1 /* 2 * Copyright (c) 2018, 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 #include "precompiled.hpp" 26 #include "gc/g1/c2/g1BarrierSetC2.hpp" 27 #include "gc/g1/g1BarrierSet.hpp" 28 #include "gc/g1/g1BarrierSetRuntime.hpp" 29 #include "gc/g1/g1CardTable.hpp" 30 #include "gc/g1/g1ThreadLocalData.hpp" 31 #include "gc/g1/heapRegion.hpp" 32 #include "opto/arraycopynode.hpp" 33 #include "opto/compile.hpp" 34 #include "opto/escape.hpp" 35 #include "opto/graphKit.hpp" 36 #include "opto/idealKit.hpp" 37 #include "opto/macro.hpp" 38 #include "opto/rootnode.hpp" 39 #include "opto/type.hpp" 40 #include "utilities/macros.hpp" 41 42 const TypeFunc *G1BarrierSetC2::write_ref_field_pre_entry_Type() { 43 const Type **fields = TypeTuple::fields(2); 44 fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL; // original field value 45 fields[TypeFunc::Parms+1] = TypeRawPtr::NOTNULL; // thread 46 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields); 47 48 // create result type (range) 49 fields = TypeTuple::fields(0); 50 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+0, fields); 51 52 return TypeFunc::make(domain, range); 53 } 54 55 const TypeFunc *G1BarrierSetC2::write_ref_field_post_entry_Type() { 56 const Type **fields = TypeTuple::fields(2); 57 fields[TypeFunc::Parms+0] = TypeRawPtr::NOTNULL; // Card addr 58 fields[TypeFunc::Parms+1] = TypeRawPtr::NOTNULL; // thread 59 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields); 60 61 // create result type (range) 62 fields = TypeTuple::fields(0); 63 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms, fields); 64 65 return TypeFunc::make(domain, range); 66 } 67 68 #define __ ideal. 69 /* 70 * Determine if the G1 pre-barrier can be removed. The pre-barrier is 71 * required by SATB to make sure all objects live at the start of the 72 * marking are kept alive, all reference updates need to any previous 73 * reference stored before writing. 74 * 75 * If the previous value is NULL there is no need to save the old value. 76 * References that are NULL are filtered during runtime by the barrier 77 * code to avoid unnecessary queuing. 78 * 79 * However in the case of newly allocated objects it might be possible to 80 * prove that the reference about to be overwritten is NULL during compile 81 * time and avoid adding the barrier code completely. 82 * 83 * The compiler needs to determine that the object in which a field is about 84 * to be written is newly allocated, and that no prior store to the same field 85 * has happened since the allocation. 86 * 87 * Returns true if the pre-barrier can be removed 88 */ 89 bool G1BarrierSetC2::g1_can_remove_pre_barrier(GraphKit* kit, 90 PhaseTransform* phase, 91 Node* adr, 92 BasicType bt, 93 uint adr_idx) const { 94 intptr_t offset = 0; 95 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 96 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 97 98 if (offset == Type::OffsetBot) { 99 return false; // cannot unalias unless there are precise offsets 100 } 101 102 if (alloc == NULL) { 103 return false; // No allocation found 104 } 105 106 intptr_t size_in_bytes = type2aelembytes(bt); 107 108 Node* mem = kit->memory(adr_idx); // start searching here... 109 110 for (int cnt = 0; cnt < 50; cnt++) { 111 112 if (mem->is_Store()) { 113 114 Node* st_adr = mem->in(MemNode::Address); 115 intptr_t st_offset = 0; 116 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 117 118 if (st_base == NULL) { 119 break; // inscrutable pointer 120 } 121 122 // Break we have found a store with same base and offset as ours so break 123 if (st_base == base && st_offset == offset) { 124 break; 125 } 126 127 if (st_offset != offset && st_offset != Type::OffsetBot) { 128 const int MAX_STORE = BytesPerLong; 129 if (st_offset >= offset + size_in_bytes || 130 st_offset <= offset - MAX_STORE || 131 st_offset <= offset - mem->as_Store()->memory_size()) { 132 // Success: The offsets are provably independent. 133 // (You may ask, why not just test st_offset != offset and be done? 134 // The answer is that stores of different sizes can co-exist 135 // in the same sequence of RawMem effects. We sometimes initialize 136 // a whole 'tile' of array elements with a single jint or jlong.) 137 mem = mem->in(MemNode::Memory); 138 continue; // advance through independent store memory 139 } 140 } 141 142 if (st_base != base 143 && MemNode::detect_ptr_independence(base, alloc, st_base, 144 AllocateNode::Ideal_allocation(st_base, phase), 145 phase)) { 146 // Success: The bases are provably independent. 147 mem = mem->in(MemNode::Memory); 148 continue; // advance through independent store memory 149 } 150 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 151 152 InitializeNode* st_init = mem->in(0)->as_Initialize(); 153 AllocateNode* st_alloc = st_init->allocation(); 154 155 // Make sure that we are looking at the same allocation site. 156 // The alloc variable is guaranteed to not be null here from earlier check. 157 if (alloc == st_alloc) { 158 // Check that the initialization is storing NULL so that no previous store 159 // has been moved up and directly write a reference 160 Node* captured_store = st_init->find_captured_store(offset, 161 type2aelembytes(T_OBJECT), 162 phase); 163 if (captured_store == NULL || captured_store == st_init->zero_memory()) { 164 return true; 165 } 166 } 167 } 168 169 // Unless there is an explicit 'continue', we must bail out here, 170 // because 'mem' is an inscrutable memory state (e.g., a call). 171 break; 172 } 173 174 return false; 175 } 176 177 // G1 pre/post barriers 178 void G1BarrierSetC2::pre_barrier(GraphKit* kit, 179 bool do_load, 180 Node* ctl, 181 Node* obj, 182 Node* adr, 183 uint alias_idx, 184 Node* val, 185 const TypeOopPtr* val_type, 186 Node* pre_val, 187 BasicType bt) const { 188 // Some sanity checks 189 // Note: val is unused in this routine. 190 191 if (do_load) { 192 // We need to generate the load of the previous value 193 assert(obj != NULL, "must have a base"); 194 assert(adr != NULL, "where are loading from?"); 195 assert(pre_val == NULL, "loaded already?"); 196 assert(val_type != NULL, "need a type"); 197 198 if (use_ReduceInitialCardMarks() 199 && g1_can_remove_pre_barrier(kit, &kit->gvn(), adr, bt, alias_idx)) { 200 return; 201 } 202 203 } else { 204 // In this case both val_type and alias_idx are unused. 205 assert(pre_val != NULL, "must be loaded already"); 206 // Nothing to be done if pre_val is null. 207 if (pre_val->bottom_type() == TypePtr::NULL_PTR) return; 208 assert(pre_val->bottom_type()->basic_type() == T_OBJECT, "or we shouldn't be here"); 209 } 210 assert(bt == T_OBJECT, "or we shouldn't be here"); 211 212 IdealKit ideal(kit, true); 213 214 Node* tls = __ thread(); // ThreadLocalStorage 215 216 Node* no_base = __ top(); 217 Node* zero = __ ConI(0); 218 Node* zeroX = __ ConX(0); 219 220 float likely = PROB_LIKELY(0.999); 221 float unlikely = PROB_UNLIKELY(0.999); 222 223 BasicType active_type = in_bytes(SATBMarkQueue::byte_width_of_active()) == 4 ? T_INT : T_BYTE; 224 assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 4 || in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "flag width"); 225 226 // Offsets into the thread 227 const int marking_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()); 228 const int index_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_index_offset()); 229 const int buffer_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_buffer_offset()); 230 231 // Now the actual pointers into the thread 232 Node* marking_adr = __ AddP(no_base, tls, __ ConX(marking_offset)); 233 Node* buffer_adr = __ AddP(no_base, tls, __ ConX(buffer_offset)); 234 Node* index_adr = __ AddP(no_base, tls, __ ConX(index_offset)); 235 236 // Now some of the values 237 Node* marking = __ load(__ ctrl(), marking_adr, TypeInt::INT, active_type, Compile::AliasIdxRaw); 238 239 // if (!marking) 240 __ if_then(marking, BoolTest::ne, zero, unlikely); { 241 BasicType index_bt = TypeX_X->basic_type(); 242 assert(sizeof(size_t) == type2aelembytes(index_bt), "Loading G1 SATBMarkQueue::_index with wrong size."); 243 Node* index = __ load(__ ctrl(), index_adr, TypeX_X, index_bt, Compile::AliasIdxRaw); 244 245 if (do_load) { 246 // load original value 247 // alias_idx correct?? 248 pre_val = __ load(__ ctrl(), adr, val_type, bt, alias_idx); 249 } 250 251 // if (pre_val != NULL) 252 __ if_then(pre_val, BoolTest::ne, kit->null()); { 253 Node* buffer = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw); 254 255 // is the queue for this thread full? 256 __ if_then(index, BoolTest::ne, zeroX, likely); { 257 258 // decrement the index 259 Node* next_index = kit->gvn().transform(new SubXNode(index, __ ConX(sizeof(intptr_t)))); 260 261 // Now get the buffer location we will log the previous value into and store it 262 Node *log_addr = __ AddP(no_base, buffer, next_index); 263 __ store(__ ctrl(), log_addr, pre_val, T_OBJECT, Compile::AliasIdxRaw, MemNode::unordered); 264 // update the index 265 __ store(__ ctrl(), index_adr, next_index, index_bt, Compile::AliasIdxRaw, MemNode::unordered); 266 267 } __ else_(); { 268 269 // logging buffer is full, call the runtime 270 const TypeFunc *tf = write_ref_field_pre_entry_Type(); 271 __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_pre_entry), "write_ref_field_pre_entry", pre_val, tls); 272 } __ end_if(); // (!index) 273 } __ end_if(); // (pre_val != NULL) 274 } __ end_if(); // (!marking) 275 276 // Final sync IdealKit and GraphKit. 277 kit->final_sync(ideal); 278 } 279 280 /* 281 * G1 similar to any GC with a Young Generation requires a way to keep track of 282 * references from Old Generation to Young Generation to make sure all live 283 * objects are found. G1 also requires to keep track of object references 284 * between different regions to enable evacuation of old regions, which is done 285 * as part of mixed collections. References are tracked in remembered sets and 286 * is continuously updated as reference are written to with the help of the 287 * post-barrier. 288 * 289 * To reduce the number of updates to the remembered set the post-barrier 290 * filters updates to fields in objects located in the Young Generation, 291 * the same region as the reference, when the NULL is being written or 292 * if the card is already marked as dirty by an earlier write. 293 * 294 * Under certain circumstances it is possible to avoid generating the 295 * post-barrier completely if it is possible during compile time to prove 296 * the object is newly allocated and that no safepoint exists between the 297 * allocation and the store. 298 * 299 * In the case of slow allocation the allocation code must handle the barrier 300 * as part of the allocation in the case the allocated object is not located 301 * in the nursery; this would happen for humongous objects. 302 * 303 * Returns true if the post barrier can be removed 304 */ 305 bool G1BarrierSetC2::g1_can_remove_post_barrier(GraphKit* kit, 306 PhaseTransform* phase, Node* store, 307 Node* adr) const { 308 intptr_t offset = 0; 309 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 310 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 311 312 if (offset == Type::OffsetBot) { 313 return false; // cannot unalias unless there are precise offsets 314 } 315 316 if (alloc == NULL) { 317 return false; // No allocation found 318 } 319 320 // Start search from Store node 321 Node* mem = store->in(MemNode::Control); 322 if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 323 324 InitializeNode* st_init = mem->in(0)->as_Initialize(); 325 AllocateNode* st_alloc = st_init->allocation(); 326 327 // Make sure we are looking at the same allocation 328 if (alloc == st_alloc) { 329 return true; 330 } 331 } 332 333 return false; 334 } 335 336 // 337 // Update the card table and add card address to the queue 338 // 339 void G1BarrierSetC2::g1_mark_card(GraphKit* kit, 340 IdealKit& ideal, 341 Node* card_adr, 342 Node* oop_store, 343 uint oop_alias_idx, 344 Node* index, 345 Node* index_adr, 346 Node* buffer, 347 const TypeFunc* tf) const { 348 Node* zero = __ ConI(0); 349 Node* zeroX = __ ConX(0); 350 Node* no_base = __ top(); 351 BasicType card_bt = T_BYTE; 352 // Smash zero into card. MUST BE ORDERED WRT TO STORE 353 __ storeCM(__ ctrl(), card_adr, zero, oop_store, oop_alias_idx, card_bt, Compile::AliasIdxRaw); 354 355 // Now do the queue work 356 __ if_then(index, BoolTest::ne, zeroX); { 357 358 Node* next_index = kit->gvn().transform(new SubXNode(index, __ ConX(sizeof(intptr_t)))); 359 Node* log_addr = __ AddP(no_base, buffer, next_index); 360 361 // Order, see storeCM. 362 __ store(__ ctrl(), log_addr, card_adr, T_ADDRESS, Compile::AliasIdxRaw, MemNode::unordered); 363 __ store(__ ctrl(), index_adr, next_index, TypeX_X->basic_type(), Compile::AliasIdxRaw, MemNode::unordered); 364 365 } __ else_(); { 366 __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_post_entry), "write_ref_field_post_entry", card_adr, __ thread()); 367 } __ end_if(); 368 369 } 370 371 void G1BarrierSetC2::post_barrier(GraphKit* kit, 372 Node* ctl, 373 Node* oop_store, 374 Node* obj, 375 Node* adr, 376 uint alias_idx, 377 Node* val, 378 BasicType bt, 379 bool use_precise) const { 380 // If we are writing a NULL then we need no post barrier 381 382 if (val != NULL && val->is_Con() && val->bottom_type() == TypePtr::NULL_PTR) { 383 // Must be NULL 384 const Type* t = val->bottom_type(); 385 assert(t == Type::TOP || t == TypePtr::NULL_PTR, "must be NULL"); 386 // No post barrier if writing NULLx 387 return; 388 } 389 390 if (use_ReduceInitialCardMarks() && obj == kit->just_allocated_object(kit->control())) { 391 // We can skip marks on a freshly-allocated object in Eden. 392 // Keep this code in sync with new_deferred_store_barrier() in runtime.cpp. 393 // That routine informs GC to take appropriate compensating steps, 394 // upon a slow-path allocation, so as to make this card-mark 395 // elision safe. 396 return; 397 } 398 399 if (use_ReduceInitialCardMarks() 400 && g1_can_remove_post_barrier(kit, &kit->gvn(), oop_store, adr)) { 401 return; 402 } 403 404 if (!use_precise) { 405 // All card marks for a (non-array) instance are in one place: 406 adr = obj; 407 } 408 // (Else it's an array (or unknown), and we want more precise card marks.) 409 assert(adr != NULL, ""); 410 411 IdealKit ideal(kit, true); 412 413 Node* tls = __ thread(); // ThreadLocalStorage 414 415 BarrierSet* bs = BarrierSet::barrier_set(); 416 CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(bs); 417 CardTable* ct = ctbs->card_table(); 418 419 Node* no_base = __ top(); 420 float likely = PROB_LIKELY_MAG(3); 421 float unlikely = PROB_UNLIKELY_MAG(3); 422 Node* young_card = __ ConI((jint)G1CardTable::g1_young_card_val()); 423 Node* dirty_card = __ ConI((jint)G1CardTable::dirty_card_val()); 424 Node* zeroX = __ ConX(0); 425 426 const TypeFunc *tf = write_ref_field_post_entry_Type(); 427 428 // Offsets into the thread 429 const int index_offset = in_bytes(G1ThreadLocalData::dirty_card_queue_index_offset()); 430 const int buffer_offset = in_bytes(G1ThreadLocalData::dirty_card_queue_buffer_offset()); 431 432 // Pointers into the thread 433 434 Node* buffer_adr = __ AddP(no_base, tls, __ ConX(buffer_offset)); 435 Node* index_adr = __ AddP(no_base, tls, __ ConX(index_offset)); 436 437 // Now some values 438 // Use ctrl to avoid hoisting these values past a safepoint, which could 439 // potentially reset these fields in the JavaThread. 440 Node* index = __ load(__ ctrl(), index_adr, TypeX_X, TypeX_X->basic_type(), Compile::AliasIdxRaw); 441 Node* buffer = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw); 442 443 // Convert the store obj pointer to an int prior to doing math on it 444 // Must use ctrl to prevent "integerized oop" existing across safepoint 445 Node* cast = __ CastPX(__ ctrl(), adr); 446 447 // Divide pointer by card size 448 Node* card_offset = __ URShiftX( cast, __ ConI(CardTable::card_shift) ); 449 450 // Combine card table base and card offset 451 Node* card_adr = __ AddP(no_base, byte_map_base_node(kit), card_offset ); 452 453 // If we know the value being stored does it cross regions? 454 455 if (val != NULL) { 456 // Does the store cause us to cross regions? 457 458 // Should be able to do an unsigned compare of region_size instead of 459 // and extra shift. Do we have an unsigned compare?? 460 // Node* region_size = __ ConI(1 << HeapRegion::LogOfHRGrainBytes); 461 Node* xor_res = __ URShiftX ( __ XorX( cast, __ CastPX(__ ctrl(), val)), __ ConI(HeapRegion::LogOfHRGrainBytes)); 462 463 // if (xor_res == 0) same region so skip 464 __ if_then(xor_res, BoolTest::ne, zeroX, likely); { 465 466 // if ((unsigned)(card_offset - low_map_offset) >= (high_map_offset - low_map_offset)) stack allocated object, so skip 467 if (kit->C->do_stack_allocation()) { 468 state()->add_enqueue_barrier(static_cast<CastP2XNode*>(cast)); 469 Node* low_off = kit->longcon(ct->byte_map_bottom_offset()); 470 Node* delta_off = kit->longcon(ct->byte_map_top_offset() - ct->byte_map_bottom_offset()); 471 Node* sub_off = __ SubL(cast, low_off); 472 473 __ uif_then(sub_off, BoolTest::le, delta_off, likely); } { 474 475 // No barrier if we are storing a NULL 476 __ if_then(val, BoolTest::ne, kit->null(), likely); { 477 478 // Ok must mark the card if not already dirty 479 480 // load the original value of the card 481 Node* card_val = __ load(__ ctrl(), card_adr, TypeInt::INT, T_BYTE, Compile::AliasIdxRaw); 482 483 __ if_then(card_val, BoolTest::ne, young_card, unlikely); { 484 kit->sync_kit(ideal); 485 kit->insert_mem_bar(Op_MemBarVolatile, oop_store); 486 __ sync_kit(kit); 487 488 Node* card_val_reload = __ load(__ ctrl(), card_adr, TypeInt::INT, T_BYTE, Compile::AliasIdxRaw); 489 __ if_then(card_val_reload, BoolTest::ne, dirty_card); { 490 g1_mark_card(kit, ideal, card_adr, oop_store, alias_idx, index, index_adr, buffer, tf); 491 } __ end_if(); 492 } __ end_if(); 493 } __ end_if(); 494 } if (kit->C->do_stack_allocation()) { 495 __ end_if(); 496 } 497 } __ end_if(); 498 } else { 499 // The Object.clone() intrinsic uses this path if !ReduceInitialCardMarks. 500 // We don't need a barrier here if the destination is a newly allocated object 501 // in Eden. Otherwise, GC verification breaks because we assume that cards in Eden 502 // are set to 'g1_young_gen' (see G1CardTable::verify_g1_young_region()). 503 assert(!use_ReduceInitialCardMarks(), "can only happen with card marking"); 504 505 // if ((unsigned)(card_offset - low_map_offset) >= (high_map_offset - low_map_offset)) stack allocated object, so skip 506 if (kit->C->do_stack_allocation()) { 507 state()->add_enqueue_barrier(static_cast<CastP2XNode*>(cast)); 508 Node* low_off = kit->longcon(ct->byte_map_bottom_offset()); 509 Node* delta_off = kit->longcon(ct->byte_map_top_offset() - ct->byte_map_bottom_offset()); 510 Node* sub_off = __ SubL(cast, low_off); 511 512 __ uif_then(sub_off, BoolTest::le, delta_off, likely); } { 513 514 Node* card_val = __ load(__ ctrl(), card_adr, TypeInt::INT, T_BYTE, Compile::AliasIdxRaw); 515 __ if_then(card_val, BoolTest::ne, young_card); { 516 g1_mark_card(kit, ideal, card_adr, oop_store, alias_idx, index, index_adr, buffer, tf); 517 } __ end_if(); 518 519 } if (kit->C->do_stack_allocation()) { 520 __ end_if(); 521 } 522 } 523 524 // Final sync IdealKit and GraphKit. 525 kit->final_sync(ideal); 526 } 527 528 // Helper that guards and inserts a pre-barrier. 529 void G1BarrierSetC2::insert_pre_barrier(GraphKit* kit, Node* base_oop, Node* offset, 530 Node* pre_val, bool need_mem_bar) const { 531 // We could be accessing the referent field of a reference object. If so, when G1 532 // is enabled, we need to log the value in the referent field in an SATB buffer. 533 // This routine performs some compile time filters and generates suitable 534 // runtime filters that guard the pre-barrier code. 535 // Also add memory barrier for non volatile load from the referent field 536 // to prevent commoning of loads across safepoint. 537 538 // Some compile time checks. 539 540 // If offset is a constant, is it java_lang_ref_Reference::_reference_offset? 541 const TypeX* otype = offset->find_intptr_t_type(); 542 if (otype != NULL && otype->is_con() && 543 otype->get_con() != java_lang_ref_Reference::referent_offset()) { 544 // Constant offset but not the reference_offset so just return 545 return; 546 } 547 548 // We only need to generate the runtime guards for instances. 549 const TypeOopPtr* btype = base_oop->bottom_type()->isa_oopptr(); 550 if (btype != NULL) { 551 if (btype->isa_aryptr()) { 552 // Array type so nothing to do 553 return; 554 } 555 556 const TypeInstPtr* itype = btype->isa_instptr(); 557 if (itype != NULL) { 558 // Can the klass of base_oop be statically determined to be 559 // _not_ a sub-class of Reference and _not_ Object? 560 ciKlass* klass = itype->klass(); 561 if ( klass->is_loaded() && 562 !klass->is_subtype_of(kit->env()->Reference_klass()) && 563 !kit->env()->Object_klass()->is_subtype_of(klass)) { 564 return; 565 } 566 } 567 } 568 569 // The compile time filters did not reject base_oop/offset so 570 // we need to generate the following runtime filters 571 // 572 // if (offset == java_lang_ref_Reference::_reference_offset) { 573 // if (instance_of(base, java.lang.ref.Reference)) { 574 // pre_barrier(_, pre_val, ...); 575 // } 576 // } 577 578 float likely = PROB_LIKELY( 0.999); 579 float unlikely = PROB_UNLIKELY(0.999); 580 581 IdealKit ideal(kit); 582 583 Node* referent_off = __ ConX(java_lang_ref_Reference::referent_offset()); 584 585 __ if_then(offset, BoolTest::eq, referent_off, unlikely); { 586 // Update graphKit memory and control from IdealKit. 587 kit->sync_kit(ideal); 588 589 Node* ref_klass_con = kit->makecon(TypeKlassPtr::make(kit->env()->Reference_klass())); 590 Node* is_instof = kit->gen_instanceof(base_oop, ref_klass_con); 591 592 // Update IdealKit memory and control from graphKit. 593 __ sync_kit(kit); 594 595 Node* one = __ ConI(1); 596 // is_instof == 0 if base_oop == NULL 597 __ if_then(is_instof, BoolTest::eq, one, unlikely); { 598 599 // Update graphKit from IdeakKit. 600 kit->sync_kit(ideal); 601 602 // Use the pre-barrier to record the value in the referent field 603 pre_barrier(kit, false /* do_load */, 604 __ ctrl(), 605 NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */, 606 pre_val /* pre_val */, 607 T_OBJECT); 608 if (need_mem_bar) { 609 // Add memory barrier to prevent commoning reads from this field 610 // across safepoint since GC can change its value. 611 kit->insert_mem_bar(Op_MemBarCPUOrder); 612 } 613 // Update IdealKit from graphKit. 614 __ sync_kit(kit); 615 616 } __ end_if(); // _ref_type != ref_none 617 } __ end_if(); // offset == referent_offset 618 619 // Final sync IdealKit and GraphKit. 620 kit->final_sync(ideal); 621 } 622 623 #undef __ 624 625 Node* G1BarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const { 626 DecoratorSet decorators = access.decorators(); 627 Node* adr = access.addr().node(); 628 Node* obj = access.base(); 629 630 bool anonymous = (decorators & C2_UNSAFE_ACCESS) != 0; 631 bool mismatched = (decorators & C2_MISMATCHED) != 0; 632 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0; 633 bool in_heap = (decorators & IN_HEAP) != 0; 634 bool in_native = (decorators & IN_NATIVE) != 0; 635 bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0; 636 bool is_unordered = (decorators & MO_UNORDERED) != 0; 637 bool is_mixed = !in_heap && !in_native; 638 bool need_cpu_mem_bar = !is_unordered || mismatched || is_mixed; 639 640 Node* top = Compile::current()->top(); 641 Node* offset = adr->is_AddP() ? adr->in(AddPNode::Offset) : top; 642 Node* load = CardTableBarrierSetC2::load_at_resolved(access, val_type); 643 644 // If we are reading the value of the referent field of a Reference 645 // object (either by using Unsafe directly or through reflection) 646 // then, if G1 is enabled, we need to record the referent in an 647 // SATB log buffer using the pre-barrier mechanism. 648 // Also we need to add memory barrier to prevent commoning reads 649 // from this field across safepoint since GC can change its value. 650 bool need_read_barrier = in_heap && (on_weak || 651 (unknown && offset != top && obj != top)); 652 653 if (!access.is_oop() || !need_read_barrier) { 654 return load; 655 } 656 657 assert(access.is_parse_access(), "entry not supported at optimization time"); 658 C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access); 659 GraphKit* kit = parse_access.kit(); 660 661 if (on_weak) { 662 // Use the pre-barrier to record the value in the referent field 663 pre_barrier(kit, false /* do_load */, 664 kit->control(), 665 NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */, 666 load /* pre_val */, T_OBJECT); 667 // Add memory barrier to prevent commoning reads from this field 668 // across safepoint since GC can change its value. 669 kit->insert_mem_bar(Op_MemBarCPUOrder); 670 } else if (unknown) { 671 // We do not require a mem bar inside pre_barrier if need_mem_bar 672 // is set: the barriers would be emitted by us. 673 insert_pre_barrier(kit, obj, offset, load, !need_cpu_mem_bar); 674 } 675 676 return load; 677 } 678 679 bool G1BarrierSetC2::is_gc_barrier_node(Node* node) const { 680 if (CardTableBarrierSetC2::is_gc_barrier_node(node)) { 681 return true; 682 } 683 if (node->Opcode() != Op_CallLeaf) { 684 return false; 685 } 686 CallLeafNode *call = node->as_CallLeaf(); 687 if (call->_name == NULL) { 688 return false; 689 } 690 691 return strcmp(call->_name, "write_ref_field_pre_entry") == 0 || strcmp(call->_name, "write_ref_field_post_entry") == 0; 692 } 693 694 bool G1BarrierSetC2::process_barrier_node(Node* node, PhaseIterGVN& igvn) const { 695 assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required"); 696 697 // Must have a control node 698 if (node->in(0) == NULL) { 699 return false; 700 } 701 702 // Search for CastP2X->Xor->URShift->Cmp path which 703 // checks if the store done to a different from the value's region. 704 Node* xorx = node->find_out_with(Op_XorX); 705 BoolNode* bool_node = NULL; 706 707 if (xorx != NULL) { 708 709 Node* shift = shift = xorx->unique_out(); 710 Node* cmpx = shift->unique_out(); 711 712 assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() && 713 cmpx->unique_out()->as_Bool()->_test._test == BoolTest::ne, 714 "missing region check in G1 post barrier"); 715 716 Node* bol = cmpx->unique_out(); 717 assert(bol->unique_out()->is_If(), "should find if after the bool node"); 718 Node* if_node = bol->unique_out(); 719 Node* if_true = if_node->find_out_with(Op_IfTrue); 720 assert(if_true != NULL, "there should be false projection"); 721 722 Node* iff_check = if_true->find_out_with(Op_If); 723 // Not a barrier with bound check 724 if (iff_check == NULL) { 725 return false; 726 } 727 728 Node* iff_check_in_1_node = iff_check->in(1); 729 if (!iff_check_in_1_node->is_Bool()) { 730 return false; 731 } 732 bool_node = iff_check_in_1_node->as_Bool(); 733 734 } else { 735 // this "could" be the the path followed when !use_ReduceInitialCardMarks() is 736 // used or when the two sides of the barrier are scalar replaced 737 //assert(false, "we managed to get here!!! process_barrier_node"); 738 Node *addl_node = node->find_out_with(Op_AddL); 739 if (addl_node == NULL) { 740 return false; 741 } 742 743 Node* cmpx = addl_node->unique_out(); 744 assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() && 745 cmpx->unique_out()->as_Bool()->_test._test == BoolTest::le, 746 "missing region check in G1 post barrier"); 747 748 bool_node = cmpx->unique_out()->as_Bool(); 749 } 750 751 if (bool_node->_test._test != BoolTest::le) { 752 return false; 753 } 754 755 // the input to the bool is the CMPX 756 Node* bool_node_in_1_node = bool_node->in(1); 757 if (!bool_node_in_1_node->is_Cmp()) { 758 return false; 759 } 760 CmpNode* cmp_node = bool_node_in_1_node->as_Cmp(); 761 762 // the input to the CMPX is the card_table_top_offset constant 763 Node* cmp_node_in_2_node = cmp_node->in(2); 764 if (!cmp_node_in_2_node->is_Con()) { 765 return false; 766 } 767 768 BarrierSet* bs = BarrierSet::barrier_set(); 769 CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(bs); 770 CardTable* ct = ctbs->card_table(); 771 size_t constant = ct->byte_map_top_offset() - ct->byte_map_bottom_offset(); 772 773 // Check that the input to this CMP node is the expected constant 774 const TypeX* otype = cmp_node_in_2_node->find_intptr_t_type(); 775 if (otype != NULL && otype->is_con() && 776 size_t(otype->get_con()) != constant) { 777 // Constant offset but not the card table size constant so just return 778 return false; 779 } 780 781 // we can't change the compare or the constant so create a new constant(0) and replace the variable 782 Node* cmp_node_in_1_node = cmp_node->in(1); 783 ConNode* zeroConstant_node = igvn.makecon(TypeX_ZERO); 784 if (cmp_node_in_1_node->_idx == zeroConstant_node->_idx) { 785 // we can get here via different nodes - but we only want to change the input once 786 return false; 787 } 788 789 igvn.rehash_node_delayed(cmp_node); 790 int numReplaced = cmp_node->replace_edge(cmp_node_in_1_node, zeroConstant_node); 791 assert(numReplaced == 1, "Failed to replace the card_offset with Conx(0)"); 792 return true; 793 } 794 795 void G1BarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { 796 assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required"); 797 assert(node->outcnt() <= 3, "expects 1, 2 or 3 users: Xor, URShift and SubL nodes"); 798 // It could be only one user, URShift node, in Object.clone() intrinsic 799 // but the new allocation is passed to arraycopy stub and it could not 800 // be scalar replaced. So we don't check the case. 801 802 // Certain loop optimisations may introduce a CastP2X node with 803 // ConvL2I in case of an AllocateArray op. Check for that case 804 // here and do not attempt to eliminate it as write barrier. 805 if (macro->C->do_stack_allocation() && !state()->is_a_barrier(static_cast<CastP2XNode*>(node))) { 806 return; 807 } 808 809 // An other case of only one user (Xor) is when the value check for NULL 810 // in G1 post barrier is folded after CCP so the code which used URShift 811 // is removed. 812 813 // Take Region node before eliminating post barrier since it also 814 // eliminates CastP2X node when it has only one user. 815 Node* this_region = node->in(0); 816 assert(this_region != NULL, ""); 817 818 // Remove G1 post barrier. 819 820 // Search for CastP2X->Xor->URShift->Cmp path which 821 // checks if the store done to a different from the value's region. 822 // And replace Cmp with #0 (false) to collapse G1 post barrier. 823 Node* xorx = node->find_out_with(Op_XorX); 824 if (xorx != NULL) { 825 Node* shift = xorx->unique_out(); 826 Node* cmpx = shift->unique_out(); 827 assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() && 828 cmpx->unique_out()->as_Bool()->_test._test == BoolTest::ne, 829 "missing region check in G1 post barrier"); 830 macro->replace_node(cmpx, macro->makecon(TypeInt::CC_EQ)); 831 832 // Remove G1 pre barrier. 833 834 // Search "if (marking != 0)" check and set it to "false". 835 // There is no G1 pre barrier if previous stored value is NULL 836 // (for example, after initialization). 837 if (this_region->is_Region() && this_region->req() == 3) { 838 int ind = 1; 839 if (!this_region->in(ind)->is_IfFalse()) { 840 ind = 2; 841 } 842 if (this_region->in(ind)->is_IfFalse() && 843 this_region->in(ind)->in(0)->Opcode() == Op_If) { 844 Node* bol = this_region->in(ind)->in(0)->in(1); 845 assert(bol->is_Bool(), ""); 846 cmpx = bol->in(1); 847 if (bol->as_Bool()->_test._test == BoolTest::ne && 848 cmpx->is_Cmp() && cmpx->in(2) == macro->intcon(0) && 849 cmpx->in(1)->is_Load()) { 850 Node* adr = cmpx->in(1)->as_Load()->in(MemNode::Address); 851 const int marking_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()); 852 if (adr->is_AddP() && adr->in(AddPNode::Base) == macro->top() && 853 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 854 adr->in(AddPNode::Offset) == macro->MakeConX(marking_offset)) { 855 macro->replace_node(cmpx, macro->makecon(TypeInt::CC_EQ)); 856 } 857 } 858 } 859 } 860 } else { 861 // In a scenario where the two sides of the barrier are scalar replaced 862 // or stack allocated, the XorX node will be visited more than once, because 863 // both edges will be CastP2X nodes from two distinct allocates. In certain 864 // instances, the removal of the CastP2X node will result in removal of the 865 // XorX node, causing the assert below to be hit when eliminate_gc_barrier is 866 // called for the second node. 867 // assert(!use_ReduceInitialCardMarks(), "can only happen with card marking"); 868 869 // This is a G1 post barrier emitted by the Object.clone() intrinsic. 870 // Search for the CastP2X->URShiftX->AddP->LoadB->Cmp path which checks if the card 871 // is marked as young_gen and replace the Cmp with 0 (false) to collapse the barrier. 872 Node* shift = node->find_out_with(Op_URShiftX); 873 assert(shift != NULL, "missing G1 post barrier"); 874 Node* addp = shift->unique_out(); 875 Node* load = addp->find_out_with(Op_LoadB); 876 assert(load != NULL, "missing G1 post barrier"); 877 Node* cmpx = load->unique_out(); 878 assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() && 879 cmpx->unique_out()->as_Bool()->_test._test == BoolTest::ne, 880 "missing card value check in G1 post barrier"); 881 macro->replace_node(cmpx, macro->makecon(TypeInt::CC_EQ)); 882 // There is no G1 pre barrier in this case 883 } 884 // Now CastP2X can be removed since it is used only on dead path 885 // which currently still alive until igvn optimize it. 886 // TODO: fix this following assert becuase of SUBL 887 // assert(node->outcnt() == 0 || node->unique_out()->Opcode() == Op_URShiftX, ""); 888 macro->replace_node(node, macro->top()); 889 890 // Remove this node from our state 891 state()->remove_enqueue_barrier(static_cast<CastP2XNode*>(node)); 892 } 893 894 Node* G1BarrierSetC2::step_over_gc_barrier(Node* c) const { 895 if (!use_ReduceInitialCardMarks() && 896 c != NULL && c->is_Region() && c->req() == 3) { 897 for (uint i = 1; i < c->req(); i++) { 898 if (c->in(i) != NULL && c->in(i)->is_Region() && 899 c->in(i)->req() == 3) { 900 Node* r = c->in(i); 901 for (uint j = 1; j < r->req(); j++) { 902 if (r->in(j) != NULL && r->in(j)->is_Proj() && 903 r->in(j)->in(0) != NULL && 904 r->in(j)->in(0)->Opcode() == Op_CallLeaf && 905 r->in(j)->in(0)->as_Call()->entry_point() == CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_post_entry)) { 906 Node* call = r->in(j)->in(0); 907 c = c->in(i == 1 ? 2 : 1); 908 if (c != NULL) { 909 c = c->in(0); 910 if (c != NULL) { 911 c = c->in(0); 912 assert(call->in(0) == NULL || 913 call->in(0)->in(0) == NULL || 914 call->in(0)->in(0)->in(0) == NULL || 915 call->in(0)->in(0)->in(0)->in(0) == NULL || 916 call->in(0)->in(0)->in(0)->in(0)->in(0) == NULL || 917 c == call->in(0)->in(0)->in(0)->in(0)->in(0), "bad barrier shape"); 918 return c; 919 } 920 } 921 } 922 } 923 } 924 } 925 } 926 return c; 927 } 928 929 #ifdef ASSERT 930 void G1BarrierSetC2::verify_gc_barriers(Compile* compile, CompilePhase phase) const { 931 if (phase != BarrierSetC2::BeforeCodeGen) { 932 return; 933 } 934 // Verify G1 pre-barriers 935 const int marking_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()); 936 937 ResourceArea *area = Thread::current()->resource_area(); 938 Unique_Node_List visited(area); 939 Node_List worklist(area); 940 // We're going to walk control flow backwards starting from the Root 941 worklist.push(compile->root()); 942 while (worklist.size() > 0) { 943 Node* x = worklist.pop(); 944 if (x == NULL || x == compile->top()) continue; 945 if (visited.member(x)) { 946 continue; 947 } else { 948 visited.push(x); 949 } 950 951 if (x->is_Region()) { 952 for (uint i = 1; i < x->req(); i++) { 953 worklist.push(x->in(i)); 954 } 955 } else { 956 worklist.push(x->in(0)); 957 // We are looking for the pattern: 958 // /->ThreadLocal 959 // If->Bool->CmpI->LoadB->AddP->ConL(marking_offset) 960 // \->ConI(0) 961 // We want to verify that the If and the LoadB have the same control 962 // See GraphKit::g1_write_barrier_pre() 963 if (x->is_If()) { 964 IfNode *iff = x->as_If(); 965 if (iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp()) { 966 CmpNode *cmp = iff->in(1)->in(1)->as_Cmp(); 967 if (cmp->Opcode() == Op_CmpI && cmp->in(2)->is_Con() && cmp->in(2)->bottom_type()->is_int()->get_con() == 0 968 && cmp->in(1)->is_Load()) { 969 LoadNode* load = cmp->in(1)->as_Load(); 970 if (load->Opcode() == Op_LoadB && load->in(2)->is_AddP() && load->in(2)->in(2)->Opcode() == Op_ThreadLocal 971 && load->in(2)->in(3)->is_Con() 972 && load->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == marking_offset) { 973 974 Node* if_ctrl = iff->in(0); 975 Node* load_ctrl = load->in(0); 976 977 if (if_ctrl != load_ctrl) { 978 // Skip possible CProj->NeverBranch in infinite loops 979 if ((if_ctrl->is_Proj() && if_ctrl->Opcode() == Op_CProj) 980 && (if_ctrl->in(0)->is_MultiBranch() && if_ctrl->in(0)->Opcode() == Op_NeverBranch)) { 981 if_ctrl = if_ctrl->in(0)->in(0); 982 } 983 } 984 assert(load_ctrl != NULL && if_ctrl == load_ctrl, "controls must match"); 985 } 986 } 987 } 988 } 989 } 990 } 991 } 992 #endif 993 994 bool G1BarrierSetC2::escape_add_to_con_graph(ConnectionGraph* conn_graph, PhaseGVN* gvn, Unique_Node_List* delayed_worklist, Node* n, uint opcode) const { 995 if (opcode == Op_StoreP) { 996 Node* adr = n->in(MemNode::Address); 997 const Type* adr_type = gvn->type(adr); 998 // Pointer stores in G1 barriers looks like unsafe access. 999 // Ignore such stores to be able scalar replace non-escaping 1000 // allocations. 1001 if (adr_type->isa_rawptr() && adr->is_AddP()) { 1002 Node* base = conn_graph->get_addp_base(adr); 1003 if (base->Opcode() == Op_LoadP && 1004 base->in(MemNode::Address)->is_AddP()) { 1005 adr = base->in(MemNode::Address); 1006 Node* tls = conn_graph->get_addp_base(adr); 1007 if (tls->Opcode() == Op_ThreadLocal) { 1008 int offs = (int) gvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot); 1009 const int buf_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_buffer_offset()); 1010 if (offs == buf_offset) { 1011 return true; // G1 pre barrier previous oop value store. 1012 } 1013 if (offs == in_bytes(G1ThreadLocalData::dirty_card_queue_buffer_offset())) { 1014 return true; // G1 post barrier card address store. 1015 } 1016 } 1017 } 1018 } 1019 } 1020 return false; 1021 }