1 /* 2 * Copyright (c) 2014, 2020, 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_GC_G1_G1HEAPREGIONATTR_HPP 26 #define SHARE_GC_G1_G1HEAPREGIONATTR_HPP 27 28 #include "gc/g1/g1BiasedArray.hpp" 29 #include "gc/g1/heapRegion.hpp" 30 31 // Per-region attributes often used during garbage collection to avoid costly 32 // lookups for that information all over the place. 33 struct G1HeapRegionAttr { 34 public: 35 #if defined(_M_ARM64)&& defined(_MSC_VER) && _MSC_VER <= 1927 36 // workaround for MSCV ARM64 bug 37 // https://developercommunity.visualstudio.com/content/problem/1079221/arm64-bad-code-generation-around-signed-char-arith.html 38 typedef int32_t region_type_t; 39 #else 40 typedef int8_t region_type_t; 41 #endif 42 typedef uint8_t needs_remset_update_t; 43 44 private: 45 needs_remset_update_t _needs_remset_update; 46 region_type_t _type; 47 48 public: 49 // Selection of the values for the _type field were driven to micro-optimize the 50 // encoding and frequency of the checks. 51 // The most common check for a given reference is whether the region is in the 52 // collection set or not, and which generation this region is in. 53 // The selected encoding allows us to use a single check (> NotInCSet) for the 54 // former. 55 // 56 // The other values are used for objects in regions requiring various special handling, 57 // eager reclamation of humongous objects or optional regions. 58 static const region_type_t Optional = -3; // The region is optional not in the current collection set. 59 static const region_type_t Humongous = -2; // The region is a humongous candidate not in the current collection set. 60 static const region_type_t NotInCSet = -1; // The region is not in the collection set. 61 static const region_type_t Young = 0; // The region is in the collection set and a young region. 62 static const region_type_t Old = 1; // The region is in the collection set and an old region. 63 static const region_type_t Num = 2; 64 G1HeapRegionAttrG1HeapRegionAttr65 G1HeapRegionAttr(region_type_t type = NotInCSet, bool needs_remset_update = false) : 66 _needs_remset_update(needs_remset_update), _type(type) { 67 68 assert(is_valid(), "Invalid type %d", _type); 69 } 70 typeG1HeapRegionAttr71 region_type_t type() const { return _type; } 72 get_type_strG1HeapRegionAttr73 const char* get_type_str() const { 74 switch (type()) { 75 case Optional: return "Optional"; 76 case Humongous: return "Humongous"; 77 case NotInCSet: return "NotInCSet"; 78 case Young: return "Young"; 79 case Old: return "Old"; 80 default: ShouldNotReachHere(); return ""; 81 } 82 } 83 needs_remset_updateG1HeapRegionAttr84 bool needs_remset_update() const { return _needs_remset_update != 0; } 85 set_oldG1HeapRegionAttr86 void set_old() { _type = Old; } clear_humongousG1HeapRegionAttr87 void clear_humongous() { 88 assert(is_humongous() || !is_in_cset(), "must be"); 89 _type = NotInCSet; 90 } set_has_remsetG1HeapRegionAttr91 void set_has_remset(bool value) { _needs_remset_update = value ? 1 : 0; } 92 is_in_cset_or_humongousG1HeapRegionAttr93 bool is_in_cset_or_humongous() const { return is_in_cset() || is_humongous(); } is_in_csetG1HeapRegionAttr94 bool is_in_cset() const { return type() >= Young; } 95 is_humongousG1HeapRegionAttr96 bool is_humongous() const { return type() == Humongous; } is_youngG1HeapRegionAttr97 bool is_young() const { return type() == Young; } is_oldG1HeapRegionAttr98 bool is_old() const { return type() == Old; } is_optionalG1HeapRegionAttr99 bool is_optional() const { return type() == Optional; } 100 101 #ifdef ASSERT is_defaultG1HeapRegionAttr102 bool is_default() const { return type() == NotInCSet; } is_validG1HeapRegionAttr103 bool is_valid() const { return (type() >= Optional && type() < Num); } is_valid_genG1HeapRegionAttr104 bool is_valid_gen() const { return (type() >= Young && type() <= Old); } 105 #endif 106 }; 107 108 // Table for all regions in the heap for above. 109 // 110 // We use this to speed up reference processing during young collection and 111 // quickly reclaim humongous objects. For the latter, at the start of GC, by adding 112 // it as a humongous region we enable special handling for that region. During the 113 // reference iteration closures, when we see a humongous region, we then simply mark 114 // it as referenced, i.e. live, and remove it from this table to prevent further 115 // processing on it. 116 // 117 // This means that this does NOT completely correspond to the information stored 118 // in a HeapRegion, but only to what is interesting for the current young collection. 119 class G1HeapRegionAttrBiasedMappedArray : public G1BiasedMappedArray<G1HeapRegionAttr> { 120 protected: default_value() const121 G1HeapRegionAttr default_value() const { return G1HeapRegionAttr(G1HeapRegionAttr::NotInCSet); } 122 public: set_optional(uintptr_t index,bool needs_remset_update)123 void set_optional(uintptr_t index, bool needs_remset_update) { 124 assert(get_by_index(index).is_default(), 125 "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str()); 126 set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Optional, needs_remset_update)); 127 } 128 set_humongous(uintptr_t index,bool needs_remset_update)129 void set_humongous(uintptr_t index, bool needs_remset_update) { 130 assert(get_by_index(index).is_default(), 131 "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str()); 132 set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Humongous, needs_remset_update)); 133 } 134 clear_humongous(uintptr_t index)135 void clear_humongous(uintptr_t index) { 136 get_ref_by_index(index)->clear_humongous(); 137 } 138 set_has_remset(uintptr_t index,bool needs_remset_update)139 void set_has_remset(uintptr_t index, bool needs_remset_update) { 140 get_ref_by_index(index)->set_has_remset(needs_remset_update); 141 } 142 set_in_young(uintptr_t index)143 void set_in_young(uintptr_t index) { 144 assert(get_by_index(index).is_default(), 145 "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str()); 146 set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Young, true)); 147 } 148 set_in_old(uintptr_t index,bool needs_remset_update)149 void set_in_old(uintptr_t index, bool needs_remset_update) { 150 assert(get_by_index(index).is_default(), 151 "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str()); 152 set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Old, needs_remset_update)); 153 } 154 is_in_cset_or_humongous(HeapWord * addr) const155 bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); } is_in_cset(HeapWord * addr) const156 bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); } is_in_cset(const HeapRegion * hr) const157 bool is_in_cset(const HeapRegion* hr) const { return get_by_index(hr->hrm_index()).is_in_cset(); } at(HeapWord * addr) const158 G1HeapRegionAttr at(HeapWord* addr) const { return get_by_address(addr); } clear()159 void clear() { G1BiasedMappedArray<G1HeapRegionAttr>::clear(); } clear(const HeapRegion * hr)160 void clear(const HeapRegion* hr) { return set_by_index(hr->hrm_index(), G1HeapRegionAttr(G1HeapRegionAttr::NotInCSet)); } 161 }; 162 163 #endif // SHARE_GC_G1_G1HEAPREGIONATTR_HPP 164