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