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, 51 Franklin Street, Fifth Floor, 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 var_ann_d
),
190 sizeof (struct tree_decl_non_common
),
191 sizeof (struct tree_field_decl
),
192 sizeof (struct tree_parm_decl
),
193 sizeof (struct tree_var_decl
),
194 sizeof (struct tree_list
),
195 sizeof (struct tree_ssa_name
),
196 sizeof (struct function
),
197 sizeof (struct basic_block_def
),
198 sizeof (bitmap_element
),
199 /* PHI nodes with one to three arguments are already covered by the
201 sizeof (struct tree_phi_node
) + sizeof (struct phi_arg_d
) * 3,
203 RTL_SIZE (2), /* MEM, PLUS, etc. */
204 RTL_SIZE (9), /* INSN */
207 /* The total number of orders. */
209 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
211 /* We use this structure to determine the alignment required for
212 allocations. For power-of-two sized allocations, that's not a
213 problem, but it does matter for odd-sized allocations. */
215 struct max_alignment
{
223 /* The biggest alignment required. */
225 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
227 /* Compute the smallest nonnegative number which when added to X gives
230 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
232 /* Compute the smallest multiple of F that is >= X. */
234 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
236 /* The Ith entry is the number of objects on a page or order I. */
238 static unsigned objects_per_page_table
[NUM_ORDERS
];
240 /* The Ith entry is the size of an object on a page of order I. */
242 static size_t object_size_table
[NUM_ORDERS
];
244 /* The Ith entry is a pair of numbers (mult, shift) such that
245 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
246 for all k evenly divisible by OBJECT_SIZE(I). */
253 inverse_table
[NUM_ORDERS
];
255 /* A page_entry records the status of an allocation page. This
256 structure is dynamically sized to fit the bitmap in_use_p. */
257 typedef struct page_entry
259 /* The next page-entry with objects of the same size, or NULL if
260 this is the last page-entry. */
261 struct page_entry
*next
;
263 /* The previous page-entry with objects of the same size, or NULL if
264 this is the first page-entry. The PREV pointer exists solely to
265 keep the cost of ggc_free manageable. */
266 struct page_entry
*prev
;
268 /* The number of bytes allocated. (This will always be a multiple
269 of the host system page size.) */
272 /* The address at which the memory is allocated. */
275 #ifdef USING_MALLOC_PAGE_GROUPS
276 /* Back pointer to the page group this page came from. */
277 struct page_group
*group
;
280 /* This is the index in the by_depth varray where this page table
282 unsigned long index_by_depth
;
284 /* Context depth of this page. */
285 unsigned short context_depth
;
287 /* The number of free objects remaining on this page. */
288 unsigned short num_free_objects
;
290 /* A likely candidate for the bit position of a free object for the
291 next allocation from this page. */
292 unsigned short next_bit_hint
;
294 /* The lg of size of objects allocated from this page. */
297 /* A bit vector indicating whether or not objects are in use. The
298 Nth bit is one if the Nth object on this page is allocated. This
299 array is dynamically sized. */
300 unsigned long in_use_p
[1];
303 #ifdef USING_MALLOC_PAGE_GROUPS
304 /* A page_group describes a large allocation from malloc, from which
305 we parcel out aligned pages. */
306 typedef struct page_group
308 /* A linked list of all extant page groups. */
309 struct page_group
*next
;
311 /* The address we received from malloc. */
314 /* The size of the block. */
317 /* A bitmask of pages in use. */
322 #if HOST_BITS_PER_PTR <= 32
324 /* On 32-bit hosts, we use a two level page table, as pictured above. */
325 typedef page_entry
**page_table
[PAGE_L1_SIZE
];
329 /* On 64-bit hosts, we use the same two level page tables plus a linked
330 list that disambiguates the top 32-bits. There will almost always be
331 exactly one entry in the list. */
332 typedef struct page_table_chain
334 struct page_table_chain
*next
;
336 page_entry
**table
[PAGE_L1_SIZE
];
341 /* The rest of the global variables. */
342 static struct globals
344 /* The Nth element in this array is a page with objects of size 2^N.
345 If there are any pages with free objects, they will be at the
346 head of the list. NULL if there are no page-entries for this
348 page_entry
*pages
[NUM_ORDERS
];
350 /* The Nth element in this array is the last page with objects of
351 size 2^N. NULL if there are no page-entries for this object
353 page_entry
*page_tails
[NUM_ORDERS
];
355 /* Lookup table for associating allocation pages with object addresses. */
358 /* The system's page size. */
362 /* Bytes currently allocated. */
365 /* Bytes currently allocated at the end of the last collection. */
366 size_t allocated_last_gc
;
368 /* Total amount of memory mapped. */
371 /* Bit N set if any allocations have been done at context depth N. */
372 unsigned long context_depth_allocations
;
374 /* Bit N set if any collections have been done at context depth N. */
375 unsigned long context_depth_collections
;
377 /* The current depth in the context stack. */
378 unsigned short context_depth
;
380 /* A file descriptor open to /dev/zero for reading. */
381 #if defined (HAVE_MMAP_DEV_ZERO)
385 /* A cache of free system pages. */
386 page_entry
*free_pages
;
388 #ifdef USING_MALLOC_PAGE_GROUPS
389 page_group
*page_groups
;
392 /* The file descriptor for debugging output. */
395 /* Current number of elements in use in depth below. */
396 unsigned int depth_in_use
;
398 /* Maximum number of elements that can be used before resizing. */
399 unsigned int depth_max
;
401 /* Each element of this arry is an index in by_depth where the given
402 depth starts. This structure is indexed by that given depth we
403 are interested in. */
406 /* Current number of elements in use in by_depth below. */
407 unsigned int by_depth_in_use
;
409 /* Maximum number of elements that can be used before resizing. */
410 unsigned int by_depth_max
;
412 /* Each element of this array is a pointer to a page_entry, all
413 page_entries can be found in here by increasing depth.
414 index_by_depth in the page_entry is the index into this data
415 structure where that page_entry can be found. This is used to
416 speed up finding all page_entries at a particular depth. */
417 page_entry
**by_depth
;
419 /* Each element is a pointer to the saved in_use_p bits, if any,
420 zero otherwise. We allocate them all together, to enable a
421 better runtime data access pattern. */
422 unsigned long **save_in_use
;
424 #ifdef ENABLE_GC_ALWAYS_COLLECT
425 /* List of free objects to be verified as actually free on the
430 struct free_object
*next
;
434 #ifdef GATHER_STATISTICS
437 /* Total memory allocated with ggc_alloc. */
438 unsigned long long total_allocated
;
439 /* Total overhead for memory to be allocated with ggc_alloc. */
440 unsigned long long total_overhead
;
442 /* Total allocations and overhead for sizes less than 32, 64 and 128.
443 These sizes are interesting because they are typical cache line
446 unsigned long long total_allocated_under32
;
447 unsigned long long total_overhead_under32
;
449 unsigned long long total_allocated_under64
;
450 unsigned long long total_overhead_under64
;
452 unsigned long long total_allocated_under128
;
453 unsigned long long total_overhead_under128
;
455 /* The allocations for each of the allocation orders. */
456 unsigned long long total_allocated_per_order
[NUM_ORDERS
];
458 /* The overhead for each of the allocation orders. */
459 unsigned long long total_overhead_per_order
[NUM_ORDERS
];
464 /* The size in bytes required to maintain a bitmap for the objects
466 #define BITMAP_SIZE(Num_objects) \
467 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
469 /* Allocate pages in chunks of this size, to throttle calls to memory
470 allocation routines. The first page is used, the rest go onto the
471 free list. This cannot be larger than HOST_BITS_PER_INT for the
472 in_use bitmask for page_group. Hosts that need a different value
473 can override this by defining GGC_QUIRE_SIZE explicitly. */
474 #ifndef GGC_QUIRE_SIZE
476 # define GGC_QUIRE_SIZE 256
478 # define GGC_QUIRE_SIZE 16
482 /* Initial guess as to how many page table entries we might need. */
483 #define INITIAL_PTE_COUNT 128
485 static int ggc_allocated_p (const void *);
486 static page_entry
*lookup_page_table_entry (const void *);
487 static void set_page_table_entry (void *, page_entry
*);
489 static char *alloc_anon (char *, size_t);
491 #ifdef USING_MALLOC_PAGE_GROUPS
492 static size_t page_group_index (char *, char *);
493 static void set_page_group_in_use (page_group
*, char *);
494 static void clear_page_group_in_use (page_group
*, char *);
496 static struct page_entry
* alloc_page (unsigned);
497 static void free_page (struct page_entry
*);
498 static void release_pages (void);
499 static void clear_marks (void);
500 static void sweep_pages (void);
501 static void ggc_recalculate_in_use_p (page_entry
*);
502 static void compute_inverse (unsigned);
503 static inline void adjust_depth (void);
504 static void move_ptes_to_front (int, int);
506 void debug_print_page_list (int);
507 static void push_depth (unsigned int);
508 static void push_by_depth (page_entry
*, unsigned long *);
510 /* Push an entry onto G.depth. */
513 push_depth (unsigned int i
)
515 if (G
.depth_in_use
>= G
.depth_max
)
518 G
.depth
= xrealloc (G
.depth
, G
.depth_max
* sizeof (unsigned int));
520 G
.depth
[G
.depth_in_use
++] = i
;
523 /* Push an entry onto G.by_depth and G.save_in_use. */
526 push_by_depth (page_entry
*p
, unsigned long *s
)
528 if (G
.by_depth_in_use
>= G
.by_depth_max
)
531 G
.by_depth
= xrealloc (G
.by_depth
,
532 G
.by_depth_max
* sizeof (page_entry
*));
533 G
.save_in_use
= xrealloc (G
.save_in_use
,
534 G
.by_depth_max
* sizeof (unsigned long *));
536 G
.by_depth
[G
.by_depth_in_use
] = p
;
537 G
.save_in_use
[G
.by_depth_in_use
++] = s
;
540 #if (GCC_VERSION < 3001)
541 #define prefetch(X) ((void) X)
543 #define prefetch(X) __builtin_prefetch (X)
546 #define save_in_use_p_i(__i) \
548 #define save_in_use_p(__p) \
549 (save_in_use_p_i (__p->index_by_depth))
551 /* Returns nonzero if P was allocated in GC'able memory. */
554 ggc_allocated_p (const void *p
)
559 #if HOST_BITS_PER_PTR <= 32
562 page_table table
= G
.lookup
;
563 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
568 if (table
->high_bits
== high_bits
)
572 base
= &table
->table
[0];
575 /* Extract the level 1 and 2 indices. */
579 return base
[L1
] && base
[L1
][L2
];
582 /* Traverse the page table and find the entry for a page.
583 Die (probably) if the object wasn't allocated via GC. */
585 static inline page_entry
*
586 lookup_page_table_entry (const void *p
)
591 #if HOST_BITS_PER_PTR <= 32
594 page_table table
= G
.lookup
;
595 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
596 while (table
->high_bits
!= high_bits
)
598 base
= &table
->table
[0];
601 /* Extract the level 1 and 2 indices. */
608 /* Set the page table entry for a page. */
611 set_page_table_entry (void *p
, page_entry
*entry
)
616 #if HOST_BITS_PER_PTR <= 32
620 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
621 for (table
= G
.lookup
; table
; table
= table
->next
)
622 if (table
->high_bits
== high_bits
)
625 /* Not found -- allocate a new table. */
626 table
= xcalloc (1, sizeof(*table
));
627 table
->next
= G
.lookup
;
628 table
->high_bits
= high_bits
;
631 base
= &table
->table
[0];
634 /* Extract the level 1 and 2 indices. */
638 if (base
[L1
] == NULL
)
639 base
[L1
] = XCNEWVEC (page_entry
*, PAGE_L2_SIZE
);
641 base
[L1
][L2
] = entry
;
644 /* Prints the page-entry for object size ORDER, for debugging. */
647 debug_print_page_list (int order
)
650 printf ("Head=%p, Tail=%p:\n", (void *) G
.pages
[order
],
651 (void *) G
.page_tails
[order
]);
655 printf ("%p(%1d|%3d) -> ", (void *) p
, p
->context_depth
,
656 p
->num_free_objects
);
664 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
665 (if non-null). The ifdef structure here is intended to cause a
666 compile error unless exactly one of the HAVE_* is defined. */
669 alloc_anon (char *pref ATTRIBUTE_UNUSED
, size_t size
)
671 #ifdef HAVE_MMAP_ANON
672 char *page
= mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
673 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
675 #ifdef HAVE_MMAP_DEV_ZERO
676 char *page
= mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
677 MAP_PRIVATE
, G
.dev_zero_fd
, 0);
680 if (page
== (char *) MAP_FAILED
)
682 perror ("virtual memory exhausted");
683 exit (FATAL_EXIT_CODE
);
686 /* Remember that we allocated this memory. */
687 G
.bytes_mapped
+= size
;
689 /* Pretend we don't have access to the allocated pages. We'll enable
690 access to smaller pieces of the area in ggc_alloc. Discard the
691 handle to avoid handle leak. */
692 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (page
, size
));
697 #ifdef USING_MALLOC_PAGE_GROUPS
698 /* Compute the index for this page into the page group. */
701 page_group_index (char *allocation
, char *page
)
703 return (size_t) (page
- allocation
) >> G
.lg_pagesize
;
706 /* Set and clear the in_use bit for this page in the page group. */
709 set_page_group_in_use (page_group
*group
, char *page
)
711 group
->in_use
|= 1 << page_group_index (group
->allocation
, page
);
715 clear_page_group_in_use (page_group
*group
, char *page
)
717 group
->in_use
&= ~(1 << page_group_index (group
->allocation
, page
));
721 /* Allocate a new page for allocating objects of size 2^ORDER,
722 and return an entry for it. The entry is not added to the
723 appropriate page_table list. */
725 static inline struct page_entry
*
726 alloc_page (unsigned order
)
728 struct page_entry
*entry
, *p
, **pp
;
732 size_t page_entry_size
;
734 #ifdef USING_MALLOC_PAGE_GROUPS
738 num_objects
= OBJECTS_PER_PAGE (order
);
739 bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
740 page_entry_size
= sizeof (page_entry
) - sizeof (long) + bitmap_size
;
741 entry_size
= num_objects
* OBJECT_SIZE (order
);
742 if (entry_size
< G
.pagesize
)
743 entry_size
= G
.pagesize
;
748 /* Check the list of free pages for one we can use. */
749 for (pp
= &G
.free_pages
, p
= *pp
; p
; pp
= &p
->next
, p
= *pp
)
750 if (p
->bytes
== entry_size
)
755 /* Recycle the allocated memory from this page ... */
759 #ifdef USING_MALLOC_PAGE_GROUPS
763 /* ... and, if possible, the page entry itself. */
764 if (p
->order
== order
)
767 memset (entry
, 0, page_entry_size
);
773 else if (entry_size
== G
.pagesize
)
775 /* We want just one page. Allocate a bunch of them and put the
776 extras on the freelist. (Can only do this optimization with
777 mmap for backing store.) */
778 struct page_entry
*e
, *f
= G
.free_pages
;
781 page
= alloc_anon (NULL
, G
.pagesize
* GGC_QUIRE_SIZE
);
783 /* This loop counts down so that the chain will be in ascending
785 for (i
= GGC_QUIRE_SIZE
- 1; i
>= 1; i
--)
787 e
= xcalloc (1, page_entry_size
);
789 e
->bytes
= G
.pagesize
;
790 e
->page
= page
+ (i
<< G
.lg_pagesize
);
798 page
= alloc_anon (NULL
, entry_size
);
800 #ifdef USING_MALLOC_PAGE_GROUPS
803 /* Allocate a large block of memory and serve out the aligned
804 pages therein. This results in much less memory wastage
805 than the traditional implementation of valloc. */
807 char *allocation
, *a
, *enda
;
808 size_t alloc_size
, head_slop
, tail_slop
;
809 int multiple_pages
= (entry_size
== G
.pagesize
);
812 alloc_size
= GGC_QUIRE_SIZE
* G
.pagesize
;
814 alloc_size
= entry_size
+ G
.pagesize
- 1;
815 allocation
= xmalloc (alloc_size
);
817 page
= (char *) (((size_t) allocation
+ G
.pagesize
- 1) & -G
.pagesize
);
818 head_slop
= page
- allocation
;
820 tail_slop
= ((size_t) allocation
+ alloc_size
) & (G
.pagesize
- 1);
822 tail_slop
= alloc_size
- entry_size
- head_slop
;
823 enda
= allocation
+ alloc_size
- tail_slop
;
825 /* We allocated N pages, which are likely not aligned, leaving
826 us with N-1 usable pages. We plan to place the page_group
827 structure somewhere in the slop. */
828 if (head_slop
>= sizeof (page_group
))
829 group
= (page_group
*)page
- 1;
832 /* We magically got an aligned allocation. Too bad, we have
833 to waste a page anyway. */
837 tail_slop
+= G
.pagesize
;
839 gcc_assert (tail_slop
>= sizeof (page_group
));
840 group
= (page_group
*)enda
;
841 tail_slop
-= sizeof (page_group
);
844 /* Remember that we allocated this memory. */
845 group
->next
= G
.page_groups
;
846 group
->allocation
= allocation
;
847 group
->alloc_size
= alloc_size
;
849 G
.page_groups
= group
;
850 G
.bytes_mapped
+= alloc_size
;
852 /* If we allocated multiple pages, put the rest on the free list. */
855 struct page_entry
*e
, *f
= G
.free_pages
;
856 for (a
= enda
- G
.pagesize
; a
!= page
; a
-= G
.pagesize
)
858 e
= xcalloc (1, page_entry_size
);
860 e
->bytes
= G
.pagesize
;
872 entry
= xcalloc (1, page_entry_size
);
874 entry
->bytes
= entry_size
;
876 entry
->context_depth
= G
.context_depth
;
877 entry
->order
= order
;
878 entry
->num_free_objects
= num_objects
;
879 entry
->next_bit_hint
= 1;
881 G
.context_depth_allocations
|= (unsigned long)1 << G
.context_depth
;
883 #ifdef USING_MALLOC_PAGE_GROUPS
884 entry
->group
= group
;
885 set_page_group_in_use (group
, page
);
888 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
889 increment the hint. */
890 entry
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
891 = (unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
);
893 set_page_table_entry (page
, entry
);
895 if (GGC_DEBUG_LEVEL
>= 2)
896 fprintf (G
.debug_file
,
897 "Allocating page at %p, object size=%lu, data %p-%p\n",
898 (void *) entry
, (unsigned long) OBJECT_SIZE (order
), page
,
899 page
+ entry_size
- 1);
904 /* Adjust the size of G.depth so that no index greater than the one
905 used by the top of the G.by_depth is used. */
912 if (G
.by_depth_in_use
)
914 top
= G
.by_depth
[G
.by_depth_in_use
-1];
916 /* Peel back indices in depth that index into by_depth, so that
917 as new elements are added to by_depth, we note the indices
918 of those elements, if they are for new context depths. */
919 while (G
.depth_in_use
> (size_t)top
->context_depth
+1)
924 /* For a page that is no longer needed, put it on the free page list. */
927 free_page (page_entry
*entry
)
929 if (GGC_DEBUG_LEVEL
>= 2)
930 fprintf (G
.debug_file
,
931 "Deallocating page at %p, data %p-%p\n", (void *) entry
,
932 entry
->page
, entry
->page
+ entry
->bytes
- 1);
934 /* Mark the page as inaccessible. Discard the handle to avoid handle
936 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (entry
->page
, entry
->bytes
));
938 set_page_table_entry (entry
->page
, NULL
);
940 #ifdef USING_MALLOC_PAGE_GROUPS
941 clear_page_group_in_use (entry
->group
, entry
->page
);
944 if (G
.by_depth_in_use
> 1)
946 page_entry
*top
= G
.by_depth
[G
.by_depth_in_use
-1];
947 int i
= entry
->index_by_depth
;
949 /* We cannot free a page from a context deeper than the current
951 gcc_assert (entry
->context_depth
== top
->context_depth
);
953 /* Put top element into freed slot. */
955 G
.save_in_use
[i
] = G
.save_in_use
[G
.by_depth_in_use
-1];
956 top
->index_by_depth
= i
;
962 entry
->next
= G
.free_pages
;
963 G
.free_pages
= entry
;
966 /* Release the free page cache to the system. */
972 page_entry
*p
, *next
;
976 /* Gather up adjacent pages so they are unmapped together. */
987 while (p
&& p
->page
== start
+ len
)
996 G
.bytes_mapped
-= len
;
1001 #ifdef USING_MALLOC_PAGE_GROUPS
1002 page_entry
**pp
, *p
;
1003 page_group
**gp
, *g
;
1005 /* Remove all pages from free page groups from the list. */
1007 while ((p
= *pp
) != NULL
)
1008 if (p
->group
->in_use
== 0)
1016 /* Remove all free page groups, and release the storage. */
1017 gp
= &G
.page_groups
;
1018 while ((g
= *gp
) != NULL
)
1022 G
.bytes_mapped
-= g
->alloc_size
;
1023 free (g
->allocation
);
1030 /* This table provides a fast way to determine ceil(log_2(size)) for
1031 allocation requests. The minimum allocation size is eight bytes. */
1033 static unsigned char size_lookup
[511] =
1035 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
1036 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1037 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1038 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1039 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1040 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1041 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1042 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1043 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1044 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1045 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1046 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1047 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1048 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1049 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1050 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1051 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1052 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1053 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1054 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1055 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1056 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1057 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1058 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1059 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1060 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1061 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1062 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1063 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1064 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1065 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1066 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
1069 /* Typed allocation function. Does nothing special in this collector. */
1072 ggc_alloc_typed_stat (enum gt_types_enum type ATTRIBUTE_UNUSED
, size_t size
1075 return ggc_alloc_stat (size PASS_MEM_STAT
);
1078 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1081 ggc_alloc_stat (size_t size MEM_STAT_DECL
)
1083 size_t order
, word
, bit
, object_offset
, object_size
;
1084 struct page_entry
*entry
;
1089 order
= size_lookup
[size
];
1090 object_size
= OBJECT_SIZE (order
);
1095 while (size
> (object_size
= OBJECT_SIZE (order
)))
1099 /* If there are non-full pages for this size allocation, they are at
1100 the head of the list. */
1101 entry
= G
.pages
[order
];
1103 /* If there is no page for this object size, or all pages in this
1104 context are full, allocate a new page. */
1105 if (entry
== NULL
|| entry
->num_free_objects
== 0)
1107 struct page_entry
*new_entry
;
1108 new_entry
= alloc_page (order
);
1110 new_entry
->index_by_depth
= G
.by_depth_in_use
;
1111 push_by_depth (new_entry
, 0);
1113 /* We can skip context depths, if we do, make sure we go all the
1114 way to the new depth. */
1115 while (new_entry
->context_depth
>= G
.depth_in_use
)
1116 push_depth (G
.by_depth_in_use
-1);
1118 /* If this is the only entry, it's also the tail. If it is not
1119 the only entry, then we must update the PREV pointer of the
1120 ENTRY (G.pages[order]) to point to our new page entry. */
1122 G
.page_tails
[order
] = new_entry
;
1124 entry
->prev
= new_entry
;
1126 /* Put new pages at the head of the page list. By definition the
1127 entry at the head of the list always has a NULL pointer. */
1128 new_entry
->next
= entry
;
1129 new_entry
->prev
= NULL
;
1131 G
.pages
[order
] = new_entry
;
1133 /* For a new page, we know the word and bit positions (in the
1134 in_use bitmap) of the first available object -- they're zero. */
1135 new_entry
->next_bit_hint
= 1;
1142 /* First try to use the hint left from the previous allocation
1143 to locate a clear bit in the in-use bitmap. We've made sure
1144 that the one-past-the-end bit is always set, so if the hint
1145 has run over, this test will fail. */
1146 unsigned hint
= entry
->next_bit_hint
;
1147 word
= hint
/ HOST_BITS_PER_LONG
;
1148 bit
= hint
% HOST_BITS_PER_LONG
;
1150 /* If the hint didn't work, scan the bitmap from the beginning. */
1151 if ((entry
->in_use_p
[word
] >> bit
) & 1)
1154 while (~entry
->in_use_p
[word
] == 0)
1157 #if GCC_VERSION >= 3004
1158 bit
= __builtin_ctzl (~entry
->in_use_p
[word
]);
1160 while ((entry
->in_use_p
[word
] >> bit
) & 1)
1164 hint
= word
* HOST_BITS_PER_LONG
+ bit
;
1167 /* Next time, try the next bit. */
1168 entry
->next_bit_hint
= hint
+ 1;
1170 object_offset
= hint
* object_size
;
1173 /* Set the in-use bit. */
1174 entry
->in_use_p
[word
] |= ((unsigned long) 1 << bit
);
1176 /* Keep a running total of the number of free objects. If this page
1177 fills up, we may have to move it to the end of the list if the
1178 next page isn't full. If the next page is full, all subsequent
1179 pages are full, so there's no need to move it. */
1180 if (--entry
->num_free_objects
== 0
1181 && entry
->next
!= NULL
1182 && entry
->next
->num_free_objects
> 0)
1184 /* We have a new head for the list. */
1185 G
.pages
[order
] = entry
->next
;
1187 /* We are moving ENTRY to the end of the page table list.
1188 The new page at the head of the list will have NULL in
1189 its PREV field and ENTRY will have NULL in its NEXT field. */
1190 entry
->next
->prev
= NULL
;
1193 /* Append ENTRY to the tail of the list. */
1194 entry
->prev
= G
.page_tails
[order
];
1195 G
.page_tails
[order
]->next
= entry
;
1196 G
.page_tails
[order
] = entry
;
1199 /* Calculate the object's address. */
1200 result
= entry
->page
+ object_offset
;
1201 #ifdef GATHER_STATISTICS
1202 ggc_record_overhead (OBJECT_SIZE (order
), OBJECT_SIZE (order
) - size
,
1203 result PASS_MEM_STAT
);
1206 #ifdef ENABLE_GC_CHECKING
1207 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1208 exact same semantics in presence of memory bugs, regardless of
1209 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1210 handle to avoid handle leak. */
1211 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, object_size
));
1213 /* `Poison' the entire allocated object, including any padding at
1215 memset (result
, 0xaf, object_size
);
1217 /* Make the bytes after the end of the object unaccessible. Discard the
1218 handle to avoid handle leak. */
1219 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) result
+ size
,
1220 object_size
- size
));
1223 /* Tell Valgrind that the memory is there, but its content isn't
1224 defined. The bytes at the end of the object are still marked
1226 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result
, size
));
1228 /* Keep track of how many bytes are being allocated. This
1229 information is used in deciding when to collect. */
1230 G
.allocated
+= object_size
;
1232 /* For timevar statistics. */
1233 timevar_ggc_mem_total
+= object_size
;
1235 #ifdef GATHER_STATISTICS
1237 size_t overhead
= object_size
- size
;
1239 G
.stats
.total_overhead
+= overhead
;
1240 G
.stats
.total_allocated
+= object_size
;
1241 G
.stats
.total_overhead_per_order
[order
] += overhead
;
1242 G
.stats
.total_allocated_per_order
[order
] += object_size
;
1246 G
.stats
.total_overhead_under32
+= overhead
;
1247 G
.stats
.total_allocated_under32
+= object_size
;
1251 G
.stats
.total_overhead_under64
+= overhead
;
1252 G
.stats
.total_allocated_under64
+= object_size
;
1256 G
.stats
.total_overhead_under128
+= overhead
;
1257 G
.stats
.total_allocated_under128
+= object_size
;
1262 if (GGC_DEBUG_LEVEL
>= 3)
1263 fprintf (G
.debug_file
,
1264 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1265 (unsigned long) size
, (unsigned long) object_size
, result
,
1271 /* If P is not marked, marks it and return false. Otherwise return true.
1272 P must have been allocated by the GC allocator; it mustn't point to
1273 static objects, stack variables, or memory allocated with malloc. */
1276 ggc_set_mark (const void *p
)
1282 /* Look up the page on which the object is alloced. If the object
1283 wasn't allocated by the collector, we'll probably die. */
1284 entry
= lookup_page_table_entry (p
);
1287 /* Calculate the index of the object on the page; this is its bit
1288 position in the in_use_p bitmap. */
1289 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1290 word
= bit
/ HOST_BITS_PER_LONG
;
1291 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1293 /* If the bit was previously set, skip it. */
1294 if (entry
->in_use_p
[word
] & mask
)
1297 /* Otherwise set it, and decrement the free object count. */
1298 entry
->in_use_p
[word
] |= mask
;
1299 entry
->num_free_objects
-= 1;
1301 if (GGC_DEBUG_LEVEL
>= 4)
1302 fprintf (G
.debug_file
, "Marking %p\n", p
);
1307 /* Return 1 if P has been marked, zero otherwise.
1308 P must have been allocated by the GC allocator; it mustn't point to
1309 static objects, stack variables, or memory allocated with malloc. */
1312 ggc_marked_p (const void *p
)
1318 /* Look up the page on which the object is alloced. If the object
1319 wasn't allocated by the collector, we'll probably die. */
1320 entry
= lookup_page_table_entry (p
);
1323 /* Calculate the index of the object on the page; this is its bit
1324 position in the in_use_p bitmap. */
1325 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1326 word
= bit
/ HOST_BITS_PER_LONG
;
1327 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1329 return (entry
->in_use_p
[word
] & mask
) != 0;
1332 /* Return the size of the gc-able object P. */
1335 ggc_get_size (const void *p
)
1337 page_entry
*pe
= lookup_page_table_entry (p
);
1338 return OBJECT_SIZE (pe
->order
);
1341 /* Release the memory for object P. */
1346 page_entry
*pe
= lookup_page_table_entry (p
);
1347 size_t order
= pe
->order
;
1348 size_t size
= OBJECT_SIZE (order
);
1350 #ifdef GATHER_STATISTICS
1351 ggc_free_overhead (p
);
1354 if (GGC_DEBUG_LEVEL
>= 3)
1355 fprintf (G
.debug_file
,
1356 "Freeing object, actual size=%lu, at %p on %p\n",
1357 (unsigned long) size
, p
, (void *) pe
);
1359 #ifdef ENABLE_GC_CHECKING
1360 /* Poison the data, to indicate the data is garbage. */
1361 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (p
, size
));
1362 memset (p
, 0xa5, size
);
1364 /* Let valgrind know the object is free. */
1365 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (p
, size
));
1367 #ifdef ENABLE_GC_ALWAYS_COLLECT
1368 /* In the completely-anal-checking mode, we do *not* immediately free
1369 the data, but instead verify that the data is *actually* not
1370 reachable the next time we collect. */
1372 struct free_object
*fo
= XNEW (struct free_object
);
1374 fo
->next
= G
.free_object_list
;
1375 G
.free_object_list
= fo
;
1379 unsigned int bit_offset
, word
, bit
;
1381 G
.allocated
-= size
;
1383 /* Mark the object not-in-use. */
1384 bit_offset
= OFFSET_TO_BIT (((const char *) p
) - pe
->page
, order
);
1385 word
= bit_offset
/ HOST_BITS_PER_LONG
;
1386 bit
= bit_offset
% HOST_BITS_PER_LONG
;
1387 pe
->in_use_p
[word
] &= ~(1UL << bit
);
1389 if (pe
->num_free_objects
++ == 0)
1393 /* If the page is completely full, then it's supposed to
1394 be after all pages that aren't. Since we've freed one
1395 object from a page that was full, we need to move the
1396 page to the head of the list.
1398 PE is the node we want to move. Q is the previous node
1399 and P is the next node in the list. */
1401 if (q
&& q
->num_free_objects
== 0)
1407 /* If PE was at the end of the list, then Q becomes the
1408 new end of the list. If PE was not the end of the
1409 list, then we need to update the PREV field for P. */
1411 G
.page_tails
[order
] = q
;
1415 /* Move PE to the head of the list. */
1416 pe
->next
= G
.pages
[order
];
1418 G
.pages
[order
]->prev
= pe
;
1419 G
.pages
[order
] = pe
;
1422 /* Reset the hint bit to point to the only free object. */
1423 pe
->next_bit_hint
= bit_offset
;
1429 /* Subroutine of init_ggc which computes the pair of numbers used to
1430 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1432 This algorithm is taken from Granlund and Montgomery's paper
1433 "Division by Invariant Integers using Multiplication"
1434 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1438 compute_inverse (unsigned order
)
1443 size
= OBJECT_SIZE (order
);
1445 while (size
% 2 == 0)
1452 while (inv
* size
!= 1)
1453 inv
= inv
* (2 - inv
*size
);
1455 DIV_MULT (order
) = inv
;
1456 DIV_SHIFT (order
) = e
;
1459 /* Initialize the ggc-mmap allocator. */
1465 G
.pagesize
= getpagesize();
1466 G
.lg_pagesize
= exact_log2 (G
.pagesize
);
1468 #ifdef HAVE_MMAP_DEV_ZERO
1469 G
.dev_zero_fd
= open ("/dev/zero", O_RDONLY
);
1470 if (G
.dev_zero_fd
== -1)
1471 internal_error ("open /dev/zero: %m");
1475 G
.debug_file
= fopen ("ggc-mmap.debug", "w");
1477 G
.debug_file
= stdout
;
1481 /* StunOS has an amazing off-by-one error for the first mmap allocation
1482 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1483 believe, is an unaligned page allocation, which would cause us to
1484 hork badly if we tried to use it. */
1486 char *p
= alloc_anon (NULL
, G
.pagesize
);
1487 struct page_entry
*e
;
1488 if ((size_t)p
& (G
.pagesize
- 1))
1490 /* How losing. Discard this one and try another. If we still
1491 can't get something useful, give up. */
1493 p
= alloc_anon (NULL
, G
.pagesize
);
1494 gcc_assert (!((size_t)p
& (G
.pagesize
- 1)));
1497 /* We have a good page, might as well hold onto it... */
1498 e
= XCNEW (struct page_entry
);
1499 e
->bytes
= G
.pagesize
;
1501 e
->next
= G
.free_pages
;
1506 /* Initialize the object size table. */
1507 for (order
= 0; order
< HOST_BITS_PER_PTR
; ++order
)
1508 object_size_table
[order
] = (size_t) 1 << order
;
1509 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1511 size_t s
= extra_order_size_table
[order
- HOST_BITS_PER_PTR
];
1513 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1514 so that we're sure of getting aligned memory. */
1515 s
= ROUND_UP (s
, MAX_ALIGNMENT
);
1516 object_size_table
[order
] = s
;
1519 /* Initialize the objects-per-page and inverse tables. */
1520 for (order
= 0; order
< NUM_ORDERS
; ++order
)
1522 objects_per_page_table
[order
] = G
.pagesize
/ OBJECT_SIZE (order
);
1523 if (objects_per_page_table
[order
] == 0)
1524 objects_per_page_table
[order
] = 1;
1525 compute_inverse (order
);
1528 /* Reset the size_lookup array to put appropriately sized objects in
1529 the special orders. All objects bigger than the previous power
1530 of two, but no greater than the special size, should go in the
1532 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1537 o
= size_lookup
[OBJECT_SIZE (order
)];
1538 for (i
= OBJECT_SIZE (order
); size_lookup
[i
] == o
; --i
)
1539 size_lookup
[i
] = order
;
1544 G
.depth
= XNEWVEC (unsigned int, G
.depth_max
);
1546 G
.by_depth_in_use
= 0;
1547 G
.by_depth_max
= INITIAL_PTE_COUNT
;
1548 G
.by_depth
= XNEWVEC (page_entry
*, G
.by_depth_max
);
1549 G
.save_in_use
= XNEWVEC (unsigned long *, G
.by_depth_max
);
1552 /* Start a new GGC zone. */
1555 new_ggc_zone (const char *name ATTRIBUTE_UNUSED
)
1560 /* Destroy a GGC zone. */
1562 destroy_ggc_zone (struct alloc_zone
*zone ATTRIBUTE_UNUSED
)
1566 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1567 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1570 ggc_recalculate_in_use_p (page_entry
*p
)
1575 /* Because the past-the-end bit in in_use_p is always set, we
1576 pretend there is one additional object. */
1577 num_objects
= OBJECTS_IN_PAGE (p
) + 1;
1579 /* Reset the free object count. */
1580 p
->num_free_objects
= num_objects
;
1582 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1584 i
< CEIL (BITMAP_SIZE (num_objects
),
1585 sizeof (*p
->in_use_p
));
1590 /* Something is in use if it is marked, or if it was in use in a
1591 context further down the context stack. */
1592 p
->in_use_p
[i
] |= save_in_use_p (p
)[i
];
1594 /* Decrement the free object count for every object allocated. */
1595 for (j
= p
->in_use_p
[i
]; j
; j
>>= 1)
1596 p
->num_free_objects
-= (j
& 1);
1599 gcc_assert (p
->num_free_objects
< num_objects
);
1602 /* Unmark all objects. */
1609 for (order
= 2; order
< NUM_ORDERS
; order
++)
1613 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1615 size_t num_objects
= OBJECTS_IN_PAGE (p
);
1616 size_t bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
1618 /* The data should be page-aligned. */
1619 gcc_assert (!((size_t) p
->page
& (G
.pagesize
- 1)));
1621 /* Pages that aren't in the topmost context are not collected;
1622 nevertheless, we need their in-use bit vectors to store GC
1623 marks. So, back them up first. */
1624 if (p
->context_depth
< G
.context_depth
)
1626 if (! save_in_use_p (p
))
1627 save_in_use_p (p
) = xmalloc (bitmap_size
);
1628 memcpy (save_in_use_p (p
), p
->in_use_p
, bitmap_size
);
1631 /* Reset reset the number of free objects and clear the
1632 in-use bits. These will be adjusted by mark_obj. */
1633 p
->num_free_objects
= num_objects
;
1634 memset (p
->in_use_p
, 0, bitmap_size
);
1636 /* Make sure the one-past-the-end bit is always set. */
1637 p
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
1638 = ((unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
));
1643 /* Free all empty pages. Partially empty pages need no attention
1644 because the `mark' bit doubles as an `unused' bit. */
1651 for (order
= 2; order
< NUM_ORDERS
; order
++)
1653 /* The last page-entry to consider, regardless of entries
1654 placed at the end of the list. */
1655 page_entry
* const last
= G
.page_tails
[order
];
1658 size_t live_objects
;
1659 page_entry
*p
, *previous
;
1669 page_entry
*next
= p
->next
;
1671 /* Loop until all entries have been examined. */
1674 num_objects
= OBJECTS_IN_PAGE (p
);
1676 /* Add all live objects on this page to the count of
1677 allocated memory. */
1678 live_objects
= num_objects
- p
->num_free_objects
;
1680 G
.allocated
+= OBJECT_SIZE (order
) * live_objects
;
1682 /* Only objects on pages in the topmost context should get
1684 if (p
->context_depth
< G
.context_depth
)
1687 /* Remove the page if it's empty. */
1688 else if (live_objects
== 0)
1690 /* If P was the first page in the list, then NEXT
1691 becomes the new first page in the list, otherwise
1692 splice P out of the forward pointers. */
1694 G
.pages
[order
] = next
;
1696 previous
->next
= next
;
1698 /* Splice P out of the back pointers too. */
1700 next
->prev
= previous
;
1702 /* Are we removing the last element? */
1703 if (p
== G
.page_tails
[order
])
1704 G
.page_tails
[order
] = previous
;
1709 /* If the page is full, move it to the end. */
1710 else if (p
->num_free_objects
== 0)
1712 /* Don't move it if it's already at the end. */
1713 if (p
!= G
.page_tails
[order
])
1715 /* Move p to the end of the list. */
1717 p
->prev
= G
.page_tails
[order
];
1718 G
.page_tails
[order
]->next
= p
;
1720 /* Update the tail pointer... */
1721 G
.page_tails
[order
] = p
;
1723 /* ... and the head pointer, if necessary. */
1725 G
.pages
[order
] = next
;
1727 previous
->next
= next
;
1729 /* And update the backpointer in NEXT if necessary. */
1731 next
->prev
= previous
;
1737 /* If we've fallen through to here, it's a page in the
1738 topmost context that is neither full nor empty. Such a
1739 page must precede pages at lesser context depth in the
1740 list, so move it to the head. */
1741 else if (p
!= G
.pages
[order
])
1743 previous
->next
= p
->next
;
1745 /* Update the backchain in the next node if it exists. */
1747 p
->next
->prev
= previous
;
1749 /* Move P to the head of the list. */
1750 p
->next
= G
.pages
[order
];
1752 G
.pages
[order
]->prev
= p
;
1754 /* Update the head pointer. */
1757 /* Are we moving the last element? */
1758 if (G
.page_tails
[order
] == p
)
1759 G
.page_tails
[order
] = previous
;
1768 /* Now, restore the in_use_p vectors for any pages from contexts
1769 other than the current one. */
1770 for (p
= G
.pages
[order
]; p
; p
= p
->next
)
1771 if (p
->context_depth
!= G
.context_depth
)
1772 ggc_recalculate_in_use_p (p
);
1776 #ifdef ENABLE_GC_CHECKING
1777 /* Clobber all free objects. */
1784 for (order
= 2; order
< NUM_ORDERS
; order
++)
1786 size_t size
= OBJECT_SIZE (order
);
1789 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1794 if (p
->context_depth
!= G
.context_depth
)
1795 /* Since we don't do any collection for pages in pushed
1796 contexts, there's no need to do any poisoning. And
1797 besides, the IN_USE_P array isn't valid until we pop
1801 num_objects
= OBJECTS_IN_PAGE (p
);
1802 for (i
= 0; i
< num_objects
; i
++)
1805 word
= i
/ HOST_BITS_PER_LONG
;
1806 bit
= i
% HOST_BITS_PER_LONG
;
1807 if (((p
->in_use_p
[word
] >> bit
) & 1) == 0)
1809 char *object
= p
->page
+ i
* size
;
1811 /* Keep poison-by-write when we expect to use Valgrind,
1812 so the exact same memory semantics is kept, in case
1813 there are memory errors. We override this request
1815 VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (object
, size
));
1816 memset (object
, 0xa5, size
);
1818 /* Drop the handle to avoid handle leak. */
1819 VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (object
, size
));
1826 #define poison_pages()
1829 #ifdef ENABLE_GC_ALWAYS_COLLECT
1830 /* Validate that the reportedly free objects actually are. */
1833 validate_free_objects (void)
1835 struct free_object
*f
, *next
, *still_free
= NULL
;
1837 for (f
= G
.free_object_list
; f
; f
= next
)
1839 page_entry
*pe
= lookup_page_table_entry (f
->object
);
1842 bit
= OFFSET_TO_BIT ((char *)f
->object
- pe
->page
, pe
->order
);
1843 word
= bit
/ HOST_BITS_PER_LONG
;
1844 bit
= bit
% HOST_BITS_PER_LONG
;
1847 /* Make certain it isn't visible from any root. Notice that we
1848 do this check before sweep_pages merges save_in_use_p. */
1849 gcc_assert (!(pe
->in_use_p
[word
] & (1UL << bit
)));
1851 /* If the object comes from an outer context, then retain the
1852 free_object entry, so that we can verify that the address
1853 isn't live on the stack in some outer context. */
1854 if (pe
->context_depth
!= G
.context_depth
)
1856 f
->next
= still_free
;
1863 G
.free_object_list
= still_free
;
1866 #define validate_free_objects()
1869 /* Top level mark-and-sweep routine. */
1874 /* Avoid frequent unnecessary work by skipping collection if the
1875 total allocations haven't expanded much since the last
1877 float allocated_last_gc
=
1878 MAX (G
.allocated_last_gc
, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE
) * 1024);
1880 float min_expand
= allocated_last_gc
* PARAM_VALUE (GGC_MIN_EXPAND
) / 100;
1882 if (G
.allocated
< allocated_last_gc
+ min_expand
&& !ggc_force_collect
)
1885 timevar_push (TV_GC
);
1887 fprintf (stderr
, " {GC %luk -> ", (unsigned long) G
.allocated
/ 1024);
1888 if (GGC_DEBUG_LEVEL
>= 2)
1889 fprintf (G
.debug_file
, "BEGIN COLLECTING\n");
1891 /* Zero the total allocated bytes. This will be recalculated in the
1895 /* Release the pages we freed the last time we collected, but didn't
1896 reuse in the interim. */
1899 /* Indicate that we've seen collections at this context depth. */
1900 G
.context_depth_collections
= ((unsigned long)1 << (G
.context_depth
+ 1)) - 1;
1904 #ifdef GATHER_STATISTICS
1905 ggc_prune_overhead_list ();
1908 validate_free_objects ();
1911 G
.allocated_last_gc
= G
.allocated
;
1913 timevar_pop (TV_GC
);
1916 fprintf (stderr
, "%luk}", (unsigned long) G
.allocated
/ 1024);
1917 if (GGC_DEBUG_LEVEL
>= 2)
1918 fprintf (G
.debug_file
, "END COLLECTING\n");
1921 /* Print allocation statistics. */
1922 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
1924 : ((x) < 1024*1024*10 \
1926 : (x) / (1024*1024))))
1927 #define STAT_LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
1930 ggc_print_statistics (void)
1932 struct ggc_statistics stats
;
1934 size_t total_overhead
= 0;
1936 /* Clear the statistics. */
1937 memset (&stats
, 0, sizeof (stats
));
1939 /* Make sure collection will really occur. */
1940 G
.allocated_last_gc
= 0;
1942 /* Collect and print the statistics common across collectors. */
1943 ggc_print_common_statistics (stderr
, &stats
);
1945 /* Release free pages so that we will not count the bytes allocated
1946 there as part of the total allocated memory. */
1949 /* Collect some information about the various sizes of
1952 "Memory still allocated at the end of the compilation process\n");
1953 fprintf (stderr
, "%-5s %10s %10s %10s\n",
1954 "Size", "Allocated", "Used", "Overhead");
1955 for (i
= 0; i
< NUM_ORDERS
; ++i
)
1962 /* Skip empty entries. */
1966 overhead
= allocated
= in_use
= 0;
1968 /* Figure out the total number of bytes allocated for objects of
1969 this size, and how many of them are actually in use. Also figure
1970 out how much memory the page table is using. */
1971 for (p
= G
.pages
[i
]; p
; p
= p
->next
)
1973 allocated
+= p
->bytes
;
1975 (OBJECTS_IN_PAGE (p
) - p
->num_free_objects
) * OBJECT_SIZE (i
);
1977 overhead
+= (sizeof (page_entry
) - sizeof (long)
1978 + BITMAP_SIZE (OBJECTS_IN_PAGE (p
) + 1));
1980 fprintf (stderr
, "%-5lu %10lu%c %10lu%c %10lu%c\n",
1981 (unsigned long) OBJECT_SIZE (i
),
1982 SCALE (allocated
), STAT_LABEL (allocated
),
1983 SCALE (in_use
), STAT_LABEL (in_use
),
1984 SCALE (overhead
), STAT_LABEL (overhead
));
1985 total_overhead
+= overhead
;
1987 fprintf (stderr
, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
1988 SCALE (G
.bytes_mapped
), STAT_LABEL (G
.bytes_mapped
),
1989 SCALE (G
.allocated
), STAT_LABEL(G
.allocated
),
1990 SCALE (total_overhead
), STAT_LABEL (total_overhead
));
1992 #ifdef GATHER_STATISTICS
1994 fprintf (stderr
, "\nTotal allocations and overheads during the compilation process\n");
1996 fprintf (stderr
, "Total Overhead: %10lld\n",
1997 G
.stats
.total_overhead
);
1998 fprintf (stderr
, "Total Allocated: %10lld\n",
1999 G
.stats
.total_allocated
);
2001 fprintf (stderr
, "Total Overhead under 32B: %10lld\n",
2002 G
.stats
.total_overhead_under32
);
2003 fprintf (stderr
, "Total Allocated under 32B: %10lld\n",
2004 G
.stats
.total_allocated_under32
);
2005 fprintf (stderr
, "Total Overhead under 64B: %10lld\n",
2006 G
.stats
.total_overhead_under64
);
2007 fprintf (stderr
, "Total Allocated under 64B: %10lld\n",
2008 G
.stats
.total_allocated_under64
);
2009 fprintf (stderr
, "Total Overhead under 128B: %10lld\n",
2010 G
.stats
.total_overhead_under128
);
2011 fprintf (stderr
, "Total Allocated under 128B: %10lld\n",
2012 G
.stats
.total_allocated_under128
);
2014 for (i
= 0; i
< NUM_ORDERS
; i
++)
2015 if (G
.stats
.total_allocated_per_order
[i
])
2017 fprintf (stderr
, "Total Overhead page size %7d: %10lld\n",
2018 OBJECT_SIZE (i
), G
.stats
.total_overhead_per_order
[i
]);
2019 fprintf (stderr
, "Total Allocated page size %7d: %10lld\n",
2020 OBJECT_SIZE (i
), G
.stats
.total_allocated_per_order
[i
]);
2028 struct ggc_pch_ondisk
2030 unsigned totals
[NUM_ORDERS
];
2032 size_t base
[NUM_ORDERS
];
2033 size_t written
[NUM_ORDERS
];
2036 struct ggc_pch_data
*
2039 return XCNEW (struct ggc_pch_data
);
2043 ggc_pch_count_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2044 size_t size
, bool is_string ATTRIBUTE_UNUSED
,
2045 enum gt_types_enum type ATTRIBUTE_UNUSED
)
2050 order
= size_lookup
[size
];
2054 while (size
> OBJECT_SIZE (order
))
2058 d
->d
.totals
[order
]++;
2062 ggc_pch_total_size (struct ggc_pch_data
*d
)
2067 for (i
= 0; i
< NUM_ORDERS
; i
++)
2068 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2073 ggc_pch_this_base (struct ggc_pch_data
*d
, void *base
)
2075 size_t a
= (size_t) base
;
2078 for (i
= 0; i
< NUM_ORDERS
; i
++)
2081 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2087 ggc_pch_alloc_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2088 size_t size
, bool is_string ATTRIBUTE_UNUSED
,
2089 enum gt_types_enum type ATTRIBUTE_UNUSED
)
2095 order
= size_lookup
[size
];
2099 while (size
> OBJECT_SIZE (order
))
2103 result
= (char *) d
->base
[order
];
2104 d
->base
[order
] += OBJECT_SIZE (order
);
2109 ggc_pch_prepare_write (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2110 FILE *f ATTRIBUTE_UNUSED
)
2112 /* Nothing to do. */
2116 ggc_pch_write_object (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2117 FILE *f
, void *x
, void *newx ATTRIBUTE_UNUSED
,
2118 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
2121 static const char emptyBytes
[256];
2124 order
= size_lookup
[size
];
2128 while (size
> OBJECT_SIZE (order
))
2132 if (fwrite (x
, size
, 1, f
) != 1)
2133 fatal_error ("can't write PCH file: %m");
2135 /* If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
2136 object out to OBJECT_SIZE(order). This happens for strings. */
2138 if (size
!= OBJECT_SIZE (order
))
2140 unsigned padding
= OBJECT_SIZE(order
) - size
;
2142 /* To speed small writes, we use a nulled-out array that's larger
2143 than most padding requests as the source for our null bytes. This
2144 permits us to do the padding with fwrite() rather than fseek(), and
2145 limits the chance the OS may try to flush any outstanding writes. */
2146 if (padding
<= sizeof(emptyBytes
))
2148 if (fwrite (emptyBytes
, 1, padding
, f
) != padding
)
2149 fatal_error ("can't write PCH file");
2153 /* Larger than our buffer? Just default to fseek. */
2154 if (fseek (f
, padding
, SEEK_CUR
) != 0)
2155 fatal_error ("can't write PCH file");
2159 d
->written
[order
]++;
2160 if (d
->written
[order
] == d
->d
.totals
[order
]
2161 && fseek (f
, ROUND_UP_VALUE (d
->d
.totals
[order
] * OBJECT_SIZE (order
),
2164 fatal_error ("can't write PCH file: %m");
2168 ggc_pch_finish (struct ggc_pch_data
*d
, FILE *f
)
2170 if (fwrite (&d
->d
, sizeof (d
->d
), 1, f
) != 1)
2171 fatal_error ("can't write PCH file: %m");
2175 /* Move the PCH PTE entries just added to the end of by_depth, to the
2179 move_ptes_to_front (int count_old_page_tables
, int count_new_page_tables
)
2183 /* First, we swap the new entries to the front of the varrays. */
2184 page_entry
**new_by_depth
;
2185 unsigned long **new_save_in_use
;
2187 new_by_depth
= XNEWVEC (page_entry
*, G
.by_depth_max
);
2188 new_save_in_use
= XNEWVEC (unsigned long *, G
.by_depth_max
);
2190 memcpy (&new_by_depth
[0],
2191 &G
.by_depth
[count_old_page_tables
],
2192 count_new_page_tables
* sizeof (void *));
2193 memcpy (&new_by_depth
[count_new_page_tables
],
2195 count_old_page_tables
* sizeof (void *));
2196 memcpy (&new_save_in_use
[0],
2197 &G
.save_in_use
[count_old_page_tables
],
2198 count_new_page_tables
* sizeof (void *));
2199 memcpy (&new_save_in_use
[count_new_page_tables
],
2201 count_old_page_tables
* sizeof (void *));
2204 free (G
.save_in_use
);
2206 G
.by_depth
= new_by_depth
;
2207 G
.save_in_use
= new_save_in_use
;
2209 /* Now update all the index_by_depth fields. */
2210 for (i
= G
.by_depth_in_use
; i
> 0; --i
)
2212 page_entry
*p
= G
.by_depth
[i
-1];
2213 p
->index_by_depth
= i
-1;
2216 /* And last, we update the depth pointers in G.depth. The first
2217 entry is already 0, and context 0 entries always start at index
2218 0, so there is nothing to update in the first slot. We need a
2219 second slot, only if we have old ptes, and if we do, they start
2220 at index count_new_page_tables. */
2221 if (count_old_page_tables
)
2222 push_depth (count_new_page_tables
);
2226 ggc_pch_read (FILE *f
, void *addr
)
2228 struct ggc_pch_ondisk d
;
2231 unsigned long count_old_page_tables
;
2232 unsigned long count_new_page_tables
;
2234 count_old_page_tables
= G
.by_depth_in_use
;
2236 /* We've just read in a PCH file. So, every object that used to be
2237 allocated is now free. */
2239 #ifdef ENABLE_GC_CHECKING
2243 /* No object read from a PCH file should ever be freed. So, set the
2244 context depth to 1, and set the depth of all the currently-allocated
2245 pages to be 1 too. PCH pages will have depth 0. */
2246 gcc_assert (!G
.context_depth
);
2247 G
.context_depth
= 1;
2248 for (i
= 0; i
< NUM_ORDERS
; i
++)
2251 for (p
= G
.pages
[i
]; p
!= NULL
; p
= p
->next
)
2252 p
->context_depth
= G
.context_depth
;
2255 /* Allocate the appropriate page-table entries for the pages read from
2257 if (fread (&d
, sizeof (d
), 1, f
) != 1)
2258 fatal_error ("can't read PCH file: %m");
2260 for (i
= 0; i
< NUM_ORDERS
; i
++)
2262 struct page_entry
*entry
;
2268 if (d
.totals
[i
] == 0)
2271 bytes
= ROUND_UP (d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2272 num_objs
= bytes
/ OBJECT_SIZE (i
);
2273 entry
= xcalloc (1, (sizeof (struct page_entry
)
2275 + BITMAP_SIZE (num_objs
+ 1)));
2276 entry
->bytes
= bytes
;
2278 entry
->context_depth
= 0;
2280 entry
->num_free_objects
= 0;
2284 j
+ HOST_BITS_PER_LONG
<= num_objs
+ 1;
2285 j
+= HOST_BITS_PER_LONG
)
2286 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
] = -1;
2287 for (; j
< num_objs
+ 1; j
++)
2288 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
]
2289 |= 1L << (j
% HOST_BITS_PER_LONG
);
2291 for (pte
= entry
->page
;
2292 pte
< entry
->page
+ entry
->bytes
;
2294 set_page_table_entry (pte
, entry
);
2296 if (G
.page_tails
[i
] != NULL
)
2297 G
.page_tails
[i
]->next
= entry
;
2300 G
.page_tails
[i
] = entry
;
2302 /* We start off by just adding all the new information to the
2303 end of the varrays, later, we will move the new information
2304 to the front of the varrays, as the PCH page tables are at
2306 push_by_depth (entry
, 0);
2309 /* Now, we update the various data structures that speed page table
2311 count_new_page_tables
= G
.by_depth_in_use
- count_old_page_tables
;
2313 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
);
2315 /* Update the statistics. */
2316 G
.allocated
= G
.allocated_last_gc
= offs
- (char *)addr
;