1 /* 2 * Copyright (c) 1997, 2019, 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/vmError.hpp" 52 #if INCLUDE_ZGC 53 #include "gc/z/c2/zBarrierSetC2.hpp" 54 #endif 55 56 // Portions of code courtesy of Clifford Click 57 58 // Optimization - Graph Style 59 60 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 61 62 //============================================================================= 63 uint MemNode::size_of() const { return sizeof(*this); } 64 65 const TypePtr *MemNode::adr_type() const { 66 Node* adr = in(Address); 67 if (adr == NULL) return NULL; // node is dead 68 const TypePtr* cross_check = NULL; 69 DEBUG_ONLY(cross_check = _adr_type); 70 return calculate_adr_type(adr->bottom_type(), cross_check); 71 } 72 73 bool MemNode::check_if_adr_maybe_raw(Node* adr) { 74 if (adr != NULL) { 75 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) { 76 return true; 77 } 78 } 79 return false; 80 } 81 82 #ifndef PRODUCT 83 void MemNode::dump_spec(outputStream *st) const { 84 if (in(Address) == NULL) return; // node is dead 85 #ifndef ASSERT 86 // fake the missing field 87 const TypePtr* _adr_type = NULL; 88 if (in(Address) != NULL) 89 _adr_type = in(Address)->bottom_type()->isa_ptr(); 90 #endif 91 dump_adr_type(this, _adr_type, st); 92 93 Compile* C = Compile::current(); 94 if (C->alias_type(_adr_type)->is_volatile()) { 95 st->print(" Volatile!"); 96 } 97 if (_unaligned_access) { 98 st->print(" unaligned"); 99 } 100 if (_mismatched_access) { 101 st->print(" mismatched"); 102 } 103 if (_unsafe_access) { 104 st->print(" unsafe"); 105 } 106 } 107 108 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 109 st->print(" @"); 110 if (adr_type == NULL) { 111 st->print("NULL"); 112 } else { 113 adr_type->dump_on(st); 114 Compile* C = Compile::current(); 115 Compile::AliasType* atp = NULL; 116 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 117 if (atp == NULL) 118 st->print(", idx=?\?;"); 119 else if (atp->index() == Compile::AliasIdxBot) 120 st->print(", idx=Bot;"); 121 else if (atp->index() == Compile::AliasIdxTop) 122 st->print(", idx=Top;"); 123 else if (atp->index() == Compile::AliasIdxRaw) 124 st->print(", idx=Raw;"); 125 else { 126 ciField* field = atp->field(); 127 if (field) { 128 st->print(", name="); 129 field->print_name_on(st); 130 } 131 st->print(", idx=%d;", atp->index()); 132 } 133 } 134 } 135 136 extern void print_alias_types(); 137 138 #endif 139 140 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) { 141 assert((t_oop != NULL), "sanity"); 142 bool is_instance = t_oop->is_known_instance_field(); 143 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() && 144 (load != NULL) && load->is_Load() && 145 (phase->is_IterGVN() != NULL); 146 if (!(is_instance || is_boxed_value_load)) 147 return mchain; // don't try to optimize non-instance types 148 uint instance_id = t_oop->instance_id(); 149 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory); 150 Node *prev = NULL; 151 Node *result = mchain; 152 while (prev != result) { 153 prev = result; 154 if (result == start_mem) 155 break; // hit one of our sentinels 156 // skip over a call which does not affect this memory slice 157 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 158 Node *proj_in = result->in(0); 159 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 160 break; // hit one of our sentinels 161 } else if (proj_in->is_Call()) { 162 // ArrayCopyNodes processed here as well 163 CallNode *call = proj_in->as_Call(); 164 if (!call->may_modify(t_oop, phase)) { // returns false for instances 165 result = call->in(TypeFunc::Memory); 166 } 167 } else if (proj_in->is_Initialize()) { 168 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 169 // Stop if this is the initialization for the object instance which 170 // contains this memory slice, otherwise skip over it. 171 if ((alloc == NULL) || (alloc->_idx == instance_id)) { 172 break; 173 } 174 if (is_instance) { 175 result = proj_in->in(TypeFunc::Memory); 176 } else if (is_boxed_value_load) { 177 Node* klass = alloc->in(AllocateNode::KlassNode); 178 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 179 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) { 180 result = proj_in->in(TypeFunc::Memory); // not related allocation 181 } 182 } 183 } else if (proj_in->is_MemBar()) { 184 ArrayCopyNode* ac = NULL; 185 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) { 186 break; 187 } 188 result = proj_in->in(TypeFunc::Memory); 189 } else { 190 assert(false, "unexpected projection"); 191 } 192 } else if (result->is_ClearArray()) { 193 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) { 194 // Can not bypass initialization of the instance 195 // we are looking for. 196 break; 197 } 198 // Otherwise skip it (the call updated 'result' value). 199 } else if (result->is_MergeMem()) { 200 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty); 201 } 202 } 203 return result; 204 } 205 206 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 207 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 208 if (t_oop == NULL) 209 return mchain; // don't try to optimize non-oop types 210 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 211 bool is_instance = t_oop->is_known_instance_field(); 212 PhaseIterGVN *igvn = phase->is_IterGVN(); 213 if (is_instance && igvn != NULL && result->is_Phi()) { 214 PhiNode *mphi = result->as_Phi(); 215 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 216 const TypePtr *t = mphi->adr_type(); 217 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 218 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 219 t->is_oopptr()->cast_to_exactness(true) 220 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 221 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) { 222 // clone the Phi with our address type 223 result = mphi->split_out_instance(t_adr, igvn); 224 } else { 225 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 226 } 227 } 228 return result; 229 } 230 231 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 232 uint alias_idx = phase->C->get_alias_index(tp); 233 Node *mem = mmem; 234 #ifdef ASSERT 235 { 236 // Check that current type is consistent with the alias index used during graph construction 237 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 238 bool consistent = adr_check == NULL || adr_check->empty() || 239 phase->C->must_alias(adr_check, alias_idx ); 240 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 241 if( !consistent && adr_check != NULL && !adr_check->empty() && 242 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 243 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 244 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 245 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 246 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 247 // don't assert if it is dead code. 248 consistent = true; 249 } 250 if( !consistent ) { 251 st->print("alias_idx==%d, adr_check==", alias_idx); 252 if( adr_check == NULL ) { 253 st->print("NULL"); 254 } else { 255 adr_check->dump(); 256 } 257 st->cr(); 258 print_alias_types(); 259 assert(consistent, "adr_check must match alias idx"); 260 } 261 } 262 #endif 263 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 264 // means an array I have not precisely typed yet. Do not do any 265 // alias stuff with it any time soon. 266 const TypeOopPtr *toop = tp->isa_oopptr(); 267 if( tp->base() != Type::AnyPtr && 268 !(toop && 269 toop->klass() != NULL && 270 toop->klass()->is_java_lang_Object() && 271 toop->offset() == Type::OffsetBot) ) { 272 // compress paths and change unreachable cycles to TOP 273 // If not, we can update the input infinitely along a MergeMem cycle 274 // Equivalent code in PhiNode::Ideal 275 Node* m = phase->transform(mmem); 276 // If transformed to a MergeMem, get the desired slice 277 // Otherwise the returned node represents memory for every slice 278 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 279 // Update input if it is progress over what we have now 280 } 281 return mem; 282 } 283 284 //--------------------------Ideal_common--------------------------------------- 285 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. 286 // Unhook non-raw memories from complete (macro-expanded) initializations. 287 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 288 // If our control input is a dead region, kill all below the region 289 Node *ctl = in(MemNode::Control); 290 if (ctl && remove_dead_region(phase, can_reshape)) 291 return this; 292 ctl = in(MemNode::Control); 293 // Don't bother trying to transform a dead node 294 if (ctl && ctl->is_top()) return NodeSentinel; 295 296 PhaseIterGVN *igvn = phase->is_IterGVN(); 297 // Wait if control on the worklist. 298 if (ctl && can_reshape && igvn != NULL) { 299 Node* bol = NULL; 300 Node* cmp = NULL; 301 if (ctl->in(0)->is_If()) { 302 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 303 bol = ctl->in(0)->in(1); 304 if (bol->is_Bool()) 305 cmp = ctl->in(0)->in(1)->in(1); 306 } 307 if (igvn->_worklist.member(ctl) || 308 (bol != NULL && igvn->_worklist.member(bol)) || 309 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 310 // This control path may be dead. 311 // Delay this memory node transformation until the control is processed. 312 phase->is_IterGVN()->_worklist.push(this); 313 return NodeSentinel; // caller will return NULL 314 } 315 } 316 // Ignore if memory is dead, or self-loop 317 Node *mem = in(MemNode::Memory); 318 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL 319 assert(mem != this, "dead loop in MemNode::Ideal"); 320 321 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 322 // This memory slice may be dead. 323 // Delay this mem node transformation until the memory is processed. 324 phase->is_IterGVN()->_worklist.push(this); 325 return NodeSentinel; // caller will return NULL 326 } 327 328 Node *address = in(MemNode::Address); 329 const Type *t_adr = phase->type(address); 330 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL 331 332 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) { 333 // Unsafe off-heap access with zero address. Remove access and other control users 334 // to not confuse optimizations and add a HaltNode to fail if this is ever executed. 335 assert(ctl != NULL, "unsafe accesses should be control dependent"); 336 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) { 337 Node* u = ctl->fast_out(i); 338 if (u != ctl) { 339 igvn->rehash_node_delayed(u); 340 int nb = u->replace_edge(ctl, phase->C->top()); 341 --i, imax -= nb; 342 } 343 } 344 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr)); 345 Node* halt = igvn->transform(new HaltNode(ctl, frame)); 346 phase->C->root()->add_req(halt); 347 return this; 348 } 349 350 if (can_reshape && igvn != NULL && 351 (igvn->_worklist.member(address) || 352 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) { 353 // The address's base and type may change when the address is processed. 354 // Delay this mem node transformation until the address is processed. 355 phase->is_IterGVN()->_worklist.push(this); 356 return NodeSentinel; // caller will return NULL 357 } 358 359 // Do NOT remove or optimize the next lines: ensure a new alias index 360 // is allocated for an oop pointer type before Escape Analysis. 361 // Note: C++ will not remove it since the call has side effect. 362 if (t_adr->isa_oopptr()) { 363 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 364 } 365 366 Node* base = NULL; 367 if (address->is_AddP()) { 368 base = address->in(AddPNode::Base); 369 } 370 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 371 !t_adr->isa_rawptr()) { 372 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 373 // Skip this node optimization if its address has TOP base. 374 return NodeSentinel; // caller will return NULL 375 } 376 377 // Avoid independent memory operations 378 Node* old_mem = mem; 379 380 // The code which unhooks non-raw memories from complete (macro-expanded) 381 // initializations was removed. After macro-expansion all stores catched 382 // by Initialize node became raw stores and there is no information 383 // which memory slices they modify. So it is unsafe to move any memory 384 // operation above these stores. Also in most cases hooked non-raw memories 385 // were already unhooked by using information from detect_ptr_independence() 386 // and find_previous_store(). 387 388 if (mem->is_MergeMem()) { 389 MergeMemNode* mmem = mem->as_MergeMem(); 390 const TypePtr *tp = t_adr->is_ptr(); 391 392 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 393 } 394 395 if (mem != old_mem) { 396 set_req(MemNode::Memory, mem); 397 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) { 398 igvn->_worklist.push(old_mem); 399 } 400 if (phase->type(mem) == Type::TOP) return NodeSentinel; 401 return this; 402 } 403 404 // let the subclass continue analyzing... 405 return NULL; 406 } 407 408 // Helper function for proving some simple control dominations. 409 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 410 // Already assumes that 'dom' is available at 'sub', and that 'sub' 411 // is not a constant (dominated by the method's StartNode). 412 // Used by MemNode::find_previous_store to prove that the 413 // control input of a memory operation predates (dominates) 414 // an allocation it wants to look past. 415 bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 416 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 417 return false; // Conservative answer for dead code 418 419 // Check 'dom'. Skip Proj and CatchProj nodes. 420 dom = dom->find_exact_control(dom); 421 if (dom == NULL || dom->is_top()) 422 return false; // Conservative answer for dead code 423 424 if (dom == sub) { 425 // For the case when, for example, 'sub' is Initialize and the original 426 // 'dom' is Proj node of the 'sub'. 427 return false; 428 } 429 430 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 431 return true; 432 433 // 'dom' dominates 'sub' if its control edge and control edges 434 // of all its inputs dominate or equal to sub's control edge. 435 436 // Currently 'sub' is either Allocate, Initialize or Start nodes. 437 // Or Region for the check in LoadNode::Ideal(); 438 // 'sub' should have sub->in(0) != NULL. 439 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 440 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 441 442 // Get control edge of 'sub'. 443 Node* orig_sub = sub; 444 sub = sub->find_exact_control(sub->in(0)); 445 if (sub == NULL || sub->is_top()) 446 return false; // Conservative answer for dead code 447 448 assert(sub->is_CFG(), "expecting control"); 449 450 if (sub == dom) 451 return true; 452 453 if (sub->is_Start() || sub->is_Root()) 454 return false; 455 456 { 457 // Check all control edges of 'dom'. 458 459 ResourceMark rm; 460 Arena* arena = Thread::current()->resource_area(); 461 Node_List nlist(arena); 462 Unique_Node_List dom_list(arena); 463 464 dom_list.push(dom); 465 bool only_dominating_controls = false; 466 467 for (uint next = 0; next < dom_list.size(); next++) { 468 Node* n = dom_list.at(next); 469 if (n == orig_sub) 470 return false; // One of dom's inputs dominated by sub. 471 if (!n->is_CFG() && n->pinned()) { 472 // Check only own control edge for pinned non-control nodes. 473 n = n->find_exact_control(n->in(0)); 474 if (n == NULL || n->is_top()) 475 return false; // Conservative answer for dead code 476 assert(n->is_CFG(), "expecting control"); 477 dom_list.push(n); 478 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 479 only_dominating_controls = true; 480 } else if (n->is_CFG()) { 481 if (n->dominates(sub, nlist)) 482 only_dominating_controls = true; 483 else 484 return false; 485 } else { 486 // First, own control edge. 487 Node* m = n->find_exact_control(n->in(0)); 488 if (m != NULL) { 489 if (m->is_top()) 490 return false; // Conservative answer for dead code 491 dom_list.push(m); 492 } 493 // Now, the rest of edges. 494 uint cnt = n->req(); 495 for (uint i = 1; i < cnt; i++) { 496 m = n->find_exact_control(n->in(i)); 497 if (m == NULL || m->is_top()) 498 continue; 499 dom_list.push(m); 500 } 501 } 502 } 503 return only_dominating_controls; 504 } 505 } 506 507 //---------------------detect_ptr_independence--------------------------------- 508 // Used by MemNode::find_previous_store to prove that two base 509 // pointers are never equal. 510 // The pointers are accompanied by their associated allocations, 511 // if any, which have been previously discovered by the caller. 512 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 513 Node* p2, AllocateNode* a2, 514 PhaseTransform* phase) { 515 // Attempt to prove that these two pointers cannot be aliased. 516 // They may both manifestly be allocations, and they should differ. 517 // Or, if they are not both allocations, they can be distinct constants. 518 // Otherwise, one is an allocation and the other a pre-existing value. 519 if (a1 == NULL && a2 == NULL) { // neither an allocation 520 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 521 } else if (a1 != NULL && a2 != NULL) { // both allocations 522 return (a1 != a2); 523 } else if (a1 != NULL) { // one allocation a1 524 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 525 return all_controls_dominate(p2, a1); 526 } else { //(a2 != NULL) // one allocation a2 527 return all_controls_dominate(p1, a2); 528 } 529 return false; 530 } 531 532 533 // Find an arraycopy that must have set (can_see_stored_value=true) or 534 // could have set (can_see_stored_value=false) the value for this load 535 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 536 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 537 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 538 Node* mb = mem->in(0); 539 if (mb->in(0) != NULL && mb->in(0)->is_Proj() && 540 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) { 541 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy(); 542 if (ac->is_clonebasic()) { 543 intptr_t offset; 544 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset); 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 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 715 // (the call updated 'mem' value) 716 continue; // (a) advance through independent allocation memory 717 } else { 718 // Can not bypass initialization of the instance 719 // we are looking for. 720 return mem; 721 } 722 } else if (mem->is_MergeMem()) { 723 int alias_idx = phase->C->get_alias_index(adr_type()); 724 mem = mem->as_MergeMem()->memory_at(alias_idx); 725 continue; // (a) advance through independent MergeMem memory 726 } 727 } 728 729 // Unless there is an explicit 'continue', we must bail out here, 730 // because 'mem' is an inscrutable memory state (e.g., a call). 731 break; 732 } 733 734 return NULL; // bail out 735 } 736 737 //----------------------calculate_adr_type------------------------------------- 738 // Helper function. Notices when the given type of address hits top or bottom. 739 // Also, asserts a cross-check of the type against the expected address type. 740 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 741 if (t == Type::TOP) return NULL; // does not touch memory any more? 742 #ifdef PRODUCT 743 cross_check = NULL; 744 #else 745 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL; 746 #endif 747 const TypePtr* tp = t->isa_ptr(); 748 if (tp == NULL) { 749 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 750 return TypePtr::BOTTOM; // touches lots of memory 751 } else { 752 #ifdef ASSERT 753 // %%%% [phh] We don't check the alias index if cross_check is 754 // TypeRawPtr::BOTTOM. Needs to be investigated. 755 if (cross_check != NULL && 756 cross_check != TypePtr::BOTTOM && 757 cross_check != TypeRawPtr::BOTTOM) { 758 // Recheck the alias index, to see if it has changed (due to a bug). 759 Compile* C = Compile::current(); 760 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 761 "must stay in the original alias category"); 762 // The type of the address must be contained in the adr_type, 763 // disregarding "null"-ness. 764 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 765 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 766 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 767 "real address must not escape from expected memory type"); 768 } 769 #endif 770 return tp; 771 } 772 } 773 774 //============================================================================= 775 // Should LoadNode::Ideal() attempt to remove control edges? 776 bool LoadNode::can_remove_control() const { 777 return true; 778 } 779 uint LoadNode::size_of() const { return sizeof(*this); } 780 bool LoadNode::cmp( const Node &n ) const 781 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 782 const Type *LoadNode::bottom_type() const { return _type; } 783 uint LoadNode::ideal_reg() const { 784 return _type->ideal_reg(); 785 } 786 787 #ifndef PRODUCT 788 void LoadNode::dump_spec(outputStream *st) const { 789 MemNode::dump_spec(st); 790 if( !Verbose && !WizardMode ) { 791 // standard dump does this in Verbose and WizardMode 792 st->print(" #"); _type->dump_on(st); 793 } 794 if (!depends_only_on_test()) { 795 st->print(" (does not depend only on test)"); 796 } 797 } 798 #endif 799 800 #ifdef ASSERT 801 //----------------------------is_immutable_value------------------------------- 802 // Helper function to allow a raw load without control edge for some cases 803 bool LoadNode::is_immutable_value(Node* adr) { 804 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 805 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 806 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 807 in_bytes(JavaThread::osthread_offset()))); 808 } 809 #endif 810 811 //----------------------------LoadNode::make----------------------------------- 812 // Polymorphic factory method: 813 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, 814 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) { 815 Compile* C = gvn.C; 816 817 // sanity check the alias category against the created node type 818 assert(!(adr_type->isa_oopptr() && 819 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 820 "use LoadKlassNode instead"); 821 assert(!(adr_type->isa_aryptr() && 822 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 823 "use LoadRangeNode instead"); 824 // Check control edge of raw loads 825 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 826 // oop will be recorded in oop map if load crosses safepoint 827 rt->isa_oopptr() || is_immutable_value(adr), 828 "raw memory operations should have control edge"); 829 LoadNode* load = NULL; 830 switch (bt) { 831 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 832 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 833 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 834 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 835 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 836 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break; 837 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 838 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 839 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break; 840 case T_OBJECT: 841 #ifdef _LP64 842 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 843 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency); 844 } else 845 #endif 846 { 847 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 848 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 849 } 850 break; 851 default: 852 ShouldNotReachHere(); 853 break; 854 } 855 assert(load != NULL, "LoadNode should have been created"); 856 if (unaligned) { 857 load->set_unaligned_access(); 858 } 859 if (mismatched) { 860 load->set_mismatched_access(); 861 } 862 if (unsafe) { 863 load->set_unsafe_access(); 864 } 865 if (load->Opcode() == Op_LoadN) { 866 Node* ld = gvn.transform(load); 867 return new DecodeNNode(ld, ld->bottom_type()->make_ptr()); 868 } 869 870 return load; 871 } 872 873 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 874 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) { 875 bool require_atomic = true; 876 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic); 877 if (unaligned) { 878 load->set_unaligned_access(); 879 } 880 if (mismatched) { 881 load->set_mismatched_access(); 882 } 883 if (unsafe) { 884 load->set_unsafe_access(); 885 } 886 return load; 887 } 888 889 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 890 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) { 891 bool require_atomic = true; 892 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic); 893 if (unaligned) { 894 load->set_unaligned_access(); 895 } 896 if (mismatched) { 897 load->set_mismatched_access(); 898 } 899 if (unsafe) { 900 load->set_unsafe_access(); 901 } 902 return load; 903 } 904 905 906 907 //------------------------------hash------------------------------------------- 908 uint LoadNode::hash() const { 909 // unroll addition of interesting fields 910 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 911 } 912 913 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 914 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 915 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 916 bool is_stable_ary = FoldStableValues && 917 (tp != NULL) && (tp->isa_aryptr() != NULL) && 918 tp->isa_aryptr()->is_stable(); 919 920 return (eliminate_boxing && non_volatile) || is_stable_ary; 921 } 922 923 return false; 924 } 925 926 // Is the value loaded previously stored by an arraycopy? If so return 927 // a load node that reads from the source array so we may be able to 928 // optimize out the ArrayCopy node later. 929 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const { 930 Node* ld_adr = in(MemNode::Address); 931 intptr_t ld_off = 0; 932 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 933 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 934 if (ac != NULL) { 935 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 936 937 Node* mem = ac->in(TypeFunc::Memory); 938 Node* ctl = ac->in(0); 939 Node* src = ac->in(ArrayCopyNode::Src); 940 941 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) { 942 return NULL; 943 } 944 945 LoadNode* ld = clone()->as_Load(); 946 Node* addp = in(MemNode::Address)->clone(); 947 if (ac->as_ArrayCopy()->is_clonebasic()) { 948 assert(ld_alloc != NULL, "need an alloc"); 949 assert(addp->is_AddP(), "address must be addp"); 950 assert(ac->in(ArrayCopyNode::Dest)->is_AddP(), "dest must be an address"); 951 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 952 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base)), "strange pattern"); 953 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address)), "strange pattern"); 954 addp->set_req(AddPNode::Base, src->in(AddPNode::Base)); 955 addp->set_req(AddPNode::Address, src->in(AddPNode::Address)); 956 } else { 957 assert(ac->as_ArrayCopy()->is_arraycopy_validated() || 958 ac->as_ArrayCopy()->is_copyof_validated() || 959 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases"); 960 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 961 addp->set_req(AddPNode::Base, src); 962 addp->set_req(AddPNode::Address, src); 963 964 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 965 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 966 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 967 uint shift = exact_log2(type2aelembytes(ary_elem)); 968 969 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 970 #ifdef _LP64 971 diff = phase->transform(new ConvI2LNode(diff)); 972 #endif 973 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 974 975 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 976 addp->set_req(AddPNode::Offset, offset); 977 } 978 addp = phase->transform(addp); 979 #ifdef ASSERT 980 const TypePtr* adr_type = phase->type(addp)->is_ptr(); 981 ld->_adr_type = adr_type; 982 #endif 983 ld->set_req(MemNode::Address, addp); 984 ld->set_req(0, ctl); 985 ld->set_req(MemNode::Memory, mem); 986 // load depends on the tests that validate the arraycopy 987 ld->_control_dependency = Pinned; 988 return ld; 989 } 990 return NULL; 991 } 992 993 994 //---------------------------can_see_stored_value------------------------------ 995 // This routine exists to make sure this set of tests is done the same 996 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 997 // will change the graph shape in a way which makes memory alive twice at the 998 // same time (uses the Oracle model of aliasing), then some 999 // LoadXNode::Identity will fold things back to the equivalence-class model 1000 // of aliasing. 1001 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 1002 Node* ld_adr = in(MemNode::Address); 1003 intptr_t ld_off = 0; 1004 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off); 1005 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase); 1006 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 1007 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 1008 // This is more general than load from boxing objects. 1009 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 1010 uint alias_idx = atp->index(); 1011 bool final = !atp->is_rewritable(); 1012 Node* result = NULL; 1013 Node* current = st; 1014 // Skip through chains of MemBarNodes checking the MergeMems for 1015 // new states for the slice of this load. Stop once any other 1016 // kind of node is encountered. Loads from final memory can skip 1017 // through any kind of MemBar but normal loads shouldn't skip 1018 // through MemBarAcquire since the could allow them to move out of 1019 // a synchronized region. 1020 while (current->is_Proj()) { 1021 int opc = current->in(0)->Opcode(); 1022 if ((final && (opc == Op_MemBarAcquire || 1023 opc == Op_MemBarAcquireLock || 1024 opc == Op_LoadFence)) || 1025 opc == Op_MemBarRelease || 1026 opc == Op_StoreFence || 1027 opc == Op_MemBarReleaseLock || 1028 opc == Op_MemBarStoreStore || 1029 opc == Op_MemBarCPUOrder) { 1030 Node* mem = current->in(0)->in(TypeFunc::Memory); 1031 if (mem->is_MergeMem()) { 1032 MergeMemNode* merge = mem->as_MergeMem(); 1033 Node* new_st = merge->memory_at(alias_idx); 1034 if (new_st == merge->base_memory()) { 1035 // Keep searching 1036 current = new_st; 1037 continue; 1038 } 1039 // Save the new memory state for the slice and fall through 1040 // to exit. 1041 result = new_st; 1042 } 1043 } 1044 break; 1045 } 1046 if (result != NULL) { 1047 st = result; 1048 } 1049 } 1050 1051 // Loop around twice in the case Load -> Initialize -> Store. 1052 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1053 for (int trip = 0; trip <= 1; trip++) { 1054 1055 if (st->is_Store()) { 1056 Node* st_adr = st->in(MemNode::Address); 1057 if (!phase->eqv(st_adr, ld_adr)) { 1058 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers). 1059 intptr_t st_off = 0; 1060 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off); 1061 if (ld_base == NULL) return NULL; 1062 if (st_base == NULL) return NULL; 1063 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL; 1064 if (ld_off != st_off) return NULL; 1065 if (ld_off == Type::OffsetBot) return NULL; 1066 // Same base, same offset. 1067 // Possible improvement for arrays: check index value instead of absolute offset. 1068 1069 // At this point we have proven something like this setup: 1070 // B = << base >> 1071 // L = LoadQ(AddP(Check/CastPP(B), #Off)) 1072 // S = StoreQ(AddP( B , #Off), V) 1073 // (Actually, we haven't yet proven the Q's are the same.) 1074 // In other words, we are loading from a casted version of 1075 // the same pointer-and-offset that we stored to. 1076 // Casted version may carry a dependency and it is respected. 1077 // Thus, we are able to replace L by V. 1078 } 1079 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1080 if (store_Opcode() != st->Opcode()) 1081 return NULL; 1082 return st->in(MemNode::ValueIn); 1083 } 1084 1085 // A load from a freshly-created object always returns zero. 1086 // (This can happen after LoadNode::Ideal resets the load's memory input 1087 // to find_captured_store, which returned InitializeNode::zero_memory.) 1088 if (st->is_Proj() && st->in(0)->is_Allocate() && 1089 (st->in(0) == ld_alloc) && 1090 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1091 // return a zero value for the load's basic type 1092 // (This is one of the few places where a generic PhaseTransform 1093 // can create new nodes. Think of it as lazily manifesting 1094 // virtually pre-existing constants.) 1095 return phase->zerocon(memory_type()); 1096 } 1097 1098 // A load from an initialization barrier can match a captured store. 1099 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1100 InitializeNode* init = st->in(0)->as_Initialize(); 1101 AllocateNode* alloc = init->allocation(); 1102 if ((alloc != NULL) && (alloc == ld_alloc)) { 1103 // examine a captured store value 1104 st = init->find_captured_store(ld_off, memory_size(), phase); 1105 if (st != NULL) { 1106 continue; // take one more trip around 1107 } 1108 } 1109 } 1110 1111 // Load boxed value from result of valueOf() call is input parameter. 1112 if (this->is_Load() && ld_adr->is_AddP() && 1113 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1114 intptr_t ignore = 0; 1115 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1116 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 1117 base = bs->step_over_gc_barrier(base); 1118 if (base != NULL && base->is_Proj() && 1119 base->as_Proj()->_con == TypeFunc::Parms && 1120 base->in(0)->is_CallStaticJava() && 1121 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1122 return base->in(0)->in(TypeFunc::Parms); 1123 } 1124 } 1125 1126 break; 1127 } 1128 1129 return NULL; 1130 } 1131 1132 //----------------------is_instance_field_load_with_local_phi------------------ 1133 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1134 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1135 in(Address)->is_AddP() ) { 1136 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1137 // Only instances and boxed values. 1138 if( t_oop != NULL && 1139 (t_oop->is_ptr_to_boxed_value() || 1140 t_oop->is_known_instance_field()) && 1141 t_oop->offset() != Type::OffsetBot && 1142 t_oop->offset() != Type::OffsetTop) { 1143 return true; 1144 } 1145 } 1146 return false; 1147 } 1148 1149 //------------------------------Identity--------------------------------------- 1150 // Loads are identity if previous store is to same address 1151 Node* LoadNode::Identity(PhaseGVN* phase) { 1152 // If the previous store-maker is the right kind of Store, and the store is 1153 // to the same address, then we are equal to the value stored. 1154 Node* mem = in(Memory); 1155 Node* value = can_see_stored_value(mem, phase); 1156 if( value ) { 1157 // byte, short & char stores truncate naturally. 1158 // A load has to load the truncated value which requires 1159 // some sort of masking operation and that requires an 1160 // Ideal call instead of an Identity call. 1161 if (memory_size() < BytesPerInt) { 1162 // If the input to the store does not fit with the load's result type, 1163 // it must be truncated via an Ideal call. 1164 if (!phase->type(value)->higher_equal(phase->type(this))) 1165 return this; 1166 } 1167 // (This works even when value is a Con, but LoadNode::Value 1168 // usually runs first, producing the singleton type of the Con.) 1169 return value; 1170 } 1171 1172 // Search for an existing data phi which was generated before for the same 1173 // instance's field to avoid infinite generation of phis in a loop. 1174 Node *region = mem->in(0); 1175 if (is_instance_field_load_with_local_phi(region)) { 1176 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1177 int this_index = phase->C->get_alias_index(addr_t); 1178 int this_offset = addr_t->offset(); 1179 int this_iid = addr_t->instance_id(); 1180 if (!addr_t->is_known_instance() && 1181 addr_t->is_ptr_to_boxed_value()) { 1182 // Use _idx of address base (could be Phi node) for boxed values. 1183 intptr_t ignore = 0; 1184 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1185 if (base == NULL) { 1186 return this; 1187 } 1188 this_iid = base->_idx; 1189 } 1190 const Type* this_type = bottom_type(); 1191 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1192 Node* phi = region->fast_out(i); 1193 if (phi->is_Phi() && phi != mem && 1194 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) { 1195 return phi; 1196 } 1197 } 1198 } 1199 1200 return this; 1201 } 1202 1203 // Construct an equivalent unsigned load. 1204 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) { 1205 BasicType bt = T_ILLEGAL; 1206 const Type* rt = NULL; 1207 switch (Opcode()) { 1208 case Op_LoadUB: return this; 1209 case Op_LoadUS: return this; 1210 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break; 1211 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break; 1212 default: 1213 assert(false, "no unsigned variant: %s", Name()); 1214 return NULL; 1215 } 1216 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1217 raw_adr_type(), rt, bt, _mo, _control_dependency, 1218 is_unaligned_access(), is_mismatched_access()); 1219 } 1220 1221 // Construct an equivalent signed load. 1222 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) { 1223 BasicType bt = T_ILLEGAL; 1224 const Type* rt = NULL; 1225 switch (Opcode()) { 1226 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break; 1227 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break; 1228 case Op_LoadB: // fall through 1229 case Op_LoadS: // fall through 1230 case Op_LoadI: // fall through 1231 case Op_LoadL: return this; 1232 default: 1233 assert(false, "no signed variant: %s", Name()); 1234 return NULL; 1235 } 1236 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1237 raw_adr_type(), rt, bt, _mo, _control_dependency, 1238 is_unaligned_access(), is_mismatched_access()); 1239 } 1240 1241 // We're loading from an object which has autobox behaviour. 1242 // If this object is result of a valueOf call we'll have a phi 1243 // merging a newly allocated object and a load from the cache. 1244 // We want to replace this load with the original incoming 1245 // argument to the valueOf call. 1246 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1247 assert(phase->C->eliminate_boxing(), "sanity"); 1248 intptr_t ignore = 0; 1249 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1250 if ((base == NULL) || base->is_Phi()) { 1251 // Push the loads from the phi that comes from valueOf up 1252 // through it to allow elimination of the loads and the recovery 1253 // of the original value. It is done in split_through_phi(). 1254 return NULL; 1255 } else if (base->is_Load() || 1256 (base->is_DecodeN() && base->in(1)->is_Load())) { 1257 // Eliminate the load of boxed value for integer types from the cache 1258 // array by deriving the value from the index into the array. 1259 // Capture the offset of the load and then reverse the computation. 1260 1261 // Get LoadN node which loads a boxing object from 'cache' array. 1262 if (base->is_DecodeN()) { 1263 base = base->in(1); 1264 } 1265 if (!base->in(Address)->is_AddP()) { 1266 return NULL; // Complex address 1267 } 1268 AddPNode* address = base->in(Address)->as_AddP(); 1269 Node* cache_base = address->in(AddPNode::Base); 1270 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1271 // Get ConP node which is static 'cache' field. 1272 cache_base = cache_base->in(1); 1273 } 1274 if ((cache_base != NULL) && cache_base->is_Con()) { 1275 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1276 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1277 Node* elements[4]; 1278 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1279 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1280 if (count > 0 && elements[0]->is_Con() && 1281 (count == 1 || 1282 (count == 2 && elements[1]->Opcode() == Op_LShiftX && 1283 elements[1]->in(2) == phase->intcon(shift)))) { 1284 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1285 // Fetch the box object cache[0] at the base of the array and get its value 1286 ciInstance* box = array->obj_at(0)->as_instance(); 1287 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1288 assert(ik->is_box_klass(), "sanity"); 1289 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1290 if (ik->nof_nonstatic_fields() == 1) { 1291 // This should be true nonstatic_field_at requires calling 1292 // nof_nonstatic_fields so check it anyway 1293 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1294 BasicType bt = c.basic_type(); 1295 // Only integer types have boxing cache. 1296 assert(bt == T_BOOLEAN || bt == T_CHAR || 1297 bt == T_BYTE || bt == T_SHORT || 1298 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt)); 1299 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1300 if (cache_low != (int)cache_low) { 1301 return NULL; // should not happen since cache is array indexed by value 1302 } 1303 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1304 if (offset != (int)offset) { 1305 return NULL; // should not happen since cache is array indexed by value 1306 } 1307 // Add up all the offsets making of the address of the load 1308 Node* result = elements[0]; 1309 for (int i = 1; i < count; i++) { 1310 result = phase->transform(new AddXNode(result, elements[i])); 1311 } 1312 // Remove the constant offset from the address and then 1313 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset))); 1314 // remove the scaling of the offset to recover the original index. 1315 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1316 // Peel the shift off directly but wrap it in a dummy node 1317 // since Ideal can't return existing nodes 1318 result = new RShiftXNode(result->in(1), phase->intcon(0)); 1319 } else if (result->is_Add() && result->in(2)->is_Con() && 1320 result->in(1)->Opcode() == Op_LShiftX && 1321 result->in(1)->in(2) == phase->intcon(shift)) { 1322 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1323 // but for boxing cache access we know that X<<Z will not overflow 1324 // (there is range check) so we do this optimizatrion by hand here. 1325 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift)); 1326 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con)); 1327 } else { 1328 result = new RShiftXNode(result, phase->intcon(shift)); 1329 } 1330 #ifdef _LP64 1331 if (bt != T_LONG) { 1332 result = new ConvL2INode(phase->transform(result)); 1333 } 1334 #else 1335 if (bt == T_LONG) { 1336 result = new ConvI2LNode(phase->transform(result)); 1337 } 1338 #endif 1339 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1340 // Need to preserve unboxing load type if it is unsigned. 1341 switch(this->Opcode()) { 1342 case Op_LoadUB: 1343 result = new AndINode(phase->transform(result), phase->intcon(0xFF)); 1344 break; 1345 case Op_LoadUS: 1346 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF)); 1347 break; 1348 } 1349 return result; 1350 } 1351 } 1352 } 1353 } 1354 } 1355 return NULL; 1356 } 1357 1358 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1359 Node* region = phi->in(0); 1360 if (region == NULL) { 1361 return false; // Wait stable graph 1362 } 1363 uint cnt = phi->req(); 1364 for (uint i = 1; i < cnt; i++) { 1365 Node* rc = region->in(i); 1366 if (rc == NULL || phase->type(rc) == Type::TOP) 1367 return false; // Wait stable graph 1368 Node* in = phi->in(i); 1369 if (in == NULL || phase->type(in) == Type::TOP) 1370 return false; // Wait stable graph 1371 } 1372 return true; 1373 } 1374 //------------------------------split_through_phi------------------------------ 1375 // Split instance or boxed field load through Phi. 1376 Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1377 Node* mem = in(Memory); 1378 Node* address = in(Address); 1379 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1380 1381 assert((t_oop != NULL) && 1382 (t_oop->is_known_instance_field() || 1383 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1384 1385 Compile* C = phase->C; 1386 intptr_t ignore = 0; 1387 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1388 bool base_is_phi = (base != NULL) && base->is_Phi(); 1389 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1390 (base != NULL) && (base == address->in(AddPNode::Base)) && 1391 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1392 1393 if (!((mem->is_Phi() || base_is_phi) && 1394 (load_boxed_values || t_oop->is_known_instance_field()))) { 1395 return NULL; // memory is not Phi 1396 } 1397 1398 if (mem->is_Phi()) { 1399 if (!stable_phi(mem->as_Phi(), phase)) { 1400 return NULL; // Wait stable graph 1401 } 1402 uint cnt = mem->req(); 1403 // Check for loop invariant memory. 1404 if (cnt == 3) { 1405 for (uint i = 1; i < cnt; i++) { 1406 Node* in = mem->in(i); 1407 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1408 if (m == mem) { 1409 if (i == 1) { 1410 // if the first edge was a loop, check second edge too. 1411 // If both are replaceable - we are in an infinite loop 1412 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase); 1413 if (n == mem) { 1414 break; 1415 } 1416 } 1417 set_req(Memory, mem->in(cnt - i)); 1418 return this; // made change 1419 } 1420 } 1421 } 1422 } 1423 if (base_is_phi) { 1424 if (!stable_phi(base->as_Phi(), phase)) { 1425 return NULL; // Wait stable graph 1426 } 1427 uint cnt = base->req(); 1428 // Check for loop invariant memory. 1429 if (cnt == 3) { 1430 for (uint i = 1; i < cnt; i++) { 1431 if (base->in(i) == base) { 1432 return NULL; // Wait stable graph 1433 } 1434 } 1435 } 1436 } 1437 1438 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0)); 1439 1440 // Split through Phi (see original code in loopopts.cpp). 1441 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1442 1443 // Do nothing here if Identity will find a value 1444 // (to avoid infinite chain of value phis generation). 1445 if (!phase->eqv(this, phase->apply_identity(this))) 1446 return NULL; 1447 1448 // Select Region to split through. 1449 Node* region; 1450 if (!base_is_phi) { 1451 assert(mem->is_Phi(), "sanity"); 1452 region = mem->in(0); 1453 // Skip if the region dominates some control edge of the address. 1454 if (!MemNode::all_controls_dominate(address, region)) 1455 return NULL; 1456 } else if (!mem->is_Phi()) { 1457 assert(base_is_phi, "sanity"); 1458 region = base->in(0); 1459 // Skip if the region dominates some control edge of the memory. 1460 if (!MemNode::all_controls_dominate(mem, region)) 1461 return NULL; 1462 } else if (base->in(0) != mem->in(0)) { 1463 assert(base_is_phi && mem->is_Phi(), "sanity"); 1464 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1465 region = base->in(0); 1466 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1467 region = mem->in(0); 1468 } else { 1469 return NULL; // complex graph 1470 } 1471 } else { 1472 assert(base->in(0) == mem->in(0), "sanity"); 1473 region = mem->in(0); 1474 } 1475 1476 const Type* this_type = this->bottom_type(); 1477 int this_index = C->get_alias_index(t_oop); 1478 int this_offset = t_oop->offset(); 1479 int this_iid = t_oop->instance_id(); 1480 if (!t_oop->is_known_instance() && load_boxed_values) { 1481 // Use _idx of address base for boxed values. 1482 this_iid = base->_idx; 1483 } 1484 PhaseIterGVN* igvn = phase->is_IterGVN(); 1485 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset); 1486 for (uint i = 1; i < region->req(); i++) { 1487 Node* x; 1488 Node* the_clone = NULL; 1489 if (region->in(i) == C->top()) { 1490 x = C->top(); // Dead path? Use a dead data op 1491 } else { 1492 x = this->clone(); // Else clone up the data op 1493 the_clone = x; // Remember for possible deletion. 1494 // Alter data node to use pre-phi inputs 1495 if (this->in(0) == region) { 1496 x->set_req(0, region->in(i)); 1497 } else { 1498 x->set_req(0, NULL); 1499 } 1500 if (mem->is_Phi() && (mem->in(0) == region)) { 1501 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1502 } 1503 if (address->is_Phi() && address->in(0) == region) { 1504 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1505 } 1506 if (base_is_phi && (base->in(0) == region)) { 1507 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1508 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1509 x->set_req(Address, adr_x); 1510 } 1511 } 1512 // Check for a 'win' on some paths 1513 const Type *t = x->Value(igvn); 1514 1515 bool singleton = t->singleton(); 1516 1517 // See comments in PhaseIdealLoop::split_thru_phi(). 1518 if (singleton && t == Type::TOP) { 1519 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1520 } 1521 1522 if (singleton) { 1523 x = igvn->makecon(t); 1524 } else { 1525 // We now call Identity to try to simplify the cloned node. 1526 // Note that some Identity methods call phase->type(this). 1527 // Make sure that the type array is big enough for 1528 // our new node, even though we may throw the node away. 1529 // (This tweaking with igvn only works because x is a new node.) 1530 igvn->set_type(x, t); 1531 // If x is a TypeNode, capture any more-precise type permanently into Node 1532 // otherwise it will be not updated during igvn->transform since 1533 // igvn->type(x) is set to x->Value() already. 1534 x->raise_bottom_type(t); 1535 Node *y = igvn->apply_identity(x); 1536 if (y != x) { 1537 x = y; 1538 } else { 1539 y = igvn->hash_find_insert(x); 1540 if (y) { 1541 x = y; 1542 } else { 1543 // Else x is a new node we are keeping 1544 // We do not need register_new_node_with_optimizer 1545 // because set_type has already been called. 1546 igvn->_worklist.push(x); 1547 } 1548 } 1549 } 1550 if (x != the_clone && the_clone != NULL) { 1551 igvn->remove_dead_node(the_clone); 1552 } 1553 phi->set_req(i, x); 1554 } 1555 // Record Phi 1556 igvn->register_new_node_with_optimizer(phi); 1557 return phi; 1558 } 1559 1560 //------------------------------Ideal------------------------------------------ 1561 // If the load is from Field memory and the pointer is non-null, it might be possible to 1562 // zero out the control input. 1563 // If the offset is constant and the base is an object allocation, 1564 // try to hook me up to the exact initializing store. 1565 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1566 Node* p = MemNode::Ideal_common(phase, can_reshape); 1567 if (p) return (p == NodeSentinel) ? NULL : p; 1568 1569 Node* ctrl = in(MemNode::Control); 1570 Node* address = in(MemNode::Address); 1571 bool progress = false; 1572 1573 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) && 1574 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes()); 1575 1576 // Skip up past a SafePoint control. Cannot do this for Stores because 1577 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1578 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1579 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw && 1580 !addr_mark ) { 1581 ctrl = ctrl->in(0); 1582 set_req(MemNode::Control,ctrl); 1583 progress = true; 1584 } 1585 1586 intptr_t ignore = 0; 1587 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1588 if (base != NULL 1589 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1590 // Check for useless control edge in some common special cases 1591 if (in(MemNode::Control) != NULL 1592 && can_remove_control() 1593 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1594 && all_controls_dominate(base, phase->C->start())) { 1595 // A method-invariant, non-null address (constant or 'this' argument). 1596 set_req(MemNode::Control, NULL); 1597 progress = true; 1598 } 1599 } 1600 1601 Node* mem = in(MemNode::Memory); 1602 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1603 1604 if (can_reshape && (addr_t != NULL)) { 1605 // try to optimize our memory input 1606 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1607 if (opt_mem != mem) { 1608 set_req(MemNode::Memory, opt_mem); 1609 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1610 return this; 1611 } 1612 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1613 if ((t_oop != NULL) && 1614 (t_oop->is_known_instance_field() || 1615 t_oop->is_ptr_to_boxed_value())) { 1616 PhaseIterGVN *igvn = phase->is_IterGVN(); 1617 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1618 // Delay this transformation until memory Phi is processed. 1619 phase->is_IterGVN()->_worklist.push(this); 1620 return NULL; 1621 } 1622 // Split instance field load through Phi. 1623 Node* result = split_through_phi(phase); 1624 if (result != NULL) return result; 1625 1626 if (t_oop->is_ptr_to_boxed_value()) { 1627 Node* result = eliminate_autobox(phase); 1628 if (result != NULL) return result; 1629 } 1630 } 1631 } 1632 1633 // Is there a dominating load that loads the same value? Leave 1634 // anything that is not a load of a field/array element (like 1635 // barriers etc.) alone 1636 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) { 1637 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 1638 Node *use = mem->fast_out(i); 1639 if (use != this && 1640 use->Opcode() == Opcode() && 1641 use->in(0) != NULL && 1642 use->in(0) != in(0) && 1643 use->in(Address) == in(Address)) { 1644 Node* ctl = in(0); 1645 for (int i = 0; i < 10 && ctl != NULL; i++) { 1646 ctl = IfNode::up_one_dom(ctl); 1647 if (ctl == use->in(0)) { 1648 set_req(0, use->in(0)); 1649 return this; 1650 } 1651 } 1652 } 1653 } 1654 } 1655 1656 // Check for prior store with a different base or offset; make Load 1657 // independent. Skip through any number of them. Bail out if the stores 1658 // are in an endless dead cycle and report no progress. This is a key 1659 // transform for Reflection. However, if after skipping through the Stores 1660 // we can't then fold up against a prior store do NOT do the transform as 1661 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1662 // array memory alive twice: once for the hoisted Load and again after the 1663 // bypassed Store. This situation only works if EVERYBODY who does 1664 // anti-dependence work knows how to bypass. I.e. we need all 1665 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1666 // the alias index stuff. So instead, peek through Stores and IFF we can 1667 // fold up, do so. 1668 Node* prev_mem = find_previous_store(phase); 1669 if (prev_mem != NULL) { 1670 Node* value = can_see_arraycopy_value(prev_mem, phase); 1671 if (value != NULL) { 1672 return value; 1673 } 1674 } 1675 // Steps (a), (b): Walk past independent stores to find an exact match. 1676 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1677 // (c) See if we can fold up on the spot, but don't fold up here. 1678 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1679 // just return a prior value, which is done by Identity calls. 1680 if (can_see_stored_value(prev_mem, phase)) { 1681 // Make ready for step (d): 1682 set_req(MemNode::Memory, prev_mem); 1683 return this; 1684 } 1685 } 1686 1687 return progress ? this : NULL; 1688 } 1689 1690 // Helper to recognize certain Klass fields which are invariant across 1691 // some group of array types (e.g., int[] or all T[] where T < Object). 1692 const Type* 1693 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1694 ciKlass* klass) const { 1695 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1696 // The field is Klass::_modifier_flags. Return its (constant) value. 1697 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1698 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1699 return TypeInt::make(klass->modifier_flags()); 1700 } 1701 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1702 // The field is Klass::_access_flags. Return its (constant) value. 1703 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1704 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1705 return TypeInt::make(klass->access_flags()); 1706 } 1707 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1708 // The field is Klass::_layout_helper. Return its constant value if known. 1709 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1710 return TypeInt::make(klass->layout_helper()); 1711 } 1712 1713 // No match. 1714 return NULL; 1715 } 1716 1717 //------------------------------Value----------------------------------------- 1718 const Type* LoadNode::Value(PhaseGVN* phase) const { 1719 // Either input is TOP ==> the result is TOP 1720 Node* mem = in(MemNode::Memory); 1721 const Type *t1 = phase->type(mem); 1722 if (t1 == Type::TOP) return Type::TOP; 1723 Node* adr = in(MemNode::Address); 1724 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1725 if (tp == NULL || tp->empty()) return Type::TOP; 1726 int off = tp->offset(); 1727 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1728 Compile* C = phase->C; 1729 1730 // Try to guess loaded type from pointer type 1731 if (tp->isa_aryptr()) { 1732 const TypeAryPtr* ary = tp->is_aryptr(); 1733 const Type* t = ary->elem(); 1734 1735 // Determine whether the reference is beyond the header or not, by comparing 1736 // the offset against the offset of the start of the array's data. 1737 // Different array types begin at slightly different offsets (12 vs. 16). 1738 // We choose T_BYTE as an example base type that is least restrictive 1739 // as to alignment, which will therefore produce the smallest 1740 // possible base offset. 1741 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1742 const bool off_beyond_header = (off >= min_base_off); 1743 1744 // Try to constant-fold a stable array element. 1745 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) { 1746 // Make sure the reference is not into the header and the offset is constant 1747 ciObject* aobj = ary->const_oop(); 1748 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1749 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0); 1750 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, 1751 stable_dimension, 1752 memory_type(), is_unsigned()); 1753 if (con_type != NULL) { 1754 return con_type; 1755 } 1756 } 1757 } 1758 1759 // Don't do this for integer types. There is only potential profit if 1760 // the element type t is lower than _type; that is, for int types, if _type is 1761 // more restrictive than t. This only happens here if one is short and the other 1762 // char (both 16 bits), and in those cases we've made an intentional decision 1763 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1764 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1765 // 1766 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1767 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1768 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1769 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1770 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1771 // In fact, that could have been the original type of p1, and p1 could have 1772 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1773 // expression (LShiftL quux 3) independently optimized to the constant 8. 1774 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1775 && (_type->isa_vect() == NULL) 1776 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1777 // t might actually be lower than _type, if _type is a unique 1778 // concrete subclass of abstract class t. 1779 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header? 1780 const Type* jt = t->join_speculative(_type); 1781 // In any case, do not allow the join, per se, to empty out the type. 1782 if (jt->empty() && !t->empty()) { 1783 // This can happen if a interface-typed array narrows to a class type. 1784 jt = _type; 1785 } 1786 #ifdef ASSERT 1787 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1788 // The pointers in the autobox arrays are always non-null 1789 Node* base = adr->in(AddPNode::Base); 1790 if ((base != NULL) && base->is_DecodeN()) { 1791 // Get LoadN node which loads IntegerCache.cache field 1792 base = base->in(1); 1793 } 1794 if ((base != NULL) && base->is_Con()) { 1795 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1796 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1797 // It could be narrow oop 1798 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1799 } 1800 } 1801 } 1802 #endif 1803 return jt; 1804 } 1805 } 1806 } else if (tp->base() == Type::InstPtr) { 1807 assert( off != Type::OffsetBot || 1808 // arrays can be cast to Objects 1809 tp->is_oopptr()->klass()->is_java_lang_Object() || 1810 // unsafe field access may not have a constant offset 1811 C->has_unsafe_access(), 1812 "Field accesses must be precise" ); 1813 // For oop loads, we expect the _type to be precise. 1814 1815 // Optimize loads from constant fields. 1816 const TypeInstPtr* tinst = tp->is_instptr(); 1817 ciObject* const_oop = tinst->const_oop(); 1818 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) { 1819 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type()); 1820 if (con_type != NULL) { 1821 return con_type; 1822 } 1823 } 1824 } else if (tp->base() == Type::KlassPtr) { 1825 assert( off != Type::OffsetBot || 1826 // arrays can be cast to Objects 1827 tp->is_klassptr()->klass()->is_java_lang_Object() || 1828 // also allow array-loading from the primary supertype 1829 // array during subtype checks 1830 Opcode() == Op_LoadKlass, 1831 "Field accesses must be precise" ); 1832 // For klass/static loads, we expect the _type to be precise 1833 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) { 1834 /* With mirrors being an indirect in the Klass* 1835 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset)) 1836 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass). 1837 * 1838 * So check the type and klass of the node before the LoadP. 1839 */ 1840 Node* adr2 = adr->in(MemNode::Address); 1841 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 1842 if (tkls != NULL && !StressReflectiveCode) { 1843 ciKlass* klass = tkls->klass(); 1844 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1845 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1846 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1847 return TypeInstPtr::make(klass->java_mirror()); 1848 } 1849 } 1850 } 1851 1852 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1853 if (tkls != NULL && !StressReflectiveCode) { 1854 ciKlass* klass = tkls->klass(); 1855 if (klass->is_loaded() && tkls->klass_is_exact()) { 1856 // We are loading a field from a Klass metaobject whose identity 1857 // is known at compile time (the type is "exact" or "precise"). 1858 // Check for fields we know are maintained as constants by the VM. 1859 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1860 // The field is Klass::_super_check_offset. Return its (constant) value. 1861 // (Folds up type checking code.) 1862 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1863 return TypeInt::make(klass->super_check_offset()); 1864 } 1865 // Compute index into primary_supers array 1866 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1867 // Check for overflowing; use unsigned compare to handle the negative case. 1868 if( depth < ciKlass::primary_super_limit() ) { 1869 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1870 // (Folds up type checking code.) 1871 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1872 ciKlass *ss = klass->super_of_depth(depth); 1873 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1874 } 1875 const Type* aift = load_array_final_field(tkls, klass); 1876 if (aift != NULL) return aift; 1877 } 1878 1879 // We can still check if we are loading from the primary_supers array at a 1880 // shallow enough depth. Even though the klass is not exact, entries less 1881 // than or equal to its super depth are correct. 1882 if (klass->is_loaded() ) { 1883 ciType *inner = klass; 1884 while( inner->is_obj_array_klass() ) 1885 inner = inner->as_obj_array_klass()->base_element_type(); 1886 if( inner->is_instance_klass() && 1887 !inner->as_instance_klass()->flags().is_interface() ) { 1888 // Compute index into primary_supers array 1889 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1890 // Check for overflowing; use unsigned compare to handle the negative case. 1891 if( depth < ciKlass::primary_super_limit() && 1892 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1893 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1894 // (Folds up type checking code.) 1895 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1896 ciKlass *ss = klass->super_of_depth(depth); 1897 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1898 } 1899 } 1900 } 1901 1902 // If the type is enough to determine that the thing is not an array, 1903 // we can give the layout_helper a positive interval type. 1904 // This will help short-circuit some reflective code. 1905 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1906 && !klass->is_array_klass() // not directly typed as an array 1907 && !klass->is_interface() // specifically not Serializable & Cloneable 1908 && !klass->is_java_lang_Object() // not the supertype of all T[] 1909 ) { 1910 // Note: When interfaces are reliable, we can narrow the interface 1911 // test to (klass != Serializable && klass != Cloneable). 1912 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1913 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1914 // The key property of this type is that it folds up tests 1915 // for array-ness, since it proves that the layout_helper is positive. 1916 // Thus, a generic value like the basic object layout helper works fine. 1917 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1918 } 1919 } 1920 1921 // If we are loading from a freshly-allocated object, produce a zero, 1922 // if the load is provably beyond the header of the object. 1923 // (Also allow a variable load from a fresh array to produce zero.) 1924 const TypeOopPtr *tinst = tp->isa_oopptr(); 1925 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1926 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 1927 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 1928 Node* value = can_see_stored_value(mem,phase); 1929 if (value != NULL && value->is_Con()) { 1930 assert(value->bottom_type()->higher_equal(_type),"sanity"); 1931 return value->bottom_type(); 1932 } 1933 } 1934 1935 if (is_instance) { 1936 // If we have an instance type and our memory input is the 1937 // programs's initial memory state, there is no matching store, 1938 // so just return a zero of the appropriate type 1939 Node *mem = in(MemNode::Memory); 1940 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1941 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1942 return Type::get_zero_type(_type->basic_type()); 1943 } 1944 } 1945 return _type; 1946 } 1947 1948 //------------------------------match_edge------------------------------------- 1949 // Do we Match on this edge index or not? Match only the address. 1950 uint LoadNode::match_edge(uint idx) const { 1951 return idx == MemNode::Address; 1952 } 1953 1954 //--------------------------LoadBNode::Ideal-------------------------------------- 1955 // 1956 // If the previous store is to the same address as this load, 1957 // and the value stored was larger than a byte, replace this load 1958 // with the value stored truncated to a byte. If no truncation is 1959 // needed, the replacement is done in LoadNode::Identity(). 1960 // 1961 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1962 Node* mem = in(MemNode::Memory); 1963 Node* value = can_see_stored_value(mem,phase); 1964 if( value && !phase->type(value)->higher_equal( _type ) ) { 1965 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) ); 1966 return new RShiftINode(result, phase->intcon(24)); 1967 } 1968 // Identity call will handle the case where truncation is not needed. 1969 return LoadNode::Ideal(phase, can_reshape); 1970 } 1971 1972 const Type* LoadBNode::Value(PhaseGVN* phase) const { 1973 Node* mem = in(MemNode::Memory); 1974 Node* value = can_see_stored_value(mem,phase); 1975 if (value != NULL && value->is_Con() && 1976 !value->bottom_type()->higher_equal(_type)) { 1977 // If the input to the store does not fit with the load's result type, 1978 // it must be truncated. We can't delay until Ideal call since 1979 // a singleton Value is needed for split_thru_phi optimization. 1980 int con = value->get_int(); 1981 return TypeInt::make((con << 24) >> 24); 1982 } 1983 return LoadNode::Value(phase); 1984 } 1985 1986 //--------------------------LoadUBNode::Ideal------------------------------------- 1987 // 1988 // If the previous store is to the same address as this load, 1989 // and the value stored was larger than a byte, replace this load 1990 // with the value stored truncated to a byte. If no truncation is 1991 // needed, the replacement is done in LoadNode::Identity(). 1992 // 1993 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 1994 Node* mem = in(MemNode::Memory); 1995 Node* value = can_see_stored_value(mem, phase); 1996 if (value && !phase->type(value)->higher_equal(_type)) 1997 return new AndINode(value, phase->intcon(0xFF)); 1998 // Identity call will handle the case where truncation is not needed. 1999 return LoadNode::Ideal(phase, can_reshape); 2000 } 2001 2002 const Type* LoadUBNode::Value(PhaseGVN* phase) const { 2003 Node* mem = in(MemNode::Memory); 2004 Node* value = can_see_stored_value(mem,phase); 2005 if (value != NULL && value->is_Con() && 2006 !value->bottom_type()->higher_equal(_type)) { 2007 // If the input to the store does not fit with the load's result type, 2008 // it must be truncated. We can't delay until Ideal call since 2009 // a singleton Value is needed for split_thru_phi optimization. 2010 int con = value->get_int(); 2011 return TypeInt::make(con & 0xFF); 2012 } 2013 return LoadNode::Value(phase); 2014 } 2015 2016 //--------------------------LoadUSNode::Ideal------------------------------------- 2017 // 2018 // If the previous store is to the same address as this load, 2019 // and the value stored was larger than a char, replace this load 2020 // with the value stored truncated to a char. If no truncation is 2021 // needed, the replacement is done in LoadNode::Identity(). 2022 // 2023 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2024 Node* mem = in(MemNode::Memory); 2025 Node* value = can_see_stored_value(mem,phase); 2026 if( value && !phase->type(value)->higher_equal( _type ) ) 2027 return new AndINode(value,phase->intcon(0xFFFF)); 2028 // Identity call will handle the case where truncation is not needed. 2029 return LoadNode::Ideal(phase, can_reshape); 2030 } 2031 2032 const Type* LoadUSNode::Value(PhaseGVN* phase) const { 2033 Node* mem = in(MemNode::Memory); 2034 Node* value = can_see_stored_value(mem,phase); 2035 if (value != NULL && value->is_Con() && 2036 !value->bottom_type()->higher_equal(_type)) { 2037 // If the input to the store does not fit with the load's result type, 2038 // it must be truncated. We can't delay until Ideal call since 2039 // a singleton Value is needed for split_thru_phi optimization. 2040 int con = value->get_int(); 2041 return TypeInt::make(con & 0xFFFF); 2042 } 2043 return LoadNode::Value(phase); 2044 } 2045 2046 //--------------------------LoadSNode::Ideal-------------------------------------- 2047 // 2048 // If the previous store is to the same address as this load, 2049 // and the value stored was larger than a short, replace this load 2050 // with the value stored truncated to a short. If no truncation is 2051 // needed, the replacement is done in LoadNode::Identity(). 2052 // 2053 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2054 Node* mem = in(MemNode::Memory); 2055 Node* value = can_see_stored_value(mem,phase); 2056 if( value && !phase->type(value)->higher_equal( _type ) ) { 2057 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) ); 2058 return new RShiftINode(result, phase->intcon(16)); 2059 } 2060 // Identity call will handle the case where truncation is not needed. 2061 return LoadNode::Ideal(phase, can_reshape); 2062 } 2063 2064 const Type* LoadSNode::Value(PhaseGVN* phase) const { 2065 Node* mem = in(MemNode::Memory); 2066 Node* value = can_see_stored_value(mem,phase); 2067 if (value != NULL && value->is_Con() && 2068 !value->bottom_type()->higher_equal(_type)) { 2069 // If the input to the store does not fit with the load's result type, 2070 // it must be truncated. We can't delay until Ideal call since 2071 // a singleton Value is needed for split_thru_phi optimization. 2072 int con = value->get_int(); 2073 return TypeInt::make((con << 16) >> 16); 2074 } 2075 return LoadNode::Value(phase); 2076 } 2077 2078 //============================================================================= 2079 //----------------------------LoadKlassNode::make------------------------------ 2080 // Polymorphic factory method: 2081 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2082 // sanity check the alias category against the created node type 2083 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2084 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2085 #ifdef _LP64 2086 if (adr_type->is_ptr_to_narrowklass()) { 2087 assert(UseCompressedClassPointers, "no compressed klasses"); 2088 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2089 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2090 } 2091 #endif 2092 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2093 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2094 } 2095 2096 //------------------------------Value------------------------------------------ 2097 const Type* LoadKlassNode::Value(PhaseGVN* phase) const { 2098 return klass_value_common(phase); 2099 } 2100 2101 // In most cases, LoadKlassNode does not have the control input set. If the control 2102 // input is set, it must not be removed (by LoadNode::Ideal()). 2103 bool LoadKlassNode::can_remove_control() const { 2104 return false; 2105 } 2106 2107 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const { 2108 // Either input is TOP ==> the result is TOP 2109 const Type *t1 = phase->type( in(MemNode::Memory) ); 2110 if (t1 == Type::TOP) return Type::TOP; 2111 Node *adr = in(MemNode::Address); 2112 const Type *t2 = phase->type( adr ); 2113 if (t2 == Type::TOP) return Type::TOP; 2114 const TypePtr *tp = t2->is_ptr(); 2115 if (TypePtr::above_centerline(tp->ptr()) || 2116 tp->ptr() == TypePtr::Null) return Type::TOP; 2117 2118 // Return a more precise klass, if possible 2119 const TypeInstPtr *tinst = tp->isa_instptr(); 2120 if (tinst != NULL) { 2121 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2122 int offset = tinst->offset(); 2123 if (ik == phase->C->env()->Class_klass() 2124 && (offset == java_lang_Class::klass_offset_in_bytes() || 2125 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2126 // We are loading a special hidden field from a Class mirror object, 2127 // the field which points to the VM's Klass metaobject. 2128 ciType* t = tinst->java_mirror_type(); 2129 // java_mirror_type returns non-null for compile-time Class constants. 2130 if (t != NULL) { 2131 // constant oop => constant klass 2132 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2133 if (t->is_void()) { 2134 // We cannot create a void array. Since void is a primitive type return null 2135 // klass. Users of this result need to do a null check on the returned klass. 2136 return TypePtr::NULL_PTR; 2137 } 2138 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2139 } 2140 if (!t->is_klass()) { 2141 // a primitive Class (e.g., int.class) has NULL for a klass field 2142 return TypePtr::NULL_PTR; 2143 } 2144 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2145 return TypeKlassPtr::make(t->as_klass()); 2146 } 2147 // non-constant mirror, so we can't tell what's going on 2148 } 2149 if( !ik->is_loaded() ) 2150 return _type; // Bail out if not loaded 2151 if (offset == oopDesc::klass_offset_in_bytes()) { 2152 if (tinst->klass_is_exact()) { 2153 return TypeKlassPtr::make(ik); 2154 } 2155 // See if we can become precise: no subklasses and no interface 2156 // (Note: We need to support verified interfaces.) 2157 if (!ik->is_interface() && !ik->has_subklass()) { 2158 //assert(!UseExactTypes, "this code should be useless with exact types"); 2159 // Add a dependence; if any subclass added we need to recompile 2160 if (!ik->is_final()) { 2161 // %%% should use stronger assert_unique_concrete_subtype instead 2162 phase->C->dependencies()->assert_leaf_type(ik); 2163 } 2164 // Return precise klass 2165 return TypeKlassPtr::make(ik); 2166 } 2167 2168 // Return root of possible klass 2169 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2170 } 2171 } 2172 2173 // Check for loading klass from an array 2174 const TypeAryPtr *tary = tp->isa_aryptr(); 2175 if( tary != NULL ) { 2176 ciKlass *tary_klass = tary->klass(); 2177 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2178 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2179 if (tary->klass_is_exact()) { 2180 return TypeKlassPtr::make(tary_klass); 2181 } 2182 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2183 // If the klass is an object array, we defer the question to the 2184 // array component klass. 2185 if( ak->is_obj_array_klass() ) { 2186 assert( ak->is_loaded(), "" ); 2187 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2188 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2189 ciInstanceKlass* ik = base_k->as_instance_klass(); 2190 // See if we can become precise: no subklasses and no interface 2191 if (!ik->is_interface() && !ik->has_subklass()) { 2192 //assert(!UseExactTypes, "this code should be useless with exact types"); 2193 // Add a dependence; if any subclass added we need to recompile 2194 if (!ik->is_final()) { 2195 phase->C->dependencies()->assert_leaf_type(ik); 2196 } 2197 // Return precise array klass 2198 return TypeKlassPtr::make(ak); 2199 } 2200 } 2201 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2202 } else { // Found a type-array? 2203 //assert(!UseExactTypes, "this code should be useless with exact types"); 2204 assert( ak->is_type_array_klass(), "" ); 2205 return TypeKlassPtr::make(ak); // These are always precise 2206 } 2207 } 2208 } 2209 2210 // Check for loading klass from an array klass 2211 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2212 if (tkls != NULL && !StressReflectiveCode) { 2213 ciKlass* klass = tkls->klass(); 2214 if( !klass->is_loaded() ) 2215 return _type; // Bail out if not loaded 2216 if( klass->is_obj_array_klass() && 2217 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2218 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2219 // // Always returning precise element type is incorrect, 2220 // // e.g., element type could be object and array may contain strings 2221 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2222 2223 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2224 // according to the element type's subclassing. 2225 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2226 } 2227 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2228 tkls->offset() == in_bytes(Klass::super_offset())) { 2229 ciKlass* sup = klass->as_instance_klass()->super(); 2230 // The field is Klass::_super. Return its (constant) value. 2231 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2232 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2233 } 2234 } 2235 2236 // Bailout case 2237 return LoadNode::Value(phase); 2238 } 2239 2240 //------------------------------Identity--------------------------------------- 2241 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2242 // Also feed through the klass in Allocate(...klass...)._klass. 2243 Node* LoadKlassNode::Identity(PhaseGVN* phase) { 2244 return klass_identity_common(phase); 2245 } 2246 2247 Node* LoadNode::klass_identity_common(PhaseGVN* phase) { 2248 Node* x = LoadNode::Identity(phase); 2249 if (x != this) return x; 2250 2251 // Take apart the address into an oop and and offset. 2252 // Return 'this' if we cannot. 2253 Node* adr = in(MemNode::Address); 2254 intptr_t offset = 0; 2255 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2256 if (base == NULL) return this; 2257 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2258 if (toop == NULL) return this; 2259 2260 // Step over potential GC barrier for OopHandle resolve 2261 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 2262 if (bs->is_gc_barrier_node(base)) { 2263 base = bs->step_over_gc_barrier(base); 2264 } 2265 2266 // We can fetch the klass directly through an AllocateNode. 2267 // This works even if the klass is not constant (clone or newArray). 2268 if (offset == oopDesc::klass_offset_in_bytes()) { 2269 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2270 if (allocated_klass != NULL) { 2271 return allocated_klass; 2272 } 2273 } 2274 2275 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2276 // See inline_native_Class_query for occurrences of these patterns. 2277 // Java Example: x.getClass().isAssignableFrom(y) 2278 // 2279 // This improves reflective code, often making the Class 2280 // mirror go completely dead. (Current exception: Class 2281 // mirrors may appear in debug info, but we could clean them out by 2282 // introducing a new debug info operator for Klass.java_mirror). 2283 2284 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2285 && offset == java_lang_Class::klass_offset_in_bytes()) { 2286 if (base->is_Load()) { 2287 Node* base2 = base->in(MemNode::Address); 2288 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */ 2289 Node* adr2 = base2->in(MemNode::Address); 2290 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2291 if (tkls != NULL && !tkls->empty() 2292 && (tkls->klass()->is_instance_klass() || 2293 tkls->klass()->is_array_klass()) 2294 && adr2->is_AddP() 2295 ) { 2296 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2297 if (tkls->offset() == mirror_field) { 2298 return adr2->in(AddPNode::Base); 2299 } 2300 } 2301 } 2302 } 2303 } 2304 2305 return this; 2306 } 2307 2308 2309 //------------------------------Value------------------------------------------ 2310 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const { 2311 const Type *t = klass_value_common(phase); 2312 if (t == Type::TOP) 2313 return t; 2314 2315 return t->make_narrowklass(); 2316 } 2317 2318 //------------------------------Identity--------------------------------------- 2319 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2320 // Also feed through the klass in Allocate(...klass...)._klass. 2321 Node* LoadNKlassNode::Identity(PhaseGVN* phase) { 2322 Node *x = klass_identity_common(phase); 2323 2324 const Type *t = phase->type( x ); 2325 if( t == Type::TOP ) return x; 2326 if( t->isa_narrowklass()) return x; 2327 assert (!t->isa_narrowoop(), "no narrow oop here"); 2328 2329 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2330 } 2331 2332 //------------------------------Value----------------------------------------- 2333 const Type* LoadRangeNode::Value(PhaseGVN* phase) const { 2334 // Either input is TOP ==> the result is TOP 2335 const Type *t1 = phase->type( in(MemNode::Memory) ); 2336 if( t1 == Type::TOP ) return Type::TOP; 2337 Node *adr = in(MemNode::Address); 2338 const Type *t2 = phase->type( adr ); 2339 if( t2 == Type::TOP ) return Type::TOP; 2340 const TypePtr *tp = t2->is_ptr(); 2341 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2342 const TypeAryPtr *tap = tp->isa_aryptr(); 2343 if( !tap ) return _type; 2344 return tap->size(); 2345 } 2346 2347 //-------------------------------Ideal--------------------------------------- 2348 // Feed through the length in AllocateArray(...length...)._length. 2349 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2350 Node* p = MemNode::Ideal_common(phase, can_reshape); 2351 if (p) return (p == NodeSentinel) ? NULL : p; 2352 2353 // Take apart the address into an oop and and offset. 2354 // Return 'this' if we cannot. 2355 Node* adr = in(MemNode::Address); 2356 intptr_t offset = 0; 2357 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2358 if (base == NULL) return NULL; 2359 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2360 if (tary == NULL) return NULL; 2361 2362 // We can fetch the length directly through an AllocateArrayNode. 2363 // This works even if the length is not constant (clone or newArray). 2364 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2365 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2366 if (alloc != NULL) { 2367 Node* allocated_length = alloc->Ideal_length(); 2368 Node* len = alloc->make_ideal_length(tary, phase); 2369 if (allocated_length != len) { 2370 // New CastII improves on this. 2371 return len; 2372 } 2373 } 2374 } 2375 2376 return NULL; 2377 } 2378 2379 //------------------------------Identity--------------------------------------- 2380 // Feed through the length in AllocateArray(...length...)._length. 2381 Node* LoadRangeNode::Identity(PhaseGVN* phase) { 2382 Node* x = LoadINode::Identity(phase); 2383 if (x != this) return x; 2384 2385 // Take apart the address into an oop and and offset. 2386 // Return 'this' if we cannot. 2387 Node* adr = in(MemNode::Address); 2388 intptr_t offset = 0; 2389 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2390 if (base == NULL) return this; 2391 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2392 if (tary == NULL) return this; 2393 2394 // We can fetch the length directly through an AllocateArrayNode. 2395 // This works even if the length is not constant (clone or newArray). 2396 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2397 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2398 if (alloc != NULL) { 2399 Node* allocated_length = alloc->Ideal_length(); 2400 // Do not allow make_ideal_length to allocate a CastII node. 2401 Node* len = alloc->make_ideal_length(tary, phase, false); 2402 if (allocated_length == len) { 2403 // Return allocated_length only if it would not be improved by a CastII. 2404 return allocated_length; 2405 } 2406 } 2407 } 2408 2409 return this; 2410 2411 } 2412 2413 //============================================================================= 2414 //---------------------------StoreNode::make----------------------------------- 2415 // Polymorphic factory method: 2416 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2417 assert((mo == unordered || mo == release), "unexpected"); 2418 Compile* C = gvn.C; 2419 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2420 ctl != NULL, "raw memory operations should have control edge"); 2421 2422 switch (bt) { 2423 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case 2424 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2425 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2426 case T_CHAR: 2427 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2428 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2429 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2430 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2431 case T_METADATA: 2432 case T_ADDRESS: 2433 case T_OBJECT: 2434 #ifdef _LP64 2435 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2436 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2437 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2438 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2439 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2440 adr->bottom_type()->isa_rawptr())) { 2441 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2442 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2443 } 2444 #endif 2445 { 2446 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2447 } 2448 default: 2449 ShouldNotReachHere(); 2450 return (StoreNode*)NULL; 2451 } 2452 } 2453 2454 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2455 bool require_atomic = true; 2456 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2457 } 2458 2459 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2460 bool require_atomic = true; 2461 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2462 } 2463 2464 2465 //--------------------------bottom_type---------------------------------------- 2466 const Type *StoreNode::bottom_type() const { 2467 return Type::MEMORY; 2468 } 2469 2470 //------------------------------hash------------------------------------------- 2471 uint StoreNode::hash() const { 2472 // unroll addition of interesting fields 2473 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2474 2475 // Since they are not commoned, do not hash them: 2476 return NO_HASH; 2477 } 2478 2479 //------------------------------Ideal------------------------------------------ 2480 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2481 // When a store immediately follows a relevant allocation/initialization, 2482 // try to capture it into the initialization, or hoist it above. 2483 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2484 Node* p = MemNode::Ideal_common(phase, can_reshape); 2485 if (p) return (p == NodeSentinel) ? NULL : p; 2486 2487 Node* mem = in(MemNode::Memory); 2488 Node* address = in(MemNode::Address); 2489 // Back-to-back stores to same address? Fold em up. Generally 2490 // unsafe if I have intervening uses... Also disallowed for StoreCM 2491 // since they must follow each StoreP operation. Redundant StoreCMs 2492 // are eliminated just before matching in final_graph_reshape. 2493 { 2494 Node* st = mem; 2495 // If Store 'st' has more than one use, we cannot fold 'st' away. 2496 // For example, 'st' might be the final state at a conditional 2497 // return. Or, 'st' might be used by some node which is live at 2498 // the same time 'st' is live, which might be unschedulable. So, 2499 // require exactly ONE user until such time as we clone 'mem' for 2500 // each of 'mem's uses (thus making the exactly-1-user-rule hold 2501 // true). 2502 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) { 2503 // Looking at a dead closed cycle of memory? 2504 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2505 assert(Opcode() == st->Opcode() || 2506 st->Opcode() == Op_StoreVector || 2507 Opcode() == Op_StoreVector || 2508 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw || 2509 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode 2510 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy 2511 (is_mismatched_access() || st->as_Store()->is_mismatched_access()), 2512 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]); 2513 2514 if (st->in(MemNode::Address)->eqv_uncast(address) && 2515 st->as_Store()->memory_size() <= this->memory_size()) { 2516 Node* use = st->raw_out(0); 2517 phase->igvn_rehash_node_delayed(use); 2518 if (can_reshape) { 2519 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN()); 2520 } else { 2521 // It's OK to do this in the parser, since DU info is always accurate, 2522 // and the parser always refers to nodes via SafePointNode maps. 2523 use->set_req(MemNode::Memory, st->in(MemNode::Memory)); 2524 } 2525 return this; 2526 } 2527 st = st->in(MemNode::Memory); 2528 } 2529 } 2530 2531 2532 // Capture an unaliased, unconditional, simple store into an initializer. 2533 // Or, if it is independent of the allocation, hoist it above the allocation. 2534 if (ReduceFieldZeroing && /*can_reshape &&*/ 2535 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2536 InitializeNode* init = mem->in(0)->as_Initialize(); 2537 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2538 if (offset > 0) { 2539 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2540 // If the InitializeNode captured me, it made a raw copy of me, 2541 // and I need to disappear. 2542 if (moved != NULL) { 2543 // %%% hack to ensure that Ideal returns a new node: 2544 mem = MergeMemNode::make(mem); 2545 return mem; // fold me away 2546 } 2547 } 2548 } 2549 2550 return NULL; // No further progress 2551 } 2552 2553 //------------------------------Value----------------------------------------- 2554 const Type* StoreNode::Value(PhaseGVN* phase) const { 2555 // Either input is TOP ==> the result is TOP 2556 const Type *t1 = phase->type( in(MemNode::Memory) ); 2557 if( t1 == Type::TOP ) return Type::TOP; 2558 const Type *t2 = phase->type( in(MemNode::Address) ); 2559 if( t2 == Type::TOP ) return Type::TOP; 2560 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2561 if( t3 == Type::TOP ) return Type::TOP; 2562 return Type::MEMORY; 2563 } 2564 2565 //------------------------------Identity--------------------------------------- 2566 // Remove redundant stores: 2567 // Store(m, p, Load(m, p)) changes to m. 2568 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2569 Node* StoreNode::Identity(PhaseGVN* phase) { 2570 Node* mem = in(MemNode::Memory); 2571 Node* adr = in(MemNode::Address); 2572 Node* val = in(MemNode::ValueIn); 2573 2574 Node* result = this; 2575 2576 // Load then Store? Then the Store is useless 2577 if (val->is_Load() && 2578 val->in(MemNode::Address)->eqv_uncast(adr) && 2579 val->in(MemNode::Memory )->eqv_uncast(mem) && 2580 val->as_Load()->store_Opcode() == Opcode()) { 2581 result = mem; 2582 } 2583 2584 // Two stores in a row of the same value? 2585 if (result == this && 2586 mem->is_Store() && 2587 mem->in(MemNode::Address)->eqv_uncast(adr) && 2588 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2589 mem->Opcode() == Opcode()) { 2590 result = mem; 2591 } 2592 2593 // Store of zero anywhere into a freshly-allocated object? 2594 // Then the store is useless. 2595 // (It must already have been captured by the InitializeNode.) 2596 if (result == this && 2597 ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2598 // a newly allocated object is already all-zeroes everywhere 2599 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2600 result = mem; 2601 } 2602 2603 if (result == this) { 2604 // the store may also apply to zero-bits in an earlier object 2605 Node* prev_mem = find_previous_store(phase); 2606 // Steps (a), (b): Walk past independent stores to find an exact match. 2607 if (prev_mem != NULL) { 2608 Node* prev_val = can_see_stored_value(prev_mem, phase); 2609 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2610 // prev_val and val might differ by a cast; it would be good 2611 // to keep the more informative of the two. 2612 result = mem; 2613 } 2614 } 2615 } 2616 } 2617 2618 if (result != this && phase->is_IterGVN() != NULL) { 2619 MemBarNode* trailing = trailing_membar(); 2620 if (trailing != NULL) { 2621 #ifdef ASSERT 2622 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr(); 2623 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects"); 2624 #endif 2625 PhaseIterGVN* igvn = phase->is_IterGVN(); 2626 trailing->remove(igvn); 2627 } 2628 } 2629 2630 return result; 2631 } 2632 2633 //------------------------------match_edge------------------------------------- 2634 // Do we Match on this edge index or not? Match only memory & value 2635 uint StoreNode::match_edge(uint idx) const { 2636 return idx == MemNode::Address || idx == MemNode::ValueIn; 2637 } 2638 2639 //------------------------------cmp-------------------------------------------- 2640 // Do not common stores up together. They generally have to be split 2641 // back up anyways, so do not bother. 2642 bool StoreNode::cmp( const Node &n ) const { 2643 return (&n == this); // Always fail except on self 2644 } 2645 2646 //------------------------------Ideal_masked_input----------------------------- 2647 // Check for a useless mask before a partial-word store 2648 // (StoreB ... (AndI valIn conIa) ) 2649 // If (conIa & mask == mask) this simplifies to 2650 // (StoreB ... (valIn) ) 2651 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2652 Node *val = in(MemNode::ValueIn); 2653 if( val->Opcode() == Op_AndI ) { 2654 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2655 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2656 set_req(MemNode::ValueIn, val->in(1)); 2657 return this; 2658 } 2659 } 2660 return NULL; 2661 } 2662 2663 2664 //------------------------------Ideal_sign_extended_input---------------------- 2665 // Check for useless sign-extension before a partial-word store 2666 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2667 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2668 // (StoreB ... (valIn) ) 2669 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2670 Node *val = in(MemNode::ValueIn); 2671 if( val->Opcode() == Op_RShiftI ) { 2672 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2673 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2674 Node *shl = val->in(1); 2675 if( shl->Opcode() == Op_LShiftI ) { 2676 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2677 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2678 set_req(MemNode::ValueIn, shl->in(1)); 2679 return this; 2680 } 2681 } 2682 } 2683 } 2684 return NULL; 2685 } 2686 2687 //------------------------------value_never_loaded----------------------------------- 2688 // Determine whether there are any possible loads of the value stored. 2689 // For simplicity, we actually check if there are any loads from the 2690 // address stored to, not just for loads of the value stored by this node. 2691 // 2692 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2693 Node *adr = in(Address); 2694 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2695 if (adr_oop == NULL) 2696 return false; 2697 if (!adr_oop->is_known_instance_field()) 2698 return false; // if not a distinct instance, there may be aliases of the address 2699 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2700 Node *use = adr->fast_out(i); 2701 if (use->is_Load() || use->is_LoadStore()) { 2702 return false; 2703 } 2704 } 2705 return true; 2706 } 2707 2708 MemBarNode* StoreNode::trailing_membar() const { 2709 if (is_release()) { 2710 MemBarNode* trailing_mb = NULL; 2711 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2712 Node* u = fast_out(i); 2713 if (u->is_MemBar()) { 2714 if (u->as_MemBar()->trailing_store()) { 2715 assert(u->Opcode() == Op_MemBarVolatile, ""); 2716 assert(trailing_mb == NULL, "only one"); 2717 trailing_mb = u->as_MemBar(); 2718 #ifdef ASSERT 2719 Node* leading = u->as_MemBar()->leading_membar(); 2720 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 2721 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair"); 2722 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair"); 2723 #endif 2724 } else { 2725 assert(u->as_MemBar()->standalone(), ""); 2726 } 2727 } 2728 } 2729 return trailing_mb; 2730 } 2731 return NULL; 2732 } 2733 2734 2735 //============================================================================= 2736 //------------------------------Ideal------------------------------------------ 2737 // If the store is from an AND mask that leaves the low bits untouched, then 2738 // we can skip the AND operation. If the store is from a sign-extension 2739 // (a left shift, then right shift) we can skip both. 2740 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2741 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2742 if( progress != NULL ) return progress; 2743 2744 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2745 if( progress != NULL ) return progress; 2746 2747 // Finally check the default case 2748 return StoreNode::Ideal(phase, can_reshape); 2749 } 2750 2751 //============================================================================= 2752 //------------------------------Ideal------------------------------------------ 2753 // If the store is from an AND mask that leaves the low bits untouched, then 2754 // we can skip the AND operation 2755 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2756 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2757 if( progress != NULL ) return progress; 2758 2759 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2760 if( progress != NULL ) return progress; 2761 2762 // Finally check the default case 2763 return StoreNode::Ideal(phase, can_reshape); 2764 } 2765 2766 //============================================================================= 2767 //------------------------------Identity--------------------------------------- 2768 Node* StoreCMNode::Identity(PhaseGVN* phase) { 2769 // No need to card mark when storing a null ptr 2770 Node* my_store = in(MemNode::OopStore); 2771 if (my_store->is_Store()) { 2772 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2773 if( t1 == TypePtr::NULL_PTR ) { 2774 return in(MemNode::Memory); 2775 } 2776 } 2777 return this; 2778 } 2779 2780 //============================================================================= 2781 //------------------------------Ideal--------------------------------------- 2782 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2783 Node* progress = StoreNode::Ideal(phase, can_reshape); 2784 if (progress != NULL) return progress; 2785 2786 Node* my_store = in(MemNode::OopStore); 2787 if (my_store->is_MergeMem()) { 2788 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2789 set_req(MemNode::OopStore, mem); 2790 return this; 2791 } 2792 2793 return NULL; 2794 } 2795 2796 //------------------------------Value----------------------------------------- 2797 const Type* StoreCMNode::Value(PhaseGVN* phase) const { 2798 // Either input is TOP ==> the result is TOP 2799 const Type *t = phase->type( in(MemNode::Memory) ); 2800 if( t == Type::TOP ) return Type::TOP; 2801 t = phase->type( in(MemNode::Address) ); 2802 if( t == Type::TOP ) return Type::TOP; 2803 t = phase->type( in(MemNode::ValueIn) ); 2804 if( t == Type::TOP ) return Type::TOP; 2805 // If extra input is TOP ==> the result is TOP 2806 t = phase->type( in(MemNode::OopStore) ); 2807 if( t == Type::TOP ) return Type::TOP; 2808 2809 return StoreNode::Value( phase ); 2810 } 2811 2812 2813 //============================================================================= 2814 //----------------------------------SCMemProjNode------------------------------ 2815 const Type* SCMemProjNode::Value(PhaseGVN* phase) const 2816 { 2817 return bottom_type(); 2818 } 2819 2820 //============================================================================= 2821 //----------------------------------LoadStoreNode------------------------------ 2822 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2823 : Node(required), 2824 _type(rt), 2825 _adr_type(at), 2826 _has_barrier(false) 2827 { 2828 init_req(MemNode::Control, c ); 2829 init_req(MemNode::Memory , mem); 2830 init_req(MemNode::Address, adr); 2831 init_req(MemNode::ValueIn, val); 2832 init_class_id(Class_LoadStore); 2833 } 2834 2835 uint LoadStoreNode::ideal_reg() const { 2836 return _type->ideal_reg(); 2837 } 2838 2839 bool LoadStoreNode::result_not_used() const { 2840 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2841 Node *x = fast_out(i); 2842 if (x->Opcode() == Op_SCMemProj) continue; 2843 return false; 2844 } 2845 return true; 2846 } 2847 2848 MemBarNode* LoadStoreNode::trailing_membar() const { 2849 MemBarNode* trailing = NULL; 2850 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2851 Node* u = fast_out(i); 2852 if (u->is_MemBar()) { 2853 if (u->as_MemBar()->trailing_load_store()) { 2854 assert(u->Opcode() == Op_MemBarAcquire, ""); 2855 assert(trailing == NULL, "only one"); 2856 trailing = u->as_MemBar(); 2857 #ifdef ASSERT 2858 Node* leading = trailing->leading_membar(); 2859 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 2860 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair"); 2861 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair"); 2862 #endif 2863 } else { 2864 assert(u->as_MemBar()->standalone(), "wrong barrier kind"); 2865 } 2866 } 2867 } 2868 2869 return trailing; 2870 } 2871 2872 uint LoadStoreNode::size_of() const { return sizeof(*this); } 2873 2874 //============================================================================= 2875 //----------------------------------LoadStoreConditionalNode-------------------- 2876 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 2877 init_req(ExpectedIn, ex ); 2878 } 2879 2880 //============================================================================= 2881 //-------------------------------adr_type-------------------------------------- 2882 const TypePtr* ClearArrayNode::adr_type() const { 2883 Node *adr = in(3); 2884 if (adr == NULL) return NULL; // node is dead 2885 return MemNode::calculate_adr_type(adr->bottom_type()); 2886 } 2887 2888 //------------------------------match_edge------------------------------------- 2889 // Do we Match on this edge index or not? Do not match memory 2890 uint ClearArrayNode::match_edge(uint idx) const { 2891 return idx > 1; 2892 } 2893 2894 //------------------------------Identity--------------------------------------- 2895 // Clearing a zero length array does nothing 2896 Node* ClearArrayNode::Identity(PhaseGVN* phase) { 2897 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2898 } 2899 2900 //------------------------------Idealize--------------------------------------- 2901 // Clearing a short array is faster with stores 2902 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2903 // Already know this is a large node, do not try to ideal it 2904 if (!IdealizeClearArrayNode || _is_large) return NULL; 2905 2906 const int unit = BytesPerLong; 2907 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2908 if (!t) return NULL; 2909 if (!t->is_con()) return NULL; 2910 intptr_t raw_count = t->get_con(); 2911 intptr_t size = raw_count; 2912 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2913 // Clearing nothing uses the Identity call. 2914 // Negative clears are possible on dead ClearArrays 2915 // (see jck test stmt114.stmt11402.val). 2916 if (size <= 0 || size % unit != 0) return NULL; 2917 intptr_t count = size / unit; 2918 // Length too long; communicate this to matchers and assemblers. 2919 // Assemblers are responsible to produce fast hardware clears for it. 2920 if (size > InitArrayShortSize) { 2921 return new ClearArrayNode(in(0), in(1), in(2), in(3), true); 2922 } 2923 Node *mem = in(1); 2924 if( phase->type(mem)==Type::TOP ) return NULL; 2925 Node *adr = in(3); 2926 const Type* at = phase->type(adr); 2927 if( at==Type::TOP ) return NULL; 2928 const TypePtr* atp = at->isa_ptr(); 2929 // adjust atp to be the correct array element address type 2930 if (atp == NULL) atp = TypePtr::BOTTOM; 2931 else atp = atp->add_offset(Type::OffsetBot); 2932 // Get base for derived pointer purposes 2933 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2934 Node *base = adr->in(1); 2935 2936 Node *zero = phase->makecon(TypeLong::ZERO); 2937 Node *off = phase->MakeConX(BytesPerLong); 2938 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2939 count--; 2940 while( count-- ) { 2941 mem = phase->transform(mem); 2942 adr = phase->transform(new AddPNode(base,adr,off)); 2943 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2944 } 2945 return mem; 2946 } 2947 2948 //----------------------------step_through---------------------------------- 2949 // Return allocation input memory edge if it is different instance 2950 // or itself if it is the one we are looking for. 2951 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2952 Node* n = *np; 2953 assert(n->is_ClearArray(), "sanity"); 2954 intptr_t offset; 2955 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2956 // This method is called only before Allocate nodes are expanded 2957 // during macro nodes expansion. Before that ClearArray nodes are 2958 // only generated in PhaseMacroExpand::generate_arraycopy() (before 2959 // Allocate nodes are expanded) which follows allocations. 2960 assert(alloc != NULL, "should have allocation"); 2961 if (alloc->_idx == instance_id) { 2962 // Can not bypass initialization of the instance we are looking for. 2963 return false; 2964 } 2965 // Otherwise skip it. 2966 InitializeNode* init = alloc->initialization(); 2967 if (init != NULL) 2968 *np = init->in(TypeFunc::Memory); 2969 else 2970 *np = alloc->in(TypeFunc::Memory); 2971 return true; 2972 } 2973 2974 //----------------------------clear_memory------------------------------------- 2975 // Generate code to initialize object storage to zero. 2976 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2977 intptr_t start_offset, 2978 Node* end_offset, 2979 PhaseGVN* phase) { 2980 intptr_t offset = start_offset; 2981 2982 int unit = BytesPerLong; 2983 if ((offset % unit) != 0) { 2984 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 2985 adr = phase->transform(adr); 2986 const TypePtr* atp = TypeRawPtr::BOTTOM; 2987 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2988 mem = phase->transform(mem); 2989 offset += BytesPerInt; 2990 } 2991 assert((offset % unit) == 0, ""); 2992 2993 // Initialize the remaining stuff, if any, with a ClearArray. 2994 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2995 } 2996 2997 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2998 Node* start_offset, 2999 Node* end_offset, 3000 PhaseGVN* phase) { 3001 if (start_offset == end_offset) { 3002 // nothing to do 3003 return mem; 3004 } 3005 3006 int unit = BytesPerLong; 3007 Node* zbase = start_offset; 3008 Node* zend = end_offset; 3009 3010 // Scale to the unit required by the CPU: 3011 if (!Matcher::init_array_count_is_in_bytes) { 3012 Node* shift = phase->intcon(exact_log2(unit)); 3013 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 3014 zend = phase->transform(new URShiftXNode(zend, shift) ); 3015 } 3016 3017 // Bulk clear double-words 3018 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 3019 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 3020 mem = new ClearArrayNode(ctl, mem, zsize, adr, false); 3021 return phase->transform(mem); 3022 } 3023 3024 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3025 intptr_t start_offset, 3026 intptr_t end_offset, 3027 PhaseGVN* phase) { 3028 if (start_offset == end_offset) { 3029 // nothing to do 3030 return mem; 3031 } 3032 3033 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 3034 intptr_t done_offset = end_offset; 3035 if ((done_offset % BytesPerLong) != 0) { 3036 done_offset -= BytesPerInt; 3037 } 3038 if (done_offset > start_offset) { 3039 mem = clear_memory(ctl, mem, dest, 3040 start_offset, phase->MakeConX(done_offset), phase); 3041 } 3042 if (done_offset < end_offset) { // emit the final 32-bit store 3043 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 3044 adr = phase->transform(adr); 3045 const TypePtr* atp = TypeRawPtr::BOTTOM; 3046 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 3047 mem = phase->transform(mem); 3048 done_offset += BytesPerInt; 3049 } 3050 assert(done_offset == end_offset, ""); 3051 return mem; 3052 } 3053 3054 //============================================================================= 3055 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 3056 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 3057 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone) 3058 #ifdef ASSERT 3059 , _pair_idx(0) 3060 #endif 3061 { 3062 init_class_id(Class_MemBar); 3063 Node* top = C->top(); 3064 init_req(TypeFunc::I_O,top); 3065 init_req(TypeFunc::FramePtr,top); 3066 init_req(TypeFunc::ReturnAdr,top); 3067 if (precedent != NULL) 3068 init_req(TypeFunc::Parms, precedent); 3069 } 3070 3071 //------------------------------cmp-------------------------------------------- 3072 uint MemBarNode::hash() const { return NO_HASH; } 3073 bool MemBarNode::cmp( const Node &n ) const { 3074 return (&n == this); // Always fail except on self 3075 } 3076 3077 //------------------------------make------------------------------------------- 3078 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 3079 switch (opcode) { 3080 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 3081 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 3082 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 3083 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 3084 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 3085 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 3086 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 3087 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 3088 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn); 3089 case Op_Initialize: return new InitializeNode(C, atp, pn); 3090 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 3091 default: ShouldNotReachHere(); return NULL; 3092 } 3093 } 3094 3095 void MemBarNode::remove(PhaseIterGVN *igvn) { 3096 if (outcnt() != 2) { 3097 return; 3098 } 3099 if (trailing_store() || trailing_load_store()) { 3100 MemBarNode* leading = leading_membar(); 3101 if (leading != NULL) { 3102 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars"); 3103 leading->remove(igvn); 3104 } 3105 } 3106 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 3107 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 3108 } 3109 3110 //------------------------------Ideal------------------------------------------ 3111 // Return a node which is more "ideal" than the current node. Strip out 3112 // control copies 3113 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3114 if (remove_dead_region(phase, can_reshape)) return this; 3115 // Don't bother trying to transform a dead node 3116 if (in(0) && in(0)->is_top()) { 3117 return NULL; 3118 } 3119 3120 bool progress = false; 3121 // Eliminate volatile MemBars for scalar replaced objects. 3122 if (can_reshape && req() == (Precedent+1)) { 3123 bool eliminate = false; 3124 int opc = Opcode(); 3125 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 3126 // Volatile field loads and stores. 3127 Node* my_mem = in(MemBarNode::Precedent); 3128 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 3129 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 3130 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 3131 // replace this Precedent (decodeN) with the Load instead. 3132 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 3133 Node* load_node = my_mem->in(1); 3134 set_req(MemBarNode::Precedent, load_node); 3135 phase->is_IterGVN()->_worklist.push(my_mem); 3136 my_mem = load_node; 3137 } else { 3138 assert(my_mem->unique_out() == this, "sanity"); 3139 del_req(Precedent); 3140 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 3141 my_mem = NULL; 3142 } 3143 progress = true; 3144 } 3145 if (my_mem != NULL && my_mem->is_Mem()) { 3146 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 3147 // Check for scalar replaced object reference. 3148 if( t_oop != NULL && t_oop->is_known_instance_field() && 3149 t_oop->offset() != Type::OffsetBot && 3150 t_oop->offset() != Type::OffsetTop) { 3151 eliminate = true; 3152 } 3153 } 3154 } else if (opc == Op_MemBarRelease) { 3155 // Final field stores. 3156 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 3157 if ((alloc != NULL) && alloc->is_Allocate() && 3158 alloc->as_Allocate()->does_not_escape_thread()) { 3159 // The allocated object does not escape. 3160 eliminate = true; 3161 } 3162 } 3163 if (eliminate) { 3164 // Replace MemBar projections by its inputs. 3165 PhaseIterGVN* igvn = phase->is_IterGVN(); 3166 remove(igvn); 3167 // Must return either the original node (now dead) or a new node 3168 // (Do not return a top here, since that would break the uniqueness of top.) 3169 return new ConINode(TypeInt::ZERO); 3170 } 3171 } 3172 return progress ? this : NULL; 3173 } 3174 3175 //------------------------------Value------------------------------------------ 3176 const Type* MemBarNode::Value(PhaseGVN* phase) const { 3177 if( !in(0) ) return Type::TOP; 3178 if( phase->type(in(0)) == Type::TOP ) 3179 return Type::TOP; 3180 return TypeTuple::MEMBAR; 3181 } 3182 3183 //------------------------------match------------------------------------------ 3184 // Construct projections for memory. 3185 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3186 switch (proj->_con) { 3187 case TypeFunc::Control: 3188 case TypeFunc::Memory: 3189 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3190 } 3191 ShouldNotReachHere(); 3192 return NULL; 3193 } 3194 3195 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3196 trailing->_kind = TrailingStore; 3197 leading->_kind = LeadingStore; 3198 #ifdef ASSERT 3199 trailing->_pair_idx = leading->_idx; 3200 leading->_pair_idx = leading->_idx; 3201 #endif 3202 } 3203 3204 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3205 trailing->_kind = TrailingLoadStore; 3206 leading->_kind = LeadingLoadStore; 3207 #ifdef ASSERT 3208 trailing->_pair_idx = leading->_idx; 3209 leading->_pair_idx = leading->_idx; 3210 #endif 3211 } 3212 3213 MemBarNode* MemBarNode::trailing_membar() const { 3214 ResourceMark rm; 3215 Node* trailing = (Node*)this; 3216 VectorSet seen(Thread::current()->resource_area()); 3217 Node_Stack multis(0); 3218 do { 3219 Node* c = trailing; 3220 uint i = 0; 3221 do { 3222 trailing = NULL; 3223 for (; i < c->outcnt(); i++) { 3224 Node* next = c->raw_out(i); 3225 if (next != c && next->is_CFG()) { 3226 if (c->is_MultiBranch()) { 3227 if (multis.node() == c) { 3228 multis.set_index(i+1); 3229 } else { 3230 multis.push(c, i+1); 3231 } 3232 } 3233 trailing = next; 3234 break; 3235 } 3236 } 3237 if (trailing != NULL && !seen.test_set(trailing->_idx)) { 3238 break; 3239 } 3240 while (multis.size() > 0) { 3241 c = multis.node(); 3242 i = multis.index(); 3243 if (i < c->req()) { 3244 break; 3245 } 3246 multis.pop(); 3247 } 3248 } while (multis.size() > 0); 3249 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing()); 3250 3251 MemBarNode* mb = trailing->as_MemBar(); 3252 assert((mb->_kind == TrailingStore && _kind == LeadingStore) || 3253 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar"); 3254 assert(mb->_pair_idx == _pair_idx, "bad trailing membar"); 3255 return mb; 3256 } 3257 3258 MemBarNode* MemBarNode::leading_membar() const { 3259 ResourceMark rm; 3260 VectorSet seen(Thread::current()->resource_area()); 3261 Node_Stack regions(0); 3262 Node* leading = in(0); 3263 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) { 3264 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) { 3265 leading = NULL; 3266 while (regions.size() > 0 && leading == NULL) { 3267 Node* r = regions.node(); 3268 uint i = regions.index(); 3269 if (i < r->req()) { 3270 leading = r->in(i); 3271 regions.set_index(i+1); 3272 } else { 3273 regions.pop(); 3274 } 3275 } 3276 if (leading == NULL) { 3277 assert(regions.size() == 0, "all paths should have been tried"); 3278 return NULL; 3279 } 3280 } 3281 if (leading->is_Region()) { 3282 regions.push(leading, 2); 3283 leading = leading->in(1); 3284 } else { 3285 leading = leading->in(0); 3286 } 3287 } 3288 #ifdef ASSERT 3289 Unique_Node_List wq; 3290 wq.push((Node*)this); 3291 uint found = 0; 3292 for (uint i = 0; i < wq.size(); i++) { 3293 Node* n = wq.at(i); 3294 if (n->is_Region()) { 3295 for (uint j = 1; j < n->req(); j++) { 3296 Node* in = n->in(j); 3297 if (in != NULL && !in->is_top()) { 3298 wq.push(in); 3299 } 3300 } 3301 } else { 3302 if (n->is_MemBar() && n->as_MemBar()->leading()) { 3303 assert(n == leading, "consistency check failed"); 3304 found++; 3305 } else { 3306 Node* in = n->in(0); 3307 if (in != NULL && !in->is_top()) { 3308 wq.push(in); 3309 } 3310 } 3311 } 3312 } 3313 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed"); 3314 #endif 3315 if (leading == NULL) { 3316 return NULL; 3317 } 3318 MemBarNode* mb = leading->as_MemBar(); 3319 assert((mb->_kind == LeadingStore && _kind == TrailingStore) || 3320 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar"); 3321 assert(mb->_pair_idx == _pair_idx, "bad leading membar"); 3322 return mb; 3323 } 3324 3325 //===========================InitializeNode==================================== 3326 // SUMMARY: 3327 // This node acts as a memory barrier on raw memory, after some raw stores. 3328 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 3329 // The Initialize can 'capture' suitably constrained stores as raw inits. 3330 // It can coalesce related raw stores into larger units (called 'tiles'). 3331 // It can avoid zeroing new storage for memory units which have raw inits. 3332 // At macro-expansion, it is marked 'complete', and does not optimize further. 3333 // 3334 // EXAMPLE: 3335 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3336 // ctl = incoming control; mem* = incoming memory 3337 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 3338 // First allocate uninitialized memory and fill in the header: 3339 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 3340 // ctl := alloc.Control; mem* := alloc.Memory* 3341 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 3342 // Then initialize to zero the non-header parts of the raw memory block: 3343 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3344 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3345 // After the initialize node executes, the object is ready for service: 3346 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3347 // Suppose its body is immediately initialized as {1,2}: 3348 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3349 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3350 // mem.SLICE(#short[*]) := store2 3351 // 3352 // DETAILS: 3353 // An InitializeNode collects and isolates object initialization after 3354 // an AllocateNode and before the next possible safepoint. As a 3355 // memory barrier (MemBarNode), it keeps critical stores from drifting 3356 // down past any safepoint or any publication of the allocation. 3357 // Before this barrier, a newly-allocated object may have uninitialized bits. 3358 // After this barrier, it may be treated as a real oop, and GC is allowed. 3359 // 3360 // The semantics of the InitializeNode include an implicit zeroing of 3361 // the new object from object header to the end of the object. 3362 // (The object header and end are determined by the AllocateNode.) 3363 // 3364 // Certain stores may be added as direct inputs to the InitializeNode. 3365 // These stores must update raw memory, and they must be to addresses 3366 // derived from the raw address produced by AllocateNode, and with 3367 // a constant offset. They must be ordered by increasing offset. 3368 // The first one is at in(RawStores), the last at in(req()-1). 3369 // Unlike most memory operations, they are not linked in a chain, 3370 // but are displayed in parallel as users of the rawmem output of 3371 // the allocation. 3372 // 3373 // (See comments in InitializeNode::capture_store, which continue 3374 // the example given above.) 3375 // 3376 // When the associated Allocate is macro-expanded, the InitializeNode 3377 // may be rewritten to optimize collected stores. A ClearArrayNode 3378 // may also be created at that point to represent any required zeroing. 3379 // The InitializeNode is then marked 'complete', prohibiting further 3380 // capturing of nearby memory operations. 3381 // 3382 // During macro-expansion, all captured initializations which store 3383 // constant values of 32 bits or smaller are coalesced (if advantageous) 3384 // into larger 'tiles' 32 or 64 bits. This allows an object to be 3385 // initialized in fewer memory operations. Memory words which are 3386 // covered by neither tiles nor non-constant stores are pre-zeroed 3387 // by explicit stores of zero. (The code shape happens to do all 3388 // zeroing first, then all other stores, with both sequences occurring 3389 // in order of ascending offsets.) 3390 // 3391 // Alternatively, code may be inserted between an AllocateNode and its 3392 // InitializeNode, to perform arbitrary initialization of the new object. 3393 // E.g., the object copying intrinsics insert complex data transfers here. 3394 // The initialization must then be marked as 'complete' disable the 3395 // built-in zeroing semantics and the collection of initializing stores. 3396 // 3397 // While an InitializeNode is incomplete, reads from the memory state 3398 // produced by it are optimizable if they match the control edge and 3399 // new oop address associated with the allocation/initialization. 3400 // They return a stored value (if the offset matches) or else zero. 3401 // A write to the memory state, if it matches control and address, 3402 // and if it is to a constant offset, may be 'captured' by the 3403 // InitializeNode. It is cloned as a raw memory operation and rewired 3404 // inside the initialization, to the raw oop produced by the allocation. 3405 // Operations on addresses which are provably distinct (e.g., to 3406 // other AllocateNodes) are allowed to bypass the initialization. 3407 // 3408 // The effect of all this is to consolidate object initialization 3409 // (both arrays and non-arrays, both piecewise and bulk) into a 3410 // single location, where it can be optimized as a unit. 3411 // 3412 // Only stores with an offset less than TrackedInitializationLimit words 3413 // will be considered for capture by an InitializeNode. This puts a 3414 // reasonable limit on the complexity of optimized initializations. 3415 3416 //---------------------------InitializeNode------------------------------------ 3417 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3418 : MemBarNode(C, adr_type, rawoop), 3419 _is_complete(Incomplete), _does_not_escape(false) 3420 { 3421 init_class_id(Class_Initialize); 3422 3423 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3424 assert(in(RawAddress) == rawoop, "proper init"); 3425 // Note: allocation() can be NULL, for secondary initialization barriers 3426 } 3427 3428 // Since this node is not matched, it will be processed by the 3429 // register allocator. Declare that there are no constraints 3430 // on the allocation of the RawAddress edge. 3431 const RegMask &InitializeNode::in_RegMask(uint idx) const { 3432 // This edge should be set to top, by the set_complete. But be conservative. 3433 if (idx == InitializeNode::RawAddress) 3434 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3435 return RegMask::Empty; 3436 } 3437 3438 Node* InitializeNode::memory(uint alias_idx) { 3439 Node* mem = in(Memory); 3440 if (mem->is_MergeMem()) { 3441 return mem->as_MergeMem()->memory_at(alias_idx); 3442 } else { 3443 // incoming raw memory is not split 3444 return mem; 3445 } 3446 } 3447 3448 bool InitializeNode::is_non_zero() { 3449 if (is_complete()) return false; 3450 remove_extra_zeroes(); 3451 return (req() > RawStores); 3452 } 3453 3454 void InitializeNode::set_complete(PhaseGVN* phase) { 3455 assert(!is_complete(), "caller responsibility"); 3456 _is_complete = Complete; 3457 3458 // After this node is complete, it contains a bunch of 3459 // raw-memory initializations. There is no need for 3460 // it to have anything to do with non-raw memory effects. 3461 // Therefore, tell all non-raw users to re-optimize themselves, 3462 // after skipping the memory effects of this initialization. 3463 PhaseIterGVN* igvn = phase->is_IterGVN(); 3464 if (igvn) igvn->add_users_to_worklist(this); 3465 } 3466 3467 // convenience function 3468 // return false if the init contains any stores already 3469 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3470 InitializeNode* init = initialization(); 3471 if (init == NULL || init->is_complete()) return false; 3472 init->remove_extra_zeroes(); 3473 // for now, if this allocation has already collected any inits, bail: 3474 if (init->is_non_zero()) return false; 3475 init->set_complete(phase); 3476 return true; 3477 } 3478 3479 void InitializeNode::remove_extra_zeroes() { 3480 if (req() == RawStores) return; 3481 Node* zmem = zero_memory(); 3482 uint fill = RawStores; 3483 for (uint i = fill; i < req(); i++) { 3484 Node* n = in(i); 3485 if (n->is_top() || n == zmem) continue; // skip 3486 if (fill < i) set_req(fill, n); // compact 3487 ++fill; 3488 } 3489 // delete any empty spaces created: 3490 while (fill < req()) { 3491 del_req(fill); 3492 } 3493 } 3494 3495 // Helper for remembering which stores go with which offsets. 3496 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3497 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3498 intptr_t offset = -1; 3499 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3500 phase, offset); 3501 if (base == NULL) return -1; // something is dead, 3502 if (offset < 0) return -1; // dead, dead 3503 return offset; 3504 } 3505 3506 // Helper for proving that an initialization expression is 3507 // "simple enough" to be folded into an object initialization. 3508 // Attempts to prove that a store's initial value 'n' can be captured 3509 // within the initialization without creating a vicious cycle, such as: 3510 // { Foo p = new Foo(); p.next = p; } 3511 // True for constants and parameters and small combinations thereof. 3512 bool InitializeNode::detect_init_independence(Node* n, int& count) { 3513 if (n == NULL) return true; // (can this really happen?) 3514 if (n->is_Proj()) n = n->in(0); 3515 if (n == this) return false; // found a cycle 3516 if (n->is_Con()) return true; 3517 if (n->is_Start()) return true; // params, etc., are OK 3518 if (n->is_Root()) return true; // even better 3519 3520 Node* ctl = n->in(0); 3521 if (ctl != NULL && !ctl->is_top()) { 3522 if (ctl->is_Proj()) ctl = ctl->in(0); 3523 if (ctl == this) return false; 3524 3525 // If we already know that the enclosing memory op is pinned right after 3526 // the init, then any control flow that the store has picked up 3527 // must have preceded the init, or else be equal to the init. 3528 // Even after loop optimizations (which might change control edges) 3529 // a store is never pinned *before* the availability of its inputs. 3530 if (!MemNode::all_controls_dominate(n, this)) 3531 return false; // failed to prove a good control 3532 } 3533 3534 // Check data edges for possible dependencies on 'this'. 3535 if ((count += 1) > 20) return false; // complexity limit 3536 for (uint i = 1; i < n->req(); i++) { 3537 Node* m = n->in(i); 3538 if (m == NULL || m == n || m->is_top()) continue; 3539 uint first_i = n->find_edge(m); 3540 if (i != first_i) continue; // process duplicate edge just once 3541 if (!detect_init_independence(m, count)) { 3542 return false; 3543 } 3544 } 3545 3546 return true; 3547 } 3548 3549 // Here are all the checks a Store must pass before it can be moved into 3550 // an initialization. Returns zero if a check fails. 3551 // On success, returns the (constant) offset to which the store applies, 3552 // within the initialized memory. 3553 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) { 3554 const int FAIL = 0; 3555 if (st->req() != MemNode::ValueIn + 1) 3556 return FAIL; // an inscrutable StoreNode (card mark?) 3557 Node* ctl = st->in(MemNode::Control); 3558 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3559 return FAIL; // must be unconditional after the initialization 3560 Node* mem = st->in(MemNode::Memory); 3561 if (!(mem->is_Proj() && mem->in(0) == this)) 3562 return FAIL; // must not be preceded by other stores 3563 Node* adr = st->in(MemNode::Address); 3564 intptr_t offset; 3565 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3566 if (alloc == NULL) 3567 return FAIL; // inscrutable address 3568 if (alloc != allocation()) 3569 return FAIL; // wrong allocation! (store needs to float up) 3570 int size_in_bytes = st->memory_size(); 3571 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) { 3572 return FAIL; // mismatched access 3573 } 3574 Node* val = st->in(MemNode::ValueIn); 3575 int complexity_count = 0; 3576 if (!detect_init_independence(val, complexity_count)) 3577 return FAIL; // stored value must be 'simple enough' 3578 3579 // The Store can be captured only if nothing after the allocation 3580 // and before the Store is using the memory location that the store 3581 // overwrites. 3582 bool failed = false; 3583 // If is_complete_with_arraycopy() is true the shape of the graph is 3584 // well defined and is safe so no need for extra checks. 3585 if (!is_complete_with_arraycopy()) { 3586 // We are going to look at each use of the memory state following 3587 // the allocation to make sure nothing reads the memory that the 3588 // Store writes. 3589 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3590 int alias_idx = phase->C->get_alias_index(t_adr); 3591 ResourceMark rm; 3592 Unique_Node_List mems; 3593 mems.push(mem); 3594 Node* unique_merge = NULL; 3595 for (uint next = 0; next < mems.size(); ++next) { 3596 Node *m = mems.at(next); 3597 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3598 Node *n = m->fast_out(j); 3599 if (n->outcnt() == 0) { 3600 continue; 3601 } 3602 if (n == st) { 3603 continue; 3604 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3605 // If the control of this use is different from the control 3606 // of the Store which is right after the InitializeNode then 3607 // this node cannot be between the InitializeNode and the 3608 // Store. 3609 continue; 3610 } else if (n->is_MergeMem()) { 3611 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3612 // We can hit a MergeMemNode (that will likely go away 3613 // later) that is a direct use of the memory state 3614 // following the InitializeNode on the same slice as the 3615 // store node that we'd like to capture. We need to check 3616 // the uses of the MergeMemNode. 3617 mems.push(n); 3618 } 3619 } else if (n->is_Mem()) { 3620 Node* other_adr = n->in(MemNode::Address); 3621 if (other_adr == adr) { 3622 failed = true; 3623 break; 3624 } else { 3625 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3626 if (other_t_adr != NULL) { 3627 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3628 if (other_alias_idx == alias_idx) { 3629 // A load from the same memory slice as the store right 3630 // after the InitializeNode. We check the control of the 3631 // object/array that is loaded from. If it's the same as 3632 // the store control then we cannot capture the store. 3633 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3634 Node* base = other_adr; 3635 assert(base->is_AddP(), "should be addp but is %s", base->Name()); 3636 base = base->in(AddPNode::Base); 3637 if (base != NULL) { 3638 base = base->uncast(); 3639 if (base->is_Proj() && base->in(0) == alloc) { 3640 failed = true; 3641 break; 3642 } 3643 } 3644 } 3645 } 3646 } 3647 } else { 3648 failed = true; 3649 break; 3650 } 3651 } 3652 } 3653 } 3654 if (failed) { 3655 if (!can_reshape) { 3656 // We decided we couldn't capture the store during parsing. We 3657 // should try again during the next IGVN once the graph is 3658 // cleaner. 3659 phase->C->record_for_igvn(st); 3660 } 3661 return FAIL; 3662 } 3663 3664 return offset; // success 3665 } 3666 3667 // Find the captured store in(i) which corresponds to the range 3668 // [start..start+size) in the initialized object. 3669 // If there is one, return its index i. If there isn't, return the 3670 // negative of the index where it should be inserted. 3671 // Return 0 if the queried range overlaps an initialization boundary 3672 // or if dead code is encountered. 3673 // If size_in_bytes is zero, do not bother with overlap checks. 3674 int InitializeNode::captured_store_insertion_point(intptr_t start, 3675 int size_in_bytes, 3676 PhaseTransform* phase) { 3677 const int FAIL = 0, MAX_STORE = BytesPerLong; 3678 3679 if (is_complete()) 3680 return FAIL; // arraycopy got here first; punt 3681 3682 assert(allocation() != NULL, "must be present"); 3683 3684 // no negatives, no header fields: 3685 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3686 3687 // after a certain size, we bail out on tracking all the stores: 3688 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3689 if (start >= ti_limit) return FAIL; 3690 3691 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3692 if (i >= limit) return -(int)i; // not found; here is where to put it 3693 3694 Node* st = in(i); 3695 intptr_t st_off = get_store_offset(st, phase); 3696 if (st_off < 0) { 3697 if (st != zero_memory()) { 3698 return FAIL; // bail out if there is dead garbage 3699 } 3700 } else if (st_off > start) { 3701 // ...we are done, since stores are ordered 3702 if (st_off < start + size_in_bytes) { 3703 return FAIL; // the next store overlaps 3704 } 3705 return -(int)i; // not found; here is where to put it 3706 } else if (st_off < start) { 3707 if (size_in_bytes != 0 && 3708 start < st_off + MAX_STORE && 3709 start < st_off + st->as_Store()->memory_size()) { 3710 return FAIL; // the previous store overlaps 3711 } 3712 } else { 3713 if (size_in_bytes != 0 && 3714 st->as_Store()->memory_size() != size_in_bytes) { 3715 return FAIL; // mismatched store size 3716 } 3717 return i; 3718 } 3719 3720 ++i; 3721 } 3722 } 3723 3724 // Look for a captured store which initializes at the offset 'start' 3725 // with the given size. If there is no such store, and no other 3726 // initialization interferes, then return zero_memory (the memory 3727 // projection of the AllocateNode). 3728 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3729 PhaseTransform* phase) { 3730 assert(stores_are_sane(phase), ""); 3731 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3732 if (i == 0) { 3733 return NULL; // something is dead 3734 } else if (i < 0) { 3735 return zero_memory(); // just primordial zero bits here 3736 } else { 3737 Node* st = in(i); // here is the store at this position 3738 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3739 return st; 3740 } 3741 } 3742 3743 // Create, as a raw pointer, an address within my new object at 'offset'. 3744 Node* InitializeNode::make_raw_address(intptr_t offset, 3745 PhaseTransform* phase) { 3746 Node* addr = in(RawAddress); 3747 if (offset != 0) { 3748 Compile* C = phase->C; 3749 addr = phase->transform( new AddPNode(C->top(), addr, 3750 phase->MakeConX(offset)) ); 3751 } 3752 return addr; 3753 } 3754 3755 // Clone the given store, converting it into a raw store 3756 // initializing a field or element of my new object. 3757 // Caller is responsible for retiring the original store, 3758 // with subsume_node or the like. 3759 // 3760 // From the example above InitializeNode::InitializeNode, 3761 // here are the old stores to be captured: 3762 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3763 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3764 // 3765 // Here is the changed code; note the extra edges on init: 3766 // alloc = (Allocate ...) 3767 // rawoop = alloc.RawAddress 3768 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3769 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3770 // init = (Initialize alloc.Control alloc.Memory rawoop 3771 // rawstore1 rawstore2) 3772 // 3773 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3774 PhaseTransform* phase, bool can_reshape) { 3775 assert(stores_are_sane(phase), ""); 3776 3777 if (start < 0) return NULL; 3778 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3779 3780 Compile* C = phase->C; 3781 int size_in_bytes = st->memory_size(); 3782 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3783 if (i == 0) return NULL; // bail out 3784 Node* prev_mem = NULL; // raw memory for the captured store 3785 if (i > 0) { 3786 prev_mem = in(i); // there is a pre-existing store under this one 3787 set_req(i, C->top()); // temporarily disconnect it 3788 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3789 } else { 3790 i = -i; // no pre-existing store 3791 prev_mem = zero_memory(); // a slice of the newly allocated object 3792 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3793 set_req(--i, C->top()); // reuse this edge; it has been folded away 3794 else 3795 ins_req(i, C->top()); // build a new edge 3796 } 3797 Node* new_st = st->clone(); 3798 new_st->set_req(MemNode::Control, in(Control)); 3799 new_st->set_req(MemNode::Memory, prev_mem); 3800 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3801 new_st = phase->transform(new_st); 3802 3803 // At this point, new_st might have swallowed a pre-existing store 3804 // at the same offset, or perhaps new_st might have disappeared, 3805 // if it redundantly stored the same value (or zero to fresh memory). 3806 3807 // In any case, wire it in: 3808 phase->igvn_rehash_node_delayed(this); 3809 set_req(i, new_st); 3810 3811 // The caller may now kill the old guy. 3812 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3813 assert(check_st == new_st || check_st == NULL, "must be findable"); 3814 assert(!is_complete(), ""); 3815 return new_st; 3816 } 3817 3818 static bool store_constant(jlong* tiles, int num_tiles, 3819 intptr_t st_off, int st_size, 3820 jlong con) { 3821 if ((st_off & (st_size-1)) != 0) 3822 return false; // strange store offset (assume size==2**N) 3823 address addr = (address)tiles + st_off; 3824 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3825 switch (st_size) { 3826 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3827 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3828 case sizeof(jint): *(jint*) addr = (jint) con; break; 3829 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3830 default: return false; // strange store size (detect size!=2**N here) 3831 } 3832 return true; // return success to caller 3833 } 3834 3835 // Coalesce subword constants into int constants and possibly 3836 // into long constants. The goal, if the CPU permits, 3837 // is to initialize the object with a small number of 64-bit tiles. 3838 // Also, convert floating-point constants to bit patterns. 3839 // Non-constants are not relevant to this pass. 3840 // 3841 // In terms of the running example on InitializeNode::InitializeNode 3842 // and InitializeNode::capture_store, here is the transformation 3843 // of rawstore1 and rawstore2 into rawstore12: 3844 // alloc = (Allocate ...) 3845 // rawoop = alloc.RawAddress 3846 // tile12 = 0x00010002 3847 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3848 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3849 // 3850 void 3851 InitializeNode::coalesce_subword_stores(intptr_t header_size, 3852 Node* size_in_bytes, 3853 PhaseGVN* phase) { 3854 Compile* C = phase->C; 3855 3856 assert(stores_are_sane(phase), ""); 3857 // Note: After this pass, they are not completely sane, 3858 // since there may be some overlaps. 3859 3860 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3861 3862 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3863 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3864 size_limit = MIN2(size_limit, ti_limit); 3865 size_limit = align_up(size_limit, BytesPerLong); 3866 int num_tiles = size_limit / BytesPerLong; 3867 3868 // allocate space for the tile map: 3869 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3870 jlong tiles_buf[small_len]; 3871 Node* nodes_buf[small_len]; 3872 jlong inits_buf[small_len]; 3873 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3874 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3875 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3876 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3877 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3878 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3879 // tiles: exact bitwise model of all primitive constants 3880 // nodes: last constant-storing node subsumed into the tiles model 3881 // inits: which bytes (in each tile) are touched by any initializations 3882 3883 //// Pass A: Fill in the tile model with any relevant stores. 3884 3885 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3886 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3887 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3888 Node* zmem = zero_memory(); // initially zero memory state 3889 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3890 Node* st = in(i); 3891 intptr_t st_off = get_store_offset(st, phase); 3892 3893 // Figure out the store's offset and constant value: 3894 if (st_off < header_size) continue; //skip (ignore header) 3895 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3896 int st_size = st->as_Store()->memory_size(); 3897 if (st_off + st_size > size_limit) break; 3898 3899 // Record which bytes are touched, whether by constant or not. 3900 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3901 continue; // skip (strange store size) 3902 3903 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3904 if (!val->singleton()) continue; //skip (non-con store) 3905 BasicType type = val->basic_type(); 3906 3907 jlong con = 0; 3908 switch (type) { 3909 case T_INT: con = val->is_int()->get_con(); break; 3910 case T_LONG: con = val->is_long()->get_con(); break; 3911 case T_FLOAT: con = jint_cast(val->getf()); break; 3912 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3913 default: continue; //skip (odd store type) 3914 } 3915 3916 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3917 st->Opcode() == Op_StoreL) { 3918 continue; // This StoreL is already optimal. 3919 } 3920 3921 // Store down the constant. 3922 store_constant(tiles, num_tiles, st_off, st_size, con); 3923 3924 intptr_t j = st_off >> LogBytesPerLong; 3925 3926 if (type == T_INT && st_size == BytesPerInt 3927 && (st_off & BytesPerInt) == BytesPerInt) { 3928 jlong lcon = tiles[j]; 3929 if (!Matcher::isSimpleConstant64(lcon) && 3930 st->Opcode() == Op_StoreI) { 3931 // This StoreI is already optimal by itself. 3932 jint* intcon = (jint*) &tiles[j]; 3933 intcon[1] = 0; // undo the store_constant() 3934 3935 // If the previous store is also optimal by itself, back up and 3936 // undo the action of the previous loop iteration... if we can. 3937 // But if we can't, just let the previous half take care of itself. 3938 st = nodes[j]; 3939 st_off -= BytesPerInt; 3940 con = intcon[0]; 3941 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3942 assert(st_off >= header_size, "still ignoring header"); 3943 assert(get_store_offset(st, phase) == st_off, "must be"); 3944 assert(in(i-1) == zmem, "must be"); 3945 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3946 assert(con == tcon->is_int()->get_con(), "must be"); 3947 // Undo the effects of the previous loop trip, which swallowed st: 3948 intcon[0] = 0; // undo store_constant() 3949 set_req(i-1, st); // undo set_req(i, zmem) 3950 nodes[j] = NULL; // undo nodes[j] = st 3951 --old_subword; // undo ++old_subword 3952 } 3953 continue; // This StoreI is already optimal. 3954 } 3955 } 3956 3957 // This store is not needed. 3958 set_req(i, zmem); 3959 nodes[j] = st; // record for the moment 3960 if (st_size < BytesPerLong) // something has changed 3961 ++old_subword; // includes int/float, but who's counting... 3962 else ++old_long; 3963 } 3964 3965 if ((old_subword + old_long) == 0) 3966 return; // nothing more to do 3967 3968 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3969 // Be sure to insert them before overlapping non-constant stores. 3970 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3971 for (int j = 0; j < num_tiles; j++) { 3972 jlong con = tiles[j]; 3973 jlong init = inits[j]; 3974 if (con == 0) continue; 3975 jint con0, con1; // split the constant, address-wise 3976 jint init0, init1; // split the init map, address-wise 3977 { union { jlong con; jint intcon[2]; } u; 3978 u.con = con; 3979 con0 = u.intcon[0]; 3980 con1 = u.intcon[1]; 3981 u.con = init; 3982 init0 = u.intcon[0]; 3983 init1 = u.intcon[1]; 3984 } 3985 3986 Node* old = nodes[j]; 3987 assert(old != NULL, "need the prior store"); 3988 intptr_t offset = (j * BytesPerLong); 3989 3990 bool split = !Matcher::isSimpleConstant64(con); 3991 3992 if (offset < header_size) { 3993 assert(offset + BytesPerInt >= header_size, "second int counts"); 3994 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3995 split = true; // only the second word counts 3996 // Example: int a[] = { 42 ... } 3997 } else if (con0 == 0 && init0 == -1) { 3998 split = true; // first word is covered by full inits 3999 // Example: int a[] = { ... foo(), 42 ... } 4000 } else if (con1 == 0 && init1 == -1) { 4001 split = true; // second word is covered by full inits 4002 // Example: int a[] = { ... 42, foo() ... } 4003 } 4004 4005 // Here's a case where init0 is neither 0 nor -1: 4006 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 4007 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 4008 // In this case the tile is not split; it is (jlong)42. 4009 // The big tile is stored down, and then the foo() value is inserted. 4010 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 4011 4012 Node* ctl = old->in(MemNode::Control); 4013 Node* adr = make_raw_address(offset, phase); 4014 const TypePtr* atp = TypeRawPtr::BOTTOM; 4015 4016 // One or two coalesced stores to plop down. 4017 Node* st[2]; 4018 intptr_t off[2]; 4019 int nst = 0; 4020 if (!split) { 4021 ++new_long; 4022 off[nst] = offset; 4023 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4024 phase->longcon(con), T_LONG, MemNode::unordered); 4025 } else { 4026 // Omit either if it is a zero. 4027 if (con0 != 0) { 4028 ++new_int; 4029 off[nst] = offset; 4030 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4031 phase->intcon(con0), T_INT, MemNode::unordered); 4032 } 4033 if (con1 != 0) { 4034 ++new_int; 4035 offset += BytesPerInt; 4036 adr = make_raw_address(offset, phase); 4037 off[nst] = offset; 4038 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4039 phase->intcon(con1), T_INT, MemNode::unordered); 4040 } 4041 } 4042 4043 // Insert second store first, then the first before the second. 4044 // Insert each one just before any overlapping non-constant stores. 4045 while (nst > 0) { 4046 Node* st1 = st[--nst]; 4047 C->copy_node_notes_to(st1, old); 4048 st1 = phase->transform(st1); 4049 offset = off[nst]; 4050 assert(offset >= header_size, "do not smash header"); 4051 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 4052 guarantee(ins_idx != 0, "must re-insert constant store"); 4053 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 4054 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 4055 set_req(--ins_idx, st1); 4056 else 4057 ins_req(ins_idx, st1); 4058 } 4059 } 4060 4061 if (PrintCompilation && WizardMode) 4062 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 4063 old_subword, old_long, new_int, new_long); 4064 if (C->log() != NULL) 4065 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 4066 old_subword, old_long, new_int, new_long); 4067 4068 // Clean up any remaining occurrences of zmem: 4069 remove_extra_zeroes(); 4070 } 4071 4072 // Explore forward from in(start) to find the first fully initialized 4073 // word, and return its offset. Skip groups of subword stores which 4074 // together initialize full words. If in(start) is itself part of a 4075 // fully initialized word, return the offset of in(start). If there 4076 // are no following full-word stores, or if something is fishy, return 4077 // a negative value. 4078 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 4079 int int_map = 0; 4080 intptr_t int_map_off = 0; 4081 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 4082 4083 for (uint i = start, limit = req(); i < limit; i++) { 4084 Node* st = in(i); 4085 4086 intptr_t st_off = get_store_offset(st, phase); 4087 if (st_off < 0) break; // return conservative answer 4088 4089 int st_size = st->as_Store()->memory_size(); 4090 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 4091 return st_off; // we found a complete word init 4092 } 4093 4094 // update the map: 4095 4096 intptr_t this_int_off = align_down(st_off, BytesPerInt); 4097 if (this_int_off != int_map_off) { 4098 // reset the map: 4099 int_map = 0; 4100 int_map_off = this_int_off; 4101 } 4102 4103 int subword_off = st_off - this_int_off; 4104 int_map |= right_n_bits(st_size) << subword_off; 4105 if ((int_map & FULL_MAP) == FULL_MAP) { 4106 return this_int_off; // we found a complete word init 4107 } 4108 4109 // Did this store hit or cross the word boundary? 4110 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt); 4111 if (next_int_off == this_int_off + BytesPerInt) { 4112 // We passed the current int, without fully initializing it. 4113 int_map_off = next_int_off; 4114 int_map >>= BytesPerInt; 4115 } else if (next_int_off > this_int_off + BytesPerInt) { 4116 // We passed the current and next int. 4117 return this_int_off + BytesPerInt; 4118 } 4119 } 4120 4121 return -1; 4122 } 4123 4124 4125 // Called when the associated AllocateNode is expanded into CFG. 4126 // At this point, we may perform additional optimizations. 4127 // Linearize the stores by ascending offset, to make memory 4128 // activity as coherent as possible. 4129 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 4130 intptr_t header_size, 4131 Node* size_in_bytes, 4132 PhaseGVN* phase) { 4133 assert(!is_complete(), "not already complete"); 4134 assert(stores_are_sane(phase), ""); 4135 assert(allocation() != NULL, "must be present"); 4136 4137 remove_extra_zeroes(); 4138 4139 if (ReduceFieldZeroing || ReduceBulkZeroing) 4140 // reduce instruction count for common initialization patterns 4141 coalesce_subword_stores(header_size, size_in_bytes, phase); 4142 4143 Node* zmem = zero_memory(); // initially zero memory state 4144 Node* inits = zmem; // accumulating a linearized chain of inits 4145 #ifdef ASSERT 4146 intptr_t first_offset = allocation()->minimum_header_size(); 4147 intptr_t last_init_off = first_offset; // previous init offset 4148 intptr_t last_init_end = first_offset; // previous init offset+size 4149 intptr_t last_tile_end = first_offset; // previous tile offset+size 4150 #endif 4151 intptr_t zeroes_done = header_size; 4152 4153 bool do_zeroing = true; // we might give up if inits are very sparse 4154 int big_init_gaps = 0; // how many large gaps have we seen? 4155 4156 if (UseTLAB && ZeroTLAB) do_zeroing = false; 4157 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 4158 4159 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 4160 Node* st = in(i); 4161 intptr_t st_off = get_store_offset(st, phase); 4162 if (st_off < 0) 4163 break; // unknown junk in the inits 4164 if (st->in(MemNode::Memory) != zmem) 4165 break; // complicated store chains somehow in list 4166 4167 int st_size = st->as_Store()->memory_size(); 4168 intptr_t next_init_off = st_off + st_size; 4169 4170 if (do_zeroing && zeroes_done < next_init_off) { 4171 // See if this store needs a zero before it or under it. 4172 intptr_t zeroes_needed = st_off; 4173 4174 if (st_size < BytesPerInt) { 4175 // Look for subword stores which only partially initialize words. 4176 // If we find some, we must lay down some word-level zeroes first, 4177 // underneath the subword stores. 4178 // 4179 // Examples: 4180 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 4181 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 4182 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 4183 // 4184 // Note: coalesce_subword_stores may have already done this, 4185 // if it was prompted by constant non-zero subword initializers. 4186 // But this case can still arise with non-constant stores. 4187 4188 intptr_t next_full_store = find_next_fullword_store(i, phase); 4189 4190 // In the examples above: 4191 // in(i) p q r s x y z 4192 // st_off 12 13 14 15 12 13 14 4193 // st_size 1 1 1 1 1 1 1 4194 // next_full_s. 12 16 16 16 16 16 16 4195 // z's_done 12 16 16 16 12 16 12 4196 // z's_needed 12 16 16 16 16 16 16 4197 // zsize 0 0 0 0 4 0 4 4198 if (next_full_store < 0) { 4199 // Conservative tack: Zero to end of current word. 4200 zeroes_needed = align_up(zeroes_needed, BytesPerInt); 4201 } else { 4202 // Zero to beginning of next fully initialized word. 4203 // Or, don't zero at all, if we are already in that word. 4204 assert(next_full_store >= zeroes_needed, "must go forward"); 4205 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 4206 zeroes_needed = next_full_store; 4207 } 4208 } 4209 4210 if (zeroes_needed > zeroes_done) { 4211 intptr_t zsize = zeroes_needed - zeroes_done; 4212 // Do some incremental zeroing on rawmem, in parallel with inits. 4213 zeroes_done = align_down(zeroes_done, BytesPerInt); 4214 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4215 zeroes_done, zeroes_needed, 4216 phase); 4217 zeroes_done = zeroes_needed; 4218 if (zsize > InitArrayShortSize && ++big_init_gaps > 2) 4219 do_zeroing = false; // leave the hole, next time 4220 } 4221 } 4222 4223 // Collect the store and move on: 4224 st->set_req(MemNode::Memory, inits); 4225 inits = st; // put it on the linearized chain 4226 set_req(i, zmem); // unhook from previous position 4227 4228 if (zeroes_done == st_off) 4229 zeroes_done = next_init_off; 4230 4231 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 4232 4233 #ifdef ASSERT 4234 // Various order invariants. Weaker than stores_are_sane because 4235 // a large constant tile can be filled in by smaller non-constant stores. 4236 assert(st_off >= last_init_off, "inits do not reverse"); 4237 last_init_off = st_off; 4238 const Type* val = NULL; 4239 if (st_size >= BytesPerInt && 4240 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 4241 (int)val->basic_type() < (int)T_OBJECT) { 4242 assert(st_off >= last_tile_end, "tiles do not overlap"); 4243 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 4244 last_tile_end = MAX2(last_tile_end, next_init_off); 4245 } else { 4246 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong); 4247 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 4248 assert(st_off >= last_init_end, "inits do not overlap"); 4249 last_init_end = next_init_off; // it's a non-tile 4250 } 4251 #endif //ASSERT 4252 } 4253 4254 remove_extra_zeroes(); // clear out all the zmems left over 4255 add_req(inits); 4256 4257 if (!(UseTLAB && ZeroTLAB)) { 4258 // If anything remains to be zeroed, zero it all now. 4259 zeroes_done = align_down(zeroes_done, BytesPerInt); 4260 // if it is the last unused 4 bytes of an instance, forget about it 4261 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 4262 if (zeroes_done + BytesPerLong >= size_limit) { 4263 AllocateNode* alloc = allocation(); 4264 assert(alloc != NULL, "must be present"); 4265 if (alloc != NULL && alloc->Opcode() == Op_Allocate) { 4266 Node* klass_node = alloc->in(AllocateNode::KlassNode); 4267 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 4268 if (zeroes_done == k->layout_helper()) 4269 zeroes_done = size_limit; 4270 } 4271 } 4272 if (zeroes_done < size_limit) { 4273 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4274 zeroes_done, size_in_bytes, phase); 4275 } 4276 } 4277 4278 set_complete(phase); 4279 return rawmem; 4280 } 4281 4282 4283 #ifdef ASSERT 4284 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 4285 if (is_complete()) 4286 return true; // stores could be anything at this point 4287 assert(allocation() != NULL, "must be present"); 4288 intptr_t last_off = allocation()->minimum_header_size(); 4289 for (uint i = InitializeNode::RawStores; i < req(); i++) { 4290 Node* st = in(i); 4291 intptr_t st_off = get_store_offset(st, phase); 4292 if (st_off < 0) continue; // ignore dead garbage 4293 if (last_off > st_off) { 4294 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 4295 this->dump(2); 4296 assert(false, "ascending store offsets"); 4297 return false; 4298 } 4299 last_off = st_off + st->as_Store()->memory_size(); 4300 } 4301 return true; 4302 } 4303 #endif //ASSERT 4304 4305 4306 4307 4308 //============================MergeMemNode===================================== 4309 // 4310 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4311 // contributing store or call operations. Each contributor provides the memory 4312 // state for a particular "alias type" (see Compile::alias_type). For example, 4313 // if a MergeMem has an input X for alias category #6, then any memory reference 4314 // to alias category #6 may use X as its memory state input, as an exact equivalent 4315 // to using the MergeMem as a whole. 4316 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4317 // 4318 // (Here, the <N> notation gives the index of the relevant adr_type.) 4319 // 4320 // In one special case (and more cases in the future), alias categories overlap. 4321 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4322 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 4323 // it is exactly equivalent to that state W: 4324 // MergeMem(<Bot>: W) <==> W 4325 // 4326 // Usually, the merge has more than one input. In that case, where inputs 4327 // overlap (i.e., one is Bot), the narrower alias type determines the memory 4328 // state for that type, and the wider alias type (Bot) fills in everywhere else: 4329 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4330 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4331 // 4332 // A merge can take a "wide" memory state as one of its narrow inputs. 4333 // This simply means that the merge observes out only the relevant parts of 4334 // the wide input. That is, wide memory states arriving at narrow merge inputs 4335 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4336 // 4337 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4338 // and that memory slices "leak through": 4339 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4340 // 4341 // But, in such a cascade, repeated memory slices can "block the leak": 4342 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4343 // 4344 // In the last example, Y is not part of the combined memory state of the 4345 // outermost MergeMem. The system must, of course, prevent unschedulable 4346 // memory states from arising, so you can be sure that the state Y is somehow 4347 // a precursor to state Y'. 4348 // 4349 // 4350 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4351 // of each MergeMemNode array are exactly the numerical alias indexes, including 4352 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4353 // Compile::alias_type (and kin) produce and manage these indexes. 4354 // 4355 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4356 // (Note that this provides quick access to the top node inside MergeMem methods, 4357 // without the need to reach out via TLS to Compile::current.) 4358 // 4359 // As a consequence of what was just described, a MergeMem that represents a full 4360 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4361 // containing all alias categories. 4362 // 4363 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4364 // 4365 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4366 // a memory state for the alias type <N>, or else the top node, meaning that 4367 // there is no particular input for that alias type. Note that the length of 4368 // a MergeMem is variable, and may be extended at any time to accommodate new 4369 // memory states at larger alias indexes. When merges grow, they are of course 4370 // filled with "top" in the unused in() positions. 4371 // 4372 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4373 // (Top was chosen because it works smoothly with passes like GCM.) 4374 // 4375 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4376 // the type of random VM bits like TLS references.) Since it is always the 4377 // first non-Bot memory slice, some low-level loops use it to initialize an 4378 // index variable: for (i = AliasIdxRaw; i < req(); i++). 4379 // 4380 // 4381 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4382 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4383 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 4384 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4385 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4386 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4387 // 4388 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4389 // really that different from the other memory inputs. An abbreviation called 4390 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4391 // 4392 // 4393 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4394 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4395 // that "emerges though" the base memory will be marked as excluding the alias types 4396 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 4397 // 4398 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4399 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4400 // 4401 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 4402 // (It is currently unimplemented.) As you can see, the resulting merge is 4403 // actually a disjoint union of memory states, rather than an overlay. 4404 // 4405 4406 //------------------------------MergeMemNode----------------------------------- 4407 Node* MergeMemNode::make_empty_memory() { 4408 Node* empty_memory = (Node*) Compile::current()->top(); 4409 assert(empty_memory->is_top(), "correct sentinel identity"); 4410 return empty_memory; 4411 } 4412 4413 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4414 init_class_id(Class_MergeMem); 4415 // all inputs are nullified in Node::Node(int) 4416 // set_input(0, NULL); // no control input 4417 4418 // Initialize the edges uniformly to top, for starters. 4419 Node* empty_mem = make_empty_memory(); 4420 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4421 init_req(i,empty_mem); 4422 } 4423 assert(empty_memory() == empty_mem, ""); 4424 4425 if( new_base != NULL && new_base->is_MergeMem() ) { 4426 MergeMemNode* mdef = new_base->as_MergeMem(); 4427 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4428 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4429 mms.set_memory(mms.memory2()); 4430 } 4431 assert(base_memory() == mdef->base_memory(), ""); 4432 } else { 4433 set_base_memory(new_base); 4434 } 4435 } 4436 4437 // Make a new, untransformed MergeMem with the same base as 'mem'. 4438 // If mem is itself a MergeMem, populate the result with the same edges. 4439 MergeMemNode* MergeMemNode::make(Node* mem) { 4440 return new MergeMemNode(mem); 4441 } 4442 4443 //------------------------------cmp-------------------------------------------- 4444 uint MergeMemNode::hash() const { return NO_HASH; } 4445 bool MergeMemNode::cmp( const Node &n ) const { 4446 return (&n == this); // Always fail except on self 4447 } 4448 4449 //------------------------------Identity--------------------------------------- 4450 Node* MergeMemNode::Identity(PhaseGVN* phase) { 4451 // Identity if this merge point does not record any interesting memory 4452 // disambiguations. 4453 Node* base_mem = base_memory(); 4454 Node* empty_mem = empty_memory(); 4455 if (base_mem != empty_mem) { // Memory path is not dead? 4456 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4457 Node* mem = in(i); 4458 if (mem != empty_mem && mem != base_mem) { 4459 return this; // Many memory splits; no change 4460 } 4461 } 4462 } 4463 return base_mem; // No memory splits; ID on the one true input 4464 } 4465 4466 //------------------------------Ideal------------------------------------------ 4467 // This method is invoked recursively on chains of MergeMem nodes 4468 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4469 // Remove chain'd MergeMems 4470 // 4471 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4472 // relative to the "in(Bot)". Since we are patching both at the same time, 4473 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4474 // but rewrite each "in(i)" relative to the new "in(Bot)". 4475 Node *progress = NULL; 4476 4477 4478 Node* old_base = base_memory(); 4479 Node* empty_mem = empty_memory(); 4480 if (old_base == empty_mem) 4481 return NULL; // Dead memory path. 4482 4483 MergeMemNode* old_mbase; 4484 if (old_base != NULL && old_base->is_MergeMem()) 4485 old_mbase = old_base->as_MergeMem(); 4486 else 4487 old_mbase = NULL; 4488 Node* new_base = old_base; 4489 4490 // simplify stacked MergeMems in base memory 4491 if (old_mbase) new_base = old_mbase->base_memory(); 4492 4493 // the base memory might contribute new slices beyond my req() 4494 if (old_mbase) grow_to_match(old_mbase); 4495 4496 // Look carefully at the base node if it is a phi. 4497 PhiNode* phi_base; 4498 if (new_base != NULL && new_base->is_Phi()) 4499 phi_base = new_base->as_Phi(); 4500 else 4501 phi_base = NULL; 4502 4503 Node* phi_reg = NULL; 4504 uint phi_len = (uint)-1; 4505 if (phi_base != NULL && !phi_base->is_copy()) { 4506 // do not examine phi if degraded to a copy 4507 phi_reg = phi_base->region(); 4508 phi_len = phi_base->req(); 4509 // see if the phi is unfinished 4510 for (uint i = 1; i < phi_len; i++) { 4511 if (phi_base->in(i) == NULL) { 4512 // incomplete phi; do not look at it yet! 4513 phi_reg = NULL; 4514 phi_len = (uint)-1; 4515 break; 4516 } 4517 } 4518 } 4519 4520 // Note: We do not call verify_sparse on entry, because inputs 4521 // can normalize to the base_memory via subsume_node or similar 4522 // mechanisms. This method repairs that damage. 4523 4524 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4525 4526 // Look at each slice. 4527 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4528 Node* old_in = in(i); 4529 // calculate the old memory value 4530 Node* old_mem = old_in; 4531 if (old_mem == empty_mem) old_mem = old_base; 4532 assert(old_mem == memory_at(i), ""); 4533 4534 // maybe update (reslice) the old memory value 4535 4536 // simplify stacked MergeMems 4537 Node* new_mem = old_mem; 4538 MergeMemNode* old_mmem; 4539 if (old_mem != NULL && old_mem->is_MergeMem()) 4540 old_mmem = old_mem->as_MergeMem(); 4541 else 4542 old_mmem = NULL; 4543 if (old_mmem == this) { 4544 // This can happen if loops break up and safepoints disappear. 4545 // A merge of BotPtr (default) with a RawPtr memory derived from a 4546 // safepoint can be rewritten to a merge of the same BotPtr with 4547 // the BotPtr phi coming into the loop. If that phi disappears 4548 // also, we can end up with a self-loop of the mergemem. 4549 // In general, if loops degenerate and memory effects disappear, 4550 // a mergemem can be left looking at itself. This simply means 4551 // that the mergemem's default should be used, since there is 4552 // no longer any apparent effect on this slice. 4553 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4554 // from start. Update the input to TOP. 4555 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4556 } 4557 else if (old_mmem != NULL) { 4558 new_mem = old_mmem->memory_at(i); 4559 } 4560 // else preceding memory was not a MergeMem 4561 4562 // replace equivalent phis (unfortunately, they do not GVN together) 4563 if (new_mem != NULL && new_mem != new_base && 4564 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4565 if (new_mem->is_Phi()) { 4566 PhiNode* phi_mem = new_mem->as_Phi(); 4567 for (uint i = 1; i < phi_len; i++) { 4568 if (phi_base->in(i) != phi_mem->in(i)) { 4569 phi_mem = NULL; 4570 break; 4571 } 4572 } 4573 if (phi_mem != NULL) { 4574 // equivalent phi nodes; revert to the def 4575 new_mem = new_base; 4576 } 4577 } 4578 } 4579 4580 // maybe store down a new value 4581 Node* new_in = new_mem; 4582 if (new_in == new_base) new_in = empty_mem; 4583 4584 if (new_in != old_in) { 4585 // Warning: Do not combine this "if" with the previous "if" 4586 // A memory slice might have be be rewritten even if it is semantically 4587 // unchanged, if the base_memory value has changed. 4588 set_req(i, new_in); 4589 progress = this; // Report progress 4590 } 4591 } 4592 4593 if (new_base != old_base) { 4594 set_req(Compile::AliasIdxBot, new_base); 4595 // Don't use set_base_memory(new_base), because we need to update du. 4596 assert(base_memory() == new_base, ""); 4597 progress = this; 4598 } 4599 4600 if( base_memory() == this ) { 4601 // a self cycle indicates this memory path is dead 4602 set_req(Compile::AliasIdxBot, empty_mem); 4603 } 4604 4605 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4606 // Recursion must occur after the self cycle check above 4607 if( base_memory()->is_MergeMem() ) { 4608 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4609 Node *m = phase->transform(new_mbase); // Rollup any cycles 4610 if( m != NULL && 4611 (m->is_top() || 4612 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) { 4613 // propagate rollup of dead cycle to self 4614 set_req(Compile::AliasIdxBot, empty_mem); 4615 } 4616 } 4617 4618 if( base_memory() == empty_mem ) { 4619 progress = this; 4620 // Cut inputs during Parse phase only. 4621 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4622 if( !can_reshape ) { 4623 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4624 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4625 } 4626 } 4627 } 4628 4629 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4630 // Check if PhiNode::Ideal's "Split phis through memory merges" 4631 // transform should be attempted. Look for this->phi->this cycle. 4632 uint merge_width = req(); 4633 if (merge_width > Compile::AliasIdxRaw) { 4634 PhiNode* phi = base_memory()->as_Phi(); 4635 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4636 if (phi->in(i) == this) { 4637 phase->is_IterGVN()->_worklist.push(phi); 4638 break; 4639 } 4640 } 4641 } 4642 } 4643 4644 assert(progress || verify_sparse(), "please, no dups of base"); 4645 return progress; 4646 } 4647 4648 //-------------------------set_base_memory------------------------------------- 4649 void MergeMemNode::set_base_memory(Node *new_base) { 4650 Node* empty_mem = empty_memory(); 4651 set_req(Compile::AliasIdxBot, new_base); 4652 assert(memory_at(req()) == new_base, "must set default memory"); 4653 // Clear out other occurrences of new_base: 4654 if (new_base != empty_mem) { 4655 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4656 if (in(i) == new_base) set_req(i, empty_mem); 4657 } 4658 } 4659 } 4660 4661 //------------------------------out_RegMask------------------------------------ 4662 const RegMask &MergeMemNode::out_RegMask() const { 4663 return RegMask::Empty; 4664 } 4665 4666 //------------------------------dump_spec-------------------------------------- 4667 #ifndef PRODUCT 4668 void MergeMemNode::dump_spec(outputStream *st) const { 4669 st->print(" {"); 4670 Node* base_mem = base_memory(); 4671 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4672 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem; 4673 if (mem == base_mem) { st->print(" -"); continue; } 4674 st->print( " N%d:", mem->_idx ); 4675 Compile::current()->get_adr_type(i)->dump_on(st); 4676 } 4677 st->print(" }"); 4678 } 4679 #endif // !PRODUCT 4680 4681 4682 #ifdef ASSERT 4683 static bool might_be_same(Node* a, Node* b) { 4684 if (a == b) return true; 4685 if (!(a->is_Phi() || b->is_Phi())) return false; 4686 // phis shift around during optimization 4687 return true; // pretty stupid... 4688 } 4689 4690 // verify a narrow slice (either incoming or outgoing) 4691 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4692 if (!VerifyAliases) return; // don't bother to verify unless requested 4693 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 4694 if (Node::in_dump()) return; // muzzle asserts when printing 4695 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4696 assert(n != NULL, ""); 4697 // Elide intervening MergeMem's 4698 while (n->is_MergeMem()) { 4699 n = n->as_MergeMem()->memory_at(alias_idx); 4700 } 4701 Compile* C = Compile::current(); 4702 const TypePtr* n_adr_type = n->adr_type(); 4703 if (n == m->empty_memory()) { 4704 // Implicit copy of base_memory() 4705 } else if (n_adr_type != TypePtr::BOTTOM) { 4706 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4707 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4708 } else { 4709 // A few places like make_runtime_call "know" that VM calls are narrow, 4710 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4711 bool expected_wide_mem = false; 4712 if (n == m->base_memory()) { 4713 expected_wide_mem = true; 4714 } else if (alias_idx == Compile::AliasIdxRaw || 4715 n == m->memory_at(Compile::AliasIdxRaw)) { 4716 expected_wide_mem = true; 4717 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4718 // memory can "leak through" calls on channels that 4719 // are write-once. Allow this also. 4720 expected_wide_mem = true; 4721 } 4722 assert(expected_wide_mem, "expected narrow slice replacement"); 4723 } 4724 } 4725 #else // !ASSERT 4726 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4727 #endif 4728 4729 4730 //-----------------------------memory_at--------------------------------------- 4731 Node* MergeMemNode::memory_at(uint alias_idx) const { 4732 assert(alias_idx >= Compile::AliasIdxRaw || 4733 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4734 "must avoid base_memory and AliasIdxTop"); 4735 4736 // Otherwise, it is a narrow slice. 4737 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4738 Compile *C = Compile::current(); 4739 if (is_empty_memory(n)) { 4740 // the array is sparse; empty slots are the "top" node 4741 n = base_memory(); 4742 assert(Node::in_dump() 4743 || n == NULL || n->bottom_type() == Type::TOP 4744 || n->adr_type() == NULL // address is TOP 4745 || n->adr_type() == TypePtr::BOTTOM 4746 || n->adr_type() == TypeRawPtr::BOTTOM 4747 || Compile::current()->AliasLevel() == 0, 4748 "must be a wide memory"); 4749 // AliasLevel == 0 if we are organizing the memory states manually. 4750 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4751 } else { 4752 // make sure the stored slice is sane 4753 #ifdef ASSERT 4754 if (VMError::is_error_reported() || Node::in_dump()) { 4755 } else if (might_be_same(n, base_memory())) { 4756 // Give it a pass: It is a mostly harmless repetition of the base. 4757 // This can arise normally from node subsumption during optimization. 4758 } else { 4759 verify_memory_slice(this, alias_idx, n); 4760 } 4761 #endif 4762 } 4763 return n; 4764 } 4765 4766 //---------------------------set_memory_at------------------------------------- 4767 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4768 verify_memory_slice(this, alias_idx, n); 4769 Node* empty_mem = empty_memory(); 4770 if (n == base_memory()) n = empty_mem; // collapse default 4771 uint need_req = alias_idx+1; 4772 if (req() < need_req) { 4773 if (n == empty_mem) return; // already the default, so do not grow me 4774 // grow the sparse array 4775 do { 4776 add_req(empty_mem); 4777 } while (req() < need_req); 4778 } 4779 set_req( alias_idx, n ); 4780 } 4781 4782 4783 4784 //--------------------------iteration_setup------------------------------------ 4785 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4786 if (other != NULL) { 4787 grow_to_match(other); 4788 // invariant: the finite support of mm2 is within mm->req() 4789 #ifdef ASSERT 4790 for (uint i = req(); i < other->req(); i++) { 4791 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4792 } 4793 #endif 4794 } 4795 // Replace spurious copies of base_memory by top. 4796 Node* base_mem = base_memory(); 4797 if (base_mem != NULL && !base_mem->is_top()) { 4798 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4799 if (in(i) == base_mem) 4800 set_req(i, empty_memory()); 4801 } 4802 } 4803 } 4804 4805 //---------------------------grow_to_match------------------------------------- 4806 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4807 Node* empty_mem = empty_memory(); 4808 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4809 // look for the finite support of the other memory 4810 for (uint i = other->req(); --i >= req(); ) { 4811 if (other->in(i) != empty_mem) { 4812 uint new_len = i+1; 4813 while (req() < new_len) add_req(empty_mem); 4814 break; 4815 } 4816 } 4817 } 4818 4819 //---------------------------verify_sparse------------------------------------- 4820 #ifndef PRODUCT 4821 bool MergeMemNode::verify_sparse() const { 4822 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4823 Node* base_mem = base_memory(); 4824 // The following can happen in degenerate cases, since empty==top. 4825 if (is_empty_memory(base_mem)) return true; 4826 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4827 assert(in(i) != NULL, "sane slice"); 4828 if (in(i) == base_mem) return false; // should have been the sentinel value! 4829 } 4830 return true; 4831 } 4832 4833 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4834 Node* n; 4835 n = mm->in(idx); 4836 if (mem == n) return true; // might be empty_memory() 4837 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4838 if (mem == n) return true; 4839 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4840 if (mem == n) return true; 4841 if (n == NULL) break; 4842 } 4843 return false; 4844 } 4845 #endif // !PRODUCT