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 "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. This is similar to 302 * how CMS is required to handle this case, see the comments for the method 303 * CollectedHeap::new_deferred_store_barrier and OptoRuntime::new_deferred_store_barrier. 304 * A deferred card mark is required for these objects and handled in the above 305 * mentioned methods. 306 * 307 * Returns true if the post barrier can be removed 308 */ 309 bool G1BarrierSetC2::g1_can_remove_post_barrier(GraphKit* kit, 310 PhaseTransform* phase, Node* store, 311 Node* adr) const { 312 intptr_t offset = 0; 313 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 314 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 315 316 if (offset == Type::OffsetBot) { 317 return false; // cannot unalias unless there are precise offsets 318 } 319 320 if (alloc == NULL) { 321 return false; // No allocation found 322 } 323 324 // Start search from Store node 325 Node* mem = store->in(MemNode::Control); 326 if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 327 328 InitializeNode* st_init = mem->in(0)->as_Initialize(); 329 AllocateNode* st_alloc = st_init->allocation(); 330 331 // Make sure we are looking at the same allocation 332 if (alloc == st_alloc) { 333 return true; 334 } 335 } 336 337 return false; 338 } 339 340 // 341 // Update the card table and add card address to the queue 342 // 343 void G1BarrierSetC2::g1_mark_card(GraphKit* kit, 344 IdealKit& ideal, 345 Node* card_adr, 346 Node* oop_store, 347 uint oop_alias_idx, 348 Node* index, 349 Node* index_adr, 350 Node* buffer, 351 const TypeFunc* tf) const { 352 Node* zero = __ ConI(0); 353 Node* zeroX = __ ConX(0); 354 Node* no_base = __ top(); 355 BasicType card_bt = T_BYTE; 356 // Smash zero into card. MUST BE ORDERED WRT TO STORE 357 __ storeCM(__ ctrl(), card_adr, zero, oop_store, oop_alias_idx, card_bt, Compile::AliasIdxRaw); 358 359 // Now do the queue work 360 __ if_then(index, BoolTest::ne, zeroX); { 361 362 Node* next_index = kit->gvn().transform(new SubXNode(index, __ ConX(sizeof(intptr_t)))); 363 Node* log_addr = __ AddP(no_base, buffer, next_index); 364 365 // Order, see storeCM. 366 __ store(__ ctrl(), log_addr, card_adr, T_ADDRESS, Compile::AliasIdxRaw, MemNode::unordered); 367 __ store(__ ctrl(), index_adr, next_index, TypeX_X->basic_type(), Compile::AliasIdxRaw, MemNode::unordered); 368 369 } __ else_(); { 370 __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_post_entry), "write_ref_field_post_entry", card_adr, __ thread()); 371 } __ end_if(); 372 373 } 374 375 void G1BarrierSetC2::post_barrier(GraphKit* kit, 376 Node* ctl, 377 Node* oop_store, 378 Node* obj, 379 Node* adr, 380 uint alias_idx, 381 Node* val, 382 BasicType bt, 383 bool use_precise) const { 384 // If we are writing a NULL then we need no post barrier 385 386 if (val != NULL && val->is_Con() && val->bottom_type() == TypePtr::NULL_PTR) { 387 // Must be NULL 388 const Type* t = val->bottom_type(); 389 assert(t == Type::TOP || t == TypePtr::NULL_PTR, "must be NULL"); 390 // No post barrier if writing NULLx 391 return; 392 } 393 394 if (use_ReduceInitialCardMarks() && obj == kit->just_allocated_object(kit->control())) { 395 // We can skip marks on a freshly-allocated object in Eden. 396 // Keep this code in sync with new_deferred_store_barrier() in runtime.cpp. 397 // That routine informs GC to take appropriate compensating steps, 398 // upon a slow-path allocation, so as to make this card-mark 399 // elision safe. 400 return; 401 } 402 403 if (use_ReduceInitialCardMarks() 404 && g1_can_remove_post_barrier(kit, &kit->gvn(), oop_store, adr)) { 405 return; 406 } 407 408 if (!use_precise) { 409 // All card marks for a (non-array) instance are in one place: 410 adr = obj; 411 } 412 // (Else it's an array (or unknown), and we want more precise card marks.) 413 assert(adr != NULL, ""); 414 415 IdealKit ideal(kit, true); 416 417 Node* tls = __ thread(); // ThreadLocalStorage 418 419 Node* no_base = __ top(); 420 float unlikely = PROB_UNLIKELY(0.999); 421 Node* young_card = __ ConI((jint)G1CardTable::g1_young_card_val()); 422 Node* dirty_card = __ ConI((jint)G1CardTable::dirty_card_val()); 423 Node* zeroX = __ ConX(0); 424 425 const TypeFunc *tf = write_ref_field_post_entry_Type(); 426 427 // Offsets into the thread 428 const int index_offset = in_bytes(G1ThreadLocalData::dirty_card_queue_index_offset()); 429 const int buffer_offset = in_bytes(G1ThreadLocalData::dirty_card_queue_buffer_offset()); 430 431 // Pointers into the thread 432 433 Node* buffer_adr = __ AddP(no_base, tls, __ ConX(buffer_offset)); 434 Node* index_adr = __ AddP(no_base, tls, __ ConX(index_offset)); 435 436 // Now some values 437 // Use ctrl to avoid hoisting these values past a safepoint, which could 438 // potentially reset these fields in the JavaThread. 439 Node* index = __ load(__ ctrl(), index_adr, TypeX_X, TypeX_X->basic_type(), Compile::AliasIdxRaw); 440 Node* buffer = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw); 441 442 // Convert the store obj pointer to an int prior to doing math on it 443 // Must use ctrl to prevent "integerized oop" existing across safepoint 444 Node* cast = __ CastPX(__ ctrl(), adr); 445 446 // Divide pointer by card size 447 Node* card_offset = __ URShiftX( cast, __ ConI(CardTable::card_shift) ); 448 449 // Combine card table base and card offset 450 Node* card_adr = __ AddP(no_base, byte_map_base_node(kit), card_offset ); 451 452 // If we know the value being stored does it cross regions? 453 454 if (val != NULL) { 455 // Does the store cause us to cross regions? 456 457 // Should be able to do an unsigned compare of region_size instead of 458 // and extra shift. Do we have an unsigned compare?? 459 // Node* region_size = __ ConI(1 << HeapRegion::LogOfHRGrainBytes); 460 Node* xor_res = __ URShiftX ( __ XorX( cast, __ CastPX(__ ctrl(), val)), __ ConI(HeapRegion::LogOfHRGrainBytes)); 461 462 // if (xor_res == 0) same region so skip 463 __ if_then(xor_res, BoolTest::ne, zeroX); { 464 465 // No barrier if we are storing a NULL 466 __ if_then(val, BoolTest::ne, kit->null(), unlikely); { 467 468 // Ok must mark the card if not already dirty 469 470 // load the original value of the card 471 Node* card_val = __ load(__ ctrl(), card_adr, TypeInt::INT, T_BYTE, Compile::AliasIdxRaw); 472 473 __ if_then(card_val, BoolTest::ne, young_card); { 474 kit->sync_kit(ideal); 475 kit->insert_store_load_for_barrier(); 476 __ sync_kit(kit); 477 478 Node* card_val_reload = __ load(__ ctrl(), card_adr, TypeInt::INT, T_BYTE, Compile::AliasIdxRaw); 479 __ if_then(card_val_reload, BoolTest::ne, dirty_card); { 480 g1_mark_card(kit, ideal, card_adr, oop_store, alias_idx, index, index_adr, buffer, tf); 481 } __ end_if(); 482 } __ end_if(); 483 } __ end_if(); 484 } __ end_if(); 485 } else { 486 // The Object.clone() intrinsic uses this path if !ReduceInitialCardMarks. 487 // We don't need a barrier here if the destination is a newly allocated object 488 // in Eden. Otherwise, GC verification breaks because we assume that cards in Eden 489 // are set to 'g1_young_gen' (see G1CardTable::verify_g1_young_region()). 490 assert(!use_ReduceInitialCardMarks(), "can only happen with card marking"); 491 Node* card_val = __ load(__ ctrl(), card_adr, TypeInt::INT, T_BYTE, Compile::AliasIdxRaw); 492 __ if_then(card_val, BoolTest::ne, young_card); { 493 g1_mark_card(kit, ideal, card_adr, oop_store, alias_idx, index, index_adr, buffer, tf); 494 } __ end_if(); 495 } 496 497 // Final sync IdealKit and GraphKit. 498 kit->final_sync(ideal); 499 } 500 501 // Helper that guards and inserts a pre-barrier. 502 void G1BarrierSetC2::insert_pre_barrier(GraphKit* kit, Node* base_oop, Node* offset, 503 Node* pre_val, bool need_mem_bar) const { 504 // We could be accessing the referent field of a reference object. If so, when G1 505 // is enabled, we need to log the value in the referent field in an SATB buffer. 506 // This routine performs some compile time filters and generates suitable 507 // runtime filters that guard the pre-barrier code. 508 // Also add memory barrier for non volatile load from the referent field 509 // to prevent commoning of loads across safepoint. 510 511 // Some compile time checks. 512 513 // If offset is a constant, is it java_lang_ref_Reference::_reference_offset? 514 const TypeX* otype = offset->find_intptr_t_type(); 515 if (otype != NULL && otype->is_con() && 516 otype->get_con() != java_lang_ref_Reference::referent_offset) { 517 // Constant offset but not the reference_offset so just return 518 return; 519 } 520 521 // We only need to generate the runtime guards for instances. 522 const TypeOopPtr* btype = base_oop->bottom_type()->isa_oopptr(); 523 if (btype != NULL) { 524 if (btype->isa_aryptr()) { 525 // Array type so nothing to do 526 return; 527 } 528 529 const TypeInstPtr* itype = btype->isa_instptr(); 530 if (itype != NULL) { 531 // Can the klass of base_oop be statically determined to be 532 // _not_ a sub-class of Reference and _not_ Object? 533 ciKlass* klass = itype->klass(); 534 if ( klass->is_loaded() && 535 !klass->is_subtype_of(kit->env()->Reference_klass()) && 536 !kit->env()->Object_klass()->is_subtype_of(klass)) { 537 return; 538 } 539 } 540 } 541 542 // The compile time filters did not reject base_oop/offset so 543 // we need to generate the following runtime filters 544 // 545 // if (offset == java_lang_ref_Reference::_reference_offset) { 546 // if (instance_of(base, java.lang.ref.Reference)) { 547 // pre_barrier(_, pre_val, ...); 548 // } 549 // } 550 551 float likely = PROB_LIKELY( 0.999); 552 float unlikely = PROB_UNLIKELY(0.999); 553 554 IdealKit ideal(kit); 555 556 Node* referent_off = __ ConX(java_lang_ref_Reference::referent_offset); 557 558 __ if_then(offset, BoolTest::eq, referent_off, unlikely); { 559 // Update graphKit memory and control from IdealKit. 560 kit->sync_kit(ideal); 561 562 Node* ref_klass_con = kit->makecon(TypeKlassPtr::make(kit->env()->Reference_klass())); 563 Node* is_instof = kit->gen_instanceof(base_oop, ref_klass_con); 564 565 // Update IdealKit memory and control from graphKit. 566 __ sync_kit(kit); 567 568 Node* one = __ ConI(1); 569 // is_instof == 0 if base_oop == NULL 570 __ if_then(is_instof, BoolTest::eq, one, unlikely); { 571 572 // Update graphKit from IdeakKit. 573 kit->sync_kit(ideal); 574 575 // Use the pre-barrier to record the value in the referent field 576 pre_barrier(kit, false /* do_load */, 577 __ ctrl(), 578 NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */, 579 pre_val /* pre_val */, 580 T_OBJECT); 581 if (need_mem_bar) { 582 // Add memory barrier to prevent commoning reads from this field 583 // across safepoint since GC can change its value. 584 kit->insert_mem_bar(Op_MemBarCPUOrder); 585 } 586 // Update IdealKit from graphKit. 587 __ sync_kit(kit); 588 589 } __ end_if(); // _ref_type != ref_none 590 } __ end_if(); // offset == referent_offset 591 592 // Final sync IdealKit and GraphKit. 593 kit->final_sync(ideal); 594 } 595 596 #undef __ 597 598 Node* G1BarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const { 599 DecoratorSet decorators = access.decorators(); 600 Node* adr = access.addr().node(); 601 Node* obj = access.base(); 602 603 bool mismatched = (decorators & C2_MISMATCHED) != 0; 604 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0; 605 bool in_heap = (decorators & IN_HEAP) != 0; 606 bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0; 607 bool is_unordered = (decorators & MO_UNORDERED) != 0; 608 bool need_cpu_mem_bar = !is_unordered || mismatched || !in_heap; 609 610 Node* top = Compile::current()->top(); 611 Node* offset = adr->is_AddP() ? adr->in(AddPNode::Offset) : top; 612 Node* load = CardTableBarrierSetC2::load_at_resolved(access, val_type); 613 614 // If we are reading the value of the referent field of a Reference 615 // object (either by using Unsafe directly or through reflection) 616 // then, if G1 is enabled, we need to record the referent in an 617 // SATB log buffer using the pre-barrier mechanism. 618 // Also we need to add memory barrier to prevent commoning reads 619 // from this field across safepoint since GC can change its value. 620 bool need_read_barrier = in_heap && (on_weak || 621 (unknown && offset != top && obj != top)); 622 623 if (!access.is_oop() || !need_read_barrier) { 624 return load; 625 } 626 627 assert(access.is_parse_access(), "entry not supported at optimization time"); 628 C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access); 629 GraphKit* kit = parse_access.kit(); 630 631 if (on_weak) { 632 // Use the pre-barrier to record the value in the referent field 633 pre_barrier(kit, false /* do_load */, 634 kit->control(), 635 NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */, 636 load /* pre_val */, T_OBJECT); 637 // Add memory barrier to prevent commoning reads from this field 638 // across safepoint since GC can change its value. 639 kit->insert_mem_bar(Op_MemBarCPUOrder); 640 } else if (unknown) { 641 // We do not require a mem bar inside pre_barrier if need_mem_bar 642 // is set: the barriers would be emitted by us. 643 insert_pre_barrier(kit, obj, offset, load, !need_cpu_mem_bar); 644 } 645 646 return load; 647 } 648 649 bool G1BarrierSetC2::is_gc_barrier_node(Node* node) const { 650 if (CardTableBarrierSetC2::is_gc_barrier_node(node)) { 651 return true; 652 } 653 if (node->Opcode() != Op_CallLeaf) { 654 return false; 655 } 656 CallLeafNode *call = node->as_CallLeaf(); 657 if (call->_name == NULL) { 658 return false; 659 } 660 661 return strcmp(call->_name, "write_ref_field_pre_entry") == 0 || strcmp(call->_name, "write_ref_field_post_entry") == 0; 662 } 663 664 void G1BarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { 665 assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required"); 666 assert(node->outcnt() <= 2, "expects 1 or 2 users: Xor and URShift nodes"); 667 // It could be only one user, URShift node, in Object.clone() intrinsic 668 // but the new allocation is passed to arraycopy stub and it could not 669 // be scalar replaced. So we don't check the case. 670 671 // An other case of only one user (Xor) is when the value check for NULL 672 // in G1 post barrier is folded after CCP so the code which used URShift 673 // is removed. 674 675 // Take Region node before eliminating post barrier since it also 676 // eliminates CastP2X node when it has only one user. 677 Node* this_region = node->in(0); 678 assert(this_region != NULL, ""); 679 680 // Remove G1 post barrier. 681 682 // Search for CastP2X->Xor->URShift->Cmp path which 683 // checks if the store done to a different from the value's region. 684 // And replace Cmp with #0 (false) to collapse G1 post barrier. 685 Node* xorx = node->find_out_with(Op_XorX); 686 if (xorx != NULL) { 687 Node* shift = xorx->unique_out(); 688 Node* cmpx = shift->unique_out(); 689 assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() && 690 cmpx->unique_out()->as_Bool()->_test._test == BoolTest::ne, 691 "missing region check in G1 post barrier"); 692 macro->replace_node(cmpx, macro->makecon(TypeInt::CC_EQ)); 693 694 // Remove G1 pre barrier. 695 696 // Search "if (marking != 0)" check and set it to "false". 697 // There is no G1 pre barrier if previous stored value is NULL 698 // (for example, after initialization). 699 if (this_region->is_Region() && this_region->req() == 3) { 700 int ind = 1; 701 if (!this_region->in(ind)->is_IfFalse()) { 702 ind = 2; 703 } 704 if (this_region->in(ind)->is_IfFalse() && 705 this_region->in(ind)->in(0)->Opcode() == Op_If) { 706 Node* bol = this_region->in(ind)->in(0)->in(1); 707 assert(bol->is_Bool(), ""); 708 cmpx = bol->in(1); 709 if (bol->as_Bool()->_test._test == BoolTest::ne && 710 cmpx->is_Cmp() && cmpx->in(2) == macro->intcon(0) && 711 cmpx->in(1)->is_Load()) { 712 Node* adr = cmpx->in(1)->as_Load()->in(MemNode::Address); 713 const int marking_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()); 714 if (adr->is_AddP() && adr->in(AddPNode::Base) == macro->top() && 715 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 716 adr->in(AddPNode::Offset) == macro->MakeConX(marking_offset)) { 717 macro->replace_node(cmpx, macro->makecon(TypeInt::CC_EQ)); 718 } 719 } 720 } 721 } 722 } else { 723 assert(!use_ReduceInitialCardMarks(), "can only happen with card marking"); 724 // This is a G1 post barrier emitted by the Object.clone() intrinsic. 725 // Search for the CastP2X->URShiftX->AddP->LoadB->Cmp path which checks if the card 726 // is marked as young_gen and replace the Cmp with 0 (false) to collapse the barrier. 727 Node* shift = node->find_out_with(Op_URShiftX); 728 assert(shift != NULL, "missing G1 post barrier"); 729 Node* addp = shift->unique_out(); 730 Node* load = addp->find_out_with(Op_LoadB); 731 assert(load != NULL, "missing G1 post barrier"); 732 Node* cmpx = load->unique_out(); 733 assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() && 734 cmpx->unique_out()->as_Bool()->_test._test == BoolTest::ne, 735 "missing card value check in G1 post barrier"); 736 macro->replace_node(cmpx, macro->makecon(TypeInt::CC_EQ)); 737 // There is no G1 pre barrier in this case 738 } 739 // Now CastP2X can be removed since it is used only on dead path 740 // which currently still alive until igvn optimize it. 741 assert(node->outcnt() == 0 || node->unique_out()->Opcode() == Op_URShiftX, ""); 742 macro->replace_node(node, macro->top()); 743 } 744 745 Node* G1BarrierSetC2::step_over_gc_barrier(Node* c) const { 746 if (!use_ReduceInitialCardMarks() && 747 c != NULL && c->is_Region() && c->req() == 3) { 748 for (uint i = 1; i < c->req(); i++) { 749 if (c->in(i) != NULL && c->in(i)->is_Region() && 750 c->in(i)->req() == 3) { 751 Node* r = c->in(i); 752 for (uint j = 1; j < r->req(); j++) { 753 if (r->in(j) != NULL && r->in(j)->is_Proj() && 754 r->in(j)->in(0) != NULL && 755 r->in(j)->in(0)->Opcode() == Op_CallLeaf && 756 r->in(j)->in(0)->as_Call()->entry_point() == CAST_FROM_FN_PTR(address, G1BarrierSetRuntime::write_ref_field_post_entry)) { 757 Node* call = r->in(j)->in(0); 758 c = c->in(i == 1 ? 2 : 1); 759 if (c != NULL) { 760 c = c->in(0); 761 if (c != NULL) { 762 c = c->in(0); 763 assert(call->in(0) == NULL || 764 call->in(0)->in(0) == NULL || 765 call->in(0)->in(0)->in(0) == NULL || 766 call->in(0)->in(0)->in(0)->in(0) == NULL || 767 call->in(0)->in(0)->in(0)->in(0)->in(0) == NULL || 768 c == call->in(0)->in(0)->in(0)->in(0)->in(0), "bad barrier shape"); 769 return c; 770 } 771 } 772 } 773 } 774 } 775 } 776 } 777 return c; 778 } 779 780 #ifdef ASSERT 781 void G1BarrierSetC2::verify_gc_barriers(Compile* compile, CompilePhase phase) const { 782 if (phase != BarrierSetC2::BeforeCodeGen) { 783 return; 784 } 785 // Verify G1 pre-barriers 786 const int marking_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_active_offset()); 787 788 ResourceArea *area = Thread::current()->resource_area(); 789 Unique_Node_List visited(area); 790 Node_List worklist(area); 791 // We're going to walk control flow backwards starting from the Root 792 worklist.push(compile->root()); 793 while (worklist.size() > 0) { 794 Node* x = worklist.pop(); 795 if (x == NULL || x == compile->top()) continue; 796 if (visited.member(x)) { 797 continue; 798 } else { 799 visited.push(x); 800 } 801 802 if (x->is_Region()) { 803 for (uint i = 1; i < x->req(); i++) { 804 worklist.push(x->in(i)); 805 } 806 } else { 807 worklist.push(x->in(0)); 808 // We are looking for the pattern: 809 // /->ThreadLocal 810 // If->Bool->CmpI->LoadB->AddP->ConL(marking_offset) 811 // \->ConI(0) 812 // We want to verify that the If and the LoadB have the same control 813 // See GraphKit::g1_write_barrier_pre() 814 if (x->is_If()) { 815 IfNode *iff = x->as_If(); 816 if (iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp()) { 817 CmpNode *cmp = iff->in(1)->in(1)->as_Cmp(); 818 if (cmp->Opcode() == Op_CmpI && cmp->in(2)->is_Con() && cmp->in(2)->bottom_type()->is_int()->get_con() == 0 819 && cmp->in(1)->is_Load()) { 820 LoadNode* load = cmp->in(1)->as_Load(); 821 if (load->Opcode() == Op_LoadB && load->in(2)->is_AddP() && load->in(2)->in(2)->Opcode() == Op_ThreadLocal 822 && load->in(2)->in(3)->is_Con() 823 && load->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == marking_offset) { 824 825 Node* if_ctrl = iff->in(0); 826 Node* load_ctrl = load->in(0); 827 828 if (if_ctrl != load_ctrl) { 829 // Skip possible CProj->NeverBranch in infinite loops 830 if ((if_ctrl->is_Proj() && if_ctrl->Opcode() == Op_CProj) 831 && (if_ctrl->in(0)->is_MultiBranch() && if_ctrl->in(0)->Opcode() == Op_NeverBranch)) { 832 if_ctrl = if_ctrl->in(0)->in(0); 833 } 834 } 835 assert(load_ctrl != NULL && if_ctrl == load_ctrl, "controls must match"); 836 } 837 } 838 } 839 } 840 } 841 } 842 } 843 #endif 844 845 bool G1BarrierSetC2::escape_add_to_con_graph(ConnectionGraph* conn_graph, PhaseGVN* gvn, Unique_Node_List* delayed_worklist, Node* n, uint opcode) const { 846 if (opcode == Op_StoreP) { 847 Node* adr = n->in(MemNode::Address); 848 const Type* adr_type = gvn->type(adr); 849 // Pointer stores in G1 barriers looks like unsafe access. 850 // Ignore such stores to be able scalar replace non-escaping 851 // allocations. 852 if (adr_type->isa_rawptr() && adr->is_AddP()) { 853 Node* base = conn_graph->get_addp_base(adr); 854 if (base->Opcode() == Op_LoadP && 855 base->in(MemNode::Address)->is_AddP()) { 856 adr = base->in(MemNode::Address); 857 Node* tls = conn_graph->get_addp_base(adr); 858 if (tls->Opcode() == Op_ThreadLocal) { 859 int offs = (int) gvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot); 860 const int buf_offset = in_bytes(G1ThreadLocalData::satb_mark_queue_buffer_offset()); 861 if (offs == buf_offset) { 862 return true; // G1 pre barrier previous oop value store. 863 } 864 if (offs == in_bytes(G1ThreadLocalData::dirty_card_queue_buffer_offset())) { 865 return true; // G1 post barrier card address store. 866 } 867 } 868 } 869 } 870 } 871 return false; 872 }