d7310fb0f7
Shark is a JIT compiler for Zero that uses the LLVM compiler infrastructure. Reviewed-by: kvn, twisti
493 lines
18 KiB
C++
493 lines
18 KiB
C++
/*
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* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY 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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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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// This kind of "BarrierSet" allows a "CollectedHeap" to detect and
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// enumerate ref fields that have been modified (since the last
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// enumeration.)
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// As it currently stands, this barrier is *imprecise*: when a ref field in
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// an object "o" is modified, the card table entry for the card containing
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// the head of "o" is dirtied, not necessarily the card containing the
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// modified field itself. For object arrays, however, the barrier *is*
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// precise; only the card containing the modified element is dirtied.
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// Any MemRegionClosures used to scan dirty cards should take these
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// considerations into account.
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class Generation;
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class OopsInGenClosure;
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class DirtyCardToOopClosure;
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class CardTableModRefBS: public ModRefBarrierSet {
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// Some classes get to look at some private stuff.
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friend class BytecodeInterpreter;
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friend class VMStructs;
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friend class CardTableRS;
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friend class CheckForUnmarkedOops; // Needs access to raw card bytes.
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friend class SharkBuilder;
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#ifndef PRODUCT
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// For debugging.
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friend class GuaranteeNotModClosure;
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#endif
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protected:
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enum CardValues {
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clean_card = -1,
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// The mask contains zeros in places for all other values.
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clean_card_mask = clean_card - 31,
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dirty_card = 0,
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precleaned_card = 1,
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claimed_card = 2,
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deferred_card = 4,
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last_card = 8,
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CT_MR_BS_last_reserved = 16
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};
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// dirty and precleaned are equivalent wrt younger_refs_iter.
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static bool card_is_dirty_wrt_gen_iter(jbyte cv) {
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return cv == dirty_card || cv == precleaned_card;
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}
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// Returns "true" iff the value "cv" will cause the card containing it
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// to be scanned in the current traversal. May be overridden by
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// subtypes.
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virtual bool card_will_be_scanned(jbyte cv) {
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return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv);
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}
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// Returns "true" iff the value "cv" may have represented a dirty card at
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// some point.
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virtual bool card_may_have_been_dirty(jbyte cv) {
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return card_is_dirty_wrt_gen_iter(cv);
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}
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// The declaration order of these const fields is important; see the
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// constructor before changing.
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const MemRegion _whole_heap; // the region covered by the card table
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const size_t _guard_index; // index of very last element in the card
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// table; it is set to a guard value
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// (last_card) and should never be modified
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const size_t _last_valid_index; // index of the last valid element
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const size_t _page_size; // page size used when mapping _byte_map
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const size_t _byte_map_size; // in bytes
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jbyte* _byte_map; // the card marking array
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int _cur_covered_regions;
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// The covered regions should be in address order.
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MemRegion* _covered;
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// The committed regions correspond one-to-one to the covered regions.
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// They represent the card-table memory that has been committed to service
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// the corresponding covered region. It may be that committed region for
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// one covered region corresponds to a larger region because of page-size
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// roundings. Thus, a committed region for one covered region may
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// actually extend onto the card-table space for the next covered region.
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MemRegion* _committed;
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// The last card is a guard card, and we commit the page for it so
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// we can use the card for verification purposes. We make sure we never
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// uncommit the MemRegion for that page.
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MemRegion _guard_region;
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protected:
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// Initialization utilities; covered_words is the size of the covered region
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// in, um, words.
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inline size_t cards_required(size_t covered_words);
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inline size_t compute_byte_map_size();
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// Finds and return the index of the region, if any, to which the given
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// region would be contiguous. If none exists, assign a new region and
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// returns its index. Requires that no more than the maximum number of
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// covered regions defined in the constructor are ever in use.
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int find_covering_region_by_base(HeapWord* base);
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// Same as above, but finds the region containing the given address
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// instead of starting at a given base address.
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int find_covering_region_containing(HeapWord* addr);
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// Resize one of the regions covered by the remembered set.
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void resize_covered_region(MemRegion new_region);
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// Returns the leftmost end of a committed region corresponding to a
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// covered region before covered region "ind", or else "NULL" if "ind" is
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// the first covered region.
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HeapWord* largest_prev_committed_end(int ind) const;
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// Returns the part of the region mr that doesn't intersect with
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// any committed region other than self. Used to prevent uncommitting
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// regions that are also committed by other regions. Also protects
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// against uncommitting the guard region.
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MemRegion committed_unique_to_self(int self, MemRegion mr) const;
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// Mapping from address to card marking array entry
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jbyte* byte_for(const void* p) const {
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assert(_whole_heap.contains(p),
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"out of bounds access to card marking array");
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jbyte* result = &byte_map_base[uintptr_t(p) >> card_shift];
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assert(result >= _byte_map && result < _byte_map + _byte_map_size,
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"out of bounds accessor for card marking array");
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return result;
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}
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// The card table byte one after the card marking array
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// entry for argument address. Typically used for higher bounds
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// for loops iterating through the card table.
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jbyte* byte_after(const void* p) const {
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return byte_for(p) + 1;
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}
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// Iterate over the portion of the card-table which covers the given
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// region mr in the given space and apply cl to any dirty sub-regions
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// of mr. cl and dcto_cl must either be the same closure or cl must
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// wrap dcto_cl. Both are required - neither may be NULL. Also, dcto_cl
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// may be modified. Note that this function will operate in a parallel
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// mode if worker threads are available.
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void non_clean_card_iterate(Space* sp, MemRegion mr,
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DirtyCardToOopClosure* dcto_cl,
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MemRegionClosure* cl,
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bool clear);
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// Utility function used to implement the other versions below.
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void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl,
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bool clear);
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void par_non_clean_card_iterate_work(Space* sp, MemRegion mr,
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DirtyCardToOopClosure* dcto_cl,
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MemRegionClosure* cl,
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bool clear,
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int n_threads);
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// Dirty the bytes corresponding to "mr" (not all of which must be
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// covered.)
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void dirty_MemRegion(MemRegion mr);
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// Clear (to clean_card) the bytes entirely contained within "mr" (not
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// all of which must be covered.)
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void clear_MemRegion(MemRegion mr);
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// *** Support for parallel card scanning.
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enum SomeConstantsForParallelism {
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StridesPerThread = 2,
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CardsPerStrideChunk = 256
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};
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// This is an array, one element per covered region of the card table.
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// Each entry is itself an array, with one element per chunk in the
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// covered region. Each entry of these arrays is the lowest non-clean
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// card of the corresponding chunk containing part of an object from the
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// previous chunk, or else NULL.
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typedef jbyte* CardPtr;
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typedef CardPtr* CardArr;
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CardArr* _lowest_non_clean;
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size_t* _lowest_non_clean_chunk_size;
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uintptr_t* _lowest_non_clean_base_chunk_index;
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int* _last_LNC_resizing_collection;
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// Initializes "lowest_non_clean" to point to the array for the region
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// covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk
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// index of the corresponding to the first element of that array.
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// Ensures that these arrays are of sufficient size, allocating if necessary.
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// May be called by several threads concurrently.
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void get_LNC_array_for_space(Space* sp,
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jbyte**& lowest_non_clean,
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uintptr_t& lowest_non_clean_base_chunk_index,
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size_t& lowest_non_clean_chunk_size);
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// Returns the number of chunks necessary to cover "mr".
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size_t chunks_to_cover(MemRegion mr) {
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return (size_t)(addr_to_chunk_index(mr.last()) -
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addr_to_chunk_index(mr.start()) + 1);
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}
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// Returns the index of the chunk in a stride which
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// covers the given address.
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uintptr_t addr_to_chunk_index(const void* addr) {
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uintptr_t card = (uintptr_t) byte_for(addr);
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return card / CardsPerStrideChunk;
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}
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// Apply cl, which must either itself apply dcto_cl or be dcto_cl,
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// to the cards in the stride (of n_strides) within the given space.
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void process_stride(Space* sp,
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MemRegion used,
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jint stride, int n_strides,
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DirtyCardToOopClosure* dcto_cl,
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MemRegionClosure* cl,
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bool clear,
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jbyte** lowest_non_clean,
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uintptr_t lowest_non_clean_base_chunk_index,
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size_t lowest_non_clean_chunk_size);
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// Makes sure that chunk boundaries are handled appropriately, by
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// adjusting the min_done of dcto_cl, and by using a special card-table
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// value to indicate how min_done should be set.
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void process_chunk_boundaries(Space* sp,
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DirtyCardToOopClosure* dcto_cl,
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MemRegion chunk_mr,
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MemRegion used,
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jbyte** lowest_non_clean,
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uintptr_t lowest_non_clean_base_chunk_index,
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size_t lowest_non_clean_chunk_size);
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public:
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// Constants
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enum SomePublicConstants {
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card_shift = 9,
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card_size = 1 << card_shift,
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card_size_in_words = card_size / sizeof(HeapWord)
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};
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static int clean_card_val() { return clean_card; }
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static int clean_card_mask_val() { return clean_card_mask; }
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static int dirty_card_val() { return dirty_card; }
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static int claimed_card_val() { return claimed_card; }
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static int precleaned_card_val() { return precleaned_card; }
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static int deferred_card_val() { return deferred_card; }
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// For RTTI simulation.
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bool is_a(BarrierSet::Name bsn) {
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return bsn == BarrierSet::CardTableModRef || ModRefBarrierSet::is_a(bsn);
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}
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CardTableModRefBS(MemRegion whole_heap, int max_covered_regions);
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// *** Barrier set functions.
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bool has_write_ref_pre_barrier() { return false; }
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inline bool write_ref_needs_barrier(void* field, oop new_val) {
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// Note that this assumes the perm gen is the highest generation
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// in the address space
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return new_val != NULL && !new_val->is_perm();
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}
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// Record a reference update. Note that these versions are precise!
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// The scanning code has to handle the fact that the write barrier may be
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// either precise or imprecise. We make non-virtual inline variants of
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// these functions here for performance.
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protected:
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void write_ref_field_work(oop obj, size_t offset, oop newVal);
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virtual void write_ref_field_work(void* field, oop newVal);
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public:
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bool has_write_ref_array_opt() { return true; }
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bool has_write_region_opt() { return true; }
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inline void inline_write_region(MemRegion mr) {
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dirty_MemRegion(mr);
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}
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protected:
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void write_region_work(MemRegion mr) {
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inline_write_region(mr);
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}
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public:
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inline void inline_write_ref_array(MemRegion mr) {
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dirty_MemRegion(mr);
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}
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protected:
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void write_ref_array_work(MemRegion mr) {
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inline_write_ref_array(mr);
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}
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public:
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bool is_aligned(HeapWord* addr) {
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return is_card_aligned(addr);
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}
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// *** Card-table-barrier-specific things.
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template <class T> inline void inline_write_ref_field_pre(T* field, oop newVal) {}
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template <class T> inline void inline_write_ref_field(T* field, oop newVal) {
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jbyte* byte = byte_for((void*)field);
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*byte = dirty_card;
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}
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// These are used by G1, when it uses the card table as a temporary data
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// structure for card claiming.
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bool is_card_dirty(size_t card_index) {
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return _byte_map[card_index] == dirty_card_val();
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}
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void mark_card_dirty(size_t card_index) {
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_byte_map[card_index] = dirty_card_val();
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}
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bool is_card_claimed(size_t card_index) {
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jbyte val = _byte_map[card_index];
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return (val & (clean_card_mask_val() | claimed_card_val())) == claimed_card_val();
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}
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void set_card_claimed(size_t card_index) {
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jbyte val = _byte_map[card_index];
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if (val == clean_card_val()) {
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val = (jbyte)claimed_card_val();
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} else {
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val |= (jbyte)claimed_card_val();
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}
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_byte_map[card_index] = val;
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}
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bool claim_card(size_t card_index);
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bool is_card_clean(size_t card_index) {
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return _byte_map[card_index] == clean_card_val();
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}
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bool is_card_deferred(size_t card_index) {
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jbyte val = _byte_map[card_index];
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return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val();
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}
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bool mark_card_deferred(size_t card_index);
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// Card marking array base (adjusted for heap low boundary)
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// This would be the 0th element of _byte_map, if the heap started at 0x0.
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// But since the heap starts at some higher address, this points to somewhere
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// before the beginning of the actual _byte_map.
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jbyte* byte_map_base;
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// Return true if "p" is at the start of a card.
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bool is_card_aligned(HeapWord* p) {
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jbyte* pcard = byte_for(p);
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return (addr_for(pcard) == p);
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}
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// The kinds of precision a CardTableModRefBS may offer.
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enum PrecisionStyle {
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Precise,
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ObjHeadPreciseArray
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};
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// Tells what style of precision this card table offers.
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PrecisionStyle precision() {
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return ObjHeadPreciseArray; // Only one supported for now.
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}
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// ModRefBS functions.
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virtual void invalidate(MemRegion mr, bool whole_heap = false);
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void clear(MemRegion mr);
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void dirty(MemRegion mr);
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void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
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bool clear = false,
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bool before_save_marks = false);
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// *** Card-table-RemSet-specific things.
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// Invoke "cl.do_MemRegion" on a set of MemRegions that collectively
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// includes all the modified cards (expressing each card as a
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// MemRegion). Thus, several modified cards may be lumped into one
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// region. The regions are non-overlapping, and are visited in
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// *decreasing* address order. (This order aids with imprecise card
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// marking, where a dirty card may cause scanning, and summarization
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// marking, of objects that extend onto subsequent cards.)
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// If "clear" is true, the card is (conceptually) marked unmodified before
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// applying the closure.
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void mod_card_iterate(MemRegionClosure* cl, bool clear = false) {
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non_clean_card_iterate_work(_whole_heap, cl, clear);
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}
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// Like the "mod_cards_iterate" above, except only invokes the closure
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// for cards within the MemRegion "mr" (which is required to be
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// card-aligned and sized.)
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void mod_card_iterate(MemRegion mr, MemRegionClosure* cl,
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bool clear = false) {
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non_clean_card_iterate_work(mr, cl, clear);
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}
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static uintx ct_max_alignment_constraint();
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// Apply closure "cl" to the dirty cards containing some part of
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// MemRegion "mr".
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void dirty_card_iterate(MemRegion mr, MemRegionClosure* cl);
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// Return the MemRegion corresponding to the first maximal run
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// of dirty cards lying completely within MemRegion mr.
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// If reset is "true", then sets those card table entries to the given
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// value.
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MemRegion dirty_card_range_after_reset(MemRegion mr, bool reset,
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int reset_val);
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// Set all the dirty cards in the given region to precleaned state.
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void preclean_dirty_cards(MemRegion mr);
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// Provide read-only access to the card table array.
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const jbyte* byte_for_const(const void* p) const {
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return byte_for(p);
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}
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const jbyte* byte_after_const(const void* p) const {
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return byte_after(p);
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}
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// Mapping from card marking array entry to address of first word
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HeapWord* addr_for(const jbyte* p) const {
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assert(p >= _byte_map && p < _byte_map + _byte_map_size,
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"out of bounds access to card marking array");
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size_t delta = pointer_delta(p, byte_map_base, sizeof(jbyte));
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HeapWord* result = (HeapWord*) (delta << card_shift);
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assert(_whole_heap.contains(result),
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"out of bounds accessor from card marking array");
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return result;
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}
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// Mapping from address to card marking array index.
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size_t index_for(void* p) {
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assert(_whole_heap.contains(p),
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"out of bounds access to card marking array");
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return byte_for(p) - _byte_map;
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}
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const jbyte* byte_for_index(const size_t card_index) const {
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return _byte_map + card_index;
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}
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void verify();
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void verify_guard();
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void verify_clean_region(MemRegion mr) PRODUCT_RETURN;
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void verify_dirty_region(MemRegion mr) PRODUCT_RETURN;
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static size_t par_chunk_heapword_alignment() {
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return CardsPerStrideChunk * card_size_in_words;
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|
}
|
|
|
|
};
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|
|
|
class CardTableRS;
|
|
|
|
// A specialization for the CardTableRS gen rem set.
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|
class CardTableModRefBSForCTRS: public CardTableModRefBS {
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|
CardTableRS* _rs;
|
|
protected:
|
|
bool card_will_be_scanned(jbyte cv);
|
|
bool card_may_have_been_dirty(jbyte cv);
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|
public:
|
|
CardTableModRefBSForCTRS(MemRegion whole_heap,
|
|
int max_covered_regions) :
|
|
CardTableModRefBS(whole_heap, max_covered_regions) {}
|
|
|
|
void set_CTRS(CardTableRS* rs) { _rs = rs; }
|
|
};
|