1 /* 2 * Copyright (c) 1997, 2014, 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 "oops/objArrayKlass.hpp" 30 #include "opto/addnode.hpp" 31 #include "opto/cfgnode.hpp" 32 #include "opto/compile.hpp" 33 #include "opto/connode.hpp" 34 #include "opto/convertnode.hpp" 35 #include "opto/loopnode.hpp" 36 #include "opto/machnode.hpp" 37 #include "opto/matcher.hpp" 38 #include "opto/memnode.hpp" 39 #include "opto/mulnode.hpp" 40 #include "opto/narrowptrnode.hpp" 41 #include "opto/phaseX.hpp" 42 #include "opto/regmask.hpp" 43 44 // Portions of code courtesy of Clifford Click 45 46 // Optimization - Graph Style 47 48 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 49 50 //============================================================================= 51 uint MemNode::size_of() const { return sizeof(*this); } 52 53 const TypePtr *MemNode::adr_type() const { 54 Node* adr = in(Address); 55 const TypePtr* cross_check = NULL; 56 DEBUG_ONLY(cross_check = _adr_type); 57 return calculate_adr_type(adr->bottom_type(), cross_check); 58 } 59 60 #ifndef PRODUCT 61 void MemNode::dump_spec(outputStream *st) const { 62 if (in(Address) == NULL) return; // node is dead 63 #ifndef ASSERT 64 // fake the missing field 65 const TypePtr* _adr_type = NULL; 66 if (in(Address) != NULL) 67 _adr_type = in(Address)->bottom_type()->isa_ptr(); 68 #endif 69 dump_adr_type(this, _adr_type, st); 70 71 Compile* C = Compile::current(); 72 if( C->alias_type(_adr_type)->is_volatile() ) 73 st->print(" Volatile!"); 74 } 75 76 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 77 st->print(" @"); 78 if (adr_type == NULL) { 79 st->print("NULL"); 80 } else { 81 adr_type->dump_on(st); 82 Compile* C = Compile::current(); 83 Compile::AliasType* atp = NULL; 84 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 85 if (atp == NULL) 86 st->print(", idx=?\?;"); 87 else if (atp->index() == Compile::AliasIdxBot) 88 st->print(", idx=Bot;"); 89 else if (atp->index() == Compile::AliasIdxTop) 90 st->print(", idx=Top;"); 91 else if (atp->index() == Compile::AliasIdxRaw) 92 st->print(", idx=Raw;"); 93 else { 94 ciField* field = atp->field(); 95 if (field) { 96 st->print(", name="); 97 field->print_name_on(st); 98 } 99 st->print(", idx=%d;", atp->index()); 100 } 101 } 102 } 103 104 extern void print_alias_types(); 105 106 #endif 107 108 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) { 109 assert((t_oop != NULL), "sanity"); 110 bool is_instance = t_oop->is_known_instance_field(); 111 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() && 112 (load != NULL) && load->is_Load() && 113 (phase->is_IterGVN() != NULL); 114 if (!(is_instance || is_boxed_value_load)) 115 return mchain; // don't try to optimize non-instance types 116 uint instance_id = t_oop->instance_id(); 117 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory); 118 Node *prev = NULL; 119 Node *result = mchain; 120 while (prev != result) { 121 prev = result; 122 if (result == start_mem) 123 break; // hit one of our sentinels 124 // skip over a call which does not affect this memory slice 125 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 126 Node *proj_in = result->in(0); 127 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 128 break; // hit one of our sentinels 129 } else if (proj_in->is_Call()) { 130 CallNode *call = proj_in->as_Call(); 131 if (!call->may_modify(t_oop, phase)) { // returns false for instances 132 result = call->in(TypeFunc::Memory); 133 } 134 } else if (proj_in->is_Initialize()) { 135 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 136 // Stop if this is the initialization for the object instance which 137 // which contains this memory slice, otherwise skip over it. 138 if ((alloc == NULL) || (alloc->_idx == instance_id)) { 139 break; 140 } 141 if (is_instance) { 142 result = proj_in->in(TypeFunc::Memory); 143 } else if (is_boxed_value_load) { 144 Node* klass = alloc->in(AllocateNode::KlassNode); 145 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 146 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) { 147 result = proj_in->in(TypeFunc::Memory); // not related allocation 148 } 149 } 150 } else if (proj_in->is_MemBar()) { 151 result = proj_in->in(TypeFunc::Memory); 152 } else { 153 assert(false, "unexpected projection"); 154 } 155 } else if (result->is_ClearArray()) { 156 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) { 157 // Can not bypass initialization of the instance 158 // we are looking for. 159 break; 160 } 161 // Otherwise skip it (the call updated 'result' value). 162 } else if (result->is_MergeMem()) { 163 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty); 164 } 165 } 166 return result; 167 } 168 169 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 170 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 171 if (t_oop == NULL) 172 return mchain; // don't try to optimize non-oop types 173 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 174 bool is_instance = t_oop->is_known_instance_field(); 175 PhaseIterGVN *igvn = phase->is_IterGVN(); 176 if (is_instance && igvn != NULL && result->is_Phi()) { 177 PhiNode *mphi = result->as_Phi(); 178 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 179 const TypePtr *t = mphi->adr_type(); 180 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 181 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 182 t->is_oopptr()->cast_to_exactness(true) 183 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 184 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) { 185 // clone the Phi with our address type 186 result = mphi->split_out_instance(t_adr, igvn); 187 } else { 188 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 189 } 190 } 191 return result; 192 } 193 194 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 195 uint alias_idx = phase->C->get_alias_index(tp); 196 Node *mem = mmem; 197 #ifdef ASSERT 198 { 199 // Check that current type is consistent with the alias index used during graph construction 200 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 201 bool consistent = adr_check == NULL || adr_check->empty() || 202 phase->C->must_alias(adr_check, alias_idx ); 203 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 204 if( !consistent && adr_check != NULL && !adr_check->empty() && 205 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 206 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 207 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 208 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 209 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 210 // don't assert if it is dead code. 211 consistent = true; 212 } 213 if( !consistent ) { 214 st->print("alias_idx==%d, adr_check==", alias_idx); 215 if( adr_check == NULL ) { 216 st->print("NULL"); 217 } else { 218 adr_check->dump(); 219 } 220 st->cr(); 221 print_alias_types(); 222 assert(consistent, "adr_check must match alias idx"); 223 } 224 } 225 #endif 226 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 227 // means an array I have not precisely typed yet. Do not do any 228 // alias stuff with it any time soon. 229 const TypeOopPtr *toop = tp->isa_oopptr(); 230 if( tp->base() != Type::AnyPtr && 231 !(toop && 232 toop->klass() != NULL && 233 toop->klass()->is_java_lang_Object() && 234 toop->offset() == Type::OffsetBot) ) { 235 // compress paths and change unreachable cycles to TOP 236 // If not, we can update the input infinitely along a MergeMem cycle 237 // Equivalent code in PhiNode::Ideal 238 Node* m = phase->transform(mmem); 239 // If transformed to a MergeMem, get the desired slice 240 // Otherwise the returned node represents memory for every slice 241 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 242 // Update input if it is progress over what we have now 243 } 244 return mem; 245 } 246 247 //--------------------------Ideal_common--------------------------------------- 248 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. 249 // Unhook non-raw memories from complete (macro-expanded) initializations. 250 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 251 // If our control input is a dead region, kill all below the region 252 Node *ctl = in(MemNode::Control); 253 if (ctl && remove_dead_region(phase, can_reshape)) 254 return this; 255 ctl = in(MemNode::Control); 256 // Don't bother trying to transform a dead node 257 if (ctl && ctl->is_top()) return NodeSentinel; 258 259 PhaseIterGVN *igvn = phase->is_IterGVN(); 260 // Wait if control on the worklist. 261 if (ctl && can_reshape && igvn != NULL) { 262 Node* bol = NULL; 263 Node* cmp = NULL; 264 if (ctl->in(0)->is_If()) { 265 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 266 bol = ctl->in(0)->in(1); 267 if (bol->is_Bool()) 268 cmp = ctl->in(0)->in(1)->in(1); 269 } 270 if (igvn->_worklist.member(ctl) || 271 (bol != NULL && igvn->_worklist.member(bol)) || 272 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 273 // This control path may be dead. 274 // Delay this memory node transformation until the control is processed. 275 phase->is_IterGVN()->_worklist.push(this); 276 return NodeSentinel; // caller will return NULL 277 } 278 } 279 // Ignore if memory is dead, or self-loop 280 Node *mem = in(MemNode::Memory); 281 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL 282 assert(mem != this, "dead loop in MemNode::Ideal"); 283 284 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 285 // This memory slice may be dead. 286 // Delay this mem node transformation until the memory is processed. 287 phase->is_IterGVN()->_worklist.push(this); 288 return NodeSentinel; // caller will return NULL 289 } 290 291 Node *address = in(MemNode::Address); 292 const Type *t_adr = phase->type(address); 293 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL 294 295 if (can_reshape && igvn != NULL && 296 (igvn->_worklist.member(address) || 297 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) { 298 // The address's base and type may change when the address is processed. 299 // Delay this mem node transformation until the address is processed. 300 phase->is_IterGVN()->_worklist.push(this); 301 return NodeSentinel; // caller will return NULL 302 } 303 304 // Do NOT remove or optimize the next lines: ensure a new alias index 305 // is allocated for an oop pointer type before Escape Analysis. 306 // Note: C++ will not remove it since the call has side effect. 307 if (t_adr->isa_oopptr()) { 308 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 309 } 310 311 Node* base = NULL; 312 if (address->is_AddP()) { 313 base = address->in(AddPNode::Base); 314 } 315 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 316 !t_adr->isa_rawptr()) { 317 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 318 // Skip this node optimization if its address has TOP base. 319 return NodeSentinel; // caller will return NULL 320 } 321 322 // Avoid independent memory operations 323 Node* old_mem = mem; 324 325 // The code which unhooks non-raw memories from complete (macro-expanded) 326 // initializations was removed. After macro-expansion all stores catched 327 // by Initialize node became raw stores and there is no information 328 // which memory slices they modify. So it is unsafe to move any memory 329 // operation above these stores. Also in most cases hooked non-raw memories 330 // were already unhooked by using information from detect_ptr_independence() 331 // and find_previous_store(). 332 333 if (mem->is_MergeMem()) { 334 MergeMemNode* mmem = mem->as_MergeMem(); 335 const TypePtr *tp = t_adr->is_ptr(); 336 337 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 338 } 339 340 if (mem != old_mem) { 341 set_req(MemNode::Memory, mem); 342 if (can_reshape && old_mem->outcnt() == 0) { 343 igvn->_worklist.push(old_mem); 344 } 345 if (phase->type( mem ) == Type::TOP) return NodeSentinel; 346 return this; 347 } 348 349 // let the subclass continue analyzing... 350 return NULL; 351 } 352 353 // Helper function for proving some simple control dominations. 354 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 355 // Already assumes that 'dom' is available at 'sub', and that 'sub' 356 // is not a constant (dominated by the method's StartNode). 357 // Used by MemNode::find_previous_store to prove that the 358 // control input of a memory operation predates (dominates) 359 // an allocation it wants to look past. 360 bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 361 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 362 return false; // Conservative answer for dead code 363 364 // Check 'dom'. Skip Proj and CatchProj nodes. 365 dom = dom->find_exact_control(dom); 366 if (dom == NULL || dom->is_top()) 367 return false; // Conservative answer for dead code 368 369 if (dom == sub) { 370 // For the case when, for example, 'sub' is Initialize and the original 371 // 'dom' is Proj node of the 'sub'. 372 return false; 373 } 374 375 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 376 return true; 377 378 // 'dom' dominates 'sub' if its control edge and control edges 379 // of all its inputs dominate or equal to sub's control edge. 380 381 // Currently 'sub' is either Allocate, Initialize or Start nodes. 382 // Or Region for the check in LoadNode::Ideal(); 383 // 'sub' should have sub->in(0) != NULL. 384 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 385 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 386 387 // Get control edge of 'sub'. 388 Node* orig_sub = sub; 389 sub = sub->find_exact_control(sub->in(0)); 390 if (sub == NULL || sub->is_top()) 391 return false; // Conservative answer for dead code 392 393 assert(sub->is_CFG(), "expecting control"); 394 395 if (sub == dom) 396 return true; 397 398 if (sub->is_Start() || sub->is_Root()) 399 return false; 400 401 { 402 // Check all control edges of 'dom'. 403 404 ResourceMark rm; 405 Arena* arena = Thread::current()->resource_area(); 406 Node_List nlist(arena); 407 Unique_Node_List dom_list(arena); 408 409 dom_list.push(dom); 410 bool only_dominating_controls = false; 411 412 for (uint next = 0; next < dom_list.size(); next++) { 413 Node* n = dom_list.at(next); 414 if (n == orig_sub) 415 return false; // One of dom's inputs dominated by sub. 416 if (!n->is_CFG() && n->pinned()) { 417 // Check only own control edge for pinned non-control nodes. 418 n = n->find_exact_control(n->in(0)); 419 if (n == NULL || n->is_top()) 420 return false; // Conservative answer for dead code 421 assert(n->is_CFG(), "expecting control"); 422 dom_list.push(n); 423 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 424 only_dominating_controls = true; 425 } else if (n->is_CFG()) { 426 if (n->dominates(sub, nlist)) 427 only_dominating_controls = true; 428 else 429 return false; 430 } else { 431 // First, own control edge. 432 Node* m = n->find_exact_control(n->in(0)); 433 if (m != NULL) { 434 if (m->is_top()) 435 return false; // Conservative answer for dead code 436 dom_list.push(m); 437 } 438 // Now, the rest of edges. 439 uint cnt = n->req(); 440 for (uint i = 1; i < cnt; i++) { 441 m = n->find_exact_control(n->in(i)); 442 if (m == NULL || m->is_top()) 443 continue; 444 dom_list.push(m); 445 } 446 } 447 } 448 return only_dominating_controls; 449 } 450 } 451 452 //---------------------detect_ptr_independence--------------------------------- 453 // Used by MemNode::find_previous_store to prove that two base 454 // pointers are never equal. 455 // The pointers are accompanied by their associated allocations, 456 // if any, which have been previously discovered by the caller. 457 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 458 Node* p2, AllocateNode* a2, 459 PhaseTransform* phase) { 460 // Attempt to prove that these two pointers cannot be aliased. 461 // They may both manifestly be allocations, and they should differ. 462 // Or, if they are not both allocations, they can be distinct constants. 463 // Otherwise, one is an allocation and the other a pre-existing value. 464 if (a1 == NULL && a2 == NULL) { // neither an allocation 465 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 466 } else if (a1 != NULL && a2 != NULL) { // both allocations 467 return (a1 != a2); 468 } else if (a1 != NULL) { // one allocation a1 469 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 470 return all_controls_dominate(p2, a1); 471 } else { //(a2 != NULL) // one allocation a2 472 return all_controls_dominate(p1, a2); 473 } 474 return false; 475 } 476 477 478 // The logic for reordering loads and stores uses four steps: 479 // (a) Walk carefully past stores and initializations which we 480 // can prove are independent of this load. 481 // (b) Observe that the next memory state makes an exact match 482 // with self (load or store), and locate the relevant store. 483 // (c) Ensure that, if we were to wire self directly to the store, 484 // the optimizer would fold it up somehow. 485 // (d) Do the rewiring, and return, depending on some other part of 486 // the optimizer to fold up the load. 487 // This routine handles steps (a) and (b). Steps (c) and (d) are 488 // specific to loads and stores, so they are handled by the callers. 489 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 490 // 491 Node* MemNode::find_previous_store(PhaseTransform* phase) { 492 Node* ctrl = in(MemNode::Control); 493 Node* adr = in(MemNode::Address); 494 intptr_t offset = 0; 495 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 496 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 497 498 if (offset == Type::OffsetBot) 499 return NULL; // cannot unalias unless there are precise offsets 500 501 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 502 503 intptr_t size_in_bytes = memory_size(); 504 505 Node* mem = in(MemNode::Memory); // start searching here... 506 507 int cnt = 50; // Cycle limiter 508 for (;;) { // While we can dance past unrelated stores... 509 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 510 511 if (mem->is_Store()) { 512 Node* st_adr = mem->in(MemNode::Address); 513 intptr_t st_offset = 0; 514 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 515 if (st_base == NULL) 516 break; // inscrutable pointer 517 if (st_offset != offset && st_offset != Type::OffsetBot) { 518 const int MAX_STORE = BytesPerLong; 519 if (st_offset >= offset + size_in_bytes || 520 st_offset <= offset - MAX_STORE || 521 st_offset <= offset - mem->as_Store()->memory_size()) { 522 // Success: The offsets are provably independent. 523 // (You may ask, why not just test st_offset != offset and be done? 524 // The answer is that stores of different sizes can co-exist 525 // in the same sequence of RawMem effects. We sometimes initialize 526 // a whole 'tile' of array elements with a single jint or jlong.) 527 mem = mem->in(MemNode::Memory); 528 continue; // (a) advance through independent store memory 529 } 530 } 531 if (st_base != base && 532 detect_ptr_independence(base, alloc, 533 st_base, 534 AllocateNode::Ideal_allocation(st_base, phase), 535 phase)) { 536 // Success: The bases are provably independent. 537 mem = mem->in(MemNode::Memory); 538 continue; // (a) advance through independent store memory 539 } 540 541 // (b) At this point, if the bases or offsets do not agree, we lose, 542 // since we have not managed to prove 'this' and 'mem' independent. 543 if (st_base == base && st_offset == offset) { 544 return mem; // let caller handle steps (c), (d) 545 } 546 547 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 548 InitializeNode* st_init = mem->in(0)->as_Initialize(); 549 AllocateNode* st_alloc = st_init->allocation(); 550 if (st_alloc == NULL) 551 break; // something degenerated 552 bool known_identical = false; 553 bool known_independent = false; 554 if (alloc == st_alloc) 555 known_identical = true; 556 else if (alloc != NULL) 557 known_independent = true; 558 else if (all_controls_dominate(this, st_alloc)) 559 known_independent = true; 560 561 if (known_independent) { 562 // The bases are provably independent: Either they are 563 // manifestly distinct allocations, or else the control 564 // of this load dominates the store's allocation. 565 int alias_idx = phase->C->get_alias_index(adr_type()); 566 if (alias_idx == Compile::AliasIdxRaw) { 567 mem = st_alloc->in(TypeFunc::Memory); 568 } else { 569 mem = st_init->memory(alias_idx); 570 } 571 continue; // (a) advance through independent store memory 572 } 573 574 // (b) at this point, if we are not looking at a store initializing 575 // the same allocation we are loading from, we lose. 576 if (known_identical) { 577 // From caller, can_see_stored_value will consult find_captured_store. 578 return mem; // let caller handle steps (c), (d) 579 } 580 581 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 582 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 583 if (mem->is_Proj() && mem->in(0)->is_Call()) { 584 CallNode *call = mem->in(0)->as_Call(); 585 if (!call->may_modify(addr_t, phase)) { 586 mem = call->in(TypeFunc::Memory); 587 continue; // (a) advance through independent call memory 588 } 589 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 590 mem = mem->in(0)->in(TypeFunc::Memory); 591 continue; // (a) advance through independent MemBar memory 592 } else if (mem->is_ClearArray()) { 593 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 594 // (the call updated 'mem' value) 595 continue; // (a) advance through independent allocation memory 596 } else { 597 // Can not bypass initialization of the instance 598 // we are looking for. 599 return mem; 600 } 601 } else if (mem->is_MergeMem()) { 602 int alias_idx = phase->C->get_alias_index(adr_type()); 603 mem = mem->as_MergeMem()->memory_at(alias_idx); 604 continue; // (a) advance through independent MergeMem memory 605 } 606 } 607 608 // Unless there is an explicit 'continue', we must bail out here, 609 // because 'mem' is an inscrutable memory state (e.g., a call). 610 break; 611 } 612 613 return NULL; // bail out 614 } 615 616 //----------------------calculate_adr_type------------------------------------- 617 // Helper function. Notices when the given type of address hits top or bottom. 618 // Also, asserts a cross-check of the type against the expected address type. 619 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 620 if (t == Type::TOP) return NULL; // does not touch memory any more? 621 #ifdef PRODUCT 622 cross_check = NULL; 623 #else 624 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL; 625 #endif 626 const TypePtr* tp = t->isa_ptr(); 627 if (tp == NULL) { 628 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 629 return TypePtr::BOTTOM; // touches lots of memory 630 } else { 631 #ifdef ASSERT 632 // %%%% [phh] We don't check the alias index if cross_check is 633 // TypeRawPtr::BOTTOM. Needs to be investigated. 634 if (cross_check != NULL && 635 cross_check != TypePtr::BOTTOM && 636 cross_check != TypeRawPtr::BOTTOM) { 637 // Recheck the alias index, to see if it has changed (due to a bug). 638 Compile* C = Compile::current(); 639 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 640 "must stay in the original alias category"); 641 // The type of the address must be contained in the adr_type, 642 // disregarding "null"-ness. 643 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 644 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 645 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 646 "real address must not escape from expected memory type"); 647 } 648 #endif 649 return tp; 650 } 651 } 652 653 //------------------------adr_phi_is_loop_invariant---------------------------- 654 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted 655 // loop is loop invariant. Make a quick traversal of Phi and associated 656 // CastPP nodes, looking to see if they are a closed group within the loop. 657 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) { 658 // The idea is that the phi-nest must boil down to only CastPP nodes 659 // with the same data. This implies that any path into the loop already 660 // includes such a CastPP, and so the original cast, whatever its input, 661 // must be covered by an equivalent cast, with an earlier control input. 662 ResourceMark rm; 663 664 // The loop entry input of the phi should be the unique dominating 665 // node for every Phi/CastPP in the loop. 666 Unique_Node_List closure; 667 closure.push(adr_phi->in(LoopNode::EntryControl)); 668 669 // Add the phi node and the cast to the worklist. 670 Unique_Node_List worklist; 671 worklist.push(adr_phi); 672 if( cast != NULL ){ 673 if( !cast->is_ConstraintCast() ) return false; 674 worklist.push(cast); 675 } 676 677 // Begin recursive walk of phi nodes. 678 while( worklist.size() ){ 679 // Take a node off the worklist 680 Node *n = worklist.pop(); 681 if( !closure.member(n) ){ 682 // Add it to the closure. 683 closure.push(n); 684 // Make a sanity check to ensure we don't waste too much time here. 685 if( closure.size() > 20) return false; 686 // This node is OK if: 687 // - it is a cast of an identical value 688 // - or it is a phi node (then we add its inputs to the worklist) 689 // Otherwise, the node is not OK, and we presume the cast is not invariant 690 if( n->is_ConstraintCast() ){ 691 worklist.push(n->in(1)); 692 } else if( n->is_Phi() ) { 693 for( uint i = 1; i < n->req(); i++ ) { 694 worklist.push(n->in(i)); 695 } 696 } else { 697 return false; 698 } 699 } 700 } 701 702 // Quit when the worklist is empty, and we've found no offending nodes. 703 return true; 704 } 705 706 //------------------------------Ideal_DU_postCCP------------------------------- 707 // Find any cast-away of null-ness and keep its control. Null cast-aways are 708 // going away in this pass and we need to make this memory op depend on the 709 // gating null check. 710 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) { 711 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address)); 712 } 713 714 // I tried to leave the CastPP's in. This makes the graph more accurate in 715 // some sense; we get to keep around the knowledge that an oop is not-null 716 // after some test. Alas, the CastPP's interfere with GVN (some values are 717 // the regular oop, some are the CastPP of the oop, all merge at Phi's which 718 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed 719 // some of the more trivial cases in the optimizer. Removing more useless 720 // Phi's started allowing Loads to illegally float above null checks. I gave 721 // up on this approach. CNC 10/20/2000 722 // This static method may be called not from MemNode (EncodePNode calls it). 723 // Only the control edge of the node 'n' might be updated. 724 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) { 725 Node *skipped_cast = NULL; 726 // Need a null check? Regular static accesses do not because they are 727 // from constant addresses. Array ops are gated by the range check (which 728 // always includes a NULL check). Just check field ops. 729 if( n->in(MemNode::Control) == NULL ) { 730 // Scan upwards for the highest location we can place this memory op. 731 while( true ) { 732 switch( adr->Opcode() ) { 733 734 case Op_AddP: // No change to NULL-ness, so peek thru AddP's 735 adr = adr->in(AddPNode::Base); 736 continue; 737 738 case Op_DecodeN: // No change to NULL-ness, so peek thru 739 case Op_DecodeNKlass: 740 adr = adr->in(1); 741 continue; 742 743 case Op_EncodeP: 744 case Op_EncodePKlass: 745 // EncodeP node's control edge could be set by this method 746 // when EncodeP node depends on CastPP node. 747 // 748 // Use its control edge for memory op because EncodeP may go away 749 // later when it is folded with following or preceding DecodeN node. 750 if (adr->in(0) == NULL) { 751 // Keep looking for cast nodes. 752 adr = adr->in(1); 753 continue; 754 } 755 ccp->hash_delete(n); 756 n->set_req(MemNode::Control, adr->in(0)); 757 ccp->hash_insert(n); 758 return n; 759 760 case Op_CastPP: 761 // If the CastPP is useless, just peek on through it. 762 if( ccp->type(adr) == ccp->type(adr->in(1)) ) { 763 // Remember the cast that we've peeked though. If we peek 764 // through more than one, then we end up remembering the highest 765 // one, that is, if in a loop, the one closest to the top. 766 skipped_cast = adr; 767 adr = adr->in(1); 768 continue; 769 } 770 // CastPP is going away in this pass! We need this memory op to be 771 // control-dependent on the test that is guarding the CastPP. 772 ccp->hash_delete(n); 773 n->set_req(MemNode::Control, adr->in(0)); 774 ccp->hash_insert(n); 775 return n; 776 777 case Op_Phi: 778 // Attempt to float above a Phi to some dominating point. 779 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) { 780 // If we've already peeked through a Cast (which could have set the 781 // control), we can't float above a Phi, because the skipped Cast 782 // may not be loop invariant. 783 if (adr_phi_is_loop_invariant(adr, skipped_cast)) { 784 adr = adr->in(1); 785 continue; 786 } 787 } 788 789 // Intentional fallthrough! 790 791 // No obvious dominating point. The mem op is pinned below the Phi 792 // by the Phi itself. If the Phi goes away (no true value is merged) 793 // then the mem op can float, but not indefinitely. It must be pinned 794 // behind the controls leading to the Phi. 795 case Op_CheckCastPP: 796 // These usually stick around to change address type, however a 797 // useless one can be elided and we still need to pick up a control edge 798 if (adr->in(0) == NULL) { 799 // This CheckCastPP node has NO control and is likely useless. But we 800 // need check further up the ancestor chain for a control input to keep 801 // the node in place. 4959717. 802 skipped_cast = adr; 803 adr = adr->in(1); 804 continue; 805 } 806 ccp->hash_delete(n); 807 n->set_req(MemNode::Control, adr->in(0)); 808 ccp->hash_insert(n); 809 return n; 810 811 // List of "safe" opcodes; those that implicitly block the memory 812 // op below any null check. 813 case Op_CastX2P: // no null checks on native pointers 814 case Op_Parm: // 'this' pointer is not null 815 case Op_LoadP: // Loading from within a klass 816 case Op_LoadN: // Loading from within a klass 817 case Op_LoadKlass: // Loading from within a klass 818 case Op_LoadNKlass: // Loading from within a klass 819 case Op_ConP: // Loading from a klass 820 case Op_ConN: // Loading from a klass 821 case Op_ConNKlass: // Loading from a klass 822 case Op_CreateEx: // Sucking up the guts of an exception oop 823 case Op_Con: // Reading from TLS 824 case Op_CMoveP: // CMoveP is pinned 825 case Op_CMoveN: // CMoveN is pinned 826 break; // No progress 827 828 case Op_Proj: // Direct call to an allocation routine 829 case Op_SCMemProj: // Memory state from store conditional ops 830 #ifdef ASSERT 831 { 832 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value"); 833 const Node* call = adr->in(0); 834 if (call->is_CallJava()) { 835 const CallJavaNode* call_java = call->as_CallJava(); 836 const TypeTuple *r = call_java->tf()->range(); 837 assert(r->cnt() > TypeFunc::Parms, "must return value"); 838 const Type* ret_type = r->field_at(TypeFunc::Parms); 839 assert(ret_type && ret_type->isa_ptr(), "must return pointer"); 840 // We further presume that this is one of 841 // new_instance_Java, new_array_Java, or 842 // the like, but do not assert for this. 843 } else if (call->is_Allocate()) { 844 // similar case to new_instance_Java, etc. 845 } else if (!call->is_CallLeaf()) { 846 // Projections from fetch_oop (OSR) are allowed as well. 847 ShouldNotReachHere(); 848 } 849 } 850 #endif 851 break; 852 default: 853 ShouldNotReachHere(); 854 } 855 break; 856 } 857 } 858 859 return NULL; // No progress 860 } 861 862 863 //============================================================================= 864 uint LoadNode::size_of() const { return sizeof(*this); } 865 uint LoadNode::cmp( const Node &n ) const 866 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 867 const Type *LoadNode::bottom_type() const { return _type; } 868 uint LoadNode::ideal_reg() const { 869 return _type->ideal_reg(); 870 } 871 872 #ifndef PRODUCT 873 void LoadNode::dump_spec(outputStream *st) const { 874 MemNode::dump_spec(st); 875 if( !Verbose && !WizardMode ) { 876 // standard dump does this in Verbose and WizardMode 877 st->print(" #"); _type->dump_on(st); 878 } 879 } 880 #endif 881 882 #ifdef ASSERT 883 //----------------------------is_immutable_value------------------------------- 884 // Helper function to allow a raw load without control edge for some cases 885 bool LoadNode::is_immutable_value(Node* adr) { 886 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 887 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 888 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 889 in_bytes(JavaThread::osthread_offset()))); 890 } 891 #endif 892 893 //----------------------------LoadNode::make----------------------------------- 894 // Polymorphic factory method: 895 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo) { 896 Compile* C = gvn.C; 897 898 // sanity check the alias category against the created node type 899 assert(!(adr_type->isa_oopptr() && 900 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 901 "use LoadKlassNode instead"); 902 assert(!(adr_type->isa_aryptr() && 903 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 904 "use LoadRangeNode instead"); 905 // Check control edge of raw loads 906 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 907 // oop will be recorded in oop map if load crosses safepoint 908 rt->isa_oopptr() || is_immutable_value(adr), 909 "raw memory operations should have control edge"); 910 switch (bt) { 911 case T_BOOLEAN: return new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo); 912 case T_BYTE: return new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo); 913 case T_INT: return new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo); 914 case T_CHAR: return new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo); 915 case T_SHORT: return new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo); 916 case T_LONG: return new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo); 917 case T_FLOAT: return new LoadFNode (ctl, mem, adr, adr_type, rt, mo); 918 case T_DOUBLE: return new LoadDNode (ctl, mem, adr, adr_type, rt, mo); 919 case T_ADDRESS: return new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo); 920 case T_OBJECT: 921 #ifdef _LP64 922 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 923 Node* load = gvn.transform(new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo)); 924 return new DecodeNNode(load, load->bottom_type()->make_ptr()); 925 } else 926 #endif 927 { 928 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 929 return new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo); 930 } 931 } 932 ShouldNotReachHere(); 933 return (LoadNode*)NULL; 934 } 935 936 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) { 937 bool require_atomic = true; 938 return new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, require_atomic); 939 } 940 941 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) { 942 bool require_atomic = true; 943 return new LoadDNode(ctl, mem, adr, adr_type, rt, mo, require_atomic); 944 } 945 946 947 948 //------------------------------hash------------------------------------------- 949 uint LoadNode::hash() const { 950 // unroll addition of interesting fields 951 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 952 } 953 954 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 955 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 956 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 957 bool is_stable_ary = FoldStableValues && 958 (tp != NULL) && (tp->isa_aryptr() != NULL) && 959 tp->isa_aryptr()->is_stable(); 960 961 return (eliminate_boxing && non_volatile) || is_stable_ary; 962 } 963 964 return false; 965 } 966 967 //---------------------------can_see_stored_value------------------------------ 968 // This routine exists to make sure this set of tests is done the same 969 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 970 // will change the graph shape in a way which makes memory alive twice at the 971 // same time (uses the Oracle model of aliasing), then some 972 // LoadXNode::Identity will fold things back to the equivalence-class model 973 // of aliasing. 974 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 975 Node* ld_adr = in(MemNode::Address); 976 intptr_t ld_off = 0; 977 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 978 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 979 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 980 // This is more general than load from boxing objects. 981 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 982 uint alias_idx = atp->index(); 983 bool final = !atp->is_rewritable(); 984 Node* result = NULL; 985 Node* current = st; 986 // Skip through chains of MemBarNodes checking the MergeMems for 987 // new states for the slice of this load. Stop once any other 988 // kind of node is encountered. Loads from final memory can skip 989 // through any kind of MemBar but normal loads shouldn't skip 990 // through MemBarAcquire since the could allow them to move out of 991 // a synchronized region. 992 while (current->is_Proj()) { 993 int opc = current->in(0)->Opcode(); 994 if ((final && (opc == Op_MemBarAcquire || 995 opc == Op_MemBarAcquireLock || 996 opc == Op_LoadFence)) || 997 opc == Op_MemBarRelease || 998 opc == Op_StoreFence || 999 opc == Op_MemBarReleaseLock || 1000 opc == Op_MemBarCPUOrder) { 1001 Node* mem = current->in(0)->in(TypeFunc::Memory); 1002 if (mem->is_MergeMem()) { 1003 MergeMemNode* merge = mem->as_MergeMem(); 1004 Node* new_st = merge->memory_at(alias_idx); 1005 if (new_st == merge->base_memory()) { 1006 // Keep searching 1007 current = new_st; 1008 continue; 1009 } 1010 // Save the new memory state for the slice and fall through 1011 // to exit. 1012 result = new_st; 1013 } 1014 } 1015 break; 1016 } 1017 if (result != NULL) { 1018 st = result; 1019 } 1020 } 1021 1022 // Loop around twice in the case Load -> Initialize -> Store. 1023 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1024 for (int trip = 0; trip <= 1; trip++) { 1025 1026 if (st->is_Store()) { 1027 Node* st_adr = st->in(MemNode::Address); 1028 if (!phase->eqv(st_adr, ld_adr)) { 1029 // Try harder before giving up... Match raw and non-raw pointers. 1030 intptr_t st_off = 0; 1031 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 1032 if (alloc == NULL) return NULL; 1033 if (alloc != ld_alloc) return NULL; 1034 if (ld_off != st_off) return NULL; 1035 // At this point we have proven something like this setup: 1036 // A = Allocate(...) 1037 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 1038 // S = StoreQ(, AddP(, A.Parm , #Off), V) 1039 // (Actually, we haven't yet proven the Q's are the same.) 1040 // In other words, we are loading from a casted version of 1041 // the same pointer-and-offset that we stored to. 1042 // Thus, we are able to replace L by V. 1043 } 1044 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1045 if (store_Opcode() != st->Opcode()) 1046 return NULL; 1047 return st->in(MemNode::ValueIn); 1048 } 1049 1050 // A load from a freshly-created object always returns zero. 1051 // (This can happen after LoadNode::Ideal resets the load's memory input 1052 // to find_captured_store, which returned InitializeNode::zero_memory.) 1053 if (st->is_Proj() && st->in(0)->is_Allocate() && 1054 (st->in(0) == ld_alloc) && 1055 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1056 // return a zero value for the load's basic type 1057 // (This is one of the few places where a generic PhaseTransform 1058 // can create new nodes. Think of it as lazily manifesting 1059 // virtually pre-existing constants.) 1060 return phase->zerocon(memory_type()); 1061 } 1062 1063 // A load from an initialization barrier can match a captured store. 1064 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1065 InitializeNode* init = st->in(0)->as_Initialize(); 1066 AllocateNode* alloc = init->allocation(); 1067 if ((alloc != NULL) && (alloc == ld_alloc)) { 1068 // examine a captured store value 1069 st = init->find_captured_store(ld_off, memory_size(), phase); 1070 if (st != NULL) 1071 continue; // take one more trip around 1072 } 1073 } 1074 1075 // Load boxed value from result of valueOf() call is input parameter. 1076 if (this->is_Load() && ld_adr->is_AddP() && 1077 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1078 intptr_t ignore = 0; 1079 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1080 if (base != NULL && base->is_Proj() && 1081 base->as_Proj()->_con == TypeFunc::Parms && 1082 base->in(0)->is_CallStaticJava() && 1083 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1084 return base->in(0)->in(TypeFunc::Parms); 1085 } 1086 } 1087 1088 break; 1089 } 1090 1091 return NULL; 1092 } 1093 1094 //----------------------is_instance_field_load_with_local_phi------------------ 1095 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1096 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1097 in(Address)->is_AddP() ) { 1098 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1099 // Only instances and boxed values. 1100 if( t_oop != NULL && 1101 (t_oop->is_ptr_to_boxed_value() || 1102 t_oop->is_known_instance_field()) && 1103 t_oop->offset() != Type::OffsetBot && 1104 t_oop->offset() != Type::OffsetTop) { 1105 return true; 1106 } 1107 } 1108 return false; 1109 } 1110 1111 //------------------------------Identity--------------------------------------- 1112 // Loads are identity if previous store is to same address 1113 Node *LoadNode::Identity( PhaseTransform *phase ) { 1114 // If the previous store-maker is the right kind of Store, and the store is 1115 // to the same address, then we are equal to the value stored. 1116 Node* mem = in(Memory); 1117 Node* value = can_see_stored_value(mem, phase); 1118 if( value ) { 1119 // byte, short & char stores truncate naturally. 1120 // A load has to load the truncated value which requires 1121 // some sort of masking operation and that requires an 1122 // Ideal call instead of an Identity call. 1123 if (memory_size() < BytesPerInt) { 1124 // If the input to the store does not fit with the load's result type, 1125 // it must be truncated via an Ideal call. 1126 if (!phase->type(value)->higher_equal(phase->type(this))) 1127 return this; 1128 } 1129 // (This works even when value is a Con, but LoadNode::Value 1130 // usually runs first, producing the singleton type of the Con.) 1131 return value; 1132 } 1133 1134 // Search for an existing data phi which was generated before for the same 1135 // instance's field to avoid infinite generation of phis in a loop. 1136 Node *region = mem->in(0); 1137 if (is_instance_field_load_with_local_phi(region)) { 1138 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1139 int this_index = phase->C->get_alias_index(addr_t); 1140 int this_offset = addr_t->offset(); 1141 int this_iid = addr_t->instance_id(); 1142 if (!addr_t->is_known_instance() && 1143 addr_t->is_ptr_to_boxed_value()) { 1144 // Use _idx of address base (could be Phi node) for boxed values. 1145 intptr_t ignore = 0; 1146 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1147 this_iid = base->_idx; 1148 } 1149 const Type* this_type = bottom_type(); 1150 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1151 Node* phi = region->fast_out(i); 1152 if (phi->is_Phi() && phi != mem && 1153 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) { 1154 return phi; 1155 } 1156 } 1157 } 1158 1159 return this; 1160 } 1161 1162 // We're loading from an object which has autobox behaviour. 1163 // If this object is result of a valueOf call we'll have a phi 1164 // merging a newly allocated object and a load from the cache. 1165 // We want to replace this load with the original incoming 1166 // argument to the valueOf call. 1167 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1168 assert(phase->C->eliminate_boxing(), "sanity"); 1169 intptr_t ignore = 0; 1170 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1171 if ((base == NULL) || base->is_Phi()) { 1172 // Push the loads from the phi that comes from valueOf up 1173 // through it to allow elimination of the loads and the recovery 1174 // of the original value. It is done in split_through_phi(). 1175 return NULL; 1176 } else if (base->is_Load() || 1177 base->is_DecodeN() && base->in(1)->is_Load()) { 1178 // Eliminate the load of boxed value for integer types from the cache 1179 // array by deriving the value from the index into the array. 1180 // Capture the offset of the load and then reverse the computation. 1181 1182 // Get LoadN node which loads a boxing object from 'cache' array. 1183 if (base->is_DecodeN()) { 1184 base = base->in(1); 1185 } 1186 if (!base->in(Address)->is_AddP()) { 1187 return NULL; // Complex address 1188 } 1189 AddPNode* address = base->in(Address)->as_AddP(); 1190 Node* cache_base = address->in(AddPNode::Base); 1191 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1192 // Get ConP node which is static 'cache' field. 1193 cache_base = cache_base->in(1); 1194 } 1195 if ((cache_base != NULL) && cache_base->is_Con()) { 1196 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1197 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1198 Node* elements[4]; 1199 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1200 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1201 if ((count > 0) && elements[0]->is_Con() && 1202 ((count == 1) || 1203 (count == 2) && elements[1]->Opcode() == Op_LShiftX && 1204 elements[1]->in(2) == phase->intcon(shift))) { 1205 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1206 // Fetch the box object cache[0] at the base of the array and get its value 1207 ciInstance* box = array->obj_at(0)->as_instance(); 1208 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1209 assert(ik->is_box_klass(), "sanity"); 1210 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1211 if (ik->nof_nonstatic_fields() == 1) { 1212 // This should be true nonstatic_field_at requires calling 1213 // nof_nonstatic_fields so check it anyway 1214 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1215 BasicType bt = c.basic_type(); 1216 // Only integer types have boxing cache. 1217 assert(bt == T_BOOLEAN || bt == T_CHAR || 1218 bt == T_BYTE || bt == T_SHORT || 1219 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt))); 1220 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1221 if (cache_low != (int)cache_low) { 1222 return NULL; // should not happen since cache is array indexed by value 1223 } 1224 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1225 if (offset != (int)offset) { 1226 return NULL; // should not happen since cache is array indexed by value 1227 } 1228 // Add up all the offsets making of the address of the load 1229 Node* result = elements[0]; 1230 for (int i = 1; i < count; i++) { 1231 result = phase->transform(new AddXNode(result, elements[i])); 1232 } 1233 // Remove the constant offset from the address and then 1234 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset))); 1235 // remove the scaling of the offset to recover the original index. 1236 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1237 // Peel the shift off directly but wrap it in a dummy node 1238 // since Ideal can't return existing nodes 1239 result = new RShiftXNode(result->in(1), phase->intcon(0)); 1240 } else if (result->is_Add() && result->in(2)->is_Con() && 1241 result->in(1)->Opcode() == Op_LShiftX && 1242 result->in(1)->in(2) == phase->intcon(shift)) { 1243 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1244 // but for boxing cache access we know that X<<Z will not overflow 1245 // (there is range check) so we do this optimizatrion by hand here. 1246 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift)); 1247 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con)); 1248 } else { 1249 result = new RShiftXNode(result, phase->intcon(shift)); 1250 } 1251 #ifdef _LP64 1252 if (bt != T_LONG) { 1253 result = new ConvL2INode(phase->transform(result)); 1254 } 1255 #else 1256 if (bt == T_LONG) { 1257 result = new ConvI2LNode(phase->transform(result)); 1258 } 1259 #endif 1260 return result; 1261 } 1262 } 1263 } 1264 } 1265 } 1266 return NULL; 1267 } 1268 1269 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1270 Node* region = phi->in(0); 1271 if (region == NULL) { 1272 return false; // Wait stable graph 1273 } 1274 uint cnt = phi->req(); 1275 for (uint i = 1; i < cnt; i++) { 1276 Node* rc = region->in(i); 1277 if (rc == NULL || phase->type(rc) == Type::TOP) 1278 return false; // Wait stable graph 1279 Node* in = phi->in(i); 1280 if (in == NULL || phase->type(in) == Type::TOP) 1281 return false; // Wait stable graph 1282 } 1283 return true; 1284 } 1285 //------------------------------split_through_phi------------------------------ 1286 // Split instance or boxed field load through Phi. 1287 Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1288 Node* mem = in(Memory); 1289 Node* address = in(Address); 1290 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1291 1292 assert((t_oop != NULL) && 1293 (t_oop->is_known_instance_field() || 1294 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1295 1296 Compile* C = phase->C; 1297 intptr_t ignore = 0; 1298 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1299 bool base_is_phi = (base != NULL) && base->is_Phi(); 1300 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1301 (base != NULL) && (base == address->in(AddPNode::Base)) && 1302 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1303 1304 if (!((mem->is_Phi() || base_is_phi) && 1305 (load_boxed_values || t_oop->is_known_instance_field()))) { 1306 return NULL; // memory is not Phi 1307 } 1308 1309 if (mem->is_Phi()) { 1310 if (!stable_phi(mem->as_Phi(), phase)) { 1311 return NULL; // Wait stable graph 1312 } 1313 uint cnt = mem->req(); 1314 // Check for loop invariant memory. 1315 if (cnt == 3) { 1316 for (uint i = 1; i < cnt; i++) { 1317 Node* in = mem->in(i); 1318 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1319 if (m == mem) { 1320 set_req(Memory, mem->in(cnt - i)); 1321 return this; // made change 1322 } 1323 } 1324 } 1325 } 1326 if (base_is_phi) { 1327 if (!stable_phi(base->as_Phi(), phase)) { 1328 return NULL; // Wait stable graph 1329 } 1330 uint cnt = base->req(); 1331 // Check for loop invariant memory. 1332 if (cnt == 3) { 1333 for (uint i = 1; i < cnt; i++) { 1334 if (base->in(i) == base) { 1335 return NULL; // Wait stable graph 1336 } 1337 } 1338 } 1339 } 1340 1341 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0)); 1342 1343 // Split through Phi (see original code in loopopts.cpp). 1344 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1345 1346 // Do nothing here if Identity will find a value 1347 // (to avoid infinite chain of value phis generation). 1348 if (!phase->eqv(this, this->Identity(phase))) 1349 return NULL; 1350 1351 // Select Region to split through. 1352 Node* region; 1353 if (!base_is_phi) { 1354 assert(mem->is_Phi(), "sanity"); 1355 region = mem->in(0); 1356 // Skip if the region dominates some control edge of the address. 1357 if (!MemNode::all_controls_dominate(address, region)) 1358 return NULL; 1359 } else if (!mem->is_Phi()) { 1360 assert(base_is_phi, "sanity"); 1361 region = base->in(0); 1362 // Skip if the region dominates some control edge of the memory. 1363 if (!MemNode::all_controls_dominate(mem, region)) 1364 return NULL; 1365 } else if (base->in(0) != mem->in(0)) { 1366 assert(base_is_phi && mem->is_Phi(), "sanity"); 1367 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1368 region = base->in(0); 1369 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1370 region = mem->in(0); 1371 } else { 1372 return NULL; // complex graph 1373 } 1374 } else { 1375 assert(base->in(0) == mem->in(0), "sanity"); 1376 region = mem->in(0); 1377 } 1378 1379 const Type* this_type = this->bottom_type(); 1380 int this_index = C->get_alias_index(t_oop); 1381 int this_offset = t_oop->offset(); 1382 int this_iid = t_oop->instance_id(); 1383 if (!t_oop->is_known_instance() && load_boxed_values) { 1384 // Use _idx of address base for boxed values. 1385 this_iid = base->_idx; 1386 } 1387 PhaseIterGVN* igvn = phase->is_IterGVN(); 1388 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset); 1389 for (uint i = 1; i < region->req(); i++) { 1390 Node* x; 1391 Node* the_clone = NULL; 1392 if (region->in(i) == C->top()) { 1393 x = C->top(); // Dead path? Use a dead data op 1394 } else { 1395 x = this->clone(); // Else clone up the data op 1396 the_clone = x; // Remember for possible deletion. 1397 // Alter data node to use pre-phi inputs 1398 if (this->in(0) == region) { 1399 x->set_req(0, region->in(i)); 1400 } else { 1401 x->set_req(0, NULL); 1402 } 1403 if (mem->is_Phi() && (mem->in(0) == region)) { 1404 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1405 } 1406 if (address->is_Phi() && address->in(0) == region) { 1407 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1408 } 1409 if (base_is_phi && (base->in(0) == region)) { 1410 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1411 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1412 x->set_req(Address, adr_x); 1413 } 1414 } 1415 // Check for a 'win' on some paths 1416 const Type *t = x->Value(igvn); 1417 1418 bool singleton = t->singleton(); 1419 1420 // See comments in PhaseIdealLoop::split_thru_phi(). 1421 if (singleton && t == Type::TOP) { 1422 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1423 } 1424 1425 if (singleton) { 1426 x = igvn->makecon(t); 1427 } else { 1428 // We now call Identity to try to simplify the cloned node. 1429 // Note that some Identity methods call phase->type(this). 1430 // Make sure that the type array is big enough for 1431 // our new node, even though we may throw the node away. 1432 // (This tweaking with igvn only works because x is a new node.) 1433 igvn->set_type(x, t); 1434 // If x is a TypeNode, capture any more-precise type permanently into Node 1435 // otherwise it will be not updated during igvn->transform since 1436 // igvn->type(x) is set to x->Value() already. 1437 x->raise_bottom_type(t); 1438 Node *y = x->Identity(igvn); 1439 if (y != x) { 1440 x = y; 1441 } else { 1442 y = igvn->hash_find_insert(x); 1443 if (y) { 1444 x = y; 1445 } else { 1446 // Else x is a new node we are keeping 1447 // We do not need register_new_node_with_optimizer 1448 // because set_type has already been called. 1449 igvn->_worklist.push(x); 1450 } 1451 } 1452 } 1453 if (x != the_clone && the_clone != NULL) { 1454 igvn->remove_dead_node(the_clone); 1455 } 1456 phi->set_req(i, x); 1457 } 1458 // Record Phi 1459 igvn->register_new_node_with_optimizer(phi); 1460 return phi; 1461 } 1462 1463 //------------------------------Ideal------------------------------------------ 1464 // If the load is from Field memory and the pointer is non-null, we can 1465 // zero out the control input. 1466 // If the offset is constant and the base is an object allocation, 1467 // try to hook me up to the exact initializing store. 1468 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1469 Node* p = MemNode::Ideal_common(phase, can_reshape); 1470 if (p) return (p == NodeSentinel) ? NULL : p; 1471 1472 Node* ctrl = in(MemNode::Control); 1473 Node* address = in(MemNode::Address); 1474 bool progress = false; 1475 1476 // Skip up past a SafePoint control. Cannot do this for Stores because 1477 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1478 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1479 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1480 ctrl = ctrl->in(0); 1481 set_req(MemNode::Control,ctrl); 1482 progress = true; 1483 } 1484 1485 intptr_t ignore = 0; 1486 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1487 if (base != NULL 1488 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1489 // Check for useless control edge in some common special cases 1490 if (in(MemNode::Control) != NULL 1491 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1492 && all_controls_dominate(base, phase->C->start())) { 1493 // A method-invariant, non-null address (constant or 'this' argument). 1494 set_req(MemNode::Control, NULL); 1495 progress = true; 1496 } 1497 } 1498 1499 Node* mem = in(MemNode::Memory); 1500 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1501 1502 if (can_reshape && (addr_t != NULL)) { 1503 // try to optimize our memory input 1504 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1505 if (opt_mem != mem) { 1506 set_req(MemNode::Memory, opt_mem); 1507 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1508 return this; 1509 } 1510 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1511 if ((t_oop != NULL) && 1512 (t_oop->is_known_instance_field() || 1513 t_oop->is_ptr_to_boxed_value())) { 1514 PhaseIterGVN *igvn = phase->is_IterGVN(); 1515 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1516 // Delay this transformation until memory Phi is processed. 1517 phase->is_IterGVN()->_worklist.push(this); 1518 return NULL; 1519 } 1520 // Split instance field load through Phi. 1521 Node* result = split_through_phi(phase); 1522 if (result != NULL) return result; 1523 1524 if (t_oop->is_ptr_to_boxed_value()) { 1525 Node* result = eliminate_autobox(phase); 1526 if (result != NULL) return result; 1527 } 1528 } 1529 } 1530 1531 // Check for prior store with a different base or offset; make Load 1532 // independent. Skip through any number of them. Bail out if the stores 1533 // are in an endless dead cycle and report no progress. This is a key 1534 // transform for Reflection. However, if after skipping through the Stores 1535 // we can't then fold up against a prior store do NOT do the transform as 1536 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1537 // array memory alive twice: once for the hoisted Load and again after the 1538 // bypassed Store. This situation only works if EVERYBODY who does 1539 // anti-dependence work knows how to bypass. I.e. we need all 1540 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1541 // the alias index stuff. So instead, peek through Stores and IFF we can 1542 // fold up, do so. 1543 Node* prev_mem = find_previous_store(phase); 1544 // Steps (a), (b): Walk past independent stores to find an exact match. 1545 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1546 // (c) See if we can fold up on the spot, but don't fold up here. 1547 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1548 // just return a prior value, which is done by Identity calls. 1549 if (can_see_stored_value(prev_mem, phase)) { 1550 // Make ready for step (d): 1551 set_req(MemNode::Memory, prev_mem); 1552 return this; 1553 } 1554 } 1555 1556 return progress ? this : NULL; 1557 } 1558 1559 // Helper to recognize certain Klass fields which are invariant across 1560 // some group of array types (e.g., int[] or all T[] where T < Object). 1561 const Type* 1562 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1563 ciKlass* klass) const { 1564 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1565 // The field is Klass::_modifier_flags. Return its (constant) value. 1566 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1567 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1568 return TypeInt::make(klass->modifier_flags()); 1569 } 1570 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1571 // The field is Klass::_access_flags. Return its (constant) value. 1572 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1573 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1574 return TypeInt::make(klass->access_flags()); 1575 } 1576 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1577 // The field is Klass::_layout_helper. Return its constant value if known. 1578 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1579 return TypeInt::make(klass->layout_helper()); 1580 } 1581 1582 // No match. 1583 return NULL; 1584 } 1585 1586 // Try to constant-fold a stable array element. 1587 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) { 1588 assert(ary->const_oop(), "array should be constant"); 1589 assert(ary->is_stable(), "array should be stable"); 1590 1591 // Decode the results of GraphKit::array_element_address. 1592 ciArray* aobj = ary->const_oop()->as_array(); 1593 ciConstant con = aobj->element_value_by_offset(off); 1594 1595 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) { 1596 const Type* con_type = Type::make_from_constant(con); 1597 if (con_type != NULL) { 1598 if (con_type->isa_aryptr()) { 1599 // Join with the array element type, in case it is also stable. 1600 int dim = ary->stable_dimension(); 1601 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1); 1602 } 1603 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) { 1604 con_type = con_type->make_narrowoop(); 1605 } 1606 #ifndef PRODUCT 1607 if (TraceIterativeGVN) { 1608 tty->print("FoldStableValues: array element [off=%d]: con_type=", off); 1609 con_type->dump(); tty->cr(); 1610 } 1611 #endif //PRODUCT 1612 return con_type; 1613 } 1614 } 1615 return NULL; 1616 } 1617 1618 //------------------------------Value----------------------------------------- 1619 const Type *LoadNode::Value( PhaseTransform *phase ) const { 1620 // Either input is TOP ==> the result is TOP 1621 Node* mem = in(MemNode::Memory); 1622 const Type *t1 = phase->type(mem); 1623 if (t1 == Type::TOP) return Type::TOP; 1624 Node* adr = in(MemNode::Address); 1625 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1626 if (tp == NULL || tp->empty()) return Type::TOP; 1627 int off = tp->offset(); 1628 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1629 Compile* C = phase->C; 1630 1631 // Try to guess loaded type from pointer type 1632 if (tp->isa_aryptr()) { 1633 const TypeAryPtr* ary = tp->is_aryptr(); 1634 const Type* t = ary->elem(); 1635 1636 // Determine whether the reference is beyond the header or not, by comparing 1637 // the offset against the offset of the start of the array's data. 1638 // Different array types begin at slightly different offsets (12 vs. 16). 1639 // We choose T_BYTE as an example base type that is least restrictive 1640 // as to alignment, which will therefore produce the smallest 1641 // possible base offset. 1642 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1643 const bool off_beyond_header = ((uint)off >= (uint)min_base_off); 1644 1645 // Try to constant-fold a stable array element. 1646 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) { 1647 // Make sure the reference is not into the header and the offset is constant 1648 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1649 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type()); 1650 if (con_type != NULL) { 1651 return con_type; 1652 } 1653 } 1654 } 1655 1656 // Don't do this for integer types. There is only potential profit if 1657 // the element type t is lower than _type; that is, for int types, if _type is 1658 // more restrictive than t. This only happens here if one is short and the other 1659 // char (both 16 bits), and in those cases we've made an intentional decision 1660 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1661 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1662 // 1663 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1664 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1665 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1666 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1667 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1668 // In fact, that could have been the original type of p1, and p1 could have 1669 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1670 // expression (LShiftL quux 3) independently optimized to the constant 8. 1671 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1672 && (_type->isa_vect() == NULL) 1673 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1674 // t might actually be lower than _type, if _type is a unique 1675 // concrete subclass of abstract class t. 1676 if (off_beyond_header) { // is the offset beyond the header? 1677 const Type* jt = t->join_speculative(_type); 1678 // In any case, do not allow the join, per se, to empty out the type. 1679 if (jt->empty() && !t->empty()) { 1680 // This can happen if a interface-typed array narrows to a class type. 1681 jt = _type; 1682 } 1683 #ifdef ASSERT 1684 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1685 // The pointers in the autobox arrays are always non-null 1686 Node* base = adr->in(AddPNode::Base); 1687 if ((base != NULL) && base->is_DecodeN()) { 1688 // Get LoadN node which loads IntegerCache.cache field 1689 base = base->in(1); 1690 } 1691 if ((base != NULL) && base->is_Con()) { 1692 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1693 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1694 // It could be narrow oop 1695 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1696 } 1697 } 1698 } 1699 #endif 1700 return jt; 1701 } 1702 } 1703 } else if (tp->base() == Type::InstPtr) { 1704 ciEnv* env = C->env(); 1705 const TypeInstPtr* tinst = tp->is_instptr(); 1706 ciKlass* klass = tinst->klass(); 1707 assert( off != Type::OffsetBot || 1708 // arrays can be cast to Objects 1709 tp->is_oopptr()->klass()->is_java_lang_Object() || 1710 // unsafe field access may not have a constant offset 1711 C->has_unsafe_access(), 1712 "Field accesses must be precise" ); 1713 // For oop loads, we expect the _type to be precise 1714 if (klass == env->String_klass() && 1715 adr->is_AddP() && off != Type::OffsetBot) { 1716 // For constant Strings treat the final fields as compile time constants. 1717 Node* base = adr->in(AddPNode::Base); 1718 const TypeOopPtr* t = phase->type(base)->isa_oopptr(); 1719 if (t != NULL && t->singleton()) { 1720 ciField* field = env->String_klass()->get_field_by_offset(off, false); 1721 if (field != NULL && field->is_final()) { 1722 ciObject* string = t->const_oop(); 1723 ciConstant constant = string->as_instance()->field_value(field); 1724 if (constant.basic_type() == T_INT) { 1725 return TypeInt::make(constant.as_int()); 1726 } else if (constant.basic_type() == T_ARRAY) { 1727 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1728 return TypeNarrowOop::make_from_constant(constant.as_object(), true); 1729 } else { 1730 return TypeOopPtr::make_from_constant(constant.as_object(), true); 1731 } 1732 } 1733 } 1734 } 1735 } 1736 // Optimizations for constant objects 1737 ciObject* const_oop = tinst->const_oop(); 1738 if (const_oop != NULL) { 1739 // For constant Boxed value treat the target field as a compile time constant. 1740 if (tinst->is_ptr_to_boxed_value()) { 1741 return tinst->get_const_boxed_value(); 1742 } else 1743 // For constant CallSites treat the target field as a compile time constant. 1744 if (const_oop->is_call_site()) { 1745 ciCallSite* call_site = const_oop->as_call_site(); 1746 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false); 1747 if (field != NULL && field->is_call_site_target()) { 1748 ciMethodHandle* target = call_site->get_target(); 1749 if (target != NULL) { // just in case 1750 ciConstant constant(T_OBJECT, target); 1751 const Type* t; 1752 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1753 t = TypeNarrowOop::make_from_constant(constant.as_object(), true); 1754 } else { 1755 t = TypeOopPtr::make_from_constant(constant.as_object(), true); 1756 } 1757 // Add a dependence for invalidation of the optimization. 1758 if (!call_site->is_constant_call_site()) { 1759 C->dependencies()->assert_call_site_target_value(call_site, target); 1760 } 1761 return t; 1762 } 1763 } 1764 } 1765 } 1766 } else if (tp->base() == Type::KlassPtr) { 1767 assert( off != Type::OffsetBot || 1768 // arrays can be cast to Objects 1769 tp->is_klassptr()->klass()->is_java_lang_Object() || 1770 // also allow array-loading from the primary supertype 1771 // array during subtype checks 1772 Opcode() == Op_LoadKlass, 1773 "Field accesses must be precise" ); 1774 // For klass/static loads, we expect the _type to be precise 1775 } 1776 1777 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1778 if (tkls != NULL && !StressReflectiveCode) { 1779 ciKlass* klass = tkls->klass(); 1780 if (klass->is_loaded() && tkls->klass_is_exact()) { 1781 // We are loading a field from a Klass metaobject whose identity 1782 // is known at compile time (the type is "exact" or "precise"). 1783 // Check for fields we know are maintained as constants by the VM. 1784 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1785 // The field is Klass::_super_check_offset. Return its (constant) value. 1786 // (Folds up type checking code.) 1787 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1788 return TypeInt::make(klass->super_check_offset()); 1789 } 1790 // Compute index into primary_supers array 1791 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1792 // Check for overflowing; use unsigned compare to handle the negative case. 1793 if( depth < ciKlass::primary_super_limit() ) { 1794 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1795 // (Folds up type checking code.) 1796 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1797 ciKlass *ss = klass->super_of_depth(depth); 1798 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1799 } 1800 const Type* aift = load_array_final_field(tkls, klass); 1801 if (aift != NULL) return aift; 1802 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset()) 1803 && klass->is_array_klass()) { 1804 // The field is ArrayKlass::_component_mirror. Return its (constant) value. 1805 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.) 1806 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror"); 1807 return TypeInstPtr::make(klass->as_array_klass()->component_mirror()); 1808 } 1809 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1810 // The field is Klass::_java_mirror. Return its (constant) value. 1811 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1812 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1813 return TypeInstPtr::make(klass->java_mirror()); 1814 } 1815 } 1816 1817 // We can still check if we are loading from the primary_supers array at a 1818 // shallow enough depth. Even though the klass is not exact, entries less 1819 // than or equal to its super depth are correct. 1820 if (klass->is_loaded() ) { 1821 ciType *inner = klass; 1822 while( inner->is_obj_array_klass() ) 1823 inner = inner->as_obj_array_klass()->base_element_type(); 1824 if( inner->is_instance_klass() && 1825 !inner->as_instance_klass()->flags().is_interface() ) { 1826 // Compute index into primary_supers array 1827 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1828 // Check for overflowing; use unsigned compare to handle the negative case. 1829 if( depth < ciKlass::primary_super_limit() && 1830 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1831 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1832 // (Folds up type checking code.) 1833 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1834 ciKlass *ss = klass->super_of_depth(depth); 1835 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1836 } 1837 } 1838 } 1839 1840 // If the type is enough to determine that the thing is not an array, 1841 // we can give the layout_helper a positive interval type. 1842 // This will help short-circuit some reflective code. 1843 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1844 && !klass->is_array_klass() // not directly typed as an array 1845 && !klass->is_interface() // specifically not Serializable & Cloneable 1846 && !klass->is_java_lang_Object() // not the supertype of all T[] 1847 ) { 1848 // Note: When interfaces are reliable, we can narrow the interface 1849 // test to (klass != Serializable && klass != Cloneable). 1850 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1851 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1852 // The key property of this type is that it folds up tests 1853 // for array-ness, since it proves that the layout_helper is positive. 1854 // Thus, a generic value like the basic object layout helper works fine. 1855 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1856 } 1857 } 1858 1859 // If we are loading from a freshly-allocated object, produce a zero, 1860 // if the load is provably beyond the header of the object. 1861 // (Also allow a variable load from a fresh array to produce zero.) 1862 const TypeOopPtr *tinst = tp->isa_oopptr(); 1863 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1864 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 1865 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 1866 Node* value = can_see_stored_value(mem,phase); 1867 if (value != NULL && value->is_Con()) { 1868 assert(value->bottom_type()->higher_equal(_type),"sanity"); 1869 return value->bottom_type(); 1870 } 1871 } 1872 1873 if (is_instance) { 1874 // If we have an instance type and our memory input is the 1875 // programs's initial memory state, there is no matching store, 1876 // so just return a zero of the appropriate type 1877 Node *mem = in(MemNode::Memory); 1878 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1879 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1880 return Type::get_zero_type(_type->basic_type()); 1881 } 1882 } 1883 return _type; 1884 } 1885 1886 //------------------------------match_edge------------------------------------- 1887 // Do we Match on this edge index or not? Match only the address. 1888 uint LoadNode::match_edge(uint idx) const { 1889 return idx == MemNode::Address; 1890 } 1891 1892 //--------------------------LoadBNode::Ideal-------------------------------------- 1893 // 1894 // If the previous store is to the same address as this load, 1895 // and the value stored was larger than a byte, replace this load 1896 // with the value stored truncated to a byte. If no truncation is 1897 // needed, the replacement is done in LoadNode::Identity(). 1898 // 1899 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1900 Node* mem = in(MemNode::Memory); 1901 Node* value = can_see_stored_value(mem,phase); 1902 if( value && !phase->type(value)->higher_equal( _type ) ) { 1903 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) ); 1904 return new RShiftINode(result, phase->intcon(24)); 1905 } 1906 // Identity call will handle the case where truncation is not needed. 1907 return LoadNode::Ideal(phase, can_reshape); 1908 } 1909 1910 const Type* LoadBNode::Value(PhaseTransform *phase) const { 1911 Node* mem = in(MemNode::Memory); 1912 Node* value = can_see_stored_value(mem,phase); 1913 if (value != NULL && value->is_Con() && 1914 !value->bottom_type()->higher_equal(_type)) { 1915 // If the input to the store does not fit with the load's result type, 1916 // it must be truncated. We can't delay until Ideal call since 1917 // a singleton Value is needed for split_thru_phi optimization. 1918 int con = value->get_int(); 1919 return TypeInt::make((con << 24) >> 24); 1920 } 1921 return LoadNode::Value(phase); 1922 } 1923 1924 //--------------------------LoadUBNode::Ideal------------------------------------- 1925 // 1926 // If the previous store is to the same address as this load, 1927 // and the value stored was larger than a byte, replace this load 1928 // with the value stored truncated to a byte. If no truncation is 1929 // needed, the replacement is done in LoadNode::Identity(). 1930 // 1931 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 1932 Node* mem = in(MemNode::Memory); 1933 Node* value = can_see_stored_value(mem, phase); 1934 if (value && !phase->type(value)->higher_equal(_type)) 1935 return new AndINode(value, phase->intcon(0xFF)); 1936 // Identity call will handle the case where truncation is not needed. 1937 return LoadNode::Ideal(phase, can_reshape); 1938 } 1939 1940 const Type* LoadUBNode::Value(PhaseTransform *phase) const { 1941 Node* mem = in(MemNode::Memory); 1942 Node* value = can_see_stored_value(mem,phase); 1943 if (value != NULL && value->is_Con() && 1944 !value->bottom_type()->higher_equal(_type)) { 1945 // If the input to the store does not fit with the load's result type, 1946 // it must be truncated. We can't delay until Ideal call since 1947 // a singleton Value is needed for split_thru_phi optimization. 1948 int con = value->get_int(); 1949 return TypeInt::make(con & 0xFF); 1950 } 1951 return LoadNode::Value(phase); 1952 } 1953 1954 //--------------------------LoadUSNode::Ideal------------------------------------- 1955 // 1956 // If the previous store is to the same address as this load, 1957 // and the value stored was larger than a char, replace this load 1958 // with the value stored truncated to a char. If no truncation is 1959 // needed, the replacement is done in LoadNode::Identity(). 1960 // 1961 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1962 Node* mem = in(MemNode::Memory); 1963 Node* value = can_see_stored_value(mem,phase); 1964 if( value && !phase->type(value)->higher_equal( _type ) ) 1965 return new AndINode(value,phase->intcon(0xFFFF)); 1966 // Identity call will handle the case where truncation is not needed. 1967 return LoadNode::Ideal(phase, can_reshape); 1968 } 1969 1970 const Type* LoadUSNode::Value(PhaseTransform *phase) const { 1971 Node* mem = in(MemNode::Memory); 1972 Node* value = can_see_stored_value(mem,phase); 1973 if (value != NULL && value->is_Con() && 1974 !value->bottom_type()->higher_equal(_type)) { 1975 // If the input to the store does not fit with the load's result type, 1976 // it must be truncated. We can't delay until Ideal call since 1977 // a singleton Value is needed for split_thru_phi optimization. 1978 int con = value->get_int(); 1979 return TypeInt::make(con & 0xFFFF); 1980 } 1981 return LoadNode::Value(phase); 1982 } 1983 1984 //--------------------------LoadSNode::Ideal-------------------------------------- 1985 // 1986 // If the previous store is to the same address as this load, 1987 // and the value stored was larger than a short, replace this load 1988 // with the value stored truncated to a short. If no truncation is 1989 // needed, the replacement is done in LoadNode::Identity(). 1990 // 1991 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1992 Node* mem = in(MemNode::Memory); 1993 Node* value = can_see_stored_value(mem,phase); 1994 if( value && !phase->type(value)->higher_equal( _type ) ) { 1995 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) ); 1996 return new RShiftINode(result, phase->intcon(16)); 1997 } 1998 // Identity call will handle the case where truncation is not needed. 1999 return LoadNode::Ideal(phase, can_reshape); 2000 } 2001 2002 const Type* LoadSNode::Value(PhaseTransform *phase) const { 2003 Node* mem = in(MemNode::Memory); 2004 Node* value = can_see_stored_value(mem,phase); 2005 if (value != NULL && value->is_Con() && 2006 !value->bottom_type()->higher_equal(_type)) { 2007 // If the input to the store does not fit with the load's result type, 2008 // it must be truncated. We can't delay until Ideal call since 2009 // a singleton Value is needed for split_thru_phi optimization. 2010 int con = value->get_int(); 2011 return TypeInt::make((con << 16) >> 16); 2012 } 2013 return LoadNode::Value(phase); 2014 } 2015 2016 //============================================================================= 2017 //----------------------------LoadKlassNode::make------------------------------ 2018 // Polymorphic factory method: 2019 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) { 2020 Node *ctl = NULL; 2021 // sanity check the alias category against the created node type 2022 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2023 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2024 #ifdef _LP64 2025 if (adr_type->is_ptr_to_narrowklass()) { 2026 assert(UseCompressedClassPointers, "no compressed klasses"); 2027 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2028 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2029 } 2030 #endif 2031 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2032 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2033 } 2034 2035 //------------------------------Value------------------------------------------ 2036 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { 2037 return klass_value_common(phase); 2038 } 2039 2040 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const { 2041 // Either input is TOP ==> the result is TOP 2042 const Type *t1 = phase->type( in(MemNode::Memory) ); 2043 if (t1 == Type::TOP) return Type::TOP; 2044 Node *adr = in(MemNode::Address); 2045 const Type *t2 = phase->type( adr ); 2046 if (t2 == Type::TOP) return Type::TOP; 2047 const TypePtr *tp = t2->is_ptr(); 2048 if (TypePtr::above_centerline(tp->ptr()) || 2049 tp->ptr() == TypePtr::Null) return Type::TOP; 2050 2051 // Return a more precise klass, if possible 2052 const TypeInstPtr *tinst = tp->isa_instptr(); 2053 if (tinst != NULL) { 2054 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2055 int offset = tinst->offset(); 2056 if (ik == phase->C->env()->Class_klass() 2057 && (offset == java_lang_Class::klass_offset_in_bytes() || 2058 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2059 // We are loading a special hidden field from a Class mirror object, 2060 // the field which points to the VM's Klass metaobject. 2061 ciType* t = tinst->java_mirror_type(); 2062 // java_mirror_type returns non-null for compile-time Class constants. 2063 if (t != NULL) { 2064 // constant oop => constant klass 2065 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2066 if (t->is_void()) { 2067 // We cannot create a void array. Since void is a primitive type return null 2068 // klass. Users of this result need to do a null check on the returned klass. 2069 return TypePtr::NULL_PTR; 2070 } 2071 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2072 } 2073 if (!t->is_klass()) { 2074 // a primitive Class (e.g., int.class) has NULL for a klass field 2075 return TypePtr::NULL_PTR; 2076 } 2077 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2078 return TypeKlassPtr::make(t->as_klass()); 2079 } 2080 // non-constant mirror, so we can't tell what's going on 2081 } 2082 if( !ik->is_loaded() ) 2083 return _type; // Bail out if not loaded 2084 if (offset == oopDesc::klass_offset_in_bytes()) { 2085 if (tinst->klass_is_exact()) { 2086 return TypeKlassPtr::make(ik); 2087 } 2088 // See if we can become precise: no subklasses and no interface 2089 // (Note: We need to support verified interfaces.) 2090 if (!ik->is_interface() && !ik->has_subklass()) { 2091 //assert(!UseExactTypes, "this code should be useless with exact types"); 2092 // Add a dependence; if any subclass added we need to recompile 2093 if (!ik->is_final()) { 2094 // %%% should use stronger assert_unique_concrete_subtype instead 2095 phase->C->dependencies()->assert_leaf_type(ik); 2096 } 2097 // Return precise klass 2098 return TypeKlassPtr::make(ik); 2099 } 2100 2101 // Return root of possible klass 2102 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2103 } 2104 } 2105 2106 // Check for loading klass from an array 2107 const TypeAryPtr *tary = tp->isa_aryptr(); 2108 if( tary != NULL ) { 2109 ciKlass *tary_klass = tary->klass(); 2110 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2111 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2112 if (tary->klass_is_exact()) { 2113 return TypeKlassPtr::make(tary_klass); 2114 } 2115 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2116 // If the klass is an object array, we defer the question to the 2117 // array component klass. 2118 if( ak->is_obj_array_klass() ) { 2119 assert( ak->is_loaded(), "" ); 2120 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2121 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2122 ciInstanceKlass* ik = base_k->as_instance_klass(); 2123 // See if we can become precise: no subklasses and no interface 2124 if (!ik->is_interface() && !ik->has_subklass()) { 2125 //assert(!UseExactTypes, "this code should be useless with exact types"); 2126 // Add a dependence; if any subclass added we need to recompile 2127 if (!ik->is_final()) { 2128 phase->C->dependencies()->assert_leaf_type(ik); 2129 } 2130 // Return precise array klass 2131 return TypeKlassPtr::make(ak); 2132 } 2133 } 2134 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2135 } else { // Found a type-array? 2136 //assert(!UseExactTypes, "this code should be useless with exact types"); 2137 assert( ak->is_type_array_klass(), "" ); 2138 return TypeKlassPtr::make(ak); // These are always precise 2139 } 2140 } 2141 } 2142 2143 // Check for loading klass from an array klass 2144 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2145 if (tkls != NULL && !StressReflectiveCode) { 2146 ciKlass* klass = tkls->klass(); 2147 if( !klass->is_loaded() ) 2148 return _type; // Bail out if not loaded 2149 if( klass->is_obj_array_klass() && 2150 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2151 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2152 // // Always returning precise element type is incorrect, 2153 // // e.g., element type could be object and array may contain strings 2154 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2155 2156 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2157 // according to the element type's subclassing. 2158 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2159 } 2160 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2161 tkls->offset() == in_bytes(Klass::super_offset())) { 2162 ciKlass* sup = klass->as_instance_klass()->super(); 2163 // The field is Klass::_super. Return its (constant) value. 2164 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2165 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2166 } 2167 } 2168 2169 // Bailout case 2170 return LoadNode::Value(phase); 2171 } 2172 2173 //------------------------------Identity--------------------------------------- 2174 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2175 // Also feed through the klass in Allocate(...klass...)._klass. 2176 Node* LoadKlassNode::Identity( PhaseTransform *phase ) { 2177 return klass_identity_common(phase); 2178 } 2179 2180 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) { 2181 Node* x = LoadNode::Identity(phase); 2182 if (x != this) return x; 2183 2184 // Take apart the address into an oop and and offset. 2185 // Return 'this' if we cannot. 2186 Node* adr = in(MemNode::Address); 2187 intptr_t offset = 0; 2188 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2189 if (base == NULL) return this; 2190 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2191 if (toop == NULL) return this; 2192 2193 // We can fetch the klass directly through an AllocateNode. 2194 // This works even if the klass is not constant (clone or newArray). 2195 if (offset == oopDesc::klass_offset_in_bytes()) { 2196 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2197 if (allocated_klass != NULL) { 2198 return allocated_klass; 2199 } 2200 } 2201 2202 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2203 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass. 2204 // See inline_native_Class_query for occurrences of these patterns. 2205 // Java Example: x.getClass().isAssignableFrom(y) 2206 // Java Example: Array.newInstance(x.getClass().getComponentType(), n) 2207 // 2208 // This improves reflective code, often making the Class 2209 // mirror go completely dead. (Current exception: Class 2210 // mirrors may appear in debug info, but we could clean them out by 2211 // introducing a new debug info operator for Klass*.java_mirror). 2212 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2213 && (offset == java_lang_Class::klass_offset_in_bytes() || 2214 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2215 // We are loading a special hidden field from a Class mirror, 2216 // the field which points to its Klass or ArrayKlass metaobject. 2217 if (base->is_Load()) { 2218 Node* adr2 = base->in(MemNode::Address); 2219 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2220 if (tkls != NULL && !tkls->empty() 2221 && (tkls->klass()->is_instance_klass() || 2222 tkls->klass()->is_array_klass()) 2223 && adr2->is_AddP() 2224 ) { 2225 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2226 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2227 mirror_field = in_bytes(ArrayKlass::component_mirror_offset()); 2228 } 2229 if (tkls->offset() == mirror_field) { 2230 return adr2->in(AddPNode::Base); 2231 } 2232 } 2233 } 2234 } 2235 2236 return this; 2237 } 2238 2239 2240 //------------------------------Value------------------------------------------ 2241 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const { 2242 const Type *t = klass_value_common(phase); 2243 if (t == Type::TOP) 2244 return t; 2245 2246 return t->make_narrowklass(); 2247 } 2248 2249 //------------------------------Identity--------------------------------------- 2250 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2251 // Also feed through the klass in Allocate(...klass...)._klass. 2252 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) { 2253 Node *x = klass_identity_common(phase); 2254 2255 const Type *t = phase->type( x ); 2256 if( t == Type::TOP ) return x; 2257 if( t->isa_narrowklass()) return x; 2258 assert (!t->isa_narrowoop(), "no narrow oop here"); 2259 2260 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2261 } 2262 2263 //------------------------------Value----------------------------------------- 2264 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { 2265 // Either input is TOP ==> the result is TOP 2266 const Type *t1 = phase->type( in(MemNode::Memory) ); 2267 if( t1 == Type::TOP ) return Type::TOP; 2268 Node *adr = in(MemNode::Address); 2269 const Type *t2 = phase->type( adr ); 2270 if( t2 == Type::TOP ) return Type::TOP; 2271 const TypePtr *tp = t2->is_ptr(); 2272 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2273 const TypeAryPtr *tap = tp->isa_aryptr(); 2274 if( !tap ) return _type; 2275 return tap->size(); 2276 } 2277 2278 //-------------------------------Ideal--------------------------------------- 2279 // Feed through the length in AllocateArray(...length...)._length. 2280 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2281 Node* p = MemNode::Ideal_common(phase, can_reshape); 2282 if (p) return (p == NodeSentinel) ? NULL : p; 2283 2284 // Take apart the address into an oop and and offset. 2285 // Return 'this' if we cannot. 2286 Node* adr = in(MemNode::Address); 2287 intptr_t offset = 0; 2288 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2289 if (base == NULL) return NULL; 2290 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2291 if (tary == NULL) return NULL; 2292 2293 // We can fetch the length directly through an AllocateArrayNode. 2294 // This works even if the length is not constant (clone or newArray). 2295 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2296 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2297 if (alloc != NULL) { 2298 Node* allocated_length = alloc->Ideal_length(); 2299 Node* len = alloc->make_ideal_length(tary, phase); 2300 if (allocated_length != len) { 2301 // New CastII improves on this. 2302 return len; 2303 } 2304 } 2305 } 2306 2307 return NULL; 2308 } 2309 2310 //------------------------------Identity--------------------------------------- 2311 // Feed through the length in AllocateArray(...length...)._length. 2312 Node* LoadRangeNode::Identity( PhaseTransform *phase ) { 2313 Node* x = LoadINode::Identity(phase); 2314 if (x != this) return x; 2315 2316 // Take apart the address into an oop and and offset. 2317 // Return 'this' if we cannot. 2318 Node* adr = in(MemNode::Address); 2319 intptr_t offset = 0; 2320 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2321 if (base == NULL) return this; 2322 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2323 if (tary == NULL) return this; 2324 2325 // We can fetch the length directly through an AllocateArrayNode. 2326 // This works even if the length is not constant (clone or newArray). 2327 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2328 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2329 if (alloc != NULL) { 2330 Node* allocated_length = alloc->Ideal_length(); 2331 // Do not allow make_ideal_length to allocate a CastII node. 2332 Node* len = alloc->make_ideal_length(tary, phase, false); 2333 if (allocated_length == len) { 2334 // Return allocated_length only if it would not be improved by a CastII. 2335 return allocated_length; 2336 } 2337 } 2338 } 2339 2340 return this; 2341 2342 } 2343 2344 //============================================================================= 2345 //---------------------------StoreNode::make----------------------------------- 2346 // Polymorphic factory method: 2347 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2348 assert((mo == unordered || mo == release), "unexpected"); 2349 Compile* C = gvn.C; 2350 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2351 ctl != NULL, "raw memory operations should have control edge"); 2352 2353 switch (bt) { 2354 case T_BOOLEAN: 2355 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2356 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2357 case T_CHAR: 2358 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2359 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2360 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2361 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2362 case T_METADATA: 2363 case T_ADDRESS: 2364 case T_OBJECT: 2365 #ifdef _LP64 2366 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2367 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2368 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2369 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2370 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2371 adr->bottom_type()->isa_rawptr())) { 2372 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2373 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2374 } 2375 #endif 2376 { 2377 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2378 } 2379 } 2380 ShouldNotReachHere(); 2381 return (StoreNode*)NULL; 2382 } 2383 2384 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2385 bool require_atomic = true; 2386 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2387 } 2388 2389 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2390 bool require_atomic = true; 2391 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2392 } 2393 2394 2395 //--------------------------bottom_type---------------------------------------- 2396 const Type *StoreNode::bottom_type() const { 2397 return Type::MEMORY; 2398 } 2399 2400 //------------------------------hash------------------------------------------- 2401 uint StoreNode::hash() const { 2402 // unroll addition of interesting fields 2403 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2404 2405 // Since they are not commoned, do not hash them: 2406 return NO_HASH; 2407 } 2408 2409 //------------------------------Ideal------------------------------------------ 2410 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2411 // When a store immediately follows a relevant allocation/initialization, 2412 // try to capture it into the initialization, or hoist it above. 2413 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2414 Node* p = MemNode::Ideal_common(phase, can_reshape); 2415 if (p) return (p == NodeSentinel) ? NULL : p; 2416 2417 Node* mem = in(MemNode::Memory); 2418 Node* address = in(MemNode::Address); 2419 2420 // Back-to-back stores to same address? Fold em up. Generally 2421 // unsafe if I have intervening uses... Also disallowed for StoreCM 2422 // since they must follow each StoreP operation. Redundant StoreCMs 2423 // are eliminated just before matching in final_graph_reshape. 2424 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) && 2425 mem->Opcode() != Op_StoreCM) { 2426 // Looking at a dead closed cycle of memory? 2427 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2428 2429 assert(Opcode() == mem->Opcode() || 2430 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, 2431 "no mismatched stores, except on raw memory"); 2432 2433 if (mem->outcnt() == 1 && // check for intervening uses 2434 mem->as_Store()->memory_size() <= this->memory_size()) { 2435 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. 2436 // For example, 'mem' might be the final state at a conditional return. 2437 // Or, 'mem' might be used by some node which is live at the same time 2438 // 'this' is live, which might be unschedulable. So, require exactly 2439 // ONE user, the 'this' store, until such time as we clone 'mem' for 2440 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). 2441 if (can_reshape) { // (%%% is this an anachronism?) 2442 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), 2443 phase->is_IterGVN()); 2444 } else { 2445 // It's OK to do this in the parser, since DU info is always accurate, 2446 // and the parser always refers to nodes via SafePointNode maps. 2447 set_req(MemNode::Memory, mem->in(MemNode::Memory)); 2448 } 2449 return this; 2450 } 2451 } 2452 2453 // Capture an unaliased, unconditional, simple store into an initializer. 2454 // Or, if it is independent of the allocation, hoist it above the allocation. 2455 if (ReduceFieldZeroing && /*can_reshape &&*/ 2456 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2457 InitializeNode* init = mem->in(0)->as_Initialize(); 2458 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2459 if (offset > 0) { 2460 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2461 // If the InitializeNode captured me, it made a raw copy of me, 2462 // and I need to disappear. 2463 if (moved != NULL) { 2464 // %%% hack to ensure that Ideal returns a new node: 2465 mem = MergeMemNode::make(mem); 2466 return mem; // fold me away 2467 } 2468 } 2469 } 2470 2471 return NULL; // No further progress 2472 } 2473 2474 //------------------------------Value----------------------------------------- 2475 const Type *StoreNode::Value( PhaseTransform *phase ) const { 2476 // Either input is TOP ==> the result is TOP 2477 const Type *t1 = phase->type( in(MemNode::Memory) ); 2478 if( t1 == Type::TOP ) return Type::TOP; 2479 const Type *t2 = phase->type( in(MemNode::Address) ); 2480 if( t2 == Type::TOP ) return Type::TOP; 2481 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2482 if( t3 == Type::TOP ) return Type::TOP; 2483 return Type::MEMORY; 2484 } 2485 2486 //------------------------------Identity--------------------------------------- 2487 // Remove redundant stores: 2488 // Store(m, p, Load(m, p)) changes to m. 2489 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2490 Node *StoreNode::Identity( PhaseTransform *phase ) { 2491 Node* mem = in(MemNode::Memory); 2492 Node* adr = in(MemNode::Address); 2493 Node* val = in(MemNode::ValueIn); 2494 2495 // Load then Store? Then the Store is useless 2496 if (val->is_Load() && 2497 val->in(MemNode::Address)->eqv_uncast(adr) && 2498 val->in(MemNode::Memory )->eqv_uncast(mem) && 2499 val->as_Load()->store_Opcode() == Opcode()) { 2500 return mem; 2501 } 2502 2503 // Two stores in a row of the same value? 2504 if (mem->is_Store() && 2505 mem->in(MemNode::Address)->eqv_uncast(adr) && 2506 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2507 mem->Opcode() == Opcode()) { 2508 return mem; 2509 } 2510 2511 // Store of zero anywhere into a freshly-allocated object? 2512 // Then the store is useless. 2513 // (It must already have been captured by the InitializeNode.) 2514 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2515 // a newly allocated object is already all-zeroes everywhere 2516 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2517 return mem; 2518 } 2519 2520 // the store may also apply to zero-bits in an earlier object 2521 Node* prev_mem = find_previous_store(phase); 2522 // Steps (a), (b): Walk past independent stores to find an exact match. 2523 if (prev_mem != NULL) { 2524 Node* prev_val = can_see_stored_value(prev_mem, phase); 2525 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2526 // prev_val and val might differ by a cast; it would be good 2527 // to keep the more informative of the two. 2528 return mem; 2529 } 2530 } 2531 } 2532 2533 return this; 2534 } 2535 2536 //------------------------------match_edge------------------------------------- 2537 // Do we Match on this edge index or not? Match only memory & value 2538 uint StoreNode::match_edge(uint idx) const { 2539 return idx == MemNode::Address || idx == MemNode::ValueIn; 2540 } 2541 2542 //------------------------------cmp-------------------------------------------- 2543 // Do not common stores up together. They generally have to be split 2544 // back up anyways, so do not bother. 2545 uint StoreNode::cmp( const Node &n ) const { 2546 return (&n == this); // Always fail except on self 2547 } 2548 2549 //------------------------------Ideal_masked_input----------------------------- 2550 // Check for a useless mask before a partial-word store 2551 // (StoreB ... (AndI valIn conIa) ) 2552 // If (conIa & mask == mask) this simplifies to 2553 // (StoreB ... (valIn) ) 2554 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2555 Node *val = in(MemNode::ValueIn); 2556 if( val->Opcode() == Op_AndI ) { 2557 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2558 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2559 set_req(MemNode::ValueIn, val->in(1)); 2560 return this; 2561 } 2562 } 2563 return NULL; 2564 } 2565 2566 2567 //------------------------------Ideal_sign_extended_input---------------------- 2568 // Check for useless sign-extension before a partial-word store 2569 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2570 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2571 // (StoreB ... (valIn) ) 2572 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2573 Node *val = in(MemNode::ValueIn); 2574 if( val->Opcode() == Op_RShiftI ) { 2575 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2576 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2577 Node *shl = val->in(1); 2578 if( shl->Opcode() == Op_LShiftI ) { 2579 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2580 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2581 set_req(MemNode::ValueIn, shl->in(1)); 2582 return this; 2583 } 2584 } 2585 } 2586 } 2587 return NULL; 2588 } 2589 2590 //------------------------------value_never_loaded----------------------------------- 2591 // Determine whether there are any possible loads of the value stored. 2592 // For simplicity, we actually check if there are any loads from the 2593 // address stored to, not just for loads of the value stored by this node. 2594 // 2595 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2596 Node *adr = in(Address); 2597 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2598 if (adr_oop == NULL) 2599 return false; 2600 if (!adr_oop->is_known_instance_field()) 2601 return false; // if not a distinct instance, there may be aliases of the address 2602 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2603 Node *use = adr->fast_out(i); 2604 int opc = use->Opcode(); 2605 if (use->is_Load() || use->is_LoadStore()) { 2606 return false; 2607 } 2608 } 2609 return true; 2610 } 2611 2612 //============================================================================= 2613 //------------------------------Ideal------------------------------------------ 2614 // If the store is from an AND mask that leaves the low bits untouched, then 2615 // we can skip the AND operation. If the store is from a sign-extension 2616 // (a left shift, then right shift) we can skip both. 2617 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2618 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2619 if( progress != NULL ) return progress; 2620 2621 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2622 if( progress != NULL ) return progress; 2623 2624 // Finally check the default case 2625 return StoreNode::Ideal(phase, can_reshape); 2626 } 2627 2628 //============================================================================= 2629 //------------------------------Ideal------------------------------------------ 2630 // If the store is from an AND mask that leaves the low bits untouched, then 2631 // we can skip the AND operation 2632 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2633 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2634 if( progress != NULL ) return progress; 2635 2636 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2637 if( progress != NULL ) return progress; 2638 2639 // Finally check the default case 2640 return StoreNode::Ideal(phase, can_reshape); 2641 } 2642 2643 //============================================================================= 2644 //------------------------------Identity--------------------------------------- 2645 Node *StoreCMNode::Identity( PhaseTransform *phase ) { 2646 // No need to card mark when storing a null ptr 2647 Node* my_store = in(MemNode::OopStore); 2648 if (my_store->is_Store()) { 2649 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2650 if( t1 == TypePtr::NULL_PTR ) { 2651 return in(MemNode::Memory); 2652 } 2653 } 2654 return this; 2655 } 2656 2657 //============================================================================= 2658 //------------------------------Ideal--------------------------------------- 2659 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2660 Node* progress = StoreNode::Ideal(phase, can_reshape); 2661 if (progress != NULL) return progress; 2662 2663 Node* my_store = in(MemNode::OopStore); 2664 if (my_store->is_MergeMem()) { 2665 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2666 set_req(MemNode::OopStore, mem); 2667 return this; 2668 } 2669 2670 return NULL; 2671 } 2672 2673 //------------------------------Value----------------------------------------- 2674 const Type *StoreCMNode::Value( PhaseTransform *phase ) const { 2675 // Either input is TOP ==> the result is TOP 2676 const Type *t = phase->type( in(MemNode::Memory) ); 2677 if( t == Type::TOP ) return Type::TOP; 2678 t = phase->type( in(MemNode::Address) ); 2679 if( t == Type::TOP ) return Type::TOP; 2680 t = phase->type( in(MemNode::ValueIn) ); 2681 if( t == Type::TOP ) return Type::TOP; 2682 // If extra input is TOP ==> the result is TOP 2683 t = phase->type( in(MemNode::OopStore) ); 2684 if( t == Type::TOP ) return Type::TOP; 2685 2686 return StoreNode::Value( phase ); 2687 } 2688 2689 2690 //============================================================================= 2691 //----------------------------------SCMemProjNode------------------------------ 2692 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const 2693 { 2694 return bottom_type(); 2695 } 2696 2697 //============================================================================= 2698 //----------------------------------LoadStoreNode------------------------------ 2699 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2700 : Node(required), 2701 _type(rt), 2702 _adr_type(at) 2703 { 2704 init_req(MemNode::Control, c ); 2705 init_req(MemNode::Memory , mem); 2706 init_req(MemNode::Address, adr); 2707 init_req(MemNode::ValueIn, val); 2708 init_class_id(Class_LoadStore); 2709 } 2710 2711 uint LoadStoreNode::ideal_reg() const { 2712 return _type->ideal_reg(); 2713 } 2714 2715 bool LoadStoreNode::result_not_used() const { 2716 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2717 Node *x = fast_out(i); 2718 if (x->Opcode() == Op_SCMemProj) continue; 2719 return false; 2720 } 2721 return true; 2722 } 2723 2724 uint LoadStoreNode::size_of() const { return sizeof(*this); } 2725 2726 //============================================================================= 2727 //----------------------------------LoadStoreConditionalNode-------------------- 2728 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 2729 init_req(ExpectedIn, ex ); 2730 } 2731 2732 //============================================================================= 2733 //-------------------------------adr_type-------------------------------------- 2734 // Do we Match on this edge index or not? Do not match memory 2735 const TypePtr* ClearArrayNode::adr_type() const { 2736 Node *adr = in(3); 2737 return MemNode::calculate_adr_type(adr->bottom_type()); 2738 } 2739 2740 //------------------------------match_edge------------------------------------- 2741 // Do we Match on this edge index or not? Do not match memory 2742 uint ClearArrayNode::match_edge(uint idx) const { 2743 return idx > 1; 2744 } 2745 2746 //------------------------------Identity--------------------------------------- 2747 // Clearing a zero length array does nothing 2748 Node *ClearArrayNode::Identity( PhaseTransform *phase ) { 2749 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2750 } 2751 2752 //------------------------------Idealize--------------------------------------- 2753 // Clearing a short array is faster with stores 2754 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2755 const int unit = BytesPerLong; 2756 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2757 if (!t) return NULL; 2758 if (!t->is_con()) return NULL; 2759 intptr_t raw_count = t->get_con(); 2760 intptr_t size = raw_count; 2761 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2762 // Clearing nothing uses the Identity call. 2763 // Negative clears are possible on dead ClearArrays 2764 // (see jck test stmt114.stmt11402.val). 2765 if (size <= 0 || size % unit != 0) return NULL; 2766 intptr_t count = size / unit; 2767 // Length too long; use fast hardware clear 2768 if (size > Matcher::init_array_short_size) return NULL; 2769 Node *mem = in(1); 2770 if( phase->type(mem)==Type::TOP ) return NULL; 2771 Node *adr = in(3); 2772 const Type* at = phase->type(adr); 2773 if( at==Type::TOP ) return NULL; 2774 const TypePtr* atp = at->isa_ptr(); 2775 // adjust atp to be the correct array element address type 2776 if (atp == NULL) atp = TypePtr::BOTTOM; 2777 else atp = atp->add_offset(Type::OffsetBot); 2778 // Get base for derived pointer purposes 2779 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2780 Node *base = adr->in(1); 2781 2782 Node *zero = phase->makecon(TypeLong::ZERO); 2783 Node *off = phase->MakeConX(BytesPerLong); 2784 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2785 count--; 2786 while( count-- ) { 2787 mem = phase->transform(mem); 2788 adr = phase->transform(new AddPNode(base,adr,off)); 2789 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2790 } 2791 return mem; 2792 } 2793 2794 //----------------------------step_through---------------------------------- 2795 // Return allocation input memory edge if it is different instance 2796 // or itself if it is the one we are looking for. 2797 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2798 Node* n = *np; 2799 assert(n->is_ClearArray(), "sanity"); 2800 intptr_t offset; 2801 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2802 // This method is called only before Allocate nodes are expanded during 2803 // macro nodes expansion. Before that ClearArray nodes are only generated 2804 // in LibraryCallKit::generate_arraycopy() which follows allocations. 2805 assert(alloc != NULL, "should have allocation"); 2806 if (alloc->_idx == instance_id) { 2807 // Can not bypass initialization of the instance we are looking for. 2808 return false; 2809 } 2810 // Otherwise skip it. 2811 InitializeNode* init = alloc->initialization(); 2812 if (init != NULL) 2813 *np = init->in(TypeFunc::Memory); 2814 else 2815 *np = alloc->in(TypeFunc::Memory); 2816 return true; 2817 } 2818 2819 //----------------------------clear_memory------------------------------------- 2820 // Generate code to initialize object storage to zero. 2821 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2822 intptr_t start_offset, 2823 Node* end_offset, 2824 PhaseGVN* phase) { 2825 intptr_t offset = start_offset; 2826 2827 int unit = BytesPerLong; 2828 if ((offset % unit) != 0) { 2829 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 2830 adr = phase->transform(adr); 2831 const TypePtr* atp = TypeRawPtr::BOTTOM; 2832 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2833 mem = phase->transform(mem); 2834 offset += BytesPerInt; 2835 } 2836 assert((offset % unit) == 0, ""); 2837 2838 // Initialize the remaining stuff, if any, with a ClearArray. 2839 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2840 } 2841 2842 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2843 Node* start_offset, 2844 Node* end_offset, 2845 PhaseGVN* phase) { 2846 if (start_offset == end_offset) { 2847 // nothing to do 2848 return mem; 2849 } 2850 2851 int unit = BytesPerLong; 2852 Node* zbase = start_offset; 2853 Node* zend = end_offset; 2854 2855 // Scale to the unit required by the CPU: 2856 if (!Matcher::init_array_count_is_in_bytes) { 2857 Node* shift = phase->intcon(exact_log2(unit)); 2858 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 2859 zend = phase->transform(new URShiftXNode(zend, shift) ); 2860 } 2861 2862 // Bulk clear double-words 2863 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 2864 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 2865 mem = new ClearArrayNode(ctl, mem, zsize, adr); 2866 return phase->transform(mem); 2867 } 2868 2869 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2870 intptr_t start_offset, 2871 intptr_t end_offset, 2872 PhaseGVN* phase) { 2873 if (start_offset == end_offset) { 2874 // nothing to do 2875 return mem; 2876 } 2877 2878 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2879 intptr_t done_offset = end_offset; 2880 if ((done_offset % BytesPerLong) != 0) { 2881 done_offset -= BytesPerInt; 2882 } 2883 if (done_offset > start_offset) { 2884 mem = clear_memory(ctl, mem, dest, 2885 start_offset, phase->MakeConX(done_offset), phase); 2886 } 2887 if (done_offset < end_offset) { // emit the final 32-bit store 2888 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 2889 adr = phase->transform(adr); 2890 const TypePtr* atp = TypeRawPtr::BOTTOM; 2891 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2892 mem = phase->transform(mem); 2893 done_offset += BytesPerInt; 2894 } 2895 assert(done_offset == end_offset, ""); 2896 return mem; 2897 } 2898 2899 //============================================================================= 2900 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2901 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2902 _adr_type(C->get_adr_type(alias_idx)) 2903 { 2904 init_class_id(Class_MemBar); 2905 Node* top = C->top(); 2906 init_req(TypeFunc::I_O,top); 2907 init_req(TypeFunc::FramePtr,top); 2908 init_req(TypeFunc::ReturnAdr,top); 2909 if (precedent != NULL) 2910 init_req(TypeFunc::Parms, precedent); 2911 } 2912 2913 //------------------------------cmp-------------------------------------------- 2914 uint MemBarNode::hash() const { return NO_HASH; } 2915 uint MemBarNode::cmp( const Node &n ) const { 2916 return (&n == this); // Always fail except on self 2917 } 2918 2919 //------------------------------make------------------------------------------- 2920 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2921 switch (opcode) { 2922 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 2923 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 2924 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 2925 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 2926 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 2927 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 2928 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 2929 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 2930 case Op_Initialize: return new InitializeNode(C, atp, pn); 2931 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 2932 default: ShouldNotReachHere(); return NULL; 2933 } 2934 } 2935 2936 //------------------------------Ideal------------------------------------------ 2937 // Return a node which is more "ideal" than the current node. Strip out 2938 // control copies 2939 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2940 if (remove_dead_region(phase, can_reshape)) return this; 2941 // Don't bother trying to transform a dead node 2942 if (in(0) && in(0)->is_top()) { 2943 return NULL; 2944 } 2945 2946 bool progress = false; 2947 // Eliminate volatile MemBars for scalar replaced objects. 2948 if (can_reshape && req() == (Precedent+1)) { 2949 bool eliminate = false; 2950 int opc = Opcode(); 2951 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 2952 // Volatile field loads and stores. 2953 Node* my_mem = in(MemBarNode::Precedent); 2954 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 2955 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 2956 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 2957 // replace this Precedent (decodeN) with the Load instead. 2958 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 2959 Node* load_node = my_mem->in(1); 2960 set_req(MemBarNode::Precedent, load_node); 2961 phase->is_IterGVN()->_worklist.push(my_mem); 2962 my_mem = load_node; 2963 } else { 2964 assert(my_mem->unique_out() == this, "sanity"); 2965 del_req(Precedent); 2966 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 2967 my_mem = NULL; 2968 } 2969 progress = true; 2970 } 2971 if (my_mem != NULL && my_mem->is_Mem()) { 2972 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 2973 // Check for scalar replaced object reference. 2974 if( t_oop != NULL && t_oop->is_known_instance_field() && 2975 t_oop->offset() != Type::OffsetBot && 2976 t_oop->offset() != Type::OffsetTop) { 2977 eliminate = true; 2978 } 2979 } 2980 } else if (opc == Op_MemBarRelease) { 2981 // Final field stores. 2982 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 2983 if ((alloc != NULL) && alloc->is_Allocate() && 2984 alloc->as_Allocate()->_is_non_escaping) { 2985 // The allocated object does not escape. 2986 eliminate = true; 2987 } 2988 } 2989 if (eliminate) { 2990 // Replace MemBar projections by its inputs. 2991 PhaseIterGVN* igvn = phase->is_IterGVN(); 2992 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 2993 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 2994 // Must return either the original node (now dead) or a new node 2995 // (Do not return a top here, since that would break the uniqueness of top.) 2996 return new ConINode(TypeInt::ZERO); 2997 } 2998 } 2999 return progress ? this : NULL; 3000 } 3001 3002 //------------------------------Value------------------------------------------ 3003 const Type *MemBarNode::Value( PhaseTransform *phase ) const { 3004 if( !in(0) ) return Type::TOP; 3005 if( phase->type(in(0)) == Type::TOP ) 3006 return Type::TOP; 3007 return TypeTuple::MEMBAR; 3008 } 3009 3010 //------------------------------match------------------------------------------ 3011 // Construct projections for memory. 3012 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3013 switch (proj->_con) { 3014 case TypeFunc::Control: 3015 case TypeFunc::Memory: 3016 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3017 } 3018 ShouldNotReachHere(); 3019 return NULL; 3020 } 3021 3022 //===========================InitializeNode==================================== 3023 // SUMMARY: 3024 // This node acts as a memory barrier on raw memory, after some raw stores. 3025 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 3026 // The Initialize can 'capture' suitably constrained stores as raw inits. 3027 // It can coalesce related raw stores into larger units (called 'tiles'). 3028 // It can avoid zeroing new storage for memory units which have raw inits. 3029 // At macro-expansion, it is marked 'complete', and does not optimize further. 3030 // 3031 // EXAMPLE: 3032 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3033 // ctl = incoming control; mem* = incoming memory 3034 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 3035 // First allocate uninitialized memory and fill in the header: 3036 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 3037 // ctl := alloc.Control; mem* := alloc.Memory* 3038 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 3039 // Then initialize to zero the non-header parts of the raw memory block: 3040 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3041 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3042 // After the initialize node executes, the object is ready for service: 3043 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3044 // Suppose its body is immediately initialized as {1,2}: 3045 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3046 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3047 // mem.SLICE(#short[*]) := store2 3048 // 3049 // DETAILS: 3050 // An InitializeNode collects and isolates object initialization after 3051 // an AllocateNode and before the next possible safepoint. As a 3052 // memory barrier (MemBarNode), it keeps critical stores from drifting 3053 // down past any safepoint or any publication of the allocation. 3054 // Before this barrier, a newly-allocated object may have uninitialized bits. 3055 // After this barrier, it may be treated as a real oop, and GC is allowed. 3056 // 3057 // The semantics of the InitializeNode include an implicit zeroing of 3058 // the new object from object header to the end of the object. 3059 // (The object header and end are determined by the AllocateNode.) 3060 // 3061 // Certain stores may be added as direct inputs to the InitializeNode. 3062 // These stores must update raw memory, and they must be to addresses 3063 // derived from the raw address produced by AllocateNode, and with 3064 // a constant offset. They must be ordered by increasing offset. 3065 // The first one is at in(RawStores), the last at in(req()-1). 3066 // Unlike most memory operations, they are not linked in a chain, 3067 // but are displayed in parallel as users of the rawmem output of 3068 // the allocation. 3069 // 3070 // (See comments in InitializeNode::capture_store, which continue 3071 // the example given above.) 3072 // 3073 // When the associated Allocate is macro-expanded, the InitializeNode 3074 // may be rewritten to optimize collected stores. A ClearArrayNode 3075 // may also be created at that point to represent any required zeroing. 3076 // The InitializeNode is then marked 'complete', prohibiting further 3077 // capturing of nearby memory operations. 3078 // 3079 // During macro-expansion, all captured initializations which store 3080 // constant values of 32 bits or smaller are coalesced (if advantageous) 3081 // into larger 'tiles' 32 or 64 bits. This allows an object to be 3082 // initialized in fewer memory operations. Memory words which are 3083 // covered by neither tiles nor non-constant stores are pre-zeroed 3084 // by explicit stores of zero. (The code shape happens to do all 3085 // zeroing first, then all other stores, with both sequences occurring 3086 // in order of ascending offsets.) 3087 // 3088 // Alternatively, code may be inserted between an AllocateNode and its 3089 // InitializeNode, to perform arbitrary initialization of the new object. 3090 // E.g., the object copying intrinsics insert complex data transfers here. 3091 // The initialization must then be marked as 'complete' disable the 3092 // built-in zeroing semantics and the collection of initializing stores. 3093 // 3094 // While an InitializeNode is incomplete, reads from the memory state 3095 // produced by it are optimizable if they match the control edge and 3096 // new oop address associated with the allocation/initialization. 3097 // They return a stored value (if the offset matches) or else zero. 3098 // A write to the memory state, if it matches control and address, 3099 // and if it is to a constant offset, may be 'captured' by the 3100 // InitializeNode. It is cloned as a raw memory operation and rewired 3101 // inside the initialization, to the raw oop produced by the allocation. 3102 // Operations on addresses which are provably distinct (e.g., to 3103 // other AllocateNodes) are allowed to bypass the initialization. 3104 // 3105 // The effect of all this is to consolidate object initialization 3106 // (both arrays and non-arrays, both piecewise and bulk) into a 3107 // single location, where it can be optimized as a unit. 3108 // 3109 // Only stores with an offset less than TrackedInitializationLimit words 3110 // will be considered for capture by an InitializeNode. This puts a 3111 // reasonable limit on the complexity of optimized initializations. 3112 3113 //---------------------------InitializeNode------------------------------------ 3114 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3115 : _is_complete(Incomplete), _does_not_escape(false), 3116 MemBarNode(C, adr_type, rawoop) 3117 { 3118 init_class_id(Class_Initialize); 3119 3120 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3121 assert(in(RawAddress) == rawoop, "proper init"); 3122 // Note: allocation() can be NULL, for secondary initialization barriers 3123 } 3124 3125 // Since this node is not matched, it will be processed by the 3126 // register allocator. Declare that there are no constraints 3127 // on the allocation of the RawAddress edge. 3128 const RegMask &InitializeNode::in_RegMask(uint idx) const { 3129 // This edge should be set to top, by the set_complete. But be conservative. 3130 if (idx == InitializeNode::RawAddress) 3131 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3132 return RegMask::Empty; 3133 } 3134 3135 Node* InitializeNode::memory(uint alias_idx) { 3136 Node* mem = in(Memory); 3137 if (mem->is_MergeMem()) { 3138 return mem->as_MergeMem()->memory_at(alias_idx); 3139 } else { 3140 // incoming raw memory is not split 3141 return mem; 3142 } 3143 } 3144 3145 bool InitializeNode::is_non_zero() { 3146 if (is_complete()) return false; 3147 remove_extra_zeroes(); 3148 return (req() > RawStores); 3149 } 3150 3151 void InitializeNode::set_complete(PhaseGVN* phase) { 3152 assert(!is_complete(), "caller responsibility"); 3153 _is_complete = Complete; 3154 3155 // After this node is complete, it contains a bunch of 3156 // raw-memory initializations. There is no need for 3157 // it to have anything to do with non-raw memory effects. 3158 // Therefore, tell all non-raw users to re-optimize themselves, 3159 // after skipping the memory effects of this initialization. 3160 PhaseIterGVN* igvn = phase->is_IterGVN(); 3161 if (igvn) igvn->add_users_to_worklist(this); 3162 } 3163 3164 // convenience function 3165 // return false if the init contains any stores already 3166 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3167 InitializeNode* init = initialization(); 3168 if (init == NULL || init->is_complete()) return false; 3169 init->remove_extra_zeroes(); 3170 // for now, if this allocation has already collected any inits, bail: 3171 if (init->is_non_zero()) return false; 3172 init->set_complete(phase); 3173 return true; 3174 } 3175 3176 void InitializeNode::remove_extra_zeroes() { 3177 if (req() == RawStores) return; 3178 Node* zmem = zero_memory(); 3179 uint fill = RawStores; 3180 for (uint i = fill; i < req(); i++) { 3181 Node* n = in(i); 3182 if (n->is_top() || n == zmem) continue; // skip 3183 if (fill < i) set_req(fill, n); // compact 3184 ++fill; 3185 } 3186 // delete any empty spaces created: 3187 while (fill < req()) { 3188 del_req(fill); 3189 } 3190 } 3191 3192 // Helper for remembering which stores go with which offsets. 3193 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3194 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3195 intptr_t offset = -1; 3196 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3197 phase, offset); 3198 if (base == NULL) return -1; // something is dead, 3199 if (offset < 0) return -1; // dead, dead 3200 return offset; 3201 } 3202 3203 // Helper for proving that an initialization expression is 3204 // "simple enough" to be folded into an object initialization. 3205 // Attempts to prove that a store's initial value 'n' can be captured 3206 // within the initialization without creating a vicious cycle, such as: 3207 // { Foo p = new Foo(); p.next = p; } 3208 // True for constants and parameters and small combinations thereof. 3209 bool InitializeNode::detect_init_independence(Node* n, int& count) { 3210 if (n == NULL) return true; // (can this really happen?) 3211 if (n->is_Proj()) n = n->in(0); 3212 if (n == this) return false; // found a cycle 3213 if (n->is_Con()) return true; 3214 if (n->is_Start()) return true; // params, etc., are OK 3215 if (n->is_Root()) return true; // even better 3216 3217 Node* ctl = n->in(0); 3218 if (ctl != NULL && !ctl->is_top()) { 3219 if (ctl->is_Proj()) ctl = ctl->in(0); 3220 if (ctl == this) return false; 3221 3222 // If we already know that the enclosing memory op is pinned right after 3223 // the init, then any control flow that the store has picked up 3224 // must have preceded the init, or else be equal to the init. 3225 // Even after loop optimizations (which might change control edges) 3226 // a store is never pinned *before* the availability of its inputs. 3227 if (!MemNode::all_controls_dominate(n, this)) 3228 return false; // failed to prove a good control 3229 } 3230 3231 // Check data edges for possible dependencies on 'this'. 3232 if ((count += 1) > 20) return false; // complexity limit 3233 for (uint i = 1; i < n->req(); i++) { 3234 Node* m = n->in(i); 3235 if (m == NULL || m == n || m->is_top()) continue; 3236 uint first_i = n->find_edge(m); 3237 if (i != first_i) continue; // process duplicate edge just once 3238 if (!detect_init_independence(m, count)) { 3239 return false; 3240 } 3241 } 3242 3243 return true; 3244 } 3245 3246 // Here are all the checks a Store must pass before it can be moved into 3247 // an initialization. Returns zero if a check fails. 3248 // On success, returns the (constant) offset to which the store applies, 3249 // within the initialized memory. 3250 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) { 3251 const int FAIL = 0; 3252 if (st->req() != MemNode::ValueIn + 1) 3253 return FAIL; // an inscrutable StoreNode (card mark?) 3254 Node* ctl = st->in(MemNode::Control); 3255 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3256 return FAIL; // must be unconditional after the initialization 3257 Node* mem = st->in(MemNode::Memory); 3258 if (!(mem->is_Proj() && mem->in(0) == this)) 3259 return FAIL; // must not be preceded by other stores 3260 Node* adr = st->in(MemNode::Address); 3261 intptr_t offset; 3262 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3263 if (alloc == NULL) 3264 return FAIL; // inscrutable address 3265 if (alloc != allocation()) 3266 return FAIL; // wrong allocation! (store needs to float up) 3267 Node* val = st->in(MemNode::ValueIn); 3268 int complexity_count = 0; 3269 if (!detect_init_independence(val, complexity_count)) 3270 return FAIL; // stored value must be 'simple enough' 3271 3272 // The Store can be captured only if nothing after the allocation 3273 // and before the Store is using the memory location that the store 3274 // overwrites. 3275 bool failed = false; 3276 // If is_complete_with_arraycopy() is true the shape of the graph is 3277 // well defined and is safe so no need for extra checks. 3278 if (!is_complete_with_arraycopy()) { 3279 // We are going to look at each use of the memory state following 3280 // the allocation to make sure nothing reads the memory that the 3281 // Store writes. 3282 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3283 int alias_idx = phase->C->get_alias_index(t_adr); 3284 ResourceMark rm; 3285 Unique_Node_List mems; 3286 mems.push(mem); 3287 Node* unique_merge = NULL; 3288 for (uint next = 0; next < mems.size(); ++next) { 3289 Node *m = mems.at(next); 3290 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3291 Node *n = m->fast_out(j); 3292 if (n->outcnt() == 0) { 3293 continue; 3294 } 3295 if (n == st) { 3296 continue; 3297 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3298 // If the control of this use is different from the control 3299 // of the Store which is right after the InitializeNode then 3300 // this node cannot be between the InitializeNode and the 3301 // Store. 3302 continue; 3303 } else if (n->is_MergeMem()) { 3304 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3305 // We can hit a MergeMemNode (that will likely go away 3306 // later) that is a direct use of the memory state 3307 // following the InitializeNode on the same slice as the 3308 // store node that we'd like to capture. We need to check 3309 // the uses of the MergeMemNode. 3310 mems.push(n); 3311 } 3312 } else if (n->is_Mem()) { 3313 Node* other_adr = n->in(MemNode::Address); 3314 if (other_adr == adr) { 3315 failed = true; 3316 break; 3317 } else { 3318 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3319 if (other_t_adr != NULL) { 3320 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3321 if (other_alias_idx == alias_idx) { 3322 // A load from the same memory slice as the store right 3323 // after the InitializeNode. We check the control of the 3324 // object/array that is loaded from. If it's the same as 3325 // the store control then we cannot capture the store. 3326 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3327 Node* base = other_adr; 3328 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name())); 3329 base = base->in(AddPNode::Base); 3330 if (base != NULL) { 3331 base = base->uncast(); 3332 if (base->is_Proj() && base->in(0) == alloc) { 3333 failed = true; 3334 break; 3335 } 3336 } 3337 } 3338 } 3339 } 3340 } else { 3341 failed = true; 3342 break; 3343 } 3344 } 3345 } 3346 } 3347 if (failed) { 3348 if (!can_reshape) { 3349 // We decided we couldn't capture the store during parsing. We 3350 // should try again during the next IGVN once the graph is 3351 // cleaner. 3352 phase->C->record_for_igvn(st); 3353 } 3354 return FAIL; 3355 } 3356 3357 return offset; // success 3358 } 3359 3360 // Find the captured store in(i) which corresponds to the range 3361 // [start..start+size) in the initialized object. 3362 // If there is one, return its index i. If there isn't, return the 3363 // negative of the index where it should be inserted. 3364 // Return 0 if the queried range overlaps an initialization boundary 3365 // or if dead code is encountered. 3366 // If size_in_bytes is zero, do not bother with overlap checks. 3367 int InitializeNode::captured_store_insertion_point(intptr_t start, 3368 int size_in_bytes, 3369 PhaseTransform* phase) { 3370 const int FAIL = 0, MAX_STORE = BytesPerLong; 3371 3372 if (is_complete()) 3373 return FAIL; // arraycopy got here first; punt 3374 3375 assert(allocation() != NULL, "must be present"); 3376 3377 // no negatives, no header fields: 3378 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3379 3380 // after a certain size, we bail out on tracking all the stores: 3381 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3382 if (start >= ti_limit) return FAIL; 3383 3384 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3385 if (i >= limit) return -(int)i; // not found; here is where to put it 3386 3387 Node* st = in(i); 3388 intptr_t st_off = get_store_offset(st, phase); 3389 if (st_off < 0) { 3390 if (st != zero_memory()) { 3391 return FAIL; // bail out if there is dead garbage 3392 } 3393 } else if (st_off > start) { 3394 // ...we are done, since stores are ordered 3395 if (st_off < start + size_in_bytes) { 3396 return FAIL; // the next store overlaps 3397 } 3398 return -(int)i; // not found; here is where to put it 3399 } else if (st_off < start) { 3400 if (size_in_bytes != 0 && 3401 start < st_off + MAX_STORE && 3402 start < st_off + st->as_Store()->memory_size()) { 3403 return FAIL; // the previous store overlaps 3404 } 3405 } else { 3406 if (size_in_bytes != 0 && 3407 st->as_Store()->memory_size() != size_in_bytes) { 3408 return FAIL; // mismatched store size 3409 } 3410 return i; 3411 } 3412 3413 ++i; 3414 } 3415 } 3416 3417 // Look for a captured store which initializes at the offset 'start' 3418 // with the given size. If there is no such store, and no other 3419 // initialization interferes, then return zero_memory (the memory 3420 // projection of the AllocateNode). 3421 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3422 PhaseTransform* phase) { 3423 assert(stores_are_sane(phase), ""); 3424 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3425 if (i == 0) { 3426 return NULL; // something is dead 3427 } else if (i < 0) { 3428 return zero_memory(); // just primordial zero bits here 3429 } else { 3430 Node* st = in(i); // here is the store at this position 3431 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3432 return st; 3433 } 3434 } 3435 3436 // Create, as a raw pointer, an address within my new object at 'offset'. 3437 Node* InitializeNode::make_raw_address(intptr_t offset, 3438 PhaseTransform* phase) { 3439 Node* addr = in(RawAddress); 3440 if (offset != 0) { 3441 Compile* C = phase->C; 3442 addr = phase->transform( new AddPNode(C->top(), addr, 3443 phase->MakeConX(offset)) ); 3444 } 3445 return addr; 3446 } 3447 3448 // Clone the given store, converting it into a raw store 3449 // initializing a field or element of my new object. 3450 // Caller is responsible for retiring the original store, 3451 // with subsume_node or the like. 3452 // 3453 // From the example above InitializeNode::InitializeNode, 3454 // here are the old stores to be captured: 3455 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3456 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3457 // 3458 // Here is the changed code; note the extra edges on init: 3459 // alloc = (Allocate ...) 3460 // rawoop = alloc.RawAddress 3461 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3462 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3463 // init = (Initialize alloc.Control alloc.Memory rawoop 3464 // rawstore1 rawstore2) 3465 // 3466 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3467 PhaseTransform* phase, bool can_reshape) { 3468 assert(stores_are_sane(phase), ""); 3469 3470 if (start < 0) return NULL; 3471 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3472 3473 Compile* C = phase->C; 3474 int size_in_bytes = st->memory_size(); 3475 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3476 if (i == 0) return NULL; // bail out 3477 Node* prev_mem = NULL; // raw memory for the captured store 3478 if (i > 0) { 3479 prev_mem = in(i); // there is a pre-existing store under this one 3480 set_req(i, C->top()); // temporarily disconnect it 3481 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3482 } else { 3483 i = -i; // no pre-existing store 3484 prev_mem = zero_memory(); // a slice of the newly allocated object 3485 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3486 set_req(--i, C->top()); // reuse this edge; it has been folded away 3487 else 3488 ins_req(i, C->top()); // build a new edge 3489 } 3490 Node* new_st = st->clone(); 3491 new_st->set_req(MemNode::Control, in(Control)); 3492 new_st->set_req(MemNode::Memory, prev_mem); 3493 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3494 new_st = phase->transform(new_st); 3495 3496 // At this point, new_st might have swallowed a pre-existing store 3497 // at the same offset, or perhaps new_st might have disappeared, 3498 // if it redundantly stored the same value (or zero to fresh memory). 3499 3500 // In any case, wire it in: 3501 phase->igvn_rehash_node_delayed(this); 3502 set_req(i, new_st); 3503 3504 // The caller may now kill the old guy. 3505 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3506 assert(check_st == new_st || check_st == NULL, "must be findable"); 3507 assert(!is_complete(), ""); 3508 return new_st; 3509 } 3510 3511 static bool store_constant(jlong* tiles, int num_tiles, 3512 intptr_t st_off, int st_size, 3513 jlong con) { 3514 if ((st_off & (st_size-1)) != 0) 3515 return false; // strange store offset (assume size==2**N) 3516 address addr = (address)tiles + st_off; 3517 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3518 switch (st_size) { 3519 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3520 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3521 case sizeof(jint): *(jint*) addr = (jint) con; break; 3522 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3523 default: return false; // strange store size (detect size!=2**N here) 3524 } 3525 return true; // return success to caller 3526 } 3527 3528 // Coalesce subword constants into int constants and possibly 3529 // into long constants. The goal, if the CPU permits, 3530 // is to initialize the object with a small number of 64-bit tiles. 3531 // Also, convert floating-point constants to bit patterns. 3532 // Non-constants are not relevant to this pass. 3533 // 3534 // In terms of the running example on InitializeNode::InitializeNode 3535 // and InitializeNode::capture_store, here is the transformation 3536 // of rawstore1 and rawstore2 into rawstore12: 3537 // alloc = (Allocate ...) 3538 // rawoop = alloc.RawAddress 3539 // tile12 = 0x00010002 3540 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3541 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3542 // 3543 void 3544 InitializeNode::coalesce_subword_stores(intptr_t header_size, 3545 Node* size_in_bytes, 3546 PhaseGVN* phase) { 3547 Compile* C = phase->C; 3548 3549 assert(stores_are_sane(phase), ""); 3550 // Note: After this pass, they are not completely sane, 3551 // since there may be some overlaps. 3552 3553 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3554 3555 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3556 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3557 size_limit = MIN2(size_limit, ti_limit); 3558 size_limit = align_size_up(size_limit, BytesPerLong); 3559 int num_tiles = size_limit / BytesPerLong; 3560 3561 // allocate space for the tile map: 3562 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3563 jlong tiles_buf[small_len]; 3564 Node* nodes_buf[small_len]; 3565 jlong inits_buf[small_len]; 3566 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3567 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3568 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3569 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3570 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3571 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3572 // tiles: exact bitwise model of all primitive constants 3573 // nodes: last constant-storing node subsumed into the tiles model 3574 // inits: which bytes (in each tile) are touched by any initializations 3575 3576 //// Pass A: Fill in the tile model with any relevant stores. 3577 3578 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3579 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3580 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3581 Node* zmem = zero_memory(); // initially zero memory state 3582 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3583 Node* st = in(i); 3584 intptr_t st_off = get_store_offset(st, phase); 3585 3586 // Figure out the store's offset and constant value: 3587 if (st_off < header_size) continue; //skip (ignore header) 3588 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3589 int st_size = st->as_Store()->memory_size(); 3590 if (st_off + st_size > size_limit) break; 3591 3592 // Record which bytes are touched, whether by constant or not. 3593 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3594 continue; // skip (strange store size) 3595 3596 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3597 if (!val->singleton()) continue; //skip (non-con store) 3598 BasicType type = val->basic_type(); 3599 3600 jlong con = 0; 3601 switch (type) { 3602 case T_INT: con = val->is_int()->get_con(); break; 3603 case T_LONG: con = val->is_long()->get_con(); break; 3604 case T_FLOAT: con = jint_cast(val->getf()); break; 3605 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3606 default: continue; //skip (odd store type) 3607 } 3608 3609 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3610 st->Opcode() == Op_StoreL) { 3611 continue; // This StoreL is already optimal. 3612 } 3613 3614 // Store down the constant. 3615 store_constant(tiles, num_tiles, st_off, st_size, con); 3616 3617 intptr_t j = st_off >> LogBytesPerLong; 3618 3619 if (type == T_INT && st_size == BytesPerInt 3620 && (st_off & BytesPerInt) == BytesPerInt) { 3621 jlong lcon = tiles[j]; 3622 if (!Matcher::isSimpleConstant64(lcon) && 3623 st->Opcode() == Op_StoreI) { 3624 // This StoreI is already optimal by itself. 3625 jint* intcon = (jint*) &tiles[j]; 3626 intcon[1] = 0; // undo the store_constant() 3627 3628 // If the previous store is also optimal by itself, back up and 3629 // undo the action of the previous loop iteration... if we can. 3630 // But if we can't, just let the previous half take care of itself. 3631 st = nodes[j]; 3632 st_off -= BytesPerInt; 3633 con = intcon[0]; 3634 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3635 assert(st_off >= header_size, "still ignoring header"); 3636 assert(get_store_offset(st, phase) == st_off, "must be"); 3637 assert(in(i-1) == zmem, "must be"); 3638 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3639 assert(con == tcon->is_int()->get_con(), "must be"); 3640 // Undo the effects of the previous loop trip, which swallowed st: 3641 intcon[0] = 0; // undo store_constant() 3642 set_req(i-1, st); // undo set_req(i, zmem) 3643 nodes[j] = NULL; // undo nodes[j] = st 3644 --old_subword; // undo ++old_subword 3645 } 3646 continue; // This StoreI is already optimal. 3647 } 3648 } 3649 3650 // This store is not needed. 3651 set_req(i, zmem); 3652 nodes[j] = st; // record for the moment 3653 if (st_size < BytesPerLong) // something has changed 3654 ++old_subword; // includes int/float, but who's counting... 3655 else ++old_long; 3656 } 3657 3658 if ((old_subword + old_long) == 0) 3659 return; // nothing more to do 3660 3661 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3662 // Be sure to insert them before overlapping non-constant stores. 3663 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3664 for (int j = 0; j < num_tiles; j++) { 3665 jlong con = tiles[j]; 3666 jlong init = inits[j]; 3667 if (con == 0) continue; 3668 jint con0, con1; // split the constant, address-wise 3669 jint init0, init1; // split the init map, address-wise 3670 { union { jlong con; jint intcon[2]; } u; 3671 u.con = con; 3672 con0 = u.intcon[0]; 3673 con1 = u.intcon[1]; 3674 u.con = init; 3675 init0 = u.intcon[0]; 3676 init1 = u.intcon[1]; 3677 } 3678 3679 Node* old = nodes[j]; 3680 assert(old != NULL, "need the prior store"); 3681 intptr_t offset = (j * BytesPerLong); 3682 3683 bool split = !Matcher::isSimpleConstant64(con); 3684 3685 if (offset < header_size) { 3686 assert(offset + BytesPerInt >= header_size, "second int counts"); 3687 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3688 split = true; // only the second word counts 3689 // Example: int a[] = { 42 ... } 3690 } else if (con0 == 0 && init0 == -1) { 3691 split = true; // first word is covered by full inits 3692 // Example: int a[] = { ... foo(), 42 ... } 3693 } else if (con1 == 0 && init1 == -1) { 3694 split = true; // second word is covered by full inits 3695 // Example: int a[] = { ... 42, foo() ... } 3696 } 3697 3698 // Here's a case where init0 is neither 0 nor -1: 3699 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3700 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3701 // In this case the tile is not split; it is (jlong)42. 3702 // The big tile is stored down, and then the foo() value is inserted. 3703 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3704 3705 Node* ctl = old->in(MemNode::Control); 3706 Node* adr = make_raw_address(offset, phase); 3707 const TypePtr* atp = TypeRawPtr::BOTTOM; 3708 3709 // One or two coalesced stores to plop down. 3710 Node* st[2]; 3711 intptr_t off[2]; 3712 int nst = 0; 3713 if (!split) { 3714 ++new_long; 3715 off[nst] = offset; 3716 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3717 phase->longcon(con), T_LONG, MemNode::unordered); 3718 } else { 3719 // Omit either if it is a zero. 3720 if (con0 != 0) { 3721 ++new_int; 3722 off[nst] = offset; 3723 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3724 phase->intcon(con0), T_INT, MemNode::unordered); 3725 } 3726 if (con1 != 0) { 3727 ++new_int; 3728 offset += BytesPerInt; 3729 adr = make_raw_address(offset, phase); 3730 off[nst] = offset; 3731 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3732 phase->intcon(con1), T_INT, MemNode::unordered); 3733 } 3734 } 3735 3736 // Insert second store first, then the first before the second. 3737 // Insert each one just before any overlapping non-constant stores. 3738 while (nst > 0) { 3739 Node* st1 = st[--nst]; 3740 C->copy_node_notes_to(st1, old); 3741 st1 = phase->transform(st1); 3742 offset = off[nst]; 3743 assert(offset >= header_size, "do not smash header"); 3744 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3745 guarantee(ins_idx != 0, "must re-insert constant store"); 3746 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3747 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3748 set_req(--ins_idx, st1); 3749 else 3750 ins_req(ins_idx, st1); 3751 } 3752 } 3753 3754 if (PrintCompilation && WizardMode) 3755 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3756 old_subword, old_long, new_int, new_long); 3757 if (C->log() != NULL) 3758 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3759 old_subword, old_long, new_int, new_long); 3760 3761 // Clean up any remaining occurrences of zmem: 3762 remove_extra_zeroes(); 3763 } 3764 3765 // Explore forward from in(start) to find the first fully initialized 3766 // word, and return its offset. Skip groups of subword stores which 3767 // together initialize full words. If in(start) is itself part of a 3768 // fully initialized word, return the offset of in(start). If there 3769 // are no following full-word stores, or if something is fishy, return 3770 // a negative value. 3771 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3772 int int_map = 0; 3773 intptr_t int_map_off = 0; 3774 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3775 3776 for (uint i = start, limit = req(); i < limit; i++) { 3777 Node* st = in(i); 3778 3779 intptr_t st_off = get_store_offset(st, phase); 3780 if (st_off < 0) break; // return conservative answer 3781 3782 int st_size = st->as_Store()->memory_size(); 3783 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3784 return st_off; // we found a complete word init 3785 } 3786 3787 // update the map: 3788 3789 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); 3790 if (this_int_off != int_map_off) { 3791 // reset the map: 3792 int_map = 0; 3793 int_map_off = this_int_off; 3794 } 3795 3796 int subword_off = st_off - this_int_off; 3797 int_map |= right_n_bits(st_size) << subword_off; 3798 if ((int_map & FULL_MAP) == FULL_MAP) { 3799 return this_int_off; // we found a complete word init 3800 } 3801 3802 // Did this store hit or cross the word boundary? 3803 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); 3804 if (next_int_off == this_int_off + BytesPerInt) { 3805 // We passed the current int, without fully initializing it. 3806 int_map_off = next_int_off; 3807 int_map >>= BytesPerInt; 3808 } else if (next_int_off > this_int_off + BytesPerInt) { 3809 // We passed the current and next int. 3810 return this_int_off + BytesPerInt; 3811 } 3812 } 3813 3814 return -1; 3815 } 3816 3817 3818 // Called when the associated AllocateNode is expanded into CFG. 3819 // At this point, we may perform additional optimizations. 3820 // Linearize the stores by ascending offset, to make memory 3821 // activity as coherent as possible. 3822 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3823 intptr_t header_size, 3824 Node* size_in_bytes, 3825 PhaseGVN* phase) { 3826 assert(!is_complete(), "not already complete"); 3827 assert(stores_are_sane(phase), ""); 3828 assert(allocation() != NULL, "must be present"); 3829 3830 remove_extra_zeroes(); 3831 3832 if (ReduceFieldZeroing || ReduceBulkZeroing) 3833 // reduce instruction count for common initialization patterns 3834 coalesce_subword_stores(header_size, size_in_bytes, phase); 3835 3836 Node* zmem = zero_memory(); // initially zero memory state 3837 Node* inits = zmem; // accumulating a linearized chain of inits 3838 #ifdef ASSERT 3839 intptr_t first_offset = allocation()->minimum_header_size(); 3840 intptr_t last_init_off = first_offset; // previous init offset 3841 intptr_t last_init_end = first_offset; // previous init offset+size 3842 intptr_t last_tile_end = first_offset; // previous tile offset+size 3843 #endif 3844 intptr_t zeroes_done = header_size; 3845 3846 bool do_zeroing = true; // we might give up if inits are very sparse 3847 int big_init_gaps = 0; // how many large gaps have we seen? 3848 3849 if (ZeroTLAB) do_zeroing = false; 3850 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3851 3852 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3853 Node* st = in(i); 3854 intptr_t st_off = get_store_offset(st, phase); 3855 if (st_off < 0) 3856 break; // unknown junk in the inits 3857 if (st->in(MemNode::Memory) != zmem) 3858 break; // complicated store chains somehow in list 3859 3860 int st_size = st->as_Store()->memory_size(); 3861 intptr_t next_init_off = st_off + st_size; 3862 3863 if (do_zeroing && zeroes_done < next_init_off) { 3864 // See if this store needs a zero before it or under it. 3865 intptr_t zeroes_needed = st_off; 3866 3867 if (st_size < BytesPerInt) { 3868 // Look for subword stores which only partially initialize words. 3869 // If we find some, we must lay down some word-level zeroes first, 3870 // underneath the subword stores. 3871 // 3872 // Examples: 3873 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3874 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3875 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3876 // 3877 // Note: coalesce_subword_stores may have already done this, 3878 // if it was prompted by constant non-zero subword initializers. 3879 // But this case can still arise with non-constant stores. 3880 3881 intptr_t next_full_store = find_next_fullword_store(i, phase); 3882 3883 // In the examples above: 3884 // in(i) p q r s x y z 3885 // st_off 12 13 14 15 12 13 14 3886 // st_size 1 1 1 1 1 1 1 3887 // next_full_s. 12 16 16 16 16 16 16 3888 // z's_done 12 16 16 16 12 16 12 3889 // z's_needed 12 16 16 16 16 16 16 3890 // zsize 0 0 0 0 4 0 4 3891 if (next_full_store < 0) { 3892 // Conservative tack: Zero to end of current word. 3893 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); 3894 } else { 3895 // Zero to beginning of next fully initialized word. 3896 // Or, don't zero at all, if we are already in that word. 3897 assert(next_full_store >= zeroes_needed, "must go forward"); 3898 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3899 zeroes_needed = next_full_store; 3900 } 3901 } 3902 3903 if (zeroes_needed > zeroes_done) { 3904 intptr_t zsize = zeroes_needed - zeroes_done; 3905 // Do some incremental zeroing on rawmem, in parallel with inits. 3906 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3907 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3908 zeroes_done, zeroes_needed, 3909 phase); 3910 zeroes_done = zeroes_needed; 3911 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) 3912 do_zeroing = false; // leave the hole, next time 3913 } 3914 } 3915 3916 // Collect the store and move on: 3917 st->set_req(MemNode::Memory, inits); 3918 inits = st; // put it on the linearized chain 3919 set_req(i, zmem); // unhook from previous position 3920 3921 if (zeroes_done == st_off) 3922 zeroes_done = next_init_off; 3923 3924 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3925 3926 #ifdef ASSERT 3927 // Various order invariants. Weaker than stores_are_sane because 3928 // a large constant tile can be filled in by smaller non-constant stores. 3929 assert(st_off >= last_init_off, "inits do not reverse"); 3930 last_init_off = st_off; 3931 const Type* val = NULL; 3932 if (st_size >= BytesPerInt && 3933 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3934 (int)val->basic_type() < (int)T_OBJECT) { 3935 assert(st_off >= last_tile_end, "tiles do not overlap"); 3936 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3937 last_tile_end = MAX2(last_tile_end, next_init_off); 3938 } else { 3939 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); 3940 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3941 assert(st_off >= last_init_end, "inits do not overlap"); 3942 last_init_end = next_init_off; // it's a non-tile 3943 } 3944 #endif //ASSERT 3945 } 3946 3947 remove_extra_zeroes(); // clear out all the zmems left over 3948 add_req(inits); 3949 3950 if (!ZeroTLAB) { 3951 // If anything remains to be zeroed, zero it all now. 3952 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3953 // if it is the last unused 4 bytes of an instance, forget about it 3954 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3955 if (zeroes_done + BytesPerLong >= size_limit) { 3956 assert(allocation() != NULL, ""); 3957 if (allocation()->Opcode() == Op_Allocate) { 3958 Node* klass_node = allocation()->in(AllocateNode::KlassNode); 3959 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3960 if (zeroes_done == k->layout_helper()) 3961 zeroes_done = size_limit; 3962 } 3963 } 3964 if (zeroes_done < size_limit) { 3965 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3966 zeroes_done, size_in_bytes, phase); 3967 } 3968 } 3969 3970 set_complete(phase); 3971 return rawmem; 3972 } 3973 3974 3975 #ifdef ASSERT 3976 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3977 if (is_complete()) 3978 return true; // stores could be anything at this point 3979 assert(allocation() != NULL, "must be present"); 3980 intptr_t last_off = allocation()->minimum_header_size(); 3981 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3982 Node* st = in(i); 3983 intptr_t st_off = get_store_offset(st, phase); 3984 if (st_off < 0) continue; // ignore dead garbage 3985 if (last_off > st_off) { 3986 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 3987 this->dump(2); 3988 assert(false, "ascending store offsets"); 3989 return false; 3990 } 3991 last_off = st_off + st->as_Store()->memory_size(); 3992 } 3993 return true; 3994 } 3995 #endif //ASSERT 3996 3997 3998 3999 4000 //============================MergeMemNode===================================== 4001 // 4002 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4003 // contributing store or call operations. Each contributor provides the memory 4004 // state for a particular "alias type" (see Compile::alias_type). For example, 4005 // if a MergeMem has an input X for alias category #6, then any memory reference 4006 // to alias category #6 may use X as its memory state input, as an exact equivalent 4007 // to using the MergeMem as a whole. 4008 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4009 // 4010 // (Here, the <N> notation gives the index of the relevant adr_type.) 4011 // 4012 // In one special case (and more cases in the future), alias categories overlap. 4013 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4014 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 4015 // it is exactly equivalent to that state W: 4016 // MergeMem(<Bot>: W) <==> W 4017 // 4018 // Usually, the merge has more than one input. In that case, where inputs 4019 // overlap (i.e., one is Bot), the narrower alias type determines the memory 4020 // state for that type, and the wider alias type (Bot) fills in everywhere else: 4021 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4022 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4023 // 4024 // A merge can take a "wide" memory state as one of its narrow inputs. 4025 // This simply means that the merge observes out only the relevant parts of 4026 // the wide input. That is, wide memory states arriving at narrow merge inputs 4027 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4028 // 4029 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4030 // and that memory slices "leak through": 4031 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4032 // 4033 // But, in such a cascade, repeated memory slices can "block the leak": 4034 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4035 // 4036 // In the last example, Y is not part of the combined memory state of the 4037 // outermost MergeMem. The system must, of course, prevent unschedulable 4038 // memory states from arising, so you can be sure that the state Y is somehow 4039 // a precursor to state Y'. 4040 // 4041 // 4042 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4043 // of each MergeMemNode array are exactly the numerical alias indexes, including 4044 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4045 // Compile::alias_type (and kin) produce and manage these indexes. 4046 // 4047 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4048 // (Note that this provides quick access to the top node inside MergeMem methods, 4049 // without the need to reach out via TLS to Compile::current.) 4050 // 4051 // As a consequence of what was just described, a MergeMem that represents a full 4052 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4053 // containing all alias categories. 4054 // 4055 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4056 // 4057 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4058 // a memory state for the alias type <N>, or else the top node, meaning that 4059 // there is no particular input for that alias type. Note that the length of 4060 // a MergeMem is variable, and may be extended at any time to accommodate new 4061 // memory states at larger alias indexes. When merges grow, they are of course 4062 // filled with "top" in the unused in() positions. 4063 // 4064 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4065 // (Top was chosen because it works smoothly with passes like GCM.) 4066 // 4067 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4068 // the type of random VM bits like TLS references.) Since it is always the 4069 // first non-Bot memory slice, some low-level loops use it to initialize an 4070 // index variable: for (i = AliasIdxRaw; i < req(); i++). 4071 // 4072 // 4073 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4074 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4075 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 4076 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4077 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4078 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4079 // 4080 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4081 // really that different from the other memory inputs. An abbreviation called 4082 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4083 // 4084 // 4085 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4086 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4087 // that "emerges though" the base memory will be marked as excluding the alias types 4088 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 4089 // 4090 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4091 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4092 // 4093 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 4094 // (It is currently unimplemented.) As you can see, the resulting merge is 4095 // actually a disjoint union of memory states, rather than an overlay. 4096 // 4097 4098 //------------------------------MergeMemNode----------------------------------- 4099 Node* MergeMemNode::make_empty_memory() { 4100 Node* empty_memory = (Node*) Compile::current()->top(); 4101 assert(empty_memory->is_top(), "correct sentinel identity"); 4102 return empty_memory; 4103 } 4104 4105 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4106 init_class_id(Class_MergeMem); 4107 // all inputs are nullified in Node::Node(int) 4108 // set_input(0, NULL); // no control input 4109 4110 // Initialize the edges uniformly to top, for starters. 4111 Node* empty_mem = make_empty_memory(); 4112 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4113 init_req(i,empty_mem); 4114 } 4115 assert(empty_memory() == empty_mem, ""); 4116 4117 if( new_base != NULL && new_base->is_MergeMem() ) { 4118 MergeMemNode* mdef = new_base->as_MergeMem(); 4119 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4120 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4121 mms.set_memory(mms.memory2()); 4122 } 4123 assert(base_memory() == mdef->base_memory(), ""); 4124 } else { 4125 set_base_memory(new_base); 4126 } 4127 } 4128 4129 // Make a new, untransformed MergeMem with the same base as 'mem'. 4130 // If mem is itself a MergeMem, populate the result with the same edges. 4131 MergeMemNode* MergeMemNode::make(Node* mem) { 4132 return new MergeMemNode(mem); 4133 } 4134 4135 //------------------------------cmp-------------------------------------------- 4136 uint MergeMemNode::hash() const { return NO_HASH; } 4137 uint MergeMemNode::cmp( const Node &n ) const { 4138 return (&n == this); // Always fail except on self 4139 } 4140 4141 //------------------------------Identity--------------------------------------- 4142 Node* MergeMemNode::Identity(PhaseTransform *phase) { 4143 // Identity if this merge point does not record any interesting memory 4144 // disambiguations. 4145 Node* base_mem = base_memory(); 4146 Node* empty_mem = empty_memory(); 4147 if (base_mem != empty_mem) { // Memory path is not dead? 4148 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4149 Node* mem = in(i); 4150 if (mem != empty_mem && mem != base_mem) { 4151 return this; // Many memory splits; no change 4152 } 4153 } 4154 } 4155 return base_mem; // No memory splits; ID on the one true input 4156 } 4157 4158 //------------------------------Ideal------------------------------------------ 4159 // This method is invoked recursively on chains of MergeMem nodes 4160 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4161 // Remove chain'd MergeMems 4162 // 4163 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4164 // relative to the "in(Bot)". Since we are patching both at the same time, 4165 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4166 // but rewrite each "in(i)" relative to the new "in(Bot)". 4167 Node *progress = NULL; 4168 4169 4170 Node* old_base = base_memory(); 4171 Node* empty_mem = empty_memory(); 4172 if (old_base == empty_mem) 4173 return NULL; // Dead memory path. 4174 4175 MergeMemNode* old_mbase; 4176 if (old_base != NULL && old_base->is_MergeMem()) 4177 old_mbase = old_base->as_MergeMem(); 4178 else 4179 old_mbase = NULL; 4180 Node* new_base = old_base; 4181 4182 // simplify stacked MergeMems in base memory 4183 if (old_mbase) new_base = old_mbase->base_memory(); 4184 4185 // the base memory might contribute new slices beyond my req() 4186 if (old_mbase) grow_to_match(old_mbase); 4187 4188 // Look carefully at the base node if it is a phi. 4189 PhiNode* phi_base; 4190 if (new_base != NULL && new_base->is_Phi()) 4191 phi_base = new_base->as_Phi(); 4192 else 4193 phi_base = NULL; 4194 4195 Node* phi_reg = NULL; 4196 uint phi_len = (uint)-1; 4197 if (phi_base != NULL && !phi_base->is_copy()) { 4198 // do not examine phi if degraded to a copy 4199 phi_reg = phi_base->region(); 4200 phi_len = phi_base->req(); 4201 // see if the phi is unfinished 4202 for (uint i = 1; i < phi_len; i++) { 4203 if (phi_base->in(i) == NULL) { 4204 // incomplete phi; do not look at it yet! 4205 phi_reg = NULL; 4206 phi_len = (uint)-1; 4207 break; 4208 } 4209 } 4210 } 4211 4212 // Note: We do not call verify_sparse on entry, because inputs 4213 // can normalize to the base_memory via subsume_node or similar 4214 // mechanisms. This method repairs that damage. 4215 4216 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4217 4218 // Look at each slice. 4219 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4220 Node* old_in = in(i); 4221 // calculate the old memory value 4222 Node* old_mem = old_in; 4223 if (old_mem == empty_mem) old_mem = old_base; 4224 assert(old_mem == memory_at(i), ""); 4225 4226 // maybe update (reslice) the old memory value 4227 4228 // simplify stacked MergeMems 4229 Node* new_mem = old_mem; 4230 MergeMemNode* old_mmem; 4231 if (old_mem != NULL && old_mem->is_MergeMem()) 4232 old_mmem = old_mem->as_MergeMem(); 4233 else 4234 old_mmem = NULL; 4235 if (old_mmem == this) { 4236 // This can happen if loops break up and safepoints disappear. 4237 // A merge of BotPtr (default) with a RawPtr memory derived from a 4238 // safepoint can be rewritten to a merge of the same BotPtr with 4239 // the BotPtr phi coming into the loop. If that phi disappears 4240 // also, we can end up with a self-loop of the mergemem. 4241 // In general, if loops degenerate and memory effects disappear, 4242 // a mergemem can be left looking at itself. This simply means 4243 // that the mergemem's default should be used, since there is 4244 // no longer any apparent effect on this slice. 4245 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4246 // from start. Update the input to TOP. 4247 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4248 } 4249 else if (old_mmem != NULL) { 4250 new_mem = old_mmem->memory_at(i); 4251 } 4252 // else preceding memory was not a MergeMem 4253 4254 // replace equivalent phis (unfortunately, they do not GVN together) 4255 if (new_mem != NULL && new_mem != new_base && 4256 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4257 if (new_mem->is_Phi()) { 4258 PhiNode* phi_mem = new_mem->as_Phi(); 4259 for (uint i = 1; i < phi_len; i++) { 4260 if (phi_base->in(i) != phi_mem->in(i)) { 4261 phi_mem = NULL; 4262 break; 4263 } 4264 } 4265 if (phi_mem != NULL) { 4266 // equivalent phi nodes; revert to the def 4267 new_mem = new_base; 4268 } 4269 } 4270 } 4271 4272 // maybe store down a new value 4273 Node* new_in = new_mem; 4274 if (new_in == new_base) new_in = empty_mem; 4275 4276 if (new_in != old_in) { 4277 // Warning: Do not combine this "if" with the previous "if" 4278 // A memory slice might have be be rewritten even if it is semantically 4279 // unchanged, if the base_memory value has changed. 4280 set_req(i, new_in); 4281 progress = this; // Report progress 4282 } 4283 } 4284 4285 if (new_base != old_base) { 4286 set_req(Compile::AliasIdxBot, new_base); 4287 // Don't use set_base_memory(new_base), because we need to update du. 4288 assert(base_memory() == new_base, ""); 4289 progress = this; 4290 } 4291 4292 if( base_memory() == this ) { 4293 // a self cycle indicates this memory path is dead 4294 set_req(Compile::AliasIdxBot, empty_mem); 4295 } 4296 4297 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4298 // Recursion must occur after the self cycle check above 4299 if( base_memory()->is_MergeMem() ) { 4300 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4301 Node *m = phase->transform(new_mbase); // Rollup any cycles 4302 if( m != NULL && (m->is_top() || 4303 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 4304 // propagate rollup of dead cycle to self 4305 set_req(Compile::AliasIdxBot, empty_mem); 4306 } 4307 } 4308 4309 if( base_memory() == empty_mem ) { 4310 progress = this; 4311 // Cut inputs during Parse phase only. 4312 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4313 if( !can_reshape ) { 4314 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4315 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4316 } 4317 } 4318 } 4319 4320 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4321 // Check if PhiNode::Ideal's "Split phis through memory merges" 4322 // transform should be attempted. Look for this->phi->this cycle. 4323 uint merge_width = req(); 4324 if (merge_width > Compile::AliasIdxRaw) { 4325 PhiNode* phi = base_memory()->as_Phi(); 4326 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4327 if (phi->in(i) == this) { 4328 phase->is_IterGVN()->_worklist.push(phi); 4329 break; 4330 } 4331 } 4332 } 4333 } 4334 4335 assert(progress || verify_sparse(), "please, no dups of base"); 4336 return progress; 4337 } 4338 4339 //-------------------------set_base_memory------------------------------------- 4340 void MergeMemNode::set_base_memory(Node *new_base) { 4341 Node* empty_mem = empty_memory(); 4342 set_req(Compile::AliasIdxBot, new_base); 4343 assert(memory_at(req()) == new_base, "must set default memory"); 4344 // Clear out other occurrences of new_base: 4345 if (new_base != empty_mem) { 4346 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4347 if (in(i) == new_base) set_req(i, empty_mem); 4348 } 4349 } 4350 } 4351 4352 //------------------------------out_RegMask------------------------------------ 4353 const RegMask &MergeMemNode::out_RegMask() const { 4354 return RegMask::Empty; 4355 } 4356 4357 //------------------------------dump_spec-------------------------------------- 4358 #ifndef PRODUCT 4359 void MergeMemNode::dump_spec(outputStream *st) const { 4360 st->print(" {"); 4361 Node* base_mem = base_memory(); 4362 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4363 Node* mem = memory_at(i); 4364 if (mem == base_mem) { st->print(" -"); continue; } 4365 st->print( " N%d:", mem->_idx ); 4366 Compile::current()->get_adr_type(i)->dump_on(st); 4367 } 4368 st->print(" }"); 4369 } 4370 #endif // !PRODUCT 4371 4372 4373 #ifdef ASSERT 4374 static bool might_be_same(Node* a, Node* b) { 4375 if (a == b) return true; 4376 if (!(a->is_Phi() || b->is_Phi())) return false; 4377 // phis shift around during optimization 4378 return true; // pretty stupid... 4379 } 4380 4381 // verify a narrow slice (either incoming or outgoing) 4382 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4383 if (!VerifyAliases) return; // don't bother to verify unless requested 4384 if (is_error_reported()) return; // muzzle asserts when debugging an error 4385 if (Node::in_dump()) return; // muzzle asserts when printing 4386 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4387 assert(n != NULL, ""); 4388 // Elide intervening MergeMem's 4389 while (n->is_MergeMem()) { 4390 n = n->as_MergeMem()->memory_at(alias_idx); 4391 } 4392 Compile* C = Compile::current(); 4393 const TypePtr* n_adr_type = n->adr_type(); 4394 if (n == m->empty_memory()) { 4395 // Implicit copy of base_memory() 4396 } else if (n_adr_type != TypePtr::BOTTOM) { 4397 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4398 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4399 } else { 4400 // A few places like make_runtime_call "know" that VM calls are narrow, 4401 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4402 bool expected_wide_mem = false; 4403 if (n == m->base_memory()) { 4404 expected_wide_mem = true; 4405 } else if (alias_idx == Compile::AliasIdxRaw || 4406 n == m->memory_at(Compile::AliasIdxRaw)) { 4407 expected_wide_mem = true; 4408 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4409 // memory can "leak through" calls on channels that 4410 // are write-once. Allow this also. 4411 expected_wide_mem = true; 4412 } 4413 assert(expected_wide_mem, "expected narrow slice replacement"); 4414 } 4415 } 4416 #else // !ASSERT 4417 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4418 #endif 4419 4420 4421 //-----------------------------memory_at--------------------------------------- 4422 Node* MergeMemNode::memory_at(uint alias_idx) const { 4423 assert(alias_idx >= Compile::AliasIdxRaw || 4424 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4425 "must avoid base_memory and AliasIdxTop"); 4426 4427 // Otherwise, it is a narrow slice. 4428 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4429 Compile *C = Compile::current(); 4430 if (is_empty_memory(n)) { 4431 // the array is sparse; empty slots are the "top" node 4432 n = base_memory(); 4433 assert(Node::in_dump() 4434 || n == NULL || n->bottom_type() == Type::TOP 4435 || n->adr_type() == NULL // address is TOP 4436 || n->adr_type() == TypePtr::BOTTOM 4437 || n->adr_type() == TypeRawPtr::BOTTOM 4438 || Compile::current()->AliasLevel() == 0, 4439 "must be a wide memory"); 4440 // AliasLevel == 0 if we are organizing the memory states manually. 4441 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4442 } else { 4443 // make sure the stored slice is sane 4444 #ifdef ASSERT 4445 if (is_error_reported() || Node::in_dump()) { 4446 } else if (might_be_same(n, base_memory())) { 4447 // Give it a pass: It is a mostly harmless repetition of the base. 4448 // This can arise normally from node subsumption during optimization. 4449 } else { 4450 verify_memory_slice(this, alias_idx, n); 4451 } 4452 #endif 4453 } 4454 return n; 4455 } 4456 4457 //---------------------------set_memory_at------------------------------------- 4458 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4459 verify_memory_slice(this, alias_idx, n); 4460 Node* empty_mem = empty_memory(); 4461 if (n == base_memory()) n = empty_mem; // collapse default 4462 uint need_req = alias_idx+1; 4463 if (req() < need_req) { 4464 if (n == empty_mem) return; // already the default, so do not grow me 4465 // grow the sparse array 4466 do { 4467 add_req(empty_mem); 4468 } while (req() < need_req); 4469 } 4470 set_req( alias_idx, n ); 4471 } 4472 4473 4474 4475 //--------------------------iteration_setup------------------------------------ 4476 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4477 if (other != NULL) { 4478 grow_to_match(other); 4479 // invariant: the finite support of mm2 is within mm->req() 4480 #ifdef ASSERT 4481 for (uint i = req(); i < other->req(); i++) { 4482 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4483 } 4484 #endif 4485 } 4486 // Replace spurious copies of base_memory by top. 4487 Node* base_mem = base_memory(); 4488 if (base_mem != NULL && !base_mem->is_top()) { 4489 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4490 if (in(i) == base_mem) 4491 set_req(i, empty_memory()); 4492 } 4493 } 4494 } 4495 4496 //---------------------------grow_to_match------------------------------------- 4497 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4498 Node* empty_mem = empty_memory(); 4499 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4500 // look for the finite support of the other memory 4501 for (uint i = other->req(); --i >= req(); ) { 4502 if (other->in(i) != empty_mem) { 4503 uint new_len = i+1; 4504 while (req() < new_len) add_req(empty_mem); 4505 break; 4506 } 4507 } 4508 } 4509 4510 //---------------------------verify_sparse------------------------------------- 4511 #ifndef PRODUCT 4512 bool MergeMemNode::verify_sparse() const { 4513 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4514 Node* base_mem = base_memory(); 4515 // The following can happen in degenerate cases, since empty==top. 4516 if (is_empty_memory(base_mem)) return true; 4517 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4518 assert(in(i) != NULL, "sane slice"); 4519 if (in(i) == base_mem) return false; // should have been the sentinel value! 4520 } 4521 return true; 4522 } 4523 4524 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4525 Node* n; 4526 n = mm->in(idx); 4527 if (mem == n) return true; // might be empty_memory() 4528 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4529 if (mem == n) return true; 4530 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4531 if (mem == n) return true; 4532 if (n == NULL) break; 4533 } 4534 return false; 4535 } 4536 #endif // !PRODUCT