1 /* 2 * Copyright (c) 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 #include "precompiled.hpp" 26 #include "ci/ciUtilities.hpp" 27 #include "gc/shared/cardTable.hpp" 28 #include "gc/shared/cardTableBarrierSet.hpp" 29 #include "gc/shared/c2/cardTableBarrierSetC2.hpp" 30 #include "opto/arraycopynode.hpp" 31 #include "opto/graphKit.hpp" 32 #include "opto/idealKit.hpp" 33 #include "opto/macro.hpp" 34 #include "utilities/macros.hpp" 35 36 #define __ ideal. 37 38 Node* CardTableBarrierSetC2::byte_map_base_node(GraphKit* kit) const { 39 // Get base of card map 40 jbyte* card_table_base = ci_card_table_address(); 41 if (card_table_base != NULL) { 42 return kit->makecon(TypeRawPtr::make((address)card_table_base)); 43 } else { 44 return kit->null(); 45 } 46 } 47 48 // vanilla/CMS post barrier 49 // Insert a write-barrier store. This is to let generational GC work; we have 50 // to flag all oop-stores before the next GC point. 51 void CardTableBarrierSetC2::post_barrier(GraphKit* kit, 52 Node* ctl, 53 Node* oop_store, 54 Node* obj, 55 Node* adr, 56 uint adr_idx, 57 Node* val, 58 BasicType bt, 59 bool use_precise) const { 60 CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(BarrierSet::barrier_set()); 61 CardTable* ct = ctbs->card_table(); 62 // No store check needed if we're storing a NULL or an old object 63 // (latter case is probably a string constant). The concurrent 64 // mark sweep garbage collector, however, needs to have all nonNull 65 // oop updates flagged via card-marks. 66 if (val != NULL && val->is_Con()) { 67 // must be either an oop or NULL 68 const Type* t = val->bottom_type(); 69 if (t == TypePtr::NULL_PTR || t == Type::TOP) 70 // stores of null never (?) need barriers 71 return; 72 } 73 74 if (use_ReduceInitialCardMarks() 75 && obj == kit->just_allocated_object(kit->control())) { 76 // We can skip marks on a freshly-allocated object in Eden. 77 // Keep this code in sync with new_deferred_store_barrier() in runtime.cpp. 78 // That routine informs GC to take appropriate compensating steps, 79 // upon a slow-path allocation, so as to make this card-mark 80 // elision safe. 81 return; 82 } 83 84 if (!use_precise) { 85 // All card marks for a (non-array) instance are in one place: 86 adr = obj; 87 } 88 // (Else it's an array (or unknown), and we want more precise card marks.) 89 assert(adr != NULL, ""); 90 91 IdealKit ideal(kit, true); 92 93 // Convert the pointer to an int prior to doing math on it 94 Node* cast = __ CastPX(__ ctrl(), adr); 95 96 // Divide by card size 97 Node* card_offset = __ URShiftX( cast, __ ConI(CardTable::card_shift) ); 98 99 // Combine card table base and card offset 100 Node* card_adr = __ AddP(__ top(), byte_map_base_node(kit), card_offset ); 101 102 // Get the alias_index for raw card-mark memory 103 int adr_type = Compile::AliasIdxRaw; 104 Node* zero = __ ConI(0); // Dirty card value 105 106 if (UseCondCardMark) { 107 if (ct->scanned_concurrently()) { 108 kit->insert_mem_bar(Op_MemBarVolatile, oop_store); 109 __ sync_kit(kit); 110 } 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(!ct->scanned_concurrently()) { 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 CardTableBarrierSetC2::clone(GraphKit* kit, Node* src_base, Node* dst_base, Node* countx, bool is_array) const { 139 BarrierSetC2::clone(kit, src_base, dst_base, countx, 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 intptr_t unused_offset; 153 Node* dst = AddPNode::Ideal_base_and_offset(dst_base, &kit->gvn(), unused_offset); 154 assert(dst != NULL, "dst_base not an Addp"); 155 post_barrier(kit, kit->control(), 156 kit->memory(raw_adr_type), 157 dst, 158 no_particular_field, 159 raw_adr_idx, 160 no_particular_value, 161 T_OBJECT, 162 false); 163 } 164 } 165 166 bool CardTableBarrierSetC2::use_ReduceInitialCardMarks() const { 167 return ReduceInitialCardMarks; 168 } 169 170 bool CardTableBarrierSetC2::is_gc_barrier_node(Node* node) const { 171 return ModRefBarrierSetC2::is_gc_barrier_node(node) || node->Opcode() == Op_StoreCM; 172 } 173 174 void CardTableBarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { 175 assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required"); 176 Node *shift = node->unique_out(); 177 Node *addp = shift->unique_out(); 178 for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) { 179 Node *mem = addp->last_out(j); 180 if (UseCondCardMark && mem->is_Load()) { 181 assert(mem->Opcode() == Op_LoadB, "unexpected code shape"); 182 // The load is checking if the card has been written so 183 // replace it with zero to fold the test. 184 macro->replace_node(mem, macro->intcon(0)); 185 continue; 186 } 187 assert(mem->is_Store(), "store required"); 188 macro->replace_node(mem, mem->in(MemNode::Memory)); 189 } 190 } 191 192 bool CardTableBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, ArrayCopyPhase phase) const { 193 bool is_oop = type == T_OBJECT || type == T_ARRAY; 194 return is_oop && (!tightly_coupled_alloc || !use_ReduceInitialCardMarks()); 195 }