* inclhack.def (AAB_aix_fcntl): New fix.
[official-gcc.git] / gcc / ggc-page.c
blobca3f6325fa9f83a877af0ca8d7508bf3ef06ae36
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, 2011 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
10 version.
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
15 for more details.
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/>. */
21 #include "config.h"
22 #include "system.h"
23 #include "coretypes.h"
24 #include "tm.h"
25 #include "tree.h"
26 #include "rtl.h"
27 #include "tm_p.h"
28 #include "diagnostic-core.h"
29 #include "flags.h"
30 #include "ggc.h"
31 #include "ggc-internal.h"
32 #include "timevar.h"
33 #include "params.h"
34 #include "tree-flow.h"
35 #include "cfgloop.h"
36 #include "plugin.h"
38 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
39 file open. Prefer either to valloc. */
40 #ifdef HAVE_MMAP_ANON
41 # undef HAVE_MMAP_DEV_ZERO
42 # define USING_MMAP
43 #endif
45 #ifdef HAVE_MMAP_DEV_ZERO
46 # define USING_MMAP
47 #endif
49 #ifndef USING_MMAP
50 #define USING_MALLOC_PAGE_GROUPS
51 #endif
53 #if defined(HAVE_MADVISE) && HAVE_DECL_MADVISE && defined(MADV_DONTNEED) \
54 && defined(USING_MMAP)
55 # define USING_MADVISE
56 #endif
58 /* Strategy:
60 This garbage-collecting allocator allocates objects on one of a set
61 of pages. Each page can allocate objects of a single size only;
62 available sizes are powers of two starting at four bytes. The size
63 of an allocation request is rounded up to the next power of two
64 (`order'), and satisfied from the appropriate page.
66 Each page is recorded in a page-entry, which also maintains an
67 in-use bitmap of object positions on the page. This allows the
68 allocation state of a particular object to be flipped without
69 touching the page itself.
71 Each page-entry also has a context depth, which is used to track
72 pushing and popping of allocation contexts. Only objects allocated
73 in the current (highest-numbered) context may be collected.
75 Page entries are arranged in an array of singly-linked lists. The
76 array is indexed by the allocation size, in bits, of the pages on
77 it; i.e. all pages on a list allocate objects of the same size.
78 Pages are ordered on the list such that all non-full pages precede
79 all full pages, with non-full pages arranged in order of decreasing
80 context depth.
82 Empty pages (of all orders) are kept on a single page cache list,
83 and are considered first when new pages are required; they are
84 deallocated at the start of the next collection if they haven't
85 been recycled by then. */
87 /* Define GGC_DEBUG_LEVEL to print debugging information.
88 0: No debugging output.
89 1: GC statistics only.
90 2: Page-entry allocations/deallocations as well.
91 3: Object allocations as well.
92 4: Object marks as well. */
93 #define GGC_DEBUG_LEVEL (0)
95 #ifndef HOST_BITS_PER_PTR
96 #define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
97 #endif
100 /* A two-level tree is used to look up the page-entry for a given
101 pointer. Two chunks of the pointer's bits are extracted to index
102 the first and second levels of the tree, as follows:
104 HOST_PAGE_SIZE_BITS
105 32 | |
106 msb +----------------+----+------+------+ lsb
107 | | |
108 PAGE_L1_BITS |
110 PAGE_L2_BITS
112 The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
113 pages are aligned on system page boundaries. The next most
114 significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
115 index values in the lookup table, respectively.
117 For 32-bit architectures and the settings below, there are no
118 leftover bits. For architectures with wider pointers, the lookup
119 tree points to a list of pages, which must be scanned to find the
120 correct one. */
122 #define PAGE_L1_BITS (8)
123 #define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
124 #define PAGE_L1_SIZE ((uintptr_t) 1 << PAGE_L1_BITS)
125 #define PAGE_L2_SIZE ((uintptr_t) 1 << PAGE_L2_BITS)
127 #define LOOKUP_L1(p) \
128 (((uintptr_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
130 #define LOOKUP_L2(p) \
131 (((uintptr_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
133 /* The number of objects per allocation page, for objects on a page of
134 the indicated ORDER. */
135 #define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
137 /* The number of objects in P. */
138 #define OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
140 /* The size of an object on a page of the indicated ORDER. */
141 #define OBJECT_SIZE(ORDER) object_size_table[ORDER]
143 /* For speed, we avoid doing a general integer divide to locate the
144 offset in the allocation bitmap, by precalculating numbers M, S
145 such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
146 within the page which is evenly divisible by the object size Z. */
147 #define DIV_MULT(ORDER) inverse_table[ORDER].mult
148 #define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
149 #define OFFSET_TO_BIT(OFFSET, ORDER) \
150 (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
152 /* We use this structure to determine the alignment required for
153 allocations. For power-of-two sized allocations, that's not a
154 problem, but it does matter for odd-sized allocations.
155 We do not care about alignment for floating-point types. */
157 struct max_alignment {
158 char c;
159 union {
160 HOST_WIDEST_INT i;
161 void *p;
162 } u;
165 /* The biggest alignment required. */
167 #define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
170 /* The number of extra orders, not corresponding to power-of-two sized
171 objects. */
173 #define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
175 #define RTL_SIZE(NSLOTS) \
176 (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))
178 #define TREE_EXP_SIZE(OPS) \
179 (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
181 /* The Ith entry is the maximum size of an object to be stored in the
182 Ith extra order. Adding a new entry to this array is the *only*
183 thing you need to do to add a new special allocation size. */
185 static const size_t extra_order_size_table[] = {
186 /* Extra orders for small non-power-of-two multiples of MAX_ALIGNMENT.
187 There are a lot of structures with these sizes and explicitly
188 listing them risks orders being dropped because they changed size. */
189 MAX_ALIGNMENT * 3,
190 MAX_ALIGNMENT * 5,
191 MAX_ALIGNMENT * 6,
192 MAX_ALIGNMENT * 7,
193 MAX_ALIGNMENT * 9,
194 MAX_ALIGNMENT * 10,
195 MAX_ALIGNMENT * 11,
196 MAX_ALIGNMENT * 12,
197 MAX_ALIGNMENT * 13,
198 MAX_ALIGNMENT * 14,
199 MAX_ALIGNMENT * 15,
200 sizeof (struct tree_decl_non_common),
201 sizeof (struct tree_field_decl),
202 sizeof (struct tree_parm_decl),
203 sizeof (struct tree_var_decl),
204 sizeof (struct tree_type_non_common),
205 sizeof (struct function),
206 sizeof (struct basic_block_def),
207 sizeof (struct cgraph_node),
208 sizeof (struct loop),
211 /* The total number of orders. */
213 #define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
215 /* Compute the smallest nonnegative number which when added to X gives
216 a multiple of F. */
218 #define ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
220 /* Compute the smallest multiple of F that is >= X. */
222 #define ROUND_UP(x, f) (CEIL (x, f) * (f))
224 /* Round X to next multiple of the page size */
226 #define PAGE_ALIGN(x) (((x) + G.pagesize - 1) & ~(G.pagesize - 1))
228 /* The Ith entry is the number of objects on a page or order I. */
230 static unsigned objects_per_page_table[NUM_ORDERS];
232 /* The Ith entry is the size of an object on a page of order I. */
234 static size_t object_size_table[NUM_ORDERS];
236 /* The Ith entry is a pair of numbers (mult, shift) such that
237 ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
238 for all k evenly divisible by OBJECT_SIZE(I). */
240 static struct
242 size_t mult;
243 unsigned int shift;
245 inverse_table[NUM_ORDERS];
247 /* A page_entry records the status of an allocation page. This
248 structure is dynamically sized to fit the bitmap in_use_p. */
249 typedef struct page_entry
251 /* The next page-entry with objects of the same size, or NULL if
252 this is the last page-entry. */
253 struct page_entry *next;
255 /* The previous page-entry with objects of the same size, or NULL if
256 this is the first page-entry. The PREV pointer exists solely to
257 keep the cost of ggc_free manageable. */
258 struct page_entry *prev;
260 /* The number of bytes allocated. (This will always be a multiple
261 of the host system page size.) */
262 size_t bytes;
264 /* The address at which the memory is allocated. */
265 char *page;
267 #ifdef USING_MALLOC_PAGE_GROUPS
268 /* Back pointer to the page group this page came from. */
269 struct page_group *group;
270 #endif
272 /* This is the index in the by_depth varray where this page table
273 can be found. */
274 unsigned long index_by_depth;
276 /* Context depth of this page. */
277 unsigned short context_depth;
279 /* The number of free objects remaining on this page. */
280 unsigned short num_free_objects;
282 /* A likely candidate for the bit position of a free object for the
283 next allocation from this page. */
284 unsigned short next_bit_hint;
286 /* The lg of size of objects allocated from this page. */
287 unsigned char order;
289 /* Discarded page? */
290 bool discarded;
292 /* A bit vector indicating whether or not objects are in use. The
293 Nth bit is one if the Nth object on this page is allocated. This
294 array is dynamically sized. */
295 unsigned long in_use_p[1];
296 } page_entry;
298 #ifdef USING_MALLOC_PAGE_GROUPS
299 /* A page_group describes a large allocation from malloc, from which
300 we parcel out aligned pages. */
301 typedef struct page_group
303 /* A linked list of all extant page groups. */
304 struct page_group *next;
306 /* The address we received from malloc. */
307 char *allocation;
309 /* The size of the block. */
310 size_t alloc_size;
312 /* A bitmask of pages in use. */
313 unsigned int in_use;
314 } page_group;
315 #endif
317 #if HOST_BITS_PER_PTR <= 32
319 /* On 32-bit hosts, we use a two level page table, as pictured above. */
320 typedef page_entry **page_table[PAGE_L1_SIZE];
322 #else
324 /* On 64-bit hosts, we use the same two level page tables plus a linked
325 list that disambiguates the top 32-bits. There will almost always be
326 exactly one entry in the list. */
327 typedef struct page_table_chain
329 struct page_table_chain *next;
330 size_t high_bits;
331 page_entry **table[PAGE_L1_SIZE];
332 } *page_table;
334 #endif
336 #ifdef ENABLE_GC_ALWAYS_COLLECT
337 /* List of free objects to be verified as actually free on the
338 next collection. */
339 struct free_object
341 void *object;
342 struct free_object *next;
344 #endif
346 /* The rest of the global variables. */
347 static struct globals
349 /* The Nth element in this array is a page with objects of size 2^N.
350 If there are any pages with free objects, they will be at the
351 head of the list. NULL if there are no page-entries for this
352 object size. */
353 page_entry *pages[NUM_ORDERS];
355 /* The Nth element in this array is the last page with objects of
356 size 2^N. NULL if there are no page-entries for this object
357 size. */
358 page_entry *page_tails[NUM_ORDERS];
360 /* Lookup table for associating allocation pages with object addresses. */
361 page_table lookup;
363 /* The system's page size. */
364 size_t pagesize;
365 size_t lg_pagesize;
367 /* Bytes currently allocated. */
368 size_t allocated;
370 /* Bytes currently allocated at the end of the last collection. */
371 size_t allocated_last_gc;
373 /* Total amount of memory mapped. */
374 size_t bytes_mapped;
376 /* Bit N set if any allocations have been done at context depth N. */
377 unsigned long context_depth_allocations;
379 /* Bit N set if any collections have been done at context depth N. */
380 unsigned long context_depth_collections;
382 /* The current depth in the context stack. */
383 unsigned short context_depth;
385 /* A file descriptor open to /dev/zero for reading. */
386 #if defined (HAVE_MMAP_DEV_ZERO)
387 int dev_zero_fd;
388 #endif
390 /* A cache of free system pages. */
391 page_entry *free_pages;
393 #ifdef USING_MALLOC_PAGE_GROUPS
394 page_group *page_groups;
395 #endif
397 /* The file descriptor for debugging output. */
398 FILE *debug_file;
400 /* Current number of elements in use in depth below. */
401 unsigned int depth_in_use;
403 /* Maximum number of elements that can be used before resizing. */
404 unsigned int depth_max;
406 /* Each element of this array is an index in by_depth where the given
407 depth starts. This structure is indexed by that given depth we
408 are interested in. */
409 unsigned int *depth;
411 /* Current number of elements in use in by_depth below. */
412 unsigned int by_depth_in_use;
414 /* Maximum number of elements that can be used before resizing. */
415 unsigned int by_depth_max;
417 /* Each element of this array is a pointer to a page_entry, all
418 page_entries can be found in here by increasing depth.
419 index_by_depth in the page_entry is the index into this data
420 structure where that page_entry can be found. This is used to
421 speed up finding all page_entries at a particular depth. */
422 page_entry **by_depth;
424 /* Each element is a pointer to the saved in_use_p bits, if any,
425 zero otherwise. We allocate them all together, to enable a
426 better runtime data access pattern. */
427 unsigned long **save_in_use;
429 #ifdef ENABLE_GC_ALWAYS_COLLECT
430 /* List of free objects to be verified as actually free on the
431 next collection. */
432 struct free_object *free_object_list;
433 #endif
435 struct
437 /* Total GC-allocated memory. */
438 unsigned long long total_allocated;
439 /* Total overhead for GC-allocated memory. */
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
444 sizes. */
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];
460 } stats;
461 } G;
463 /* The size in bytes required to maintain a bitmap for the objects
464 on a page-entry. */
465 #define BITMAP_SIZE(Num_objects) \
466 (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
468 /* Allocate pages in chunks of this size, to throttle calls to memory
469 allocation routines. The first page is used, the rest go onto the
470 free list. This cannot be larger than HOST_BITS_PER_INT for the
471 in_use bitmask for page_group. Hosts that need a different value
472 can override this by defining GGC_QUIRE_SIZE explicitly. */
473 #ifndef GGC_QUIRE_SIZE
474 # ifdef USING_MMAP
475 # define GGC_QUIRE_SIZE 512 /* 2MB for 4K pages */
476 # else
477 # define GGC_QUIRE_SIZE 16
478 # endif
479 #endif
481 /* Initial guess as to how many page table entries we might need. */
482 #define INITIAL_PTE_COUNT 128
484 static int ggc_allocated_p (const void *);
485 static page_entry *lookup_page_table_entry (const void *);
486 static void set_page_table_entry (void *, page_entry *);
487 #ifdef USING_MMAP
488 static char *alloc_anon (char *, size_t, bool check);
489 #endif
490 #ifdef USING_MALLOC_PAGE_GROUPS
491 static size_t page_group_index (char *, char *);
492 static void set_page_group_in_use (page_group *, char *);
493 static void clear_page_group_in_use (page_group *, char *);
494 #endif
495 static struct page_entry * alloc_page (unsigned);
496 static void free_page (struct page_entry *);
497 static void release_pages (void);
498 static void clear_marks (void);
499 static void sweep_pages (void);
500 static void ggc_recalculate_in_use_p (page_entry *);
501 static void compute_inverse (unsigned);
502 static inline void adjust_depth (void);
503 static void move_ptes_to_front (int, int);
505 void debug_print_page_list (int);
506 static void push_depth (unsigned int);
507 static void push_by_depth (page_entry *, unsigned long *);
509 /* Push an entry onto G.depth. */
511 inline static void
512 push_depth (unsigned int i)
514 if (G.depth_in_use >= G.depth_max)
516 G.depth_max *= 2;
517 G.depth = XRESIZEVEC (unsigned int, G.depth, G.depth_max);
519 G.depth[G.depth_in_use++] = i;
522 /* Push an entry onto G.by_depth and G.save_in_use. */
524 inline static void
525 push_by_depth (page_entry *p, unsigned long *s)
527 if (G.by_depth_in_use >= G.by_depth_max)
529 G.by_depth_max *= 2;
530 G.by_depth = XRESIZEVEC (page_entry *, G.by_depth, G.by_depth_max);
531 G.save_in_use = XRESIZEVEC (unsigned long *, G.save_in_use,
532 G.by_depth_max);
534 G.by_depth[G.by_depth_in_use] = p;
535 G.save_in_use[G.by_depth_in_use++] = s;
538 #if (GCC_VERSION < 3001)
539 #define prefetch(X) ((void) X)
540 #else
541 #define prefetch(X) __builtin_prefetch (X)
542 #endif
544 #define save_in_use_p_i(__i) \
545 (G.save_in_use[__i])
546 #define save_in_use_p(__p) \
547 (save_in_use_p_i (__p->index_by_depth))
549 /* Returns nonzero if P was allocated in GC'able memory. */
551 static inline int
552 ggc_allocated_p (const void *p)
554 page_entry ***base;
555 size_t L1, L2;
557 #if HOST_BITS_PER_PTR <= 32
558 base = &G.lookup[0];
559 #else
560 page_table table = G.lookup;
561 uintptr_t high_bits = (uintptr_t) p & ~ (uintptr_t) 0xffffffff;
562 while (1)
564 if (table == NULL)
565 return 0;
566 if (table->high_bits == high_bits)
567 break;
568 table = table->next;
570 base = &table->table[0];
571 #endif
573 /* Extract the level 1 and 2 indices. */
574 L1 = LOOKUP_L1 (p);
575 L2 = LOOKUP_L2 (p);
577 return base[L1] && base[L1][L2];
580 /* Traverse the page table and find the entry for a page.
581 Die (probably) if the object wasn't allocated via GC. */
583 static inline page_entry *
584 lookup_page_table_entry (const void *p)
586 page_entry ***base;
587 size_t L1, L2;
589 #if HOST_BITS_PER_PTR <= 32
590 base = &G.lookup[0];
591 #else
592 page_table table = G.lookup;
593 uintptr_t high_bits = (uintptr_t) p & ~ (uintptr_t) 0xffffffff;
594 while (table->high_bits != high_bits)
595 table = table->next;
596 base = &table->table[0];
597 #endif
599 /* Extract the level 1 and 2 indices. */
600 L1 = LOOKUP_L1 (p);
601 L2 = LOOKUP_L2 (p);
603 return base[L1][L2];
606 /* Set the page table entry for a page. */
608 static void
609 set_page_table_entry (void *p, page_entry *entry)
611 page_entry ***base;
612 size_t L1, L2;
614 #if HOST_BITS_PER_PTR <= 32
615 base = &G.lookup[0];
616 #else
617 page_table table;
618 uintptr_t high_bits = (uintptr_t) p & ~ (uintptr_t) 0xffffffff;
619 for (table = G.lookup; table; table = table->next)
620 if (table->high_bits == high_bits)
621 goto found;
623 /* Not found -- allocate a new table. */
624 table = XCNEW (struct page_table_chain);
625 table->next = G.lookup;
626 table->high_bits = high_bits;
627 G.lookup = table;
628 found:
629 base = &table->table[0];
630 #endif
632 /* Extract the level 1 and 2 indices. */
633 L1 = LOOKUP_L1 (p);
634 L2 = LOOKUP_L2 (p);
636 if (base[L1] == NULL)
637 base[L1] = XCNEWVEC (page_entry *, PAGE_L2_SIZE);
639 base[L1][L2] = entry;
642 /* Prints the page-entry for object size ORDER, for debugging. */
644 DEBUG_FUNCTION void
645 debug_print_page_list (int order)
647 page_entry *p;
648 printf ("Head=%p, Tail=%p:\n", (void *) G.pages[order],
649 (void *) G.page_tails[order]);
650 p = G.pages[order];
651 while (p != NULL)
653 printf ("%p(%1d|%3d) -> ", (void *) p, p->context_depth,
654 p->num_free_objects);
655 p = p->next;
657 printf ("NULL\n");
658 fflush (stdout);
661 #ifdef USING_MMAP
662 /* Allocate SIZE bytes of anonymous memory, preferably near PREF,
663 (if non-null). The ifdef structure here is intended to cause a
664 compile error unless exactly one of the HAVE_* is defined. */
666 static inline char *
667 alloc_anon (char *pref ATTRIBUTE_UNUSED, size_t size, bool check)
669 #ifdef HAVE_MMAP_ANON
670 char *page = (char *) mmap (pref, size, PROT_READ | PROT_WRITE,
671 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
672 #endif
673 #ifdef HAVE_MMAP_DEV_ZERO
674 char *page = (char *) mmap (pref, size, PROT_READ | PROT_WRITE,
675 MAP_PRIVATE, G.dev_zero_fd, 0);
676 #endif
678 if (page == (char *) MAP_FAILED)
680 if (!check)
681 return NULL;
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_internal_alloc. Discard the
691 handle to avoid handle leak. */
692 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (page, size));
694 return page;
696 #endif
697 #ifdef USING_MALLOC_PAGE_GROUPS
698 /* Compute the index for this page into the page group. */
700 static inline size_t
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. */
708 static inline void
709 set_page_group_in_use (page_group *group, char *page)
711 group->in_use |= 1 << page_group_index (group->allocation, page);
714 static inline void
715 clear_page_group_in_use (page_group *group, char *page)
717 group->in_use &= ~(1 << page_group_index (group->allocation, page));
719 #endif
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;
729 char *page;
730 size_t num_objects;
731 size_t bitmap_size;
732 size_t page_entry_size;
733 size_t entry_size;
734 #ifdef USING_MALLOC_PAGE_GROUPS
735 page_group *group;
736 #endif
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;
744 entry_size = PAGE_ALIGN (entry_size);
746 entry = NULL;
747 page = NULL;
749 /* Check the list of free pages for one we can use. */
750 for (pp = &G.free_pages, p = *pp; p; pp = &p->next, p = *pp)
751 if (p->bytes == entry_size)
752 break;
754 if (p != NULL)
756 if (p->discarded)
757 G.bytes_mapped += p->bytes;
758 p->discarded = false;
760 /* Recycle the allocated memory from this page ... */
761 *pp = p->next;
762 page = p->page;
764 #ifdef USING_MALLOC_PAGE_GROUPS
765 group = p->group;
766 #endif
768 /* ... and, if possible, the page entry itself. */
769 if (p->order == order)
771 entry = p;
772 memset (entry, 0, page_entry_size);
774 else
775 free (p);
777 #ifdef USING_MMAP
778 else if (entry_size == G.pagesize)
780 /* We want just one page. Allocate a bunch of them and put the
781 extras on the freelist. (Can only do this optimization with
782 mmap for backing store.) */
783 struct page_entry *e, *f = G.free_pages;
784 int i, entries = GGC_QUIRE_SIZE;
786 page = alloc_anon (NULL, G.pagesize * GGC_QUIRE_SIZE, false);
787 if (page == NULL)
789 page = alloc_anon(NULL, G.pagesize, true);
790 entries = 1;
793 /* This loop counts down so that the chain will be in ascending
794 memory order. */
795 for (i = entries - 1; i >= 1; i--)
797 e = XCNEWVAR (struct page_entry, page_entry_size);
798 e->order = order;
799 e->bytes = G.pagesize;
800 e->page = page + (i << G.lg_pagesize);
801 e->next = f;
802 f = e;
805 G.free_pages = f;
807 else
808 page = alloc_anon (NULL, entry_size, true);
809 #endif
810 #ifdef USING_MALLOC_PAGE_GROUPS
811 else
813 /* Allocate a large block of memory and serve out the aligned
814 pages therein. This results in much less memory wastage
815 than the traditional implementation of valloc. */
817 char *allocation, *a, *enda;
818 size_t alloc_size, head_slop, tail_slop;
819 int multiple_pages = (entry_size == G.pagesize);
821 if (multiple_pages)
822 alloc_size = GGC_QUIRE_SIZE * G.pagesize;
823 else
824 alloc_size = entry_size + G.pagesize - 1;
825 allocation = XNEWVEC (char, alloc_size);
827 page = (char *) (((uintptr_t) allocation + G.pagesize - 1) & -G.pagesize);
828 head_slop = page - allocation;
829 if (multiple_pages)
830 tail_slop = ((size_t) allocation + alloc_size) & (G.pagesize - 1);
831 else
832 tail_slop = alloc_size - entry_size - head_slop;
833 enda = allocation + alloc_size - tail_slop;
835 /* We allocated N pages, which are likely not aligned, leaving
836 us with N-1 usable pages. We plan to place the page_group
837 structure somewhere in the slop. */
838 if (head_slop >= sizeof (page_group))
839 group = (page_group *)page - 1;
840 else
842 /* We magically got an aligned allocation. Too bad, we have
843 to waste a page anyway. */
844 if (tail_slop == 0)
846 enda -= G.pagesize;
847 tail_slop += G.pagesize;
849 gcc_assert (tail_slop >= sizeof (page_group));
850 group = (page_group *)enda;
851 tail_slop -= sizeof (page_group);
854 /* Remember that we allocated this memory. */
855 group->next = G.page_groups;
856 group->allocation = allocation;
857 group->alloc_size = alloc_size;
858 group->in_use = 0;
859 G.page_groups = group;
860 G.bytes_mapped += alloc_size;
862 /* If we allocated multiple pages, put the rest on the free list. */
863 if (multiple_pages)
865 struct page_entry *e, *f = G.free_pages;
866 for (a = enda - G.pagesize; a != page; a -= G.pagesize)
868 e = XCNEWVAR (struct page_entry, page_entry_size);
869 e->order = order;
870 e->bytes = G.pagesize;
871 e->page = a;
872 e->group = group;
873 e->next = f;
874 f = e;
876 G.free_pages = f;
879 #endif
881 if (entry == NULL)
882 entry = XCNEWVAR (struct page_entry, page_entry_size);
884 entry->bytes = entry_size;
885 entry->page = page;
886 entry->context_depth = G.context_depth;
887 entry->order = order;
888 entry->num_free_objects = num_objects;
889 entry->next_bit_hint = 1;
891 G.context_depth_allocations |= (unsigned long)1 << G.context_depth;
893 #ifdef USING_MALLOC_PAGE_GROUPS
894 entry->group = group;
895 set_page_group_in_use (group, page);
896 #endif
898 /* Set the one-past-the-end in-use bit. This acts as a sentry as we
899 increment the hint. */
900 entry->in_use_p[num_objects / HOST_BITS_PER_LONG]
901 = (unsigned long) 1 << (num_objects % HOST_BITS_PER_LONG);
903 set_page_table_entry (page, entry);
905 if (GGC_DEBUG_LEVEL >= 2)
906 fprintf (G.debug_file,
907 "Allocating page at %p, object size=%lu, data %p-%p\n",
908 (void *) entry, (unsigned long) OBJECT_SIZE (order), page,
909 page + entry_size - 1);
911 return entry;
914 /* Adjust the size of G.depth so that no index greater than the one
915 used by the top of the G.by_depth is used. */
917 static inline void
918 adjust_depth (void)
920 page_entry *top;
922 if (G.by_depth_in_use)
924 top = G.by_depth[G.by_depth_in_use-1];
926 /* Peel back indices in depth that index into by_depth, so that
927 as new elements are added to by_depth, we note the indices
928 of those elements, if they are for new context depths. */
929 while (G.depth_in_use > (size_t)top->context_depth+1)
930 --G.depth_in_use;
934 /* For a page that is no longer needed, put it on the free page list. */
936 static void
937 free_page (page_entry *entry)
939 if (GGC_DEBUG_LEVEL >= 2)
940 fprintf (G.debug_file,
941 "Deallocating page at %p, data %p-%p\n", (void *) entry,
942 entry->page, entry->page + entry->bytes - 1);
944 /* Mark the page as inaccessible. Discard the handle to avoid handle
945 leak. */
946 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (entry->page, entry->bytes));
948 set_page_table_entry (entry->page, NULL);
950 #ifdef USING_MALLOC_PAGE_GROUPS
951 clear_page_group_in_use (entry->group, entry->page);
952 #endif
954 if (G.by_depth_in_use > 1)
956 page_entry *top = G.by_depth[G.by_depth_in_use-1];
957 int i = entry->index_by_depth;
959 /* We cannot free a page from a context deeper than the current
960 one. */
961 gcc_assert (entry->context_depth == top->context_depth);
963 /* Put top element into freed slot. */
964 G.by_depth[i] = top;
965 G.save_in_use[i] = G.save_in_use[G.by_depth_in_use-1];
966 top->index_by_depth = i;
968 --G.by_depth_in_use;
970 adjust_depth ();
972 entry->next = G.free_pages;
973 G.free_pages = entry;
976 /* Release the free page cache to the system. */
978 static void
979 release_pages (void)
981 #ifdef USING_MADVISE
982 page_entry *p, *start_p;
983 char *start;
984 size_t len;
985 size_t mapped_len;
986 page_entry *next, *prev, *newprev;
987 size_t free_unit = (GGC_QUIRE_SIZE/2) * G.pagesize;
989 /* First free larger continuous areas to the OS.
990 This allows other allocators to grab these areas if needed.
991 This is only done on larger chunks to avoid fragmentation.
992 This does not always work because the free_pages list is only
993 approximately sorted. */
995 p = G.free_pages;
996 prev = NULL;
997 while (p)
999 start = p->page;
1000 start_p = p;
1001 len = 0;
1002 mapped_len = 0;
1003 newprev = prev;
1004 while (p && p->page == start + len)
1006 len += p->bytes;
1007 if (!p->discarded)
1008 mapped_len += p->bytes;
1009 newprev = p;
1010 p = p->next;
1012 if (len >= free_unit)
1014 while (start_p != p)
1016 next = start_p->next;
1017 free (start_p);
1018 start_p = next;
1020 munmap (start, len);
1021 if (prev)
1022 prev->next = p;
1023 else
1024 G.free_pages = p;
1025 G.bytes_mapped -= mapped_len;
1026 continue;
1028 prev = newprev;
1031 /* Now give back the fragmented pages to the OS, but keep the address
1032 space to reuse it next time. */
1034 for (p = G.free_pages; p; )
1036 if (p->discarded)
1038 p = p->next;
1039 continue;
1041 start = p->page;
1042 len = p->bytes;
1043 start_p = p;
1044 p = p->next;
1045 while (p && p->page == start + len)
1047 len += p->bytes;
1048 p = p->next;
1050 /* Give the page back to the kernel, but don't free the mapping.
1051 This avoids fragmentation in the virtual memory map of the
1052 process. Next time we can reuse it by just touching it. */
1053 madvise (start, len, MADV_DONTNEED);
1054 /* Don't count those pages as mapped to not touch the garbage collector
1055 unnecessarily. */
1056 G.bytes_mapped -= len;
1057 while (start_p != p)
1059 start_p->discarded = true;
1060 start_p = start_p->next;
1063 #endif
1064 #if defined(USING_MMAP) && !defined(USING_MADVISE)
1065 page_entry *p, *next;
1066 char *start;
1067 size_t len;
1069 /* Gather up adjacent pages so they are unmapped together. */
1070 p = G.free_pages;
1072 while (p)
1074 start = p->page;
1075 next = p->next;
1076 len = p->bytes;
1077 free (p);
1078 p = next;
1080 while (p && p->page == start + len)
1082 next = p->next;
1083 len += p->bytes;
1084 free (p);
1085 p = next;
1088 munmap (start, len);
1089 G.bytes_mapped -= len;
1092 G.free_pages = NULL;
1093 #endif
1094 #ifdef USING_MALLOC_PAGE_GROUPS
1095 page_entry **pp, *p;
1096 page_group **gp, *g;
1098 /* Remove all pages from free page groups from the list. */
1099 pp = &G.free_pages;
1100 while ((p = *pp) != NULL)
1101 if (p->group->in_use == 0)
1103 *pp = p->next;
1104 free (p);
1106 else
1107 pp = &p->next;
1109 /* Remove all free page groups, and release the storage. */
1110 gp = &G.page_groups;
1111 while ((g = *gp) != NULL)
1112 if (g->in_use == 0)
1114 *gp = g->next;
1115 G.bytes_mapped -= g->alloc_size;
1116 free (g->allocation);
1118 else
1119 gp = &g->next;
1120 #endif
1123 /* This table provides a fast way to determine ceil(log_2(size)) for
1124 allocation requests. The minimum allocation size is eight bytes. */
1125 #define NUM_SIZE_LOOKUP 512
1126 static unsigned char size_lookup[NUM_SIZE_LOOKUP] =
1128 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
1129 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
1130 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1131 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
1132 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1133 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1134 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1135 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
1136 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1137 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1138 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1139 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1140 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1141 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1142 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1143 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
1144 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1145 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1146 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1147 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1148 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1149 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1150 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1151 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1152 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1153 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1154 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1155 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1156 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1157 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1158 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
1159 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
1162 /* For a given size of memory requested for allocation, return the
1163 actual size that is going to be allocated, as well as the size
1164 order. */
1166 static void
1167 ggc_round_alloc_size_1 (size_t requested_size,
1168 size_t *size_order,
1169 size_t *alloced_size)
1171 size_t order, object_size;
1173 if (requested_size < NUM_SIZE_LOOKUP)
1175 order = size_lookup[requested_size];
1176 object_size = OBJECT_SIZE (order);
1178 else
1180 order = 10;
1181 while (requested_size > (object_size = OBJECT_SIZE (order)))
1182 order++;
1185 if (size_order)
1186 *size_order = order;
1187 if (alloced_size)
1188 *alloced_size = object_size;
1191 /* For a given size of memory requested for allocation, return the
1192 actual size that is going to be allocated. */
1194 size_t
1195 ggc_round_alloc_size (size_t requested_size)
1197 size_t size = 0;
1199 ggc_round_alloc_size_1 (requested_size, NULL, &size);
1200 return size;
1203 /* Typed allocation function. Does nothing special in this collector. */
1205 void *
1206 ggc_alloc_typed_stat (enum gt_types_enum type ATTRIBUTE_UNUSED, size_t size
1207 MEM_STAT_DECL)
1209 return ggc_internal_alloc_stat (size PASS_MEM_STAT);
1212 /* Allocate a chunk of memory of SIZE bytes. Its contents are undefined. */
1214 void *
1215 ggc_internal_alloc_stat (size_t size MEM_STAT_DECL)
1217 size_t order, word, bit, object_offset, object_size;
1218 struct page_entry *entry;
1219 void *result;
1221 ggc_round_alloc_size_1 (size, &order, &object_size);
1223 /* If there are non-full pages for this size allocation, they are at
1224 the head of the list. */
1225 entry = G.pages[order];
1227 /* If there is no page for this object size, or all pages in this
1228 context are full, allocate a new page. */
1229 if (entry == NULL || entry->num_free_objects == 0)
1231 struct page_entry *new_entry;
1232 new_entry = alloc_page (order);
1234 new_entry->index_by_depth = G.by_depth_in_use;
1235 push_by_depth (new_entry, 0);
1237 /* We can skip context depths, if we do, make sure we go all the
1238 way to the new depth. */
1239 while (new_entry->context_depth >= G.depth_in_use)
1240 push_depth (G.by_depth_in_use-1);
1242 /* If this is the only entry, it's also the tail. If it is not
1243 the only entry, then we must update the PREV pointer of the
1244 ENTRY (G.pages[order]) to point to our new page entry. */
1245 if (entry == NULL)
1246 G.page_tails[order] = new_entry;
1247 else
1248 entry->prev = new_entry;
1250 /* Put new pages at the head of the page list. By definition the
1251 entry at the head of the list always has a NULL pointer. */
1252 new_entry->next = entry;
1253 new_entry->prev = NULL;
1254 entry = new_entry;
1255 G.pages[order] = new_entry;
1257 /* For a new page, we know the word and bit positions (in the
1258 in_use bitmap) of the first available object -- they're zero. */
1259 new_entry->next_bit_hint = 1;
1260 word = 0;
1261 bit = 0;
1262 object_offset = 0;
1264 else
1266 /* First try to use the hint left from the previous allocation
1267 to locate a clear bit in the in-use bitmap. We've made sure
1268 that the one-past-the-end bit is always set, so if the hint
1269 has run over, this test will fail. */
1270 unsigned hint = entry->next_bit_hint;
1271 word = hint / HOST_BITS_PER_LONG;
1272 bit = hint % HOST_BITS_PER_LONG;
1274 /* If the hint didn't work, scan the bitmap from the beginning. */
1275 if ((entry->in_use_p[word] >> bit) & 1)
1277 word = bit = 0;
1278 while (~entry->in_use_p[word] == 0)
1279 ++word;
1281 #if GCC_VERSION >= 3004
1282 bit = __builtin_ctzl (~entry->in_use_p[word]);
1283 #else
1284 while ((entry->in_use_p[word] >> bit) & 1)
1285 ++bit;
1286 #endif
1288 hint = word * HOST_BITS_PER_LONG + bit;
1291 /* Next time, try the next bit. */
1292 entry->next_bit_hint = hint + 1;
1294 object_offset = hint * object_size;
1297 /* Set the in-use bit. */
1298 entry->in_use_p[word] |= ((unsigned long) 1 << bit);
1300 /* Keep a running total of the number of free objects. If this page
1301 fills up, we may have to move it to the end of the list if the
1302 next page isn't full. If the next page is full, all subsequent
1303 pages are full, so there's no need to move it. */
1304 if (--entry->num_free_objects == 0
1305 && entry->next != NULL
1306 && entry->next->num_free_objects > 0)
1308 /* We have a new head for the list. */
1309 G.pages[order] = entry->next;
1311 /* We are moving ENTRY to the end of the page table list.
1312 The new page at the head of the list will have NULL in
1313 its PREV field and ENTRY will have NULL in its NEXT field. */
1314 entry->next->prev = NULL;
1315 entry->next = NULL;
1317 /* Append ENTRY to the tail of the list. */
1318 entry->prev = G.page_tails[order];
1319 G.page_tails[order]->next = entry;
1320 G.page_tails[order] = entry;
1323 /* Calculate the object's address. */
1324 result = entry->page + object_offset;
1325 if (GATHER_STATISTICS)
1326 ggc_record_overhead (OBJECT_SIZE (order), OBJECT_SIZE (order) - size,
1327 result FINAL_PASS_MEM_STAT);
1329 #ifdef ENABLE_GC_CHECKING
1330 /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
1331 exact same semantics in presence of memory bugs, regardless of
1332 ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
1333 handle to avoid handle leak. */
1334 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, object_size));
1336 /* `Poison' the entire allocated object, including any padding at
1337 the end. */
1338 memset (result, 0xaf, object_size);
1340 /* Make the bytes after the end of the object unaccessible. Discard the
1341 handle to avoid handle leak. */
1342 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *) result + size,
1343 object_size - size));
1344 #endif
1346 /* Tell Valgrind that the memory is there, but its content isn't
1347 defined. The bytes at the end of the object are still marked
1348 unaccessible. */
1349 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, size));
1351 /* Keep track of how many bytes are being allocated. This
1352 information is used in deciding when to collect. */
1353 G.allocated += object_size;
1355 /* For timevar statistics. */
1356 timevar_ggc_mem_total += object_size;
1358 if (GATHER_STATISTICS)
1360 size_t overhead = object_size - size;
1362 G.stats.total_overhead += overhead;
1363 G.stats.total_allocated += object_size;
1364 G.stats.total_overhead_per_order[order] += overhead;
1365 G.stats.total_allocated_per_order[order] += object_size;
1367 if (size <= 32)
1369 G.stats.total_overhead_under32 += overhead;
1370 G.stats.total_allocated_under32 += object_size;
1372 if (size <= 64)
1374 G.stats.total_overhead_under64 += overhead;
1375 G.stats.total_allocated_under64 += object_size;
1377 if (size <= 128)
1379 G.stats.total_overhead_under128 += overhead;
1380 G.stats.total_allocated_under128 += object_size;
1384 if (GGC_DEBUG_LEVEL >= 3)
1385 fprintf (G.debug_file,
1386 "Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
1387 (unsigned long) size, (unsigned long) object_size, result,
1388 (void *) entry);
1390 return result;
1393 /* Mark function for strings. */
1395 void
1396 gt_ggc_m_S (const void *p)
1398 page_entry *entry;
1399 unsigned bit, word;
1400 unsigned long mask;
1401 unsigned long offset;
1403 if (!p || !ggc_allocated_p (p))
1404 return;
1406 /* Look up the page on which the object is alloced. . */
1407 entry = lookup_page_table_entry (p);
1408 gcc_assert (entry);
1410 /* Calculate the index of the object on the page; this is its bit
1411 position in the in_use_p bitmap. Note that because a char* might
1412 point to the middle of an object, we need special code here to
1413 make sure P points to the start of an object. */
1414 offset = ((const char *) p - entry->page) % object_size_table[entry->order];
1415 if (offset)
1417 /* Here we've seen a char* which does not point to the beginning
1418 of an allocated object. We assume it points to the middle of
1419 a STRING_CST. */
1420 gcc_assert (offset == offsetof (struct tree_string, str));
1421 p = ((const char *) p) - offset;
1422 gt_ggc_mx_lang_tree_node (CONST_CAST (void *, p));
1423 return;
1426 bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
1427 word = bit / HOST_BITS_PER_LONG;
1428 mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
1430 /* If the bit was previously set, skip it. */
1431 if (entry->in_use_p[word] & mask)
1432 return;
1434 /* Otherwise set it, and decrement the free object count. */
1435 entry->in_use_p[word] |= mask;
1436 entry->num_free_objects -= 1;
1438 if (GGC_DEBUG_LEVEL >= 4)
1439 fprintf (G.debug_file, "Marking %p\n", p);
1441 return;
1445 /* User-callable entry points for marking string X. */
1447 void
1448 gt_ggc_mx (const char *& x)
1450 gt_ggc_m_S (x);
1453 void
1454 gt_ggc_mx (unsigned char *& x)
1456 gt_ggc_m_S (x);
1459 void
1460 gt_ggc_mx (unsigned char& x ATTRIBUTE_UNUSED)
1464 /* If P is not marked, marks it and return false. Otherwise return true.
1465 P must have been allocated by the GC allocator; it mustn't point to
1466 static objects, stack variables, or memory allocated with malloc. */
1469 ggc_set_mark (const void *p)
1471 page_entry *entry;
1472 unsigned bit, word;
1473 unsigned long mask;
1475 /* Look up the page on which the object is alloced. If the object
1476 wasn't allocated by the collector, we'll probably die. */
1477 entry = lookup_page_table_entry (p);
1478 gcc_assert (entry);
1480 /* Calculate the index of the object on the page; this is its bit
1481 position in the in_use_p bitmap. */
1482 bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
1483 word = bit / HOST_BITS_PER_LONG;
1484 mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
1486 /* If the bit was previously set, skip it. */
1487 if (entry->in_use_p[word] & mask)
1488 return 1;
1490 /* Otherwise set it, and decrement the free object count. */
1491 entry->in_use_p[word] |= mask;
1492 entry->num_free_objects -= 1;
1494 if (GGC_DEBUG_LEVEL >= 4)
1495 fprintf (G.debug_file, "Marking %p\n", p);
1497 return 0;
1500 /* Return 1 if P has been marked, zero otherwise.
1501 P must have been allocated by the GC allocator; it mustn't point to
1502 static objects, stack variables, or memory allocated with malloc. */
1505 ggc_marked_p (const void *p)
1507 page_entry *entry;
1508 unsigned bit, word;
1509 unsigned long mask;
1511 /* Look up the page on which the object is alloced. If the object
1512 wasn't allocated by the collector, we'll probably die. */
1513 entry = lookup_page_table_entry (p);
1514 gcc_assert (entry);
1516 /* Calculate the index of the object on the page; this is its bit
1517 position in the in_use_p bitmap. */
1518 bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
1519 word = bit / HOST_BITS_PER_LONG;
1520 mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
1522 return (entry->in_use_p[word] & mask) != 0;
1525 /* Return the size of the gc-able object P. */
1527 size_t
1528 ggc_get_size (const void *p)
1530 page_entry *pe = lookup_page_table_entry (p);
1531 return OBJECT_SIZE (pe->order);
1534 /* Release the memory for object P. */
1536 void
1537 ggc_free (void *p)
1539 page_entry *pe = lookup_page_table_entry (p);
1540 size_t order = pe->order;
1541 size_t size = OBJECT_SIZE (order);
1543 if (GATHER_STATISTICS)
1544 ggc_free_overhead (p);
1546 if (GGC_DEBUG_LEVEL >= 3)
1547 fprintf (G.debug_file,
1548 "Freeing object, actual size=%lu, at %p on %p\n",
1549 (unsigned long) size, p, (void *) pe);
1551 #ifdef ENABLE_GC_CHECKING
1552 /* Poison the data, to indicate the data is garbage. */
1553 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (p, size));
1554 memset (p, 0xa5, size);
1555 #endif
1556 /* Let valgrind know the object is free. */
1557 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (p, size));
1559 #ifdef ENABLE_GC_ALWAYS_COLLECT
1560 /* In the completely-anal-checking mode, we do *not* immediately free
1561 the data, but instead verify that the data is *actually* not
1562 reachable the next time we collect. */
1564 struct free_object *fo = XNEW (struct free_object);
1565 fo->object = p;
1566 fo->next = G.free_object_list;
1567 G.free_object_list = fo;
1569 #else
1571 unsigned int bit_offset, word, bit;
1573 G.allocated -= size;
1575 /* Mark the object not-in-use. */
1576 bit_offset = OFFSET_TO_BIT (((const char *) p) - pe->page, order);
1577 word = bit_offset / HOST_BITS_PER_LONG;
1578 bit = bit_offset % HOST_BITS_PER_LONG;
1579 pe->in_use_p[word] &= ~(1UL << bit);
1581 if (pe->num_free_objects++ == 0)
1583 page_entry *p, *q;
1585 /* If the page is completely full, then it's supposed to
1586 be after all pages that aren't. Since we've freed one
1587 object from a page that was full, we need to move the
1588 page to the head of the list.
1590 PE is the node we want to move. Q is the previous node
1591 and P is the next node in the list. */
1592 q = pe->prev;
1593 if (q && q->num_free_objects == 0)
1595 p = pe->next;
1597 q->next = p;
1599 /* If PE was at the end of the list, then Q becomes the
1600 new end of the list. If PE was not the end of the
1601 list, then we need to update the PREV field for P. */
1602 if (!p)
1603 G.page_tails[order] = q;
1604 else
1605 p->prev = q;
1607 /* Move PE to the head of the list. */
1608 pe->next = G.pages[order];
1609 pe->prev = NULL;
1610 G.pages[order]->prev = pe;
1611 G.pages[order] = pe;
1614 /* Reset the hint bit to point to the only free object. */
1615 pe->next_bit_hint = bit_offset;
1618 #endif
1621 /* Subroutine of init_ggc which computes the pair of numbers used to
1622 perform division by OBJECT_SIZE (order) and fills in inverse_table[].
1624 This algorithm is taken from Granlund and Montgomery's paper
1625 "Division by Invariant Integers using Multiplication"
1626 (Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
1627 constants). */
1629 static void
1630 compute_inverse (unsigned order)
1632 size_t size, inv;
1633 unsigned int e;
1635 size = OBJECT_SIZE (order);
1636 e = 0;
1637 while (size % 2 == 0)
1639 e++;
1640 size >>= 1;
1643 inv = size;
1644 while (inv * size != 1)
1645 inv = inv * (2 - inv*size);
1647 DIV_MULT (order) = inv;
1648 DIV_SHIFT (order) = e;
1651 /* Initialize the ggc-mmap allocator. */
1652 void
1653 init_ggc (void)
1655 unsigned order;
1657 G.pagesize = getpagesize();
1658 G.lg_pagesize = exact_log2 (G.pagesize);
1660 #ifdef HAVE_MMAP_DEV_ZERO
1661 G.dev_zero_fd = open ("/dev/zero", O_RDONLY);
1662 if (G.dev_zero_fd == -1)
1663 internal_error ("open /dev/zero: %m");
1664 #endif
1666 #if 0
1667 G.debug_file = fopen ("ggc-mmap.debug", "w");
1668 #else
1669 G.debug_file = stdout;
1670 #endif
1672 #ifdef USING_MMAP
1673 /* StunOS has an amazing off-by-one error for the first mmap allocation
1674 after fiddling with RLIMIT_STACK. The result, as hard as it is to
1675 believe, is an unaligned page allocation, which would cause us to
1676 hork badly if we tried to use it. */
1678 char *p = alloc_anon (NULL, G.pagesize, true);
1679 struct page_entry *e;
1680 if ((uintptr_t)p & (G.pagesize - 1))
1682 /* How losing. Discard this one and try another. If we still
1683 can't get something useful, give up. */
1685 p = alloc_anon (NULL, G.pagesize, true);
1686 gcc_assert (!((uintptr_t)p & (G.pagesize - 1)));
1689 /* We have a good page, might as well hold onto it... */
1690 e = XCNEW (struct page_entry);
1691 e->bytes = G.pagesize;
1692 e->page = p;
1693 e->next = G.free_pages;
1694 G.free_pages = e;
1696 #endif
1698 /* Initialize the object size table. */
1699 for (order = 0; order < HOST_BITS_PER_PTR; ++order)
1700 object_size_table[order] = (size_t) 1 << order;
1701 for (order = HOST_BITS_PER_PTR; order < NUM_ORDERS; ++order)
1703 size_t s = extra_order_size_table[order - HOST_BITS_PER_PTR];
1705 /* If S is not a multiple of the MAX_ALIGNMENT, then round it up
1706 so that we're sure of getting aligned memory. */
1707 s = ROUND_UP (s, MAX_ALIGNMENT);
1708 object_size_table[order] = s;
1711 /* Initialize the objects-per-page and inverse tables. */
1712 for (order = 0; order < NUM_ORDERS; ++order)
1714 objects_per_page_table[order] = G.pagesize / OBJECT_SIZE (order);
1715 if (objects_per_page_table[order] == 0)
1716 objects_per_page_table[order] = 1;
1717 compute_inverse (order);
1720 /* Reset the size_lookup array to put appropriately sized objects in
1721 the special orders. All objects bigger than the previous power
1722 of two, but no greater than the special size, should go in the
1723 new order. */
1724 for (order = HOST_BITS_PER_PTR; order < NUM_ORDERS; ++order)
1726 int o;
1727 int i;
1729 i = OBJECT_SIZE (order);
1730 if (i >= NUM_SIZE_LOOKUP)
1731 continue;
1733 for (o = size_lookup[i]; o == size_lookup [i]; --i)
1734 size_lookup[i] = order;
1737 G.depth_in_use = 0;
1738 G.depth_max = 10;
1739 G.depth = XNEWVEC (unsigned int, G.depth_max);
1741 G.by_depth_in_use = 0;
1742 G.by_depth_max = INITIAL_PTE_COUNT;
1743 G.by_depth = XNEWVEC (page_entry *, G.by_depth_max);
1744 G.save_in_use = XNEWVEC (unsigned long *, G.by_depth_max);
1747 /* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
1748 reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
1750 static void
1751 ggc_recalculate_in_use_p (page_entry *p)
1753 unsigned int i;
1754 size_t num_objects;
1756 /* Because the past-the-end bit in in_use_p is always set, we
1757 pretend there is one additional object. */
1758 num_objects = OBJECTS_IN_PAGE (p) + 1;
1760 /* Reset the free object count. */
1761 p->num_free_objects = num_objects;
1763 /* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
1764 for (i = 0;
1765 i < CEIL (BITMAP_SIZE (num_objects),
1766 sizeof (*p->in_use_p));
1767 ++i)
1769 unsigned long j;
1771 /* Something is in use if it is marked, or if it was in use in a
1772 context further down the context stack. */
1773 p->in_use_p[i] |= save_in_use_p (p)[i];
1775 /* Decrement the free object count for every object allocated. */
1776 for (j = p->in_use_p[i]; j; j >>= 1)
1777 p->num_free_objects -= (j & 1);
1780 gcc_assert (p->num_free_objects < num_objects);
1783 /* Unmark all objects. */
1785 static void
1786 clear_marks (void)
1788 unsigned order;
1790 for (order = 2; order < NUM_ORDERS; order++)
1792 page_entry *p;
1794 for (p = G.pages[order]; p != NULL; p = p->next)
1796 size_t num_objects = OBJECTS_IN_PAGE (p);
1797 size_t bitmap_size = BITMAP_SIZE (num_objects + 1);
1799 /* The data should be page-aligned. */
1800 gcc_assert (!((uintptr_t) p->page & (G.pagesize - 1)));
1802 /* Pages that aren't in the topmost context are not collected;
1803 nevertheless, we need their in-use bit vectors to store GC
1804 marks. So, back them up first. */
1805 if (p->context_depth < G.context_depth)
1807 if (! save_in_use_p (p))
1808 save_in_use_p (p) = XNEWVAR (unsigned long, bitmap_size);
1809 memcpy (save_in_use_p (p), p->in_use_p, bitmap_size);
1812 /* Reset reset the number of free objects and clear the
1813 in-use bits. These will be adjusted by mark_obj. */
1814 p->num_free_objects = num_objects;
1815 memset (p->in_use_p, 0, bitmap_size);
1817 /* Make sure the one-past-the-end bit is always set. */
1818 p->in_use_p[num_objects / HOST_BITS_PER_LONG]
1819 = ((unsigned long) 1 << (num_objects % HOST_BITS_PER_LONG));
1824 /* Free all empty pages. Partially empty pages need no attention
1825 because the `mark' bit doubles as an `unused' bit. */
1827 static void
1828 sweep_pages (void)
1830 unsigned order;
1832 for (order = 2; order < NUM_ORDERS; order++)
1834 /* The last page-entry to consider, regardless of entries
1835 placed at the end of the list. */
1836 page_entry * const last = G.page_tails[order];
1838 size_t num_objects;
1839 size_t live_objects;
1840 page_entry *p, *previous;
1841 int done;
1843 p = G.pages[order];
1844 if (p == NULL)
1845 continue;
1847 previous = NULL;
1850 page_entry *next = p->next;
1852 /* Loop until all entries have been examined. */
1853 done = (p == last);
1855 num_objects = OBJECTS_IN_PAGE (p);
1857 /* Add all live objects on this page to the count of
1858 allocated memory. */
1859 live_objects = num_objects - p->num_free_objects;
1861 G.allocated += OBJECT_SIZE (order) * live_objects;
1863 /* Only objects on pages in the topmost context should get
1864 collected. */
1865 if (p->context_depth < G.context_depth)
1868 /* Remove the page if it's empty. */
1869 else if (live_objects == 0)
1871 /* If P was the first page in the list, then NEXT
1872 becomes the new first page in the list, otherwise
1873 splice P out of the forward pointers. */
1874 if (! previous)
1875 G.pages[order] = next;
1876 else
1877 previous->next = next;
1879 /* Splice P out of the back pointers too. */
1880 if (next)
1881 next->prev = previous;
1883 /* Are we removing the last element? */
1884 if (p == G.page_tails[order])
1885 G.page_tails[order] = previous;
1886 free_page (p);
1887 p = previous;
1890 /* If the page is full, move it to the end. */
1891 else if (p->num_free_objects == 0)
1893 /* Don't move it if it's already at the end. */
1894 if (p != G.page_tails[order])
1896 /* Move p to the end of the list. */
1897 p->next = NULL;
1898 p->prev = G.page_tails[order];
1899 G.page_tails[order]->next = p;
1901 /* Update the tail pointer... */
1902 G.page_tails[order] = p;
1904 /* ... and the head pointer, if necessary. */
1905 if (! previous)
1906 G.pages[order] = next;
1907 else
1908 previous->next = next;
1910 /* And update the backpointer in NEXT if necessary. */
1911 if (next)
1912 next->prev = previous;
1914 p = previous;
1918 /* If we've fallen through to here, it's a page in the
1919 topmost context that is neither full nor empty. Such a
1920 page must precede pages at lesser context depth in the
1921 list, so move it to the head. */
1922 else if (p != G.pages[order])
1924 previous->next = p->next;
1926 /* Update the backchain in the next node if it exists. */
1927 if (p->next)
1928 p->next->prev = previous;
1930 /* Move P to the head of the list. */
1931 p->next = G.pages[order];
1932 p->prev = NULL;
1933 G.pages[order]->prev = p;
1935 /* Update the head pointer. */
1936 G.pages[order] = p;
1938 /* Are we moving the last element? */
1939 if (G.page_tails[order] == p)
1940 G.page_tails[order] = previous;
1941 p = previous;
1944 previous = p;
1945 p = next;
1947 while (! done);
1949 /* Now, restore the in_use_p vectors for any pages from contexts
1950 other than the current one. */
1951 for (p = G.pages[order]; p; p = p->next)
1952 if (p->context_depth != G.context_depth)
1953 ggc_recalculate_in_use_p (p);
1957 #ifdef ENABLE_GC_CHECKING
1958 /* Clobber all free objects. */
1960 static void
1961 poison_pages (void)
1963 unsigned order;
1965 for (order = 2; order < NUM_ORDERS; order++)
1967 size_t size = OBJECT_SIZE (order);
1968 page_entry *p;
1970 for (p = G.pages[order]; p != NULL; p = p->next)
1972 size_t num_objects;
1973 size_t i;
1975 if (p->context_depth != G.context_depth)
1976 /* Since we don't do any collection for pages in pushed
1977 contexts, there's no need to do any poisoning. And
1978 besides, the IN_USE_P array isn't valid until we pop
1979 contexts. */
1980 continue;
1982 num_objects = OBJECTS_IN_PAGE (p);
1983 for (i = 0; i < num_objects; i++)
1985 size_t word, bit;
1986 word = i / HOST_BITS_PER_LONG;
1987 bit = i % HOST_BITS_PER_LONG;
1988 if (((p->in_use_p[word] >> bit) & 1) == 0)
1990 char *object = p->page + i * size;
1992 /* Keep poison-by-write when we expect to use Valgrind,
1993 so the exact same memory semantics is kept, in case
1994 there are memory errors. We override this request
1995 below. */
1996 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (object,
1997 size));
1998 memset (object, 0xa5, size);
2000 /* Drop the handle to avoid handle leak. */
2001 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS (object, size));
2007 #else
2008 #define poison_pages()
2009 #endif
2011 #ifdef ENABLE_GC_ALWAYS_COLLECT
2012 /* Validate that the reportedly free objects actually are. */
2014 static void
2015 validate_free_objects (void)
2017 struct free_object *f, *next, *still_free = NULL;
2019 for (f = G.free_object_list; f ; f = next)
2021 page_entry *pe = lookup_page_table_entry (f->object);
2022 size_t bit, word;
2024 bit = OFFSET_TO_BIT ((char *)f->object - pe->page, pe->order);
2025 word = bit / HOST_BITS_PER_LONG;
2026 bit = bit % HOST_BITS_PER_LONG;
2027 next = f->next;
2029 /* Make certain it isn't visible from any root. Notice that we
2030 do this check before sweep_pages merges save_in_use_p. */
2031 gcc_assert (!(pe->in_use_p[word] & (1UL << bit)));
2033 /* If the object comes from an outer context, then retain the
2034 free_object entry, so that we can verify that the address
2035 isn't live on the stack in some outer context. */
2036 if (pe->context_depth != G.context_depth)
2038 f->next = still_free;
2039 still_free = f;
2041 else
2042 free (f);
2045 G.free_object_list = still_free;
2047 #else
2048 #define validate_free_objects()
2049 #endif
2051 /* Top level mark-and-sweep routine. */
2053 void
2054 ggc_collect (void)
2056 /* Avoid frequent unnecessary work by skipping collection if the
2057 total allocations haven't expanded much since the last
2058 collection. */
2059 float allocated_last_gc =
2060 MAX (G.allocated_last_gc, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE) * 1024);
2062 float min_expand = allocated_last_gc * PARAM_VALUE (GGC_MIN_EXPAND) / 100;
2064 if (G.allocated < allocated_last_gc + min_expand && !ggc_force_collect)
2065 return;
2067 timevar_push (TV_GC);
2068 if (!quiet_flag)
2069 fprintf (stderr, " {GC %luk -> ", (unsigned long) G.allocated / 1024);
2070 if (GGC_DEBUG_LEVEL >= 2)
2071 fprintf (G.debug_file, "BEGIN COLLECTING\n");
2073 /* Zero the total allocated bytes. This will be recalculated in the
2074 sweep phase. */
2075 G.allocated = 0;
2077 /* Release the pages we freed the last time we collected, but didn't
2078 reuse in the interim. */
2079 release_pages ();
2081 /* Indicate that we've seen collections at this context depth. */
2082 G.context_depth_collections = ((unsigned long)1 << (G.context_depth + 1)) - 1;
2084 invoke_plugin_callbacks (PLUGIN_GGC_START, NULL);
2086 clear_marks ();
2087 ggc_mark_roots ();
2089 if (GATHER_STATISTICS)
2090 ggc_prune_overhead_list ();
2092 poison_pages ();
2093 validate_free_objects ();
2094 sweep_pages ();
2096 G.allocated_last_gc = G.allocated;
2098 invoke_plugin_callbacks (PLUGIN_GGC_END, NULL);
2100 timevar_pop (TV_GC);
2102 if (!quiet_flag)
2103 fprintf (stderr, "%luk}", (unsigned long) G.allocated / 1024);
2104 if (GGC_DEBUG_LEVEL >= 2)
2105 fprintf (G.debug_file, "END COLLECTING\n");
2108 /* Print allocation statistics. */
2109 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
2110 ? (x) \
2111 : ((x) < 1024*1024*10 \
2112 ? (x) / 1024 \
2113 : (x) / (1024*1024))))
2114 #define STAT_LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
2116 void
2117 ggc_print_statistics (void)
2119 struct ggc_statistics stats;
2120 unsigned int i;
2121 size_t total_overhead = 0;
2123 /* Clear the statistics. */
2124 memset (&stats, 0, sizeof (stats));
2126 /* Make sure collection will really occur. */
2127 G.allocated_last_gc = 0;
2129 /* Collect and print the statistics common across collectors. */
2130 ggc_print_common_statistics (stderr, &stats);
2132 /* Release free pages so that we will not count the bytes allocated
2133 there as part of the total allocated memory. */
2134 release_pages ();
2136 /* Collect some information about the various sizes of
2137 allocation. */
2138 fprintf (stderr,
2139 "Memory still allocated at the end of the compilation process\n");
2140 fprintf (stderr, "%-5s %10s %10s %10s\n",
2141 "Size", "Allocated", "Used", "Overhead");
2142 for (i = 0; i < NUM_ORDERS; ++i)
2144 page_entry *p;
2145 size_t allocated;
2146 size_t in_use;
2147 size_t overhead;
2149 /* Skip empty entries. */
2150 if (!G.pages[i])
2151 continue;
2153 overhead = allocated = in_use = 0;
2155 /* Figure out the total number of bytes allocated for objects of
2156 this size, and how many of them are actually in use. Also figure
2157 out how much memory the page table is using. */
2158 for (p = G.pages[i]; p; p = p->next)
2160 allocated += p->bytes;
2161 in_use +=
2162 (OBJECTS_IN_PAGE (p) - p->num_free_objects) * OBJECT_SIZE (i);
2164 overhead += (sizeof (page_entry) - sizeof (long)
2165 + BITMAP_SIZE (OBJECTS_IN_PAGE (p) + 1));
2167 fprintf (stderr, "%-5lu %10lu%c %10lu%c %10lu%c\n",
2168 (unsigned long) OBJECT_SIZE (i),
2169 SCALE (allocated), STAT_LABEL (allocated),
2170 SCALE (in_use), STAT_LABEL (in_use),
2171 SCALE (overhead), STAT_LABEL (overhead));
2172 total_overhead += overhead;
2174 fprintf (stderr, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
2175 SCALE (G.bytes_mapped), STAT_LABEL (G.bytes_mapped),
2176 SCALE (G.allocated), STAT_LABEL(G.allocated),
2177 SCALE (total_overhead), STAT_LABEL (total_overhead));
2179 if (GATHER_STATISTICS)
2181 fprintf (stderr, "\nTotal allocations and overheads during the compilation process\n");
2183 fprintf (stderr, "Total Overhead: %10lld\n",
2184 G.stats.total_overhead);
2185 fprintf (stderr, "Total Allocated: %10lld\n",
2186 G.stats.total_allocated);
2188 fprintf (stderr, "Total Overhead under 32B: %10lld\n",
2189 G.stats.total_overhead_under32);
2190 fprintf (stderr, "Total Allocated under 32B: %10lld\n",
2191 G.stats.total_allocated_under32);
2192 fprintf (stderr, "Total Overhead under 64B: %10lld\n",
2193 G.stats.total_overhead_under64);
2194 fprintf (stderr, "Total Allocated under 64B: %10lld\n",
2195 G.stats.total_allocated_under64);
2196 fprintf (stderr, "Total Overhead under 128B: %10lld\n",
2197 G.stats.total_overhead_under128);
2198 fprintf (stderr, "Total Allocated under 128B: %10lld\n",
2199 G.stats.total_allocated_under128);
2201 for (i = 0; i < NUM_ORDERS; i++)
2202 if (G.stats.total_allocated_per_order[i])
2204 fprintf (stderr, "Total Overhead page size %7lu: %10lld\n",
2205 (unsigned long) OBJECT_SIZE (i),
2206 G.stats.total_overhead_per_order[i]);
2207 fprintf (stderr, "Total Allocated page size %7lu: %10lld\n",
2208 (unsigned long) OBJECT_SIZE (i),
2209 G.stats.total_allocated_per_order[i]);
2214 struct ggc_pch_ondisk
2216 unsigned totals[NUM_ORDERS];
2219 struct ggc_pch_data
2221 struct ggc_pch_ondisk d;
2222 uintptr_t base[NUM_ORDERS];
2223 size_t written[NUM_ORDERS];
2226 struct ggc_pch_data *
2227 init_ggc_pch (void)
2229 return XCNEW (struct ggc_pch_data);
2232 void
2233 ggc_pch_count_object (struct ggc_pch_data *d, void *x ATTRIBUTE_UNUSED,
2234 size_t size, bool is_string ATTRIBUTE_UNUSED,
2235 enum gt_types_enum type ATTRIBUTE_UNUSED)
2237 unsigned order;
2239 if (size < NUM_SIZE_LOOKUP)
2240 order = size_lookup[size];
2241 else
2243 order = 10;
2244 while (size > OBJECT_SIZE (order))
2245 order++;
2248 d->d.totals[order]++;
2251 size_t
2252 ggc_pch_total_size (struct ggc_pch_data *d)
2254 size_t a = 0;
2255 unsigned i;
2257 for (i = 0; i < NUM_ORDERS; i++)
2258 a += PAGE_ALIGN (d->d.totals[i] * OBJECT_SIZE (i));
2259 return a;
2262 void
2263 ggc_pch_this_base (struct ggc_pch_data *d, void *base)
2265 uintptr_t a = (uintptr_t) base;
2266 unsigned i;
2268 for (i = 0; i < NUM_ORDERS; i++)
2270 d->base[i] = a;
2271 a += PAGE_ALIGN (d->d.totals[i] * OBJECT_SIZE (i));
2276 char *
2277 ggc_pch_alloc_object (struct ggc_pch_data *d, void *x ATTRIBUTE_UNUSED,
2278 size_t size, bool is_string ATTRIBUTE_UNUSED,
2279 enum gt_types_enum type ATTRIBUTE_UNUSED)
2281 unsigned order;
2282 char *result;
2284 if (size < NUM_SIZE_LOOKUP)
2285 order = size_lookup[size];
2286 else
2288 order = 10;
2289 while (size > OBJECT_SIZE (order))
2290 order++;
2293 result = (char *) d->base[order];
2294 d->base[order] += OBJECT_SIZE (order);
2295 return result;
2298 void
2299 ggc_pch_prepare_write (struct ggc_pch_data *d ATTRIBUTE_UNUSED,
2300 FILE *f ATTRIBUTE_UNUSED)
2302 /* Nothing to do. */
2305 void
2306 ggc_pch_write_object (struct ggc_pch_data *d ATTRIBUTE_UNUSED,
2307 FILE *f, void *x, void *newx ATTRIBUTE_UNUSED,
2308 size_t size, bool is_string ATTRIBUTE_UNUSED)
2310 unsigned order;
2311 static const char emptyBytes[256] = { 0 };
2313 if (size < NUM_SIZE_LOOKUP)
2314 order = size_lookup[size];
2315 else
2317 order = 10;
2318 while (size > OBJECT_SIZE (order))
2319 order++;
2322 if (fwrite (x, size, 1, f) != 1)
2323 fatal_error ("can%'t write PCH file: %m");
2325 /* If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
2326 object out to OBJECT_SIZE(order). This happens for strings. */
2328 if (size != OBJECT_SIZE (order))
2330 unsigned padding = OBJECT_SIZE(order) - size;
2332 /* To speed small writes, we use a nulled-out array that's larger
2333 than most padding requests as the source for our null bytes. This
2334 permits us to do the padding with fwrite() rather than fseek(), and
2335 limits the chance the OS may try to flush any outstanding writes. */
2336 if (padding <= sizeof(emptyBytes))
2338 if (fwrite (emptyBytes, 1, padding, f) != padding)
2339 fatal_error ("can%'t write PCH file");
2341 else
2343 /* Larger than our buffer? Just default to fseek. */
2344 if (fseek (f, padding, SEEK_CUR) != 0)
2345 fatal_error ("can%'t write PCH file");
2349 d->written[order]++;
2350 if (d->written[order] == d->d.totals[order]
2351 && fseek (f, ROUND_UP_VALUE (d->d.totals[order] * OBJECT_SIZE (order),
2352 G.pagesize),
2353 SEEK_CUR) != 0)
2354 fatal_error ("can%'t write PCH file: %m");
2357 void
2358 ggc_pch_finish (struct ggc_pch_data *d, FILE *f)
2360 if (fwrite (&d->d, sizeof (d->d), 1, f) != 1)
2361 fatal_error ("can%'t write PCH file: %m");
2362 free (d);
2365 /* Move the PCH PTE entries just added to the end of by_depth, to the
2366 front. */
2368 static void
2369 move_ptes_to_front (int count_old_page_tables, int count_new_page_tables)
2371 unsigned i;
2373 /* First, we swap the new entries to the front of the varrays. */
2374 page_entry **new_by_depth;
2375 unsigned long **new_save_in_use;
2377 new_by_depth = XNEWVEC (page_entry *, G.by_depth_max);
2378 new_save_in_use = XNEWVEC (unsigned long *, G.by_depth_max);
2380 memcpy (&new_by_depth[0],
2381 &G.by_depth[count_old_page_tables],
2382 count_new_page_tables * sizeof (void *));
2383 memcpy (&new_by_depth[count_new_page_tables],
2384 &G.by_depth[0],
2385 count_old_page_tables * sizeof (void *));
2386 memcpy (&new_save_in_use[0],
2387 &G.save_in_use[count_old_page_tables],
2388 count_new_page_tables * sizeof (void *));
2389 memcpy (&new_save_in_use[count_new_page_tables],
2390 &G.save_in_use[0],
2391 count_old_page_tables * sizeof (void *));
2393 free (G.by_depth);
2394 free (G.save_in_use);
2396 G.by_depth = new_by_depth;
2397 G.save_in_use = new_save_in_use;
2399 /* Now update all the index_by_depth fields. */
2400 for (i = G.by_depth_in_use; i > 0; --i)
2402 page_entry *p = G.by_depth[i-1];
2403 p->index_by_depth = i-1;
2406 /* And last, we update the depth pointers in G.depth. The first
2407 entry is already 0, and context 0 entries always start at index
2408 0, so there is nothing to update in the first slot. We need a
2409 second slot, only if we have old ptes, and if we do, they start
2410 at index count_new_page_tables. */
2411 if (count_old_page_tables)
2412 push_depth (count_new_page_tables);
2415 void
2416 ggc_pch_read (FILE *f, void *addr)
2418 struct ggc_pch_ondisk d;
2419 unsigned i;
2420 char *offs = (char *) addr;
2421 unsigned long count_old_page_tables;
2422 unsigned long count_new_page_tables;
2424 count_old_page_tables = G.by_depth_in_use;
2426 /* We've just read in a PCH file. So, every object that used to be
2427 allocated is now free. */
2428 clear_marks ();
2429 #ifdef ENABLE_GC_CHECKING
2430 poison_pages ();
2431 #endif
2432 /* Since we free all the allocated objects, the free list becomes
2433 useless. Validate it now, which will also clear it. */
2434 validate_free_objects();
2436 /* No object read from a PCH file should ever be freed. So, set the
2437 context depth to 1, and set the depth of all the currently-allocated
2438 pages to be 1 too. PCH pages will have depth 0. */
2439 gcc_assert (!G.context_depth);
2440 G.context_depth = 1;
2441 for (i = 0; i < NUM_ORDERS; i++)
2443 page_entry *p;
2444 for (p = G.pages[i]; p != NULL; p = p->next)
2445 p->context_depth = G.context_depth;
2448 /* Allocate the appropriate page-table entries for the pages read from
2449 the PCH file. */
2450 if (fread (&d, sizeof (d), 1, f) != 1)
2451 fatal_error ("can%'t read PCH file: %m");
2453 for (i = 0; i < NUM_ORDERS; i++)
2455 struct page_entry *entry;
2456 char *pte;
2457 size_t bytes;
2458 size_t num_objs;
2459 size_t j;
2461 if (d.totals[i] == 0)
2462 continue;
2464 bytes = PAGE_ALIGN (d.totals[i] * OBJECT_SIZE (i));
2465 num_objs = bytes / OBJECT_SIZE (i);
2466 entry = XCNEWVAR (struct page_entry, (sizeof (struct page_entry)
2467 - sizeof (long)
2468 + BITMAP_SIZE (num_objs + 1)));
2469 entry->bytes = bytes;
2470 entry->page = offs;
2471 entry->context_depth = 0;
2472 offs += bytes;
2473 entry->num_free_objects = 0;
2474 entry->order = i;
2476 for (j = 0;
2477 j + HOST_BITS_PER_LONG <= num_objs + 1;
2478 j += HOST_BITS_PER_LONG)
2479 entry->in_use_p[j / HOST_BITS_PER_LONG] = -1;
2480 for (; j < num_objs + 1; j++)
2481 entry->in_use_p[j / HOST_BITS_PER_LONG]
2482 |= 1L << (j % HOST_BITS_PER_LONG);
2484 for (pte = entry->page;
2485 pte < entry->page + entry->bytes;
2486 pte += G.pagesize)
2487 set_page_table_entry (pte, entry);
2489 if (G.page_tails[i] != NULL)
2490 G.page_tails[i]->next = entry;
2491 else
2492 G.pages[i] = entry;
2493 G.page_tails[i] = entry;
2495 /* We start off by just adding all the new information to the
2496 end of the varrays, later, we will move the new information
2497 to the front of the varrays, as the PCH page tables are at
2498 context 0. */
2499 push_by_depth (entry, 0);
2502 /* Now, we update the various data structures that speed page table
2503 handling. */
2504 count_new_page_tables = G.by_depth_in_use - count_old_page_tables;
2506 move_ptes_to_front (count_old_page_tables, count_new_page_tables);
2508 /* Update the statistics. */
2509 G.allocated = G.allocated_last_gc = offs - (char *)addr;
2512 struct alloc_zone
2514 int dummy;
2517 struct alloc_zone rtl_zone;
2518 struct alloc_zone tree_zone;
2519 struct alloc_zone tree_id_zone;