0N/A

0N/A#ifndef SHARE_VM_MEMORY_CARDTABLEMODREFBS_HPP

0N/A#define SHARE_VM_MEMORY_CARDTABLEMODREFBS_HPP

0N/A

0N/A#include "memory/modRefBarrierSet.hpp"

0N/A#include "oops/oop.hpp"

0N/A#include "oops/oop.inline2.hpp"

0N/A

0N/A

0N/A

0N/Aclass Generation;

0N/Aclass OopsInGenClosure;

0N/Aclass DirtyCardToOopClosure;

0N/Aclass ClearNoncleanCardWrapper;

0N/A

0N/Aclass CardTableModRefBS: public ModRefBarrierSet {

0N/A // Some classes get to look at some private stuff.

0N/A friend class BytecodeInterpreter;

0N/A friend class VMStructs;

0N/A friend class CardTableRS;

0N/A friend class CheckForUnmarkedOops; // Needs access to raw card bytes.

0N/A friend class SharkBuilder;

0N/A#ifndef PRODUCT

0N/A // For debugging.

0N/A friend class GuaranteeNotModClosure;

0N/A#endif

0N/A protected:

0N/A

0N/A enum CardValues {

0N/A clean_card = -1,

0N/A // The mask contains zeros in places for all other values.

0N/A clean_card_mask = clean_card - 31,

0N/A

0N/A dirty_card = 0,

0N/A precleaned_card = 1,

0N/A claimed_card = 2,

0N/A deferred_card = 4,

0N/A last_card = 8,

0N/A CT_MR_BS_last_reserved = 16

0N/A };

0N/A

0N/A // a word's worth (row) of clean card values

0N/A static const intptr_t clean_card_row = (intptr_t)(-1);

0N/A

0N/A // dirty and precleaned are equivalent wrt younger_refs_iter.

0N/A static bool card_is_dirty_wrt_gen_iter(jbyte cv) {

0N/A return cv == dirty_card || cv == precleaned_card;

0N/A }

0N/A

0N/A // Returns "true" iff the value "cv" will cause the card containing it

0N/A // to be scanned in the current traversal. May be overridden by

0N/A // subtypes.

0N/A virtual bool card_will_be_scanned(jbyte cv) {

0N/A return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv);

0N/A }

0N/A

0N/A // Returns "true" iff the value "cv" may have represented a dirty card at

0N/A // some point.

0N/A virtual bool card_may_have_been_dirty(jbyte cv) {

0N/A return card_is_dirty_wrt_gen_iter(cv);

0N/A }

0N/A

0N/A // The declaration order of these const fields is important; see the

0N/A // constructor before changing.

0N/A const MemRegion _whole_heap; // the region covered by the card table

0N/A const size_t _guard_index; // index of very last element in the card

0N/A // table; it is set to a guard value

0N/A // (last_card) and should never be modified

0N/A const size_t _last_valid_index; // index of the last valid element

0N/A const size_t _page_size; // page size used when mapping _byte_map

0N/A const size_t _byte_map_size; // in bytes

0N/A jbyte* _byte_map; // the card marking array

0N/A

0N/A int _cur_covered_regions;

0N/A // The covered regions should be in address order.

0N/A MemRegion* _covered;

0N/A // The committed regions correspond one-to-one to the covered regions.

0N/A // They represent the card-table memory that has been committed to service

0N/A // the corresponding covered region. It may be that committed region for

0N/A // one covered region corresponds to a larger region because of page-size

0N/A // roundings. Thus, a committed region for one covered region may

0N/A // actually extend onto the card-table space for the next covered region.

0N/A MemRegion* _committed;

0N/A

0N/A // The last card is a guard card, and we commit the page for it so

0N/A // we can use the card for verification purposes. We make sure we never

0N/A // uncommit the MemRegion for that page.

0N/A MemRegion _guard_region;

0N/A

0N/A protected:

0N/A // Initialization utilities; covered_words is the size of the covered region

0N/A // in, um, words.

0N/A inline size_t cards_required(size_t covered_words);

0N/A inline size_t compute_byte_map_size();

0N/A

0N/A // Finds and return the index of the region, if any, to which the given

0N/A // region would be contiguous. If none exists, assign a new region and

0N/A // returns its index. Requires that no more than the maximum number of

0N/A // covered regions defined in the constructor are ever in use.

0N/A int find_covering_region_by_base(HeapWord* base);

0N/A

0N/A // Same as above, but finds the region containing the given address

0N/A // instead of starting at a given base address.

0N/A int find_covering_region_containing(HeapWord* addr);

0N/A

0N/A // Resize one of the regions covered by the remembered set.

0N/A void resize_covered_region(MemRegion new_region);

0N/A

0N/A // Returns the leftmost end of a committed region corresponding to a

0N/A // covered region before covered region "ind", or else "NULL" if "ind" is

0N/A // the first covered region.

0N/A HeapWord* largest_prev_committed_end(int ind) const;

0N/A

0N/A // Returns the part of the region mr that doesn't intersect with

0N/A // any committed region other than self. Used to prevent uncommitting

0N/A // regions that are also committed by other regions. Also protects

0N/A // against uncommitting the guard region.

0N/A MemRegion committed_unique_to_self(int self, MemRegion mr) const;

0N/A

0N/A // Mapping from address to card marking array entry

0N/A jbyte* byte_for(const void* p) const {

0N/A assert(_whole_heap.contains(p),

0N/A err_msg("Attempt to access p = "PTR_FORMAT" out of bounds of "

0N/A " card marking array's _whole_heap = ["PTR_FORMAT","PTR_FORMAT")",

0N/A p, _whole_heap.start(), _whole_heap.end()));

0N/A jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift];

0N/A assert(result >= _byte_map && result < _byte_map + _byte_map_size,

0N/A "out of bounds accessor for card marking array");

0N/A return result;

0N/A }

0N/A

0N/A // The card table byte one after the card marking array

0N/A // entry for argument address. Typically used for higher bounds

0N/A // for loops iterating through the card table.

0N/A jbyte* byte_after(const void* p) const {

0N/A return byte_for(p) + 1;

0N/A }

0N/A

0N/A // Iterate over the portion of the card-table which covers the given

// region mr in the given space and apply cl to any dirty sub-regions

// of mr. Dirty cards are _not_ cleared by the iterator method itself,

// but closures may arrange to do so on their own should they so wish.

void non_clean_card_iterate_serial(MemRegion mr, MemRegionClosure* cl);

// A variant of the above that will operate in a parallel mode if

// worker threads are available, and clear the dirty cards as it

// processes them.

// XXX ??? MemRegionClosure above vs OopsInGenClosure below XXX

// XXX some new_dcto_cl's take OopClosure's, plus as above there are

// some MemRegionClosures. Clean this up everywhere. XXX

void non_clean_card_iterate_possibly_parallel(Space* sp, MemRegion mr,

OopsInGenClosure* cl, CardTableRS* ct);

private:

// Work method used to implement non_clean_card_iterate_possibly_parallel()

// above in the parallel case.

void non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr,

OopsInGenClosure* cl, CardTableRS* ct,

int n_threads);

protected:

// Dirty the bytes corresponding to "mr" (not all of which must be

// covered.)

void dirty_MemRegion(MemRegion mr);

// Clear (to clean_card) the bytes entirely contained within "mr" (not

// all of which must be covered.)

void clear_MemRegion(MemRegion mr);

// *** Support for parallel card scanning.

// This is an array, one element per covered region of the card table.

// Each entry is itself an array, with one element per chunk in the

// covered region. Each entry of these arrays is the lowest non-clean

// card of the corresponding chunk containing part of an object from the

// previous chunk, or else NULL.

typedef jbyte* CardPtr;

typedef CardPtr* CardArr;

CardArr* _lowest_non_clean;

size_t* _lowest_non_clean_chunk_size;

uintptr_t* _lowest_non_clean_base_chunk_index;

int* _last_LNC_resizing_collection;

// Initializes "lowest_non_clean" to point to the array for the region

// covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk

// index of the corresponding to the first element of that array.

// Ensures that these arrays are of sufficient size, allocating if necessary.

// May be called by several threads concurrently.

void get_LNC_array_for_space(Space* sp,

jbyte**& lowest_non_clean,

uintptr_t& lowest_non_clean_base_chunk_index,

size_t& lowest_non_clean_chunk_size);

// Returns the number of chunks necessary to cover "mr".

size_t chunks_to_cover(MemRegion mr) {

return (size_t)(addr_to_chunk_index(mr.last()) -

addr_to_chunk_index(mr.start()) + 1);

}

// Returns the index of the chunk in a stride which

// covers the given address.

uintptr_t addr_to_chunk_index(const void* addr) {

uintptr_t card = (uintptr_t) byte_for(addr);

return card / ParGCCardsPerStrideChunk;

}

// Apply cl, which must either itself apply dcto_cl or be dcto_cl,

// to the cards in the stride (of n_strides) within the given space.

void process_stride(Space* sp,

MemRegion used,

jint stride, int n_strides,

OopsInGenClosure* cl,

CardTableRS* ct,

jbyte** lowest_non_clean,

uintptr_t lowest_non_clean_base_chunk_index,

size_t lowest_non_clean_chunk_size);

// Makes sure that chunk boundaries are handled appropriately, by

// adjusting the min_done of dcto_cl, and by using a special card-table

// value to indicate how min_done should be set.

void process_chunk_boundaries(Space* sp,

DirtyCardToOopClosure* dcto_cl,

MemRegion chunk_mr,

MemRegion used,

jbyte** lowest_non_clean,

uintptr_t lowest_non_clean_base_chunk_index,

size_t lowest_non_clean_chunk_size);

public:

// Constants

enum SomePublicConstants {

card_shift = 9,

card_size = 1 << card_shift,

card_size_in_words = card_size / sizeof(HeapWord)

};

static int clean_card_val() { return clean_card; }

static int clean_card_mask_val() { return clean_card_mask; }

static int dirty_card_val() { return dirty_card; }

static int claimed_card_val() { return claimed_card; }

static int precleaned_card_val() { return precleaned_card; }

static int deferred_card_val() { return deferred_card; }

// For RTTI simulation.

bool is_a(BarrierSet::Name bsn) {

return bsn == BarrierSet::CardTableModRef || ModRefBarrierSet::is_a(bsn);

}

CardTableModRefBS(MemRegion whole_heap, int max_covered_regions);

// *** Barrier set functions.

bool has_write_ref_pre_barrier() { return false; }

inline bool write_ref_needs_barrier(void* field, oop new_val) {

// Note that this assumes the perm gen is the highest generation

// in the address space

return new_val != NULL && !new_val->is_perm();

}

// Record a reference update. Note that these versions are precise!

// The scanning code has to handle the fact that the write barrier may be

// either precise or imprecise. We make non-virtual inline variants of

// these functions here for performance.

protected:

void write_ref_field_work(oop obj, size_t offset, oop newVal);

virtual void write_ref_field_work(void* field, oop newVal);

public:

bool has_write_ref_array_opt() { return true; }

bool has_write_region_opt() { return true; }

inline void inline_write_region(MemRegion mr) {

dirty_MemRegion(mr);

}

protected:

void write_region_work(MemRegion mr) {

inline_write_region(mr);

}

public:

inline void inline_write_ref_array(MemRegion mr) {

dirty_MemRegion(mr);

}

protected:

void write_ref_array_work(MemRegion mr) {

inline_write_ref_array(mr);

}

public:

bool is_aligned(HeapWord* addr) {

return is_card_aligned(addr);

}

// *** Card-table-barrier-specific things.

template <class T> inline void inline_write_ref_field_pre(T* field, oop newVal) {}

template <class T> inline void inline_write_ref_field(T* field, oop newVal) {

jbyte* byte = byte_for((void*)field);

*byte = dirty_card;

}

// These are used by G1, when it uses the card table as a temporary data

// structure for card claiming.

bool is_card_dirty(size_t card_index) {

return _byte_map[card_index] == dirty_card_val();

}

void mark_card_dirty(size_t card_index) {

_byte_map[card_index] = dirty_card_val();

}

bool is_card_claimed(size_t card_index) {

jbyte val = _byte_map[card_index];

return (val & (clean_card_mask_val() | claimed_card_val())) == claimed_card_val();

}

void set_card_claimed(size_t card_index) {

jbyte val = _byte_map[card_index];

if (val == clean_card_val()) {

val = (jbyte)claimed_card_val();

} else {

val |= (jbyte)claimed_card_val();

}

_byte_map[card_index] = val;

}

bool claim_card(size_t card_index);

bool is_card_clean(size_t card_index) {

return _byte_map[card_index] == clean_card_val();

}

bool is_card_deferred(size_t card_index) {

jbyte val = _byte_map[card_index];

return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val();

}

bool mark_card_deferred(size_t card_index);

// Card marking array base (adjusted for heap low boundary)

// This would be the 0th element of _byte_map, if the heap started at 0x0.

// But since the heap starts at some higher address, this points to somewhere

// before the beginning of the actual _byte_map.

jbyte* byte_map_base;

// Return true if "p" is at the start of a card.

bool is_card_aligned(HeapWord* p) {

jbyte* pcard = byte_for(p);

return (addr_for(pcard) == p);

}

HeapWord* align_to_card_boundary(HeapWord* p) {

jbyte* pcard = byte_for(p + card_size_in_words - 1);

return addr_for(pcard);

}

// The kinds of precision a CardTableModRefBS may offer.

enum PrecisionStyle {

Precise,

ObjHeadPreciseArray

};

// Tells what style of precision this card table offers.

PrecisionStyle precision() {

return ObjHeadPreciseArray; // Only one supported for now.

}

// ModRefBS functions.

virtual void invalidate(MemRegion mr, bool whole_heap = false);

void clear(MemRegion mr);

void dirty(MemRegion mr);

// *** Card-table-RemSet-specific things.

// Invoke "cl.do_MemRegion" on a set of MemRegions that collectively

// includes all the modified cards (expressing each card as a

// MemRegion). Thus, several modified cards may be lumped into one

// region. The regions are non-overlapping, and are visited in

// *decreasing* address order. (This order aids with imprecise card

// marking, where a dirty card may cause scanning, and summarization

// marking, of objects that extend onto subsequent cards.)

void mod_card_iterate(MemRegionClosure* cl) {

non_clean_card_iterate_serial(_whole_heap, cl);

}

// Like the "mod_cards_iterate" above, except only invokes the closure

// for cards within the MemRegion "mr" (which is required to be

// card-aligned and sized.)

void mod_card_iterate(MemRegion mr, MemRegionClosure* cl) {

non_clean_card_iterate_serial(mr, cl);

}

static uintx ct_max_alignment_constraint();

// Apply closure "cl" to the dirty cards containing some part of

// MemRegion "mr".

void dirty_card_iterate(MemRegion mr, MemRegionClosure* cl);

// Return the MemRegion corresponding to the first maximal run

// of dirty cards lying completely within MemRegion mr.

// If reset is "true", then sets those card table entries to the given

// value.

MemRegion dirty_card_range_after_reset(MemRegion mr, bool reset,

int reset_val);

// Provide read-only access to the card table array.

const jbyte* byte_for_const(const void* p) const {

return byte_for(p);

}

const jbyte* byte_after_const(const void* p) const {

return byte_after(p);

}

// Mapping from card marking array entry to address of first word

HeapWord* addr_for(const jbyte* p) const {

assert(p >= _byte_map && p < _byte_map + _byte_map_size,

"out of bounds access to card marking array");

size_t delta = pointer_delta(p, byte_map_base, sizeof(jbyte));

HeapWord* result = (HeapWord*) (delta << card_shift);

assert(_whole_heap.contains(result),

err_msg("Returning result = "PTR_FORMAT" out of bounds of "

" card marking array's _whole_heap = ["PTR_FORMAT","PTR_FORMAT")",

result, _whole_heap.start(), _whole_heap.end()));

return result;

}

// Mapping from address to card marking array index.

size_t index_for(void* p) {

assert(_whole_heap.contains(p),

err_msg("Attempt to access p = "PTR_FORMAT" out of bounds of "

" card marking array's _whole_heap = ["PTR_FORMAT","PTR_FORMAT")",

p, _whole_heap.start(), _whole_heap.end()));

return byte_for(p) - _byte_map;

}

const jbyte* byte_for_index(const size_t card_index) const {

return _byte_map + card_index;

}

// Print a description of the memory for the barrier set

virtual void print_on(outputStream* st) const;

void verify();

void verify_guard();

// val_equals -> it will check that all cards covered by mr equal val

// !val_equals -> it will check that all cards covered by mr do not equal val

void verify_region(MemRegion mr, jbyte val, bool val_equals) PRODUCT_RETURN;

void verify_not_dirty_region(MemRegion mr) PRODUCT_RETURN;

void verify_dirty_region(MemRegion mr) PRODUCT_RETURN;

static size_t par_chunk_heapword_alignment() {

return ParGCCardsPerStrideChunk * card_size_in_words;

}

};

class CardTableRS;

class CardTableModRefBSForCTRS: public CardTableModRefBS {

CardTableRS* _rs;

protected:

bool card_will_be_scanned(jbyte cv);

bool card_may_have_been_dirty(jbyte cv);

public:

CardTableModRefBSForCTRS(MemRegion whole_heap,

int max_covered_regions) :

CardTableModRefBS(whole_heap, max_covered_regions) {}

void set_CTRS(CardTableRS* rs) { _rs = rs; }

};

#endif // SHARE_VM_MEMORY_CARDTABLEMODREFBS_HPP