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src/share/vm/gc/shared/cardTableModRefBS.hpp
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rev 12906 : [mq]: gc_interface
@@ -24,11 +24,12 @@
#ifndef SHARE_VM_GC_SHARED_CARDTABLEMODREFBS_HPP
#define SHARE_VM_GC_SHARED_CARDTABLEMODREFBS_HPP
#include "gc/shared/modRefBarrierSet.hpp"
-#include "oops/oop.hpp"
+
+class CardTable;
// This kind of "BarrierSet" allows a "CollectedHeap" to detect and
// enumerate ref fields that have been modified (since the last
// enumeration.)
@@ -42,294 +43,101 @@
class CardTableModRefBS: public ModRefBarrierSet {
// Some classes get to look at some private stuff.
friend class VMStructs;
protected:
+ // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2
+ // or INCLUDE_JVMCI is being used
+ bool _defer_initial_card_mark;
+ bool _can_elide_tlab_store_barriers;
+ CardTable* _card_table;
- enum CardValues {
- clean_card = -1,
- // The mask contains zeros in places for all other values.
- clean_card_mask = clean_card - 31,
-
- dirty_card = 0,
- precleaned_card = 1,
- claimed_card = 2,
- deferred_card = 4,
- last_card = 8,
- CT_MR_BS_last_reserved = 16
- };
-
- // a word's worth (row) of clean card values
- static const intptr_t clean_card_row = (intptr_t)(-1);
-
- // The declaration order of these const fields is important; see the
- // constructor before changing.
- const MemRegion _whole_heap; // the region covered by the card table
- size_t _guard_index; // index of very last element in the card
- // table; it is set to a guard value
- // (last_card) and should never be modified
- size_t _last_valid_index; // index of the last valid element
- const size_t _page_size; // page size used when mapping _byte_map
- size_t _byte_map_size; // in bytes
- jbyte* _byte_map; // the card marking array
-
- int _cur_covered_regions;
- // The covered regions should be in address order.
- MemRegion* _covered;
- // The committed regions correspond one-to-one to the covered regions.
- // They represent the card-table memory that has been committed to service
- // the corresponding covered region. It may be that committed region for
- // one covered region corresponds to a larger region because of page-size
- // roundings. Thus, a committed region for one covered region may
- // actually extend onto the card-table space for the next covered region.
- MemRegion* _committed;
-
- // The last card is a guard card, and we commit the page for it so
- // we can use the card for verification purposes. We make sure we never
- // uncommit the MemRegion for that page.
- MemRegion _guard_region;
-
- protected:
- inline size_t compute_byte_map_size();
-
- // Finds and return the index of the region, if any, to which the given
- // region would be contiguous. If none exists, assign a new region and
- // returns its index. Requires that no more than the maximum number of
- // covered regions defined in the constructor are ever in use.
- int find_covering_region_by_base(HeapWord* base);
-
- // Same as above, but finds the region containing the given address
- // instead of starting at a given base address.
- int find_covering_region_containing(HeapWord* addr);
-
- // Resize one of the regions covered by the remembered set.
- virtual void resize_covered_region(MemRegion new_region);
-
- // Returns the leftmost end of a committed region corresponding to a
- // covered region before covered region "ind", or else "NULL" if "ind" is
- // the first covered region.
- HeapWord* largest_prev_committed_end(int ind) const;
-
- // Returns the part of the region mr that doesn't intersect with
- // any committed region other than self. Used to prevent uncommitting
- // regions that are also committed by other regions. Also protects
- // against uncommitting the guard region.
- MemRegion committed_unique_to_self(int self, MemRegion mr) const;
-
- // Mapping from address to card marking array entry
- jbyte* byte_for(const void* p) const {
- assert(_whole_heap.contains(p),
- "Attempt to access p = " PTR_FORMAT " out of bounds of "
- " card marking array's _whole_heap = [" PTR_FORMAT "," PTR_FORMAT ")",
- p2i(p), p2i(_whole_heap.start()), p2i(_whole_heap.end()));
- jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift];
- assert(result >= _byte_map && result < _byte_map + _byte_map_size,
- "out of bounds accessor for card marking array");
- return result;
- }
-
- // The card table byte one after the card marking array
- // entry for argument address. Typically used for higher bounds
- // for loops iterating through the card table.
- jbyte* byte_after(const void* p) const {
- return byte_for(p) + 1;
- }
-
- 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);
+ CardTableModRefBS(CardTable* card_table, const BarrierSet::FakeRtti& fake_rtti);
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; }
-
- virtual void initialize();
-
- // *** Barrier set functions.
-
- bool has_write_ref_pre_barrier() { return false; }
-
- // Initialization utilities; covered_words is the size of the covered region
- // in, um, words.
- inline size_t cards_required(size_t covered_words) {
- // Add one for a guard card, used to detect errors.
- const size_t words = align_size_up(covered_words, card_size_in_words);
- return words / card_size_in_words + 1;
- }
+ CardTableModRefBS(CardTable* card_table);
+ ~CardTableModRefBS();
-protected:
+ void initialize();
- CardTableModRefBS(MemRegion whole_heap, const BarrierSet::FakeRtti& fake_rtti);
- ~CardTableModRefBS();
+ CardTable* card_table() const { return _card_table; }
// 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.
- void write_ref_field_work(oop obj, size_t offset, oop newVal);
- virtual void write_ref_field_work(void* field, oop newVal, bool release);
-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 <DecoratorSet decorators>
+ void write_ref_field_post(void* field, oop newVal);
- 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, bool release);
-
- // 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_clean(size_t card_index) {
- return _byte_map[card_index] == clean_card_val();
- }
-
- // 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.
- }
+ virtual void write_region(MemRegion mr);
+ virtual void write_ref_array_region(MemRegion mr);
// ModRefBS functions.
virtual void invalidate(MemRegion mr);
- void clear(MemRegion mr);
- void dirty(MemRegion mr);
-
- // *** Card-table-RemSet-specific things.
- 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);
- }
+ // Print a description of the memory for the barrier set
+ virtual void print_on(outputStream* st) const;
- // 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),
- "Returning result = " PTR_FORMAT " out of bounds of "
- " card marking array's _whole_heap = [" PTR_FORMAT "," PTR_FORMAT ")",
- p2i(result), p2i(_whole_heap.start()), p2i(_whole_heap.end()));
- return result;
- }
+ // ReduceInitialCardMarks
+ void new_deferred_store_barrier(JavaThread* thread, oop new_obj);
- // Mapping from address to card marking array index.
- size_t index_for(void* p) {
- assert(_whole_heap.contains(p),
- "Attempt to access p = " PTR_FORMAT " out of bounds of "
- " card marking array's _whole_heap = [" PTR_FORMAT "," PTR_FORMAT ")",
- p2i(p), p2i(_whole_heap.start()), p2i(_whole_heap.end()));
- return byte_for(p) - _byte_map;
+ // If the CollectedHeap was asked to defer a store barrier above,
+ // this informs it to flush such a deferred store barrier to the
+ // remembered set.
+ void flush_deferred_store_barrier(JavaThread* thread);
+
+ // Can a compiler initialize a new object without store barriers?
+ // This permission only extends from the creation of a new object
+ // via a TLAB up to the first subsequent safepoint. If such permission
+ // is granted for this heap type, the compiler promises to call
+ // defer_store_barrier() below on any slow path allocation of
+ // a new object for which such initializing store barriers will
+ // have been elided. G1, like CMS, allows this, but should be
+ // ready to provide a compensating write barrier as necessary
+ // if that storage came out of a non-young region. The efficiency
+ // of this implementation depends crucially on being able to
+ // answer very efficiently in constant time whether a piece of
+ // storage in the heap comes from a young region or not.
+ // See ReduceInitialCardMarks.
+ virtual bool can_elide_tlab_store_barriers() const { return true; }
+
+ // If a compiler is eliding store barriers for TLAB-allocated objects,
+ // we will be informed of a slow-path allocation by a call
+ // to new_deferred_store_barrier() above. Such a call precedes the
+ // initialization of the object itself, and no post-store-barriers will
+ // be issued. Some heap types require that the barrier strictly follows
+ // the initializing stores. (This is currently implemented by deferring the
+ // barrier until the next slow-path allocation or gc-related safepoint.)
+ // This interface answers whether a particular barrier type needs the card
+ // mark to be thus strictly sequenced after the stores.
+ virtual bool card_mark_must_follow_store() const;
+
+ void on_slowpath_allocation(JavaThread* thread, oop new_obj) {
+ if (_can_elide_tlab_store_barriers) {
+ new_deferred_store_barrier(thread, new_obj);
}
-
- const jbyte* byte_for_index(const size_t card_index) const {
- return _byte_map + card_index;
}
+ void on_destroy_thread(JavaThread* thread);
+ void make_parsable(JavaThread* thread);
- // Print a description of the memory for the barrier set
- virtual void print_on(outputStream* st) const;
-
- void verify();
- void verify_guard();
+protected:
+ virtual BarrierSetCodeGen* make_code_gen();
+ virtual C1BarrierSetCodeGen* make_c1_code_gen();
+ virtual C2BarrierSetCodeGen* make_c2_code_gen();
- // 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;
+public:
+ template <DecoratorSet decorators>
+ class AccessBarrier: public ModRefBarrierSet::AccessBarrier<decorators, CardTableModRefBS> {};
};
template<>
-struct BarrierSet::GetName<CardTableModRefBS> {
+struct BSTypeToName<CardTableModRefBS> {
static const BarrierSet::Name value = BarrierSet::CardTableModRef;
};
+template<>
+struct BSNameToType<BarrierSet::CardTableModRef> {
+ typedef CardTableModRefBS type;
+};
#endif // SHARE_VM_GC_SHARED_CARDTABLEMODREFBS_HPP
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