1 /* 2 * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "compiler/compileLog.hpp" 28 #include "gc/shared/barrierSet.hpp" 29 #include "gc/shared/c2/barrierSetC2.hpp" 30 #include "memory/allocation.inline.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "oops/objArrayKlass.hpp" 33 #include "opto/addnode.hpp" 34 #include "opto/arraycopynode.hpp" 35 #include "opto/cfgnode.hpp" 36 #include "opto/compile.hpp" 37 #include "opto/connode.hpp" 38 #include "opto/convertnode.hpp" 39 #include "opto/loopnode.hpp" 40 #include "opto/machnode.hpp" 41 #include "opto/matcher.hpp" 42 #include "opto/memnode.hpp" 43 #include "opto/mulnode.hpp" 44 #include "opto/narrowptrnode.hpp" 45 #include "opto/phaseX.hpp" 46 #include "opto/regmask.hpp" 47 #include "opto/rootnode.hpp" 48 #include "utilities/align.hpp" 49 #include "utilities/copy.hpp" 50 #include "utilities/macros.hpp" 51 #include "utilities/powerOfTwo.hpp" 52 #include "utilities/vmError.hpp" 53 54 // Portions of code courtesy of Clifford Click 55 56 // Optimization - Graph Style 57 58 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 59 60 //============================================================================= 61 uint MemNode::size_of() const { return sizeof(*this); } 62 63 const TypePtr *MemNode::adr_type() const { 64 Node* adr = in(Address); 65 if (adr == NULL) return NULL; // node is dead 66 const TypePtr* cross_check = NULL; 67 DEBUG_ONLY(cross_check = _adr_type); 68 return calculate_adr_type(adr->bottom_type(), cross_check); 69 } 70 71 bool MemNode::check_if_adr_maybe_raw(Node* adr) { 72 if (adr != NULL) { 73 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) { 74 return true; 75 } 76 } 77 return false; 78 } 79 80 #ifndef PRODUCT 81 void MemNode::dump_spec(outputStream *st) const { 82 if (in(Address) == NULL) return; // node is dead 83 #ifndef ASSERT 84 // fake the missing field 85 const TypePtr* _adr_type = NULL; 86 if (in(Address) != NULL) 87 _adr_type = in(Address)->bottom_type()->isa_ptr(); 88 #endif 89 dump_adr_type(this, _adr_type, st); 90 91 Compile* C = Compile::current(); 92 if (C->alias_type(_adr_type)->is_volatile()) { 93 st->print(" Volatile!"); 94 } 95 if (_unaligned_access) { 96 st->print(" unaligned"); 97 } 98 if (_mismatched_access) { 99 st->print(" mismatched"); 100 } 101 if (_unsafe_access) { 102 st->print(" unsafe"); 103 } 104 } 105 106 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 107 st->print(" @"); 108 if (adr_type == NULL) { 109 st->print("NULL"); 110 } else { 111 adr_type->dump_on(st); 112 Compile* C = Compile::current(); 113 Compile::AliasType* atp = NULL; 114 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 115 if (atp == NULL) 116 st->print(", idx=?\?;"); 117 else if (atp->index() == Compile::AliasIdxBot) 118 st->print(", idx=Bot;"); 119 else if (atp->index() == Compile::AliasIdxTop) 120 st->print(", idx=Top;"); 121 else if (atp->index() == Compile::AliasIdxRaw) 122 st->print(", idx=Raw;"); 123 else { 124 ciField* field = atp->field(); 125 if (field) { 126 st->print(", name="); 127 field->print_name_on(st); 128 } 129 st->print(", idx=%d;", atp->index()); 130 } 131 } 132 } 133 134 extern void print_alias_types(); 135 136 #endif 137 138 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) { 139 assert((t_oop != NULL), "sanity"); 140 bool is_instance = t_oop->is_known_instance_field(); 141 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() && 142 (load != NULL) && load->is_Load() && 143 (phase->is_IterGVN() != NULL); 144 if (!(is_instance || is_boxed_value_load)) 145 return mchain; // don't try to optimize non-instance types 146 uint instance_id = t_oop->instance_id(); 147 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory); 148 Node *prev = NULL; 149 Node *result = mchain; 150 while (prev != result) { 151 prev = result; 152 if (result == start_mem) 153 break; // hit one of our sentinels 154 // skip over a call which does not affect this memory slice 155 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 156 Node *proj_in = result->in(0); 157 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 158 break; // hit one of our sentinels 159 } else if (proj_in->is_Call()) { 160 // ArrayCopyNodes processed here as well 161 CallNode *call = proj_in->as_Call(); 162 if (!call->may_modify(t_oop, phase)) { // returns false for instances 163 result = call->in(TypeFunc::Memory); 164 } 165 } else if (proj_in->is_Initialize()) { 166 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 167 // Stop if this is the initialization for the object instance which 168 // contains this memory slice, otherwise skip over it. 169 if ((alloc == NULL) || (alloc->_idx == instance_id)) { 170 break; 171 } 172 if (is_instance) { 173 result = proj_in->in(TypeFunc::Memory); 174 } else if (is_boxed_value_load) { 175 Node* klass = alloc->in(AllocateNode::KlassNode); 176 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 177 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) { 178 result = proj_in->in(TypeFunc::Memory); // not related allocation 179 } 180 } 181 } else if (proj_in->is_MemBar()) { 182 ArrayCopyNode* ac = NULL; 183 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) { 184 break; 185 } 186 result = proj_in->in(TypeFunc::Memory); 187 } else { 188 assert(false, "unexpected projection"); 189 } 190 } else if (result->is_ClearArray()) { 191 intptr_t offset; 192 AllocateNode* alloc = AllocateNode::Ideal_allocation(result->in(3), phase, offset); 193 194 if (!is_instance || (alloc == NULL) || !ClearArrayNode::step_through(&result, instance_id, phase)) { 195 // Can not bypass initialization of the instance 196 // we are looking for. 197 break; 198 } 199 // Otherwise skip it (the call updated 'result' value). 200 } else if (result->is_MergeMem()) { 201 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty); 202 } 203 } 204 return result; 205 } 206 207 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 208 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 209 if (t_oop == NULL) 210 return mchain; // don't try to optimize non-oop types 211 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 212 bool is_instance = t_oop->is_known_instance_field(); 213 PhaseIterGVN *igvn = phase->is_IterGVN(); 214 if (is_instance && igvn != NULL && result->is_Phi()) { 215 PhiNode *mphi = result->as_Phi(); 216 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 217 const TypePtr *t = mphi->adr_type(); 218 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 219 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 220 t->is_oopptr()->cast_to_exactness(true) 221 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 222 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) { 223 // clone the Phi with our address type 224 result = mphi->split_out_instance(t_adr, igvn); 225 } else { 226 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 227 } 228 } 229 return result; 230 } 231 232 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 233 uint alias_idx = phase->C->get_alias_index(tp); 234 Node *mem = mmem; 235 #ifdef ASSERT 236 { 237 // Check that current type is consistent with the alias index used during graph construction 238 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 239 bool consistent = adr_check == NULL || adr_check->empty() || 240 phase->C->must_alias(adr_check, alias_idx ); 241 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 242 if( !consistent && adr_check != NULL && !adr_check->empty() && 243 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 244 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 245 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 246 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 247 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 248 // don't assert if it is dead code. 249 consistent = true; 250 } 251 if( !consistent ) { 252 st->print("alias_idx==%d, adr_check==", alias_idx); 253 if( adr_check == NULL ) { 254 st->print("NULL"); 255 } else { 256 adr_check->dump(); 257 } 258 st->cr(); 259 print_alias_types(); 260 assert(consistent, "adr_check must match alias idx"); 261 } 262 } 263 #endif 264 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 265 // means an array I have not precisely typed yet. Do not do any 266 // alias stuff with it any time soon. 267 const TypeOopPtr *toop = tp->isa_oopptr(); 268 if( tp->base() != Type::AnyPtr && 269 !(toop && 270 toop->klass() != NULL && 271 toop->klass()->is_java_lang_Object() && 272 toop->offset() == Type::OffsetBot) ) { 273 // compress paths and change unreachable cycles to TOP 274 // If not, we can update the input infinitely along a MergeMem cycle 275 // Equivalent code in PhiNode::Ideal 276 Node* m = phase->transform(mmem); 277 // If transformed to a MergeMem, get the desired slice 278 // Otherwise the returned node represents memory for every slice 279 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 280 // Update input if it is progress over what we have now 281 } 282 return mem; 283 } 284 285 //--------------------------Ideal_common--------------------------------------- 286 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. 287 // Unhook non-raw memories from complete (macro-expanded) initializations. 288 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 289 // If our control input is a dead region, kill all below the region 290 Node *ctl = in(MemNode::Control); 291 if (ctl && remove_dead_region(phase, can_reshape)) 292 return this; 293 ctl = in(MemNode::Control); 294 // Don't bother trying to transform a dead node 295 if (ctl && ctl->is_top()) return NodeSentinel; 296 297 PhaseIterGVN *igvn = phase->is_IterGVN(); 298 // Wait if control on the worklist. 299 if (ctl && can_reshape && igvn != NULL) { 300 Node* bol = NULL; 301 Node* cmp = NULL; 302 if (ctl->in(0)->is_If()) { 303 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 304 bol = ctl->in(0)->in(1); 305 if (bol->is_Bool()) 306 cmp = ctl->in(0)->in(1)->in(1); 307 } 308 if (igvn->_worklist.member(ctl) || 309 (bol != NULL && igvn->_worklist.member(bol)) || 310 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 311 // This control path may be dead. 312 // Delay this memory node transformation until the control is processed. 313 phase->is_IterGVN()->_worklist.push(this); 314 return NodeSentinel; // caller will return NULL 315 } 316 } 317 // Ignore if memory is dead, or self-loop 318 Node *mem = in(MemNode::Memory); 319 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL 320 assert(mem != this, "dead loop in MemNode::Ideal"); 321 322 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 323 // This memory slice may be dead. 324 // Delay this mem node transformation until the memory is processed. 325 phase->is_IterGVN()->_worklist.push(this); 326 return NodeSentinel; // caller will return NULL 327 } 328 329 Node *address = in(MemNode::Address); 330 const Type *t_adr = phase->type(address); 331 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL 332 333 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) { 334 // Unsafe off-heap access with zero address. Remove access and other control users 335 // to not confuse optimizations and add a HaltNode to fail if this is ever executed. 336 assert(ctl != NULL, "unsafe accesses should be control dependent"); 337 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) { 338 Node* u = ctl->fast_out(i); 339 if (u != ctl) { 340 igvn->rehash_node_delayed(u); 341 int nb = u->replace_edge(ctl, phase->C->top()); 342 --i, imax -= nb; 343 } 344 } 345 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr)); 346 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address")); 347 phase->C->root()->add_req(halt); 348 return this; 349 } 350 351 if (can_reshape && igvn != NULL && 352 (igvn->_worklist.member(address) || 353 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) { 354 // The address's base and type may change when the address is processed. 355 // Delay this mem node transformation until the address is processed. 356 phase->is_IterGVN()->_worklist.push(this); 357 return NodeSentinel; // caller will return NULL 358 } 359 360 // Do NOT remove or optimize the next lines: ensure a new alias index 361 // is allocated for an oop pointer type before Escape Analysis. 362 // Note: C++ will not remove it since the call has side effect. 363 if (t_adr->isa_oopptr()) { 364 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 365 } 366 367 Node* base = NULL; 368 if (address->is_AddP()) { 369 base = address->in(AddPNode::Base); 370 } 371 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 372 !t_adr->isa_rawptr()) { 373 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 374 // Skip this node optimization if its address has TOP base. 375 return NodeSentinel; // caller will return NULL 376 } 377 378 // Avoid independent memory operations 379 Node* old_mem = mem; 380 381 // The code which unhooks non-raw memories from complete (macro-expanded) 382 // initializations was removed. After macro-expansion all stores catched 383 // by Initialize node became raw stores and there is no information 384 // which memory slices they modify. So it is unsafe to move any memory 385 // operation above these stores. Also in most cases hooked non-raw memories 386 // were already unhooked by using information from detect_ptr_independence() 387 // and find_previous_store(). 388 389 if (mem->is_MergeMem()) { 390 MergeMemNode* mmem = mem->as_MergeMem(); 391 const TypePtr *tp = t_adr->is_ptr(); 392 393 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 394 } 395 396 if (mem != old_mem) { 397 set_req(MemNode::Memory, mem); 398 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) { 399 igvn->_worklist.push(old_mem); 400 } 401 if (phase->type(mem) == Type::TOP) return NodeSentinel; 402 return this; 403 } 404 405 // let the subclass continue analyzing... 406 return NULL; 407 } 408 409 // Helper function for proving some simple control dominations. 410 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 411 // Already assumes that 'dom' is available at 'sub', and that 'sub' 412 // is not a constant (dominated by the method's StartNode). 413 // Used by MemNode::find_previous_store to prove that the 414 // control input of a memory operation predates (dominates) 415 // an allocation it wants to look past. 416 bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 417 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 418 return false; // Conservative answer for dead code 419 420 // Check 'dom'. Skip Proj and CatchProj nodes. 421 dom = dom->find_exact_control(dom); 422 if (dom == NULL || dom->is_top()) 423 return false; // Conservative answer for dead code 424 425 if (dom == sub) { 426 // For the case when, for example, 'sub' is Initialize and the original 427 // 'dom' is Proj node of the 'sub'. 428 return false; 429 } 430 431 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 432 return true; 433 434 // 'dom' dominates 'sub' if its control edge and control edges 435 // of all its inputs dominate or equal to sub's control edge. 436 437 // Currently 'sub' is either Allocate, Initialize or Start nodes. 438 // Or Region for the check in LoadNode::Ideal(); 439 // 'sub' should have sub->in(0) != NULL. 440 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 441 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 442 443 // Get control edge of 'sub'. 444 Node* orig_sub = sub; 445 sub = sub->find_exact_control(sub->in(0)); 446 if (sub == NULL || sub->is_top()) 447 return false; // Conservative answer for dead code 448 449 assert(sub->is_CFG(), "expecting control"); 450 451 if (sub == dom) 452 return true; 453 454 if (sub->is_Start() || sub->is_Root()) 455 return false; 456 457 { 458 // Check all control edges of 'dom'. 459 460 ResourceMark rm; 461 Arena* arena = Thread::current()->resource_area(); 462 Node_List nlist(arena); 463 Unique_Node_List dom_list(arena); 464 465 dom_list.push(dom); 466 bool only_dominating_controls = false; 467 468 for (uint next = 0; next < dom_list.size(); next++) { 469 Node* n = dom_list.at(next); 470 if (n == orig_sub) 471 return false; // One of dom's inputs dominated by sub. 472 if (!n->is_CFG() && n->pinned()) { 473 // Check only own control edge for pinned non-control nodes. 474 n = n->find_exact_control(n->in(0)); 475 if (n == NULL || n->is_top()) 476 return false; // Conservative answer for dead code 477 assert(n->is_CFG(), "expecting control"); 478 dom_list.push(n); 479 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 480 only_dominating_controls = true; 481 } else if (n->is_CFG()) { 482 if (n->dominates(sub, nlist)) 483 only_dominating_controls = true; 484 else 485 return false; 486 } else { 487 // First, own control edge. 488 Node* m = n->find_exact_control(n->in(0)); 489 if (m != NULL) { 490 if (m->is_top()) 491 return false; // Conservative answer for dead code 492 dom_list.push(m); 493 } 494 // Now, the rest of edges. 495 uint cnt = n->req(); 496 for (uint i = 1; i < cnt; i++) { 497 m = n->find_exact_control(n->in(i)); 498 if (m == NULL || m->is_top()) 499 continue; 500 dom_list.push(m); 501 } 502 } 503 } 504 return only_dominating_controls; 505 } 506 } 507 508 //---------------------detect_ptr_independence--------------------------------- 509 // Used by MemNode::find_previous_store to prove that two base 510 // pointers are never equal. 511 // The pointers are accompanied by their associated allocations, 512 // if any, which have been previously discovered by the caller. 513 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 514 Node* p2, AllocateNode* a2, 515 PhaseTransform* phase) { 516 // Attempt to prove that these two pointers cannot be aliased. 517 // They may both manifestly be allocations, and they should differ. 518 // Or, if they are not both allocations, they can be distinct constants. 519 // Otherwise, one is an allocation and the other a pre-existing value. 520 if (a1 == NULL && a2 == NULL) { // neither an allocation 521 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 522 } else if (a1 != NULL && a2 != NULL) { // both allocations 523 return (a1 != a2); 524 } else if (a1 != NULL) { // one allocation a1 525 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 526 return all_controls_dominate(p2, a1); 527 } else { //(a2 != NULL) // one allocation a2 528 return all_controls_dominate(p1, a2); 529 } 530 return false; 531 } 532 533 534 // Find an arraycopy that must have set (can_see_stored_value=true) or 535 // could have set (can_see_stored_value=false) the value for this load 536 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 537 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 538 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 539 Node* mb = mem->in(0); 540 if (mb->in(0) != NULL && mb->in(0)->is_Proj() && 541 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) { 542 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy(); 543 if (ac->is_clonebasic()) { 544 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase); 545 if (alloc != NULL && alloc == ld_alloc) { 546 return ac; 547 } 548 } 549 } 550 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) { 551 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy(); 552 553 if (ac->is_arraycopy_validated() || 554 ac->is_copyof_validated() || 555 ac->is_copyofrange_validated()) { 556 Node* ld_addp = in(MemNode::Address); 557 if (ld_addp->is_AddP()) { 558 Node* ld_base = ld_addp->in(AddPNode::Address); 559 Node* ld_offs = ld_addp->in(AddPNode::Offset); 560 561 Node* dest = ac->in(ArrayCopyNode::Dest); 562 563 if (dest == ld_base) { 564 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 565 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) { 566 return ac; 567 } 568 if (!can_see_stored_value) { 569 mem = ac->in(TypeFunc::Memory); 570 } 571 } 572 } 573 } 574 } 575 return NULL; 576 } 577 578 // The logic for reordering loads and stores uses four steps: 579 // (a) Walk carefully past stores and initializations which we 580 // can prove are independent of this load. 581 // (b) Observe that the next memory state makes an exact match 582 // with self (load or store), and locate the relevant store. 583 // (c) Ensure that, if we were to wire self directly to the store, 584 // the optimizer would fold it up somehow. 585 // (d) Do the rewiring, and return, depending on some other part of 586 // the optimizer to fold up the load. 587 // This routine handles steps (a) and (b). Steps (c) and (d) are 588 // specific to loads and stores, so they are handled by the callers. 589 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 590 // 591 Node* MemNode::find_previous_store(PhaseTransform* phase) { 592 Node* ctrl = in(MemNode::Control); 593 Node* adr = in(MemNode::Address); 594 intptr_t offset = 0; 595 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 596 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 597 598 if (offset == Type::OffsetBot) 599 return NULL; // cannot unalias unless there are precise offsets 600 601 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr); 602 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 603 604 intptr_t size_in_bytes = memory_size(); 605 606 Node* mem = in(MemNode::Memory); // start searching here... 607 608 int cnt = 50; // Cycle limiter 609 for (;;) { // While we can dance past unrelated stores... 610 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 611 612 Node* prev = mem; 613 if (mem->is_Store()) { 614 Node* st_adr = mem->in(MemNode::Address); 615 intptr_t st_offset = 0; 616 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 617 if (st_base == NULL) 618 break; // inscrutable pointer 619 620 // For raw accesses it's not enough to prove that constant offsets don't intersect. 621 // We need the bases to be the equal in order for the offset check to make sense. 622 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) { 623 break; 624 } 625 626 if (st_offset != offset && st_offset != Type::OffsetBot) { 627 const int MAX_STORE = BytesPerLong; 628 if (st_offset >= offset + size_in_bytes || 629 st_offset <= offset - MAX_STORE || 630 st_offset <= offset - mem->as_Store()->memory_size()) { 631 // Success: The offsets are provably independent. 632 // (You may ask, why not just test st_offset != offset and be done? 633 // The answer is that stores of different sizes can co-exist 634 // in the same sequence of RawMem effects. We sometimes initialize 635 // a whole 'tile' of array elements with a single jint or jlong.) 636 mem = mem->in(MemNode::Memory); 637 continue; // (a) advance through independent store memory 638 } 639 } 640 if (st_base != base && 641 detect_ptr_independence(base, alloc, 642 st_base, 643 AllocateNode::Ideal_allocation(st_base, phase), 644 phase)) { 645 // Success: The bases are provably independent. 646 mem = mem->in(MemNode::Memory); 647 continue; // (a) advance through independent store memory 648 } 649 650 // (b) At this point, if the bases or offsets do not agree, we lose, 651 // since we have not managed to prove 'this' and 'mem' independent. 652 if (st_base == base && st_offset == offset) { 653 return mem; // let caller handle steps (c), (d) 654 } 655 656 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 657 InitializeNode* st_init = mem->in(0)->as_Initialize(); 658 AllocateNode* st_alloc = st_init->allocation(); 659 if (st_alloc == NULL) 660 break; // something degenerated 661 bool known_identical = false; 662 bool known_independent = false; 663 if (alloc == st_alloc) 664 known_identical = true; 665 else if (alloc != NULL) 666 known_independent = true; 667 else if (all_controls_dominate(this, st_alloc)) 668 known_independent = true; 669 670 if (known_independent) { 671 // The bases are provably independent: Either they are 672 // manifestly distinct allocations, or else the control 673 // of this load dominates the store's allocation. 674 int alias_idx = phase->C->get_alias_index(adr_type()); 675 if (alias_idx == Compile::AliasIdxRaw) { 676 mem = st_alloc->in(TypeFunc::Memory); 677 } else { 678 mem = st_init->memory(alias_idx); 679 } 680 continue; // (a) advance through independent store memory 681 } 682 683 // (b) at this point, if we are not looking at a store initializing 684 // the same allocation we are loading from, we lose. 685 if (known_identical) { 686 // From caller, can_see_stored_value will consult find_captured_store. 687 return mem; // let caller handle steps (c), (d) 688 } 689 690 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) { 691 if (prev != mem) { 692 // Found an arraycopy but it doesn't affect that load 693 continue; 694 } 695 // Found an arraycopy that may affect that load 696 return mem; 697 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 698 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 699 if (mem->is_Proj() && mem->in(0)->is_Call()) { 700 // ArrayCopyNodes processed here as well. 701 CallNode *call = mem->in(0)->as_Call(); 702 if (!call->may_modify(addr_t, phase)) { 703 mem = call->in(TypeFunc::Memory); 704 continue; // (a) advance through independent call memory 705 } 706 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 707 ArrayCopyNode* ac = NULL; 708 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) { 709 break; 710 } 711 mem = mem->in(0)->in(TypeFunc::Memory); 712 continue; // (a) advance through independent MemBar memory 713 } else if (mem->is_ClearArray()) { 714 intptr_t offset; 715 AllocateNode* alloc = AllocateNode::Ideal_allocation(mem->in(3), phase, offset); 716 717 if ((alloc != NULL) && ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 718 // (the call updated 'mem' value) 719 continue; // (a) advance through independent allocation memory 720 } else { 721 // Can not bypass initialization of the instance 722 // we are looking for. 723 return mem; 724 } 725 } else if (mem->is_MergeMem()) { 726 int alias_idx = phase->C->get_alias_index(adr_type()); 727 mem = mem->as_MergeMem()->memory_at(alias_idx); 728 continue; // (a) advance through independent MergeMem memory 729 } 730 } 731 732 // Unless there is an explicit 'continue', we must bail out here, 733 // because 'mem' is an inscrutable memory state (e.g., a call). 734 break; 735 } 736 737 return NULL; // bail out 738 } 739 740 //----------------------calculate_adr_type------------------------------------- 741 // Helper function. Notices when the given type of address hits top or bottom. 742 // Also, asserts a cross-check of the type against the expected address type. 743 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 744 if (t == Type::TOP) return NULL; // does not touch memory any more? 745 #ifdef ASSERT 746 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL; 747 #endif 748 const TypePtr* tp = t->isa_ptr(); 749 if (tp == NULL) { 750 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 751 return TypePtr::BOTTOM; // touches lots of memory 752 } else { 753 #ifdef ASSERT 754 // %%%% [phh] We don't check the alias index if cross_check is 755 // TypeRawPtr::BOTTOM. Needs to be investigated. 756 if (cross_check != NULL && 757 cross_check != TypePtr::BOTTOM && 758 cross_check != TypeRawPtr::BOTTOM) { 759 // Recheck the alias index, to see if it has changed (due to a bug). 760 Compile* C = Compile::current(); 761 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 762 "must stay in the original alias category"); 763 // The type of the address must be contained in the adr_type, 764 // disregarding "null"-ness. 765 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 766 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 767 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 768 "real address must not escape from expected memory type"); 769 } 770 #endif 771 return tp; 772 } 773 } 774 775 //============================================================================= 776 // Should LoadNode::Ideal() attempt to remove control edges? 777 bool LoadNode::can_remove_control() const { 778 return true; 779 } 780 uint LoadNode::size_of() const { return sizeof(*this); } 781 bool LoadNode::cmp( const Node &n ) const 782 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 783 const Type *LoadNode::bottom_type() const { return _type; } 784 uint LoadNode::ideal_reg() const { 785 return _type->ideal_reg(); 786 } 787 788 #ifndef PRODUCT 789 void LoadNode::dump_spec(outputStream *st) const { 790 MemNode::dump_spec(st); 791 if( !Verbose && !WizardMode ) { 792 // standard dump does this in Verbose and WizardMode 793 st->print(" #"); _type->dump_on(st); 794 } 795 if (!depends_only_on_test()) { 796 st->print(" (does not depend only on test)"); 797 } 798 } 799 #endif 800 801 #ifdef ASSERT 802 //----------------------------is_immutable_value------------------------------- 803 // Helper function to allow a raw load without control edge for some cases 804 bool LoadNode::is_immutable_value(Node* adr) { 805 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 806 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 807 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 808 in_bytes(JavaThread::osthread_offset()))); 809 } 810 #endif 811 812 //----------------------------LoadNode::make----------------------------------- 813 // Polymorphic factory method: 814 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, 815 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) { 816 Compile* C = gvn.C; 817 818 // sanity check the alias category against the created node type 819 assert(!(adr_type->isa_oopptr() && 820 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 821 "use LoadKlassNode instead"); 822 assert(!(adr_type->isa_aryptr() && 823 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 824 "use LoadRangeNode instead"); 825 // Check control edge of raw loads 826 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 827 // oop will be recorded in oop map if load crosses safepoint 828 rt->isa_oopptr() || is_immutable_value(adr), 829 "raw memory operations should have control edge"); 830 LoadNode* load = NULL; 831 switch (bt) { 832 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 833 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 834 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 835 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 836 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 837 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break; 838 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 839 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 840 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break; 841 case T_OBJECT: 842 #ifdef _LP64 843 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 844 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency); 845 } else 846 #endif 847 { 848 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 849 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 850 } 851 break; 852 default: 853 ShouldNotReachHere(); 854 break; 855 } 856 assert(load != NULL, "LoadNode should have been created"); 857 if (unaligned) { 858 load->set_unaligned_access(); 859 } 860 if (mismatched) { 861 load->set_mismatched_access(); 862 } 863 if (unsafe) { 864 load->set_unsafe_access(); 865 } 866 load->set_barrier_data(barrier_data); 867 if (load->Opcode() == Op_LoadN) { 868 Node* ld = gvn.transform(load); 869 return new DecodeNNode(ld, ld->bottom_type()->make_ptr()); 870 } 871 872 return load; 873 } 874 875 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 876 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) { 877 bool require_atomic = true; 878 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic); 879 if (unaligned) { 880 load->set_unaligned_access(); 881 } 882 if (mismatched) { 883 load->set_mismatched_access(); 884 } 885 if (unsafe) { 886 load->set_unsafe_access(); 887 } 888 load->set_barrier_data(barrier_data); 889 return load; 890 } 891 892 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 893 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) { 894 bool require_atomic = true; 895 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic); 896 if (unaligned) { 897 load->set_unaligned_access(); 898 } 899 if (mismatched) { 900 load->set_mismatched_access(); 901 } 902 if (unsafe) { 903 load->set_unsafe_access(); 904 } 905 load->set_barrier_data(barrier_data); 906 return load; 907 } 908 909 910 911 //------------------------------hash------------------------------------------- 912 uint LoadNode::hash() const { 913 // unroll addition of interesting fields 914 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 915 } 916 917 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 918 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 919 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 920 bool is_stable_ary = FoldStableValues && 921 (tp != NULL) && (tp->isa_aryptr() != NULL) && 922 tp->isa_aryptr()->is_stable(); 923 924 return (eliminate_boxing && non_volatile) || is_stable_ary; 925 } 926 927 return false; 928 } 929 930 // Is the value loaded previously stored by an arraycopy? If so return 931 // a load node that reads from the source array so we may be able to 932 // optimize out the ArrayCopy node later. 933 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const { 934 Node* ld_adr = in(MemNode::Address); 935 intptr_t ld_off = 0; 936 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 937 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 938 if (ac != NULL) { 939 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 940 941 Node* mem = ac->in(TypeFunc::Memory); 942 Node* ctl = ac->in(0); 943 Node* src = ac->in(ArrayCopyNode::Src); 944 945 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) { 946 return NULL; 947 } 948 949 LoadNode* ld = clone()->as_Load(); 950 Node* addp = in(MemNode::Address)->clone(); 951 if (ac->as_ArrayCopy()->is_clonebasic()) { 952 assert(ld_alloc != NULL, "need an alloc"); 953 assert(addp->is_AddP(), "address must be addp"); 954 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 955 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern"); 956 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern"); 957 addp->set_req(AddPNode::Base, src); 958 addp->set_req(AddPNode::Address, src); 959 } else { 960 assert(ac->as_ArrayCopy()->is_arraycopy_validated() || 961 ac->as_ArrayCopy()->is_copyof_validated() || 962 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases"); 963 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 964 addp->set_req(AddPNode::Base, src); 965 addp->set_req(AddPNode::Address, src); 966 967 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 968 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 969 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 970 uint shift = exact_log2(type2aelembytes(ary_elem)); 971 972 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 973 #ifdef _LP64 974 diff = phase->transform(new ConvI2LNode(diff)); 975 #endif 976 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 977 978 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 979 addp->set_req(AddPNode::Offset, offset); 980 } 981 addp = phase->transform(addp); 982 #ifdef ASSERT 983 const TypePtr* adr_type = phase->type(addp)->is_ptr(); 984 ld->_adr_type = adr_type; 985 #endif 986 ld->set_req(MemNode::Address, addp); 987 ld->set_req(0, ctl); 988 ld->set_req(MemNode::Memory, mem); 989 // load depends on the tests that validate the arraycopy 990 ld->_control_dependency = UnknownControl; 991 return ld; 992 } 993 return NULL; 994 } 995 996 997 //---------------------------can_see_stored_value------------------------------ 998 // This routine exists to make sure this set of tests is done the same 999 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 1000 // will change the graph shape in a way which makes memory alive twice at the 1001 // same time (uses the Oracle model of aliasing), then some 1002 // LoadXNode::Identity will fold things back to the equivalence-class model 1003 // of aliasing. 1004 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 1005 Node* ld_adr = in(MemNode::Address); 1006 intptr_t ld_off = 0; 1007 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off); 1008 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase); 1009 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 1010 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 1011 // This is more general than load from boxing objects. 1012 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 1013 uint alias_idx = atp->index(); 1014 bool final = !atp->is_rewritable(); 1015 Node* result = NULL; 1016 Node* current = st; 1017 // Skip through chains of MemBarNodes checking the MergeMems for 1018 // new states for the slice of this load. Stop once any other 1019 // kind of node is encountered. Loads from final memory can skip 1020 // through any kind of MemBar but normal loads shouldn't skip 1021 // through MemBarAcquire since the could allow them to move out of 1022 // a synchronized region. 1023 while (current->is_Proj()) { 1024 int opc = current->in(0)->Opcode(); 1025 if ((final && (opc == Op_MemBarAcquire || 1026 opc == Op_MemBarAcquireLock || 1027 opc == Op_LoadFence)) || 1028 opc == Op_MemBarRelease || 1029 opc == Op_StoreFence || 1030 opc == Op_MemBarReleaseLock || 1031 opc == Op_MemBarStoreStore || 1032 opc == Op_MemBarCPUOrder) { 1033 Node* mem = current->in(0)->in(TypeFunc::Memory); 1034 if (mem->is_MergeMem()) { 1035 MergeMemNode* merge = mem->as_MergeMem(); 1036 Node* new_st = merge->memory_at(alias_idx); 1037 if (new_st == merge->base_memory()) { 1038 // Keep searching 1039 current = new_st; 1040 continue; 1041 } 1042 // Save the new memory state for the slice and fall through 1043 // to exit. 1044 result = new_st; 1045 } 1046 } 1047 break; 1048 } 1049 if (result != NULL) { 1050 st = result; 1051 } 1052 } 1053 1054 // Loop around twice in the case Load -> Initialize -> Store. 1055 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1056 for (int trip = 0; trip <= 1; trip++) { 1057 1058 if (st->is_Store()) { 1059 Node* st_adr = st->in(MemNode::Address); 1060 if (!phase->eqv(st_adr, ld_adr)) { 1061 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers). 1062 intptr_t st_off = 0; 1063 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off); 1064 if (ld_base == NULL) return NULL; 1065 if (st_base == NULL) return NULL; 1066 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL; 1067 if (ld_off != st_off) return NULL; 1068 if (ld_off == Type::OffsetBot) return NULL; 1069 // Same base, same offset. 1070 // Possible improvement for arrays: check index value instead of absolute offset. 1071 1072 // At this point we have proven something like this setup: 1073 // B = << base >> 1074 // L = LoadQ(AddP(Check/CastPP(B), #Off)) 1075 // S = StoreQ(AddP( B , #Off), V) 1076 // (Actually, we haven't yet proven the Q's are the same.) 1077 // In other words, we are loading from a casted version of 1078 // the same pointer-and-offset that we stored to. 1079 // Casted version may carry a dependency and it is respected. 1080 // Thus, we are able to replace L by V. 1081 } 1082 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1083 if (store_Opcode() != st->Opcode()) 1084 return NULL; 1085 return st->in(MemNode::ValueIn); 1086 } 1087 1088 // A load from a freshly-created object always returns zero. 1089 // (This can happen after LoadNode::Ideal resets the load's memory input 1090 // to find_captured_store, which returned InitializeNode::zero_memory.) 1091 if (st->is_Proj() && st->in(0)->is_Allocate() && 1092 (st->in(0) == ld_alloc) && 1093 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1094 // return a zero value for the load's basic type 1095 // (This is one of the few places where a generic PhaseTransform 1096 // can create new nodes. Think of it as lazily manifesting 1097 // virtually pre-existing constants.) 1098 return phase->zerocon(memory_type()); 1099 } 1100 1101 // A load from an initialization barrier can match a captured store. 1102 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1103 InitializeNode* init = st->in(0)->as_Initialize(); 1104 AllocateNode* alloc = init->allocation(); 1105 if ((alloc != NULL) && (alloc == ld_alloc)) { 1106 // examine a captured store value 1107 st = init->find_captured_store(ld_off, memory_size(), phase); 1108 if (st != NULL) { 1109 continue; // take one more trip around 1110 } 1111 } 1112 } 1113 1114 // Load boxed value from result of valueOf() call is input parameter. 1115 if (this->is_Load() && ld_adr->is_AddP() && 1116 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1117 intptr_t ignore = 0; 1118 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1119 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 1120 base = bs->step_over_gc_barrier(base); 1121 if (base != NULL && base->is_Proj() && 1122 base->as_Proj()->_con == TypeFunc::Parms && 1123 base->in(0)->is_CallStaticJava() && 1124 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1125 return base->in(0)->in(TypeFunc::Parms); 1126 } 1127 } 1128 1129 break; 1130 } 1131 1132 return NULL; 1133 } 1134 1135 //----------------------is_instance_field_load_with_local_phi------------------ 1136 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1137 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1138 in(Address)->is_AddP() ) { 1139 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1140 // Only instances and boxed values. 1141 if( t_oop != NULL && 1142 (t_oop->is_ptr_to_boxed_value() || 1143 t_oop->is_known_instance_field()) && 1144 t_oop->offset() != Type::OffsetBot && 1145 t_oop->offset() != Type::OffsetTop) { 1146 return true; 1147 } 1148 } 1149 return false; 1150 } 1151 1152 //------------------------------Identity--------------------------------------- 1153 // Loads are identity if previous store is to same address 1154 Node* LoadNode::Identity(PhaseGVN* phase) { 1155 // If the previous store-maker is the right kind of Store, and the store is 1156 // to the same address, then we are equal to the value stored. 1157 Node* mem = in(Memory); 1158 Node* value = can_see_stored_value(mem, phase); 1159 if( value ) { 1160 // byte, short & char stores truncate naturally. 1161 // A load has to load the truncated value which requires 1162 // some sort of masking operation and that requires an 1163 // Ideal call instead of an Identity call. 1164 if (memory_size() < BytesPerInt) { 1165 // If the input to the store does not fit with the load's result type, 1166 // it must be truncated via an Ideal call. 1167 if (!phase->type(value)->higher_equal(phase->type(this))) 1168 return this; 1169 } 1170 // (This works even when value is a Con, but LoadNode::Value 1171 // usually runs first, producing the singleton type of the Con.) 1172 return value; 1173 } 1174 1175 // Search for an existing data phi which was generated before for the same 1176 // instance's field to avoid infinite generation of phis in a loop. 1177 Node *region = mem->in(0); 1178 if (is_instance_field_load_with_local_phi(region)) { 1179 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1180 int this_index = phase->C->get_alias_index(addr_t); 1181 int this_offset = addr_t->offset(); 1182 int this_iid = addr_t->instance_id(); 1183 if (!addr_t->is_known_instance() && 1184 addr_t->is_ptr_to_boxed_value()) { 1185 // Use _idx of address base (could be Phi node) for boxed values. 1186 intptr_t ignore = 0; 1187 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1188 if (base == NULL) { 1189 return this; 1190 } 1191 this_iid = base->_idx; 1192 } 1193 const Type* this_type = bottom_type(); 1194 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1195 Node* phi = region->fast_out(i); 1196 if (phi->is_Phi() && phi != mem && 1197 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) { 1198 return phi; 1199 } 1200 } 1201 } 1202 1203 return this; 1204 } 1205 1206 // Construct an equivalent unsigned load. 1207 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) { 1208 BasicType bt = T_ILLEGAL; 1209 const Type* rt = NULL; 1210 switch (Opcode()) { 1211 case Op_LoadUB: return this; 1212 case Op_LoadUS: return this; 1213 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break; 1214 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break; 1215 default: 1216 assert(false, "no unsigned variant: %s", Name()); 1217 return NULL; 1218 } 1219 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1220 raw_adr_type(), rt, bt, _mo, _control_dependency, 1221 is_unaligned_access(), is_mismatched_access()); 1222 } 1223 1224 // Construct an equivalent signed load. 1225 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) { 1226 BasicType bt = T_ILLEGAL; 1227 const Type* rt = NULL; 1228 switch (Opcode()) { 1229 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break; 1230 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break; 1231 case Op_LoadB: // fall through 1232 case Op_LoadS: // fall through 1233 case Op_LoadI: // fall through 1234 case Op_LoadL: return this; 1235 default: 1236 assert(false, "no signed variant: %s", Name()); 1237 return NULL; 1238 } 1239 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1240 raw_adr_type(), rt, bt, _mo, _control_dependency, 1241 is_unaligned_access(), is_mismatched_access()); 1242 } 1243 1244 // We're loading from an object which has autobox behaviour. 1245 // If this object is result of a valueOf call we'll have a phi 1246 // merging a newly allocated object and a load from the cache. 1247 // We want to replace this load with the original incoming 1248 // argument to the valueOf call. 1249 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1250 assert(phase->C->eliminate_boxing(), "sanity"); 1251 intptr_t ignore = 0; 1252 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1253 if ((base == NULL) || base->is_Phi()) { 1254 // Push the loads from the phi that comes from valueOf up 1255 // through it to allow elimination of the loads and the recovery 1256 // of the original value. It is done in split_through_phi(). 1257 return NULL; 1258 } else if (base->is_Load() || 1259 (base->is_DecodeN() && base->in(1)->is_Load())) { 1260 // Eliminate the load of boxed value for integer types from the cache 1261 // array by deriving the value from the index into the array. 1262 // Capture the offset of the load and then reverse the computation. 1263 1264 // Get LoadN node which loads a boxing object from 'cache' array. 1265 if (base->is_DecodeN()) { 1266 base = base->in(1); 1267 } 1268 if (!base->in(Address)->is_AddP()) { 1269 return NULL; // Complex address 1270 } 1271 AddPNode* address = base->in(Address)->as_AddP(); 1272 Node* cache_base = address->in(AddPNode::Base); 1273 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1274 // Get ConP node which is static 'cache' field. 1275 cache_base = cache_base->in(1); 1276 } 1277 if ((cache_base != NULL) && cache_base->is_Con()) { 1278 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1279 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1280 Node* elements[4]; 1281 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1282 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1283 if (count > 0 && elements[0]->is_Con() && 1284 (count == 1 || 1285 (count == 2 && elements[1]->Opcode() == Op_LShiftX && 1286 elements[1]->in(2) == phase->intcon(shift)))) { 1287 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1288 // Fetch the box object cache[0] at the base of the array and get its value 1289 ciInstance* box = array->obj_at(0)->as_instance(); 1290 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1291 assert(ik->is_box_klass(), "sanity"); 1292 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1293 if (ik->nof_nonstatic_fields() == 1) { 1294 // This should be true nonstatic_field_at requires calling 1295 // nof_nonstatic_fields so check it anyway 1296 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1297 BasicType bt = c.basic_type(); 1298 // Only integer types have boxing cache. 1299 assert(bt == T_BOOLEAN || bt == T_CHAR || 1300 bt == T_BYTE || bt == T_SHORT || 1301 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt)); 1302 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1303 if (cache_low != (int)cache_low) { 1304 return NULL; // should not happen since cache is array indexed by value 1305 } 1306 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1307 if (offset != (int)offset) { 1308 return NULL; // should not happen since cache is array indexed by value 1309 } 1310 // Add up all the offsets making of the address of the load 1311 Node* result = elements[0]; 1312 for (int i = 1; i < count; i++) { 1313 result = phase->transform(new AddXNode(result, elements[i])); 1314 } 1315 // Remove the constant offset from the address and then 1316 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset))); 1317 // remove the scaling of the offset to recover the original index. 1318 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1319 // Peel the shift off directly but wrap it in a dummy node 1320 // since Ideal can't return existing nodes 1321 result = new RShiftXNode(result->in(1), phase->intcon(0)); 1322 } else if (result->is_Add() && result->in(2)->is_Con() && 1323 result->in(1)->Opcode() == Op_LShiftX && 1324 result->in(1)->in(2) == phase->intcon(shift)) { 1325 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1326 // but for boxing cache access we know that X<<Z will not overflow 1327 // (there is range check) so we do this optimizatrion by hand here. 1328 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift)); 1329 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con)); 1330 } else { 1331 result = new RShiftXNode(result, phase->intcon(shift)); 1332 } 1333 #ifdef _LP64 1334 if (bt != T_LONG) { 1335 result = new ConvL2INode(phase->transform(result)); 1336 } 1337 #else 1338 if (bt == T_LONG) { 1339 result = new ConvI2LNode(phase->transform(result)); 1340 } 1341 #endif 1342 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1343 // Need to preserve unboxing load type if it is unsigned. 1344 switch(this->Opcode()) { 1345 case Op_LoadUB: 1346 result = new AndINode(phase->transform(result), phase->intcon(0xFF)); 1347 break; 1348 case Op_LoadUS: 1349 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF)); 1350 break; 1351 } 1352 return result; 1353 } 1354 } 1355 } 1356 } 1357 } 1358 return NULL; 1359 } 1360 1361 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1362 Node* region = phi->in(0); 1363 if (region == NULL) { 1364 return false; // Wait stable graph 1365 } 1366 uint cnt = phi->req(); 1367 for (uint i = 1; i < cnt; i++) { 1368 Node* rc = region->in(i); 1369 if (rc == NULL || phase->type(rc) == Type::TOP) 1370 return false; // Wait stable graph 1371 Node* in = phi->in(i); 1372 if (in == NULL || phase->type(in) == Type::TOP) 1373 return false; // Wait stable graph 1374 } 1375 return true; 1376 } 1377 //------------------------------split_through_phi------------------------------ 1378 // Split instance or boxed field load through Phi. 1379 Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1380 Node* mem = in(Memory); 1381 Node* address = in(Address); 1382 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1383 1384 assert((t_oop != NULL) && 1385 (t_oop->is_known_instance_field() || 1386 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1387 1388 Compile* C = phase->C; 1389 intptr_t ignore = 0; 1390 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1391 bool base_is_phi = (base != NULL) && base->is_Phi(); 1392 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1393 (base != NULL) && (base == address->in(AddPNode::Base)) && 1394 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1395 1396 if (!((mem->is_Phi() || base_is_phi) && 1397 (load_boxed_values || t_oop->is_known_instance_field()))) { 1398 return NULL; // memory is not Phi 1399 } 1400 1401 if (mem->is_Phi()) { 1402 if (!stable_phi(mem->as_Phi(), phase)) { 1403 return NULL; // Wait stable graph 1404 } 1405 uint cnt = mem->req(); 1406 // Check for loop invariant memory. 1407 if (cnt == 3) { 1408 for (uint i = 1; i < cnt; i++) { 1409 Node* in = mem->in(i); 1410 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1411 if (m == mem) { 1412 if (i == 1) { 1413 // if the first edge was a loop, check second edge too. 1414 // If both are replaceable - we are in an infinite loop 1415 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase); 1416 if (n == mem) { 1417 break; 1418 } 1419 } 1420 set_req(Memory, mem->in(cnt - i)); 1421 return this; // made change 1422 } 1423 } 1424 } 1425 } 1426 if (base_is_phi) { 1427 if (!stable_phi(base->as_Phi(), phase)) { 1428 return NULL; // Wait stable graph 1429 } 1430 uint cnt = base->req(); 1431 // Check for loop invariant memory. 1432 if (cnt == 3) { 1433 for (uint i = 1; i < cnt; i++) { 1434 if (base->in(i) == base) { 1435 return NULL; // Wait stable graph 1436 } 1437 } 1438 } 1439 } 1440 1441 // Split through Phi (see original code in loopopts.cpp). 1442 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1443 1444 // Do nothing here if Identity will find a value 1445 // (to avoid infinite chain of value phis generation). 1446 if (!phase->eqv(this, this->Identity(phase))) { 1447 return NULL; 1448 } 1449 1450 // Select Region to split through. 1451 Node* region; 1452 if (!base_is_phi) { 1453 assert(mem->is_Phi(), "sanity"); 1454 region = mem->in(0); 1455 // Skip if the region dominates some control edge of the address. 1456 if (!MemNode::all_controls_dominate(address, region)) 1457 return NULL; 1458 } else if (!mem->is_Phi()) { 1459 assert(base_is_phi, "sanity"); 1460 region = base->in(0); 1461 // Skip if the region dominates some control edge of the memory. 1462 if (!MemNode::all_controls_dominate(mem, region)) 1463 return NULL; 1464 } else if (base->in(0) != mem->in(0)) { 1465 assert(base_is_phi && mem->is_Phi(), "sanity"); 1466 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1467 region = base->in(0); 1468 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1469 region = mem->in(0); 1470 } else { 1471 return NULL; // complex graph 1472 } 1473 } else { 1474 assert(base->in(0) == mem->in(0), "sanity"); 1475 region = mem->in(0); 1476 } 1477 1478 const Type* this_type = this->bottom_type(); 1479 int this_index = C->get_alias_index(t_oop); 1480 int this_offset = t_oop->offset(); 1481 int this_iid = t_oop->instance_id(); 1482 if (!t_oop->is_known_instance() && load_boxed_values) { 1483 // Use _idx of address base for boxed values. 1484 this_iid = base->_idx; 1485 } 1486 PhaseIterGVN* igvn = phase->is_IterGVN(); 1487 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset); 1488 for (uint i = 1; i < region->req(); i++) { 1489 Node* x; 1490 Node* the_clone = NULL; 1491 Node* in = region->in(i); 1492 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl && 1493 in != NULL && in->is_OuterStripMinedLoop()) { 1494 // No node should go in the outer strip mined loop 1495 in = in->in(LoopNode::EntryControl); 1496 } 1497 if (in == NULL || in == C->top()) { 1498 x = C->top(); // Dead path? Use a dead data op 1499 } else { 1500 x = this->clone(); // Else clone up the data op 1501 the_clone = x; // Remember for possible deletion. 1502 // Alter data node to use pre-phi inputs 1503 if (this->in(0) == region) { 1504 x->set_req(0, in); 1505 } else { 1506 x->set_req(0, NULL); 1507 } 1508 if (mem->is_Phi() && (mem->in(0) == region)) { 1509 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1510 } 1511 if (address->is_Phi() && address->in(0) == region) { 1512 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1513 } 1514 if (base_is_phi && (base->in(0) == region)) { 1515 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1516 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1517 x->set_req(Address, adr_x); 1518 } 1519 } 1520 // Check for a 'win' on some paths 1521 const Type *t = x->Value(igvn); 1522 1523 bool singleton = t->singleton(); 1524 1525 // See comments in PhaseIdealLoop::split_thru_phi(). 1526 if (singleton && t == Type::TOP) { 1527 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1528 } 1529 1530 if (singleton) { 1531 x = igvn->makecon(t); 1532 } else { 1533 // We now call Identity to try to simplify the cloned node. 1534 // Note that some Identity methods call phase->type(this). 1535 // Make sure that the type array is big enough for 1536 // our new node, even though we may throw the node away. 1537 // (This tweaking with igvn only works because x is a new node.) 1538 igvn->set_type(x, t); 1539 // If x is a TypeNode, capture any more-precise type permanently into Node 1540 // otherwise it will be not updated during igvn->transform since 1541 // igvn->type(x) is set to x->Value() already. 1542 x->raise_bottom_type(t); 1543 Node* y = x->Identity(igvn); 1544 if (y != x) { 1545 x = y; 1546 } else { 1547 y = igvn->hash_find_insert(x); 1548 if (y) { 1549 x = y; 1550 } else { 1551 // Else x is a new node we are keeping 1552 // We do not need register_new_node_with_optimizer 1553 // because set_type has already been called. 1554 igvn->_worklist.push(x); 1555 } 1556 } 1557 } 1558 if (x != the_clone && the_clone != NULL) { 1559 igvn->remove_dead_node(the_clone); 1560 } 1561 phi->set_req(i, x); 1562 } 1563 // Record Phi 1564 igvn->register_new_node_with_optimizer(phi); 1565 return phi; 1566 } 1567 1568 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const { 1569 if (Opcode() == Op_LoadX) { 1570 Node* address = in(MemNode::Address); 1571 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase); 1572 Node* mem = in(MemNode::Memory); 1573 if (alloc != NULL && mem->is_Proj() && 1574 mem->in(0) != NULL && 1575 mem->in(0) == alloc->initialization() && 1576 alloc->initialization()->proj_out_or_null(0) != NULL) { 1577 return alloc; 1578 } 1579 } 1580 return NULL; 1581 } 1582 1583 1584 //------------------------------Ideal------------------------------------------ 1585 // If the load is from Field memory and the pointer is non-null, it might be possible to 1586 // zero out the control input. 1587 // If the offset is constant and the base is an object allocation, 1588 // try to hook me up to the exact initializing store. 1589 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1590 Node* p = MemNode::Ideal_common(phase, can_reshape); 1591 if (p) return (p == NodeSentinel) ? NULL : p; 1592 1593 Node* ctrl = in(MemNode::Control); 1594 Node* address = in(MemNode::Address); 1595 bool progress = false; 1596 1597 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) && 1598 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes()); 1599 1600 // Skip up past a SafePoint control. Cannot do this for Stores because 1601 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1602 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1603 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw && 1604 !addr_mark && 1605 (depends_only_on_test() || has_unknown_control_dependency())) { 1606 ctrl = ctrl->in(0); 1607 set_req(MemNode::Control,ctrl); 1608 progress = true; 1609 } 1610 1611 intptr_t ignore = 0; 1612 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1613 if (base != NULL 1614 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1615 // Check for useless control edge in some common special cases 1616 if (in(MemNode::Control) != NULL 1617 && can_remove_control() 1618 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1619 && all_controls_dominate(base, phase->C->start())) { 1620 // A method-invariant, non-null address (constant or 'this' argument). 1621 set_req(MemNode::Control, NULL); 1622 progress = true; 1623 } 1624 } 1625 1626 Node* mem = in(MemNode::Memory); 1627 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1628 1629 if (can_reshape && (addr_t != NULL)) { 1630 // try to optimize our memory input 1631 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1632 if (opt_mem != mem) { 1633 set_req(MemNode::Memory, opt_mem); 1634 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1635 return this; 1636 } 1637 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1638 if ((t_oop != NULL) && 1639 (t_oop->is_known_instance_field() || 1640 t_oop->is_ptr_to_boxed_value())) { 1641 PhaseIterGVN *igvn = phase->is_IterGVN(); 1642 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1643 // Delay this transformation until memory Phi is processed. 1644 phase->is_IterGVN()->_worklist.push(this); 1645 return NULL; 1646 } 1647 // Split instance field load through Phi. 1648 Node* result = split_through_phi(phase); 1649 if (result != NULL) return result; 1650 1651 if (t_oop->is_ptr_to_boxed_value()) { 1652 Node* result = eliminate_autobox(phase); 1653 if (result != NULL) return result; 1654 } 1655 } 1656 } 1657 1658 // Is there a dominating load that loads the same value? Leave 1659 // anything that is not a load of a field/array element (like 1660 // barriers etc.) alone 1661 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) { 1662 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 1663 Node *use = mem->fast_out(i); 1664 if (use != this && 1665 use->Opcode() == Opcode() && 1666 use->in(0) != NULL && 1667 use->in(0) != in(0) && 1668 use->in(Address) == in(Address)) { 1669 Node* ctl = in(0); 1670 for (int i = 0; i < 10 && ctl != NULL; i++) { 1671 ctl = IfNode::up_one_dom(ctl); 1672 if (ctl == use->in(0)) { 1673 set_req(0, use->in(0)); 1674 return this; 1675 } 1676 } 1677 } 1678 } 1679 } 1680 1681 // Check for prior store with a different base or offset; make Load 1682 // independent. Skip through any number of them. Bail out if the stores 1683 // are in an endless dead cycle and report no progress. This is a key 1684 // transform for Reflection. However, if after skipping through the Stores 1685 // we can't then fold up against a prior store do NOT do the transform as 1686 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1687 // array memory alive twice: once for the hoisted Load and again after the 1688 // bypassed Store. This situation only works if EVERYBODY who does 1689 // anti-dependence work knows how to bypass. I.e. we need all 1690 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1691 // the alias index stuff. So instead, peek through Stores and IFF we can 1692 // fold up, do so. 1693 Node* prev_mem = find_previous_store(phase); 1694 if (prev_mem != NULL) { 1695 Node* value = can_see_arraycopy_value(prev_mem, phase); 1696 if (value != NULL) { 1697 return value; 1698 } 1699 } 1700 // Steps (a), (b): Walk past independent stores to find an exact match. 1701 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1702 // (c) See if we can fold up on the spot, but don't fold up here. 1703 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1704 // just return a prior value, which is done by Identity calls. 1705 if (can_see_stored_value(prev_mem, phase)) { 1706 // Make ready for step (d): 1707 set_req(MemNode::Memory, prev_mem); 1708 return this; 1709 } 1710 } 1711 1712 AllocateNode* alloc = is_new_object_mark_load(phase); 1713 if (alloc != NULL && alloc->Opcode() == Op_Allocate && UseBiasedLocking) { 1714 InitializeNode* init = alloc->initialization(); 1715 Node* control = init->proj_out(0); 1716 return alloc->make_ideal_mark(phase, address, control, mem); 1717 } 1718 1719 return progress ? this : NULL; 1720 } 1721 1722 // Helper to recognize certain Klass fields which are invariant across 1723 // some group of array types (e.g., int[] or all T[] where T < Object). 1724 const Type* 1725 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1726 ciKlass* klass) const { 1727 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1728 // The field is Klass::_modifier_flags. Return its (constant) value. 1729 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1730 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1731 return TypeInt::make(klass->modifier_flags()); 1732 } 1733 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1734 // The field is Klass::_access_flags. Return its (constant) value. 1735 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1736 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1737 return TypeInt::make(klass->access_flags()); 1738 } 1739 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1740 // The field is Klass::_layout_helper. Return its constant value if known. 1741 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1742 return TypeInt::make(klass->layout_helper()); 1743 } 1744 1745 // No match. 1746 return NULL; 1747 } 1748 1749 //------------------------------Value----------------------------------------- 1750 const Type* LoadNode::Value(PhaseGVN* phase) const { 1751 // Either input is TOP ==> the result is TOP 1752 Node* mem = in(MemNode::Memory); 1753 const Type *t1 = phase->type(mem); 1754 if (t1 == Type::TOP) return Type::TOP; 1755 Node* adr = in(MemNode::Address); 1756 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1757 if (tp == NULL || tp->empty()) return Type::TOP; 1758 int off = tp->offset(); 1759 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1760 Compile* C = phase->C; 1761 1762 // Try to guess loaded type from pointer type 1763 if (tp->isa_aryptr()) { 1764 const TypeAryPtr* ary = tp->is_aryptr(); 1765 const Type* t = ary->elem(); 1766 1767 // Determine whether the reference is beyond the header or not, by comparing 1768 // the offset against the offset of the start of the array's data. 1769 // Different array types begin at slightly different offsets (12 vs. 16). 1770 // We choose T_BYTE as an example base type that is least restrictive 1771 // as to alignment, which will therefore produce the smallest 1772 // possible base offset. 1773 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1774 const bool off_beyond_header = (off >= min_base_off); 1775 1776 // Try to constant-fold a stable array element. 1777 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) { 1778 // Make sure the reference is not into the header and the offset is constant 1779 ciObject* aobj = ary->const_oop(); 1780 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1781 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0); 1782 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, 1783 stable_dimension, 1784 memory_type(), is_unsigned()); 1785 if (con_type != NULL) { 1786 return con_type; 1787 } 1788 } 1789 } 1790 1791 // Don't do this for integer types. There is only potential profit if 1792 // the element type t is lower than _type; that is, for int types, if _type is 1793 // more restrictive than t. This only happens here if one is short and the other 1794 // char (both 16 bits), and in those cases we've made an intentional decision 1795 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1796 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1797 // 1798 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1799 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1800 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1801 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1802 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1803 // In fact, that could have been the original type of p1, and p1 could have 1804 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1805 // expression (LShiftL quux 3) independently optimized to the constant 8. 1806 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1807 && (_type->isa_vect() == NULL) 1808 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1809 // t might actually be lower than _type, if _type is a unique 1810 // concrete subclass of abstract class t. 1811 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header? 1812 const Type* jt = t->join_speculative(_type); 1813 // In any case, do not allow the join, per se, to empty out the type. 1814 if (jt->empty() && !t->empty()) { 1815 // This can happen if a interface-typed array narrows to a class type. 1816 jt = _type; 1817 } 1818 #ifdef ASSERT 1819 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1820 // The pointers in the autobox arrays are always non-null 1821 Node* base = adr->in(AddPNode::Base); 1822 if ((base != NULL) && base->is_DecodeN()) { 1823 // Get LoadN node which loads IntegerCache.cache field 1824 base = base->in(1); 1825 } 1826 if ((base != NULL) && base->is_Con()) { 1827 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1828 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1829 // It could be narrow oop 1830 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1831 } 1832 } 1833 } 1834 #endif 1835 return jt; 1836 } 1837 } 1838 } else if (tp->base() == Type::InstPtr) { 1839 assert( off != Type::OffsetBot || 1840 // arrays can be cast to Objects 1841 tp->is_oopptr()->klass()->is_java_lang_Object() || 1842 // unsafe field access may not have a constant offset 1843 C->has_unsafe_access(), 1844 "Field accesses must be precise" ); 1845 // For oop loads, we expect the _type to be precise. 1846 1847 // Optimize loads from constant fields. 1848 const TypeInstPtr* tinst = tp->is_instptr(); 1849 ciObject* const_oop = tinst->const_oop(); 1850 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) { 1851 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type()); 1852 if (con_type != NULL) { 1853 return con_type; 1854 } 1855 } 1856 } else if (tp->base() == Type::KlassPtr) { 1857 assert( off != Type::OffsetBot || 1858 // arrays can be cast to Objects 1859 tp->is_klassptr()->klass()->is_java_lang_Object() || 1860 // also allow array-loading from the primary supertype 1861 // array during subtype checks 1862 Opcode() == Op_LoadKlass, 1863 "Field accesses must be precise" ); 1864 // For klass/static loads, we expect the _type to be precise 1865 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) { 1866 /* With mirrors being an indirect in the Klass* 1867 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset)) 1868 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass). 1869 * 1870 * So check the type and klass of the node before the LoadP. 1871 */ 1872 Node* adr2 = adr->in(MemNode::Address); 1873 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 1874 if (tkls != NULL && !StressReflectiveCode) { 1875 ciKlass* klass = tkls->klass(); 1876 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1877 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1878 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1879 return TypeInstPtr::make(klass->java_mirror()); 1880 } 1881 } 1882 } 1883 1884 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1885 if (tkls != NULL && !StressReflectiveCode) { 1886 ciKlass* klass = tkls->klass(); 1887 if (klass->is_loaded() && tkls->klass_is_exact()) { 1888 // We are loading a field from a Klass metaobject whose identity 1889 // is known at compile time (the type is "exact" or "precise"). 1890 // Check for fields we know are maintained as constants by the VM. 1891 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1892 // The field is Klass::_super_check_offset. Return its (constant) value. 1893 // (Folds up type checking code.) 1894 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1895 return TypeInt::make(klass->super_check_offset()); 1896 } 1897 // Compute index into primary_supers array 1898 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1899 // Check for overflowing; use unsigned compare to handle the negative case. 1900 if( depth < ciKlass::primary_super_limit() ) { 1901 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1902 // (Folds up type checking code.) 1903 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1904 ciKlass *ss = klass->super_of_depth(depth); 1905 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1906 } 1907 const Type* aift = load_array_final_field(tkls, klass); 1908 if (aift != NULL) return aift; 1909 } 1910 1911 // We can still check if we are loading from the primary_supers array at a 1912 // shallow enough depth. Even though the klass is not exact, entries less 1913 // than or equal to its super depth are correct. 1914 if (klass->is_loaded() ) { 1915 ciType *inner = klass; 1916 while( inner->is_obj_array_klass() ) 1917 inner = inner->as_obj_array_klass()->base_element_type(); 1918 if( inner->is_instance_klass() && 1919 !inner->as_instance_klass()->flags().is_interface() ) { 1920 // Compute index into primary_supers array 1921 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1922 // Check for overflowing; use unsigned compare to handle the negative case. 1923 if( depth < ciKlass::primary_super_limit() && 1924 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1925 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1926 // (Folds up type checking code.) 1927 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1928 ciKlass *ss = klass->super_of_depth(depth); 1929 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1930 } 1931 } 1932 } 1933 1934 // If the type is enough to determine that the thing is not an array, 1935 // we can give the layout_helper a positive interval type. 1936 // This will help short-circuit some reflective code. 1937 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1938 && !klass->is_array_klass() // not directly typed as an array 1939 && !klass->is_interface() // specifically not Serializable & Cloneable 1940 && !klass->is_java_lang_Object() // not the supertype of all T[] 1941 ) { 1942 // Note: When interfaces are reliable, we can narrow the interface 1943 // test to (klass != Serializable && klass != Cloneable). 1944 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1945 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1946 // The key property of this type is that it folds up tests 1947 // for array-ness, since it proves that the layout_helper is positive. 1948 // Thus, a generic value like the basic object layout helper works fine. 1949 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1950 } 1951 } 1952 1953 // If we are loading from a freshly-allocated object, produce a zero, 1954 // if the load is provably beyond the header of the object. 1955 // (Also allow a variable load from a fresh array to produce zero.) 1956 const TypeOopPtr *tinst = tp->isa_oopptr(); 1957 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1958 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 1959 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 1960 Node* value = can_see_stored_value(mem,phase); 1961 if (value != NULL && value->is_Con()) { 1962 assert(value->bottom_type()->higher_equal(_type),"sanity"); 1963 return value->bottom_type(); 1964 } 1965 } 1966 1967 if (is_instance) { 1968 // If we have an instance type and our memory input is the 1969 // programs's initial memory state, there is no matching store, 1970 // so just return a zero of the appropriate type 1971 Node *mem = in(MemNode::Memory); 1972 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1973 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1974 return Type::get_zero_type(_type->basic_type()); 1975 } 1976 } 1977 1978 Node* alloc = is_new_object_mark_load(phase); 1979 if (alloc != NULL && !(alloc->Opcode() == Op_Allocate && UseBiasedLocking)) { 1980 return TypeX::make(markWord::prototype().value()); 1981 } 1982 1983 return _type; 1984 } 1985 1986 //------------------------------match_edge------------------------------------- 1987 // Do we Match on this edge index or not? Match only the address. 1988 uint LoadNode::match_edge(uint idx) const { 1989 return idx == MemNode::Address; 1990 } 1991 1992 //--------------------------LoadBNode::Ideal-------------------------------------- 1993 // 1994 // If the previous store is to the same address as this load, 1995 // and the value stored was larger than a byte, replace this load 1996 // with the value stored truncated to a byte. If no truncation is 1997 // needed, the replacement is done in LoadNode::Identity(). 1998 // 1999 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2000 Node* mem = in(MemNode::Memory); 2001 Node* value = can_see_stored_value(mem,phase); 2002 if( value && !phase->type(value)->higher_equal( _type ) ) { 2003 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) ); 2004 return new RShiftINode(result, phase->intcon(24)); 2005 } 2006 // Identity call will handle the case where truncation is not needed. 2007 return LoadNode::Ideal(phase, can_reshape); 2008 } 2009 2010 const Type* LoadBNode::Value(PhaseGVN* phase) const { 2011 Node* mem = in(MemNode::Memory); 2012 Node* value = can_see_stored_value(mem,phase); 2013 if (value != NULL && value->is_Con() && 2014 !value->bottom_type()->higher_equal(_type)) { 2015 // If the input to the store does not fit with the load's result type, 2016 // it must be truncated. We can't delay until Ideal call since 2017 // a singleton Value is needed for split_thru_phi optimization. 2018 int con = value->get_int(); 2019 return TypeInt::make((con << 24) >> 24); 2020 } 2021 return LoadNode::Value(phase); 2022 } 2023 2024 //--------------------------LoadUBNode::Ideal------------------------------------- 2025 // 2026 // If the previous store is to the same address as this load, 2027 // and the value stored was larger than a byte, replace this load 2028 // with the value stored truncated to a byte. If no truncation is 2029 // needed, the replacement is done in LoadNode::Identity(). 2030 // 2031 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2032 Node* mem = in(MemNode::Memory); 2033 Node* value = can_see_stored_value(mem, phase); 2034 if (value && !phase->type(value)->higher_equal(_type)) 2035 return new AndINode(value, phase->intcon(0xFF)); 2036 // Identity call will handle the case where truncation is not needed. 2037 return LoadNode::Ideal(phase, can_reshape); 2038 } 2039 2040 const Type* LoadUBNode::Value(PhaseGVN* phase) const { 2041 Node* mem = in(MemNode::Memory); 2042 Node* value = can_see_stored_value(mem,phase); 2043 if (value != NULL && value->is_Con() && 2044 !value->bottom_type()->higher_equal(_type)) { 2045 // If the input to the store does not fit with the load's result type, 2046 // it must be truncated. We can't delay until Ideal call since 2047 // a singleton Value is needed for split_thru_phi optimization. 2048 int con = value->get_int(); 2049 return TypeInt::make(con & 0xFF); 2050 } 2051 return LoadNode::Value(phase); 2052 } 2053 2054 //--------------------------LoadUSNode::Ideal------------------------------------- 2055 // 2056 // If the previous store is to the same address as this load, 2057 // and the value stored was larger than a char, replace this load 2058 // with the value stored truncated to a char. If no truncation is 2059 // needed, the replacement is done in LoadNode::Identity(). 2060 // 2061 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2062 Node* mem = in(MemNode::Memory); 2063 Node* value = can_see_stored_value(mem,phase); 2064 if( value && !phase->type(value)->higher_equal( _type ) ) 2065 return new AndINode(value,phase->intcon(0xFFFF)); 2066 // Identity call will handle the case where truncation is not needed. 2067 return LoadNode::Ideal(phase, can_reshape); 2068 } 2069 2070 const Type* LoadUSNode::Value(PhaseGVN* phase) const { 2071 Node* mem = in(MemNode::Memory); 2072 Node* value = can_see_stored_value(mem,phase); 2073 if (value != NULL && value->is_Con() && 2074 !value->bottom_type()->higher_equal(_type)) { 2075 // If the input to the store does not fit with the load's result type, 2076 // it must be truncated. We can't delay until Ideal call since 2077 // a singleton Value is needed for split_thru_phi optimization. 2078 int con = value->get_int(); 2079 return TypeInt::make(con & 0xFFFF); 2080 } 2081 return LoadNode::Value(phase); 2082 } 2083 2084 //--------------------------LoadSNode::Ideal-------------------------------------- 2085 // 2086 // If the previous store is to the same address as this load, 2087 // and the value stored was larger than a short, replace this load 2088 // with the value stored truncated to a short. If no truncation is 2089 // needed, the replacement is done in LoadNode::Identity(). 2090 // 2091 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2092 Node* mem = in(MemNode::Memory); 2093 Node* value = can_see_stored_value(mem,phase); 2094 if( value && !phase->type(value)->higher_equal( _type ) ) { 2095 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) ); 2096 return new RShiftINode(result, phase->intcon(16)); 2097 } 2098 // Identity call will handle the case where truncation is not needed. 2099 return LoadNode::Ideal(phase, can_reshape); 2100 } 2101 2102 const Type* LoadSNode::Value(PhaseGVN* phase) const { 2103 Node* mem = in(MemNode::Memory); 2104 Node* value = can_see_stored_value(mem,phase); 2105 if (value != NULL && value->is_Con() && 2106 !value->bottom_type()->higher_equal(_type)) { 2107 // If the input to the store does not fit with the load's result type, 2108 // it must be truncated. We can't delay until Ideal call since 2109 // a singleton Value is needed for split_thru_phi optimization. 2110 int con = value->get_int(); 2111 return TypeInt::make((con << 16) >> 16); 2112 } 2113 return LoadNode::Value(phase); 2114 } 2115 2116 //============================================================================= 2117 //----------------------------LoadKlassNode::make------------------------------ 2118 // Polymorphic factory method: 2119 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2120 // sanity check the alias category against the created node type 2121 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2122 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2123 #ifdef _LP64 2124 if (adr_type->is_ptr_to_narrowklass()) { 2125 assert(UseCompressedClassPointers, "no compressed klasses"); 2126 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2127 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2128 } 2129 #endif 2130 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2131 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2132 } 2133 2134 //------------------------------Value------------------------------------------ 2135 const Type* LoadKlassNode::Value(PhaseGVN* phase) const { 2136 return klass_value_common(phase); 2137 } 2138 2139 // In most cases, LoadKlassNode does not have the control input set. If the control 2140 // input is set, it must not be removed (by LoadNode::Ideal()). 2141 bool LoadKlassNode::can_remove_control() const { 2142 return false; 2143 } 2144 2145 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const { 2146 // Either input is TOP ==> the result is TOP 2147 const Type *t1 = phase->type( in(MemNode::Memory) ); 2148 if (t1 == Type::TOP) return Type::TOP; 2149 Node *adr = in(MemNode::Address); 2150 const Type *t2 = phase->type( adr ); 2151 if (t2 == Type::TOP) return Type::TOP; 2152 const TypePtr *tp = t2->is_ptr(); 2153 if (TypePtr::above_centerline(tp->ptr()) || 2154 tp->ptr() == TypePtr::Null) return Type::TOP; 2155 2156 // Return a more precise klass, if possible 2157 const TypeInstPtr *tinst = tp->isa_instptr(); 2158 if (tinst != NULL) { 2159 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2160 int offset = tinst->offset(); 2161 if (ik == phase->C->env()->Class_klass() 2162 && (offset == java_lang_Class::klass_offset() || 2163 offset == java_lang_Class::array_klass_offset())) { 2164 // We are loading a special hidden field from a Class mirror object, 2165 // the field which points to the VM's Klass metaobject. 2166 ciType* t = tinst->java_mirror_type(); 2167 // java_mirror_type returns non-null for compile-time Class constants. 2168 if (t != NULL) { 2169 // constant oop => constant klass 2170 if (offset == java_lang_Class::array_klass_offset()) { 2171 if (t->is_void()) { 2172 // We cannot create a void array. Since void is a primitive type return null 2173 // klass. Users of this result need to do a null check on the returned klass. 2174 return TypePtr::NULL_PTR; 2175 } 2176 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2177 } 2178 if (!t->is_klass()) { 2179 // a primitive Class (e.g., int.class) has NULL for a klass field 2180 return TypePtr::NULL_PTR; 2181 } 2182 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2183 return TypeKlassPtr::make(t->as_klass()); 2184 } 2185 // non-constant mirror, so we can't tell what's going on 2186 } 2187 if( !ik->is_loaded() ) 2188 return _type; // Bail out if not loaded 2189 if (offset == oopDesc::klass_offset_in_bytes()) { 2190 if (tinst->klass_is_exact()) { 2191 return TypeKlassPtr::make(ik); 2192 } 2193 // See if we can become precise: no subklasses and no interface 2194 // (Note: We need to support verified interfaces.) 2195 if (!ik->is_interface() && !ik->has_subklass()) { 2196 // Add a dependence; if any subclass added we need to recompile 2197 if (!ik->is_final()) { 2198 // %%% should use stronger assert_unique_concrete_subtype instead 2199 phase->C->dependencies()->assert_leaf_type(ik); 2200 } 2201 // Return precise klass 2202 return TypeKlassPtr::make(ik); 2203 } 2204 2205 // Return root of possible klass 2206 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2207 } 2208 } 2209 2210 // Check for loading klass from an array 2211 const TypeAryPtr *tary = tp->isa_aryptr(); 2212 if( tary != NULL ) { 2213 ciKlass *tary_klass = tary->klass(); 2214 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2215 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2216 if (tary->klass_is_exact()) { 2217 return TypeKlassPtr::make(tary_klass); 2218 } 2219 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2220 // If the klass is an object array, we defer the question to the 2221 // array component klass. 2222 if( ak->is_obj_array_klass() ) { 2223 assert( ak->is_loaded(), "" ); 2224 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2225 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2226 ciInstanceKlass* ik = base_k->as_instance_klass(); 2227 // See if we can become precise: no subklasses and no interface 2228 if (!ik->is_interface() && !ik->has_subklass()) { 2229 // Add a dependence; if any subclass added we need to recompile 2230 if (!ik->is_final()) { 2231 phase->C->dependencies()->assert_leaf_type(ik); 2232 } 2233 // Return precise array klass 2234 return TypeKlassPtr::make(ak); 2235 } 2236 } 2237 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2238 } else { // Found a type-array? 2239 assert( ak->is_type_array_klass(), "" ); 2240 return TypeKlassPtr::make(ak); // These are always precise 2241 } 2242 } 2243 } 2244 2245 // Check for loading klass from an array klass 2246 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2247 if (tkls != NULL && !StressReflectiveCode) { 2248 ciKlass* klass = tkls->klass(); 2249 if( !klass->is_loaded() ) 2250 return _type; // Bail out if not loaded 2251 if( klass->is_obj_array_klass() && 2252 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2253 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2254 // // Always returning precise element type is incorrect, 2255 // // e.g., element type could be object and array may contain strings 2256 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2257 2258 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2259 // according to the element type's subclassing. 2260 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2261 } 2262 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2263 tkls->offset() == in_bytes(Klass::super_offset())) { 2264 ciKlass* sup = klass->as_instance_klass()->super(); 2265 // The field is Klass::_super. Return its (constant) value. 2266 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2267 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2268 } 2269 } 2270 2271 // Bailout case 2272 return LoadNode::Value(phase); 2273 } 2274 2275 //------------------------------Identity--------------------------------------- 2276 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2277 // Also feed through the klass in Allocate(...klass...)._klass. 2278 Node* LoadKlassNode::Identity(PhaseGVN* phase) { 2279 return klass_identity_common(phase); 2280 } 2281 2282 Node* LoadNode::klass_identity_common(PhaseGVN* phase) { 2283 Node* x = LoadNode::Identity(phase); 2284 if (x != this) return x; 2285 2286 // Take apart the address into an oop and and offset. 2287 // Return 'this' if we cannot. 2288 Node* adr = in(MemNode::Address); 2289 intptr_t offset = 0; 2290 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2291 if (base == NULL) return this; 2292 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2293 if (toop == NULL) return this; 2294 2295 // Step over potential GC barrier for OopHandle resolve 2296 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 2297 if (bs->is_gc_barrier_node(base)) { 2298 base = bs->step_over_gc_barrier(base); 2299 } 2300 2301 // We can fetch the klass directly through an AllocateNode. 2302 // This works even if the klass is not constant (clone or newArray). 2303 if (offset == oopDesc::klass_offset_in_bytes()) { 2304 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2305 if (allocated_klass != NULL) { 2306 return allocated_klass; 2307 } 2308 } 2309 2310 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2311 // See inline_native_Class_query for occurrences of these patterns. 2312 // Java Example: x.getClass().isAssignableFrom(y) 2313 // 2314 // This improves reflective code, often making the Class 2315 // mirror go completely dead. (Current exception: Class 2316 // mirrors may appear in debug info, but we could clean them out by 2317 // introducing a new debug info operator for Klass.java_mirror). 2318 2319 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2320 && offset == java_lang_Class::klass_offset()) { 2321 if (base->is_Load()) { 2322 Node* base2 = base->in(MemNode::Address); 2323 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */ 2324 Node* adr2 = base2->in(MemNode::Address); 2325 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2326 if (tkls != NULL && !tkls->empty() 2327 && (tkls->klass()->is_instance_klass() || 2328 tkls->klass()->is_array_klass()) 2329 && adr2->is_AddP() 2330 ) { 2331 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2332 if (tkls->offset() == mirror_field) { 2333 return adr2->in(AddPNode::Base); 2334 } 2335 } 2336 } 2337 } 2338 } 2339 2340 return this; 2341 } 2342 2343 2344 //------------------------------Value------------------------------------------ 2345 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const { 2346 const Type *t = klass_value_common(phase); 2347 if (t == Type::TOP) 2348 return t; 2349 2350 return t->make_narrowklass(); 2351 } 2352 2353 //------------------------------Identity--------------------------------------- 2354 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2355 // Also feed through the klass in Allocate(...klass...)._klass. 2356 Node* LoadNKlassNode::Identity(PhaseGVN* phase) { 2357 Node *x = klass_identity_common(phase); 2358 2359 const Type *t = phase->type( x ); 2360 if( t == Type::TOP ) return x; 2361 if( t->isa_narrowklass()) return x; 2362 assert (!t->isa_narrowoop(), "no narrow oop here"); 2363 2364 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2365 } 2366 2367 //------------------------------Value----------------------------------------- 2368 const Type* LoadRangeNode::Value(PhaseGVN* phase) const { 2369 // Either input is TOP ==> the result is TOP 2370 const Type *t1 = phase->type( in(MemNode::Memory) ); 2371 if( t1 == Type::TOP ) return Type::TOP; 2372 Node *adr = in(MemNode::Address); 2373 const Type *t2 = phase->type( adr ); 2374 if( t2 == Type::TOP ) return Type::TOP; 2375 const TypePtr *tp = t2->is_ptr(); 2376 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2377 const TypeAryPtr *tap = tp->isa_aryptr(); 2378 if( !tap ) return _type; 2379 return tap->size(); 2380 } 2381 2382 //-------------------------------Ideal--------------------------------------- 2383 // Feed through the length in AllocateArray(...length...)._length. 2384 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2385 Node* p = MemNode::Ideal_common(phase, can_reshape); 2386 if (p) return (p == NodeSentinel) ? NULL : p; 2387 2388 // Take apart the address into an oop and and offset. 2389 // Return 'this' if we cannot. 2390 Node* adr = in(MemNode::Address); 2391 intptr_t offset = 0; 2392 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2393 if (base == NULL) return NULL; 2394 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2395 if (tary == NULL) return NULL; 2396 2397 // We can fetch the length directly through an AllocateArrayNode. 2398 // This works even if the length is not constant (clone or newArray). 2399 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2400 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2401 if (alloc != NULL) { 2402 Node* allocated_length = alloc->Ideal_length(); 2403 Node* len = alloc->make_ideal_length(tary, phase); 2404 if (allocated_length != len) { 2405 // New CastII improves on this. 2406 return len; 2407 } 2408 } 2409 } 2410 2411 return NULL; 2412 } 2413 2414 //------------------------------Identity--------------------------------------- 2415 // Feed through the length in AllocateArray(...length...)._length. 2416 Node* LoadRangeNode::Identity(PhaseGVN* phase) { 2417 Node* x = LoadINode::Identity(phase); 2418 if (x != this) return x; 2419 2420 // Take apart the address into an oop and and offset. 2421 // Return 'this' if we cannot. 2422 Node* adr = in(MemNode::Address); 2423 intptr_t offset = 0; 2424 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2425 if (base == NULL) return this; 2426 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2427 if (tary == NULL) return this; 2428 2429 // We can fetch the length directly through an AllocateArrayNode. 2430 // This works even if the length is not constant (clone or newArray). 2431 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2432 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2433 if (alloc != NULL) { 2434 Node* allocated_length = alloc->Ideal_length(); 2435 // Do not allow make_ideal_length to allocate a CastII node. 2436 Node* len = alloc->make_ideal_length(tary, phase, false); 2437 if (allocated_length == len) { 2438 // Return allocated_length only if it would not be improved by a CastII. 2439 return allocated_length; 2440 } 2441 } 2442 } 2443 2444 return this; 2445 2446 } 2447 2448 //============================================================================= 2449 //---------------------------StoreNode::make----------------------------------- 2450 // Polymorphic factory method: 2451 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2452 assert((mo == unordered || mo == release), "unexpected"); 2453 Compile* C = gvn.C; 2454 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2455 ctl != NULL, "raw memory operations should have control edge"); 2456 2457 switch (bt) { 2458 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case 2459 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2460 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2461 case T_CHAR: 2462 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2463 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2464 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2465 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2466 case T_METADATA: 2467 case T_ADDRESS: 2468 case T_OBJECT: 2469 #ifdef _LP64 2470 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2471 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2472 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2473 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2474 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2475 adr->bottom_type()->isa_rawptr())) { 2476 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2477 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2478 } 2479 #endif 2480 { 2481 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2482 } 2483 default: 2484 ShouldNotReachHere(); 2485 return (StoreNode*)NULL; 2486 } 2487 } 2488 2489 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2490 bool require_atomic = true; 2491 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2492 } 2493 2494 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2495 bool require_atomic = true; 2496 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2497 } 2498 2499 2500 //--------------------------bottom_type---------------------------------------- 2501 const Type *StoreNode::bottom_type() const { 2502 return Type::MEMORY; 2503 } 2504 2505 //------------------------------hash------------------------------------------- 2506 uint StoreNode::hash() const { 2507 // unroll addition of interesting fields 2508 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2509 2510 // Since they are not commoned, do not hash them: 2511 return NO_HASH; 2512 } 2513 2514 //------------------------------Ideal------------------------------------------ 2515 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2516 // When a store immediately follows a relevant allocation/initialization, 2517 // try to capture it into the initialization, or hoist it above. 2518 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2519 Node* p = MemNode::Ideal_common(phase, can_reshape); 2520 if (p) return (p == NodeSentinel) ? NULL : p; 2521 2522 Node* mem = in(MemNode::Memory); 2523 Node* address = in(MemNode::Address); 2524 // Back-to-back stores to same address? Fold em up. Generally 2525 // unsafe if I have intervening uses... Also disallowed for StoreCM 2526 // since they must follow each StoreP operation. Redundant StoreCMs 2527 // are eliminated just before matching in final_graph_reshape. 2528 { 2529 Node* st = mem; 2530 // If Store 'st' has more than one use, we cannot fold 'st' away. 2531 // For example, 'st' might be the final state at a conditional 2532 // return. Or, 'st' might be used by some node which is live at 2533 // the same time 'st' is live, which might be unschedulable. So, 2534 // require exactly ONE user until such time as we clone 'mem' for 2535 // each of 'mem's uses (thus making the exactly-1-user-rule hold 2536 // true). 2537 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) { 2538 // Looking at a dead closed cycle of memory? 2539 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2540 assert(Opcode() == st->Opcode() || 2541 st->Opcode() == Op_StoreVector || 2542 Opcode() == Op_StoreVector || 2543 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw || 2544 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode 2545 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy 2546 (is_mismatched_access() || st->as_Store()->is_mismatched_access()), 2547 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]); 2548 2549 if (st->in(MemNode::Address)->eqv_uncast(address) && 2550 st->as_Store()->memory_size() <= this->memory_size()) { 2551 Node* use = st->raw_out(0); 2552 phase->igvn_rehash_node_delayed(use); 2553 if (can_reshape) { 2554 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN()); 2555 } else { 2556 // It's OK to do this in the parser, since DU info is always accurate, 2557 // and the parser always refers to nodes via SafePointNode maps. 2558 use->set_req(MemNode::Memory, st->in(MemNode::Memory)); 2559 } 2560 return this; 2561 } 2562 st = st->in(MemNode::Memory); 2563 } 2564 } 2565 2566 2567 // Capture an unaliased, unconditional, simple store into an initializer. 2568 // Or, if it is independent of the allocation, hoist it above the allocation. 2569 if (ReduceFieldZeroing && /*can_reshape &&*/ 2570 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2571 InitializeNode* init = mem->in(0)->as_Initialize(); 2572 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2573 if (offset > 0) { 2574 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2575 // If the InitializeNode captured me, it made a raw copy of me, 2576 // and I need to disappear. 2577 if (moved != NULL) { 2578 // %%% hack to ensure that Ideal returns a new node: 2579 mem = MergeMemNode::make(mem); 2580 return mem; // fold me away 2581 } 2582 } 2583 } 2584 2585 return NULL; // No further progress 2586 } 2587 2588 //------------------------------Value----------------------------------------- 2589 const Type* StoreNode::Value(PhaseGVN* phase) const { 2590 // Either input is TOP ==> the result is TOP 2591 const Type *t1 = phase->type( in(MemNode::Memory) ); 2592 if( t1 == Type::TOP ) return Type::TOP; 2593 const Type *t2 = phase->type( in(MemNode::Address) ); 2594 if( t2 == Type::TOP ) return Type::TOP; 2595 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2596 if( t3 == Type::TOP ) return Type::TOP; 2597 return Type::MEMORY; 2598 } 2599 2600 //------------------------------Identity--------------------------------------- 2601 // Remove redundant stores: 2602 // Store(m, p, Load(m, p)) changes to m. 2603 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2604 Node* StoreNode::Identity(PhaseGVN* phase) { 2605 Node* mem = in(MemNode::Memory); 2606 Node* adr = in(MemNode::Address); 2607 Node* val = in(MemNode::ValueIn); 2608 2609 Node* result = this; 2610 2611 // Load then Store? Then the Store is useless 2612 if (val->is_Load() && 2613 val->in(MemNode::Address)->eqv_uncast(adr) && 2614 val->in(MemNode::Memory )->eqv_uncast(mem) && 2615 val->as_Load()->store_Opcode() == Opcode()) { 2616 result = mem; 2617 } 2618 2619 // Two stores in a row of the same value? 2620 if (result == this && 2621 mem->is_Store() && 2622 mem->in(MemNode::Address)->eqv_uncast(adr) && 2623 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2624 mem->Opcode() == Opcode()) { 2625 result = mem; 2626 } 2627 2628 // Store of zero anywhere into a freshly-allocated object? 2629 // Then the store is useless. 2630 // (It must already have been captured by the InitializeNode.) 2631 if (result == this && 2632 ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2633 // a newly allocated object is already all-zeroes everywhere 2634 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2635 result = mem; 2636 } 2637 2638 if (result == this) { 2639 // the store may also apply to zero-bits in an earlier object 2640 Node* prev_mem = find_previous_store(phase); 2641 // Steps (a), (b): Walk past independent stores to find an exact match. 2642 if (prev_mem != NULL) { 2643 Node* prev_val = can_see_stored_value(prev_mem, phase); 2644 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2645 // prev_val and val might differ by a cast; it would be good 2646 // to keep the more informative of the two. 2647 result = mem; 2648 } 2649 } 2650 } 2651 } 2652 2653 if (result != this && phase->is_IterGVN() != NULL) { 2654 MemBarNode* trailing = trailing_membar(); 2655 if (trailing != NULL) { 2656 #ifdef ASSERT 2657 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr(); 2658 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects"); 2659 #endif 2660 PhaseIterGVN* igvn = phase->is_IterGVN(); 2661 trailing->remove(igvn); 2662 } 2663 } 2664 2665 return result; 2666 } 2667 2668 //------------------------------match_edge------------------------------------- 2669 // Do we Match on this edge index or not? Match only memory & value 2670 uint StoreNode::match_edge(uint idx) const { 2671 return idx == MemNode::Address || idx == MemNode::ValueIn; 2672 } 2673 2674 //------------------------------cmp-------------------------------------------- 2675 // Do not common stores up together. They generally have to be split 2676 // back up anyways, so do not bother. 2677 bool StoreNode::cmp( const Node &n ) const { 2678 return (&n == this); // Always fail except on self 2679 } 2680 2681 //------------------------------Ideal_masked_input----------------------------- 2682 // Check for a useless mask before a partial-word store 2683 // (StoreB ... (AndI valIn conIa) ) 2684 // If (conIa & mask == mask) this simplifies to 2685 // (StoreB ... (valIn) ) 2686 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2687 Node *val = in(MemNode::ValueIn); 2688 if( val->Opcode() == Op_AndI ) { 2689 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2690 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2691 set_req(MemNode::ValueIn, val->in(1)); 2692 return this; 2693 } 2694 } 2695 return NULL; 2696 } 2697 2698 2699 //------------------------------Ideal_sign_extended_input---------------------- 2700 // Check for useless sign-extension before a partial-word store 2701 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2702 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2703 // (StoreB ... (valIn) ) 2704 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2705 Node *val = in(MemNode::ValueIn); 2706 if( val->Opcode() == Op_RShiftI ) { 2707 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2708 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2709 Node *shl = val->in(1); 2710 if( shl->Opcode() == Op_LShiftI ) { 2711 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2712 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2713 set_req(MemNode::ValueIn, shl->in(1)); 2714 return this; 2715 } 2716 } 2717 } 2718 } 2719 return NULL; 2720 } 2721 2722 //------------------------------value_never_loaded----------------------------------- 2723 // Determine whether there are any possible loads of the value stored. 2724 // For simplicity, we actually check if there are any loads from the 2725 // address stored to, not just for loads of the value stored by this node. 2726 // 2727 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2728 Node *adr = in(Address); 2729 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2730 if (adr_oop == NULL) 2731 return false; 2732 if (!adr_oop->is_known_instance_field()) 2733 return false; // if not a distinct instance, there may be aliases of the address 2734 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2735 Node *use = adr->fast_out(i); 2736 if (use->is_Load() || use->is_LoadStore()) { 2737 return false; 2738 } 2739 } 2740 return true; 2741 } 2742 2743 MemBarNode* StoreNode::trailing_membar() const { 2744 if (is_release()) { 2745 MemBarNode* trailing_mb = NULL; 2746 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2747 Node* u = fast_out(i); 2748 if (u->is_MemBar()) { 2749 if (u->as_MemBar()->trailing_store()) { 2750 assert(u->Opcode() == Op_MemBarVolatile, ""); 2751 assert(trailing_mb == NULL, "only one"); 2752 trailing_mb = u->as_MemBar(); 2753 #ifdef ASSERT 2754 Node* leading = u->as_MemBar()->leading_membar(); 2755 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 2756 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair"); 2757 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair"); 2758 #endif 2759 } else { 2760 assert(u->as_MemBar()->standalone(), ""); 2761 } 2762 } 2763 } 2764 return trailing_mb; 2765 } 2766 return NULL; 2767 } 2768 2769 2770 //============================================================================= 2771 //------------------------------Ideal------------------------------------------ 2772 // If the store is from an AND mask that leaves the low bits untouched, then 2773 // we can skip the AND operation. If the store is from a sign-extension 2774 // (a left shift, then right shift) we can skip both. 2775 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2776 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2777 if( progress != NULL ) return progress; 2778 2779 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2780 if( progress != NULL ) return progress; 2781 2782 // Finally check the default case 2783 return StoreNode::Ideal(phase, can_reshape); 2784 } 2785 2786 //============================================================================= 2787 //------------------------------Ideal------------------------------------------ 2788 // If the store is from an AND mask that leaves the low bits untouched, then 2789 // we can skip the AND operation 2790 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2791 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2792 if( progress != NULL ) return progress; 2793 2794 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2795 if( progress != NULL ) return progress; 2796 2797 // Finally check the default case 2798 return StoreNode::Ideal(phase, can_reshape); 2799 } 2800 2801 //============================================================================= 2802 //------------------------------Identity--------------------------------------- 2803 Node* StoreCMNode::Identity(PhaseGVN* phase) { 2804 // No need to card mark when storing a null ptr 2805 Node* my_store = in(MemNode::OopStore); 2806 if (my_store->is_Store()) { 2807 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2808 if( t1 == TypePtr::NULL_PTR ) { 2809 return in(MemNode::Memory); 2810 } 2811 } 2812 return this; 2813 } 2814 2815 //============================================================================= 2816 //------------------------------Ideal--------------------------------------- 2817 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2818 Node* progress = StoreNode::Ideal(phase, can_reshape); 2819 if (progress != NULL) return progress; 2820 2821 Node* my_store = in(MemNode::OopStore); 2822 if (my_store->is_MergeMem()) { 2823 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2824 set_req(MemNode::OopStore, mem); 2825 return this; 2826 } 2827 2828 return NULL; 2829 } 2830 2831 //------------------------------Value----------------------------------------- 2832 const Type* StoreCMNode::Value(PhaseGVN* phase) const { 2833 // Either input is TOP ==> the result is TOP 2834 const Type *t = phase->type( in(MemNode::Memory) ); 2835 if( t == Type::TOP ) return Type::TOP; 2836 t = phase->type( in(MemNode::Address) ); 2837 if( t == Type::TOP ) return Type::TOP; 2838 t = phase->type( in(MemNode::ValueIn) ); 2839 if( t == Type::TOP ) return Type::TOP; 2840 // If extra input is TOP ==> the result is TOP 2841 t = phase->type( in(MemNode::OopStore) ); 2842 if( t == Type::TOP ) return Type::TOP; 2843 2844 return StoreNode::Value( phase ); 2845 } 2846 2847 2848 //============================================================================= 2849 //----------------------------------SCMemProjNode------------------------------ 2850 const Type* SCMemProjNode::Value(PhaseGVN* phase) const 2851 { 2852 return bottom_type(); 2853 } 2854 2855 //============================================================================= 2856 //----------------------------------LoadStoreNode------------------------------ 2857 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2858 : Node(required), 2859 _type(rt), 2860 _adr_type(at), 2861 _barrier(0) 2862 { 2863 init_req(MemNode::Control, c ); 2864 init_req(MemNode::Memory , mem); 2865 init_req(MemNode::Address, adr); 2866 init_req(MemNode::ValueIn, val); 2867 init_class_id(Class_LoadStore); 2868 } 2869 2870 uint LoadStoreNode::ideal_reg() const { 2871 return _type->ideal_reg(); 2872 } 2873 2874 bool LoadStoreNode::result_not_used() const { 2875 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2876 Node *x = fast_out(i); 2877 if (x->Opcode() == Op_SCMemProj) continue; 2878 return false; 2879 } 2880 return true; 2881 } 2882 2883 MemBarNode* LoadStoreNode::trailing_membar() const { 2884 MemBarNode* trailing = NULL; 2885 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2886 Node* u = fast_out(i); 2887 if (u->is_MemBar()) { 2888 if (u->as_MemBar()->trailing_load_store()) { 2889 assert(u->Opcode() == Op_MemBarAcquire, ""); 2890 assert(trailing == NULL, "only one"); 2891 trailing = u->as_MemBar(); 2892 #ifdef ASSERT 2893 Node* leading = trailing->leading_membar(); 2894 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 2895 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair"); 2896 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair"); 2897 #endif 2898 } else { 2899 assert(u->as_MemBar()->standalone(), "wrong barrier kind"); 2900 } 2901 } 2902 } 2903 2904 return trailing; 2905 } 2906 2907 uint LoadStoreNode::size_of() const { return sizeof(*this); } 2908 2909 //============================================================================= 2910 //----------------------------------LoadStoreConditionalNode-------------------- 2911 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 2912 init_req(ExpectedIn, ex ); 2913 } 2914 2915 //============================================================================= 2916 //-------------------------------adr_type-------------------------------------- 2917 const TypePtr* ClearArrayNode::adr_type() const { 2918 Node *adr = in(3); 2919 if (adr == NULL) return NULL; // node is dead 2920 return MemNode::calculate_adr_type(adr->bottom_type()); 2921 } 2922 2923 //------------------------------match_edge------------------------------------- 2924 // Do we Match on this edge index or not? Do not match memory 2925 uint ClearArrayNode::match_edge(uint idx) const { 2926 return idx > 1; 2927 } 2928 2929 //------------------------------Identity--------------------------------------- 2930 // Clearing a zero length array does nothing 2931 Node* ClearArrayNode::Identity(PhaseGVN* phase) { 2932 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2933 } 2934 2935 //------------------------------Idealize--------------------------------------- 2936 // Clearing a short array is faster with stores 2937 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2938 // Already know this is a large node, do not try to ideal it 2939 if (!IdealizeClearArrayNode || _is_large) return NULL; 2940 2941 const int unit = BytesPerLong; 2942 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2943 if (!t) return NULL; 2944 if (!t->is_con()) return NULL; 2945 intptr_t raw_count = t->get_con(); 2946 intptr_t size = raw_count; 2947 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2948 // Clearing nothing uses the Identity call. 2949 // Negative clears are possible on dead ClearArrays 2950 // (see jck test stmt114.stmt11402.val). 2951 if (size <= 0 || size % unit != 0) return NULL; 2952 intptr_t count = size / unit; 2953 // Length too long; communicate this to matchers and assemblers. 2954 // Assemblers are responsible to produce fast hardware clears for it. 2955 if (size > InitArrayShortSize) { 2956 return new ClearArrayNode(in(0), in(1), in(2), in(3), true); 2957 } 2958 Node *mem = in(1); 2959 if( phase->type(mem)==Type::TOP ) return NULL; 2960 Node *adr = in(3); 2961 const Type* at = phase->type(adr); 2962 if( at==Type::TOP ) return NULL; 2963 const TypePtr* atp = at->isa_ptr(); 2964 // adjust atp to be the correct array element address type 2965 if (atp == NULL) atp = TypePtr::BOTTOM; 2966 else atp = atp->add_offset(Type::OffsetBot); 2967 // Get base for derived pointer purposes 2968 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2969 Node *base = adr->in(1); 2970 2971 Node *zero = phase->makecon(TypeLong::ZERO); 2972 Node *off = phase->MakeConX(BytesPerLong); 2973 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2974 count--; 2975 while( count-- ) { 2976 mem = phase->transform(mem); 2977 adr = phase->transform(new AddPNode(base,adr,off)); 2978 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2979 } 2980 return mem; 2981 } 2982 2983 //----------------------------step_through---------------------------------- 2984 // Return allocation input memory edge if it is different instance 2985 // or itself if it is the one we are looking for. 2986 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2987 Node* n = *np; 2988 assert(n->is_ClearArray(), "sanity"); 2989 intptr_t offset; 2990 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2991 // This method is called only before Allocate nodes are expanded 2992 // during macro nodes expansion. Before that ClearArray nodes are 2993 // only generated in PhaseMacroExpand::generate_arraycopy() (before 2994 // Allocate nodes are expanded) which follows allocations. 2995 assert(alloc != NULL, "should have allocation"); 2996 if (alloc->_idx == instance_id) { 2997 // Can not bypass initialization of the instance we are looking for. 2998 return false; 2999 } 3000 // Otherwise skip it. 3001 InitializeNode* init = alloc->initialization(); 3002 if (init != NULL) 3003 *np = init->in(TypeFunc::Memory); 3004 else 3005 *np = alloc->in(TypeFunc::Memory); 3006 return true; 3007 } 3008 3009 //----------------------------clear_memory------------------------------------- 3010 // Generate code to initialize object storage to zero. 3011 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3012 intptr_t start_offset, 3013 Node* end_offset, 3014 PhaseGVN* phase) { 3015 intptr_t offset = start_offset; 3016 3017 int unit = BytesPerLong; 3018 if ((offset % unit) != 0) { 3019 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 3020 adr = phase->transform(adr); 3021 const TypePtr* atp = TypeRawPtr::BOTTOM; 3022 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 3023 mem = phase->transform(mem); 3024 offset += BytesPerInt; 3025 } 3026 assert((offset % unit) == 0, ""); 3027 3028 // Initialize the remaining stuff, if any, with a ClearArray. 3029 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 3030 } 3031 3032 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3033 Node* start_offset, 3034 Node* end_offset, 3035 PhaseGVN* phase) { 3036 if (start_offset == end_offset) { 3037 // nothing to do 3038 return mem; 3039 } 3040 3041 int unit = BytesPerLong; 3042 Node* zbase = start_offset; 3043 Node* zend = end_offset; 3044 3045 // Scale to the unit required by the CPU: 3046 if (!Matcher::init_array_count_is_in_bytes) { 3047 Node* shift = phase->intcon(exact_log2(unit)); 3048 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 3049 zend = phase->transform(new URShiftXNode(zend, shift) ); 3050 } 3051 3052 // Bulk clear double-words 3053 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 3054 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 3055 mem = new ClearArrayNode(ctl, mem, zsize, adr, false); 3056 return phase->transform(mem); 3057 } 3058 3059 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3060 intptr_t start_offset, 3061 intptr_t end_offset, 3062 PhaseGVN* phase) { 3063 if (start_offset == end_offset) { 3064 // nothing to do 3065 return mem; 3066 } 3067 3068 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 3069 intptr_t done_offset = end_offset; 3070 if ((done_offset % BytesPerLong) != 0) { 3071 done_offset -= BytesPerInt; 3072 } 3073 if (done_offset > start_offset) { 3074 mem = clear_memory(ctl, mem, dest, 3075 start_offset, phase->MakeConX(done_offset), phase); 3076 } 3077 if (done_offset < end_offset) { // emit the final 32-bit store 3078 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 3079 adr = phase->transform(adr); 3080 const TypePtr* atp = TypeRawPtr::BOTTOM; 3081 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 3082 mem = phase->transform(mem); 3083 done_offset += BytesPerInt; 3084 } 3085 assert(done_offset == end_offset, ""); 3086 return mem; 3087 } 3088 3089 //============================================================================= 3090 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 3091 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 3092 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone) 3093 #ifdef ASSERT 3094 , _pair_idx(0) 3095 #endif 3096 { 3097 init_class_id(Class_MemBar); 3098 Node* top = C->top(); 3099 init_req(TypeFunc::I_O,top); 3100 init_req(TypeFunc::FramePtr,top); 3101 init_req(TypeFunc::ReturnAdr,top); 3102 if (precedent != NULL) 3103 init_req(TypeFunc::Parms, precedent); 3104 } 3105 3106 //------------------------------cmp-------------------------------------------- 3107 uint MemBarNode::hash() const { return NO_HASH; } 3108 bool MemBarNode::cmp( const Node &n ) const { 3109 return (&n == this); // Always fail except on self 3110 } 3111 3112 //------------------------------make------------------------------------------- 3113 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 3114 switch (opcode) { 3115 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 3116 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 3117 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 3118 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 3119 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 3120 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 3121 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 3122 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 3123 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn); 3124 case Op_Initialize: return new InitializeNode(C, atp, pn); 3125 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 3126 default: ShouldNotReachHere(); return NULL; 3127 } 3128 } 3129 3130 void MemBarNode::remove(PhaseIterGVN *igvn) { 3131 if (outcnt() != 2) { 3132 return; 3133 } 3134 if (trailing_store() || trailing_load_store()) { 3135 MemBarNode* leading = leading_membar(); 3136 if (leading != NULL) { 3137 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars"); 3138 leading->remove(igvn); 3139 } 3140 } 3141 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 3142 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 3143 } 3144 3145 //------------------------------Ideal------------------------------------------ 3146 // Return a node which is more "ideal" than the current node. Strip out 3147 // control copies 3148 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3149 if (remove_dead_region(phase, can_reshape)) return this; 3150 // Don't bother trying to transform a dead node 3151 if (in(0) && in(0)->is_top()) { 3152 return NULL; 3153 } 3154 3155 bool progress = false; 3156 // Eliminate volatile MemBars for scalar replaced objects. 3157 if (can_reshape && req() == (Precedent+1)) { 3158 bool eliminate = false; 3159 int opc = Opcode(); 3160 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 3161 // Volatile field loads and stores. 3162 Node* my_mem = in(MemBarNode::Precedent); 3163 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 3164 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 3165 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 3166 // replace this Precedent (decodeN) with the Load instead. 3167 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 3168 Node* load_node = my_mem->in(1); 3169 set_req(MemBarNode::Precedent, load_node); 3170 phase->is_IterGVN()->_worklist.push(my_mem); 3171 my_mem = load_node; 3172 } else { 3173 assert(my_mem->unique_out() == this, "sanity"); 3174 del_req(Precedent); 3175 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 3176 my_mem = NULL; 3177 } 3178 progress = true; 3179 } 3180 if (my_mem != NULL && my_mem->is_Mem()) { 3181 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 3182 // Check for scalar replaced object reference. 3183 if( t_oop != NULL && t_oop->is_known_instance_field() && 3184 t_oop->offset() != Type::OffsetBot && 3185 t_oop->offset() != Type::OffsetTop) { 3186 eliminate = true; 3187 } 3188 } 3189 } else if (opc == Op_MemBarRelease) { 3190 // Final field stores. 3191 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 3192 if ((alloc != NULL) && alloc->is_Allocate() && 3193 alloc->as_Allocate()->does_not_escape_thread()) { 3194 // The allocated object does not escape. 3195 eliminate = true; 3196 } 3197 } 3198 if (eliminate) { 3199 // Replace MemBar projections by its inputs. 3200 PhaseIterGVN* igvn = phase->is_IterGVN(); 3201 remove(igvn); 3202 // Must return either the original node (now dead) or a new node 3203 // (Do not return a top here, since that would break the uniqueness of top.) 3204 return new ConINode(TypeInt::ZERO); 3205 } 3206 } 3207 return progress ? this : NULL; 3208 } 3209 3210 //------------------------------Value------------------------------------------ 3211 const Type* MemBarNode::Value(PhaseGVN* phase) const { 3212 if( !in(0) ) return Type::TOP; 3213 if( phase->type(in(0)) == Type::TOP ) 3214 return Type::TOP; 3215 return TypeTuple::MEMBAR; 3216 } 3217 3218 //------------------------------match------------------------------------------ 3219 // Construct projections for memory. 3220 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3221 switch (proj->_con) { 3222 case TypeFunc::Control: 3223 case TypeFunc::Memory: 3224 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3225 } 3226 ShouldNotReachHere(); 3227 return NULL; 3228 } 3229 3230 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3231 trailing->_kind = TrailingStore; 3232 leading->_kind = LeadingStore; 3233 #ifdef ASSERT 3234 trailing->_pair_idx = leading->_idx; 3235 leading->_pair_idx = leading->_idx; 3236 #endif 3237 } 3238 3239 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3240 trailing->_kind = TrailingLoadStore; 3241 leading->_kind = LeadingLoadStore; 3242 #ifdef ASSERT 3243 trailing->_pair_idx = leading->_idx; 3244 leading->_pair_idx = leading->_idx; 3245 #endif 3246 } 3247 3248 MemBarNode* MemBarNode::trailing_membar() const { 3249 ResourceMark rm; 3250 Node* trailing = (Node*)this; 3251 VectorSet seen(Thread::current()->resource_area()); 3252 Node_Stack multis(0); 3253 do { 3254 Node* c = trailing; 3255 uint i = 0; 3256 do { 3257 trailing = NULL; 3258 for (; i < c->outcnt(); i++) { 3259 Node* next = c->raw_out(i); 3260 if (next != c && next->is_CFG()) { 3261 if (c->is_MultiBranch()) { 3262 if (multis.node() == c) { 3263 multis.set_index(i+1); 3264 } else { 3265 multis.push(c, i+1); 3266 } 3267 } 3268 trailing = next; 3269 break; 3270 } 3271 } 3272 if (trailing != NULL && !seen.test_set(trailing->_idx)) { 3273 break; 3274 } 3275 while (multis.size() > 0) { 3276 c = multis.node(); 3277 i = multis.index(); 3278 if (i < c->req()) { 3279 break; 3280 } 3281 multis.pop(); 3282 } 3283 } while (multis.size() > 0); 3284 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing()); 3285 3286 MemBarNode* mb = trailing->as_MemBar(); 3287 assert((mb->_kind == TrailingStore && _kind == LeadingStore) || 3288 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar"); 3289 assert(mb->_pair_idx == _pair_idx, "bad trailing membar"); 3290 return mb; 3291 } 3292 3293 MemBarNode* MemBarNode::leading_membar() const { 3294 ResourceMark rm; 3295 VectorSet seen(Thread::current()->resource_area()); 3296 Node_Stack regions(0); 3297 Node* leading = in(0); 3298 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) { 3299 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) { 3300 leading = NULL; 3301 while (regions.size() > 0 && leading == NULL) { 3302 Node* r = regions.node(); 3303 uint i = regions.index(); 3304 if (i < r->req()) { 3305 leading = r->in(i); 3306 regions.set_index(i+1); 3307 } else { 3308 regions.pop(); 3309 } 3310 } 3311 if (leading == NULL) { 3312 assert(regions.size() == 0, "all paths should have been tried"); 3313 return NULL; 3314 } 3315 } 3316 if (leading->is_Region()) { 3317 regions.push(leading, 2); 3318 leading = leading->in(1); 3319 } else { 3320 leading = leading->in(0); 3321 } 3322 } 3323 #ifdef ASSERT 3324 Unique_Node_List wq; 3325 wq.push((Node*)this); 3326 uint found = 0; 3327 for (uint i = 0; i < wq.size(); i++) { 3328 Node* n = wq.at(i); 3329 if (n->is_Region()) { 3330 for (uint j = 1; j < n->req(); j++) { 3331 Node* in = n->in(j); 3332 if (in != NULL && !in->is_top()) { 3333 wq.push(in); 3334 } 3335 } 3336 } else { 3337 if (n->is_MemBar() && n->as_MemBar()->leading()) { 3338 assert(n == leading, "consistency check failed"); 3339 found++; 3340 } else { 3341 Node* in = n->in(0); 3342 if (in != NULL && !in->is_top()) { 3343 wq.push(in); 3344 } 3345 } 3346 } 3347 } 3348 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed"); 3349 #endif 3350 if (leading == NULL) { 3351 return NULL; 3352 } 3353 MemBarNode* mb = leading->as_MemBar(); 3354 assert((mb->_kind == LeadingStore && _kind == TrailingStore) || 3355 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar"); 3356 assert(mb->_pair_idx == _pair_idx, "bad leading membar"); 3357 return mb; 3358 } 3359 3360 //===========================InitializeNode==================================== 3361 // SUMMARY: 3362 // This node acts as a memory barrier on raw memory, after some raw stores. 3363 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 3364 // The Initialize can 'capture' suitably constrained stores as raw inits. 3365 // It can coalesce related raw stores into larger units (called 'tiles'). 3366 // It can avoid zeroing new storage for memory units which have raw inits. 3367 // At macro-expansion, it is marked 'complete', and does not optimize further. 3368 // 3369 // EXAMPLE: 3370 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3371 // ctl = incoming control; mem* = incoming memory 3372 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 3373 // First allocate uninitialized memory and fill in the header: 3374 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 3375 // ctl := alloc.Control; mem* := alloc.Memory* 3376 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 3377 // Then initialize to zero the non-header parts of the raw memory block: 3378 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3379 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3380 // After the initialize node executes, the object is ready for service: 3381 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3382 // Suppose its body is immediately initialized as {1,2}: 3383 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3384 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3385 // mem.SLICE(#short[*]) := store2 3386 // 3387 // DETAILS: 3388 // An InitializeNode collects and isolates object initialization after 3389 // an AllocateNode and before the next possible safepoint. As a 3390 // memory barrier (MemBarNode), it keeps critical stores from drifting 3391 // down past any safepoint or any publication of the allocation. 3392 // Before this barrier, a newly-allocated object may have uninitialized bits. 3393 // After this barrier, it may be treated as a real oop, and GC is allowed. 3394 // 3395 // The semantics of the InitializeNode include an implicit zeroing of 3396 // the new object from object header to the end of the object. 3397 // (The object header and end are determined by the AllocateNode.) 3398 // 3399 // Certain stores may be added as direct inputs to the InitializeNode. 3400 // These stores must update raw memory, and they must be to addresses 3401 // derived from the raw address produced by AllocateNode, and with 3402 // a constant offset. They must be ordered by increasing offset. 3403 // The first one is at in(RawStores), the last at in(req()-1). 3404 // Unlike most memory operations, they are not linked in a chain, 3405 // but are displayed in parallel as users of the rawmem output of 3406 // the allocation. 3407 // 3408 // (See comments in InitializeNode::capture_store, which continue 3409 // the example given above.) 3410 // 3411 // When the associated Allocate is macro-expanded, the InitializeNode 3412 // may be rewritten to optimize collected stores. A ClearArrayNode 3413 // may also be created at that point to represent any required zeroing. 3414 // The InitializeNode is then marked 'complete', prohibiting further 3415 // capturing of nearby memory operations. 3416 // 3417 // During macro-expansion, all captured initializations which store 3418 // constant values of 32 bits or smaller are coalesced (if advantageous) 3419 // into larger 'tiles' 32 or 64 bits. This allows an object to be 3420 // initialized in fewer memory operations. Memory words which are 3421 // covered by neither tiles nor non-constant stores are pre-zeroed 3422 // by explicit stores of zero. (The code shape happens to do all 3423 // zeroing first, then all other stores, with both sequences occurring 3424 // in order of ascending offsets.) 3425 // 3426 // Alternatively, code may be inserted between an AllocateNode and its 3427 // InitializeNode, to perform arbitrary initialization of the new object. 3428 // E.g., the object copying intrinsics insert complex data transfers here. 3429 // The initialization must then be marked as 'complete' disable the 3430 // built-in zeroing semantics and the collection of initializing stores. 3431 // 3432 // While an InitializeNode is incomplete, reads from the memory state 3433 // produced by it are optimizable if they match the control edge and 3434 // new oop address associated with the allocation/initialization. 3435 // They return a stored value (if the offset matches) or else zero. 3436 // A write to the memory state, if it matches control and address, 3437 // and if it is to a constant offset, may be 'captured' by the 3438 // InitializeNode. It is cloned as a raw memory operation and rewired 3439 // inside the initialization, to the raw oop produced by the allocation. 3440 // Operations on addresses which are provably distinct (e.g., to 3441 // other AllocateNodes) are allowed to bypass the initialization. 3442 // 3443 // The effect of all this is to consolidate object initialization 3444 // (both arrays and non-arrays, both piecewise and bulk) into a 3445 // single location, where it can be optimized as a unit. 3446 // 3447 // Only stores with an offset less than TrackedInitializationLimit words 3448 // will be considered for capture by an InitializeNode. This puts a 3449 // reasonable limit on the complexity of optimized initializations. 3450 3451 //---------------------------InitializeNode------------------------------------ 3452 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3453 : MemBarNode(C, adr_type, rawoop), 3454 _is_complete(Incomplete), _does_not_escape(false) 3455 { 3456 init_class_id(Class_Initialize); 3457 3458 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3459 assert(in(RawAddress) == rawoop, "proper init"); 3460 // Note: allocation() can be NULL, for secondary initialization barriers 3461 } 3462 3463 // Since this node is not matched, it will be processed by the 3464 // register allocator. Declare that there are no constraints 3465 // on the allocation of the RawAddress edge. 3466 const RegMask &InitializeNode::in_RegMask(uint idx) const { 3467 // This edge should be set to top, by the set_complete. But be conservative. 3468 if (idx == InitializeNode::RawAddress) 3469 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3470 return RegMask::Empty; 3471 } 3472 3473 Node* InitializeNode::memory(uint alias_idx) { 3474 Node* mem = in(Memory); 3475 if (mem->is_MergeMem()) { 3476 return mem->as_MergeMem()->memory_at(alias_idx); 3477 } else { 3478 // incoming raw memory is not split 3479 return mem; 3480 } 3481 } 3482 3483 bool InitializeNode::is_non_zero() { 3484 if (is_complete()) return false; 3485 remove_extra_zeroes(); 3486 return (req() > RawStores); 3487 } 3488 3489 void InitializeNode::set_complete(PhaseGVN* phase) { 3490 assert(!is_complete(), "caller responsibility"); 3491 _is_complete = Complete; 3492 3493 // After this node is complete, it contains a bunch of 3494 // raw-memory initializations. There is no need for 3495 // it to have anything to do with non-raw memory effects. 3496 // Therefore, tell all non-raw users to re-optimize themselves, 3497 // after skipping the memory effects of this initialization. 3498 PhaseIterGVN* igvn = phase->is_IterGVN(); 3499 if (igvn) igvn->add_users_to_worklist(this); 3500 } 3501 3502 // convenience function 3503 // return false if the init contains any stores already 3504 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3505 InitializeNode* init = initialization(); 3506 if (init == NULL || init->is_complete()) return false; 3507 init->remove_extra_zeroes(); 3508 // for now, if this allocation has already collected any inits, bail: 3509 if (init->is_non_zero()) return false; 3510 init->set_complete(phase); 3511 return true; 3512 } 3513 3514 void InitializeNode::remove_extra_zeroes() { 3515 if (req() == RawStores) return; 3516 Node* zmem = zero_memory(); 3517 uint fill = RawStores; 3518 for (uint i = fill; i < req(); i++) { 3519 Node* n = in(i); 3520 if (n->is_top() || n == zmem) continue; // skip 3521 if (fill < i) set_req(fill, n); // compact 3522 ++fill; 3523 } 3524 // delete any empty spaces created: 3525 while (fill < req()) { 3526 del_req(fill); 3527 } 3528 } 3529 3530 // Helper for remembering which stores go with which offsets. 3531 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3532 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3533 intptr_t offset = -1; 3534 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3535 phase, offset); 3536 if (base == NULL) return -1; // something is dead, 3537 if (offset < 0) return -1; // dead, dead 3538 return offset; 3539 } 3540 3541 // Helper for proving that an initialization expression is 3542 // "simple enough" to be folded into an object initialization. 3543 // Attempts to prove that a store's initial value 'n' can be captured 3544 // within the initialization without creating a vicious cycle, such as: 3545 // { Foo p = new Foo(); p.next = p; } 3546 // True for constants and parameters and small combinations thereof. 3547 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) { 3548 ResourceMark rm; 3549 Unique_Node_List worklist; 3550 worklist.push(value); 3551 3552 uint complexity_limit = 20; 3553 for (uint j = 0; j < worklist.size(); j++) { 3554 if (j >= complexity_limit) { 3555 return false; // Bail out if processed too many nodes 3556 } 3557 3558 Node* n = worklist.at(j); 3559 if (n == NULL) continue; // (can this really happen?) 3560 if (n->is_Proj()) n = n->in(0); 3561 if (n == this) return false; // found a cycle 3562 if (n->is_Con()) continue; 3563 if (n->is_Start()) continue; // params, etc., are OK 3564 if (n->is_Root()) continue; // even better 3565 3566 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation 3567 if (n->is_CFG() && phase->is_dominator(n, allocation())) { 3568 continue; 3569 } 3570 3571 Node* ctl = n->in(0); 3572 if (ctl != NULL && !ctl->is_top()) { 3573 if (ctl->is_Proj()) ctl = ctl->in(0); 3574 if (ctl == this) return false; 3575 3576 // If we already know that the enclosing memory op is pinned right after 3577 // the init, then any control flow that the store has picked up 3578 // must have preceded the init, or else be equal to the init. 3579 // Even after loop optimizations (which might change control edges) 3580 // a store is never pinned *before* the availability of its inputs. 3581 if (!MemNode::all_controls_dominate(n, this)) 3582 return false; // failed to prove a good control 3583 } 3584 3585 // Check data edges for possible dependencies on 'this'. 3586 for (uint i = 1; i < n->req(); i++) { 3587 Node* m = n->in(i); 3588 if (m == NULL || m == n || m->is_top()) continue; 3589 3590 // Only process data inputs once 3591 worklist.push(m); 3592 } 3593 } 3594 3595 return true; 3596 } 3597 3598 // Here are all the checks a Store must pass before it can be moved into 3599 // an initialization. Returns zero if a check fails. 3600 // On success, returns the (constant) offset to which the store applies, 3601 // within the initialized memory. 3602 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) { 3603 const int FAIL = 0; 3604 if (st->req() != MemNode::ValueIn + 1) 3605 return FAIL; // an inscrutable StoreNode (card mark?) 3606 Node* ctl = st->in(MemNode::Control); 3607 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3608 return FAIL; // must be unconditional after the initialization 3609 Node* mem = st->in(MemNode::Memory); 3610 if (!(mem->is_Proj() && mem->in(0) == this)) 3611 return FAIL; // must not be preceded by other stores 3612 Node* adr = st->in(MemNode::Address); 3613 intptr_t offset; 3614 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3615 if (alloc == NULL) 3616 return FAIL; // inscrutable address 3617 if (alloc != allocation()) 3618 return FAIL; // wrong allocation! (store needs to float up) 3619 int size_in_bytes = st->memory_size(); 3620 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) { 3621 return FAIL; // mismatched access 3622 } 3623 Node* val = st->in(MemNode::ValueIn); 3624 3625 if (!detect_init_independence(val, phase)) 3626 return FAIL; // stored value must be 'simple enough' 3627 3628 // The Store can be captured only if nothing after the allocation 3629 // and before the Store is using the memory location that the store 3630 // overwrites. 3631 bool failed = false; 3632 // If is_complete_with_arraycopy() is true the shape of the graph is 3633 // well defined and is safe so no need for extra checks. 3634 if (!is_complete_with_arraycopy()) { 3635 // We are going to look at each use of the memory state following 3636 // the allocation to make sure nothing reads the memory that the 3637 // Store writes. 3638 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3639 int alias_idx = phase->C->get_alias_index(t_adr); 3640 ResourceMark rm; 3641 Unique_Node_List mems; 3642 mems.push(mem); 3643 Node* unique_merge = NULL; 3644 for (uint next = 0; next < mems.size(); ++next) { 3645 Node *m = mems.at(next); 3646 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3647 Node *n = m->fast_out(j); 3648 if (n->outcnt() == 0) { 3649 continue; 3650 } 3651 if (n == st) { 3652 continue; 3653 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3654 // If the control of this use is different from the control 3655 // of the Store which is right after the InitializeNode then 3656 // this node cannot be between the InitializeNode and the 3657 // Store. 3658 continue; 3659 } else if (n->is_MergeMem()) { 3660 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3661 // We can hit a MergeMemNode (that will likely go away 3662 // later) that is a direct use of the memory state 3663 // following the InitializeNode on the same slice as the 3664 // store node that we'd like to capture. We need to check 3665 // the uses of the MergeMemNode. 3666 mems.push(n); 3667 } 3668 } else if (n->is_Mem()) { 3669 Node* other_adr = n->in(MemNode::Address); 3670 if (other_adr == adr) { 3671 failed = true; 3672 break; 3673 } else { 3674 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3675 if (other_t_adr != NULL) { 3676 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3677 if (other_alias_idx == alias_idx) { 3678 // A load from the same memory slice as the store right 3679 // after the InitializeNode. We check the control of the 3680 // object/array that is loaded from. If it's the same as 3681 // the store control then we cannot capture the store. 3682 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3683 Node* base = other_adr; 3684 assert(base->is_AddP(), "should be addp but is %s", base->Name()); 3685 base = base->in(AddPNode::Base); 3686 if (base != NULL) { 3687 base = base->uncast(); 3688 if (base->is_Proj() && base->in(0) == alloc) { 3689 failed = true; 3690 break; 3691 } 3692 } 3693 } 3694 } 3695 } 3696 } else { 3697 failed = true; 3698 break; 3699 } 3700 } 3701 } 3702 } 3703 if (failed) { 3704 if (!can_reshape) { 3705 // We decided we couldn't capture the store during parsing. We 3706 // should try again during the next IGVN once the graph is 3707 // cleaner. 3708 phase->C->record_for_igvn(st); 3709 } 3710 return FAIL; 3711 } 3712 3713 return offset; // success 3714 } 3715 3716 // Find the captured store in(i) which corresponds to the range 3717 // [start..start+size) in the initialized object. 3718 // If there is one, return its index i. If there isn't, return the 3719 // negative of the index where it should be inserted. 3720 // Return 0 if the queried range overlaps an initialization boundary 3721 // or if dead code is encountered. 3722 // If size_in_bytes is zero, do not bother with overlap checks. 3723 int InitializeNode::captured_store_insertion_point(intptr_t start, 3724 int size_in_bytes, 3725 PhaseTransform* phase) { 3726 const int FAIL = 0, MAX_STORE = BytesPerLong; 3727 3728 if (is_complete()) 3729 return FAIL; // arraycopy got here first; punt 3730 3731 assert(allocation() != NULL, "must be present"); 3732 3733 // no negatives, no header fields: 3734 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3735 3736 // after a certain size, we bail out on tracking all the stores: 3737 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3738 if (start >= ti_limit) return FAIL; 3739 3740 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3741 if (i >= limit) return -(int)i; // not found; here is where to put it 3742 3743 Node* st = in(i); 3744 intptr_t st_off = get_store_offset(st, phase); 3745 if (st_off < 0) { 3746 if (st != zero_memory()) { 3747 return FAIL; // bail out if there is dead garbage 3748 } 3749 } else if (st_off > start) { 3750 // ...we are done, since stores are ordered 3751 if (st_off < start + size_in_bytes) { 3752 return FAIL; // the next store overlaps 3753 } 3754 return -(int)i; // not found; here is where to put it 3755 } else if (st_off < start) { 3756 if (size_in_bytes != 0 && 3757 start < st_off + MAX_STORE && 3758 start < st_off + st->as_Store()->memory_size()) { 3759 return FAIL; // the previous store overlaps 3760 } 3761 } else { 3762 if (size_in_bytes != 0 && 3763 st->as_Store()->memory_size() != size_in_bytes) { 3764 return FAIL; // mismatched store size 3765 } 3766 return i; 3767 } 3768 3769 ++i; 3770 } 3771 } 3772 3773 // Look for a captured store which initializes at the offset 'start' 3774 // with the given size. If there is no such store, and no other 3775 // initialization interferes, then return zero_memory (the memory 3776 // projection of the AllocateNode). 3777 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3778 PhaseTransform* phase) { 3779 assert(stores_are_sane(phase), ""); 3780 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3781 if (i == 0) { 3782 return NULL; // something is dead 3783 } else if (i < 0) { 3784 return zero_memory(); // just primordial zero bits here 3785 } else { 3786 Node* st = in(i); // here is the store at this position 3787 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3788 return st; 3789 } 3790 } 3791 3792 // Create, as a raw pointer, an address within my new object at 'offset'. 3793 Node* InitializeNode::make_raw_address(intptr_t offset, 3794 PhaseTransform* phase) { 3795 Node* addr = in(RawAddress); 3796 if (offset != 0) { 3797 Compile* C = phase->C; 3798 addr = phase->transform( new AddPNode(C->top(), addr, 3799 phase->MakeConX(offset)) ); 3800 } 3801 return addr; 3802 } 3803 3804 // Clone the given store, converting it into a raw store 3805 // initializing a field or element of my new object. 3806 // Caller is responsible for retiring the original store, 3807 // with subsume_node or the like. 3808 // 3809 // From the example above InitializeNode::InitializeNode, 3810 // here are the old stores to be captured: 3811 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3812 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3813 // 3814 // Here is the changed code; note the extra edges on init: 3815 // alloc = (Allocate ...) 3816 // rawoop = alloc.RawAddress 3817 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3818 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3819 // init = (Initialize alloc.Control alloc.Memory rawoop 3820 // rawstore1 rawstore2) 3821 // 3822 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3823 PhaseGVN* phase, bool can_reshape) { 3824 assert(stores_are_sane(phase), ""); 3825 3826 if (start < 0) return NULL; 3827 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3828 3829 Compile* C = phase->C; 3830 int size_in_bytes = st->memory_size(); 3831 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3832 if (i == 0) return NULL; // bail out 3833 Node* prev_mem = NULL; // raw memory for the captured store 3834 if (i > 0) { 3835 prev_mem = in(i); // there is a pre-existing store under this one 3836 set_req(i, C->top()); // temporarily disconnect it 3837 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3838 } else { 3839 i = -i; // no pre-existing store 3840 prev_mem = zero_memory(); // a slice of the newly allocated object 3841 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3842 set_req(--i, C->top()); // reuse this edge; it has been folded away 3843 else 3844 ins_req(i, C->top()); // build a new edge 3845 } 3846 Node* new_st = st->clone(); 3847 new_st->set_req(MemNode::Control, in(Control)); 3848 new_st->set_req(MemNode::Memory, prev_mem); 3849 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3850 new_st = phase->transform(new_st); 3851 3852 // At this point, new_st might have swallowed a pre-existing store 3853 // at the same offset, or perhaps new_st might have disappeared, 3854 // if it redundantly stored the same value (or zero to fresh memory). 3855 3856 // In any case, wire it in: 3857 phase->igvn_rehash_node_delayed(this); 3858 set_req(i, new_st); 3859 3860 // The caller may now kill the old guy. 3861 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3862 assert(check_st == new_st || check_st == NULL, "must be findable"); 3863 assert(!is_complete(), ""); 3864 return new_st; 3865 } 3866 3867 static bool store_constant(jlong* tiles, int num_tiles, 3868 intptr_t st_off, int st_size, 3869 jlong con) { 3870 if ((st_off & (st_size-1)) != 0) 3871 return false; // strange store offset (assume size==2**N) 3872 address addr = (address)tiles + st_off; 3873 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3874 switch (st_size) { 3875 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3876 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3877 case sizeof(jint): *(jint*) addr = (jint) con; break; 3878 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3879 default: return false; // strange store size (detect size!=2**N here) 3880 } 3881 return true; // return success to caller 3882 } 3883 3884 // Coalesce subword constants into int constants and possibly 3885 // into long constants. The goal, if the CPU permits, 3886 // is to initialize the object with a small number of 64-bit tiles. 3887 // Also, convert floating-point constants to bit patterns. 3888 // Non-constants are not relevant to this pass. 3889 // 3890 // In terms of the running example on InitializeNode::InitializeNode 3891 // and InitializeNode::capture_store, here is the transformation 3892 // of rawstore1 and rawstore2 into rawstore12: 3893 // alloc = (Allocate ...) 3894 // rawoop = alloc.RawAddress 3895 // tile12 = 0x00010002 3896 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3897 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3898 // 3899 void 3900 InitializeNode::coalesce_subword_stores(intptr_t header_size, 3901 Node* size_in_bytes, 3902 PhaseGVN* phase) { 3903 Compile* C = phase->C; 3904 3905 assert(stores_are_sane(phase), ""); 3906 // Note: After this pass, they are not completely sane, 3907 // since there may be some overlaps. 3908 3909 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3910 3911 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3912 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3913 size_limit = MIN2(size_limit, ti_limit); 3914 size_limit = align_up(size_limit, BytesPerLong); 3915 int num_tiles = size_limit / BytesPerLong; 3916 3917 // allocate space for the tile map: 3918 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3919 jlong tiles_buf[small_len]; 3920 Node* nodes_buf[small_len]; 3921 jlong inits_buf[small_len]; 3922 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3923 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3924 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3925 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3926 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3927 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3928 // tiles: exact bitwise model of all primitive constants 3929 // nodes: last constant-storing node subsumed into the tiles model 3930 // inits: which bytes (in each tile) are touched by any initializations 3931 3932 //// Pass A: Fill in the tile model with any relevant stores. 3933 3934 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3935 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3936 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3937 Node* zmem = zero_memory(); // initially zero memory state 3938 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3939 Node* st = in(i); 3940 intptr_t st_off = get_store_offset(st, phase); 3941 3942 // Figure out the store's offset and constant value: 3943 if (st_off < header_size) continue; //skip (ignore header) 3944 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3945 int st_size = st->as_Store()->memory_size(); 3946 if (st_off + st_size > size_limit) break; 3947 3948 // Record which bytes are touched, whether by constant or not. 3949 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3950 continue; // skip (strange store size) 3951 3952 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3953 if (!val->singleton()) continue; //skip (non-con store) 3954 BasicType type = val->basic_type(); 3955 3956 jlong con = 0; 3957 switch (type) { 3958 case T_INT: con = val->is_int()->get_con(); break; 3959 case T_LONG: con = val->is_long()->get_con(); break; 3960 case T_FLOAT: con = jint_cast(val->getf()); break; 3961 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3962 default: continue; //skip (odd store type) 3963 } 3964 3965 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3966 st->Opcode() == Op_StoreL) { 3967 continue; // This StoreL is already optimal. 3968 } 3969 3970 // Store down the constant. 3971 store_constant(tiles, num_tiles, st_off, st_size, con); 3972 3973 intptr_t j = st_off >> LogBytesPerLong; 3974 3975 if (type == T_INT && st_size == BytesPerInt 3976 && (st_off & BytesPerInt) == BytesPerInt) { 3977 jlong lcon = tiles[j]; 3978 if (!Matcher::isSimpleConstant64(lcon) && 3979 st->Opcode() == Op_StoreI) { 3980 // This StoreI is already optimal by itself. 3981 jint* intcon = (jint*) &tiles[j]; 3982 intcon[1] = 0; // undo the store_constant() 3983 3984 // If the previous store is also optimal by itself, back up and 3985 // undo the action of the previous loop iteration... if we can. 3986 // But if we can't, just let the previous half take care of itself. 3987 st = nodes[j]; 3988 st_off -= BytesPerInt; 3989 con = intcon[0]; 3990 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3991 assert(st_off >= header_size, "still ignoring header"); 3992 assert(get_store_offset(st, phase) == st_off, "must be"); 3993 assert(in(i-1) == zmem, "must be"); 3994 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3995 assert(con == tcon->is_int()->get_con(), "must be"); 3996 // Undo the effects of the previous loop trip, which swallowed st: 3997 intcon[0] = 0; // undo store_constant() 3998 set_req(i-1, st); // undo set_req(i, zmem) 3999 nodes[j] = NULL; // undo nodes[j] = st 4000 --old_subword; // undo ++old_subword 4001 } 4002 continue; // This StoreI is already optimal. 4003 } 4004 } 4005 4006 // This store is not needed. 4007 set_req(i, zmem); 4008 nodes[j] = st; // record for the moment 4009 if (st_size < BytesPerLong) // something has changed 4010 ++old_subword; // includes int/float, but who's counting... 4011 else ++old_long; 4012 } 4013 4014 if ((old_subword + old_long) == 0) 4015 return; // nothing more to do 4016 4017 //// Pass B: Convert any non-zero tiles into optimal constant stores. 4018 // Be sure to insert them before overlapping non-constant stores. 4019 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 4020 for (int j = 0; j < num_tiles; j++) { 4021 jlong con = tiles[j]; 4022 jlong init = inits[j]; 4023 if (con == 0) continue; 4024 jint con0, con1; // split the constant, address-wise 4025 jint init0, init1; // split the init map, address-wise 4026 { union { jlong con; jint intcon[2]; } u; 4027 u.con = con; 4028 con0 = u.intcon[0]; 4029 con1 = u.intcon[1]; 4030 u.con = init; 4031 init0 = u.intcon[0]; 4032 init1 = u.intcon[1]; 4033 } 4034 4035 Node* old = nodes[j]; 4036 assert(old != NULL, "need the prior store"); 4037 intptr_t offset = (j * BytesPerLong); 4038 4039 bool split = !Matcher::isSimpleConstant64(con); 4040 4041 if (offset < header_size) { 4042 assert(offset + BytesPerInt >= header_size, "second int counts"); 4043 assert(*(jint*)&tiles[j] == 0, "junk in header"); 4044 split = true; // only the second word counts 4045 // Example: int a[] = { 42 ... } 4046 } else if (con0 == 0 && init0 == -1) { 4047 split = true; // first word is covered by full inits 4048 // Example: int a[] = { ... foo(), 42 ... } 4049 } else if (con1 == 0 && init1 == -1) { 4050 split = true; // second word is covered by full inits 4051 // Example: int a[] = { ... 42, foo() ... } 4052 } 4053 4054 // Here's a case where init0 is neither 0 nor -1: 4055 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 4056 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 4057 // In this case the tile is not split; it is (jlong)42. 4058 // The big tile is stored down, and then the foo() value is inserted. 4059 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 4060 4061 Node* ctl = old->in(MemNode::Control); 4062 Node* adr = make_raw_address(offset, phase); 4063 const TypePtr* atp = TypeRawPtr::BOTTOM; 4064 4065 // One or two coalesced stores to plop down. 4066 Node* st[2]; 4067 intptr_t off[2]; 4068 int nst = 0; 4069 if (!split) { 4070 ++new_long; 4071 off[nst] = offset; 4072 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4073 phase->longcon(con), T_LONG, MemNode::unordered); 4074 } else { 4075 // Omit either if it is a zero. 4076 if (con0 != 0) { 4077 ++new_int; 4078 off[nst] = offset; 4079 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4080 phase->intcon(con0), T_INT, MemNode::unordered); 4081 } 4082 if (con1 != 0) { 4083 ++new_int; 4084 offset += BytesPerInt; 4085 adr = make_raw_address(offset, phase); 4086 off[nst] = offset; 4087 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4088 phase->intcon(con1), T_INT, MemNode::unordered); 4089 } 4090 } 4091 4092 // Insert second store first, then the first before the second. 4093 // Insert each one just before any overlapping non-constant stores. 4094 while (nst > 0) { 4095 Node* st1 = st[--nst]; 4096 C->copy_node_notes_to(st1, old); 4097 st1 = phase->transform(st1); 4098 offset = off[nst]; 4099 assert(offset >= header_size, "do not smash header"); 4100 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 4101 guarantee(ins_idx != 0, "must re-insert constant store"); 4102 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 4103 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 4104 set_req(--ins_idx, st1); 4105 else 4106 ins_req(ins_idx, st1); 4107 } 4108 } 4109 4110 if (PrintCompilation && WizardMode) 4111 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 4112 old_subword, old_long, new_int, new_long); 4113 if (C->log() != NULL) 4114 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 4115 old_subword, old_long, new_int, new_long); 4116 4117 // Clean up any remaining occurrences of zmem: 4118 remove_extra_zeroes(); 4119 } 4120 4121 // Explore forward from in(start) to find the first fully initialized 4122 // word, and return its offset. Skip groups of subword stores which 4123 // together initialize full words. If in(start) is itself part of a 4124 // fully initialized word, return the offset of in(start). If there 4125 // are no following full-word stores, or if something is fishy, return 4126 // a negative value. 4127 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 4128 int int_map = 0; 4129 intptr_t int_map_off = 0; 4130 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 4131 4132 for (uint i = start, limit = req(); i < limit; i++) { 4133 Node* st = in(i); 4134 4135 intptr_t st_off = get_store_offset(st, phase); 4136 if (st_off < 0) break; // return conservative answer 4137 4138 int st_size = st->as_Store()->memory_size(); 4139 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 4140 return st_off; // we found a complete word init 4141 } 4142 4143 // update the map: 4144 4145 intptr_t this_int_off = align_down(st_off, BytesPerInt); 4146 if (this_int_off != int_map_off) { 4147 // reset the map: 4148 int_map = 0; 4149 int_map_off = this_int_off; 4150 } 4151 4152 int subword_off = st_off - this_int_off; 4153 int_map |= right_n_bits(st_size) << subword_off; 4154 if ((int_map & FULL_MAP) == FULL_MAP) { 4155 return this_int_off; // we found a complete word init 4156 } 4157 4158 // Did this store hit or cross the word boundary? 4159 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt); 4160 if (next_int_off == this_int_off + BytesPerInt) { 4161 // We passed the current int, without fully initializing it. 4162 int_map_off = next_int_off; 4163 int_map >>= BytesPerInt; 4164 } else if (next_int_off > this_int_off + BytesPerInt) { 4165 // We passed the current and next int. 4166 return this_int_off + BytesPerInt; 4167 } 4168 } 4169 4170 return -1; 4171 } 4172 4173 4174 // Called when the associated AllocateNode is expanded into CFG. 4175 // At this point, we may perform additional optimizations. 4176 // Linearize the stores by ascending offset, to make memory 4177 // activity as coherent as possible. 4178 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 4179 intptr_t header_size, 4180 Node* size_in_bytes, 4181 PhaseIterGVN* phase) { 4182 assert(!is_complete(), "not already complete"); 4183 assert(stores_are_sane(phase), ""); 4184 assert(allocation() != NULL, "must be present"); 4185 4186 remove_extra_zeroes(); 4187 4188 if (ReduceFieldZeroing || ReduceBulkZeroing) 4189 // reduce instruction count for common initialization patterns 4190 coalesce_subword_stores(header_size, size_in_bytes, phase); 4191 4192 Node* zmem = zero_memory(); // initially zero memory state 4193 Node* inits = zmem; // accumulating a linearized chain of inits 4194 #ifdef ASSERT 4195 intptr_t first_offset = allocation()->minimum_header_size(); 4196 intptr_t last_init_off = first_offset; // previous init offset 4197 intptr_t last_init_end = first_offset; // previous init offset+size 4198 intptr_t last_tile_end = first_offset; // previous tile offset+size 4199 #endif 4200 intptr_t zeroes_done = header_size; 4201 4202 bool do_zeroing = true; // we might give up if inits are very sparse 4203 int big_init_gaps = 0; // how many large gaps have we seen? 4204 4205 if (UseTLAB && ZeroTLAB) do_zeroing = false; 4206 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 4207 4208 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 4209 Node* st = in(i); 4210 intptr_t st_off = get_store_offset(st, phase); 4211 if (st_off < 0) 4212 break; // unknown junk in the inits 4213 if (st->in(MemNode::Memory) != zmem) 4214 break; // complicated store chains somehow in list 4215 4216 int st_size = st->as_Store()->memory_size(); 4217 intptr_t next_init_off = st_off + st_size; 4218 4219 if (do_zeroing && zeroes_done < next_init_off) { 4220 // See if this store needs a zero before it or under it. 4221 intptr_t zeroes_needed = st_off; 4222 4223 if (st_size < BytesPerInt) { 4224 // Look for subword stores which only partially initialize words. 4225 // If we find some, we must lay down some word-level zeroes first, 4226 // underneath the subword stores. 4227 // 4228 // Examples: 4229 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 4230 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 4231 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 4232 // 4233 // Note: coalesce_subword_stores may have already done this, 4234 // if it was prompted by constant non-zero subword initializers. 4235 // But this case can still arise with non-constant stores. 4236 4237 intptr_t next_full_store = find_next_fullword_store(i, phase); 4238 4239 // In the examples above: 4240 // in(i) p q r s x y z 4241 // st_off 12 13 14 15 12 13 14 4242 // st_size 1 1 1 1 1 1 1 4243 // next_full_s. 12 16 16 16 16 16 16 4244 // z's_done 12 16 16 16 12 16 12 4245 // z's_needed 12 16 16 16 16 16 16 4246 // zsize 0 0 0 0 4 0 4 4247 if (next_full_store < 0) { 4248 // Conservative tack: Zero to end of current word. 4249 zeroes_needed = align_up(zeroes_needed, BytesPerInt); 4250 } else { 4251 // Zero to beginning of next fully initialized word. 4252 // Or, don't zero at all, if we are already in that word. 4253 assert(next_full_store >= zeroes_needed, "must go forward"); 4254 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 4255 zeroes_needed = next_full_store; 4256 } 4257 } 4258 4259 if (zeroes_needed > zeroes_done) { 4260 intptr_t zsize = zeroes_needed - zeroes_done; 4261 // Do some incremental zeroing on rawmem, in parallel with inits. 4262 zeroes_done = align_down(zeroes_done, BytesPerInt); 4263 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4264 zeroes_done, zeroes_needed, 4265 phase); 4266 zeroes_done = zeroes_needed; 4267 if (zsize > InitArrayShortSize && ++big_init_gaps > 2) 4268 do_zeroing = false; // leave the hole, next time 4269 } 4270 } 4271 4272 // Collect the store and move on: 4273 phase->replace_input_of(st, MemNode::Memory, inits); 4274 inits = st; // put it on the linearized chain 4275 set_req(i, zmem); // unhook from previous position 4276 4277 if (zeroes_done == st_off) 4278 zeroes_done = next_init_off; 4279 4280 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 4281 4282 #ifdef ASSERT 4283 // Various order invariants. Weaker than stores_are_sane because 4284 // a large constant tile can be filled in by smaller non-constant stores. 4285 assert(st_off >= last_init_off, "inits do not reverse"); 4286 last_init_off = st_off; 4287 const Type* val = NULL; 4288 if (st_size >= BytesPerInt && 4289 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 4290 (int)val->basic_type() < (int)T_OBJECT) { 4291 assert(st_off >= last_tile_end, "tiles do not overlap"); 4292 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 4293 last_tile_end = MAX2(last_tile_end, next_init_off); 4294 } else { 4295 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong); 4296 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 4297 assert(st_off >= last_init_end, "inits do not overlap"); 4298 last_init_end = next_init_off; // it's a non-tile 4299 } 4300 #endif //ASSERT 4301 } 4302 4303 remove_extra_zeroes(); // clear out all the zmems left over 4304 add_req(inits); 4305 4306 if (!(UseTLAB && ZeroTLAB)) { 4307 // If anything remains to be zeroed, zero it all now. 4308 zeroes_done = align_down(zeroes_done, BytesPerInt); 4309 // if it is the last unused 4 bytes of an instance, forget about it 4310 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 4311 if (zeroes_done + BytesPerLong >= size_limit) { 4312 AllocateNode* alloc = allocation(); 4313 assert(alloc != NULL, "must be present"); 4314 if (alloc != NULL && alloc->Opcode() == Op_Allocate) { 4315 Node* klass_node = alloc->in(AllocateNode::KlassNode); 4316 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 4317 if (zeroes_done == k->layout_helper()) 4318 zeroes_done = size_limit; 4319 } 4320 } 4321 if (zeroes_done < size_limit) { 4322 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4323 zeroes_done, size_in_bytes, phase); 4324 } 4325 } 4326 4327 set_complete(phase); 4328 return rawmem; 4329 } 4330 4331 4332 #ifdef ASSERT 4333 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 4334 if (is_complete()) 4335 return true; // stores could be anything at this point 4336 assert(allocation() != NULL, "must be present"); 4337 intptr_t last_off = allocation()->minimum_header_size(); 4338 for (uint i = InitializeNode::RawStores; i < req(); i++) { 4339 Node* st = in(i); 4340 intptr_t st_off = get_store_offset(st, phase); 4341 if (st_off < 0) continue; // ignore dead garbage 4342 if (last_off > st_off) { 4343 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 4344 this->dump(2); 4345 assert(false, "ascending store offsets"); 4346 return false; 4347 } 4348 last_off = st_off + st->as_Store()->memory_size(); 4349 } 4350 return true; 4351 } 4352 #endif //ASSERT 4353 4354 4355 4356 4357 //============================MergeMemNode===================================== 4358 // 4359 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4360 // contributing store or call operations. Each contributor provides the memory 4361 // state for a particular "alias type" (see Compile::alias_type). For example, 4362 // if a MergeMem has an input X for alias category #6, then any memory reference 4363 // to alias category #6 may use X as its memory state input, as an exact equivalent 4364 // to using the MergeMem as a whole. 4365 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4366 // 4367 // (Here, the <N> notation gives the index of the relevant adr_type.) 4368 // 4369 // In one special case (and more cases in the future), alias categories overlap. 4370 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4371 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 4372 // it is exactly equivalent to that state W: 4373 // MergeMem(<Bot>: W) <==> W 4374 // 4375 // Usually, the merge has more than one input. In that case, where inputs 4376 // overlap (i.e., one is Bot), the narrower alias type determines the memory 4377 // state for that type, and the wider alias type (Bot) fills in everywhere else: 4378 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4379 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4380 // 4381 // A merge can take a "wide" memory state as one of its narrow inputs. 4382 // This simply means that the merge observes out only the relevant parts of 4383 // the wide input. That is, wide memory states arriving at narrow merge inputs 4384 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4385 // 4386 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4387 // and that memory slices "leak through": 4388 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4389 // 4390 // But, in such a cascade, repeated memory slices can "block the leak": 4391 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4392 // 4393 // In the last example, Y is not part of the combined memory state of the 4394 // outermost MergeMem. The system must, of course, prevent unschedulable 4395 // memory states from arising, so you can be sure that the state Y is somehow 4396 // a precursor to state Y'. 4397 // 4398 // 4399 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4400 // of each MergeMemNode array are exactly the numerical alias indexes, including 4401 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4402 // Compile::alias_type (and kin) produce and manage these indexes. 4403 // 4404 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4405 // (Note that this provides quick access to the top node inside MergeMem methods, 4406 // without the need to reach out via TLS to Compile::current.) 4407 // 4408 // As a consequence of what was just described, a MergeMem that represents a full 4409 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4410 // containing all alias categories. 4411 // 4412 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4413 // 4414 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4415 // a memory state for the alias type <N>, or else the top node, meaning that 4416 // there is no particular input for that alias type. Note that the length of 4417 // a MergeMem is variable, and may be extended at any time to accommodate new 4418 // memory states at larger alias indexes. When merges grow, they are of course 4419 // filled with "top" in the unused in() positions. 4420 // 4421 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4422 // (Top was chosen because it works smoothly with passes like GCM.) 4423 // 4424 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4425 // the type of random VM bits like TLS references.) Since it is always the 4426 // first non-Bot memory slice, some low-level loops use it to initialize an 4427 // index variable: for (i = AliasIdxRaw; i < req(); i++). 4428 // 4429 // 4430 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4431 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4432 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 4433 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4434 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4435 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4436 // 4437 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4438 // really that different from the other memory inputs. An abbreviation called 4439 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4440 // 4441 // 4442 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4443 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4444 // that "emerges though" the base memory will be marked as excluding the alias types 4445 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 4446 // 4447 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4448 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4449 // 4450 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 4451 // (It is currently unimplemented.) As you can see, the resulting merge is 4452 // actually a disjoint union of memory states, rather than an overlay. 4453 // 4454 4455 //------------------------------MergeMemNode----------------------------------- 4456 Node* MergeMemNode::make_empty_memory() { 4457 Node* empty_memory = (Node*) Compile::current()->top(); 4458 assert(empty_memory->is_top(), "correct sentinel identity"); 4459 return empty_memory; 4460 } 4461 4462 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4463 init_class_id(Class_MergeMem); 4464 // all inputs are nullified in Node::Node(int) 4465 // set_input(0, NULL); // no control input 4466 4467 // Initialize the edges uniformly to top, for starters. 4468 Node* empty_mem = make_empty_memory(); 4469 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4470 init_req(i,empty_mem); 4471 } 4472 assert(empty_memory() == empty_mem, ""); 4473 4474 if( new_base != NULL && new_base->is_MergeMem() ) { 4475 MergeMemNode* mdef = new_base->as_MergeMem(); 4476 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4477 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4478 mms.set_memory(mms.memory2()); 4479 } 4480 assert(base_memory() == mdef->base_memory(), ""); 4481 } else { 4482 set_base_memory(new_base); 4483 } 4484 } 4485 4486 // Make a new, untransformed MergeMem with the same base as 'mem'. 4487 // If mem is itself a MergeMem, populate the result with the same edges. 4488 MergeMemNode* MergeMemNode::make(Node* mem) { 4489 return new MergeMemNode(mem); 4490 } 4491 4492 //------------------------------cmp-------------------------------------------- 4493 uint MergeMemNode::hash() const { return NO_HASH; } 4494 bool MergeMemNode::cmp( const Node &n ) const { 4495 return (&n == this); // Always fail except on self 4496 } 4497 4498 //------------------------------Identity--------------------------------------- 4499 Node* MergeMemNode::Identity(PhaseGVN* phase) { 4500 // Identity if this merge point does not record any interesting memory 4501 // disambiguations. 4502 Node* base_mem = base_memory(); 4503 Node* empty_mem = empty_memory(); 4504 if (base_mem != empty_mem) { // Memory path is not dead? 4505 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4506 Node* mem = in(i); 4507 if (mem != empty_mem && mem != base_mem) { 4508 return this; // Many memory splits; no change 4509 } 4510 } 4511 } 4512 return base_mem; // No memory splits; ID on the one true input 4513 } 4514 4515 //------------------------------Ideal------------------------------------------ 4516 // This method is invoked recursively on chains of MergeMem nodes 4517 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4518 // Remove chain'd MergeMems 4519 // 4520 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4521 // relative to the "in(Bot)". Since we are patching both at the same time, 4522 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4523 // but rewrite each "in(i)" relative to the new "in(Bot)". 4524 Node *progress = NULL; 4525 4526 4527 Node* old_base = base_memory(); 4528 Node* empty_mem = empty_memory(); 4529 if (old_base == empty_mem) 4530 return NULL; // Dead memory path. 4531 4532 MergeMemNode* old_mbase; 4533 if (old_base != NULL && old_base->is_MergeMem()) 4534 old_mbase = old_base->as_MergeMem(); 4535 else 4536 old_mbase = NULL; 4537 Node* new_base = old_base; 4538 4539 // simplify stacked MergeMems in base memory 4540 if (old_mbase) new_base = old_mbase->base_memory(); 4541 4542 // the base memory might contribute new slices beyond my req() 4543 if (old_mbase) grow_to_match(old_mbase); 4544 4545 // Look carefully at the base node if it is a phi. 4546 PhiNode* phi_base; 4547 if (new_base != NULL && new_base->is_Phi()) 4548 phi_base = new_base->as_Phi(); 4549 else 4550 phi_base = NULL; 4551 4552 Node* phi_reg = NULL; 4553 uint phi_len = (uint)-1; 4554 if (phi_base != NULL && !phi_base->is_copy()) { 4555 // do not examine phi if degraded to a copy 4556 phi_reg = phi_base->region(); 4557 phi_len = phi_base->req(); 4558 // see if the phi is unfinished 4559 for (uint i = 1; i < phi_len; i++) { 4560 if (phi_base->in(i) == NULL) { 4561 // incomplete phi; do not look at it yet! 4562 phi_reg = NULL; 4563 phi_len = (uint)-1; 4564 break; 4565 } 4566 } 4567 } 4568 4569 // Note: We do not call verify_sparse on entry, because inputs 4570 // can normalize to the base_memory via subsume_node or similar 4571 // mechanisms. This method repairs that damage. 4572 4573 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4574 4575 // Look at each slice. 4576 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4577 Node* old_in = in(i); 4578 // calculate the old memory value 4579 Node* old_mem = old_in; 4580 if (old_mem == empty_mem) old_mem = old_base; 4581 assert(old_mem == memory_at(i), ""); 4582 4583 // maybe update (reslice) the old memory value 4584 4585 // simplify stacked MergeMems 4586 Node* new_mem = old_mem; 4587 MergeMemNode* old_mmem; 4588 if (old_mem != NULL && old_mem->is_MergeMem()) 4589 old_mmem = old_mem->as_MergeMem(); 4590 else 4591 old_mmem = NULL; 4592 if (old_mmem == this) { 4593 // This can happen if loops break up and safepoints disappear. 4594 // A merge of BotPtr (default) with a RawPtr memory derived from a 4595 // safepoint can be rewritten to a merge of the same BotPtr with 4596 // the BotPtr phi coming into the loop. If that phi disappears 4597 // also, we can end up with a self-loop of the mergemem. 4598 // In general, if loops degenerate and memory effects disappear, 4599 // a mergemem can be left looking at itself. This simply means 4600 // that the mergemem's default should be used, since there is 4601 // no longer any apparent effect on this slice. 4602 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4603 // from start. Update the input to TOP. 4604 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4605 } 4606 else if (old_mmem != NULL) { 4607 new_mem = old_mmem->memory_at(i); 4608 } 4609 // else preceding memory was not a MergeMem 4610 4611 // replace equivalent phis (unfortunately, they do not GVN together) 4612 if (new_mem != NULL && new_mem != new_base && 4613 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4614 if (new_mem->is_Phi()) { 4615 PhiNode* phi_mem = new_mem->as_Phi(); 4616 for (uint i = 1; i < phi_len; i++) { 4617 if (phi_base->in(i) != phi_mem->in(i)) { 4618 phi_mem = NULL; 4619 break; 4620 } 4621 } 4622 if (phi_mem != NULL) { 4623 // equivalent phi nodes; revert to the def 4624 new_mem = new_base; 4625 } 4626 } 4627 } 4628 4629 // maybe store down a new value 4630 Node* new_in = new_mem; 4631 if (new_in == new_base) new_in = empty_mem; 4632 4633 if (new_in != old_in) { 4634 // Warning: Do not combine this "if" with the previous "if" 4635 // A memory slice might have be be rewritten even if it is semantically 4636 // unchanged, if the base_memory value has changed. 4637 set_req(i, new_in); 4638 progress = this; // Report progress 4639 } 4640 } 4641 4642 if (new_base != old_base) { 4643 set_req(Compile::AliasIdxBot, new_base); 4644 // Don't use set_base_memory(new_base), because we need to update du. 4645 assert(base_memory() == new_base, ""); 4646 progress = this; 4647 } 4648 4649 if( base_memory() == this ) { 4650 // a self cycle indicates this memory path is dead 4651 set_req(Compile::AliasIdxBot, empty_mem); 4652 } 4653 4654 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4655 // Recursion must occur after the self cycle check above 4656 if( base_memory()->is_MergeMem() ) { 4657 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4658 Node *m = phase->transform(new_mbase); // Rollup any cycles 4659 if( m != NULL && 4660 (m->is_top() || 4661 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) { 4662 // propagate rollup of dead cycle to self 4663 set_req(Compile::AliasIdxBot, empty_mem); 4664 } 4665 } 4666 4667 if( base_memory() == empty_mem ) { 4668 progress = this; 4669 // Cut inputs during Parse phase only. 4670 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4671 if( !can_reshape ) { 4672 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4673 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4674 } 4675 } 4676 } 4677 4678 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4679 // Check if PhiNode::Ideal's "Split phis through memory merges" 4680 // transform should be attempted. Look for this->phi->this cycle. 4681 uint merge_width = req(); 4682 if (merge_width > Compile::AliasIdxRaw) { 4683 PhiNode* phi = base_memory()->as_Phi(); 4684 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4685 if (phi->in(i) == this) { 4686 phase->is_IterGVN()->_worklist.push(phi); 4687 break; 4688 } 4689 } 4690 } 4691 } 4692 4693 assert(progress || verify_sparse(), "please, no dups of base"); 4694 return progress; 4695 } 4696 4697 //-------------------------set_base_memory------------------------------------- 4698 void MergeMemNode::set_base_memory(Node *new_base) { 4699 Node* empty_mem = empty_memory(); 4700 set_req(Compile::AliasIdxBot, new_base); 4701 assert(memory_at(req()) == new_base, "must set default memory"); 4702 // Clear out other occurrences of new_base: 4703 if (new_base != empty_mem) { 4704 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4705 if (in(i) == new_base) set_req(i, empty_mem); 4706 } 4707 } 4708 } 4709 4710 //------------------------------out_RegMask------------------------------------ 4711 const RegMask &MergeMemNode::out_RegMask() const { 4712 return RegMask::Empty; 4713 } 4714 4715 //------------------------------dump_spec-------------------------------------- 4716 #ifndef PRODUCT 4717 void MergeMemNode::dump_spec(outputStream *st) const { 4718 st->print(" {"); 4719 Node* base_mem = base_memory(); 4720 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4721 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem; 4722 if (mem == base_mem) { st->print(" -"); continue; } 4723 st->print( " N%d:", mem->_idx ); 4724 Compile::current()->get_adr_type(i)->dump_on(st); 4725 } 4726 st->print(" }"); 4727 } 4728 #endif // !PRODUCT 4729 4730 4731 #ifdef ASSERT 4732 static bool might_be_same(Node* a, Node* b) { 4733 if (a == b) return true; 4734 if (!(a->is_Phi() || b->is_Phi())) return false; 4735 // phis shift around during optimization 4736 return true; // pretty stupid... 4737 } 4738 4739 // verify a narrow slice (either incoming or outgoing) 4740 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4741 if (!VerifyAliases) return; // don't bother to verify unless requested 4742 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 4743 if (Node::in_dump()) return; // muzzle asserts when printing 4744 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4745 assert(n != NULL, ""); 4746 // Elide intervening MergeMem's 4747 while (n->is_MergeMem()) { 4748 n = n->as_MergeMem()->memory_at(alias_idx); 4749 } 4750 Compile* C = Compile::current(); 4751 const TypePtr* n_adr_type = n->adr_type(); 4752 if (n == m->empty_memory()) { 4753 // Implicit copy of base_memory() 4754 } else if (n_adr_type != TypePtr::BOTTOM) { 4755 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4756 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4757 } else { 4758 // A few places like make_runtime_call "know" that VM calls are narrow, 4759 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4760 bool expected_wide_mem = false; 4761 if (n == m->base_memory()) { 4762 expected_wide_mem = true; 4763 } else if (alias_idx == Compile::AliasIdxRaw || 4764 n == m->memory_at(Compile::AliasIdxRaw)) { 4765 expected_wide_mem = true; 4766 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4767 // memory can "leak through" calls on channels that 4768 // are write-once. Allow this also. 4769 expected_wide_mem = true; 4770 } 4771 assert(expected_wide_mem, "expected narrow slice replacement"); 4772 } 4773 } 4774 #else // !ASSERT 4775 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4776 #endif 4777 4778 4779 //-----------------------------memory_at--------------------------------------- 4780 Node* MergeMemNode::memory_at(uint alias_idx) const { 4781 assert(alias_idx >= Compile::AliasIdxRaw || 4782 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4783 "must avoid base_memory and AliasIdxTop"); 4784 4785 // Otherwise, it is a narrow slice. 4786 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4787 Compile *C = Compile::current(); 4788 if (is_empty_memory(n)) { 4789 // the array is sparse; empty slots are the "top" node 4790 n = base_memory(); 4791 assert(Node::in_dump() 4792 || n == NULL || n->bottom_type() == Type::TOP 4793 || n->adr_type() == NULL // address is TOP 4794 || n->adr_type() == TypePtr::BOTTOM 4795 || n->adr_type() == TypeRawPtr::BOTTOM 4796 || Compile::current()->AliasLevel() == 0, 4797 "must be a wide memory"); 4798 // AliasLevel == 0 if we are organizing the memory states manually. 4799 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4800 } else { 4801 // make sure the stored slice is sane 4802 #ifdef ASSERT 4803 if (VMError::is_error_reported() || Node::in_dump()) { 4804 } else if (might_be_same(n, base_memory())) { 4805 // Give it a pass: It is a mostly harmless repetition of the base. 4806 // This can arise normally from node subsumption during optimization. 4807 } else { 4808 verify_memory_slice(this, alias_idx, n); 4809 } 4810 #endif 4811 } 4812 return n; 4813 } 4814 4815 //---------------------------set_memory_at------------------------------------- 4816 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4817 verify_memory_slice(this, alias_idx, n); 4818 Node* empty_mem = empty_memory(); 4819 if (n == base_memory()) n = empty_mem; // collapse default 4820 uint need_req = alias_idx+1; 4821 if (req() < need_req) { 4822 if (n == empty_mem) return; // already the default, so do not grow me 4823 // grow the sparse array 4824 do { 4825 add_req(empty_mem); 4826 } while (req() < need_req); 4827 } 4828 set_req( alias_idx, n ); 4829 } 4830 4831 4832 4833 //--------------------------iteration_setup------------------------------------ 4834 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4835 if (other != NULL) { 4836 grow_to_match(other); 4837 // invariant: the finite support of mm2 is within mm->req() 4838 #ifdef ASSERT 4839 for (uint i = req(); i < other->req(); i++) { 4840 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4841 } 4842 #endif 4843 } 4844 // Replace spurious copies of base_memory by top. 4845 Node* base_mem = base_memory(); 4846 if (base_mem != NULL && !base_mem->is_top()) { 4847 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4848 if (in(i) == base_mem) 4849 set_req(i, empty_memory()); 4850 } 4851 } 4852 } 4853 4854 //---------------------------grow_to_match------------------------------------- 4855 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4856 Node* empty_mem = empty_memory(); 4857 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4858 // look for the finite support of the other memory 4859 for (uint i = other->req(); --i >= req(); ) { 4860 if (other->in(i) != empty_mem) { 4861 uint new_len = i+1; 4862 while (req() < new_len) add_req(empty_mem); 4863 break; 4864 } 4865 } 4866 } 4867 4868 //---------------------------verify_sparse------------------------------------- 4869 #ifndef PRODUCT 4870 bool MergeMemNode::verify_sparse() const { 4871 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4872 Node* base_mem = base_memory(); 4873 // The following can happen in degenerate cases, since empty==top. 4874 if (is_empty_memory(base_mem)) return true; 4875 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4876 assert(in(i) != NULL, "sane slice"); 4877 if (in(i) == base_mem) return false; // should have been the sentinel value! 4878 } 4879 return true; 4880 } 4881 4882 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4883 Node* n; 4884 n = mm->in(idx); 4885 if (mem == n) return true; // might be empty_memory() 4886 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4887 if (mem == n) return true; 4888 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4889 if (mem == n) return true; 4890 if (n == NULL) break; 4891 } 4892 return false; 4893 } 4894 #endif // !PRODUCT