= omask
- 1;
1617 G
.context_depth_collections
&= omask
- 1;
1619 /* The G.depth array is shortened so that the last index is the
1620 context_depth of the top element of by_depth. */
1621 if (depth
+1 < G
.depth_in_use
)
1622 e
= G
.depth
[depth
+1];
1624 e
= G
.by_depth_in_use
;
1626 /* We might not have any PTEs of depth depth. */
1627 if (depth
< G
.depth_in_use
)
1630 /* First we go through all the pages at depth depth to
1631 recalculate the in use bits. */
1632 for (i
= G
.depth
[depth
]; i
< e
; ++i
)
1634 page_entry
*p
= G
.by_depth
[i
];
1636 /* Check that all of the pages really are at the depth that
1638 gcc_assert (p
->context_depth
== depth
);
1639 gcc_assert (p
->index_by_depth
== i
);
1641 prefetch (&save_in_use_p_i (i
+8));
1642 prefetch (&save_in_use_p_i (i
+16));
1643 if (save_in_use_p_i (i
))
1646 ggc_recalculate_in_use_p (p
);
1647 free (save_in_use_p_i (i
));
1648 save_in_use_p_i (i
) = 0;
1653 /* Then, we reset all page_entries with a depth greater than depth
1655 for (i
= e
; i
< G
.by_depth_in_use
; ++i
)
1657 page_entry
*p
= G
.by_depth
[i
];
1659 /* Check that all of the pages really are at the depth we
1661 gcc_assert (p
->context_depth
> depth
);
1662 gcc_assert (p
->index_by_depth
== i
);
1663 p
->context_depth
= depth
;
1668 #ifdef ENABLE_CHECKING
1669 for (order
= 2; order
< NUM_ORDERS
; order
++)
1673 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1674 gcc_assert (p
->context_depth
< depth
||
1675 (p
->context_depth
== depth
&& !save_in_use_p (p
)));
1680 /* Unmark all objects. */
1687 for (order
= 2; order
< NUM_ORDERS
; order
++)
1691 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1693 size_t num_objects
= OBJECTS_IN_PAGE (p
);
1694 size_t bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
1696 /* The data should be page-aligned. */
1697 gcc_assert (!((size_t) p
->page
& (G
.pagesize
- 1)));
1699 /* Pages that aren't in the topmost context are not collected;
1700 nevertheless, we need their in-use bit vectors to store GC
1701 marks. So, back them up first. */
1702 if (p
->context_depth
< G
.context_depth
)
1704 if (! save_in_use_p (p
))
1705 save_in_use_p (p
) = xmalloc (bitmap_size
);
1706 memcpy (save_in_use_p (p
), p
->in_use_p
, bitmap_size
);
1709 /* Reset reset the number of free objects and clear the
1710 in-use bits. These will be adjusted by mark_obj. */
1711 p
->num_free_objects
= num_objects
;
1712 memset (p
->in_use_p
, 0, bitmap_size
);
1714 /* Make sure the one-past-the-end bit is always set. */
1715 p
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
1716 = ((unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
));
1721 /* Free all empty pages. Partially empty pages need no attention
1722 because the `mark' bit doubles as an `unused' bit. */
1729 for (order
= 2; order
< NUM_ORDERS
; order
++)
1731 /* The last page-entry to consider, regardless of entries
1732 placed at the end of the list. */
1733 page_entry
* const last
= G
.page_tails
[order
];
1736 size_t live_objects
;
1737 page_entry
*p
, *previous
;
1747 page_entry
*next
= p
->next
;
1749 /* Loop until all entries have been examined. */
1752 num_objects
= OBJECTS_IN_PAGE (p
);
1754 /* Add all live objects on this page to the count of
1755 allocated memory. */
1756 live_objects
= num_objects
- p
->num_free_objects
;
1758 G
.allocated
+= OBJECT_SIZE (order
) * live_objects
;
1760 /* Only objects on pages in the topmost context should get
1762 if (p
->context_depth
< G
.context_depth
)
1765 /* Remove the page if it's empty. */
1766 else if (live_objects
== 0)
1768 /* If P was the first page in the list, then NEXT
1769 becomes the new first page in the list, otherwise
1770 splice P out of the forward pointers. */
1772 G
.pages
[order
] = next
;
1774 previous
->next
= next
;
1776 /* Splice P out of the back pointers too. */
1778 next
->prev
= previous
;
1780 /* Are we removing the last element? */
1781 if (p
== G
.page_tails
[order
])
1782 G
.page_tails
[order
] = previous
;
1787 /* If the page is full, move it to the end. */
1788 else if (p
->num_free_objects
== 0)
1790 /* Don't move it if it's already at the end. */
1791 if (p
!= G
.page_tails
[order
])
1793 /* Move p to the end of the list. */
1795 p
->prev
= G
.page_tails
[order
];
1796 G
.page_tails
[order
]->next
= p
;
1798 /* Update the tail pointer... */
1799 G
.page_tails
[order
] = p
;
1801 /* ... and the head pointer, if necessary. */
1803 G
.pages
[order
] = next
;
1805 previous
->next
= next
;
1807 /* And update the backpointer in NEXT if necessary. */
1809 next
->prev
= previous
;
1815 /* If we've fallen through to here, it's a page in the
1816 topmost context that is neither full nor empty. Such a
1817 page must precede pages at lesser context depth in the
1818 list, so move it to the head. */
1819 else if (p
!= G
.pages
[order
])
1821 previous
->next
= p
->next
;
1823 /* Update the backchain in the next node if it exists. */
1825 p
->next
->prev
= previous
;
1827 /* Move P to the head of the list. */
1828 p
->next
= G
.pages
[order
];
1830 G
.pages
[order
]->prev
= p
;
1832 /* Update the head pointer. */
1835 /* Are we moving the last element? */
1836 if (G
.page_tails
[order
] == p
)
1837 G
.page_tails
[order
] = previous
;
1846 /* Now, restore the in_use_p vectors for any pages from contexts
1847 other than the current one. */
1848 for (p
= G
.pages
[order
]; p
; p
= p
->next
)
1849 if (p
->context_depth
!= G
.context_depth
)
1850 ggc_recalculate_in_use_p (p
);
1854 #ifdef ENABLE_GC_CHECKING
1855 /* Clobber all free objects. */
1862 for (order
= 2; order
< NUM_ORDERS
; order
++)
1864 size_t size
= OBJECT_SIZE (order
);
1867 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1872 if (p
->context_depth
!= G
.context_depth
)
1873 /* Since we don't do any collection for pages in pushed
1874 contexts, there's no need to do any poisoning. And
1875 besides, the IN_USE_P array isn't valid until we pop
1879 num_objects
= OBJECTS_IN_PAGE (p
);
1880 for (i
= 0; i
< num_objects
; i
++)
1883 word
= i
/ HOST_BITS_PER_LONG
;
1884 bit
= i
% HOST_BITS_PER_LONG
;
1885 if (((p
->in_use_p
[word
] >> bit
) & 1) == 0)
1887 char *object
= p
->page
+ i
* size
;
1889 /* Keep poison-by-write when we expect to use Valgrind,
1890 so the exact same memory semantics is kept, in case
1891 there are memory errors. We override this request
1893 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (object
, size
));
1894 memset (object
, 0xa5, size
);
1896 /* Drop the handle to avoid handle leak. */
1897 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (object
, size
));
1904 #define poison_pages()
1907 #ifdef ENABLE_GC_ALWAYS_COLLECT
1908 /* Validate that the reportedly free objects actually are. */
1911 validate_free_objects (void)
1913 struct free_object
*f
, *next
, *still_free
= NULL
;
1915 for (f
= G
.free_object_list
; f
; f
= next
)
1917 page_entry
*pe
= lookup_page_table_entry (f
->object
);
1920 bit
= OFFSET_TO_BIT ((char *)f
->object
- pe
->page
, pe
->order
);
1921 word
= bit
/ HOST_BITS_PER_LONG
;
1922 bit
= bit
% HOST_BITS_PER_LONG
;
1925 /* Make certain it isn't visible from any root. Notice that we
1926 do this check before sweep_pages merges save_in_use_p. */
1927 gcc_assert (!(pe
->in_use_p
[word
] & (1UL << bit
)));
1929 /* If the object comes from an outer context, then retain the
1930 free_object entry, so that we can verify that the address
1931 isn't live on the stack in some outer context. */
1932 if (pe
->context_depth
!= G
.context_depth
)
1934 f
->next
= still_free
;
1941 G
.free_object_list
= still_free
;
1944 #define validate_free_objects()
1947 /* Top level mark-and-sweep routine. */
1952 /* Avoid frequent unnecessary work by skipping collection if the
1953 total allocations haven't expanded much since the last
1955 float allocated_last_gc
=
1956 MAX (G
.allocated_last_gc
, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE
) * 1024);
1958 float min_expand
= allocated_last_gc
* PARAM_VALUE (GGC_MIN_EXPAND
) / 100;
1960 if (G
.allocated
< allocated_last_gc
+ min_expand
&& !ggc_force_collect
)
1963 timevar_push (TV_GC
);
1965 fprintf (stderr
, " {GC %luk -> ", (unsigned long) G
.allocated
/ 1024);
1966 if (GGC_DEBUG_LEVEL
>= 2)
1967 fprintf (G
.debug_file
, "BEGIN COLLECTING\n");
1969 /* Zero the total allocated bytes. This will be recalculated in the
1973 /* Release the pages we freed the last time we collected, but didn't
1974 reuse in the interim. */
1977 /* Indicate that we've seen collections at this context depth. */
1978 G
.context_depth_collections
= ((unsigned long)1 << (G
.context_depth
+ 1)) - 1;
1982 #ifdef GATHER_STATISTICS
1983 ggc_prune_overhead_list ();
1986 validate_free_objects ();
1989 G
.allocated_last_gc
= G
.allocated
;
1991 timevar_pop (TV_GC
);
1994 fprintf (stderr
, "%luk}", (unsigned long) G
.allocated
/ 1024);
1995 if (GGC_DEBUG_LEVEL
>= 2)
1996 fprintf (G
.debug_file
, "END COLLECTING\n");
1999 /* Print allocation statistics. */
2000 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
2002 : ((x) < 1024*1024*10 \
2004 : (x) / (1024*1024))))
2005 #define STAT_LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
2008 ggc_print_statistics (void)
2010 struct ggc_statistics stats
;
2012 size_t total_overhead
= 0;
2014 /* Clear the statistics. */
2015 memset (&stats
, 0, sizeof (stats
));
2017 /* Make sure collection will really occur. */
2018 G
.allocated_last_gc
= 0;
2020 /* Collect and print the statistics common across collectors. */
2021 ggc_print_common_statistics (stderr
, &stats
);
2023 /* Release free pages so that we will not count the bytes allocated
2024 there as part of the total allocated memory. */
2027 /* Collect some information about the various sizes of
2030 "Memory still allocated at the end of the compilation process\n");
2031 fprintf (stderr
, "%-5s %10s %10s %10s\n",
2032 "Size", "Allocated", "Used", "Overhead");
2033 for (i
= 0; i
< NUM_ORDERS
; ++i
)
2040 /* Skip empty entries. */
2044 overhead
= allocated
= in_use
= 0;
2046 /* Figure out the total number of bytes allocated for objects of
2047 this size, and how many of them are actually in use. Also figure
2048 out how much memory the page table is using. */
2049 for (p
= G
.pages
[i
]; p
; p
= p
->next
)
2051 allocated
+= p
->bytes
;
2053 (OBJECTS_IN_PAGE (p
) - p
->num_free_objects
) * OBJECT_SIZE (i
);
2055 overhead
+= (sizeof (page_entry
) - sizeof (long)
2056 + BITMAP_SIZE (OBJECTS_IN_PAGE (p
) + 1));
2058 fprintf (stderr
, "%-5lu %10lu%c %10lu%c %10lu%c\n",
2059 (unsigned long) OBJECT_SIZE (i
),
2060 SCALE (allocated
), STAT_LABEL (allocated
),
2061 SCALE (in_use
), STAT_LABEL (in_use
),
2062 SCALE (overhead
), STAT_LABEL (overhead
));
2063 total_overhead
+= overhead
;
2065 fprintf (stderr
, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
2066 SCALE (G
.bytes_mapped
), STAT_LABEL (G
.bytes_mapped
),
2067 SCALE (G
.allocated
), STAT_LABEL(G
.allocated
),
2068 SCALE (total_overhead
), STAT_LABEL (total_overhead
));
2070 #ifdef GATHER_STATISTICS
2072 fprintf (stderr
, "\nTotal allocations and overheads during the compilation process\n");
2074 fprintf (stderr
, "Total Overhead: %10lld\n",
2075 G
.stats
.total_overhead
);
2076 fprintf (stderr
, "Total Allocated: %10lld\n",
2077 G
.stats
.total_allocated
);
2079 fprintf (stderr
, "Total Overhead under 32B: %10lld\n",
2080 G
.stats
.total_overhead_under32
);
2081 fprintf (stderr
, "Total Allocated under 32B: %10lld\n",
2082 G
.stats
.total_allocated_under32
);
2083 fprintf (stderr
, "Total Overhead under 64B: %10lld\n",
2084 G
.stats
.total_overhead_under64
);
2085 fprintf (stderr
, "Total Allocated under 64B: %10lld\n",
2086 G
.stats
.total_allocated_under64
);
2087 fprintf (stderr
, "Total Overhead under 128B: %10lld\n",
2088 G
.stats
.total_overhead_under128
);
2089 fprintf (stderr
, "Total Allocated under 128B: %10lld\n",
2090 G
.stats
.total_allocated_under128
);
2092 for (i
= 0; i
< NUM_ORDERS
; i
++)
2093 if (G
.stats
.total_allocated_per_order
[i
])
2095 fprintf (stderr
, "Total Overhead page size %7d: %10lld\n",
2096 OBJECT_SIZE (i
), G
.stats
.total_overhead_per_order
[i
]);
2097 fprintf (stderr
, "Total Allocated page size %7d: %10lld\n",
2098 OBJECT_SIZE (i
), G
.stats
.total_allocated_per_order
[i
]);
2106 struct ggc_pch_ondisk
2108 unsigned totals
[NUM_ORDERS
];
2110 size_t base
[NUM_ORDERS
];
2111 size_t written
[NUM_ORDERS
];
2114 struct ggc_pch_data
*
2117 return xcalloc (sizeof (struct ggc_pch_data
), 1);
2121 ggc_pch_count_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2122 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
2127 order
= size_lookup
[size
];
2131 while (size
> OBJECT_SIZE (order
))
2135 d
->d
.totals
[order
]++;
2139 ggc_pch_total_size (struct ggc_pch_data
*d
)
2144 for (i
= 0; i
< NUM_ORDERS
; i
++)
2145 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2150 ggc_pch_this_base (struct ggc_pch_data
*d
, void *base
)
2152 size_t a
= (size_t) base
;
2155 for (i
= 0; i
< NUM_ORDERS
; i
++)
2158 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2164 ggc_pch_alloc_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2165 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
2171 order
= size_lookup
[size
];
2175 while (size
> OBJECT_SIZE (order
))
2179 result
= (char *) d
->base
[order
];
2180 d
->base
[order
] += OBJECT_SIZE (order
);
2185 ggc_pch_prepare_write (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2186 FILE *f ATTRIBUTE_UNUSED
)
2188 /* Nothing to do. */
2192 ggc_pch_write_object (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2193 FILE *f
, void *x
, void *newx ATTRIBUTE_UNUSED
,
2194 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
2197 static const char emptyBytes
[256];
2200 order
= size_lookup
[size
];
2204 while (size
> OBJECT_SIZE (order
))
2208 if (fwrite (x
, size
, 1, f
) != 1)
2209 fatal_error ("can't write PCH file: %m");
2211 /* If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
2212 object out to OBJECT_SIZE(order). This happens for strings. */
2214 if (size
!= OBJECT_SIZE (order
))
2216 unsigned padding
= OBJECT_SIZE(order
) - size
;
2218 /* To speed small writes, we use a nulled-out array that's larger
2219 than most padding requests as the source for our null bytes. This
2220 permits us to do the padding with fwrite() rather than fseek(), and
2221 limits the chance the OS may try to flush any outstanding writes. */
2222 if (padding
<= sizeof(emptyBytes
))
2224 if (fwrite (emptyBytes
, 1, padding
, f
) != padding
)
2225 fatal_error ("can't write PCH file");
2229 /* Larger than our buffer? Just default to fseek. */
2230 if (fseek (f
, padding
, SEEK_CUR
) != 0)
2231 fatal_error ("can't write PCH file");
2235 d
->written
[order
]++;
2236 if (d
->written
[order
] == d
->d
.totals
[order
]
2237 && fseek (f
, ROUND_UP_VALUE (d
->d
.totals
[order
] * OBJECT_SIZE (order
),
2240 fatal_error ("can't write PCH file: %m");
2244 ggc_pch_finish (struct ggc_pch_data
*d
, FILE *f
)
2246 if (fwrite (&d
->d
, sizeof (d
->d
), 1, f
) != 1)
2247 fatal_error ("can't write PCH file: %m");
2251 /* Move the PCH PTE entries just added to the end of by_depth, to the
2255 move_ptes_to_front (int count_old_page_tables
, int count_new_page_tables
)
2259 /* First, we swap the new entries to the front of the varrays. */
2260 page_entry
**new_by_depth
;
2261 unsigned long **new_save_in_use
;
2263 new_by_depth
= xmalloc (G
.by_depth_max
* sizeof (page_entry
*));
2264 new_save_in_use
= xmalloc (G
.by_depth_max
* sizeof (unsigned long *));
2266 memcpy (&new_by_depth
[0],
2267 &G
.by_depth
[count_old_page_tables
],
2268 count_new_page_tables
* sizeof (void *));
2269 memcpy (&new_by_depth
[count_new_page_tables
],
2271 count_old_page_tables
* sizeof (void *));
2272 memcpy (&new_save_in_use
[0],
2273 &G
.save_in_use
[count_old_page_tables
],
2274 count_new_page_tables
* sizeof (void *));
2275 memcpy (&new_save_in_use
[count_new_page_tables
],
2277 count_old_page_tables
* sizeof (void *));
2280 free (G
.save_in_use
);
2282 G
.by_depth
= new_by_depth
;
2283 G
.save_in_use
= new_save_in_use
;
2285 /* Now update all the index_by_depth fields. */
2286 for (i
= G
.by_depth_in_use
; i
> 0; --i
)
2288 page_entry
*p
= G
.by_depth
[i
-1];
2289 p
->index_by_depth
= i
-1;
2292 /* And last, we update the depth pointers in G.depth. The first
2293 entry is already 0, and context 0 entries always start at index
2294 0, so there is nothing to update in the first slot. We need a
2295 second slot, only if we have old ptes, and if we do, they start
2296 at index count_new_page_tables. */
2297 if (count_old_page_tables
)
2298 push_depth (count_new_page_tables
);
2302 ggc_pch_read (FILE *f
, void *addr
)
2304 struct ggc_pch_ondisk d
;
2307 unsigned long count_old_page_tables
;
2308 unsigned long count_new_page_tables
;
2310 count_old_page_tables
= G
.by_depth_in_use
;
2312 /* We've just read in a PCH file. So, every object that used to be
2313 allocated is now free. */
2315 #ifdef ENABLE_GC_CHECKING
2319 /* No object read from a PCH file should ever be freed. So, set the
2320 context depth to 1, and set the depth of all the currently-allocated
2321 pages to be 1 too. PCH pages will have depth 0. */
2322 gcc_assert (!G
.context_depth
);
2323 G
.context_depth
= 1;
2324 for (i
= 0; i
< NUM_ORDERS
; i
++)
2327 for (p
= G
.pages
[i
]; p
!= NULL
; p
= p
->next
)
2328 p
->context_depth
= G
.context_depth
;
2331 /* Allocate the appropriate page-table entries for the pages read from
2333 if (fread (&d
, sizeof (d
), 1, f
) != 1)
2334 fatal_error ("can't read PCH file: %m");
2336 for (i
= 0; i
< NUM_ORDERS
; i
++)
2338 struct page_entry
*entry
;
2344 if (d
.totals
[i
] == 0)
2347 bytes
= ROUND_UP (d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2348 num_objs
= bytes
/ OBJECT_SIZE (i
);
2349 entry
= xcalloc (1, (sizeof (struct page_entry
)
2351 + BITMAP_SIZE (num_objs
+ 1)));
2352 entry
->bytes
= bytes
;
2354 entry
->context_depth
= 0;
2356 entry
->num_free_objects
= 0;
2360 j
+ HOST_BITS_PER_LONG
<= num_objs
+ 1;
2361 j
+= HOST_BITS_PER_LONG
)
2362 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
] = -1;
2363 for (; j
< num_objs
+ 1; j
++)
2364 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
]
2365 |= 1L << (j
% HOST_BITS_PER_LONG
);
2367 for (pte
= entry
->page
;
2368 pte
< entry
->page
+ entry
->bytes
;
2370 set_page_table_entry (pte
, entry
);
2372 if (G
.page_tails
[i
] != NULL
)
2373 G
.page_tails
[i
]->next
= entry
;
2376 G
.page_tails
[i
] = entry
;
2378 /* We start off by just adding all the new information to the
2379 end of the varrays, later, we will move the new information
2380 to the front of the varrays, as the PCH page tables are at
2382 push_by_depth (entry
, 0);
2385 /* Now, we update the various data structures that speed page table
2387 count_new_page_tables
= G
.by_depth_in_use
- count_old_page_tables
;
2389 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
);
2391 /* Update the statistics. */
2392 G
.allocated
= G
.allocated_last_gc
= offs
- (char *)addr
;