1 /* 2 * Copyright (c) 2002, 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_PARALLELSCAVENGE_PSPROMOTIONLAB_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPROMOTIONLAB_HPP 27 28 #include "gc_implementation/parallelScavenge/objectStartArray.hpp" 29 #include "memory/allocation.hpp" 30 31 // 32 // PSPromotionLAB is a parallel scavenge promotion lab. This class acts very 33 // much like a MutableSpace. We couldn't embed a MutableSpace, though, as 34 // it has a considerable number of asserts and invariants that are violated. 35 // 36 37 class ObjectStartArray; 38 39 class PSPromotionLAB : public CHeapObj<mtGC> { 40 protected: 41 static size_t filler_header_size; 42 43 enum LabState { 44 needs_flush, 45 flushed, 46 zero_size 47 }; 48 49 HeapWord* _top; 50 HeapWord* _bottom; 51 HeapWord* _end; 52 LabState _state; 53 54 void set_top(HeapWord* value) { _top = value; } 55 void set_bottom(HeapWord* value) { _bottom = value; } 56 void set_end(HeapWord* value) { _end = value; } 57 58 // The shared initialize code invokes this. 59 debug_only(virtual bool lab_is_valid(MemRegion lab) { return false; }); 60 61 PSPromotionLAB() : _top(NULL), _bottom(NULL), _end(NULL) { } 62 63 public: 64 // Filling and flushing. 65 void initialize(MemRegion lab); 66 67 virtual void flush(); 68 69 // Accessors 70 HeapWord* bottom() const { return _bottom; } 71 HeapWord* end() const { return _end; } 72 HeapWord* top() const { return _top; } 73 74 bool is_flushed() { return _state == flushed; } 75 76 bool unallocate_object(HeapWord* obj, size_t obj_size); 77 78 // Returns a subregion containing all objects in this space. 79 MemRegion used_region() { return MemRegion(bottom(), top()); } 80 81 // Boolean querries. 82 bool is_empty() const { return used() == 0; } 83 bool not_empty() const { return used() > 0; } 84 bool contains(const void* p) const { return _bottom <= p && p < _end; } 85 86 // Size computations. Sizes are in bytes. 87 size_t capacity() const { return byte_size(bottom(), end()); } 88 size_t used() const { return byte_size(bottom(), top()); } 89 size_t free() const { return byte_size(top(), end()); } 90 }; 91 92 class PSYoungPromotionLAB : public PSPromotionLAB { 93 public: 94 PSYoungPromotionLAB() { } 95 96 // Not MT safe 97 HeapWord* allocate(size_t size) { 98 // Can't assert this, when young fills, we keep the LAB around, but flushed. 99 // assert(_state != flushed, "Sanity"); 100 HeapWord* obj = top(); 101 HeapWord* new_top = obj + size; 102 // The 'new_top>obj' check is needed to detect overflow of obj+size. 103 if (new_top > obj && new_top <= end()) { 104 set_top(new_top); 105 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top), 106 "checking alignment"); 107 return obj; 108 } 109 110 return NULL; 111 } 112 113 debug_only(virtual bool lab_is_valid(MemRegion lab)); 114 }; 115 116 class PSOldPromotionLAB : public PSPromotionLAB { 117 private: 118 ObjectStartArray* _start_array; 119 120 public: 121 PSOldPromotionLAB() : _start_array(NULL) { } 122 PSOldPromotionLAB(ObjectStartArray* start_array) : _start_array(start_array) { } 123 124 void set_start_array(ObjectStartArray* start_array) { _start_array = start_array; } 125 126 void flush(); 127 128 // Not MT safe 129 HeapWord* allocate(size_t size) { 130 // Cannot test for this now that we're doing promotion failures 131 // assert(_state != flushed, "Sanity"); 132 assert(_start_array != NULL, "Sanity"); 133 HeapWord* obj = top(); 134 HeapWord* new_top = obj + size; 135 // The 'new_top>obj' check is needed to detect overflow of obj+size. 136 if (new_top > obj && new_top <= end()) { 137 set_top(new_top); 138 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top), 139 "checking alignment"); 140 _start_array->allocate_block(obj); 141 return obj; 142 } 143 144 return NULL; 145 } 146 147 debug_only(virtual bool lab_is_valid(MemRegion lab)); 148 }; 149 150 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPROMOTIONLAB_HPP