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(Compile *C, 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(Compile *C, 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 Compile* C = gvn.C; 2021 Node *ctl = NULL; 2022 // sanity check the alias category against the created node type 2023 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2024 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2025 #ifdef _LP64 2026 if (adr_type->is_ptr_to_narrowklass()) { 2027 assert(UseCompressedClassPointers, "no compressed klasses"); 2028 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2029 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2030 } 2031 #endif 2032 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2033 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2034 } 2035 2036 //------------------------------Value------------------------------------------ 2037 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { 2038 return klass_value_common(phase); 2039 } 2040 2041 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const { 2042 // Either input is TOP ==> the result is TOP 2043 const Type *t1 = phase->type( in(MemNode::Memory) ); 2044 if (t1 == Type::TOP) return Type::TOP; 2045 Node *adr = in(MemNode::Address); 2046 const Type *t2 = phase->type( adr ); 2047 if (t2 == Type::TOP) return Type::TOP; 2048 const TypePtr *tp = t2->is_ptr(); 2049 if (TypePtr::above_centerline(tp->ptr()) || 2050 tp->ptr() == TypePtr::Null) return Type::TOP; 2051 2052 // Return a more precise klass, if possible 2053 const TypeInstPtr *tinst = tp->isa_instptr(); 2054 if (tinst != NULL) { 2055 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2056 int offset = tinst->offset(); 2057 if (ik == phase->C->env()->Class_klass() 2058 && (offset == java_lang_Class::klass_offset_in_bytes() || 2059 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2060 // We are loading a special hidden field from a Class mirror object, 2061 // the field which points to the VM's Klass metaobject. 2062 ciType* t = tinst->java_mirror_type(); 2063 // java_mirror_type returns non-null for compile-time Class constants. 2064 if (t != NULL) { 2065 // constant oop => constant klass 2066 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2067 if (t->is_void()) { 2068 // We cannot create a void array. Since void is a primitive type return null 2069 // klass. Users of this result need to do a null check on the returned klass. 2070 return TypePtr::NULL_PTR; 2071 } 2072 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2073 } 2074 if (!t->is_klass()) { 2075 // a primitive Class (e.g., int.class) has NULL for a klass field 2076 return TypePtr::NULL_PTR; 2077 } 2078 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2079 return TypeKlassPtr::make(t->as_klass()); 2080 } 2081 // non-constant mirror, so we can't tell what's going on 2082 } 2083 if( !ik->is_loaded() ) 2084 return _type; // Bail out if not loaded 2085 if (offset == oopDesc::klass_offset_in_bytes()) { 2086 if (tinst->klass_is_exact()) { 2087 return TypeKlassPtr::make(ik); 2088 } 2089 // See if we can become precise: no subklasses and no interface 2090 // (Note: We need to support verified interfaces.) 2091 if (!ik->is_interface() && !ik->has_subklass()) { 2092 //assert(!UseExactTypes, "this code should be useless with exact types"); 2093 // Add a dependence; if any subclass added we need to recompile 2094 if (!ik->is_final()) { 2095 // %%% should use stronger assert_unique_concrete_subtype instead 2096 phase->C->dependencies()->assert_leaf_type(ik); 2097 } 2098 // Return precise klass 2099 return TypeKlassPtr::make(ik); 2100 } 2101 2102 // Return root of possible klass 2103 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2104 } 2105 } 2106 2107 // Check for loading klass from an array 2108 const TypeAryPtr *tary = tp->isa_aryptr(); 2109 if( tary != NULL ) { 2110 ciKlass *tary_klass = tary->klass(); 2111 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2112 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2113 if (tary->klass_is_exact()) { 2114 return TypeKlassPtr::make(tary_klass); 2115 } 2116 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2117 // If the klass is an object array, we defer the question to the 2118 // array component klass. 2119 if( ak->is_obj_array_klass() ) { 2120 assert( ak->is_loaded(), "" ); 2121 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2122 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2123 ciInstanceKlass* ik = base_k->as_instance_klass(); 2124 // See if we can become precise: no subklasses and no interface 2125 if (!ik->is_interface() && !ik->has_subklass()) { 2126 //assert(!UseExactTypes, "this code should be useless with exact types"); 2127 // Add a dependence; if any subclass added we need to recompile 2128 if (!ik->is_final()) { 2129 phase->C->dependencies()->assert_leaf_type(ik); 2130 } 2131 // Return precise array klass 2132 return TypeKlassPtr::make(ak); 2133 } 2134 } 2135 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2136 } else { // Found a type-array? 2137 //assert(!UseExactTypes, "this code should be useless with exact types"); 2138 assert( ak->is_type_array_klass(), "" ); 2139 return TypeKlassPtr::make(ak); // These are always precise 2140 } 2141 } 2142 } 2143 2144 // Check for loading klass from an array klass 2145 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2146 if (tkls != NULL && !StressReflectiveCode) { 2147 ciKlass* klass = tkls->klass(); 2148 if( !klass->is_loaded() ) 2149 return _type; // Bail out if not loaded 2150 if( klass->is_obj_array_klass() && 2151 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2152 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2153 // // Always returning precise element type is incorrect, 2154 // // e.g., element type could be object and array may contain strings 2155 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2156 2157 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2158 // according to the element type's subclassing. 2159 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2160 } 2161 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2162 tkls->offset() == in_bytes(Klass::super_offset())) { 2163 ciKlass* sup = klass->as_instance_klass()->super(); 2164 // The field is Klass::_super. Return its (constant) value. 2165 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2166 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2167 } 2168 } 2169 2170 // Bailout case 2171 return LoadNode::Value(phase); 2172 } 2173 2174 //------------------------------Identity--------------------------------------- 2175 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2176 // Also feed through the klass in Allocate(...klass...)._klass. 2177 Node* LoadKlassNode::Identity( PhaseTransform *phase ) { 2178 return klass_identity_common(phase); 2179 } 2180 2181 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) { 2182 Node* x = LoadNode::Identity(phase); 2183 if (x != this) return x; 2184 2185 // Take apart the address into an oop and and offset. 2186 // Return 'this' if we cannot. 2187 Node* adr = in(MemNode::Address); 2188 intptr_t offset = 0; 2189 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2190 if (base == NULL) return this; 2191 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2192 if (toop == NULL) return this; 2193 2194 // We can fetch the klass directly through an AllocateNode. 2195 // This works even if the klass is not constant (clone or newArray). 2196 if (offset == oopDesc::klass_offset_in_bytes()) { 2197 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2198 if (allocated_klass != NULL) { 2199 return allocated_klass; 2200 } 2201 } 2202 2203 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2204 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass. 2205 // See inline_native_Class_query for occurrences of these patterns. 2206 // Java Example: x.getClass().isAssignableFrom(y) 2207 // Java Example: Array.newInstance(x.getClass().getComponentType(), n) 2208 // 2209 // This improves reflective code, often making the Class 2210 // mirror go completely dead. (Current exception: Class 2211 // mirrors may appear in debug info, but we could clean them out by 2212 // introducing a new debug info operator for Klass*.java_mirror). 2213 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2214 && (offset == java_lang_Class::klass_offset_in_bytes() || 2215 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2216 // We are loading a special hidden field from a Class mirror, 2217 // the field which points to its Klass or ArrayKlass metaobject. 2218 if (base->is_Load()) { 2219 Node* adr2 = base->in(MemNode::Address); 2220 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2221 if (tkls != NULL && !tkls->empty() 2222 && (tkls->klass()->is_instance_klass() || 2223 tkls->klass()->is_array_klass()) 2224 && adr2->is_AddP() 2225 ) { 2226 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2227 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2228 mirror_field = in_bytes(ArrayKlass::component_mirror_offset()); 2229 } 2230 if (tkls->offset() == mirror_field) { 2231 return adr2->in(AddPNode::Base); 2232 } 2233 } 2234 } 2235 } 2236 2237 return this; 2238 } 2239 2240 2241 //------------------------------Value------------------------------------------ 2242 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const { 2243 const Type *t = klass_value_common(phase); 2244 if (t == Type::TOP) 2245 return t; 2246 2247 return t->make_narrowklass(); 2248 } 2249 2250 //------------------------------Identity--------------------------------------- 2251 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2252 // Also feed through the klass in Allocate(...klass...)._klass. 2253 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) { 2254 Node *x = klass_identity_common(phase); 2255 2256 const Type *t = phase->type( x ); 2257 if( t == Type::TOP ) return x; 2258 if( t->isa_narrowklass()) return x; 2259 assert (!t->isa_narrowoop(), "no narrow oop here"); 2260 2261 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2262 } 2263 2264 //------------------------------Value----------------------------------------- 2265 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { 2266 // Either input is TOP ==> the result is TOP 2267 const Type *t1 = phase->type( in(MemNode::Memory) ); 2268 if( t1 == Type::TOP ) return Type::TOP; 2269 Node *adr = in(MemNode::Address); 2270 const Type *t2 = phase->type( adr ); 2271 if( t2 == Type::TOP ) return Type::TOP; 2272 const TypePtr *tp = t2->is_ptr(); 2273 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2274 const TypeAryPtr *tap = tp->isa_aryptr(); 2275 if( !tap ) return _type; 2276 return tap->size(); 2277 } 2278 2279 //-------------------------------Ideal--------------------------------------- 2280 // Feed through the length in AllocateArray(...length...)._length. 2281 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2282 Node* p = MemNode::Ideal_common(phase, can_reshape); 2283 if (p) return (p == NodeSentinel) ? NULL : p; 2284 2285 // Take apart the address into an oop and and offset. 2286 // Return 'this' if we cannot. 2287 Node* adr = in(MemNode::Address); 2288 intptr_t offset = 0; 2289 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2290 if (base == NULL) return NULL; 2291 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2292 if (tary == NULL) return NULL; 2293 2294 // We can fetch the length directly through an AllocateArrayNode. 2295 // This works even if the length is not constant (clone or newArray). 2296 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2297 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2298 if (alloc != NULL) { 2299 Node* allocated_length = alloc->Ideal_length(); 2300 Node* len = alloc->make_ideal_length(tary, phase); 2301 if (allocated_length != len) { 2302 // New CastII improves on this. 2303 return len; 2304 } 2305 } 2306 } 2307 2308 return NULL; 2309 } 2310 2311 //------------------------------Identity--------------------------------------- 2312 // Feed through the length in AllocateArray(...length...)._length. 2313 Node* LoadRangeNode::Identity( PhaseTransform *phase ) { 2314 Node* x = LoadINode::Identity(phase); 2315 if (x != this) return x; 2316 2317 // Take apart the address into an oop and and offset. 2318 // Return 'this' if we cannot. 2319 Node* adr = in(MemNode::Address); 2320 intptr_t offset = 0; 2321 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2322 if (base == NULL) return this; 2323 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2324 if (tary == NULL) return this; 2325 2326 // We can fetch the length directly through an AllocateArrayNode. 2327 // This works even if the length is not constant (clone or newArray). 2328 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2329 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2330 if (alloc != NULL) { 2331 Node* allocated_length = alloc->Ideal_length(); 2332 // Do not allow make_ideal_length to allocate a CastII node. 2333 Node* len = alloc->make_ideal_length(tary, phase, false); 2334 if (allocated_length == len) { 2335 // Return allocated_length only if it would not be improved by a CastII. 2336 return allocated_length; 2337 } 2338 } 2339 } 2340 2341 return this; 2342 2343 } 2344 2345 //============================================================================= 2346 //---------------------------StoreNode::make----------------------------------- 2347 // Polymorphic factory method: 2348 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2349 assert((mo == unordered || mo == release), "unexpected"); 2350 Compile* C = gvn.C; 2351 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2352 ctl != NULL, "raw memory operations should have control edge"); 2353 2354 switch (bt) { 2355 case T_BOOLEAN: 2356 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2357 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2358 case T_CHAR: 2359 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2360 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2361 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2362 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2363 case T_METADATA: 2364 case T_ADDRESS: 2365 case T_OBJECT: 2366 #ifdef _LP64 2367 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2368 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2369 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2370 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2371 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2372 adr->bottom_type()->isa_rawptr())) { 2373 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2374 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2375 } 2376 #endif 2377 { 2378 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2379 } 2380 } 2381 ShouldNotReachHere(); 2382 return (StoreNode*)NULL; 2383 } 2384 2385 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2386 bool require_atomic = true; 2387 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2388 } 2389 2390 StoreDNode* StoreDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2391 bool require_atomic = true; 2392 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2393 } 2394 2395 2396 //--------------------------bottom_type---------------------------------------- 2397 const Type *StoreNode::bottom_type() const { 2398 return Type::MEMORY; 2399 } 2400 2401 //------------------------------hash------------------------------------------- 2402 uint StoreNode::hash() const { 2403 // unroll addition of interesting fields 2404 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2405 2406 // Since they are not commoned, do not hash them: 2407 return NO_HASH; 2408 } 2409 2410 //------------------------------Ideal------------------------------------------ 2411 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2412 // When a store immediately follows a relevant allocation/initialization, 2413 // try to capture it into the initialization, or hoist it above. 2414 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2415 Node* p = MemNode::Ideal_common(phase, can_reshape); 2416 if (p) return (p == NodeSentinel) ? NULL : p; 2417 2418 Node* mem = in(MemNode::Memory); 2419 Node* address = in(MemNode::Address); 2420 2421 // Back-to-back stores to same address? Fold em up. Generally 2422 // unsafe if I have intervening uses... Also disallowed for StoreCM 2423 // since they must follow each StoreP operation. Redundant StoreCMs 2424 // are eliminated just before matching in final_graph_reshape. 2425 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) && 2426 mem->Opcode() != Op_StoreCM) { 2427 // Looking at a dead closed cycle of memory? 2428 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2429 2430 assert(Opcode() == mem->Opcode() || 2431 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, 2432 "no mismatched stores, except on raw memory"); 2433 2434 if (mem->outcnt() == 1 && // check for intervening uses 2435 mem->as_Store()->memory_size() <= this->memory_size()) { 2436 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. 2437 // For example, 'mem' might be the final state at a conditional return. 2438 // Or, 'mem' might be used by some node which is live at the same time 2439 // 'this' is live, which might be unschedulable. So, require exactly 2440 // ONE user, the 'this' store, until such time as we clone 'mem' for 2441 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). 2442 if (can_reshape) { // (%%% is this an anachronism?) 2443 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), 2444 phase->is_IterGVN()); 2445 } else { 2446 // It's OK to do this in the parser, since DU info is always accurate, 2447 // and the parser always refers to nodes via SafePointNode maps. 2448 set_req(MemNode::Memory, mem->in(MemNode::Memory)); 2449 } 2450 return this; 2451 } 2452 } 2453 2454 // Capture an unaliased, unconditional, simple store into an initializer. 2455 // Or, if it is independent of the allocation, hoist it above the allocation. 2456 if (ReduceFieldZeroing && /*can_reshape &&*/ 2457 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2458 InitializeNode* init = mem->in(0)->as_Initialize(); 2459 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2460 if (offset > 0) { 2461 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2462 // If the InitializeNode captured me, it made a raw copy of me, 2463 // and I need to disappear. 2464 if (moved != NULL) { 2465 // %%% hack to ensure that Ideal returns a new node: 2466 mem = MergeMemNode::make(phase->C, mem); 2467 return mem; // fold me away 2468 } 2469 } 2470 } 2471 2472 return NULL; // No further progress 2473 } 2474 2475 //------------------------------Value----------------------------------------- 2476 const Type *StoreNode::Value( PhaseTransform *phase ) const { 2477 // Either input is TOP ==> the result is TOP 2478 const Type *t1 = phase->type( in(MemNode::Memory) ); 2479 if( t1 == Type::TOP ) return Type::TOP; 2480 const Type *t2 = phase->type( in(MemNode::Address) ); 2481 if( t2 == Type::TOP ) return Type::TOP; 2482 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2483 if( t3 == Type::TOP ) return Type::TOP; 2484 return Type::MEMORY; 2485 } 2486 2487 //------------------------------Identity--------------------------------------- 2488 // Remove redundant stores: 2489 // Store(m, p, Load(m, p)) changes to m. 2490 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2491 Node *StoreNode::Identity( PhaseTransform *phase ) { 2492 Node* mem = in(MemNode::Memory); 2493 Node* adr = in(MemNode::Address); 2494 Node* val = in(MemNode::ValueIn); 2495 2496 // Load then Store? Then the Store is useless 2497 if (val->is_Load() && 2498 val->in(MemNode::Address)->eqv_uncast(adr) && 2499 val->in(MemNode::Memory )->eqv_uncast(mem) && 2500 val->as_Load()->store_Opcode() == Opcode()) { 2501 return mem; 2502 } 2503 2504 // Two stores in a row of the same value? 2505 if (mem->is_Store() && 2506 mem->in(MemNode::Address)->eqv_uncast(adr) && 2507 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2508 mem->Opcode() == Opcode()) { 2509 return mem; 2510 } 2511 2512 // Store of zero anywhere into a freshly-allocated object? 2513 // Then the store is useless. 2514 // (It must already have been captured by the InitializeNode.) 2515 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2516 // a newly allocated object is already all-zeroes everywhere 2517 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2518 return mem; 2519 } 2520 2521 // the store may also apply to zero-bits in an earlier object 2522 Node* prev_mem = find_previous_store(phase); 2523 // Steps (a), (b): Walk past independent stores to find an exact match. 2524 if (prev_mem != NULL) { 2525 Node* prev_val = can_see_stored_value(prev_mem, phase); 2526 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2527 // prev_val and val might differ by a cast; it would be good 2528 // to keep the more informative of the two. 2529 return mem; 2530 } 2531 } 2532 } 2533 2534 return this; 2535 } 2536 2537 //------------------------------match_edge------------------------------------- 2538 // Do we Match on this edge index or not? Match only memory & value 2539 uint StoreNode::match_edge(uint idx) const { 2540 return idx == MemNode::Address || idx == MemNode::ValueIn; 2541 } 2542 2543 //------------------------------cmp-------------------------------------------- 2544 // Do not common stores up together. They generally have to be split 2545 // back up anyways, so do not bother. 2546 uint StoreNode::cmp( const Node &n ) const { 2547 return (&n == this); // Always fail except on self 2548 } 2549 2550 //------------------------------Ideal_masked_input----------------------------- 2551 // Check for a useless mask before a partial-word store 2552 // (StoreB ... (AndI valIn conIa) ) 2553 // If (conIa & mask == mask) this simplifies to 2554 // (StoreB ... (valIn) ) 2555 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2556 Node *val = in(MemNode::ValueIn); 2557 if( val->Opcode() == Op_AndI ) { 2558 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2559 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2560 set_req(MemNode::ValueIn, val->in(1)); 2561 return this; 2562 } 2563 } 2564 return NULL; 2565 } 2566 2567 2568 //------------------------------Ideal_sign_extended_input---------------------- 2569 // Check for useless sign-extension before a partial-word store 2570 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2571 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2572 // (StoreB ... (valIn) ) 2573 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2574 Node *val = in(MemNode::ValueIn); 2575 if( val->Opcode() == Op_RShiftI ) { 2576 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2577 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2578 Node *shl = val->in(1); 2579 if( shl->Opcode() == Op_LShiftI ) { 2580 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2581 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2582 set_req(MemNode::ValueIn, shl->in(1)); 2583 return this; 2584 } 2585 } 2586 } 2587 } 2588 return NULL; 2589 } 2590 2591 //------------------------------value_never_loaded----------------------------------- 2592 // Determine whether there are any possible loads of the value stored. 2593 // For simplicity, we actually check if there are any loads from the 2594 // address stored to, not just for loads of the value stored by this node. 2595 // 2596 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2597 Node *adr = in(Address); 2598 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2599 if (adr_oop == NULL) 2600 return false; 2601 if (!adr_oop->is_known_instance_field()) 2602 return false; // if not a distinct instance, there may be aliases of the address 2603 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2604 Node *use = adr->fast_out(i); 2605 int opc = use->Opcode(); 2606 if (use->is_Load() || use->is_LoadStore()) { 2607 return false; 2608 } 2609 } 2610 return true; 2611 } 2612 2613 //============================================================================= 2614 //------------------------------Ideal------------------------------------------ 2615 // If the store is from an AND mask that leaves the low bits untouched, then 2616 // we can skip the AND operation. If the store is from a sign-extension 2617 // (a left shift, then right shift) we can skip both. 2618 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2619 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2620 if( progress != NULL ) return progress; 2621 2622 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2623 if( progress != NULL ) return progress; 2624 2625 // Finally check the default case 2626 return StoreNode::Ideal(phase, can_reshape); 2627 } 2628 2629 //============================================================================= 2630 //------------------------------Ideal------------------------------------------ 2631 // If the store is from an AND mask that leaves the low bits untouched, then 2632 // we can skip the AND operation 2633 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2634 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2635 if( progress != NULL ) return progress; 2636 2637 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2638 if( progress != NULL ) return progress; 2639 2640 // Finally check the default case 2641 return StoreNode::Ideal(phase, can_reshape); 2642 } 2643 2644 //============================================================================= 2645 //------------------------------Identity--------------------------------------- 2646 Node *StoreCMNode::Identity( PhaseTransform *phase ) { 2647 // No need to card mark when storing a null ptr 2648 Node* my_store = in(MemNode::OopStore); 2649 if (my_store->is_Store()) { 2650 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2651 if( t1 == TypePtr::NULL_PTR ) { 2652 return in(MemNode::Memory); 2653 } 2654 } 2655 return this; 2656 } 2657 2658 //============================================================================= 2659 //------------------------------Ideal--------------------------------------- 2660 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2661 Node* progress = StoreNode::Ideal(phase, can_reshape); 2662 if (progress != NULL) return progress; 2663 2664 Node* my_store = in(MemNode::OopStore); 2665 if (my_store->is_MergeMem()) { 2666 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2667 set_req(MemNode::OopStore, mem); 2668 return this; 2669 } 2670 2671 return NULL; 2672 } 2673 2674 //------------------------------Value----------------------------------------- 2675 const Type *StoreCMNode::Value( PhaseTransform *phase ) const { 2676 // Either input is TOP ==> the result is TOP 2677 const Type *t = phase->type( in(MemNode::Memory) ); 2678 if( t == Type::TOP ) return Type::TOP; 2679 t = phase->type( in(MemNode::Address) ); 2680 if( t == Type::TOP ) return Type::TOP; 2681 t = phase->type( in(MemNode::ValueIn) ); 2682 if( t == Type::TOP ) return Type::TOP; 2683 // If extra input is TOP ==> the result is TOP 2684 t = phase->type( in(MemNode::OopStore) ); 2685 if( t == Type::TOP ) return Type::TOP; 2686 2687 return StoreNode::Value( phase ); 2688 } 2689 2690 2691 //============================================================================= 2692 //----------------------------------SCMemProjNode------------------------------ 2693 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const 2694 { 2695 return bottom_type(); 2696 } 2697 2698 //============================================================================= 2699 //----------------------------------LoadStoreNode------------------------------ 2700 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2701 : Node(required), 2702 _type(rt), 2703 _adr_type(at) 2704 { 2705 init_req(MemNode::Control, c ); 2706 init_req(MemNode::Memory , mem); 2707 init_req(MemNode::Address, adr); 2708 init_req(MemNode::ValueIn, val); 2709 init_class_id(Class_LoadStore); 2710 } 2711 2712 uint LoadStoreNode::ideal_reg() const { 2713 return _type->ideal_reg(); 2714 } 2715 2716 bool LoadStoreNode::result_not_used() const { 2717 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2718 Node *x = fast_out(i); 2719 if (x->Opcode() == Op_SCMemProj) continue; 2720 return false; 2721 } 2722 return true; 2723 } 2724 2725 uint LoadStoreNode::size_of() const { return sizeof(*this); } 2726 2727 //============================================================================= 2728 //----------------------------------LoadStoreConditionalNode-------------------- 2729 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 2730 init_req(ExpectedIn, ex ); 2731 } 2732 2733 //============================================================================= 2734 //-------------------------------adr_type-------------------------------------- 2735 // Do we Match on this edge index or not? Do not match memory 2736 const TypePtr* ClearArrayNode::adr_type() const { 2737 Node *adr = in(3); 2738 return MemNode::calculate_adr_type(adr->bottom_type()); 2739 } 2740 2741 //------------------------------match_edge------------------------------------- 2742 // Do we Match on this edge index or not? Do not match memory 2743 uint ClearArrayNode::match_edge(uint idx) const { 2744 return idx > 1; 2745 } 2746 2747 //------------------------------Identity--------------------------------------- 2748 // Clearing a zero length array does nothing 2749 Node *ClearArrayNode::Identity( PhaseTransform *phase ) { 2750 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2751 } 2752 2753 //------------------------------Idealize--------------------------------------- 2754 // Clearing a short array is faster with stores 2755 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2756 const int unit = BytesPerLong; 2757 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2758 if (!t) return NULL; 2759 if (!t->is_con()) return NULL; 2760 intptr_t raw_count = t->get_con(); 2761 intptr_t size = raw_count; 2762 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2763 // Clearing nothing uses the Identity call. 2764 // Negative clears are possible on dead ClearArrays 2765 // (see jck test stmt114.stmt11402.val). 2766 if (size <= 0 || size % unit != 0) return NULL; 2767 intptr_t count = size / unit; 2768 // Length too long; use fast hardware clear 2769 if (size > Matcher::init_array_short_size) return NULL; 2770 Node *mem = in(1); 2771 if( phase->type(mem)==Type::TOP ) return NULL; 2772 Node *adr = in(3); 2773 const Type* at = phase->type(adr); 2774 if( at==Type::TOP ) return NULL; 2775 const TypePtr* atp = at->isa_ptr(); 2776 // adjust atp to be the correct array element address type 2777 if (atp == NULL) atp = TypePtr::BOTTOM; 2778 else atp = atp->add_offset(Type::OffsetBot); 2779 // Get base for derived pointer purposes 2780 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2781 Node *base = adr->in(1); 2782 2783 Node *zero = phase->makecon(TypeLong::ZERO); 2784 Node *off = phase->MakeConX(BytesPerLong); 2785 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2786 count--; 2787 while( count-- ) { 2788 mem = phase->transform(mem); 2789 adr = phase->transform(new AddPNode(base,adr,off)); 2790 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2791 } 2792 return mem; 2793 } 2794 2795 //----------------------------step_through---------------------------------- 2796 // Return allocation input memory edge if it is different instance 2797 // or itself if it is the one we are looking for. 2798 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2799 Node* n = *np; 2800 assert(n->is_ClearArray(), "sanity"); 2801 intptr_t offset; 2802 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2803 // This method is called only before Allocate nodes are expanded during 2804 // macro nodes expansion. Before that ClearArray nodes are only generated 2805 // in LibraryCallKit::generate_arraycopy() which follows allocations. 2806 assert(alloc != NULL, "should have allocation"); 2807 if (alloc->_idx == instance_id) { 2808 // Can not bypass initialization of the instance we are looking for. 2809 return false; 2810 } 2811 // Otherwise skip it. 2812 InitializeNode* init = alloc->initialization(); 2813 if (init != NULL) 2814 *np = init->in(TypeFunc::Memory); 2815 else 2816 *np = alloc->in(TypeFunc::Memory); 2817 return true; 2818 } 2819 2820 //----------------------------clear_memory------------------------------------- 2821 // Generate code to initialize object storage to zero. 2822 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2823 intptr_t start_offset, 2824 Node* end_offset, 2825 PhaseGVN* phase) { 2826 Compile* C = phase->C; 2827 intptr_t offset = start_offset; 2828 2829 int unit = BytesPerLong; 2830 if ((offset % unit) != 0) { 2831 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 2832 adr = phase->transform(adr); 2833 const TypePtr* atp = TypeRawPtr::BOTTOM; 2834 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2835 mem = phase->transform(mem); 2836 offset += BytesPerInt; 2837 } 2838 assert((offset % unit) == 0, ""); 2839 2840 // Initialize the remaining stuff, if any, with a ClearArray. 2841 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2842 } 2843 2844 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2845 Node* start_offset, 2846 Node* end_offset, 2847 PhaseGVN* phase) { 2848 if (start_offset == end_offset) { 2849 // nothing to do 2850 return mem; 2851 } 2852 2853 Compile* C = phase->C; 2854 int unit = BytesPerLong; 2855 Node* zbase = start_offset; 2856 Node* zend = end_offset; 2857 2858 // Scale to the unit required by the CPU: 2859 if (!Matcher::init_array_count_is_in_bytes) { 2860 Node* shift = phase->intcon(exact_log2(unit)); 2861 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 2862 zend = phase->transform(new URShiftXNode(zend, shift) ); 2863 } 2864 2865 // Bulk clear double-words 2866 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 2867 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 2868 mem = new ClearArrayNode(ctl, mem, zsize, adr); 2869 return phase->transform(mem); 2870 } 2871 2872 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2873 intptr_t start_offset, 2874 intptr_t end_offset, 2875 PhaseGVN* phase) { 2876 if (start_offset == end_offset) { 2877 // nothing to do 2878 return mem; 2879 } 2880 2881 Compile* C = phase->C; 2882 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2883 intptr_t done_offset = end_offset; 2884 if ((done_offset % BytesPerLong) != 0) { 2885 done_offset -= BytesPerInt; 2886 } 2887 if (done_offset > start_offset) { 2888 mem = clear_memory(ctl, mem, dest, 2889 start_offset, phase->MakeConX(done_offset), phase); 2890 } 2891 if (done_offset < end_offset) { // emit the final 32-bit store 2892 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 2893 adr = phase->transform(adr); 2894 const TypePtr* atp = TypeRawPtr::BOTTOM; 2895 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2896 mem = phase->transform(mem); 2897 done_offset += BytesPerInt; 2898 } 2899 assert(done_offset == end_offset, ""); 2900 return mem; 2901 } 2902 2903 //============================================================================= 2904 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2905 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2906 _adr_type(C->get_adr_type(alias_idx)) 2907 { 2908 init_class_id(Class_MemBar); 2909 Node* top = C->top(); 2910 init_req(TypeFunc::I_O,top); 2911 init_req(TypeFunc::FramePtr,top); 2912 init_req(TypeFunc::ReturnAdr,top); 2913 if (precedent != NULL) 2914 init_req(TypeFunc::Parms, precedent); 2915 } 2916 2917 //------------------------------cmp-------------------------------------------- 2918 uint MemBarNode::hash() const { return NO_HASH; } 2919 uint MemBarNode::cmp( const Node &n ) const { 2920 return (&n == this); // Always fail except on self 2921 } 2922 2923 //------------------------------make------------------------------------------- 2924 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2925 switch (opcode) { 2926 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 2927 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 2928 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 2929 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 2930 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 2931 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 2932 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 2933 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 2934 case Op_Initialize: return new InitializeNode(C, atp, pn); 2935 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 2936 default: ShouldNotReachHere(); return NULL; 2937 } 2938 } 2939 2940 //------------------------------Ideal------------------------------------------ 2941 // Return a node which is more "ideal" than the current node. Strip out 2942 // control copies 2943 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2944 if (remove_dead_region(phase, can_reshape)) return this; 2945 // Don't bother trying to transform a dead node 2946 if (in(0) && in(0)->is_top()) { 2947 return NULL; 2948 } 2949 2950 bool progress = false; 2951 // Eliminate volatile MemBars for scalar replaced objects. 2952 if (can_reshape && req() == (Precedent+1)) { 2953 bool eliminate = false; 2954 int opc = Opcode(); 2955 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 2956 // Volatile field loads and stores. 2957 Node* my_mem = in(MemBarNode::Precedent); 2958 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 2959 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 2960 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 2961 // replace this Precedent (decodeN) with the Load instead. 2962 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 2963 Node* load_node = my_mem->in(1); 2964 set_req(MemBarNode::Precedent, load_node); 2965 phase->is_IterGVN()->_worklist.push(my_mem); 2966 my_mem = load_node; 2967 } else { 2968 assert(my_mem->unique_out() == this, "sanity"); 2969 del_req(Precedent); 2970 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 2971 my_mem = NULL; 2972 } 2973 progress = true; 2974 } 2975 if (my_mem != NULL && my_mem->is_Mem()) { 2976 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 2977 // Check for scalar replaced object reference. 2978 if( t_oop != NULL && t_oop->is_known_instance_field() && 2979 t_oop->offset() != Type::OffsetBot && 2980 t_oop->offset() != Type::OffsetTop) { 2981 eliminate = true; 2982 } 2983 } 2984 } else if (opc == Op_MemBarRelease) { 2985 // Final field stores. 2986 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 2987 if ((alloc != NULL) && alloc->is_Allocate() && 2988 alloc->as_Allocate()->_is_non_escaping) { 2989 // The allocated object does not escape. 2990 eliminate = true; 2991 } 2992 } 2993 if (eliminate) { 2994 // Replace MemBar projections by its inputs. 2995 PhaseIterGVN* igvn = phase->is_IterGVN(); 2996 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 2997 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 2998 // Must return either the original node (now dead) or a new node 2999 // (Do not return a top here, since that would break the uniqueness of top.) 3000 return new ConINode(TypeInt::ZERO); 3001 } 3002 } 3003 return progress ? this : NULL; 3004 } 3005 3006 //------------------------------Value------------------------------------------ 3007 const Type *MemBarNode::Value( PhaseTransform *phase ) const { 3008 if( !in(0) ) return Type::TOP; 3009 if( phase->type(in(0)) == Type::TOP ) 3010 return Type::TOP; 3011 return TypeTuple::MEMBAR; 3012 } 3013 3014 //------------------------------match------------------------------------------ 3015 // Construct projections for memory. 3016 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3017 switch (proj->_con) { 3018 case TypeFunc::Control: 3019 case TypeFunc::Memory: 3020 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3021 } 3022 ShouldNotReachHere(); 3023 return NULL; 3024 } 3025 3026 //===========================InitializeNode==================================== 3027 // SUMMARY: 3028 // This node acts as a memory barrier on raw memory, after some raw stores. 3029 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 3030 // The Initialize can 'capture' suitably constrained stores as raw inits. 3031 // It can coalesce related raw stores into larger units (called 'tiles'). 3032 // It can avoid zeroing new storage for memory units which have raw inits. 3033 // At macro-expansion, it is marked 'complete', and does not optimize further. 3034 // 3035 // EXAMPLE: 3036 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3037 // ctl = incoming control; mem* = incoming memory 3038 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 3039 // First allocate uninitialized memory and fill in the header: 3040 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 3041 // ctl := alloc.Control; mem* := alloc.Memory* 3042 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 3043 // Then initialize to zero the non-header parts of the raw memory block: 3044 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3045 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3046 // After the initialize node executes, the object is ready for service: 3047 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3048 // Suppose its body is immediately initialized as {1,2}: 3049 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3050 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3051 // mem.SLICE(#short[*]) := store2 3052 // 3053 // DETAILS: 3054 // An InitializeNode collects and isolates object initialization after 3055 // an AllocateNode and before the next possible safepoint. As a 3056 // memory barrier (MemBarNode), it keeps critical stores from drifting 3057 // down past any safepoint or any publication of the allocation. 3058 // Before this barrier, a newly-allocated object may have uninitialized bits. 3059 // After this barrier, it may be treated as a real oop, and GC is allowed. 3060 // 3061 // The semantics of the InitializeNode include an implicit zeroing of 3062 // the new object from object header to the end of the object. 3063 // (The object header and end are determined by the AllocateNode.) 3064 // 3065 // Certain stores may be added as direct inputs to the InitializeNode. 3066 // These stores must update raw memory, and they must be to addresses 3067 // derived from the raw address produced by AllocateNode, and with 3068 // a constant offset. They must be ordered by increasing offset. 3069 // The first one is at in(RawStores), the last at in(req()-1). 3070 // Unlike most memory operations, they are not linked in a chain, 3071 // but are displayed in parallel as users of the rawmem output of 3072 // the allocation. 3073 // 3074 // (See comments in InitializeNode::capture_store, which continue 3075 // the example given above.) 3076 // 3077 // When the associated Allocate is macro-expanded, the InitializeNode 3078 // may be rewritten to optimize collected stores. A ClearArrayNode 3079 // may also be created at that point to represent any required zeroing. 3080 // The InitializeNode is then marked 'complete', prohibiting further 3081 // capturing of nearby memory operations. 3082 // 3083 // During macro-expansion, all captured initializations which store 3084 // constant values of 32 bits or smaller are coalesced (if advantageous) 3085 // into larger 'tiles' 32 or 64 bits. This allows an object to be 3086 // initialized in fewer memory operations. Memory words which are 3087 // covered by neither tiles nor non-constant stores are pre-zeroed 3088 // by explicit stores of zero. (The code shape happens to do all 3089 // zeroing first, then all other stores, with both sequences occurring 3090 // in order of ascending offsets.) 3091 // 3092 // Alternatively, code may be inserted between an AllocateNode and its 3093 // InitializeNode, to perform arbitrary initialization of the new object. 3094 // E.g., the object copying intrinsics insert complex data transfers here. 3095 // The initialization must then be marked as 'complete' disable the 3096 // built-in zeroing semantics and the collection of initializing stores. 3097 // 3098 // While an InitializeNode is incomplete, reads from the memory state 3099 // produced by it are optimizable if they match the control edge and 3100 // new oop address associated with the allocation/initialization. 3101 // They return a stored value (if the offset matches) or else zero. 3102 // A write to the memory state, if it matches control and address, 3103 // and if it is to a constant offset, may be 'captured' by the 3104 // InitializeNode. It is cloned as a raw memory operation and rewired 3105 // inside the initialization, to the raw oop produced by the allocation. 3106 // Operations on addresses which are provably distinct (e.g., to 3107 // other AllocateNodes) are allowed to bypass the initialization. 3108 // 3109 // The effect of all this is to consolidate object initialization 3110 // (both arrays and non-arrays, both piecewise and bulk) into a 3111 // single location, where it can be optimized as a unit. 3112 // 3113 // Only stores with an offset less than TrackedInitializationLimit words 3114 // will be considered for capture by an InitializeNode. This puts a 3115 // reasonable limit on the complexity of optimized initializations. 3116 3117 //---------------------------InitializeNode------------------------------------ 3118 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3119 : _is_complete(Incomplete), _does_not_escape(false), 3120 MemBarNode(C, adr_type, rawoop) 3121 { 3122 init_class_id(Class_Initialize); 3123 3124 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3125 assert(in(RawAddress) == rawoop, "proper init"); 3126 // Note: allocation() can be NULL, for secondary initialization barriers 3127 } 3128 3129 // Since this node is not matched, it will be processed by the 3130 // register allocator. Declare that there are no constraints 3131 // on the allocation of the RawAddress edge. 3132 const RegMask &InitializeNode::in_RegMask(uint idx) const { 3133 // This edge should be set to top, by the set_complete. But be conservative. 3134 if (idx == InitializeNode::RawAddress) 3135 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3136 return RegMask::Empty; 3137 } 3138 3139 Node* InitializeNode::memory(uint alias_idx) { 3140 Node* mem = in(Memory); 3141 if (mem->is_MergeMem()) { 3142 return mem->as_MergeMem()->memory_at(alias_idx); 3143 } else { 3144 // incoming raw memory is not split 3145 return mem; 3146 } 3147 } 3148 3149 bool InitializeNode::is_non_zero() { 3150 if (is_complete()) return false; 3151 remove_extra_zeroes(); 3152 return (req() > RawStores); 3153 } 3154 3155 void InitializeNode::set_complete(PhaseGVN* phase) { 3156 assert(!is_complete(), "caller responsibility"); 3157 _is_complete = Complete; 3158 3159 // After this node is complete, it contains a bunch of 3160 // raw-memory initializations. There is no need for 3161 // it to have anything to do with non-raw memory effects. 3162 // Therefore, tell all non-raw users to re-optimize themselves, 3163 // after skipping the memory effects of this initialization. 3164 PhaseIterGVN* igvn = phase->is_IterGVN(); 3165 if (igvn) igvn->add_users_to_worklist(this); 3166 } 3167 3168 // convenience function 3169 // return false if the init contains any stores already 3170 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3171 InitializeNode* init = initialization(); 3172 if (init == NULL || init->is_complete()) return false; 3173 init->remove_extra_zeroes(); 3174 // for now, if this allocation has already collected any inits, bail: 3175 if (init->is_non_zero()) return false; 3176 init->set_complete(phase); 3177 return true; 3178 } 3179 3180 void InitializeNode::remove_extra_zeroes() { 3181 if (req() == RawStores) return; 3182 Node* zmem = zero_memory(); 3183 uint fill = RawStores; 3184 for (uint i = fill; i < req(); i++) { 3185 Node* n = in(i); 3186 if (n->is_top() || n == zmem) continue; // skip 3187 if (fill < i) set_req(fill, n); // compact 3188 ++fill; 3189 } 3190 // delete any empty spaces created: 3191 while (fill < req()) { 3192 del_req(fill); 3193 } 3194 } 3195 3196 // Helper for remembering which stores go with which offsets. 3197 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3198 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3199 intptr_t offset = -1; 3200 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3201 phase, offset); 3202 if (base == NULL) return -1; // something is dead, 3203 if (offset < 0) return -1; // dead, dead 3204 return offset; 3205 } 3206 3207 // Helper for proving that an initialization expression is 3208 // "simple enough" to be folded into an object initialization. 3209 // Attempts to prove that a store's initial value 'n' can be captured 3210 // within the initialization without creating a vicious cycle, such as: 3211 // { Foo p = new Foo(); p.next = p; } 3212 // True for constants and parameters and small combinations thereof. 3213 bool InitializeNode::detect_init_independence(Node* n, int& count) { 3214 if (n == NULL) return true; // (can this really happen?) 3215 if (n->is_Proj()) n = n->in(0); 3216 if (n == this) return false; // found a cycle 3217 if (n->is_Con()) return true; 3218 if (n->is_Start()) return true; // params, etc., are OK 3219 if (n->is_Root()) return true; // even better 3220 3221 Node* ctl = n->in(0); 3222 if (ctl != NULL && !ctl->is_top()) { 3223 if (ctl->is_Proj()) ctl = ctl->in(0); 3224 if (ctl == this) return false; 3225 3226 // If we already know that the enclosing memory op is pinned right after 3227 // the init, then any control flow that the store has picked up 3228 // must have preceded the init, or else be equal to the init. 3229 // Even after loop optimizations (which might change control edges) 3230 // a store is never pinned *before* the availability of its inputs. 3231 if (!MemNode::all_controls_dominate(n, this)) 3232 return false; // failed to prove a good control 3233 } 3234 3235 // Check data edges for possible dependencies on 'this'. 3236 if ((count += 1) > 20) return false; // complexity limit 3237 for (uint i = 1; i < n->req(); i++) { 3238 Node* m = n->in(i); 3239 if (m == NULL || m == n || m->is_top()) continue; 3240 uint first_i = n->find_edge(m); 3241 if (i != first_i) continue; // process duplicate edge just once 3242 if (!detect_init_independence(m, count)) { 3243 return false; 3244 } 3245 } 3246 3247 return true; 3248 } 3249 3250 // Here are all the checks a Store must pass before it can be moved into 3251 // an initialization. Returns zero if a check fails. 3252 // On success, returns the (constant) offset to which the store applies, 3253 // within the initialized memory. 3254 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) { 3255 const int FAIL = 0; 3256 if (st->req() != MemNode::ValueIn + 1) 3257 return FAIL; // an inscrutable StoreNode (card mark?) 3258 Node* ctl = st->in(MemNode::Control); 3259 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3260 return FAIL; // must be unconditional after the initialization 3261 Node* mem = st->in(MemNode::Memory); 3262 if (!(mem->is_Proj() && mem->in(0) == this)) 3263 return FAIL; // must not be preceded by other stores 3264 Node* adr = st->in(MemNode::Address); 3265 intptr_t offset; 3266 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3267 if (alloc == NULL) 3268 return FAIL; // inscrutable address 3269 if (alloc != allocation()) 3270 return FAIL; // wrong allocation! (store needs to float up) 3271 Node* val = st->in(MemNode::ValueIn); 3272 int complexity_count = 0; 3273 if (!detect_init_independence(val, complexity_count)) 3274 return FAIL; // stored value must be 'simple enough' 3275 3276 // The Store can be captured only if nothing after the allocation 3277 // and before the Store is using the memory location that the store 3278 // overwrites. 3279 bool failed = false; 3280 // If is_complete_with_arraycopy() is true the shape of the graph is 3281 // well defined and is safe so no need for extra checks. 3282 if (!is_complete_with_arraycopy()) { 3283 // We are going to look at each use of the memory state following 3284 // the allocation to make sure nothing reads the memory that the 3285 // Store writes. 3286 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3287 int alias_idx = phase->C->get_alias_index(t_adr); 3288 ResourceMark rm; 3289 Unique_Node_List mems; 3290 mems.push(mem); 3291 Node* unique_merge = NULL; 3292 for (uint next = 0; next < mems.size(); ++next) { 3293 Node *m = mems.at(next); 3294 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3295 Node *n = m->fast_out(j); 3296 if (n->outcnt() == 0) { 3297 continue; 3298 } 3299 if (n == st) { 3300 continue; 3301 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3302 // If the control of this use is different from the control 3303 // of the Store which is right after the InitializeNode then 3304 // this node cannot be between the InitializeNode and the 3305 // Store. 3306 continue; 3307 } else if (n->is_MergeMem()) { 3308 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3309 // We can hit a MergeMemNode (that will likely go away 3310 // later) that is a direct use of the memory state 3311 // following the InitializeNode on the same slice as the 3312 // store node that we'd like to capture. We need to check 3313 // the uses of the MergeMemNode. 3314 mems.push(n); 3315 } 3316 } else if (n->is_Mem()) { 3317 Node* other_adr = n->in(MemNode::Address); 3318 if (other_adr == adr) { 3319 failed = true; 3320 break; 3321 } else { 3322 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3323 if (other_t_adr != NULL) { 3324 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3325 if (other_alias_idx == alias_idx) { 3326 // A load from the same memory slice as the store right 3327 // after the InitializeNode. We check the control of the 3328 // object/array that is loaded from. If it's the same as 3329 // the store control then we cannot capture the store. 3330 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3331 Node* base = other_adr; 3332 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name())); 3333 base = base->in(AddPNode::Base); 3334 if (base != NULL) { 3335 base = base->uncast(); 3336 if (base->is_Proj() && base->in(0) == alloc) { 3337 failed = true; 3338 break; 3339 } 3340 } 3341 } 3342 } 3343 } 3344 } else { 3345 failed = true; 3346 break; 3347 } 3348 } 3349 } 3350 } 3351 if (failed) { 3352 if (!can_reshape) { 3353 // We decided we couldn't capture the store during parsing. We 3354 // should try again during the next IGVN once the graph is 3355 // cleaner. 3356 phase->C->record_for_igvn(st); 3357 } 3358 return FAIL; 3359 } 3360 3361 return offset; // success 3362 } 3363 3364 // Find the captured store in(i) which corresponds to the range 3365 // [start..start+size) in the initialized object. 3366 // If there is one, return its index i. If there isn't, return the 3367 // negative of the index where it should be inserted. 3368 // Return 0 if the queried range overlaps an initialization boundary 3369 // or if dead code is encountered. 3370 // If size_in_bytes is zero, do not bother with overlap checks. 3371 int InitializeNode::captured_store_insertion_point(intptr_t start, 3372 int size_in_bytes, 3373 PhaseTransform* phase) { 3374 const int FAIL = 0, MAX_STORE = BytesPerLong; 3375 3376 if (is_complete()) 3377 return FAIL; // arraycopy got here first; punt 3378 3379 assert(allocation() != NULL, "must be present"); 3380 3381 // no negatives, no header fields: 3382 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3383 3384 // after a certain size, we bail out on tracking all the stores: 3385 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3386 if (start >= ti_limit) return FAIL; 3387 3388 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3389 if (i >= limit) return -(int)i; // not found; here is where to put it 3390 3391 Node* st = in(i); 3392 intptr_t st_off = get_store_offset(st, phase); 3393 if (st_off < 0) { 3394 if (st != zero_memory()) { 3395 return FAIL; // bail out if there is dead garbage 3396 } 3397 } else if (st_off > start) { 3398 // ...we are done, since stores are ordered 3399 if (st_off < start + size_in_bytes) { 3400 return FAIL; // the next store overlaps 3401 } 3402 return -(int)i; // not found; here is where to put it 3403 } else if (st_off < start) { 3404 if (size_in_bytes != 0 && 3405 start < st_off + MAX_STORE && 3406 start < st_off + st->as_Store()->memory_size()) { 3407 return FAIL; // the previous store overlaps 3408 } 3409 } else { 3410 if (size_in_bytes != 0 && 3411 st->as_Store()->memory_size() != size_in_bytes) { 3412 return FAIL; // mismatched store size 3413 } 3414 return i; 3415 } 3416 3417 ++i; 3418 } 3419 } 3420 3421 // Look for a captured store which initializes at the offset 'start' 3422 // with the given size. If there is no such store, and no other 3423 // initialization interferes, then return zero_memory (the memory 3424 // projection of the AllocateNode). 3425 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3426 PhaseTransform* phase) { 3427 assert(stores_are_sane(phase), ""); 3428 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3429 if (i == 0) { 3430 return NULL; // something is dead 3431 } else if (i < 0) { 3432 return zero_memory(); // just primordial zero bits here 3433 } else { 3434 Node* st = in(i); // here is the store at this position 3435 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3436 return st; 3437 } 3438 } 3439 3440 // Create, as a raw pointer, an address within my new object at 'offset'. 3441 Node* InitializeNode::make_raw_address(intptr_t offset, 3442 PhaseTransform* phase) { 3443 Node* addr = in(RawAddress); 3444 if (offset != 0) { 3445 Compile* C = phase->C; 3446 addr = phase->transform( new AddPNode(C->top(), addr, 3447 phase->MakeConX(offset)) ); 3448 } 3449 return addr; 3450 } 3451 3452 // Clone the given store, converting it into a raw store 3453 // initializing a field or element of my new object. 3454 // Caller is responsible for retiring the original store, 3455 // with subsume_node or the like. 3456 // 3457 // From the example above InitializeNode::InitializeNode, 3458 // here are the old stores to be captured: 3459 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3460 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3461 // 3462 // Here is the changed code; note the extra edges on init: 3463 // alloc = (Allocate ...) 3464 // rawoop = alloc.RawAddress 3465 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3466 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3467 // init = (Initialize alloc.Control alloc.Memory rawoop 3468 // rawstore1 rawstore2) 3469 // 3470 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3471 PhaseTransform* phase, bool can_reshape) { 3472 assert(stores_are_sane(phase), ""); 3473 3474 if (start < 0) return NULL; 3475 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3476 3477 Compile* C = phase->C; 3478 int size_in_bytes = st->memory_size(); 3479 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3480 if (i == 0) return NULL; // bail out 3481 Node* prev_mem = NULL; // raw memory for the captured store 3482 if (i > 0) { 3483 prev_mem = in(i); // there is a pre-existing store under this one 3484 set_req(i, C->top()); // temporarily disconnect it 3485 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3486 } else { 3487 i = -i; // no pre-existing store 3488 prev_mem = zero_memory(); // a slice of the newly allocated object 3489 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3490 set_req(--i, C->top()); // reuse this edge; it has been folded away 3491 else 3492 ins_req(i, C->top()); // build a new edge 3493 } 3494 Node* new_st = st->clone(); 3495 new_st->set_req(MemNode::Control, in(Control)); 3496 new_st->set_req(MemNode::Memory, prev_mem); 3497 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3498 new_st = phase->transform(new_st); 3499 3500 // At this point, new_st might have swallowed a pre-existing store 3501 // at the same offset, or perhaps new_st might have disappeared, 3502 // if it redundantly stored the same value (or zero to fresh memory). 3503 3504 // In any case, wire it in: 3505 phase->igvn_rehash_node_delayed(this); 3506 set_req(i, new_st); 3507 3508 // The caller may now kill the old guy. 3509 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3510 assert(check_st == new_st || check_st == NULL, "must be findable"); 3511 assert(!is_complete(), ""); 3512 return new_st; 3513 } 3514 3515 static bool store_constant(jlong* tiles, int num_tiles, 3516 intptr_t st_off, int st_size, 3517 jlong con) { 3518 if ((st_off & (st_size-1)) != 0) 3519 return false; // strange store offset (assume size==2**N) 3520 address addr = (address)tiles + st_off; 3521 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3522 switch (st_size) { 3523 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3524 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3525 case sizeof(jint): *(jint*) addr = (jint) con; break; 3526 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3527 default: return false; // strange store size (detect size!=2**N here) 3528 } 3529 return true; // return success to caller 3530 } 3531 3532 // Coalesce subword constants into int constants and possibly 3533 // into long constants. The goal, if the CPU permits, 3534 // is to initialize the object with a small number of 64-bit tiles. 3535 // Also, convert floating-point constants to bit patterns. 3536 // Non-constants are not relevant to this pass. 3537 // 3538 // In terms of the running example on InitializeNode::InitializeNode 3539 // and InitializeNode::capture_store, here is the transformation 3540 // of rawstore1 and rawstore2 into rawstore12: 3541 // alloc = (Allocate ...) 3542 // rawoop = alloc.RawAddress 3543 // tile12 = 0x00010002 3544 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3545 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3546 // 3547 void 3548 InitializeNode::coalesce_subword_stores(intptr_t header_size, 3549 Node* size_in_bytes, 3550 PhaseGVN* phase) { 3551 Compile* C = phase->C; 3552 3553 assert(stores_are_sane(phase), ""); 3554 // Note: After this pass, they are not completely sane, 3555 // since there may be some overlaps. 3556 3557 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3558 3559 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3560 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3561 size_limit = MIN2(size_limit, ti_limit); 3562 size_limit = align_size_up(size_limit, BytesPerLong); 3563 int num_tiles = size_limit / BytesPerLong; 3564 3565 // allocate space for the tile map: 3566 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3567 jlong tiles_buf[small_len]; 3568 Node* nodes_buf[small_len]; 3569 jlong inits_buf[small_len]; 3570 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3571 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3572 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3573 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3574 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3575 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3576 // tiles: exact bitwise model of all primitive constants 3577 // nodes: last constant-storing node subsumed into the tiles model 3578 // inits: which bytes (in each tile) are touched by any initializations 3579 3580 //// Pass A: Fill in the tile model with any relevant stores. 3581 3582 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3583 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3584 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3585 Node* zmem = zero_memory(); // initially zero memory state 3586 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3587 Node* st = in(i); 3588 intptr_t st_off = get_store_offset(st, phase); 3589 3590 // Figure out the store's offset and constant value: 3591 if (st_off < header_size) continue; //skip (ignore header) 3592 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3593 int st_size = st->as_Store()->memory_size(); 3594 if (st_off + st_size > size_limit) break; 3595 3596 // Record which bytes are touched, whether by constant or not. 3597 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3598 continue; // skip (strange store size) 3599 3600 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3601 if (!val->singleton()) continue; //skip (non-con store) 3602 BasicType type = val->basic_type(); 3603 3604 jlong con = 0; 3605 switch (type) { 3606 case T_INT: con = val->is_int()->get_con(); break; 3607 case T_LONG: con = val->is_long()->get_con(); break; 3608 case T_FLOAT: con = jint_cast(val->getf()); break; 3609 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3610 default: continue; //skip (odd store type) 3611 } 3612 3613 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3614 st->Opcode() == Op_StoreL) { 3615 continue; // This StoreL is already optimal. 3616 } 3617 3618 // Store down the constant. 3619 store_constant(tiles, num_tiles, st_off, st_size, con); 3620 3621 intptr_t j = st_off >> LogBytesPerLong; 3622 3623 if (type == T_INT && st_size == BytesPerInt 3624 && (st_off & BytesPerInt) == BytesPerInt) { 3625 jlong lcon = tiles[j]; 3626 if (!Matcher::isSimpleConstant64(lcon) && 3627 st->Opcode() == Op_StoreI) { 3628 // This StoreI is already optimal by itself. 3629 jint* intcon = (jint*) &tiles[j]; 3630 intcon[1] = 0; // undo the store_constant() 3631 3632 // If the previous store is also optimal by itself, back up and 3633 // undo the action of the previous loop iteration... if we can. 3634 // But if we can't, just let the previous half take care of itself. 3635 st = nodes[j]; 3636 st_off -= BytesPerInt; 3637 con = intcon[0]; 3638 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3639 assert(st_off >= header_size, "still ignoring header"); 3640 assert(get_store_offset(st, phase) == st_off, "must be"); 3641 assert(in(i-1) == zmem, "must be"); 3642 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3643 assert(con == tcon->is_int()->get_con(), "must be"); 3644 // Undo the effects of the previous loop trip, which swallowed st: 3645 intcon[0] = 0; // undo store_constant() 3646 set_req(i-1, st); // undo set_req(i, zmem) 3647 nodes[j] = NULL; // undo nodes[j] = st 3648 --old_subword; // undo ++old_subword 3649 } 3650 continue; // This StoreI is already optimal. 3651 } 3652 } 3653 3654 // This store is not needed. 3655 set_req(i, zmem); 3656 nodes[j] = st; // record for the moment 3657 if (st_size < BytesPerLong) // something has changed 3658 ++old_subword; // includes int/float, but who's counting... 3659 else ++old_long; 3660 } 3661 3662 if ((old_subword + old_long) == 0) 3663 return; // nothing more to do 3664 3665 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3666 // Be sure to insert them before overlapping non-constant stores. 3667 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3668 for (int j = 0; j < num_tiles; j++) { 3669 jlong con = tiles[j]; 3670 jlong init = inits[j]; 3671 if (con == 0) continue; 3672 jint con0, con1; // split the constant, address-wise 3673 jint init0, init1; // split the init map, address-wise 3674 { union { jlong con; jint intcon[2]; } u; 3675 u.con = con; 3676 con0 = u.intcon[0]; 3677 con1 = u.intcon[1]; 3678 u.con = init; 3679 init0 = u.intcon[0]; 3680 init1 = u.intcon[1]; 3681 } 3682 3683 Node* old = nodes[j]; 3684 assert(old != NULL, "need the prior store"); 3685 intptr_t offset = (j * BytesPerLong); 3686 3687 bool split = !Matcher::isSimpleConstant64(con); 3688 3689 if (offset < header_size) { 3690 assert(offset + BytesPerInt >= header_size, "second int counts"); 3691 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3692 split = true; // only the second word counts 3693 // Example: int a[] = { 42 ... } 3694 } else if (con0 == 0 && init0 == -1) { 3695 split = true; // first word is covered by full inits 3696 // Example: int a[] = { ... foo(), 42 ... } 3697 } else if (con1 == 0 && init1 == -1) { 3698 split = true; // second word is covered by full inits 3699 // Example: int a[] = { ... 42, foo() ... } 3700 } 3701 3702 // Here's a case where init0 is neither 0 nor -1: 3703 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3704 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3705 // In this case the tile is not split; it is (jlong)42. 3706 // The big tile is stored down, and then the foo() value is inserted. 3707 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3708 3709 Node* ctl = old->in(MemNode::Control); 3710 Node* adr = make_raw_address(offset, phase); 3711 const TypePtr* atp = TypeRawPtr::BOTTOM; 3712 3713 // One or two coalesced stores to plop down. 3714 Node* st[2]; 3715 intptr_t off[2]; 3716 int nst = 0; 3717 if (!split) { 3718 ++new_long; 3719 off[nst] = offset; 3720 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3721 phase->longcon(con), T_LONG, MemNode::unordered); 3722 } else { 3723 // Omit either if it is a zero. 3724 if (con0 != 0) { 3725 ++new_int; 3726 off[nst] = offset; 3727 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3728 phase->intcon(con0), T_INT, MemNode::unordered); 3729 } 3730 if (con1 != 0) { 3731 ++new_int; 3732 offset += BytesPerInt; 3733 adr = make_raw_address(offset, phase); 3734 off[nst] = offset; 3735 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3736 phase->intcon(con1), T_INT, MemNode::unordered); 3737 } 3738 } 3739 3740 // Insert second store first, then the first before the second. 3741 // Insert each one just before any overlapping non-constant stores. 3742 while (nst > 0) { 3743 Node* st1 = st[--nst]; 3744 C->copy_node_notes_to(st1, old); 3745 st1 = phase->transform(st1); 3746 offset = off[nst]; 3747 assert(offset >= header_size, "do not smash header"); 3748 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3749 guarantee(ins_idx != 0, "must re-insert constant store"); 3750 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3751 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3752 set_req(--ins_idx, st1); 3753 else 3754 ins_req(ins_idx, st1); 3755 } 3756 } 3757 3758 if (PrintCompilation && WizardMode) 3759 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3760 old_subword, old_long, new_int, new_long); 3761 if (C->log() != NULL) 3762 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3763 old_subword, old_long, new_int, new_long); 3764 3765 // Clean up any remaining occurrences of zmem: 3766 remove_extra_zeroes(); 3767 } 3768 3769 // Explore forward from in(start) to find the first fully initialized 3770 // word, and return its offset. Skip groups of subword stores which 3771 // together initialize full words. If in(start) is itself part of a 3772 // fully initialized word, return the offset of in(start). If there 3773 // are no following full-word stores, or if something is fishy, return 3774 // a negative value. 3775 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3776 int int_map = 0; 3777 intptr_t int_map_off = 0; 3778 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3779 3780 for (uint i = start, limit = req(); i < limit; i++) { 3781 Node* st = in(i); 3782 3783 intptr_t st_off = get_store_offset(st, phase); 3784 if (st_off < 0) break; // return conservative answer 3785 3786 int st_size = st->as_Store()->memory_size(); 3787 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3788 return st_off; // we found a complete word init 3789 } 3790 3791 // update the map: 3792 3793 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); 3794 if (this_int_off != int_map_off) { 3795 // reset the map: 3796 int_map = 0; 3797 int_map_off = this_int_off; 3798 } 3799 3800 int subword_off = st_off - this_int_off; 3801 int_map |= right_n_bits(st_size) << subword_off; 3802 if ((int_map & FULL_MAP) == FULL_MAP) { 3803 return this_int_off; // we found a complete word init 3804 } 3805 3806 // Did this store hit or cross the word boundary? 3807 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); 3808 if (next_int_off == this_int_off + BytesPerInt) { 3809 // We passed the current int, without fully initializing it. 3810 int_map_off = next_int_off; 3811 int_map >>= BytesPerInt; 3812 } else if (next_int_off > this_int_off + BytesPerInt) { 3813 // We passed the current and next int. 3814 return this_int_off + BytesPerInt; 3815 } 3816 } 3817 3818 return -1; 3819 } 3820 3821 3822 // Called when the associated AllocateNode is expanded into CFG. 3823 // At this point, we may perform additional optimizations. 3824 // Linearize the stores by ascending offset, to make memory 3825 // activity as coherent as possible. 3826 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3827 intptr_t header_size, 3828 Node* size_in_bytes, 3829 PhaseGVN* phase) { 3830 assert(!is_complete(), "not already complete"); 3831 assert(stores_are_sane(phase), ""); 3832 assert(allocation() != NULL, "must be present"); 3833 3834 remove_extra_zeroes(); 3835 3836 if (ReduceFieldZeroing || ReduceBulkZeroing) 3837 // reduce instruction count for common initialization patterns 3838 coalesce_subword_stores(header_size, size_in_bytes, phase); 3839 3840 Node* zmem = zero_memory(); // initially zero memory state 3841 Node* inits = zmem; // accumulating a linearized chain of inits 3842 #ifdef ASSERT 3843 intptr_t first_offset = allocation()->minimum_header_size(); 3844 intptr_t last_init_off = first_offset; // previous init offset 3845 intptr_t last_init_end = first_offset; // previous init offset+size 3846 intptr_t last_tile_end = first_offset; // previous tile offset+size 3847 #endif 3848 intptr_t zeroes_done = header_size; 3849 3850 bool do_zeroing = true; // we might give up if inits are very sparse 3851 int big_init_gaps = 0; // how many large gaps have we seen? 3852 3853 if (ZeroTLAB) do_zeroing = false; 3854 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3855 3856 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3857 Node* st = in(i); 3858 intptr_t st_off = get_store_offset(st, phase); 3859 if (st_off < 0) 3860 break; // unknown junk in the inits 3861 if (st->in(MemNode::Memory) != zmem) 3862 break; // complicated store chains somehow in list 3863 3864 int st_size = st->as_Store()->memory_size(); 3865 intptr_t next_init_off = st_off + st_size; 3866 3867 if (do_zeroing && zeroes_done < next_init_off) { 3868 // See if this store needs a zero before it or under it. 3869 intptr_t zeroes_needed = st_off; 3870 3871 if (st_size < BytesPerInt) { 3872 // Look for subword stores which only partially initialize words. 3873 // If we find some, we must lay down some word-level zeroes first, 3874 // underneath the subword stores. 3875 // 3876 // Examples: 3877 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3878 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3879 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3880 // 3881 // Note: coalesce_subword_stores may have already done this, 3882 // if it was prompted by constant non-zero subword initializers. 3883 // But this case can still arise with non-constant stores. 3884 3885 intptr_t next_full_store = find_next_fullword_store(i, phase); 3886 3887 // In the examples above: 3888 // in(i) p q r s x y z 3889 // st_off 12 13 14 15 12 13 14 3890 // st_size 1 1 1 1 1 1 1 3891 // next_full_s. 12 16 16 16 16 16 16 3892 // z's_done 12 16 16 16 12 16 12 3893 // z's_needed 12 16 16 16 16 16 16 3894 // zsize 0 0 0 0 4 0 4 3895 if (next_full_store < 0) { 3896 // Conservative tack: Zero to end of current word. 3897 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); 3898 } else { 3899 // Zero to beginning of next fully initialized word. 3900 // Or, don't zero at all, if we are already in that word. 3901 assert(next_full_store >= zeroes_needed, "must go forward"); 3902 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3903 zeroes_needed = next_full_store; 3904 } 3905 } 3906 3907 if (zeroes_needed > zeroes_done) { 3908 intptr_t zsize = zeroes_needed - zeroes_done; 3909 // Do some incremental zeroing on rawmem, in parallel with inits. 3910 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3911 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3912 zeroes_done, zeroes_needed, 3913 phase); 3914 zeroes_done = zeroes_needed; 3915 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) 3916 do_zeroing = false; // leave the hole, next time 3917 } 3918 } 3919 3920 // Collect the store and move on: 3921 st->set_req(MemNode::Memory, inits); 3922 inits = st; // put it on the linearized chain 3923 set_req(i, zmem); // unhook from previous position 3924 3925 if (zeroes_done == st_off) 3926 zeroes_done = next_init_off; 3927 3928 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3929 3930 #ifdef ASSERT 3931 // Various order invariants. Weaker than stores_are_sane because 3932 // a large constant tile can be filled in by smaller non-constant stores. 3933 assert(st_off >= last_init_off, "inits do not reverse"); 3934 last_init_off = st_off; 3935 const Type* val = NULL; 3936 if (st_size >= BytesPerInt && 3937 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3938 (int)val->basic_type() < (int)T_OBJECT) { 3939 assert(st_off >= last_tile_end, "tiles do not overlap"); 3940 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3941 last_tile_end = MAX2(last_tile_end, next_init_off); 3942 } else { 3943 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); 3944 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3945 assert(st_off >= last_init_end, "inits do not overlap"); 3946 last_init_end = next_init_off; // it's a non-tile 3947 } 3948 #endif //ASSERT 3949 } 3950 3951 remove_extra_zeroes(); // clear out all the zmems left over 3952 add_req(inits); 3953 3954 if (!ZeroTLAB) { 3955 // If anything remains to be zeroed, zero it all now. 3956 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3957 // if it is the last unused 4 bytes of an instance, forget about it 3958 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3959 if (zeroes_done + BytesPerLong >= size_limit) { 3960 assert(allocation() != NULL, ""); 3961 if (allocation()->Opcode() == Op_Allocate) { 3962 Node* klass_node = allocation()->in(AllocateNode::KlassNode); 3963 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3964 if (zeroes_done == k->layout_helper()) 3965 zeroes_done = size_limit; 3966 } 3967 } 3968 if (zeroes_done < size_limit) { 3969 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3970 zeroes_done, size_in_bytes, phase); 3971 } 3972 } 3973 3974 set_complete(phase); 3975 return rawmem; 3976 } 3977 3978 3979 #ifdef ASSERT 3980 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3981 if (is_complete()) 3982 return true; // stores could be anything at this point 3983 assert(allocation() != NULL, "must be present"); 3984 intptr_t last_off = allocation()->minimum_header_size(); 3985 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3986 Node* st = in(i); 3987 intptr_t st_off = get_store_offset(st, phase); 3988 if (st_off < 0) continue; // ignore dead garbage 3989 if (last_off > st_off) { 3990 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 3991 this->dump(2); 3992 assert(false, "ascending store offsets"); 3993 return false; 3994 } 3995 last_off = st_off + st->as_Store()->memory_size(); 3996 } 3997 return true; 3998 } 3999 #endif //ASSERT 4000 4001 4002 4003 4004 //============================MergeMemNode===================================== 4005 // 4006 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4007 // contributing store or call operations. Each contributor provides the memory 4008 // state for a particular "alias type" (see Compile::alias_type). For example, 4009 // if a MergeMem has an input X for alias category #6, then any memory reference 4010 // to alias category #6 may use X as its memory state input, as an exact equivalent 4011 // to using the MergeMem as a whole. 4012 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4013 // 4014 // (Here, the <N> notation gives the index of the relevant adr_type.) 4015 // 4016 // In one special case (and more cases in the future), alias categories overlap. 4017 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4018 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 4019 // it is exactly equivalent to that state W: 4020 // MergeMem(<Bot>: W) <==> W 4021 // 4022 // Usually, the merge has more than one input. In that case, where inputs 4023 // overlap (i.e., one is Bot), the narrower alias type determines the memory 4024 // state for that type, and the wider alias type (Bot) fills in everywhere else: 4025 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4026 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4027 // 4028 // A merge can take a "wide" memory state as one of its narrow inputs. 4029 // This simply means that the merge observes out only the relevant parts of 4030 // the wide input. That is, wide memory states arriving at narrow merge inputs 4031 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4032 // 4033 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4034 // and that memory slices "leak through": 4035 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4036 // 4037 // But, in such a cascade, repeated memory slices can "block the leak": 4038 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4039 // 4040 // In the last example, Y is not part of the combined memory state of the 4041 // outermost MergeMem. The system must, of course, prevent unschedulable 4042 // memory states from arising, so you can be sure that the state Y is somehow 4043 // a precursor to state Y'. 4044 // 4045 // 4046 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4047 // of each MergeMemNode array are exactly the numerical alias indexes, including 4048 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4049 // Compile::alias_type (and kin) produce and manage these indexes. 4050 // 4051 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4052 // (Note that this provides quick access to the top node inside MergeMem methods, 4053 // without the need to reach out via TLS to Compile::current.) 4054 // 4055 // As a consequence of what was just described, a MergeMem that represents a full 4056 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4057 // containing all alias categories. 4058 // 4059 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4060 // 4061 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4062 // a memory state for the alias type <N>, or else the top node, meaning that 4063 // there is no particular input for that alias type. Note that the length of 4064 // a MergeMem is variable, and may be extended at any time to accommodate new 4065 // memory states at larger alias indexes. When merges grow, they are of course 4066 // filled with "top" in the unused in() positions. 4067 // 4068 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4069 // (Top was chosen because it works smoothly with passes like GCM.) 4070 // 4071 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4072 // the type of random VM bits like TLS references.) Since it is always the 4073 // first non-Bot memory slice, some low-level loops use it to initialize an 4074 // index variable: for (i = AliasIdxRaw; i < req(); i++). 4075 // 4076 // 4077 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4078 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4079 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 4080 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4081 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4082 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4083 // 4084 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4085 // really that different from the other memory inputs. An abbreviation called 4086 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4087 // 4088 // 4089 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4090 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4091 // that "emerges though" the base memory will be marked as excluding the alias types 4092 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 4093 // 4094 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4095 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4096 // 4097 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 4098 // (It is currently unimplemented.) As you can see, the resulting merge is 4099 // actually a disjoint union of memory states, rather than an overlay. 4100 // 4101 4102 //------------------------------MergeMemNode----------------------------------- 4103 Node* MergeMemNode::make_empty_memory() { 4104 Node* empty_memory = (Node*) Compile::current()->top(); 4105 assert(empty_memory->is_top(), "correct sentinel identity"); 4106 return empty_memory; 4107 } 4108 4109 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4110 init_class_id(Class_MergeMem); 4111 // all inputs are nullified in Node::Node(int) 4112 // set_input(0, NULL); // no control input 4113 4114 // Initialize the edges uniformly to top, for starters. 4115 Node* empty_mem = make_empty_memory(); 4116 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4117 init_req(i,empty_mem); 4118 } 4119 assert(empty_memory() == empty_mem, ""); 4120 4121 if( new_base != NULL && new_base->is_MergeMem() ) { 4122 MergeMemNode* mdef = new_base->as_MergeMem(); 4123 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4124 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4125 mms.set_memory(mms.memory2()); 4126 } 4127 assert(base_memory() == mdef->base_memory(), ""); 4128 } else { 4129 set_base_memory(new_base); 4130 } 4131 } 4132 4133 // Make a new, untransformed MergeMem with the same base as 'mem'. 4134 // If mem is itself a MergeMem, populate the result with the same edges. 4135 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) { 4136 return new MergeMemNode(mem); 4137 } 4138 4139 //------------------------------cmp-------------------------------------------- 4140 uint MergeMemNode::hash() const { return NO_HASH; } 4141 uint MergeMemNode::cmp( const Node &n ) const { 4142 return (&n == this); // Always fail except on self 4143 } 4144 4145 //------------------------------Identity--------------------------------------- 4146 Node* MergeMemNode::Identity(PhaseTransform *phase) { 4147 // Identity if this merge point does not record any interesting memory 4148 // disambiguations. 4149 Node* base_mem = base_memory(); 4150 Node* empty_mem = empty_memory(); 4151 if (base_mem != empty_mem) { // Memory path is not dead? 4152 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4153 Node* mem = in(i); 4154 if (mem != empty_mem && mem != base_mem) { 4155 return this; // Many memory splits; no change 4156 } 4157 } 4158 } 4159 return base_mem; // No memory splits; ID on the one true input 4160 } 4161 4162 //------------------------------Ideal------------------------------------------ 4163 // This method is invoked recursively on chains of MergeMem nodes 4164 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4165 // Remove chain'd MergeMems 4166 // 4167 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4168 // relative to the "in(Bot)". Since we are patching both at the same time, 4169 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4170 // but rewrite each "in(i)" relative to the new "in(Bot)". 4171 Node *progress = NULL; 4172 4173 4174 Node* old_base = base_memory(); 4175 Node* empty_mem = empty_memory(); 4176 if (old_base == empty_mem) 4177 return NULL; // Dead memory path. 4178 4179 MergeMemNode* old_mbase; 4180 if (old_base != NULL && old_base->is_MergeMem()) 4181 old_mbase = old_base->as_MergeMem(); 4182 else 4183 old_mbase = NULL; 4184 Node* new_base = old_base; 4185 4186 // simplify stacked MergeMems in base memory 4187 if (old_mbase) new_base = old_mbase->base_memory(); 4188 4189 // the base memory might contribute new slices beyond my req() 4190 if (old_mbase) grow_to_match(old_mbase); 4191 4192 // Look carefully at the base node if it is a phi. 4193 PhiNode* phi_base; 4194 if (new_base != NULL && new_base->is_Phi()) 4195 phi_base = new_base->as_Phi(); 4196 else 4197 phi_base = NULL; 4198 4199 Node* phi_reg = NULL; 4200 uint phi_len = (uint)-1; 4201 if (phi_base != NULL && !phi_base->is_copy()) { 4202 // do not examine phi if degraded to a copy 4203 phi_reg = phi_base->region(); 4204 phi_len = phi_base->req(); 4205 // see if the phi is unfinished 4206 for (uint i = 1; i < phi_len; i++) { 4207 if (phi_base->in(i) == NULL) { 4208 // incomplete phi; do not look at it yet! 4209 phi_reg = NULL; 4210 phi_len = (uint)-1; 4211 break; 4212 } 4213 } 4214 } 4215 4216 // Note: We do not call verify_sparse on entry, because inputs 4217 // can normalize to the base_memory via subsume_node or similar 4218 // mechanisms. This method repairs that damage. 4219 4220 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4221 4222 // Look at each slice. 4223 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4224 Node* old_in = in(i); 4225 // calculate the old memory value 4226 Node* old_mem = old_in; 4227 if (old_mem == empty_mem) old_mem = old_base; 4228 assert(old_mem == memory_at(i), ""); 4229 4230 // maybe update (reslice) the old memory value 4231 4232 // simplify stacked MergeMems 4233 Node* new_mem = old_mem; 4234 MergeMemNode* old_mmem; 4235 if (old_mem != NULL && old_mem->is_MergeMem()) 4236 old_mmem = old_mem->as_MergeMem(); 4237 else 4238 old_mmem = NULL; 4239 if (old_mmem == this) { 4240 // This can happen if loops break up and safepoints disappear. 4241 // A merge of BotPtr (default) with a RawPtr memory derived from a 4242 // safepoint can be rewritten to a merge of the same BotPtr with 4243 // the BotPtr phi coming into the loop. If that phi disappears 4244 // also, we can end up with a self-loop of the mergemem. 4245 // In general, if loops degenerate and memory effects disappear, 4246 // a mergemem can be left looking at itself. This simply means 4247 // that the mergemem's default should be used, since there is 4248 // no longer any apparent effect on this slice. 4249 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4250 // from start. Update the input to TOP. 4251 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4252 } 4253 else if (old_mmem != NULL) { 4254 new_mem = old_mmem->memory_at(i); 4255 } 4256 // else preceding memory was not a MergeMem 4257 4258 // replace equivalent phis (unfortunately, they do not GVN together) 4259 if (new_mem != NULL && new_mem != new_base && 4260 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4261 if (new_mem->is_Phi()) { 4262 PhiNode* phi_mem = new_mem->as_Phi(); 4263 for (uint i = 1; i < phi_len; i++) { 4264 if (phi_base->in(i) != phi_mem->in(i)) { 4265 phi_mem = NULL; 4266 break; 4267 } 4268 } 4269 if (phi_mem != NULL) { 4270 // equivalent phi nodes; revert to the def 4271 new_mem = new_base; 4272 } 4273 } 4274 } 4275 4276 // maybe store down a new value 4277 Node* new_in = new_mem; 4278 if (new_in == new_base) new_in = empty_mem; 4279 4280 if (new_in != old_in) { 4281 // Warning: Do not combine this "if" with the previous "if" 4282 // A memory slice might have be be rewritten even if it is semantically 4283 // unchanged, if the base_memory value has changed. 4284 set_req(i, new_in); 4285 progress = this; // Report progress 4286 } 4287 } 4288 4289 if (new_base != old_base) { 4290 set_req(Compile::AliasIdxBot, new_base); 4291 // Don't use set_base_memory(new_base), because we need to update du. 4292 assert(base_memory() == new_base, ""); 4293 progress = this; 4294 } 4295 4296 if( base_memory() == this ) { 4297 // a self cycle indicates this memory path is dead 4298 set_req(Compile::AliasIdxBot, empty_mem); 4299 } 4300 4301 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4302 // Recursion must occur after the self cycle check above 4303 if( base_memory()->is_MergeMem() ) { 4304 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4305 Node *m = phase->transform(new_mbase); // Rollup any cycles 4306 if( m != NULL && (m->is_top() || 4307 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 4308 // propagate rollup of dead cycle to self 4309 set_req(Compile::AliasIdxBot, empty_mem); 4310 } 4311 } 4312 4313 if( base_memory() == empty_mem ) { 4314 progress = this; 4315 // Cut inputs during Parse phase only. 4316 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4317 if( !can_reshape ) { 4318 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4319 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4320 } 4321 } 4322 } 4323 4324 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4325 // Check if PhiNode::Ideal's "Split phis through memory merges" 4326 // transform should be attempted. Look for this->phi->this cycle. 4327 uint merge_width = req(); 4328 if (merge_width > Compile::AliasIdxRaw) { 4329 PhiNode* phi = base_memory()->as_Phi(); 4330 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4331 if (phi->in(i) == this) { 4332 phase->is_IterGVN()->_worklist.push(phi); 4333 break; 4334 } 4335 } 4336 } 4337 } 4338 4339 assert(progress || verify_sparse(), "please, no dups of base"); 4340 return progress; 4341 } 4342 4343 //-------------------------set_base_memory------------------------------------- 4344 void MergeMemNode::set_base_memory(Node *new_base) { 4345 Node* empty_mem = empty_memory(); 4346 set_req(Compile::AliasIdxBot, new_base); 4347 assert(memory_at(req()) == new_base, "must set default memory"); 4348 // Clear out other occurrences of new_base: 4349 if (new_base != empty_mem) { 4350 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4351 if (in(i) == new_base) set_req(i, empty_mem); 4352 } 4353 } 4354 } 4355 4356 //------------------------------out_RegMask------------------------------------ 4357 const RegMask &MergeMemNode::out_RegMask() const { 4358 return RegMask::Empty; 4359 } 4360 4361 //------------------------------dump_spec-------------------------------------- 4362 #ifndef PRODUCT 4363 void MergeMemNode::dump_spec(outputStream *st) const { 4364 st->print(" {"); 4365 Node* base_mem = base_memory(); 4366 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4367 Node* mem = memory_at(i); 4368 if (mem == base_mem) { st->print(" -"); continue; } 4369 st->print( " N%d:", mem->_idx ); 4370 Compile::current()->get_adr_type(i)->dump_on(st); 4371 } 4372 st->print(" }"); 4373 } 4374 #endif // !PRODUCT 4375 4376 4377 #ifdef ASSERT 4378 static bool might_be_same(Node* a, Node* b) { 4379 if (a == b) return true; 4380 if (!(a->is_Phi() || b->is_Phi())) return false; 4381 // phis shift around during optimization 4382 return true; // pretty stupid... 4383 } 4384 4385 // verify a narrow slice (either incoming or outgoing) 4386 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4387 if (!VerifyAliases) return; // don't bother to verify unless requested 4388 if (is_error_reported()) return; // muzzle asserts when debugging an error 4389 if (Node::in_dump()) return; // muzzle asserts when printing 4390 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4391 assert(n != NULL, ""); 4392 // Elide intervening MergeMem's 4393 while (n->is_MergeMem()) { 4394 n = n->as_MergeMem()->memory_at(alias_idx); 4395 } 4396 Compile* C = Compile::current(); 4397 const TypePtr* n_adr_type = n->adr_type(); 4398 if (n == m->empty_memory()) { 4399 // Implicit copy of base_memory() 4400 } else if (n_adr_type != TypePtr::BOTTOM) { 4401 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4402 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4403 } else { 4404 // A few places like make_runtime_call "know" that VM calls are narrow, 4405 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4406 bool expected_wide_mem = false; 4407 if (n == m->base_memory()) { 4408 expected_wide_mem = true; 4409 } else if (alias_idx == Compile::AliasIdxRaw || 4410 n == m->memory_at(Compile::AliasIdxRaw)) { 4411 expected_wide_mem = true; 4412 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4413 // memory can "leak through" calls on channels that 4414 // are write-once. Allow this also. 4415 expected_wide_mem = true; 4416 } 4417 assert(expected_wide_mem, "expected narrow slice replacement"); 4418 } 4419 } 4420 #else // !ASSERT 4421 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4422 #endif 4423 4424 4425 //-----------------------------memory_at--------------------------------------- 4426 Node* MergeMemNode::memory_at(uint alias_idx) const { 4427 assert(alias_idx >= Compile::AliasIdxRaw || 4428 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4429 "must avoid base_memory and AliasIdxTop"); 4430 4431 // Otherwise, it is a narrow slice. 4432 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4433 Compile *C = Compile::current(); 4434 if (is_empty_memory(n)) { 4435 // the array is sparse; empty slots are the "top" node 4436 n = base_memory(); 4437 assert(Node::in_dump() 4438 || n == NULL || n->bottom_type() == Type::TOP 4439 || n->adr_type() == NULL // address is TOP 4440 || n->adr_type() == TypePtr::BOTTOM 4441 || n->adr_type() == TypeRawPtr::BOTTOM 4442 || Compile::current()->AliasLevel() == 0, 4443 "must be a wide memory"); 4444 // AliasLevel == 0 if we are organizing the memory states manually. 4445 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4446 } else { 4447 // make sure the stored slice is sane 4448 #ifdef ASSERT 4449 if (is_error_reported() || Node::in_dump()) { 4450 } else if (might_be_same(n, base_memory())) { 4451 // Give it a pass: It is a mostly harmless repetition of the base. 4452 // This can arise normally from node subsumption during optimization. 4453 } else { 4454 verify_memory_slice(this, alias_idx, n); 4455 } 4456 #endif 4457 } 4458 return n; 4459 } 4460 4461 //---------------------------set_memory_at------------------------------------- 4462 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4463 verify_memory_slice(this, alias_idx, n); 4464 Node* empty_mem = empty_memory(); 4465 if (n == base_memory()) n = empty_mem; // collapse default 4466 uint need_req = alias_idx+1; 4467 if (req() < need_req) { 4468 if (n == empty_mem) return; // already the default, so do not grow me 4469 // grow the sparse array 4470 do { 4471 add_req(empty_mem); 4472 } while (req() < need_req); 4473 } 4474 set_req( alias_idx, n ); 4475 } 4476 4477 4478 4479 //--------------------------iteration_setup------------------------------------ 4480 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4481 if (other != NULL) { 4482 grow_to_match(other); 4483 // invariant: the finite support of mm2 is within mm->req() 4484 #ifdef ASSERT 4485 for (uint i = req(); i < other->req(); i++) { 4486 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4487 } 4488 #endif 4489 } 4490 // Replace spurious copies of base_memory by top. 4491 Node* base_mem = base_memory(); 4492 if (base_mem != NULL && !base_mem->is_top()) { 4493 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4494 if (in(i) == base_mem) 4495 set_req(i, empty_memory()); 4496 } 4497 } 4498 } 4499 4500 //---------------------------grow_to_match------------------------------------- 4501 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4502 Node* empty_mem = empty_memory(); 4503 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4504 // look for the finite support of the other memory 4505 for (uint i = other->req(); --i >= req(); ) { 4506 if (other->in(i) != empty_mem) { 4507 uint new_len = i+1; 4508 while (req() < new_len) add_req(empty_mem); 4509 break; 4510 } 4511 } 4512 } 4513 4514 //---------------------------verify_sparse------------------------------------- 4515 #ifndef PRODUCT 4516 bool MergeMemNode::verify_sparse() const { 4517 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4518 Node* base_mem = base_memory(); 4519 // The following can happen in degenerate cases, since empty==top. 4520 if (is_empty_memory(base_mem)) return true; 4521 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4522 assert(in(i) != NULL, "sane slice"); 4523 if (in(i) == base_mem) return false; // should have been the sentinel value! 4524 } 4525 return true; 4526 } 4527 4528 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4529 Node* n; 4530 n = mm->in(idx); 4531 if (mem == n) return true; // might be empty_memory() 4532 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4533 if (mem == n) return true; 4534 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4535 if (mem == n) return true; 4536 if (n == NULL) break; 4537 } 4538 return false; 4539 } 4540 #endif // !PRODUCT