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