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1812 lines
50 KiB
C
1812 lines
50 KiB
C
/* "Bag-of-pages" garbage collector for the GNU compiler.
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Copyright (C) 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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#include "config.h"
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#include "system.h"
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#include "tree.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "toplev.h"
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#include "flags.h"
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#include "ggc.h"
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#include "timevar.h"
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#include "params.h"
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#ifdef ENABLE_VALGRIND_CHECKING
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#include <valgrind.h>
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#else
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/* Avoid #ifdef:s when we can help it. */
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#define VALGRIND_DISCARD(x)
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#endif
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/* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
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file open. Prefer either to valloc. */
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#ifdef HAVE_MMAP_ANON
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# undef HAVE_MMAP_DEV_ZERO
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# include <sys/mman.h>
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# ifndef MAP_FAILED
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# define MAP_FAILED -1
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# endif
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# if !defined (MAP_ANONYMOUS) && defined (MAP_ANON)
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# define MAP_ANONYMOUS MAP_ANON
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# endif
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# define USING_MMAP
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#endif
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#ifdef HAVE_MMAP_DEV_ZERO
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# include <sys/mman.h>
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# ifndef MAP_FAILED
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# define MAP_FAILED -1
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# endif
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# define USING_MMAP
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#endif
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#ifndef USING_MMAP
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#define USING_MALLOC_PAGE_GROUPS
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#endif
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/* Stategy:
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This garbage-collecting allocator allocates objects on one of a set
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of pages. Each page can allocate objects of a single size only;
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available sizes are powers of two starting at four bytes. The size
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of an allocation request is rounded up to the next power of two
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(`order'), and satisfied from the appropriate page.
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Each page is recorded in a page-entry, which also maintains an
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in-use bitmap of object positions on the page. This allows the
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allocation state of a particular object to be flipped without
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touching the page itself.
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Each page-entry also has a context depth, which is used to track
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pushing and popping of allocation contexts. Only objects allocated
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in the current (highest-numbered) context may be collected.
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Page entries are arranged in an array of singly-linked lists. The
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array is indexed by the allocation size, in bits, of the pages on
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it; i.e. all pages on a list allocate objects of the same size.
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Pages are ordered on the list such that all non-full pages precede
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all full pages, with non-full pages arranged in order of decreasing
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context depth.
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Empty pages (of all orders) are kept on a single page cache list,
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and are considered first when new pages are required; they are
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deallocated at the start of the next collection if they haven't
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been recycled by then. */
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/* Define GGC_DEBUG_LEVEL to print debugging information.
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0: No debugging output.
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1: GC statistics only.
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2: Page-entry allocations/deallocations as well.
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3: Object allocations as well.
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4: Object marks as well. */
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#define GGC_DEBUG_LEVEL (0)
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#ifndef HOST_BITS_PER_PTR
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#define HOST_BITS_PER_PTR HOST_BITS_PER_LONG
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#endif
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/* A two-level tree is used to look up the page-entry for a given
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pointer. Two chunks of the pointer's bits are extracted to index
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the first and second levels of the tree, as follows:
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HOST_PAGE_SIZE_BITS
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32 | |
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msb +----------------+----+------+------+ lsb
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| | |
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PAGE_L1_BITS |
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PAGE_L2_BITS
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The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry
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pages are aligned on system page boundaries. The next most
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significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first
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index values in the lookup table, respectively.
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For 32-bit architectures and the settings below, there are no
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leftover bits. For architectures with wider pointers, the lookup
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tree points to a list of pages, which must be scanned to find the
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correct one. */
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#define PAGE_L1_BITS (8)
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#define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
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#define PAGE_L1_SIZE ((size_t) 1 << PAGE_L1_BITS)
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#define PAGE_L2_SIZE ((size_t) 1 << PAGE_L2_BITS)
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#define LOOKUP_L1(p) \
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(((size_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
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#define LOOKUP_L2(p) \
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(((size_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
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/* The number of objects per allocation page, for objects on a page of
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the indicated ORDER. */
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#define OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
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/* The size of an object on a page of the indicated ORDER. */
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#define OBJECT_SIZE(ORDER) object_size_table[ORDER]
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/* For speed, we avoid doing a general integer divide to locate the
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offset in the allocation bitmap, by precalculating numbers M, S
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such that (O * M) >> S == O / Z (modulo 2^32), for any offset O
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within the page which is evenly divisible by the object size Z. */
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#define DIV_MULT(ORDER) inverse_table[ORDER].mult
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#define DIV_SHIFT(ORDER) inverse_table[ORDER].shift
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#define OFFSET_TO_BIT(OFFSET, ORDER) \
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(((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
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/* The number of extra orders, not corresponding to power-of-two sized
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objects. */
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#define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
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#define RTL_SIZE(NSLOTS) \
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(sizeof (struct rtx_def) + ((NSLOTS) - 1) * sizeof (rtunion))
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/* The Ith entry is the maximum size of an object to be stored in the
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Ith extra order. Adding a new entry to this array is the *only*
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thing you need to do to add a new special allocation size. */
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static const size_t extra_order_size_table[] = {
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sizeof (struct tree_decl),
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sizeof (struct tree_list),
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RTL_SIZE (2), /* REG, MEM, PLUS, etc. */
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RTL_SIZE (10), /* INSN, CALL_INSN, JUMP_INSN */
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};
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/* The total number of orders. */
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#define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
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/* We use this structure to determine the alignment required for
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allocations. For power-of-two sized allocations, that's not a
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problem, but it does matter for odd-sized allocations. */
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struct max_alignment {
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char c;
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union {
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HOST_WIDEST_INT i;
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#ifdef HAVE_LONG_DOUBLE
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long double d;
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#else
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double d;
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#endif
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} u;
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};
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/* The biggest alignment required. */
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#define MAX_ALIGNMENT (offsetof (struct max_alignment, u))
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/* The Ith entry is the number of objects on a page or order I. */
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static unsigned objects_per_page_table[NUM_ORDERS];
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/* The Ith entry is the size of an object on a page of order I. */
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static size_t object_size_table[NUM_ORDERS];
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/* The Ith entry is a pair of numbers (mult, shift) such that
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((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
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for all k evenly divisible by OBJECT_SIZE(I). */
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static struct
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{
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unsigned int mult;
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unsigned int shift;
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}
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inverse_table[NUM_ORDERS];
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/* A page_entry records the status of an allocation page. This
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structure is dynamically sized to fit the bitmap in_use_p. */
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typedef struct page_entry
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{
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/* The next page-entry with objects of the same size, or NULL if
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this is the last page-entry. */
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struct page_entry *next;
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/* The number of bytes allocated. (This will always be a multiple
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of the host system page size.) */
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size_t bytes;
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/* The address at which the memory is allocated. */
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char *page;
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#ifdef USING_MALLOC_PAGE_GROUPS
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/* Back pointer to the page group this page came from. */
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struct page_group *group;
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#endif
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/* This is the index in the by_depth varray where this page table
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can be found. */
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unsigned long index_by_depth;
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/* Context depth of this page. */
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unsigned short context_depth;
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/* The number of free objects remaining on this page. */
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unsigned short num_free_objects;
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/* A likely candidate for the bit position of a free object for the
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next allocation from this page. */
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unsigned short next_bit_hint;
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/* The lg of size of objects allocated from this page. */
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unsigned char order;
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/* A bit vector indicating whether or not objects are in use. The
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Nth bit is one if the Nth object on this page is allocated. This
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array is dynamically sized. */
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unsigned long in_use_p[1];
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} page_entry;
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#ifdef USING_MALLOC_PAGE_GROUPS
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/* A page_group describes a large allocation from malloc, from which
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we parcel out aligned pages. */
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typedef struct page_group
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{
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/* A linked list of all extant page groups. */
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struct page_group *next;
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/* The address we received from malloc. */
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char *allocation;
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/* The size of the block. */
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size_t alloc_size;
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/* A bitmask of pages in use. */
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unsigned int in_use;
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} page_group;
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#endif
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#if HOST_BITS_PER_PTR <= 32
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/* On 32-bit hosts, we use a two level page table, as pictured above. */
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typedef page_entry **page_table[PAGE_L1_SIZE];
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#else
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/* On 64-bit hosts, we use the same two level page tables plus a linked
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list that disambiguates the top 32-bits. There will almost always be
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exactly one entry in the list. */
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typedef struct page_table_chain
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{
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struct page_table_chain *next;
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size_t high_bits;
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page_entry **table[PAGE_L1_SIZE];
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} *page_table;
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#endif
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/* The rest of the global variables. */
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static struct globals
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{
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/* The Nth element in this array is a page with objects of size 2^N.
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If there are any pages with free objects, they will be at the
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head of the list. NULL if there are no page-entries for this
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object size. */
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page_entry *pages[NUM_ORDERS];
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/* The Nth element in this array is the last page with objects of
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size 2^N. NULL if there are no page-entries for this object
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size. */
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page_entry *page_tails[NUM_ORDERS];
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/* Lookup table for associating allocation pages with object addresses. */
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page_table lookup;
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/* The system's page size. */
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size_t pagesize;
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size_t lg_pagesize;
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/* Bytes currently allocated. */
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size_t allocated;
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/* Bytes currently allocated at the end of the last collection. */
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size_t allocated_last_gc;
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/* Total amount of memory mapped. */
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size_t bytes_mapped;
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/* Bit N set if any allocations have been done at context depth N. */
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unsigned long context_depth_allocations;
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/* Bit N set if any collections have been done at context depth N. */
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unsigned long context_depth_collections;
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/* The current depth in the context stack. */
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unsigned short context_depth;
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/* A file descriptor open to /dev/zero for reading. */
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#if defined (HAVE_MMAP_DEV_ZERO)
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int dev_zero_fd;
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#endif
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/* A cache of free system pages. */
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page_entry *free_pages;
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#ifdef USING_MALLOC_PAGE_GROUPS
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page_group *page_groups;
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#endif
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/* The file descriptor for debugging output. */
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FILE *debug_file;
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/* Current number of elements in use in depth below. */
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unsigned int depth_in_use;
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/* Maximum number of elements that can be used before resizing. */
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unsigned int depth_max;
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/* Each element of this arry is an index in by_depth where the given
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depth starts. This structure is indexed by that given depth we
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are interested in. */
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unsigned int *depth;
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/* Current number of elements in use in by_depth below. */
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unsigned int by_depth_in_use;
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/* Maximum number of elements that can be used before resizing. */
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unsigned int by_depth_max;
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/* Each element of this array is a pointer to a page_entry, all
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page_entries can be found in here by increasing depth.
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index_by_depth in the page_entry is the index into this data
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structure where that page_entry can be found. This is used to
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speed up finding all page_entries at a particular depth. */
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page_entry **by_depth;
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/* Each element is a pointer to the saved in_use_p bits, if any,
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zero otherwise. We allocate them all together, to enable a
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better runtime data access pattern. */
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unsigned long **save_in_use;
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} G;
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/* The size in bytes required to maintain a bitmap for the objects
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on a page-entry. */
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#define BITMAP_SIZE(Num_objects) \
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(CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof(long))
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/* Allocate pages in chunks of this size, to throttle calls to memory
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allocation routines. The first page is used, the rest go onto the
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free list. This cannot be larger than HOST_BITS_PER_INT for the
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in_use bitmask for page_group. */
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#define GGC_QUIRE_SIZE 16
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/* Initial guess as to how many page table entries we might need. */
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#define INITIAL_PTE_COUNT 128
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static int ggc_allocated_p PARAMS ((const void *));
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static page_entry *lookup_page_table_entry PARAMS ((const void *));
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static void set_page_table_entry PARAMS ((void *, page_entry *));
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#ifdef USING_MMAP
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static char *alloc_anon PARAMS ((char *, size_t));
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#endif
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#ifdef USING_MALLOC_PAGE_GROUPS
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static size_t page_group_index PARAMS ((char *, char *));
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static void set_page_group_in_use PARAMS ((page_group *, char *));
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static void clear_page_group_in_use PARAMS ((page_group *, char *));
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#endif
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static struct page_entry * alloc_page PARAMS ((unsigned));
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static void free_page PARAMS ((struct page_entry *));
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static void release_pages PARAMS ((void));
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static void clear_marks PARAMS ((void));
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static void sweep_pages PARAMS ((void));
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static void ggc_recalculate_in_use_p PARAMS ((page_entry *));
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static void compute_inverse PARAMS ((unsigned));
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static inline void adjust_depth PARAMS ((void));
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#ifdef ENABLE_GC_CHECKING
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static void poison_pages PARAMS ((void));
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#endif
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||
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void debug_print_page_list PARAMS ((int));
|
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static void push_depth PARAMS ((unsigned int));
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static void push_by_depth PARAMS ((page_entry *, unsigned long *));
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/* Push an entry onto G.depth. */
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inline static void
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push_depth (i)
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unsigned int i;
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{
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if (G.depth_in_use >= G.depth_max)
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{
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G.depth_max *= 2;
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G.depth = (unsigned int *) xrealloc ((char *) G.depth,
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G.depth_max * sizeof (unsigned int));
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}
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G.depth[G.depth_in_use++] = i;
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||
}
|
||
|
||
/* Push an entry onto G.by_depth and G.save_in_use. */
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||
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inline static void
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push_by_depth (p, s)
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page_entry *p;
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unsigned long *s;
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{
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if (G.by_depth_in_use >= G.by_depth_max)
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{
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G.by_depth_max *= 2;
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G.by_depth = (page_entry **) xrealloc ((char *) G.by_depth,
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G.by_depth_max * sizeof (page_entry *));
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G.save_in_use = (unsigned long **) xrealloc ((char *) G.save_in_use,
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G.by_depth_max * sizeof (unsigned long *));
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}
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G.by_depth[G.by_depth_in_use] = p;
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G.save_in_use[G.by_depth_in_use++] = s;
|
||
}
|
||
|
||
/* For the 3.3 release, we will avoid prefetch, as it isn't tested widely. */
|
||
#define prefetch(X) ((void) X)
|
||
|
||
#define save_in_use_p_i(__i) \
|
||
(G.save_in_use[__i])
|
||
#define save_in_use_p(__p) \
|
||
(save_in_use_p_i (__p->index_by_depth))
|
||
|
||
/* Returns nonzero if P was allocated in GC'able memory. */
|
||
|
||
static inline int
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||
ggc_allocated_p (p)
|
||
const void *p;
|
||
{
|
||
page_entry ***base;
|
||
size_t L1, L2;
|
||
|
||
#if HOST_BITS_PER_PTR <= 32
|
||
base = &G.lookup[0];
|
||
#else
|
||
page_table table = G.lookup;
|
||
size_t high_bits = (size_t) p & ~ (size_t) 0xffffffff;
|
||
while (1)
|
||
{
|
||
if (table == NULL)
|
||
return 0;
|
||
if (table->high_bits == high_bits)
|
||
break;
|
||
table = table->next;
|
||
}
|
||
base = &table->table[0];
|
||
#endif
|
||
|
||
/* Extract the level 1 and 2 indices. */
|
||
L1 = LOOKUP_L1 (p);
|
||
L2 = LOOKUP_L2 (p);
|
||
|
||
return base[L1] && base[L1][L2];
|
||
}
|
||
|
||
/* Traverse the page table and find the entry for a page.
|
||
Die (probably) if the object wasn't allocated via GC. */
|
||
|
||
static inline page_entry *
|
||
lookup_page_table_entry(p)
|
||
const void *p;
|
||
{
|
||
page_entry ***base;
|
||
size_t L1, L2;
|
||
|
||
#if HOST_BITS_PER_PTR <= 32
|
||
base = &G.lookup[0];
|
||
#else
|
||
page_table table = G.lookup;
|
||
size_t high_bits = (size_t) p & ~ (size_t) 0xffffffff;
|
||
while (table->high_bits != high_bits)
|
||
table = table->next;
|
||
base = &table->table[0];
|
||
#endif
|
||
|
||
/* Extract the level 1 and 2 indices. */
|
||
L1 = LOOKUP_L1 (p);
|
||
L2 = LOOKUP_L2 (p);
|
||
|
||
return base[L1][L2];
|
||
}
|
||
|
||
/* Set the page table entry for a page. */
|
||
|
||
static void
|
||
set_page_table_entry(p, entry)
|
||
void *p;
|
||
page_entry *entry;
|
||
{
|
||
page_entry ***base;
|
||
size_t L1, L2;
|
||
|
||
#if HOST_BITS_PER_PTR <= 32
|
||
base = &G.lookup[0];
|
||
#else
|
||
page_table table;
|
||
size_t high_bits = (size_t) p & ~ (size_t) 0xffffffff;
|
||
for (table = G.lookup; table; table = table->next)
|
||
if (table->high_bits == high_bits)
|
||
goto found;
|
||
|
||
/* Not found -- allocate a new table. */
|
||
table = (page_table) xcalloc (1, sizeof(*table));
|
||
table->next = G.lookup;
|
||
table->high_bits = high_bits;
|
||
G.lookup = table;
|
||
found:
|
||
base = &table->table[0];
|
||
#endif
|
||
|
||
/* Extract the level 1 and 2 indices. */
|
||
L1 = LOOKUP_L1 (p);
|
||
L2 = LOOKUP_L2 (p);
|
||
|
||
if (base[L1] == NULL)
|
||
base[L1] = (page_entry **) xcalloc (PAGE_L2_SIZE, sizeof (page_entry *));
|
||
|
||
base[L1][L2] = entry;
|
||
}
|
||
|
||
/* Prints the page-entry for object size ORDER, for debugging. */
|
||
|
||
void
|
||
debug_print_page_list (order)
|
||
int order;
|
||
{
|
||
page_entry *p;
|
||
printf ("Head=%p, Tail=%p:\n", (PTR) G.pages[order],
|
||
(PTR) G.page_tails[order]);
|
||
p = G.pages[order];
|
||
while (p != NULL)
|
||
{
|
||
printf ("%p(%1d|%3d) -> ", (PTR) p, p->context_depth,
|
||
p->num_free_objects);
|
||
p = p->next;
|
||
}
|
||
printf ("NULL\n");
|
||
fflush (stdout);
|
||
}
|
||
|
||
#ifdef USING_MMAP
|
||
/* Allocate SIZE bytes of anonymous memory, preferably near PREF,
|
||
(if non-null). The ifdef structure here is intended to cause a
|
||
compile error unless exactly one of the HAVE_* is defined. */
|
||
|
||
static inline char *
|
||
alloc_anon (pref, size)
|
||
char *pref ATTRIBUTE_UNUSED;
|
||
size_t size;
|
||
{
|
||
#ifdef HAVE_MMAP_ANON
|
||
char *page = (char *) mmap (pref, size, PROT_READ | PROT_WRITE,
|
||
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
||
#endif
|
||
#ifdef HAVE_MMAP_DEV_ZERO
|
||
char *page = (char *) mmap (pref, size, PROT_READ | PROT_WRITE,
|
||
MAP_PRIVATE, G.dev_zero_fd, 0);
|
||
#endif
|
||
|
||
if (page == (char *) MAP_FAILED)
|
||
{
|
||
perror ("virtual memory exhausted");
|
||
exit (FATAL_EXIT_CODE);
|
||
}
|
||
|
||
/* Remember that we allocated this memory. */
|
||
G.bytes_mapped += size;
|
||
|
||
/* Pretend we don't have access to the allocated pages. We'll enable
|
||
access to smaller pieces of the area in ggc_alloc. Discard the
|
||
handle to avoid handle leak. */
|
||
VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (page, size));
|
||
|
||
return page;
|
||
}
|
||
#endif
|
||
#ifdef USING_MALLOC_PAGE_GROUPS
|
||
/* Compute the index for this page into the page group. */
|
||
|
||
static inline size_t
|
||
page_group_index (allocation, page)
|
||
char *allocation, *page;
|
||
{
|
||
return (size_t) (page - allocation) >> G.lg_pagesize;
|
||
}
|
||
|
||
/* Set and clear the in_use bit for this page in the page group. */
|
||
|
||
static inline void
|
||
set_page_group_in_use (group, page)
|
||
page_group *group;
|
||
char *page;
|
||
{
|
||
group->in_use |= 1 << page_group_index (group->allocation, page);
|
||
}
|
||
|
||
static inline void
|
||
clear_page_group_in_use (group, page)
|
||
page_group *group;
|
||
char *page;
|
||
{
|
||
group->in_use &= ~(1 << page_group_index (group->allocation, page));
|
||
}
|
||
#endif
|
||
|
||
/* Allocate a new page for allocating objects of size 2^ORDER,
|
||
and return an entry for it. The entry is not added to the
|
||
appropriate page_table list. */
|
||
|
||
static inline struct page_entry *
|
||
alloc_page (order)
|
||
unsigned order;
|
||
{
|
||
struct page_entry *entry, *p, **pp;
|
||
char *page;
|
||
size_t num_objects;
|
||
size_t bitmap_size;
|
||
size_t page_entry_size;
|
||
size_t entry_size;
|
||
#ifdef USING_MALLOC_PAGE_GROUPS
|
||
page_group *group;
|
||
#endif
|
||
|
||
num_objects = OBJECTS_PER_PAGE (order);
|
||
bitmap_size = BITMAP_SIZE (num_objects + 1);
|
||
page_entry_size = sizeof (page_entry) - sizeof (long) + bitmap_size;
|
||
entry_size = num_objects * OBJECT_SIZE (order);
|
||
if (entry_size < G.pagesize)
|
||
entry_size = G.pagesize;
|
||
|
||
entry = NULL;
|
||
page = NULL;
|
||
|
||
/* Check the list of free pages for one we can use. */
|
||
for (pp = &G.free_pages, p = *pp; p; pp = &p->next, p = *pp)
|
||
if (p->bytes == entry_size)
|
||
break;
|
||
|
||
if (p != NULL)
|
||
{
|
||
/* Recycle the allocated memory from this page ... */
|
||
*pp = p->next;
|
||
page = p->page;
|
||
|
||
#ifdef USING_MALLOC_PAGE_GROUPS
|
||
group = p->group;
|
||
#endif
|
||
|
||
/* ... and, if possible, the page entry itself. */
|
||
if (p->order == order)
|
||
{
|
||
entry = p;
|
||
memset (entry, 0, page_entry_size);
|
||
}
|
||
else
|
||
free (p);
|
||
}
|
||
#ifdef USING_MMAP
|
||
else if (entry_size == G.pagesize)
|
||
{
|
||
/* We want just one page. Allocate a bunch of them and put the
|
||
extras on the freelist. (Can only do this optimization with
|
||
mmap for backing store.) */
|
||
struct page_entry *e, *f = G.free_pages;
|
||
int i;
|
||
|
||
page = alloc_anon (NULL, G.pagesize * GGC_QUIRE_SIZE);
|
||
|
||
/* This loop counts down so that the chain will be in ascending
|
||
memory order. */
|
||
for (i = GGC_QUIRE_SIZE - 1; i >= 1; i--)
|
||
{
|
||
e = (struct page_entry *) xcalloc (1, page_entry_size);
|
||
e->order = order;
|
||
e->bytes = G.pagesize;
|
||
e->page = page + (i << G.lg_pagesize);
|
||
e->next = f;
|
||
f = e;
|
||
}
|
||
|
||
G.free_pages = f;
|
||
}
|
||
else
|
||
page = alloc_anon (NULL, entry_size);
|
||
#endif
|
||
#ifdef USING_MALLOC_PAGE_GROUPS
|
||
else
|
||
{
|
||
/* Allocate a large block of memory and serve out the aligned
|
||
pages therein. This results in much less memory wastage
|
||
than the traditional implementation of valloc. */
|
||
|
||
char *allocation, *a, *enda;
|
||
size_t alloc_size, head_slop, tail_slop;
|
||
int multiple_pages = (entry_size == G.pagesize);
|
||
|
||
if (multiple_pages)
|
||
alloc_size = GGC_QUIRE_SIZE * G.pagesize;
|
||
else
|
||
alloc_size = entry_size + G.pagesize - 1;
|
||
allocation = xmalloc (alloc_size);
|
||
|
||
page = (char *) (((size_t) allocation + G.pagesize - 1) & -G.pagesize);
|
||
head_slop = page - allocation;
|
||
if (multiple_pages)
|
||
tail_slop = ((size_t) allocation + alloc_size) & (G.pagesize - 1);
|
||
else
|
||
tail_slop = alloc_size - entry_size - head_slop;
|
||
enda = allocation + alloc_size - tail_slop;
|
||
|
||
/* We allocated N pages, which are likely not aligned, leaving
|
||
us with N-1 usable pages. We plan to place the page_group
|
||
structure somewhere in the slop. */
|
||
if (head_slop >= sizeof (page_group))
|
||
group = (page_group *)page - 1;
|
||
else
|
||
{
|
||
/* We magically got an aligned allocation. Too bad, we have
|
||
to waste a page anyway. */
|
||
if (tail_slop == 0)
|
||
{
|
||
enda -= G.pagesize;
|
||
tail_slop += G.pagesize;
|
||
}
|
||
if (tail_slop < sizeof (page_group))
|
||
abort ();
|
||
group = (page_group *)enda;
|
||
tail_slop -= sizeof (page_group);
|
||
}
|
||
|
||
/* Remember that we allocated this memory. */
|
||
group->next = G.page_groups;
|
||
group->allocation = allocation;
|
||
group->alloc_size = alloc_size;
|
||
group->in_use = 0;
|
||
G.page_groups = group;
|
||
G.bytes_mapped += alloc_size;
|
||
|
||
/* If we allocated multiple pages, put the rest on the free list. */
|
||
if (multiple_pages)
|
||
{
|
||
struct page_entry *e, *f = G.free_pages;
|
||
for (a = enda - G.pagesize; a != page; a -= G.pagesize)
|
||
{
|
||
e = (struct page_entry *) xcalloc (1, page_entry_size);
|
||
e->order = order;
|
||
e->bytes = G.pagesize;
|
||
e->page = a;
|
||
e->group = group;
|
||
e->next = f;
|
||
f = e;
|
||
}
|
||
G.free_pages = f;
|
||
}
|
||
}
|
||
#endif
|
||
|
||
if (entry == NULL)
|
||
entry = (struct page_entry *) xcalloc (1, page_entry_size);
|
||
|
||
entry->bytes = entry_size;
|
||
entry->page = page;
|
||
entry->context_depth = G.context_depth;
|
||
entry->order = order;
|
||
entry->num_free_objects = num_objects;
|
||
entry->next_bit_hint = 1;
|
||
|
||
G.context_depth_allocations |= (unsigned long)1 << G.context_depth;
|
||
|
||
#ifdef USING_MALLOC_PAGE_GROUPS
|
||
entry->group = group;
|
||
set_page_group_in_use (group, page);
|
||
#endif
|
||
|
||
/* Set the one-past-the-end in-use bit. This acts as a sentry as we
|
||
increment the hint. */
|
||
entry->in_use_p[num_objects / HOST_BITS_PER_LONG]
|
||
= (unsigned long) 1 << (num_objects % HOST_BITS_PER_LONG);
|
||
|
||
set_page_table_entry (page, entry);
|
||
|
||
if (GGC_DEBUG_LEVEL >= 2)
|
||
fprintf (G.debug_file,
|
||
"Allocating page at %p, object size=%lu, data %p-%p\n",
|
||
(PTR) entry, (unsigned long) OBJECT_SIZE (order), page,
|
||
page + entry_size - 1);
|
||
|
||
return entry;
|
||
}
|
||
|
||
/* Adjust the size of G.depth so that no index greater than the one
|
||
used by the top of the G.by_depth is used. */
|
||
|
||
static inline void
|
||
adjust_depth ()
|
||
{
|
||
page_entry *top;
|
||
|
||
if (G.by_depth_in_use)
|
||
{
|
||
top = G.by_depth[G.by_depth_in_use-1];
|
||
|
||
/* Peel back indicies in depth that index into by_depth, so that
|
||
as new elements are added to by_depth, we note the indicies
|
||
of those elements, if they are for new context depths. */
|
||
while (G.depth_in_use > (size_t)top->context_depth+1)
|
||
--G.depth_in_use;
|
||
}
|
||
}
|
||
|
||
/* For a page that is no longer needed, put it on the free page list. */
|
||
|
||
static inline void
|
||
free_page (entry)
|
||
page_entry *entry;
|
||
{
|
||
if (GGC_DEBUG_LEVEL >= 2)
|
||
fprintf (G.debug_file,
|
||
"Deallocating page at %p, data %p-%p\n", (PTR) entry,
|
||
entry->page, entry->page + entry->bytes - 1);
|
||
|
||
/* Mark the page as inaccessible. Discard the handle to avoid handle
|
||
leak. */
|
||
VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (entry->page, entry->bytes));
|
||
|
||
set_page_table_entry (entry->page, NULL);
|
||
|
||
#ifdef USING_MALLOC_PAGE_GROUPS
|
||
clear_page_group_in_use (entry->group, entry->page);
|
||
#endif
|
||
|
||
if (G.by_depth_in_use > 1)
|
||
{
|
||
page_entry *top = G.by_depth[G.by_depth_in_use-1];
|
||
|
||
/* If they are at the same depth, put top element into freed
|
||
slot. */
|
||
if (entry->context_depth == top->context_depth)
|
||
{
|
||
int i = entry->index_by_depth;
|
||
G.by_depth[i] = top;
|
||
G.save_in_use[i] = G.save_in_use[G.by_depth_in_use-1];
|
||
top->index_by_depth = i;
|
||
}
|
||
else
|
||
{
|
||
/* We cannot free a page from a context deeper than the
|
||
current one. */
|
||
abort ();
|
||
}
|
||
}
|
||
--G.by_depth_in_use;
|
||
|
||
adjust_depth ();
|
||
|
||
entry->next = G.free_pages;
|
||
G.free_pages = entry;
|
||
}
|
||
|
||
/* Release the free page cache to the system. */
|
||
|
||
static void
|
||
release_pages ()
|
||
{
|
||
#ifdef USING_MMAP
|
||
page_entry *p, *next;
|
||
char *start;
|
||
size_t len;
|
||
|
||
/* Gather up adjacent pages so they are unmapped together. */
|
||
p = G.free_pages;
|
||
|
||
while (p)
|
||
{
|
||
start = p->page;
|
||
next = p->next;
|
||
len = p->bytes;
|
||
free (p);
|
||
p = next;
|
||
|
||
while (p && p->page == start + len)
|
||
{
|
||
next = p->next;
|
||
len += p->bytes;
|
||
free (p);
|
||
p = next;
|
||
}
|
||
|
||
munmap (start, len);
|
||
G.bytes_mapped -= len;
|
||
}
|
||
|
||
G.free_pages = NULL;
|
||
#endif
|
||
#ifdef USING_MALLOC_PAGE_GROUPS
|
||
page_entry **pp, *p;
|
||
page_group **gp, *g;
|
||
|
||
/* Remove all pages from free page groups from the list. */
|
||
pp = &G.free_pages;
|
||
while ((p = *pp) != NULL)
|
||
if (p->group->in_use == 0)
|
||
{
|
||
*pp = p->next;
|
||
free (p);
|
||
}
|
||
else
|
||
pp = &p->next;
|
||
|
||
/* Remove all free page groups, and release the storage. */
|
||
gp = &G.page_groups;
|
||
while ((g = *gp) != NULL)
|
||
if (g->in_use == 0)
|
||
{
|
||
*gp = g->next;
|
||
G.bytes_mapped -= g->alloc_size;
|
||
free (g->allocation);
|
||
}
|
||
else
|
||
gp = &g->next;
|
||
#endif
|
||
}
|
||
|
||
/* This table provides a fast way to determine ceil(log_2(size)) for
|
||
allocation requests. The minimum allocation size is eight bytes. */
|
||
|
||
static unsigned char size_lookup[257] =
|
||
{
|
||
3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4,
|
||
4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
|
||
5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||
6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||
7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
|
||
8
|
||
};
|
||
|
||
/* Allocate a chunk of memory of SIZE bytes. If ZERO is nonzero, the
|
||
memory is zeroed; otherwise, its contents are undefined. */
|
||
|
||
void *
|
||
ggc_alloc (size)
|
||
size_t size;
|
||
{
|
||
unsigned order, word, bit, object_offset;
|
||
struct page_entry *entry;
|
||
void *result;
|
||
|
||
if (size <= 256)
|
||
order = size_lookup[size];
|
||
else
|
||
{
|
||
order = 9;
|
||
while (size > OBJECT_SIZE (order))
|
||
order++;
|
||
}
|
||
|
||
/* If there are non-full pages for this size allocation, they are at
|
||
the head of the list. */
|
||
entry = G.pages[order];
|
||
|
||
/* If there is no page for this object size, or all pages in this
|
||
context are full, allocate a new page. */
|
||
if (entry == NULL || entry->num_free_objects == 0)
|
||
{
|
||
struct page_entry *new_entry;
|
||
new_entry = alloc_page (order);
|
||
|
||
new_entry->index_by_depth = G.by_depth_in_use;
|
||
push_by_depth (new_entry, 0);
|
||
|
||
/* We can skip context depths, if we do, make sure we go all the
|
||
way to the new depth. */
|
||
while (new_entry->context_depth >= G.depth_in_use)
|
||
push_depth (G.by_depth_in_use-1);
|
||
|
||
/* If this is the only entry, it's also the tail. */
|
||
if (entry == NULL)
|
||
G.page_tails[order] = new_entry;
|
||
|
||
/* Put new pages at the head of the page list. */
|
||
new_entry->next = entry;
|
||
entry = new_entry;
|
||
G.pages[order] = new_entry;
|
||
|
||
/* For a new page, we know the word and bit positions (in the
|
||
in_use bitmap) of the first available object -- they're zero. */
|
||
new_entry->next_bit_hint = 1;
|
||
word = 0;
|
||
bit = 0;
|
||
object_offset = 0;
|
||
}
|
||
else
|
||
{
|
||
/* First try to use the hint left from the previous allocation
|
||
to locate a clear bit in the in-use bitmap. We've made sure
|
||
that the one-past-the-end bit is always set, so if the hint
|
||
has run over, this test will fail. */
|
||
unsigned hint = entry->next_bit_hint;
|
||
word = hint / HOST_BITS_PER_LONG;
|
||
bit = hint % HOST_BITS_PER_LONG;
|
||
|
||
/* If the hint didn't work, scan the bitmap from the beginning. */
|
||
if ((entry->in_use_p[word] >> bit) & 1)
|
||
{
|
||
word = bit = 0;
|
||
while (~entry->in_use_p[word] == 0)
|
||
++word;
|
||
while ((entry->in_use_p[word] >> bit) & 1)
|
||
++bit;
|
||
hint = word * HOST_BITS_PER_LONG + bit;
|
||
}
|
||
|
||
/* Next time, try the next bit. */
|
||
entry->next_bit_hint = hint + 1;
|
||
|
||
object_offset = hint * OBJECT_SIZE (order);
|
||
}
|
||
|
||
/* Set the in-use bit. */
|
||
entry->in_use_p[word] |= ((unsigned long) 1 << bit);
|
||
|
||
/* Keep a running total of the number of free objects. If this page
|
||
fills up, we may have to move it to the end of the list if the
|
||
next page isn't full. If the next page is full, all subsequent
|
||
pages are full, so there's no need to move it. */
|
||
if (--entry->num_free_objects == 0
|
||
&& entry->next != NULL
|
||
&& entry->next->num_free_objects > 0)
|
||
{
|
||
G.pages[order] = entry->next;
|
||
entry->next = NULL;
|
||
G.page_tails[order]->next = entry;
|
||
G.page_tails[order] = entry;
|
||
}
|
||
|
||
/* Calculate the object's address. */
|
||
result = entry->page + object_offset;
|
||
|
||
#ifdef ENABLE_GC_CHECKING
|
||
/* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
|
||
exact same semantics in presence of memory bugs, regardless of
|
||
ENABLE_VALGRIND_CHECKING. We override this request below. Drop the
|
||
handle to avoid handle leak. */
|
||
VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result, OBJECT_SIZE (order)));
|
||
|
||
/* `Poison' the entire allocated object, including any padding at
|
||
the end. */
|
||
memset (result, 0xaf, OBJECT_SIZE (order));
|
||
|
||
/* Make the bytes after the end of the object unaccessible. Discard the
|
||
handle to avoid handle leak. */
|
||
VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) result + size,
|
||
OBJECT_SIZE (order) - size));
|
||
#endif
|
||
|
||
/* Tell Valgrind that the memory is there, but its content isn't
|
||
defined. The bytes at the end of the object are still marked
|
||
unaccessible. */
|
||
VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result, size));
|
||
|
||
/* Keep track of how many bytes are being allocated. This
|
||
information is used in deciding when to collect. */
|
||
G.allocated += OBJECT_SIZE (order);
|
||
|
||
if (GGC_DEBUG_LEVEL >= 3)
|
||
fprintf (G.debug_file,
|
||
"Allocating object, requested size=%lu, actual=%lu at %p on %p\n",
|
||
(unsigned long) size, (unsigned long) OBJECT_SIZE (order), result,
|
||
(PTR) entry);
|
||
|
||
return result;
|
||
}
|
||
|
||
/* If P is not marked, marks it and return false. Otherwise return true.
|
||
P must have been allocated by the GC allocator; it mustn't point to
|
||
static objects, stack variables, or memory allocated with malloc. */
|
||
|
||
int
|
||
ggc_set_mark (p)
|
||
const void *p;
|
||
{
|
||
page_entry *entry;
|
||
unsigned bit, word;
|
||
unsigned long mask;
|
||
|
||
/* Look up the page on which the object is alloced. If the object
|
||
wasn't allocated by the collector, we'll probably die. */
|
||
entry = lookup_page_table_entry (p);
|
||
#ifdef ENABLE_CHECKING
|
||
if (entry == NULL)
|
||
abort ();
|
||
#endif
|
||
|
||
/* Calculate the index of the object on the page; this is its bit
|
||
position in the in_use_p bitmap. */
|
||
bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
|
||
word = bit / HOST_BITS_PER_LONG;
|
||
mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
|
||
|
||
/* If the bit was previously set, skip it. */
|
||
if (entry->in_use_p[word] & mask)
|
||
return 1;
|
||
|
||
/* Otherwise set it, and decrement the free object count. */
|
||
entry->in_use_p[word] |= mask;
|
||
entry->num_free_objects -= 1;
|
||
|
||
if (GGC_DEBUG_LEVEL >= 4)
|
||
fprintf (G.debug_file, "Marking %p\n", p);
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Return 1 if P has been marked, zero otherwise.
|
||
P must have been allocated by the GC allocator; it mustn't point to
|
||
static objects, stack variables, or memory allocated with malloc. */
|
||
|
||
int
|
||
ggc_marked_p (p)
|
||
const void *p;
|
||
{
|
||
page_entry *entry;
|
||
unsigned bit, word;
|
||
unsigned long mask;
|
||
|
||
/* Look up the page on which the object is alloced. If the object
|
||
wasn't allocated by the collector, we'll probably die. */
|
||
entry = lookup_page_table_entry (p);
|
||
#ifdef ENABLE_CHECKING
|
||
if (entry == NULL)
|
||
abort ();
|
||
#endif
|
||
|
||
/* Calculate the index of the object on the page; this is its bit
|
||
position in the in_use_p bitmap. */
|
||
bit = OFFSET_TO_BIT (((const char *) p) - entry->page, entry->order);
|
||
word = bit / HOST_BITS_PER_LONG;
|
||
mask = (unsigned long) 1 << (bit % HOST_BITS_PER_LONG);
|
||
|
||
return (entry->in_use_p[word] & mask) != 0;
|
||
}
|
||
|
||
/* Return the size of the gc-able object P. */
|
||
|
||
size_t
|
||
ggc_get_size (p)
|
||
const void *p;
|
||
{
|
||
page_entry *pe = lookup_page_table_entry (p);
|
||
return OBJECT_SIZE (pe->order);
|
||
}
|
||
|
||
/* Subroutine of init_ggc which computes the pair of numbers used to
|
||
perform division by OBJECT_SIZE (order) and fills in inverse_table[].
|
||
|
||
This algorithm is taken from Granlund and Montgomery's paper
|
||
"Division by Invariant Integers using Multiplication"
|
||
(Proc. SIGPLAN PLDI, 1994), section 9 (Exact division by
|
||
constants). */
|
||
|
||
static void
|
||
compute_inverse (order)
|
||
unsigned order;
|
||
{
|
||
unsigned size, inv, e;
|
||
|
||
/* There can be only one object per "page" in a bucket for sizes
|
||
larger than half a machine page; it will always have offset zero. */
|
||
if (OBJECT_SIZE (order) > G.pagesize/2)
|
||
{
|
||
if (OBJECTS_PER_PAGE (order) != 1)
|
||
abort ();
|
||
|
||
DIV_MULT (order) = 1;
|
||
DIV_SHIFT (order) = 0;
|
||
return;
|
||
}
|
||
|
||
size = OBJECT_SIZE (order);
|
||
e = 0;
|
||
while (size % 2 == 0)
|
||
{
|
||
e++;
|
||
size >>= 1;
|
||
}
|
||
|
||
inv = size;
|
||
while (inv * size != 1)
|
||
inv = inv * (2 - inv*size);
|
||
|
||
DIV_MULT (order) = inv;
|
||
DIV_SHIFT (order) = e;
|
||
}
|
||
|
||
/* Initialize the ggc-mmap allocator. */
|
||
void
|
||
init_ggc ()
|
||
{
|
||
unsigned order;
|
||
|
||
G.pagesize = getpagesize();
|
||
G.lg_pagesize = exact_log2 (G.pagesize);
|
||
|
||
#ifdef HAVE_MMAP_DEV_ZERO
|
||
G.dev_zero_fd = open ("/dev/zero", O_RDONLY);
|
||
if (G.dev_zero_fd == -1)
|
||
fatal_io_error ("open /dev/zero");
|
||
#endif
|
||
|
||
#if 0
|
||
G.debug_file = fopen ("ggc-mmap.debug", "w");
|
||
#else
|
||
G.debug_file = stdout;
|
||
#endif
|
||
|
||
#ifdef USING_MMAP
|
||
/* StunOS has an amazing off-by-one error for the first mmap allocation
|
||
after fiddling with RLIMIT_STACK. The result, as hard as it is to
|
||
believe, is an unaligned page allocation, which would cause us to
|
||
hork badly if we tried to use it. */
|
||
{
|
||
char *p = alloc_anon (NULL, G.pagesize);
|
||
struct page_entry *e;
|
||
if ((size_t)p & (G.pagesize - 1))
|
||
{
|
||
/* How losing. Discard this one and try another. If we still
|
||
can't get something useful, give up. */
|
||
|
||
p = alloc_anon (NULL, G.pagesize);
|
||
if ((size_t)p & (G.pagesize - 1))
|
||
abort ();
|
||
}
|
||
|
||
/* We have a good page, might as well hold onto it... */
|
||
e = (struct page_entry *) xcalloc (1, sizeof (struct page_entry));
|
||
e->bytes = G.pagesize;
|
||
e->page = p;
|
||
e->next = G.free_pages;
|
||
G.free_pages = e;
|
||
}
|
||
#endif
|
||
|
||
/* Initialize the object size table. */
|
||
for (order = 0; order < HOST_BITS_PER_PTR; ++order)
|
||
object_size_table[order] = (size_t) 1 << order;
|
||
for (order = HOST_BITS_PER_PTR; order < NUM_ORDERS; ++order)
|
||
{
|
||
size_t s = extra_order_size_table[order - HOST_BITS_PER_PTR];
|
||
|
||
/* If S is not a multiple of the MAX_ALIGNMENT, then round it up
|
||
so that we're sure of getting aligned memory. */
|
||
s = CEIL (s, MAX_ALIGNMENT) * MAX_ALIGNMENT;
|
||
object_size_table[order] = s;
|
||
}
|
||
|
||
/* Initialize the objects-per-page and inverse tables. */
|
||
for (order = 0; order < NUM_ORDERS; ++order)
|
||
{
|
||
objects_per_page_table[order] = G.pagesize / OBJECT_SIZE (order);
|
||
if (objects_per_page_table[order] == 0)
|
||
objects_per_page_table[order] = 1;
|
||
compute_inverse (order);
|
||
}
|
||
|
||
/* Reset the size_lookup array to put appropriately sized objects in
|
||
the special orders. All objects bigger than the previous power
|
||
of two, but no greater than the special size, should go in the
|
||
new order. */
|
||
for (order = HOST_BITS_PER_PTR; order < NUM_ORDERS; ++order)
|
||
{
|
||
int o;
|
||
int i;
|
||
|
||
o = size_lookup[OBJECT_SIZE (order)];
|
||
for (i = OBJECT_SIZE (order); size_lookup [i] == o; --i)
|
||
size_lookup[i] = order;
|
||
}
|
||
|
||
G.depth_in_use = 0;
|
||
G.depth_max = 10;
|
||
G.depth = (unsigned int *) xmalloc (G.depth_max * sizeof (unsigned int));
|
||
|
||
G.by_depth_in_use = 0;
|
||
G.by_depth_max = INITIAL_PTE_COUNT;
|
||
G.by_depth = (page_entry **) xmalloc (G.by_depth_max * sizeof (page_entry *));
|
||
G.save_in_use = (unsigned long **) xmalloc (G.by_depth_max * sizeof (unsigned long *));
|
||
}
|
||
|
||
/* Increment the `GC context'. Objects allocated in an outer context
|
||
are never freed, eliminating the need to register their roots. */
|
||
|
||
void
|
||
ggc_push_context ()
|
||
{
|
||
++G.context_depth;
|
||
|
||
/* Die on wrap. */
|
||
if (G.context_depth >= HOST_BITS_PER_LONG)
|
||
abort ();
|
||
}
|
||
|
||
/* Merge the SAVE_IN_USE_P and IN_USE_P arrays in P so that IN_USE_P
|
||
reflects reality. Recalculate NUM_FREE_OBJECTS as well. */
|
||
|
||
static void
|
||
ggc_recalculate_in_use_p (p)
|
||
page_entry *p;
|
||
{
|
||
unsigned int i;
|
||
size_t num_objects;
|
||
|
||
/* Because the past-the-end bit in in_use_p is always set, we
|
||
pretend there is one additional object. */
|
||
num_objects = OBJECTS_PER_PAGE (p->order) + 1;
|
||
|
||
/* Reset the free object count. */
|
||
p->num_free_objects = num_objects;
|
||
|
||
/* Combine the IN_USE_P and SAVE_IN_USE_P arrays. */
|
||
for (i = 0;
|
||
i < CEIL (BITMAP_SIZE (num_objects),
|
||
sizeof (*p->in_use_p));
|
||
++i)
|
||
{
|
||
unsigned long j;
|
||
|
||
/* Something is in use if it is marked, or if it was in use in a
|
||
context further down the context stack. */
|
||
p->in_use_p[i] |= save_in_use_p (p)[i];
|
||
|
||
/* Decrement the free object count for every object allocated. */
|
||
for (j = p->in_use_p[i]; j; j >>= 1)
|
||
p->num_free_objects -= (j & 1);
|
||
}
|
||
|
||
if (p->num_free_objects >= num_objects)
|
||
abort ();
|
||
}
|
||
|
||
/* Decrement the `GC context'. All objects allocated since the
|
||
previous ggc_push_context are migrated to the outer context. */
|
||
|
||
void
|
||
ggc_pop_context ()
|
||
{
|
||
unsigned long omask;
|
||
unsigned int depth, i, e;
|
||
#ifdef ENABLE_CHECKING
|
||
unsigned int order;
|
||
#endif
|
||
|
||
depth = --G.context_depth;
|
||
omask = (unsigned long)1 << (depth + 1);
|
||
|
||
if (!((G.context_depth_allocations | G.context_depth_collections) & omask))
|
||
return;
|
||
|
||
G.context_depth_allocations |= (G.context_depth_allocations & omask) >> 1;
|
||
G.context_depth_allocations &= omask - 1;
|
||
G.context_depth_collections &= omask - 1;
|
||
|
||
/* The G.depth array is shortend so that the last index is the
|
||
context_depth of the top element of by_depth. */
|
||
if (depth+1 < G.depth_in_use)
|
||
e = G.depth[depth+1];
|
||
else
|
||
e = G.by_depth_in_use;
|
||
|
||
/* We might not have any PTEs of depth depth. */
|
||
if (depth < G.depth_in_use)
|
||
{
|
||
|
||
/* First we go through all the pages at depth depth to
|
||
recalculate the in use bits. */
|
||
for (i = G.depth[depth]; i < e; ++i)
|
||
{
|
||
page_entry *p;
|
||
|
||
#ifdef ENABLE_CHECKING
|
||
p = G.by_depth[i];
|
||
|
||
/* Check that all of the pages really are at the depth that
|
||
we expect. */
|
||
if (p->context_depth != depth)
|
||
abort ();
|
||
if (p->index_by_depth != i)
|
||
abort ();
|
||
#endif
|
||
|
||
prefetch (&save_in_use_p_i (i+8));
|
||
prefetch (&save_in_use_p_i (i+16));
|
||
if (save_in_use_p_i (i))
|
||
{
|
||
p = G.by_depth[i];
|
||
ggc_recalculate_in_use_p (p);
|
||
free (save_in_use_p_i (i));
|
||
save_in_use_p_i (i) = 0;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Then, we reset all page_entries with a depth greater than depth
|
||
to be at depth. */
|
||
for (i = e; i < G.by_depth_in_use; ++i)
|
||
{
|
||
page_entry *p = G.by_depth[i];
|
||
|
||
/* Check that all of the pages really are at the depth we
|
||
expect. */
|
||
#ifdef ENABLE_CHECKING
|
||
if (p->context_depth <= depth)
|
||
abort ();
|
||
if (p->index_by_depth != i)
|
||
abort ();
|
||
#endif
|
||
p->context_depth = depth;
|
||
}
|
||
|
||
adjust_depth ();
|
||
|
||
#ifdef ENABLE_CHECKING
|
||
for (order = 2; order < NUM_ORDERS; order++)
|
||
{
|
||
page_entry *p;
|
||
|
||
for (p = G.pages[order]; p != NULL; p = p->next)
|
||
{
|
||
if (p->context_depth > depth)
|
||
abort ();
|
||
else if (p->context_depth == depth && save_in_use_p (p))
|
||
abort ();
|
||
}
|
||
}
|
||
#endif
|
||
}
|
||
|
||
/* Unmark all objects. */
|
||
|
||
static inline void
|
||
clear_marks ()
|
||
{
|
||
unsigned order;
|
||
|
||
for (order = 2; order < NUM_ORDERS; order++)
|
||
{
|
||
size_t num_objects = OBJECTS_PER_PAGE (order);
|
||
size_t bitmap_size = BITMAP_SIZE (num_objects + 1);
|
||
page_entry *p;
|
||
|
||
for (p = G.pages[order]; p != NULL; p = p->next)
|
||
{
|
||
#ifdef ENABLE_CHECKING
|
||
/* The data should be page-aligned. */
|
||
if ((size_t) p->page & (G.pagesize - 1))
|
||
abort ();
|
||
#endif
|
||
|
||
/* Pages that aren't in the topmost context are not collected;
|
||
nevertheless, we need their in-use bit vectors to store GC
|
||
marks. So, back them up first. */
|
||
if (p->context_depth < G.context_depth)
|
||
{
|
||
if (! save_in_use_p (p))
|
||
save_in_use_p (p) = xmalloc (bitmap_size);
|
||
memcpy (save_in_use_p (p), p->in_use_p, bitmap_size);
|
||
}
|
||
|
||
/* Reset reset the number of free objects and clear the
|
||
in-use bits. These will be adjusted by mark_obj. */
|
||
p->num_free_objects = num_objects;
|
||
memset (p->in_use_p, 0, bitmap_size);
|
||
|
||
/* Make sure the one-past-the-end bit is always set. */
|
||
p->in_use_p[num_objects / HOST_BITS_PER_LONG]
|
||
= ((unsigned long) 1 << (num_objects % HOST_BITS_PER_LONG));
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Free all empty pages. Partially empty pages need no attention
|
||
because the `mark' bit doubles as an `unused' bit. */
|
||
|
||
static inline void
|
||
sweep_pages ()
|
||
{
|
||
unsigned order;
|
||
|
||
for (order = 2; order < NUM_ORDERS; order++)
|
||
{
|
||
/* The last page-entry to consider, regardless of entries
|
||
placed at the end of the list. */
|
||
page_entry * const last = G.page_tails[order];
|
||
|
||
size_t num_objects = OBJECTS_PER_PAGE (order);
|
||
size_t live_objects;
|
||
page_entry *p, *previous;
|
||
int done;
|
||
|
||
p = G.pages[order];
|
||
if (p == NULL)
|
||
continue;
|
||
|
||
previous = NULL;
|
||
do
|
||
{
|
||
page_entry *next = p->next;
|
||
|
||
/* Loop until all entries have been examined. */
|
||
done = (p == last);
|
||
|
||
/* Add all live objects on this page to the count of
|
||
allocated memory. */
|
||
live_objects = num_objects - p->num_free_objects;
|
||
|
||
G.allocated += OBJECT_SIZE (order) * live_objects;
|
||
|
||
/* Only objects on pages in the topmost context should get
|
||
collected. */
|
||
if (p->context_depth < G.context_depth)
|
||
;
|
||
|
||
/* Remove the page if it's empty. */
|
||
else if (live_objects == 0)
|
||
{
|
||
if (! previous)
|
||
G.pages[order] = next;
|
||
else
|
||
previous->next = next;
|
||
|
||
/* Are we removing the last element? */
|
||
if (p == G.page_tails[order])
|
||
G.page_tails[order] = previous;
|
||
free_page (p);
|
||
p = previous;
|
||
}
|
||
|
||
/* If the page is full, move it to the end. */
|
||
else if (p->num_free_objects == 0)
|
||
{
|
||
/* Don't move it if it's already at the end. */
|
||
if (p != G.page_tails[order])
|
||
{
|
||
/* Move p to the end of the list. */
|
||
p->next = NULL;
|
||
G.page_tails[order]->next = p;
|
||
|
||
/* Update the tail pointer... */
|
||
G.page_tails[order] = p;
|
||
|
||
/* ... and the head pointer, if necessary. */
|
||
if (! previous)
|
||
G.pages[order] = next;
|
||
else
|
||
previous->next = next;
|
||
p = previous;
|
||
}
|
||
}
|
||
|
||
/* If we've fallen through to here, it's a page in the
|
||
topmost context that is neither full nor empty. Such a
|
||
page must precede pages at lesser context depth in the
|
||
list, so move it to the head. */
|
||
else if (p != G.pages[order])
|
||
{
|
||
previous->next = p->next;
|
||
p->next = G.pages[order];
|
||
G.pages[order] = p;
|
||
/* Are we moving the last element? */
|
||
if (G.page_tails[order] == p)
|
||
G.page_tails[order] = previous;
|
||
p = previous;
|
||
}
|
||
|
||
previous = p;
|
||
p = next;
|
||
}
|
||
while (! done);
|
||
|
||
/* Now, restore the in_use_p vectors for any pages from contexts
|
||
other than the current one. */
|
||
for (p = G.pages[order]; p; p = p->next)
|
||
if (p->context_depth != G.context_depth)
|
||
ggc_recalculate_in_use_p (p);
|
||
}
|
||
}
|
||
|
||
#ifdef ENABLE_GC_CHECKING
|
||
/* Clobber all free objects. */
|
||
|
||
static inline void
|
||
poison_pages ()
|
||
{
|
||
unsigned order;
|
||
|
||
for (order = 2; order < NUM_ORDERS; order++)
|
||
{
|
||
size_t num_objects = OBJECTS_PER_PAGE (order);
|
||
size_t size = OBJECT_SIZE (order);
|
||
page_entry *p;
|
||
|
||
for (p = G.pages[order]; p != NULL; p = p->next)
|
||
{
|
||
size_t i;
|
||
|
||
if (p->context_depth != G.context_depth)
|
||
/* Since we don't do any collection for pages in pushed
|
||
contexts, there's no need to do any poisoning. And
|
||
besides, the IN_USE_P array isn't valid until we pop
|
||
contexts. */
|
||
continue;
|
||
|
||
for (i = 0; i < num_objects; i++)
|
||
{
|
||
size_t word, bit;
|
||
word = i / HOST_BITS_PER_LONG;
|
||
bit = i % HOST_BITS_PER_LONG;
|
||
if (((p->in_use_p[word] >> bit) & 1) == 0)
|
||
{
|
||
char *object = p->page + i * size;
|
||
|
||
/* Keep poison-by-write when we expect to use Valgrind,
|
||
so the exact same memory semantics is kept, in case
|
||
there are memory errors. We override this request
|
||
below. */
|
||
VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (object, size));
|
||
memset (object, 0xa5, size);
|
||
|
||
/* Drop the handle to avoid handle leak. */
|
||
VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (object, size));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
#endif
|
||
|
||
/* Top level mark-and-sweep routine. */
|
||
|
||
void
|
||
ggc_collect ()
|
||
{
|
||
/* Avoid frequent unnecessary work by skipping collection if the
|
||
total allocations haven't expanded much since the last
|
||
collection. */
|
||
float allocated_last_gc =
|
||
MAX (G.allocated_last_gc, (size_t)PARAM_VALUE (GGC_MIN_HEAPSIZE) * 1024);
|
||
|
||
float min_expand = allocated_last_gc * PARAM_VALUE (GGC_MIN_EXPAND) / 100;
|
||
|
||
if (G.allocated < allocated_last_gc + min_expand)
|
||
return;
|
||
|
||
timevar_push (TV_GC);
|
||
if (!quiet_flag)
|
||
fprintf (stderr, " {GC %luk -> ", (unsigned long) G.allocated / 1024);
|
||
|
||
/* Zero the total allocated bytes. This will be recalculated in the
|
||
sweep phase. */
|
||
G.allocated = 0;
|
||
|
||
/* Release the pages we freed the last time we collected, but didn't
|
||
reuse in the interim. */
|
||
release_pages ();
|
||
|
||
/* Indicate that we've seen collections at this context depth. */
|
||
G.context_depth_collections = ((unsigned long)1 << (G.context_depth + 1)) - 1;
|
||
|
||
clear_marks ();
|
||
ggc_mark_roots ();
|
||
|
||
#ifdef ENABLE_GC_CHECKING
|
||
poison_pages ();
|
||
#endif
|
||
|
||
sweep_pages ();
|
||
|
||
G.allocated_last_gc = G.allocated;
|
||
|
||
timevar_pop (TV_GC);
|
||
|
||
if (!quiet_flag)
|
||
fprintf (stderr, "%luk}", (unsigned long) G.allocated / 1024);
|
||
}
|
||
|
||
/* Print allocation statistics. */
|
||
#define SCALE(x) ((unsigned long) ((x) < 1024*10 \
|
||
? (x) \
|
||
: ((x) < 1024*1024*10 \
|
||
? (x) / 1024 \
|
||
: (x) / (1024*1024))))
|
||
#define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
|
||
|
||
void
|
||
ggc_print_statistics ()
|
||
{
|
||
struct ggc_statistics stats;
|
||
unsigned int i;
|
||
size_t total_overhead = 0;
|
||
|
||
/* Clear the statistics. */
|
||
memset (&stats, 0, sizeof (stats));
|
||
|
||
/* Make sure collection will really occur. */
|
||
G.allocated_last_gc = 0;
|
||
|
||
/* Collect and print the statistics common across collectors. */
|
||
ggc_print_common_statistics (stderr, &stats);
|
||
|
||
/* Release free pages so that we will not count the bytes allocated
|
||
there as part of the total allocated memory. */
|
||
release_pages ();
|
||
|
||
/* Collect some information about the various sizes of
|
||
allocation. */
|
||
fprintf (stderr, "\n%-5s %10s %10s %10s\n",
|
||
"Size", "Allocated", "Used", "Overhead");
|
||
for (i = 0; i < NUM_ORDERS; ++i)
|
||
{
|
||
page_entry *p;
|
||
size_t allocated;
|
||
size_t in_use;
|
||
size_t overhead;
|
||
|
||
/* Skip empty entries. */
|
||
if (!G.pages[i])
|
||
continue;
|
||
|
||
overhead = allocated = in_use = 0;
|
||
|
||
/* Figure out the total number of bytes allocated for objects of
|
||
this size, and how many of them are actually in use. Also figure
|
||
out how much memory the page table is using. */
|
||
for (p = G.pages[i]; p; p = p->next)
|
||
{
|
||
allocated += p->bytes;
|
||
in_use +=
|
||
(OBJECTS_PER_PAGE (i) - p->num_free_objects) * OBJECT_SIZE (i);
|
||
|
||
overhead += (sizeof (page_entry) - sizeof (long)
|
||
+ BITMAP_SIZE (OBJECTS_PER_PAGE (i) + 1));
|
||
}
|
||
fprintf (stderr, "%-5lu %10lu%c %10lu%c %10lu%c\n",
|
||
(unsigned long) OBJECT_SIZE (i),
|
||
SCALE (allocated), LABEL (allocated),
|
||
SCALE (in_use), LABEL (in_use),
|
||
SCALE (overhead), LABEL (overhead));
|
||
total_overhead += overhead;
|
||
}
|
||
fprintf (stderr, "%-5s %10lu%c %10lu%c %10lu%c\n", "Total",
|
||
SCALE (G.bytes_mapped), LABEL (G.bytes_mapped),
|
||
SCALE (G.allocated), LABEL(G.allocated),
|
||
SCALE (total_overhead), LABEL (total_overhead));
|
||
}
|