1 /* 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_INLINE_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_INLINE_HPP 27 28 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp" 29 #include "gc_implementation/g1/g1CollectedHeap.hpp" 30 #include "gc_implementation/g1/heapRegion.hpp" 31 #include "memory/space.hpp" 32 #include "runtime/atomic.inline.hpp" 33 34 // This version requires locking. 35 inline HeapWord* G1OffsetTableContigSpace::allocate_impl(size_t size, 36 HeapWord* const end_value) { 37 HeapWord* obj = top(); 38 if (pointer_delta(end_value, obj) >= size) { 39 HeapWord* new_top = obj + size; 40 set_top(new_top); 41 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 42 return obj; 43 } else { 44 return NULL; 45 } 46 } 47 48 // This version is lock-free. 49 inline HeapWord* G1OffsetTableContigSpace::par_allocate_impl(size_t size, 50 HeapWord* const end_value) { 51 do { 52 HeapWord* obj = top(); 53 if (pointer_delta(end_value, obj) >= size) { 54 HeapWord* new_top = obj + size; 55 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); 56 // result can be one of two: 57 // the old top value: the exchange succeeded 58 // otherwise: the new value of the top is returned. 59 if (result == obj) { 60 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 61 return obj; 62 } 63 } else { 64 return NULL; 65 } 66 } while (true); 67 } 68 69 inline HeapWord* G1OffsetTableContigSpace::allocate(size_t size) { 70 HeapWord* res = allocate_impl(size, end()); 71 if (res != NULL) { 72 _offsets.alloc_block(res, size); 73 } 74 return res; 75 } 76 77 // Because of the requirement of keeping "_offsets" up to date with the 78 // allocations, we sequentialize these with a lock. Therefore, best if 79 // this is used for larger LAB allocations only. 80 inline HeapWord* G1OffsetTableContigSpace::par_allocate(size_t size) { 81 MutexLocker x(&_par_alloc_lock); 82 return allocate(size); 83 } 84 85 inline HeapWord* G1OffsetTableContigSpace::block_start(const void* p) { 86 return _offsets.block_start(p); 87 } 88 89 inline HeapWord* 90 G1OffsetTableContigSpace::block_start_const(const void* p) const { 91 return _offsets.block_start_const(p); 92 } 93 94 inline bool 95 HeapRegion::block_is_obj(const HeapWord* p) const { 96 return p < top(); 97 } 98 99 inline size_t 100 HeapRegion::block_size(const HeapWord *addr) const { 101 const HeapWord* current_top = top(); 102 if (addr < current_top) { 103 return oop(addr)->size(); 104 } else { 105 assert(addr == current_top, "just checking"); 106 return pointer_delta(end(), addr); 107 } 108 } 109 110 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t word_size) { 111 assert(is_young(), "we can only skip BOT updates on young regions"); 112 return par_allocate_impl(word_size, end()); 113 } 114 115 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) { 116 assert(is_young(), "we can only skip BOT updates on young regions"); 117 return allocate_impl(word_size, end()); 118 } 119 120 inline void HeapRegion::note_start_of_marking() { 121 _next_marked_bytes = 0; 122 _next_top_at_mark_start = top(); 123 } 124 125 inline void HeapRegion::note_end_of_marking() { 126 _prev_top_at_mark_start = _next_top_at_mark_start; 127 _prev_marked_bytes = _next_marked_bytes; 128 _next_marked_bytes = 0; 129 130 assert(_prev_marked_bytes <= 131 (size_t) pointer_delta(prev_top_at_mark_start(), bottom()) * 132 HeapWordSize, "invariant"); 133 } 134 135 inline void HeapRegion::note_start_of_copying(bool during_initial_mark) { 136 if (is_survivor()) { 137 // This is how we always allocate survivors. 138 assert(_next_top_at_mark_start == bottom(), "invariant"); 139 } else { 140 if (during_initial_mark) { 141 // During initial-mark we'll explicitly mark any objects on old 142 // regions that are pointed to by roots. Given that explicit 143 // marks only make sense under NTAMS it'd be nice if we could 144 // check that condition if we wanted to. Given that we don't 145 // know where the top of this region will end up, we simply set 146 // NTAMS to the end of the region so all marks will be below 147 // NTAMS. We'll set it to the actual top when we retire this region. 148 _next_top_at_mark_start = end(); 149 } else { 150 // We could have re-used this old region as to-space over a 151 // couple of GCs since the start of the concurrent marking 152 // cycle. This means that [bottom,NTAMS) will contain objects 153 // copied up to and including initial-mark and [NTAMS, top) 154 // will contain objects copied during the concurrent marking cycle. 155 assert(top() >= _next_top_at_mark_start, "invariant"); 156 } 157 } 158 } 159 160 inline void HeapRegion::note_end_of_copying(bool during_initial_mark) { 161 if (is_survivor()) { 162 // This is how we always allocate survivors. 163 assert(_next_top_at_mark_start == bottom(), "invariant"); 164 } else { 165 if (during_initial_mark) { 166 // See the comment for note_start_of_copying() for the details 167 // on this. 168 assert(_next_top_at_mark_start == end(), "pre-condition"); 169 _next_top_at_mark_start = top(); 170 } else { 171 // See the comment for note_start_of_copying() for the details 172 // on this. 173 assert(top() >= _next_top_at_mark_start, "invariant"); 174 } 175 } 176 } 177 178 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_INLINE_HPP