Mercurial > hg > graal-compiler
view src/share/vm/memory/blockOffsetTable.hpp @ 599:0ad1cb407fa1
6805427: adlc compiler may generate incorrect machnode emission code
Reviewed-by: kvn, twisti
author | never |
---|---|
date | Wed, 25 Feb 2009 10:53:14 -0800 |
parents | eb28cf662f56 |
children | c3a720eefe82 |
line wrap: on
line source
/* * Copyright 2000-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ // The CollectedHeap type requires subtypes to implement a method // "block_start". For some subtypes, notably generational // systems using card-table-based write barriers, the efficiency of this // operation may be important. Implementations of the "BlockOffsetArray" // class may be useful in providing such efficient implementations. // // BlockOffsetTable (abstract) // - BlockOffsetArray (abstract) // - BlockOffsetArrayNonContigSpace // - BlockOffsetArrayContigSpace // class ContiguousSpace; class SerializeOopClosure; ////////////////////////////////////////////////////////////////////////// // The BlockOffsetTable "interface" ////////////////////////////////////////////////////////////////////////// class BlockOffsetTable VALUE_OBJ_CLASS_SPEC { friend class VMStructs; protected: // These members describe the region covered by the table. // The space this table is covering. HeapWord* _bottom; // == reserved.start HeapWord* _end; // End of currently allocated region. public: // Initialize the table to cover the given space. // The contents of the initial table are undefined. BlockOffsetTable(HeapWord* bottom, HeapWord* end): _bottom(bottom), _end(end) { assert(_bottom <= _end, "arguments out of order"); } // Note that the committed size of the covered space may have changed, // so the table size might also wish to change. virtual void resize(size_t new_word_size) = 0; virtual void set_bottom(HeapWord* new_bottom) { assert(new_bottom <= _end, "new_bottom > _end"); _bottom = new_bottom; resize(pointer_delta(_end, _bottom)); } // Requires "addr" to be contained by a block, and returns the address of // the start of that block. virtual HeapWord* block_start_unsafe(const void* addr) const = 0; // Returns the address of the start of the block containing "addr", or // else "null" if it is covered by no block. HeapWord* block_start(const void* addr) const; }; ////////////////////////////////////////////////////////////////////////// // One implementation of "BlockOffsetTable," the BlockOffsetArray, // 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 BlockOffsetArray is owned by a Space. However, the actual array // may be shared by several BlockOffsetArrays; this is useful // when a single resizable area (such as a generation) is divided up into // several spaces in which contiguous allocation takes place. (Consider, // for example, the garbage-first generation.) // Here is the shared array type. ////////////////////////////////////////////////////////////////////////// // BlockOffsetSharedArray ////////////////////////////////////////////////////////////////////////// class BlockOffsetSharedArray: public CHeapObj { friend class BlockOffsetArray; friend class BlockOffsetArrayNonContigSpace; friend class BlockOffsetArrayContigSpace; friend class VMStructs; private: enum SomePrivateConstants { LogN = 9, LogN_words = LogN - LogHeapWordSize, N_bytes = 1 << LogN, N_words = 1 << LogN_words }; // The reserved region covered by the shared array. MemRegion _reserved; // End of the current committed region. HeapWord* _end; // Array for keeping offsets for retrieving object start fast given an // address. VirtualSpace _vs; u_char* _offset_array; // byte array keeping backwards offsets protected: // Bounds checking accessors: // For performance these have to devolve to array accesses in product builds. u_char offset_array(size_t index) const { assert(index < _vs.committed_size(), "index out of range"); return _offset_array[index]; } void set_offset_array(size_t index, u_char offset) { assert(index < _vs.committed_size(), "index out of range"); _offset_array[index] = offset; } void set_offset_array(size_t index, HeapWord* high, HeapWord* low) { assert(index < _vs.committed_size(), "index out of range"); assert(high >= low, "addresses out of order"); assert(pointer_delta(high, low) <= N_words, "offset too large"); _offset_array[index] = (u_char)pointer_delta(high, low); } void set_offset_array(HeapWord* left, HeapWord* right, u_char offset) { assert(index_for(right - 1) < _vs.committed_size(), "right address out of range"); assert(left < right, "Heap addresses out of order"); size_t num_cards = pointer_delta(right, left) >> LogN_words; memset(&_offset_array[index_for(left)], offset, num_cards); } void set_offset_array(size_t left, size_t right, u_char offset) { assert(right < _vs.committed_size(), "right address out of range"); assert(left <= right, "indexes out of order"); size_t num_cards = right - left + 1; memset(&_offset_array[left], offset, num_cards); } void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const { assert(index < _vs.committed_size(), "index out of range"); assert(high >= low, "addresses out of order"); assert(pointer_delta(high, low) <= N_words, "offset too large"); assert(_offset_array[index] == pointer_delta(high, low), "Wrong offset"); } bool is_card_boundary(HeapWord* p) const; // Return the number of slots needed for an offset array // that covers mem_region_words words. // We always add an extra slot because if an object // ends on a card boundary we put a 0 in the next // offset array slot, so we want that slot always // to be reserved. size_t compute_size(size_t mem_region_words) { size_t number_of_slots = (mem_region_words / N_words) + 1; return ReservedSpace::allocation_align_size_up(number_of_slots); } public: // Initialize the table to cover from "base" to (at least) // "base + init_word_size". In the future, the table may be expanded // (see "resize" below) up to the size of "_reserved" (which must be at // least "init_word_size".) The contents of the initial table are // undefined; it is the responsibility of the constituent // BlockOffsetTable(s) to initialize cards. BlockOffsetSharedArray(MemRegion reserved, size_t init_word_size); // Notes a change in the committed size of the region covered by the // table. The "new_word_size" may not be larger than the size of the // reserved region this table covers. void resize(size_t new_word_size); void set_bottom(HeapWord* new_bottom); // Updates all the BlockOffsetArray's sharing this shared array to // reflect the current "top"'s of their spaces. void update_offset_arrays(); // Not yet implemented! // Return the appropriate index into "_offset_array" for "p". size_t index_for(const void* p) const; // Return the address indicating the start of the region corresponding to // "index" in "_offset_array". HeapWord* address_for_index(size_t index) const; // Return the address "p" incremented by the size of // a region. This method does not align the address // returned to the start of a region. It is a simple // primitive. HeapWord* inc_by_region_size(HeapWord* p) const { return p + N_words; } // Shared space support void serialize(SerializeOopClosure* soc, HeapWord* start, HeapWord* end); }; ////////////////////////////////////////////////////////////////////////// // The BlockOffsetArray whose subtypes use the BlockOffsetSharedArray. ////////////////////////////////////////////////////////////////////////// class BlockOffsetArray: public BlockOffsetTable { friend class VMStructs; friend class G1BlockOffsetArray; // temp. until we restructure and cleanup protected: // The following enums are used by do_block_internal() below enum Action { Action_single, // BOT records a single block (see single_block()) Action_mark, // BOT marks the start of a block (see mark_block()) Action_check // Check that BOT records block correctly // (see verify_single_block()). }; enum SomePrivateConstants { N_words = BlockOffsetSharedArray::N_words, LogN = BlockOffsetSharedArray::LogN, // entries "e" of at least N_words mean "go back by Base^(e-N_words)." // All entries are less than "N_words + N_powers". LogBase = 4, Base = (1 << LogBase), N_powers = 14 }; static size_t power_to_cards_back(uint i) { return 1 << (LogBase * i); } static size_t power_to_words_back(uint i) { return power_to_cards_back(i) * N_words; } static size_t entry_to_cards_back(u_char entry) { assert(entry >= N_words, "Precondition"); return power_to_cards_back(entry - N_words); } static size_t entry_to_words_back(u_char entry) { assert(entry >= N_words, "Precondition"); return power_to_words_back(entry - N_words); } // The shared array, which is shared with other BlockOffsetArray's // corresponding to different spaces within a generation or span of // memory. BlockOffsetSharedArray* _array; // The space that owns this subregion. Space* _sp; // If true, array entries are initialized to 0; otherwise, they are // initialized to point backwards to the beginning of the covered region. bool _init_to_zero; // 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); // A helper function for BOT adjustment/verification work void do_block_internal(HeapWord* blk_start, HeapWord* blk_end, Action action); public: // The space may not have its bottom and top set yet, which is why the // region is passed as a parameter. If "init_to_zero" is true, the // elements of the array are initialized to zero. Otherwise, they are // initialized to point backwards to the beginning. BlockOffsetArray(BlockOffsetSharedArray* array, MemRegion mr, bool init_to_zero); // Note: this ought to be part of the constructor, but that would require // "this" to be passed as a parameter to a member constructor for // the containing concrete subtype of Space. // This would be legal C++, but MS VC++ doesn't allow it. void set_space(Space* sp) { _sp = sp; } // Resets the covered region to the given "mr". void set_region(MemRegion mr) { _bottom = mr.start(); _end = mr.end(); } // Note that the committed size of the covered space may have changed, // so the table size might also wish to change. virtual void resize(size_t new_word_size) { HeapWord* new_end = _bottom + new_word_size; if (_end < new_end && !init_to_zero()) { // verify that the old and new boundaries are also card boundaries assert(_array->is_card_boundary(_end), "_end not a card boundary"); assert(_array->is_card_boundary(new_end), "new _end would not be a card boundary"); // set all the newly added cards _array->set_offset_array(_end, new_end, N_words); } _end = new_end; // update _end } // Adjust the BOT to show that it has a single block in the // range [blk_start, blk_start + size). All necessary BOT // cards are adjusted, but _unallocated_block isn't. void single_block(HeapWord* blk_start, HeapWord* blk_end); void single_block(HeapWord* blk, size_t size) { single_block(blk, blk + size); } // When the alloc_block() call returns, the block offset table should // have enough information such that any subsequent block_start() call // with an argument equal to an address that is within the range // [blk_start, blk_end) would return the value blk_start, provided // there have been no calls in between that reset this information // (e.g. see BlockOffsetArrayNonContigSpace::single_block() call // for an appropriate range covering the said interval). // These methods expect to be called with [blk_start, blk_end) // representing a block of memory in the heap. virtual void alloc_block(HeapWord* blk_start, HeapWord* blk_end); void alloc_block(HeapWord* blk, size_t size) { alloc_block(blk, blk + size); } // If true, initialize array slots with no allocated blocks to zero. // Otherwise, make them point back to the front. bool init_to_zero() { return _init_to_zero; } // Debugging // Return the index of the last entry in the "active" region. virtual size_t last_active_index() const = 0; // Verify the block offset table void verify() const; void check_all_cards(size_t left_card, size_t right_card) const; }; //////////////////////////////////////////////////////////////////////////// // A subtype of BlockOffsetArray that takes advantage of the fact // that its underlying space is a NonContiguousSpace, so that some // specialized interfaces can be made available for spaces that // manipulate the table. //////////////////////////////////////////////////////////////////////////// class BlockOffsetArrayNonContigSpace: public BlockOffsetArray { friend class VMStructs; private: // The portion [_unallocated_block, _sp.end()) of the space that // is a single block known not to contain any objects. // NOTE: See BlockOffsetArrayUseUnallocatedBlock flag. HeapWord* _unallocated_block; public: BlockOffsetArrayNonContigSpace(BlockOffsetSharedArray* array, MemRegion mr): BlockOffsetArray(array, mr, false), _unallocated_block(_bottom) { } // accessor HeapWord* unallocated_block() const { assert(BlockOffsetArrayUseUnallocatedBlock, "_unallocated_block is not being maintained"); return _unallocated_block; } void set_unallocated_block(HeapWord* block) { assert(BlockOffsetArrayUseUnallocatedBlock, "_unallocated_block is not being maintained"); assert(block >= _bottom && block <= _end, "out of range"); _unallocated_block = block; } // These methods expect to be called with [blk_start, blk_end) // representing a block of memory in the heap. void alloc_block(HeapWord* blk_start, HeapWord* blk_end); void alloc_block(HeapWord* blk, size_t size) { alloc_block(blk, blk + size); } // The following methods are useful and optimized for a // non-contiguous space. // Given a block [blk_start, blk_start + full_blk_size), and // a left_blk_size < full_blk_size, adjust the BOT to show two // blocks [blk_start, blk_start + left_blk_size) and // [blk_start + left_blk_size, blk_start + full_blk_size). // It is assumed (and verified in the non-product VM) that the // BOT was correct for the original block. void split_block(HeapWord* blk_start, size_t full_blk_size, size_t left_blk_size); // Adjust BOT to show that it has a block in the range // [blk_start, blk_start + size). Only the first card // of BOT is touched. It is assumed (and verified in the // non-product VM) that the remaining cards of the block // are correct. void mark_block(HeapWord* blk_start, HeapWord* blk_end); void mark_block(HeapWord* blk, size_t size) { mark_block(blk, blk + size); } // Adjust _unallocated_block to indicate that a particular // block has been newly allocated or freed. It is assumed (and // verified in the non-product VM) that the BOT is correct for // the given block. void allocated(HeapWord* blk_start, HeapWord* blk_end) { // Verify that the BOT shows [blk, blk + blk_size) to be one block. verify_single_block(blk_start, blk_end); if (BlockOffsetArrayUseUnallocatedBlock) { _unallocated_block = MAX2(_unallocated_block, blk_end); } } void allocated(HeapWord* blk, size_t size) { allocated(blk, blk + size); } void freed(HeapWord* blk_start, HeapWord* blk_end); void freed(HeapWord* blk, size_t size) { freed(blk, blk + size); } HeapWord* block_start_unsafe(const void* addr) const; // Requires "addr" to be the start of a card and returns the // start of the block that contains the given address. HeapWord* block_start_careful(const void* addr) const; // Verification & debugging: ensure that the offset table reflects // the fact that the block [blk_start, blk_end) or [blk, blk + size) // is a single block of storage. NOTE: can't const this because of // call to non-const do_block_internal() below. void verify_single_block(HeapWord* blk_start, HeapWord* blk_end) PRODUCT_RETURN; void verify_single_block(HeapWord* blk, size_t size) PRODUCT_RETURN; // Verify that the given block is before _unallocated_block void verify_not_unallocated(HeapWord* blk_start, HeapWord* blk_end) const PRODUCT_RETURN; void verify_not_unallocated(HeapWord* blk, size_t size) const PRODUCT_RETURN; // Debugging support virtual size_t last_active_index() const; }; //////////////////////////////////////////////////////////////////////////// // A subtype of BlockOffsetArray that takes advantage of the fact // that its underlying space is a ContiguousSpace, so that its "active" // region can be more efficiently tracked (than for a non-contiguous space). //////////////////////////////////////////////////////////////////////////// class BlockOffsetArrayContigSpace: public BlockOffsetArray { 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 // Work function when allocation start crosses threshold. void alloc_block_work(HeapWord* blk_start, HeapWord* blk_end); public: BlockOffsetArrayContigSpace(BlockOffsetSharedArray* array, MemRegion mr): BlockOffsetArray(array, mr, true) { _next_offset_threshold = NULL; _next_offset_index = 0; } void set_contig_space(ContiguousSpace* sp) { set_space((Space*)sp); } // Initialize the threshold for an empty heap. HeapWord* initialize_threshold(); // Zero out the entry for _bottom (offset will be zero) void zero_bottom_entry(); // Return the next threshold, the point at which the table should be // updated. HeapWord* threshold() const { return _next_offset_threshold; } // In general, these methods expect to be called with // [blk_start, blk_end) representing a block of memory in the heap. // In this implementation, however, we are OK even if blk_start and/or // blk_end are NULL 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(blk_start, blk_end); } } void alloc_block(HeapWord* blk, size_t size) { alloc_block(blk, blk + size); } HeapWord* block_start_unsafe(const void* addr) const; void serialize(SerializeOopClosure* soc); // Debugging support virtual size_t last_active_index() const; };