1 /* "Bag-of-pages" garbage collector for the GNU compiler.
2 Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
33 #include "tree-flow.h"
35 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
36 file open. Prefer either to valloc. */
38 # undef HAVE_MMAP_DEV_ZERO
40 # include <sys/mman.h>
42 # define MAP_FAILED -1
44 # if !defined (MAP_ANONYMOUS) && defined (MAP_ANON)
45 # define MAP_ANONYMOUS MAP_ANON
51 #ifdef HAVE_MMAP_DEV_ZERO
53 # include <sys/mman.h>
55 # define MAP_FAILED -1
62 #define USING_MALLOC_PAGE_GROUPS
67 This garbage-collecting allocator allocates objects on one of a set
68 of pages. Each page can allocate objects of a single size only;
69 available sizes are powers of two starting at four bytes. The size
70 of an allocation request is rounded up to the next power of two
71 (`order'), and satisfied from the appropriate page.
73 Each page is recorded in a page-entry, which also maintains an
74 in-use bitmap of object positions on the page. This allows the
75 allocation state of a particular object to be flipped without
76 touching the page itself.
78 Each page-entry also has a context depth, which is used to track
79 pushing and popping of allocation contexts. Only objects allocated
80 in the current (highest-numbered) context may be collected.
82 Page entries are arranged in an array of singly-linked lists. The
83 array is indexed by the allocation size, in bits, of the pages on
84 it; i.e. all pages on a list allocate objects of the same size.
85 Pages are ordered on the list such that all non-full pages precede
86 all full pages, with non-full pages arranged in order of decreasing
89 Empty pages (of all orders) are kept on a single page cache list,
90 and are considered first when new pages are required; they are
91 deallocated at the start of the next collection if they haven't
92 been recycled by then. */
94 /* Define GGC_DEBUG_LEVEL to print debugging information.
95 0: No debugging output.
96 1: GC statistics only.
97 2: Page-entry allocations/deallocations as well.
98 3: Object allocations as well.
99 4: Object marks as well. */
100 #define GGC_DEBUG_LEVEL (0)
102 #ifndef HOST_BITS_PER_PTR
103 #define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
107 /* A two-level tree is used to look up the page-entry for a given
108 pointer. Two chunks of the pointer's bits are extracted to index
109 the first and second levels of the tree, as follows:
113 msb +----------------+----+------+------+ lsb
119 The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
120 pages are aligned on system page boundaries. The next most
121 significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
122 index values in the lookup table, respectively.
124 For 32-bit architectures and the settings below, there are no
125 leftover bits. For architectures with wider pointers, the lookup
126 tree points to a list of pages, which must be scanned to find the
129 #define PAGE_L1_BITS (8)
130 #define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
131 #define PAGE_L1_SIZE ((size_t) 1 << PAGE_L1_BITS)
132 #define PAGE_L2_SIZE ((size_t) 1 << PAGE_L2_BITS)
134 #define LOOKUP_L1(p) \
135 (((size_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
137 #define LOOKUP_L2(p) \
138 (((size_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
140 /* The number of objects per allocation page, for objects on a page of
141 the indicated ORDER. */
142 #define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
144 /* The number of objects in P. */
145 #define OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
147 /* The size of an object on a page of the indicated ORDER. */
148 #define OBJECT_SIZE(ORDER) object_size_table[ORDER]
150 /* For speed, we avoid doing a general integer divide to locate the
151 offset in the allocation bitmap, by precalculating numbers M, S
152 such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
153 within the page which is evenly divisible by the object size Z. */
154 #define DIV_MULT(ORDER) inverse_table[ORDER].mult
155 #define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
156 #define OFFSET_TO_BIT(OFFSET, ORDER) \
157 (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
159 /* The number of extra orders, not corresponding to power-of-two sized
162 #define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
164 #define RTL_SIZE(NSLOTS) \
165 (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))
167 #define TREE_EXP_SIZE(OPS) \
168 (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
170 /* The Ith entry is the maximum size of an object to be stored in the
171 Ith extra order. Adding a new entry to this array is the *only*
172 thing you need to do to add a new special allocation size. */
174 static const size_t extra_order_size_table
[] = {
175 sizeof (struct var_ann_d
),
176 sizeof (struct tree_decl_non_common
),
177 sizeof (struct tree_field_decl
),
178 sizeof (struct tree_parm_decl
),
179 sizeof (struct tree_var_decl
),
180 sizeof (struct tree_list
),
181 sizeof (struct tree_ssa_name
),
182 sizeof (struct function
),
183 sizeof (struct basic_block_def
),
184 sizeof (bitmap_element
),
185 sizeof (bitmap_head
),
187 RTL_SIZE (2), /* MEM, PLUS, etc. */
188 RTL_SIZE (9), /* INSN */
191 /* The total number of orders. */
193 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
195 /* We use this structure to determine the alignment required for
196 allocations. For power-of-two sized allocations, that's not a
197 problem, but it does matter for odd-sized allocations. */
199 struct max_alignment
{
207 /* The biggest alignment required. */
209 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
211 /* Compute the smallest nonnegative number which when added to X gives
214 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
216 /* Compute the smallest multiple of F that is >= X. */
218 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
220 /* The Ith entry is the number of objects on a page or order I. */
222 static unsigned objects_per_page_table
[NUM_ORDERS
];
224 /* The Ith entry is the size of an object on a page of order I. */
226 static size_t object_size_table
[NUM_ORDERS
];
228 /* The Ith entry is a pair of numbers (mult, shift) such that
229 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
230 for all k evenly divisible by OBJECT_SIZE(I). */
237 inverse_table
[NUM_ORDERS
];
239 /* A page_entry records the status of an allocation page. This
240 structure is dynamically sized to fit the bitmap in_use_p. */
241 typedef struct page_entry
243 /* The next page-entry with objects of the same size, or NULL if
244 this is the last page-entry. */
245 struct page_entry
*next
;
247 /* The previous page-entry with objects of the same size, or NULL if
248 this is the first page-entry. The PREV pointer exists solely to
249 keep the cost of ggc_free manageable. */
250 struct page_entry
*prev
;
252 /* The number of bytes allocated. (This will always be a multiple
253 of the host system page size.) */
256 /* The address at which the memory is allocated. */
259 #ifdef USING_MALLOC_PAGE_GROUPS
260 /* Back pointer to the page group this page came from. */
261 struct page_group
*group
;
264 /* This is the index in the by_depth varray where this page table
266 unsigned long index_by_depth
;
268 /* Context depth of this page. */
269 unsigned short context_depth
;
271 /* The number of free objects remaining on this page. */
272 unsigned short num_free_objects
;
274 /* A likely candidate for the bit position of a free object for the
275 next allocation from this page. */
276 unsigned short next_bit_hint
;
278 /* The lg of size of objects allocated from this page. */
281 /* A bit vector indicating whether or not objects are in use. The
282 Nth bit is one if the Nth object on this page is allocated. This
283 array is dynamically sized. */
284 unsigned long in_use_p
[1];
287 #ifdef USING_MALLOC_PAGE_GROUPS
288 /* A page_group describes a large allocation from malloc, from which
289 we parcel out aligned pages. */
290 typedef struct page_group
292 /* A linked list of all extant page groups. */
293 struct page_group
*next
;
295 /* The address we received from malloc. */
298 /* The size of the block. */
301 /* A bitmask of pages in use. */
306 #if HOST_BITS_PER_PTR <= 32
308 /* On 32-bit hosts, we use a two level page table, as pictured above. */
309 typedef page_entry
**page_table
[PAGE_L1_SIZE
];
313 /* On 64-bit hosts, we use the same two level page tables plus a linked
314 list that disambiguates the top 32-bits. There will almost always be
315 exactly one entry in the list. */
316 typedef struct page_table_chain
318 struct page_table_chain
*next
;
320 page_entry
**table
[PAGE_L1_SIZE
];
325 /* The rest of the global variables. */
326 static struct globals
328 /* The Nth element in this array is a page with objects of size 2^N.
329 If there are any pages with free objects, they will be at the
330 head of the list. NULL if there are no page-entries for this
332 page_entry
*pages
[NUM_ORDERS
];
334 /* The Nth element in this array is the last page with objects of
335 size 2^N. NULL if there are no page-entries for this object
337 page_entry
*page_tails
[NUM_ORDERS
];
339 /* Lookup table for associating allocation pages with object addresses. */
342 /* The system's page size. */
346 /* Bytes currently allocated. */
349 /* Bytes currently allocated at the end of the last collection. */
350 size_t allocated_last_gc
;
352 /* Total amount of memory mapped. */
355 /* Bit N set if any allocations have been done at context depth N. */
356 unsigned long context_depth_allocations
;
358 /* Bit N set if any collections have been done at context depth N. */
359 unsigned long context_depth_collections
;
361 /* The current depth in the context stack. */
362 unsigned short context_depth
;
364 /* A file descriptor open to /dev/zero for reading. */
365 #if defined (HAVE_MMAP_DEV_ZERO)
369 /* A cache of free system pages. */
370 page_entry
*free_pages
;
372 #ifdef USING_MALLOC_PAGE_GROUPS
373 page_group
*page_groups
;
376 /* The file descriptor for debugging output. */
379 /* Current number of elements in use in depth below. */
380 unsigned int depth_in_use
;
382 /* Maximum number of elements that can be used before resizing. */
383 unsigned int depth_max
;
385 /* Each element of this array is an index in by_depth where the given
386 depth starts. This structure is indexed by that given depth we
387 are interested in. */
390 /* Current number of elements in use in by_depth below. */
391 unsigned int by_depth_in_use
;
393 /* Maximum number of elements that can be used before resizing. */
394 unsigned int by_depth_max
;
396 /* Each element of this array is a pointer to a page_entry, all
397 page_entries can be found in here by increasing depth.
398 index_by_depth in the page_entry is the index into this data
399 structure where that page_entry can be found. This is used to
400 speed up finding all page_entries at a particular depth. */
401 page_entry
**by_depth
;
403 /* Each element is a pointer to the saved in_use_p bits, if any,
404 zero otherwise. We allocate them all together, to enable a
405 better runtime data access pattern. */
406 unsigned long **save_in_use
;
408 #ifdef ENABLE_GC_ALWAYS_COLLECT
409 /* List of free objects to be verified as actually free on the
414 struct free_object
*next
;
418 #ifdef GATHER_STATISTICS
421 /* Total memory allocated with ggc_alloc. */
422 unsigned long long total_allocated
;
423 /* Total overhead for memory to be allocated with ggc_alloc. */
424 unsigned long long total_overhead
;
426 /* Total allocations and overhead for sizes less than 32, 64 and 128.
427 These sizes are interesting because they are typical cache line
430 unsigned long long total_allocated_under32
;
431 unsigned long long total_overhead_under32
;
433 unsigned long long total_allocated_under64
;
434 unsigned long long total_overhead_under64
;
436 unsigned long long total_allocated_under128
;
437 unsigned long long total_overhead_under128
;
439 /* The allocations for each of the allocation orders. */
440 unsigned long long total_allocated_per_order
[NUM_ORDERS
];
442 /* The overhead for each of the allocation orders. */
443 unsigned long long total_overhead_per_order
[NUM_ORDERS
];
448 /* The size in bytes required to maintain a bitmap for the objects
450 #define BITMAP_SIZE(Num_objects) \
451 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
453 /* Allocate pages in chunks of this size, to throttle calls to memory
454 allocation routines. The first page is used, the rest go onto the
455 free list. This cannot be larger than HOST_BITS_PER_INT for the
456 in_use bitmask for page_group. Hosts that need a different value
457 can override this by defining GGC_QUIRE_SIZE explicitly. */
458 #ifndef GGC_QUIRE_SIZE
460 # define GGC_QUIRE_SIZE 256
462 # define GGC_QUIRE_SIZE 16
466 /* Initial guess as to how many page table entries we might need. */
467 #define INITIAL_PTE_COUNT 128
469 static int ggc_allocated_p (const void *);
470 static page_entry
*lookup_page_table_entry (const void *);
471 static void set_page_table_entry (void *, page_entry
*);
473 static char *alloc_anon (char *, size_t);
475 #ifdef USING_MALLOC_PAGE_GROUPS
476 static size_t page_group_index (char *, char *);
477 static void set_page_group_in_use (page_group
*, char *);
478 static void clear_page_group_in_use (page_group
*, char *);
480 static struct page_entry
* alloc_page (unsigned);
481 static void free_page (struct page_entry
*);
482 static void release_pages (void);
483 static void clear_marks (void);
484 static void sweep_pages (void);
485 static void ggc_recalculate_in_use_p (page_entry
*);
486 static void compute_inverse (unsigned);
487 static inline void adjust_depth (void);
488 static void move_ptes_to_front (int, int);
490 void debug_print_page_list (int);
491 static void push_depth (unsigned int);
492 static void push_by_depth (page_entry
*, unsigned long *);
494 /* Push an entry onto G.depth. */
497 push_depth (unsigned int i
)
499 if (G
.depth_in_use
>= G
.depth_max
)
502 G
.depth
= XRESIZEVEC (unsigned int, G
.depth
, G
.depth_max
);
504 G
.depth
[G
.depth_in_use
++] = i
;
507 /* Push an entry onto G.by_depth and G.save_in_use. */
510 push_by_depth (page_entry
*p
, unsigned long *s
)
512 if (G
.by_depth_in_use
>= G
.by_depth_max
)
515 G
.by_depth
= XRESIZEVEC (page_entry
*, G
.by_depth
, G
.by_depth_max
);
516 G
.save_in_use
= XRESIZEVEC (unsigned long *, G
.save_in_use
,
519 G
.by_depth
[G
.by_depth_in_use
] = p
;
520 G
.save_in_use
[G
.by_depth_in_use
++] = s
;
523 #if (GCC_VERSION < 3001)
524 #define prefetch(X) ((void) X)
526 #define prefetch(X) __builtin_prefetch (X)
529 #define save_in_use_p_i(__i) \
531 #define save_in_use_p(__p) \
532 (save_in_use_p_i (__p->index_by_depth))
534 /* Returns nonzero if P was allocated in GC'able memory. */
537 ggc_allocated_p (const void *p
)
542 #if HOST_BITS_PER_PTR <= 32
545 page_table table
= G
.lookup
;
546 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
551 if (table
->high_bits
== high_bits
)
555 base
= &table
->table
[0];
558 /* Extract the level 1 and 2 indices. */
562 return base
[L1
] && base
[L1
][L2
];
565 /* Traverse the page table and find the entry for a page.
566 Die (probably) if the object wasn't allocated via GC. */
568 static inline page_entry
*
569 lookup_page_table_entry (const void *p
)
574 #if HOST_BITS_PER_PTR <= 32
577 page_table table
= G
.lookup
;
578 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
579 while (table
->high_bits
!= high_bits
)
581 base
= &table
->table
[0];
584 /* Extract the level 1 and 2 indices. */
591 /* Set the page table entry for a page. */
594 set_page_table_entry (void *p
, page_entry
*entry
)
599 #if HOST_BITS_PER_PTR <= 32
603 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
604 for (table
= G
.lookup
; table
; table
= table
->next
)
605 if (table
->high_bits
== high_bits
)
608 /* Not found -- allocate a new table. */
609 table
= XCNEW (struct page_table_chain
);
610 table
->next
= G
.lookup
;
611 table
->high_bits
= high_bits
;
614 base
= &table
->table
[0];
617 /* Extract the level 1 and 2 indices. */
621 if (base
[L1
] == NULL
)
622 base
[L1
] = XCNEWVEC (page_entry
*, PAGE_L2_SIZE
);
624 base
[L1
][L2
] = entry
;
627 /* Prints the page-entry for object size ORDER, for debugging. */
630 debug_print_page_list (int order
)
633 printf ("Head=%p, Tail=%p:\n", (void *) G
.pages
[order
],
634 (void *) G
.page_tails
[order
]);
638 printf ("%p(%1d|%3d) -> ", (void *) p
, p
->context_depth
,
639 p
->num_free_objects
);
647 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
648 (if non-null). The ifdef structure here is intended to cause a
649 compile error unless exactly one of the HAVE_* is defined. */
652 alloc_anon (char *pref ATTRIBUTE_UNUSED
, size_t size
)
654 #ifdef HAVE_MMAP_ANON
655 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
656 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
658 #ifdef HAVE_MMAP_DEV_ZERO
659 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
660 MAP_PRIVATE
, G
.dev_zero_fd
, 0);
663 if (page
== (char *) MAP_FAILED
)
665 perror ("virtual memory exhausted");
666 exit (FATAL_EXIT_CODE
);
669 /* Remember that we allocated this memory. */
670 G
.bytes_mapped
+= size
;
672 /* Pretend we don't have access to the allocated pages. We'll enable
673 access to smaller pieces of the area in ggc_alloc. Discard the
674 handle to avoid handle leak. */
675 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (page
, size
));
680 #ifdef USING_MALLOC_PAGE_GROUPS
681 /* Compute the index for this page into the page group. */
684 page_group_index (char *allocation
, char *page
)
686 return (size_t) (page
- allocation
) >> G
.lg_pagesize
;
689 /* Set and clear the in_use bit for this page in the page group. */
692 set_page_group_in_use (page_group
*group
, char *page
)
694 group
->in_use
|= 1 << page_group_index (group
->allocation
, page
);
698 clear_page_group_in_use (page_group
*group
, char *page
)
700 group
->in_use
&= ~(1 << page_group_index (group
->allocation
, page
));
704 /* Allocate a new page for allocating objects of size 2^ORDER,
705 and return an entry for it. The entry is not added to the
706 appropriate page_table list. */
708 static inline struct page_entry
*
709 alloc_page (unsigned order
)
711 struct page_entry
*entry
, *p
, **pp
;
715 size_t page_entry_size
;
717 #ifdef USING_MALLOC_PAGE_GROUPS
721 num_objects
= OBJECTS_PER_PAGE (order
);
722 bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
723 page_entry_size
= sizeof (page_entry
) - sizeof (long) + bitmap_size
;
724 entry_size
= num_objects
* OBJECT_SIZE (order
);
725 if (entry_size
< G
.pagesize
)
726 entry_size
= G
.pagesize
;
731 /* Check the list of free pages for one we can use. */
732 for (pp
= &G
.free_pages
, p
= *pp
; p
; pp
= &p
->next
, p
= *pp
)
733 if (p
->bytes
== entry_size
)
738 /* Recycle the allocated memory from this page ... */
742 #ifdef USING_MALLOC_PAGE_GROUPS
746 /* ... and, if possible, the page entry itself. */
747 if (p
->order
== order
)
750 memset (entry
, 0, page_entry_size
);
756 else if (entry_size
== G
.pagesize
)
758 /* We want just one page. Allocate a bunch of them and put the
759 extras on the freelist. (Can only do this optimization with
760 mmap for backing store.) */
761 struct page_entry
*e
, *f
= G
.free_pages
;
764 page
= alloc_anon (NULL
, G
.pagesize
* GGC_QUIRE_SIZE
);
766 /* This loop counts down so that the chain will be in ascending
768 for (i
= GGC_QUIRE_SIZE
- 1; i
>= 1; i
--)
770 e
= XCNEWVAR (struct page_entry
, page_entry_size
);
772 e
->bytes
= G
.pagesize
;
773 e
->page
= page
+ (i
<< G
.lg_pagesize
);
781 page
= alloc_anon (NULL
, entry_size
);
783 #ifdef USING_MALLOC_PAGE_GROUPS
786 /* Allocate a large block of memory and serve out the aligned
787 pages therein. This results in much less memory wastage
788 than the traditional implementation of valloc. */
790 char *allocation
, *a
, *enda
;
791 size_t alloc_size
, head_slop
, tail_slop
;
792 int multiple_pages
= (entry_size
== G
.pagesize
);
795 alloc_size
= GGC_QUIRE_SIZE
* G
.pagesize
;
797 alloc_size
= entry_size
+ G
.pagesize
- 1;
798 allocation
= XNEWVEC (char, alloc_size
);
800 page
= (char *) (((size_t) allocation
+ G
.pagesize
- 1) & -G
.pagesize
);
801 head_slop
= page
- allocation
;
803 tail_slop
= ((size_t) allocation
+ alloc_size
) & (G
.pagesize
- 1);
805 tail_slop
= alloc_size
- entry_size
- head_slop
;
806 enda
= allocation
+ alloc_size
- tail_slop
;
808 /* We allocated N pages, which are likely not aligned, leaving
809 us with N-1 usable pages. We plan to place the page_group
810 structure somewhere in the slop. */
811 if (head_slop
>= sizeof (page_group
))
812 group
= (page_group
*)page
- 1;
815 /* We magically got an aligned allocation. Too bad, we have
816 to waste a page anyway. */
820 tail_slop
+= G
.pagesize
;
822 gcc_assert (tail_slop
>= sizeof (page_group
));
823 group
= (page_group
*)enda
;
824 tail_slop
-= sizeof (page_group
);
827 /* Remember that we allocated this memory. */
828 group
->next
= G
.page_groups
;
829 group
->allocation
= allocation
;
830 group
->alloc_size
= alloc_size
;
832 G
.page_groups
= group
;
833 G
.bytes_mapped
+= alloc_size
;
835 /* If we allocated multiple pages, put the rest on the free list. */
838 struct page_entry
*e
, *f
= G
.free_pages
;
839 for (a
= enda
- G
.pagesize
; a
!= page
; a
-= G
.pagesize
)
841 e
= XCNEWVAR (struct page_entry
, page_entry_size
);
843 e
->bytes
= G
.pagesize
;
855 entry
= XCNEWVAR (struct page_entry
, page_entry_size
);
857 entry
->bytes
= entry_size
;
859 entry
->context_depth
= G
.context_depth
;
860 entry
->order
= order
;
861 entry
->num_free_objects
= num_objects
;
862 entry
->next_bit_hint
= 1;
864 G
.context_depth_allocations
|= (unsigned long)1 << G
.context_depth
;
866 #ifdef USING_MALLOC_PAGE_GROUPS
867 entry
->group
= group
;
868 set_page_group_in_use (group
, page
);
871 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
872 increment the hint. */
873 entry
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
874 = (unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
);
876 set_page_table_entry (page
, entry
);
878 if (GGC_DEBUG_LEVEL
>= 2)
879 fprintf (G
.debug_file
,
880 "Allocating page at %p, object size=%lu, data %p-%p\n",
881 (void *) entry
, (unsigned long) OBJECT_SIZE (order
), page
,
882 page
+ entry_size
- 1);
887 /* Adjust the size of G.depth so that no index greater than the one
888 used by the top of the G.by_depth is used. */
895 if (G
.by_depth_in_use
)
897 top
= G
.by_depth
[G
.by_depth_in_use
-1];
899 /* Peel back indices in depth that index into by_depth, so that
900 as new elements are added to by_depth, we note the indices
901 of those elements, if they are for new context depths. */
902 while (G
.depth_in_use
> (size_t)top
->context_depth
+1)
907 /* For a page that is no longer needed, put it on the free page list. */
910 free_page (page_entry
*entry
)
912 if (GGC_DEBUG_LEVEL
>= 2)
913 fprintf (G
.debug_file
,
914 "Deallocating page at %p, data %p-%p\n", (void *) entry
,
915 entry
->page
, entry
->page
+ entry
->bytes
- 1);
917 /* Mark the page as inaccessible. Discard the handle to avoid handle
919 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (entry
->page
, entry
->bytes
));
921 set_page_table_entry (entry
->page
, NULL
);
923 #ifdef USING_MALLOC_PAGE_GROUPS
924 clear_page_group_in_use (entry
->group
, entry
->page
);
927 if (G
.by_depth_in_use
> 1)
929 page_entry
*top
= G
.by_depth
[G
.by_depth_in_use
-1];
930 int i
= entry
->index_by_depth
;
932 /* We cannot free a page from a context deeper than the current
934 gcc_assert (entry
->context_depth
== top
->context_depth
);
936 /* Put top element into freed slot. */
938 G
.save_in_use
[i
] = G
.save_in_use
[G
.by_depth_in_use
-1];
939 top
->index_by_depth
= i
;
945 entry
->next
= G
.free_pages
;
946 G
.free_pages
= entry
;
949 /* Release the free page cache to the system. */
955 page_entry
*p
, *next
;
959 /* Gather up adjacent pages so they are unmapped together. */
970 while (p
&& p
->page
== start
+ len
)
979 G
.bytes_mapped
-= len
;
984 #ifdef USING_MALLOC_PAGE_GROUPS
988 /* Remove all pages from free page groups from the list. */
990 while ((p
= *pp
) != NULL
)
991 if (p
->group
->in_use
== 0)
999 /* Remove all free page groups, and release the storage. */
1000 gp
= &G
.page_groups
;
1001 while ((g
= *gp
) != NULL
)
1005 G
.bytes_mapped
-= g
->alloc_size
;
1006 free (g
->allocation
);
1013 /* This table provides a fast way to determine ceil(log_2(size)) for
1014 allocation requests. The minimum allocation size is eight bytes. */
1015 #define NUM_SIZE_LOOKUP 512
1016 static unsigned char size_lookup
[NUM_SIZE_LOOKUP
] =
1018 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
1019 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1020 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1021 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1022 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1023 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1024 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1025 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1026 7, 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,
1028 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1029 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1030 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1031 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1032 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1033 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1034 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1035 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1036 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1037 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1038 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1039 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1040 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1041 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1042 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1043 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1044 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1045 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1046 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1047 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1048 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1049 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
1052 /* Typed allocation function. Does nothing special in this collector. */
1055 ggc_alloc_typed_stat (enum gt_types_enum type ATTRIBUTE_UNUSED
, size_t size
1058 return ggc_alloc_stat (size PASS_MEM_STAT
);
1061 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1064 ggc_alloc_stat (size_t size MEM_STAT_DECL
)
1066 size_t order
, word
, bit
, object_offset
, object_size
;
1067 struct page_entry
*entry
;
1070 if (size
< NUM_SIZE_LOOKUP
)
1072 order
= size_lookup
[size
];
1073 object_size
= OBJECT_SIZE (order
);
1078 while (size
> (object_size
= OBJECT_SIZE (order
)))
1082 /* If there are non-full pages for this size allocation, they are at
1083 the head of the list. */
1084 entry
= G
.pages
[order
];
1086 /* If there is no page for this object size, or all pages in this
1087 context are full, allocate a new page. */
1088 if (entry
== NULL
|| entry
->num_free_objects
== 0)
1090 struct page_entry
*new_entry
;
1091 new_entry
= alloc_page (order
);
1093 new_entry
->index_by_depth
= G
.by_depth_in_use
;
1094 push_by_depth (new_entry
, 0);
1096 /* We can skip context depths, if we do, make sure we go all the
1097 way to the new depth. */
1098 while (new_entry
->context_depth
>= G
.depth_in_use
)
1099 push_depth (G
.by_depth_in_use
-1);
1101 /* If this is the only entry, it's also the tail. If it is not
1102 the only entry, then we must update the PREV pointer of the
1103 ENTRY (G.pages[order]) to point to our new page entry. */
1105 G
.page_tails
[order
] = new_entry
;
1107 entry
->prev
= new_entry
;
1109 /* Put new pages at the head of the page list. By definition the
1110 entry at the head of the list always has a NULL pointer. */
1111 new_entry
->next
= entry
;
1112 new_entry
->prev
= NULL
;
1114 G
.pages
[order
] = new_entry
;
1116 /* For a new page, we know the word and bit positions (in the
1117 in_use bitmap) of the first available object -- they're zero. */
1118 new_entry
->next_bit_hint
= 1;
1125 /* First try to use the hint left from the previous allocation
1126 to locate a clear bit in the in-use bitmap. We've made sure
1127 that the one-past-the-end bit is always set, so if the hint
1128 has run over, this test will fail. */
1129 unsigned hint
= entry
->next_bit_hint
;
1130 word
= hint
/ HOST_BITS_PER_LONG
;
1131 bit
= hint
% HOST_BITS_PER_LONG
;
1133 /* If the hint didn't work, scan the bitmap from the beginning. */
1134 if ((entry
->in_use_p
[word
] >> bit
) & 1)
1137 while (~entry
->in_use_p
[word
] == 0)
1140 #if GCC_VERSION >= 3004
1141 bit
= __builtin_ctzl (~entry
->in_use_p
[word
]);
1143 while ((entry
->in_use_p
[word
] >> bit
) & 1)
1147 hint
= word
* HOST_BITS_PER_LONG
+ bit
;
1150 /* Next time, try the next bit. */
1151 entry
->next_bit_hint
= hint
+ 1;
1153 object_offset
= hint
* object_size
;
1156 /* Set the in-use bit. */
1157 entry
->in_use_p
[word
] |= ((unsigned long) 1 << bit
);
1159 /* Keep a running total of the number of free objects. If this page
1160 fills up, we may have to move it to the end of the list if the
1161 next page isn't full. If the next page is full, all subsequent
1162 pages are full, so there's no need to move it. */
1163 if (--entry
->num_free_objects
== 0
1164 && entry
->next
!= NULL
1165 && entry
->next
->num_free_objects
> 0)
1167 /* We have a new head for the list. */
1168 G
.pages
[order
] = entry
->next
;
1170 /* We are moving ENTRY to the end of the page table list.
1171 The new page at the head of the list will have NULL in
1172 its PREV field and ENTRY will have NULL in its NEXT field. */
1173 entry
->next
->prev
= NULL
;
1176 /* Append ENTRY to the tail of the list. */
1177 entry
->prev
= G
.page_tails
[order
];
1178 G
.page_tails
[order
]->next
= entry
;
1179 G
.page_tails
[order
] = entry
;
1182 /* Calculate the object's address. */
1183 result
= entry
->page
+ object_offset
;
1184 #ifdef GATHER_STATISTICS
1185 ggc_record_overhead (OBJECT_SIZE (order
), OBJECT_SIZE (order
) - size
,
1186 result PASS_MEM_STAT
);
1189 #ifdef ENABLE_GC_CHECKING
1190 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1191 exact same semantics in presence of memory bugs, regardless of
1192 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1193 handle to avoid handle leak. */
1194 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result
, object_size
));
1196 /* `Poison' the entire allocated object, including any padding at
1198 memset (result
, 0xaf, object_size
);
1200 /* Make the bytes after the end of the object unaccessible. Discard the
1201 handle to avoid handle leak. */
1202 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *) result
+ size
,
1203 object_size
- size
));
1206 /* Tell Valgrind that the memory is there, but its content isn't
1207 defined. The bytes at the end of the object are still marked
1209 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result
, size
));
1211 /* Keep track of how many bytes are being allocated. This
1212 information is used in deciding when to collect. */
1213 G
.allocated
+= object_size
;
1215 /* For timevar statistics. */
1216 timevar_ggc_mem_total
+= 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 /* Mark function for strings. */
1257 gt_ggc_m_S (const void *p
)
1262 unsigned long offset
;
1264 if (!p
|| !ggc_allocated_p (p
))
1267 /* Look up the page on which the object is alloced. . */
1268 entry
= lookup_page_table_entry (p
);
1271 /* Calculate the index of the object on the page; this is its bit
1272 position in the in_use_p bitmap. Note that because a char* might
1273 point to the middle of an object, we need special code here to
1274 make sure P points to the start of an object. */
1275 offset
= ((const char *) p
- entry
->page
) % object_size_table
[entry
->order
];
1278 /* Here we've seen a char* which does not point to the beginning
1279 of an allocated object. We assume it points to the middle of
1281 gcc_assert (offset
== offsetof (struct tree_string
, str
));
1282 p
= ((const char *) p
) - offset
;
1283 gt_ggc_mx_lang_tree_node (CONST_CAST (void *, p
));
1287 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1288 word
= bit
/ HOST_BITS_PER_LONG
;
1289 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1291 /* If the bit was previously set, skip it. */
1292 if (entry
->in_use_p
[word
] & mask
)
1295 /* Otherwise set it, and decrement the free object count. */
1296 entry
->in_use_p
[word
] |= mask
;
1297 entry
->num_free_objects
-= 1;
1299 if (GGC_DEBUG_LEVEL
>= 4)
1300 fprintf (G
.debug_file
, "Marking %p\n", p
);
1305 /* If P is not marked, marks it and return false. Otherwise return true.
1306 P must have been allocated by the GC allocator; it mustn't point to
1307 static objects, stack variables, or memory allocated with malloc. */
1310 ggc_set_mark (const void *p
)
1316 /* Look up the page on which the object is alloced. If the object
1317 wasn't allocated by the collector, we'll probably die. */
1318 entry
= lookup_page_table_entry (p
);
1321 /* Calculate the index of the object on the page; this is its bit
1322 position in the in_use_p bitmap. */
1323 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1324 word
= bit
/ HOST_BITS_PER_LONG
;
1325 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1327 /* If the bit was previously set, skip it. */
1328 if (entry
->in_use_p
[word
] & mask
)
1331 /* Otherwise set it, and decrement the free object count. */
1332 entry
->in_use_p
[word
] |= mask
;
1333 entry
->num_free_objects
-= 1;
1335 if (GGC_DEBUG_LEVEL
>= 4)
1336 fprintf (G
.debug_file
, "Marking %p\n", p
);
1341 /* Return 1 if P has been marked, zero otherwise.
1342 P must have been allocated by the GC allocator; it mustn't point to
1343 static objects, stack variables, or memory allocated with malloc. */
1346 ggc_marked_p (const void *p
)
1352 /* Look up the page on which the object is alloced. If the object
1353 wasn't allocated by the collector, we'll probably die. */
1354 entry
= lookup_page_table_entry (p
);
1357 /* Calculate the index of the object on the page; this is its bit
1358 position in the in_use_p bitmap. */
1359 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1360 word
= bit
/ HOST_BITS_PER_LONG
;
1361 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1363 return (entry
->in_use_p
[word
] & mask
) != 0;
1366 /* Return the size of the gc-able object P. */
1369 ggc_get_size (const void *p
)
1371 page_entry
*pe
= lookup_page_table_entry (p
);
1372 return OBJECT_SIZE (pe
->order
);
1375 /* Release the memory for object P. */
1380 page_entry
*pe
= lookup_page_table_entry (p
);
1381 size_t order
= pe
->order
;
1382 size_t size
= OBJECT_SIZE (order
);
1384 #ifdef GATHER_STATISTICS
1385 ggc_free_overhead (p
);
1388 if (GGC_DEBUG_LEVEL
>= 3)
1389 fprintf (G
.debug_file
,
1390 "Freeing object, actual size=%lu, at %p on %p\n",
1391 (unsigned long) size
, p
, (void *) pe
);
1393 #ifdef ENABLE_GC_CHECKING
1394 /* Poison the data, to indicate the data is garbage. */
1395 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (p
, size
));
1396 memset (p
, 0xa5, size
);
1398 /* Let valgrind know the object is free. */
1399 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (p
, size
));
1401 #ifdef ENABLE_GC_ALWAYS_COLLECT
1402 /* In the completely-anal-checking mode, we do *not* immediately free
1403 the data, but instead verify that the data is *actually* not
1404 reachable the next time we collect. */
1406 struct free_object
*fo
= XNEW (struct free_object
);
1408 fo
->next
= G
.free_object_list
;
1409 G
.free_object_list
= fo
;
1413 unsigned int bit_offset
, word
, bit
;
1415 G
.allocated
-= size
;
1417 /* Mark the object not-in-use. */
1418 bit_offset
= OFFSET_TO_BIT (((const char *) p
) - pe
->page
, order
);
1419 word
= bit_offset
/ HOST_BITS_PER_LONG
;
1420 bit
= bit_offset
% HOST_BITS_PER_LONG
;
1421 pe
->in_use_p
[word
] &= ~(1UL << bit
);
1423 if (pe
->num_free_objects
++ == 0)
1427 /* If the page is completely full, then it's supposed to
1428 be after all pages that aren't. Since we've freed one
1429 object from a page that was full, we need to move the
1430 page to the head of the list.
1432 PE is the node we want to move. Q is the previous node
1433 and P is the next node in the list. */
1435 if (q
&& q
->num_free_objects
== 0)
1441 /* If PE was at the end of the list, then Q becomes the
1442 new end of the list. If PE was not the end of the
1443 list, then we need to update the PREV field for P. */
1445 G
.page_tails
[order
] = q
;
1449 /* Move PE to the head of the list. */
1450 pe
->next
= G
.pages
[order
];
1452 G
.pages
[order
]->prev
= pe
;
1453 G
.pages
[order
] = pe
;
1456 /* Reset the hint bit to point to the only free object. */
1457 pe
->next_bit_hint
= bit_offset
;
1463 /* Subroutine of init_ggc which computes the pair of numbers used to
1464 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1466 This algorithm is taken from Granlund and Montgomery's paper
1467 "Division by Invariant Integers using Multiplication"
1468 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1472 compute_inverse (unsigned order
)
1477 size
= OBJECT_SIZE (order
);
1479 while (size
% 2 == 0)
1486 while (inv
* size
!= 1)
1487 inv
= inv
* (2 - inv
*size
);
1489 DIV_MULT (order
) = inv
;
1490 DIV_SHIFT (order
) = e
;
1493 /* Initialize the ggc-mmap allocator. */
1499 G
.pagesize
= getpagesize();
1500 G
.lg_pagesize
= exact_log2 (G
.pagesize
);
1502 #ifdef HAVE_MMAP_DEV_ZERO
1503 G
.dev_zero_fd
= open ("/dev/zero", O_RDONLY
);
1504 if (G
.dev_zero_fd
== -1)
1505 internal_error ("open /dev/zero: %m");
1509 G
.debug_file
= fopen ("ggc-mmap.debug", "w");
1511 G
.debug_file
= stdout
;
1515 /* StunOS has an amazing off-by-one error for the first mmap allocation
1516 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1517 believe, is an unaligned page allocation, which would cause us to
1518 hork badly if we tried to use it. */
1520 char *p
= alloc_anon (NULL
, G
.pagesize
);
1521 struct page_entry
*e
;
1522 if ((size_t)p
& (G
.pagesize
- 1))
1524 /* How losing. Discard this one and try another. If we still
1525 can't get something useful, give up. */
1527 p
= alloc_anon (NULL
, G
.pagesize
);
1528 gcc_assert (!((size_t)p
& (G
.pagesize
- 1)));
1531 /* We have a good page, might as well hold onto it... */
1532 e
= XCNEW (struct page_entry
);
1533 e
->bytes
= G
.pagesize
;
1535 e
->next
= G
.free_pages
;
1540 /* Initialize the object size table. */
1541 for (order
= 0; order
< HOST_BITS_PER_PTR
; ++order
)
1542 object_size_table
[order
] = (size_t) 1 << order
;
1543 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1545 size_t s
= extra_order_size_table
[order
- HOST_BITS_PER_PTR
];
1547 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1548 so that we're sure of getting aligned memory. */
1549 s
= ROUND_UP (s
, MAX_ALIGNMENT
);
1550 object_size_table
[order
] = s
;
1553 /* Initialize the objects-per-page and inverse tables. */
1554 for (order
= 0; order
< NUM_ORDERS
; ++order
)
1556 objects_per_page_table
[order
] = G
.pagesize
/ OBJECT_SIZE (order
);
1557 if (objects_per_page_table
[order
] == 0)
1558 objects_per_page_table
[order
] = 1;
1559 compute_inverse (order
);
1562 /* Reset the size_lookup array to put appropriately sized objects in
1563 the special orders. All objects bigger than the previous power
1564 of two, but no greater than the special size, should go in the
1566 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1571 i
= OBJECT_SIZE (order
);
1572 if (i
>= NUM_SIZE_LOOKUP
)
1575 for (o
= size_lookup
[i
]; o
== size_lookup
[i
]; --i
)
1576 size_lookup
[i
] = order
;
1581 G
.depth
= XNEWVEC (unsigned int, G
.depth_max
);
1583 G
.by_depth_in_use
= 0;
1584 G
.by_depth_max
= INITIAL_PTE_COUNT
;
1585 G
.by_depth
= XNEWVEC (page_entry
*, G
.by_depth_max
);
1586 G
.save_in_use
= XNEWVEC (unsigned long *, G
.by_depth_max
);
1589 /* Start a new GGC zone. */
1592 new_ggc_zone (const char *name ATTRIBUTE_UNUSED
)
1597 /* Destroy a GGC zone. */
1599 destroy_ggc_zone (struct alloc_zone
*zone ATTRIBUTE_UNUSED
)
1603 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1604 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1607 ggc_recalculate_in_use_p (page_entry
*p
)
1612 /* Because the past-the-end bit in in_use_p is always set, we
1613 pretend there is one additional object. */
1614 num_objects
= OBJECTS_IN_PAGE (p
) + 1;
1616 /* Reset the free object count. */
1617 p
->num_free_objects
= num_objects
;
1619 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1621 i
< CEIL (BITMAP_SIZE (num_objects
),
1622 sizeof (*p
->in_use_p
));
1627 /* Something is in use if it is marked, or if it was in use in a
1628 context further down the context stack. */
1629 p
->in_use_p
[i
] |= save_in_use_p (p
)[i
];
1631 /* Decrement the free object count for every object allocated. */
1632 for (j
= p
->in_use_p
[i
]; j
; j
>>= 1)
1633 p
->num_free_objects
-= (j
& 1);
1636 gcc_assert (p
->num_free_objects
< num_objects
);
1639 /* Unmark all objects. */
1646 for (order
= 2; order
< NUM_ORDERS
; order
++)
1650 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1652 size_t num_objects
= OBJECTS_IN_PAGE (p
);
1653 size_t bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
1655 /* The data should be page-aligned. */
1656 gcc_assert (!((size_t) p
->page
& (G
.pagesize
- 1)));
1658 /* Pages that aren't in the topmost context are not collected;
1659 nevertheless, we need their in-use bit vectors to store GC
1660 marks. So, back them up first. */
1661 if (p
->context_depth
< G
.context_depth
)
1663 if (! save_in_use_p (p
))
1664 save_in_use_p (p
) = XNEWVAR (unsigned long, bitmap_size
);
1665 memcpy (save_in_use_p (p
), p
->in_use_p
, bitmap_size
);
1668 /* Reset reset the number of free objects and clear the
1669 in-use bits. These will be adjusted by mark_obj. */
1670 p
->num_free_objects
= num_objects
;
1671 memset (p
->in_use_p
, 0, bitmap_size
);
1673 /* Make sure the one-past-the-end bit is always set. */
1674 p
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
1675 = ((unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
));
1680 /* Free all empty pages. Partially empty pages need no attention
1681 because the `mark' bit doubles as an `unused' bit. */
1688 for (order
= 2; order
< NUM_ORDERS
; order
++)
1690 /* The last page-entry to consider, regardless of entries
1691 placed at the end of the list. */
1692 page_entry
* const last
= G
.page_tails
[order
];
1695 size_t live_objects
;
1696 page_entry
*p
, *previous
;
1706 page_entry
*next
= p
->next
;
1708 /* Loop until all entries have been examined. */
1711 num_objects
= OBJECTS_IN_PAGE (p
);
1713 /* Add all live objects on this page to the count of
1714 allocated memory. */
1715 live_objects
= num_objects
- p
->num_free_objects
;
1717 G
.allocated
+= OBJECT_SIZE (order
) * live_objects
;
1719 /* Only objects on pages in the topmost context should get
1721 if (p
->context_depth
< G
.context_depth
)
1724 /* Remove the page if it's empty. */
1725 else if (live_objects
== 0)
1727 /* If P was the first page in the list, then NEXT
1728 becomes the new first page in the list, otherwise
1729 splice P out of the forward pointers. */
1731 G
.pages
[order
] = next
;
1733 previous
->next
= next
;
1735 /* Splice P out of the back pointers too. */
1737 next
->prev
= previous
;
1739 /* Are we removing the last element? */
1740 if (p
== G
.page_tails
[order
])
1741 G
.page_tails
[order
] = previous
;
1746 /* If the page is full, move it to the end. */
1747 else if (p
->num_free_objects
== 0)
1749 /* Don't move it if it's already at the end. */
1750 if (p
!= G
.page_tails
[order
])
1752 /* Move p to the end of the list. */
1754 p
->prev
= G
.page_tails
[order
];
1755 G
.page_tails
[order
]->next
= p
;
1757 /* Update the tail pointer... */
1758 G
.page_tails
[order
] = p
;
1760 /* ... and the head pointer, if necessary. */
1762 G
.pages
[order
] = next
;
1764 previous
->next
= next
;
1766 /* And update the backpointer in NEXT if necessary. */
1768 next
->prev
= previous
;
1774 /* If we've fallen through to here, it's a page in the
1775 topmost context that is neither full nor empty. Such a
1776 page must precede pages at lesser context depth in the
1777 list, so move it to the head. */
1778 else if (p
!= G
.pages
[order
])
1780 previous
->next
= p
->next
;
1782 /* Update the backchain in the next node if it exists. */
1784 p
->next
->prev
= previous
;
1786 /* Move P to the head of the list. */
1787 p
->next
= G
.pages
[order
];
1789 G
.pages
[order
]->prev
= p
;
1791 /* Update the head pointer. */
1794 /* Are we moving the last element? */
1795 if (G
.page_tails
[order
] == p
)
1796 G
.page_tails
[order
] = previous
;
1805 /* Now, restore the in_use_p vectors for any pages from contexts
1806 other than the current one. */
1807 for (p
= G
.pages
[order
]; p
; p
= p
->next
)
1808 if (p
->context_depth
!= G
.context_depth
)
1809 ggc_recalculate_in_use_p (p
);
1813 #ifdef ENABLE_GC_CHECKING
1814 /* Clobber all free objects. */
1821 for (order
= 2; order
< NUM_ORDERS
; order
++)
1823 size_t size
= OBJECT_SIZE (order
);
1826 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1831 if (p
->context_depth
!= G
.context_depth
)
1832 /* Since we don't do any collection for pages in pushed
1833 contexts, there's no need to do any poisoning. And
1834 besides, the IN_USE_P array isn't valid until we pop
1838 num_objects
= OBJECTS_IN_PAGE (p
);
1839 for (i
= 0; i
< num_objects
; i
++)
1842 word
= i
/ HOST_BITS_PER_LONG
;
1843 bit
= i
% HOST_BITS_PER_LONG
;
1844 if (((p
->in_use_p
[word
] >> bit
) & 1) == 0)
1846 char *object
= p
->page
+ i
* size
;
1848 /* Keep poison-by-write when we expect to use Valgrind,
1849 so the exact same memory semantics is kept, in case
1850 there are memory errors. We override this request
1852 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (object
,
1854 memset (object
, 0xa5, size
);
1856 /* Drop the handle to avoid handle leak. */
1857 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (object
, size
));
1864 #define poison_pages()
1867 #ifdef ENABLE_GC_ALWAYS_COLLECT
1868 /* Validate that the reportedly free objects actually are. */
1871 validate_free_objects (void)
1873 struct free_object
*f
, *next
, *still_free
= NULL
;
1875 for (f
= G
.free_object_list
; f
; f
= next
)
1877 page_entry
*pe
= lookup_page_table_entry (f
->object
);
1880 bit
= OFFSET_TO_BIT ((char *)f
->object
- pe
->page
, pe
->order
);
1881 word
= bit
/ HOST_BITS_PER_LONG
;
1882 bit
= bit
% HOST_BITS_PER_LONG
;
1885 /* Make certain it isn't visible from any root. Notice that we
1886 do this check before sweep_pages merges save_in_use_p. */
1887 gcc_assert (!(pe
->in_use_p
[word
] & (1UL << bit
)));
1889 /* If the object comes from an outer context, then retain the
1890 free_object entry, so that we can verify that the address
1891 isn't live on the stack in some outer context. */
1892 if (pe
->context_depth
!= G
.context_depth
)
1894 f
->next
= still_free
;
1901 G
.free_object_list
= still_free
;
1904 #define validate_free_objects()
1907 /* Top level mark-and-sweep routine. */
1912 /* Avoid frequent unnecessary work by skipping collection if the
1913 total allocations haven't expanded much since the last
1915 float allocated_last_gc
=
1916 MAX (G
.allocated_last_gc
, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE
) * 1024);
1918 float min_expand
= allocated_last_gc
* PARAM_VALUE (GGC_MIN_EXPAND
) / 100;
1920 if (G
.allocated
< allocated_last_gc
+ min_expand
&& !ggc_force_collect
)
1923 timevar_push (TV_GC
);
1925 fprintf (stderr
, " {GC %luk -> ", (unsigned long) G
.allocated
/ 1024);
1926 if (GGC_DEBUG_LEVEL
>= 2)
1927 fprintf (G
.debug_file
, "BEGIN COLLECTING\n");
1929 /* Zero the total allocated bytes. This will be recalculated in the
1933 /* Release the pages we freed the last time we collected, but didn't
1934 reuse in the interim. */
1937 /* Indicate that we've seen collections at this context depth. */
1938 G
.context_depth_collections
= ((unsigned long)1 << (G
.context_depth
+ 1)) - 1;
1942 #ifdef GATHER_STATISTICS
1943 ggc_prune_overhead_list ();
1946 validate_free_objects ();
1949 G
.allocated_last_gc
= G
.allocated
;
1951 timevar_pop (TV_GC
);
1954 fprintf (stderr
, "%luk}", (unsigned long) G
.allocated
/ 1024);
1955 if (GGC_DEBUG_LEVEL
>= 2)
1956 fprintf (G
.debug_file
, "END COLLECTING\n");
1959 /* Print allocation statistics. */
1960 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
1962 : ((x) < 1024*1024*10 \
1964 : (x) / (1024*1024))))
1965 #define STAT_LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
1968 ggc_print_statistics (void)
1970 struct ggc_statistics stats
;
1972 size_t total_overhead
= 0;
1974 /* Clear the statistics. */
1975 memset (&stats
, 0, sizeof (stats
));
1977 /* Make sure collection will really occur. */
1978 G
.allocated_last_gc
= 0;
1980 /* Collect and print the statistics common across collectors. */
1981 ggc_print_common_statistics (stderr
, &stats
);
1983 /* Release free pages so that we will not count the bytes allocated
1984 there as part of the total allocated memory. */
1987 /* Collect some information about the various sizes of
1990 "Memory still allocated at the end of the compilation process\n");
1991 fprintf (stderr
, "%-5s %10s %10s %10s\n",
1992 "Size", "Allocated", "Used", "Overhead");
1993 for (i
= 0; i
< NUM_ORDERS
; ++i
)
2000 /* Skip empty entries. */
2004 overhead
= allocated
= in_use
= 0;
2006 /* Figure out the total number of bytes allocated for objects of
2007 this size, and how many of them are actually in use. Also figure
2008 out how much memory the page table is using. */
2009 for (p
= G
.pages
[i
]; p
; p
= p
->next
)
2011 allocated
+= p
->bytes
;
2013 (OBJECTS_IN_PAGE (p
) - p
->num_free_objects
) * OBJECT_SIZE (i
);
2015 overhead
+= (sizeof (page_entry
) - sizeof (long)
2016 + BITMAP_SIZE (OBJECTS_IN_PAGE (p
) + 1));
2018 fprintf (stderr
, "%-5lu %10lu%c %10lu%c %10lu%c\n",
2019 (unsigned long) OBJECT_SIZE (i
),
2020 SCALE (allocated
), STAT_LABEL (allocated
),
2021 SCALE (in_use
), STAT_LABEL (in_use
),
2022 SCALE (overhead
), STAT_LABEL (overhead
));
2023 total_overhead
+= overhead
;
2025 fprintf (stderr
, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
2026 SCALE (G
.bytes_mapped
), STAT_LABEL (G
.bytes_mapped
),
2027 SCALE (G
.allocated
), STAT_LABEL(G
.allocated
),
2028 SCALE (total_overhead
), STAT_LABEL (total_overhead
));
2030 #ifdef GATHER_STATISTICS
2032 fprintf (stderr
, "\nTotal allocations and overheads during the compilation process\n");
2034 fprintf (stderr
, "Total Overhead: %10lld\n",
2035 G
.stats
.total_overhead
);
2036 fprintf (stderr
, "Total Allocated: %10lld\n",
2037 G
.stats
.total_allocated
);
2039 fprintf (stderr
, "Total Overhead under 32B: %10lld\n",
2040 G
.stats
.total_overhead_under32
);
2041 fprintf (stderr
, "Total Allocated under 32B: %10lld\n",
2042 G
.stats
.total_allocated_under32
);
2043 fprintf (stderr
, "Total Overhead under 64B: %10lld\n",
2044 G
.stats
.total_overhead_under64
);
2045 fprintf (stderr
, "Total Allocated under 64B: %10lld\n",
2046 G
.stats
.total_allocated_under64
);
2047 fprintf (stderr
, "Total Overhead under 128B: %10lld\n",
2048 G
.stats
.total_overhead_under128
);
2049 fprintf (stderr
, "Total Allocated under 128B: %10lld\n",
2050 G
.stats
.total_allocated_under128
);
2052 for (i
= 0; i
< NUM_ORDERS
; i
++)
2053 if (G
.stats
.total_allocated_per_order
[i
])
2055 fprintf (stderr
, "Total Overhead page size %7lu: %10lld\n",
2056 (unsigned long) OBJECT_SIZE (i
),
2057 G
.stats
.total_overhead_per_order
[i
]);
2058 fprintf (stderr
, "Total Allocated page size %7lu: %10lld\n",
2059 (unsigned long) OBJECT_SIZE (i
),
2060 G
.stats
.total_allocated_per_order
[i
]);
2066 struct ggc_pch_ondisk
2068 unsigned totals
[NUM_ORDERS
];
2073 struct ggc_pch_ondisk d
;
2074 size_t base
[NUM_ORDERS
];
2075 size_t written
[NUM_ORDERS
];
2078 struct ggc_pch_data
*
2081 return XCNEW (struct ggc_pch_data
);
2085 ggc_pch_count_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2086 size_t size
, bool is_string ATTRIBUTE_UNUSED
,
2087 enum gt_types_enum type ATTRIBUTE_UNUSED
)
2091 if (size
< NUM_SIZE_LOOKUP
)
2092 order
= size_lookup
[size
];
2096 while (size
> OBJECT_SIZE (order
))
2100 d
->d
.totals
[order
]++;
2104 ggc_pch_total_size (struct ggc_pch_data
*d
)
2109 for (i
= 0; i
< NUM_ORDERS
; i
++)
2110 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2115 ggc_pch_this_base (struct ggc_pch_data
*d
, void *base
)
2117 size_t a
= (size_t) base
;
2120 for (i
= 0; i
< NUM_ORDERS
; i
++)
2123 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2129 ggc_pch_alloc_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2130 size_t size
, bool is_string ATTRIBUTE_UNUSED
,
2131 enum gt_types_enum type ATTRIBUTE_UNUSED
)
2136 if (size
< NUM_SIZE_LOOKUP
)
2137 order
= size_lookup
[size
];
2141 while (size
> OBJECT_SIZE (order
))
2145 result
= (char *) d
->base
[order
];
2146 d
->base
[order
] += OBJECT_SIZE (order
);
2151 ggc_pch_prepare_write (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2152 FILE *f ATTRIBUTE_UNUSED
)
2154 /* Nothing to do. */
2158 ggc_pch_write_object (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2159 FILE *f
, void *x
, void *newx ATTRIBUTE_UNUSED
,
2160 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
2163 static const char emptyBytes
[256];
2165 if (size
< NUM_SIZE_LOOKUP
)
2166 order
= size_lookup
[size
];
2170 while (size
> OBJECT_SIZE (order
))
2174 if (fwrite (x
, size
, 1, f
) != 1)
2175 fatal_error ("can't write PCH file: %m");
2177 /* If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
2178 object out to OBJECT_SIZE(order). This happens for strings. */
2180 if (size
!= OBJECT_SIZE (order
))
2182 unsigned padding
= OBJECT_SIZE(order
) - size
;
2184 /* To speed small writes, we use a nulled-out array that's larger
2185 than most padding requests as the source for our null bytes. This
2186 permits us to do the padding with fwrite() rather than fseek(), and
2187 limits the chance the OS may try to flush any outstanding writes. */
2188 if (padding
<= sizeof(emptyBytes
))
2190 if (fwrite (emptyBytes
, 1, padding
, f
) != padding
)
2191 fatal_error ("can't write PCH file");
2195 /* Larger than our buffer? Just default to fseek. */
2196 if (fseek (f
, padding
, SEEK_CUR
) != 0)
2197 fatal_error ("can't write PCH file");
2201 d
->written
[order
]++;
2202 if (d
->written
[order
] == d
->d
.totals
[order
]
2203 && fseek (f
, ROUND_UP_VALUE (d
->d
.totals
[order
] * OBJECT_SIZE (order
),
2206 fatal_error ("can't write PCH file: %m");
2210 ggc_pch_finish (struct ggc_pch_data
*d
, FILE *f
)
2212 if (fwrite (&d
->d
, sizeof (d
->d
), 1, f
) != 1)
2213 fatal_error ("can't write PCH file: %m");
2217 /* Move the PCH PTE entries just added to the end of by_depth, to the
2221 move_ptes_to_front (int count_old_page_tables
, int count_new_page_tables
)
2225 /* First, we swap the new entries to the front of the varrays. */
2226 page_entry
**new_by_depth
;
2227 unsigned long **new_save_in_use
;
2229 new_by_depth
= XNEWVEC (page_entry
*, G
.by_depth_max
);
2230 new_save_in_use
= XNEWVEC (unsigned long *, G
.by_depth_max
);
2232 memcpy (&new_by_depth
[0],
2233 &G
.by_depth
[count_old_page_tables
],
2234 count_new_page_tables
* sizeof (void *));
2235 memcpy (&new_by_depth
[count_new_page_tables
],
2237 count_old_page_tables
* sizeof (void *));
2238 memcpy (&new_save_in_use
[0],
2239 &G
.save_in_use
[count_old_page_tables
],
2240 count_new_page_tables
* sizeof (void *));
2241 memcpy (&new_save_in_use
[count_new_page_tables
],
2243 count_old_page_tables
* sizeof (void *));
2246 free (G
.save_in_use
);
2248 G
.by_depth
= new_by_depth
;
2249 G
.save_in_use
= new_save_in_use
;
2251 /* Now update all the index_by_depth fields. */
2252 for (i
= G
.by_depth_in_use
; i
> 0; --i
)
2254 page_entry
*p
= G
.by_depth
[i
-1];
2255 p
->index_by_depth
= i
-1;
2258 /* And last, we update the depth pointers in G.depth. The first
2259 entry is already 0, and context 0 entries always start at index
2260 0, so there is nothing to update in the first slot. We need a
2261 second slot, only if we have old ptes, and if we do, they start
2262 at index count_new_page_tables. */
2263 if (count_old_page_tables
)
2264 push_depth (count_new_page_tables
);
2268 ggc_pch_read (FILE *f
, void *addr
)
2270 struct ggc_pch_ondisk d
;
2272 char *offs
= (char *) addr
;
2273 unsigned long count_old_page_tables
;
2274 unsigned long count_new_page_tables
;
2276 count_old_page_tables
= G
.by_depth_in_use
;
2278 /* We've just read in a PCH file. So, every object that used to be
2279 allocated is now free. */
2281 #ifdef ENABLE_GC_CHECKING
2284 /* Since we free all the allocated objects, the free list becomes
2285 useless. Validate it now, which will also clear it. */
2286 validate_free_objects();
2288 /* No object read from a PCH file should ever be freed. So, set the
2289 context depth to 1, and set the depth of all the currently-allocated
2290 pages to be 1 too. PCH pages will have depth 0. */
2291 gcc_assert (!G
.context_depth
);
2292 G
.context_depth
= 1;
2293 for (i
= 0; i
< NUM_ORDERS
; i
++)
2296 for (p
= G
.pages
[i
]; p
!= NULL
; p
= p
->next
)
2297 p
->context_depth
= G
.context_depth
;
2300 /* Allocate the appropriate page-table entries for the pages read from
2302 if (fread (&d
, sizeof (d
), 1, f
) != 1)
2303 fatal_error ("can't read PCH file: %m");
2305 for (i
= 0; i
< NUM_ORDERS
; i
++)
2307 struct page_entry
*entry
;
2313 if (d
.totals
[i
] == 0)
2316 bytes
= ROUND_UP (d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2317 num_objs
= bytes
/ OBJECT_SIZE (i
);
2318 entry
= XCNEWVAR (struct page_entry
, (sizeof (struct page_entry
)
2320 + BITMAP_SIZE (num_objs
+ 1)));
2321 entry
->bytes
= bytes
;
2323 entry
->context_depth
= 0;
2325 entry
->num_free_objects
= 0;
2329 j
+ HOST_BITS_PER_LONG
<= num_objs
+ 1;
2330 j
+= HOST_BITS_PER_LONG
)
2331 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
] = -1;
2332 for (; j
< num_objs
+ 1; j
++)
2333 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
]
2334 |= 1L << (j
% HOST_BITS_PER_LONG
);
2336 for (pte
= entry
->page
;
2337 pte
< entry
->page
+ entry
->bytes
;
2339 set_page_table_entry (pte
, entry
);
2341 if (G
.page_tails
[i
] != NULL
)
2342 G
.page_tails
[i
]->next
= entry
;
2345 G
.page_tails
[i
] = entry
;
2347 /* We start off by just adding all the new information to the
2348 end of the varrays, later, we will move the new information
2349 to the front of the varrays, as the PCH page tables are at
2351 push_by_depth (entry
, 0);
2354 /* Now, we update the various data structures that speed page table
2356 count_new_page_tables
= G
.by_depth_in_use
- count_old_page_tables
;
2358 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
);
2360 /* Update the statistics. */
2361 G
.allocated
= G
.allocated_last_gc
= offs
- (char *)addr
;