1 /* 2 * Copyright (c) 1997, 2011, 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/loopnode.hpp" 35 #include "opto/machnode.hpp" 36 #include "opto/matcher.hpp" 37 #include "opto/memnode.hpp" 38 #include "opto/mulnode.hpp" 39 #include "opto/phaseX.hpp" 40 #include "opto/regmask.hpp" 41 42 // Portions of code courtesy of Clifford Click 43 44 // Optimization - Graph Style 45 46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 47 48 //============================================================================= 49 uint MemNode::size_of() const { return sizeof(*this); } 50 51 const TypePtr *MemNode::adr_type() const { 52 Node* adr = in(Address); 53 const TypePtr* cross_check = NULL; 54 DEBUG_ONLY(cross_check = _adr_type); 55 return calculate_adr_type(adr->bottom_type(), cross_check); 56 } 57 58 #ifndef PRODUCT 59 void MemNode::dump_spec(outputStream *st) const { 60 if (in(Address) == NULL) return; // node is dead 61 #ifndef ASSERT 62 // fake the missing field 63 const TypePtr* _adr_type = NULL; 64 if (in(Address) != NULL) 65 _adr_type = in(Address)->bottom_type()->isa_ptr(); 66 #endif 67 dump_adr_type(this, _adr_type, st); 68 69 Compile* C = Compile::current(); 70 if( C->alias_type(_adr_type)->is_volatile() ) 71 st->print(" Volatile!"); 72 } 73 74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 75 st->print(" @"); 76 if (adr_type == NULL) { 77 st->print("NULL"); 78 } else { 79 adr_type->dump_on(st); 80 Compile* C = Compile::current(); 81 Compile::AliasType* atp = NULL; 82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 83 if (atp == NULL) 84 st->print(", idx=?\?;"); 85 else if (atp->index() == Compile::AliasIdxBot) 86 st->print(", idx=Bot;"); 87 else if (atp->index() == Compile::AliasIdxTop) 88 st->print(", idx=Top;"); 89 else if (atp->index() == Compile::AliasIdxRaw) 90 st->print(", idx=Raw;"); 91 else { 92 ciField* field = atp->field(); 93 if (field) { 94 st->print(", name="); 95 field->print_name_on(st); 96 } 97 st->print(", idx=%d;", atp->index()); 98 } 99 } 100 } 101 102 extern void print_alias_types(); 103 104 #endif 105 106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) { 107 const TypeOopPtr *tinst = t_adr->isa_oopptr(); 108 if (tinst == NULL || !tinst->is_known_instance_field()) 109 return mchain; // don't try to optimize non-instance types 110 uint instance_id = tinst->instance_id(); 111 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory); 112 Node *prev = NULL; 113 Node *result = mchain; 114 while (prev != result) { 115 prev = result; 116 if (result == start_mem) 117 break; // hit one of our sentinels 118 // skip over a call which does not affect this memory slice 119 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 120 Node *proj_in = result->in(0); 121 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 122 break; // hit one of our sentinels 123 } else if (proj_in->is_Call()) { 124 CallNode *call = proj_in->as_Call(); 125 if (!call->may_modify(t_adr, phase)) { 126 result = call->in(TypeFunc::Memory); 127 } 128 } else if (proj_in->is_Initialize()) { 129 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 130 // Stop if this is the initialization for the object instance which 131 // which contains this memory slice, otherwise skip over it. 132 if (alloc != NULL && alloc->_idx != instance_id) { 133 result = proj_in->in(TypeFunc::Memory); 134 } 135 } else if (proj_in->is_MemBar()) { 136 result = proj_in->in(TypeFunc::Memory); 137 } else { 138 assert(false, "unexpected projection"); 139 } 140 } else if (result->is_ClearArray()) { 141 if (!ClearArrayNode::step_through(&result, instance_id, phase)) { 142 // Can not bypass initialization of the instance 143 // we are looking for. 144 break; 145 } 146 // Otherwise skip it (the call updated 'result' value). 147 } else if (result->is_MergeMem()) { 148 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty); 149 } 150 } 151 return result; 152 } 153 154 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) { 155 const TypeOopPtr *t_oop = t_adr->isa_oopptr(); 156 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field(); 157 PhaseIterGVN *igvn = phase->is_IterGVN(); 158 Node *result = mchain; 159 result = optimize_simple_memory_chain(result, t_adr, phase); 160 if (is_instance && igvn != NULL && result->is_Phi()) { 161 PhiNode *mphi = result->as_Phi(); 162 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 163 const TypePtr *t = mphi->adr_type(); 164 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 165 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 166 t->is_oopptr()->cast_to_exactness(true) 167 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 168 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) { 169 // clone the Phi with our address type 170 result = mphi->split_out_instance(t_adr, igvn); 171 } else { 172 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 173 } 174 } 175 return result; 176 } 177 178 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 179 uint alias_idx = phase->C->get_alias_index(tp); 180 Node *mem = mmem; 181 #ifdef ASSERT 182 { 183 // Check that current type is consistent with the alias index used during graph construction 184 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 185 bool consistent = adr_check == NULL || adr_check->empty() || 186 phase->C->must_alias(adr_check, alias_idx ); 187 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 188 if( !consistent && adr_check != NULL && !adr_check->empty() && 189 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 190 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 191 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 192 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 193 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 194 // don't assert if it is dead code. 195 consistent = true; 196 } 197 if( !consistent ) { 198 st->print("alias_idx==%d, adr_check==", alias_idx); 199 if( adr_check == NULL ) { 200 st->print("NULL"); 201 } else { 202 adr_check->dump(); 203 } 204 st->cr(); 205 print_alias_types(); 206 assert(consistent, "adr_check must match alias idx"); 207 } 208 } 209 #endif 210 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 211 // means an array I have not precisely typed yet. Do not do any 212 // alias stuff with it any time soon. 213 const TypeOopPtr *toop = tp->isa_oopptr(); 214 if( tp->base() != Type::AnyPtr && 215 !(toop && 216 toop->klass() != NULL && 217 toop->klass()->is_java_lang_Object() && 218 toop->offset() == Type::OffsetBot) ) { 219 // compress paths and change unreachable cycles to TOP 220 // If not, we can update the input infinitely along a MergeMem cycle 221 // Equivalent code in PhiNode::Ideal 222 Node* m = phase->transform(mmem); 223 // If transformed to a MergeMem, get the desired slice 224 // Otherwise the returned node represents memory for every slice 225 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 226 // Update input if it is progress over what we have now 227 } 228 return mem; 229 } 230 231 //--------------------------Ideal_common--------------------------------------- 232 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. 233 // Unhook non-raw memories from complete (macro-expanded) initializations. 234 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 235 // If our control input is a dead region, kill all below the region 236 Node *ctl = in(MemNode::Control); 237 if (ctl && remove_dead_region(phase, can_reshape)) 238 return this; 239 ctl = in(MemNode::Control); 240 // Don't bother trying to transform a dead node 241 if( ctl && ctl->is_top() ) return NodeSentinel; 242 243 PhaseIterGVN *igvn = phase->is_IterGVN(); 244 // Wait if control on the worklist. 245 if (ctl && can_reshape && igvn != NULL) { 246 Node* bol = NULL; 247 Node* cmp = NULL; 248 if (ctl->in(0)->is_If()) { 249 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 250 bol = ctl->in(0)->in(1); 251 if (bol->is_Bool()) 252 cmp = ctl->in(0)->in(1)->in(1); 253 } 254 if (igvn->_worklist.member(ctl) || 255 (bol != NULL && igvn->_worklist.member(bol)) || 256 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 257 // This control path may be dead. 258 // Delay this memory node transformation until the control is processed. 259 phase->is_IterGVN()->_worklist.push(this); 260 return NodeSentinel; // caller will return NULL 261 } 262 } 263 // Ignore if memory is dead, or self-loop 264 Node *mem = in(MemNode::Memory); 265 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL 266 assert( mem != this, "dead loop in MemNode::Ideal" ); 267 268 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 269 // This memory slice may be dead. 270 // Delay this mem node transformation until the memory is processed. 271 phase->is_IterGVN()->_worklist.push(this); 272 return NodeSentinel; // caller will return NULL 273 } 274 275 Node *address = in(MemNode::Address); 276 const Type *t_adr = phase->type( address ); 277 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL 278 279 if( can_reshape && igvn != NULL && 280 (igvn->_worklist.member(address) || 281 igvn->_worklist.size() > 0 && (phase->type(address) != adr_type())) ) { 282 // The address's base and type may change when the address is processed. 283 // Delay this mem node transformation until the address is processed. 284 phase->is_IterGVN()->_worklist.push(this); 285 return NodeSentinel; // caller will return NULL 286 } 287 288 // Do NOT remove or optimize the next lines: ensure a new alias index 289 // is allocated for an oop pointer type before Escape Analysis. 290 // Note: C++ will not remove it since the call has side effect. 291 if ( t_adr->isa_oopptr() ) { 292 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 293 } 294 295 #ifdef ASSERT 296 Node* base = NULL; 297 if (address->is_AddP()) 298 base = address->in(AddPNode::Base); 299 assert(base == NULL || t_adr->isa_rawptr() || 300 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?"); 301 #endif 302 303 // Avoid independent memory operations 304 Node* old_mem = mem; 305 306 // The code which unhooks non-raw memories from complete (macro-expanded) 307 // initializations was removed. After macro-expansion all stores catched 308 // by Initialize node became raw stores and there is no information 309 // which memory slices they modify. So it is unsafe to move any memory 310 // operation above these stores. Also in most cases hooked non-raw memories 311 // were already unhooked by using information from detect_ptr_independence() 312 // and find_previous_store(). 313 314 if (mem->is_MergeMem()) { 315 MergeMemNode* mmem = mem->as_MergeMem(); 316 const TypePtr *tp = t_adr->is_ptr(); 317 318 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 319 } 320 321 if (mem != old_mem) { 322 set_req(MemNode::Memory, mem); 323 if (phase->type( mem ) == Type::TOP) return NodeSentinel; 324 return this; 325 } 326 327 // let the subclass continue analyzing... 328 return NULL; 329 } 330 331 // Helper function for proving some simple control dominations. 332 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 333 // Already assumes that 'dom' is available at 'sub', and that 'sub' 334 // is not a constant (dominated by the method's StartNode). 335 // Used by MemNode::find_previous_store to prove that the 336 // control input of a memory operation predates (dominates) 337 // an allocation it wants to look past. 338 bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 339 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 340 return false; // Conservative answer for dead code 341 342 // Check 'dom'. Skip Proj and CatchProj nodes. 343 dom = dom->find_exact_control(dom); 344 if (dom == NULL || dom->is_top()) 345 return false; // Conservative answer for dead code 346 347 if (dom == sub) { 348 // For the case when, for example, 'sub' is Initialize and the original 349 // 'dom' is Proj node of the 'sub'. 350 return false; 351 } 352 353 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 354 return true; 355 356 // 'dom' dominates 'sub' if its control edge and control edges 357 // of all its inputs dominate or equal to sub's control edge. 358 359 // Currently 'sub' is either Allocate, Initialize or Start nodes. 360 // Or Region for the check in LoadNode::Ideal(); 361 // 'sub' should have sub->in(0) != NULL. 362 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 363 sub->is_Region(), "expecting only these nodes"); 364 365 // Get control edge of 'sub'. 366 Node* orig_sub = sub; 367 sub = sub->find_exact_control(sub->in(0)); 368 if (sub == NULL || sub->is_top()) 369 return false; // Conservative answer for dead code 370 371 assert(sub->is_CFG(), "expecting control"); 372 373 if (sub == dom) 374 return true; 375 376 if (sub->is_Start() || sub->is_Root()) 377 return false; 378 379 { 380 // Check all control edges of 'dom'. 381 382 ResourceMark rm; 383 Arena* arena = Thread::current()->resource_area(); 384 Node_List nlist(arena); 385 Unique_Node_List dom_list(arena); 386 387 dom_list.push(dom); 388 bool only_dominating_controls = false; 389 390 for (uint next = 0; next < dom_list.size(); next++) { 391 Node* n = dom_list.at(next); 392 if (n == orig_sub) 393 return false; // One of dom's inputs dominated by sub. 394 if (!n->is_CFG() && n->pinned()) { 395 // Check only own control edge for pinned non-control nodes. 396 n = n->find_exact_control(n->in(0)); 397 if (n == NULL || n->is_top()) 398 return false; // Conservative answer for dead code 399 assert(n->is_CFG(), "expecting control"); 400 dom_list.push(n); 401 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 402 only_dominating_controls = true; 403 } else if (n->is_CFG()) { 404 if (n->dominates(sub, nlist)) 405 only_dominating_controls = true; 406 else 407 return false; 408 } else { 409 // First, own control edge. 410 Node* m = n->find_exact_control(n->in(0)); 411 if (m != NULL) { 412 if (m->is_top()) 413 return false; // Conservative answer for dead code 414 dom_list.push(m); 415 } 416 // Now, the rest of edges. 417 uint cnt = n->req(); 418 for (uint i = 1; i < cnt; i++) { 419 m = n->find_exact_control(n->in(i)); 420 if (m == NULL || m->is_top()) 421 continue; 422 dom_list.push(m); 423 } 424 } 425 } 426 return only_dominating_controls; 427 } 428 } 429 430 //---------------------detect_ptr_independence--------------------------------- 431 // Used by MemNode::find_previous_store to prove that two base 432 // pointers are never equal. 433 // The pointers are accompanied by their associated allocations, 434 // if any, which have been previously discovered by the caller. 435 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 436 Node* p2, AllocateNode* a2, 437 PhaseTransform* phase) { 438 // Attempt to prove that these two pointers cannot be aliased. 439 // They may both manifestly be allocations, and they should differ. 440 // Or, if they are not both allocations, they can be distinct constants. 441 // Otherwise, one is an allocation and the other a pre-existing value. 442 if (a1 == NULL && a2 == NULL) { // neither an allocation 443 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 444 } else if (a1 != NULL && a2 != NULL) { // both allocations 445 return (a1 != a2); 446 } else if (a1 != NULL) { // one allocation a1 447 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 448 return all_controls_dominate(p2, a1); 449 } else { //(a2 != NULL) // one allocation a2 450 return all_controls_dominate(p1, a2); 451 } 452 return false; 453 } 454 455 456 // The logic for reordering loads and stores uses four steps: 457 // (a) Walk carefully past stores and initializations which we 458 // can prove are independent of this load. 459 // (b) Observe that the next memory state makes an exact match 460 // with self (load or store), and locate the relevant store. 461 // (c) Ensure that, if we were to wire self directly to the store, 462 // the optimizer would fold it up somehow. 463 // (d) Do the rewiring, and return, depending on some other part of 464 // the optimizer to fold up the load. 465 // This routine handles steps (a) and (b). Steps (c) and (d) are 466 // specific to loads and stores, so they are handled by the callers. 467 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 468 // 469 Node* MemNode::find_previous_store(PhaseTransform* phase) { 470 Node* ctrl = in(MemNode::Control); 471 Node* adr = in(MemNode::Address); 472 intptr_t offset = 0; 473 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 474 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 475 476 if (offset == Type::OffsetBot) 477 return NULL; // cannot unalias unless there are precise offsets 478 479 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 480 481 intptr_t size_in_bytes = memory_size(); 482 483 Node* mem = in(MemNode::Memory); // start searching here... 484 485 int cnt = 50; // Cycle limiter 486 for (;;) { // While we can dance past unrelated stores... 487 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 488 489 if (mem->is_Store()) { 490 Node* st_adr = mem->in(MemNode::Address); 491 intptr_t st_offset = 0; 492 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 493 if (st_base == NULL) 494 break; // inscrutable pointer 495 if (st_offset != offset && st_offset != Type::OffsetBot) { 496 const int MAX_STORE = BytesPerLong; 497 if (st_offset >= offset + size_in_bytes || 498 st_offset <= offset - MAX_STORE || 499 st_offset <= offset - mem->as_Store()->memory_size()) { 500 // Success: The offsets are provably independent. 501 // (You may ask, why not just test st_offset != offset and be done? 502 // The answer is that stores of different sizes can co-exist 503 // in the same sequence of RawMem effects. We sometimes initialize 504 // a whole 'tile' of array elements with a single jint or jlong.) 505 mem = mem->in(MemNode::Memory); 506 continue; // (a) advance through independent store memory 507 } 508 } 509 if (st_base != base && 510 detect_ptr_independence(base, alloc, 511 st_base, 512 AllocateNode::Ideal_allocation(st_base, phase), 513 phase)) { 514 // Success: The bases are provably independent. 515 mem = mem->in(MemNode::Memory); 516 continue; // (a) advance through independent store memory 517 } 518 519 // (b) At this point, if the bases or offsets do not agree, we lose, 520 // since we have not managed to prove 'this' and 'mem' independent. 521 if (st_base == base && st_offset == offset) { 522 return mem; // let caller handle steps (c), (d) 523 } 524 525 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 526 InitializeNode* st_init = mem->in(0)->as_Initialize(); 527 AllocateNode* st_alloc = st_init->allocation(); 528 if (st_alloc == NULL) 529 break; // something degenerated 530 bool known_identical = false; 531 bool known_independent = false; 532 if (alloc == st_alloc) 533 known_identical = true; 534 else if (alloc != NULL) 535 known_independent = true; 536 else if (all_controls_dominate(this, st_alloc)) 537 known_independent = true; 538 539 if (known_independent) { 540 // The bases are provably independent: Either they are 541 // manifestly distinct allocations, or else the control 542 // of this load dominates the store's allocation. 543 int alias_idx = phase->C->get_alias_index(adr_type()); 544 if (alias_idx == Compile::AliasIdxRaw) { 545 mem = st_alloc->in(TypeFunc::Memory); 546 } else { 547 mem = st_init->memory(alias_idx); 548 } 549 continue; // (a) advance through independent store memory 550 } 551 552 // (b) at this point, if we are not looking at a store initializing 553 // the same allocation we are loading from, we lose. 554 if (known_identical) { 555 // From caller, can_see_stored_value will consult find_captured_store. 556 return mem; // let caller handle steps (c), (d) 557 } 558 559 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 560 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 561 if (mem->is_Proj() && mem->in(0)->is_Call()) { 562 CallNode *call = mem->in(0)->as_Call(); 563 if (!call->may_modify(addr_t, phase)) { 564 mem = call->in(TypeFunc::Memory); 565 continue; // (a) advance through independent call memory 566 } 567 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 568 mem = mem->in(0)->in(TypeFunc::Memory); 569 continue; // (a) advance through independent MemBar memory 570 } else if (mem->is_ClearArray()) { 571 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 572 // (the call updated 'mem' value) 573 continue; // (a) advance through independent allocation memory 574 } else { 575 // Can not bypass initialization of the instance 576 // we are looking for. 577 return mem; 578 } 579 } else if (mem->is_MergeMem()) { 580 int alias_idx = phase->C->get_alias_index(adr_type()); 581 mem = mem->as_MergeMem()->memory_at(alias_idx); 582 continue; // (a) advance through independent MergeMem memory 583 } 584 } 585 586 // Unless there is an explicit 'continue', we must bail out here, 587 // because 'mem' is an inscrutable memory state (e.g., a call). 588 break; 589 } 590 591 return NULL; // bail out 592 } 593 594 //----------------------calculate_adr_type------------------------------------- 595 // Helper function. Notices when the given type of address hits top or bottom. 596 // Also, asserts a cross-check of the type against the expected address type. 597 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 598 if (t == Type::TOP) return NULL; // does not touch memory any more? 599 #ifdef PRODUCT 600 cross_check = NULL; 601 #else 602 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL; 603 #endif 604 const TypePtr* tp = t->isa_ptr(); 605 if (tp == NULL) { 606 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 607 return TypePtr::BOTTOM; // touches lots of memory 608 } else { 609 #ifdef ASSERT 610 // %%%% [phh] We don't check the alias index if cross_check is 611 // TypeRawPtr::BOTTOM. Needs to be investigated. 612 if (cross_check != NULL && 613 cross_check != TypePtr::BOTTOM && 614 cross_check != TypeRawPtr::BOTTOM) { 615 // Recheck the alias index, to see if it has changed (due to a bug). 616 Compile* C = Compile::current(); 617 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 618 "must stay in the original alias category"); 619 // The type of the address must be contained in the adr_type, 620 // disregarding "null"-ness. 621 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 622 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 623 assert(cross_check->meet(tp_notnull) == cross_check, 624 "real address must not escape from expected memory type"); 625 } 626 #endif 627 return tp; 628 } 629 } 630 631 //------------------------adr_phi_is_loop_invariant---------------------------- 632 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted 633 // loop is loop invariant. Make a quick traversal of Phi and associated 634 // CastPP nodes, looking to see if they are a closed group within the loop. 635 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) { 636 // The idea is that the phi-nest must boil down to only CastPP nodes 637 // with the same data. This implies that any path into the loop already 638 // includes such a CastPP, and so the original cast, whatever its input, 639 // must be covered by an equivalent cast, with an earlier control input. 640 ResourceMark rm; 641 642 // The loop entry input of the phi should be the unique dominating 643 // node for every Phi/CastPP in the loop. 644 Unique_Node_List closure; 645 closure.push(adr_phi->in(LoopNode::EntryControl)); 646 647 // Add the phi node and the cast to the worklist. 648 Unique_Node_List worklist; 649 worklist.push(adr_phi); 650 if( cast != NULL ){ 651 if( !cast->is_ConstraintCast() ) return false; 652 worklist.push(cast); 653 } 654 655 // Begin recursive walk of phi nodes. 656 while( worklist.size() ){ 657 // Take a node off the worklist 658 Node *n = worklist.pop(); 659 if( !closure.member(n) ){ 660 // Add it to the closure. 661 closure.push(n); 662 // Make a sanity check to ensure we don't waste too much time here. 663 if( closure.size() > 20) return false; 664 // This node is OK if: 665 // - it is a cast of an identical value 666 // - or it is a phi node (then we add its inputs to the worklist) 667 // Otherwise, the node is not OK, and we presume the cast is not invariant 668 if( n->is_ConstraintCast() ){ 669 worklist.push(n->in(1)); 670 } else if( n->is_Phi() ) { 671 for( uint i = 1; i < n->req(); i++ ) { 672 worklist.push(n->in(i)); 673 } 674 } else { 675 return false; 676 } 677 } 678 } 679 680 // Quit when the worklist is empty, and we've found no offending nodes. 681 return true; 682 } 683 684 //------------------------------Ideal_DU_postCCP------------------------------- 685 // Find any cast-away of null-ness and keep its control. Null cast-aways are 686 // going away in this pass and we need to make this memory op depend on the 687 // gating null check. 688 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) { 689 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address)); 690 } 691 692 // I tried to leave the CastPP's in. This makes the graph more accurate in 693 // some sense; we get to keep around the knowledge that an oop is not-null 694 // after some test. Alas, the CastPP's interfere with GVN (some values are 695 // the regular oop, some are the CastPP of the oop, all merge at Phi's which 696 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed 697 // some of the more trivial cases in the optimizer. Removing more useless 698 // Phi's started allowing Loads to illegally float above null checks. I gave 699 // up on this approach. CNC 10/20/2000 700 // This static method may be called not from MemNode (EncodePNode calls it). 701 // Only the control edge of the node 'n' might be updated. 702 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) { 703 Node *skipped_cast = NULL; 704 // Need a null check? Regular static accesses do not because they are 705 // from constant addresses. Array ops are gated by the range check (which 706 // always includes a NULL check). Just check field ops. 707 if( n->in(MemNode::Control) == NULL ) { 708 // Scan upwards for the highest location we can place this memory op. 709 while( true ) { 710 switch( adr->Opcode() ) { 711 712 case Op_AddP: // No change to NULL-ness, so peek thru AddP's 713 adr = adr->in(AddPNode::Base); 714 continue; 715 716 case Op_DecodeN: // No change to NULL-ness, so peek thru 717 adr = adr->in(1); 718 continue; 719 720 case Op_CastPP: 721 // If the CastPP is useless, just peek on through it. 722 if( ccp->type(adr) == ccp->type(adr->in(1)) ) { 723 // Remember the cast that we've peeked though. If we peek 724 // through more than one, then we end up remembering the highest 725 // one, that is, if in a loop, the one closest to the top. 726 skipped_cast = adr; 727 adr = adr->in(1); 728 continue; 729 } 730 // CastPP is going away in this pass! We need this memory op to be 731 // control-dependent on the test that is guarding the CastPP. 732 ccp->hash_delete(n); 733 n->set_req(MemNode::Control, adr->in(0)); 734 ccp->hash_insert(n); 735 return n; 736 737 case Op_Phi: 738 // Attempt to float above a Phi to some dominating point. 739 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) { 740 // If we've already peeked through a Cast (which could have set the 741 // control), we can't float above a Phi, because the skipped Cast 742 // may not be loop invariant. 743 if (adr_phi_is_loop_invariant(adr, skipped_cast)) { 744 adr = adr->in(1); 745 continue; 746 } 747 } 748 749 // Intentional fallthrough! 750 751 // No obvious dominating point. The mem op is pinned below the Phi 752 // by the Phi itself. If the Phi goes away (no true value is merged) 753 // then the mem op can float, but not indefinitely. It must be pinned 754 // behind the controls leading to the Phi. 755 case Op_CheckCastPP: 756 // These usually stick around to change address type, however a 757 // useless one can be elided and we still need to pick up a control edge 758 if (adr->in(0) == NULL) { 759 // This CheckCastPP node has NO control and is likely useless. But we 760 // need check further up the ancestor chain for a control input to keep 761 // the node in place. 4959717. 762 skipped_cast = adr; 763 adr = adr->in(1); 764 continue; 765 } 766 ccp->hash_delete(n); 767 n->set_req(MemNode::Control, adr->in(0)); 768 ccp->hash_insert(n); 769 return n; 770 771 // List of "safe" opcodes; those that implicitly block the memory 772 // op below any null check. 773 case Op_CastX2P: // no null checks on native pointers 774 case Op_Parm: // 'this' pointer is not null 775 case Op_LoadP: // Loading from within a klass 776 case Op_LoadN: // Loading from within a klass 777 case Op_LoadKlass: // Loading from within a klass 778 case Op_LoadNKlass: // Loading from within a klass 779 case Op_ConP: // Loading from a klass 780 case Op_ConN: // Loading from a klass 781 case Op_CreateEx: // Sucking up the guts of an exception oop 782 case Op_Con: // Reading from TLS 783 case Op_CMoveP: // CMoveP is pinned 784 case Op_CMoveN: // CMoveN is pinned 785 break; // No progress 786 787 case Op_Proj: // Direct call to an allocation routine 788 case Op_SCMemProj: // Memory state from store conditional ops 789 #ifdef ASSERT 790 { 791 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value"); 792 const Node* call = adr->in(0); 793 if (call->is_CallJava()) { 794 const CallJavaNode* call_java = call->as_CallJava(); 795 const TypeTuple *r = call_java->tf()->range(); 796 assert(r->cnt() > TypeFunc::Parms, "must return value"); 797 const Type* ret_type = r->field_at(TypeFunc::Parms); 798 assert(ret_type && ret_type->isa_ptr(), "must return pointer"); 799 // We further presume that this is one of 800 // new_instance_Java, new_array_Java, or 801 // the like, but do not assert for this. 802 } else if (call->is_Allocate()) { 803 // similar case to new_instance_Java, etc. 804 } else if (!call->is_CallLeaf()) { 805 // Projections from fetch_oop (OSR) are allowed as well. 806 ShouldNotReachHere(); 807 } 808 } 809 #endif 810 break; 811 default: 812 ShouldNotReachHere(); 813 } 814 break; 815 } 816 } 817 818 return NULL; // No progress 819 } 820 821 822 //============================================================================= 823 uint LoadNode::size_of() const { return sizeof(*this); } 824 uint LoadNode::cmp( const Node &n ) const 825 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 826 const Type *LoadNode::bottom_type() const { return _type; } 827 uint LoadNode::ideal_reg() const { 828 return Matcher::base2reg[_type->base()]; 829 } 830 831 #ifndef PRODUCT 832 void LoadNode::dump_spec(outputStream *st) const { 833 MemNode::dump_spec(st); 834 if( !Verbose && !WizardMode ) { 835 // standard dump does this in Verbose and WizardMode 836 st->print(" #"); _type->dump_on(st); 837 } 838 } 839 #endif 840 841 #ifdef ASSERT 842 //----------------------------is_immutable_value------------------------------- 843 // Helper function to allow a raw load without control edge for some cases 844 bool LoadNode::is_immutable_value(Node* adr) { 845 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 846 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 847 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 848 in_bytes(JavaThread::osthread_offset()))); 849 } 850 #endif 851 852 //----------------------------LoadNode::make----------------------------------- 853 // Polymorphic factory method: 854 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) { 855 Compile* C = gvn.C; 856 857 // sanity check the alias category against the created node type 858 assert(!(adr_type->isa_oopptr() && 859 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 860 "use LoadKlassNode instead"); 861 assert(!(adr_type->isa_aryptr() && 862 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 863 "use LoadRangeNode instead"); 864 // Check control edge of raw loads 865 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 866 // oop will be recorded in oop map if load crosses safepoint 867 rt->isa_oopptr() || is_immutable_value(adr), 868 "raw memory operations should have control edge"); 869 switch (bt) { 870 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() ); 871 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() ); 872 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() ); 873 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() ); 874 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() ); 875 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() ); 876 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt ); 877 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt ); 878 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() ); 879 case T_OBJECT: 880 #ifdef _LP64 881 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 882 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop())); 883 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr()); 884 } else 885 #endif 886 { 887 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 888 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr()); 889 } 890 } 891 ShouldNotReachHere(); 892 return (LoadNode*)NULL; 893 } 894 895 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) { 896 bool require_atomic = true; 897 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic); 898 } 899 900 901 902 903 //------------------------------hash------------------------------------------- 904 uint LoadNode::hash() const { 905 // unroll addition of interesting fields 906 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 907 } 908 909 //---------------------------can_see_stored_value------------------------------ 910 // This routine exists to make sure this set of tests is done the same 911 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 912 // will change the graph shape in a way which makes memory alive twice at the 913 // same time (uses the Oracle model of aliasing), then some 914 // LoadXNode::Identity will fold things back to the equivalence-class model 915 // of aliasing. 916 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 917 Node* ld_adr = in(MemNode::Address); 918 919 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 920 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL; 921 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw && 922 atp->field() != NULL && !atp->field()->is_volatile()) { 923 uint alias_idx = atp->index(); 924 bool final = atp->field()->is_final(); 925 Node* result = NULL; 926 Node* current = st; 927 // Skip through chains of MemBarNodes checking the MergeMems for 928 // new states for the slice of this load. Stop once any other 929 // kind of node is encountered. Loads from final memory can skip 930 // through any kind of MemBar but normal loads shouldn't skip 931 // through MemBarAcquire since the could allow them to move out of 932 // a synchronized region. 933 while (current->is_Proj()) { 934 int opc = current->in(0)->Opcode(); 935 if ((final && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock)) || 936 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder || 937 opc == Op_MemBarReleaseLock) { 938 Node* mem = current->in(0)->in(TypeFunc::Memory); 939 if (mem->is_MergeMem()) { 940 MergeMemNode* merge = mem->as_MergeMem(); 941 Node* new_st = merge->memory_at(alias_idx); 942 if (new_st == merge->base_memory()) { 943 // Keep searching 944 current = merge->base_memory(); 945 continue; 946 } 947 // Save the new memory state for the slice and fall through 948 // to exit. 949 result = new_st; 950 } 951 } 952 break; 953 } 954 if (result != NULL) { 955 st = result; 956 } 957 } 958 959 960 // Loop around twice in the case Load -> Initialize -> Store. 961 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 962 for (int trip = 0; trip <= 1; trip++) { 963 964 if (st->is_Store()) { 965 Node* st_adr = st->in(MemNode::Address); 966 if (!phase->eqv(st_adr, ld_adr)) { 967 // Try harder before giving up... Match raw and non-raw pointers. 968 intptr_t st_off = 0; 969 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 970 if (alloc == NULL) return NULL; 971 intptr_t ld_off = 0; 972 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 973 if (alloc != allo2) return NULL; 974 if (ld_off != st_off) return NULL; 975 // At this point we have proven something like this setup: 976 // A = Allocate(...) 977 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 978 // S = StoreQ(, AddP(, A.Parm , #Off), V) 979 // (Actually, we haven't yet proven the Q's are the same.) 980 // In other words, we are loading from a casted version of 981 // the same pointer-and-offset that we stored to. 982 // Thus, we are able to replace L by V. 983 } 984 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 985 if (store_Opcode() != st->Opcode()) 986 return NULL; 987 return st->in(MemNode::ValueIn); 988 } 989 990 intptr_t offset = 0; // scratch 991 992 // A load from a freshly-created object always returns zero. 993 // (This can happen after LoadNode::Ideal resets the load's memory input 994 // to find_captured_store, which returned InitializeNode::zero_memory.) 995 if (st->is_Proj() && st->in(0)->is_Allocate() && 996 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) && 997 offset >= st->in(0)->as_Allocate()->minimum_header_size()) { 998 // return a zero value for the load's basic type 999 // (This is one of the few places where a generic PhaseTransform 1000 // can create new nodes. Think of it as lazily manifesting 1001 // virtually pre-existing constants.) 1002 return phase->zerocon(memory_type()); 1003 } 1004 1005 // A load from an initialization barrier can match a captured store. 1006 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1007 InitializeNode* init = st->in(0)->as_Initialize(); 1008 AllocateNode* alloc = init->allocation(); 1009 if (alloc != NULL && 1010 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) { 1011 // examine a captured store value 1012 st = init->find_captured_store(offset, memory_size(), phase); 1013 if (st != NULL) 1014 continue; // take one more trip around 1015 } 1016 } 1017 1018 break; 1019 } 1020 1021 return NULL; 1022 } 1023 1024 //----------------------is_instance_field_load_with_local_phi------------------ 1025 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1026 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl && 1027 in(MemNode::Address)->is_AddP() ) { 1028 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr(); 1029 // Only instances. 1030 if( t_oop != NULL && t_oop->is_known_instance_field() && 1031 t_oop->offset() != Type::OffsetBot && 1032 t_oop->offset() != Type::OffsetTop) { 1033 return true; 1034 } 1035 } 1036 return false; 1037 } 1038 1039 //------------------------------Identity--------------------------------------- 1040 // Loads are identity if previous store is to same address 1041 Node *LoadNode::Identity( PhaseTransform *phase ) { 1042 // If the previous store-maker is the right kind of Store, and the store is 1043 // to the same address, then we are equal to the value stored. 1044 Node* mem = in(MemNode::Memory); 1045 Node* value = can_see_stored_value(mem, phase); 1046 if( value ) { 1047 // byte, short & char stores truncate naturally. 1048 // A load has to load the truncated value which requires 1049 // some sort of masking operation and that requires an 1050 // Ideal call instead of an Identity call. 1051 if (memory_size() < BytesPerInt) { 1052 // If the input to the store does not fit with the load's result type, 1053 // it must be truncated via an Ideal call. 1054 if (!phase->type(value)->higher_equal(phase->type(this))) 1055 return this; 1056 } 1057 // (This works even when value is a Con, but LoadNode::Value 1058 // usually runs first, producing the singleton type of the Con.) 1059 return value; 1060 } 1061 1062 // Search for an existing data phi which was generated before for the same 1063 // instance's field to avoid infinite generation of phis in a loop. 1064 Node *region = mem->in(0); 1065 if (is_instance_field_load_with_local_phi(region)) { 1066 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr(); 1067 int this_index = phase->C->get_alias_index(addr_t); 1068 int this_offset = addr_t->offset(); 1069 int this_id = addr_t->is_oopptr()->instance_id(); 1070 const Type* this_type = bottom_type(); 1071 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1072 Node* phi = region->fast_out(i); 1073 if (phi->is_Phi() && phi != mem && 1074 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) { 1075 return phi; 1076 } 1077 } 1078 } 1079 1080 return this; 1081 } 1082 1083 1084 // Returns true if the AliasType refers to the field that holds the 1085 // cached box array. Currently only handles the IntegerCache case. 1086 static bool is_autobox_cache(Compile::AliasType* atp) { 1087 if (atp != NULL && atp->field() != NULL) { 1088 ciField* field = atp->field(); 1089 ciSymbol* klass = field->holder()->name(); 1090 if (field->name() == ciSymbol::cache_field_name() && 1091 field->holder()->uses_default_loader() && 1092 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 1093 return true; 1094 } 1095 } 1096 return false; 1097 } 1098 1099 // Fetch the base value in the autobox array 1100 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) { 1101 if (atp != NULL && atp->field() != NULL) { 1102 ciField* field = atp->field(); 1103 ciSymbol* klass = field->holder()->name(); 1104 if (field->name() == ciSymbol::cache_field_name() && 1105 field->holder()->uses_default_loader() && 1106 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 1107 assert(field->is_constant(), "what?"); 1108 ciObjArray* array = field->constant_value().as_object()->as_obj_array(); 1109 // Fetch the box object at the base of the array and get its value 1110 ciInstance* box = array->obj_at(0)->as_instance(); 1111 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1112 if (ik->nof_nonstatic_fields() == 1) { 1113 // This should be true nonstatic_field_at requires calling 1114 // nof_nonstatic_fields so check it anyway 1115 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1116 cache_offset = c.as_int(); 1117 } 1118 return true; 1119 } 1120 } 1121 return false; 1122 } 1123 1124 // Returns true if the AliasType refers to the value field of an 1125 // autobox object. Currently only handles Integer. 1126 static bool is_autobox_object(Compile::AliasType* atp) { 1127 if (atp != NULL && atp->field() != NULL) { 1128 ciField* field = atp->field(); 1129 ciSymbol* klass = field->holder()->name(); 1130 if (field->name() == ciSymbol::value_name() && 1131 field->holder()->uses_default_loader() && 1132 klass == ciSymbol::java_lang_Integer()) { 1133 return true; 1134 } 1135 } 1136 return false; 1137 } 1138 1139 1140 // We're loading from an object which has autobox behaviour. 1141 // If this object is result of a valueOf call we'll have a phi 1142 // merging a newly allocated object and a load from the cache. 1143 // We want to replace this load with the original incoming 1144 // argument to the valueOf call. 1145 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1146 Node* base = in(Address)->in(AddPNode::Base); 1147 if (base->is_Phi() && base->req() == 3) { 1148 AllocateNode* allocation = NULL; 1149 int allocation_index = -1; 1150 int load_index = -1; 1151 for (uint i = 1; i < base->req(); i++) { 1152 allocation = AllocateNode::Ideal_allocation(base->in(i), phase); 1153 if (allocation != NULL) { 1154 allocation_index = i; 1155 load_index = 3 - allocation_index; 1156 break; 1157 } 1158 } 1159 bool has_load = ( allocation != NULL && 1160 (base->in(load_index)->is_Load() || 1161 base->in(load_index)->is_DecodeN() && 1162 base->in(load_index)->in(1)->is_Load()) ); 1163 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) { 1164 // Push the loads from the phi that comes from valueOf up 1165 // through it to allow elimination of the loads and the recovery 1166 // of the original value. 1167 Node* mem_phi = in(Memory); 1168 Node* offset = in(Address)->in(AddPNode::Offset); 1169 Node* region = base->in(0); 1170 1171 Node* in1 = clone(); 1172 Node* in1_addr = in1->in(Address)->clone(); 1173 in1_addr->set_req(AddPNode::Base, base->in(allocation_index)); 1174 in1_addr->set_req(AddPNode::Address, base->in(allocation_index)); 1175 in1_addr->set_req(AddPNode::Offset, offset); 1176 in1->set_req(0, region->in(allocation_index)); 1177 in1->set_req(Address, in1_addr); 1178 in1->set_req(Memory, mem_phi->in(allocation_index)); 1179 1180 Node* in2 = clone(); 1181 Node* in2_addr = in2->in(Address)->clone(); 1182 in2_addr->set_req(AddPNode::Base, base->in(load_index)); 1183 in2_addr->set_req(AddPNode::Address, base->in(load_index)); 1184 in2_addr->set_req(AddPNode::Offset, offset); 1185 in2->set_req(0, region->in(load_index)); 1186 in2->set_req(Address, in2_addr); 1187 in2->set_req(Memory, mem_phi->in(load_index)); 1188 1189 in1_addr = phase->transform(in1_addr); 1190 in1 = phase->transform(in1); 1191 in2_addr = phase->transform(in2_addr); 1192 in2 = phase->transform(in2); 1193 1194 PhiNode* result = PhiNode::make_blank(region, this); 1195 result->set_req(allocation_index, in1); 1196 result->set_req(load_index, in2); 1197 return result; 1198 } 1199 } else if (base->is_Load() || 1200 base->is_DecodeN() && base->in(1)->is_Load()) { 1201 if (base->is_DecodeN()) { 1202 // Get LoadN node which loads cached Integer object 1203 base = base->in(1); 1204 } 1205 // Eliminate the load of Integer.value for integers from the cache 1206 // array by deriving the value from the index into the array. 1207 // Capture the offset of the load and then reverse the computation. 1208 Node* load_base = base->in(Address)->in(AddPNode::Base); 1209 if (load_base->is_DecodeN()) { 1210 // Get LoadN node which loads IntegerCache.cache field 1211 load_base = load_base->in(1); 1212 } 1213 if (load_base != NULL) { 1214 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type()); 1215 intptr_t cache_offset; 1216 int shift = -1; 1217 Node* cache = NULL; 1218 if (is_autobox_cache(atp)) { 1219 shift = exact_log2(type2aelembytes(T_OBJECT)); 1220 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset); 1221 } 1222 if (cache != NULL && base->in(Address)->is_AddP()) { 1223 Node* elements[4]; 1224 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements)); 1225 int cache_low; 1226 if (count > 0 && fetch_autobox_base(atp, cache_low)) { 1227 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift); 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 (phase->C, 3) AddXNode(result, elements[i])); 1232 } 1233 // Remove the constant offset from the address and then 1234 // remove the scaling of the offset to recover the original index. 1235 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset))); 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 (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0)); 1240 } else { 1241 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift)); 1242 } 1243 #ifdef _LP64 1244 result = new (phase->C, 2) ConvL2INode(phase->transform(result)); 1245 #endif 1246 return result; 1247 } 1248 } 1249 } 1250 } 1251 return NULL; 1252 } 1253 1254 //------------------------------split_through_phi------------------------------ 1255 // Split instance field load through Phi. 1256 Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1257 Node* mem = in(MemNode::Memory); 1258 Node* address = in(MemNode::Address); 1259 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1260 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1261 1262 assert(mem->is_Phi() && (t_oop != NULL) && 1263 t_oop->is_known_instance_field(), "invalide conditions"); 1264 1265 Node *region = mem->in(0); 1266 if (region == NULL) { 1267 return NULL; // Wait stable graph 1268 } 1269 uint cnt = mem->req(); 1270 for (uint i = 1; i < cnt; i++) { 1271 Node* rc = region->in(i); 1272 if (rc == NULL || phase->type(rc) == Type::TOP) 1273 return NULL; // Wait stable graph 1274 Node *in = mem->in(i); 1275 if (in == NULL) { 1276 return NULL; // Wait stable graph 1277 } 1278 } 1279 // Check for loop invariant. 1280 if (cnt == 3) { 1281 for (uint i = 1; i < cnt; i++) { 1282 Node *in = mem->in(i); 1283 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase); 1284 if (m == mem) { 1285 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi. 1286 return this; 1287 } 1288 } 1289 } 1290 // Split through Phi (see original code in loopopts.cpp). 1291 assert(phase->C->have_alias_type(addr_t), "instance should have alias type"); 1292 1293 // Do nothing here if Identity will find a value 1294 // (to avoid infinite chain of value phis generation). 1295 if (!phase->eqv(this, this->Identity(phase))) 1296 return NULL; 1297 1298 // Skip the split if the region dominates some control edge of the address. 1299 if (!MemNode::all_controls_dominate(address, region)) 1300 return NULL; 1301 1302 const Type* this_type = this->bottom_type(); 1303 int this_index = phase->C->get_alias_index(addr_t); 1304 int this_offset = addr_t->offset(); 1305 int this_iid = addr_t->is_oopptr()->instance_id(); 1306 PhaseIterGVN *igvn = phase->is_IterGVN(); 1307 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset); 1308 for (uint i = 1; i < region->req(); i++) { 1309 Node *x; 1310 Node* the_clone = NULL; 1311 if (region->in(i) == phase->C->top()) { 1312 x = phase->C->top(); // Dead path? Use a dead data op 1313 } else { 1314 x = this->clone(); // Else clone up the data op 1315 the_clone = x; // Remember for possible deletion. 1316 // Alter data node to use pre-phi inputs 1317 if (this->in(0) == region) { 1318 x->set_req(0, region->in(i)); 1319 } else { 1320 x->set_req(0, NULL); 1321 } 1322 for (uint j = 1; j < this->req(); j++) { 1323 Node *in = this->in(j); 1324 if (in->is_Phi() && in->in(0) == region) 1325 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone 1326 } 1327 } 1328 // Check for a 'win' on some paths 1329 const Type *t = x->Value(igvn); 1330 1331 bool singleton = t->singleton(); 1332 1333 // See comments in PhaseIdealLoop::split_thru_phi(). 1334 if (singleton && t == Type::TOP) { 1335 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1336 } 1337 1338 if (singleton) { 1339 x = igvn->makecon(t); 1340 } else { 1341 // We now call Identity to try to simplify the cloned node. 1342 // Note that some Identity methods call phase->type(this). 1343 // Make sure that the type array is big enough for 1344 // our new node, even though we may throw the node away. 1345 // (This tweaking with igvn only works because x is a new node.) 1346 igvn->set_type(x, t); 1347 // If x is a TypeNode, capture any more-precise type permanently into Node 1348 // otherwise it will be not updated during igvn->transform since 1349 // igvn->type(x) is set to x->Value() already. 1350 x->raise_bottom_type(t); 1351 Node *y = x->Identity(igvn); 1352 if (y != x) { 1353 x = y; 1354 } else { 1355 y = igvn->hash_find(x); 1356 if (y) { 1357 x = y; 1358 } else { 1359 // Else x is a new node we are keeping 1360 // We do not need register_new_node_with_optimizer 1361 // because set_type has already been called. 1362 igvn->_worklist.push(x); 1363 } 1364 } 1365 } 1366 if (x != the_clone && the_clone != NULL) 1367 igvn->remove_dead_node(the_clone); 1368 phi->set_req(i, x); 1369 } 1370 // Record Phi 1371 igvn->register_new_node_with_optimizer(phi); 1372 return phi; 1373 } 1374 1375 //------------------------------Ideal------------------------------------------ 1376 // If the load is from Field memory and the pointer is non-null, we can 1377 // zero out the control input. 1378 // If the offset is constant and the base is an object allocation, 1379 // try to hook me up to the exact initializing store. 1380 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1381 Node* p = MemNode::Ideal_common(phase, can_reshape); 1382 if (p) return (p == NodeSentinel) ? NULL : p; 1383 1384 Node* ctrl = in(MemNode::Control); 1385 Node* address = in(MemNode::Address); 1386 1387 // Skip up past a SafePoint control. Cannot do this for Stores because 1388 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1389 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1390 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1391 ctrl = ctrl->in(0); 1392 set_req(MemNode::Control,ctrl); 1393 } 1394 1395 intptr_t ignore = 0; 1396 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1397 if (base != NULL 1398 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1399 // Check for useless control edge in some common special cases 1400 if (in(MemNode::Control) != NULL 1401 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1402 && all_controls_dominate(base, phase->C->start())) { 1403 // A method-invariant, non-null address (constant or 'this' argument). 1404 set_req(MemNode::Control, NULL); 1405 } 1406 1407 if (EliminateAutoBox && can_reshape) { 1408 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null"); 1409 Compile::AliasType* atp = phase->C->alias_type(adr_type()); 1410 if (is_autobox_object(atp)) { 1411 Node* result = eliminate_autobox(phase); 1412 if (result != NULL) return result; 1413 } 1414 } 1415 } 1416 1417 Node* mem = in(MemNode::Memory); 1418 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1419 1420 if (addr_t != NULL) { 1421 // try to optimize our memory input 1422 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase); 1423 if (opt_mem != mem) { 1424 set_req(MemNode::Memory, opt_mem); 1425 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1426 return this; 1427 } 1428 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1429 if (can_reshape && opt_mem->is_Phi() && 1430 (t_oop != NULL) && t_oop->is_known_instance_field()) { 1431 PhaseIterGVN *igvn = phase->is_IterGVN(); 1432 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1433 // Delay this transformation until memory Phi is processed. 1434 phase->is_IterGVN()->_worklist.push(this); 1435 return NULL; 1436 } 1437 // Split instance field load through Phi. 1438 Node* result = split_through_phi(phase); 1439 if (result != NULL) return result; 1440 } 1441 } 1442 1443 // Check for prior store with a different base or offset; make Load 1444 // independent. Skip through any number of them. Bail out if the stores 1445 // are in an endless dead cycle and report no progress. This is a key 1446 // transform for Reflection. However, if after skipping through the Stores 1447 // we can't then fold up against a prior store do NOT do the transform as 1448 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1449 // array memory alive twice: once for the hoisted Load and again after the 1450 // bypassed Store. This situation only works if EVERYBODY who does 1451 // anti-dependence work knows how to bypass. I.e. we need all 1452 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1453 // the alias index stuff. So instead, peek through Stores and IFF we can 1454 // fold up, do so. 1455 Node* prev_mem = find_previous_store(phase); 1456 // Steps (a), (b): Walk past independent stores to find an exact match. 1457 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1458 // (c) See if we can fold up on the spot, but don't fold up here. 1459 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1460 // just return a prior value, which is done by Identity calls. 1461 if (can_see_stored_value(prev_mem, phase)) { 1462 // Make ready for step (d): 1463 set_req(MemNode::Memory, prev_mem); 1464 return this; 1465 } 1466 } 1467 1468 return NULL; // No further progress 1469 } 1470 1471 // Helper to recognize certain Klass fields which are invariant across 1472 // some group of array types (e.g., int[] or all T[] where T < Object). 1473 const Type* 1474 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1475 ciKlass* klass) const { 1476 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1477 // The field is Klass::_modifier_flags. Return its (constant) value. 1478 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1479 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1480 return TypeInt::make(klass->modifier_flags()); 1481 } 1482 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1483 // The field is Klass::_access_flags. Return its (constant) value. 1484 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1485 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1486 return TypeInt::make(klass->access_flags()); 1487 } 1488 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1489 // The field is Klass::_layout_helper. Return its constant value if known. 1490 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1491 return TypeInt::make(klass->layout_helper()); 1492 } 1493 1494 // No match. 1495 return NULL; 1496 } 1497 1498 //------------------------------Value----------------------------------------- 1499 const Type *LoadNode::Value( PhaseTransform *phase ) const { 1500 // Either input is TOP ==> the result is TOP 1501 Node* mem = in(MemNode::Memory); 1502 const Type *t1 = phase->type(mem); 1503 if (t1 == Type::TOP) return Type::TOP; 1504 Node* adr = in(MemNode::Address); 1505 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1506 if (tp == NULL || tp->empty()) return Type::TOP; 1507 int off = tp->offset(); 1508 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1509 Compile* C = phase->C; 1510 1511 // Try to guess loaded type from pointer type 1512 if (tp->base() == Type::AryPtr) { 1513 const Type *t = tp->is_aryptr()->elem(); 1514 // Don't do this for integer types. There is only potential profit if 1515 // the element type t is lower than _type; that is, for int types, if _type is 1516 // more restrictive than t. This only happens here if one is short and the other 1517 // char (both 16 bits), and in those cases we've made an intentional decision 1518 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1519 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1520 // 1521 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1522 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1523 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1524 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1525 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1526 // In fact, that could have been the original type of p1, and p1 could have 1527 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1528 // expression (LShiftL quux 3) independently optimized to the constant 8. 1529 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1530 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1531 // t might actually be lower than _type, if _type is a unique 1532 // concrete subclass of abstract class t. 1533 // Make sure the reference is not into the header, by comparing 1534 // the offset against the offset of the start of the array's data. 1535 // Different array types begin at slightly different offsets (12 vs. 16). 1536 // We choose T_BYTE as an example base type that is least restrictive 1537 // as to alignment, which will therefore produce the smallest 1538 // possible base offset. 1539 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1540 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header? 1541 const Type* jt = t->join(_type); 1542 // In any case, do not allow the join, per se, to empty out the type. 1543 if (jt->empty() && !t->empty()) { 1544 // This can happen if a interface-typed array narrows to a class type. 1545 jt = _type; 1546 } 1547 1548 if (EliminateAutoBox && adr->is_AddP()) { 1549 // The pointers in the autobox arrays are always non-null 1550 Node* base = adr->in(AddPNode::Base); 1551 if (base != NULL && 1552 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) { 1553 Compile::AliasType* atp = C->alias_type(base->adr_type()); 1554 if (is_autobox_cache(atp)) { 1555 return jt->join(TypePtr::NOTNULL)->is_ptr(); 1556 } 1557 } 1558 } 1559 return jt; 1560 } 1561 } 1562 } else if (tp->base() == Type::InstPtr) { 1563 ciEnv* env = C->env(); 1564 const TypeInstPtr* tinst = tp->is_instptr(); 1565 ciKlass* klass = tinst->klass(); 1566 assert( off != Type::OffsetBot || 1567 // arrays can be cast to Objects 1568 tp->is_oopptr()->klass()->is_java_lang_Object() || 1569 // unsafe field access may not have a constant offset 1570 C->has_unsafe_access(), 1571 "Field accesses must be precise" ); 1572 // For oop loads, we expect the _type to be precise 1573 if (klass == env->String_klass() && 1574 adr->is_AddP() && off != Type::OffsetBot) { 1575 // For constant Strings treat the final fields as compile time constants. 1576 Node* base = adr->in(AddPNode::Base); 1577 const TypeOopPtr* t = phase->type(base)->isa_oopptr(); 1578 if (t != NULL && t->singleton()) { 1579 ciField* field = env->String_klass()->get_field_by_offset(off, false); 1580 if (field != NULL && field->is_final()) { 1581 ciObject* string = t->const_oop(); 1582 ciConstant constant = string->as_instance()->field_value(field); 1583 if (constant.basic_type() == T_INT) { 1584 return TypeInt::make(constant.as_int()); 1585 } else if (constant.basic_type() == T_ARRAY) { 1586 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1587 return TypeNarrowOop::make_from_constant(constant.as_object(), true); 1588 } else { 1589 return TypeOopPtr::make_from_constant(constant.as_object(), true); 1590 } 1591 } 1592 } 1593 } 1594 } 1595 // Optimizations for constant objects 1596 ciObject* const_oop = tinst->const_oop(); 1597 if (const_oop != NULL) { 1598 // For constant CallSites treat the target field as a compile time constant. 1599 if (const_oop->is_call_site()) { 1600 ciCallSite* call_site = const_oop->as_call_site(); 1601 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false); 1602 if (field != NULL && field->is_call_site_target()) { 1603 ciMethodHandle* target = call_site->get_target(); 1604 if (target != NULL) { // just in case 1605 ciConstant constant(T_OBJECT, target); 1606 const Type* t; 1607 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1608 t = TypeNarrowOop::make_from_constant(constant.as_object(), true); 1609 } else { 1610 t = TypeOopPtr::make_from_constant(constant.as_object(), true); 1611 } 1612 // Add a dependence for invalidation of the optimization. 1613 if (!call_site->is_constant_call_site()) { 1614 C->dependencies()->assert_call_site_target_value(call_site, target); 1615 } 1616 return t; 1617 } 1618 } 1619 } 1620 } 1621 } else if (tp->base() == Type::KlassPtr) { 1622 assert( off != Type::OffsetBot || 1623 // arrays can be cast to Objects 1624 tp->is_klassptr()->klass()->is_java_lang_Object() || 1625 // also allow array-loading from the primary supertype 1626 // array during subtype checks 1627 Opcode() == Op_LoadKlass, 1628 "Field accesses must be precise" ); 1629 // For klass/static loads, we expect the _type to be precise 1630 } 1631 1632 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1633 if (tkls != NULL && !StressReflectiveCode) { 1634 ciKlass* klass = tkls->klass(); 1635 if (klass->is_loaded() && tkls->klass_is_exact()) { 1636 // We are loading a field from a Klass metaobject whose identity 1637 // is known at compile time (the type is "exact" or "precise"). 1638 // Check for fields we know are maintained as constants by the VM. 1639 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1640 // The field is Klass::_super_check_offset. Return its (constant) value. 1641 // (Folds up type checking code.) 1642 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1643 return TypeInt::make(klass->super_check_offset()); 1644 } 1645 // Compute index into primary_supers array 1646 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(klassOop); 1647 // Check for overflowing; use unsigned compare to handle the negative case. 1648 if( depth < ciKlass::primary_super_limit() ) { 1649 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1650 // (Folds up type checking code.) 1651 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1652 ciKlass *ss = klass->super_of_depth(depth); 1653 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1654 } 1655 const Type* aift = load_array_final_field(tkls, klass); 1656 if (aift != NULL) return aift; 1657 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) 1658 && klass->is_array_klass()) { 1659 // The field is arrayKlass::_component_mirror. Return its (constant) value. 1660 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.) 1661 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror"); 1662 return TypeInstPtr::make(klass->as_array_klass()->component_mirror()); 1663 } 1664 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1665 // The field is Klass::_java_mirror. Return its (constant) value. 1666 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1667 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1668 return TypeInstPtr::make(klass->java_mirror()); 1669 } 1670 } 1671 1672 // We can still check if we are loading from the primary_supers array at a 1673 // shallow enough depth. Even though the klass is not exact, entries less 1674 // than or equal to its super depth are correct. 1675 if (klass->is_loaded() ) { 1676 ciType *inner = klass->klass(); 1677 while( inner->is_obj_array_klass() ) 1678 inner = inner->as_obj_array_klass()->base_element_type(); 1679 if( inner->is_instance_klass() && 1680 !inner->as_instance_klass()->flags().is_interface() ) { 1681 // Compute index into primary_supers array 1682 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(klassOop); 1683 // Check for overflowing; use unsigned compare to handle the negative case. 1684 if( depth < ciKlass::primary_super_limit() && 1685 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1686 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1687 // (Folds up type checking code.) 1688 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1689 ciKlass *ss = klass->super_of_depth(depth); 1690 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1691 } 1692 } 1693 } 1694 1695 // If the type is enough to determine that the thing is not an array, 1696 // we can give the layout_helper a positive interval type. 1697 // This will help short-circuit some reflective code. 1698 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1699 && !klass->is_array_klass() // not directly typed as an array 1700 && !klass->is_interface() // specifically not Serializable & Cloneable 1701 && !klass->is_java_lang_Object() // not the supertype of all T[] 1702 ) { 1703 // Note: When interfaces are reliable, we can narrow the interface 1704 // test to (klass != Serializable && klass != Cloneable). 1705 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1706 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1707 // The key property of this type is that it folds up tests 1708 // for array-ness, since it proves that the layout_helper is positive. 1709 // Thus, a generic value like the basic object layout helper works fine. 1710 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1711 } 1712 } 1713 1714 // If we are loading from a freshly-allocated object, produce a zero, 1715 // if the load is provably beyond the header of the object. 1716 // (Also allow a variable load from a fresh array to produce zero.) 1717 const TypeOopPtr *tinst = tp->isa_oopptr(); 1718 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1719 if (ReduceFieldZeroing || is_instance) { 1720 Node* value = can_see_stored_value(mem,phase); 1721 if (value != NULL && value->is_Con()) 1722 return value->bottom_type(); 1723 } 1724 1725 if (is_instance) { 1726 // If we have an instance type and our memory input is the 1727 // programs's initial memory state, there is no matching store, 1728 // so just return a zero of the appropriate type 1729 Node *mem = in(MemNode::Memory); 1730 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1731 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1732 return Type::get_zero_type(_type->basic_type()); 1733 } 1734 } 1735 return _type; 1736 } 1737 1738 //------------------------------match_edge------------------------------------- 1739 // Do we Match on this edge index or not? Match only the address. 1740 uint LoadNode::match_edge(uint idx) const { 1741 return idx == MemNode::Address; 1742 } 1743 1744 //--------------------------LoadBNode::Ideal-------------------------------------- 1745 // 1746 // If the previous store is to the same address as this load, 1747 // and the value stored was larger than a byte, replace this load 1748 // with the value stored truncated to a byte. If no truncation is 1749 // needed, the replacement is done in LoadNode::Identity(). 1750 // 1751 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1752 Node* mem = in(MemNode::Memory); 1753 Node* value = can_see_stored_value(mem,phase); 1754 if( value && !phase->type(value)->higher_equal( _type ) ) { 1755 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) ); 1756 return new (phase->C, 3) RShiftINode(result, phase->intcon(24)); 1757 } 1758 // Identity call will handle the case where truncation is not needed. 1759 return LoadNode::Ideal(phase, can_reshape); 1760 } 1761 1762 //--------------------------LoadUBNode::Ideal------------------------------------- 1763 // 1764 // If the previous store is to the same address as this load, 1765 // and the value stored was larger than a byte, replace this load 1766 // with the value stored truncated to a byte. If no truncation is 1767 // needed, the replacement is done in LoadNode::Identity(). 1768 // 1769 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 1770 Node* mem = in(MemNode::Memory); 1771 Node* value = can_see_stored_value(mem, phase); 1772 if (value && !phase->type(value)->higher_equal(_type)) 1773 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF)); 1774 // Identity call will handle the case where truncation is not needed. 1775 return LoadNode::Ideal(phase, can_reshape); 1776 } 1777 1778 //--------------------------LoadUSNode::Ideal------------------------------------- 1779 // 1780 // If the previous store is to the same address as this load, 1781 // and the value stored was larger than a char, replace this load 1782 // with the value stored truncated to a char. If no truncation is 1783 // needed, the replacement is done in LoadNode::Identity(). 1784 // 1785 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1786 Node* mem = in(MemNode::Memory); 1787 Node* value = can_see_stored_value(mem,phase); 1788 if( value && !phase->type(value)->higher_equal( _type ) ) 1789 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF)); 1790 // Identity call will handle the case where truncation is not needed. 1791 return LoadNode::Ideal(phase, can_reshape); 1792 } 1793 1794 //--------------------------LoadSNode::Ideal-------------------------------------- 1795 // 1796 // If the previous store is to the same address as this load, 1797 // and the value stored was larger than a short, replace this load 1798 // with the value stored truncated to a short. If no truncation is 1799 // needed, the replacement is done in LoadNode::Identity(). 1800 // 1801 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1802 Node* mem = in(MemNode::Memory); 1803 Node* value = can_see_stored_value(mem,phase); 1804 if( value && !phase->type(value)->higher_equal( _type ) ) { 1805 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) ); 1806 return new (phase->C, 3) RShiftINode(result, phase->intcon(16)); 1807 } 1808 // Identity call will handle the case where truncation is not needed. 1809 return LoadNode::Ideal(phase, can_reshape); 1810 } 1811 1812 //============================================================================= 1813 //----------------------------LoadKlassNode::make------------------------------ 1814 // Polymorphic factory method: 1815 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) { 1816 Compile* C = gvn.C; 1817 Node *ctl = NULL; 1818 // sanity check the alias category against the created node type 1819 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr(); 1820 assert(adr_type != NULL, "expecting TypeOopPtr"); 1821 #ifdef _LP64 1822 if (adr_type->is_ptr_to_narrowoop()) { 1823 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop())); 1824 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr()); 1825 } 1826 #endif 1827 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 1828 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk); 1829 } 1830 1831 //------------------------------Value------------------------------------------ 1832 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { 1833 return klass_value_common(phase); 1834 } 1835 1836 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const { 1837 // Either input is TOP ==> the result is TOP 1838 const Type *t1 = phase->type( in(MemNode::Memory) ); 1839 if (t1 == Type::TOP) return Type::TOP; 1840 Node *adr = in(MemNode::Address); 1841 const Type *t2 = phase->type( adr ); 1842 if (t2 == Type::TOP) return Type::TOP; 1843 const TypePtr *tp = t2->is_ptr(); 1844 if (TypePtr::above_centerline(tp->ptr()) || 1845 tp->ptr() == TypePtr::Null) return Type::TOP; 1846 1847 // Return a more precise klass, if possible 1848 const TypeInstPtr *tinst = tp->isa_instptr(); 1849 if (tinst != NULL) { 1850 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 1851 int offset = tinst->offset(); 1852 if (ik == phase->C->env()->Class_klass() 1853 && (offset == java_lang_Class::klass_offset_in_bytes() || 1854 offset == java_lang_Class::array_klass_offset_in_bytes())) { 1855 // We are loading a special hidden field from a Class mirror object, 1856 // the field which points to the VM's Klass metaobject. 1857 ciType* t = tinst->java_mirror_type(); 1858 // java_mirror_type returns non-null for compile-time Class constants. 1859 if (t != NULL) { 1860 // constant oop => constant klass 1861 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 1862 return TypeKlassPtr::make(ciArrayKlass::make(t)); 1863 } 1864 if (!t->is_klass()) { 1865 // a primitive Class (e.g., int.class) has NULL for a klass field 1866 return TypePtr::NULL_PTR; 1867 } 1868 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 1869 return TypeKlassPtr::make(t->as_klass()); 1870 } 1871 // non-constant mirror, so we can't tell what's going on 1872 } 1873 if( !ik->is_loaded() ) 1874 return _type; // Bail out if not loaded 1875 if (offset == oopDesc::klass_offset_in_bytes()) { 1876 if (tinst->klass_is_exact()) { 1877 return TypeKlassPtr::make(ik); 1878 } 1879 // See if we can become precise: no subklasses and no interface 1880 // (Note: We need to support verified interfaces.) 1881 if (!ik->is_interface() && !ik->has_subklass()) { 1882 //assert(!UseExactTypes, "this code should be useless with exact types"); 1883 // Add a dependence; if any subclass added we need to recompile 1884 if (!ik->is_final()) { 1885 // %%% should use stronger assert_unique_concrete_subtype instead 1886 phase->C->dependencies()->assert_leaf_type(ik); 1887 } 1888 // Return precise klass 1889 return TypeKlassPtr::make(ik); 1890 } 1891 1892 // Return root of possible klass 1893 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 1894 } 1895 } 1896 1897 // Check for loading klass from an array 1898 const TypeAryPtr *tary = tp->isa_aryptr(); 1899 if( tary != NULL ) { 1900 ciKlass *tary_klass = tary->klass(); 1901 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 1902 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 1903 if (tary->klass_is_exact()) { 1904 return TypeKlassPtr::make(tary_klass); 1905 } 1906 ciArrayKlass *ak = tary->klass()->as_array_klass(); 1907 // If the klass is an object array, we defer the question to the 1908 // array component klass. 1909 if( ak->is_obj_array_klass() ) { 1910 assert( ak->is_loaded(), "" ); 1911 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 1912 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 1913 ciInstanceKlass* ik = base_k->as_instance_klass(); 1914 // See if we can become precise: no subklasses and no interface 1915 if (!ik->is_interface() && !ik->has_subklass()) { 1916 //assert(!UseExactTypes, "this code should be useless with exact types"); 1917 // Add a dependence; if any subclass added we need to recompile 1918 if (!ik->is_final()) { 1919 phase->C->dependencies()->assert_leaf_type(ik); 1920 } 1921 // Return precise array klass 1922 return TypeKlassPtr::make(ak); 1923 } 1924 } 1925 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 1926 } else { // Found a type-array? 1927 //assert(!UseExactTypes, "this code should be useless with exact types"); 1928 assert( ak->is_type_array_klass(), "" ); 1929 return TypeKlassPtr::make(ak); // These are always precise 1930 } 1931 } 1932 } 1933 1934 // Check for loading klass from an array klass 1935 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1936 if (tkls != NULL && !StressReflectiveCode) { 1937 ciKlass* klass = tkls->klass(); 1938 if( !klass->is_loaded() ) 1939 return _type; // Bail out if not loaded 1940 if( klass->is_obj_array_klass() && 1941 tkls->offset() == in_bytes(objArrayKlass::element_klass_offset())) { 1942 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 1943 // // Always returning precise element type is incorrect, 1944 // // e.g., element type could be object and array may contain strings 1945 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 1946 1947 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 1948 // according to the element type's subclassing. 1949 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 1950 } 1951 if( klass->is_instance_klass() && tkls->klass_is_exact() && 1952 tkls->offset() == in_bytes(Klass::super_offset())) { 1953 ciKlass* sup = klass->as_instance_klass()->super(); 1954 // The field is Klass::_super. Return its (constant) value. 1955 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 1956 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 1957 } 1958 } 1959 1960 // Bailout case 1961 return LoadNode::Value(phase); 1962 } 1963 1964 //------------------------------Identity--------------------------------------- 1965 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 1966 // Also feed through the klass in Allocate(...klass...)._klass. 1967 Node* LoadKlassNode::Identity( PhaseTransform *phase ) { 1968 return klass_identity_common(phase); 1969 } 1970 1971 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) { 1972 Node* x = LoadNode::Identity(phase); 1973 if (x != this) return x; 1974 1975 // Take apart the address into an oop and and offset. 1976 // Return 'this' if we cannot. 1977 Node* adr = in(MemNode::Address); 1978 intptr_t offset = 0; 1979 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 1980 if (base == NULL) return this; 1981 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 1982 if (toop == NULL) return this; 1983 1984 // We can fetch the klass directly through an AllocateNode. 1985 // This works even if the klass is not constant (clone or newArray). 1986 if (offset == oopDesc::klass_offset_in_bytes()) { 1987 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 1988 if (allocated_klass != NULL) { 1989 return allocated_klass; 1990 } 1991 } 1992 1993 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop. 1994 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass. 1995 // See inline_native_Class_query for occurrences of these patterns. 1996 // Java Example: x.getClass().isAssignableFrom(y) 1997 // Java Example: Array.newInstance(x.getClass().getComponentType(), n) 1998 // 1999 // This improves reflective code, often making the Class 2000 // mirror go completely dead. (Current exception: Class 2001 // mirrors may appear in debug info, but we could clean them out by 2002 // introducing a new debug info operator for klassOop.java_mirror). 2003 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2004 && (offset == java_lang_Class::klass_offset_in_bytes() || 2005 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2006 // We are loading a special hidden field from a Class mirror, 2007 // the field which points to its Klass or arrayKlass metaobject. 2008 if (base->is_Load()) { 2009 Node* adr2 = base->in(MemNode::Address); 2010 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2011 if (tkls != NULL && !tkls->empty() 2012 && (tkls->klass()->is_instance_klass() || 2013 tkls->klass()->is_array_klass()) 2014 && adr2->is_AddP() 2015 ) { 2016 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2017 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2018 mirror_field = in_bytes(arrayKlass::component_mirror_offset()); 2019 } 2020 if (tkls->offset() == mirror_field) { 2021 return adr2->in(AddPNode::Base); 2022 } 2023 } 2024 } 2025 } 2026 2027 return this; 2028 } 2029 2030 2031 //------------------------------Value------------------------------------------ 2032 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const { 2033 const Type *t = klass_value_common(phase); 2034 if (t == Type::TOP) 2035 return t; 2036 2037 return t->make_narrowoop(); 2038 } 2039 2040 //------------------------------Identity--------------------------------------- 2041 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2042 // Also feed through the klass in Allocate(...klass...)._klass. 2043 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) { 2044 Node *x = klass_identity_common(phase); 2045 2046 const Type *t = phase->type( x ); 2047 if( t == Type::TOP ) return x; 2048 if( t->isa_narrowoop()) return x; 2049 2050 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop())); 2051 } 2052 2053 //------------------------------Value----------------------------------------- 2054 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { 2055 // Either input is TOP ==> the result is TOP 2056 const Type *t1 = phase->type( in(MemNode::Memory) ); 2057 if( t1 == Type::TOP ) return Type::TOP; 2058 Node *adr = in(MemNode::Address); 2059 const Type *t2 = phase->type( adr ); 2060 if( t2 == Type::TOP ) return Type::TOP; 2061 const TypePtr *tp = t2->is_ptr(); 2062 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2063 const TypeAryPtr *tap = tp->isa_aryptr(); 2064 if( !tap ) return _type; 2065 return tap->size(); 2066 } 2067 2068 //-------------------------------Ideal--------------------------------------- 2069 // Feed through the length in AllocateArray(...length...)._length. 2070 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2071 Node* p = MemNode::Ideal_common(phase, can_reshape); 2072 if (p) return (p == NodeSentinel) ? NULL : p; 2073 2074 // Take apart the address into an oop and and offset. 2075 // Return 'this' if we cannot. 2076 Node* adr = in(MemNode::Address); 2077 intptr_t offset = 0; 2078 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2079 if (base == NULL) return NULL; 2080 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2081 if (tary == NULL) return NULL; 2082 2083 // We can fetch the length directly through an AllocateArrayNode. 2084 // This works even if the length is not constant (clone or newArray). 2085 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2086 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2087 if (alloc != NULL) { 2088 Node* allocated_length = alloc->Ideal_length(); 2089 Node* len = alloc->make_ideal_length(tary, phase); 2090 if (allocated_length != len) { 2091 // New CastII improves on this. 2092 return len; 2093 } 2094 } 2095 } 2096 2097 return NULL; 2098 } 2099 2100 //------------------------------Identity--------------------------------------- 2101 // Feed through the length in AllocateArray(...length...)._length. 2102 Node* LoadRangeNode::Identity( PhaseTransform *phase ) { 2103 Node* x = LoadINode::Identity(phase); 2104 if (x != this) return x; 2105 2106 // Take apart the address into an oop and and offset. 2107 // Return 'this' if we cannot. 2108 Node* adr = in(MemNode::Address); 2109 intptr_t offset = 0; 2110 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2111 if (base == NULL) return this; 2112 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2113 if (tary == NULL) return this; 2114 2115 // We can fetch the length directly through an AllocateArrayNode. 2116 // This works even if the length is not constant (clone or newArray). 2117 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2118 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2119 if (alloc != NULL) { 2120 Node* allocated_length = alloc->Ideal_length(); 2121 // Do not allow make_ideal_length to allocate a CastII node. 2122 Node* len = alloc->make_ideal_length(tary, phase, false); 2123 if (allocated_length == len) { 2124 // Return allocated_length only if it would not be improved by a CastII. 2125 return allocated_length; 2126 } 2127 } 2128 } 2129 2130 return this; 2131 2132 } 2133 2134 //============================================================================= 2135 //---------------------------StoreNode::make----------------------------------- 2136 // Polymorphic factory method: 2137 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) { 2138 Compile* C = gvn.C; 2139 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2140 ctl != NULL, "raw memory operations should have control edge"); 2141 2142 switch (bt) { 2143 case T_BOOLEAN: 2144 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val); 2145 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val); 2146 case T_CHAR: 2147 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val); 2148 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val); 2149 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val); 2150 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val); 2151 case T_ADDRESS: 2152 case T_OBJECT: 2153 #ifdef _LP64 2154 if (adr->bottom_type()->is_ptr_to_narrowoop() || 2155 (UseCompressedOops && val->bottom_type()->isa_klassptr() && 2156 adr->bottom_type()->isa_rawptr())) { 2157 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop())); 2158 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val); 2159 } else 2160 #endif 2161 { 2162 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val); 2163 } 2164 } 2165 ShouldNotReachHere(); 2166 return (StoreNode*)NULL; 2167 } 2168 2169 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) { 2170 bool require_atomic = true; 2171 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic); 2172 } 2173 2174 2175 //--------------------------bottom_type---------------------------------------- 2176 const Type *StoreNode::bottom_type() const { 2177 return Type::MEMORY; 2178 } 2179 2180 //------------------------------hash------------------------------------------- 2181 uint StoreNode::hash() const { 2182 // unroll addition of interesting fields 2183 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2184 2185 // Since they are not commoned, do not hash them: 2186 return NO_HASH; 2187 } 2188 2189 //------------------------------Ideal------------------------------------------ 2190 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2191 // When a store immediately follows a relevant allocation/initialization, 2192 // try to capture it into the initialization, or hoist it above. 2193 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2194 Node* p = MemNode::Ideal_common(phase, can_reshape); 2195 if (p) return (p == NodeSentinel) ? NULL : p; 2196 2197 Node* mem = in(MemNode::Memory); 2198 Node* address = in(MemNode::Address); 2199 2200 // Back-to-back stores to same address? Fold em up. Generally 2201 // unsafe if I have intervening uses... Also disallowed for StoreCM 2202 // since they must follow each StoreP operation. Redundant StoreCMs 2203 // are eliminated just before matching in final_graph_reshape. 2204 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address) && 2205 mem->Opcode() != Op_StoreCM) { 2206 // Looking at a dead closed cycle of memory? 2207 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2208 2209 assert(Opcode() == mem->Opcode() || 2210 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, 2211 "no mismatched stores, except on raw memory"); 2212 2213 if (mem->outcnt() == 1 && // check for intervening uses 2214 mem->as_Store()->memory_size() <= this->memory_size()) { 2215 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. 2216 // For example, 'mem' might be the final state at a conditional return. 2217 // Or, 'mem' might be used by some node which is live at the same time 2218 // 'this' is live, which might be unschedulable. So, require exactly 2219 // ONE user, the 'this' store, until such time as we clone 'mem' for 2220 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). 2221 if (can_reshape) { // (%%% is this an anachronism?) 2222 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), 2223 phase->is_IterGVN()); 2224 } else { 2225 // It's OK to do this in the parser, since DU info is always accurate, 2226 // and the parser always refers to nodes via SafePointNode maps. 2227 set_req(MemNode::Memory, mem->in(MemNode::Memory)); 2228 } 2229 return this; 2230 } 2231 } 2232 2233 // Capture an unaliased, unconditional, simple store into an initializer. 2234 // Or, if it is independent of the allocation, hoist it above the allocation. 2235 if (ReduceFieldZeroing && /*can_reshape &&*/ 2236 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2237 InitializeNode* init = mem->in(0)->as_Initialize(); 2238 intptr_t offset = init->can_capture_store(this, phase); 2239 if (offset > 0) { 2240 Node* moved = init->capture_store(this, offset, phase); 2241 // If the InitializeNode captured me, it made a raw copy of me, 2242 // and I need to disappear. 2243 if (moved != NULL) { 2244 // %%% hack to ensure that Ideal returns a new node: 2245 mem = MergeMemNode::make(phase->C, mem); 2246 return mem; // fold me away 2247 } 2248 } 2249 } 2250 2251 return NULL; // No further progress 2252 } 2253 2254 //------------------------------Value----------------------------------------- 2255 const Type *StoreNode::Value( PhaseTransform *phase ) const { 2256 // Either input is TOP ==> the result is TOP 2257 const Type *t1 = phase->type( in(MemNode::Memory) ); 2258 if( t1 == Type::TOP ) return Type::TOP; 2259 const Type *t2 = phase->type( in(MemNode::Address) ); 2260 if( t2 == Type::TOP ) return Type::TOP; 2261 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2262 if( t3 == Type::TOP ) return Type::TOP; 2263 return Type::MEMORY; 2264 } 2265 2266 //------------------------------Identity--------------------------------------- 2267 // Remove redundant stores: 2268 // Store(m, p, Load(m, p)) changes to m. 2269 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2270 Node *StoreNode::Identity( PhaseTransform *phase ) { 2271 Node* mem = in(MemNode::Memory); 2272 Node* adr = in(MemNode::Address); 2273 Node* val = in(MemNode::ValueIn); 2274 2275 // Load then Store? Then the Store is useless 2276 if (val->is_Load() && 2277 phase->eqv_uncast( val->in(MemNode::Address), adr ) && 2278 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) && 2279 val->as_Load()->store_Opcode() == Opcode()) { 2280 return mem; 2281 } 2282 2283 // Two stores in a row of the same value? 2284 if (mem->is_Store() && 2285 phase->eqv_uncast( mem->in(MemNode::Address), adr ) && 2286 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) && 2287 mem->Opcode() == Opcode()) { 2288 return mem; 2289 } 2290 2291 // Store of zero anywhere into a freshly-allocated object? 2292 // Then the store is useless. 2293 // (It must already have been captured by the InitializeNode.) 2294 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2295 // a newly allocated object is already all-zeroes everywhere 2296 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2297 return mem; 2298 } 2299 2300 // the store may also apply to zero-bits in an earlier object 2301 Node* prev_mem = find_previous_store(phase); 2302 // Steps (a), (b): Walk past independent stores to find an exact match. 2303 if (prev_mem != NULL) { 2304 Node* prev_val = can_see_stored_value(prev_mem, phase); 2305 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2306 // prev_val and val might differ by a cast; it would be good 2307 // to keep the more informative of the two. 2308 return mem; 2309 } 2310 } 2311 } 2312 2313 return this; 2314 } 2315 2316 //------------------------------match_edge------------------------------------- 2317 // Do we Match on this edge index or not? Match only memory & value 2318 uint StoreNode::match_edge(uint idx) const { 2319 return idx == MemNode::Address || idx == MemNode::ValueIn; 2320 } 2321 2322 //------------------------------cmp-------------------------------------------- 2323 // Do not common stores up together. They generally have to be split 2324 // back up anyways, so do not bother. 2325 uint StoreNode::cmp( const Node &n ) const { 2326 return (&n == this); // Always fail except on self 2327 } 2328 2329 //------------------------------Ideal_masked_input----------------------------- 2330 // Check for a useless mask before a partial-word store 2331 // (StoreB ... (AndI valIn conIa) ) 2332 // If (conIa & mask == mask) this simplifies to 2333 // (StoreB ... (valIn) ) 2334 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2335 Node *val = in(MemNode::ValueIn); 2336 if( val->Opcode() == Op_AndI ) { 2337 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2338 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2339 set_req(MemNode::ValueIn, val->in(1)); 2340 return this; 2341 } 2342 } 2343 return NULL; 2344 } 2345 2346 2347 //------------------------------Ideal_sign_extended_input---------------------- 2348 // Check for useless sign-extension before a partial-word store 2349 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2350 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2351 // (StoreB ... (valIn) ) 2352 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2353 Node *val = in(MemNode::ValueIn); 2354 if( val->Opcode() == Op_RShiftI ) { 2355 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2356 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2357 Node *shl = val->in(1); 2358 if( shl->Opcode() == Op_LShiftI ) { 2359 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2360 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2361 set_req(MemNode::ValueIn, shl->in(1)); 2362 return this; 2363 } 2364 } 2365 } 2366 } 2367 return NULL; 2368 } 2369 2370 //------------------------------value_never_loaded----------------------------------- 2371 // Determine whether there are any possible loads of the value stored. 2372 // For simplicity, we actually check if there are any loads from the 2373 // address stored to, not just for loads of the value stored by this node. 2374 // 2375 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2376 Node *adr = in(Address); 2377 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2378 if (adr_oop == NULL) 2379 return false; 2380 if (!adr_oop->is_known_instance_field()) 2381 return false; // if not a distinct instance, there may be aliases of the address 2382 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2383 Node *use = adr->fast_out(i); 2384 int opc = use->Opcode(); 2385 if (use->is_Load() || use->is_LoadStore()) { 2386 return false; 2387 } 2388 } 2389 return true; 2390 } 2391 2392 //============================================================================= 2393 //------------------------------Ideal------------------------------------------ 2394 // If the store is from an AND mask that leaves the low bits untouched, then 2395 // we can skip the AND operation. If the store is from a sign-extension 2396 // (a left shift, then right shift) we can skip both. 2397 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2398 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2399 if( progress != NULL ) return progress; 2400 2401 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2402 if( progress != NULL ) return progress; 2403 2404 // Finally check the default case 2405 return StoreNode::Ideal(phase, can_reshape); 2406 } 2407 2408 //============================================================================= 2409 //------------------------------Ideal------------------------------------------ 2410 // If the store is from an AND mask that leaves the low bits untouched, then 2411 // we can skip the AND operation 2412 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2413 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2414 if( progress != NULL ) return progress; 2415 2416 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2417 if( progress != NULL ) return progress; 2418 2419 // Finally check the default case 2420 return StoreNode::Ideal(phase, can_reshape); 2421 } 2422 2423 //============================================================================= 2424 //------------------------------Identity--------------------------------------- 2425 Node *StoreCMNode::Identity( PhaseTransform *phase ) { 2426 // No need to card mark when storing a null ptr 2427 Node* my_store = in(MemNode::OopStore); 2428 if (my_store->is_Store()) { 2429 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2430 if( t1 == TypePtr::NULL_PTR ) { 2431 return in(MemNode::Memory); 2432 } 2433 } 2434 return this; 2435 } 2436 2437 //============================================================================= 2438 //------------------------------Ideal--------------------------------------- 2439 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2440 Node* progress = StoreNode::Ideal(phase, can_reshape); 2441 if (progress != NULL) return progress; 2442 2443 Node* my_store = in(MemNode::OopStore); 2444 if (my_store->is_MergeMem()) { 2445 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2446 set_req(MemNode::OopStore, mem); 2447 return this; 2448 } 2449 2450 return NULL; 2451 } 2452 2453 //------------------------------Value----------------------------------------- 2454 const Type *StoreCMNode::Value( PhaseTransform *phase ) const { 2455 // Either input is TOP ==> the result is TOP 2456 const Type *t = phase->type( in(MemNode::Memory) ); 2457 if( t == Type::TOP ) return Type::TOP; 2458 t = phase->type( in(MemNode::Address) ); 2459 if( t == Type::TOP ) return Type::TOP; 2460 t = phase->type( in(MemNode::ValueIn) ); 2461 if( t == Type::TOP ) return Type::TOP; 2462 // If extra input is TOP ==> the result is TOP 2463 t = phase->type( in(MemNode::OopStore) ); 2464 if( t == Type::TOP ) return Type::TOP; 2465 2466 return StoreNode::Value( phase ); 2467 } 2468 2469 2470 //============================================================================= 2471 //----------------------------------SCMemProjNode------------------------------ 2472 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const 2473 { 2474 return bottom_type(); 2475 } 2476 2477 //============================================================================= 2478 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) { 2479 init_req(MemNode::Control, c ); 2480 init_req(MemNode::Memory , mem); 2481 init_req(MemNode::Address, adr); 2482 init_req(MemNode::ValueIn, val); 2483 init_req( ExpectedIn, ex ); 2484 init_class_id(Class_LoadStore); 2485 2486 } 2487 2488 //============================================================================= 2489 //-------------------------------adr_type-------------------------------------- 2490 // Do we Match on this edge index or not? Do not match memory 2491 const TypePtr* ClearArrayNode::adr_type() const { 2492 Node *adr = in(3); 2493 return MemNode::calculate_adr_type(adr->bottom_type()); 2494 } 2495 2496 //------------------------------match_edge------------------------------------- 2497 // Do we Match on this edge index or not? Do not match memory 2498 uint ClearArrayNode::match_edge(uint idx) const { 2499 return idx > 1; 2500 } 2501 2502 //------------------------------Identity--------------------------------------- 2503 // Clearing a zero length array does nothing 2504 Node *ClearArrayNode::Identity( PhaseTransform *phase ) { 2505 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2506 } 2507 2508 //------------------------------Idealize--------------------------------------- 2509 // Clearing a short array is faster with stores 2510 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2511 const int unit = BytesPerLong; 2512 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2513 if (!t) return NULL; 2514 if (!t->is_con()) return NULL; 2515 intptr_t raw_count = t->get_con(); 2516 intptr_t size = raw_count; 2517 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2518 // Clearing nothing uses the Identity call. 2519 // Negative clears are possible on dead ClearArrays 2520 // (see jck test stmt114.stmt11402.val). 2521 if (size <= 0 || size % unit != 0) return NULL; 2522 intptr_t count = size / unit; 2523 // Length too long; use fast hardware clear 2524 if (size > Matcher::init_array_short_size) return NULL; 2525 Node *mem = in(1); 2526 if( phase->type(mem)==Type::TOP ) return NULL; 2527 Node *adr = in(3); 2528 const Type* at = phase->type(adr); 2529 if( at==Type::TOP ) return NULL; 2530 const TypePtr* atp = at->isa_ptr(); 2531 // adjust atp to be the correct array element address type 2532 if (atp == NULL) atp = TypePtr::BOTTOM; 2533 else atp = atp->add_offset(Type::OffsetBot); 2534 // Get base for derived pointer purposes 2535 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2536 Node *base = adr->in(1); 2537 2538 Node *zero = phase->makecon(TypeLong::ZERO); 2539 Node *off = phase->MakeConX(BytesPerLong); 2540 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2541 count--; 2542 while( count-- ) { 2543 mem = phase->transform(mem); 2544 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off)); 2545 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2546 } 2547 return mem; 2548 } 2549 2550 //----------------------------step_through---------------------------------- 2551 // Return allocation input memory edge if it is different instance 2552 // or itself if it is the one we are looking for. 2553 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2554 Node* n = *np; 2555 assert(n->is_ClearArray(), "sanity"); 2556 intptr_t offset; 2557 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2558 // This method is called only before Allocate nodes are expanded during 2559 // macro nodes expansion. Before that ClearArray nodes are only generated 2560 // in LibraryCallKit::generate_arraycopy() which follows allocations. 2561 assert(alloc != NULL, "should have allocation"); 2562 if (alloc->_idx == instance_id) { 2563 // Can not bypass initialization of the instance we are looking for. 2564 return false; 2565 } 2566 // Otherwise skip it. 2567 InitializeNode* init = alloc->initialization(); 2568 if (init != NULL) 2569 *np = init->in(TypeFunc::Memory); 2570 else 2571 *np = alloc->in(TypeFunc::Memory); 2572 return true; 2573 } 2574 2575 //----------------------------clear_memory------------------------------------- 2576 // Generate code to initialize object storage to zero. 2577 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2578 intptr_t start_offset, 2579 Node* end_offset, 2580 PhaseGVN* phase) { 2581 Compile* C = phase->C; 2582 intptr_t offset = start_offset; 2583 2584 int unit = BytesPerLong; 2585 if ((offset % unit) != 0) { 2586 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset)); 2587 adr = phase->transform(adr); 2588 const TypePtr* atp = TypeRawPtr::BOTTOM; 2589 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2590 mem = phase->transform(mem); 2591 offset += BytesPerInt; 2592 } 2593 assert((offset % unit) == 0, ""); 2594 2595 // Initialize the remaining stuff, if any, with a ClearArray. 2596 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2597 } 2598 2599 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2600 Node* start_offset, 2601 Node* end_offset, 2602 PhaseGVN* phase) { 2603 if (start_offset == end_offset) { 2604 // nothing to do 2605 return mem; 2606 } 2607 2608 Compile* C = phase->C; 2609 int unit = BytesPerLong; 2610 Node* zbase = start_offset; 2611 Node* zend = end_offset; 2612 2613 // Scale to the unit required by the CPU: 2614 if (!Matcher::init_array_count_is_in_bytes) { 2615 Node* shift = phase->intcon(exact_log2(unit)); 2616 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) ); 2617 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) ); 2618 } 2619 2620 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) ); 2621 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT); 2622 2623 // Bulk clear double-words 2624 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) ); 2625 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr); 2626 return phase->transform(mem); 2627 } 2628 2629 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2630 intptr_t start_offset, 2631 intptr_t end_offset, 2632 PhaseGVN* phase) { 2633 if (start_offset == end_offset) { 2634 // nothing to do 2635 return mem; 2636 } 2637 2638 Compile* C = phase->C; 2639 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2640 intptr_t done_offset = end_offset; 2641 if ((done_offset % BytesPerLong) != 0) { 2642 done_offset -= BytesPerInt; 2643 } 2644 if (done_offset > start_offset) { 2645 mem = clear_memory(ctl, mem, dest, 2646 start_offset, phase->MakeConX(done_offset), phase); 2647 } 2648 if (done_offset < end_offset) { // emit the final 32-bit store 2649 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset)); 2650 adr = phase->transform(adr); 2651 const TypePtr* atp = TypeRawPtr::BOTTOM; 2652 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2653 mem = phase->transform(mem); 2654 done_offset += BytesPerInt; 2655 } 2656 assert(done_offset == end_offset, ""); 2657 return mem; 2658 } 2659 2660 //============================================================================= 2661 // Do not match memory edge. 2662 uint StrIntrinsicNode::match_edge(uint idx) const { 2663 return idx == 2 || idx == 3; 2664 } 2665 2666 //------------------------------Ideal------------------------------------------ 2667 // Return a node which is more "ideal" than the current node. Strip out 2668 // control copies 2669 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2670 if (remove_dead_region(phase, can_reshape)) return this; 2671 // Don't bother trying to transform a dead node 2672 if (in(0) && in(0)->is_top()) return NULL; 2673 2674 if (can_reshape) { 2675 Node* mem = phase->transform(in(MemNode::Memory)); 2676 // If transformed to a MergeMem, get the desired slice 2677 uint alias_idx = phase->C->get_alias_index(adr_type()); 2678 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem; 2679 if (mem != in(MemNode::Memory)) { 2680 set_req(MemNode::Memory, mem); 2681 return this; 2682 } 2683 } 2684 return NULL; 2685 } 2686 2687 //------------------------------Value------------------------------------------ 2688 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const { 2689 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP; 2690 return bottom_type(); 2691 } 2692 2693 //============================================================================= 2694 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2695 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2696 _adr_type(C->get_adr_type(alias_idx)) 2697 { 2698 init_class_id(Class_MemBar); 2699 Node* top = C->top(); 2700 init_req(TypeFunc::I_O,top); 2701 init_req(TypeFunc::FramePtr,top); 2702 init_req(TypeFunc::ReturnAdr,top); 2703 if (precedent != NULL) 2704 init_req(TypeFunc::Parms, precedent); 2705 } 2706 2707 //------------------------------cmp-------------------------------------------- 2708 uint MemBarNode::hash() const { return NO_HASH; } 2709 uint MemBarNode::cmp( const Node &n ) const { 2710 return (&n == this); // Always fail except on self 2711 } 2712 2713 //------------------------------make------------------------------------------- 2714 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2715 int len = Precedent + (pn == NULL? 0: 1); 2716 switch (opcode) { 2717 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn); 2718 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn); 2719 case Op_MemBarAcquireLock: return new(C, len) MemBarAcquireLockNode(C, atp, pn); 2720 case Op_MemBarReleaseLock: return new(C, len) MemBarReleaseLockNode(C, atp, pn); 2721 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn); 2722 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn); 2723 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn); 2724 default: ShouldNotReachHere(); return NULL; 2725 } 2726 } 2727 2728 //------------------------------Ideal------------------------------------------ 2729 // Return a node which is more "ideal" than the current node. Strip out 2730 // control copies 2731 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2732 if (remove_dead_region(phase, can_reshape)) return this; 2733 // Don't bother trying to transform a dead node 2734 if (in(0) && in(0)->is_top()) return NULL; 2735 2736 // Eliminate volatile MemBars for scalar replaced objects. 2737 if (can_reshape && req() == (Precedent+1) && 2738 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) { 2739 // Volatile field loads and stores. 2740 Node* my_mem = in(MemBarNode::Precedent); 2741 if (my_mem != NULL && my_mem->is_Mem()) { 2742 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 2743 // Check for scalar replaced object reference. 2744 if( t_oop != NULL && t_oop->is_known_instance_field() && 2745 t_oop->offset() != Type::OffsetBot && 2746 t_oop->offset() != Type::OffsetTop) { 2747 // Replace MemBar projections by its inputs. 2748 PhaseIterGVN* igvn = phase->is_IterGVN(); 2749 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 2750 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 2751 // Must return either the original node (now dead) or a new node 2752 // (Do not return a top here, since that would break the uniqueness of top.) 2753 return new (phase->C, 1) ConINode(TypeInt::ZERO); 2754 } 2755 } 2756 } 2757 return NULL; 2758 } 2759 2760 //------------------------------Value------------------------------------------ 2761 const Type *MemBarNode::Value( PhaseTransform *phase ) const { 2762 if( !in(0) ) return Type::TOP; 2763 if( phase->type(in(0)) == Type::TOP ) 2764 return Type::TOP; 2765 return TypeTuple::MEMBAR; 2766 } 2767 2768 //------------------------------match------------------------------------------ 2769 // Construct projections for memory. 2770 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 2771 switch (proj->_con) { 2772 case TypeFunc::Control: 2773 case TypeFunc::Memory: 2774 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 2775 } 2776 ShouldNotReachHere(); 2777 return NULL; 2778 } 2779 2780 //===========================InitializeNode==================================== 2781 // SUMMARY: 2782 // This node acts as a memory barrier on raw memory, after some raw stores. 2783 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 2784 // The Initialize can 'capture' suitably constrained stores as raw inits. 2785 // It can coalesce related raw stores into larger units (called 'tiles'). 2786 // It can avoid zeroing new storage for memory units which have raw inits. 2787 // At macro-expansion, it is marked 'complete', and does not optimize further. 2788 // 2789 // EXAMPLE: 2790 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 2791 // ctl = incoming control; mem* = incoming memory 2792 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 2793 // First allocate uninitialized memory and fill in the header: 2794 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 2795 // ctl := alloc.Control; mem* := alloc.Memory* 2796 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 2797 // Then initialize to zero the non-header parts of the raw memory block: 2798 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 2799 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 2800 // After the initialize node executes, the object is ready for service: 2801 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 2802 // Suppose its body is immediately initialized as {1,2}: 2803 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 2804 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 2805 // mem.SLICE(#short[*]) := store2 2806 // 2807 // DETAILS: 2808 // An InitializeNode collects and isolates object initialization after 2809 // an AllocateNode and before the next possible safepoint. As a 2810 // memory barrier (MemBarNode), it keeps critical stores from drifting 2811 // down past any safepoint or any publication of the allocation. 2812 // Before this barrier, a newly-allocated object may have uninitialized bits. 2813 // After this barrier, it may be treated as a real oop, and GC is allowed. 2814 // 2815 // The semantics of the InitializeNode include an implicit zeroing of 2816 // the new object from object header to the end of the object. 2817 // (The object header and end are determined by the AllocateNode.) 2818 // 2819 // Certain stores may be added as direct inputs to the InitializeNode. 2820 // These stores must update raw memory, and they must be to addresses 2821 // derived from the raw address produced by AllocateNode, and with 2822 // a constant offset. They must be ordered by increasing offset. 2823 // The first one is at in(RawStores), the last at in(req()-1). 2824 // Unlike most memory operations, they are not linked in a chain, 2825 // but are displayed in parallel as users of the rawmem output of 2826 // the allocation. 2827 // 2828 // (See comments in InitializeNode::capture_store, which continue 2829 // the example given above.) 2830 // 2831 // When the associated Allocate is macro-expanded, the InitializeNode 2832 // may be rewritten to optimize collected stores. A ClearArrayNode 2833 // may also be created at that point to represent any required zeroing. 2834 // The InitializeNode is then marked 'complete', prohibiting further 2835 // capturing of nearby memory operations. 2836 // 2837 // During macro-expansion, all captured initializations which store 2838 // constant values of 32 bits or smaller are coalesced (if advantageous) 2839 // into larger 'tiles' 32 or 64 bits. This allows an object to be 2840 // initialized in fewer memory operations. Memory words which are 2841 // covered by neither tiles nor non-constant stores are pre-zeroed 2842 // by explicit stores of zero. (The code shape happens to do all 2843 // zeroing first, then all other stores, with both sequences occurring 2844 // in order of ascending offsets.) 2845 // 2846 // Alternatively, code may be inserted between an AllocateNode and its 2847 // InitializeNode, to perform arbitrary initialization of the new object. 2848 // E.g., the object copying intrinsics insert complex data transfers here. 2849 // The initialization must then be marked as 'complete' disable the 2850 // built-in zeroing semantics and the collection of initializing stores. 2851 // 2852 // While an InitializeNode is incomplete, reads from the memory state 2853 // produced by it are optimizable if they match the control edge and 2854 // new oop address associated with the allocation/initialization. 2855 // They return a stored value (if the offset matches) or else zero. 2856 // A write to the memory state, if it matches control and address, 2857 // and if it is to a constant offset, may be 'captured' by the 2858 // InitializeNode. It is cloned as a raw memory operation and rewired 2859 // inside the initialization, to the raw oop produced by the allocation. 2860 // Operations on addresses which are provably distinct (e.g., to 2861 // other AllocateNodes) are allowed to bypass the initialization. 2862 // 2863 // The effect of all this is to consolidate object initialization 2864 // (both arrays and non-arrays, both piecewise and bulk) into a 2865 // single location, where it can be optimized as a unit. 2866 // 2867 // Only stores with an offset less than TrackedInitializationLimit words 2868 // will be considered for capture by an InitializeNode. This puts a 2869 // reasonable limit on the complexity of optimized initializations. 2870 2871 //---------------------------InitializeNode------------------------------------ 2872 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 2873 : _is_complete(Incomplete), 2874 MemBarNode(C, adr_type, rawoop) 2875 { 2876 init_class_id(Class_Initialize); 2877 2878 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 2879 assert(in(RawAddress) == rawoop, "proper init"); 2880 // Note: allocation() can be NULL, for secondary initialization barriers 2881 } 2882 2883 // Since this node is not matched, it will be processed by the 2884 // register allocator. Declare that there are no constraints 2885 // on the allocation of the RawAddress edge. 2886 const RegMask &InitializeNode::in_RegMask(uint idx) const { 2887 // This edge should be set to top, by the set_complete. But be conservative. 2888 if (idx == InitializeNode::RawAddress) 2889 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 2890 return RegMask::Empty; 2891 } 2892 2893 Node* InitializeNode::memory(uint alias_idx) { 2894 Node* mem = in(Memory); 2895 if (mem->is_MergeMem()) { 2896 return mem->as_MergeMem()->memory_at(alias_idx); 2897 } else { 2898 // incoming raw memory is not split 2899 return mem; 2900 } 2901 } 2902 2903 bool InitializeNode::is_non_zero() { 2904 if (is_complete()) return false; 2905 remove_extra_zeroes(); 2906 return (req() > RawStores); 2907 } 2908 2909 void InitializeNode::set_complete(PhaseGVN* phase) { 2910 assert(!is_complete(), "caller responsibility"); 2911 _is_complete = Complete; 2912 2913 // After this node is complete, it contains a bunch of 2914 // raw-memory initializations. There is no need for 2915 // it to have anything to do with non-raw memory effects. 2916 // Therefore, tell all non-raw users to re-optimize themselves, 2917 // after skipping the memory effects of this initialization. 2918 PhaseIterGVN* igvn = phase->is_IterGVN(); 2919 if (igvn) igvn->add_users_to_worklist(this); 2920 } 2921 2922 // convenience function 2923 // return false if the init contains any stores already 2924 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 2925 InitializeNode* init = initialization(); 2926 if (init == NULL || init->is_complete()) return false; 2927 init->remove_extra_zeroes(); 2928 // for now, if this allocation has already collected any inits, bail: 2929 if (init->is_non_zero()) return false; 2930 init->set_complete(phase); 2931 return true; 2932 } 2933 2934 void InitializeNode::remove_extra_zeroes() { 2935 if (req() == RawStores) return; 2936 Node* zmem = zero_memory(); 2937 uint fill = RawStores; 2938 for (uint i = fill; i < req(); i++) { 2939 Node* n = in(i); 2940 if (n->is_top() || n == zmem) continue; // skip 2941 if (fill < i) set_req(fill, n); // compact 2942 ++fill; 2943 } 2944 // delete any empty spaces created: 2945 while (fill < req()) { 2946 del_req(fill); 2947 } 2948 } 2949 2950 // Helper for remembering which stores go with which offsets. 2951 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 2952 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 2953 intptr_t offset = -1; 2954 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 2955 phase, offset); 2956 if (base == NULL) return -1; // something is dead, 2957 if (offset < 0) return -1; // dead, dead 2958 return offset; 2959 } 2960 2961 // Helper for proving that an initialization expression is 2962 // "simple enough" to be folded into an object initialization. 2963 // Attempts to prove that a store's initial value 'n' can be captured 2964 // within the initialization without creating a vicious cycle, such as: 2965 // { Foo p = new Foo(); p.next = p; } 2966 // True for constants and parameters and small combinations thereof. 2967 bool InitializeNode::detect_init_independence(Node* n, 2968 bool st_is_pinned, 2969 int& count) { 2970 if (n == NULL) return true; // (can this really happen?) 2971 if (n->is_Proj()) n = n->in(0); 2972 if (n == this) return false; // found a cycle 2973 if (n->is_Con()) return true; 2974 if (n->is_Start()) return true; // params, etc., are OK 2975 if (n->is_Root()) return true; // even better 2976 2977 Node* ctl = n->in(0); 2978 if (ctl != NULL && !ctl->is_top()) { 2979 if (ctl->is_Proj()) ctl = ctl->in(0); 2980 if (ctl == this) return false; 2981 2982 // If we already know that the enclosing memory op is pinned right after 2983 // the init, then any control flow that the store has picked up 2984 // must have preceded the init, or else be equal to the init. 2985 // Even after loop optimizations (which might change control edges) 2986 // a store is never pinned *before* the availability of its inputs. 2987 if (!MemNode::all_controls_dominate(n, this)) 2988 return false; // failed to prove a good control 2989 2990 } 2991 2992 // Check data edges for possible dependencies on 'this'. 2993 if ((count += 1) > 20) return false; // complexity limit 2994 for (uint i = 1; i < n->req(); i++) { 2995 Node* m = n->in(i); 2996 if (m == NULL || m == n || m->is_top()) continue; 2997 uint first_i = n->find_edge(m); 2998 if (i != first_i) continue; // process duplicate edge just once 2999 if (!detect_init_independence(m, st_is_pinned, count)) { 3000 return false; 3001 } 3002 } 3003 3004 return true; 3005 } 3006 3007 // Here are all the checks a Store must pass before it can be moved into 3008 // an initialization. Returns zero if a check fails. 3009 // On success, returns the (constant) offset to which the store applies, 3010 // within the initialized memory. 3011 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) { 3012 const int FAIL = 0; 3013 if (st->req() != MemNode::ValueIn + 1) 3014 return FAIL; // an inscrutable StoreNode (card mark?) 3015 Node* ctl = st->in(MemNode::Control); 3016 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3017 return FAIL; // must be unconditional after the initialization 3018 Node* mem = st->in(MemNode::Memory); 3019 if (!(mem->is_Proj() && mem->in(0) == this)) 3020 return FAIL; // must not be preceded by other stores 3021 Node* adr = st->in(MemNode::Address); 3022 intptr_t offset; 3023 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3024 if (alloc == NULL) 3025 return FAIL; // inscrutable address 3026 if (alloc != allocation()) 3027 return FAIL; // wrong allocation! (store needs to float up) 3028 Node* val = st->in(MemNode::ValueIn); 3029 int complexity_count = 0; 3030 if (!detect_init_independence(val, true, complexity_count)) 3031 return FAIL; // stored value must be 'simple enough' 3032 3033 return offset; // success 3034 } 3035 3036 // Find the captured store in(i) which corresponds to the range 3037 // [start..start+size) in the initialized object. 3038 // If there is one, return its index i. If there isn't, return the 3039 // negative of the index where it should be inserted. 3040 // Return 0 if the queried range overlaps an initialization boundary 3041 // or if dead code is encountered. 3042 // If size_in_bytes is zero, do not bother with overlap checks. 3043 int InitializeNode::captured_store_insertion_point(intptr_t start, 3044 int size_in_bytes, 3045 PhaseTransform* phase) { 3046 const int FAIL = 0, MAX_STORE = BytesPerLong; 3047 3048 if (is_complete()) 3049 return FAIL; // arraycopy got here first; punt 3050 3051 assert(allocation() != NULL, "must be present"); 3052 3053 // no negatives, no header fields: 3054 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3055 3056 // after a certain size, we bail out on tracking all the stores: 3057 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3058 if (start >= ti_limit) return FAIL; 3059 3060 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3061 if (i >= limit) return -(int)i; // not found; here is where to put it 3062 3063 Node* st = in(i); 3064 intptr_t st_off = get_store_offset(st, phase); 3065 if (st_off < 0) { 3066 if (st != zero_memory()) { 3067 return FAIL; // bail out if there is dead garbage 3068 } 3069 } else if (st_off > start) { 3070 // ...we are done, since stores are ordered 3071 if (st_off < start + size_in_bytes) { 3072 return FAIL; // the next store overlaps 3073 } 3074 return -(int)i; // not found; here is where to put it 3075 } else if (st_off < start) { 3076 if (size_in_bytes != 0 && 3077 start < st_off + MAX_STORE && 3078 start < st_off + st->as_Store()->memory_size()) { 3079 return FAIL; // the previous store overlaps 3080 } 3081 } else { 3082 if (size_in_bytes != 0 && 3083 st->as_Store()->memory_size() != size_in_bytes) { 3084 return FAIL; // mismatched store size 3085 } 3086 return i; 3087 } 3088 3089 ++i; 3090 } 3091 } 3092 3093 // Look for a captured store which initializes at the offset 'start' 3094 // with the given size. If there is no such store, and no other 3095 // initialization interferes, then return zero_memory (the memory 3096 // projection of the AllocateNode). 3097 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3098 PhaseTransform* phase) { 3099 assert(stores_are_sane(phase), ""); 3100 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3101 if (i == 0) { 3102 return NULL; // something is dead 3103 } else if (i < 0) { 3104 return zero_memory(); // just primordial zero bits here 3105 } else { 3106 Node* st = in(i); // here is the store at this position 3107 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3108 return st; 3109 } 3110 } 3111 3112 // Create, as a raw pointer, an address within my new object at 'offset'. 3113 Node* InitializeNode::make_raw_address(intptr_t offset, 3114 PhaseTransform* phase) { 3115 Node* addr = in(RawAddress); 3116 if (offset != 0) { 3117 Compile* C = phase->C; 3118 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr, 3119 phase->MakeConX(offset)) ); 3120 } 3121 return addr; 3122 } 3123 3124 // Clone the given store, converting it into a raw store 3125 // initializing a field or element of my new object. 3126 // Caller is responsible for retiring the original store, 3127 // with subsume_node or the like. 3128 // 3129 // From the example above InitializeNode::InitializeNode, 3130 // here are the old stores to be captured: 3131 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3132 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3133 // 3134 // Here is the changed code; note the extra edges on init: 3135 // alloc = (Allocate ...) 3136 // rawoop = alloc.RawAddress 3137 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3138 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3139 // init = (Initialize alloc.Control alloc.Memory rawoop 3140 // rawstore1 rawstore2) 3141 // 3142 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3143 PhaseTransform* phase) { 3144 assert(stores_are_sane(phase), ""); 3145 3146 if (start < 0) return NULL; 3147 assert(can_capture_store(st, phase) == start, "sanity"); 3148 3149 Compile* C = phase->C; 3150 int size_in_bytes = st->memory_size(); 3151 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3152 if (i == 0) return NULL; // bail out 3153 Node* prev_mem = NULL; // raw memory for the captured store 3154 if (i > 0) { 3155 prev_mem = in(i); // there is a pre-existing store under this one 3156 set_req(i, C->top()); // temporarily disconnect it 3157 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3158 } else { 3159 i = -i; // no pre-existing store 3160 prev_mem = zero_memory(); // a slice of the newly allocated object 3161 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3162 set_req(--i, C->top()); // reuse this edge; it has been folded away 3163 else 3164 ins_req(i, C->top()); // build a new edge 3165 } 3166 Node* new_st = st->clone(); 3167 new_st->set_req(MemNode::Control, in(Control)); 3168 new_st->set_req(MemNode::Memory, prev_mem); 3169 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3170 new_st = phase->transform(new_st); 3171 3172 // At this point, new_st might have swallowed a pre-existing store 3173 // at the same offset, or perhaps new_st might have disappeared, 3174 // if it redundantly stored the same value (or zero to fresh memory). 3175 3176 // In any case, wire it in: 3177 set_req(i, new_st); 3178 3179 // The caller may now kill the old guy. 3180 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3181 assert(check_st == new_st || check_st == NULL, "must be findable"); 3182 assert(!is_complete(), ""); 3183 return new_st; 3184 } 3185 3186 static bool store_constant(jlong* tiles, int num_tiles, 3187 intptr_t st_off, int st_size, 3188 jlong con) { 3189 if ((st_off & (st_size-1)) != 0) 3190 return false; // strange store offset (assume size==2**N) 3191 address addr = (address)tiles + st_off; 3192 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3193 switch (st_size) { 3194 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3195 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3196 case sizeof(jint): *(jint*) addr = (jint) con; break; 3197 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3198 default: return false; // strange store size (detect size!=2**N here) 3199 } 3200 return true; // return success to caller 3201 } 3202 3203 // Coalesce subword constants into int constants and possibly 3204 // into long constants. The goal, if the CPU permits, 3205 // is to initialize the object with a small number of 64-bit tiles. 3206 // Also, convert floating-point constants to bit patterns. 3207 // Non-constants are not relevant to this pass. 3208 // 3209 // In terms of the running example on InitializeNode::InitializeNode 3210 // and InitializeNode::capture_store, here is the transformation 3211 // of rawstore1 and rawstore2 into rawstore12: 3212 // alloc = (Allocate ...) 3213 // rawoop = alloc.RawAddress 3214 // tile12 = 0x00010002 3215 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3216 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3217 // 3218 void 3219 InitializeNode::coalesce_subword_stores(intptr_t header_size, 3220 Node* size_in_bytes, 3221 PhaseGVN* phase) { 3222 Compile* C = phase->C; 3223 3224 assert(stores_are_sane(phase), ""); 3225 // Note: After this pass, they are not completely sane, 3226 // since there may be some overlaps. 3227 3228 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3229 3230 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3231 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3232 size_limit = MIN2(size_limit, ti_limit); 3233 size_limit = align_size_up(size_limit, BytesPerLong); 3234 int num_tiles = size_limit / BytesPerLong; 3235 3236 // allocate space for the tile map: 3237 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3238 jlong tiles_buf[small_len]; 3239 Node* nodes_buf[small_len]; 3240 jlong inits_buf[small_len]; 3241 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3242 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3243 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3244 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3245 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3246 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3247 // tiles: exact bitwise model of all primitive constants 3248 // nodes: last constant-storing node subsumed into the tiles model 3249 // inits: which bytes (in each tile) are touched by any initializations 3250 3251 //// Pass A: Fill in the tile model with any relevant stores. 3252 3253 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3254 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3255 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3256 Node* zmem = zero_memory(); // initially zero memory state 3257 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3258 Node* st = in(i); 3259 intptr_t st_off = get_store_offset(st, phase); 3260 3261 // Figure out the store's offset and constant value: 3262 if (st_off < header_size) continue; //skip (ignore header) 3263 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3264 int st_size = st->as_Store()->memory_size(); 3265 if (st_off + st_size > size_limit) break; 3266 3267 // Record which bytes are touched, whether by constant or not. 3268 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3269 continue; // skip (strange store size) 3270 3271 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3272 if (!val->singleton()) continue; //skip (non-con store) 3273 BasicType type = val->basic_type(); 3274 3275 jlong con = 0; 3276 switch (type) { 3277 case T_INT: con = val->is_int()->get_con(); break; 3278 case T_LONG: con = val->is_long()->get_con(); break; 3279 case T_FLOAT: con = jint_cast(val->getf()); break; 3280 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3281 default: continue; //skip (odd store type) 3282 } 3283 3284 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3285 st->Opcode() == Op_StoreL) { 3286 continue; // This StoreL is already optimal. 3287 } 3288 3289 // Store down the constant. 3290 store_constant(tiles, num_tiles, st_off, st_size, con); 3291 3292 intptr_t j = st_off >> LogBytesPerLong; 3293 3294 if (type == T_INT && st_size == BytesPerInt 3295 && (st_off & BytesPerInt) == BytesPerInt) { 3296 jlong lcon = tiles[j]; 3297 if (!Matcher::isSimpleConstant64(lcon) && 3298 st->Opcode() == Op_StoreI) { 3299 // This StoreI is already optimal by itself. 3300 jint* intcon = (jint*) &tiles[j]; 3301 intcon[1] = 0; // undo the store_constant() 3302 3303 // If the previous store is also optimal by itself, back up and 3304 // undo the action of the previous loop iteration... if we can. 3305 // But if we can't, just let the previous half take care of itself. 3306 st = nodes[j]; 3307 st_off -= BytesPerInt; 3308 con = intcon[0]; 3309 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3310 assert(st_off >= header_size, "still ignoring header"); 3311 assert(get_store_offset(st, phase) == st_off, "must be"); 3312 assert(in(i-1) == zmem, "must be"); 3313 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3314 assert(con == tcon->is_int()->get_con(), "must be"); 3315 // Undo the effects of the previous loop trip, which swallowed st: 3316 intcon[0] = 0; // undo store_constant() 3317 set_req(i-1, st); // undo set_req(i, zmem) 3318 nodes[j] = NULL; // undo nodes[j] = st 3319 --old_subword; // undo ++old_subword 3320 } 3321 continue; // This StoreI is already optimal. 3322 } 3323 } 3324 3325 // This store is not needed. 3326 set_req(i, zmem); 3327 nodes[j] = st; // record for the moment 3328 if (st_size < BytesPerLong) // something has changed 3329 ++old_subword; // includes int/float, but who's counting... 3330 else ++old_long; 3331 } 3332 3333 if ((old_subword + old_long) == 0) 3334 return; // nothing more to do 3335 3336 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3337 // Be sure to insert them before overlapping non-constant stores. 3338 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3339 for (int j = 0; j < num_tiles; j++) { 3340 jlong con = tiles[j]; 3341 jlong init = inits[j]; 3342 if (con == 0) continue; 3343 jint con0, con1; // split the constant, address-wise 3344 jint init0, init1; // split the init map, address-wise 3345 { union { jlong con; jint intcon[2]; } u; 3346 u.con = con; 3347 con0 = u.intcon[0]; 3348 con1 = u.intcon[1]; 3349 u.con = init; 3350 init0 = u.intcon[0]; 3351 init1 = u.intcon[1]; 3352 } 3353 3354 Node* old = nodes[j]; 3355 assert(old != NULL, "need the prior store"); 3356 intptr_t offset = (j * BytesPerLong); 3357 3358 bool split = !Matcher::isSimpleConstant64(con); 3359 3360 if (offset < header_size) { 3361 assert(offset + BytesPerInt >= header_size, "second int counts"); 3362 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3363 split = true; // only the second word counts 3364 // Example: int a[] = { 42 ... } 3365 } else if (con0 == 0 && init0 == -1) { 3366 split = true; // first word is covered by full inits 3367 // Example: int a[] = { ... foo(), 42 ... } 3368 } else if (con1 == 0 && init1 == -1) { 3369 split = true; // second word is covered by full inits 3370 // Example: int a[] = { ... 42, foo() ... } 3371 } 3372 3373 // Here's a case where init0 is neither 0 nor -1: 3374 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3375 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3376 // In this case the tile is not split; it is (jlong)42. 3377 // The big tile is stored down, and then the foo() value is inserted. 3378 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3379 3380 Node* ctl = old->in(MemNode::Control); 3381 Node* adr = make_raw_address(offset, phase); 3382 const TypePtr* atp = TypeRawPtr::BOTTOM; 3383 3384 // One or two coalesced stores to plop down. 3385 Node* st[2]; 3386 intptr_t off[2]; 3387 int nst = 0; 3388 if (!split) { 3389 ++new_long; 3390 off[nst] = offset; 3391 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3392 phase->longcon(con), T_LONG); 3393 } else { 3394 // Omit either if it is a zero. 3395 if (con0 != 0) { 3396 ++new_int; 3397 off[nst] = offset; 3398 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3399 phase->intcon(con0), T_INT); 3400 } 3401 if (con1 != 0) { 3402 ++new_int; 3403 offset += BytesPerInt; 3404 adr = make_raw_address(offset, phase); 3405 off[nst] = offset; 3406 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3407 phase->intcon(con1), T_INT); 3408 } 3409 } 3410 3411 // Insert second store first, then the first before the second. 3412 // Insert each one just before any overlapping non-constant stores. 3413 while (nst > 0) { 3414 Node* st1 = st[--nst]; 3415 C->copy_node_notes_to(st1, old); 3416 st1 = phase->transform(st1); 3417 offset = off[nst]; 3418 assert(offset >= header_size, "do not smash header"); 3419 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3420 guarantee(ins_idx != 0, "must re-insert constant store"); 3421 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3422 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3423 set_req(--ins_idx, st1); 3424 else 3425 ins_req(ins_idx, st1); 3426 } 3427 } 3428 3429 if (PrintCompilation && WizardMode) 3430 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3431 old_subword, old_long, new_int, new_long); 3432 if (C->log() != NULL) 3433 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3434 old_subword, old_long, new_int, new_long); 3435 3436 // Clean up any remaining occurrences of zmem: 3437 remove_extra_zeroes(); 3438 } 3439 3440 // Explore forward from in(start) to find the first fully initialized 3441 // word, and return its offset. Skip groups of subword stores which 3442 // together initialize full words. If in(start) is itself part of a 3443 // fully initialized word, return the offset of in(start). If there 3444 // are no following full-word stores, or if something is fishy, return 3445 // a negative value. 3446 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3447 int int_map = 0; 3448 intptr_t int_map_off = 0; 3449 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3450 3451 for (uint i = start, limit = req(); i < limit; i++) { 3452 Node* st = in(i); 3453 3454 intptr_t st_off = get_store_offset(st, phase); 3455 if (st_off < 0) break; // return conservative answer 3456 3457 int st_size = st->as_Store()->memory_size(); 3458 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3459 return st_off; // we found a complete word init 3460 } 3461 3462 // update the map: 3463 3464 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); 3465 if (this_int_off != int_map_off) { 3466 // reset the map: 3467 int_map = 0; 3468 int_map_off = this_int_off; 3469 } 3470 3471 int subword_off = st_off - this_int_off; 3472 int_map |= right_n_bits(st_size) << subword_off; 3473 if ((int_map & FULL_MAP) == FULL_MAP) { 3474 return this_int_off; // we found a complete word init 3475 } 3476 3477 // Did this store hit or cross the word boundary? 3478 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); 3479 if (next_int_off == this_int_off + BytesPerInt) { 3480 // We passed the current int, without fully initializing it. 3481 int_map_off = next_int_off; 3482 int_map >>= BytesPerInt; 3483 } else if (next_int_off > this_int_off + BytesPerInt) { 3484 // We passed the current and next int. 3485 return this_int_off + BytesPerInt; 3486 } 3487 } 3488 3489 return -1; 3490 } 3491 3492 3493 // Called when the associated AllocateNode is expanded into CFG. 3494 // At this point, we may perform additional optimizations. 3495 // Linearize the stores by ascending offset, to make memory 3496 // activity as coherent as possible. 3497 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3498 intptr_t header_size, 3499 Node* size_in_bytes, 3500 PhaseGVN* phase) { 3501 assert(!is_complete(), "not already complete"); 3502 assert(stores_are_sane(phase), ""); 3503 assert(allocation() != NULL, "must be present"); 3504 3505 remove_extra_zeroes(); 3506 3507 if (ReduceFieldZeroing || ReduceBulkZeroing) 3508 // reduce instruction count for common initialization patterns 3509 coalesce_subword_stores(header_size, size_in_bytes, phase); 3510 3511 Node* zmem = zero_memory(); // initially zero memory state 3512 Node* inits = zmem; // accumulating a linearized chain of inits 3513 #ifdef ASSERT 3514 intptr_t first_offset = allocation()->minimum_header_size(); 3515 intptr_t last_init_off = first_offset; // previous init offset 3516 intptr_t last_init_end = first_offset; // previous init offset+size 3517 intptr_t last_tile_end = first_offset; // previous tile offset+size 3518 #endif 3519 intptr_t zeroes_done = header_size; 3520 3521 bool do_zeroing = true; // we might give up if inits are very sparse 3522 int big_init_gaps = 0; // how many large gaps have we seen? 3523 3524 if (ZeroTLAB) do_zeroing = false; 3525 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3526 3527 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3528 Node* st = in(i); 3529 intptr_t st_off = get_store_offset(st, phase); 3530 if (st_off < 0) 3531 break; // unknown junk in the inits 3532 if (st->in(MemNode::Memory) != zmem) 3533 break; // complicated store chains somehow in list 3534 3535 int st_size = st->as_Store()->memory_size(); 3536 intptr_t next_init_off = st_off + st_size; 3537 3538 if (do_zeroing && zeroes_done < next_init_off) { 3539 // See if this store needs a zero before it or under it. 3540 intptr_t zeroes_needed = st_off; 3541 3542 if (st_size < BytesPerInt) { 3543 // Look for subword stores which only partially initialize words. 3544 // If we find some, we must lay down some word-level zeroes first, 3545 // underneath the subword stores. 3546 // 3547 // Examples: 3548 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3549 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3550 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3551 // 3552 // Note: coalesce_subword_stores may have already done this, 3553 // if it was prompted by constant non-zero subword initializers. 3554 // But this case can still arise with non-constant stores. 3555 3556 intptr_t next_full_store = find_next_fullword_store(i, phase); 3557 3558 // In the examples above: 3559 // in(i) p q r s x y z 3560 // st_off 12 13 14 15 12 13 14 3561 // st_size 1 1 1 1 1 1 1 3562 // next_full_s. 12 16 16 16 16 16 16 3563 // z's_done 12 16 16 16 12 16 12 3564 // z's_needed 12 16 16 16 16 16 16 3565 // zsize 0 0 0 0 4 0 4 3566 if (next_full_store < 0) { 3567 // Conservative tack: Zero to end of current word. 3568 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); 3569 } else { 3570 // Zero to beginning of next fully initialized word. 3571 // Or, don't zero at all, if we are already in that word. 3572 assert(next_full_store >= zeroes_needed, "must go forward"); 3573 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3574 zeroes_needed = next_full_store; 3575 } 3576 } 3577 3578 if (zeroes_needed > zeroes_done) { 3579 intptr_t zsize = zeroes_needed - zeroes_done; 3580 // Do some incremental zeroing on rawmem, in parallel with inits. 3581 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3582 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3583 zeroes_done, zeroes_needed, 3584 phase); 3585 zeroes_done = zeroes_needed; 3586 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) 3587 do_zeroing = false; // leave the hole, next time 3588 } 3589 } 3590 3591 // Collect the store and move on: 3592 st->set_req(MemNode::Memory, inits); 3593 inits = st; // put it on the linearized chain 3594 set_req(i, zmem); // unhook from previous position 3595 3596 if (zeroes_done == st_off) 3597 zeroes_done = next_init_off; 3598 3599 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3600 3601 #ifdef ASSERT 3602 // Various order invariants. Weaker than stores_are_sane because 3603 // a large constant tile can be filled in by smaller non-constant stores. 3604 assert(st_off >= last_init_off, "inits do not reverse"); 3605 last_init_off = st_off; 3606 const Type* val = NULL; 3607 if (st_size >= BytesPerInt && 3608 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3609 (int)val->basic_type() < (int)T_OBJECT) { 3610 assert(st_off >= last_tile_end, "tiles do not overlap"); 3611 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3612 last_tile_end = MAX2(last_tile_end, next_init_off); 3613 } else { 3614 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); 3615 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3616 assert(st_off >= last_init_end, "inits do not overlap"); 3617 last_init_end = next_init_off; // it's a non-tile 3618 } 3619 #endif //ASSERT 3620 } 3621 3622 remove_extra_zeroes(); // clear out all the zmems left over 3623 add_req(inits); 3624 3625 if (!ZeroTLAB) { 3626 // If anything remains to be zeroed, zero it all now. 3627 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3628 // if it is the last unused 4 bytes of an instance, forget about it 3629 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3630 if (zeroes_done + BytesPerLong >= size_limit) { 3631 assert(allocation() != NULL, ""); 3632 if (allocation()->Opcode() == Op_Allocate) { 3633 Node* klass_node = allocation()->in(AllocateNode::KlassNode); 3634 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3635 if (zeroes_done == k->layout_helper()) 3636 zeroes_done = size_limit; 3637 } 3638 } 3639 if (zeroes_done < size_limit) { 3640 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3641 zeroes_done, size_in_bytes, phase); 3642 } 3643 } 3644 3645 set_complete(phase); 3646 return rawmem; 3647 } 3648 3649 3650 #ifdef ASSERT 3651 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3652 if (is_complete()) 3653 return true; // stores could be anything at this point 3654 assert(allocation() != NULL, "must be present"); 3655 intptr_t last_off = allocation()->minimum_header_size(); 3656 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3657 Node* st = in(i); 3658 intptr_t st_off = get_store_offset(st, phase); 3659 if (st_off < 0) continue; // ignore dead garbage 3660 if (last_off > st_off) { 3661 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off); 3662 this->dump(2); 3663 assert(false, "ascending store offsets"); 3664 return false; 3665 } 3666 last_off = st_off + st->as_Store()->memory_size(); 3667 } 3668 return true; 3669 } 3670 #endif //ASSERT 3671 3672 3673 3674 3675 //============================MergeMemNode===================================== 3676 // 3677 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 3678 // contributing store or call operations. Each contributor provides the memory 3679 // state for a particular "alias type" (see Compile::alias_type). For example, 3680 // if a MergeMem has an input X for alias category #6, then any memory reference 3681 // to alias category #6 may use X as its memory state input, as an exact equivalent 3682 // to using the MergeMem as a whole. 3683 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 3684 // 3685 // (Here, the <N> notation gives the index of the relevant adr_type.) 3686 // 3687 // In one special case (and more cases in the future), alias categories overlap. 3688 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 3689 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 3690 // it is exactly equivalent to that state W: 3691 // MergeMem(<Bot>: W) <==> W 3692 // 3693 // Usually, the merge has more than one input. In that case, where inputs 3694 // overlap (i.e., one is Bot), the narrower alias type determines the memory 3695 // state for that type, and the wider alias type (Bot) fills in everywhere else: 3696 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 3697 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 3698 // 3699 // A merge can take a "wide" memory state as one of its narrow inputs. 3700 // This simply means that the merge observes out only the relevant parts of 3701 // the wide input. That is, wide memory states arriving at narrow merge inputs 3702 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 3703 // 3704 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 3705 // and that memory slices "leak through": 3706 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 3707 // 3708 // But, in such a cascade, repeated memory slices can "block the leak": 3709 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 3710 // 3711 // In the last example, Y is not part of the combined memory state of the 3712 // outermost MergeMem. The system must, of course, prevent unschedulable 3713 // memory states from arising, so you can be sure that the state Y is somehow 3714 // a precursor to state Y'. 3715 // 3716 // 3717 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 3718 // of each MergeMemNode array are exactly the numerical alias indexes, including 3719 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 3720 // Compile::alias_type (and kin) produce and manage these indexes. 3721 // 3722 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 3723 // (Note that this provides quick access to the top node inside MergeMem methods, 3724 // without the need to reach out via TLS to Compile::current.) 3725 // 3726 // As a consequence of what was just described, a MergeMem that represents a full 3727 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 3728 // containing all alias categories. 3729 // 3730 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 3731 // 3732 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 3733 // a memory state for the alias type <N>, or else the top node, meaning that 3734 // there is no particular input for that alias type. Note that the length of 3735 // a MergeMem is variable, and may be extended at any time to accommodate new 3736 // memory states at larger alias indexes. When merges grow, they are of course 3737 // filled with "top" in the unused in() positions. 3738 // 3739 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 3740 // (Top was chosen because it works smoothly with passes like GCM.) 3741 // 3742 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 3743 // the type of random VM bits like TLS references.) Since it is always the 3744 // first non-Bot memory slice, some low-level loops use it to initialize an 3745 // index variable: for (i = AliasIdxRaw; i < req(); i++). 3746 // 3747 // 3748 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 3749 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 3750 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 3751 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 3752 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 3753 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 3754 // 3755 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 3756 // really that different from the other memory inputs. An abbreviation called 3757 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 3758 // 3759 // 3760 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 3761 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 3762 // that "emerges though" the base memory will be marked as excluding the alias types 3763 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 3764 // 3765 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 3766 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 3767 // 3768 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 3769 // (It is currently unimplemented.) As you can see, the resulting merge is 3770 // actually a disjoint union of memory states, rather than an overlay. 3771 // 3772 3773 //------------------------------MergeMemNode----------------------------------- 3774 Node* MergeMemNode::make_empty_memory() { 3775 Node* empty_memory = (Node*) Compile::current()->top(); 3776 assert(empty_memory->is_top(), "correct sentinel identity"); 3777 return empty_memory; 3778 } 3779 3780 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 3781 init_class_id(Class_MergeMem); 3782 // all inputs are nullified in Node::Node(int) 3783 // set_input(0, NULL); // no control input 3784 3785 // Initialize the edges uniformly to top, for starters. 3786 Node* empty_mem = make_empty_memory(); 3787 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 3788 init_req(i,empty_mem); 3789 } 3790 assert(empty_memory() == empty_mem, ""); 3791 3792 if( new_base != NULL && new_base->is_MergeMem() ) { 3793 MergeMemNode* mdef = new_base->as_MergeMem(); 3794 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 3795 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 3796 mms.set_memory(mms.memory2()); 3797 } 3798 assert(base_memory() == mdef->base_memory(), ""); 3799 } else { 3800 set_base_memory(new_base); 3801 } 3802 } 3803 3804 // Make a new, untransformed MergeMem with the same base as 'mem'. 3805 // If mem is itself a MergeMem, populate the result with the same edges. 3806 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) { 3807 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem); 3808 } 3809 3810 //------------------------------cmp-------------------------------------------- 3811 uint MergeMemNode::hash() const { return NO_HASH; } 3812 uint MergeMemNode::cmp( const Node &n ) const { 3813 return (&n == this); // Always fail except on self 3814 } 3815 3816 //------------------------------Identity--------------------------------------- 3817 Node* MergeMemNode::Identity(PhaseTransform *phase) { 3818 // Identity if this merge point does not record any interesting memory 3819 // disambiguations. 3820 Node* base_mem = base_memory(); 3821 Node* empty_mem = empty_memory(); 3822 if (base_mem != empty_mem) { // Memory path is not dead? 3823 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3824 Node* mem = in(i); 3825 if (mem != empty_mem && mem != base_mem) { 3826 return this; // Many memory splits; no change 3827 } 3828 } 3829 } 3830 return base_mem; // No memory splits; ID on the one true input 3831 } 3832 3833 //------------------------------Ideal------------------------------------------ 3834 // This method is invoked recursively on chains of MergeMem nodes 3835 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3836 // Remove chain'd MergeMems 3837 // 3838 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 3839 // relative to the "in(Bot)". Since we are patching both at the same time, 3840 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 3841 // but rewrite each "in(i)" relative to the new "in(Bot)". 3842 Node *progress = NULL; 3843 3844 3845 Node* old_base = base_memory(); 3846 Node* empty_mem = empty_memory(); 3847 if (old_base == empty_mem) 3848 return NULL; // Dead memory path. 3849 3850 MergeMemNode* old_mbase; 3851 if (old_base != NULL && old_base->is_MergeMem()) 3852 old_mbase = old_base->as_MergeMem(); 3853 else 3854 old_mbase = NULL; 3855 Node* new_base = old_base; 3856 3857 // simplify stacked MergeMems in base memory 3858 if (old_mbase) new_base = old_mbase->base_memory(); 3859 3860 // the base memory might contribute new slices beyond my req() 3861 if (old_mbase) grow_to_match(old_mbase); 3862 3863 // Look carefully at the base node if it is a phi. 3864 PhiNode* phi_base; 3865 if (new_base != NULL && new_base->is_Phi()) 3866 phi_base = new_base->as_Phi(); 3867 else 3868 phi_base = NULL; 3869 3870 Node* phi_reg = NULL; 3871 uint phi_len = (uint)-1; 3872 if (phi_base != NULL && !phi_base->is_copy()) { 3873 // do not examine phi if degraded to a copy 3874 phi_reg = phi_base->region(); 3875 phi_len = phi_base->req(); 3876 // see if the phi is unfinished 3877 for (uint i = 1; i < phi_len; i++) { 3878 if (phi_base->in(i) == NULL) { 3879 // incomplete phi; do not look at it yet! 3880 phi_reg = NULL; 3881 phi_len = (uint)-1; 3882 break; 3883 } 3884 } 3885 } 3886 3887 // Note: We do not call verify_sparse on entry, because inputs 3888 // can normalize to the base_memory via subsume_node or similar 3889 // mechanisms. This method repairs that damage. 3890 3891 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 3892 3893 // Look at each slice. 3894 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3895 Node* old_in = in(i); 3896 // calculate the old memory value 3897 Node* old_mem = old_in; 3898 if (old_mem == empty_mem) old_mem = old_base; 3899 assert(old_mem == memory_at(i), ""); 3900 3901 // maybe update (reslice) the old memory value 3902 3903 // simplify stacked MergeMems 3904 Node* new_mem = old_mem; 3905 MergeMemNode* old_mmem; 3906 if (old_mem != NULL && old_mem->is_MergeMem()) 3907 old_mmem = old_mem->as_MergeMem(); 3908 else 3909 old_mmem = NULL; 3910 if (old_mmem == this) { 3911 // This can happen if loops break up and safepoints disappear. 3912 // A merge of BotPtr (default) with a RawPtr memory derived from a 3913 // safepoint can be rewritten to a merge of the same BotPtr with 3914 // the BotPtr phi coming into the loop. If that phi disappears 3915 // also, we can end up with a self-loop of the mergemem. 3916 // In general, if loops degenerate and memory effects disappear, 3917 // a mergemem can be left looking at itself. This simply means 3918 // that the mergemem's default should be used, since there is 3919 // no longer any apparent effect on this slice. 3920 // Note: If a memory slice is a MergeMem cycle, it is unreachable 3921 // from start. Update the input to TOP. 3922 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 3923 } 3924 else if (old_mmem != NULL) { 3925 new_mem = old_mmem->memory_at(i); 3926 } 3927 // else preceding memory was not a MergeMem 3928 3929 // replace equivalent phis (unfortunately, they do not GVN together) 3930 if (new_mem != NULL && new_mem != new_base && 3931 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 3932 if (new_mem->is_Phi()) { 3933 PhiNode* phi_mem = new_mem->as_Phi(); 3934 for (uint i = 1; i < phi_len; i++) { 3935 if (phi_base->in(i) != phi_mem->in(i)) { 3936 phi_mem = NULL; 3937 break; 3938 } 3939 } 3940 if (phi_mem != NULL) { 3941 // equivalent phi nodes; revert to the def 3942 new_mem = new_base; 3943 } 3944 } 3945 } 3946 3947 // maybe store down a new value 3948 Node* new_in = new_mem; 3949 if (new_in == new_base) new_in = empty_mem; 3950 3951 if (new_in != old_in) { 3952 // Warning: Do not combine this "if" with the previous "if" 3953 // A memory slice might have be be rewritten even if it is semantically 3954 // unchanged, if the base_memory value has changed. 3955 set_req(i, new_in); 3956 progress = this; // Report progress 3957 } 3958 } 3959 3960 if (new_base != old_base) { 3961 set_req(Compile::AliasIdxBot, new_base); 3962 // Don't use set_base_memory(new_base), because we need to update du. 3963 assert(base_memory() == new_base, ""); 3964 progress = this; 3965 } 3966 3967 if( base_memory() == this ) { 3968 // a self cycle indicates this memory path is dead 3969 set_req(Compile::AliasIdxBot, empty_mem); 3970 } 3971 3972 // Resolve external cycles by calling Ideal on a MergeMem base_memory 3973 // Recursion must occur after the self cycle check above 3974 if( base_memory()->is_MergeMem() ) { 3975 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 3976 Node *m = phase->transform(new_mbase); // Rollup any cycles 3977 if( m != NULL && (m->is_top() || 3978 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 3979 // propagate rollup of dead cycle to self 3980 set_req(Compile::AliasIdxBot, empty_mem); 3981 } 3982 } 3983 3984 if( base_memory() == empty_mem ) { 3985 progress = this; 3986 // Cut inputs during Parse phase only. 3987 // During Optimize phase a dead MergeMem node will be subsumed by Top. 3988 if( !can_reshape ) { 3989 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3990 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 3991 } 3992 } 3993 } 3994 3995 if( !progress && base_memory()->is_Phi() && can_reshape ) { 3996 // Check if PhiNode::Ideal's "Split phis through memory merges" 3997 // transform should be attempted. Look for this->phi->this cycle. 3998 uint merge_width = req(); 3999 if (merge_width > Compile::AliasIdxRaw) { 4000 PhiNode* phi = base_memory()->as_Phi(); 4001 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4002 if (phi->in(i) == this) { 4003 phase->is_IterGVN()->_worklist.push(phi); 4004 break; 4005 } 4006 } 4007 } 4008 } 4009 4010 assert(progress || verify_sparse(), "please, no dups of base"); 4011 return progress; 4012 } 4013 4014 //-------------------------set_base_memory------------------------------------- 4015 void MergeMemNode::set_base_memory(Node *new_base) { 4016 Node* empty_mem = empty_memory(); 4017 set_req(Compile::AliasIdxBot, new_base); 4018 assert(memory_at(req()) == new_base, "must set default memory"); 4019 // Clear out other occurrences of new_base: 4020 if (new_base != empty_mem) { 4021 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4022 if (in(i) == new_base) set_req(i, empty_mem); 4023 } 4024 } 4025 } 4026 4027 //------------------------------out_RegMask------------------------------------ 4028 const RegMask &MergeMemNode::out_RegMask() const { 4029 return RegMask::Empty; 4030 } 4031 4032 //------------------------------dump_spec-------------------------------------- 4033 #ifndef PRODUCT 4034 void MergeMemNode::dump_spec(outputStream *st) const { 4035 st->print(" {"); 4036 Node* base_mem = base_memory(); 4037 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4038 Node* mem = memory_at(i); 4039 if (mem == base_mem) { st->print(" -"); continue; } 4040 st->print( " N%d:", mem->_idx ); 4041 Compile::current()->get_adr_type(i)->dump_on(st); 4042 } 4043 st->print(" }"); 4044 } 4045 #endif // !PRODUCT 4046 4047 4048 #ifdef ASSERT 4049 static bool might_be_same(Node* a, Node* b) { 4050 if (a == b) return true; 4051 if (!(a->is_Phi() || b->is_Phi())) return false; 4052 // phis shift around during optimization 4053 return true; // pretty stupid... 4054 } 4055 4056 // verify a narrow slice (either incoming or outgoing) 4057 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4058 if (!VerifyAliases) return; // don't bother to verify unless requested 4059 if (is_error_reported()) return; // muzzle asserts when debugging an error 4060 if (Node::in_dump()) return; // muzzle asserts when printing 4061 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4062 assert(n != NULL, ""); 4063 // Elide intervening MergeMem's 4064 while (n->is_MergeMem()) { 4065 n = n->as_MergeMem()->memory_at(alias_idx); 4066 } 4067 Compile* C = Compile::current(); 4068 const TypePtr* n_adr_type = n->adr_type(); 4069 if (n == m->empty_memory()) { 4070 // Implicit copy of base_memory() 4071 } else if (n_adr_type != TypePtr::BOTTOM) { 4072 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4073 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4074 } else { 4075 // A few places like make_runtime_call "know" that VM calls are narrow, 4076 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4077 bool expected_wide_mem = false; 4078 if (n == m->base_memory()) { 4079 expected_wide_mem = true; 4080 } else if (alias_idx == Compile::AliasIdxRaw || 4081 n == m->memory_at(Compile::AliasIdxRaw)) { 4082 expected_wide_mem = true; 4083 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4084 // memory can "leak through" calls on channels that 4085 // are write-once. Allow this also. 4086 expected_wide_mem = true; 4087 } 4088 assert(expected_wide_mem, "expected narrow slice replacement"); 4089 } 4090 } 4091 #else // !ASSERT 4092 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op 4093 #endif 4094 4095 4096 //-----------------------------memory_at--------------------------------------- 4097 Node* MergeMemNode::memory_at(uint alias_idx) const { 4098 assert(alias_idx >= Compile::AliasIdxRaw || 4099 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4100 "must avoid base_memory and AliasIdxTop"); 4101 4102 // Otherwise, it is a narrow slice. 4103 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4104 Compile *C = Compile::current(); 4105 if (is_empty_memory(n)) { 4106 // the array is sparse; empty slots are the "top" node 4107 n = base_memory(); 4108 assert(Node::in_dump() 4109 || n == NULL || n->bottom_type() == Type::TOP 4110 || n->adr_type() == NULL // address is TOP 4111 || n->adr_type() == TypePtr::BOTTOM 4112 || n->adr_type() == TypeRawPtr::BOTTOM 4113 || Compile::current()->AliasLevel() == 0, 4114 "must be a wide memory"); 4115 // AliasLevel == 0 if we are organizing the memory states manually. 4116 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4117 } else { 4118 // make sure the stored slice is sane 4119 #ifdef ASSERT 4120 if (is_error_reported() || Node::in_dump()) { 4121 } else if (might_be_same(n, base_memory())) { 4122 // Give it a pass: It is a mostly harmless repetition of the base. 4123 // This can arise normally from node subsumption during optimization. 4124 } else { 4125 verify_memory_slice(this, alias_idx, n); 4126 } 4127 #endif 4128 } 4129 return n; 4130 } 4131 4132 //---------------------------set_memory_at------------------------------------- 4133 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4134 verify_memory_slice(this, alias_idx, n); 4135 Node* empty_mem = empty_memory(); 4136 if (n == base_memory()) n = empty_mem; // collapse default 4137 uint need_req = alias_idx+1; 4138 if (req() < need_req) { 4139 if (n == empty_mem) return; // already the default, so do not grow me 4140 // grow the sparse array 4141 do { 4142 add_req(empty_mem); 4143 } while (req() < need_req); 4144 } 4145 set_req( alias_idx, n ); 4146 } 4147 4148 4149 4150 //--------------------------iteration_setup------------------------------------ 4151 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4152 if (other != NULL) { 4153 grow_to_match(other); 4154 // invariant: the finite support of mm2 is within mm->req() 4155 #ifdef ASSERT 4156 for (uint i = req(); i < other->req(); i++) { 4157 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4158 } 4159 #endif 4160 } 4161 // Replace spurious copies of base_memory by top. 4162 Node* base_mem = base_memory(); 4163 if (base_mem != NULL && !base_mem->is_top()) { 4164 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4165 if (in(i) == base_mem) 4166 set_req(i, empty_memory()); 4167 } 4168 } 4169 } 4170 4171 //---------------------------grow_to_match------------------------------------- 4172 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4173 Node* empty_mem = empty_memory(); 4174 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4175 // look for the finite support of the other memory 4176 for (uint i = other->req(); --i >= req(); ) { 4177 if (other->in(i) != empty_mem) { 4178 uint new_len = i+1; 4179 while (req() < new_len) add_req(empty_mem); 4180 break; 4181 } 4182 } 4183 } 4184 4185 //---------------------------verify_sparse------------------------------------- 4186 #ifndef PRODUCT 4187 bool MergeMemNode::verify_sparse() const { 4188 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4189 Node* base_mem = base_memory(); 4190 // The following can happen in degenerate cases, since empty==top. 4191 if (is_empty_memory(base_mem)) return true; 4192 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4193 assert(in(i) != NULL, "sane slice"); 4194 if (in(i) == base_mem) return false; // should have been the sentinel value! 4195 } 4196 return true; 4197 } 4198 4199 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4200 Node* n; 4201 n = mm->in(idx); 4202 if (mem == n) return true; // might be empty_memory() 4203 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4204 if (mem == n) return true; 4205 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4206 if (mem == n) return true; 4207 if (n == NULL) break; 4208 } 4209 return false; 4210 } 4211 #endif // !PRODUCT