1 /* 2 * Copyright (c) 2002, 2015, 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 "gc_interface/collectedHeap.hpp" 30 #include "memory/allocation.hpp" 31 32 // 33 // PSPromotionLAB is a parallel scavenge promotion lab. This class acts very 34 // much like a MutableSpace. We couldn't embed a MutableSpace, though, as 35 // it has a considerable number of asserts and invariants that are violated. 36 // 37 38 class ObjectStartArray; 39 40 class PSPromotionLAB : public CHeapObj<mtGC> { 41 protected: 42 static size_t filler_header_size; 43 44 enum LabState { 45 needs_flush, 46 flushed, 47 zero_size 48 }; 49 50 HeapWord* _top; 51 HeapWord* _bottom; 52 HeapWord* _end; 53 LabState _state; 54 55 void set_top(HeapWord* value) { _top = value; } 56 void set_bottom(HeapWord* value) { _bottom = value; } 57 void set_end(HeapWord* value) { _end = value; } 58 59 // The shared initialize code invokes this. 60 debug_only(virtual bool lab_is_valid(MemRegion lab) { return false; }); 61 62 PSPromotionLAB() : _top(NULL), _bottom(NULL), _end(NULL), _state(zero_size) { } 63 64 public: 65 // Filling and flushing. 66 void initialize(MemRegion lab); 67 68 virtual void flush(); 69 70 // Accessors 71 HeapWord* bottom() const { return _bottom; } 72 HeapWord* end() const { return _end; } 73 HeapWord* top() const { return _top; } 74 75 bool is_flushed() { return _state == flushed; } 76 77 bool unallocate_object(HeapWord* obj, size_t obj_size); 78 79 // Returns a subregion containing all objects in this space. 80 MemRegion used_region() { return MemRegion(bottom(), top()); } 81 82 // Boolean queries. 83 bool is_empty() const { return used() == 0; } 84 bool not_empty() const { return used() > 0; } 85 bool contains(const void* p) const { return _bottom <= p && p < _end; } 86 87 // Size computations. Sizes are in bytes. 88 size_t capacity() const { return byte_size(bottom(), end()); } 89 size_t used() const { return byte_size(bottom(), top()); } 90 size_t free() const { return byte_size(top(), end()); } 91 }; 92 93 class PSYoungPromotionLAB : public PSPromotionLAB { 94 public: 95 PSYoungPromotionLAB() { } 96 97 // Not MT safe 98 inline HeapWord* allocate(size_t size); 99 100 debug_only(virtual bool lab_is_valid(MemRegion lab);) 101 }; 102 103 class PSOldPromotionLAB : public PSPromotionLAB { 104 private: 105 ObjectStartArray* _start_array; 106 107 public: 108 PSOldPromotionLAB() : _start_array(NULL) { } 109 PSOldPromotionLAB(ObjectStartArray* start_array) : _start_array(start_array) { } 110 111 void set_start_array(ObjectStartArray* start_array) { _start_array = start_array; } 112 113 void flush(); 114 115 // Not MT safe 116 HeapWord* allocate(size_t size) { 117 // Cannot test for this now that we're doing promotion failures 118 // assert(_state != flushed, "Sanity"); 119 assert(_start_array != NULL, "Sanity"); 120 HeapWord* obj = top(); 121 HeapWord* new_top = obj + size; 122 // The 'new_top>obj' check is needed to detect overflow of obj+size. 123 if (new_top > obj && new_top <= end()) { 124 set_top(new_top); 125 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top), 126 "checking alignment"); 127 _start_array->allocate_block(obj); 128 return obj; 129 } 130 131 return NULL; 132 } 133 134 debug_only(virtual bool lab_is_valid(MemRegion lab)); 135 }; 136 137 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPROMOTIONLAB_HPP