| /* |
| * Copyright (c) 2001, 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 |
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| */ |
| |
| #ifndef SHARE_VM_GC_G1_G1BLOCKOFFSETTABLE_HPP |
| #define SHARE_VM_GC_G1_G1BLOCKOFFSETTABLE_HPP |
| |
| #include "gc/g1/g1RegionToSpaceMapper.hpp" |
| #include "gc/shared/blockOffsetTable.hpp" |
| #include "memory/memRegion.hpp" |
| #include "memory/virtualspace.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| |
| // Forward declarations |
| class G1BlockOffsetTable; |
| class G1ContiguousSpace; |
| |
| // This implementation of "G1BlockOffsetTable" divides the covered region |
| // into "N"-word subregions (where "N" = 2^"LogN". An array with an entry |
| // for each such subregion indicates how far back one must go to find the |
| // start of the chunk that includes the first word of the subregion. |
| // |
| // Each G1BlockOffsetTablePart is owned by a G1ContiguousSpace. |
| |
| class G1BlockOffsetTable: public CHeapObj<mtGC> { |
| friend class G1BlockOffsetTablePart; |
| friend class VMStructs; |
| |
| private: |
| // The reserved region covered by the table. |
| MemRegion _reserved; |
| |
| // Array for keeping offsets for retrieving object start fast given an |
| // address. |
| volatile u_char* _offset_array; // byte array keeping backwards offsets |
| |
| void check_offset(size_t offset, const char* msg) const { |
| assert(offset <= BOTConstants::N_words, |
| "%s - offset: " SIZE_FORMAT ", N_words: %u", |
| msg, offset, BOTConstants::N_words); |
| } |
| |
| // Bounds checking accessors: |
| // For performance these have to devolve to array accesses in product builds. |
| inline u_char offset_array(size_t index) const; |
| |
| inline void set_offset_array_raw(size_t index, u_char offset); |
| inline void set_offset_array(size_t index, u_char offset); |
| |
| inline void set_offset_array(size_t index, HeapWord* high, HeapWord* low); |
| |
| inline void set_offset_array(size_t left, size_t right, u_char offset); |
| |
| bool is_card_boundary(HeapWord* p) const; |
| |
| void check_index(size_t index, const char* msg) const NOT_DEBUG_RETURN; |
| |
| public: |
| |
| // Return the number of slots needed for an offset array |
| // that covers mem_region_words words. |
| static size_t compute_size(size_t mem_region_words) { |
| size_t number_of_slots = (mem_region_words / BOTConstants::N_words); |
| return ReservedSpace::allocation_align_size_up(number_of_slots); |
| } |
| |
| // Returns how many bytes of the heap a single byte of the BOT corresponds to. |
| static size_t heap_map_factor() { |
| return BOTConstants::N_bytes; |
| } |
| |
| // Initialize the Block Offset Table to cover the memory region passed |
| // in the heap parameter. |
| G1BlockOffsetTable(MemRegion heap, G1RegionToSpaceMapper* storage); |
| |
| // Return the appropriate index into "_offset_array" for "p". |
| inline size_t index_for(const void* p) const; |
| inline size_t index_for_raw(const void* p) const; |
| |
| // Return the address indicating the start of the region corresponding to |
| // "index" in "_offset_array". |
| inline HeapWord* address_for_index(size_t index) const; |
| // Variant of address_for_index that does not check the index for validity. |
| inline HeapWord* address_for_index_raw(size_t index) const { |
| return _reserved.start() + (index << BOTConstants::LogN_words); |
| } |
| }; |
| |
| class G1BlockOffsetTablePart { |
| friend class G1BlockOffsetTable; |
| friend class VMStructs; |
| private: |
| // allocation boundary at which offset array must be updated |
| HeapWord* _next_offset_threshold; |
| size_t _next_offset_index; // index corresponding to that boundary |
| |
| // Indicates if an object can span into this G1BlockOffsetTablePart. |
| debug_only(bool _object_can_span;) |
| |
| // This is the global BlockOffsetTable. |
| G1BlockOffsetTable* _bot; |
| |
| // The space that owns this subregion. |
| G1ContiguousSpace* _space; |
| |
| // Sets the entries |
| // corresponding to the cards starting at "start" and ending at "end" |
| // to point back to the card before "start": the interval [start, end) |
| // is right-open. |
| void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end); |
| // Same as above, except that the args here are a card _index_ interval |
| // that is closed: [start_index, end_index] |
| void set_remainder_to_point_to_start_incl(size_t start, size_t end); |
| |
| // Zero out the entry for _bottom (offset will be zero). Does not check for availability of the |
| // memory first. |
| void zero_bottom_entry_raw(); |
| // Variant of initialize_threshold that does not check for availability of the |
| // memory first. |
| HeapWord* initialize_threshold_raw(); |
| |
| inline size_t block_size(const HeapWord* p) const; |
| |
| // Returns the address of a block whose start is at most "addr". |
| // If "has_max_index" is true, "assumes "max_index" is the last valid one |
| // in the array. |
| inline HeapWord* block_at_or_preceding(const void* addr, |
| bool has_max_index, |
| size_t max_index) const; |
| |
| // "q" is a block boundary that is <= "addr"; "n" is the address of the |
| // next block (or the end of the space.) Return the address of the |
| // beginning of the block that contains "addr". Does so without side |
| // effects (see, e.g., spec of block_start.) |
| inline HeapWord* forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n, |
| const void* addr) const; |
| |
| // "q" is a block boundary that is <= "addr"; return the address of the |
| // beginning of the block that contains "addr". May have side effects |
| // on "this", by updating imprecise entries. |
| inline HeapWord* forward_to_block_containing_addr(HeapWord* q, |
| const void* addr); |
| |
| // "q" is a block boundary that is <= "addr"; "n" is the address of the |
| // next block (or the end of the space.) Return the address of the |
| // beginning of the block that contains "addr". May have side effects |
| // on "this", by updating imprecise entries. |
| HeapWord* forward_to_block_containing_addr_slow(HeapWord* q, |
| HeapWord* n, |
| const void* addr); |
| |
| // Requires that "*threshold_" be the first array entry boundary at or |
| // above "blk_start", and that "*index_" be the corresponding array |
| // index. If the block starts at or crosses "*threshold_", records |
| // "blk_start" as the appropriate block start for the array index |
| // starting at "*threshold_", and for any other indices crossed by the |
| // block. Updates "*threshold_" and "*index_" to correspond to the first |
| // index after the block end. |
| void alloc_block_work(HeapWord** threshold_, size_t* index_, |
| HeapWord* blk_start, HeapWord* blk_end); |
| |
| void check_all_cards(size_t left_card, size_t right_card) const; |
| |
| public: |
| // The elements of the array are initialized to zero. |
| G1BlockOffsetTablePart(G1BlockOffsetTable* array, G1ContiguousSpace* gsp); |
| |
| void verify() const; |
| |
| // Returns the address of the start of the block containing "addr", or |
| // else "null" if it is covered by no block. (May have side effects, |
| // namely updating of shared array entries that "point" too far |
| // backwards. This can occur, for example, when lab allocation is used |
| // in a space covered by the table.) |
| inline HeapWord* block_start(const void* addr); |
| // Same as above, but does not have any of the possible side effects |
| // discussed above. |
| inline HeapWord* block_start_const(const void* addr) const; |
| |
| // Initialize the threshold to reflect the first boundary after the |
| // bottom of the covered region. |
| HeapWord* initialize_threshold(); |
| |
| void reset_bot() { |
| zero_bottom_entry_raw(); |
| initialize_threshold_raw(); |
| } |
| |
| // Return the next threshold, the point at which the table should be |
| // updated. |
| HeapWord* threshold() const { return _next_offset_threshold; } |
| |
| // These must be guaranteed to work properly (i.e., do nothing) |
| // when "blk_start" ("blk" for second version) is "NULL". In this |
| // implementation, that's true because NULL is represented as 0, and thus |
| // never exceeds the "_next_offset_threshold". |
| void alloc_block(HeapWord* blk_start, HeapWord* blk_end) { |
| if (blk_end > _next_offset_threshold) { |
| alloc_block_work(&_next_offset_threshold, &_next_offset_index, blk_start, blk_end); |
| } |
| } |
| void alloc_block(HeapWord* blk, size_t size) { |
| alloc_block(blk, blk+size); |
| } |
| |
| void set_for_starts_humongous(HeapWord* obj_top, size_t fill_size); |
| void set_object_can_span(bool can_span) NOT_DEBUG_RETURN; |
| |
| void print_on(outputStream* out) PRODUCT_RETURN; |
| }; |
| |
| #endif // SHARE_VM_GC_G1_G1BLOCKOFFSETTABLE_HPP |