1 /* 2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #include "ci/ciFlatArrayKlass.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/systemDictionary.hpp" 29 #include "compiler/compileLog.hpp" 30 #include "gc/shared/barrierSet.hpp" 31 #include "gc/shared/c2/barrierSetC2.hpp" 32 #include "gc/shared/tlab_globals.hpp" 33 #include "memory/allocation.inline.hpp" 34 #include "memory/resourceArea.hpp" 35 #include "oops/flatArrayKlass.hpp" 36 #include "oops/objArrayKlass.hpp" 37 #include "opto/addnode.hpp" 38 #include "opto/arraycopynode.hpp" 39 #include "opto/cfgnode.hpp" 40 #include "opto/compile.hpp" 41 #include "opto/connode.hpp" 42 #include "opto/convertnode.hpp" 43 #include "opto/inlinetypenode.hpp" 44 #include "opto/loopnode.hpp" 45 #include "opto/machnode.hpp" 46 #include "opto/matcher.hpp" 47 #include "opto/memnode.hpp" 48 #include "opto/mempointer.hpp" 49 #include "opto/mulnode.hpp" 50 #include "opto/narrowptrnode.hpp" 51 #include "opto/phaseX.hpp" 52 #include "opto/regalloc.hpp" 53 #include "opto/regmask.hpp" 54 #include "opto/rootnode.hpp" 55 #include "opto/traceMergeStoresTag.hpp" 56 #include "opto/vectornode.hpp" 57 #include "utilities/align.hpp" 58 #include "utilities/copy.hpp" 59 #include "utilities/macros.hpp" 60 #include "utilities/powerOfTwo.hpp" 61 #include "utilities/vmError.hpp" 62 63 // Portions of code courtesy of Clifford Click 64 65 // Optimization - Graph Style 66 67 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 68 69 //============================================================================= 70 uint MemNode::size_of() const { return sizeof(*this); } 71 72 const TypePtr *MemNode::adr_type() const { 73 Node* adr = in(Address); 74 if (adr == nullptr) return nullptr; // node is dead 75 const TypePtr* cross_check = nullptr; 76 DEBUG_ONLY(cross_check = _adr_type); 77 return calculate_adr_type(adr->bottom_type(), cross_check); 78 } 79 80 bool MemNode::check_if_adr_maybe_raw(Node* adr) { 81 if (adr != nullptr) { 82 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) { 83 return true; 84 } 85 } 86 return false; 87 } 88 89 #ifndef PRODUCT 90 void MemNode::dump_spec(outputStream *st) const { 91 if (in(Address) == nullptr) return; // node is dead 92 #ifndef ASSERT 93 // fake the missing field 94 const TypePtr* _adr_type = nullptr; 95 if (in(Address) != nullptr) 96 _adr_type = in(Address)->bottom_type()->isa_ptr(); 97 #endif 98 dump_adr_type(this, _adr_type, st); 99 100 Compile* C = Compile::current(); 101 if (C->alias_type(_adr_type)->is_volatile()) { 102 st->print(" Volatile!"); 103 } 104 if (_unaligned_access) { 105 st->print(" unaligned"); 106 } 107 if (_mismatched_access) { 108 st->print(" mismatched"); 109 } 110 if (_unsafe_access) { 111 st->print(" unsafe"); 112 } 113 } 114 115 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 116 st->print(" @"); 117 if (adr_type == nullptr) { 118 st->print("null"); 119 } else { 120 adr_type->dump_on(st); 121 Compile* C = Compile::current(); 122 Compile::AliasType* atp = nullptr; 123 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 124 if (atp == nullptr) 125 st->print(", idx=?\?;"); 126 else if (atp->index() == Compile::AliasIdxBot) 127 st->print(", idx=Bot;"); 128 else if (atp->index() == Compile::AliasIdxTop) 129 st->print(", idx=Top;"); 130 else if (atp->index() == Compile::AliasIdxRaw) 131 st->print(", idx=Raw;"); 132 else { 133 ciField* field = atp->field(); 134 if (field) { 135 st->print(", name="); 136 field->print_name_on(st); 137 } 138 st->print(", idx=%d;", atp->index()); 139 } 140 } 141 } 142 143 extern void print_alias_types(); 144 145 #endif 146 147 // Find the memory output corresponding to the fall-through path of a call 148 static Node* find_call_fallthrough_mem_output(CallNode* call) { 149 ResourceMark rm; 150 CallProjections* projs = call->extract_projections(false, false); 151 Node* res = projs->fallthrough_memproj; 152 assert(res != nullptr, "must have a fallthrough mem output"); 153 return res; 154 } 155 156 // Try to find a better memory input for a load from a strict final field 157 static Node* try_optimize_strict_final_load_memory(PhaseGVN* phase, Node* adr, ProjNode*& base_local) { 158 intptr_t offset = 0; 159 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 160 if (base == nullptr) { 161 return nullptr; 162 } 163 164 Node* base_uncasted = base->uncast(); 165 if (base_uncasted->is_Proj()) { 166 MultiNode* multi = base_uncasted->in(0)->as_Multi(); 167 if (multi->is_Allocate()) { 168 base_local = base_uncasted->as_Proj(); 169 return nullptr; 170 } else if (multi->is_Call()) { 171 // The oop is returned from a call, the memory can be the fallthrough output of the call 172 return find_call_fallthrough_mem_output(multi->as_Call()); 173 } else if (multi->is_Start()) { 174 // The oop is a parameter 175 if (phase->C->method()->is_object_constructor() && base_uncasted->as_Proj()->_con == TypeFunc::Parms) { 176 // The receiver of a constructor is similar to the result of an AllocateNode 177 base_local = base_uncasted->as_Proj(); 178 return nullptr; 179 } else { 180 // Use the start memory otherwise 181 return multi->proj_out(TypeFunc::Memory); 182 } 183 } 184 } 185 186 return nullptr; 187 } 188 189 // Whether a call can modify a strict final field, given that the object is allocated inside the 190 // current compilation unit, or is the first parameter when the compilation root is a constructor. 191 // This is equivalent to asking whether 'call' is a constructor invocation and the class declaring 192 // the target method is a subclass of the class declaring 'field'. 193 static bool call_can_modify_local_object(ciField* field, CallNode* call) { 194 if (!call->is_CallJava()) { 195 return false; 196 } 197 198 ciMethod* target = call->as_CallJava()->method(); 199 if (target == nullptr || !target->is_object_constructor()) { 200 return false; 201 } 202 203 // If 'field' is declared in a class that is a subclass of the one declaring the constructor, 204 // then the field is set inside the constructor, else the field must be set before the 205 // constructor invocation. E.g. A field Super.x will be set during the execution of Sub::<init>, 206 // while a field Sub.y must be set before Super::<init> is invoked. 207 // We can try to be more heroic and decide if the receiver of the constructor invocation is the 208 // object from which we are loading from. This, however, may be problematic as deciding if 2 209 // nodes are definitely different may not be trivial, especially if the graph is not canonical. 210 // As a result, it is made more conservative for now. 211 assert(call->req() > TypeFunc::Parms, "constructor must have at least 1 argument"); 212 return target->holder()->is_subclass_of(field->holder()); 213 } 214 215 Node* MemNode::optimize_simple_memory_chain(Node* mchain, const TypeOopPtr* t_oop, Node* load, PhaseGVN* phase) { 216 assert(t_oop != nullptr, "sanity"); 217 bool is_instance = t_oop->is_known_instance_field(); 218 219 ciField* field = phase->C->alias_type(t_oop)->field(); 220 bool is_strict_final_load = false; 221 222 // After macro expansion, an allocation may become a call, changing the memory input to the 223 // memory output of that call would be illegal. As a result, disallow this transformation after 224 // macro expansion. 225 if (phase->is_IterGVN() && phase->C->allow_macro_nodes() && load != nullptr && load->is_Load() && !load->as_Load()->is_mismatched_access()) { 226 if (EnableValhalla) { 227 if (field != nullptr && (field->holder()->is_inlinetype() || field->holder()->is_abstract_value_klass())) { 228 is_strict_final_load = true; 229 } 230 #ifdef ASSERT 231 if (t_oop->is_inlinetypeptr() && t_oop->inline_klass()->contains_field_offset(t_oop->offset())) { 232 assert(is_strict_final_load, "sanity check for basic cases"); 233 } 234 #endif 235 } else { 236 is_strict_final_load = field != nullptr && t_oop->is_ptr_to_boxed_value(); 237 } 238 } 239 240 if (!is_instance && !is_strict_final_load) { 241 return mchain; 242 } 243 244 Node* result = mchain; 245 ProjNode* base_local = nullptr; 246 247 if (is_strict_final_load) { 248 Node* adr = load->in(MemNode::Address); 249 assert(phase->type(adr) == t_oop, "inconsistent type"); 250 Node* tmp = try_optimize_strict_final_load_memory(phase, adr, base_local); 251 if (tmp != nullptr) { 252 result = tmp; 253 } 254 } 255 256 uint instance_id = t_oop->instance_id(); 257 Node* start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory); 258 Node* prev = nullptr; 259 while (prev != result) { 260 prev = result; 261 if (result == start_mem) { 262 // start_mem is the earliest memory possible 263 break; 264 } 265 266 // skip over a call which does not affect this memory slice 267 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 268 Node* proj_in = result->in(0); 269 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 270 // This is the allocation that creates the object from which we are loading from 271 break; 272 } else if (proj_in->is_Call()) { 273 // ArrayCopyNodes processed here as well 274 CallNode* call = proj_in->as_Call(); 275 if (!call->may_modify(t_oop, phase)) { 276 result = call->in(TypeFunc::Memory); 277 } else if (is_strict_final_load && base_local != nullptr && !call_can_modify_local_object(field, call)) { 278 result = call->in(TypeFunc::Memory); 279 } 280 } else if (proj_in->is_Initialize()) { 281 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 282 // Stop if this is the initialization for the object instance which 283 // contains this memory slice, otherwise skip over it. 284 if ((alloc == nullptr) || (alloc->_idx == instance_id)) { 285 break; 286 } 287 if (is_instance) { 288 result = proj_in->in(TypeFunc::Memory); 289 } else if (is_strict_final_load) { 290 Node* klass = alloc->in(AllocateNode::KlassNode); 291 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 292 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) { 293 // Allocation of another type, must be another object 294 result = proj_in->in(TypeFunc::Memory); 295 } else if (base_local != nullptr && (base_local->is_Parm() || base_local->in(0) != alloc)) { 296 // Allocation of another object 297 result = proj_in->in(TypeFunc::Memory); 298 } 299 } 300 } else if (proj_in->is_MemBar()) { 301 ArrayCopyNode* ac = nullptr; 302 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) { 303 break; 304 } 305 result = proj_in->in(TypeFunc::Memory); 306 } else if (proj_in->is_top()) { 307 break; // dead code 308 } else { 309 assert(false, "unexpected projection"); 310 } 311 } else if (result->is_ClearArray()) { 312 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) { 313 // Can not bypass initialization of the instance 314 // we are looking for. 315 break; 316 } 317 // Otherwise skip it (the call updated 'result' value). 318 } else if (result->is_MergeMem()) { 319 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty); 320 } 321 } 322 return result; 323 } 324 325 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 326 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 327 if (t_oop == nullptr) 328 return mchain; // don't try to optimize non-oop types 329 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 330 bool is_instance = t_oop->is_known_instance_field(); 331 PhaseIterGVN *igvn = phase->is_IterGVN(); 332 if (is_instance && igvn != nullptr && result->is_Phi()) { 333 PhiNode *mphi = result->as_Phi(); 334 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 335 const TypePtr *t = mphi->adr_type(); 336 bool do_split = false; 337 // In the following cases, Load memory input can be further optimized based on 338 // its precise address type 339 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) { 340 do_split = true; 341 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) { 342 const TypeOopPtr* mem_t = 343 t->is_oopptr()->cast_to_exactness(true) 344 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 345 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()); 346 if (t_oop->isa_aryptr()) { 347 mem_t = mem_t->is_aryptr() 348 ->cast_to_stable(t_oop->is_aryptr()->is_stable()) 349 ->cast_to_size(t_oop->is_aryptr()->size()) 350 ->cast_to_not_flat(t_oop->is_aryptr()->is_not_flat()) 351 ->cast_to_not_null_free(t_oop->is_aryptr()->is_not_null_free()) 352 ->with_offset(t_oop->is_aryptr()->offset()) 353 ->is_aryptr(); 354 } 355 do_split = mem_t == t_oop; 356 } 357 if (do_split) { 358 // clone the Phi with our address type 359 result = mphi->split_out_instance(t_adr, igvn); 360 } else { 361 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 362 } 363 } 364 return result; 365 } 366 367 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 368 uint alias_idx = phase->C->get_alias_index(tp); 369 Node *mem = mmem; 370 #ifdef ASSERT 371 { 372 // Check that current type is consistent with the alias index used during graph construction 373 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 374 bool consistent = adr_check == nullptr || adr_check->empty() || 375 phase->C->must_alias(adr_check, alias_idx ); 376 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 377 if( !consistent && adr_check != nullptr && !adr_check->empty() && 378 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 379 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 380 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 381 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 382 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 383 // don't assert if it is dead code. 384 consistent = true; 385 } 386 if( !consistent ) { 387 st->print("alias_idx==%d, adr_check==", alias_idx); 388 if( adr_check == nullptr ) { 389 st->print("null"); 390 } else { 391 adr_check->dump(); 392 } 393 st->cr(); 394 print_alias_types(); 395 assert(consistent, "adr_check must match alias idx"); 396 } 397 } 398 #endif 399 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 400 // means an array I have not precisely typed yet. Do not do any 401 // alias stuff with it any time soon. 402 const TypeOopPtr *toop = tp->isa_oopptr(); 403 if (tp->base() != Type::AnyPtr && 404 !(toop && 405 toop->isa_instptr() && 406 toop->is_instptr()->instance_klass()->is_java_lang_Object() && 407 toop->offset() == Type::OffsetBot)) { 408 // IGVN _delay_transform may be set to true and if that is the case and mmem 409 // is already a registered node then the validation inside transform will 410 // complain. 411 Node* m = mmem; 412 PhaseIterGVN* igvn = phase->is_IterGVN(); 413 if (igvn == nullptr || !igvn->delay_transform()) { 414 // compress paths and change unreachable cycles to TOP 415 // If not, we can update the input infinitely along a MergeMem cycle 416 // Equivalent code in PhiNode::Ideal 417 m = phase->transform(mmem); 418 } 419 // If transformed to a MergeMem, get the desired slice 420 // Otherwise the returned node represents memory for every slice 421 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 422 // Update input if it is progress over what we have now 423 } 424 return mem; 425 } 426 427 //--------------------------Ideal_common--------------------------------------- 428 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. 429 // Unhook non-raw memories from complete (macro-expanded) initializations. 430 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 431 // If our control input is a dead region, kill all below the region 432 Node *ctl = in(MemNode::Control); 433 if (ctl && remove_dead_region(phase, can_reshape)) 434 return this; 435 ctl = in(MemNode::Control); 436 // Don't bother trying to transform a dead node 437 if (ctl && ctl->is_top()) return NodeSentinel; 438 439 PhaseIterGVN *igvn = phase->is_IterGVN(); 440 // Wait if control on the worklist. 441 if (ctl && can_reshape && igvn != nullptr) { 442 Node* bol = nullptr; 443 Node* cmp = nullptr; 444 if (ctl->in(0)->is_If()) { 445 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 446 bol = ctl->in(0)->in(1); 447 if (bol->is_Bool()) 448 cmp = ctl->in(0)->in(1)->in(1); 449 } 450 if (igvn->_worklist.member(ctl) || 451 (bol != nullptr && igvn->_worklist.member(bol)) || 452 (cmp != nullptr && igvn->_worklist.member(cmp)) ) { 453 // This control path may be dead. 454 // Delay this memory node transformation until the control is processed. 455 igvn->_worklist.push(this); 456 return NodeSentinel; // caller will return null 457 } 458 } 459 // Ignore if memory is dead, or self-loop 460 Node *mem = in(MemNode::Memory); 461 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null 462 assert(mem != this, "dead loop in MemNode::Ideal"); 463 464 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) { 465 // This memory slice may be dead. 466 // Delay this mem node transformation until the memory is processed. 467 igvn->_worklist.push(this); 468 return NodeSentinel; // caller will return null 469 } 470 471 Node *address = in(MemNode::Address); 472 const Type *t_adr = phase->type(address); 473 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null 474 475 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) { 476 // Unsafe off-heap access with zero address. Remove access and other control users 477 // to not confuse optimizations and add a HaltNode to fail if this is ever executed. 478 assert(ctl != nullptr, "unsafe accesses should be control dependent"); 479 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) { 480 Node* u = ctl->fast_out(i); 481 if (u != ctl) { 482 igvn->rehash_node_delayed(u); 483 int nb = u->replace_edge(ctl, phase->C->top(), igvn); 484 --i, imax -= nb; 485 } 486 } 487 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr)); 488 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address")); 489 phase->C->root()->add_req(halt); 490 return this; 491 } 492 493 if (can_reshape && igvn != nullptr && 494 (igvn->_worklist.member(address) || 495 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) { 496 // The address's base and type may change when the address is processed. 497 // Delay this mem node transformation until the address is processed. 498 igvn->_worklist.push(this); 499 return NodeSentinel; // caller will return null 500 } 501 502 // Do NOT remove or optimize the next lines: ensure a new alias index 503 // is allocated for an oop pointer type before Escape Analysis. 504 // Note: C++ will not remove it since the call has side effect. 505 if (t_adr->isa_oopptr()) { 506 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 507 } 508 509 Node* base = nullptr; 510 if (address->is_AddP()) { 511 base = address->in(AddPNode::Base); 512 } 513 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 514 !t_adr->isa_rawptr()) { 515 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 516 // Skip this node optimization if its address has TOP base. 517 return NodeSentinel; // caller will return null 518 } 519 520 // Avoid independent memory operations 521 Node* old_mem = mem; 522 523 // The code which unhooks non-raw memories from complete (macro-expanded) 524 // initializations was removed. After macro-expansion all stores caught 525 // by Initialize node became raw stores and there is no information 526 // which memory slices they modify. So it is unsafe to move any memory 527 // operation above these stores. Also in most cases hooked non-raw memories 528 // were already unhooked by using information from detect_ptr_independence() 529 // and find_previous_store(). 530 531 if (mem->is_MergeMem()) { 532 MergeMemNode* mmem = mem->as_MergeMem(); 533 const TypePtr *tp = t_adr->is_ptr(); 534 535 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 536 } 537 538 if (mem != old_mem) { 539 set_req_X(MemNode::Memory, mem, phase); 540 if (phase->type(mem) == Type::TOP) return NodeSentinel; 541 return this; 542 } 543 544 // let the subclass continue analyzing... 545 return nullptr; 546 } 547 548 // Helper function for proving some simple control dominations. 549 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 550 // Already assumes that 'dom' is available at 'sub', and that 'sub' 551 // is not a constant (dominated by the method's StartNode). 552 // Used by MemNode::find_previous_store to prove that the 553 // control input of a memory operation predates (dominates) 554 // an allocation it wants to look past. 555 // Returns 'DomResult::Dominate' if all control inputs of 'dom' 556 // dominate 'sub', 'DomResult::NotDominate' if not, 557 // and 'DomResult::EncounteredDeadCode' if we can't decide due to 558 // dead code, but at the end of IGVN, we know the definite result 559 // once the dead code is cleaned up. 560 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) { 561 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) { 562 return DomResult::EncounteredDeadCode; // Conservative answer for dead code 563 } 564 565 // Check 'dom'. Skip Proj and CatchProj nodes. 566 dom = dom->find_exact_control(dom); 567 if (dom == nullptr || dom->is_top()) { 568 return DomResult::EncounteredDeadCode; // Conservative answer for dead code 569 } 570 571 if (dom == sub) { 572 // For the case when, for example, 'sub' is Initialize and the original 573 // 'dom' is Proj node of the 'sub'. 574 return DomResult::NotDominate; 575 } 576 577 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) { 578 return DomResult::Dominate; 579 } 580 581 // 'dom' dominates 'sub' if its control edge and control edges 582 // of all its inputs dominate or equal to sub's control edge. 583 584 // Currently 'sub' is either Allocate, Initialize or Start nodes. 585 // Or Region for the check in LoadNode::Ideal(); 586 // 'sub' should have sub->in(0) != nullptr. 587 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 588 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 589 590 // Get control edge of 'sub'. 591 Node* orig_sub = sub; 592 sub = sub->find_exact_control(sub->in(0)); 593 if (sub == nullptr || sub->is_top()) { 594 return DomResult::EncounteredDeadCode; // Conservative answer for dead code 595 } 596 597 assert(sub->is_CFG(), "expecting control"); 598 599 if (sub == dom) { 600 return DomResult::Dominate; 601 } 602 603 if (sub->is_Start() || sub->is_Root()) { 604 return DomResult::NotDominate; 605 } 606 607 { 608 // Check all control edges of 'dom'. 609 610 ResourceMark rm; 611 Node_List nlist; 612 Unique_Node_List dom_list; 613 614 dom_list.push(dom); 615 bool only_dominating_controls = false; 616 617 for (uint next = 0; next < dom_list.size(); next++) { 618 Node* n = dom_list.at(next); 619 if (n == orig_sub) { 620 return DomResult::NotDominate; // One of dom's inputs dominated by sub. 621 } 622 if (!n->is_CFG() && n->pinned()) { 623 // Check only own control edge for pinned non-control nodes. 624 n = n->find_exact_control(n->in(0)); 625 if (n == nullptr || n->is_top()) { 626 return DomResult::EncounteredDeadCode; // Conservative answer for dead code 627 } 628 assert(n->is_CFG(), "expecting control"); 629 dom_list.push(n); 630 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 631 only_dominating_controls = true; 632 } else if (n->is_CFG()) { 633 DomResult dom_result = n->dominates(sub, nlist); 634 if (dom_result == DomResult::Dominate) { 635 only_dominating_controls = true; 636 } else { 637 return dom_result; 638 } 639 } else { 640 // First, own control edge. 641 Node* m = n->find_exact_control(n->in(0)); 642 if (m != nullptr) { 643 if (m->is_top()) { 644 return DomResult::EncounteredDeadCode; // Conservative answer for dead code 645 } 646 dom_list.push(m); 647 } 648 // Now, the rest of edges. 649 uint cnt = n->req(); 650 for (uint i = 1; i < cnt; i++) { 651 m = n->find_exact_control(n->in(i)); 652 if (m == nullptr || m->is_top()) { 653 continue; 654 } 655 dom_list.push(m); 656 } 657 } 658 } 659 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate; 660 } 661 } 662 663 //---------------------detect_ptr_independence--------------------------------- 664 // Used by MemNode::find_previous_store to prove that two base 665 // pointers are never equal. 666 // The pointers are accompanied by their associated allocations, 667 // if any, which have been previously discovered by the caller. 668 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 669 Node* p2, AllocateNode* a2, 670 PhaseTransform* phase) { 671 // Attempt to prove that these two pointers cannot be aliased. 672 // They may both manifestly be allocations, and they should differ. 673 // Or, if they are not both allocations, they can be distinct constants. 674 // Otherwise, one is an allocation and the other a pre-existing value. 675 if (a1 == nullptr && a2 == nullptr) { // neither an allocation 676 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 677 } else if (a1 != nullptr && a2 != nullptr) { // both allocations 678 return (a1 != a2); 679 } else if (a1 != nullptr) { // one allocation a1 680 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 681 return all_controls_dominate(p2, a1); 682 } else { //(a2 != null) // one allocation a2 683 return all_controls_dominate(p1, a2); 684 } 685 return false; 686 } 687 688 689 // Find an arraycopy ac that produces the memory state represented by parameter mem. 690 // Return ac if 691 // (a) can_see_stored_value=true and ac must have set the value for this load or if 692 // (b) can_see_stored_value=false and ac could have set the value for this load or if 693 // (c) can_see_stored_value=false and ac cannot have set the value for this load. 694 // In case (c) change the parameter mem to the memory input of ac to skip it 695 // when searching stored value. 696 // Otherwise return null. 697 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 698 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem); 699 if (ac != nullptr) { 700 Node* ld_addp = in(MemNode::Address); 701 Node* src = ac->in(ArrayCopyNode::Src); 702 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr(); 703 704 // This is a load from a cloned array. The corresponding arraycopy ac must 705 // have set the value for the load and we can return ac but only if the load 706 // is known to be within bounds. This is checked below. 707 if (ary_t != nullptr && ld_addp->is_AddP()) { 708 Node* ld_offs = ld_addp->in(AddPNode::Offset); 709 BasicType ary_elem = ary_t->elem()->array_element_basic_type(); 710 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem); 711 jlong elemsize = type2aelembytes(ary_elem); 712 713 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 714 const TypeInt* sizetype = ary_t->size(); 715 716 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) { 717 // The load is known to be within bounds. It receives its value from ac. 718 return ac; 719 } 720 // The load is known to be out-of-bounds. 721 } 722 // The load could be out-of-bounds. It must not be hoisted but must remain 723 // dependent on the runtime range check. This is achieved by returning null. 724 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) { 725 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy(); 726 727 if (ac->is_arraycopy_validated() || 728 ac->is_copyof_validated() || 729 ac->is_copyofrange_validated()) { 730 Node* ld_addp = in(MemNode::Address); 731 if (ld_addp->is_AddP()) { 732 Node* ld_base = ld_addp->in(AddPNode::Address); 733 Node* ld_offs = ld_addp->in(AddPNode::Offset); 734 735 Node* dest = ac->in(ArrayCopyNode::Dest); 736 737 if (dest == ld_base) { 738 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 739 assert(!ld_offs_t->empty(), "dead reference should be checked already"); 740 // Take into account vector or unsafe access size 741 jlong ld_size_in_bytes = (jlong)memory_size(); 742 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1; 743 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM 744 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) { 745 return ac; 746 } 747 if (!can_see_stored_value) { 748 mem = ac->in(TypeFunc::Memory); 749 return ac; 750 } 751 } 752 } 753 } 754 } 755 return nullptr; 756 } 757 758 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const { 759 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 760 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 761 if (ld_alloc != nullptr) { 762 // Check if there is an array copy for a clone 763 Node* mb = mem->in(0); 764 ArrayCopyNode* ac = nullptr; 765 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() && 766 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) { 767 ac = mb->in(0)->in(0)->as_ArrayCopy(); 768 } else { 769 // Step over GC barrier when ReduceInitialCardMarks is disabled 770 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 771 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0)); 772 773 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) { 774 ac = control_proj_ac->in(0)->as_ArrayCopy(); 775 } 776 } 777 778 if (ac != nullptr && ac->is_clonebasic()) { 779 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest)); 780 if (alloc != nullptr && alloc == ld_alloc) { 781 return ac; 782 } 783 } 784 } 785 } 786 return nullptr; 787 } 788 789 // The logic for reordering loads and stores uses four steps: 790 // (a) Walk carefully past stores and initializations which we 791 // can prove are independent of this load. 792 // (b) Observe that the next memory state makes an exact match 793 // with self (load or store), and locate the relevant store. 794 // (c) Ensure that, if we were to wire self directly to the store, 795 // the optimizer would fold it up somehow. 796 // (d) Do the rewiring, and return, depending on some other part of 797 // the optimizer to fold up the load. 798 // This routine handles steps (a) and (b). Steps (c) and (d) are 799 // specific to loads and stores, so they are handled by the callers. 800 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 801 // 802 Node* MemNode::find_previous_store(PhaseValues* phase) { 803 Node* ctrl = in(MemNode::Control); 804 Node* adr = in(MemNode::Address); 805 intptr_t offset = 0; 806 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 807 AllocateNode* alloc = AllocateNode::Ideal_allocation(base); 808 809 if (offset == Type::OffsetBot) 810 return nullptr; // cannot unalias unless there are precise offsets 811 812 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr); 813 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 814 815 intptr_t size_in_bytes = memory_size(); 816 817 Node* mem = in(MemNode::Memory); // start searching here... 818 819 int cnt = 50; // Cycle limiter 820 for (;;) { // While we can dance past unrelated stores... 821 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 822 823 Node* prev = mem; 824 if (mem->is_Store()) { 825 Node* st_adr = mem->in(MemNode::Address); 826 intptr_t st_offset = 0; 827 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 828 if (st_base == nullptr) 829 break; // inscrutable pointer 830 831 // For raw accesses it's not enough to prove that constant offsets don't intersect. 832 // We need the bases to be the equal in order for the offset check to make sense. 833 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) { 834 break; 835 } 836 837 if (st_offset != offset && st_offset != Type::OffsetBot) { 838 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize); 839 assert(mem->as_Store()->memory_size() <= MAX_STORE, ""); 840 if (st_offset >= offset + size_in_bytes || 841 st_offset <= offset - MAX_STORE || 842 st_offset <= offset - mem->as_Store()->memory_size()) { 843 // Success: The offsets are provably independent. 844 // (You may ask, why not just test st_offset != offset and be done? 845 // The answer is that stores of different sizes can co-exist 846 // in the same sequence of RawMem effects. We sometimes initialize 847 // a whole 'tile' of array elements with a single jint or jlong.) 848 mem = mem->in(MemNode::Memory); 849 continue; // (a) advance through independent store memory 850 } 851 } 852 if (st_base != base && 853 detect_ptr_independence(base, alloc, 854 st_base, 855 AllocateNode::Ideal_allocation(st_base), 856 phase)) { 857 // Success: The bases are provably independent. 858 mem = mem->in(MemNode::Memory); 859 continue; // (a) advance through independent store memory 860 } 861 862 // (b) At this point, if the bases or offsets do not agree, we lose, 863 // since we have not managed to prove 'this' and 'mem' independent. 864 if (st_base == base && st_offset == offset) { 865 return mem; // let caller handle steps (c), (d) 866 } 867 868 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 869 InitializeNode* st_init = mem->in(0)->as_Initialize(); 870 AllocateNode* st_alloc = st_init->allocation(); 871 if (st_alloc == nullptr) { 872 break; // something degenerated 873 } 874 bool known_identical = false; 875 bool known_independent = false; 876 if (alloc == st_alloc) { 877 known_identical = true; 878 } else if (alloc != nullptr) { 879 known_independent = true; 880 } else if (all_controls_dominate(this, st_alloc)) { 881 known_independent = true; 882 } 883 884 if (known_independent) { 885 // The bases are provably independent: Either they are 886 // manifestly distinct allocations, or else the control 887 // of this load dominates the store's allocation. 888 int alias_idx = phase->C->get_alias_index(adr_type()); 889 if (alias_idx == Compile::AliasIdxRaw) { 890 mem = st_alloc->in(TypeFunc::Memory); 891 } else { 892 mem = st_init->memory(alias_idx); 893 } 894 continue; // (a) advance through independent store memory 895 } 896 897 // (b) at this point, if we are not looking at a store initializing 898 // the same allocation we are loading from, we lose. 899 if (known_identical) { 900 // From caller, can_see_stored_value will consult find_captured_store. 901 return mem; // let caller handle steps (c), (d) 902 } 903 904 } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) { 905 if (prev != mem) { 906 // Found an arraycopy but it doesn't affect that load 907 continue; 908 } 909 // Found an arraycopy that may affect that load 910 return mem; 911 } else if (addr_t != nullptr && addr_t->is_known_instance_field()) { 912 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 913 if (mem->is_Proj() && mem->in(0)->is_Call()) { 914 // ArrayCopyNodes processed here as well. 915 CallNode *call = mem->in(0)->as_Call(); 916 if (!call->may_modify(addr_t, phase)) { 917 mem = call->in(TypeFunc::Memory); 918 continue; // (a) advance through independent call memory 919 } 920 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 921 ArrayCopyNode* ac = nullptr; 922 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) { 923 break; 924 } 925 mem = mem->in(0)->in(TypeFunc::Memory); 926 continue; // (a) advance through independent MemBar memory 927 } else if (mem->is_ClearArray()) { 928 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 929 // (the call updated 'mem' value) 930 continue; // (a) advance through independent allocation memory 931 } else { 932 // Can not bypass initialization of the instance 933 // we are looking for. 934 return mem; 935 } 936 } else if (mem->is_MergeMem()) { 937 int alias_idx = phase->C->get_alias_index(adr_type()); 938 mem = mem->as_MergeMem()->memory_at(alias_idx); 939 continue; // (a) advance through independent MergeMem memory 940 } 941 } 942 943 // Unless there is an explicit 'continue', we must bail out here, 944 // because 'mem' is an inscrutable memory state (e.g., a call). 945 break; 946 } 947 948 return nullptr; // bail out 949 } 950 951 //----------------------calculate_adr_type------------------------------------- 952 // Helper function. Notices when the given type of address hits top or bottom. 953 // Also, asserts a cross-check of the type against the expected address type. 954 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 955 if (t == Type::TOP) return nullptr; // does not touch memory any more? 956 #ifdef ASSERT 957 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr; 958 #endif 959 const TypePtr* tp = t->isa_ptr(); 960 if (tp == nullptr) { 961 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 962 return TypePtr::BOTTOM; // touches lots of memory 963 } else { 964 #ifdef ASSERT 965 // %%%% [phh] We don't check the alias index if cross_check is 966 // TypeRawPtr::BOTTOM. Needs to be investigated. 967 if (cross_check != nullptr && 968 cross_check != TypePtr::BOTTOM && 969 cross_check != TypeRawPtr::BOTTOM) { 970 // Recheck the alias index, to see if it has changed (due to a bug). 971 Compile* C = Compile::current(); 972 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 973 "must stay in the original alias category"); 974 // The type of the address must be contained in the adr_type, 975 // disregarding "null"-ness. 976 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 977 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 978 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 979 "real address must not escape from expected memory type"); 980 } 981 #endif 982 return tp; 983 } 984 } 985 986 uint8_t MemNode::barrier_data(const Node* n) { 987 if (n->is_LoadStore()) { 988 return n->as_LoadStore()->barrier_data(); 989 } else if (n->is_Mem()) { 990 return n->as_Mem()->barrier_data(); 991 } 992 return 0; 993 } 994 995 //============================================================================= 996 // Should LoadNode::Ideal() attempt to remove control edges? 997 bool LoadNode::can_remove_control() const { 998 return !has_pinned_control_dependency(); 999 } 1000 uint LoadNode::size_of() const { return sizeof(*this); } 1001 bool LoadNode::cmp(const Node &n) const { 1002 LoadNode& load = (LoadNode &)n; 1003 return Type::equals(_type, load._type) && 1004 _control_dependency == load._control_dependency && 1005 _mo == load._mo; 1006 } 1007 const Type *LoadNode::bottom_type() const { return _type; } 1008 uint LoadNode::ideal_reg() const { 1009 return _type->ideal_reg(); 1010 } 1011 1012 #ifndef PRODUCT 1013 void LoadNode::dump_spec(outputStream *st) const { 1014 MemNode::dump_spec(st); 1015 if( !Verbose && !WizardMode ) { 1016 // standard dump does this in Verbose and WizardMode 1017 st->print(" #"); _type->dump_on(st); 1018 } 1019 if (!depends_only_on_test()) { 1020 st->print(" (does not depend only on test, "); 1021 if (control_dependency() == UnknownControl) { 1022 st->print("unknown control"); 1023 } else if (control_dependency() == Pinned) { 1024 st->print("pinned"); 1025 } else if (adr_type() == TypeRawPtr::BOTTOM) { 1026 st->print("raw access"); 1027 } else { 1028 st->print("unknown reason"); 1029 } 1030 st->print(")"); 1031 } 1032 } 1033 #endif 1034 1035 #ifdef ASSERT 1036 //----------------------------is_immutable_value------------------------------- 1037 // Helper function to allow a raw load without control edge for some cases 1038 bool LoadNode::is_immutable_value(Node* adr) { 1039 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 1040 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) { 1041 1042 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1); 1043 int offsets[] = { 1044 in_bytes(JavaThread::osthread_offset()), 1045 in_bytes(JavaThread::threadObj_offset()), 1046 in_bytes(JavaThread::vthread_offset()), 1047 in_bytes(JavaThread::scopedValueCache_offset()), 1048 }; 1049 1050 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) { 1051 if (offset == offsets[i]) { 1052 return true; 1053 } 1054 } 1055 } 1056 1057 return false; 1058 } 1059 #endif 1060 1061 //----------------------------LoadNode::make----------------------------------- 1062 // Polymorphic factory method: 1063 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo, 1064 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) { 1065 Compile* C = gvn.C; 1066 1067 // sanity check the alias category against the created node type 1068 assert(!(adr_type->isa_oopptr() && 1069 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 1070 "use LoadKlassNode instead"); 1071 assert(!(adr_type->isa_aryptr() && 1072 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 1073 "use LoadRangeNode instead"); 1074 // Check control edge of raw loads 1075 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 1076 // oop will be recorded in oop map if load crosses safepoint 1077 rt->isa_oopptr() || is_immutable_value(adr), 1078 "raw memory operations should have control edge"); 1079 LoadNode* load = nullptr; 1080 switch (bt) { 1081 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 1082 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 1083 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 1084 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 1085 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 1086 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break; 1087 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 1088 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break; 1089 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break; 1090 case T_OBJECT: 1091 case T_NARROWOOP: 1092 #ifdef _LP64 1093 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1094 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency); 1095 } else 1096 #endif 1097 { 1098 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 1099 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 1100 } 1101 break; 1102 default: 1103 ShouldNotReachHere(); 1104 break; 1105 } 1106 assert(load != nullptr, "LoadNode should have been created"); 1107 if (unaligned) { 1108 load->set_unaligned_access(); 1109 } 1110 if (mismatched) { 1111 load->set_mismatched_access(); 1112 } 1113 if (unsafe) { 1114 load->set_unsafe_access(); 1115 } 1116 load->set_barrier_data(barrier_data); 1117 if (load->Opcode() == Op_LoadN) { 1118 Node* ld = gvn.transform(load); 1119 return new DecodeNNode(ld, ld->bottom_type()->make_ptr()); 1120 } 1121 1122 return load; 1123 } 1124 1125 //------------------------------hash------------------------------------------- 1126 uint LoadNode::hash() const { 1127 // unroll addition of interesting fields 1128 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 1129 } 1130 1131 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 1132 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) { 1133 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile(); 1134 bool is_stable_ary = FoldStableValues && 1135 (tp != nullptr) && (tp->isa_aryptr() != nullptr) && 1136 tp->isa_aryptr()->is_stable(); 1137 1138 return (eliminate_boxing && non_volatile) || is_stable_ary || tp->is_inlinetypeptr(); 1139 } 1140 1141 return false; 1142 } 1143 1144 LoadNode* LoadNode::pin_array_access_node() const { 1145 const TypePtr* adr_type = this->adr_type(); 1146 if (adr_type != nullptr && adr_type->isa_aryptr()) { 1147 return clone_pinned(); 1148 } 1149 return nullptr; 1150 } 1151 1152 // Is the value loaded previously stored by an arraycopy? If so return 1153 // a load node that reads from the source array so we may be able to 1154 // optimize out the ArrayCopy node later. 1155 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const { 1156 Node* ld_adr = in(MemNode::Address); 1157 intptr_t ld_off = 0; 1158 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 1159 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 1160 if (ac != nullptr) { 1161 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 1162 1163 Node* mem = ac->in(TypeFunc::Memory); 1164 Node* ctl = ac->in(0); 1165 Node* src = ac->in(ArrayCopyNode::Src); 1166 1167 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) { 1168 return nullptr; 1169 } 1170 1171 // load depends on the tests that validate the arraycopy 1172 LoadNode* ld = clone_pinned(); 1173 Node* addp = in(MemNode::Address)->clone(); 1174 if (ac->as_ArrayCopy()->is_clonebasic()) { 1175 assert(ld_alloc != nullptr, "need an alloc"); 1176 assert(addp->is_AddP(), "address must be addp"); 1177 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 1178 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern"); 1179 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern"); 1180 addp->set_req(AddPNode::Base, src); 1181 addp->set_req(AddPNode::Address, src); 1182 } else { 1183 assert(ac->as_ArrayCopy()->is_arraycopy_validated() || 1184 ac->as_ArrayCopy()->is_copyof_validated() || 1185 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases"); 1186 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 1187 addp->set_req(AddPNode::Base, src); 1188 addp->set_req(AddPNode::Address, src); 1189 1190 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 1191 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type(); 1192 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT; 1193 1194 uint shift = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem)); 1195 1196 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 1197 #ifdef _LP64 1198 diff = phase->transform(new ConvI2LNode(diff)); 1199 #endif 1200 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 1201 1202 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 1203 addp->set_req(AddPNode::Offset, offset); 1204 } 1205 addp = phase->transform(addp); 1206 #ifdef ASSERT 1207 const TypePtr* adr_type = phase->type(addp)->is_ptr(); 1208 ld->_adr_type = adr_type; 1209 #endif 1210 ld->set_req(MemNode::Address, addp); 1211 ld->set_req(0, ctl); 1212 ld->set_req(MemNode::Memory, mem); 1213 return ld; 1214 } 1215 return nullptr; 1216 } 1217 1218 static Node* see_through_inline_type(PhaseValues* phase, const MemNode* load, Node* base, int offset) { 1219 if (!load->is_mismatched_access() && base != nullptr && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) { 1220 InlineTypeNode* vt = base->as_InlineType(); 1221 Node* value = vt->field_value_by_offset(offset, true); 1222 assert(value != nullptr, "must see some value"); 1223 return value; 1224 } 1225 1226 return nullptr; 1227 } 1228 1229 //---------------------------can_see_stored_value------------------------------ 1230 // This routine exists to make sure this set of tests is done the same 1231 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 1232 // will change the graph shape in a way which makes memory alive twice at the 1233 // same time (uses the Oracle model of aliasing), then some 1234 // LoadXNode::Identity will fold things back to the equivalence-class model 1235 // of aliasing. 1236 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const { 1237 Node* ld_adr = in(MemNode::Address); 1238 intptr_t ld_off = 0; 1239 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off); 1240 // Try to see through an InlineTypeNode 1241 // LoadN is special because the input is not compressed 1242 if (Opcode() != Op_LoadN) { 1243 Node* value = see_through_inline_type(phase, this, ld_base, ld_off); 1244 if (value != nullptr) { 1245 return value; 1246 } 1247 } 1248 1249 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base); 1250 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 1251 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr; 1252 // This is more general than load from boxing objects. 1253 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 1254 uint alias_idx = atp->index(); 1255 Node* result = nullptr; 1256 Node* current = st; 1257 // Skip through chains of MemBarNodes checking the MergeMems for 1258 // new states for the slice of this load. Stop once any other 1259 // kind of node is encountered. Loads from final memory can skip 1260 // through any kind of MemBar but normal loads shouldn't skip 1261 // through MemBarAcquire since the could allow them to move out of 1262 // a synchronized region. It is not safe to step over MemBarCPUOrder, 1263 // because alias info above them may be inaccurate (e.g., due to 1264 // mixed/mismatched unsafe accesses). 1265 bool is_final_mem = !atp->is_rewritable(); 1266 while (current->is_Proj()) { 1267 int opc = current->in(0)->Opcode(); 1268 if ((is_final_mem && (opc == Op_MemBarAcquire || 1269 opc == Op_MemBarAcquireLock || 1270 opc == Op_LoadFence)) || 1271 opc == Op_MemBarRelease || 1272 opc == Op_StoreFence || 1273 opc == Op_MemBarReleaseLock || 1274 opc == Op_MemBarStoreStore || 1275 opc == Op_StoreStoreFence) { 1276 Node* mem = current->in(0)->in(TypeFunc::Memory); 1277 if (mem->is_MergeMem()) { 1278 MergeMemNode* merge = mem->as_MergeMem(); 1279 Node* new_st = merge->memory_at(alias_idx); 1280 if (new_st == merge->base_memory()) { 1281 // Keep searching 1282 current = new_st; 1283 continue; 1284 } 1285 // Save the new memory state for the slice and fall through 1286 // to exit. 1287 result = new_st; 1288 } 1289 } 1290 break; 1291 } 1292 if (result != nullptr) { 1293 st = result; 1294 } 1295 } 1296 1297 // Loop around twice in the case Load -> Initialize -> Store. 1298 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1299 for (int trip = 0; trip <= 1; trip++) { 1300 1301 if (st->is_Store()) { 1302 Node* st_adr = st->in(MemNode::Address); 1303 if (st_adr != ld_adr) { 1304 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers). 1305 intptr_t st_off = 0; 1306 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off); 1307 if (ld_base == nullptr) return nullptr; 1308 if (st_base == nullptr) return nullptr; 1309 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr; 1310 if (ld_off != st_off) return nullptr; 1311 if (ld_off == Type::OffsetBot) return nullptr; 1312 // Same base, same offset. 1313 // Possible improvement for arrays: check index value instead of absolute offset. 1314 1315 // At this point we have proven something like this setup: 1316 // B = << base >> 1317 // L = LoadQ(AddP(Check/CastPP(B), #Off)) 1318 // S = StoreQ(AddP( B , #Off), V) 1319 // (Actually, we haven't yet proven the Q's are the same.) 1320 // In other words, we are loading from a casted version of 1321 // the same pointer-and-offset that we stored to. 1322 // Casted version may carry a dependency and it is respected. 1323 // Thus, we are able to replace L by V. 1324 } 1325 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1326 if (store_Opcode() != st->Opcode()) { 1327 return nullptr; 1328 } 1329 // LoadVector/StoreVector needs additional check to ensure the types match. 1330 if (st->is_StoreVector()) { 1331 const TypeVect* in_vt = st->as_StoreVector()->vect_type(); 1332 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type(); 1333 if (in_vt != out_vt) { 1334 return nullptr; 1335 } 1336 } 1337 return st->in(MemNode::ValueIn); 1338 } 1339 1340 // A load from a freshly-created object always returns zero. 1341 // (This can happen after LoadNode::Ideal resets the load's memory input 1342 // to find_captured_store, which returned InitializeNode::zero_memory.) 1343 if (st->is_Proj() && st->in(0)->is_Allocate() && 1344 (st->in(0) == ld_alloc) && 1345 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1346 // return a zero value for the load's basic type 1347 // (This is one of the few places where a generic PhaseTransform 1348 // can create new nodes. Think of it as lazily manifesting 1349 // virtually pre-existing constants.) 1350 Node* init_value = ld_alloc->in(AllocateNode::InitValue); 1351 if (init_value != nullptr) { 1352 // TODO 8350865 Scalar replacement does not work well for flat arrays. 1353 // Is this correct for non-all-zero init values? Don't we need field_value_by_offset? 1354 return init_value; 1355 } 1356 assert(ld_alloc->in(AllocateNode::RawInitValue) == nullptr, "init value may not be null"); 1357 if (value_basic_type() != T_VOID) { 1358 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) { 1359 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an 1360 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done 1361 // by the ArrayCopyNode. 1362 return phase->zerocon(value_basic_type()); 1363 } 1364 } else { 1365 // TODO: materialize all-zero vector constant 1366 assert(!isa_Load() || as_Load()->type()->isa_vect(), ""); 1367 } 1368 } 1369 1370 // A load from an initialization barrier can match a captured store. 1371 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1372 InitializeNode* init = st->in(0)->as_Initialize(); 1373 AllocateNode* alloc = init->allocation(); 1374 if ((alloc != nullptr) && (alloc == ld_alloc)) { 1375 // examine a captured store value 1376 st = init->find_captured_store(ld_off, memory_size(), phase); 1377 if (st != nullptr) { 1378 continue; // take one more trip around 1379 } 1380 } 1381 } 1382 1383 // Load boxed value from result of valueOf() call is input parameter. 1384 if (this->is_Load() && ld_adr->is_AddP() && 1385 (tp != nullptr) && tp->is_ptr_to_boxed_value()) { 1386 intptr_t ignore = 0; 1387 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1388 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 1389 base = bs->step_over_gc_barrier(base); 1390 if (base != nullptr && base->is_Proj() && 1391 base->as_Proj()->_con == TypeFunc::Parms && 1392 base->in(0)->is_CallStaticJava() && 1393 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1394 return base->in(0)->in(TypeFunc::Parms); 1395 } 1396 } 1397 1398 break; 1399 } 1400 1401 return nullptr; 1402 } 1403 1404 //----------------------is_instance_field_load_with_local_phi------------------ 1405 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1406 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1407 in(Address)->is_AddP() ) { 1408 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1409 // Only instances and boxed values. 1410 if( t_oop != nullptr && 1411 (t_oop->is_ptr_to_boxed_value() || 1412 t_oop->is_known_instance_field()) && 1413 t_oop->offset() != Type::OffsetBot && 1414 t_oop->offset() != Type::OffsetTop) { 1415 return true; 1416 } 1417 } 1418 return false; 1419 } 1420 1421 //------------------------------Identity--------------------------------------- 1422 // Loads are identity if previous store is to same address 1423 Node* LoadNode::Identity(PhaseGVN* phase) { 1424 // If the previous store-maker is the right kind of Store, and the store is 1425 // to the same address, then we are equal to the value stored. 1426 Node* mem = in(Memory); 1427 Node* value = can_see_stored_value(mem, phase); 1428 if( value ) { 1429 // byte, short & char stores truncate naturally. 1430 // A load has to load the truncated value which requires 1431 // some sort of masking operation and that requires an 1432 // Ideal call instead of an Identity call. 1433 if (memory_size() < BytesPerInt) { 1434 // If the input to the store does not fit with the load's result type, 1435 // it must be truncated via an Ideal call. 1436 if (!phase->type(value)->higher_equal(phase->type(this))) 1437 return this; 1438 } 1439 // (This works even when value is a Con, but LoadNode::Value 1440 // usually runs first, producing the singleton type of the Con.) 1441 if (!has_pinned_control_dependency() || value->is_Con()) { 1442 return value; 1443 } else { 1444 return this; 1445 } 1446 } 1447 1448 if (has_pinned_control_dependency()) { 1449 return this; 1450 } 1451 // Search for an existing data phi which was generated before for the same 1452 // instance's field to avoid infinite generation of phis in a loop. 1453 Node *region = mem->in(0); 1454 if (is_instance_field_load_with_local_phi(region)) { 1455 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1456 int this_index = phase->C->get_alias_index(addr_t); 1457 int this_offset = addr_t->offset(); 1458 int this_iid = addr_t->instance_id(); 1459 if (!addr_t->is_known_instance() && 1460 addr_t->is_ptr_to_boxed_value()) { 1461 // Use _idx of address base (could be Phi node) for boxed values. 1462 intptr_t ignore = 0; 1463 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1464 if (base == nullptr) { 1465 return this; 1466 } 1467 this_iid = base->_idx; 1468 } 1469 const Type* this_type = bottom_type(); 1470 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1471 Node* phi = region->fast_out(i); 1472 if (phi->is_Phi() && phi != mem && 1473 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) { 1474 return phi; 1475 } 1476 } 1477 } 1478 1479 return this; 1480 } 1481 1482 // Construct an equivalent unsigned load. 1483 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) { 1484 BasicType bt = T_ILLEGAL; 1485 const Type* rt = nullptr; 1486 switch (Opcode()) { 1487 case Op_LoadUB: return this; 1488 case Op_LoadUS: return this; 1489 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break; 1490 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break; 1491 default: 1492 assert(false, "no unsigned variant: %s", Name()); 1493 return nullptr; 1494 } 1495 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1496 raw_adr_type(), rt, bt, _mo, _control_dependency, 1497 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access()); 1498 } 1499 1500 // Construct an equivalent signed load. 1501 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) { 1502 BasicType bt = T_ILLEGAL; 1503 const Type* rt = nullptr; 1504 switch (Opcode()) { 1505 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break; 1506 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break; 1507 case Op_LoadB: // fall through 1508 case Op_LoadS: // fall through 1509 case Op_LoadI: // fall through 1510 case Op_LoadL: return this; 1511 default: 1512 assert(false, "no signed variant: %s", Name()); 1513 return nullptr; 1514 } 1515 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1516 raw_adr_type(), rt, bt, _mo, _control_dependency, 1517 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access()); 1518 } 1519 1520 bool LoadNode::has_reinterpret_variant(const Type* rt) { 1521 BasicType bt = rt->basic_type(); 1522 switch (Opcode()) { 1523 case Op_LoadI: return (bt == T_FLOAT); 1524 case Op_LoadL: return (bt == T_DOUBLE); 1525 case Op_LoadF: return (bt == T_INT); 1526 case Op_LoadD: return (bt == T_LONG); 1527 1528 default: return false; 1529 } 1530 } 1531 1532 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) { 1533 BasicType bt = rt->basic_type(); 1534 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt)); 1535 bool is_mismatched = is_mismatched_access(); 1536 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr(); 1537 if (raw_type == nullptr) { 1538 is_mismatched = true; // conservatively match all non-raw accesses as mismatched 1539 } 1540 const int op = Opcode(); 1541 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) || 1542 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access()); 1543 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1544 raw_adr_type(), rt, bt, _mo, _control_dependency, 1545 require_atomic_access, is_unaligned_access(), is_mismatched); 1546 } 1547 1548 bool StoreNode::has_reinterpret_variant(const Type* vt) { 1549 BasicType bt = vt->basic_type(); 1550 switch (Opcode()) { 1551 case Op_StoreI: return (bt == T_FLOAT); 1552 case Op_StoreL: return (bt == T_DOUBLE); 1553 case Op_StoreF: return (bt == T_INT); 1554 case Op_StoreD: return (bt == T_LONG); 1555 1556 default: return false; 1557 } 1558 } 1559 1560 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) { 1561 BasicType bt = vt->basic_type(); 1562 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt)); 1563 const int op = Opcode(); 1564 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) || 1565 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access()); 1566 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1567 raw_adr_type(), val, bt, _mo, require_atomic_access); 1568 1569 bool is_mismatched = is_mismatched_access(); 1570 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr(); 1571 if (raw_type == nullptr) { 1572 is_mismatched = true; // conservatively match all non-raw accesses as mismatched 1573 } 1574 if (is_mismatched) { 1575 st->set_mismatched_access(); 1576 } 1577 return st; 1578 } 1579 1580 // We're loading from an object which has autobox behaviour. 1581 // If this object is result of a valueOf call we'll have a phi 1582 // merging a newly allocated object and a load from the cache. 1583 // We want to replace this load with the original incoming 1584 // argument to the valueOf call. 1585 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) { 1586 assert(igvn->C->eliminate_boxing(), "sanity"); 1587 intptr_t ignore = 0; 1588 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore); 1589 if ((base == nullptr) || base->is_Phi()) { 1590 // Push the loads from the phi that comes from valueOf up 1591 // through it to allow elimination of the loads and the recovery 1592 // of the original value. It is done in split_through_phi(). 1593 return nullptr; 1594 } else if (base->is_Load() || 1595 (base->is_DecodeN() && base->in(1)->is_Load())) { 1596 // Eliminate the load of boxed value for integer types from the cache 1597 // array by deriving the value from the index into the array. 1598 // Capture the offset of the load and then reverse the computation. 1599 1600 // Get LoadN node which loads a boxing object from 'cache' array. 1601 if (base->is_DecodeN()) { 1602 base = base->in(1); 1603 } 1604 if (!base->in(Address)->is_AddP()) { 1605 return nullptr; // Complex address 1606 } 1607 AddPNode* address = base->in(Address)->as_AddP(); 1608 Node* cache_base = address->in(AddPNode::Base); 1609 if ((cache_base != nullptr) && cache_base->is_DecodeN()) { 1610 // Get ConP node which is static 'cache' field. 1611 cache_base = cache_base->in(1); 1612 } 1613 if ((cache_base != nullptr) && cache_base->is_Con()) { 1614 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1615 if ((base_type != nullptr) && base_type->is_autobox_cache()) { 1616 Node* elements[4]; 1617 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1618 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1619 if (count > 0 && elements[0]->is_Con() && 1620 (count == 1 || 1621 (count == 2 && elements[1]->Opcode() == Op_LShiftX && 1622 elements[1]->in(2) == igvn->intcon(shift)))) { 1623 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1624 // Fetch the box object cache[0] at the base of the array and get its value 1625 ciInstance* box = array->obj_at(0)->as_instance(); 1626 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1627 assert(ik->is_box_klass(), "sanity"); 1628 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1629 if (ik->nof_nonstatic_fields() == 1) { 1630 // This should be true nonstatic_field_at requires calling 1631 // nof_nonstatic_fields so check it anyway 1632 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1633 BasicType bt = c.basic_type(); 1634 // Only integer types have boxing cache. 1635 assert(bt == T_BOOLEAN || bt == T_CHAR || 1636 bt == T_BYTE || bt == T_SHORT || 1637 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt)); 1638 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1639 if (cache_low != (int)cache_low) { 1640 return nullptr; // should not happen since cache is array indexed by value 1641 } 1642 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1643 if (offset != (int)offset) { 1644 return nullptr; // should not happen since cache is array indexed by value 1645 } 1646 // Add up all the offsets making of the address of the load 1647 Node* result = elements[0]; 1648 for (int i = 1; i < count; i++) { 1649 result = igvn->transform(new AddXNode(result, elements[i])); 1650 } 1651 // Remove the constant offset from the address and then 1652 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset))); 1653 // remove the scaling of the offset to recover the original index. 1654 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) { 1655 // Peel the shift off directly but wrap it in a dummy node 1656 // since Ideal can't return existing nodes 1657 igvn->_worklist.push(result); // remove dead node later 1658 result = new RShiftXNode(result->in(1), igvn->intcon(0)); 1659 } else if (result->is_Add() && result->in(2)->is_Con() && 1660 result->in(1)->Opcode() == Op_LShiftX && 1661 result->in(1)->in(2) == igvn->intcon(shift)) { 1662 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1663 // but for boxing cache access we know that X<<Z will not overflow 1664 // (there is range check) so we do this optimizatrion by hand here. 1665 igvn->_worklist.push(result); // remove dead node later 1666 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift)); 1667 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con)); 1668 } else { 1669 result = new RShiftXNode(result, igvn->intcon(shift)); 1670 } 1671 #ifdef _LP64 1672 if (bt != T_LONG) { 1673 result = new ConvL2INode(igvn->transform(result)); 1674 } 1675 #else 1676 if (bt == T_LONG) { 1677 result = new ConvI2LNode(igvn->transform(result)); 1678 } 1679 #endif 1680 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1681 // Need to preserve unboxing load type if it is unsigned. 1682 switch(this->Opcode()) { 1683 case Op_LoadUB: 1684 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF)); 1685 break; 1686 case Op_LoadUS: 1687 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF)); 1688 break; 1689 } 1690 return result; 1691 } 1692 } 1693 } 1694 } 1695 } 1696 return nullptr; 1697 } 1698 1699 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1700 Node* region = phi->in(0); 1701 if (region == nullptr) { 1702 return false; // Wait stable graph 1703 } 1704 uint cnt = phi->req(); 1705 for (uint i = 1; i < cnt; i++) { 1706 Node* rc = region->in(i); 1707 if (rc == nullptr || phase->type(rc) == Type::TOP) 1708 return false; // Wait stable graph 1709 Node* in = phi->in(i); 1710 if (in == nullptr || phase->type(in) == Type::TOP) 1711 return false; // Wait stable graph 1712 } 1713 return true; 1714 } 1715 1716 //------------------------------split_through_phi------------------------------ 1717 // Check whether a call to 'split_through_phi' would split this load through the 1718 // Phi *base*. This method is essentially a copy of the validations performed 1719 // by 'split_through_phi'. The first use of this method was in EA code as part 1720 // of simplification of allocation merges. 1721 // Some differences from original method (split_through_phi): 1722 // - If base->is_CastPP(): base = base->in(1) 1723 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) { 1724 Node* mem = in(Memory); 1725 Node* address = in(Address); 1726 intptr_t ignore = 0; 1727 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1728 1729 if (base->is_CastPP()) { 1730 base = base->in(1); 1731 } 1732 1733 if (req() > 3 || base == nullptr || !base->is_Phi()) { 1734 return false; 1735 } 1736 1737 if (!mem->is_Phi()) { 1738 if (!MemNode::all_controls_dominate(mem, base->in(0))) { 1739 return false; 1740 } 1741 } else if (base->in(0) != mem->in(0)) { 1742 if (!MemNode::all_controls_dominate(mem, base->in(0))) { 1743 return false; 1744 } 1745 } 1746 1747 return true; 1748 } 1749 1750 //------------------------------split_through_phi------------------------------ 1751 // Split instance or boxed field load through Phi. 1752 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) { 1753 if (req() > 3) { 1754 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs"); 1755 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account 1756 return nullptr; 1757 } 1758 Node* mem = in(Memory); 1759 Node* address = in(Address); 1760 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1761 1762 assert((t_oop != nullptr) && 1763 (ignore_missing_instance_id || 1764 t_oop->is_known_instance_field() || 1765 t_oop->is_ptr_to_boxed_value()), "invalid conditions"); 1766 1767 Compile* C = phase->C; 1768 intptr_t ignore = 0; 1769 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1770 bool base_is_phi = (base != nullptr) && base->is_Phi(); 1771 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1772 (base != nullptr) && (base == address->in(AddPNode::Base)) && 1773 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1774 1775 if (!((mem->is_Phi() || base_is_phi) && 1776 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) { 1777 return nullptr; // Neither memory or base are Phi 1778 } 1779 1780 if (mem->is_Phi()) { 1781 if (!stable_phi(mem->as_Phi(), phase)) { 1782 return nullptr; // Wait stable graph 1783 } 1784 uint cnt = mem->req(); 1785 // Check for loop invariant memory. 1786 if (cnt == 3) { 1787 for (uint i = 1; i < cnt; i++) { 1788 Node* in = mem->in(i); 1789 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1790 if (m == mem) { 1791 if (i == 1) { 1792 // if the first edge was a loop, check second edge too. 1793 // If both are replaceable - we are in an infinite loop 1794 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase); 1795 if (n == mem) { 1796 break; 1797 } 1798 } 1799 set_req(Memory, mem->in(cnt - i)); 1800 return this; // made change 1801 } 1802 } 1803 } 1804 } 1805 if (base_is_phi) { 1806 if (!stable_phi(base->as_Phi(), phase)) { 1807 return nullptr; // Wait stable graph 1808 } 1809 uint cnt = base->req(); 1810 // Check for loop invariant memory. 1811 if (cnt == 3) { 1812 for (uint i = 1; i < cnt; i++) { 1813 if (base->in(i) == base) { 1814 return nullptr; // Wait stable graph 1815 } 1816 } 1817 } 1818 } 1819 1820 // Split through Phi (see original code in loopopts.cpp). 1821 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type"); 1822 1823 // Do nothing here if Identity will find a value 1824 // (to avoid infinite chain of value phis generation). 1825 if (this != Identity(phase)) { 1826 return nullptr; 1827 } 1828 1829 // Select Region to split through. 1830 Node* region; 1831 DomResult dom_result = DomResult::Dominate; 1832 if (!base_is_phi) { 1833 assert(mem->is_Phi(), "sanity"); 1834 region = mem->in(0); 1835 // Skip if the region dominates some control edge of the address. 1836 // We will check `dom_result` later. 1837 dom_result = MemNode::maybe_all_controls_dominate(address, region); 1838 } else if (!mem->is_Phi()) { 1839 assert(base_is_phi, "sanity"); 1840 region = base->in(0); 1841 // Skip if the region dominates some control edge of the memory. 1842 // We will check `dom_result` later. 1843 dom_result = MemNode::maybe_all_controls_dominate(mem, region); 1844 } else if (base->in(0) != mem->in(0)) { 1845 assert(base_is_phi && mem->is_Phi(), "sanity"); 1846 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0)); 1847 if (dom_result == DomResult::Dominate) { 1848 region = base->in(0); 1849 } else { 1850 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0)); 1851 if (dom_result == DomResult::Dominate) { 1852 region = mem->in(0); 1853 } 1854 // Otherwise we encountered a complex graph. 1855 } 1856 } else { 1857 assert(base->in(0) == mem->in(0), "sanity"); 1858 region = mem->in(0); 1859 } 1860 1861 PhaseIterGVN* igvn = phase->is_IterGVN(); 1862 if (dom_result != DomResult::Dominate) { 1863 if (dom_result == DomResult::EncounteredDeadCode) { 1864 // There is some dead code which eventually will be removed in IGVN. 1865 // Once this is the case, we get an unambiguous dominance result. 1866 // Push the node to the worklist again until the dead code is removed. 1867 igvn->_worklist.push(this); 1868 } 1869 return nullptr; 1870 } 1871 1872 Node* phi = nullptr; 1873 const Type* this_type = this->bottom_type(); 1874 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) { 1875 int this_index = C->get_alias_index(t_oop); 1876 int this_offset = t_oop->offset(); 1877 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx; 1878 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset); 1879 } else if (ignore_missing_instance_id) { 1880 phi = new PhiNode(region, this_type, nullptr, mem->_idx); 1881 } else { 1882 return nullptr; 1883 } 1884 1885 for (uint i = 1; i < region->req(); i++) { 1886 Node* x; 1887 Node* the_clone = nullptr; 1888 Node* in = region->in(i); 1889 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl && 1890 in != nullptr && in->is_OuterStripMinedLoop()) { 1891 // No node should go in the outer strip mined loop 1892 in = in->in(LoopNode::EntryControl); 1893 } 1894 if (in == nullptr || in == C->top()) { 1895 x = C->top(); // Dead path? Use a dead data op 1896 } else { 1897 x = this->clone(); // Else clone up the data op 1898 the_clone = x; // Remember for possible deletion. 1899 // Alter data node to use pre-phi inputs 1900 if (this->in(0) == region) { 1901 x->set_req(0, in); 1902 } else { 1903 x->set_req(0, nullptr); 1904 } 1905 if (mem->is_Phi() && (mem->in(0) == region)) { 1906 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1907 } 1908 if (address->is_Phi() && address->in(0) == region) { 1909 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1910 } 1911 if (base_is_phi && (base->in(0) == region)) { 1912 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1913 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1914 x->set_req(Address, adr_x); 1915 } 1916 } 1917 // Check for a 'win' on some paths 1918 const Type *t = x->Value(igvn); 1919 1920 bool singleton = t->singleton(); 1921 1922 // See comments in PhaseIdealLoop::split_thru_phi(). 1923 if (singleton && t == Type::TOP) { 1924 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1925 } 1926 1927 if (singleton) { 1928 x = igvn->makecon(t); 1929 } else { 1930 // We now call Identity to try to simplify the cloned node. 1931 // Note that some Identity methods call phase->type(this). 1932 // Make sure that the type array is big enough for 1933 // our new node, even though we may throw the node away. 1934 // (This tweaking with igvn only works because x is a new node.) 1935 igvn->set_type(x, t); 1936 // If x is a TypeNode, capture any more-precise type permanently into Node 1937 // otherwise it will be not updated during igvn->transform since 1938 // igvn->type(x) is set to x->Value() already. 1939 x->raise_bottom_type(t); 1940 Node* y = x->Identity(igvn); 1941 if (y != x) { 1942 x = y; 1943 } else { 1944 y = igvn->hash_find_insert(x); 1945 if (y) { 1946 x = y; 1947 } else { 1948 // Else x is a new node we are keeping 1949 // We do not need register_new_node_with_optimizer 1950 // because set_type has already been called. 1951 igvn->_worklist.push(x); 1952 } 1953 } 1954 } 1955 if (x != the_clone && the_clone != nullptr) { 1956 igvn->remove_dead_node(the_clone); 1957 } 1958 phi->set_req(i, x); 1959 } 1960 // Record Phi 1961 igvn->register_new_node_with_optimizer(phi); 1962 return phi; 1963 } 1964 1965 AllocateNode* LoadNode::is_new_object_mark_load() const { 1966 if (Opcode() == Op_LoadX) { 1967 Node* address = in(MemNode::Address); 1968 AllocateNode* alloc = AllocateNode::Ideal_allocation(address); 1969 Node* mem = in(MemNode::Memory); 1970 if (alloc != nullptr && mem->is_Proj() && 1971 mem->in(0) != nullptr && 1972 mem->in(0) == alloc->initialization() && 1973 alloc->initialization()->proj_out_or_null(0) != nullptr) { 1974 return alloc; 1975 } 1976 } 1977 return nullptr; 1978 } 1979 1980 1981 //------------------------------Ideal------------------------------------------ 1982 // If the load is from Field memory and the pointer is non-null, it might be possible to 1983 // zero out the control input. 1984 // If the offset is constant and the base is an object allocation, 1985 // try to hook me up to the exact initializing store. 1986 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1987 if (has_pinned_control_dependency()) { 1988 return nullptr; 1989 } 1990 Node* p = MemNode::Ideal_common(phase, can_reshape); 1991 if (p) return (p == NodeSentinel) ? nullptr : p; 1992 1993 Node* ctrl = in(MemNode::Control); 1994 Node* address = in(MemNode::Address); 1995 bool progress = false; 1996 1997 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) && 1998 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes()); 1999 2000 // Skip up past a SafePoint control. Cannot do this for Stores because 2001 // pointer stores & cardmarks must stay on the same side of a SafePoint. 2002 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint && 2003 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw && 2004 !addr_mark && 2005 (depends_only_on_test() || has_unknown_control_dependency())) { 2006 ctrl = ctrl->in(0); 2007 set_req(MemNode::Control,ctrl); 2008 progress = true; 2009 } 2010 2011 intptr_t ignore = 0; 2012 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 2013 if (base != nullptr 2014 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 2015 // Check for useless control edge in some common special cases 2016 if (in(MemNode::Control) != nullptr 2017 && !(phase->type(address)->is_inlinetypeptr() && is_mismatched_access()) 2018 && can_remove_control() 2019 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 2020 && all_controls_dominate(base, phase->C->start())) { 2021 // A method-invariant, non-null address (constant or 'this' argument). 2022 set_req(MemNode::Control, nullptr); 2023 progress = true; 2024 } 2025 } 2026 2027 Node* mem = in(MemNode::Memory); 2028 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 2029 2030 if (can_reshape && (addr_t != nullptr)) { 2031 // try to optimize our memory input 2032 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 2033 if (opt_mem != mem) { 2034 set_req_X(MemNode::Memory, opt_mem, phase); 2035 if (phase->type( opt_mem ) == Type::TOP) return nullptr; 2036 return this; 2037 } 2038 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 2039 if ((t_oop != nullptr) && 2040 (t_oop->is_known_instance_field() || 2041 t_oop->is_ptr_to_boxed_value())) { 2042 PhaseIterGVN *igvn = phase->is_IterGVN(); 2043 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true"); 2044 if (igvn->_worklist.member(opt_mem)) { 2045 // Delay this transformation until memory Phi is processed. 2046 igvn->_worklist.push(this); 2047 return nullptr; 2048 } 2049 // Split instance field load through Phi. 2050 Node* result = split_through_phi(phase); 2051 if (result != nullptr) return result; 2052 2053 if (t_oop->is_ptr_to_boxed_value()) { 2054 Node* result = eliminate_autobox(igvn); 2055 if (result != nullptr) return result; 2056 } 2057 } 2058 } 2059 2060 // Is there a dominating load that loads the same value? Leave 2061 // anything that is not a load of a field/array element (like 2062 // barriers etc.) alone 2063 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) { 2064 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 2065 Node *use = mem->fast_out(i); 2066 if (use != this && 2067 use->Opcode() == Opcode() && 2068 use->in(0) != nullptr && 2069 use->in(0) != in(0) && 2070 use->in(Address) == in(Address)) { 2071 Node* ctl = in(0); 2072 for (int i = 0; i < 10 && ctl != nullptr; i++) { 2073 ctl = IfNode::up_one_dom(ctl); 2074 if (ctl == use->in(0)) { 2075 set_req(0, use->in(0)); 2076 return this; 2077 } 2078 } 2079 } 2080 } 2081 } 2082 2083 // Check for prior store with a different base or offset; make Load 2084 // independent. Skip through any number of them. Bail out if the stores 2085 // are in an endless dead cycle and report no progress. This is a key 2086 // transform for Reflection. However, if after skipping through the Stores 2087 // we can't then fold up against a prior store do NOT do the transform as 2088 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 2089 // array memory alive twice: once for the hoisted Load and again after the 2090 // bypassed Store. This situation only works if EVERYBODY who does 2091 // anti-dependence work knows how to bypass. I.e. we need all 2092 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 2093 // the alias index stuff. So instead, peek through Stores and IFF we can 2094 // fold up, do so. 2095 Node* prev_mem = find_previous_store(phase); 2096 if (prev_mem != nullptr) { 2097 Node* value = can_see_arraycopy_value(prev_mem, phase); 2098 if (value != nullptr) { 2099 return value; 2100 } 2101 } 2102 // Steps (a), (b): Walk past independent stores to find an exact match. 2103 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) { 2104 // (c) See if we can fold up on the spot, but don't fold up here. 2105 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 2106 // just return a prior value, which is done by Identity calls. 2107 if (can_see_stored_value(prev_mem, phase)) { 2108 // Make ready for step (d): 2109 set_req_X(MemNode::Memory, prev_mem, phase); 2110 return this; 2111 } 2112 } 2113 2114 if (progress) { 2115 return this; 2116 } 2117 2118 if (!can_reshape) { 2119 phase->record_for_igvn(this); 2120 } 2121 return nullptr; 2122 } 2123 2124 // Helper to recognize certain Klass fields which are invariant across 2125 // some group of array types (e.g., int[] or all T[] where T < Object). 2126 const Type* 2127 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 2128 ciKlass* klass) const { 2129 assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()), 2130 "must not happen"); 2131 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 2132 // The field is Klass::_access_flags. Return its (constant) value. 2133 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags"); 2134 return TypeInt::make(klass->access_flags()); 2135 } 2136 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) { 2137 // The field is Klass::_misc_flags. Return its (constant) value. 2138 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags"); 2139 return TypeInt::make(klass->misc_flags()); 2140 } 2141 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 2142 // The field is Klass::_layout_helper. Return its constant value if known. 2143 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 2144 return TypeInt::make(klass->layout_helper()); 2145 } 2146 2147 // No match. 2148 return nullptr; 2149 } 2150 2151 //------------------------------Value----------------------------------------- 2152 const Type* LoadNode::Value(PhaseGVN* phase) const { 2153 // Either input is TOP ==> the result is TOP 2154 Node* mem = in(MemNode::Memory); 2155 const Type *t1 = phase->type(mem); 2156 if (t1 == Type::TOP) return Type::TOP; 2157 Node* adr = in(MemNode::Address); 2158 const TypePtr* tp = phase->type(adr)->isa_ptr(); 2159 if (tp == nullptr || tp->empty()) return Type::TOP; 2160 int off = tp->offset(); 2161 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 2162 Compile* C = phase->C; 2163 2164 // If we are loading from a freshly-allocated object, produce a zero, 2165 // if the load is provably beyond the header of the object. 2166 // (Also allow a variable load from a fresh array to produce zero.) 2167 const TypeOopPtr* tinst = tp->isa_oopptr(); 2168 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field(); 2169 Node* value = can_see_stored_value(mem, phase); 2170 if (value != nullptr && value->is_Con()) { 2171 assert(value->bottom_type()->higher_equal(_type), "sanity"); 2172 return value->bottom_type(); 2173 } 2174 2175 // Try to guess loaded type from pointer type 2176 if (tp->isa_aryptr()) { 2177 const TypeAryPtr* ary = tp->is_aryptr(); 2178 const Type* t = ary->elem(); 2179 2180 // Determine whether the reference is beyond the header or not, by comparing 2181 // the offset against the offset of the start of the array's data. 2182 // Different array types begin at slightly different offsets (12 vs. 16). 2183 // We choose T_BYTE as an example base type that is least restrictive 2184 // as to alignment, which will therefore produce the smallest 2185 // possible base offset. 2186 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 2187 const bool off_beyond_header = (off >= min_base_off); 2188 2189 // Try to constant-fold a stable array element. 2190 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) { 2191 // Make sure the reference is not into the header and the offset is constant 2192 ciObject* aobj = ary->const_oop(); 2193 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 2194 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0); 2195 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, 2196 stable_dimension, 2197 value_basic_type(), is_unsigned()); 2198 if (con_type != nullptr) { 2199 return con_type; 2200 } 2201 } 2202 } 2203 2204 // Don't do this for integer types. There is only potential profit if 2205 // the element type t is lower than _type; that is, for int types, if _type is 2206 // more restrictive than t. This only happens here if one is short and the other 2207 // char (both 16 bits), and in those cases we've made an intentional decision 2208 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 2209 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 2210 // 2211 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 2212 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 2213 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 2214 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 2215 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 2216 // In fact, that could have been the original type of p1, and p1 could have 2217 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 2218 // expression (LShiftL quux 3) independently optimized to the constant 8. 2219 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr) 2220 && (_type->isa_vect() == nullptr) 2221 && !ary->is_flat() 2222 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 2223 // t might actually be lower than _type, if _type is a unique 2224 // concrete subclass of abstract class t. 2225 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header? 2226 const Type* jt = t->join_speculative(_type); 2227 // In any case, do not allow the join, per se, to empty out the type. 2228 if (jt->empty() && !t->empty()) { 2229 // This can happen if a interface-typed array narrows to a class type. 2230 jt = _type; 2231 } 2232 #ifdef ASSERT 2233 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 2234 // The pointers in the autobox arrays are always non-null 2235 Node* base = adr->in(AddPNode::Base); 2236 if ((base != nullptr) && base->is_DecodeN()) { 2237 // Get LoadN node which loads IntegerCache.cache field 2238 base = base->in(1); 2239 } 2240 if ((base != nullptr) && base->is_Con()) { 2241 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 2242 if ((base_type != nullptr) && base_type->is_autobox_cache()) { 2243 // It could be narrow oop 2244 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 2245 } 2246 } 2247 } 2248 #endif 2249 return jt; 2250 } 2251 } 2252 } else if (tp->base() == Type::InstPtr) { 2253 assert( off != Type::OffsetBot || 2254 // arrays can be cast to Objects 2255 !tp->isa_instptr() || 2256 tp->is_instptr()->instance_klass()->is_java_lang_Object() || 2257 // Default value load 2258 tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() || 2259 // unsafe field access may not have a constant offset 2260 C->has_unsafe_access(), 2261 "Field accesses must be precise" ); 2262 // For oop loads, we expect the _type to be precise. 2263 2264 const TypeInstPtr* tinst = tp->is_instptr(); 2265 BasicType bt = value_basic_type(); 2266 2267 // Optimize loads from constant fields. 2268 ciObject* const_oop = tinst->const_oop(); 2269 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) { 2270 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt); 2271 if (con_type != nullptr) { 2272 return con_type; 2273 } 2274 } 2275 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) { 2276 assert(off != Type::OffsetBot || 2277 !tp->isa_instklassptr() || 2278 // arrays can be cast to Objects 2279 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() || 2280 // also allow array-loading from the primary supertype 2281 // array during subtype checks 2282 Opcode() == Op_LoadKlass, 2283 "Field accesses must be precise"); 2284 // For klass/static loads, we expect the _type to be precise 2285 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) { 2286 /* With mirrors being an indirect in the Klass* 2287 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset)) 2288 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass). 2289 * 2290 * So check the type and klass of the node before the LoadP. 2291 */ 2292 Node* adr2 = adr->in(MemNode::Address); 2293 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2294 if (tkls != nullptr && !StressReflectiveCode) { 2295 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 2296 ciKlass* klass = tkls->exact_klass(); 2297 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 2298 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 2299 return TypeInstPtr::make(klass->java_mirror()); 2300 } 2301 } 2302 } 2303 2304 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2305 if (tkls != nullptr) { 2306 if (tkls->is_loaded() && tkls->klass_is_exact()) { 2307 ciKlass* klass = tkls->exact_klass(); 2308 // We are loading a field from a Klass metaobject whose identity 2309 // is known at compile time (the type is "exact" or "precise"). 2310 // Check for fields we know are maintained as constants by the VM. 2311 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 2312 // The field is Klass::_super_check_offset. Return its (constant) value. 2313 // (Folds up type checking code.) 2314 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 2315 return TypeInt::make(klass->super_check_offset()); 2316 } 2317 if (klass->is_flat_array_klass() && tkls->offset() == in_bytes(FlatArrayKlass::layout_kind_offset())) { 2318 assert(Opcode() == Op_LoadI, "must load an int from _layout_kind"); 2319 return TypeInt::make(static_cast<jint>(klass->as_flat_array_klass()->layout_kind())); 2320 } 2321 if (UseCompactObjectHeaders) { // TODO: Should EnableValhalla also take this path ? 2322 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) { 2323 // The field is Klass::_prototype_header. Return its (constant) value. 2324 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header"); 2325 return TypeX::make(klass->prototype_header()); 2326 } 2327 } 2328 // Compute index into primary_supers array 2329 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 2330 // Check for overflowing; use unsigned compare to handle the negative case. 2331 if( depth < ciKlass::primary_super_limit() ) { 2332 // The field is an element of Klass::_primary_supers. Return its (constant) value. 2333 // (Folds up type checking code.) 2334 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 2335 ciKlass *ss = klass->super_of_depth(depth); 2336 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR; 2337 } 2338 const Type* aift = load_array_final_field(tkls, klass); 2339 if (aift != nullptr) return aift; 2340 } 2341 2342 // We can still check if we are loading from the primary_supers array at a 2343 // shallow enough depth. Even though the klass is not exact, entries less 2344 // than or equal to its super depth are correct. 2345 if (tkls->is_loaded()) { 2346 ciKlass* klass = nullptr; 2347 if (tkls->isa_instklassptr()) { 2348 klass = tkls->is_instklassptr()->instance_klass(); 2349 } else { 2350 int dims; 2351 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims); 2352 if (inner->isa_instklassptr()) { 2353 klass = inner->is_instklassptr()->instance_klass(); 2354 klass = ciObjArrayKlass::make(klass, dims); 2355 } 2356 } 2357 if (klass != nullptr) { 2358 // Compute index into primary_supers array 2359 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 2360 // Check for overflowing; use unsigned compare to handle the negative case. 2361 if (depth < ciKlass::primary_super_limit() && 2362 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case 2363 // The field is an element of Klass::_primary_supers. Return its (constant) value. 2364 // (Folds up type checking code.) 2365 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 2366 ciKlass *ss = klass->super_of_depth(depth); 2367 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR; 2368 } 2369 } 2370 } 2371 2372 // If the type is enough to determine that the thing is not an array, 2373 // we can give the layout_helper a positive interval type. 2374 // This will help short-circuit some reflective code. 2375 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) && 2376 tkls->isa_instklassptr() && // not directly typed as an array 2377 !tkls->is_instklassptr()->might_be_an_array() // not the supertype of all T[] (java.lang.Object) or has an interface that is not Serializable or Cloneable 2378 ) { 2379 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 2380 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 2381 // The key property of this type is that it folds up tests 2382 // for array-ness, since it proves that the layout_helper is positive. 2383 // Thus, a generic value like the basic object layout helper works fine. 2384 return TypeInt::make(min_size, max_jint, Type::WidenMin); 2385 } 2386 } 2387 2388 bool is_vect = (_type->isa_vect() != nullptr); 2389 if (is_instance && !is_vect) { 2390 // If we have an instance type and our memory input is the 2391 // programs's initial memory state, there is no matching store, 2392 // so just return a zero of the appropriate type - 2393 // except if it is vectorized - then we have no zero constant. 2394 Node *mem = in(MemNode::Memory); 2395 if (mem->is_Parm() && mem->in(0)->is_Start()) { 2396 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 2397 // TODO 8350865 Scalar replacement does not work well for flat arrays. 2398 // Escape Analysis assumes that arrays are always zeroed during allocation which is not true for null-free arrays 2399 // ConnectionGraph::split_unique_types will re-wire the memory of loads from such arrays around the allocation 2400 // TestArrays::test6 and test152 and TestBasicFunctionality::test20 are affected by this. 2401 if (tp->isa_aryptr() && tp->is_aryptr()->is_flat() && tp->is_aryptr()->is_null_free()) { 2402 intptr_t offset = 0; 2403 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2404 AllocateNode* alloc = AllocateNode::Ideal_allocation(base); 2405 if (alloc != nullptr && alloc->is_AllocateArray() && alloc->in(AllocateNode::InitValue) != nullptr) { 2406 return _type; 2407 } 2408 } 2409 return Type::get_zero_type(_type->basic_type()); 2410 } 2411 } 2412 if (!UseCompactObjectHeaders) { 2413 Node* alloc = is_new_object_mark_load(); 2414 if (alloc != nullptr) { 2415 if (EnableValhalla) { 2416 // The mark word may contain property bits (inline, flat, null-free) 2417 Node* klass_node = alloc->in(AllocateNode::KlassNode); 2418 const TypeKlassPtr* tkls = phase->type(klass_node)->isa_klassptr(); 2419 if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact()) { 2420 return TypeX::make(tkls->exact_klass()->prototype_header()); 2421 } 2422 } else { 2423 return TypeX::make(markWord::prototype().value()); 2424 } 2425 } 2426 } 2427 2428 return _type; 2429 } 2430 2431 //------------------------------match_edge------------------------------------- 2432 // Do we Match on this edge index or not? Match only the address. 2433 uint LoadNode::match_edge(uint idx) const { 2434 return idx == MemNode::Address; 2435 } 2436 2437 //--------------------------LoadBNode::Ideal-------------------------------------- 2438 // 2439 // If the previous store is to the same address as this load, 2440 // and the value stored was larger than a byte, replace this load 2441 // with the value stored truncated to a byte. If no truncation is 2442 // needed, the replacement is done in LoadNode::Identity(). 2443 // 2444 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2445 Node* mem = in(MemNode::Memory); 2446 Node* value = can_see_stored_value(mem,phase); 2447 if (value != nullptr) { 2448 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false); 2449 if (narrow != value) { 2450 return narrow; 2451 } 2452 } 2453 // Identity call will handle the case where truncation is not needed. 2454 return LoadNode::Ideal(phase, can_reshape); 2455 } 2456 2457 const Type* LoadBNode::Value(PhaseGVN* phase) const { 2458 Node* mem = in(MemNode::Memory); 2459 Node* value = can_see_stored_value(mem,phase); 2460 if (value != nullptr && value->is_Con() && 2461 !value->bottom_type()->higher_equal(_type)) { 2462 // If the input to the store does not fit with the load's result type, 2463 // it must be truncated. We can't delay until Ideal call since 2464 // a singleton Value is needed for split_thru_phi optimization. 2465 int con = value->get_int(); 2466 return TypeInt::make((con << 24) >> 24); 2467 } 2468 return LoadNode::Value(phase); 2469 } 2470 2471 //--------------------------LoadUBNode::Ideal------------------------------------- 2472 // 2473 // If the previous store is to the same address as this load, 2474 // and the value stored was larger than a byte, replace this load 2475 // with the value stored truncated to a byte. If no truncation is 2476 // needed, the replacement is done in LoadNode::Identity(). 2477 // 2478 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2479 Node* mem = in(MemNode::Memory); 2480 Node* value = can_see_stored_value(mem, phase); 2481 if (value != nullptr) { 2482 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false); 2483 if (narrow != value) { 2484 return narrow; 2485 } 2486 } 2487 // Identity call will handle the case where truncation is not needed. 2488 return LoadNode::Ideal(phase, can_reshape); 2489 } 2490 2491 const Type* LoadUBNode::Value(PhaseGVN* phase) const { 2492 Node* mem = in(MemNode::Memory); 2493 Node* value = can_see_stored_value(mem,phase); 2494 if (value != nullptr && value->is_Con() && 2495 !value->bottom_type()->higher_equal(_type)) { 2496 // If the input to the store does not fit with the load's result type, 2497 // it must be truncated. We can't delay until Ideal call since 2498 // a singleton Value is needed for split_thru_phi optimization. 2499 int con = value->get_int(); 2500 return TypeInt::make(con & 0xFF); 2501 } 2502 return LoadNode::Value(phase); 2503 } 2504 2505 //--------------------------LoadUSNode::Ideal------------------------------------- 2506 // 2507 // If the previous store is to the same address as this load, 2508 // and the value stored was larger than a char, replace this load 2509 // with the value stored truncated to a char. If no truncation is 2510 // needed, the replacement is done in LoadNode::Identity(). 2511 // 2512 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2513 Node* mem = in(MemNode::Memory); 2514 Node* value = can_see_stored_value(mem,phase); 2515 if (value != nullptr) { 2516 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false); 2517 if (narrow != value) { 2518 return narrow; 2519 } 2520 } 2521 // Identity call will handle the case where truncation is not needed. 2522 return LoadNode::Ideal(phase, can_reshape); 2523 } 2524 2525 const Type* LoadUSNode::Value(PhaseGVN* phase) const { 2526 Node* mem = in(MemNode::Memory); 2527 Node* value = can_see_stored_value(mem,phase); 2528 if (value != nullptr && value->is_Con() && 2529 !value->bottom_type()->higher_equal(_type)) { 2530 // If the input to the store does not fit with the load's result type, 2531 // it must be truncated. We can't delay until Ideal call since 2532 // a singleton Value is needed for split_thru_phi optimization. 2533 int con = value->get_int(); 2534 return TypeInt::make(con & 0xFFFF); 2535 } 2536 return LoadNode::Value(phase); 2537 } 2538 2539 //--------------------------LoadSNode::Ideal-------------------------------------- 2540 // 2541 // If the previous store is to the same address as this load, 2542 // and the value stored was larger than a short, replace this load 2543 // with the value stored truncated to a short. If no truncation is 2544 // needed, the replacement is done in LoadNode::Identity(). 2545 // 2546 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2547 Node* mem = in(MemNode::Memory); 2548 Node* value = can_see_stored_value(mem,phase); 2549 if (value != nullptr) { 2550 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false); 2551 if (narrow != value) { 2552 return narrow; 2553 } 2554 } 2555 // Identity call will handle the case where truncation is not needed. 2556 return LoadNode::Ideal(phase, can_reshape); 2557 } 2558 2559 const Type* LoadSNode::Value(PhaseGVN* phase) const { 2560 Node* mem = in(MemNode::Memory); 2561 Node* value = can_see_stored_value(mem,phase); 2562 if (value != nullptr && value->is_Con() && 2563 !value->bottom_type()->higher_equal(_type)) { 2564 // If the input to the store does not fit with the load's result type, 2565 // it must be truncated. We can't delay until Ideal call since 2566 // a singleton Value is needed for split_thru_phi optimization. 2567 int con = value->get_int(); 2568 return TypeInt::make((con << 16) >> 16); 2569 } 2570 return LoadNode::Value(phase); 2571 } 2572 2573 Node* LoadNNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2574 // Loading from an InlineType, find the input and make an EncodeP 2575 Node* addr = in(Address); 2576 intptr_t offset; 2577 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset); 2578 Node* value = see_through_inline_type(phase, this, base, offset); 2579 if (value != nullptr) { 2580 return new EncodePNode(value, type()); 2581 } 2582 2583 return LoadNode::Ideal(phase, can_reshape); 2584 } 2585 2586 //============================================================================= 2587 //----------------------------LoadKlassNode::make------------------------------ 2588 // Polymorphic factory method: 2589 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2590 // sanity check the alias category against the created node type 2591 const TypePtr* adr_type = adr->bottom_type()->isa_ptr(); 2592 assert(adr_type != nullptr, "expecting TypeKlassPtr"); 2593 #ifdef _LP64 2594 if (adr_type->is_ptr_to_narrowklass()) { 2595 assert(UseCompressedClassPointers, "no compressed klasses"); 2596 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2597 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2598 } 2599 #endif 2600 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2601 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered); 2602 } 2603 2604 //------------------------------Value------------------------------------------ 2605 const Type* LoadKlassNode::Value(PhaseGVN* phase) const { 2606 return klass_value_common(phase); 2607 } 2608 2609 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const { 2610 // Either input is TOP ==> the result is TOP 2611 const Type *t1 = phase->type( in(MemNode::Memory) ); 2612 if (t1 == Type::TOP) return Type::TOP; 2613 Node *adr = in(MemNode::Address); 2614 const Type *t2 = phase->type( adr ); 2615 if (t2 == Type::TOP) return Type::TOP; 2616 const TypePtr *tp = t2->is_ptr(); 2617 if (TypePtr::above_centerline(tp->ptr()) || 2618 tp->ptr() == TypePtr::Null) return Type::TOP; 2619 2620 // Return a more precise klass, if possible 2621 const TypeInstPtr *tinst = tp->isa_instptr(); 2622 if (tinst != nullptr) { 2623 ciInstanceKlass* ik = tinst->instance_klass(); 2624 int offset = tinst->offset(); 2625 if (ik == phase->C->env()->Class_klass() 2626 && (offset == java_lang_Class::klass_offset() || 2627 offset == java_lang_Class::array_klass_offset())) { 2628 // We are loading a special hidden field from a Class mirror object, 2629 // the field which points to the VM's Klass metaobject. 2630 ciType* t = tinst->java_mirror_type(); 2631 // java_mirror_type returns non-null for compile-time Class constants. 2632 if (t != nullptr) { 2633 // constant oop => constant klass 2634 if (offset == java_lang_Class::array_klass_offset()) { 2635 if (t->is_void()) { 2636 // We cannot create a void array. Since void is a primitive type return null 2637 // klass. Users of this result need to do a null check on the returned klass. 2638 return TypePtr::NULL_PTR; 2639 } 2640 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces); 2641 } 2642 if (!t->is_klass()) { 2643 // a primitive Class (e.g., int.class) has null for a klass field 2644 return TypePtr::NULL_PTR; 2645 } 2646 // Fold up the load of the hidden field 2647 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces); 2648 } 2649 // non-constant mirror, so we can't tell what's going on 2650 } 2651 if (!tinst->is_loaded()) 2652 return _type; // Bail out if not loaded 2653 if (offset == oopDesc::klass_offset_in_bytes()) { 2654 return tinst->as_klass_type(true); 2655 } 2656 } 2657 2658 // Check for loading klass from an array 2659 const TypeAryPtr* tary = tp->isa_aryptr(); 2660 if (tary != nullptr && 2661 tary->offset() == oopDesc::klass_offset_in_bytes()) { 2662 return tary->as_klass_type(true); 2663 } 2664 2665 // Check for loading klass from an array klass 2666 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2667 if (tkls != nullptr && !StressReflectiveCode) { 2668 if (!tkls->is_loaded()) 2669 return _type; // Bail out if not loaded 2670 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() && 2671 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2672 // // Always returning precise element type is incorrect, 2673 // // e.g., element type could be object and array may contain strings 2674 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2675 2676 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2677 // according to the element type's subclassing. 2678 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact()); 2679 } 2680 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() && 2681 tkls->offset() == in_bytes(Klass::super_offset())) { 2682 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super(); 2683 // The field is Klass::_super. Return its (constant) value. 2684 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2685 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR; 2686 } 2687 } 2688 2689 if (tkls != nullptr && !UseSecondarySupersCache 2690 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) { 2691 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled. 2692 return TypePtr::NULL_PTR; 2693 } 2694 2695 // Bailout case 2696 return LoadNode::Value(phase); 2697 } 2698 2699 //------------------------------Identity--------------------------------------- 2700 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2701 // Also feed through the klass in Allocate(...klass...)._klass. 2702 Node* LoadKlassNode::Identity(PhaseGVN* phase) { 2703 return klass_identity_common(phase); 2704 } 2705 2706 Node* LoadNode::klass_identity_common(PhaseGVN* phase) { 2707 Node* x = LoadNode::Identity(phase); 2708 if (x != this) return x; 2709 2710 // Take apart the address into an oop and offset. 2711 // Return 'this' if we cannot. 2712 Node* adr = in(MemNode::Address); 2713 intptr_t offset = 0; 2714 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2715 if (base == nullptr) return this; 2716 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2717 if (toop == nullptr) return this; 2718 2719 // Step over potential GC barrier for OopHandle resolve 2720 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 2721 if (bs->is_gc_barrier_node(base)) { 2722 base = bs->step_over_gc_barrier(base); 2723 } 2724 2725 // We can fetch the klass directly through an AllocateNode. 2726 // This works even if the klass is not constant (clone or newArray). 2727 if (offset == oopDesc::klass_offset_in_bytes()) { 2728 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2729 if (allocated_klass != nullptr) { 2730 return allocated_klass; 2731 } 2732 } 2733 2734 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2735 // See inline_native_Class_query for occurrences of these patterns. 2736 // Java Example: x.getClass().isAssignableFrom(y) 2737 // 2738 // This improves reflective code, often making the Class 2739 // mirror go completely dead. (Current exception: Class 2740 // mirrors may appear in debug info, but we could clean them out by 2741 // introducing a new debug info operator for Klass.java_mirror). 2742 2743 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass() 2744 && offset == java_lang_Class::klass_offset()) { 2745 if (base->is_Load()) { 2746 Node* base2 = base->in(MemNode::Address); 2747 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */ 2748 Node* adr2 = base2->in(MemNode::Address); 2749 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2750 // TODO 8366668 Re-enable this for arrays 2751 if (tkls != nullptr && !tkls->empty() 2752 && ((tkls->isa_instklassptr() && !tkls->is_instklassptr()->might_be_an_array()) || (tkls->isa_aryklassptr() && false)) 2753 && adr2->is_AddP() 2754 ) { 2755 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2756 if (tkls->offset() == mirror_field) { 2757 return adr2->in(AddPNode::Base); 2758 } 2759 } 2760 } 2761 } 2762 } 2763 2764 return this; 2765 } 2766 2767 LoadNode* LoadNode::clone_pinned() const { 2768 LoadNode* ld = clone()->as_Load(); 2769 ld->_control_dependency = UnknownControl; 2770 return ld; 2771 } 2772 2773 2774 //------------------------------Value------------------------------------------ 2775 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const { 2776 const Type *t = klass_value_common(phase); 2777 if (t == Type::TOP) 2778 return t; 2779 2780 return t->make_narrowklass(); 2781 } 2782 2783 //------------------------------Identity--------------------------------------- 2784 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2785 // Also feed through the klass in Allocate(...klass...)._klass. 2786 Node* LoadNKlassNode::Identity(PhaseGVN* phase) { 2787 Node *x = klass_identity_common(phase); 2788 2789 const Type *t = phase->type( x ); 2790 if( t == Type::TOP ) return x; 2791 if( t->isa_narrowklass()) return x; 2792 assert (!t->isa_narrowoop(), "no narrow oop here"); 2793 2794 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2795 } 2796 2797 //------------------------------Value----------------------------------------- 2798 const Type* LoadRangeNode::Value(PhaseGVN* phase) const { 2799 // Either input is TOP ==> the result is TOP 2800 const Type *t1 = phase->type( in(MemNode::Memory) ); 2801 if( t1 == Type::TOP ) return Type::TOP; 2802 Node *adr = in(MemNode::Address); 2803 const Type *t2 = phase->type( adr ); 2804 if( t2 == Type::TOP ) return Type::TOP; 2805 const TypePtr *tp = t2->is_ptr(); 2806 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2807 const TypeAryPtr *tap = tp->isa_aryptr(); 2808 if( !tap ) return _type; 2809 return tap->size(); 2810 } 2811 2812 //-------------------------------Ideal--------------------------------------- 2813 // Feed through the length in AllocateArray(...length...)._length. 2814 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2815 Node* p = MemNode::Ideal_common(phase, can_reshape); 2816 if (p) return (p == NodeSentinel) ? nullptr : p; 2817 2818 // Take apart the address into an oop and offset. 2819 // Return 'this' if we cannot. 2820 Node* adr = in(MemNode::Address); 2821 intptr_t offset = 0; 2822 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2823 if (base == nullptr) return nullptr; 2824 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2825 if (tary == nullptr) return nullptr; 2826 2827 // We can fetch the length directly through an AllocateArrayNode. 2828 // This works even if the length is not constant (clone or newArray). 2829 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2830 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base); 2831 if (alloc != nullptr) { 2832 Node* allocated_length = alloc->Ideal_length(); 2833 Node* len = alloc->make_ideal_length(tary, phase); 2834 if (allocated_length != len) { 2835 // New CastII improves on this. 2836 return len; 2837 } 2838 } 2839 } 2840 2841 return nullptr; 2842 } 2843 2844 //------------------------------Identity--------------------------------------- 2845 // Feed through the length in AllocateArray(...length...)._length. 2846 Node* LoadRangeNode::Identity(PhaseGVN* phase) { 2847 Node* x = LoadINode::Identity(phase); 2848 if (x != this) return x; 2849 2850 // Take apart the address into an oop and offset. 2851 // Return 'this' if we cannot. 2852 Node* adr = in(MemNode::Address); 2853 intptr_t offset = 0; 2854 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2855 if (base == nullptr) return this; 2856 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2857 if (tary == nullptr) return this; 2858 2859 // We can fetch the length directly through an AllocateArrayNode. 2860 // This works even if the length is not constant (clone or newArray). 2861 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2862 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base); 2863 if (alloc != nullptr) { 2864 Node* allocated_length = alloc->Ideal_length(); 2865 // Do not allow make_ideal_length to allocate a CastII node. 2866 Node* len = alloc->make_ideal_length(tary, phase, false); 2867 if (allocated_length == len) { 2868 // Return allocated_length only if it would not be improved by a CastII. 2869 return allocated_length; 2870 } 2871 } 2872 } 2873 2874 return this; 2875 2876 } 2877 2878 //============================================================================= 2879 //---------------------------StoreNode::make----------------------------------- 2880 // Polymorphic factory method: 2881 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo, bool require_atomic_access) { 2882 assert((mo == unordered || mo == release), "unexpected"); 2883 Compile* C = gvn.C; 2884 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2885 ctl != nullptr, "raw memory operations should have control edge"); 2886 2887 switch (bt) { 2888 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case 2889 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2890 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2891 case T_CHAR: 2892 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2893 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access); 2894 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2895 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access); 2896 case T_METADATA: 2897 case T_ADDRESS: 2898 case T_OBJECT: 2899 #ifdef _LP64 2900 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2901 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2902 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2903 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2904 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2905 adr->bottom_type()->isa_rawptr())) { 2906 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2907 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2908 } 2909 #endif 2910 { 2911 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2912 } 2913 default: 2914 ShouldNotReachHere(); 2915 return (StoreNode*)nullptr; 2916 } 2917 } 2918 2919 //--------------------------bottom_type---------------------------------------- 2920 const Type *StoreNode::bottom_type() const { 2921 return Type::MEMORY; 2922 } 2923 2924 //------------------------------hash------------------------------------------- 2925 uint StoreNode::hash() const { 2926 // unroll addition of interesting fields 2927 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2928 2929 // Since they are not commoned, do not hash them: 2930 return NO_HASH; 2931 } 2932 2933 // Link together multiple stores (B/S/C/I) into a longer one. 2934 // 2935 // Example: _store = StoreB[i+3] 2936 // 2937 // RangeCheck[i+0] RangeCheck[i+0] 2938 // StoreB[i+0] 2939 // RangeCheck[i+3] RangeCheck[i+3] 2940 // StoreB[i+1] --> pass: fail: 2941 // StoreB[i+2] StoreI[i+0] StoreB[i+0] 2942 // StoreB[i+3] 2943 // 2944 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before 2945 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After 2946 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the 2947 // failing path. 2948 // 2949 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with: 2950 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop, 2951 // and possibly no RangeChecks remain between the stores. 2952 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks, 2953 // and those later RangeChecks can be removed. Example: 2954 // 2955 // RangeCheck[i+0] RangeCheck[i+0] <- before first store 2956 // StoreB[i+0] StoreB[i+0] <- first store 2957 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store 2958 // StoreB[i+1] StoreB[i+1] <- second store 2959 // RangeCheck[i+2] --> removed 2960 // StoreB[i+2] StoreB[i+2] 2961 // RangeCheck[i+3] --> removed 2962 // StoreB[i+3] StoreB[i+3] <- last store 2963 // 2964 // Thus, it is a common pattern that between the first and last store in a chain 2965 // of adjacent stores there remains exactly one RangeCheck, located between the 2966 // first and the second store (e.g. RangeCheck[i+3]). 2967 // 2968 class MergePrimitiveStores : public StackObj { 2969 private: 2970 PhaseGVN* const _phase; 2971 StoreNode* const _store; 2972 // State machine with initial state Unknown 2973 // Allowed transitions: 2974 // Unknown -> Const 2975 // Unknown -> Platform 2976 // Unknown -> Reverse 2977 // Unknown -> NotAdjacent 2978 // Const -> Const 2979 // Const -> NotAdjacent 2980 // Platform -> Platform 2981 // Platform -> NotAdjacent 2982 // Reverse -> Reverse 2983 // Reverse -> NotAdjacent 2984 // NotAdjacent -> NotAdjacent 2985 enum ValueOrder : uint8_t { 2986 Unknown, // Initial state 2987 Const, // Input values are const 2988 Platform, // Platform order 2989 Reverse, // Reverse platform order 2990 NotAdjacent // Not adjacent 2991 }; 2992 ValueOrder _value_order; 2993 2994 NOT_PRODUCT( const CHeapBitMap &_trace_tags; ) 2995 2996 public: 2997 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) : 2998 _phase(phase), _store(store), _value_order(ValueOrder::Unknown) 2999 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) ) 3000 {} 3001 3002 StoreNode* run(); 3003 3004 private: 3005 bool is_compatible_store(const StoreNode* other_store) const; 3006 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const; 3007 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const; 3008 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase); 3009 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure }; 3010 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store); 3011 3012 class Status { 3013 private: 3014 StoreNode* _found_store; 3015 bool _found_range_check; 3016 3017 Status(StoreNode* found_store, bool found_range_check) 3018 : _found_store(found_store), _found_range_check(found_range_check) {} 3019 3020 public: 3021 StoreNode* found_store() const { return _found_store; } 3022 bool found_range_check() const { return _found_range_check; } 3023 static Status make_failure() { return Status(nullptr, false); } 3024 3025 static Status make(StoreNode* found_store, const CFGStatus cfg_status) { 3026 if (cfg_status == CFGStatus::Failure) { 3027 return Status::make_failure(); 3028 } 3029 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck); 3030 } 3031 3032 #ifndef PRODUCT 3033 void print_on(outputStream* st) const { 3034 if (_found_store == nullptr) { 3035 st->print_cr("None"); 3036 } else { 3037 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(), 3038 _found_range_check ? "RC" : "no-RC"); 3039 } 3040 } 3041 #endif 3042 }; 3043 3044 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const; 3045 Status find_adjacent_use_store(const StoreNode* def_store) const; 3046 Status find_adjacent_def_store(const StoreNode* use_store) const; 3047 Status find_use_store(const StoreNode* def_store) const; 3048 Status find_def_store(const StoreNode* use_store) const; 3049 Status find_use_store_unidirectional(const StoreNode* def_store) const; 3050 Status find_def_store_unidirectional(const StoreNode* use_store) const; 3051 3052 void collect_merge_list(Node_List& merge_list) const; 3053 Node* make_merged_input_value(const Node_List& merge_list); 3054 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value); 3055 3056 #ifndef PRODUCT 3057 // Access to TraceMergeStores tags 3058 bool is_trace(TraceMergeStores::Tag tag) const { 3059 return _trace_tags.at(tag); 3060 } 3061 3062 bool is_trace_basic() const { 3063 return is_trace(TraceMergeStores::Tag::BASIC); 3064 } 3065 3066 bool is_trace_pointer_parsing() const { 3067 return is_trace(TraceMergeStores::Tag::POINTER_PARSING); 3068 } 3069 3070 bool is_trace_pointer_aliasing() const { 3071 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING); 3072 } 3073 3074 bool is_trace_pointer_adjacency() const { 3075 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY); 3076 } 3077 3078 bool is_trace_success() const { 3079 return is_trace(TraceMergeStores::Tag::SUCCESS); 3080 } 3081 #endif 3082 3083 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; ) 3084 }; 3085 3086 StoreNode* MergePrimitiveStores::run() { 3087 // Check for B/S/C/I 3088 int opc = _store->Opcode(); 3089 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) { 3090 return nullptr; 3091 } 3092 3093 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); }) 3094 3095 // The _store must be the "last" store in a chain. If we find a use we could merge with 3096 // then that use or a store further down is the "last" store. 3097 Status status_use = find_adjacent_use_store(_store); 3098 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); }) 3099 if (status_use.found_store() != nullptr) { 3100 return nullptr; 3101 } 3102 3103 // Check if we can merge with at least one def, so that we have at least 2 stores to merge. 3104 Status status_def = find_adjacent_def_store(_store); 3105 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); }) 3106 Node* def_store = status_def.found_store(); 3107 if (def_store == nullptr) { 3108 return nullptr; 3109 } 3110 3111 // Initialize value order 3112 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn), 3113 _store->in(MemNode::ValueIn), 3114 _store->memory_size()); 3115 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked"); 3116 3117 ResourceMark rm; 3118 Node_List merge_list; 3119 collect_merge_list(merge_list); 3120 3121 Node* merged_input_value = make_merged_input_value(merge_list); 3122 if (merged_input_value == nullptr) { return nullptr; } 3123 3124 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value); 3125 3126 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } ) 3127 3128 return merged_store; 3129 } 3130 3131 // Check compatibility between _store and other_store. 3132 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const { 3133 int opc = _store->Opcode(); 3134 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition"); 3135 3136 if (other_store == nullptr || 3137 _store->Opcode() != other_store->Opcode()) { 3138 return false; 3139 } 3140 3141 return true; 3142 } 3143 3144 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const { 3145 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn), 3146 use_store->in(MemNode::ValueIn), 3147 def_store->memory_size())) { 3148 return false; 3149 } 3150 3151 ResourceMark rm; 3152 #ifndef PRODUCT 3153 const TraceMemPointer trace(is_trace_pointer_parsing(), 3154 is_trace_pointer_aliasing(), 3155 is_trace_pointer_adjacency(), 3156 true); 3157 #endif 3158 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace)); 3159 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace)); 3160 return pointer_def.is_adjacent_to_and_before(pointer_use); 3161 } 3162 3163 // Check input values n1 and n2 can be merged and return the value order 3164 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2, 3165 const int memory_size) const { 3166 // Pattern: [n1 = ConI, n2 = ConI] 3167 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) { 3168 return ValueOrder::Const; 3169 } 3170 3171 Node const *base_n2; 3172 jint shift_n2; 3173 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) { 3174 return ValueOrder::NotAdjacent; 3175 } 3176 Node const *base_n1; 3177 jint shift_n1; 3178 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) { 3179 return ValueOrder::NotAdjacent; 3180 } 3181 3182 int bits_per_store = memory_size * 8; 3183 if (base_n1 != base_n2 || 3184 abs(shift_n1 - shift_n2) != bits_per_store || 3185 shift_n1 % bits_per_store != 0) { 3186 // Values are not adjacent 3187 return ValueOrder::NotAdjacent; 3188 } 3189 3190 // Detect value order 3191 #ifdef VM_LITTLE_ENDIAN 3192 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)] 3193 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift] 3194 #else 3195 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift] 3196 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)] 3197 #endif 3198 } 3199 3200 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const { 3201 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size); 3202 3203 switch (input_value_order) { 3204 case ValueOrder::NotAdjacent: 3205 return false; 3206 case ValueOrder::Reverse: 3207 if (memory_size != 1 || 3208 !Matcher::match_rule_supported(Op_ReverseBytesS) || 3209 !Matcher::match_rule_supported(Op_ReverseBytesI) || 3210 !Matcher::match_rule_supported(Op_ReverseBytesL)) { 3211 // ReverseBytes are not supported by platform 3212 return false; 3213 } 3214 // fall-through. 3215 case ValueOrder::Const: 3216 case ValueOrder::Platform: 3217 if (_value_order == ValueOrder::Unknown) { 3218 // Initial state is Unknown, and we find a valid input value order 3219 return true; 3220 } 3221 // The value order can not be changed 3222 return _value_order == input_value_order; 3223 case ValueOrder::Unknown: 3224 default: 3225 ShouldNotReachHere(); 3226 } 3227 return false; 3228 } 3229 3230 // Detect pattern: n = base_out >> shift_out 3231 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) { 3232 assert(n != nullptr, "precondition"); 3233 3234 int opc = n->Opcode(); 3235 if (opc == Op_ConvL2I) { 3236 n = n->in(1); 3237 opc = n->Opcode(); 3238 } 3239 3240 if ((opc == Op_RShiftI || 3241 opc == Op_RShiftL || 3242 opc == Op_URShiftI || 3243 opc == Op_URShiftL) && 3244 n->in(2)->is_ConI()) { 3245 base_out = n->in(1); 3246 shift_out = n->in(2)->get_int(); 3247 // The shift must be positive: 3248 return shift_out >= 0; 3249 } 3250 3251 if (phase->type(n)->isa_int() != nullptr || 3252 phase->type(n)->isa_long() != nullptr) { 3253 // (base >> 0) 3254 base_out = n; 3255 shift_out = 0; 3256 return true; 3257 } 3258 return false; 3259 } 3260 3261 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap. 3262 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) { 3263 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship"); 3264 3265 Node* ctrl_use = use_store->in(MemNode::Control); 3266 Node* ctrl_def = def_store->in(MemNode::Control); 3267 if (ctrl_use == nullptr || ctrl_def == nullptr) { 3268 return CFGStatus::Failure; 3269 } 3270 3271 if (ctrl_use == ctrl_def) { 3272 // Same ctrl -> no RangeCheck in between. 3273 // Check: use_store must be the only use of def_store. 3274 if (def_store->outcnt() > 1) { 3275 return CFGStatus::Failure; 3276 } 3277 return CFGStatus::SuccessNoRangeCheck; 3278 } 3279 3280 // Different ctrl -> could have RangeCheck in between. 3281 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and 3282 // 2. ctrl separated by RangeCheck. 3283 if (def_store->outcnt() != 2) { 3284 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap. 3285 } 3286 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1; 3287 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem(); 3288 if (merge_mem == nullptr || 3289 merge_mem->outcnt() != 1) { 3290 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap. 3291 } 3292 if (!ctrl_use->is_IfProj() || 3293 !ctrl_use->in(0)->is_RangeCheck() || 3294 ctrl_use->in(0)->outcnt() != 2) { 3295 return CFGStatus::Failure; // Not RangeCheck. 3296 } 3297 ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj(); 3298 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check); 3299 if (trap != merge_mem->unique_out() || 3300 ctrl_use->in(0)->in(0) != ctrl_def) { 3301 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap. 3302 } 3303 3304 return CFGStatus::SuccessWithRangeCheck; 3305 } 3306 3307 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const { 3308 Status status_use = find_use_store(def_store); 3309 StoreNode* use_store = status_use.found_store(); 3310 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) { 3311 return Status::make_failure(); 3312 } 3313 return status_use; 3314 } 3315 3316 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const { 3317 Status status_def = find_def_store(use_store); 3318 StoreNode* def_store = status_def.found_store(); 3319 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) { 3320 return Status::make_failure(); 3321 } 3322 return status_def; 3323 } 3324 3325 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const { 3326 Status status_use = find_use_store_unidirectional(def_store); 3327 3328 #ifdef ASSERT 3329 StoreNode* use_store = status_use.found_store(); 3330 if (use_store != nullptr) { 3331 Status status_def = find_def_store_unidirectional(use_store); 3332 assert(status_def.found_store() == def_store && 3333 status_def.found_range_check() == status_use.found_range_check(), 3334 "find_use_store and find_def_store must be symmetric"); 3335 } 3336 #endif 3337 3338 return status_use; 3339 } 3340 3341 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const { 3342 Status status_def = find_def_store_unidirectional(use_store); 3343 3344 #ifdef ASSERT 3345 StoreNode* def_store = status_def.found_store(); 3346 if (def_store != nullptr) { 3347 Status status_use = find_use_store_unidirectional(def_store); 3348 assert(status_use.found_store() == use_store && 3349 status_use.found_range_check() == status_def.found_range_check(), 3350 "find_use_store and find_def_store must be symmetric"); 3351 } 3352 #endif 3353 3354 return status_def; 3355 } 3356 3357 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const { 3358 assert(is_compatible_store(def_store), "precondition: must be compatible with _store"); 3359 3360 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) { 3361 StoreNode* use_store = def_store->fast_out(i)->isa_Store(); 3362 if (is_compatible_store(use_store)) { 3363 return Status::make(use_store, cfg_status_for_pair(use_store, def_store)); 3364 } 3365 } 3366 3367 return Status::make_failure(); 3368 } 3369 3370 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const { 3371 assert(is_compatible_store(use_store), "precondition: must be compatible with _store"); 3372 3373 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store(); 3374 if (!is_compatible_store(def_store)) { 3375 return Status::make_failure(); 3376 } 3377 3378 return Status::make(def_store, cfg_status_for_pair(use_store, def_store)); 3379 } 3380 3381 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const { 3382 // The merged store can be at most 8 bytes. 3383 const uint merge_list_max_size = 8 / _store->memory_size(); 3384 assert(merge_list_max_size >= 2 && 3385 merge_list_max_size <= 8 && 3386 is_power_of_2(merge_list_max_size), 3387 "must be 2, 4 or 8"); 3388 3389 // Traverse up the chain of adjacent def stores. 3390 StoreNode* current = _store; 3391 merge_list.push(current); 3392 while (current != nullptr && merge_list.size() < merge_list_max_size) { 3393 Status status = find_adjacent_def_store(current); 3394 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); }) 3395 3396 current = status.found_store(); 3397 if (current != nullptr) { 3398 merge_list.push(current); 3399 3400 // We can have at most one RangeCheck. 3401 if (status.found_range_check()) { 3402 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); }) 3403 break; 3404 } 3405 } 3406 } 3407 3408 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); }) 3409 3410 // Truncate the merge_list to a power of 2. 3411 const uint pow2size = round_down_power_of_2(merge_list.size()); 3412 assert(pow2size >= 2, "must be merging at least 2 stores"); 3413 while (merge_list.size() > pow2size) { merge_list.pop(); } 3414 3415 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); }) 3416 } 3417 3418 // Merge the input values of the smaller stores to a single larger input value. 3419 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) { 3420 int new_memory_size = _store->memory_size() * merge_list.size(); 3421 Node* first = merge_list.at(merge_list.size()-1); 3422 Node* merged_input_value = nullptr; 3423 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) { 3424 assert(_value_order == ValueOrder::Const, "must match"); 3425 // Pattern: [ConI, ConI, ...] -> new constant 3426 jlong con = 0; 3427 jlong bits_per_store = _store->memory_size() * 8; 3428 jlong mask = (((jlong)1) << bits_per_store) - 1; 3429 for (uint i = 0; i < merge_list.size(); i++) { 3430 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int(); 3431 #ifdef VM_LITTLE_ENDIAN 3432 con = con << bits_per_store; 3433 con = con | (mask & con_i); 3434 #else // VM_LITTLE_ENDIAN 3435 con_i = (mask & con_i) << (i * bits_per_store); 3436 con = con | con_i; 3437 #endif // VM_LITTLE_ENDIAN 3438 } 3439 merged_input_value = _phase->longcon(con); 3440 } else { 3441 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match"); 3442 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base 3443 // | | 3444 // _store first 3445 // 3446 Node* hi = _store->in(MemNode::ValueIn); 3447 Node* lo = first->in(MemNode::ValueIn); 3448 #ifndef VM_LITTLE_ENDIAN 3449 // `_store` and `first` are swapped in the diagram above 3450 swap(hi, lo); 3451 #endif // !VM_LITTLE_ENDIAN 3452 if (_value_order == ValueOrder::Reverse) { 3453 swap(hi, lo); 3454 } 3455 Node const* hi_base; 3456 jint hi_shift; 3457 merged_input_value = lo; 3458 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase); 3459 assert(is_true, "must detect con RShift"); 3460 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) { 3461 // look through 3462 merged_input_value = merged_input_value->in(1); 3463 } 3464 if (merged_input_value != hi_base) { 3465 // merged_input_value is not the base 3466 return nullptr; 3467 } 3468 } 3469 3470 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) { 3471 // Example: 3472 // 3473 // long base = ...; 3474 // a[0] = (byte)(base >> 0); 3475 // a[1] = (byte)(base >> 8); 3476 // 3477 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value)); 3478 } 3479 3480 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) || 3481 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8), 3482 "merged_input_value is either int or long, and new_memory_size is small enough"); 3483 3484 if (_value_order == ValueOrder::Reverse) { 3485 assert(_store->memory_size() == 1, "only implemented for bytes"); 3486 if (new_memory_size == 8) { 3487 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value)); 3488 } else if (new_memory_size == 4) { 3489 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value)); 3490 } else { 3491 assert(new_memory_size == 2, "sanity check"); 3492 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value)); 3493 } 3494 } 3495 return merged_input_value; 3496 } 3497 3498 // // 3499 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr // 3500 // | | | | | | // 3501 // | | | | +---------------+ | // 3502 // | | | | | | | // 3503 // | | +---------+ | | +---------------+ // 3504 // | | | | | | | | // 3505 // +--------------+ | | v1 +------------------------------+ | | v1 // 3506 // | | | | | | | | | | | | // 3507 // RangeCheck first_store RangeCheck | | first_store // 3508 // | | | | | | | // 3509 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap // 3510 // | | ===> | | | // 3511 // +--------------+ | a2 v2 | | | // 3512 // | | | | | | | | // 3513 // | second_store | | | // 3514 // | | | | | [v1 v2 ... vn] // 3515 // ... ... | | | | // 3516 // | | | | | v // 3517 // +--------------+ | an vn +--------------+ | | merged_input_value // 3518 // | | | | | | | | // 3519 // last_store (= _store) merged_store // 3520 // // 3521 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) { 3522 Node* first_store = merge_list.at(merge_list.size()-1); 3523 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck 3524 Node* first_mem = first_store->in(MemNode::Memory); 3525 Node* first_adr = first_store->in(MemNode::Address); 3526 3527 const TypePtr* new_adr_type = _store->adr_type(); 3528 3529 int new_memory_size = _store->memory_size() * merge_list.size(); 3530 BasicType bt = T_ILLEGAL; 3531 switch (new_memory_size) { 3532 case 2: bt = T_SHORT; break; 3533 case 4: bt = T_INT; break; 3534 case 8: bt = T_LONG; break; 3535 } 3536 3537 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr, 3538 new_adr_type, merged_input_value, bt, MemNode::unordered); 3539 3540 // Marking the store mismatched is sufficient to prevent reordering, since array stores 3541 // are all on the same slice. Hence, we need no barriers. 3542 merged_store->set_mismatched_access(); 3543 3544 // Constants above may now also be be packed -> put candidate on worklist 3545 _phase->is_IterGVN()->_worklist.push(first_mem); 3546 3547 return merged_store; 3548 } 3549 3550 #ifndef PRODUCT 3551 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const { 3552 stringStream ss; 3553 ss.print_cr("[TraceMergeStores]: Replace"); 3554 for (int i = (int)merge_list.size() - 1; i >= 0; i--) { 3555 merge_list.at(i)->dump("\n", false, &ss); 3556 } 3557 ss.print_cr("[TraceMergeStores]: with"); 3558 merged_input_value->dump("\n", false, &ss); 3559 merged_store->dump("\n", false, &ss); 3560 tty->print("%s", ss.as_string()); 3561 } 3562 #endif 3563 3564 //------------------------------Ideal------------------------------------------ 3565 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 3566 // When a store immediately follows a relevant allocation/initialization, 3567 // try to capture it into the initialization, or hoist it above. 3568 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3569 Node* p = MemNode::Ideal_common(phase, can_reshape); 3570 if (p) return (p == NodeSentinel) ? nullptr : p; 3571 3572 Node* mem = in(MemNode::Memory); 3573 Node* address = in(MemNode::Address); 3574 Node* value = in(MemNode::ValueIn); 3575 // Back-to-back stores to same address? Fold em up. Generally 3576 // unsafe if I have intervening uses... 3577 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) { 3578 Node* st = mem; 3579 // If Store 'st' has more than one use, we cannot fold 'st' away. 3580 // For example, 'st' might be the final state at a conditional 3581 // return. Or, 'st' might be used by some node which is live at 3582 // the same time 'st' is live, which might be unschedulable. So, 3583 // require exactly ONE user until such time as we clone 'mem' for 3584 // each of 'mem's uses (thus making the exactly-1-user-rule hold 3585 // true). 3586 while (st->is_Store() && st->outcnt() == 1) { 3587 // Looking at a dead closed cycle of memory? 3588 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 3589 assert(Opcode() == st->Opcode() || 3590 st->Opcode() == Op_StoreVector || 3591 Opcode() == Op_StoreVector || 3592 st->Opcode() == Op_StoreVectorScatter || 3593 Opcode() == Op_StoreVectorScatter || 3594 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw || 3595 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode 3596 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy 3597 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) || 3598 (st->adr_type()->isa_aryptr() && st->adr_type()->is_aryptr()->is_flat()) || // TODO 8343835 3599 (is_mismatched_access() || st->as_Store()->is_mismatched_access()), 3600 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]); 3601 3602 if (st->in(MemNode::Address)->eqv_uncast(address) && 3603 st->as_Store()->memory_size() <= this->memory_size()) { 3604 Node* use = st->raw_out(0); 3605 if (phase->is_IterGVN()) { 3606 phase->is_IterGVN()->rehash_node_delayed(use); 3607 } 3608 // It's OK to do this in the parser, since DU info is always accurate, 3609 // and the parser always refers to nodes via SafePointNode maps. 3610 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase); 3611 return this; 3612 } 3613 st = st->in(MemNode::Memory); 3614 } 3615 } 3616 3617 3618 // Capture an unaliased, unconditional, simple store into an initializer. 3619 // Or, if it is independent of the allocation, hoist it above the allocation. 3620 if (ReduceFieldZeroing && /*can_reshape &&*/ 3621 mem->is_Proj() && mem->in(0)->is_Initialize()) { 3622 InitializeNode* init = mem->in(0)->as_Initialize(); 3623 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 3624 if (offset > 0) { 3625 Node* moved = init->capture_store(this, offset, phase, can_reshape); 3626 // If the InitializeNode captured me, it made a raw copy of me, 3627 // and I need to disappear. 3628 if (moved != nullptr) { 3629 // %%% hack to ensure that Ideal returns a new node: 3630 mem = MergeMemNode::make(mem); 3631 return mem; // fold me away 3632 } 3633 } 3634 } 3635 3636 // Fold reinterpret cast into memory operation: 3637 // StoreX mem (MoveY2X v) => StoreY mem v 3638 if (value->is_Move()) { 3639 const Type* vt = value->in(1)->bottom_type(); 3640 if (has_reinterpret_variant(vt)) { 3641 if (phase->C->post_loop_opts_phase()) { 3642 return convert_to_reinterpret_store(*phase, value->in(1), vt); 3643 } else { 3644 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over 3645 } 3646 } 3647 } 3648 3649 if (MergeStores && UseUnalignedAccesses) { 3650 if (phase->C->merge_stores_phase()) { 3651 MergePrimitiveStores merge(phase, this); 3652 Node* progress = merge.run(); 3653 if (progress != nullptr) { return progress; } 3654 } else { 3655 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during 3656 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between 3657 // the stores, and we merge the wrong sequence of stores. 3658 // Example: 3659 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI 3660 // Apply MergeStores: 3661 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI 3662 // Remove more RangeChecks: 3663 // StoreI [ StoreL ] StoreI 3664 // But now it would have been better to do this instead: 3665 // [ StoreL ] [ StoreL ] 3666 phase->C->record_for_merge_stores_igvn(this); 3667 } 3668 } 3669 3670 return nullptr; // No further progress 3671 } 3672 3673 //------------------------------Value----------------------------------------- 3674 const Type* StoreNode::Value(PhaseGVN* phase) const { 3675 // Either input is TOP ==> the result is TOP 3676 const Type *t1 = phase->type( in(MemNode::Memory) ); 3677 if( t1 == Type::TOP ) return Type::TOP; 3678 const Type *t2 = phase->type( in(MemNode::Address) ); 3679 if( t2 == Type::TOP ) return Type::TOP; 3680 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 3681 if( t3 == Type::TOP ) return Type::TOP; 3682 return Type::MEMORY; 3683 } 3684 3685 //------------------------------Identity--------------------------------------- 3686 // Remove redundant stores: 3687 // Store(m, p, Load(m, p)) changes to m. 3688 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 3689 Node* StoreNode::Identity(PhaseGVN* phase) { 3690 Node* mem = in(MemNode::Memory); 3691 Node* adr = in(MemNode::Address); 3692 Node* val = in(MemNode::ValueIn); 3693 3694 Node* result = this; 3695 3696 // Load then Store? Then the Store is useless 3697 if (val->is_Load() && 3698 val->in(MemNode::Address)->eqv_uncast(adr) && 3699 val->in(MemNode::Memory )->eqv_uncast(mem) && 3700 val->as_Load()->store_Opcode() == Opcode()) { 3701 // Ensure vector type is the same 3702 if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) { 3703 result = mem; 3704 } 3705 } 3706 3707 // Two stores in a row of the same value? 3708 if (result == this && 3709 mem->is_Store() && 3710 mem->in(MemNode::Address)->eqv_uncast(adr) && 3711 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 3712 mem->Opcode() == Opcode()) { 3713 if (!is_StoreVector()) { 3714 result = mem; 3715 } else { 3716 const StoreVectorNode* store_vector = as_StoreVector(); 3717 const StoreVectorNode* mem_vector = mem->as_StoreVector(); 3718 const Node* store_indices = store_vector->indices(); 3719 const Node* mem_indices = mem_vector->indices(); 3720 const Node* store_mask = store_vector->mask(); 3721 const Node* mem_mask = mem_vector->mask(); 3722 // Ensure types, indices, and masks match 3723 if (store_vector->vect_type() == mem_vector->vect_type() && 3724 ((store_indices == nullptr) == (mem_indices == nullptr) && 3725 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) && 3726 ((store_mask == nullptr) == (mem_mask == nullptr) && 3727 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) { 3728 result = mem; 3729 } 3730 } 3731 } 3732 3733 // Store of zero anywhere into a freshly-allocated object? 3734 // Then the store is useless. 3735 // (It must already have been captured by the InitializeNode.) 3736 if (result == this && ReduceFieldZeroing) { 3737 // a newly allocated object is already all-zeroes everywhere 3738 if (mem->is_Proj() && mem->in(0)->is_Allocate() && 3739 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::InitValue) == val)) { 3740 result = mem; 3741 } 3742 3743 if (result == this && phase->type(val)->is_zero_type()) { 3744 // the store may also apply to zero-bits in an earlier object 3745 Node* prev_mem = find_previous_store(phase); 3746 // Steps (a), (b): Walk past independent stores to find an exact match. 3747 if (prev_mem != nullptr) { 3748 Node* prev_val = can_see_stored_value(prev_mem, phase); 3749 if (prev_val != nullptr && prev_val == val) { 3750 // prev_val and val might differ by a cast; it would be good 3751 // to keep the more informative of the two. 3752 result = mem; 3753 } 3754 } 3755 } 3756 } 3757 3758 PhaseIterGVN* igvn = phase->is_IterGVN(); 3759 if (result != this && igvn != nullptr) { 3760 MemBarNode* trailing = trailing_membar(); 3761 if (trailing != nullptr) { 3762 #ifdef ASSERT 3763 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr(); 3764 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects"); 3765 #endif 3766 trailing->remove(igvn); 3767 } 3768 } 3769 3770 return result; 3771 } 3772 3773 //------------------------------match_edge------------------------------------- 3774 // Do we Match on this edge index or not? Match only memory & value 3775 uint StoreNode::match_edge(uint idx) const { 3776 return idx == MemNode::Address || idx == MemNode::ValueIn; 3777 } 3778 3779 //------------------------------cmp-------------------------------------------- 3780 // Do not common stores up together. They generally have to be split 3781 // back up anyways, so do not bother. 3782 bool StoreNode::cmp( const Node &n ) const { 3783 return (&n == this); // Always fail except on self 3784 } 3785 3786 //------------------------------Ideal_masked_input----------------------------- 3787 // Check for a useless mask before a partial-word store 3788 // (StoreB ... (AndI valIn conIa) ) 3789 // If (conIa & mask == mask) this simplifies to 3790 // (StoreB ... (valIn) ) 3791 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 3792 Node *val = in(MemNode::ValueIn); 3793 if( val->Opcode() == Op_AndI ) { 3794 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 3795 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 3796 set_req_X(MemNode::ValueIn, val->in(1), phase); 3797 return this; 3798 } 3799 } 3800 return nullptr; 3801 } 3802 3803 3804 //------------------------------Ideal_sign_extended_input---------------------- 3805 // Check for useless sign-extension before a partial-word store 3806 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR)) 3807 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to 3808 // (StoreB ... (v)) 3809 // If (conIL > conIR) under some conditions, it can be simplified into 3810 // (StoreB ... (LShiftI _ v (conIL - conIR))) 3811 // This case happens when the value of the store was itself a left shift, that 3812 // gets merged into the inner left shift of the sign-extension. For instance, 3813 // if we have 3814 // array_of_shorts[0] = (short)(v << 2) 3815 // We get a structure such as: 3816 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16)) 3817 // that is simplified into 3818 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)). 3819 // It is thus useful to handle cases where conIL > conIR. But this simplification 3820 // does not always hold. Let's see in which cases it's valid. 3821 // 3822 // Let's assume we have the following 32 bits integer v: 3823 // +----------------------------------+ 3824 // | v[0..31] | 3825 // +----------------------------------+ 3826 // 31 0 3827 // that will be stuffed in 8 bits byte after a shift left and a shift right of 3828 // potentially different magnitudes. 3829 // We denote num_rejected_bits the number of bits of the discarded part. In this 3830 // case, num_rejected_bits == 24. 3831 // 3832 // Statement (proved further below in case analysis): 3833 // Given: 3834 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount) 3835 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount) 3836 // - conIL >= conIR 3837 // - num_rejected_bits >= conIR 3838 // Then this form: 3839 // (RShiftI _ (LShiftI _ v conIL) conIR) 3840 // can be replaced with this form: 3841 // (LShiftI _ v (conIL-conIR)) 3842 // 3843 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte) 3844 // have to be correct, as the higher bits are rejected / truncated by the store. 3845 // 3846 // The hypotheses 3847 // 0 <= conIL < BitsPerJavaInteger 3848 // 0 <= conIR < BitsPerJavaInteger 3849 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed, 3850 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent 3851 // to v << 1). 3852 // 3853 // 3854 // If you don't like case analysis, jump after the conclusion. 3855 // ### Case 1 : conIL == conIR 3856 // ###### Case 1.1: conIL == conIR == num_rejected_bits 3857 // If we do the shift left then right by 24 bits, we get: 3858 // after: v << 24 3859 // +---------+------------------------+ 3860 // | v[0..7] | 0 | 3861 // +---------+------------------------+ 3862 // 31 24 23 0 3863 // after: (v << 24) >> 24 3864 // +------------------------+---------+ 3865 // | sign bit | v[0..7] | 3866 // +------------------------+---------+ 3867 // 31 8 7 0 3868 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the 3869 // result) are the same before and after, so, indeed, simplifying is correct. 3870 3871 // ###### Case 1.2: conIL == conIR < num_rejected_bits 3872 // If we do the shift left then right by 22 bits, we get: 3873 // after: v << 22 3874 // +---------+------------------------+ 3875 // | v[0..9] | 0 | 3876 // +---------+------------------------+ 3877 // 31 22 21 0 3878 // after: (v << 22) >> 22 3879 // +------------------------+---------+ 3880 // | sign bit | v[0..9] | 3881 // +------------------------+---------+ 3882 // 31 10 9 0 3883 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still 3884 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is 3885 // still correct. 3886 3887 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits 3888 // If we do the shift left then right by 26 bits, we get: 3889 // after: v << 26 3890 // +---------+------------------------+ 3891 // | v[0..5] | 0 | 3892 // +---------+------------------------+ 3893 // 31 26 25 0 3894 // after: (v << 26) >> 26 3895 // +------------------------+---------+ 3896 // | sign bit | v[0..5] | 3897 // +------------------------+---------+ 3898 // 31 6 5 0 3899 // The non-rejected bits are made of 3900 // - 0-5 => the bits 0 to 5 of v 3901 // - 6-7 => the sign bit of v[0..5] (that is v[5]) 3902 // Simplifying this as v is not correct. 3903 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1 3904 // 3905 // ### Case 2: conIL > conIR 3906 // ###### Case 2.1: num_rejected_bits == conIR 3907 // We take conIL == 26 for this example. 3908 // after: v << 26 3909 // +---------+------------------------+ 3910 // | v[0..5] | 0 | 3911 // +---------+------------------------+ 3912 // 31 26 25 0 3913 // after: (v << 26) >> 24 3914 // +------------------+---------+-----+ 3915 // | sign bit | v[0..5] | 0 | 3916 // +------------------+---------+-----+ 3917 // 31 8 7 2 1 0 3918 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR). 3919 // The bits 6 and 7 of v have been thrown away after the shift left. 3920 // The simplification is still correct. 3921 // 3922 // ###### Case 2.2: num_rejected_bits > conIR. 3923 // Let's say conIL == 26 and conIR == 22. 3924 // after: v << 26 3925 // +---------+------------------------+ 3926 // | v[0..5] | 0 | 3927 // +---------+------------------------+ 3928 // 31 26 25 0 3929 // after: (v << 26) >> 22 3930 // +------------------+---------+-----+ 3931 // | sign bit | v[0..5] | 0 | 3932 // +------------------+---------+-----+ 3933 // 31 10 9 4 3 0 3934 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)): 3935 // - 0-3 => 0 3936 // - 4-7 => bits 0 to 3 of v 3937 // The simplification is still correct. 3938 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't 3939 // matter as they are not in the 8 lower bits: they will be cut out by the store. 3940 // 3941 // ###### But! Case 2.3: num_rejected_bits < conIR. 3942 // Let's see that this case is not as easy to simplify. 3943 // Let's say conIL == 28 and conIR == 26. 3944 // after: v << 28 3945 // +---------+------------------------+ 3946 // | v[0..3] | 0 | 3947 // +---------+------------------------+ 3948 // 31 28 27 0 3949 // after: (v << 28) >> 26 3950 // +------------------+---------+-----+ 3951 // | sign bit | v[0..3] | 0 | 3952 // +------------------+---------+-----+ 3953 // 31 6 5 2 1 0 3954 // The non-rejected bits are made of 3955 // - 0-1 => 0 3956 // - 2-5 => the bits 0 to 3 of v 3957 // - 6-7 => the sign bit of v[0..3] (that is v[3]) 3958 // Simplifying this as (v << 2) is not correct. 3959 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2. 3960 // 3961 // ### Conclusion: 3962 // Our hypotheses are indeed sufficient: 3963 // - 0 <= conIL < BitsPerJavaInteger 3964 // - 0 <= conIR < BitsPerJavaInteger 3965 // - conIL >= conIR 3966 // - num_rejected_bits >= conIR 3967 // 3968 // ### A rationale without case analysis: 3969 // After the shift left, conIL upper bits of v are discarded and conIL lower bit 3970 // zeroes are added. After the shift right, conIR lower bits of the previous result 3971 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during 3972 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But 3973 // the point of the simplification is to get an expression of the form 3974 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the 3975 // simplification is not correct if conIL < conIR. 3976 // 3977 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the 3978 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If 3979 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will 3980 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to 3981 // (v << (conIL-conIR)) if conIR > num_rejected_bits. 3982 // 3983 // We do not treat the case conIL < conIR here since the point of this function is 3984 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need 3985 // of treating conIL > conIR comes from the cases where the sign-extended value is 3986 // also left-shift expression. Computing the sign-extension of a right-shift expression 3987 // doesn't yield a situation such as 3988 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR)) 3989 // where conIL < conIR. 3990 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) { 3991 Node* shr = in(MemNode::ValueIn); 3992 if (shr->Opcode() == Op_RShiftI) { 3993 const TypeInt* conIR = phase->type(shr->in(2))->isa_int(); 3994 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) { 3995 Node* shl = shr->in(1); 3996 if (shl->Opcode() == Op_LShiftI) { 3997 const TypeInt* conIL = phase->type(shl->in(2))->isa_int(); 3998 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) { 3999 if (conIL->get_con() == conIR->get_con()) { 4000 set_req_X(MemNode::ValueIn, shl->in(1), phase); 4001 return this; 4002 } 4003 if (conIL->get_con() > conIR->get_con()) { 4004 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con()))); 4005 set_req_X(MemNode::ValueIn, new_shl, phase); 4006 return this; 4007 } 4008 } 4009 } 4010 } 4011 } 4012 return nullptr; 4013 } 4014 4015 //------------------------------value_never_loaded----------------------------------- 4016 // Determine whether there are any possible loads of the value stored. 4017 // For simplicity, we actually check if there are any loads from the 4018 // address stored to, not just for loads of the value stored by this node. 4019 // 4020 bool StoreNode::value_never_loaded(PhaseValues* phase) const { 4021 Node *adr = in(Address); 4022 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 4023 if (adr_oop == nullptr) 4024 return false; 4025 if (!adr_oop->is_known_instance_field()) 4026 return false; // if not a distinct instance, there may be aliases of the address 4027 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 4028 Node *use = adr->fast_out(i); 4029 if (use->is_Load() || use->is_LoadStore()) { 4030 return false; 4031 } 4032 } 4033 return true; 4034 } 4035 4036 MemBarNode* StoreNode::trailing_membar() const { 4037 if (is_release()) { 4038 MemBarNode* trailing_mb = nullptr; 4039 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 4040 Node* u = fast_out(i); 4041 if (u->is_MemBar()) { 4042 if (u->as_MemBar()->trailing_store()) { 4043 assert(u->Opcode() == Op_MemBarVolatile, ""); 4044 assert(trailing_mb == nullptr, "only one"); 4045 trailing_mb = u->as_MemBar(); 4046 #ifdef ASSERT 4047 Node* leading = u->as_MemBar()->leading_membar(); 4048 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 4049 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair"); 4050 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair"); 4051 #endif 4052 } else { 4053 assert(u->as_MemBar()->standalone(), ""); 4054 } 4055 } 4056 } 4057 return trailing_mb; 4058 } 4059 return nullptr; 4060 } 4061 4062 4063 //============================================================================= 4064 //------------------------------Ideal------------------------------------------ 4065 // If the store is from an AND mask that leaves the low bits untouched, then 4066 // we can skip the AND operation. If the store is from a sign-extension 4067 // (a left shift, then right shift) we can skip both. 4068 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 4069 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 4070 if( progress != nullptr ) return progress; 4071 4072 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 4073 if( progress != nullptr ) return progress; 4074 4075 // Finally check the default case 4076 return StoreNode::Ideal(phase, can_reshape); 4077 } 4078 4079 //============================================================================= 4080 //------------------------------Ideal------------------------------------------ 4081 // If the store is from an AND mask that leaves the low bits untouched, then 4082 // we can skip the AND operation 4083 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 4084 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 4085 if( progress != nullptr ) return progress; 4086 4087 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 4088 if( progress != nullptr ) return progress; 4089 4090 // Finally check the default case 4091 return StoreNode::Ideal(phase, can_reshape); 4092 } 4093 4094 //============================================================================= 4095 //----------------------------------SCMemProjNode------------------------------ 4096 const Type* SCMemProjNode::Value(PhaseGVN* phase) const 4097 { 4098 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) { 4099 return Type::TOP; 4100 } 4101 return bottom_type(); 4102 } 4103 4104 //============================================================================= 4105 //----------------------------------LoadStoreNode------------------------------ 4106 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 4107 : Node(required), 4108 _type(rt), 4109 _adr_type(at), 4110 _barrier_data(0) 4111 { 4112 init_req(MemNode::Control, c ); 4113 init_req(MemNode::Memory , mem); 4114 init_req(MemNode::Address, adr); 4115 init_req(MemNode::ValueIn, val); 4116 init_class_id(Class_LoadStore); 4117 } 4118 4119 //------------------------------Value----------------------------------------- 4120 const Type* LoadStoreNode::Value(PhaseGVN* phase) const { 4121 // Either input is TOP ==> the result is TOP 4122 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) { 4123 return Type::TOP; 4124 } 4125 const Type* t = phase->type(in(MemNode::Memory)); 4126 if (t == Type::TOP) { 4127 return Type::TOP; 4128 } 4129 t = phase->type(in(MemNode::Address)); 4130 if (t == Type::TOP) { 4131 return Type::TOP; 4132 } 4133 t = phase->type(in(MemNode::ValueIn)); 4134 if (t == Type::TOP) { 4135 return Type::TOP; 4136 } 4137 return bottom_type(); 4138 } 4139 4140 uint LoadStoreNode::ideal_reg() const { 4141 return _type->ideal_reg(); 4142 } 4143 4144 // This method conservatively checks if the result of a LoadStoreNode is 4145 // used, that is, if it returns true, then it is definitely the case that 4146 // the result of the node is not needed. 4147 // For example, GetAndAdd can be matched into a lock_add instead of a 4148 // lock_xadd if the result of LoadStoreNode::result_not_used() is true 4149 bool LoadStoreNode::result_not_used() const { 4150 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 4151 Node *x = fast_out(i); 4152 if (x->Opcode() == Op_SCMemProj) { 4153 continue; 4154 } 4155 if (x->bottom_type() == TypeTuple::MEMBAR && 4156 !x->is_Call() && 4157 x->Opcode() != Op_Blackhole) { 4158 continue; 4159 } 4160 return false; 4161 } 4162 return true; 4163 } 4164 4165 MemBarNode* LoadStoreNode::trailing_membar() const { 4166 MemBarNode* trailing = nullptr; 4167 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 4168 Node* u = fast_out(i); 4169 if (u->is_MemBar()) { 4170 if (u->as_MemBar()->trailing_load_store()) { 4171 assert(u->Opcode() == Op_MemBarAcquire, ""); 4172 assert(trailing == nullptr, "only one"); 4173 trailing = u->as_MemBar(); 4174 #ifdef ASSERT 4175 Node* leading = trailing->leading_membar(); 4176 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 4177 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair"); 4178 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair"); 4179 #endif 4180 } else { 4181 assert(u->as_MemBar()->standalone(), "wrong barrier kind"); 4182 } 4183 } 4184 } 4185 4186 return trailing; 4187 } 4188 4189 uint LoadStoreNode::size_of() const { return sizeof(*this); } 4190 4191 //============================================================================= 4192 //----------------------------------LoadStoreConditionalNode-------------------- 4193 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) { 4194 init_req(ExpectedIn, ex ); 4195 } 4196 4197 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const { 4198 // Either input is TOP ==> the result is TOP 4199 const Type* t = phase->type(in(ExpectedIn)); 4200 if (t == Type::TOP) { 4201 return Type::TOP; 4202 } 4203 return LoadStoreNode::Value(phase); 4204 } 4205 4206 //============================================================================= 4207 //-------------------------------adr_type-------------------------------------- 4208 const TypePtr* ClearArrayNode::adr_type() const { 4209 Node *adr = in(3); 4210 if (adr == nullptr) return nullptr; // node is dead 4211 return MemNode::calculate_adr_type(adr->bottom_type()); 4212 } 4213 4214 //------------------------------match_edge------------------------------------- 4215 // Do we Match on this edge index or not? Do not match memory 4216 uint ClearArrayNode::match_edge(uint idx) const { 4217 return idx > 1; 4218 } 4219 4220 //------------------------------Identity--------------------------------------- 4221 // Clearing a zero length array does nothing 4222 Node* ClearArrayNode::Identity(PhaseGVN* phase) { 4223 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 4224 } 4225 4226 //------------------------------Idealize--------------------------------------- 4227 // Clearing a short array is faster with stores 4228 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4229 // Already know this is a large node, do not try to ideal it 4230 if (_is_large) return nullptr; 4231 4232 const int unit = BytesPerLong; 4233 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 4234 if (!t) return nullptr; 4235 if (!t->is_con()) return nullptr; 4236 intptr_t raw_count = t->get_con(); 4237 intptr_t size = raw_count; 4238 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 4239 // Clearing nothing uses the Identity call. 4240 // Negative clears are possible on dead ClearArrays 4241 // (see jck test stmt114.stmt11402.val). 4242 if (size <= 0 || size % unit != 0) return nullptr; 4243 intptr_t count = size / unit; 4244 // Length too long; communicate this to matchers and assemblers. 4245 // Assemblers are responsible to produce fast hardware clears for it. 4246 if (size > InitArrayShortSize) { 4247 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true); 4248 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) { 4249 return nullptr; 4250 } 4251 if (!IdealizeClearArrayNode) return nullptr; 4252 Node *mem = in(1); 4253 if( phase->type(mem)==Type::TOP ) return nullptr; 4254 Node *adr = in(3); 4255 const Type* at = phase->type(adr); 4256 if( at==Type::TOP ) return nullptr; 4257 const TypePtr* atp = at->isa_ptr(); 4258 // adjust atp to be the correct array element address type 4259 if (atp == nullptr) atp = TypePtr::BOTTOM; 4260 else atp = atp->add_offset(Type::OffsetBot); 4261 // Get base for derived pointer purposes 4262 if( adr->Opcode() != Op_AddP ) Unimplemented(); 4263 Node *base = adr->in(1); 4264 4265 Node *val = in(4); 4266 Node *off = phase->MakeConX(BytesPerLong); 4267 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false); 4268 count--; 4269 while( count-- ) { 4270 mem = phase->transform(mem); 4271 adr = phase->transform(new AddPNode(base,adr,off)); 4272 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false); 4273 } 4274 return mem; 4275 } 4276 4277 //----------------------------step_through---------------------------------- 4278 // Return allocation input memory edge if it is different instance 4279 // or itself if it is the one we are looking for. 4280 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) { 4281 Node* n = *np; 4282 assert(n->is_ClearArray(), "sanity"); 4283 intptr_t offset; 4284 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 4285 // This method is called only before Allocate nodes are expanded 4286 // during macro nodes expansion. Before that ClearArray nodes are 4287 // only generated in PhaseMacroExpand::generate_arraycopy() (before 4288 // Allocate nodes are expanded) which follows allocations. 4289 assert(alloc != nullptr, "should have allocation"); 4290 if (alloc->_idx == instance_id) { 4291 // Can not bypass initialization of the instance we are looking for. 4292 return false; 4293 } 4294 // Otherwise skip it. 4295 InitializeNode* init = alloc->initialization(); 4296 if (init != nullptr) 4297 *np = init->in(TypeFunc::Memory); 4298 else 4299 *np = alloc->in(TypeFunc::Memory); 4300 return true; 4301 } 4302 4303 //----------------------------clear_memory------------------------------------- 4304 // Generate code to initialize object storage to zero. 4305 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 4306 Node* val, 4307 Node* raw_val, 4308 intptr_t start_offset, 4309 Node* end_offset, 4310 PhaseGVN* phase) { 4311 intptr_t offset = start_offset; 4312 4313 int unit = BytesPerLong; 4314 if ((offset % unit) != 0) { 4315 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 4316 adr = phase->transform(adr); 4317 const TypePtr* atp = TypeRawPtr::BOTTOM; 4318 if (val != nullptr) { 4319 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop"); 4320 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered); 4321 } else { 4322 assert(raw_val == nullptr, "val may not be null"); 4323 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 4324 } 4325 mem = phase->transform(mem); 4326 offset += BytesPerInt; 4327 } 4328 assert((offset % unit) == 0, ""); 4329 4330 // Initialize the remaining stuff, if any, with a ClearArray. 4331 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase); 4332 } 4333 4334 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 4335 Node* raw_val, 4336 Node* start_offset, 4337 Node* end_offset, 4338 PhaseGVN* phase) { 4339 if (start_offset == end_offset) { 4340 // nothing to do 4341 return mem; 4342 } 4343 4344 int unit = BytesPerLong; 4345 Node* zbase = start_offset; 4346 Node* zend = end_offset; 4347 4348 // Scale to the unit required by the CPU: 4349 if (!Matcher::init_array_count_is_in_bytes) { 4350 Node* shift = phase->intcon(exact_log2(unit)); 4351 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 4352 zend = phase->transform(new URShiftXNode(zend, shift) ); 4353 } 4354 4355 // Bulk clear double-words 4356 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 4357 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 4358 if (raw_val == nullptr) { 4359 raw_val = phase->MakeConX(0); 4360 } 4361 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false); 4362 return phase->transform(mem); 4363 } 4364 4365 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 4366 Node* val, 4367 Node* raw_val, 4368 intptr_t start_offset, 4369 intptr_t end_offset, 4370 PhaseGVN* phase) { 4371 if (start_offset == end_offset) { 4372 // nothing to do 4373 return mem; 4374 } 4375 4376 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 4377 intptr_t done_offset = end_offset; 4378 if ((done_offset % BytesPerLong) != 0) { 4379 done_offset -= BytesPerInt; 4380 } 4381 if (done_offset > start_offset) { 4382 mem = clear_memory(ctl, mem, dest, val, raw_val, 4383 start_offset, phase->MakeConX(done_offset), phase); 4384 } 4385 if (done_offset < end_offset) { // emit the final 32-bit store 4386 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 4387 adr = phase->transform(adr); 4388 const TypePtr* atp = TypeRawPtr::BOTTOM; 4389 if (val != nullptr) { 4390 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop"); 4391 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered); 4392 } else { 4393 assert(raw_val == nullptr, "val may not be null"); 4394 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 4395 } 4396 mem = phase->transform(mem); 4397 done_offset += BytesPerInt; 4398 } 4399 assert(done_offset == end_offset, ""); 4400 return mem; 4401 } 4402 4403 //============================================================================= 4404 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 4405 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)), 4406 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone) 4407 #ifdef ASSERT 4408 , _pair_idx(0) 4409 #endif 4410 { 4411 init_class_id(Class_MemBar); 4412 Node* top = C->top(); 4413 init_req(TypeFunc::I_O,top); 4414 init_req(TypeFunc::FramePtr,top); 4415 init_req(TypeFunc::ReturnAdr,top); 4416 if (precedent != nullptr) 4417 init_req(TypeFunc::Parms, precedent); 4418 } 4419 4420 //------------------------------cmp-------------------------------------------- 4421 uint MemBarNode::hash() const { return NO_HASH; } 4422 bool MemBarNode::cmp( const Node &n ) const { 4423 return (&n == this); // Always fail except on self 4424 } 4425 4426 //------------------------------make------------------------------------------- 4427 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 4428 switch (opcode) { 4429 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 4430 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 4431 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 4432 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 4433 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 4434 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn); 4435 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 4436 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 4437 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 4438 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 4439 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn); 4440 case Op_Initialize: return new InitializeNode(C, atp, pn); 4441 default: ShouldNotReachHere(); return nullptr; 4442 } 4443 } 4444 4445 void MemBarNode::remove(PhaseIterGVN *igvn) { 4446 if (outcnt() != 2) { 4447 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory"); 4448 assert(outcnt() == 1, "Only control then"); 4449 } 4450 if (trailing_store() || trailing_load_store()) { 4451 MemBarNode* leading = leading_membar(); 4452 if (leading != nullptr) { 4453 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars"); 4454 leading->remove(igvn); 4455 } 4456 } 4457 if (proj_out_or_null(TypeFunc::Memory) != nullptr) { 4458 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 4459 } 4460 if (proj_out_or_null(TypeFunc::Control) != nullptr) { 4461 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 4462 } 4463 } 4464 4465 //------------------------------Ideal------------------------------------------ 4466 // Return a node which is more "ideal" than the current node. Strip out 4467 // control copies 4468 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4469 if (remove_dead_region(phase, can_reshape)) return this; 4470 // Don't bother trying to transform a dead node 4471 if (in(0) && in(0)->is_top()) { 4472 return nullptr; 4473 } 4474 4475 bool progress = false; 4476 // Eliminate volatile MemBars for scalar replaced objects. 4477 if (can_reshape && req() == (Precedent+1)) { 4478 bool eliminate = false; 4479 int opc = Opcode(); 4480 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 4481 // Volatile field loads and stores. 4482 Node* my_mem = in(MemBarNode::Precedent); 4483 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 4484 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 4485 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 4486 // replace this Precedent (decodeN) with the Load instead. 4487 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 4488 Node* load_node = my_mem->in(1); 4489 set_req(MemBarNode::Precedent, load_node); 4490 phase->is_IterGVN()->_worklist.push(my_mem); 4491 my_mem = load_node; 4492 } else { 4493 assert(my_mem->unique_out() == this, "sanity"); 4494 assert(!trailing_load_store(), "load store node can't be eliminated"); 4495 del_req(Precedent); 4496 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 4497 my_mem = nullptr; 4498 } 4499 progress = true; 4500 } 4501 if (my_mem != nullptr && my_mem->is_Mem()) { 4502 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 4503 // Check for scalar replaced object reference. 4504 if( t_oop != nullptr && t_oop->is_known_instance_field() && 4505 t_oop->offset() != Type::OffsetBot && 4506 t_oop->offset() != Type::OffsetTop) { 4507 eliminate = true; 4508 } 4509 } 4510 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) { 4511 // Final field stores. 4512 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent)); 4513 if ((alloc != nullptr) && alloc->is_Allocate() && 4514 alloc->as_Allocate()->does_not_escape_thread()) { 4515 // The allocated object does not escape. 4516 eliminate = true; 4517 } 4518 } 4519 if (eliminate) { 4520 // Replace MemBar projections by its inputs. 4521 PhaseIterGVN* igvn = phase->is_IterGVN(); 4522 remove(igvn); 4523 // Must return either the original node (now dead) or a new node 4524 // (Do not return a top here, since that would break the uniqueness of top.) 4525 return new ConINode(TypeInt::ZERO); 4526 } 4527 } 4528 return progress ? this : nullptr; 4529 } 4530 4531 //------------------------------Value------------------------------------------ 4532 const Type* MemBarNode::Value(PhaseGVN* phase) const { 4533 if( !in(0) ) return Type::TOP; 4534 if( phase->type(in(0)) == Type::TOP ) 4535 return Type::TOP; 4536 return TypeTuple::MEMBAR; 4537 } 4538 4539 //------------------------------match------------------------------------------ 4540 // Construct projections for memory. 4541 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) { 4542 switch (proj->_con) { 4543 case TypeFunc::Control: 4544 case TypeFunc::Memory: 4545 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 4546 } 4547 ShouldNotReachHere(); 4548 return nullptr; 4549 } 4550 4551 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) { 4552 trailing->_kind = TrailingStore; 4553 leading->_kind = LeadingStore; 4554 #ifdef ASSERT 4555 trailing->_pair_idx = leading->_idx; 4556 leading->_pair_idx = leading->_idx; 4557 #endif 4558 } 4559 4560 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) { 4561 trailing->_kind = TrailingLoadStore; 4562 leading->_kind = LeadingLoadStore; 4563 #ifdef ASSERT 4564 trailing->_pair_idx = leading->_idx; 4565 leading->_pair_idx = leading->_idx; 4566 #endif 4567 } 4568 4569 MemBarNode* MemBarNode::trailing_membar() const { 4570 ResourceMark rm; 4571 Node* trailing = (Node*)this; 4572 VectorSet seen; 4573 Node_Stack multis(0); 4574 do { 4575 Node* c = trailing; 4576 uint i = 0; 4577 do { 4578 trailing = nullptr; 4579 for (; i < c->outcnt(); i++) { 4580 Node* next = c->raw_out(i); 4581 if (next != c && next->is_CFG()) { 4582 if (c->is_MultiBranch()) { 4583 if (multis.node() == c) { 4584 multis.set_index(i+1); 4585 } else { 4586 multis.push(c, i+1); 4587 } 4588 } 4589 trailing = next; 4590 break; 4591 } 4592 } 4593 if (trailing != nullptr && !seen.test_set(trailing->_idx)) { 4594 break; 4595 } 4596 while (multis.size() > 0) { 4597 c = multis.node(); 4598 i = multis.index(); 4599 if (i < c->req()) { 4600 break; 4601 } 4602 multis.pop(); 4603 } 4604 } while (multis.size() > 0); 4605 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing()); 4606 4607 MemBarNode* mb = trailing->as_MemBar(); 4608 assert((mb->_kind == TrailingStore && _kind == LeadingStore) || 4609 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar"); 4610 assert(mb->_pair_idx == _pair_idx, "bad trailing membar"); 4611 return mb; 4612 } 4613 4614 MemBarNode* MemBarNode::leading_membar() const { 4615 ResourceMark rm; 4616 VectorSet seen; 4617 Node_Stack regions(0); 4618 Node* leading = in(0); 4619 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) { 4620 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) { 4621 leading = nullptr; 4622 while (regions.size() > 0 && leading == nullptr) { 4623 Node* r = regions.node(); 4624 uint i = regions.index(); 4625 if (i < r->req()) { 4626 leading = r->in(i); 4627 regions.set_index(i+1); 4628 } else { 4629 regions.pop(); 4630 } 4631 } 4632 if (leading == nullptr) { 4633 assert(regions.size() == 0, "all paths should have been tried"); 4634 return nullptr; 4635 } 4636 } 4637 if (leading->is_Region()) { 4638 regions.push(leading, 2); 4639 leading = leading->in(1); 4640 } else { 4641 leading = leading->in(0); 4642 } 4643 } 4644 #ifdef ASSERT 4645 Unique_Node_List wq; 4646 wq.push((Node*)this); 4647 uint found = 0; 4648 for (uint i = 0; i < wq.size(); i++) { 4649 Node* n = wq.at(i); 4650 if (n->is_Region()) { 4651 for (uint j = 1; j < n->req(); j++) { 4652 Node* in = n->in(j); 4653 if (in != nullptr && !in->is_top()) { 4654 wq.push(in); 4655 } 4656 } 4657 } else { 4658 if (n->is_MemBar() && n->as_MemBar()->leading()) { 4659 assert(n == leading, "consistency check failed"); 4660 found++; 4661 } else { 4662 Node* in = n->in(0); 4663 if (in != nullptr && !in->is_top()) { 4664 wq.push(in); 4665 } 4666 } 4667 } 4668 } 4669 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed"); 4670 #endif 4671 if (leading == nullptr) { 4672 return nullptr; 4673 } 4674 MemBarNode* mb = leading->as_MemBar(); 4675 assert((mb->_kind == LeadingStore && _kind == TrailingStore) || 4676 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar"); 4677 assert(mb->_pair_idx == _pair_idx, "bad leading membar"); 4678 return mb; 4679 } 4680 4681 4682 //===========================InitializeNode==================================== 4683 // SUMMARY: 4684 // This node acts as a memory barrier on raw memory, after some raw stores. 4685 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 4686 // The Initialize can 'capture' suitably constrained stores as raw inits. 4687 // It can coalesce related raw stores into larger units (called 'tiles'). 4688 // It can avoid zeroing new storage for memory units which have raw inits. 4689 // At macro-expansion, it is marked 'complete', and does not optimize further. 4690 // 4691 // EXAMPLE: 4692 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 4693 // ctl = incoming control; mem* = incoming memory 4694 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 4695 // First allocate uninitialized memory and fill in the header: 4696 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 4697 // ctl := alloc.Control; mem* := alloc.Memory* 4698 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 4699 // Then initialize to zero the non-header parts of the raw memory block: 4700 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 4701 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 4702 // After the initialize node executes, the object is ready for service: 4703 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 4704 // Suppose its body is immediately initialized as {1,2}: 4705 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 4706 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 4707 // mem.SLICE(#short[*]) := store2 4708 // 4709 // DETAILS: 4710 // An InitializeNode collects and isolates object initialization after 4711 // an AllocateNode and before the next possible safepoint. As a 4712 // memory barrier (MemBarNode), it keeps critical stores from drifting 4713 // down past any safepoint or any publication of the allocation. 4714 // Before this barrier, a newly-allocated object may have uninitialized bits. 4715 // After this barrier, it may be treated as a real oop, and GC is allowed. 4716 // 4717 // The semantics of the InitializeNode include an implicit zeroing of 4718 // the new object from object header to the end of the object. 4719 // (The object header and end are determined by the AllocateNode.) 4720 // 4721 // Certain stores may be added as direct inputs to the InitializeNode. 4722 // These stores must update raw memory, and they must be to addresses 4723 // derived from the raw address produced by AllocateNode, and with 4724 // a constant offset. They must be ordered by increasing offset. 4725 // The first one is at in(RawStores), the last at in(req()-1). 4726 // Unlike most memory operations, they are not linked in a chain, 4727 // but are displayed in parallel as users of the rawmem output of 4728 // the allocation. 4729 // 4730 // (See comments in InitializeNode::capture_store, which continue 4731 // the example given above.) 4732 // 4733 // When the associated Allocate is macro-expanded, the InitializeNode 4734 // may be rewritten to optimize collected stores. A ClearArrayNode 4735 // may also be created at that point to represent any required zeroing. 4736 // The InitializeNode is then marked 'complete', prohibiting further 4737 // capturing of nearby memory operations. 4738 // 4739 // During macro-expansion, all captured initializations which store 4740 // constant values of 32 bits or smaller are coalesced (if advantageous) 4741 // into larger 'tiles' 32 or 64 bits. This allows an object to be 4742 // initialized in fewer memory operations. Memory words which are 4743 // covered by neither tiles nor non-constant stores are pre-zeroed 4744 // by explicit stores of zero. (The code shape happens to do all 4745 // zeroing first, then all other stores, with both sequences occurring 4746 // in order of ascending offsets.) 4747 // 4748 // Alternatively, code may be inserted between an AllocateNode and its 4749 // InitializeNode, to perform arbitrary initialization of the new object. 4750 // E.g., the object copying intrinsics insert complex data transfers here. 4751 // The initialization must then be marked as 'complete' disable the 4752 // built-in zeroing semantics and the collection of initializing stores. 4753 // 4754 // While an InitializeNode is incomplete, reads from the memory state 4755 // produced by it are optimizable if they match the control edge and 4756 // new oop address associated with the allocation/initialization. 4757 // They return a stored value (if the offset matches) or else zero. 4758 // A write to the memory state, if it matches control and address, 4759 // and if it is to a constant offset, may be 'captured' by the 4760 // InitializeNode. It is cloned as a raw memory operation and rewired 4761 // inside the initialization, to the raw oop produced by the allocation. 4762 // Operations on addresses which are provably distinct (e.g., to 4763 // other AllocateNodes) are allowed to bypass the initialization. 4764 // 4765 // The effect of all this is to consolidate object initialization 4766 // (both arrays and non-arrays, both piecewise and bulk) into a 4767 // single location, where it can be optimized as a unit. 4768 // 4769 // Only stores with an offset less than TrackedInitializationLimit words 4770 // will be considered for capture by an InitializeNode. This puts a 4771 // reasonable limit on the complexity of optimized initializations. 4772 4773 //---------------------------InitializeNode------------------------------------ 4774 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 4775 : MemBarNode(C, adr_type, rawoop), 4776 _is_complete(Incomplete), _does_not_escape(false) 4777 { 4778 init_class_id(Class_Initialize); 4779 4780 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 4781 assert(in(RawAddress) == rawoop, "proper init"); 4782 // Note: allocation() can be null, for secondary initialization barriers 4783 } 4784 4785 // Since this node is not matched, it will be processed by the 4786 // register allocator. Declare that there are no constraints 4787 // on the allocation of the RawAddress edge. 4788 const RegMask &InitializeNode::in_RegMask(uint idx) const { 4789 // This edge should be set to top, by the set_complete. But be conservative. 4790 if (idx == InitializeNode::RawAddress) 4791 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 4792 return RegMask::Empty; 4793 } 4794 4795 Node* InitializeNode::memory(uint alias_idx) { 4796 Node* mem = in(Memory); 4797 if (mem->is_MergeMem()) { 4798 return mem->as_MergeMem()->memory_at(alias_idx); 4799 } else { 4800 // incoming raw memory is not split 4801 return mem; 4802 } 4803 } 4804 4805 bool InitializeNode::is_non_zero() { 4806 if (is_complete()) return false; 4807 remove_extra_zeroes(); 4808 return (req() > RawStores); 4809 } 4810 4811 void InitializeNode::set_complete(PhaseGVN* phase) { 4812 assert(!is_complete(), "caller responsibility"); 4813 _is_complete = Complete; 4814 4815 // After this node is complete, it contains a bunch of 4816 // raw-memory initializations. There is no need for 4817 // it to have anything to do with non-raw memory effects. 4818 // Therefore, tell all non-raw users to re-optimize themselves, 4819 // after skipping the memory effects of this initialization. 4820 PhaseIterGVN* igvn = phase->is_IterGVN(); 4821 if (igvn) igvn->add_users_to_worklist(this); 4822 } 4823 4824 // convenience function 4825 // return false if the init contains any stores already 4826 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 4827 InitializeNode* init = initialization(); 4828 if (init == nullptr || init->is_complete()) { 4829 return false; 4830 } 4831 init->remove_extra_zeroes(); 4832 // for now, if this allocation has already collected any inits, bail: 4833 if (init->is_non_zero()) return false; 4834 init->set_complete(phase); 4835 return true; 4836 } 4837 4838 void InitializeNode::remove_extra_zeroes() { 4839 if (req() == RawStores) return; 4840 Node* zmem = zero_memory(); 4841 uint fill = RawStores; 4842 for (uint i = fill; i < req(); i++) { 4843 Node* n = in(i); 4844 if (n->is_top() || n == zmem) continue; // skip 4845 if (fill < i) set_req(fill, n); // compact 4846 ++fill; 4847 } 4848 // delete any empty spaces created: 4849 while (fill < req()) { 4850 del_req(fill); 4851 } 4852 } 4853 4854 // Helper for remembering which stores go with which offsets. 4855 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) { 4856 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 4857 intptr_t offset = -1; 4858 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 4859 phase, offset); 4860 if (base == nullptr) return -1; // something is dead, 4861 if (offset < 0) return -1; // dead, dead 4862 return offset; 4863 } 4864 4865 // Helper for proving that an initialization expression is 4866 // "simple enough" to be folded into an object initialization. 4867 // Attempts to prove that a store's initial value 'n' can be captured 4868 // within the initialization without creating a vicious cycle, such as: 4869 // { Foo p = new Foo(); p.next = p; } 4870 // True for constants and parameters and small combinations thereof. 4871 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) { 4872 ResourceMark rm; 4873 Unique_Node_List worklist; 4874 worklist.push(value); 4875 4876 uint complexity_limit = 20; 4877 for (uint j = 0; j < worklist.size(); j++) { 4878 if (j >= complexity_limit) { 4879 return false; // Bail out if processed too many nodes 4880 } 4881 4882 Node* n = worklist.at(j); 4883 if (n == nullptr) continue; // (can this really happen?) 4884 if (n->is_Proj()) n = n->in(0); 4885 if (n == this) return false; // found a cycle 4886 if (n->is_Con()) continue; 4887 if (n->is_Start()) continue; // params, etc., are OK 4888 if (n->is_Root()) continue; // even better 4889 4890 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation 4891 if (n->is_CFG() && phase->is_dominator(n, allocation())) { 4892 continue; 4893 } 4894 4895 Node* ctl = n->in(0); 4896 if (ctl != nullptr && !ctl->is_top()) { 4897 if (ctl->is_Proj()) ctl = ctl->in(0); 4898 if (ctl == this) return false; 4899 4900 // If we already know that the enclosing memory op is pinned right after 4901 // the init, then any control flow that the store has picked up 4902 // must have preceded the init, or else be equal to the init. 4903 // Even after loop optimizations (which might change control edges) 4904 // a store is never pinned *before* the availability of its inputs. 4905 if (!MemNode::all_controls_dominate(n, this)) { 4906 return false; // failed to prove a good control 4907 } 4908 } 4909 4910 // Check data edges for possible dependencies on 'this'. 4911 for (uint i = 1; i < n->req(); i++) { 4912 Node* m = n->in(i); 4913 if (m == nullptr || m == n || m->is_top()) continue; 4914 4915 // Only process data inputs once 4916 worklist.push(m); 4917 } 4918 } 4919 4920 return true; 4921 } 4922 4923 // Here are all the checks a Store must pass before it can be moved into 4924 // an initialization. Returns zero if a check fails. 4925 // On success, returns the (constant) offset to which the store applies, 4926 // within the initialized memory. 4927 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) { 4928 const int FAIL = 0; 4929 if (st->req() != MemNode::ValueIn + 1) 4930 return FAIL; // an inscrutable StoreNode (card mark?) 4931 Node* ctl = st->in(MemNode::Control); 4932 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this)) 4933 return FAIL; // must be unconditional after the initialization 4934 Node* mem = st->in(MemNode::Memory); 4935 if (!(mem->is_Proj() && mem->in(0) == this)) 4936 return FAIL; // must not be preceded by other stores 4937 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 4938 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) && 4939 !bs->can_initialize_object(st)) { 4940 return FAIL; 4941 } 4942 Node* adr = st->in(MemNode::Address); 4943 intptr_t offset; 4944 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 4945 if (alloc == nullptr) 4946 return FAIL; // inscrutable address 4947 if (alloc != allocation()) 4948 return FAIL; // wrong allocation! (store needs to float up) 4949 int size_in_bytes = st->memory_size(); 4950 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) { 4951 return FAIL; // mismatched access 4952 } 4953 Node* val = st->in(MemNode::ValueIn); 4954 4955 if (!detect_init_independence(val, phase)) 4956 return FAIL; // stored value must be 'simple enough' 4957 4958 // The Store can be captured only if nothing after the allocation 4959 // and before the Store is using the memory location that the store 4960 // overwrites. 4961 bool failed = false; 4962 // If is_complete_with_arraycopy() is true the shape of the graph is 4963 // well defined and is safe so no need for extra checks. 4964 if (!is_complete_with_arraycopy()) { 4965 // We are going to look at each use of the memory state following 4966 // the allocation to make sure nothing reads the memory that the 4967 // Store writes. 4968 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 4969 int alias_idx = phase->C->get_alias_index(t_adr); 4970 ResourceMark rm; 4971 Unique_Node_List mems; 4972 mems.push(mem); 4973 Node* unique_merge = nullptr; 4974 for (uint next = 0; next < mems.size(); ++next) { 4975 Node *m = mems.at(next); 4976 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 4977 Node *n = m->fast_out(j); 4978 if (n->outcnt() == 0) { 4979 continue; 4980 } 4981 if (n == st) { 4982 continue; 4983 } else if (n->in(0) != nullptr && n->in(0) != ctl) { 4984 // If the control of this use is different from the control 4985 // of the Store which is right after the InitializeNode then 4986 // this node cannot be between the InitializeNode and the 4987 // Store. 4988 continue; 4989 } else if (n->is_MergeMem()) { 4990 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 4991 // We can hit a MergeMemNode (that will likely go away 4992 // later) that is a direct use of the memory state 4993 // following the InitializeNode on the same slice as the 4994 // store node that we'd like to capture. We need to check 4995 // the uses of the MergeMemNode. 4996 mems.push(n); 4997 } 4998 } else if (n->is_Mem()) { 4999 Node* other_adr = n->in(MemNode::Address); 5000 if (other_adr == adr) { 5001 failed = true; 5002 break; 5003 } else { 5004 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 5005 if (other_t_adr != nullptr) { 5006 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 5007 if (other_alias_idx == alias_idx) { 5008 // A load from the same memory slice as the store right 5009 // after the InitializeNode. We check the control of the 5010 // object/array that is loaded from. If it's the same as 5011 // the store control then we cannot capture the store. 5012 assert(!n->is_Store(), "2 stores to same slice on same control?"); 5013 Node* base = other_adr; 5014 if (base->is_Phi()) { 5015 // In rare case, base may be a PhiNode and it may read 5016 // the same memory slice between InitializeNode and store. 5017 failed = true; 5018 break; 5019 } 5020 assert(base->is_AddP(), "should be addp but is %s", base->Name()); 5021 base = base->in(AddPNode::Base); 5022 if (base != nullptr) { 5023 base = base->uncast(); 5024 if (base->is_Proj() && base->in(0) == alloc) { 5025 failed = true; 5026 break; 5027 } 5028 } 5029 } 5030 } 5031 } 5032 } else { 5033 failed = true; 5034 break; 5035 } 5036 } 5037 } 5038 } 5039 if (failed) { 5040 if (!can_reshape) { 5041 // We decided we couldn't capture the store during parsing. We 5042 // should try again during the next IGVN once the graph is 5043 // cleaner. 5044 phase->C->record_for_igvn(st); 5045 } 5046 return FAIL; 5047 } 5048 5049 return offset; // success 5050 } 5051 5052 // Find the captured store in(i) which corresponds to the range 5053 // [start..start+size) in the initialized object. 5054 // If there is one, return its index i. If there isn't, return the 5055 // negative of the index where it should be inserted. 5056 // Return 0 if the queried range overlaps an initialization boundary 5057 // or if dead code is encountered. 5058 // If size_in_bytes is zero, do not bother with overlap checks. 5059 int InitializeNode::captured_store_insertion_point(intptr_t start, 5060 int size_in_bytes, 5061 PhaseValues* phase) { 5062 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize); 5063 5064 if (is_complete()) 5065 return FAIL; // arraycopy got here first; punt 5066 5067 assert(allocation() != nullptr, "must be present"); 5068 5069 // no negatives, no header fields: 5070 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 5071 5072 // after a certain size, we bail out on tracking all the stores: 5073 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 5074 if (start >= ti_limit) return FAIL; 5075 5076 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 5077 if (i >= limit) return -(int)i; // not found; here is where to put it 5078 5079 Node* st = in(i); 5080 intptr_t st_off = get_store_offset(st, phase); 5081 if (st_off < 0) { 5082 if (st != zero_memory()) { 5083 return FAIL; // bail out if there is dead garbage 5084 } 5085 } else if (st_off > start) { 5086 // ...we are done, since stores are ordered 5087 if (st_off < start + size_in_bytes) { 5088 return FAIL; // the next store overlaps 5089 } 5090 return -(int)i; // not found; here is where to put it 5091 } else if (st_off < start) { 5092 assert(st->as_Store()->memory_size() <= MAX_STORE, ""); 5093 if (size_in_bytes != 0 && 5094 start < st_off + MAX_STORE && 5095 start < st_off + st->as_Store()->memory_size()) { 5096 return FAIL; // the previous store overlaps 5097 } 5098 } else { 5099 if (size_in_bytes != 0 && 5100 st->as_Store()->memory_size() != size_in_bytes) { 5101 return FAIL; // mismatched store size 5102 } 5103 return i; 5104 } 5105 5106 ++i; 5107 } 5108 } 5109 5110 // Look for a captured store which initializes at the offset 'start' 5111 // with the given size. If there is no such store, and no other 5112 // initialization interferes, then return zero_memory (the memory 5113 // projection of the AllocateNode). 5114 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 5115 PhaseValues* phase) { 5116 assert(stores_are_sane(phase), ""); 5117 int i = captured_store_insertion_point(start, size_in_bytes, phase); 5118 if (i == 0) { 5119 return nullptr; // something is dead 5120 } else if (i < 0) { 5121 return zero_memory(); // just primordial zero bits here 5122 } else { 5123 Node* st = in(i); // here is the store at this position 5124 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 5125 return st; 5126 } 5127 } 5128 5129 // Create, as a raw pointer, an address within my new object at 'offset'. 5130 Node* InitializeNode::make_raw_address(intptr_t offset, 5131 PhaseGVN* phase) { 5132 Node* addr = in(RawAddress); 5133 if (offset != 0) { 5134 Compile* C = phase->C; 5135 addr = phase->transform( new AddPNode(C->top(), addr, 5136 phase->MakeConX(offset)) ); 5137 } 5138 return addr; 5139 } 5140 5141 // Clone the given store, converting it into a raw store 5142 // initializing a field or element of my new object. 5143 // Caller is responsible for retiring the original store, 5144 // with subsume_node or the like. 5145 // 5146 // From the example above InitializeNode::InitializeNode, 5147 // here are the old stores to be captured: 5148 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 5149 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 5150 // 5151 // Here is the changed code; note the extra edges on init: 5152 // alloc = (Allocate ...) 5153 // rawoop = alloc.RawAddress 5154 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 5155 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 5156 // init = (Initialize alloc.Control alloc.Memory rawoop 5157 // rawstore1 rawstore2) 5158 // 5159 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 5160 PhaseGVN* phase, bool can_reshape) { 5161 assert(stores_are_sane(phase), ""); 5162 5163 if (start < 0) return nullptr; 5164 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 5165 5166 Compile* C = phase->C; 5167 int size_in_bytes = st->memory_size(); 5168 int i = captured_store_insertion_point(start, size_in_bytes, phase); 5169 if (i == 0) return nullptr; // bail out 5170 Node* prev_mem = nullptr; // raw memory for the captured store 5171 if (i > 0) { 5172 prev_mem = in(i); // there is a pre-existing store under this one 5173 set_req(i, C->top()); // temporarily disconnect it 5174 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 5175 } else { 5176 i = -i; // no pre-existing store 5177 prev_mem = zero_memory(); // a slice of the newly allocated object 5178 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 5179 set_req(--i, C->top()); // reuse this edge; it has been folded away 5180 else 5181 ins_req(i, C->top()); // build a new edge 5182 } 5183 Node* new_st = st->clone(); 5184 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 5185 new_st->set_req(MemNode::Control, in(Control)); 5186 new_st->set_req(MemNode::Memory, prev_mem); 5187 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 5188 bs->eliminate_gc_barrier_data(new_st); 5189 new_st = phase->transform(new_st); 5190 5191 // At this point, new_st might have swallowed a pre-existing store 5192 // at the same offset, or perhaps new_st might have disappeared, 5193 // if it redundantly stored the same value (or zero to fresh memory). 5194 5195 // In any case, wire it in: 5196 PhaseIterGVN* igvn = phase->is_IterGVN(); 5197 if (igvn) { 5198 igvn->rehash_node_delayed(this); 5199 } 5200 set_req(i, new_st); 5201 5202 // The caller may now kill the old guy. 5203 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 5204 assert(check_st == new_st || check_st == nullptr, "must be findable"); 5205 assert(!is_complete(), ""); 5206 return new_st; 5207 } 5208 5209 static bool store_constant(jlong* tiles, int num_tiles, 5210 intptr_t st_off, int st_size, 5211 jlong con) { 5212 if ((st_off & (st_size-1)) != 0) 5213 return false; // strange store offset (assume size==2**N) 5214 address addr = (address)tiles + st_off; 5215 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 5216 switch (st_size) { 5217 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 5218 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 5219 case sizeof(jint): *(jint*) addr = (jint) con; break; 5220 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 5221 default: return false; // strange store size (detect size!=2**N here) 5222 } 5223 return true; // return success to caller 5224 } 5225 5226 // Coalesce subword constants into int constants and possibly 5227 // into long constants. The goal, if the CPU permits, 5228 // is to initialize the object with a small number of 64-bit tiles. 5229 // Also, convert floating-point constants to bit patterns. 5230 // Non-constants are not relevant to this pass. 5231 // 5232 // In terms of the running example on InitializeNode::InitializeNode 5233 // and InitializeNode::capture_store, here is the transformation 5234 // of rawstore1 and rawstore2 into rawstore12: 5235 // alloc = (Allocate ...) 5236 // rawoop = alloc.RawAddress 5237 // tile12 = 0x00010002 5238 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 5239 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 5240 // 5241 void 5242 InitializeNode::coalesce_subword_stores(intptr_t header_size, 5243 Node* size_in_bytes, 5244 PhaseGVN* phase) { 5245 Compile* C = phase->C; 5246 5247 assert(stores_are_sane(phase), ""); 5248 // Note: After this pass, they are not completely sane, 5249 // since there may be some overlaps. 5250 5251 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 5252 5253 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 5254 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 5255 size_limit = MIN2(size_limit, ti_limit); 5256 size_limit = align_up(size_limit, BytesPerLong); 5257 int num_tiles = size_limit / BytesPerLong; 5258 5259 // allocate space for the tile map: 5260 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 5261 jlong tiles_buf[small_len]; 5262 Node* nodes_buf[small_len]; 5263 jlong inits_buf[small_len]; 5264 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 5265 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 5266 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 5267 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 5268 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 5269 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 5270 // tiles: exact bitwise model of all primitive constants 5271 // nodes: last constant-storing node subsumed into the tiles model 5272 // inits: which bytes (in each tile) are touched by any initializations 5273 5274 //// Pass A: Fill in the tile model with any relevant stores. 5275 5276 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 5277 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 5278 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 5279 Node* zmem = zero_memory(); // initially zero memory state 5280 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 5281 Node* st = in(i); 5282 intptr_t st_off = get_store_offset(st, phase); 5283 5284 // Figure out the store's offset and constant value: 5285 if (st_off < header_size) continue; //skip (ignore header) 5286 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 5287 int st_size = st->as_Store()->memory_size(); 5288 if (st_off + st_size > size_limit) break; 5289 5290 // Record which bytes are touched, whether by constant or not. 5291 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 5292 continue; // skip (strange store size) 5293 5294 const Type* val = phase->type(st->in(MemNode::ValueIn)); 5295 if (!val->singleton()) continue; //skip (non-con store) 5296 BasicType type = val->basic_type(); 5297 5298 jlong con = 0; 5299 switch (type) { 5300 case T_INT: con = val->is_int()->get_con(); break; 5301 case T_LONG: con = val->is_long()->get_con(); break; 5302 case T_FLOAT: con = jint_cast(val->getf()); break; 5303 case T_DOUBLE: con = jlong_cast(val->getd()); break; 5304 default: continue; //skip (odd store type) 5305 } 5306 5307 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 5308 st->Opcode() == Op_StoreL) { 5309 continue; // This StoreL is already optimal. 5310 } 5311 5312 // Store down the constant. 5313 store_constant(tiles, num_tiles, st_off, st_size, con); 5314 5315 intptr_t j = st_off >> LogBytesPerLong; 5316 5317 if (type == T_INT && st_size == BytesPerInt 5318 && (st_off & BytesPerInt) == BytesPerInt) { 5319 jlong lcon = tiles[j]; 5320 if (!Matcher::isSimpleConstant64(lcon) && 5321 st->Opcode() == Op_StoreI) { 5322 // This StoreI is already optimal by itself. 5323 jint* intcon = (jint*) &tiles[j]; 5324 intcon[1] = 0; // undo the store_constant() 5325 5326 // If the previous store is also optimal by itself, back up and 5327 // undo the action of the previous loop iteration... if we can. 5328 // But if we can't, just let the previous half take care of itself. 5329 st = nodes[j]; 5330 st_off -= BytesPerInt; 5331 con = intcon[0]; 5332 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) { 5333 assert(st_off >= header_size, "still ignoring header"); 5334 assert(get_store_offset(st, phase) == st_off, "must be"); 5335 assert(in(i-1) == zmem, "must be"); 5336 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 5337 assert(con == tcon->is_int()->get_con(), "must be"); 5338 // Undo the effects of the previous loop trip, which swallowed st: 5339 intcon[0] = 0; // undo store_constant() 5340 set_req(i-1, st); // undo set_req(i, zmem) 5341 nodes[j] = nullptr; // undo nodes[j] = st 5342 --old_subword; // undo ++old_subword 5343 } 5344 continue; // This StoreI is already optimal. 5345 } 5346 } 5347 5348 // This store is not needed. 5349 set_req(i, zmem); 5350 nodes[j] = st; // record for the moment 5351 if (st_size < BytesPerLong) // something has changed 5352 ++old_subword; // includes int/float, but who's counting... 5353 else ++old_long; 5354 } 5355 5356 if ((old_subword + old_long) == 0) 5357 return; // nothing more to do 5358 5359 //// Pass B: Convert any non-zero tiles into optimal constant stores. 5360 // Be sure to insert them before overlapping non-constant stores. 5361 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 5362 for (int j = 0; j < num_tiles; j++) { 5363 jlong con = tiles[j]; 5364 jlong init = inits[j]; 5365 if (con == 0) continue; 5366 jint con0, con1; // split the constant, address-wise 5367 jint init0, init1; // split the init map, address-wise 5368 { union { jlong con; jint intcon[2]; } u; 5369 u.con = con; 5370 con0 = u.intcon[0]; 5371 con1 = u.intcon[1]; 5372 u.con = init; 5373 init0 = u.intcon[0]; 5374 init1 = u.intcon[1]; 5375 } 5376 5377 Node* old = nodes[j]; 5378 assert(old != nullptr, "need the prior store"); 5379 intptr_t offset = (j * BytesPerLong); 5380 5381 bool split = !Matcher::isSimpleConstant64(con); 5382 5383 if (offset < header_size) { 5384 assert(offset + BytesPerInt >= header_size, "second int counts"); 5385 assert(*(jint*)&tiles[j] == 0, "junk in header"); 5386 split = true; // only the second word counts 5387 // Example: int a[] = { 42 ... } 5388 } else if (con0 == 0 && init0 == -1) { 5389 split = true; // first word is covered by full inits 5390 // Example: int a[] = { ... foo(), 42 ... } 5391 } else if (con1 == 0 && init1 == -1) { 5392 split = true; // second word is covered by full inits 5393 // Example: int a[] = { ... 42, foo() ... } 5394 } 5395 5396 // Here's a case where init0 is neither 0 nor -1: 5397 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 5398 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 5399 // In this case the tile is not split; it is (jlong)42. 5400 // The big tile is stored down, and then the foo() value is inserted. 5401 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 5402 5403 Node* ctl = old->in(MemNode::Control); 5404 Node* adr = make_raw_address(offset, phase); 5405 const TypePtr* atp = TypeRawPtr::BOTTOM; 5406 5407 // One or two coalesced stores to plop down. 5408 Node* st[2]; 5409 intptr_t off[2]; 5410 int nst = 0; 5411 if (!split) { 5412 ++new_long; 5413 off[nst] = offset; 5414 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 5415 phase->longcon(con), T_LONG, MemNode::unordered); 5416 } else { 5417 // Omit either if it is a zero. 5418 if (con0 != 0) { 5419 ++new_int; 5420 off[nst] = offset; 5421 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 5422 phase->intcon(con0), T_INT, MemNode::unordered); 5423 } 5424 if (con1 != 0) { 5425 ++new_int; 5426 offset += BytesPerInt; 5427 adr = make_raw_address(offset, phase); 5428 off[nst] = offset; 5429 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 5430 phase->intcon(con1), T_INT, MemNode::unordered); 5431 } 5432 } 5433 5434 // Insert second store first, then the first before the second. 5435 // Insert each one just before any overlapping non-constant stores. 5436 while (nst > 0) { 5437 Node* st1 = st[--nst]; 5438 C->copy_node_notes_to(st1, old); 5439 st1 = phase->transform(st1); 5440 offset = off[nst]; 5441 assert(offset >= header_size, "do not smash header"); 5442 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 5443 guarantee(ins_idx != 0, "must re-insert constant store"); 5444 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 5445 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 5446 set_req(--ins_idx, st1); 5447 else 5448 ins_req(ins_idx, st1); 5449 } 5450 } 5451 5452 if (PrintCompilation && WizardMode) 5453 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 5454 old_subword, old_long, new_int, new_long); 5455 if (C->log() != nullptr) 5456 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 5457 old_subword, old_long, new_int, new_long); 5458 5459 // Clean up any remaining occurrences of zmem: 5460 remove_extra_zeroes(); 5461 } 5462 5463 // Explore forward from in(start) to find the first fully initialized 5464 // word, and return its offset. Skip groups of subword stores which 5465 // together initialize full words. If in(start) is itself part of a 5466 // fully initialized word, return the offset of in(start). If there 5467 // are no following full-word stores, or if something is fishy, return 5468 // a negative value. 5469 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 5470 int int_map = 0; 5471 intptr_t int_map_off = 0; 5472 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 5473 5474 for (uint i = start, limit = req(); i < limit; i++) { 5475 Node* st = in(i); 5476 5477 intptr_t st_off = get_store_offset(st, phase); 5478 if (st_off < 0) break; // return conservative answer 5479 5480 int st_size = st->as_Store()->memory_size(); 5481 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 5482 return st_off; // we found a complete word init 5483 } 5484 5485 // update the map: 5486 5487 intptr_t this_int_off = align_down(st_off, BytesPerInt); 5488 if (this_int_off != int_map_off) { 5489 // reset the map: 5490 int_map = 0; 5491 int_map_off = this_int_off; 5492 } 5493 5494 int subword_off = st_off - this_int_off; 5495 int_map |= right_n_bits(st_size) << subword_off; 5496 if ((int_map & FULL_MAP) == FULL_MAP) { 5497 return this_int_off; // we found a complete word init 5498 } 5499 5500 // Did this store hit or cross the word boundary? 5501 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt); 5502 if (next_int_off == this_int_off + BytesPerInt) { 5503 // We passed the current int, without fully initializing it. 5504 int_map_off = next_int_off; 5505 int_map >>= BytesPerInt; 5506 } else if (next_int_off > this_int_off + BytesPerInt) { 5507 // We passed the current and next int. 5508 return this_int_off + BytesPerInt; 5509 } 5510 } 5511 5512 return -1; 5513 } 5514 5515 5516 // Called when the associated AllocateNode is expanded into CFG. 5517 // At this point, we may perform additional optimizations. 5518 // Linearize the stores by ascending offset, to make memory 5519 // activity as coherent as possible. 5520 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 5521 intptr_t header_size, 5522 Node* size_in_bytes, 5523 PhaseIterGVN* phase) { 5524 assert(!is_complete(), "not already complete"); 5525 assert(stores_are_sane(phase), ""); 5526 assert(allocation() != nullptr, "must be present"); 5527 5528 remove_extra_zeroes(); 5529 5530 if (ReduceFieldZeroing || ReduceBulkZeroing) 5531 // reduce instruction count for common initialization patterns 5532 coalesce_subword_stores(header_size, size_in_bytes, phase); 5533 5534 Node* zmem = zero_memory(); // initially zero memory state 5535 Node* inits = zmem; // accumulating a linearized chain of inits 5536 #ifdef ASSERT 5537 intptr_t first_offset = allocation()->minimum_header_size(); 5538 intptr_t last_init_off = first_offset; // previous init offset 5539 intptr_t last_init_end = first_offset; // previous init offset+size 5540 intptr_t last_tile_end = first_offset; // previous tile offset+size 5541 #endif 5542 intptr_t zeroes_done = header_size; 5543 5544 bool do_zeroing = true; // we might give up if inits are very sparse 5545 int big_init_gaps = 0; // how many large gaps have we seen? 5546 5547 if (UseTLAB && ZeroTLAB) do_zeroing = false; 5548 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 5549 5550 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 5551 Node* st = in(i); 5552 intptr_t st_off = get_store_offset(st, phase); 5553 if (st_off < 0) 5554 break; // unknown junk in the inits 5555 if (st->in(MemNode::Memory) != zmem) 5556 break; // complicated store chains somehow in list 5557 5558 int st_size = st->as_Store()->memory_size(); 5559 intptr_t next_init_off = st_off + st_size; 5560 5561 if (do_zeroing && zeroes_done < next_init_off) { 5562 // See if this store needs a zero before it or under it. 5563 intptr_t zeroes_needed = st_off; 5564 5565 if (st_size < BytesPerInt) { 5566 // Look for subword stores which only partially initialize words. 5567 // If we find some, we must lay down some word-level zeroes first, 5568 // underneath the subword stores. 5569 // 5570 // Examples: 5571 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 5572 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 5573 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 5574 // 5575 // Note: coalesce_subword_stores may have already done this, 5576 // if it was prompted by constant non-zero subword initializers. 5577 // But this case can still arise with non-constant stores. 5578 5579 intptr_t next_full_store = find_next_fullword_store(i, phase); 5580 5581 // In the examples above: 5582 // in(i) p q r s x y z 5583 // st_off 12 13 14 15 12 13 14 5584 // st_size 1 1 1 1 1 1 1 5585 // next_full_s. 12 16 16 16 16 16 16 5586 // z's_done 12 16 16 16 12 16 12 5587 // z's_needed 12 16 16 16 16 16 16 5588 // zsize 0 0 0 0 4 0 4 5589 if (next_full_store < 0) { 5590 // Conservative tack: Zero to end of current word. 5591 zeroes_needed = align_up(zeroes_needed, BytesPerInt); 5592 } else { 5593 // Zero to beginning of next fully initialized word. 5594 // Or, don't zero at all, if we are already in that word. 5595 assert(next_full_store >= zeroes_needed, "must go forward"); 5596 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 5597 zeroes_needed = next_full_store; 5598 } 5599 } 5600 5601 if (zeroes_needed > zeroes_done) { 5602 intptr_t zsize = zeroes_needed - zeroes_done; 5603 // Do some incremental zeroing on rawmem, in parallel with inits. 5604 zeroes_done = align_down(zeroes_done, BytesPerInt); 5605 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 5606 allocation()->in(AllocateNode::InitValue), 5607 allocation()->in(AllocateNode::RawInitValue), 5608 zeroes_done, zeroes_needed, 5609 phase); 5610 zeroes_done = zeroes_needed; 5611 if (zsize > InitArrayShortSize && ++big_init_gaps > 2) 5612 do_zeroing = false; // leave the hole, next time 5613 } 5614 } 5615 5616 // Collect the store and move on: 5617 phase->replace_input_of(st, MemNode::Memory, inits); 5618 inits = st; // put it on the linearized chain 5619 set_req(i, zmem); // unhook from previous position 5620 5621 if (zeroes_done == st_off) 5622 zeroes_done = next_init_off; 5623 5624 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 5625 5626 #ifdef ASSERT 5627 // Various order invariants. Weaker than stores_are_sane because 5628 // a large constant tile can be filled in by smaller non-constant stores. 5629 assert(st_off >= last_init_off, "inits do not reverse"); 5630 last_init_off = st_off; 5631 const Type* val = nullptr; 5632 if (st_size >= BytesPerInt && 5633 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 5634 (int)val->basic_type() < (int)T_OBJECT) { 5635 assert(st_off >= last_tile_end, "tiles do not overlap"); 5636 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 5637 last_tile_end = MAX2(last_tile_end, next_init_off); 5638 } else { 5639 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong); 5640 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 5641 assert(st_off >= last_init_end, "inits do not overlap"); 5642 last_init_end = next_init_off; // it's a non-tile 5643 } 5644 #endif //ASSERT 5645 } 5646 5647 remove_extra_zeroes(); // clear out all the zmems left over 5648 add_req(inits); 5649 5650 if (!(UseTLAB && ZeroTLAB)) { 5651 // If anything remains to be zeroed, zero it all now. 5652 zeroes_done = align_down(zeroes_done, BytesPerInt); 5653 // if it is the last unused 4 bytes of an instance, forget about it 5654 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 5655 if (zeroes_done + BytesPerLong >= size_limit) { 5656 AllocateNode* alloc = allocation(); 5657 assert(alloc != nullptr, "must be present"); 5658 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) { 5659 Node* klass_node = alloc->in(AllocateNode::KlassNode); 5660 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass(); 5661 if (zeroes_done == k->layout_helper()) 5662 zeroes_done = size_limit; 5663 } 5664 } 5665 if (zeroes_done < size_limit) { 5666 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 5667 allocation()->in(AllocateNode::InitValue), 5668 allocation()->in(AllocateNode::RawInitValue), 5669 zeroes_done, size_in_bytes, phase); 5670 } 5671 } 5672 5673 set_complete(phase); 5674 return rawmem; 5675 } 5676 5677 5678 #ifdef ASSERT 5679 bool InitializeNode::stores_are_sane(PhaseValues* phase) { 5680 if (is_complete()) 5681 return true; // stores could be anything at this point 5682 assert(allocation() != nullptr, "must be present"); 5683 intptr_t last_off = allocation()->minimum_header_size(); 5684 for (uint i = InitializeNode::RawStores; i < req(); i++) { 5685 Node* st = in(i); 5686 intptr_t st_off = get_store_offset(st, phase); 5687 if (st_off < 0) continue; // ignore dead garbage 5688 if (last_off > st_off) { 5689 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off); 5690 this->dump(2); 5691 assert(false, "ascending store offsets"); 5692 return false; 5693 } 5694 last_off = st_off + st->as_Store()->memory_size(); 5695 } 5696 return true; 5697 } 5698 #endif //ASSERT 5699 5700 5701 5702 5703 //============================MergeMemNode===================================== 5704 // 5705 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 5706 // contributing store or call operations. Each contributor provides the memory 5707 // state for a particular "alias type" (see Compile::alias_type). For example, 5708 // if a MergeMem has an input X for alias category #6, then any memory reference 5709 // to alias category #6 may use X as its memory state input, as an exact equivalent 5710 // to using the MergeMem as a whole. 5711 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 5712 // 5713 // (Here, the <N> notation gives the index of the relevant adr_type.) 5714 // 5715 // In one special case (and more cases in the future), alias categories overlap. 5716 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 5717 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 5718 // it is exactly equivalent to that state W: 5719 // MergeMem(<Bot>: W) <==> W 5720 // 5721 // Usually, the merge has more than one input. In that case, where inputs 5722 // overlap (i.e., one is Bot), the narrower alias type determines the memory 5723 // state for that type, and the wider alias type (Bot) fills in everywhere else: 5724 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 5725 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 5726 // 5727 // A merge can take a "wide" memory state as one of its narrow inputs. 5728 // This simply means that the merge observes out only the relevant parts of 5729 // the wide input. That is, wide memory states arriving at narrow merge inputs 5730 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 5731 // 5732 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 5733 // and that memory slices "leak through": 5734 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 5735 // 5736 // But, in such a cascade, repeated memory slices can "block the leak": 5737 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 5738 // 5739 // In the last example, Y is not part of the combined memory state of the 5740 // outermost MergeMem. The system must, of course, prevent unschedulable 5741 // memory states from arising, so you can be sure that the state Y is somehow 5742 // a precursor to state Y'. 5743 // 5744 // 5745 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 5746 // of each MergeMemNode array are exactly the numerical alias indexes, including 5747 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 5748 // Compile::alias_type (and kin) produce and manage these indexes. 5749 // 5750 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 5751 // (Note that this provides quick access to the top node inside MergeMem methods, 5752 // without the need to reach out via TLS to Compile::current.) 5753 // 5754 // As a consequence of what was just described, a MergeMem that represents a full 5755 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 5756 // containing all alias categories. 5757 // 5758 // MergeMem nodes never (?) have control inputs, so in(0) is null. 5759 // 5760 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 5761 // a memory state for the alias type <N>, or else the top node, meaning that 5762 // there is no particular input for that alias type. Note that the length of 5763 // a MergeMem is variable, and may be extended at any time to accommodate new 5764 // memory states at larger alias indexes. When merges grow, they are of course 5765 // filled with "top" in the unused in() positions. 5766 // 5767 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 5768 // (Top was chosen because it works smoothly with passes like GCM.) 5769 // 5770 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 5771 // the type of random VM bits like TLS references.) Since it is always the 5772 // first non-Bot memory slice, some low-level loops use it to initialize an 5773 // index variable: for (i = AliasIdxRaw; i < req(); i++). 5774 // 5775 // 5776 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 5777 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 5778 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 5779 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 5780 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 5781 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 5782 // 5783 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 5784 // really that different from the other memory inputs. An abbreviation called 5785 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 5786 // 5787 // 5788 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 5789 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 5790 // that "emerges though" the base memory will be marked as excluding the alias types 5791 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 5792 // 5793 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 5794 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 5795 // 5796 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 5797 // (It is currently unimplemented.) As you can see, the resulting merge is 5798 // actually a disjoint union of memory states, rather than an overlay. 5799 // 5800 5801 //------------------------------MergeMemNode----------------------------------- 5802 Node* MergeMemNode::make_empty_memory() { 5803 Node* empty_memory = (Node*) Compile::current()->top(); 5804 assert(empty_memory->is_top(), "correct sentinel identity"); 5805 return empty_memory; 5806 } 5807 5808 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 5809 init_class_id(Class_MergeMem); 5810 // all inputs are nullified in Node::Node(int) 5811 // set_input(0, nullptr); // no control input 5812 5813 // Initialize the edges uniformly to top, for starters. 5814 Node* empty_mem = make_empty_memory(); 5815 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 5816 init_req(i,empty_mem); 5817 } 5818 assert(empty_memory() == empty_mem, ""); 5819 5820 if( new_base != nullptr && new_base->is_MergeMem() ) { 5821 MergeMemNode* mdef = new_base->as_MergeMem(); 5822 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 5823 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 5824 mms.set_memory(mms.memory2()); 5825 } 5826 assert(base_memory() == mdef->base_memory(), ""); 5827 } else { 5828 set_base_memory(new_base); 5829 } 5830 } 5831 5832 // Make a new, untransformed MergeMem with the same base as 'mem'. 5833 // If mem is itself a MergeMem, populate the result with the same edges. 5834 MergeMemNode* MergeMemNode::make(Node* mem) { 5835 return new MergeMemNode(mem); 5836 } 5837 5838 //------------------------------cmp-------------------------------------------- 5839 uint MergeMemNode::hash() const { return NO_HASH; } 5840 bool MergeMemNode::cmp( const Node &n ) const { 5841 return (&n == this); // Always fail except on self 5842 } 5843 5844 //------------------------------Identity--------------------------------------- 5845 Node* MergeMemNode::Identity(PhaseGVN* phase) { 5846 // Identity if this merge point does not record any interesting memory 5847 // disambiguations. 5848 Node* base_mem = base_memory(); 5849 Node* empty_mem = empty_memory(); 5850 if (base_mem != empty_mem) { // Memory path is not dead? 5851 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 5852 Node* mem = in(i); 5853 if (mem != empty_mem && mem != base_mem) { 5854 return this; // Many memory splits; no change 5855 } 5856 } 5857 } 5858 return base_mem; // No memory splits; ID on the one true input 5859 } 5860 5861 //------------------------------Ideal------------------------------------------ 5862 // This method is invoked recursively on chains of MergeMem nodes 5863 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 5864 // Remove chain'd MergeMems 5865 // 5866 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 5867 // relative to the "in(Bot)". Since we are patching both at the same time, 5868 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 5869 // but rewrite each "in(i)" relative to the new "in(Bot)". 5870 Node *progress = nullptr; 5871 5872 5873 Node* old_base = base_memory(); 5874 Node* empty_mem = empty_memory(); 5875 if (old_base == empty_mem) 5876 return nullptr; // Dead memory path. 5877 5878 MergeMemNode* old_mbase; 5879 if (old_base != nullptr && old_base->is_MergeMem()) 5880 old_mbase = old_base->as_MergeMem(); 5881 else 5882 old_mbase = nullptr; 5883 Node* new_base = old_base; 5884 5885 // simplify stacked MergeMems in base memory 5886 if (old_mbase) new_base = old_mbase->base_memory(); 5887 5888 // the base memory might contribute new slices beyond my req() 5889 if (old_mbase) grow_to_match(old_mbase); 5890 5891 // Note: We do not call verify_sparse on entry, because inputs 5892 // can normalize to the base_memory via subsume_node or similar 5893 // mechanisms. This method repairs that damage. 5894 5895 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 5896 5897 // Look at each slice. 5898 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 5899 Node* old_in = in(i); 5900 // calculate the old memory value 5901 Node* old_mem = old_in; 5902 if (old_mem == empty_mem) old_mem = old_base; 5903 assert(old_mem == memory_at(i), ""); 5904 5905 // maybe update (reslice) the old memory value 5906 5907 // simplify stacked MergeMems 5908 Node* new_mem = old_mem; 5909 MergeMemNode* old_mmem; 5910 if (old_mem != nullptr && old_mem->is_MergeMem()) 5911 old_mmem = old_mem->as_MergeMem(); 5912 else 5913 old_mmem = nullptr; 5914 if (old_mmem == this) { 5915 // This can happen if loops break up and safepoints disappear. 5916 // A merge of BotPtr (default) with a RawPtr memory derived from a 5917 // safepoint can be rewritten to a merge of the same BotPtr with 5918 // the BotPtr phi coming into the loop. If that phi disappears 5919 // also, we can end up with a self-loop of the mergemem. 5920 // In general, if loops degenerate and memory effects disappear, 5921 // a mergemem can be left looking at itself. This simply means 5922 // that the mergemem's default should be used, since there is 5923 // no longer any apparent effect on this slice. 5924 // Note: If a memory slice is a MergeMem cycle, it is unreachable 5925 // from start. Update the input to TOP. 5926 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 5927 } 5928 else if (old_mmem != nullptr) { 5929 new_mem = old_mmem->memory_at(i); 5930 } 5931 // else preceding memory was not a MergeMem 5932 5933 // maybe store down a new value 5934 Node* new_in = new_mem; 5935 if (new_in == new_base) new_in = empty_mem; 5936 5937 if (new_in != old_in) { 5938 // Warning: Do not combine this "if" with the previous "if" 5939 // A memory slice might have be be rewritten even if it is semantically 5940 // unchanged, if the base_memory value has changed. 5941 set_req_X(i, new_in, phase); 5942 progress = this; // Report progress 5943 } 5944 } 5945 5946 if (new_base != old_base) { 5947 set_req_X(Compile::AliasIdxBot, new_base, phase); 5948 // Don't use set_base_memory(new_base), because we need to update du. 5949 assert(base_memory() == new_base, ""); 5950 progress = this; 5951 } 5952 5953 if( base_memory() == this ) { 5954 // a self cycle indicates this memory path is dead 5955 set_req(Compile::AliasIdxBot, empty_mem); 5956 } 5957 5958 // Resolve external cycles by calling Ideal on a MergeMem base_memory 5959 // Recursion must occur after the self cycle check above 5960 if( base_memory()->is_MergeMem() ) { 5961 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 5962 Node *m = phase->transform(new_mbase); // Rollup any cycles 5963 if( m != nullptr && 5964 (m->is_top() || 5965 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) { 5966 // propagate rollup of dead cycle to self 5967 set_req(Compile::AliasIdxBot, empty_mem); 5968 } 5969 } 5970 5971 if( base_memory() == empty_mem ) { 5972 progress = this; 5973 // Cut inputs during Parse phase only. 5974 // During Optimize phase a dead MergeMem node will be subsumed by Top. 5975 if( !can_reshape ) { 5976 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 5977 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 5978 } 5979 } 5980 } 5981 5982 if( !progress && base_memory()->is_Phi() && can_reshape ) { 5983 // Check if PhiNode::Ideal's "Split phis through memory merges" 5984 // transform should be attempted. Look for this->phi->this cycle. 5985 uint merge_width = req(); 5986 if (merge_width > Compile::AliasIdxRaw) { 5987 PhiNode* phi = base_memory()->as_Phi(); 5988 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 5989 if (phi->in(i) == this) { 5990 phase->is_IterGVN()->_worklist.push(phi); 5991 break; 5992 } 5993 } 5994 } 5995 } 5996 5997 assert(progress || verify_sparse(), "please, no dups of base"); 5998 return progress; 5999 } 6000 6001 //-------------------------set_base_memory------------------------------------- 6002 void MergeMemNode::set_base_memory(Node *new_base) { 6003 Node* empty_mem = empty_memory(); 6004 set_req(Compile::AliasIdxBot, new_base); 6005 assert(memory_at(req()) == new_base, "must set default memory"); 6006 // Clear out other occurrences of new_base: 6007 if (new_base != empty_mem) { 6008 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 6009 if (in(i) == new_base) set_req(i, empty_mem); 6010 } 6011 } 6012 } 6013 6014 //------------------------------out_RegMask------------------------------------ 6015 const RegMask &MergeMemNode::out_RegMask() const { 6016 return RegMask::Empty; 6017 } 6018 6019 //------------------------------dump_spec-------------------------------------- 6020 #ifndef PRODUCT 6021 void MergeMemNode::dump_spec(outputStream *st) const { 6022 st->print(" {"); 6023 Node* base_mem = base_memory(); 6024 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 6025 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem; 6026 if (mem == base_mem) { st->print(" -"); continue; } 6027 st->print( " N%d:", mem->_idx ); 6028 Compile::current()->get_adr_type(i)->dump_on(st); 6029 } 6030 st->print(" }"); 6031 } 6032 #endif // !PRODUCT 6033 6034 6035 #ifdef ASSERT 6036 static bool might_be_same(Node* a, Node* b) { 6037 if (a == b) return true; 6038 if (!(a->is_Phi() || b->is_Phi())) return false; 6039 // phis shift around during optimization 6040 return true; // pretty stupid... 6041 } 6042 6043 // verify a narrow slice (either incoming or outgoing) 6044 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 6045 if (!VerifyAliases) return; // don't bother to verify unless requested 6046 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 6047 if (Node::in_dump()) return; // muzzle asserts when printing 6048 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 6049 assert(n != nullptr, ""); 6050 // Elide intervening MergeMem's 6051 while (n->is_MergeMem()) { 6052 n = n->as_MergeMem()->memory_at(alias_idx); 6053 } 6054 Compile* C = Compile::current(); 6055 const TypePtr* n_adr_type = n->adr_type(); 6056 if (n == m->empty_memory()) { 6057 // Implicit copy of base_memory() 6058 } else if (n_adr_type != TypePtr::BOTTOM) { 6059 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type"); 6060 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 6061 } else { 6062 // A few places like make_runtime_call "know" that VM calls are narrow, 6063 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 6064 bool expected_wide_mem = false; 6065 if (n == m->base_memory()) { 6066 expected_wide_mem = true; 6067 } else if (alias_idx == Compile::AliasIdxRaw || 6068 n == m->memory_at(Compile::AliasIdxRaw)) { 6069 expected_wide_mem = true; 6070 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 6071 // memory can "leak through" calls on channels that 6072 // are write-once. Allow this also. 6073 expected_wide_mem = true; 6074 } 6075 assert(expected_wide_mem, "expected narrow slice replacement"); 6076 } 6077 } 6078 #else // !ASSERT 6079 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 6080 #endif 6081 6082 6083 //-----------------------------memory_at--------------------------------------- 6084 Node* MergeMemNode::memory_at(uint alias_idx) const { 6085 assert(alias_idx >= Compile::AliasIdxRaw || 6086 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()), 6087 "must avoid base_memory and AliasIdxTop"); 6088 6089 // Otherwise, it is a narrow slice. 6090 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 6091 if (is_empty_memory(n)) { 6092 // the array is sparse; empty slots are the "top" node 6093 n = base_memory(); 6094 assert(Node::in_dump() 6095 || n == nullptr || n->bottom_type() == Type::TOP 6096 || n->adr_type() == nullptr // address is TOP 6097 || n->adr_type() == TypePtr::BOTTOM 6098 || n->adr_type() == TypeRawPtr::BOTTOM 6099 || !Compile::current()->do_aliasing(), 6100 "must be a wide memory"); 6101 // do_aliasing == false if we are organizing the memory states manually. 6102 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 6103 } else { 6104 // make sure the stored slice is sane 6105 #ifdef ASSERT 6106 if (VMError::is_error_reported() || Node::in_dump()) { 6107 } else if (might_be_same(n, base_memory())) { 6108 // Give it a pass: It is a mostly harmless repetition of the base. 6109 // This can arise normally from node subsumption during optimization. 6110 } else { 6111 verify_memory_slice(this, alias_idx, n); 6112 } 6113 #endif 6114 } 6115 return n; 6116 } 6117 6118 //---------------------------set_memory_at------------------------------------- 6119 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 6120 verify_memory_slice(this, alias_idx, n); 6121 Node* empty_mem = empty_memory(); 6122 if (n == base_memory()) n = empty_mem; // collapse default 6123 uint need_req = alias_idx+1; 6124 if (req() < need_req) { 6125 if (n == empty_mem) return; // already the default, so do not grow me 6126 // grow the sparse array 6127 do { 6128 add_req(empty_mem); 6129 } while (req() < need_req); 6130 } 6131 set_req( alias_idx, n ); 6132 } 6133 6134 6135 6136 //--------------------------iteration_setup------------------------------------ 6137 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 6138 if (other != nullptr) { 6139 grow_to_match(other); 6140 // invariant: the finite support of mm2 is within mm->req() 6141 #ifdef ASSERT 6142 for (uint i = req(); i < other->req(); i++) { 6143 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 6144 } 6145 #endif 6146 } 6147 // Replace spurious copies of base_memory by top. 6148 Node* base_mem = base_memory(); 6149 if (base_mem != nullptr && !base_mem->is_top()) { 6150 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 6151 if (in(i) == base_mem) 6152 set_req(i, empty_memory()); 6153 } 6154 } 6155 } 6156 6157 //---------------------------grow_to_match------------------------------------- 6158 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 6159 Node* empty_mem = empty_memory(); 6160 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 6161 // look for the finite support of the other memory 6162 for (uint i = other->req(); --i >= req(); ) { 6163 if (other->in(i) != empty_mem) { 6164 uint new_len = i+1; 6165 while (req() < new_len) add_req(empty_mem); 6166 break; 6167 } 6168 } 6169 } 6170 6171 //---------------------------verify_sparse------------------------------------- 6172 #ifndef PRODUCT 6173 bool MergeMemNode::verify_sparse() const { 6174 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 6175 Node* base_mem = base_memory(); 6176 // The following can happen in degenerate cases, since empty==top. 6177 if (is_empty_memory(base_mem)) return true; 6178 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 6179 assert(in(i) != nullptr, "sane slice"); 6180 if (in(i) == base_mem) return false; // should have been the sentinel value! 6181 } 6182 return true; 6183 } 6184 6185 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 6186 Node* n; 6187 n = mm->in(idx); 6188 if (mem == n) return true; // might be empty_memory() 6189 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 6190 if (mem == n) return true; 6191 return false; 6192 } 6193 #endif // !PRODUCT