1 /* "Bag-of-pages" garbage collector for the GNU compiler.
2 Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009,
3 2010 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"
31 #include "ggc-internal.h"
34 #include "tree-flow.h"
38 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
39 file open. Prefer either to valloc. */
41 # undef HAVE_MMAP_DEV_ZERO
43 # include <sys/mman.h>
45 # define MAP_FAILED -1
47 # if !defined (MAP_ANONYMOUS) && defined (MAP_ANON)
48 # define MAP_ANONYMOUS MAP_ANON
54 #ifdef HAVE_MMAP_DEV_ZERO
56 # include <sys/mman.h>
58 # define MAP_FAILED -1
65 #define USING_MALLOC_PAGE_GROUPS
70 This garbage-collecting allocator allocates objects on one of a set
71 of pages. Each page can allocate objects of a single size only;
72 available sizes are powers of two starting at four bytes. The size
73 of an allocation request is rounded up to the next power of two
74 (`order'), and satisfied from the appropriate page.
76 Each page is recorded in a page-entry, which also maintains an
77 in-use bitmap of object positions on the page. This allows the
78 allocation state of a particular object to be flipped without
79 touching the page itself.
81 Each page-entry also has a context depth, which is used to track
82 pushing and popping of allocation contexts. Only objects allocated
83 in the current (highest-numbered) context may be collected.
85 Page entries are arranged in an array of singly-linked lists. The
86 array is indexed by the allocation size, in bits, of the pages on
87 it; i.e. all pages on a list allocate objects of the same size.
88 Pages are ordered on the list such that all non-full pages precede
89 all full pages, with non-full pages arranged in order of decreasing
92 Empty pages (of all orders) are kept on a single page cache list,
93 and are considered first when new pages are required; they are
94 deallocated at the start of the next collection if they haven't
95 been recycled by then. */
97 /* Define GGC_DEBUG_LEVEL to print debugging information.
98 0: No debugging output.
99 1: GC statistics only.
100 2: Page-entry allocations/deallocations as well.
101 3: Object allocations as well.
102 4: Object marks as well. */
103 #define GGC_DEBUG_LEVEL (0)
105 #ifndef HOST_BITS_PER_PTR
106 #define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
110 /* A two-level tree is used to look up the page-entry for a given
111 pointer. Two chunks of the pointer's bits are extracted to index
112 the first and second levels of the tree, as follows:
116 msb +----------------+----+------+------+ lsb
122 The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
123 pages are aligned on system page boundaries. The next most
124 significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
125 index values in the lookup table, respectively.
127 For 32-bit architectures and the settings below, there are no
128 leftover bits. For architectures with wider pointers, the lookup
129 tree points to a list of pages, which must be scanned to find the
132 #define PAGE_L1_BITS (8)
133 #define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
134 #define PAGE_L1_SIZE ((size_t) 1 << PAGE_L1_BITS)
135 #define PAGE_L2_SIZE ((size_t) 1 << PAGE_L2_BITS)
137 #define LOOKUP_L1(p) \
138 (((size_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
140 #define LOOKUP_L2(p) \
141 (((size_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
143 /* The number of objects per allocation page, for objects on a page of
144 the indicated ORDER. */
145 #define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
147 /* The number of objects in P. */
148 #define OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
150 /* The size of an object on a page of the indicated ORDER. */
151 #define OBJECT_SIZE(ORDER) object_size_table[ORDER]
153 /* For speed, we avoid doing a general integer divide to locate the
154 offset in the allocation bitmap, by precalculating numbers M, S
155 such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
156 within the page which is evenly divisible by the object size Z. */
157 #define DIV_MULT(ORDER) inverse_table[ORDER].mult
158 #define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
159 #define OFFSET_TO_BIT(OFFSET, ORDER) \
160 (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
162 /* We use this structure to determine the alignment required for
163 allocations. For power-of-two sized allocations, that's not a
164 problem, but it does matter for odd-sized allocations.
165 We do not care about alignment for floating-point types. */
167 struct max_alignment
{
175 /* The biggest alignment required. */
177 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
180 /* The number of extra orders, not corresponding to power-of-two sized
183 #define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
185 #define RTL_SIZE(NSLOTS) \
186 (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))
188 #define TREE_EXP_SIZE(OPS) \
189 (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
191 /* The Ith entry is the maximum size of an object to be stored in the
192 Ith extra order. Adding a new entry to this array is the *only*
193 thing you need to do to add a new special allocation size. */
195 static const size_t extra_order_size_table
[] = {
196 /* Extra orders for small non-power-of-two multiples of MAX_ALIGNMENT.
197 There are a lot of structures with these sizes and explicitly
198 listing them risks orders being dropped because they changed size. */
210 sizeof (struct tree_decl_non_common
),
211 sizeof (struct tree_field_decl
),
212 sizeof (struct tree_parm_decl
),
213 sizeof (struct tree_var_decl
),
214 sizeof (struct tree_type
),
215 sizeof (struct function
),
216 sizeof (struct basic_block_def
),
217 sizeof (struct cgraph_node
),
218 sizeof (struct loop
),
221 /* The total number of orders. */
223 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
225 /* Compute the smallest nonnegative number which when added to X gives
228 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
230 /* Compute the smallest multiple of F that is >= X. */
232 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
234 /* The Ith entry is the number of objects on a page or order I. */
236 static unsigned objects_per_page_table
[NUM_ORDERS
];
238 /* The Ith entry is the size of an object on a page of order I. */
240 static size_t object_size_table
[NUM_ORDERS
];
242 /* The Ith entry is a pair of numbers (mult, shift) such that
243 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
244 for all k evenly divisible by OBJECT_SIZE(I). */
251 inverse_table
[NUM_ORDERS
];
253 /* A page_entry records the status of an allocation page. This
254 structure is dynamically sized to fit the bitmap in_use_p. */
255 typedef struct page_entry
257 /* The next page-entry with objects of the same size, or NULL if
258 this is the last page-entry. */
259 struct page_entry
*next
;
261 /* The previous page-entry with objects of the same size, or NULL if
262 this is the first page-entry. The PREV pointer exists solely to
263 keep the cost of ggc_free manageable. */
264 struct page_entry
*prev
;
266 /* The number of bytes allocated. (This will always be a multiple
267 of the host system page size.) */
270 /* The address at which the memory is allocated. */
273 #ifdef USING_MALLOC_PAGE_GROUPS
274 /* Back pointer to the page group this page came from. */
275 struct page_group
*group
;
278 /* This is the index in the by_depth varray where this page table
280 unsigned long index_by_depth
;
282 /* Context depth of this page. */
283 unsigned short context_depth
;
285 /* The number of free objects remaining on this page. */
286 unsigned short num_free_objects
;
288 /* A likely candidate for the bit position of a free object for the
289 next allocation from this page. */
290 unsigned short next_bit_hint
;
292 /* The lg of size of objects allocated from this page. */
295 /* A bit vector indicating whether or not objects are in use. The
296 Nth bit is one if the Nth object on this page is allocated. This
297 array is dynamically sized. */
298 unsigned long in_use_p
[1];
301 #ifdef USING_MALLOC_PAGE_GROUPS
302 /* A page_group describes a large allocation from malloc, from which
303 we parcel out aligned pages. */
304 typedef struct page_group
306 /* A linked list of all extant page groups. */
307 struct page_group
*next
;
309 /* The address we received from malloc. */
312 /* The size of the block. */
315 /* A bitmask of pages in use. */
320 #if HOST_BITS_PER_PTR <= 32
322 /* On 32-bit hosts, we use a two level page table, as pictured above. */
323 typedef page_entry
**page_table
[PAGE_L1_SIZE
];
327 /* On 64-bit hosts, we use the same two level page tables plus a linked
328 list that disambiguates the top 32-bits. There will almost always be
329 exactly one entry in the list. */
330 typedef struct page_table_chain
332 struct page_table_chain
*next
;
334 page_entry
**table
[PAGE_L1_SIZE
];
339 #ifdef ENABLE_GC_ALWAYS_COLLECT
340 /* List of free objects to be verified as actually free on the
345 struct free_object
*next
;
349 /* The rest of the global variables. */
350 static struct globals
352 /* The Nth element in this array is a page with objects of size 2^N.
353 If there are any pages with free objects, they will be at the
354 head of the list. NULL if there are no page-entries for this
356 page_entry
*pages
[NUM_ORDERS
];
358 /* The Nth element in this array is the last page with objects of
359 size 2^N. NULL if there are no page-entries for this object
361 page_entry
*page_tails
[NUM_ORDERS
];
363 /* Lookup table for associating allocation pages with object addresses. */
366 /* The system's page size. */
370 /* Bytes currently allocated. */
373 /* Bytes currently allocated at the end of the last collection. */
374 size_t allocated_last_gc
;
376 /* Total amount of memory mapped. */
379 /* Bit N set if any allocations have been done at context depth N. */
380 unsigned long context_depth_allocations
;
382 /* Bit N set if any collections have been done at context depth N. */
383 unsigned long context_depth_collections
;
385 /* The current depth in the context stack. */
386 unsigned short context_depth
;
388 /* A file descriptor open to /dev/zero for reading. */
389 #if defined (HAVE_MMAP_DEV_ZERO)
393 /* A cache of free system pages. */
394 page_entry
*free_pages
;
396 #ifdef USING_MALLOC_PAGE_GROUPS
397 page_group
*page_groups
;
400 /* The file descriptor for debugging output. */
403 /* Current number of elements in use in depth below. */
404 unsigned int depth_in_use
;
406 /* Maximum number of elements that can be used before resizing. */
407 unsigned int depth_max
;
409 /* Each element of this array is an index in by_depth where the given
410 depth starts. This structure is indexed by that given depth we
411 are interested in. */
414 /* Current number of elements in use in by_depth below. */
415 unsigned int by_depth_in_use
;
417 /* Maximum number of elements that can be used before resizing. */
418 unsigned int by_depth_max
;
420 /* Each element of this array is a pointer to a page_entry, all
421 page_entries can be found in here by increasing depth.
422 index_by_depth in the page_entry is the index into this data
423 structure where that page_entry can be found. This is used to
424 speed up finding all page_entries at a particular depth. */
425 page_entry
**by_depth
;
427 /* Each element is a pointer to the saved in_use_p bits, if any,
428 zero otherwise. We allocate them all together, to enable a
429 better runtime data access pattern. */
430 unsigned long **save_in_use
;
432 #ifdef ENABLE_GC_ALWAYS_COLLECT
433 /* List of free objects to be verified as actually free on the
435 struct free_object
*free_object_list
;
438 #ifdef GATHER_STATISTICS
441 /* Total GC-allocated memory. */
442 unsigned long long total_allocated
;
443 /* Total overhead for GC-allocated memory. */
444 unsigned long long total_overhead
;
446 /* Total allocations and overhead for sizes less than 32, 64 and 128.
447 These sizes are interesting because they are typical cache line
450 unsigned long long total_allocated_under32
;
451 unsigned long long total_overhead_under32
;
453 unsigned long long total_allocated_under64
;
454 unsigned long long total_overhead_under64
;
456 unsigned long long total_allocated_under128
;
457 unsigned long long total_overhead_under128
;
459 /* The allocations for each of the allocation orders. */
460 unsigned long long total_allocated_per_order
[NUM_ORDERS
];
462 /* The overhead for each of the allocation orders. */
463 unsigned long long total_overhead_per_order
[NUM_ORDERS
];
468 /* The size in bytes required to maintain a bitmap for the objects
470 #define BITMAP_SIZE(Num_objects) \
471 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
473 /* Allocate pages in chunks of this size, to throttle calls to memory
474 allocation routines. The first page is used, the rest go onto the
475 free list. This cannot be larger than HOST_BITS_PER_INT for the
476 in_use bitmask for page_group. Hosts that need a different value
477 can override this by defining GGC_QUIRE_SIZE explicitly. */
478 #ifndef GGC_QUIRE_SIZE
480 # define GGC_QUIRE_SIZE 256
482 # define GGC_QUIRE_SIZE 16
486 /* Initial guess as to how many page table entries we might need. */
487 #define INITIAL_PTE_COUNT 128
489 static int ggc_allocated_p (const void *);
490 static page_entry
*lookup_page_table_entry (const void *);
491 static void set_page_table_entry (void *, page_entry
*);
493 static char *alloc_anon (char *, size_t);
495 #ifdef USING_MALLOC_PAGE_GROUPS
496 static size_t page_group_index (char *, char *);
497 static void set_page_group_in_use (page_group
*, char *);
498 static void clear_page_group_in_use (page_group
*, char *);
500 static struct page_entry
* alloc_page (unsigned);
501 static void free_page (struct page_entry
*);
502 static void release_pages (void);
503 static void clear_marks (void);
504 static void sweep_pages (void);
505 static void ggc_recalculate_in_use_p (page_entry
*);
506 static void compute_inverse (unsigned);
507 static inline void adjust_depth (void);
508 static void move_ptes_to_front (int, int);
510 void debug_print_page_list (int);
511 static void push_depth (unsigned int);
512 static void push_by_depth (page_entry
*, unsigned long *);
514 /* Push an entry onto G.depth. */
517 push_depth (unsigned int i
)
519 if (G
.depth_in_use
>= G
.depth_max
)
522 G
.depth
= XRESIZEVEC (unsigned int, G
.depth
, G
.depth_max
);
524 G
.depth
[G
.depth_in_use
++] = i
;
527 /* Push an entry onto G.by_depth and G.save_in_use. */
530 push_by_depth (page_entry
*p
, unsigned long *s
)
532 if (G
.by_depth_in_use
>= G
.by_depth_max
)
535 G
.by_depth
= XRESIZEVEC (page_entry
*, G
.by_depth
, G
.by_depth_max
);
536 G
.save_in_use
= XRESIZEVEC (unsigned long *, G
.save_in_use
,
539 G
.by_depth
[G
.by_depth_in_use
] = p
;
540 G
.save_in_use
[G
.by_depth_in_use
++] = s
;
543 #if (GCC_VERSION < 3001)
544 #define prefetch(X) ((void) X)
546 #define prefetch(X) __builtin_prefetch (X)
549 #define save_in_use_p_i(__i) \
551 #define save_in_use_p(__p) \
552 (save_in_use_p_i (__p->index_by_depth))
554 /* Returns nonzero if P was allocated in GC'able memory. */
557 ggc_allocated_p (const void *p
)
562 #if HOST_BITS_PER_PTR <= 32
565 page_table table
= G
.lookup
;
566 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
571 if (table
->high_bits
== high_bits
)
575 base
= &table
->table
[0];
578 /* Extract the level 1 and 2 indices. */
582 return base
[L1
] && base
[L1
][L2
];
585 /* Traverse the page table and find the entry for a page.
586 Die (probably) if the object wasn't allocated via GC. */
588 static inline page_entry
*
589 lookup_page_table_entry (const void *p
)
594 #if HOST_BITS_PER_PTR <= 32
597 page_table table
= G
.lookup
;
598 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
599 while (table
->high_bits
!= high_bits
)
601 base
= &table
->table
[0];
604 /* Extract the level 1 and 2 indices. */
611 /* Set the page table entry for a page. */
614 set_page_table_entry (void *p
, page_entry
*entry
)
619 #if HOST_BITS_PER_PTR <= 32
623 size_t high_bits
= (size_t) p
& ~ (size_t) 0xffffffff;
624 for (table
= G
.lookup
; table
; table
= table
->next
)
625 if (table
->high_bits
== high_bits
)
628 /* Not found -- allocate a new table. */
629 table
= XCNEW (struct page_table_chain
);
630 table
->next
= G
.lookup
;
631 table
->high_bits
= high_bits
;
634 base
= &table
->table
[0];
637 /* Extract the level 1 and 2 indices. */
641 if (base
[L1
] == NULL
)
642 base
[L1
] = XCNEWVEC (page_entry
*, PAGE_L2_SIZE
);
644 base
[L1
][L2
] = entry
;
647 /* Prints the page-entry for object size ORDER, for debugging. */
650 debug_print_page_list (int order
)
653 printf ("Head=%p, Tail=%p:\n", (void *) G
.pages
[order
],
654 (void *) G
.page_tails
[order
]);
658 printf ("%p(%1d|%3d) -> ", (void *) p
, p
->context_depth
,
659 p
->num_free_objects
);
667 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
668 (if non-null). The ifdef structure here is intended to cause a
669 compile error unless exactly one of the HAVE_* is defined. */
672 alloc_anon (char *pref ATTRIBUTE_UNUSED
, size_t size
)
674 #ifdef HAVE_MMAP_ANON
675 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
676 MAP_PRIVATE
| MAP_ANONYMOUS
, -1, 0);
678 #ifdef HAVE_MMAP_DEV_ZERO
679 char *page
= (char *) mmap (pref
, size
, PROT_READ
| PROT_WRITE
,
680 MAP_PRIVATE
, G
.dev_zero_fd
, 0);
683 if (page
== (char *) MAP_FAILED
)
685 perror ("virtual memory exhausted");
686 exit (FATAL_EXIT_CODE
);
689 /* Remember that we allocated this memory. */
690 G
.bytes_mapped
+= size
;
692 /* Pretend we don't have access to the allocated pages. We'll enable
693 access to smaller pieces of the area in ggc_internal_alloc. Discard the
694 handle to avoid handle leak. */
695 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (page
, size
));
700 #ifdef USING_MALLOC_PAGE_GROUPS
701 /* Compute the index for this page into the page group. */
704 page_group_index (char *allocation
, char *page
)
706 return (size_t) (page
- allocation
) >> G
.lg_pagesize
;
709 /* Set and clear the in_use bit for this page in the page group. */
712 set_page_group_in_use (page_group
*group
, char *page
)
714 group
->in_use
|= 1 << page_group_index (group
->allocation
, page
);
718 clear_page_group_in_use (page_group
*group
, char *page
)
720 group
->in_use
&= ~(1 << page_group_index (group
->allocation
, page
));
724 /* Allocate a new page for allocating objects of size 2^ORDER,
725 and return an entry for it. The entry is not added to the
726 appropriate page_table list. */
728 static inline struct page_entry
*
729 alloc_page (unsigned order
)
731 struct page_entry
*entry
, *p
, **pp
;
735 size_t page_entry_size
;
737 #ifdef USING_MALLOC_PAGE_GROUPS
741 num_objects
= OBJECTS_PER_PAGE (order
);
742 bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
743 page_entry_size
= sizeof (page_entry
) - sizeof (long) + bitmap_size
;
744 entry_size
= num_objects
* OBJECT_SIZE (order
);
745 if (entry_size
< G
.pagesize
)
746 entry_size
= G
.pagesize
;
751 /* Check the list of free pages for one we can use. */
752 for (pp
= &G
.free_pages
, p
= *pp
; p
; pp
= &p
->next
, p
= *pp
)
753 if (p
->bytes
== entry_size
)
758 /* Recycle the allocated memory from this page ... */
762 #ifdef USING_MALLOC_PAGE_GROUPS
766 /* ... and, if possible, the page entry itself. */
767 if (p
->order
== order
)
770 memset (entry
, 0, page_entry_size
);
776 else if (entry_size
== G
.pagesize
)
778 /* We want just one page. Allocate a bunch of them and put the
779 extras on the freelist. (Can only do this optimization with
780 mmap for backing store.) */
781 struct page_entry
*e
, *f
= G
.free_pages
;
784 page
= alloc_anon (NULL
, G
.pagesize
* GGC_QUIRE_SIZE
);
786 /* This loop counts down so that the chain will be in ascending
788 for (i
= GGC_QUIRE_SIZE
- 1; i
>= 1; i
--)
790 e
= XCNEWVAR (struct page_entry
, page_entry_size
);
792 e
->bytes
= G
.pagesize
;
793 e
->page
= page
+ (i
<< G
.lg_pagesize
);
801 page
= alloc_anon (NULL
, entry_size
);
803 #ifdef USING_MALLOC_PAGE_GROUPS
806 /* Allocate a large block of memory and serve out the aligned
807 pages therein. This results in much less memory wastage
808 than the traditional implementation of valloc. */
810 char *allocation
, *a
, *enda
;
811 size_t alloc_size
, head_slop
, tail_slop
;
812 int multiple_pages
= (entry_size
== G
.pagesize
);
815 alloc_size
= GGC_QUIRE_SIZE
* G
.pagesize
;
817 alloc_size
= entry_size
+ G
.pagesize
- 1;
818 allocation
= XNEWVEC (char, alloc_size
);
820 page
= (char *) (((size_t) allocation
+ G
.pagesize
- 1) & -G
.pagesize
);
821 head_slop
= page
- allocation
;
823 tail_slop
= ((size_t) allocation
+ alloc_size
) & (G
.pagesize
- 1);
825 tail_slop
= alloc_size
- entry_size
- head_slop
;
826 enda
= allocation
+ alloc_size
- tail_slop
;
828 /* We allocated N pages, which are likely not aligned, leaving
829 us with N-1 usable pages. We plan to place the page_group
830 structure somewhere in the slop. */
831 if (head_slop
>= sizeof (page_group
))
832 group
= (page_group
*)page
- 1;
835 /* We magically got an aligned allocation. Too bad, we have
836 to waste a page anyway. */
840 tail_slop
+= G
.pagesize
;
842 gcc_assert (tail_slop
>= sizeof (page_group
));
843 group
= (page_group
*)enda
;
844 tail_slop
-= sizeof (page_group
);
847 /* Remember that we allocated this memory. */
848 group
->next
= G
.page_groups
;
849 group
->allocation
= allocation
;
850 group
->alloc_size
= alloc_size
;
852 G
.page_groups
= group
;
853 G
.bytes_mapped
+= alloc_size
;
855 /* If we allocated multiple pages, put the rest on the free list. */
858 struct page_entry
*e
, *f
= G
.free_pages
;
859 for (a
= enda
- G
.pagesize
; a
!= page
; a
-= G
.pagesize
)
861 e
= XCNEWVAR (struct page_entry
, page_entry_size
);
863 e
->bytes
= G
.pagesize
;
875 entry
= XCNEWVAR (struct page_entry
, page_entry_size
);
877 entry
->bytes
= entry_size
;
879 entry
->context_depth
= G
.context_depth
;
880 entry
->order
= order
;
881 entry
->num_free_objects
= num_objects
;
882 entry
->next_bit_hint
= 1;
884 G
.context_depth_allocations
|= (unsigned long)1 << G
.context_depth
;
886 #ifdef USING_MALLOC_PAGE_GROUPS
887 entry
->group
= group
;
888 set_page_group_in_use (group
, page
);
891 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
892 increment the hint. */
893 entry
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
894 = (unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
);
896 set_page_table_entry (page
, entry
);
898 if (GGC_DEBUG_LEVEL
>= 2)
899 fprintf (G
.debug_file
,
900 "Allocating page at %p, object size=%lu, data %p-%p\n",
901 (void *) entry
, (unsigned long) OBJECT_SIZE (order
), page
,
902 page
+ entry_size
- 1);
907 /* Adjust the size of G.depth so that no index greater than the one
908 used by the top of the G.by_depth is used. */
915 if (G
.by_depth_in_use
)
917 top
= G
.by_depth
[G
.by_depth_in_use
-1];
919 /* Peel back indices in depth that index into by_depth, so that
920 as new elements are added to by_depth, we note the indices
921 of those elements, if they are for new context depths. */
922 while (G
.depth_in_use
> (size_t)top
->context_depth
+1)
927 /* For a page that is no longer needed, put it on the free page list. */
930 free_page (page_entry
*entry
)
932 if (GGC_DEBUG_LEVEL
>= 2)
933 fprintf (G
.debug_file
,
934 "Deallocating page at %p, data %p-%p\n", (void *) entry
,
935 entry
->page
, entry
->page
+ entry
->bytes
- 1);
937 /* Mark the page as inaccessible. Discard the handle to avoid handle
939 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (entry
->page
, entry
->bytes
));
941 set_page_table_entry (entry
->page
, NULL
);
943 #ifdef USING_MALLOC_PAGE_GROUPS
944 clear_page_group_in_use (entry
->group
, entry
->page
);
947 if (G
.by_depth_in_use
> 1)
949 page_entry
*top
= G
.by_depth
[G
.by_depth_in_use
-1];
950 int i
= entry
->index_by_depth
;
952 /* We cannot free a page from a context deeper than the current
954 gcc_assert (entry
->context_depth
== top
->context_depth
);
956 /* Put top element into freed slot. */
958 G
.save_in_use
[i
] = G
.save_in_use
[G
.by_depth_in_use
-1];
959 top
->index_by_depth
= i
;
965 entry
->next
= G
.free_pages
;
966 G
.free_pages
= entry
;
969 /* Release the free page cache to the system. */
975 page_entry
*p
, *next
;
979 /* Gather up adjacent pages so they are unmapped together. */
990 while (p
&& p
->page
== start
+ len
)
999 G
.bytes_mapped
-= len
;
1002 G
.free_pages
= NULL
;
1004 #ifdef USING_MALLOC_PAGE_GROUPS
1005 page_entry
**pp
, *p
;
1006 page_group
**gp
, *g
;
1008 /* Remove all pages from free page groups from the list. */
1010 while ((p
= *pp
) != NULL
)
1011 if (p
->group
->in_use
== 0)
1019 /* Remove all free page groups, and release the storage. */
1020 gp
= &G
.page_groups
;
1021 while ((g
= *gp
) != NULL
)
1025 G
.bytes_mapped
-= g
->alloc_size
;
1026 free (g
->allocation
);
1033 /* This table provides a fast way to determine ceil(log_2(size)) for
1034 allocation requests. The minimum allocation size is eight bytes. */
1035 #define NUM_SIZE_LOOKUP 512
1036 static unsigned char size_lookup
[NUM_SIZE_LOOKUP
] =
1038 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
1039 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1040 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1041 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1042 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1043 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1044 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1045 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1046 7, 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, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1052 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1053 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1054 8, 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, 9,
1067 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1068 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1069 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
1072 /* Typed allocation function. Does nothing special in this collector. */
1075 ggc_alloc_typed_stat (enum gt_types_enum type ATTRIBUTE_UNUSED
, size_t size
1078 return ggc_internal_alloc_stat (size PASS_MEM_STAT
);
1081 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1084 ggc_internal_alloc_stat (size_t size MEM_STAT_DECL
)
1086 size_t order
, word
, bit
, object_offset
, object_size
;
1087 struct page_entry
*entry
;
1090 if (size
< NUM_SIZE_LOOKUP
)
1092 order
= size_lookup
[size
];
1093 object_size
= OBJECT_SIZE (order
);
1098 while (size
> (object_size
= OBJECT_SIZE (order
)))
1102 /* If there are non-full pages for this size allocation, they are at
1103 the head of the list. */
1104 entry
= G
.pages
[order
];
1106 /* If there is no page for this object size, or all pages in this
1107 context are full, allocate a new page. */
1108 if (entry
== NULL
|| entry
->num_free_objects
== 0)
1110 struct page_entry
*new_entry
;
1111 new_entry
= alloc_page (order
);
1113 new_entry
->index_by_depth
= G
.by_depth_in_use
;
1114 push_by_depth (new_entry
, 0);
1116 /* We can skip context depths, if we do, make sure we go all the
1117 way to the new depth. */
1118 while (new_entry
->context_depth
>= G
.depth_in_use
)
1119 push_depth (G
.by_depth_in_use
-1);
1121 /* If this is the only entry, it's also the tail. If it is not
1122 the only entry, then we must update the PREV pointer of the
1123 ENTRY (G.pages[order]) to point to our new page entry. */
1125 G
.page_tails
[order
] = new_entry
;
1127 entry
->prev
= new_entry
;
1129 /* Put new pages at the head of the page list. By definition the
1130 entry at the head of the list always has a NULL pointer. */
1131 new_entry
->next
= entry
;
1132 new_entry
->prev
= NULL
;
1134 G
.pages
[order
] = new_entry
;
1136 /* For a new page, we know the word and bit positions (in the
1137 in_use bitmap) of the first available object -- they're zero. */
1138 new_entry
->next_bit_hint
= 1;
1145 /* First try to use the hint left from the previous allocation
1146 to locate a clear bit in the in-use bitmap. We've made sure
1147 that the one-past-the-end bit is always set, so if the hint
1148 has run over, this test will fail. */
1149 unsigned hint
= entry
->next_bit_hint
;
1150 word
= hint
/ HOST_BITS_PER_LONG
;
1151 bit
= hint
% HOST_BITS_PER_LONG
;
1153 /* If the hint didn't work, scan the bitmap from the beginning. */
1154 if ((entry
->in_use_p
[word
] >> bit
) & 1)
1157 while (~entry
->in_use_p
[word
] == 0)
1160 #if GCC_VERSION >= 3004
1161 bit
= __builtin_ctzl (~entry
->in_use_p
[word
]);
1163 while ((entry
->in_use_p
[word
] >> bit
) & 1)
1167 hint
= word
* HOST_BITS_PER_LONG
+ bit
;
1170 /* Next time, try the next bit. */
1171 entry
->next_bit_hint
= hint
+ 1;
1173 object_offset
= hint
* object_size
;
1176 /* Set the in-use bit. */
1177 entry
->in_use_p
[word
] |= ((unsigned long) 1 << bit
);
1179 /* Keep a running total of the number of free objects. If this page
1180 fills up, we may have to move it to the end of the list if the
1181 next page isn't full. If the next page is full, all subsequent
1182 pages are full, so there's no need to move it. */
1183 if (--entry
->num_free_objects
== 0
1184 && entry
->next
!= NULL
1185 && entry
->next
->num_free_objects
> 0)
1187 /* We have a new head for the list. */
1188 G
.pages
[order
] = entry
->next
;
1190 /* We are moving ENTRY to the end of the page table list.
1191 The new page at the head of the list will have NULL in
1192 its PREV field and ENTRY will have NULL in its NEXT field. */
1193 entry
->next
->prev
= NULL
;
1196 /* Append ENTRY to the tail of the list. */
1197 entry
->prev
= G
.page_tails
[order
];
1198 G
.page_tails
[order
]->next
= entry
;
1199 G
.page_tails
[order
] = entry
;
1202 /* Calculate the object's address. */
1203 result
= entry
->page
+ object_offset
;
1204 #ifdef GATHER_STATISTICS
1205 ggc_record_overhead (OBJECT_SIZE (order
), OBJECT_SIZE (order
) - size
,
1206 result PASS_MEM_STAT
);
1209 #ifdef ENABLE_GC_CHECKING
1210 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1211 exact same semantics in presence of memory bugs, regardless of
1212 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1213 handle to avoid handle leak. */
1214 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result
, object_size
));
1216 /* `Poison' the entire allocated object, including any padding at
1218 memset (result
, 0xaf, object_size
);
1220 /* Make the bytes after the end of the object unaccessible. Discard the
1221 handle to avoid handle leak. */
1222 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *) result
+ size
,
1223 object_size
- size
));
1226 /* Tell Valgrind that the memory is there, but its content isn't
1227 defined. The bytes at the end of the object are still marked
1229 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result
, size
));
1231 /* Keep track of how many bytes are being allocated. This
1232 information is used in deciding when to collect. */
1233 G
.allocated
+= object_size
;
1235 /* For timevar statistics. */
1236 timevar_ggc_mem_total
+= object_size
;
1238 #ifdef GATHER_STATISTICS
1240 size_t overhead
= object_size
- size
;
1242 G
.stats
.total_overhead
+= overhead
;
1243 G
.stats
.total_allocated
+= object_size
;
1244 G
.stats
.total_overhead_per_order
[order
] += overhead
;
1245 G
.stats
.total_allocated_per_order
[order
] += object_size
;
1249 G
.stats
.total_overhead_under32
+= overhead
;
1250 G
.stats
.total_allocated_under32
+= object_size
;
1254 G
.stats
.total_overhead_under64
+= overhead
;
1255 G
.stats
.total_allocated_under64
+= object_size
;
1259 G
.stats
.total_overhead_under128
+= overhead
;
1260 G
.stats
.total_allocated_under128
+= object_size
;
1265 if (GGC_DEBUG_LEVEL
>= 3)
1266 fprintf (G
.debug_file
,
1267 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1268 (unsigned long) size
, (unsigned long) object_size
, result
,
1274 /* Mark function for strings. */
1277 gt_ggc_m_S (const void *p
)
1282 unsigned long offset
;
1284 if (!p
|| !ggc_allocated_p (p
))
1287 /* Look up the page on which the object is alloced. . */
1288 entry
= lookup_page_table_entry (p
);
1291 /* Calculate the index of the object on the page; this is its bit
1292 position in the in_use_p bitmap. Note that because a char* might
1293 point to the middle of an object, we need special code here to
1294 make sure P points to the start of an object. */
1295 offset
= ((const char *) p
- entry
->page
) % object_size_table
[entry
->order
];
1298 /* Here we've seen a char* which does not point to the beginning
1299 of an allocated object. We assume it points to the middle of
1301 gcc_assert (offset
== offsetof (struct tree_string
, str
));
1302 p
= ((const char *) p
) - offset
;
1303 gt_ggc_mx_lang_tree_node (CONST_CAST (void *, p
));
1307 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1308 word
= bit
/ HOST_BITS_PER_LONG
;
1309 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1311 /* If the bit was previously set, skip it. */
1312 if (entry
->in_use_p
[word
] & mask
)
1315 /* Otherwise set it, and decrement the free object count. */
1316 entry
->in_use_p
[word
] |= mask
;
1317 entry
->num_free_objects
-= 1;
1319 if (GGC_DEBUG_LEVEL
>= 4)
1320 fprintf (G
.debug_file
, "Marking %p\n", p
);
1325 /* If P is not marked, marks it and return false. Otherwise return true.
1326 P must have been allocated by the GC allocator; it mustn't point to
1327 static objects, stack variables, or memory allocated with malloc. */
1330 ggc_set_mark (const void *p
)
1336 /* Look up the page on which the object is alloced. If the object
1337 wasn't allocated by the collector, we'll probably die. */
1338 entry
= lookup_page_table_entry (p
);
1341 /* Calculate the index of the object on the page; this is its bit
1342 position in the in_use_p bitmap. */
1343 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1344 word
= bit
/ HOST_BITS_PER_LONG
;
1345 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1347 /* If the bit was previously set, skip it. */
1348 if (entry
->in_use_p
[word
] & mask
)
1351 /* Otherwise set it, and decrement the free object count. */
1352 entry
->in_use_p
[word
] |= mask
;
1353 entry
->num_free_objects
-= 1;
1355 if (GGC_DEBUG_LEVEL
>= 4)
1356 fprintf (G
.debug_file
, "Marking %p\n", p
);
1361 /* Return 1 if P has been marked, zero otherwise.
1362 P must have been allocated by the GC allocator; it mustn't point to
1363 static objects, stack variables, or memory allocated with malloc. */
1366 ggc_marked_p (const void *p
)
1372 /* Look up the page on which the object is alloced. If the object
1373 wasn't allocated by the collector, we'll probably die. */
1374 entry
= lookup_page_table_entry (p
);
1377 /* Calculate the index of the object on the page; this is its bit
1378 position in the in_use_p bitmap. */
1379 bit
= OFFSET_TO_BIT (((const char *) p
) - entry
->page
, entry
->order
);
1380 word
= bit
/ HOST_BITS_PER_LONG
;
1381 mask
= (unsigned long) 1 << (bit
% HOST_BITS_PER_LONG
);
1383 return (entry
->in_use_p
[word
] & mask
) != 0;
1386 /* Return the size of the gc-able object P. */
1389 ggc_get_size (const void *p
)
1391 page_entry
*pe
= lookup_page_table_entry (p
);
1392 return OBJECT_SIZE (pe
->order
);
1395 /* Release the memory for object P. */
1400 page_entry
*pe
= lookup_page_table_entry (p
);
1401 size_t order
= pe
->order
;
1402 size_t size
= OBJECT_SIZE (order
);
1404 #ifdef GATHER_STATISTICS
1405 ggc_free_overhead (p
);
1408 if (GGC_DEBUG_LEVEL
>= 3)
1409 fprintf (G
.debug_file
,
1410 "Freeing object, actual size=%lu, at %p on %p\n",
1411 (unsigned long) size
, p
, (void *) pe
);
1413 #ifdef ENABLE_GC_CHECKING
1414 /* Poison the data, to indicate the data is garbage. */
1415 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (p
, size
));
1416 memset (p
, 0xa5, size
);
1418 /* Let valgrind know the object is free. */
1419 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (p
, size
));
1421 #ifdef ENABLE_GC_ALWAYS_COLLECT
1422 /* In the completely-anal-checking mode, we do *not* immediately free
1423 the data, but instead verify that the data is *actually* not
1424 reachable the next time we collect. */
1426 struct free_object
*fo
= XNEW (struct free_object
);
1428 fo
->next
= G
.free_object_list
;
1429 G
.free_object_list
= fo
;
1433 unsigned int bit_offset
, word
, bit
;
1435 G
.allocated
-= size
;
1437 /* Mark the object not-in-use. */
1438 bit_offset
= OFFSET_TO_BIT (((const char *) p
) - pe
->page
, order
);
1439 word
= bit_offset
/ HOST_BITS_PER_LONG
;
1440 bit
= bit_offset
% HOST_BITS_PER_LONG
;
1441 pe
->in_use_p
[word
] &= ~(1UL << bit
);
1443 if (pe
->num_free_objects
++ == 0)
1447 /* If the page is completely full, then it's supposed to
1448 be after all pages that aren't. Since we've freed one
1449 object from a page that was full, we need to move the
1450 page to the head of the list.
1452 PE is the node we want to move. Q is the previous node
1453 and P is the next node in the list. */
1455 if (q
&& q
->num_free_objects
== 0)
1461 /* If PE was at the end of the list, then Q becomes the
1462 new end of the list. If PE was not the end of the
1463 list, then we need to update the PREV field for P. */
1465 G
.page_tails
[order
] = q
;
1469 /* Move PE to the head of the list. */
1470 pe
->next
= G
.pages
[order
];
1472 G
.pages
[order
]->prev
= pe
;
1473 G
.pages
[order
] = pe
;
1476 /* Reset the hint bit to point to the only free object. */
1477 pe
->next_bit_hint
= bit_offset
;
1483 /* Subroutine of init_ggc which computes the pair of numbers used to
1484 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1486 This algorithm is taken from Granlund and Montgomery's paper
1487 "Division by Invariant Integers using Multiplication"
1488 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1492 compute_inverse (unsigned order
)
1497 size
= OBJECT_SIZE (order
);
1499 while (size
% 2 == 0)
1506 while (inv
* size
!= 1)
1507 inv
= inv
* (2 - inv
*size
);
1509 DIV_MULT (order
) = inv
;
1510 DIV_SHIFT (order
) = e
;
1513 /* Initialize the ggc-mmap allocator. */
1519 G
.pagesize
= getpagesize();
1520 G
.lg_pagesize
= exact_log2 (G
.pagesize
);
1522 #ifdef HAVE_MMAP_DEV_ZERO
1523 G
.dev_zero_fd
= open ("/dev/zero", O_RDONLY
);
1524 if (G
.dev_zero_fd
== -1)
1525 internal_error ("open /dev/zero: %m");
1529 G
.debug_file
= fopen ("ggc-mmap.debug", "w");
1531 G
.debug_file
= stdout
;
1535 /* StunOS has an amazing off-by-one error for the first mmap allocation
1536 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1537 believe, is an unaligned page allocation, which would cause us to
1538 hork badly if we tried to use it. */
1540 char *p
= alloc_anon (NULL
, G
.pagesize
);
1541 struct page_entry
*e
;
1542 if ((size_t)p
& (G
.pagesize
- 1))
1544 /* How losing. Discard this one and try another. If we still
1545 can't get something useful, give up. */
1547 p
= alloc_anon (NULL
, G
.pagesize
);
1548 gcc_assert (!((size_t)p
& (G
.pagesize
- 1)));
1551 /* We have a good page, might as well hold onto it... */
1552 e
= XCNEW (struct page_entry
);
1553 e
->bytes
= G
.pagesize
;
1555 e
->next
= G
.free_pages
;
1560 /* Initialize the object size table. */
1561 for (order
= 0; order
< HOST_BITS_PER_PTR
; ++order
)
1562 object_size_table
[order
] = (size_t) 1 << order
;
1563 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1565 size_t s
= extra_order_size_table
[order
- HOST_BITS_PER_PTR
];
1567 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1568 so that we're sure of getting aligned memory. */
1569 s
= ROUND_UP (s
, MAX_ALIGNMENT
);
1570 object_size_table
[order
] = s
;
1573 /* Initialize the objects-per-page and inverse tables. */
1574 for (order
= 0; order
< NUM_ORDERS
; ++order
)
1576 objects_per_page_table
[order
] = G
.pagesize
/ OBJECT_SIZE (order
);
1577 if (objects_per_page_table
[order
] == 0)
1578 objects_per_page_table
[order
] = 1;
1579 compute_inverse (order
);
1582 /* Reset the size_lookup array to put appropriately sized objects in
1583 the special orders. All objects bigger than the previous power
1584 of two, but no greater than the special size, should go in the
1586 for (order
= HOST_BITS_PER_PTR
; order
< NUM_ORDERS
; ++order
)
1591 i
= OBJECT_SIZE (order
);
1592 if (i
>= NUM_SIZE_LOOKUP
)
1595 for (o
= size_lookup
[i
]; o
== size_lookup
[i
]; --i
)
1596 size_lookup
[i
] = order
;
1601 G
.depth
= XNEWVEC (unsigned int, G
.depth_max
);
1603 G
.by_depth_in_use
= 0;
1604 G
.by_depth_max
= INITIAL_PTE_COUNT
;
1605 G
.by_depth
= XNEWVEC (page_entry
*, G
.by_depth_max
);
1606 G
.save_in_use
= XNEWVEC (unsigned long *, G
.by_depth_max
);
1609 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1610 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1613 ggc_recalculate_in_use_p (page_entry
*p
)
1618 /* Because the past-the-end bit in in_use_p is always set, we
1619 pretend there is one additional object. */
1620 num_objects
= OBJECTS_IN_PAGE (p
) + 1;
1622 /* Reset the free object count. */
1623 p
->num_free_objects
= num_objects
;
1625 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1627 i
< CEIL (BITMAP_SIZE (num_objects
),
1628 sizeof (*p
->in_use_p
));
1633 /* Something is in use if it is marked, or if it was in use in a
1634 context further down the context stack. */
1635 p
->in_use_p
[i
] |= save_in_use_p (p
)[i
];
1637 /* Decrement the free object count for every object allocated. */
1638 for (j
= p
->in_use_p
[i
]; j
; j
>>= 1)
1639 p
->num_free_objects
-= (j
& 1);
1642 gcc_assert (p
->num_free_objects
< num_objects
);
1645 /* Unmark all objects. */
1652 for (order
= 2; order
< NUM_ORDERS
; order
++)
1656 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1658 size_t num_objects
= OBJECTS_IN_PAGE (p
);
1659 size_t bitmap_size
= BITMAP_SIZE (num_objects
+ 1);
1661 /* The data should be page-aligned. */
1662 gcc_assert (!((size_t) p
->page
& (G
.pagesize
- 1)));
1664 /* Pages that aren't in the topmost context are not collected;
1665 nevertheless, we need their in-use bit vectors to store GC
1666 marks. So, back them up first. */
1667 if (p
->context_depth
< G
.context_depth
)
1669 if (! save_in_use_p (p
))
1670 save_in_use_p (p
) = XNEWVAR (unsigned long, bitmap_size
);
1671 memcpy (save_in_use_p (p
), p
->in_use_p
, bitmap_size
);
1674 /* Reset reset the number of free objects and clear the
1675 in-use bits. These will be adjusted by mark_obj. */
1676 p
->num_free_objects
= num_objects
;
1677 memset (p
->in_use_p
, 0, bitmap_size
);
1679 /* Make sure the one-past-the-end bit is always set. */
1680 p
->in_use_p
[num_objects
/ HOST_BITS_PER_LONG
]
1681 = ((unsigned long) 1 << (num_objects
% HOST_BITS_PER_LONG
));
1686 /* Free all empty pages. Partially empty pages need no attention
1687 because the `mark' bit doubles as an `unused' bit. */
1694 for (order
= 2; order
< NUM_ORDERS
; order
++)
1696 /* The last page-entry to consider, regardless of entries
1697 placed at the end of the list. */
1698 page_entry
* const last
= G
.page_tails
[order
];
1701 size_t live_objects
;
1702 page_entry
*p
, *previous
;
1712 page_entry
*next
= p
->next
;
1714 /* Loop until all entries have been examined. */
1717 num_objects
= OBJECTS_IN_PAGE (p
);
1719 /* Add all live objects on this page to the count of
1720 allocated memory. */
1721 live_objects
= num_objects
- p
->num_free_objects
;
1723 G
.allocated
+= OBJECT_SIZE (order
) * live_objects
;
1725 /* Only objects on pages in the topmost context should get
1727 if (p
->context_depth
< G
.context_depth
)
1730 /* Remove the page if it's empty. */
1731 else if (live_objects
== 0)
1733 /* If P was the first page in the list, then NEXT
1734 becomes the new first page in the list, otherwise
1735 splice P out of the forward pointers. */
1737 G
.pages
[order
] = next
;
1739 previous
->next
= next
;
1741 /* Splice P out of the back pointers too. */
1743 next
->prev
= previous
;
1745 /* Are we removing the last element? */
1746 if (p
== G
.page_tails
[order
])
1747 G
.page_tails
[order
] = previous
;
1752 /* If the page is full, move it to the end. */
1753 else if (p
->num_free_objects
== 0)
1755 /* Don't move it if it's already at the end. */
1756 if (p
!= G
.page_tails
[order
])
1758 /* Move p to the end of the list. */
1760 p
->prev
= G
.page_tails
[order
];
1761 G
.page_tails
[order
]->next
= p
;
1763 /* Update the tail pointer... */
1764 G
.page_tails
[order
] = p
;
1766 /* ... and the head pointer, if necessary. */
1768 G
.pages
[order
] = next
;
1770 previous
->next
= next
;
1772 /* And update the backpointer in NEXT if necessary. */
1774 next
->prev
= previous
;
1780 /* If we've fallen through to here, it's a page in the
1781 topmost context that is neither full nor empty. Such a
1782 page must precede pages at lesser context depth in the
1783 list, so move it to the head. */
1784 else if (p
!= G
.pages
[order
])
1786 previous
->next
= p
->next
;
1788 /* Update the backchain in the next node if it exists. */
1790 p
->next
->prev
= previous
;
1792 /* Move P to the head of the list. */
1793 p
->next
= G
.pages
[order
];
1795 G
.pages
[order
]->prev
= p
;
1797 /* Update the head pointer. */
1800 /* Are we moving the last element? */
1801 if (G
.page_tails
[order
] == p
)
1802 G
.page_tails
[order
] = previous
;
1811 /* Now, restore the in_use_p vectors for any pages from contexts
1812 other than the current one. */
1813 for (p
= G
.pages
[order
]; p
; p
= p
->next
)
1814 if (p
->context_depth
!= G
.context_depth
)
1815 ggc_recalculate_in_use_p (p
);
1819 #ifdef ENABLE_GC_CHECKING
1820 /* Clobber all free objects. */
1827 for (order
= 2; order
< NUM_ORDERS
; order
++)
1829 size_t size
= OBJECT_SIZE (order
);
1832 for (p
= G
.pages
[order
]; p
!= NULL
; p
= p
->next
)
1837 if (p
->context_depth
!= G
.context_depth
)
1838 /* Since we don't do any collection for pages in pushed
1839 contexts, there's no need to do any poisoning. And
1840 besides, the IN_USE_P array isn't valid until we pop
1844 num_objects
= OBJECTS_IN_PAGE (p
);
1845 for (i
= 0; i
< num_objects
; i
++)
1848 word
= i
/ HOST_BITS_PER_LONG
;
1849 bit
= i
% HOST_BITS_PER_LONG
;
1850 if (((p
->in_use_p
[word
] >> bit
) & 1) == 0)
1852 char *object
= p
->page
+ i
* size
;
1854 /* Keep poison-by-write when we expect to use Valgrind,
1855 so the exact same memory semantics is kept, in case
1856 there are memory errors. We override this request
1858 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (object
,
1860 memset (object
, 0xa5, size
);
1862 /* Drop the handle to avoid handle leak. */
1863 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (object
, size
));
1870 #define poison_pages()
1873 #ifdef ENABLE_GC_ALWAYS_COLLECT
1874 /* Validate that the reportedly free objects actually are. */
1877 validate_free_objects (void)
1879 struct free_object
*f
, *next
, *still_free
= NULL
;
1881 for (f
= G
.free_object_list
; f
; f
= next
)
1883 page_entry
*pe
= lookup_page_table_entry (f
->object
);
1886 bit
= OFFSET_TO_BIT ((char *)f
->object
- pe
->page
, pe
->order
);
1887 word
= bit
/ HOST_BITS_PER_LONG
;
1888 bit
= bit
% HOST_BITS_PER_LONG
;
1891 /* Make certain it isn't visible from any root. Notice that we
1892 do this check before sweep_pages merges save_in_use_p. */
1893 gcc_assert (!(pe
->in_use_p
[word
] & (1UL << bit
)));
1895 /* If the object comes from an outer context, then retain the
1896 free_object entry, so that we can verify that the address
1897 isn't live on the stack in some outer context. */
1898 if (pe
->context_depth
!= G
.context_depth
)
1900 f
->next
= still_free
;
1907 G
.free_object_list
= still_free
;
1910 #define validate_free_objects()
1913 /* Top level mark-and-sweep routine. */
1918 /* Avoid frequent unnecessary work by skipping collection if the
1919 total allocations haven't expanded much since the last
1921 float allocated_last_gc
=
1922 MAX (G
.allocated_last_gc
, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE
) * 1024);
1924 float min_expand
= allocated_last_gc
* PARAM_VALUE (GGC_MIN_EXPAND
) / 100;
1926 if (G
.allocated
< allocated_last_gc
+ min_expand
&& !ggc_force_collect
)
1929 timevar_push (TV_GC
);
1931 fprintf (stderr
, " {GC %luk -> ", (unsigned long) G
.allocated
/ 1024);
1932 if (GGC_DEBUG_LEVEL
>= 2)
1933 fprintf (G
.debug_file
, "BEGIN COLLECTING\n");
1935 /* Zero the total allocated bytes. This will be recalculated in the
1939 /* Release the pages we freed the last time we collected, but didn't
1940 reuse in the interim. */
1943 /* Indicate that we've seen collections at this context depth. */
1944 G
.context_depth_collections
= ((unsigned long)1 << (G
.context_depth
+ 1)) - 1;
1946 invoke_plugin_callbacks (PLUGIN_GGC_START
, NULL
);
1950 #ifdef GATHER_STATISTICS
1951 ggc_prune_overhead_list ();
1954 validate_free_objects ();
1957 G
.allocated_last_gc
= G
.allocated
;
1959 invoke_plugin_callbacks (PLUGIN_GGC_END
, NULL
);
1961 timevar_pop (TV_GC
);
1964 fprintf (stderr
, "%luk}", (unsigned long) G
.allocated
/ 1024);
1965 if (GGC_DEBUG_LEVEL
>= 2)
1966 fprintf (G
.debug_file
, "END COLLECTING\n");
1969 /* Print allocation statistics. */
1970 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
1972 : ((x) < 1024*1024*10 \
1974 : (x) / (1024*1024))))
1975 #define STAT_LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
1978 ggc_print_statistics (void)
1980 struct ggc_statistics stats
;
1982 size_t total_overhead
= 0;
1984 /* Clear the statistics. */
1985 memset (&stats
, 0, sizeof (stats
));
1987 /* Make sure collection will really occur. */
1988 G
.allocated_last_gc
= 0;
1990 /* Collect and print the statistics common across collectors. */
1991 ggc_print_common_statistics (stderr
, &stats
);
1993 /* Release free pages so that we will not count the bytes allocated
1994 there as part of the total allocated memory. */
1997 /* Collect some information about the various sizes of
2000 "Memory still allocated at the end of the compilation process\n");
2001 fprintf (stderr
, "%-5s %10s %10s %10s\n",
2002 "Size", "Allocated", "Used", "Overhead");
2003 for (i
= 0; i
< NUM_ORDERS
; ++i
)
2010 /* Skip empty entries. */
2014 overhead
= allocated
= in_use
= 0;
2016 /* Figure out the total number of bytes allocated for objects of
2017 this size, and how many of them are actually in use. Also figure
2018 out how much memory the page table is using. */
2019 for (p
= G
.pages
[i
]; p
; p
= p
->next
)
2021 allocated
+= p
->bytes
;
2023 (OBJECTS_IN_PAGE (p
) - p
->num_free_objects
) * OBJECT_SIZE (i
);
2025 overhead
+= (sizeof (page_entry
) - sizeof (long)
2026 + BITMAP_SIZE (OBJECTS_IN_PAGE (p
) + 1));
2028 fprintf (stderr
, "%-5lu %10lu%c %10lu%c %10lu%c\n",
2029 (unsigned long) OBJECT_SIZE (i
),
2030 SCALE (allocated
), STAT_LABEL (allocated
),
2031 SCALE (in_use
), STAT_LABEL (in_use
),
2032 SCALE (overhead
), STAT_LABEL (overhead
));
2033 total_overhead
+= overhead
;
2035 fprintf (stderr
, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
2036 SCALE (G
.bytes_mapped
), STAT_LABEL (G
.bytes_mapped
),
2037 SCALE (G
.allocated
), STAT_LABEL(G
.allocated
),
2038 SCALE (total_overhead
), STAT_LABEL (total_overhead
));
2040 #ifdef GATHER_STATISTICS
2042 fprintf (stderr
, "\nTotal allocations and overheads during the compilation process\n");
2044 fprintf (stderr
, "Total Overhead: %10lld\n",
2045 G
.stats
.total_overhead
);
2046 fprintf (stderr
, "Total Allocated: %10lld\n",
2047 G
.stats
.total_allocated
);
2049 fprintf (stderr
, "Total Overhead under 32B: %10lld\n",
2050 G
.stats
.total_overhead_under32
);
2051 fprintf (stderr
, "Total Allocated under 32B: %10lld\n",
2052 G
.stats
.total_allocated_under32
);
2053 fprintf (stderr
, "Total Overhead under 64B: %10lld\n",
2054 G
.stats
.total_overhead_under64
);
2055 fprintf (stderr
, "Total Allocated under 64B: %10lld\n",
2056 G
.stats
.total_allocated_under64
);
2057 fprintf (stderr
, "Total Overhead under 128B: %10lld\n",
2058 G
.stats
.total_overhead_under128
);
2059 fprintf (stderr
, "Total Allocated under 128B: %10lld\n",
2060 G
.stats
.total_allocated_under128
);
2062 for (i
= 0; i
< NUM_ORDERS
; i
++)
2063 if (G
.stats
.total_allocated_per_order
[i
])
2065 fprintf (stderr
, "Total Overhead page size %7lu: %10lld\n",
2066 (unsigned long) OBJECT_SIZE (i
),
2067 G
.stats
.total_overhead_per_order
[i
]);
2068 fprintf (stderr
, "Total Allocated page size %7lu: %10lld\n",
2069 (unsigned long) OBJECT_SIZE (i
),
2070 G
.stats
.total_allocated_per_order
[i
]);
2076 struct ggc_pch_ondisk
2078 unsigned totals
[NUM_ORDERS
];
2083 struct ggc_pch_ondisk d
;
2084 size_t base
[NUM_ORDERS
];
2085 size_t written
[NUM_ORDERS
];
2088 struct ggc_pch_data
*
2091 return XCNEW (struct ggc_pch_data
);
2095 ggc_pch_count_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2096 size_t size
, bool is_string ATTRIBUTE_UNUSED
,
2097 enum gt_types_enum type ATTRIBUTE_UNUSED
)
2101 if (size
< NUM_SIZE_LOOKUP
)
2102 order
= size_lookup
[size
];
2106 while (size
> OBJECT_SIZE (order
))
2110 d
->d
.totals
[order
]++;
2114 ggc_pch_total_size (struct ggc_pch_data
*d
)
2119 for (i
= 0; i
< NUM_ORDERS
; i
++)
2120 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2125 ggc_pch_this_base (struct ggc_pch_data
*d
, void *base
)
2127 size_t a
= (size_t) base
;
2130 for (i
= 0; i
< NUM_ORDERS
; i
++)
2133 a
+= ROUND_UP (d
->d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2139 ggc_pch_alloc_object (struct ggc_pch_data
*d
, void *x ATTRIBUTE_UNUSED
,
2140 size_t size
, bool is_string ATTRIBUTE_UNUSED
,
2141 enum gt_types_enum type ATTRIBUTE_UNUSED
)
2146 if (size
< NUM_SIZE_LOOKUP
)
2147 order
= size_lookup
[size
];
2151 while (size
> OBJECT_SIZE (order
))
2155 result
= (char *) d
->base
[order
];
2156 d
->base
[order
] += OBJECT_SIZE (order
);
2161 ggc_pch_prepare_write (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2162 FILE *f ATTRIBUTE_UNUSED
)
2164 /* Nothing to do. */
2168 ggc_pch_write_object (struct ggc_pch_data
*d ATTRIBUTE_UNUSED
,
2169 FILE *f
, void *x
, void *newx ATTRIBUTE_UNUSED
,
2170 size_t size
, bool is_string ATTRIBUTE_UNUSED
)
2173 static const char emptyBytes
[256] = { 0 };
2175 if (size
< NUM_SIZE_LOOKUP
)
2176 order
= size_lookup
[size
];
2180 while (size
> OBJECT_SIZE (order
))
2184 if (fwrite (x
, size
, 1, f
) != 1)
2185 fatal_error ("can't write PCH file: %m");
2187 /* If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
2188 object out to OBJECT_SIZE(order). This happens for strings. */
2190 if (size
!= OBJECT_SIZE (order
))
2192 unsigned padding
= OBJECT_SIZE(order
) - size
;
2194 /* To speed small writes, we use a nulled-out array that's larger
2195 than most padding requests as the source for our null bytes. This
2196 permits us to do the padding with fwrite() rather than fseek(), and
2197 limits the chance the OS may try to flush any outstanding writes. */
2198 if (padding
<= sizeof(emptyBytes
))
2200 if (fwrite (emptyBytes
, 1, padding
, f
) != padding
)
2201 fatal_error ("can't write PCH file");
2205 /* Larger than our buffer? Just default to fseek. */
2206 if (fseek (f
, padding
, SEEK_CUR
) != 0)
2207 fatal_error ("can't write PCH file");
2211 d
->written
[order
]++;
2212 if (d
->written
[order
] == d
->d
.totals
[order
]
2213 && fseek (f
, ROUND_UP_VALUE (d
->d
.totals
[order
] * OBJECT_SIZE (order
),
2216 fatal_error ("can't write PCH file: %m");
2220 ggc_pch_finish (struct ggc_pch_data
*d
, FILE *f
)
2222 if (fwrite (&d
->d
, sizeof (d
->d
), 1, f
) != 1)
2223 fatal_error ("can't write PCH file: %m");
2227 /* Move the PCH PTE entries just added to the end of by_depth, to the
2231 move_ptes_to_front (int count_old_page_tables
, int count_new_page_tables
)
2235 /* First, we swap the new entries to the front of the varrays. */
2236 page_entry
**new_by_depth
;
2237 unsigned long **new_save_in_use
;
2239 new_by_depth
= XNEWVEC (page_entry
*, G
.by_depth_max
);
2240 new_save_in_use
= XNEWVEC (unsigned long *, G
.by_depth_max
);
2242 memcpy (&new_by_depth
[0],
2243 &G
.by_depth
[count_old_page_tables
],
2244 count_new_page_tables
* sizeof (void *));
2245 memcpy (&new_by_depth
[count_new_page_tables
],
2247 count_old_page_tables
* sizeof (void *));
2248 memcpy (&new_save_in_use
[0],
2249 &G
.save_in_use
[count_old_page_tables
],
2250 count_new_page_tables
* sizeof (void *));
2251 memcpy (&new_save_in_use
[count_new_page_tables
],
2253 count_old_page_tables
* sizeof (void *));
2256 free (G
.save_in_use
);
2258 G
.by_depth
= new_by_depth
;
2259 G
.save_in_use
= new_save_in_use
;
2261 /* Now update all the index_by_depth fields. */
2262 for (i
= G
.by_depth_in_use
; i
> 0; --i
)
2264 page_entry
*p
= G
.by_depth
[i
-1];
2265 p
->index_by_depth
= i
-1;
2268 /* And last, we update the depth pointers in G.depth. The first
2269 entry is already 0, and context 0 entries always start at index
2270 0, so there is nothing to update in the first slot. We need a
2271 second slot, only if we have old ptes, and if we do, they start
2272 at index count_new_page_tables. */
2273 if (count_old_page_tables
)
2274 push_depth (count_new_page_tables
);
2278 ggc_pch_read (FILE *f
, void *addr
)
2280 struct ggc_pch_ondisk d
;
2282 char *offs
= (char *) addr
;
2283 unsigned long count_old_page_tables
;
2284 unsigned long count_new_page_tables
;
2286 count_old_page_tables
= G
.by_depth_in_use
;
2288 /* We've just read in a PCH file. So, every object that used to be
2289 allocated is now free. */
2291 #ifdef ENABLE_GC_CHECKING
2294 /* Since we free all the allocated objects, the free list becomes
2295 useless. Validate it now, which will also clear it. */
2296 validate_free_objects();
2298 /* No object read from a PCH file should ever be freed. So, set the
2299 context depth to 1, and set the depth of all the currently-allocated
2300 pages to be 1 too. PCH pages will have depth 0. */
2301 gcc_assert (!G
.context_depth
);
2302 G
.context_depth
= 1;
2303 for (i
= 0; i
< NUM_ORDERS
; i
++)
2306 for (p
= G
.pages
[i
]; p
!= NULL
; p
= p
->next
)
2307 p
->context_depth
= G
.context_depth
;
2310 /* Allocate the appropriate page-table entries for the pages read from
2312 if (fread (&d
, sizeof (d
), 1, f
) != 1)
2313 fatal_error ("can't read PCH file: %m");
2315 for (i
= 0; i
< NUM_ORDERS
; i
++)
2317 struct page_entry
*entry
;
2323 if (d
.totals
[i
] == 0)
2326 bytes
= ROUND_UP (d
.totals
[i
] * OBJECT_SIZE (i
), G
.pagesize
);
2327 num_objs
= bytes
/ OBJECT_SIZE (i
);
2328 entry
= XCNEWVAR (struct page_entry
, (sizeof (struct page_entry
)
2330 + BITMAP_SIZE (num_objs
+ 1)));
2331 entry
->bytes
= bytes
;
2333 entry
->context_depth
= 0;
2335 entry
->num_free_objects
= 0;
2339 j
+ HOST_BITS_PER_LONG
<= num_objs
+ 1;
2340 j
+= HOST_BITS_PER_LONG
)
2341 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
] = -1;
2342 for (; j
< num_objs
+ 1; j
++)
2343 entry
->in_use_p
[j
/ HOST_BITS_PER_LONG
]
2344 |= 1L << (j
% HOST_BITS_PER_LONG
);
2346 for (pte
= entry
->page
;
2347 pte
< entry
->page
+ entry
->bytes
;
2349 set_page_table_entry (pte
, entry
);
2351 if (G
.page_tails
[i
] != NULL
)
2352 G
.page_tails
[i
]->next
= entry
;
2355 G
.page_tails
[i
] = entry
;
2357 /* We start off by just adding all the new information to the
2358 end of the varrays, later, we will move the new information
2359 to the front of the varrays, as the PCH page tables are at
2361 push_by_depth (entry
, 0);
2364 /* Now, we update the various data structures that speed page table
2366 count_new_page_tables
= G
.by_depth_in_use
- count_old_page_tables
;
2368 move_ptes_to_front (count_old_page_tables
, count_new_page_tables
);
2370 /* Update the statistics. */
2371 G
.allocated
= G
.allocated_last_gc
= offs
- (char *)addr
;
2379 struct alloc_zone rtl_zone
;
2380 struct alloc_zone tree_zone
;
2381 struct alloc_zone tree_id_zone
;