1 /* 2 * Copyright (c) 2017, 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 #include "precompiled.hpp" 26 #include "opto/arraycopynode.hpp" 27 #include "opto/graphKit.hpp" 28 #include "opto/idealKit.hpp" 29 #include "opto/macro.hpp" 30 #include "gc/shared/c2CardTableModRefBSCodeGen.hpp" 31 #include "utilities/macros.hpp" 32 33 #define __ ideal. 34 35 Node* C2CardTableModRefBSCodeGen::byte_map_base_node(GraphKit* kit) { 36 // Get base of card map 37 CardTableModRefBS* ct = 38 barrier_set_cast<CardTableModRefBS>(Universe::heap()->barrier_set()); 39 assert(sizeof(*ct->card_table()->byte_map_base()) == sizeof(jbyte), "adjust users of this code"); 40 if (ct->card_table()->byte_map_base() != NULL) { 41 return kit->makecon(TypeRawPtr::make((address)ct->card_table()->byte_map_base())); 42 } else { 43 return kit->null(); 44 } 45 } 46 47 // vanilla/CMS post barrier 48 // Insert a write-barrier store. This is to let generational GC work; we have 49 // to flag all oop-stores before the next GC point. 50 void C2CardTableModRefBSCodeGen::post_barrier(GraphKit* kit, 51 Node* ctl, 52 Node* oop_store, 53 Node* obj, 54 Node* adr, 55 uint adr_idx, 56 Node* val, 57 BasicType bt, 58 bool use_precise) { 59 // No store check needed if we're storing a NULL or an old object 60 // (latter case is probably a string constant). The concurrent 61 // mark sweep garbage collector, however, needs to have all nonNull 62 // oop updates flagged via card-marks. 63 if (val != NULL && val->is_Con()) { 64 // must be either an oop or NULL 65 const Type* t = val->bottom_type(); 66 if (t == TypePtr::NULL_PTR || t == Type::TOP) 67 // stores of null never (?) need barriers 68 return; 69 } 70 71 if (use_ReduceInitialCardMarks() 72 && obj == kit->just_allocated_object(kit->control())) { 73 // We can skip marks on a freshly-allocated object in Eden. 74 // Keep this code in sync with new_deferred_store_barrier() in runtime.cpp. 75 // That routine informs GC to take appropriate compensating steps, 76 // upon a slow-path allocation, so as to make this card-mark 77 // elision safe. 78 return; 79 } 80 81 if (!use_precise) { 82 // All card marks for a (non-array) instance are in one place: 83 adr = obj; 84 } 85 // (Else it's an array (or unknown), and we want more precise card marks.) 86 assert(adr != NULL, ""); 87 88 IdealKit ideal(kit, true); 89 90 // Convert the pointer to an int prior to doing math on it 91 Node* cast = __ CastPX(__ ctrl(), adr); 92 93 // Divide by card size 94 assert(Universe::heap()->barrier_set()->is_a(BarrierSet::CardTableModRef), 95 "Only one we handle so far."); 96 Node* card_offset = __ URShiftX( cast, __ ConI(CardTable::card_shift) ); 97 98 // Combine card table base and card offset 99 Node* card_adr = __ AddP(__ top(), byte_map_base_node(kit), card_offset ); 100 101 // Get the alias_index for raw card-mark memory 102 int adr_type = Compile::AliasIdxRaw; 103 Node* zero = __ ConI(0); // Dirty card value 104 105 if (UseConcMarkSweepGC && UseCondCardMark) { 106 kit->insert_mem_bar(Op_MemBarVolatile, oop_store); 107 __ sync_kit(kit); 108 } 109 110 if (UseCondCardMark) { 111 // The classic GC reference write barrier is typically implemented 112 // as a store into the global card mark table. Unfortunately 113 // unconditional stores can result in false sharing and excessive 114 // coherence traffic as well as false transactional aborts. 115 // UseCondCardMark enables MP "polite" conditional card mark 116 // stores. In theory we could relax the load from ctrl() to 117 // no_ctrl, but that doesn't buy much latitude. 118 Node* card_val = __ load( __ ctrl(), card_adr, TypeInt::BYTE, T_BYTE, adr_type); 119 __ if_then(card_val, BoolTest::ne, zero); 120 } 121 122 // Smash zero into card 123 if( !UseConcMarkSweepGC ) { 124 __ store(__ ctrl(), card_adr, zero, T_BYTE, adr_type, MemNode::unordered); 125 } else { 126 // Specialized path for CM store barrier 127 __ storeCM(__ ctrl(), card_adr, zero, oop_store, adr_idx, T_BYTE, adr_type); 128 } 129 130 if (UseCondCardMark) { 131 __ end_if(); 132 } 133 134 // Final sync IdealKit and GraphKit. 135 kit->final_sync(ideal); 136 } 137 138 void C2CardTableModRefBSCodeGen::clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) { 139 C2BarrierSetCodeGen::clone(kit, src, dst, size, is_array); 140 const TypePtr* raw_adr_type = TypeRawPtr::BOTTOM; 141 142 // If necessary, emit some card marks afterwards. (Non-arrays only.) 143 bool card_mark = !is_array && !use_ReduceInitialCardMarks(); 144 if (card_mark) { 145 assert(!is_array, ""); 146 // Put in store barrier for any and all oops we are sticking 147 // into this object. (We could avoid this if we could prove 148 // that the object type contains no oop fields at all.) 149 Node* no_particular_value = NULL; 150 Node* no_particular_field = NULL; 151 int raw_adr_idx = Compile::AliasIdxRaw; 152 post_barrier(kit, kit->control(), 153 kit->memory(raw_adr_type), 154 dst, 155 no_particular_field, 156 raw_adr_idx, 157 no_particular_value, 158 T_OBJECT, 159 false); 160 } 161 } 162 163 bool C2CardTableModRefBSCodeGen::use_ReduceInitialCardMarks() { 164 BarrierSet *bs = Universe::heap()->barrier_set(); 165 return barrier_set_cast<CardTableModRefBS>(bs)->can_elide_tlab_store_barriers() 166 && ReduceInitialCardMarks; 167 } 168 169 bool C2CardTableModRefBSCodeGen::is_gc_barrier_node(Node* node) { 170 return C2ModRefBSCodeGen::is_gc_barrier_node(node) || node->Opcode() == Op_StoreCM; 171 } 172 173 void C2CardTableModRefBSCodeGen::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) { 174 assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required"); 175 Node *shift = node->unique_out(); 176 Node *addp = shift->unique_out(); 177 for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) { 178 Node *mem = addp->last_out(j); 179 if (UseCondCardMark && mem->is_Load()) { 180 assert(mem->Opcode() == Op_LoadB, "unexpected code shape"); 181 // The load is checking if the card has been written so 182 // replace it with zero to fold the test. 183 macro->replace_node(mem, macro->intcon(0)); 184 continue; 185 } 186 assert(mem->is_Store(), "store required"); 187 macro->replace_node(mem, mem->in(MemNode::Memory)); 188 } 189 } 190 191 bool C2CardTableModRefBSCodeGen::array_copy_requires_gc_barriers(BasicType type) { 192 return !use_ReduceInitialCardMarks(); 193 }