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