--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/cardTable.hpp Fri Mar 02 21:00:12 2018 +0100
@@ -0,0 +1,266 @@
+/*
+ * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_CARDTABLE_HPP
+#define SHARE_VM_GC_SHARED_CARDTABLE_HPP
+
+#include "memory/allocation.hpp"
+#include "memory/memRegion.hpp"
+#include "oops/oopsHierarchy.hpp"
+#include "utilities/align.hpp"
+
+class CardTable: public CHeapObj<mtGC> {
+ friend class VMStructs;
+protected:
+ // The declaration order of these const fields is important; see the
+ // constructor before changing.
+ const bool _scanned_concurrently;
+ 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
+ jbyte* _byte_map_base;
+
+ 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;
+
+ 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);
+
+ // 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;
+
+ // Some barrier sets create tables whose elements correspond to parts of
+ // the heap; the CardTableModRefBS is an example. Such barrier sets will
+ // normally reserve space for such tables, and commit parts of the table
+ // "covering" parts of the heap that are committed. At most one covered
+ // region per generation is needed.
+ static const int _max_covered_regions = 2;
+
+ 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);
+
+public:
+ CardTable(MemRegion whole_heap, bool conc_scan);
+ virtual ~CardTable();
+ virtual void initialize();
+
+ // 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.
+ }
+
+ // *** Barrier set functions.
+
+ // 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_up(covered_words, card_size_in_words);
+ return words / card_size_in_words + 1;
+ }
+
+ // 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);
+
+ // 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);
+ }
+
+ // 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;
+ }
+
+ virtual void invalidate(MemRegion mr);
+ void clear(MemRegion mr);
+ void dirty(MemRegion mr);
+
+ // 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. p: " PTR_FORMAT
+ " _byte_map: " PTR_FORMAT " _byte_map + _byte_map_size: " PTR_FORMAT,
+ p2i(p), p2i(_byte_map), p2i(_byte_map + _byte_map_size));
+ 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;
+ }
+
+ // 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;
+ }
+
+ const jbyte* byte_for_index(const size_t card_index) const {
+ return _byte_map + card_index;
+ }
+
+ // Resize one of the regions covered by the remembered set.
+ virtual void resize_covered_region(MemRegion new_region);
+
+ // *** 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);
+
+ // Constants
+ enum SomePublicConstants {
+ card_shift = 9,
+ card_size = 1 << card_shift,
+ card_size_in_words = card_size / sizeof(HeapWord)
+ };
+
+ static jbyte clean_card_val() { return clean_card; }
+ static jbyte clean_card_mask_val() { return clean_card_mask; }
+ static jbyte dirty_card_val() { return dirty_card; }
+ static jbyte claimed_card_val() { return claimed_card; }
+ static jbyte precleaned_card_val() { return precleaned_card; }
+ static jbyte deferred_card_val() { return deferred_card; }
+ static intptr_t clean_card_row_val() { return clean_card_row; }
+
+ // 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() const { return _byte_map_base; }
+ bool scanned_concurrently() const { return _scanned_concurrently; }
+
+ virtual bool is_in_young(oop obj) const = 0;
+
+ // Print a description of the memory for the card table
+ 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;
+};
+
+#endif // SHARE_VM_GC_SHARED_CARDTABLE_HPP