# HG changeset patch # User brutisso # Date 1409129468 -7200 # Node ID 3e4ef23b8ee3a5c0c5008e2fadbdef4b89664112 # Parent 93f6b40c038b2e57f1aa09569a1bad676e16a8c2 8055816: Remove dead code in g1BlockOffsetTable Reviewed-by: tschatzl, mgerdin diff -r 93f6b40c038b -r 3e4ef23b8ee3 hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp --- a/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp Tue Aug 26 09:36:53 2014 +0200 +++ b/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp Wed Aug 27 10:51:08 2014 +0200 @@ -32,13 +32,6 @@ -void G1BlockOffsetSharedArrayMappingChangedListener::on_commit(uint start_idx, size_t num_regions) { - // Nothing to do. The BOT is hard-wired to be part of the HeapRegion, and we cannot - // retrieve it here since this would cause firing of several asserts. The code - // executed after commit of a region already needs to do some re-initialization of - // the HeapRegion, so we combine that. -} - ////////////////////////////////////////////////////////////////////// // G1BlockOffsetSharedArray ////////////////////////////////////////////////////////////////////// @@ -72,26 +65,16 @@ return (delta & right_n_bits(LogN_words)) == (size_t)NoBits; } -void G1BlockOffsetSharedArray::set_offset_array(HeapWord* left, HeapWord* right, u_char offset) { - set_offset_array(index_for(left), index_for(right -1), offset); -} - ////////////////////////////////////////////////////////////////////// // G1BlockOffsetArray ////////////////////////////////////////////////////////////////////// G1BlockOffsetArray::G1BlockOffsetArray(G1BlockOffsetSharedArray* array, - MemRegion mr, bool init_to_zero) : + MemRegion mr) : G1BlockOffsetTable(mr.start(), mr.end()), _unallocated_block(_bottom), - _array(array), _gsp(NULL), - _init_to_zero(init_to_zero) { + _array(array), _gsp(NULL) { assert(_bottom <= _end, "arguments out of order"); - if (!_init_to_zero) { - // initialize cards to point back to mr.start() - set_remainder_to_point_to_start(mr.start() + N_words, mr.end()); - _array->set_offset_array(0, 0); // set first card to 0 - } } void G1BlockOffsetArray::set_space(G1OffsetTableContigSpace* sp) { @@ -181,93 +164,6 @@ DEBUG_ONLY(check_all_cards(start_card, end_card);) } -// The block [blk_start, blk_end) has been allocated; -// adjust the block offset table to represent this information; -// right-open interval: [blk_start, blk_end) -void -G1BlockOffsetArray::alloc_block(HeapWord* blk_start, HeapWord* blk_end) { - mark_block(blk_start, blk_end); - allocated(blk_start, blk_end); -} - -// Adjust BOT to show that a previously whole block has been split -// into two. -void G1BlockOffsetArray::split_block(HeapWord* blk, size_t blk_size, - size_t left_blk_size) { - // Verify that the BOT shows [blk, blk + blk_size) to be one block. - verify_single_block(blk, blk_size); - // Update the BOT to indicate that [blk + left_blk_size, blk + blk_size) - // is one single block. - mark_block(blk + left_blk_size, blk + blk_size); -} - - -// Action_mark - update the BOT for the block [blk_start, blk_end). -// Current typical use is for splitting a block. -// Action_single - update the BOT for an allocation. -// Action_verify - BOT verification. -void G1BlockOffsetArray::do_block_internal(HeapWord* blk_start, - HeapWord* blk_end, - Action action) { - assert(Universe::heap()->is_in_reserved(blk_start), - "reference must be into the heap"); - assert(Universe::heap()->is_in_reserved(blk_end-1), - "limit must be within the heap"); - // This is optimized to make the test fast, assuming we only rarely - // cross boundaries. - uintptr_t end_ui = (uintptr_t)(blk_end - 1); - uintptr_t start_ui = (uintptr_t)blk_start; - // Calculate the last card boundary preceding end of blk - intptr_t boundary_before_end = (intptr_t)end_ui; - clear_bits(boundary_before_end, right_n_bits(LogN)); - if (start_ui <= (uintptr_t)boundary_before_end) { - // blk starts at or crosses a boundary - // Calculate index of card on which blk begins - size_t start_index = _array->index_for(blk_start); - // Index of card on which blk ends - size_t end_index = _array->index_for(blk_end - 1); - // Start address of card on which blk begins - HeapWord* boundary = _array->address_for_index(start_index); - assert(boundary <= blk_start, "blk should start at or after boundary"); - if (blk_start != boundary) { - // blk starts strictly after boundary - // adjust card boundary and start_index forward to next card - boundary += N_words; - start_index++; - } - assert(start_index <= end_index, "monotonicity of index_for()"); - assert(boundary <= (HeapWord*)boundary_before_end, "tautology"); - switch (action) { - case Action_mark: { - if (init_to_zero()) { - _array->set_offset_array(start_index, boundary, blk_start); - break; - } // Else fall through to the next case - } - case Action_single: { - _array->set_offset_array(start_index, boundary, blk_start); - // We have finished marking the "offset card". We need to now - // mark the subsequent cards that this blk spans. - if (start_index < end_index) { - HeapWord* rem_st = _array->address_for_index(start_index) + N_words; - HeapWord* rem_end = _array->address_for_index(end_index) + N_words; - set_remainder_to_point_to_start(rem_st, rem_end); - } - break; - } - case Action_check: { - _array->check_offset_array(start_index, boundary, blk_start); - // We have finished checking the "offset card". We need to now - // check the subsequent cards that this blk spans. - check_all_cards(start_index + 1, end_index); - break; - } - default: - ShouldNotReachHere(); - } - } -} - // The card-interval [start_card, end_card] is a closed interval; this // is an expensive check -- use with care and only under protection of // suitable flag. @@ -306,25 +202,6 @@ } } -// The range [blk_start, blk_end) represents a single contiguous block -// of storage; modify the block offset table to represent this -// information; Right-open interval: [blk_start, blk_end) -// NOTE: this method does _not_ adjust _unallocated_block. -void -G1BlockOffsetArray::single_block(HeapWord* blk_start, HeapWord* blk_end) { - do_block_internal(blk_start, blk_end, Action_single); -} - -// Mark the BOT such that if [blk_start, blk_end) straddles a card -// boundary, the card following the first such boundary is marked -// with the appropriate offset. -// NOTE: this method does _not_ adjust _unallocated_block or -// any cards subsequent to the first one. -void -G1BlockOffsetArray::mark_block(HeapWord* blk_start, HeapWord* blk_end) { - do_block_internal(blk_start, blk_end, Action_mark); -} - HeapWord* G1BlockOffsetArray::block_start_unsafe(const void* addr) { assert(_bottom <= addr && addr < _end, "addr must be covered by this Array"); @@ -397,57 +274,13 @@ return forward_to_block_containing_addr_const(q, n, addr); } -HeapWord* G1BlockOffsetArray::block_start_careful(const void* addr) const { - assert(_array->offset_array(0) == 0, "objects can't cross covered areas"); - - assert(_bottom <= addr && addr < _end, - "addr must be covered by this Array"); - // Must read this exactly once because it can be modified by parallel - // allocation. - HeapWord* ub = _unallocated_block; - if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) { - assert(ub < _end, "tautology (see above)"); - return ub; - } - - // Otherwise, find the block start using the table, but taking - // care (cf block_start_unsafe() above) not to parse any objects/blocks - // on the cards themselves. - size_t index = _array->index_for(addr); - assert(_array->address_for_index(index) == addr, - "arg should be start of card"); - - HeapWord* q = (HeapWord*)addr; - uint offset; - do { - offset = _array->offset_array(index--); - q -= offset; - } while (offset == N_words); - assert(q <= addr, "block start should be to left of arg"); - return q; -} - // Note that the committed size of the covered space may have changed, // so the table size might also wish to change. void G1BlockOffsetArray::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 } -void G1BlockOffsetArray::set_region(MemRegion mr) { - _bottom = mr.start(); - _end = mr.end(); -} - // // threshold_ // | _index_ @@ -606,7 +439,7 @@ G1BlockOffsetArrayContigSpace:: G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, MemRegion mr) : - G1BlockOffsetArray(array, mr, true) + G1BlockOffsetArray(array, mr) { _next_offset_threshold = NULL; _next_offset_index = 0; @@ -641,15 +474,6 @@ return _next_offset_threshold; } -void G1BlockOffsetArrayContigSpace::zero_bottom_entry() { - assert(!Universe::heap()->is_in_reserved(_array->_offset_array), - "just checking"); - size_t bottom_index = _array->index_for(_bottom); - assert(_array->address_for_index(bottom_index) == _bottom, - "Precondition of call"); - _array->set_offset_array(bottom_index, 0); -} - void G1BlockOffsetArrayContigSpace::set_for_starts_humongous(HeapWord* new_top) { assert(new_top <= _end, "_end should have already been updated"); diff -r 93f6b40c038b -r 3e4ef23b8ee3 hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp --- a/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp Tue Aug 26 09:36:53 2014 +0200 +++ b/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp Wed Aug 27 10:51:08 2014 +0200 @@ -109,7 +109,12 @@ class G1BlockOffsetSharedArrayMappingChangedListener : public G1MappingChangedListener { public: - virtual void on_commit(uint start_idx, size_t num_regions); + virtual void on_commit(uint start_idx, size_t num_regions) { + // Nothing to do. The BOT is hard-wired to be part of the HeapRegion, and we cannot + // retrieve it here since this would cause firing of several asserts. The code + // executed after commit of a region already needs to do some re-initialization of + // the HeapRegion, so we combine that. + } }; // This implementation of "G1BlockOffsetTable" divides the covered region @@ -153,8 +158,6 @@ // For performance these have to devolve to array accesses in product builds. inline u_char offset_array(size_t index) const; - void set_offset_array(HeapWord* left, HeapWord* right, u_char offset); - void set_offset_array_raw(size_t index, u_char offset) { _offset_array[index] = offset; } @@ -165,8 +168,6 @@ inline void set_offset_array(size_t left, size_t right, u_char offset); - inline void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const; - bool is_card_boundary(HeapWord* p) const; public: @@ -193,8 +194,6 @@ // G1BlockOffsetTable(s) to initialize cards. G1BlockOffsetSharedArray(MemRegion heap, G1RegionToSpaceMapper* storage); - void set_bottom(HeapWord* new_bottom); - // 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; @@ -220,14 +219,6 @@ LogN = G1BlockOffsetSharedArray::LogN }; - // The following enums are used by do_block_helper - 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()). - }; - // This is the array, which can be shared by several BlockOffsetArray's // servicing different G1BlockOffsetSharedArray* _array; @@ -235,10 +226,6 @@ // The space that owns this subregion. G1OffsetTableContigSpace* _gsp; - // 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; - // The portion [_unallocated_block, _sp.end()) of the space that // is a single block known not to contain any objects. // NOTE: See BlockOffsetArrayUseUnallocatedBlock flag. @@ -253,9 +240,6 @@ // 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); - protected: G1OffsetTableContigSpace* gsp() const { return _gsp; } @@ -303,11 +287,9 @@ public: // The space may not have it's 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. - G1BlockOffsetArray(G1BlockOffsetSharedArray* array, MemRegion mr, - bool init_to_zero); + // region is passed as a parameter. The elements of the array are + // initialized to zero. + G1BlockOffsetArray(G1BlockOffsetSharedArray* array, MemRegion mr); // 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 @@ -315,114 +297,19 @@ // This would be legal C++, but MS VC++ doesn't allow it. void set_space(G1OffsetTableContigSpace* sp); - // Resets the covered region to the given "mr". - void set_region(MemRegion mr); - // Resets the covered region to one with the same _bottom as before but // the "new_word_size". void resize(size_t new_word_size); - // These must be guaranteed to work properly (i.e., do nothing) - // when "blk_start" ("blk" for second version) is "NULL". - virtual void alloc_block(HeapWord* blk_start, HeapWord* blk_end); - virtual void alloc_block(HeapWord* blk, size_t size) { - alloc_block(blk, blk + size); - } - - // The following methods are useful and optimized for a - // general, 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 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); - } - - // 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. - inline 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); - } - } - - inline void allocated(HeapWord* blk, size_t size) { - allocated(blk, blk + size); - } - - inline void freed(HeapWord* blk_start, HeapWord* blk_end); - - inline void freed(HeapWord* blk, size_t size); - virtual HeapWord* block_start_unsafe(const void* addr); virtual HeapWord* block_start_unsafe_const(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; - - // 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; } - - // 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. - inline void verify_single_block(HeapWord* blk_start, HeapWord* blk_end) { - if (VerifyBlockOffsetArray) { - do_block_internal(blk_start, blk_end, Action_check); - } - } - - inline void verify_single_block(HeapWord* blk, size_t size) { - verify_single_block(blk, blk + size); - } - // Used by region verification. Checks that the contents of the // BOT reflect that there's a single object that spans the address // range [obj_start, obj_start + word_size); returns true if this is // the case, returns false if it's not. bool verify_for_object(HeapWord* obj_start, size_t word_size) const; - // Verify that the given block is before _unallocated_block - inline void verify_not_unallocated(HeapWord* blk_start, - HeapWord* blk_end) const { - if (BlockOffsetArrayUseUnallocatedBlock) { - assert(blk_start < blk_end, "Block inconsistency?"); - assert(blk_end <= _unallocated_block, "_unallocated_block problem"); - } - } - - inline void verify_not_unallocated(HeapWord* blk, size_t size) const { - verify_not_unallocated(blk, blk + size); - } - void check_all_cards(size_t left_card, size_t right_card) const; virtual void print_on(outputStream* out) PRODUCT_RETURN; @@ -445,14 +332,12 @@ blk_start, blk_end); } - // Variant of zero_bottom_entry that does not check for availability of the + // 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(); - // Zero out the entry for _bottom (offset will be zero). - void zero_bottom_entry(); public: G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, MemRegion mr); diff -r 93f6b40c038b -r 3e4ef23b8ee3 hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp --- a/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp Tue Aug 26 09:36:53 2014 +0200 +++ b/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp Wed Aug 27 10:51:08 2014 +0200 @@ -91,13 +91,6 @@ } } -void G1BlockOffsetSharedArray::check_offset_array(size_t index, HeapWord* high, HeapWord* low) const { - check_index(index, "index out of range"); - assert(high >= low, "addresses out of order"); - check_offset(pointer_delta(high, low), "offset too large"); - assert(_offset_array[index] == pointer_delta(high, low), "Wrong offset"); -} - // Variant of index_for that does not check the index for validity. inline size_t G1BlockOffsetSharedArray::index_for_raw(const void* p) const { return pointer_delta((char*)p, _reserved.start(), sizeof(char)) >> LogN; @@ -193,28 +186,4 @@ return q; } -////////////////////////////////////////////////////////////////////////// -// BlockOffsetArrayNonContigSpace inlines -////////////////////////////////////////////////////////////////////////// -inline void G1BlockOffsetArray::freed(HeapWord* blk_start, HeapWord* blk_end) { - // Verify that the BOT shows [blk_start, blk_end) to be one block. - verify_single_block(blk_start, blk_end); - // adjust _unallocated_block upward or downward - // as appropriate - if (BlockOffsetArrayUseUnallocatedBlock) { - assert(_unallocated_block <= _end, - "Inconsistent value for _unallocated_block"); - if (blk_end >= _unallocated_block && blk_start <= _unallocated_block) { - // CMS-specific note: a block abutting _unallocated_block to - // its left is being freed, a new block is being added or - // we are resetting following a compaction - _unallocated_block = blk_start; - } - } -} - -inline void G1BlockOffsetArray::freed(HeapWord* blk, size_t size) { - freed(blk, blk + size); -} - #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_INLINE_HPP diff -r 93f6b40c038b -r 3e4ef23b8ee3 hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp --- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp Tue Aug 26 09:36:53 2014 +0200 +++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp Wed Aug 27 10:51:08 2014 +0200 @@ -322,29 +322,6 @@ return false; } -HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) { - HeapWord* low = addr; - HeapWord* high = end(); - while (low < high) { - size_t diff = pointer_delta(high, low); - // Must add one below to bias toward the high amount. Otherwise, if - // "high" were at the desired value, and "low" were one less, we - // would not converge on "high". This is not symmetric, because - // we set "high" to a block start, which might be the right one, - // which we don't do for "low". - HeapWord* middle = low + (diff+1)/2; - if (middle == high) return high; - HeapWord* mid_bs = block_start_careful(middle); - if (mid_bs < addr) { - low = middle; - } else { - high = mid_bs; - } - } - assert(low == high && low >= addr, "Didn't work."); - return low; -} - HeapRegion::HeapRegion(uint hrm_index, G1BlockOffsetSharedArray* sharedOffsetArray, MemRegion mr) : diff -r 93f6b40c038b -r 3e4ef23b8ee3 hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp --- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp Tue Aug 26 09:36:53 2014 +0200 +++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp Wed Aug 27 10:51:08 2014 +0200 @@ -206,10 +206,6 @@ _offsets.reset_bot(); } - void update_bot_for_object(HeapWord* start, size_t word_size) { - _offsets.alloc_block(start, word_size); - } - void print_bot_on(outputStream* out) { _offsets.print_on(out); } @@ -737,18 +733,6 @@ bool filter_young, jbyte* card_ptr); - // A version of block start that is guaranteed to find *some* block - // boundary at or before "p", but does not object iteration, and may - // therefore be used safely when the heap is unparseable. - HeapWord* block_start_careful(const void* p) const { - return _offsets.block_start_careful(p); - } - - // Requires that "addr" is within the region. Returns the start of the - // first ("careful") block that starts at or after "addr", or else the - // "end" of the region if there is no such block. - HeapWord* next_block_start_careful(HeapWord* addr); - size_t recorded_rs_length() const { return _recorded_rs_length; } double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; } size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }