#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "tm_p.h"
#include "diagnostic-core.h"
#include "flags.h"
#include "ggc.h"
#include "ggc-internal.h"
#include "timevar.h"
#include "params.h"
#include "cgraph.h"
#include "cfgloop.h"
#include "plugin.h"

Include dependency graph for ggc-page.c:

Data Structures
struct	max_alignment
struct	page_entry
struct	page_group
struct	globals
struct	ggc_pch_ondisk
struct	ggc_pch_data

Macros
#define	USING_MALLOC_PAGE_GROUPS
#define	GGC_DEBUG_LEVEL (0)
#define	HOST_BITS_PER_PTR HOST_BITS_PER_LONG
#define	PAGE_L1_BITS (8)
#define	PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)
#define	PAGE_L1_SIZE ((uintptr_t) 1 << PAGE_L1_BITS)
#define	PAGE_L2_SIZE ((uintptr_t) 1 << PAGE_L2_BITS)
#define	LOOKUP_L1(p) (((uintptr_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))
#define	LOOKUP_L2(p) (((uintptr_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))
#define	OBJECTS_PER_PAGE(ORDER) objects_per_page_table[ORDER]
#define	OBJECTS_IN_PAGE(P) ((P)->bytes / OBJECT_SIZE ((P)->order))
#define	OBJECT_SIZE(ORDER) object_size_table[ORDER]
#define	DIV_MULT(ORDER) inverse_table[ORDER].mult
#define	DIV_SHIFT(ORDER) inverse_table[ORDER].shift
#define	OFFSET_TO_BIT(OFFSET, ORDER) (((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))
#define	MAX_ALIGNMENT (offsetof (struct max_alignment, u))
#define	NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)
#define	RTL_SIZE(NSLOTS) (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))
#define	TREE_EXP_SIZE(OPS) (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))
#define	NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)
#define	ROUND_UP_VALUE(x, f) ((f) - 1 - ((f) - 1 + (x)) % (f))
#define	ROUND_UP(x, f) (CEIL (x, f) * (f))
#define	PAGE_ALIGN(x) (((x) + G.pagesize - 1) & ~(G.pagesize - 1))
#define	BITMAP_SIZE(Num_objects) (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof (long))
#define	GGC_QUIRE_SIZE 16
#define	INITIAL_PTE_COUNT 128
#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))
#define	NUM_SIZE_LOOKUP 512
#define	poison_pages()
#define	validate_free_objects()
#define	SCALE(x)
#define	STAT_LABEL(x) ((x) < 102410 ? ' ' : ((x) < 10241024*10 ? 'k' : 'M'))

Typedefs
typedef struct page_entry	page_entry
typedef struct page_group	page_group
typedef page_entry **	page_table [PAGE_L1_SIZE]

Functions
static int	ggc_allocated_p (const void *)
static page_entry *	lookup_page_table_entry (const void *)
static void	set_page_table_entry (void , page_entry )
static size_t	page_group_index (char , char )
static void	set_page_group_in_use (page_group , char )
static void	clear_page_group_in_use (page_group , char )
static struct page_entry *	alloc_page (unsigned)
static void	free_page (struct page_entry *)
static void	release_pages (void)
static void	clear_marks (void)
static void	sweep_pages (void)
static void	ggc_recalculate_in_use_p (page_entry *)
static void	compute_inverse (unsigned)
static void	adjust_depth (void)
static void	move_ptes_to_front (int, int)
void	debug_print_page_list (int)
static void	push_depth (unsigned int)
static void	push_by_depth (page_entry , unsigned long )
static void	push_depth ()
static void	push_by_depth ()
static int	ggc_allocated_p ()
static page_entry *	lookup_page_table_entry ()
static void	set_page_table_entry ()
DEBUG_FUNCTION void	debug_print_page_list ()
static size_t	page_group_index ()
static void	set_page_group_in_use ()
static void	clear_page_group_in_use ()
static struct page_entry *	alloc_page ()
static void	free_page ()
static void	ggc_round_alloc_size_1 (size_t requested_size, size_t size_order, size_t alloced_size)
size_t	ggc_round_alloc_size ()
void *	ggc_internal_alloc_stat ()
void	gt_ggc_m_S ()
void	gt_ggc_mx ()
int	ggc_set_mark ()
int	ggc_marked_p ()
size_t	ggc_get_size ()
void	ggc_free ()
static void	compute_inverse ()
void	init_ggc ()
static void	ggc_recalculate_in_use_p ()
void	ggc_collect ()
void	ggc_print_statistics ()
struct ggc_pch_data *	init_ggc_pch ()
void	ggc_pch_count_object (struct ggc_pch_data d, void x, size_t size, bool is_string)
size_t	ggc_pch_total_size ()
void	ggc_pch_this_base ()
char *	ggc_pch_alloc_object (struct ggc_pch_data d, void x, size_t size, bool is_string)
void	ggc_pch_prepare_write (struct ggc_pch_data d, FILE f)
void	ggc_pch_write_object (struct ggc_pch_data d, FILE f, void x, void newx, size_t size, bool is_string)
void	ggc_pch_finish ()
static void	move_ptes_to_front ()
void	ggc_pch_read ()

Variables
static const size_t	extra_order_size_table []
static unsigned	objects_per_page_table [NUM_ORDERS]
static size_t	object_size_table [NUM_ORDERS]
struct {
size_t mult
unsigned int shift
}	inverse_table [NUM_ORDERS]
static struct globals	G
static unsigned char	size_lookup [NUM_SIZE_LOOKUP]

Macro Definition Documentation

#define BITMAP_SIZE ( Num_objects ) (CEIL ((Num_objects), HOST_BITS_PER_LONG) * sizeof (long))

The size in bytes required to maintain a bitmap for the objects on a page-entry.

Referenced by compute_inverse(), and debug_print_page_list().

#define DIV_MULT ( ORDER ) inverse_table[ORDER].mult

For speed, we avoid doing a general integer divide to locate the offset in the allocation bitmap, by precalculating numbers M, S such that (O * M) >> S == O / Z (modulo 2^32), for any offset O within the page which is evenly divisible by the object size Z.

#define DIV_SHIFT ( ORDER ) inverse_table[ORDER].shift

#define GGC_DEBUG_LEVEL (0)

Strategy:

This garbage-collecting allocator allocates objects on one of a set of pages. Each page can allocate objects of a single size only; available sizes are powers of two starting at four bytes. The size of an allocation request is rounded up to the next power of two (`order'), and satisfied from the appropriate page.

Each page is recorded in a page-entry, which also maintains an in-use bitmap of object positions on the page. This allows the allocation state of a particular object to be flipped without touching the page itself.

Each page-entry also has a context depth, which is used to track pushing and popping of allocation contexts. Only objects allocated in the current (highest-numbered) context may be collected.

Page entries are arranged in an array of singly-linked lists. The array is indexed by the allocation size, in bits, of the pages on it; i.e. all pages on a list allocate objects of the same size. Pages are ordered on the list such that all non-full pages precede all full pages, with non-full pages arranged in order of decreasing context depth.

Empty pages (of all orders) are kept on a single page cache list, and are considered first when new pages are required; they are deallocated at the start of the next collection if they haven't been recycled by then. Define GGC_DEBUG_LEVEL to print debugging information. 0: No debugging output. 1: GC statistics only. 2: Page-entry allocations/deallocations as well. 3: Object allocations as well. 4: Object marks as well.

Referenced by gt_ggc_m_S().

#define GGC_QUIRE_SIZE 16

Allocate pages in chunks of this size, to throttle calls to memory allocation routines. The first page is used, the rest go onto the free list. This cannot be larger than HOST_BITS_PER_INT for the in_use bitmask for page_group. Hosts that need a different value can override this by defining GGC_QUIRE_SIZE explicitly.

Referenced by debug_print_page_list().

#define HOST_BITS_PER_PTR HOST_BITS_PER_LONG

#define INITIAL_PTE_COUNT 128

Initial guess as to how many page table entries we might need.

#define LOOKUP_L1 ( p ) (((uintptr_t) (p) >> (32 - PAGE_L1_BITS)) & ((1 << PAGE_L1_BITS) - 1))

#define LOOKUP_L2 ( p ) (((uintptr_t) (p) >> G.lg_pagesize) & ((1 << PAGE_L2_BITS) - 1))

#define MAX_ALIGNMENT (offsetof (struct max_alignment, u))

The biggest alignment required.

#define NUM_EXTRA_ORDERS ARRAY_SIZE (extra_order_size_table)

The number of extra orders, not corresponding to power-of-two sized objects.

#define NUM_ORDERS (HOST_BITS_PER_PTR + NUM_EXTRA_ORDERS)

The total number of orders.

#define NUM_SIZE_LOOKUP 512

This table provides a fast way to determine ceil(log_2(size)) for allocation requests. The minimum allocation size is eight bytes.

#define OBJECT_SIZE ( ORDER ) object_size_table[ORDER]

The size of an object on a page of the indicated ORDER.

Referenced by clear_marks(), debug_print_page_list(), and gt_ggc_m_S().

#define OBJECTS_IN_PAGE ( P ) ((P)->bytes / OBJECT_SIZE ((P)->order))

The number of objects in P.

Referenced by clear_marks(), and compute_inverse().

#define OBJECTS_PER_PAGE ( ORDER ) objects_per_page_table[ORDER]

The number of objects per allocation page, for objects on a page of the indicated ORDER.

Referenced by debug_print_page_list().

#define OFFSET_TO_BIT	(	OFFSET,
		ORDER
	)	(((OFFSET) * DIV_MULT (ORDER)) >> DIV_SHIFT (ORDER))

Referenced by gt_ggc_m_S(), and sweep_pages().

#define PAGE_ALIGN ( x ) (((x) + G.pagesize - 1) & ~(G.pagesize - 1))

Round X to next multiple of the page size

Referenced by debug_print_page_list(), and ggc_collect().

#define PAGE_L1_BITS (8)

A two-level tree is used to look up the page-entry for a given pointer. Two chunks of the pointer's bits are extracted to index the first and second levels of the tree, as follows:

                            HOST_PAGE_SIZE_BITS
                    32           |      |
msb +&mdash;&mdash;&mdash;&mdash;&mdash;-+&mdash;-+&mdash;&mdash;+&mdash;&mdash;+ lsb
                     |    |      |
                  PAGE_L1_BITS   |
                          |      |
                        PAGE_L2_BITS

The bottommost HOST_PAGE_SIZE_BITS are ignored, since page-entry pages are aligned on system page boundaries. The next most significant PAGE_L2_BITS and PAGE_L1_BITS are the second and first index values in the lookup table, respectively.

For 32-bit architectures and the settings below, there are no leftover bits. For architectures with wider pointers, the lookup tree points to a list of pages, which must be scanned to find the correct one.

#define PAGE_L1_SIZE ((uintptr_t) 1 << PAGE_L1_BITS)

#define PAGE_L2_BITS (32 - PAGE_L1_BITS - G.lg_pagesize)

#define PAGE_L2_SIZE ((uintptr_t) 1 << PAGE_L2_BITS)

#define poison_pages ( )

#define prefetch ( X ) ((void) X)

#define ROUND_UP	(	x,
		f
	)	(CEIL (x, f) * (f))

Compute the smallest multiple of F that is >= X.

#define ROUND_UP_VALUE	(	x,
		f
	)	((f) - 1 - ((f) - 1 + (x)) % (f))

Compute the smallest nonnegative number which when added to X gives a multiple of F.

#define RTL_SIZE ( NSLOTS ) (RTX_HDR_SIZE + (NSLOTS) * sizeof (rtunion))

#define save_in_use_p ( __p ) (save_in_use_p_i (__p->index_by_depth))

Referenced by compute_inverse().

#define save_in_use_p_i ( __i ) (G.save_in_use[__i])

#define SCALE ( x )

Value:

((unsigned long) ((x) < 1024*10 \
                  ? (x) \
                  : ((x) < 1024*1024*10 \
                     ? (x) / 1024 \
                     : (x) / (1024*1024))))

Print allocation statistics.

#define STAT_LABEL ( x ) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))

#define TREE_EXP_SIZE ( OPS ) (sizeof (struct tree_exp) + ((OPS) - 1) * sizeof (tree))

#define USING_MALLOC_PAGE_GROUPS

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see http://www.gnu.org/licenses/. Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a file open. Prefer either to valloc.

#define validate_free_objects ( )

Typedef Documentation

typedef struct page_entry page_entry

A page_entry records the status of an allocation page. This structure is dynamically sized to fit the bitmap in_use_p.

typedef struct page_group page_group

A page_group describes a large allocation from malloc, from which we parcel out aligned pages.

typedef page_entry** page_table[PAGE_L1_SIZE]

On 32-bit hosts, we use a two level page table, as pictured above.

Function Documentation

static void adjust_depth ( )

inlinestatic

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.

Peel back indices in depth that index into by_depth, so that as new elements are added to by_depth, we note the indices of those elements, if they are for new context depths.

static struct page_entry* alloc_page ( unsigned )

staticread

static struct page_entry* alloc_page ( )

staticread

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.

 Check the list of free pages for one we can use.

     Recycle the allocated memory from this page ...

     ... and, if possible, the page entry itself.

     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.

     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.

         We magically got an aligned allocation.  Too bad, we have
         to waste a page anyway.

     Remember that we allocated this memory.

     If we allocated multiple pages, put the rest on the free list.

 Set the one-past-the-end in-use bit.  This acts as a sentry as we
 increment the hint.

static void clear_marks ( )

static

Unmark all objects.

         The data should be page-aligned.

         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.

         Reset reset the number of free objects and clear the
         in-use bits.  These will be adjusted by mark_obj.

         Make sure the one-past-the-end bit is always set.

References page_entry::context_depth, globals::context_depth, G, HOST_BITS_PER_LONG, page_entry::in_use_p, page_entry::next, NULL, OBJECT_SIZE, OBJECTS_IN_PAGE, page_entry::page, globals::pages, and VALGRIND_DISCARD.

static void clear_page_group_in_use	(	page_group *	,
		char *
	)

static

static void clear_page_group_in_use ( )

inlinestatic

static void compute_inverse ( unsigned )

static

static void compute_inverse ( )

static

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).

References BITMAP_SIZE, page_entry::context_depth, globals::context_depth, G, gcc_assert, page_entry::in_use_p, page_entry::num_free_objects, OBJECTS_IN_PAGE, page_entry::page, globals::pagesize, and save_in_use_p.

void debug_print_page_list ( int )

DEBUG_FUNCTION void debug_print_page_list ( )

Prints the page-entry for object size ORDER, for debugging.

References BITMAP_SIZE, page_entry::bytes, globals::bytes_mapped, page_entry::discarded, globals::free_pages, G, GGC_QUIRE_SIZE, page_entry::group, page_entry::next, NULL, OBJECT_SIZE, OBJECTS_PER_PAGE, page_entry::order, page_entry::page, PAGE_ALIGN, and globals::pagesize.

static void free_page ( struct page_entry * )

static

static void free_page ( )

static

For a page that is no longer needed, put it on the free page list.

 Mark the page as inaccessible.  Discard the handle to avoid handle
 leak.

     We cannot free a page from a context deeper than the current
     one.

     Put top element into freed slot.

static int ggc_allocated_p ( const void * )

static

static int ggc_allocated_p ( )

inlinestatic

Returns nonzero if P was allocated in GC'able memory.

Extract the level 1 and 2 indices.

void ggc_collect ( void )

Top level mark-and-sweep routine.

 Avoid frequent unnecessary work by skipping collection if the
 total allocations haven't expanded much since the last
 collection.

 Zero the total allocated bytes.  This will be recalculated in the
 sweep phase.

 Release the pages we freed the last time we collected, but didn't
 reuse in the interim.

 Indicate that we've seen collections at this context depth.

References ggc_pch_data::base, ggc_pch_data::d, PAGE_ALIGN, and ggc_pch_ondisk::totals.

Referenced by ggc_splay_alloc(), and gcc::pass_manager::pass_manager().

void ggc_free ( )

Release the memory for object P.

 Let valgrind know the object is free.

   Mark the object not-in-use.

       If the page is completely full, then it's supposed to
       be after all pages that aren't.  Since we've freed one
       object from a page that was full, we need to move the
       page to the head of the list.

       PE is the node we want to move.  Q is the previous node
       and P is the next node in the list.

           If PE was at the end of the list, then Q becomes the
           new end of the list.  If PE was not the end of the
           list, then we need to update the PREV field for P.

           Move PE to the head of the list.

       Reset the hint bit to point to the only free object.

size_t ggc_get_size ( )

Return the size of the gc-able object P.

void* ggc_internal_alloc_stat ( )

Allocate a chunk of memory of SIZE bytes. Its contents are undefined.

 If there are non-full pages for this size allocation, they are at
 the head of the list.

 If there is no page for this object size, or all pages in this
 context are full, allocate a new page.

     We can skip context depths, if we do, make sure we go all the
     way to the new depth.

     If this is the only entry, it's also the tail.  If it is not
     the only entry, then we must update the PREV pointer of the
     ENTRY (G.pages[order]) to point to our new page entry.

     Put new pages at the head of the page list.  By definition the
     entry at the head of the list always has a NULL pointer.

     For a new page, we know the word and bit positions (in the
     in_use bitmap) of the first available object &ndash; they're zero.

     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.

     If the hint didn't work, scan the bitmap from the beginning.

     Next time, try the next bit.

 Set the in-use 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.

     We have a new head for the list.

     We are moving ENTRY to the end of the page table list.
     The new page at the head of the list will have NULL in
     its PREV field and ENTRY will have NULL in its NEXT field.

     Append ENTRY to the tail of the list.

 Calculate the object's address.

 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.

 Keep track of how many bytes are being allocated.  This
 information is used in deciding when to collect.

 For timevar statistics.

int ggc_marked_p ( )

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.

Look up the page on which the object is alloced. If the object wasn't allocated by the collector, we'll probably die.

 Calculate the index of the object on the page; this is its bit
 position in the in_use_p bitmap.

Referenced by stringpool_statistics().

char* ggc_pch_alloc_object	(	struct ggc_pch_data *	,
		void *	,
		size_t	,
		bool
	)

Assuming that the objects really do end up at the address passed to ggc_pch_this_base, return the address of this object. The bool argument should be true if the object is a string.

void ggc_pch_count_object	(	struct ggc_pch_data *	,
		void *	,
		size_t	,
		bool
	)

The second parameter and third parameters give the address and size of an object. Update the ggc_pch_data structure with as much of that information as is necessary. The bool argument should be true if the object is a string.

void ggc_pch_finish ( )

void ggc_pch_prepare_write	(	struct ggc_pch_data *	,
		FILE *
	)

Write out any initial information required.

Nothing to do.

void ggc_pch_read ( )

 We've just read in a PCH file.  So, every object that used to be
 allocated is now free.

 Since we free all the allocated objects, the free list becomes
 useless.  Validate it now, which will also clear it.

 No object read from a PCH file should ever be freed.  So, set the
 context depth to 1, and set the depth of all the currently-allocated
 pages to be 1 too.  PCH pages will have depth 0.

 Allocate the appropriate page-table entries for the pages read from
 the PCH file.

     We start off by just adding all the new information to the
     end of the varrays, later, we will move the new information
     to the front of the varrays, as the PCH page tables are at
     context 0.

 Now, we update the various data structures that speed page table
 handling.

 Update the statistics.

void ggc_pch_this_base ( )

size_t ggc_pch_total_size ( )

void ggc_pch_write_object	(	struct ggc_pch_data *	,
		FILE *	,
		void *	,
		void *	,
		size_t	,
		bool
	)

Write out this object, including any padding. The last argument should be true if the object is a string.

 If SIZE is not the same as OBJECT_SIZE(order), then we need to pad the
 object out to OBJECT_SIZE(order).  This happens for strings.

     To speed small writes, we use a nulled-out array that's larger
     than most padding requests as the source for our null bytes.  This
     permits us to do the padding with fwrite() rather than fseek(), and
     limits the chance the OS may try to flush any outstanding writes.

         Larger than our buffer?  Just default to fseek.

void ggc_print_statistics ( void )

Statistics. Print allocation statistics.

 Clear the statistics.

 Make sure collection will really occur.

 Collect and print the statistics common across collectors.

 Release free pages so that we will not count the bytes allocated
 there as part of the total allocated memory.

 Collect some information about the various sizes of
 allocation.

     Skip empty entries.

     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.

References fatal_error().

static void ggc_recalculate_in_use_p ( page_entry * )

static

static void ggc_recalculate_in_use_p ( )

static

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.

 Because the past-the-end bit in in_use_p is always set, we
 pretend there is one additional object.

 Reset the free object count.

 Combine the IN_USE_P and SAVE_IN_USE_P arrays.

     Something is in use if it is marked, or if it was in use in a
     context further down the context stack.

     Decrement the free object count for every object allocated.

size_t ggc_round_alloc_size ( )

For a given size of memory requested for allocation, return the actual size that is going to be allocated.

static void ggc_round_alloc_size_1	(	size_t	requested_size,
		size_t *	size_order,
		size_t *	alloced_size
	)

static

For a given size of memory requested for allocation, return the actual size that is going to be allocated, as well as the size order.

int ggc_set_mark ( )

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.

 Look up the page on which the object is alloced.  If the object
 wasn't allocated by the collector, we'll probably die.

 Calculate the index of the object on the page; this is its bit
 position in the in_use_p bitmap.

 If the bit was previously set, skip it.

 Otherwise set it, and decrement the free object count.

Referenced by ggc_register_cache_tab().

void gt_ggc_m_S ( )

Mark function for strings.

 Look up the page on which the object is alloced.  .

 Calculate the index of the object on the page; this is its bit
 position in the in_use_p bitmap.  Note that because a char* might
 point to the middle of an object, we need special code here to
 make sure P points to the start of an object.

     Here we've seen a char* which does not point to the beginning
     of an allocated object.  We assume it points to the middle of
     a STRING_CST.

 If the bit was previously set, skip it.

 Otherwise set it, and decrement the free object count.

References globals::allocated, globals::debug_file, G, GGC_DEBUG_LEVEL, ggc_free_overhead(), HOST_BITS_PER_LONG, page_entry::in_use_p, lookup_page_table_entry(), page_entry::num_free_objects, OBJECT_SIZE, OFFSET_TO_BIT, page_entry::order, page_entry::page, page_entry::prev, and VALGRIND_DISCARD.

void gt_ggc_mx ( )

User-callable entry points for marking string X.

Nothing to do. Vectors of atomic types wrt GC do not need to be traversed.

References G, page_entry::next, NULL, order, globals::page_tails, globals::pages, and page_entry::prev.

void init_ggc ( void )

Initialize the ggc-mmap allocator.

 Initialize the object size table.

     If S is not a multiple of the MAX_ALIGNMENT, then round it up
     so that we're sure of getting aligned memory.

 Initialize the objects-per-page and inverse tables.

 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.

struct ggc_pch_data* init_ggc_pch ( void )

read

Return a new ggc_pch_data structure.

References page_entry::bytes.

static page_entry* lookup_page_table_entry ( const void * )

static

Referenced by gt_ggc_m_S(), and sweep_pages().

static page_entry* lookup_page_table_entry ( )

inlinestatic

Traverse the page table and find the entry for a page. Die (probably) if the object wasn't allocated via GC.

Extract the level 1 and 2 indices.

References globals::bytes_mapped, FATAL_EXIT_CODE, G, MAP_FAILED, NULL, page_entry::page, and pref.

static void move_ptes_to_front	(	int	,
		int
	)

static

static void move_ptes_to_front ( )

static

Move the PCH PTE entries just added to the end of by_depth, to the front.

 First, we swap the new entries to the front of the varrays.

 Now update all the index_by_depth fields.

 And last, we update the depth pointers in G.depth.  The first
 entry is already 0, and context 0 entries always start at index
 0, so there is nothing to update in the first slot.  We need a
 second slot, only if we have old ptes, and if we do, they start
 at index count_new_page_tables.

static size_t page_group_index	(	char *	,
		char *
	)

static

static size_t page_group_index ( )

inlinestatic

Compute the index for this page into the page group.

References G, NULL, and globals::pagesize.

static void push_by_depth	(	page_entry *	,
		unsigned long *
	)

static

static void push_by_depth ( )

inlinestatic

Push an entry onto G.by_depth and G.save_in_use.

static void push_depth ( unsigned int )

static

static void push_depth ( )

inlinestatic

Push an entry onto G.depth.

References G, and globals::lookup.

static void release_pages ( )

static

Release the free page cache to the system.

Remove all pages from free page groups from the list.

 Remove all free page groups, and release the storage.

static void set_page_group_in_use	(	page_group *	,
		char *
	)

static

static void set_page_group_in_use ( )

inlinestatic

Set and clear the in_use bit for this page in the page group.

References page_entry::bytes, G, globals::lg_pagesize, page_entry::next, page_entry::order, order, page_entry::page, and globals::pagesize.

static void set_page_table_entry	(	void *	,
		page_entry *
	)

static

static void set_page_table_entry ( )

static

Set the page table entry for a page.

Extract the level 1 and 2 indices.

static void sweep_pages ( )

static

Free all empty pages. Partially empty pages need no attention because the `mark' bit doubles as an `unused' bit.

     The last page-entry to consider, regardless of entries
     placed at the end of the list.

         Loop until all entries have been examined.

         Add all live objects on this page to the count of
         allocated memory.

         Only objects on pages in the topmost context should get
         collected.

         Remove the page if it's empty.

             If P was the first page in the list, then NEXT
             becomes the new first page in the list, otherwise
             splice P out of the forward pointers.

             Splice P out of the back pointers too.

             Are we removing the last element?

         If the page is full, move it to the end.

             Don't move it if it's already at the end.

                 Move p to the end of the list.

                 Update the tail pointer...

                 ... and the head pointer, if necessary.

                 And update the backpointer in NEXT if necessary.

         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.

             Update the backchain in the next node if it exists.

             Move P to the head of the list.

             Update the head pointer.

             Are we moving the last element?

     Now, restore the in_use_p vectors for any pages from contexts
     other than the current one.

References page_entry::context_depth, globals::context_depth, G, gcc_assert, HOST_BITS_PER_LONG, page_entry::in_use_p, lookup_page_table_entry(), NULL, OFFSET_TO_BIT, page_entry::order, and page_entry::page.

Variable Documentation

const size_t extra_order_size_table[]

static

Initial value:

 {
  
  MAX_ALIGNMENT * 3,
  MAX_ALIGNMENT * 5,
  MAX_ALIGNMENT * 6,
  MAX_ALIGNMENT * 7,
  MAX_ALIGNMENT * 9,
  MAX_ALIGNMENT * 10,
  MAX_ALIGNMENT * 11,
  MAX_ALIGNMENT * 12,
  MAX_ALIGNMENT * 13,
  MAX_ALIGNMENT * 14,
  MAX_ALIGNMENT * 15,
  sizeof (struct tree_decl_non_common),
  sizeof (struct tree_field_decl),
  sizeof (struct tree_parm_decl),
  sizeof (struct tree_var_decl),
  sizeof (struct tree_type_non_common),
  sizeof (struct function),
  sizeof (struct basic_block_def),
  sizeof (struct cgraph_node),
  sizeof (struct loop),
}

The Ith entry is the maximum size of an object to be stored in the Ith extra order. Adding a new entry to this array is the only thing you need to do to add a new special allocation size.

struct globals G

static

Referenced by clear_marks(), compute_inverse(), debug_print_page_list(), gt_ggc_m_S(), gt_ggc_mx(), lookup_page_table_entry(), page_group_index(), push_depth(), set_page_group_in_use(), and sweep_pages().

struct { ... } inverse_table[NUM_ORDERS]

The Ith entry is a pair of numbers (mult, shift) such that ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32, for all k evenly divisible by OBJECT_SIZE(I).

size_t mult

Referenced by coalesce_cost_bb(), and update_costs_from_allocno().

size_t object_size_table[NUM_ORDERS]

static

The Ith entry is the size of an object on a page of order I.

unsigned objects_per_page_table[NUM_ORDERS]

static

The Ith entry is the number of objects on a page or order I.

unsigned int shift

Referenced by bit_value_unop_1(), expand_mult_highpart_adjust(), find_shift_sequence(), output_constant(), output_constant_def(), and reg_loc_descriptor().

unsigned char size_lookup[NUM_SIZE_LOOKUP]

static

Data Structures

Macros

Typedefs

Functions

Variables

Macro Definition Documentation

Typedef Documentation

Function Documentation

Variable Documentation