1 /* 2 * Copyright (c) 2014, 2018, 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_G1_G1INCSETSTATE_HPP 26 #define SHARE_VM_GC_G1_G1INCSETSTATE_HPP 27 28 #include "gc/g1/g1BiasedArray.hpp" 29 #include "gc/g1/heapRegion.hpp" 30 31 // Per-region state during garbage collection. 32 struct InCSetState { 33 public: 34 // We use different types to represent the state value. Particularly SPARC puts 35 // values in structs from "left to right", i.e. MSB to LSB. This results in many 36 // unnecessary shift operations when loading and storing values of this type. 37 // This degrades performance significantly (>10%) on that platform. 38 // Other tested ABIs do not seem to have this problem, and actually tend to 39 // favor smaller types, so we use the smallest usable type there. 40 #ifdef SPARC 41 #define CSETSTATE_FORMAT INTPTR_FORMAT 42 typedef intptr_t in_cset_state_t; 43 #else 44 #define CSETSTATE_FORMAT "%d" 45 typedef int8_t in_cset_state_t; 46 #endif 47 private: 48 in_cset_state_t _value; 49 public: 50 enum { 51 // Selection of the values were driven to micro-optimize the encoding and 52 // frequency of the checks. 53 // The most common check is whether the region is in the collection set or not, 54 // this encoding allows us to use an > 0 check. 55 // The positive values are encoded in increasing generation order, which 56 // makes getting the next generation fast by a simple increment. They are also 57 // used to index into arrays. 58 // The negative values are used for objects requiring various special cases, 59 // for example eager reclamation of humongous objects. 60 Humongous = -1, // The region is humongous 61 NotInCSet = 0, // The region is not in the collection set. 62 Young = 1, // The region is in the collection set and a young region. 63 Old = 2, // The region is in the collection set and an old region. 64 Num 65 }; 66 InCSetStateInCSetState67 InCSetState(in_cset_state_t value = NotInCSet) : _value(value) { 68 assert(is_valid(), "Invalid state %d", _value); 69 } 70 valueInCSetState71 in_cset_state_t value() const { return _value; } 72 set_oldInCSetState73 void set_old() { _value = Old; } 74 is_in_cset_or_humongousInCSetState75 bool is_in_cset_or_humongous() const { return is_in_cset() || is_humongous(); } is_in_csetInCSetState76 bool is_in_cset() const { return _value > NotInCSet; } 77 is_humongousInCSetState78 bool is_humongous() const { return _value == Humongous; } is_youngInCSetState79 bool is_young() const { return _value == Young; } is_oldInCSetState80 bool is_old() const { return _value == Old; } 81 82 #ifdef ASSERT is_defaultInCSetState83 bool is_default() const { return _value == NotInCSet; } is_validInCSetState84 bool is_valid() const { return (_value >= Humongous) && (_value < Num); } is_valid_genInCSetState85 bool is_valid_gen() const { return (_value >= Young && _value <= Old); } 86 #endif 87 }; 88 89 // Instances of this class are used for quick tests on whether a reference points 90 // into the collection set and into which generation or is a humongous object 91 // 92 // Each of the array's elements indicates whether the corresponding region is in 93 // the collection set and if so in which generation, or a humongous region. 94 // 95 // We use this to speed up reference processing during young collection and 96 // quickly reclaim humongous objects. For the latter, by making a humongous region 97 // succeed this test, we sort-of add it to the collection set. During the reference 98 // iteration closures, when we see a humongous region, we then simply mark it as 99 // referenced, i.e. live. 100 class G1InCSetStateFastTestBiasedMappedArray : public G1BiasedMappedArray<InCSetState> { 101 protected: default_value() const102 InCSetState default_value() const { return InCSetState::NotInCSet; } 103 public: set_humongous(uintptr_t index)104 void set_humongous(uintptr_t index) { 105 assert(get_by_index(index).is_default(), 106 "State at index " INTPTR_FORMAT " should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()); 107 set_by_index(index, InCSetState::Humongous); 108 } 109 clear_humongous(uintptr_t index)110 void clear_humongous(uintptr_t index) { 111 set_by_index(index, InCSetState::NotInCSet); 112 } 113 set_in_young(uintptr_t index)114 void set_in_young(uintptr_t index) { 115 assert(get_by_index(index).is_default(), 116 "State at index " INTPTR_FORMAT " should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()); 117 set_by_index(index, InCSetState::Young); 118 } 119 set_in_old(uintptr_t index)120 void set_in_old(uintptr_t index) { 121 assert(get_by_index(index).is_default(), 122 "State at index " INTPTR_FORMAT " should be default but is " CSETSTATE_FORMAT, index, get_by_index(index).value()); 123 set_by_index(index, InCSetState::Old); 124 } 125 is_in_cset_or_humongous(HeapWord * addr) const126 bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); } is_in_cset(HeapWord * addr) const127 bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); } is_in_cset(const HeapRegion * hr) const128 bool is_in_cset(const HeapRegion* hr) const { return get_by_index(hr->hrm_index()).is_in_cset(); } at(HeapWord * addr) const129 InCSetState at(HeapWord* addr) const { return get_by_address(addr); } clear()130 void clear() { G1BiasedMappedArray<InCSetState>::clear(); } clear(const HeapRegion * hr)131 void clear(const HeapRegion* hr) { return set_by_index(hr->hrm_index(), InCSetState::NotInCSet); } 132 }; 133 134 #endif // SHARE_VM_GC_G1_G1INCSETSTATE_HPP 135