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 Node *address = in(MemNode::Address); 269 const Type *t_adr = phase->type( address ); 270 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL 271 272 if( can_reshape && igvn != NULL && 273 (igvn->_worklist.member(address) || 274 igvn->_worklist.size() > 0 && (phase->type(address) != adr_type())) ) { 275 // The address's base and type may change when the address is processed. 276 // Delay this mem node transformation until the address is processed. 277 phase->is_IterGVN()->_worklist.push(this); 278 return NodeSentinel; // caller will return NULL 279 } 280 281 // Do NOT remove or optimize the next lines: ensure a new alias index 282 // is allocated for an oop pointer type before Escape Analysis. 283 // Note: C++ will not remove it since the call has side effect. 284 if ( t_adr->isa_oopptr() ) { 285 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 286 } 287 288 #ifdef ASSERT 289 Node* base = NULL; 290 if (address->is_AddP()) 291 base = address->in(AddPNode::Base); 292 assert(base == NULL || t_adr->isa_rawptr() || 293 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?"); 294 #endif 295 296 // Avoid independent memory operations 297 Node* old_mem = mem; 298 299 // The code which unhooks non-raw memories from complete (macro-expanded) 300 // initializations was removed. After macro-expansion all stores catched 301 // by Initialize node became raw stores and there is no information 302 // which memory slices they modify. So it is unsafe to move any memory 303 // operation above these stores. Also in most cases hooked non-raw memories 304 // were already unhooked by using information from detect_ptr_independence() 305 // and find_previous_store(). 306 307 if (mem->is_MergeMem()) { 308 MergeMemNode* mmem = mem->as_MergeMem(); 309 const TypePtr *tp = t_adr->is_ptr(); 310 311 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 312 } 313 314 if (mem != old_mem) { 315 set_req(MemNode::Memory, mem); 316 if (phase->type( mem ) == Type::TOP) return NodeSentinel; 317 return this; 318 } 319 320 // let the subclass continue analyzing... 321 return NULL; 322 } 323 324 // Helper function for proving some simple control dominations. 325 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 326 // Already assumes that 'dom' is available at 'sub', and that 'sub' 327 // is not a constant (dominated by the method's StartNode). 328 // Used by MemNode::find_previous_store to prove that the 329 // control input of a memory operation predates (dominates) 330 // an allocation it wants to look past. 331 bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 332 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 333 return false; // Conservative answer for dead code 334 335 // Check 'dom'. Skip Proj and CatchProj nodes. 336 dom = dom->find_exact_control(dom); 337 if (dom == NULL || dom->is_top()) 338 return false; // Conservative answer for dead code 339 340 if (dom == sub) { 341 // For the case when, for example, 'sub' is Initialize and the original 342 // 'dom' is Proj node of the 'sub'. 343 return false; 344 } 345 346 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 347 return true; 348 349 // 'dom' dominates 'sub' if its control edge and control edges 350 // of all its inputs dominate or equal to sub's control edge. 351 352 // Currently 'sub' is either Allocate, Initialize or Start nodes. 353 // Or Region for the check in LoadNode::Ideal(); 354 // 'sub' should have sub->in(0) != NULL. 355 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 356 sub->is_Region(), "expecting only these nodes"); 357 358 // Get control edge of 'sub'. 359 Node* orig_sub = sub; 360 sub = sub->find_exact_control(sub->in(0)); 361 if (sub == NULL || sub->is_top()) 362 return false; // Conservative answer for dead code 363 364 assert(sub->is_CFG(), "expecting control"); 365 366 if (sub == dom) 367 return true; 368 369 if (sub->is_Start() || sub->is_Root()) 370 return false; 371 372 { 373 // Check all control edges of 'dom'. 374 375 ResourceMark rm; 376 Arena* arena = Thread::current()->resource_area(); 377 Node_List nlist(arena); 378 Unique_Node_List dom_list(arena); 379 380 dom_list.push(dom); 381 bool only_dominating_controls = false; 382 383 for (uint next = 0; next < dom_list.size(); next++) { 384 Node* n = dom_list.at(next); 385 if (n == orig_sub) 386 return false; // One of dom's inputs dominated by sub. 387 if (!n->is_CFG() && n->pinned()) { 388 // Check only own control edge for pinned non-control nodes. 389 n = n->find_exact_control(n->in(0)); 390 if (n == NULL || n->is_top()) 391 return false; // Conservative answer for dead code 392 assert(n->is_CFG(), "expecting control"); 393 dom_list.push(n); 394 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 395 only_dominating_controls = true; 396 } else if (n->is_CFG()) { 397 if (n->dominates(sub, nlist)) 398 only_dominating_controls = true; 399 else 400 return false; 401 } else { 402 // First, own control edge. 403 Node* m = n->find_exact_control(n->in(0)); 404 if (m != NULL) { 405 if (m->is_top()) 406 return false; // Conservative answer for dead code 407 dom_list.push(m); 408 } 409 // Now, the rest of edges. 410 uint cnt = n->req(); 411 for (uint i = 1; i < cnt; i++) { 412 m = n->find_exact_control(n->in(i)); 413 if (m == NULL || m->is_top()) 414 continue; 415 dom_list.push(m); 416 } 417 } 418 } 419 return only_dominating_controls; 420 } 421 } 422 423 //---------------------detect_ptr_independence--------------------------------- 424 // Used by MemNode::find_previous_store to prove that two base 425 // pointers are never equal. 426 // The pointers are accompanied by their associated allocations, 427 // if any, which have been previously discovered by the caller. 428 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 429 Node* p2, AllocateNode* a2, 430 PhaseTransform* phase) { 431 // Attempt to prove that these two pointers cannot be aliased. 432 // They may both manifestly be allocations, and they should differ. 433 // Or, if they are not both allocations, they can be distinct constants. 434 // Otherwise, one is an allocation and the other a pre-existing value. 435 if (a1 == NULL && a2 == NULL) { // neither an allocation 436 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 437 } else if (a1 != NULL && a2 != NULL) { // both allocations 438 return (a1 != a2); 439 } else if (a1 != NULL) { // one allocation a1 440 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 441 return all_controls_dominate(p2, a1); 442 } else { //(a2 != NULL) // one allocation a2 443 return all_controls_dominate(p1, a2); 444 } 445 return false; 446 } 447 448 449 // The logic for reordering loads and stores uses four steps: 450 // (a) Walk carefully past stores and initializations which we 451 // can prove are independent of this load. 452 // (b) Observe that the next memory state makes an exact match 453 // with self (load or store), and locate the relevant store. 454 // (c) Ensure that, if we were to wire self directly to the store, 455 // the optimizer would fold it up somehow. 456 // (d) Do the rewiring, and return, depending on some other part of 457 // the optimizer to fold up the load. 458 // This routine handles steps (a) and (b). Steps (c) and (d) are 459 // specific to loads and stores, so they are handled by the callers. 460 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 461 // 462 Node* MemNode::find_previous_store(PhaseTransform* phase) { 463 Node* ctrl = in(MemNode::Control); 464 Node* adr = in(MemNode::Address); 465 intptr_t offset = 0; 466 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 467 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 468 469 if (offset == Type::OffsetBot) 470 return NULL; // cannot unalias unless there are precise offsets 471 472 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 473 474 intptr_t size_in_bytes = memory_size(); 475 476 Node* mem = in(MemNode::Memory); // start searching here... 477 478 int cnt = 50; // Cycle limiter 479 for (;;) { // While we can dance past unrelated stores... 480 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 481 482 if (mem->is_Store()) { 483 Node* st_adr = mem->in(MemNode::Address); 484 intptr_t st_offset = 0; 485 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 486 if (st_base == NULL) 487 break; // inscrutable pointer 488 if (st_offset != offset && st_offset != Type::OffsetBot) { 489 const int MAX_STORE = BytesPerLong; 490 if (st_offset >= offset + size_in_bytes || 491 st_offset <= offset - MAX_STORE || 492 st_offset <= offset - mem->as_Store()->memory_size()) { 493 // Success: The offsets are provably independent. 494 // (You may ask, why not just test st_offset != offset and be done? 495 // The answer is that stores of different sizes can co-exist 496 // in the same sequence of RawMem effects. We sometimes initialize 497 // a whole 'tile' of array elements with a single jint or jlong.) 498 mem = mem->in(MemNode::Memory); 499 continue; // (a) advance through independent store memory 500 } 501 } 502 if (st_base != base && 503 detect_ptr_independence(base, alloc, 504 st_base, 505 AllocateNode::Ideal_allocation(st_base, phase), 506 phase)) { 507 // Success: The bases are provably independent. 508 mem = mem->in(MemNode::Memory); 509 continue; // (a) advance through independent store memory 510 } 511 512 // (b) At this point, if the bases or offsets do not agree, we lose, 513 // since we have not managed to prove 'this' and 'mem' independent. 514 if (st_base == base && st_offset == offset) { 515 return mem; // let caller handle steps (c), (d) 516 } 517 518 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 519 InitializeNode* st_init = mem->in(0)->as_Initialize(); 520 AllocateNode* st_alloc = st_init->allocation(); 521 if (st_alloc == NULL) 522 break; // something degenerated 523 bool known_identical = false; 524 bool known_independent = false; 525 if (alloc == st_alloc) 526 known_identical = true; 527 else if (alloc != NULL) 528 known_independent = true; 529 else if (all_controls_dominate(this, st_alloc)) 530 known_independent = true; 531 532 if (known_independent) { 533 // The bases are provably independent: Either they are 534 // manifestly distinct allocations, or else the control 535 // of this load dominates the store's allocation. 536 int alias_idx = phase->C->get_alias_index(adr_type()); 537 if (alias_idx == Compile::AliasIdxRaw) { 538 mem = st_alloc->in(TypeFunc::Memory); 539 } else { 540 mem = st_init->memory(alias_idx); 541 } 542 continue; // (a) advance through independent store memory 543 } 544 545 // (b) at this point, if we are not looking at a store initializing 546 // the same allocation we are loading from, we lose. 547 if (known_identical) { 548 // From caller, can_see_stored_value will consult find_captured_store. 549 return mem; // let caller handle steps (c), (d) 550 } 551 552 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 553 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 554 if (mem->is_Proj() && mem->in(0)->is_Call()) { 555 CallNode *call = mem->in(0)->as_Call(); 556 if (!call->may_modify(addr_t, phase)) { 557 mem = call->in(TypeFunc::Memory); 558 continue; // (a) advance through independent call memory 559 } 560 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 561 mem = mem->in(0)->in(TypeFunc::Memory); 562 continue; // (a) advance through independent MemBar memory 563 } else if (mem->is_ClearArray()) { 564 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 565 // (the call updated 'mem' value) 566 continue; // (a) advance through independent allocation memory 567 } else { 568 // Can not bypass initialization of the instance 569 // we are looking for. 570 return mem; 571 } 572 } else if (mem->is_MergeMem()) { 573 int alias_idx = phase->C->get_alias_index(adr_type()); 574 mem = mem->as_MergeMem()->memory_at(alias_idx); 575 continue; // (a) advance through independent MergeMem memory 576 } 577 } 578 579 // Unless there is an explicit 'continue', we must bail out here, 580 // because 'mem' is an inscrutable memory state (e.g., a call). 581 break; 582 } 583 584 return NULL; // bail out 585 } 586 587 //----------------------calculate_adr_type------------------------------------- 588 // Helper function. Notices when the given type of address hits top or bottom. 589 // Also, asserts a cross-check of the type against the expected address type. 590 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 591 if (t == Type::TOP) return NULL; // does not touch memory any more? 592 #ifdef PRODUCT 593 cross_check = NULL; 594 #else 595 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL; 596 #endif 597 const TypePtr* tp = t->isa_ptr(); 598 if (tp == NULL) { 599 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 600 return TypePtr::BOTTOM; // touches lots of memory 601 } else { 602 #ifdef ASSERT 603 // %%%% [phh] We don't check the alias index if cross_check is 604 // TypeRawPtr::BOTTOM. Needs to be investigated. 605 if (cross_check != NULL && 606 cross_check != TypePtr::BOTTOM && 607 cross_check != TypeRawPtr::BOTTOM) { 608 // Recheck the alias index, to see if it has changed (due to a bug). 609 Compile* C = Compile::current(); 610 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 611 "must stay in the original alias category"); 612 // The type of the address must be contained in the adr_type, 613 // disregarding "null"-ness. 614 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 615 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 616 assert(cross_check->meet(tp_notnull) == cross_check, 617 "real address must not escape from expected memory type"); 618 } 619 #endif 620 return tp; 621 } 622 } 623 624 //------------------------adr_phi_is_loop_invariant---------------------------- 625 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted 626 // loop is loop invariant. Make a quick traversal of Phi and associated 627 // CastPP nodes, looking to see if they are a closed group within the loop. 628 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) { 629 // The idea is that the phi-nest must boil down to only CastPP nodes 630 // with the same data. This implies that any path into the loop already 631 // includes such a CastPP, and so the original cast, whatever its input, 632 // must be covered by an equivalent cast, with an earlier control input. 633 ResourceMark rm; 634 635 // The loop entry input of the phi should be the unique dominating 636 // node for every Phi/CastPP in the loop. 637 Unique_Node_List closure; 638 closure.push(adr_phi->in(LoopNode::EntryControl)); 639 640 // Add the phi node and the cast to the worklist. 641 Unique_Node_List worklist; 642 worklist.push(adr_phi); 643 if( cast != NULL ){ 644 if( !cast->is_ConstraintCast() ) return false; 645 worklist.push(cast); 646 } 647 648 // Begin recursive walk of phi nodes. 649 while( worklist.size() ){ 650 // Take a node off the worklist 651 Node *n = worklist.pop(); 652 if( !closure.member(n) ){ 653 // Add it to the closure. 654 closure.push(n); 655 // Make a sanity check to ensure we don't waste too much time here. 656 if( closure.size() > 20) return false; 657 // This node is OK if: 658 // - it is a cast of an identical value 659 // - or it is a phi node (then we add its inputs to the worklist) 660 // Otherwise, the node is not OK, and we presume the cast is not invariant 661 if( n->is_ConstraintCast() ){ 662 worklist.push(n->in(1)); 663 } else if( n->is_Phi() ) { 664 for( uint i = 1; i < n->req(); i++ ) { 665 worklist.push(n->in(i)); 666 } 667 } else { 668 return false; 669 } 670 } 671 } 672 673 // Quit when the worklist is empty, and we've found no offending nodes. 674 return true; 675 } 676 677 //------------------------------Ideal_DU_postCCP------------------------------- 678 // Find any cast-away of null-ness and keep its control. Null cast-aways are 679 // going away in this pass and we need to make this memory op depend on the 680 // gating null check. 681 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) { 682 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address)); 683 } 684 685 // I tried to leave the CastPP's in. This makes the graph more accurate in 686 // some sense; we get to keep around the knowledge that an oop is not-null 687 // after some test. Alas, the CastPP's interfere with GVN (some values are 688 // the regular oop, some are the CastPP of the oop, all merge at Phi's which 689 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed 690 // some of the more trivial cases in the optimizer. Removing more useless 691 // Phi's started allowing Loads to illegally float above null checks. I gave 692 // up on this approach. CNC 10/20/2000 693 // This static method may be called not from MemNode (EncodePNode calls it). 694 // Only the control edge of the node 'n' might be updated. 695 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) { 696 Node *skipped_cast = NULL; 697 // Need a null check? Regular static accesses do not because they are 698 // from constant addresses. Array ops are gated by the range check (which 699 // always includes a NULL check). Just check field ops. 700 if( n->in(MemNode::Control) == NULL ) { 701 // Scan upwards for the highest location we can place this memory op. 702 while( true ) { 703 switch( adr->Opcode() ) { 704 705 case Op_AddP: // No change to NULL-ness, so peek thru AddP's 706 adr = adr->in(AddPNode::Base); 707 continue; 708 709 case Op_DecodeN: // No change to NULL-ness, so peek thru 710 adr = adr->in(1); 711 continue; 712 713 case Op_CastPP: 714 // If the CastPP is useless, just peek on through it. 715 if( ccp->type(adr) == ccp->type(adr->in(1)) ) { 716 // Remember the cast that we've peeked though. If we peek 717 // through more than one, then we end up remembering the highest 718 // one, that is, if in a loop, the one closest to the top. 719 skipped_cast = adr; 720 adr = adr->in(1); 721 continue; 722 } 723 // CastPP is going away in this pass! We need this memory op to be 724 // control-dependent on the test that is guarding the CastPP. 725 ccp->hash_delete(n); 726 n->set_req(MemNode::Control, adr->in(0)); 727 ccp->hash_insert(n); 728 return n; 729 730 case Op_Phi: 731 // Attempt to float above a Phi to some dominating point. 732 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) { 733 // If we've already peeked through a Cast (which could have set the 734 // control), we can't float above a Phi, because the skipped Cast 735 // may not be loop invariant. 736 if (adr_phi_is_loop_invariant(adr, skipped_cast)) { 737 adr = adr->in(1); 738 continue; 739 } 740 } 741 742 // Intentional fallthrough! 743 744 // No obvious dominating point. The mem op is pinned below the Phi 745 // by the Phi itself. If the Phi goes away (no true value is merged) 746 // then the mem op can float, but not indefinitely. It must be pinned 747 // behind the controls leading to the Phi. 748 case Op_CheckCastPP: 749 // These usually stick around to change address type, however a 750 // useless one can be elided and we still need to pick up a control edge 751 if (adr->in(0) == NULL) { 752 // This CheckCastPP node has NO control and is likely useless. But we 753 // need check further up the ancestor chain for a control input to keep 754 // the node in place. 4959717. 755 skipped_cast = adr; 756 adr = adr->in(1); 757 continue; 758 } 759 ccp->hash_delete(n); 760 n->set_req(MemNode::Control, adr->in(0)); 761 ccp->hash_insert(n); 762 return n; 763 764 // List of "safe" opcodes; those that implicitly block the memory 765 // op below any null check. 766 case Op_CastX2P: // no null checks on native pointers 767 case Op_Parm: // 'this' pointer is not null 768 case Op_LoadP: // Loading from within a klass 769 case Op_LoadN: // Loading from within a klass 770 case Op_LoadKlass: // Loading from within a klass 771 case Op_LoadNKlass: // Loading from within a klass 772 case Op_ConP: // Loading from a klass 773 case Op_ConN: // Loading from a klass 774 case Op_CreateEx: // Sucking up the guts of an exception oop 775 case Op_Con: // Reading from TLS 776 case Op_CMoveP: // CMoveP is pinned 777 case Op_CMoveN: // CMoveN is pinned 778 break; // No progress 779 780 case Op_Proj: // Direct call to an allocation routine 781 case Op_SCMemProj: // Memory state from store conditional ops 782 #ifdef ASSERT 783 { 784 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value"); 785 const Node* call = adr->in(0); 786 if (call->is_CallJava()) { 787 const CallJavaNode* call_java = call->as_CallJava(); 788 const TypeTuple *r = call_java->tf()->range(); 789 assert(r->cnt() > TypeFunc::Parms, "must return value"); 790 const Type* ret_type = r->field_at(TypeFunc::Parms); 791 assert(ret_type && ret_type->isa_ptr(), "must return pointer"); 792 // We further presume that this is one of 793 // new_instance_Java, new_array_Java, or 794 // the like, but do not assert for this. 795 } else if (call->is_Allocate()) { 796 // similar case to new_instance_Java, etc. 797 } else if (!call->is_CallLeaf()) { 798 // Projections from fetch_oop (OSR) are allowed as well. 799 ShouldNotReachHere(); 800 } 801 } 802 #endif 803 break; 804 default: 805 ShouldNotReachHere(); 806 } 807 break; 808 } 809 } 810 811 return NULL; // No progress 812 } 813 814 815 //============================================================================= 816 uint LoadNode::size_of() const { return sizeof(*this); } 817 uint LoadNode::cmp( const Node &n ) const 818 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 819 const Type *LoadNode::bottom_type() const { return _type; } 820 uint LoadNode::ideal_reg() const { 821 return Matcher::base2reg[_type->base()]; 822 } 823 824 #ifndef PRODUCT 825 void LoadNode::dump_spec(outputStream *st) const { 826 MemNode::dump_spec(st); 827 if( !Verbose && !WizardMode ) { 828 // standard dump does this in Verbose and WizardMode 829 st->print(" #"); _type->dump_on(st); 830 } 831 } 832 #endif 833 834 #ifdef ASSERT 835 //----------------------------is_immutable_value------------------------------- 836 // Helper function to allow a raw load without control edge for some cases 837 bool LoadNode::is_immutable_value(Node* adr) { 838 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 839 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 840 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 841 in_bytes(JavaThread::osthread_offset()))); 842 } 843 #endif 844 845 //----------------------------LoadNode::make----------------------------------- 846 // Polymorphic factory method: 847 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) { 848 Compile* C = gvn.C; 849 850 // sanity check the alias category against the created node type 851 assert(!(adr_type->isa_oopptr() && 852 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 853 "use LoadKlassNode instead"); 854 assert(!(adr_type->isa_aryptr() && 855 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 856 "use LoadRangeNode instead"); 857 // Check control edge of raw loads 858 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 859 // oop will be recorded in oop map if load crosses safepoint 860 rt->isa_oopptr() || is_immutable_value(adr), 861 "raw memory operations should have control edge"); 862 switch (bt) { 863 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() ); 864 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() ); 865 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() ); 866 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() ); 867 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() ); 868 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() ); 869 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt ); 870 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt ); 871 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() ); 872 case T_OBJECT: 873 #ifdef _LP64 874 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 875 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop())); 876 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr()); 877 } else 878 #endif 879 { 880 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 881 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr()); 882 } 883 } 884 ShouldNotReachHere(); 885 return (LoadNode*)NULL; 886 } 887 888 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) { 889 bool require_atomic = true; 890 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic); 891 } 892 893 894 895 896 //------------------------------hash------------------------------------------- 897 uint LoadNode::hash() const { 898 // unroll addition of interesting fields 899 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 900 } 901 902 //---------------------------can_see_stored_value------------------------------ 903 // This routine exists to make sure this set of tests is done the same 904 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 905 // will change the graph shape in a way which makes memory alive twice at the 906 // same time (uses the Oracle model of aliasing), then some 907 // LoadXNode::Identity will fold things back to the equivalence-class model 908 // of aliasing. 909 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 910 Node* ld_adr = in(MemNode::Address); 911 912 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 913 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL; 914 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw && 915 atp->field() != NULL && !atp->field()->is_volatile()) { 916 uint alias_idx = atp->index(); 917 bool final = atp->field()->is_final(); 918 Node* result = NULL; 919 Node* current = st; 920 // Skip through chains of MemBarNodes checking the MergeMems for 921 // new states for the slice of this load. Stop once any other 922 // kind of node is encountered. Loads from final memory can skip 923 // through any kind of MemBar but normal loads shouldn't skip 924 // through MemBarAcquire since the could allow them to move out of 925 // a synchronized region. 926 while (current->is_Proj()) { 927 int opc = current->in(0)->Opcode(); 928 if ((final && opc == Op_MemBarAcquire) || 929 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) { 930 Node* mem = current->in(0)->in(TypeFunc::Memory); 931 if (mem->is_MergeMem()) { 932 MergeMemNode* merge = mem->as_MergeMem(); 933 Node* new_st = merge->memory_at(alias_idx); 934 if (new_st == merge->base_memory()) { 935 // Keep searching 936 current = merge->base_memory(); 937 continue; 938 } 939 // Save the new memory state for the slice and fall through 940 // to exit. 941 result = new_st; 942 } 943 } 944 break; 945 } 946 if (result != NULL) { 947 st = result; 948 } 949 } 950 951 952 // Loop around twice in the case Load -> Initialize -> Store. 953 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 954 for (int trip = 0; trip <= 1; trip++) { 955 956 if (st->is_Store()) { 957 Node* st_adr = st->in(MemNode::Address); 958 if (!phase->eqv(st_adr, ld_adr)) { 959 // Try harder before giving up... Match raw and non-raw pointers. 960 intptr_t st_off = 0; 961 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 962 if (alloc == NULL) return NULL; 963 intptr_t ld_off = 0; 964 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 965 if (alloc != allo2) return NULL; 966 if (ld_off != st_off) return NULL; 967 // At this point we have proven something like this setup: 968 // A = Allocate(...) 969 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 970 // S = StoreQ(, AddP(, A.Parm , #Off), V) 971 // (Actually, we haven't yet proven the Q's are the same.) 972 // In other words, we are loading from a casted version of 973 // the same pointer-and-offset that we stored to. 974 // Thus, we are able to replace L by V. 975 } 976 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 977 if (store_Opcode() != st->Opcode()) 978 return NULL; 979 return st->in(MemNode::ValueIn); 980 } 981 982 intptr_t offset = 0; // scratch 983 984 // A load from a freshly-created object always returns zero. 985 // (This can happen after LoadNode::Ideal resets the load's memory input 986 // to find_captured_store, which returned InitializeNode::zero_memory.) 987 if (st->is_Proj() && st->in(0)->is_Allocate() && 988 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) && 989 offset >= st->in(0)->as_Allocate()->minimum_header_size()) { 990 // return a zero value for the load's basic type 991 // (This is one of the few places where a generic PhaseTransform 992 // can create new nodes. Think of it as lazily manifesting 993 // virtually pre-existing constants.) 994 return phase->zerocon(memory_type()); 995 } 996 997 // A load from an initialization barrier can match a captured store. 998 if (st->is_Proj() && st->in(0)->is_Initialize()) { 999 InitializeNode* init = st->in(0)->as_Initialize(); 1000 AllocateNode* alloc = init->allocation(); 1001 if (alloc != NULL && 1002 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) { 1003 // examine a captured store value 1004 st = init->find_captured_store(offset, memory_size(), phase); 1005 if (st != NULL) 1006 continue; // take one more trip around 1007 } 1008 } 1009 1010 break; 1011 } 1012 1013 return NULL; 1014 } 1015 1016 //----------------------is_instance_field_load_with_local_phi------------------ 1017 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1018 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl && 1019 in(MemNode::Address)->is_AddP() ) { 1020 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr(); 1021 // Only instances. 1022 if( t_oop != NULL && t_oop->is_known_instance_field() && 1023 t_oop->offset() != Type::OffsetBot && 1024 t_oop->offset() != Type::OffsetTop) { 1025 return true; 1026 } 1027 } 1028 return false; 1029 } 1030 1031 //------------------------------Identity--------------------------------------- 1032 // Loads are identity if previous store is to same address 1033 Node *LoadNode::Identity( PhaseTransform *phase ) { 1034 // If the previous store-maker is the right kind of Store, and the store is 1035 // to the same address, then we are equal to the value stored. 1036 Node* mem = in(MemNode::Memory); 1037 Node* value = can_see_stored_value(mem, phase); 1038 if( value ) { 1039 // byte, short & char stores truncate naturally. 1040 // A load has to load the truncated value which requires 1041 // some sort of masking operation and that requires an 1042 // Ideal call instead of an Identity call. 1043 if (memory_size() < BytesPerInt) { 1044 // If the input to the store does not fit with the load's result type, 1045 // it must be truncated via an Ideal call. 1046 if (!phase->type(value)->higher_equal(phase->type(this))) 1047 return this; 1048 } 1049 // (This works even when value is a Con, but LoadNode::Value 1050 // usually runs first, producing the singleton type of the Con.) 1051 return value; 1052 } 1053 1054 // Search for an existing data phi which was generated before for the same 1055 // instance's field to avoid infinite generation of phis in a loop. 1056 Node *region = mem->in(0); 1057 if (is_instance_field_load_with_local_phi(region)) { 1058 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr(); 1059 int this_index = phase->C->get_alias_index(addr_t); 1060 int this_offset = addr_t->offset(); 1061 int this_id = addr_t->is_oopptr()->instance_id(); 1062 const Type* this_type = bottom_type(); 1063 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1064 Node* phi = region->fast_out(i); 1065 if (phi->is_Phi() && phi != mem && 1066 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) { 1067 return phi; 1068 } 1069 } 1070 } 1071 1072 return this; 1073 } 1074 1075 1076 // Returns true if the AliasType refers to the field that holds the 1077 // cached box array. Currently only handles the IntegerCache case. 1078 static bool is_autobox_cache(Compile::AliasType* atp) { 1079 if (atp != NULL && atp->field() != NULL) { 1080 ciField* field = atp->field(); 1081 ciSymbol* klass = field->holder()->name(); 1082 if (field->name() == ciSymbol::cache_field_name() && 1083 field->holder()->uses_default_loader() && 1084 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 1085 return true; 1086 } 1087 } 1088 return false; 1089 } 1090 1091 // Fetch the base value in the autobox array 1092 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) { 1093 if (atp != NULL && atp->field() != NULL) { 1094 ciField* field = atp->field(); 1095 ciSymbol* klass = field->holder()->name(); 1096 if (field->name() == ciSymbol::cache_field_name() && 1097 field->holder()->uses_default_loader() && 1098 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 1099 assert(field->is_constant(), "what?"); 1100 ciObjArray* array = field->constant_value().as_object()->as_obj_array(); 1101 // Fetch the box object at the base of the array and get its value 1102 ciInstance* box = array->obj_at(0)->as_instance(); 1103 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1104 if (ik->nof_nonstatic_fields() == 1) { 1105 // This should be true nonstatic_field_at requires calling 1106 // nof_nonstatic_fields so check it anyway 1107 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1108 cache_offset = c.as_int(); 1109 } 1110 return true; 1111 } 1112 } 1113 return false; 1114 } 1115 1116 // Returns true if the AliasType refers to the value field of an 1117 // autobox object. Currently only handles Integer. 1118 static bool is_autobox_object(Compile::AliasType* atp) { 1119 if (atp != NULL && atp->field() != NULL) { 1120 ciField* field = atp->field(); 1121 ciSymbol* klass = field->holder()->name(); 1122 if (field->name() == ciSymbol::value_name() && 1123 field->holder()->uses_default_loader() && 1124 klass == ciSymbol::java_lang_Integer()) { 1125 return true; 1126 } 1127 } 1128 return false; 1129 } 1130 1131 1132 // We're loading from an object which has autobox behaviour. 1133 // If this object is result of a valueOf call we'll have a phi 1134 // merging a newly allocated object and a load from the cache. 1135 // We want to replace this load with the original incoming 1136 // argument to the valueOf call. 1137 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1138 Node* base = in(Address)->in(AddPNode::Base); 1139 if (base->is_Phi() && base->req() == 3) { 1140 AllocateNode* allocation = NULL; 1141 int allocation_index = -1; 1142 int load_index = -1; 1143 for (uint i = 1; i < base->req(); i++) { 1144 allocation = AllocateNode::Ideal_allocation(base->in(i), phase); 1145 if (allocation != NULL) { 1146 allocation_index = i; 1147 load_index = 3 - allocation_index; 1148 break; 1149 } 1150 } 1151 bool has_load = ( allocation != NULL && 1152 (base->in(load_index)->is_Load() || 1153 base->in(load_index)->is_DecodeN() && 1154 base->in(load_index)->in(1)->is_Load()) ); 1155 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) { 1156 // Push the loads from the phi that comes from valueOf up 1157 // through it to allow elimination of the loads and the recovery 1158 // of the original value. 1159 Node* mem_phi = in(Memory); 1160 Node* offset = in(Address)->in(AddPNode::Offset); 1161 Node* region = base->in(0); 1162 1163 Node* in1 = clone(); 1164 Node* in1_addr = in1->in(Address)->clone(); 1165 in1_addr->set_req(AddPNode::Base, base->in(allocation_index)); 1166 in1_addr->set_req(AddPNode::Address, base->in(allocation_index)); 1167 in1_addr->set_req(AddPNode::Offset, offset); 1168 in1->set_req(0, region->in(allocation_index)); 1169 in1->set_req(Address, in1_addr); 1170 in1->set_req(Memory, mem_phi->in(allocation_index)); 1171 1172 Node* in2 = clone(); 1173 Node* in2_addr = in2->in(Address)->clone(); 1174 in2_addr->set_req(AddPNode::Base, base->in(load_index)); 1175 in2_addr->set_req(AddPNode::Address, base->in(load_index)); 1176 in2_addr->set_req(AddPNode::Offset, offset); 1177 in2->set_req(0, region->in(load_index)); 1178 in2->set_req(Address, in2_addr); 1179 in2->set_req(Memory, mem_phi->in(load_index)); 1180 1181 in1_addr = phase->transform(in1_addr); 1182 in1 = phase->transform(in1); 1183 in2_addr = phase->transform(in2_addr); 1184 in2 = phase->transform(in2); 1185 1186 PhiNode* result = PhiNode::make_blank(region, this); 1187 result->set_req(allocation_index, in1); 1188 result->set_req(load_index, in2); 1189 return result; 1190 } 1191 } else if (base->is_Load() || 1192 base->is_DecodeN() && base->in(1)->is_Load()) { 1193 if (base->is_DecodeN()) { 1194 // Get LoadN node which loads cached Integer object 1195 base = base->in(1); 1196 } 1197 // Eliminate the load of Integer.value for integers from the cache 1198 // array by deriving the value from the index into the array. 1199 // Capture the offset of the load and then reverse the computation. 1200 Node* load_base = base->in(Address)->in(AddPNode::Base); 1201 if (load_base->is_DecodeN()) { 1202 // Get LoadN node which loads IntegerCache.cache field 1203 load_base = load_base->in(1); 1204 } 1205 if (load_base != NULL) { 1206 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type()); 1207 intptr_t cache_offset; 1208 int shift = -1; 1209 Node* cache = NULL; 1210 if (is_autobox_cache(atp)) { 1211 shift = exact_log2(type2aelembytes(T_OBJECT)); 1212 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset); 1213 } 1214 if (cache != NULL && base->in(Address)->is_AddP()) { 1215 Node* elements[4]; 1216 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements)); 1217 int cache_low; 1218 if (count > 0 && fetch_autobox_base(atp, cache_low)) { 1219 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift); 1220 // Add up all the offsets making of the address of the load 1221 Node* result = elements[0]; 1222 for (int i = 1; i < count; i++) { 1223 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i])); 1224 } 1225 // Remove the constant offset from the address and then 1226 // remove the scaling of the offset to recover the original index. 1227 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset))); 1228 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1229 // Peel the shift off directly but wrap it in a dummy node 1230 // since Ideal can't return existing nodes 1231 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0)); 1232 } else { 1233 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift)); 1234 } 1235 #ifdef _LP64 1236 result = new (phase->C, 2) ConvL2INode(phase->transform(result)); 1237 #endif 1238 return result; 1239 } 1240 } 1241 } 1242 } 1243 return NULL; 1244 } 1245 1246 //------------------------------split_through_phi------------------------------ 1247 // Split instance field load through Phi. 1248 Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1249 Node* mem = in(MemNode::Memory); 1250 Node* address = in(MemNode::Address); 1251 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1252 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1253 1254 assert(mem->is_Phi() && (t_oop != NULL) && 1255 t_oop->is_known_instance_field(), "invalide conditions"); 1256 1257 Node *region = mem->in(0); 1258 if (region == NULL) { 1259 return NULL; // Wait stable graph 1260 } 1261 uint cnt = mem->req(); 1262 for (uint i = 1; i < cnt; i++) { 1263 Node* rc = region->in(i); 1264 if (rc == NULL || phase->type(rc) == Type::TOP) 1265 return NULL; // Wait stable graph 1266 Node *in = mem->in(i); 1267 if (in == NULL) { 1268 return NULL; // Wait stable graph 1269 } 1270 } 1271 // Check for loop invariant. 1272 if (cnt == 3) { 1273 for (uint i = 1; i < cnt; i++) { 1274 Node *in = mem->in(i); 1275 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase); 1276 if (m == mem) { 1277 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi. 1278 return this; 1279 } 1280 } 1281 } 1282 // Split through Phi (see original code in loopopts.cpp). 1283 assert(phase->C->have_alias_type(addr_t), "instance should have alias type"); 1284 1285 // Do nothing here if Identity will find a value 1286 // (to avoid infinite chain of value phis generation). 1287 if (!phase->eqv(this, this->Identity(phase))) 1288 return NULL; 1289 1290 // Skip the split if the region dominates some control edge of the address. 1291 if (!MemNode::all_controls_dominate(address, region)) 1292 return NULL; 1293 1294 const Type* this_type = this->bottom_type(); 1295 int this_index = phase->C->get_alias_index(addr_t); 1296 int this_offset = addr_t->offset(); 1297 int this_iid = addr_t->is_oopptr()->instance_id(); 1298 PhaseIterGVN *igvn = phase->is_IterGVN(); 1299 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset); 1300 for (uint i = 1; i < region->req(); i++) { 1301 Node *x; 1302 Node* the_clone = NULL; 1303 if (region->in(i) == phase->C->top()) { 1304 x = phase->C->top(); // Dead path? Use a dead data op 1305 } else { 1306 x = this->clone(); // Else clone up the data op 1307 the_clone = x; // Remember for possible deletion. 1308 // Alter data node to use pre-phi inputs 1309 if (this->in(0) == region) { 1310 x->set_req(0, region->in(i)); 1311 } else { 1312 x->set_req(0, NULL); 1313 } 1314 for (uint j = 1; j < this->req(); j++) { 1315 Node *in = this->in(j); 1316 if (in->is_Phi() && in->in(0) == region) 1317 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone 1318 } 1319 } 1320 // Check for a 'win' on some paths 1321 const Type *t = x->Value(igvn); 1322 1323 bool singleton = t->singleton(); 1324 1325 // See comments in PhaseIdealLoop::split_thru_phi(). 1326 if (singleton && t == Type::TOP) { 1327 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1328 } 1329 1330 if (singleton) { 1331 x = igvn->makecon(t); 1332 } else { 1333 // We now call Identity to try to simplify the cloned node. 1334 // Note that some Identity methods call phase->type(this). 1335 // Make sure that the type array is big enough for 1336 // our new node, even though we may throw the node away. 1337 // (This tweaking with igvn only works because x is a new node.) 1338 igvn->set_type(x, t); 1339 // If x is a TypeNode, capture any more-precise type permanently into Node 1340 // otherwise it will be not updated during igvn->transform since 1341 // igvn->type(x) is set to x->Value() already. 1342 x->raise_bottom_type(t); 1343 Node *y = x->Identity(igvn); 1344 if (y != x) { 1345 x = y; 1346 } else { 1347 y = igvn->hash_find(x); 1348 if (y) { 1349 x = y; 1350 } else { 1351 // Else x is a new node we are keeping 1352 // We do not need register_new_node_with_optimizer 1353 // because set_type has already been called. 1354 igvn->_worklist.push(x); 1355 } 1356 } 1357 } 1358 if (x != the_clone && the_clone != NULL) 1359 igvn->remove_dead_node(the_clone); 1360 phi->set_req(i, x); 1361 } 1362 // Record Phi 1363 igvn->register_new_node_with_optimizer(phi); 1364 return phi; 1365 } 1366 1367 //------------------------------Ideal------------------------------------------ 1368 // If the load is from Field memory and the pointer is non-null, we can 1369 // zero out the control input. 1370 // If the offset is constant and the base is an object allocation, 1371 // try to hook me up to the exact initializing store. 1372 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1373 Node* p = MemNode::Ideal_common(phase, can_reshape); 1374 if (p) return (p == NodeSentinel) ? NULL : p; 1375 1376 Node* ctrl = in(MemNode::Control); 1377 Node* address = in(MemNode::Address); 1378 1379 // Skip up past a SafePoint control. Cannot do this for Stores because 1380 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1381 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1382 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1383 ctrl = ctrl->in(0); 1384 set_req(MemNode::Control,ctrl); 1385 } 1386 1387 intptr_t ignore = 0; 1388 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1389 if (base != NULL 1390 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1391 // Check for useless control edge in some common special cases 1392 if (in(MemNode::Control) != NULL 1393 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1394 && all_controls_dominate(base, phase->C->start())) { 1395 // A method-invariant, non-null address (constant or 'this' argument). 1396 set_req(MemNode::Control, NULL); 1397 } 1398 1399 if (EliminateAutoBox && can_reshape) { 1400 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null"); 1401 Compile::AliasType* atp = phase->C->alias_type(adr_type()); 1402 if (is_autobox_object(atp)) { 1403 Node* result = eliminate_autobox(phase); 1404 if (result != NULL) return result; 1405 } 1406 } 1407 } 1408 1409 Node* mem = in(MemNode::Memory); 1410 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1411 1412 if (addr_t != NULL) { 1413 // try to optimize our memory input 1414 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase); 1415 if (opt_mem != mem) { 1416 set_req(MemNode::Memory, opt_mem); 1417 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1418 return this; 1419 } 1420 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1421 if (can_reshape && opt_mem->is_Phi() && 1422 (t_oop != NULL) && t_oop->is_known_instance_field()) { 1423 // Split instance field load through Phi. 1424 Node* result = split_through_phi(phase); 1425 if (result != NULL) return result; 1426 } 1427 } 1428 1429 // Check for prior store with a different base or offset; make Load 1430 // independent. Skip through any number of them. Bail out if the stores 1431 // are in an endless dead cycle and report no progress. This is a key 1432 // transform for Reflection. However, if after skipping through the Stores 1433 // we can't then fold up against a prior store do NOT do the transform as 1434 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1435 // array memory alive twice: once for the hoisted Load and again after the 1436 // bypassed Store. This situation only works if EVERYBODY who does 1437 // anti-dependence work knows how to bypass. I.e. we need all 1438 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1439 // the alias index stuff. So instead, peek through Stores and IFF we can 1440 // fold up, do so. 1441 Node* prev_mem = find_previous_store(phase); 1442 // Steps (a), (b): Walk past independent stores to find an exact match. 1443 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1444 // (c) See if we can fold up on the spot, but don't fold up here. 1445 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1446 // just return a prior value, which is done by Identity calls. 1447 if (can_see_stored_value(prev_mem, phase)) { 1448 // Make ready for step (d): 1449 set_req(MemNode::Memory, prev_mem); 1450 return this; 1451 } 1452 } 1453 1454 return NULL; // No further progress 1455 } 1456 1457 // Helper to recognize certain Klass fields which are invariant across 1458 // some group of array types (e.g., int[] or all T[] where T < Object). 1459 const Type* 1460 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1461 ciKlass* klass) const { 1462 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { 1463 // The field is Klass::_modifier_flags. Return its (constant) value. 1464 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1465 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1466 return TypeInt::make(klass->modifier_flags()); 1467 } 1468 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { 1469 // The field is Klass::_access_flags. Return its (constant) value. 1470 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1471 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1472 return TypeInt::make(klass->access_flags()); 1473 } 1474 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) { 1475 // The field is Klass::_layout_helper. Return its constant value if known. 1476 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1477 return TypeInt::make(klass->layout_helper()); 1478 } 1479 1480 // No match. 1481 return NULL; 1482 } 1483 1484 //------------------------------Value----------------------------------------- 1485 const Type *LoadNode::Value( PhaseTransform *phase ) const { 1486 // Either input is TOP ==> the result is TOP 1487 Node* mem = in(MemNode::Memory); 1488 const Type *t1 = phase->type(mem); 1489 if (t1 == Type::TOP) return Type::TOP; 1490 Node* adr = in(MemNode::Address); 1491 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1492 if (tp == NULL || tp->empty()) return Type::TOP; 1493 int off = tp->offset(); 1494 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1495 1496 // Try to guess loaded type from pointer type 1497 if (tp->base() == Type::AryPtr) { 1498 const Type *t = tp->is_aryptr()->elem(); 1499 // Don't do this for integer types. There is only potential profit if 1500 // the element type t is lower than _type; that is, for int types, if _type is 1501 // more restrictive than t. This only happens here if one is short and the other 1502 // char (both 16 bits), and in those cases we've made an intentional decision 1503 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1504 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1505 // 1506 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1507 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1508 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1509 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1510 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1511 // In fact, that could have been the original type of p1, and p1 could have 1512 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1513 // expression (LShiftL quux 3) independently optimized to the constant 8. 1514 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1515 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1516 // t might actually be lower than _type, if _type is a unique 1517 // concrete subclass of abstract class t. 1518 // Make sure the reference is not into the header, by comparing 1519 // the offset against the offset of the start of the array's data. 1520 // Different array types begin at slightly different offsets (12 vs. 16). 1521 // We choose T_BYTE as an example base type that is least restrictive 1522 // as to alignment, which will therefore produce the smallest 1523 // possible base offset. 1524 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1525 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header? 1526 const Type* jt = t->join(_type); 1527 // In any case, do not allow the join, per se, to empty out the type. 1528 if (jt->empty() && !t->empty()) { 1529 // This can happen if a interface-typed array narrows to a class type. 1530 jt = _type; 1531 } 1532 1533 if (EliminateAutoBox && adr->is_AddP()) { 1534 // The pointers in the autobox arrays are always non-null 1535 Node* base = adr->in(AddPNode::Base); 1536 if (base != NULL && 1537 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) { 1538 Compile::AliasType* atp = phase->C->alias_type(base->adr_type()); 1539 if (is_autobox_cache(atp)) { 1540 return jt->join(TypePtr::NOTNULL)->is_ptr(); 1541 } 1542 } 1543 } 1544 return jt; 1545 } 1546 } 1547 } else if (tp->base() == Type::InstPtr) { 1548 const TypeInstPtr* tinst = tp->is_instptr(); 1549 ciKlass* klass = tinst->klass(); 1550 assert( off != Type::OffsetBot || 1551 // arrays can be cast to Objects 1552 tp->is_oopptr()->klass()->is_java_lang_Object() || 1553 // unsafe field access may not have a constant offset 1554 phase->C->has_unsafe_access(), 1555 "Field accesses must be precise" ); 1556 // For oop loads, we expect the _type to be precise 1557 if (klass == phase->C->env()->String_klass() && 1558 adr->is_AddP() && off != Type::OffsetBot) { 1559 // For constant Strings treat the final fields as compile time constants. 1560 Node* base = adr->in(AddPNode::Base); 1561 const TypeOopPtr* t = phase->type(base)->isa_oopptr(); 1562 if (t != NULL && t->singleton()) { 1563 ciField* field = phase->C->env()->String_klass()->get_field_by_offset(off, false); 1564 if (field != NULL && field->is_final()) { 1565 ciObject* string = t->const_oop(); 1566 ciConstant constant = string->as_instance()->field_value(field); 1567 if (constant.basic_type() == T_INT) { 1568 return TypeInt::make(constant.as_int()); 1569 } else if (constant.basic_type() == T_ARRAY) { 1570 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1571 return TypeNarrowOop::make_from_constant(constant.as_object(), true); 1572 } else { 1573 return TypeOopPtr::make_from_constant(constant.as_object(), true); 1574 } 1575 } 1576 } 1577 } 1578 } 1579 } else if (tp->base() == Type::KlassPtr) { 1580 assert( off != Type::OffsetBot || 1581 // arrays can be cast to Objects 1582 tp->is_klassptr()->klass()->is_java_lang_Object() || 1583 // also allow array-loading from the primary supertype 1584 // array during subtype checks 1585 Opcode() == Op_LoadKlass, 1586 "Field accesses must be precise" ); 1587 // For klass/static loads, we expect the _type to be precise 1588 } 1589 1590 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1591 if (tkls != NULL && !StressReflectiveCode) { 1592 ciKlass* klass = tkls->klass(); 1593 if (klass->is_loaded() && tkls->klass_is_exact()) { 1594 // We are loading a field from a Klass metaobject whose identity 1595 // is known at compile time (the type is "exact" or "precise"). 1596 // Check for fields we know are maintained as constants by the VM. 1597 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) { 1598 // The field is Klass::_super_check_offset. Return its (constant) value. 1599 // (Folds up type checking code.) 1600 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1601 return TypeInt::make(klass->super_check_offset()); 1602 } 1603 // Compute index into primary_supers array 1604 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); 1605 // Check for overflowing; use unsigned compare to handle the negative case. 1606 if( depth < ciKlass::primary_super_limit() ) { 1607 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1608 // (Folds up type checking code.) 1609 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1610 ciKlass *ss = klass->super_of_depth(depth); 1611 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1612 } 1613 const Type* aift = load_array_final_field(tkls, klass); 1614 if (aift != NULL) return aift; 1615 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc) 1616 && klass->is_array_klass()) { 1617 // The field is arrayKlass::_component_mirror. Return its (constant) value. 1618 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.) 1619 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror"); 1620 return TypeInstPtr::make(klass->as_array_klass()->component_mirror()); 1621 } 1622 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) { 1623 // The field is Klass::_java_mirror. Return its (constant) value. 1624 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1625 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1626 return TypeInstPtr::make(klass->java_mirror()); 1627 } 1628 } 1629 1630 // We can still check if we are loading from the primary_supers array at a 1631 // shallow enough depth. Even though the klass is not exact, entries less 1632 // than or equal to its super depth are correct. 1633 if (klass->is_loaded() ) { 1634 ciType *inner = klass->klass(); 1635 while( inner->is_obj_array_klass() ) 1636 inner = inner->as_obj_array_klass()->base_element_type(); 1637 if( inner->is_instance_klass() && 1638 !inner->as_instance_klass()->flags().is_interface() ) { 1639 // Compute index into primary_supers array 1640 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); 1641 // Check for overflowing; use unsigned compare to handle the negative case. 1642 if( depth < ciKlass::primary_super_limit() && 1643 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1644 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1645 // (Folds up type checking code.) 1646 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1647 ciKlass *ss = klass->super_of_depth(depth); 1648 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1649 } 1650 } 1651 } 1652 1653 // If the type is enough to determine that the thing is not an array, 1654 // we can give the layout_helper a positive interval type. 1655 // This will help short-circuit some reflective code. 1656 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc) 1657 && !klass->is_array_klass() // not directly typed as an array 1658 && !klass->is_interface() // specifically not Serializable & Cloneable 1659 && !klass->is_java_lang_Object() // not the supertype of all T[] 1660 ) { 1661 // Note: When interfaces are reliable, we can narrow the interface 1662 // test to (klass != Serializable && klass != Cloneable). 1663 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1664 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1665 // The key property of this type is that it folds up tests 1666 // for array-ness, since it proves that the layout_helper is positive. 1667 // Thus, a generic value like the basic object layout helper works fine. 1668 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1669 } 1670 } 1671 1672 // If we are loading from a freshly-allocated object, produce a zero, 1673 // if the load is provably beyond the header of the object. 1674 // (Also allow a variable load from a fresh array to produce zero.) 1675 const TypeOopPtr *tinst = tp->isa_oopptr(); 1676 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1677 if (ReduceFieldZeroing || is_instance) { 1678 Node* value = can_see_stored_value(mem,phase); 1679 if (value != NULL && value->is_Con()) 1680 return value->bottom_type(); 1681 } 1682 1683 if (is_instance) { 1684 // If we have an instance type and our memory input is the 1685 // programs's initial memory state, there is no matching store, 1686 // so just return a zero of the appropriate type 1687 Node *mem = in(MemNode::Memory); 1688 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1689 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1690 return Type::get_zero_type(_type->basic_type()); 1691 } 1692 } 1693 return _type; 1694 } 1695 1696 //------------------------------match_edge------------------------------------- 1697 // Do we Match on this edge index or not? Match only the address. 1698 uint LoadNode::match_edge(uint idx) const { 1699 return idx == MemNode::Address; 1700 } 1701 1702 //--------------------------LoadBNode::Ideal-------------------------------------- 1703 // 1704 // If the previous store is to the same address as this load, 1705 // and the value stored was larger than a byte, replace this load 1706 // with the value stored truncated to a byte. If no truncation is 1707 // needed, the replacement is done in LoadNode::Identity(). 1708 // 1709 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1710 Node* mem = in(MemNode::Memory); 1711 Node* value = can_see_stored_value(mem,phase); 1712 if( value && !phase->type(value)->higher_equal( _type ) ) { 1713 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) ); 1714 return new (phase->C, 3) RShiftINode(result, phase->intcon(24)); 1715 } 1716 // Identity call will handle the case where truncation is not needed. 1717 return LoadNode::Ideal(phase, can_reshape); 1718 } 1719 1720 //--------------------------LoadUBNode::Ideal------------------------------------- 1721 // 1722 // If the previous store is to the same address as this load, 1723 // and the value stored was larger than a byte, replace this load 1724 // with the value stored truncated to a byte. If no truncation is 1725 // needed, the replacement is done in LoadNode::Identity(). 1726 // 1727 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 1728 Node* mem = in(MemNode::Memory); 1729 Node* value = can_see_stored_value(mem, phase); 1730 if (value && !phase->type(value)->higher_equal(_type)) 1731 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF)); 1732 // Identity call will handle the case where truncation is not needed. 1733 return LoadNode::Ideal(phase, can_reshape); 1734 } 1735 1736 //--------------------------LoadUSNode::Ideal------------------------------------- 1737 // 1738 // If the previous store is to the same address as this load, 1739 // and the value stored was larger than a char, replace this load 1740 // with the value stored truncated to a char. If no truncation is 1741 // needed, the replacement is done in LoadNode::Identity(). 1742 // 1743 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1744 Node* mem = in(MemNode::Memory); 1745 Node* value = can_see_stored_value(mem,phase); 1746 if( value && !phase->type(value)->higher_equal( _type ) ) 1747 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF)); 1748 // Identity call will handle the case where truncation is not needed. 1749 return LoadNode::Ideal(phase, can_reshape); 1750 } 1751 1752 //--------------------------LoadSNode::Ideal-------------------------------------- 1753 // 1754 // If the previous store is to the same address as this load, 1755 // and the value stored was larger than a short, replace this load 1756 // with the value stored truncated to a short. If no truncation is 1757 // needed, the replacement is done in LoadNode::Identity(). 1758 // 1759 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1760 Node* mem = in(MemNode::Memory); 1761 Node* value = can_see_stored_value(mem,phase); 1762 if( value && !phase->type(value)->higher_equal( _type ) ) { 1763 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) ); 1764 return new (phase->C, 3) RShiftINode(result, phase->intcon(16)); 1765 } 1766 // Identity call will handle the case where truncation is not needed. 1767 return LoadNode::Ideal(phase, can_reshape); 1768 } 1769 1770 //============================================================================= 1771 //----------------------------LoadKlassNode::make------------------------------ 1772 // Polymorphic factory method: 1773 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) { 1774 Compile* C = gvn.C; 1775 Node *ctl = NULL; 1776 // sanity check the alias category against the created node type 1777 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr(); 1778 assert(adr_type != NULL, "expecting TypeOopPtr"); 1779 #ifdef _LP64 1780 if (adr_type->is_ptr_to_narrowoop()) { 1781 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop())); 1782 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr()); 1783 } 1784 #endif 1785 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 1786 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk); 1787 } 1788 1789 //------------------------------Value------------------------------------------ 1790 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { 1791 return klass_value_common(phase); 1792 } 1793 1794 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const { 1795 // Either input is TOP ==> the result is TOP 1796 const Type *t1 = phase->type( in(MemNode::Memory) ); 1797 if (t1 == Type::TOP) return Type::TOP; 1798 Node *adr = in(MemNode::Address); 1799 const Type *t2 = phase->type( adr ); 1800 if (t2 == Type::TOP) return Type::TOP; 1801 const TypePtr *tp = t2->is_ptr(); 1802 if (TypePtr::above_centerline(tp->ptr()) || 1803 tp->ptr() == TypePtr::Null) return Type::TOP; 1804 1805 // Return a more precise klass, if possible 1806 const TypeInstPtr *tinst = tp->isa_instptr(); 1807 if (tinst != NULL) { 1808 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 1809 int offset = tinst->offset(); 1810 if (ik == phase->C->env()->Class_klass() 1811 && (offset == java_lang_Class::klass_offset_in_bytes() || 1812 offset == java_lang_Class::array_klass_offset_in_bytes())) { 1813 // We are loading a special hidden field from a Class mirror object, 1814 // the field which points to the VM's Klass metaobject. 1815 ciType* t = tinst->java_mirror_type(); 1816 // java_mirror_type returns non-null for compile-time Class constants. 1817 if (t != NULL) { 1818 // constant oop => constant klass 1819 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 1820 return TypeKlassPtr::make(ciArrayKlass::make(t)); 1821 } 1822 if (!t->is_klass()) { 1823 // a primitive Class (e.g., int.class) has NULL for a klass field 1824 return TypePtr::NULL_PTR; 1825 } 1826 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 1827 return TypeKlassPtr::make(t->as_klass()); 1828 } 1829 // non-constant mirror, so we can't tell what's going on 1830 } 1831 if( !ik->is_loaded() ) 1832 return _type; // Bail out if not loaded 1833 if (offset == oopDesc::klass_offset_in_bytes()) { 1834 if (tinst->klass_is_exact()) { 1835 return TypeKlassPtr::make(ik); 1836 } 1837 // See if we can become precise: no subklasses and no interface 1838 // (Note: We need to support verified interfaces.) 1839 if (!ik->is_interface() && !ik->has_subklass()) { 1840 //assert(!UseExactTypes, "this code should be useless with exact types"); 1841 // Add a dependence; if any subclass added we need to recompile 1842 if (!ik->is_final()) { 1843 // %%% should use stronger assert_unique_concrete_subtype instead 1844 phase->C->dependencies()->assert_leaf_type(ik); 1845 } 1846 // Return precise klass 1847 return TypeKlassPtr::make(ik); 1848 } 1849 1850 // Return root of possible klass 1851 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 1852 } 1853 } 1854 1855 // Check for loading klass from an array 1856 const TypeAryPtr *tary = tp->isa_aryptr(); 1857 if( tary != NULL ) { 1858 ciKlass *tary_klass = tary->klass(); 1859 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 1860 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 1861 if (tary->klass_is_exact()) { 1862 return TypeKlassPtr::make(tary_klass); 1863 } 1864 ciArrayKlass *ak = tary->klass()->as_array_klass(); 1865 // If the klass is an object array, we defer the question to the 1866 // array component klass. 1867 if( ak->is_obj_array_klass() ) { 1868 assert( ak->is_loaded(), "" ); 1869 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 1870 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 1871 ciInstanceKlass* ik = base_k->as_instance_klass(); 1872 // See if we can become precise: no subklasses and no interface 1873 if (!ik->is_interface() && !ik->has_subklass()) { 1874 //assert(!UseExactTypes, "this code should be useless with exact types"); 1875 // Add a dependence; if any subclass added we need to recompile 1876 if (!ik->is_final()) { 1877 phase->C->dependencies()->assert_leaf_type(ik); 1878 } 1879 // Return precise array klass 1880 return TypeKlassPtr::make(ak); 1881 } 1882 } 1883 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 1884 } else { // Found a type-array? 1885 //assert(!UseExactTypes, "this code should be useless with exact types"); 1886 assert( ak->is_type_array_klass(), "" ); 1887 return TypeKlassPtr::make(ak); // These are always precise 1888 } 1889 } 1890 } 1891 1892 // Check for loading klass from an array klass 1893 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1894 if (tkls != NULL && !StressReflectiveCode) { 1895 ciKlass* klass = tkls->klass(); 1896 if( !klass->is_loaded() ) 1897 return _type; // Bail out if not loaded 1898 if( klass->is_obj_array_klass() && 1899 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) { 1900 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 1901 // // Always returning precise element type is incorrect, 1902 // // e.g., element type could be object and array may contain strings 1903 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 1904 1905 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 1906 // according to the element type's subclassing. 1907 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 1908 } 1909 if( klass->is_instance_klass() && tkls->klass_is_exact() && 1910 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) { 1911 ciKlass* sup = klass->as_instance_klass()->super(); 1912 // The field is Klass::_super. Return its (constant) value. 1913 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 1914 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 1915 } 1916 } 1917 1918 // Bailout case 1919 return LoadNode::Value(phase); 1920 } 1921 1922 //------------------------------Identity--------------------------------------- 1923 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 1924 // Also feed through the klass in Allocate(...klass...)._klass. 1925 Node* LoadKlassNode::Identity( PhaseTransform *phase ) { 1926 return klass_identity_common(phase); 1927 } 1928 1929 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) { 1930 Node* x = LoadNode::Identity(phase); 1931 if (x != this) return x; 1932 1933 // Take apart the address into an oop and and offset. 1934 // Return 'this' if we cannot. 1935 Node* adr = in(MemNode::Address); 1936 intptr_t offset = 0; 1937 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 1938 if (base == NULL) return this; 1939 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 1940 if (toop == NULL) return this; 1941 1942 // We can fetch the klass directly through an AllocateNode. 1943 // This works even if the klass is not constant (clone or newArray). 1944 if (offset == oopDesc::klass_offset_in_bytes()) { 1945 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 1946 if (allocated_klass != NULL) { 1947 return allocated_klass; 1948 } 1949 } 1950 1951 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop. 1952 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass. 1953 // See inline_native_Class_query for occurrences of these patterns. 1954 // Java Example: x.getClass().isAssignableFrom(y) 1955 // Java Example: Array.newInstance(x.getClass().getComponentType(), n) 1956 // 1957 // This improves reflective code, often making the Class 1958 // mirror go completely dead. (Current exception: Class 1959 // mirrors may appear in debug info, but we could clean them out by 1960 // introducing a new debug info operator for klassOop.java_mirror). 1961 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 1962 && (offset == java_lang_Class::klass_offset_in_bytes() || 1963 offset == java_lang_Class::array_klass_offset_in_bytes())) { 1964 // We are loading a special hidden field from a Class mirror, 1965 // the field which points to its Klass or arrayKlass metaobject. 1966 if (base->is_Load()) { 1967 Node* adr2 = base->in(MemNode::Address); 1968 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 1969 if (tkls != NULL && !tkls->empty() 1970 && (tkls->klass()->is_instance_klass() || 1971 tkls->klass()->is_array_klass()) 1972 && adr2->is_AddP() 1973 ) { 1974 int mirror_field = Klass::java_mirror_offset_in_bytes(); 1975 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 1976 mirror_field = in_bytes(arrayKlass::component_mirror_offset()); 1977 } 1978 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) { 1979 return adr2->in(AddPNode::Base); 1980 } 1981 } 1982 } 1983 } 1984 1985 return this; 1986 } 1987 1988 1989 //------------------------------Value------------------------------------------ 1990 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const { 1991 const Type *t = klass_value_common(phase); 1992 if (t == Type::TOP) 1993 return t; 1994 1995 return t->make_narrowoop(); 1996 } 1997 1998 //------------------------------Identity--------------------------------------- 1999 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2000 // Also feed through the klass in Allocate(...klass...)._klass. 2001 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) { 2002 Node *x = klass_identity_common(phase); 2003 2004 const Type *t = phase->type( x ); 2005 if( t == Type::TOP ) return x; 2006 if( t->isa_narrowoop()) return x; 2007 2008 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop())); 2009 } 2010 2011 //------------------------------Value----------------------------------------- 2012 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { 2013 // Either input is TOP ==> the result is TOP 2014 const Type *t1 = phase->type( in(MemNode::Memory) ); 2015 if( t1 == Type::TOP ) return Type::TOP; 2016 Node *adr = in(MemNode::Address); 2017 const Type *t2 = phase->type( adr ); 2018 if( t2 == Type::TOP ) return Type::TOP; 2019 const TypePtr *tp = t2->is_ptr(); 2020 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2021 const TypeAryPtr *tap = tp->isa_aryptr(); 2022 if( !tap ) return _type; 2023 return tap->size(); 2024 } 2025 2026 //-------------------------------Ideal--------------------------------------- 2027 // Feed through the length in AllocateArray(...length...)._length. 2028 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2029 Node* p = MemNode::Ideal_common(phase, can_reshape); 2030 if (p) return (p == NodeSentinel) ? NULL : p; 2031 2032 // Take apart the address into an oop and and offset. 2033 // Return 'this' if we cannot. 2034 Node* adr = in(MemNode::Address); 2035 intptr_t offset = 0; 2036 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2037 if (base == NULL) return NULL; 2038 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2039 if (tary == NULL) return NULL; 2040 2041 // We can fetch the length directly through an AllocateArrayNode. 2042 // This works even if the length is not constant (clone or newArray). 2043 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2044 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2045 if (alloc != NULL) { 2046 Node* allocated_length = alloc->Ideal_length(); 2047 Node* len = alloc->make_ideal_length(tary, phase); 2048 if (allocated_length != len) { 2049 // New CastII improves on this. 2050 return len; 2051 } 2052 } 2053 } 2054 2055 return NULL; 2056 } 2057 2058 //------------------------------Identity--------------------------------------- 2059 // Feed through the length in AllocateArray(...length...)._length. 2060 Node* LoadRangeNode::Identity( PhaseTransform *phase ) { 2061 Node* x = LoadINode::Identity(phase); 2062 if (x != this) return x; 2063 2064 // Take apart the address into an oop and and offset. 2065 // Return 'this' if we cannot. 2066 Node* adr = in(MemNode::Address); 2067 intptr_t offset = 0; 2068 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2069 if (base == NULL) return this; 2070 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2071 if (tary == NULL) return this; 2072 2073 // We can fetch the length directly through an AllocateArrayNode. 2074 // This works even if the length is not constant (clone or newArray). 2075 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2076 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2077 if (alloc != NULL) { 2078 Node* allocated_length = alloc->Ideal_length(); 2079 // Do not allow make_ideal_length to allocate a CastII node. 2080 Node* len = alloc->make_ideal_length(tary, phase, false); 2081 if (allocated_length == len) { 2082 // Return allocated_length only if it would not be improved by a CastII. 2083 return allocated_length; 2084 } 2085 } 2086 } 2087 2088 return this; 2089 2090 } 2091 2092 //============================================================================= 2093 //---------------------------StoreNode::make----------------------------------- 2094 // Polymorphic factory method: 2095 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) { 2096 Compile* C = gvn.C; 2097 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2098 ctl != NULL, "raw memory operations should have control edge"); 2099 2100 switch (bt) { 2101 case T_BOOLEAN: 2102 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val); 2103 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val); 2104 case T_CHAR: 2105 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val); 2106 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val); 2107 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val); 2108 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val); 2109 case T_ADDRESS: 2110 case T_OBJECT: 2111 #ifdef _LP64 2112 if (adr->bottom_type()->is_ptr_to_narrowoop() || 2113 (UseCompressedOops && val->bottom_type()->isa_klassptr() && 2114 adr->bottom_type()->isa_rawptr())) { 2115 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop())); 2116 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val); 2117 } else 2118 #endif 2119 { 2120 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val); 2121 } 2122 } 2123 ShouldNotReachHere(); 2124 return (StoreNode*)NULL; 2125 } 2126 2127 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) { 2128 bool require_atomic = true; 2129 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic); 2130 } 2131 2132 2133 //--------------------------bottom_type---------------------------------------- 2134 const Type *StoreNode::bottom_type() const { 2135 return Type::MEMORY; 2136 } 2137 2138 //------------------------------hash------------------------------------------- 2139 uint StoreNode::hash() const { 2140 // unroll addition of interesting fields 2141 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2142 2143 // Since they are not commoned, do not hash them: 2144 return NO_HASH; 2145 } 2146 2147 //------------------------------Ideal------------------------------------------ 2148 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2149 // When a store immediately follows a relevant allocation/initialization, 2150 // try to capture it into the initialization, or hoist it above. 2151 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2152 Node* p = MemNode::Ideal_common(phase, can_reshape); 2153 if (p) return (p == NodeSentinel) ? NULL : p; 2154 2155 Node* mem = in(MemNode::Memory); 2156 Node* address = in(MemNode::Address); 2157 2158 // Back-to-back stores to same address? Fold em up. Generally 2159 // unsafe if I have intervening uses... Also disallowed for StoreCM 2160 // since they must follow each StoreP operation. Redundant StoreCMs 2161 // are eliminated just before matching in final_graph_reshape. 2162 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address) && 2163 mem->Opcode() != Op_StoreCM) { 2164 // Looking at a dead closed cycle of memory? 2165 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2166 2167 assert(Opcode() == mem->Opcode() || 2168 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, 2169 "no mismatched stores, except on raw memory"); 2170 2171 if (mem->outcnt() == 1 && // check for intervening uses 2172 mem->as_Store()->memory_size() <= this->memory_size()) { 2173 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. 2174 // For example, 'mem' might be the final state at a conditional return. 2175 // Or, 'mem' might be used by some node which is live at the same time 2176 // 'this' is live, which might be unschedulable. So, require exactly 2177 // ONE user, the 'this' store, until such time as we clone 'mem' for 2178 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). 2179 if (can_reshape) { // (%%% is this an anachronism?) 2180 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), 2181 phase->is_IterGVN()); 2182 } else { 2183 // It's OK to do this in the parser, since DU info is always accurate, 2184 // and the parser always refers to nodes via SafePointNode maps. 2185 set_req(MemNode::Memory, mem->in(MemNode::Memory)); 2186 } 2187 return this; 2188 } 2189 } 2190 2191 // Capture an unaliased, unconditional, simple store into an initializer. 2192 // Or, if it is independent of the allocation, hoist it above the allocation. 2193 if (ReduceFieldZeroing && /*can_reshape &&*/ 2194 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2195 InitializeNode* init = mem->in(0)->as_Initialize(); 2196 intptr_t offset = init->can_capture_store(this, phase); 2197 if (offset > 0) { 2198 Node* moved = init->capture_store(this, offset, phase); 2199 // If the InitializeNode captured me, it made a raw copy of me, 2200 // and I need to disappear. 2201 if (moved != NULL) { 2202 // %%% hack to ensure that Ideal returns a new node: 2203 mem = MergeMemNode::make(phase->C, mem); 2204 return mem; // fold me away 2205 } 2206 } 2207 } 2208 2209 return NULL; // No further progress 2210 } 2211 2212 //------------------------------Value----------------------------------------- 2213 const Type *StoreNode::Value( PhaseTransform *phase ) const { 2214 // Either input is TOP ==> the result is TOP 2215 const Type *t1 = phase->type( in(MemNode::Memory) ); 2216 if( t1 == Type::TOP ) return Type::TOP; 2217 const Type *t2 = phase->type( in(MemNode::Address) ); 2218 if( t2 == Type::TOP ) return Type::TOP; 2219 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2220 if( t3 == Type::TOP ) return Type::TOP; 2221 return Type::MEMORY; 2222 } 2223 2224 //------------------------------Identity--------------------------------------- 2225 // Remove redundant stores: 2226 // Store(m, p, Load(m, p)) changes to m. 2227 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2228 Node *StoreNode::Identity( PhaseTransform *phase ) { 2229 Node* mem = in(MemNode::Memory); 2230 Node* adr = in(MemNode::Address); 2231 Node* val = in(MemNode::ValueIn); 2232 2233 // Load then Store? Then the Store is useless 2234 if (val->is_Load() && 2235 phase->eqv_uncast( val->in(MemNode::Address), adr ) && 2236 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) && 2237 val->as_Load()->store_Opcode() == Opcode()) { 2238 return mem; 2239 } 2240 2241 // Two stores in a row of the same value? 2242 if (mem->is_Store() && 2243 phase->eqv_uncast( mem->in(MemNode::Address), adr ) && 2244 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) && 2245 mem->Opcode() == Opcode()) { 2246 return mem; 2247 } 2248 2249 // Store of zero anywhere into a freshly-allocated object? 2250 // Then the store is useless. 2251 // (It must already have been captured by the InitializeNode.) 2252 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2253 // a newly allocated object is already all-zeroes everywhere 2254 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2255 return mem; 2256 } 2257 2258 // the store may also apply to zero-bits in an earlier object 2259 Node* prev_mem = find_previous_store(phase); 2260 // Steps (a), (b): Walk past independent stores to find an exact match. 2261 if (prev_mem != NULL) { 2262 Node* prev_val = can_see_stored_value(prev_mem, phase); 2263 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2264 // prev_val and val might differ by a cast; it would be good 2265 // to keep the more informative of the two. 2266 return mem; 2267 } 2268 } 2269 } 2270 2271 return this; 2272 } 2273 2274 //------------------------------match_edge------------------------------------- 2275 // Do we Match on this edge index or not? Match only memory & value 2276 uint StoreNode::match_edge(uint idx) const { 2277 return idx == MemNode::Address || idx == MemNode::ValueIn; 2278 } 2279 2280 //------------------------------cmp-------------------------------------------- 2281 // Do not common stores up together. They generally have to be split 2282 // back up anyways, so do not bother. 2283 uint StoreNode::cmp( const Node &n ) const { 2284 return (&n == this); // Always fail except on self 2285 } 2286 2287 //------------------------------Ideal_masked_input----------------------------- 2288 // Check for a useless mask before a partial-word store 2289 // (StoreB ... (AndI valIn conIa) ) 2290 // If (conIa & mask == mask) this simplifies to 2291 // (StoreB ... (valIn) ) 2292 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2293 Node *val = in(MemNode::ValueIn); 2294 if( val->Opcode() == Op_AndI ) { 2295 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2296 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2297 set_req(MemNode::ValueIn, val->in(1)); 2298 return this; 2299 } 2300 } 2301 return NULL; 2302 } 2303 2304 2305 //------------------------------Ideal_sign_extended_input---------------------- 2306 // Check for useless sign-extension before a partial-word store 2307 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2308 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2309 // (StoreB ... (valIn) ) 2310 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2311 Node *val = in(MemNode::ValueIn); 2312 if( val->Opcode() == Op_RShiftI ) { 2313 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2314 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2315 Node *shl = val->in(1); 2316 if( shl->Opcode() == Op_LShiftI ) { 2317 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2318 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2319 set_req(MemNode::ValueIn, shl->in(1)); 2320 return this; 2321 } 2322 } 2323 } 2324 } 2325 return NULL; 2326 } 2327 2328 //------------------------------value_never_loaded----------------------------------- 2329 // Determine whether there are any possible loads of the value stored. 2330 // For simplicity, we actually check if there are any loads from the 2331 // address stored to, not just for loads of the value stored by this node. 2332 // 2333 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2334 Node *adr = in(Address); 2335 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2336 if (adr_oop == NULL) 2337 return false; 2338 if (!adr_oop->is_known_instance_field()) 2339 return false; // if not a distinct instance, there may be aliases of the address 2340 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2341 Node *use = adr->fast_out(i); 2342 int opc = use->Opcode(); 2343 if (use->is_Load() || use->is_LoadStore()) { 2344 return false; 2345 } 2346 } 2347 return true; 2348 } 2349 2350 //============================================================================= 2351 //------------------------------Ideal------------------------------------------ 2352 // If the store is from an AND mask that leaves the low bits untouched, then 2353 // we can skip the AND operation. If the store is from a sign-extension 2354 // (a left shift, then right shift) we can skip both. 2355 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2356 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2357 if( progress != NULL ) return progress; 2358 2359 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2360 if( progress != NULL ) return progress; 2361 2362 // Finally check the default case 2363 return StoreNode::Ideal(phase, can_reshape); 2364 } 2365 2366 //============================================================================= 2367 //------------------------------Ideal------------------------------------------ 2368 // If the store is from an AND mask that leaves the low bits untouched, then 2369 // we can skip the AND operation 2370 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2371 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2372 if( progress != NULL ) return progress; 2373 2374 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2375 if( progress != NULL ) return progress; 2376 2377 // Finally check the default case 2378 return StoreNode::Ideal(phase, can_reshape); 2379 } 2380 2381 //============================================================================= 2382 //------------------------------Identity--------------------------------------- 2383 Node *StoreCMNode::Identity( PhaseTransform *phase ) { 2384 // No need to card mark when storing a null ptr 2385 Node* my_store = in(MemNode::OopStore); 2386 if (my_store->is_Store()) { 2387 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2388 if( t1 == TypePtr::NULL_PTR ) { 2389 return in(MemNode::Memory); 2390 } 2391 } 2392 return this; 2393 } 2394 2395 //============================================================================= 2396 //------------------------------Ideal--------------------------------------- 2397 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2398 Node* progress = StoreNode::Ideal(phase, can_reshape); 2399 if (progress != NULL) return progress; 2400 2401 Node* my_store = in(MemNode::OopStore); 2402 if (my_store->is_MergeMem()) { 2403 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2404 set_req(MemNode::OopStore, mem); 2405 return this; 2406 } 2407 2408 return NULL; 2409 } 2410 2411 //------------------------------Value----------------------------------------- 2412 const Type *StoreCMNode::Value( PhaseTransform *phase ) const { 2413 // Either input is TOP ==> the result is TOP 2414 const Type *t = phase->type( in(MemNode::Memory) ); 2415 if( t == Type::TOP ) return Type::TOP; 2416 t = phase->type( in(MemNode::Address) ); 2417 if( t == Type::TOP ) return Type::TOP; 2418 t = phase->type( in(MemNode::ValueIn) ); 2419 if( t == Type::TOP ) return Type::TOP; 2420 // If extra input is TOP ==> the result is TOP 2421 t = phase->type( in(MemNode::OopStore) ); 2422 if( t == Type::TOP ) return Type::TOP; 2423 2424 return StoreNode::Value( phase ); 2425 } 2426 2427 2428 //============================================================================= 2429 //----------------------------------SCMemProjNode------------------------------ 2430 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const 2431 { 2432 return bottom_type(); 2433 } 2434 2435 //============================================================================= 2436 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) { 2437 init_req(MemNode::Control, c ); 2438 init_req(MemNode::Memory , mem); 2439 init_req(MemNode::Address, adr); 2440 init_req(MemNode::ValueIn, val); 2441 init_req( ExpectedIn, ex ); 2442 init_class_id(Class_LoadStore); 2443 2444 } 2445 2446 //============================================================================= 2447 //-------------------------------adr_type-------------------------------------- 2448 // Do we Match on this edge index or not? Do not match memory 2449 const TypePtr* ClearArrayNode::adr_type() const { 2450 Node *adr = in(3); 2451 return MemNode::calculate_adr_type(adr->bottom_type()); 2452 } 2453 2454 //------------------------------match_edge------------------------------------- 2455 // Do we Match on this edge index or not? Do not match memory 2456 uint ClearArrayNode::match_edge(uint idx) const { 2457 return idx > 1; 2458 } 2459 2460 //------------------------------Identity--------------------------------------- 2461 // Clearing a zero length array does nothing 2462 Node *ClearArrayNode::Identity( PhaseTransform *phase ) { 2463 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2464 } 2465 2466 //------------------------------Idealize--------------------------------------- 2467 // Clearing a short array is faster with stores 2468 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2469 const int unit = BytesPerLong; 2470 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2471 if (!t) return NULL; 2472 if (!t->is_con()) return NULL; 2473 intptr_t raw_count = t->get_con(); 2474 intptr_t size = raw_count; 2475 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2476 // Clearing nothing uses the Identity call. 2477 // Negative clears are possible on dead ClearArrays 2478 // (see jck test stmt114.stmt11402.val). 2479 if (size <= 0 || size % unit != 0) return NULL; 2480 intptr_t count = size / unit; 2481 // Length too long; use fast hardware clear 2482 if (size > Matcher::init_array_short_size) return NULL; 2483 Node *mem = in(1); 2484 if( phase->type(mem)==Type::TOP ) return NULL; 2485 Node *adr = in(3); 2486 const Type* at = phase->type(adr); 2487 if( at==Type::TOP ) return NULL; 2488 const TypePtr* atp = at->isa_ptr(); 2489 // adjust atp to be the correct array element address type 2490 if (atp == NULL) atp = TypePtr::BOTTOM; 2491 else atp = atp->add_offset(Type::OffsetBot); 2492 // Get base for derived pointer purposes 2493 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2494 Node *base = adr->in(1); 2495 2496 Node *zero = phase->makecon(TypeLong::ZERO); 2497 Node *off = phase->MakeConX(BytesPerLong); 2498 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2499 count--; 2500 while( count-- ) { 2501 mem = phase->transform(mem); 2502 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off)); 2503 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2504 } 2505 return mem; 2506 } 2507 2508 //----------------------------step_through---------------------------------- 2509 // Return allocation input memory edge if it is different instance 2510 // or itself if it is the one we are looking for. 2511 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2512 Node* n = *np; 2513 assert(n->is_ClearArray(), "sanity"); 2514 intptr_t offset; 2515 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2516 // This method is called only before Allocate nodes are expanded during 2517 // macro nodes expansion. Before that ClearArray nodes are only generated 2518 // in LibraryCallKit::generate_arraycopy() which follows allocations. 2519 assert(alloc != NULL, "should have allocation"); 2520 if (alloc->_idx == instance_id) { 2521 // Can not bypass initialization of the instance we are looking for. 2522 return false; 2523 } 2524 // Otherwise skip it. 2525 InitializeNode* init = alloc->initialization(); 2526 if (init != NULL) 2527 *np = init->in(TypeFunc::Memory); 2528 else 2529 *np = alloc->in(TypeFunc::Memory); 2530 return true; 2531 } 2532 2533 //----------------------------clear_memory------------------------------------- 2534 // Generate code to initialize object storage to zero. 2535 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2536 intptr_t start_offset, 2537 Node* end_offset, 2538 PhaseGVN* phase) { 2539 Compile* C = phase->C; 2540 intptr_t offset = start_offset; 2541 2542 int unit = BytesPerLong; 2543 if ((offset % unit) != 0) { 2544 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset)); 2545 adr = phase->transform(adr); 2546 const TypePtr* atp = TypeRawPtr::BOTTOM; 2547 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2548 mem = phase->transform(mem); 2549 offset += BytesPerInt; 2550 } 2551 assert((offset % unit) == 0, ""); 2552 2553 // Initialize the remaining stuff, if any, with a ClearArray. 2554 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2555 } 2556 2557 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2558 Node* start_offset, 2559 Node* end_offset, 2560 PhaseGVN* phase) { 2561 if (start_offset == end_offset) { 2562 // nothing to do 2563 return mem; 2564 } 2565 2566 Compile* C = phase->C; 2567 int unit = BytesPerLong; 2568 Node* zbase = start_offset; 2569 Node* zend = end_offset; 2570 2571 // Scale to the unit required by the CPU: 2572 if (!Matcher::init_array_count_is_in_bytes) { 2573 Node* shift = phase->intcon(exact_log2(unit)); 2574 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) ); 2575 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) ); 2576 } 2577 2578 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) ); 2579 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT); 2580 2581 // Bulk clear double-words 2582 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) ); 2583 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr); 2584 return phase->transform(mem); 2585 } 2586 2587 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2588 intptr_t start_offset, 2589 intptr_t end_offset, 2590 PhaseGVN* phase) { 2591 if (start_offset == end_offset) { 2592 // nothing to do 2593 return mem; 2594 } 2595 2596 Compile* C = phase->C; 2597 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2598 intptr_t done_offset = end_offset; 2599 if ((done_offset % BytesPerLong) != 0) { 2600 done_offset -= BytesPerInt; 2601 } 2602 if (done_offset > start_offset) { 2603 mem = clear_memory(ctl, mem, dest, 2604 start_offset, phase->MakeConX(done_offset), phase); 2605 } 2606 if (done_offset < end_offset) { // emit the final 32-bit store 2607 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset)); 2608 adr = phase->transform(adr); 2609 const TypePtr* atp = TypeRawPtr::BOTTOM; 2610 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2611 mem = phase->transform(mem); 2612 done_offset += BytesPerInt; 2613 } 2614 assert(done_offset == end_offset, ""); 2615 return mem; 2616 } 2617 2618 //============================================================================= 2619 // Do not match memory edge. 2620 uint StrIntrinsicNode::match_edge(uint idx) const { 2621 return idx == 2 || idx == 3; 2622 } 2623 2624 //------------------------------Ideal------------------------------------------ 2625 // Return a node which is more "ideal" than the current node. Strip out 2626 // control copies 2627 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2628 if (remove_dead_region(phase, can_reshape)) return this; 2629 2630 if (can_reshape) { 2631 Node* mem = phase->transform(in(MemNode::Memory)); 2632 // If transformed to a MergeMem, get the desired slice 2633 uint alias_idx = phase->C->get_alias_index(adr_type()); 2634 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem; 2635 if (mem != in(MemNode::Memory)) { 2636 set_req(MemNode::Memory, mem); 2637 return this; 2638 } 2639 } 2640 return NULL; 2641 } 2642 2643 //============================================================================= 2644 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2645 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2646 _adr_type(C->get_adr_type(alias_idx)) 2647 { 2648 init_class_id(Class_MemBar); 2649 Node* top = C->top(); 2650 init_req(TypeFunc::I_O,top); 2651 init_req(TypeFunc::FramePtr,top); 2652 init_req(TypeFunc::ReturnAdr,top); 2653 if (precedent != NULL) 2654 init_req(TypeFunc::Parms, precedent); 2655 } 2656 2657 //------------------------------cmp-------------------------------------------- 2658 uint MemBarNode::hash() const { return NO_HASH; } 2659 uint MemBarNode::cmp( const Node &n ) const { 2660 return (&n == this); // Always fail except on self 2661 } 2662 2663 //------------------------------make------------------------------------------- 2664 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2665 int len = Precedent + (pn == NULL? 0: 1); 2666 switch (opcode) { 2667 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn); 2668 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn); 2669 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn); 2670 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn); 2671 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn); 2672 default: ShouldNotReachHere(); return NULL; 2673 } 2674 } 2675 2676 //------------------------------Ideal------------------------------------------ 2677 // Return a node which is more "ideal" than the current node. Strip out 2678 // control copies 2679 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2680 if (remove_dead_region(phase, can_reshape)) return this; 2681 2682 // Eliminate volatile MemBars for scalar replaced objects. 2683 if (can_reshape && req() == (Precedent+1) && 2684 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) { 2685 // Volatile field loads and stores. 2686 Node* my_mem = in(MemBarNode::Precedent); 2687 if (my_mem != NULL && my_mem->is_Mem()) { 2688 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 2689 // Check for scalar replaced object reference. 2690 if( t_oop != NULL && t_oop->is_known_instance_field() && 2691 t_oop->offset() != Type::OffsetBot && 2692 t_oop->offset() != Type::OffsetTop) { 2693 // Replace MemBar projections by its inputs. 2694 PhaseIterGVN* igvn = phase->is_IterGVN(); 2695 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 2696 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 2697 // Must return either the original node (now dead) or a new node 2698 // (Do not return a top here, since that would break the uniqueness of top.) 2699 return new (phase->C, 1) ConINode(TypeInt::ZERO); 2700 } 2701 } 2702 } 2703 return NULL; 2704 } 2705 2706 //------------------------------Value------------------------------------------ 2707 const Type *MemBarNode::Value( PhaseTransform *phase ) const { 2708 if( !in(0) ) return Type::TOP; 2709 if( phase->type(in(0)) == Type::TOP ) 2710 return Type::TOP; 2711 return TypeTuple::MEMBAR; 2712 } 2713 2714 //------------------------------match------------------------------------------ 2715 // Construct projections for memory. 2716 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 2717 switch (proj->_con) { 2718 case TypeFunc::Control: 2719 case TypeFunc::Memory: 2720 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 2721 } 2722 ShouldNotReachHere(); 2723 return NULL; 2724 } 2725 2726 //===========================InitializeNode==================================== 2727 // SUMMARY: 2728 // This node acts as a memory barrier on raw memory, after some raw stores. 2729 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 2730 // The Initialize can 'capture' suitably constrained stores as raw inits. 2731 // It can coalesce related raw stores into larger units (called 'tiles'). 2732 // It can avoid zeroing new storage for memory units which have raw inits. 2733 // At macro-expansion, it is marked 'complete', and does not optimize further. 2734 // 2735 // EXAMPLE: 2736 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 2737 // ctl = incoming control; mem* = incoming memory 2738 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 2739 // First allocate uninitialized memory and fill in the header: 2740 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 2741 // ctl := alloc.Control; mem* := alloc.Memory* 2742 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 2743 // Then initialize to zero the non-header parts of the raw memory block: 2744 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 2745 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 2746 // After the initialize node executes, the object is ready for service: 2747 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 2748 // Suppose its body is immediately initialized as {1,2}: 2749 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 2750 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 2751 // mem.SLICE(#short[*]) := store2 2752 // 2753 // DETAILS: 2754 // An InitializeNode collects and isolates object initialization after 2755 // an AllocateNode and before the next possible safepoint. As a 2756 // memory barrier (MemBarNode), it keeps critical stores from drifting 2757 // down past any safepoint or any publication of the allocation. 2758 // Before this barrier, a newly-allocated object may have uninitialized bits. 2759 // After this barrier, it may be treated as a real oop, and GC is allowed. 2760 // 2761 // The semantics of the InitializeNode include an implicit zeroing of 2762 // the new object from object header to the end of the object. 2763 // (The object header and end are determined by the AllocateNode.) 2764 // 2765 // Certain stores may be added as direct inputs to the InitializeNode. 2766 // These stores must update raw memory, and they must be to addresses 2767 // derived from the raw address produced by AllocateNode, and with 2768 // a constant offset. They must be ordered by increasing offset. 2769 // The first one is at in(RawStores), the last at in(req()-1). 2770 // Unlike most memory operations, they are not linked in a chain, 2771 // but are displayed in parallel as users of the rawmem output of 2772 // the allocation. 2773 // 2774 // (See comments in InitializeNode::capture_store, which continue 2775 // the example given above.) 2776 // 2777 // When the associated Allocate is macro-expanded, the InitializeNode 2778 // may be rewritten to optimize collected stores. A ClearArrayNode 2779 // may also be created at that point to represent any required zeroing. 2780 // The InitializeNode is then marked 'complete', prohibiting further 2781 // capturing of nearby memory operations. 2782 // 2783 // During macro-expansion, all captured initializations which store 2784 // constant values of 32 bits or smaller are coalesced (if advantageous) 2785 // into larger 'tiles' 32 or 64 bits. This allows an object to be 2786 // initialized in fewer memory operations. Memory words which are 2787 // covered by neither tiles nor non-constant stores are pre-zeroed 2788 // by explicit stores of zero. (The code shape happens to do all 2789 // zeroing first, then all other stores, with both sequences occurring 2790 // in order of ascending offsets.) 2791 // 2792 // Alternatively, code may be inserted between an AllocateNode and its 2793 // InitializeNode, to perform arbitrary initialization of the new object. 2794 // E.g., the object copying intrinsics insert complex data transfers here. 2795 // The initialization must then be marked as 'complete' disable the 2796 // built-in zeroing semantics and the collection of initializing stores. 2797 // 2798 // While an InitializeNode is incomplete, reads from the memory state 2799 // produced by it are optimizable if they match the control edge and 2800 // new oop address associated with the allocation/initialization. 2801 // They return a stored value (if the offset matches) or else zero. 2802 // A write to the memory state, if it matches control and address, 2803 // and if it is to a constant offset, may be 'captured' by the 2804 // InitializeNode. It is cloned as a raw memory operation and rewired 2805 // inside the initialization, to the raw oop produced by the allocation. 2806 // Operations on addresses which are provably distinct (e.g., to 2807 // other AllocateNodes) are allowed to bypass the initialization. 2808 // 2809 // The effect of all this is to consolidate object initialization 2810 // (both arrays and non-arrays, both piecewise and bulk) into a 2811 // single location, where it can be optimized as a unit. 2812 // 2813 // Only stores with an offset less than TrackedInitializationLimit words 2814 // will be considered for capture by an InitializeNode. This puts a 2815 // reasonable limit on the complexity of optimized initializations. 2816 2817 //---------------------------InitializeNode------------------------------------ 2818 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 2819 : _is_complete(false), 2820 MemBarNode(C, adr_type, rawoop) 2821 { 2822 init_class_id(Class_Initialize); 2823 2824 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 2825 assert(in(RawAddress) == rawoop, "proper init"); 2826 // Note: allocation() can be NULL, for secondary initialization barriers 2827 } 2828 2829 // Since this node is not matched, it will be processed by the 2830 // register allocator. Declare that there are no constraints 2831 // on the allocation of the RawAddress edge. 2832 const RegMask &InitializeNode::in_RegMask(uint idx) const { 2833 // This edge should be set to top, by the set_complete. But be conservative. 2834 if (idx == InitializeNode::RawAddress) 2835 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 2836 return RegMask::Empty; 2837 } 2838 2839 Node* InitializeNode::memory(uint alias_idx) { 2840 Node* mem = in(Memory); 2841 if (mem->is_MergeMem()) { 2842 return mem->as_MergeMem()->memory_at(alias_idx); 2843 } else { 2844 // incoming raw memory is not split 2845 return mem; 2846 } 2847 } 2848 2849 bool InitializeNode::is_non_zero() { 2850 if (is_complete()) return false; 2851 remove_extra_zeroes(); 2852 return (req() > RawStores); 2853 } 2854 2855 void InitializeNode::set_complete(PhaseGVN* phase) { 2856 assert(!is_complete(), "caller responsibility"); 2857 _is_complete = true; 2858 2859 // After this node is complete, it contains a bunch of 2860 // raw-memory initializations. There is no need for 2861 // it to have anything to do with non-raw memory effects. 2862 // Therefore, tell all non-raw users to re-optimize themselves, 2863 // after skipping the memory effects of this initialization. 2864 PhaseIterGVN* igvn = phase->is_IterGVN(); 2865 if (igvn) igvn->add_users_to_worklist(this); 2866 } 2867 2868 // convenience function 2869 // return false if the init contains any stores already 2870 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 2871 InitializeNode* init = initialization(); 2872 if (init == NULL || init->is_complete()) return false; 2873 init->remove_extra_zeroes(); 2874 // for now, if this allocation has already collected any inits, bail: 2875 if (init->is_non_zero()) return false; 2876 init->set_complete(phase); 2877 return true; 2878 } 2879 2880 void InitializeNode::remove_extra_zeroes() { 2881 if (req() == RawStores) return; 2882 Node* zmem = zero_memory(); 2883 uint fill = RawStores; 2884 for (uint i = fill; i < req(); i++) { 2885 Node* n = in(i); 2886 if (n->is_top() || n == zmem) continue; // skip 2887 if (fill < i) set_req(fill, n); // compact 2888 ++fill; 2889 } 2890 // delete any empty spaces created: 2891 while (fill < req()) { 2892 del_req(fill); 2893 } 2894 } 2895 2896 // Helper for remembering which stores go with which offsets. 2897 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 2898 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 2899 intptr_t offset = -1; 2900 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 2901 phase, offset); 2902 if (base == NULL) return -1; // something is dead, 2903 if (offset < 0) return -1; // dead, dead 2904 return offset; 2905 } 2906 2907 // Helper for proving that an initialization expression is 2908 // "simple enough" to be folded into an object initialization. 2909 // Attempts to prove that a store's initial value 'n' can be captured 2910 // within the initialization without creating a vicious cycle, such as: 2911 // { Foo p = new Foo(); p.next = p; } 2912 // True for constants and parameters and small combinations thereof. 2913 bool InitializeNode::detect_init_independence(Node* n, 2914 bool st_is_pinned, 2915 int& count) { 2916 if (n == NULL) return true; // (can this really happen?) 2917 if (n->is_Proj()) n = n->in(0); 2918 if (n == this) return false; // found a cycle 2919 if (n->is_Con()) return true; 2920 if (n->is_Start()) return true; // params, etc., are OK 2921 if (n->is_Root()) return true; // even better 2922 2923 Node* ctl = n->in(0); 2924 if (ctl != NULL && !ctl->is_top()) { 2925 if (ctl->is_Proj()) ctl = ctl->in(0); 2926 if (ctl == this) return false; 2927 2928 // If we already know that the enclosing memory op is pinned right after 2929 // the init, then any control flow that the store has picked up 2930 // must have preceded the init, or else be equal to the init. 2931 // Even after loop optimizations (which might change control edges) 2932 // a store is never pinned *before* the availability of its inputs. 2933 if (!MemNode::all_controls_dominate(n, this)) 2934 return false; // failed to prove a good control 2935 2936 } 2937 2938 // Check data edges for possible dependencies on 'this'. 2939 if ((count += 1) > 20) return false; // complexity limit 2940 for (uint i = 1; i < n->req(); i++) { 2941 Node* m = n->in(i); 2942 if (m == NULL || m == n || m->is_top()) continue; 2943 uint first_i = n->find_edge(m); 2944 if (i != first_i) continue; // process duplicate edge just once 2945 if (!detect_init_independence(m, st_is_pinned, count)) { 2946 return false; 2947 } 2948 } 2949 2950 return true; 2951 } 2952 2953 // Here are all the checks a Store must pass before it can be moved into 2954 // an initialization. Returns zero if a check fails. 2955 // On success, returns the (constant) offset to which the store applies, 2956 // within the initialized memory. 2957 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) { 2958 const int FAIL = 0; 2959 if (st->req() != MemNode::ValueIn + 1) 2960 return FAIL; // an inscrutable StoreNode (card mark?) 2961 Node* ctl = st->in(MemNode::Control); 2962 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 2963 return FAIL; // must be unconditional after the initialization 2964 Node* mem = st->in(MemNode::Memory); 2965 if (!(mem->is_Proj() && mem->in(0) == this)) 2966 return FAIL; // must not be preceded by other stores 2967 Node* adr = st->in(MemNode::Address); 2968 intptr_t offset; 2969 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 2970 if (alloc == NULL) 2971 return FAIL; // inscrutable address 2972 if (alloc != allocation()) 2973 return FAIL; // wrong allocation! (store needs to float up) 2974 Node* val = st->in(MemNode::ValueIn); 2975 int complexity_count = 0; 2976 if (!detect_init_independence(val, true, complexity_count)) 2977 return FAIL; // stored value must be 'simple enough' 2978 2979 return offset; // success 2980 } 2981 2982 // Find the captured store in(i) which corresponds to the range 2983 // [start..start+size) in the initialized object. 2984 // If there is one, return its index i. If there isn't, return the 2985 // negative of the index where it should be inserted. 2986 // Return 0 if the queried range overlaps an initialization boundary 2987 // or if dead code is encountered. 2988 // If size_in_bytes is zero, do not bother with overlap checks. 2989 int InitializeNode::captured_store_insertion_point(intptr_t start, 2990 int size_in_bytes, 2991 PhaseTransform* phase) { 2992 const int FAIL = 0, MAX_STORE = BytesPerLong; 2993 2994 if (is_complete()) 2995 return FAIL; // arraycopy got here first; punt 2996 2997 assert(allocation() != NULL, "must be present"); 2998 2999 // no negatives, no header fields: 3000 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3001 3002 // after a certain size, we bail out on tracking all the stores: 3003 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3004 if (start >= ti_limit) return FAIL; 3005 3006 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3007 if (i >= limit) return -(int)i; // not found; here is where to put it 3008 3009 Node* st = in(i); 3010 intptr_t st_off = get_store_offset(st, phase); 3011 if (st_off < 0) { 3012 if (st != zero_memory()) { 3013 return FAIL; // bail out if there is dead garbage 3014 } 3015 } else if (st_off > start) { 3016 // ...we are done, since stores are ordered 3017 if (st_off < start + size_in_bytes) { 3018 return FAIL; // the next store overlaps 3019 } 3020 return -(int)i; // not found; here is where to put it 3021 } else if (st_off < start) { 3022 if (size_in_bytes != 0 && 3023 start < st_off + MAX_STORE && 3024 start < st_off + st->as_Store()->memory_size()) { 3025 return FAIL; // the previous store overlaps 3026 } 3027 } else { 3028 if (size_in_bytes != 0 && 3029 st->as_Store()->memory_size() != size_in_bytes) { 3030 return FAIL; // mismatched store size 3031 } 3032 return i; 3033 } 3034 3035 ++i; 3036 } 3037 } 3038 3039 // Look for a captured store which initializes at the offset 'start' 3040 // with the given size. If there is no such store, and no other 3041 // initialization interferes, then return zero_memory (the memory 3042 // projection of the AllocateNode). 3043 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3044 PhaseTransform* phase) { 3045 assert(stores_are_sane(phase), ""); 3046 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3047 if (i == 0) { 3048 return NULL; // something is dead 3049 } else if (i < 0) { 3050 return zero_memory(); // just primordial zero bits here 3051 } else { 3052 Node* st = in(i); // here is the store at this position 3053 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3054 return st; 3055 } 3056 } 3057 3058 // Create, as a raw pointer, an address within my new object at 'offset'. 3059 Node* InitializeNode::make_raw_address(intptr_t offset, 3060 PhaseTransform* phase) { 3061 Node* addr = in(RawAddress); 3062 if (offset != 0) { 3063 Compile* C = phase->C; 3064 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr, 3065 phase->MakeConX(offset)) ); 3066 } 3067 return addr; 3068 } 3069 3070 // Clone the given store, converting it into a raw store 3071 // initializing a field or element of my new object. 3072 // Caller is responsible for retiring the original store, 3073 // with subsume_node or the like. 3074 // 3075 // From the example above InitializeNode::InitializeNode, 3076 // here are the old stores to be captured: 3077 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3078 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3079 // 3080 // Here is the changed code; note the extra edges on init: 3081 // alloc = (Allocate ...) 3082 // rawoop = alloc.RawAddress 3083 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3084 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3085 // init = (Initialize alloc.Control alloc.Memory rawoop 3086 // rawstore1 rawstore2) 3087 // 3088 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3089 PhaseTransform* phase) { 3090 assert(stores_are_sane(phase), ""); 3091 3092 if (start < 0) return NULL; 3093 assert(can_capture_store(st, phase) == start, "sanity"); 3094 3095 Compile* C = phase->C; 3096 int size_in_bytes = st->memory_size(); 3097 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3098 if (i == 0) return NULL; // bail out 3099 Node* prev_mem = NULL; // raw memory for the captured store 3100 if (i > 0) { 3101 prev_mem = in(i); // there is a pre-existing store under this one 3102 set_req(i, C->top()); // temporarily disconnect it 3103 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3104 } else { 3105 i = -i; // no pre-existing store 3106 prev_mem = zero_memory(); // a slice of the newly allocated object 3107 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3108 set_req(--i, C->top()); // reuse this edge; it has been folded away 3109 else 3110 ins_req(i, C->top()); // build a new edge 3111 } 3112 Node* new_st = st->clone(); 3113 new_st->set_req(MemNode::Control, in(Control)); 3114 new_st->set_req(MemNode::Memory, prev_mem); 3115 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3116 new_st = phase->transform(new_st); 3117 3118 // At this point, new_st might have swallowed a pre-existing store 3119 // at the same offset, or perhaps new_st might have disappeared, 3120 // if it redundantly stored the same value (or zero to fresh memory). 3121 3122 // In any case, wire it in: 3123 set_req(i, new_st); 3124 3125 // The caller may now kill the old guy. 3126 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3127 assert(check_st == new_st || check_st == NULL, "must be findable"); 3128 assert(!is_complete(), ""); 3129 return new_st; 3130 } 3131 3132 static bool store_constant(jlong* tiles, int num_tiles, 3133 intptr_t st_off, int st_size, 3134 jlong con) { 3135 if ((st_off & (st_size-1)) != 0) 3136 return false; // strange store offset (assume size==2**N) 3137 address addr = (address)tiles + st_off; 3138 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3139 switch (st_size) { 3140 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3141 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3142 case sizeof(jint): *(jint*) addr = (jint) con; break; 3143 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3144 default: return false; // strange store size (detect size!=2**N here) 3145 } 3146 return true; // return success to caller 3147 } 3148 3149 // Coalesce subword constants into int constants and possibly 3150 // into long constants. The goal, if the CPU permits, 3151 // is to initialize the object with a small number of 64-bit tiles. 3152 // Also, convert floating-point constants to bit patterns. 3153 // Non-constants are not relevant to this pass. 3154 // 3155 // In terms of the running example on InitializeNode::InitializeNode 3156 // and InitializeNode::capture_store, here is the transformation 3157 // of rawstore1 and rawstore2 into rawstore12: 3158 // alloc = (Allocate ...) 3159 // rawoop = alloc.RawAddress 3160 // tile12 = 0x00010002 3161 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3162 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3163 // 3164 void 3165 InitializeNode::coalesce_subword_stores(intptr_t header_size, 3166 Node* size_in_bytes, 3167 PhaseGVN* phase) { 3168 Compile* C = phase->C; 3169 3170 assert(stores_are_sane(phase), ""); 3171 // Note: After this pass, they are not completely sane, 3172 // since there may be some overlaps. 3173 3174 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3175 3176 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3177 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3178 size_limit = MIN2(size_limit, ti_limit); 3179 size_limit = align_size_up(size_limit, BytesPerLong); 3180 int num_tiles = size_limit / BytesPerLong; 3181 3182 // allocate space for the tile map: 3183 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3184 jlong tiles_buf[small_len]; 3185 Node* nodes_buf[small_len]; 3186 jlong inits_buf[small_len]; 3187 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3188 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3189 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3190 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3191 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3192 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3193 // tiles: exact bitwise model of all primitive constants 3194 // nodes: last constant-storing node subsumed into the tiles model 3195 // inits: which bytes (in each tile) are touched by any initializations 3196 3197 //// Pass A: Fill in the tile model with any relevant stores. 3198 3199 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3200 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3201 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3202 Node* zmem = zero_memory(); // initially zero memory state 3203 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3204 Node* st = in(i); 3205 intptr_t st_off = get_store_offset(st, phase); 3206 3207 // Figure out the store's offset and constant value: 3208 if (st_off < header_size) continue; //skip (ignore header) 3209 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3210 int st_size = st->as_Store()->memory_size(); 3211 if (st_off + st_size > size_limit) break; 3212 3213 // Record which bytes are touched, whether by constant or not. 3214 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3215 continue; // skip (strange store size) 3216 3217 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3218 if (!val->singleton()) continue; //skip (non-con store) 3219 BasicType type = val->basic_type(); 3220 3221 jlong con = 0; 3222 switch (type) { 3223 case T_INT: con = val->is_int()->get_con(); break; 3224 case T_LONG: con = val->is_long()->get_con(); break; 3225 case T_FLOAT: con = jint_cast(val->getf()); break; 3226 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3227 default: continue; //skip (odd store type) 3228 } 3229 3230 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3231 st->Opcode() == Op_StoreL) { 3232 continue; // This StoreL is already optimal. 3233 } 3234 3235 // Store down the constant. 3236 store_constant(tiles, num_tiles, st_off, st_size, con); 3237 3238 intptr_t j = st_off >> LogBytesPerLong; 3239 3240 if (type == T_INT && st_size == BytesPerInt 3241 && (st_off & BytesPerInt) == BytesPerInt) { 3242 jlong lcon = tiles[j]; 3243 if (!Matcher::isSimpleConstant64(lcon) && 3244 st->Opcode() == Op_StoreI) { 3245 // This StoreI is already optimal by itself. 3246 jint* intcon = (jint*) &tiles[j]; 3247 intcon[1] = 0; // undo the store_constant() 3248 3249 // If the previous store is also optimal by itself, back up and 3250 // undo the action of the previous loop iteration... if we can. 3251 // But if we can't, just let the previous half take care of itself. 3252 st = nodes[j]; 3253 st_off -= BytesPerInt; 3254 con = intcon[0]; 3255 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3256 assert(st_off >= header_size, "still ignoring header"); 3257 assert(get_store_offset(st, phase) == st_off, "must be"); 3258 assert(in(i-1) == zmem, "must be"); 3259 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3260 assert(con == tcon->is_int()->get_con(), "must be"); 3261 // Undo the effects of the previous loop trip, which swallowed st: 3262 intcon[0] = 0; // undo store_constant() 3263 set_req(i-1, st); // undo set_req(i, zmem) 3264 nodes[j] = NULL; // undo nodes[j] = st 3265 --old_subword; // undo ++old_subword 3266 } 3267 continue; // This StoreI is already optimal. 3268 } 3269 } 3270 3271 // This store is not needed. 3272 set_req(i, zmem); 3273 nodes[j] = st; // record for the moment 3274 if (st_size < BytesPerLong) // something has changed 3275 ++old_subword; // includes int/float, but who's counting... 3276 else ++old_long; 3277 } 3278 3279 if ((old_subword + old_long) == 0) 3280 return; // nothing more to do 3281 3282 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3283 // Be sure to insert them before overlapping non-constant stores. 3284 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3285 for (int j = 0; j < num_tiles; j++) { 3286 jlong con = tiles[j]; 3287 jlong init = inits[j]; 3288 if (con == 0) continue; 3289 jint con0, con1; // split the constant, address-wise 3290 jint init0, init1; // split the init map, address-wise 3291 { union { jlong con; jint intcon[2]; } u; 3292 u.con = con; 3293 con0 = u.intcon[0]; 3294 con1 = u.intcon[1]; 3295 u.con = init; 3296 init0 = u.intcon[0]; 3297 init1 = u.intcon[1]; 3298 } 3299 3300 Node* old = nodes[j]; 3301 assert(old != NULL, "need the prior store"); 3302 intptr_t offset = (j * BytesPerLong); 3303 3304 bool split = !Matcher::isSimpleConstant64(con); 3305 3306 if (offset < header_size) { 3307 assert(offset + BytesPerInt >= header_size, "second int counts"); 3308 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3309 split = true; // only the second word counts 3310 // Example: int a[] = { 42 ... } 3311 } else if (con0 == 0 && init0 == -1) { 3312 split = true; // first word is covered by full inits 3313 // Example: int a[] = { ... foo(), 42 ... } 3314 } else if (con1 == 0 && init1 == -1) { 3315 split = true; // second word is covered by full inits 3316 // Example: int a[] = { ... 42, foo() ... } 3317 } 3318 3319 // Here's a case where init0 is neither 0 nor -1: 3320 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3321 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3322 // In this case the tile is not split; it is (jlong)42. 3323 // The big tile is stored down, and then the foo() value is inserted. 3324 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3325 3326 Node* ctl = old->in(MemNode::Control); 3327 Node* adr = make_raw_address(offset, phase); 3328 const TypePtr* atp = TypeRawPtr::BOTTOM; 3329 3330 // One or two coalesced stores to plop down. 3331 Node* st[2]; 3332 intptr_t off[2]; 3333 int nst = 0; 3334 if (!split) { 3335 ++new_long; 3336 off[nst] = offset; 3337 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3338 phase->longcon(con), T_LONG); 3339 } else { 3340 // Omit either if it is a zero. 3341 if (con0 != 0) { 3342 ++new_int; 3343 off[nst] = offset; 3344 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3345 phase->intcon(con0), T_INT); 3346 } 3347 if (con1 != 0) { 3348 ++new_int; 3349 offset += BytesPerInt; 3350 adr = make_raw_address(offset, phase); 3351 off[nst] = offset; 3352 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3353 phase->intcon(con1), T_INT); 3354 } 3355 } 3356 3357 // Insert second store first, then the first before the second. 3358 // Insert each one just before any overlapping non-constant stores. 3359 while (nst > 0) { 3360 Node* st1 = st[--nst]; 3361 C->copy_node_notes_to(st1, old); 3362 st1 = phase->transform(st1); 3363 offset = off[nst]; 3364 assert(offset >= header_size, "do not smash header"); 3365 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3366 guarantee(ins_idx != 0, "must re-insert constant store"); 3367 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3368 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3369 set_req(--ins_idx, st1); 3370 else 3371 ins_req(ins_idx, st1); 3372 } 3373 } 3374 3375 if (PrintCompilation && WizardMode) 3376 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3377 old_subword, old_long, new_int, new_long); 3378 if (C->log() != NULL) 3379 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3380 old_subword, old_long, new_int, new_long); 3381 3382 // Clean up any remaining occurrences of zmem: 3383 remove_extra_zeroes(); 3384 } 3385 3386 // Explore forward from in(start) to find the first fully initialized 3387 // word, and return its offset. Skip groups of subword stores which 3388 // together initialize full words. If in(start) is itself part of a 3389 // fully initialized word, return the offset of in(start). If there 3390 // are no following full-word stores, or if something is fishy, return 3391 // a negative value. 3392 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3393 int int_map = 0; 3394 intptr_t int_map_off = 0; 3395 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3396 3397 for (uint i = start, limit = req(); i < limit; i++) { 3398 Node* st = in(i); 3399 3400 intptr_t st_off = get_store_offset(st, phase); 3401 if (st_off < 0) break; // return conservative answer 3402 3403 int st_size = st->as_Store()->memory_size(); 3404 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3405 return st_off; // we found a complete word init 3406 } 3407 3408 // update the map: 3409 3410 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); 3411 if (this_int_off != int_map_off) { 3412 // reset the map: 3413 int_map = 0; 3414 int_map_off = this_int_off; 3415 } 3416 3417 int subword_off = st_off - this_int_off; 3418 int_map |= right_n_bits(st_size) << subword_off; 3419 if ((int_map & FULL_MAP) == FULL_MAP) { 3420 return this_int_off; // we found a complete word init 3421 } 3422 3423 // Did this store hit or cross the word boundary? 3424 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); 3425 if (next_int_off == this_int_off + BytesPerInt) { 3426 // We passed the current int, without fully initializing it. 3427 int_map_off = next_int_off; 3428 int_map >>= BytesPerInt; 3429 } else if (next_int_off > this_int_off + BytesPerInt) { 3430 // We passed the current and next int. 3431 return this_int_off + BytesPerInt; 3432 } 3433 } 3434 3435 return -1; 3436 } 3437 3438 3439 // Called when the associated AllocateNode is expanded into CFG. 3440 // At this point, we may perform additional optimizations. 3441 // Linearize the stores by ascending offset, to make memory 3442 // activity as coherent as possible. 3443 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3444 intptr_t header_size, 3445 Node* size_in_bytes, 3446 PhaseGVN* phase) { 3447 assert(!is_complete(), "not already complete"); 3448 assert(stores_are_sane(phase), ""); 3449 assert(allocation() != NULL, "must be present"); 3450 3451 remove_extra_zeroes(); 3452 3453 if (ReduceFieldZeroing || ReduceBulkZeroing) 3454 // reduce instruction count for common initialization patterns 3455 coalesce_subword_stores(header_size, size_in_bytes, phase); 3456 3457 Node* zmem = zero_memory(); // initially zero memory state 3458 Node* inits = zmem; // accumulating a linearized chain of inits 3459 #ifdef ASSERT 3460 intptr_t first_offset = allocation()->minimum_header_size(); 3461 intptr_t last_init_off = first_offset; // previous init offset 3462 intptr_t last_init_end = first_offset; // previous init offset+size 3463 intptr_t last_tile_end = first_offset; // previous tile offset+size 3464 #endif 3465 intptr_t zeroes_done = header_size; 3466 3467 bool do_zeroing = true; // we might give up if inits are very sparse 3468 int big_init_gaps = 0; // how many large gaps have we seen? 3469 3470 if (ZeroTLAB) do_zeroing = false; 3471 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3472 3473 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3474 Node* st = in(i); 3475 intptr_t st_off = get_store_offset(st, phase); 3476 if (st_off < 0) 3477 break; // unknown junk in the inits 3478 if (st->in(MemNode::Memory) != zmem) 3479 break; // complicated store chains somehow in list 3480 3481 int st_size = st->as_Store()->memory_size(); 3482 intptr_t next_init_off = st_off + st_size; 3483 3484 if (do_zeroing && zeroes_done < next_init_off) { 3485 // See if this store needs a zero before it or under it. 3486 intptr_t zeroes_needed = st_off; 3487 3488 if (st_size < BytesPerInt) { 3489 // Look for subword stores which only partially initialize words. 3490 // If we find some, we must lay down some word-level zeroes first, 3491 // underneath the subword stores. 3492 // 3493 // Examples: 3494 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3495 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3496 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3497 // 3498 // Note: coalesce_subword_stores may have already done this, 3499 // if it was prompted by constant non-zero subword initializers. 3500 // But this case can still arise with non-constant stores. 3501 3502 intptr_t next_full_store = find_next_fullword_store(i, phase); 3503 3504 // In the examples above: 3505 // in(i) p q r s x y z 3506 // st_off 12 13 14 15 12 13 14 3507 // st_size 1 1 1 1 1 1 1 3508 // next_full_s. 12 16 16 16 16 16 16 3509 // z's_done 12 16 16 16 12 16 12 3510 // z's_needed 12 16 16 16 16 16 16 3511 // zsize 0 0 0 0 4 0 4 3512 if (next_full_store < 0) { 3513 // Conservative tack: Zero to end of current word. 3514 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); 3515 } else { 3516 // Zero to beginning of next fully initialized word. 3517 // Or, don't zero at all, if we are already in that word. 3518 assert(next_full_store >= zeroes_needed, "must go forward"); 3519 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3520 zeroes_needed = next_full_store; 3521 } 3522 } 3523 3524 if (zeroes_needed > zeroes_done) { 3525 intptr_t zsize = zeroes_needed - zeroes_done; 3526 // Do some incremental zeroing on rawmem, in parallel with inits. 3527 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3528 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3529 zeroes_done, zeroes_needed, 3530 phase); 3531 zeroes_done = zeroes_needed; 3532 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) 3533 do_zeroing = false; // leave the hole, next time 3534 } 3535 } 3536 3537 // Collect the store and move on: 3538 st->set_req(MemNode::Memory, inits); 3539 inits = st; // put it on the linearized chain 3540 set_req(i, zmem); // unhook from previous position 3541 3542 if (zeroes_done == st_off) 3543 zeroes_done = next_init_off; 3544 3545 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3546 3547 #ifdef ASSERT 3548 // Various order invariants. Weaker than stores_are_sane because 3549 // a large constant tile can be filled in by smaller non-constant stores. 3550 assert(st_off >= last_init_off, "inits do not reverse"); 3551 last_init_off = st_off; 3552 const Type* val = NULL; 3553 if (st_size >= BytesPerInt && 3554 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3555 (int)val->basic_type() < (int)T_OBJECT) { 3556 assert(st_off >= last_tile_end, "tiles do not overlap"); 3557 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3558 last_tile_end = MAX2(last_tile_end, next_init_off); 3559 } else { 3560 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); 3561 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3562 assert(st_off >= last_init_end, "inits do not overlap"); 3563 last_init_end = next_init_off; // it's a non-tile 3564 } 3565 #endif //ASSERT 3566 } 3567 3568 remove_extra_zeroes(); // clear out all the zmems left over 3569 add_req(inits); 3570 3571 if (!ZeroTLAB) { 3572 // If anything remains to be zeroed, zero it all now. 3573 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3574 // if it is the last unused 4 bytes of an instance, forget about it 3575 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3576 if (zeroes_done + BytesPerLong >= size_limit) { 3577 assert(allocation() != NULL, ""); 3578 if (allocation()->Opcode() == Op_Allocate) { 3579 Node* klass_node = allocation()->in(AllocateNode::KlassNode); 3580 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3581 if (zeroes_done == k->layout_helper()) 3582 zeroes_done = size_limit; 3583 } 3584 } 3585 if (zeroes_done < size_limit) { 3586 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3587 zeroes_done, size_in_bytes, phase); 3588 } 3589 } 3590 3591 set_complete(phase); 3592 return rawmem; 3593 } 3594 3595 3596 #ifdef ASSERT 3597 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3598 if (is_complete()) 3599 return true; // stores could be anything at this point 3600 assert(allocation() != NULL, "must be present"); 3601 intptr_t last_off = allocation()->minimum_header_size(); 3602 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3603 Node* st = in(i); 3604 intptr_t st_off = get_store_offset(st, phase); 3605 if (st_off < 0) continue; // ignore dead garbage 3606 if (last_off > st_off) { 3607 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off); 3608 this->dump(2); 3609 assert(false, "ascending store offsets"); 3610 return false; 3611 } 3612 last_off = st_off + st->as_Store()->memory_size(); 3613 } 3614 return true; 3615 } 3616 #endif //ASSERT 3617 3618 3619 3620 3621 //============================MergeMemNode===================================== 3622 // 3623 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 3624 // contributing store or call operations. Each contributor provides the memory 3625 // state for a particular "alias type" (see Compile::alias_type). For example, 3626 // if a MergeMem has an input X for alias category #6, then any memory reference 3627 // to alias category #6 may use X as its memory state input, as an exact equivalent 3628 // to using the MergeMem as a whole. 3629 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 3630 // 3631 // (Here, the <N> notation gives the index of the relevant adr_type.) 3632 // 3633 // In one special case (and more cases in the future), alias categories overlap. 3634 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 3635 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 3636 // it is exactly equivalent to that state W: 3637 // MergeMem(<Bot>: W) <==> W 3638 // 3639 // Usually, the merge has more than one input. In that case, where inputs 3640 // overlap (i.e., one is Bot), the narrower alias type determines the memory 3641 // state for that type, and the wider alias type (Bot) fills in everywhere else: 3642 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 3643 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 3644 // 3645 // A merge can take a "wide" memory state as one of its narrow inputs. 3646 // This simply means that the merge observes out only the relevant parts of 3647 // the wide input. That is, wide memory states arriving at narrow merge inputs 3648 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 3649 // 3650 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 3651 // and that memory slices "leak through": 3652 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 3653 // 3654 // But, in such a cascade, repeated memory slices can "block the leak": 3655 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 3656 // 3657 // In the last example, Y is not part of the combined memory state of the 3658 // outermost MergeMem. The system must, of course, prevent unschedulable 3659 // memory states from arising, so you can be sure that the state Y is somehow 3660 // a precursor to state Y'. 3661 // 3662 // 3663 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 3664 // of each MergeMemNode array are exactly the numerical alias indexes, including 3665 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 3666 // Compile::alias_type (and kin) produce and manage these indexes. 3667 // 3668 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 3669 // (Note that this provides quick access to the top node inside MergeMem methods, 3670 // without the need to reach out via TLS to Compile::current.) 3671 // 3672 // As a consequence of what was just described, a MergeMem that represents a full 3673 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 3674 // containing all alias categories. 3675 // 3676 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 3677 // 3678 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 3679 // a memory state for the alias type <N>, or else the top node, meaning that 3680 // there is no particular input for that alias type. Note that the length of 3681 // a MergeMem is variable, and may be extended at any time to accommodate new 3682 // memory states at larger alias indexes. When merges grow, they are of course 3683 // filled with "top" in the unused in() positions. 3684 // 3685 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 3686 // (Top was chosen because it works smoothly with passes like GCM.) 3687 // 3688 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 3689 // the type of random VM bits like TLS references.) Since it is always the 3690 // first non-Bot memory slice, some low-level loops use it to initialize an 3691 // index variable: for (i = AliasIdxRaw; i < req(); i++). 3692 // 3693 // 3694 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 3695 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 3696 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 3697 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 3698 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 3699 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 3700 // 3701 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 3702 // really that different from the other memory inputs. An abbreviation called 3703 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 3704 // 3705 // 3706 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 3707 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 3708 // that "emerges though" the base memory will be marked as excluding the alias types 3709 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 3710 // 3711 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 3712 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 3713 // 3714 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 3715 // (It is currently unimplemented.) As you can see, the resulting merge is 3716 // actually a disjoint union of memory states, rather than an overlay. 3717 // 3718 3719 //------------------------------MergeMemNode----------------------------------- 3720 Node* MergeMemNode::make_empty_memory() { 3721 Node* empty_memory = (Node*) Compile::current()->top(); 3722 assert(empty_memory->is_top(), "correct sentinel identity"); 3723 return empty_memory; 3724 } 3725 3726 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 3727 init_class_id(Class_MergeMem); 3728 // all inputs are nullified in Node::Node(int) 3729 // set_input(0, NULL); // no control input 3730 3731 // Initialize the edges uniformly to top, for starters. 3732 Node* empty_mem = make_empty_memory(); 3733 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 3734 init_req(i,empty_mem); 3735 } 3736 assert(empty_memory() == empty_mem, ""); 3737 3738 if( new_base != NULL && new_base->is_MergeMem() ) { 3739 MergeMemNode* mdef = new_base->as_MergeMem(); 3740 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 3741 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 3742 mms.set_memory(mms.memory2()); 3743 } 3744 assert(base_memory() == mdef->base_memory(), ""); 3745 } else { 3746 set_base_memory(new_base); 3747 } 3748 } 3749 3750 // Make a new, untransformed MergeMem with the same base as 'mem'. 3751 // If mem is itself a MergeMem, populate the result with the same edges. 3752 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) { 3753 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem); 3754 } 3755 3756 //------------------------------cmp-------------------------------------------- 3757 uint MergeMemNode::hash() const { return NO_HASH; } 3758 uint MergeMemNode::cmp( const Node &n ) const { 3759 return (&n == this); // Always fail except on self 3760 } 3761 3762 //------------------------------Identity--------------------------------------- 3763 Node* MergeMemNode::Identity(PhaseTransform *phase) { 3764 // Identity if this merge point does not record any interesting memory 3765 // disambiguations. 3766 Node* base_mem = base_memory(); 3767 Node* empty_mem = empty_memory(); 3768 if (base_mem != empty_mem) { // Memory path is not dead? 3769 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3770 Node* mem = in(i); 3771 if (mem != empty_mem && mem != base_mem) { 3772 return this; // Many memory splits; no change 3773 } 3774 } 3775 } 3776 return base_mem; // No memory splits; ID on the one true input 3777 } 3778 3779 //------------------------------Ideal------------------------------------------ 3780 // This method is invoked recursively on chains of MergeMem nodes 3781 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3782 // Remove chain'd MergeMems 3783 // 3784 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 3785 // relative to the "in(Bot)". Since we are patching both at the same time, 3786 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 3787 // but rewrite each "in(i)" relative to the new "in(Bot)". 3788 Node *progress = NULL; 3789 3790 3791 Node* old_base = base_memory(); 3792 Node* empty_mem = empty_memory(); 3793 if (old_base == empty_mem) 3794 return NULL; // Dead memory path. 3795 3796 MergeMemNode* old_mbase; 3797 if (old_base != NULL && old_base->is_MergeMem()) 3798 old_mbase = old_base->as_MergeMem(); 3799 else 3800 old_mbase = NULL; 3801 Node* new_base = old_base; 3802 3803 // simplify stacked MergeMems in base memory 3804 if (old_mbase) new_base = old_mbase->base_memory(); 3805 3806 // the base memory might contribute new slices beyond my req() 3807 if (old_mbase) grow_to_match(old_mbase); 3808 3809 // Look carefully at the base node if it is a phi. 3810 PhiNode* phi_base; 3811 if (new_base != NULL && new_base->is_Phi()) 3812 phi_base = new_base->as_Phi(); 3813 else 3814 phi_base = NULL; 3815 3816 Node* phi_reg = NULL; 3817 uint phi_len = (uint)-1; 3818 if (phi_base != NULL && !phi_base->is_copy()) { 3819 // do not examine phi if degraded to a copy 3820 phi_reg = phi_base->region(); 3821 phi_len = phi_base->req(); 3822 // see if the phi is unfinished 3823 for (uint i = 1; i < phi_len; i++) { 3824 if (phi_base->in(i) == NULL) { 3825 // incomplete phi; do not look at it yet! 3826 phi_reg = NULL; 3827 phi_len = (uint)-1; 3828 break; 3829 } 3830 } 3831 } 3832 3833 // Note: We do not call verify_sparse on entry, because inputs 3834 // can normalize to the base_memory via subsume_node or similar 3835 // mechanisms. This method repairs that damage. 3836 3837 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 3838 3839 // Look at each slice. 3840 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3841 Node* old_in = in(i); 3842 // calculate the old memory value 3843 Node* old_mem = old_in; 3844 if (old_mem == empty_mem) old_mem = old_base; 3845 assert(old_mem == memory_at(i), ""); 3846 3847 // maybe update (reslice) the old memory value 3848 3849 // simplify stacked MergeMems 3850 Node* new_mem = old_mem; 3851 MergeMemNode* old_mmem; 3852 if (old_mem != NULL && old_mem->is_MergeMem()) 3853 old_mmem = old_mem->as_MergeMem(); 3854 else 3855 old_mmem = NULL; 3856 if (old_mmem == this) { 3857 // This can happen if loops break up and safepoints disappear. 3858 // A merge of BotPtr (default) with a RawPtr memory derived from a 3859 // safepoint can be rewritten to a merge of the same BotPtr with 3860 // the BotPtr phi coming into the loop. If that phi disappears 3861 // also, we can end up with a self-loop of the mergemem. 3862 // In general, if loops degenerate and memory effects disappear, 3863 // a mergemem can be left looking at itself. This simply means 3864 // that the mergemem's default should be used, since there is 3865 // no longer any apparent effect on this slice. 3866 // Note: If a memory slice is a MergeMem cycle, it is unreachable 3867 // from start. Update the input to TOP. 3868 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 3869 } 3870 else if (old_mmem != NULL) { 3871 new_mem = old_mmem->memory_at(i); 3872 } 3873 // else preceding memory was not a MergeMem 3874 3875 // replace equivalent phis (unfortunately, they do not GVN together) 3876 if (new_mem != NULL && new_mem != new_base && 3877 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 3878 if (new_mem->is_Phi()) { 3879 PhiNode* phi_mem = new_mem->as_Phi(); 3880 for (uint i = 1; i < phi_len; i++) { 3881 if (phi_base->in(i) != phi_mem->in(i)) { 3882 phi_mem = NULL; 3883 break; 3884 } 3885 } 3886 if (phi_mem != NULL) { 3887 // equivalent phi nodes; revert to the def 3888 new_mem = new_base; 3889 } 3890 } 3891 } 3892 3893 // maybe store down a new value 3894 Node* new_in = new_mem; 3895 if (new_in == new_base) new_in = empty_mem; 3896 3897 if (new_in != old_in) { 3898 // Warning: Do not combine this "if" with the previous "if" 3899 // A memory slice might have be be rewritten even if it is semantically 3900 // unchanged, if the base_memory value has changed. 3901 set_req(i, new_in); 3902 progress = this; // Report progress 3903 } 3904 } 3905 3906 if (new_base != old_base) { 3907 set_req(Compile::AliasIdxBot, new_base); 3908 // Don't use set_base_memory(new_base), because we need to update du. 3909 assert(base_memory() == new_base, ""); 3910 progress = this; 3911 } 3912 3913 if( base_memory() == this ) { 3914 // a self cycle indicates this memory path is dead 3915 set_req(Compile::AliasIdxBot, empty_mem); 3916 } 3917 3918 // Resolve external cycles by calling Ideal on a MergeMem base_memory 3919 // Recursion must occur after the self cycle check above 3920 if( base_memory()->is_MergeMem() ) { 3921 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 3922 Node *m = phase->transform(new_mbase); // Rollup any cycles 3923 if( m != NULL && (m->is_top() || 3924 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 3925 // propagate rollup of dead cycle to self 3926 set_req(Compile::AliasIdxBot, empty_mem); 3927 } 3928 } 3929 3930 if( base_memory() == empty_mem ) { 3931 progress = this; 3932 // Cut inputs during Parse phase only. 3933 // During Optimize phase a dead MergeMem node will be subsumed by Top. 3934 if( !can_reshape ) { 3935 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3936 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 3937 } 3938 } 3939 } 3940 3941 if( !progress && base_memory()->is_Phi() && can_reshape ) { 3942 // Check if PhiNode::Ideal's "Split phis through memory merges" 3943 // transform should be attempted. Look for this->phi->this cycle. 3944 uint merge_width = req(); 3945 if (merge_width > Compile::AliasIdxRaw) { 3946 PhiNode* phi = base_memory()->as_Phi(); 3947 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 3948 if (phi->in(i) == this) { 3949 phase->is_IterGVN()->_worklist.push(phi); 3950 break; 3951 } 3952 } 3953 } 3954 } 3955 3956 assert(progress || verify_sparse(), "please, no dups of base"); 3957 return progress; 3958 } 3959 3960 //-------------------------set_base_memory------------------------------------- 3961 void MergeMemNode::set_base_memory(Node *new_base) { 3962 Node* empty_mem = empty_memory(); 3963 set_req(Compile::AliasIdxBot, new_base); 3964 assert(memory_at(req()) == new_base, "must set default memory"); 3965 // Clear out other occurrences of new_base: 3966 if (new_base != empty_mem) { 3967 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3968 if (in(i) == new_base) set_req(i, empty_mem); 3969 } 3970 } 3971 } 3972 3973 //------------------------------out_RegMask------------------------------------ 3974 const RegMask &MergeMemNode::out_RegMask() const { 3975 return RegMask::Empty; 3976 } 3977 3978 //------------------------------dump_spec-------------------------------------- 3979 #ifndef PRODUCT 3980 void MergeMemNode::dump_spec(outputStream *st) const { 3981 st->print(" {"); 3982 Node* base_mem = base_memory(); 3983 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 3984 Node* mem = memory_at(i); 3985 if (mem == base_mem) { st->print(" -"); continue; } 3986 st->print( " N%d:", mem->_idx ); 3987 Compile::current()->get_adr_type(i)->dump_on(st); 3988 } 3989 st->print(" }"); 3990 } 3991 #endif // !PRODUCT 3992 3993 3994 #ifdef ASSERT 3995 static bool might_be_same(Node* a, Node* b) { 3996 if (a == b) return true; 3997 if (!(a->is_Phi() || b->is_Phi())) return false; 3998 // phis shift around during optimization 3999 return true; // pretty stupid... 4000 } 4001 4002 // verify a narrow slice (either incoming or outgoing) 4003 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4004 if (!VerifyAliases) return; // don't bother to verify unless requested 4005 if (is_error_reported()) return; // muzzle asserts when debugging an error 4006 if (Node::in_dump()) return; // muzzle asserts when printing 4007 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4008 assert(n != NULL, ""); 4009 // Elide intervening MergeMem's 4010 while (n->is_MergeMem()) { 4011 n = n->as_MergeMem()->memory_at(alias_idx); 4012 } 4013 Compile* C = Compile::current(); 4014 const TypePtr* n_adr_type = n->adr_type(); 4015 if (n == m->empty_memory()) { 4016 // Implicit copy of base_memory() 4017 } else if (n_adr_type != TypePtr::BOTTOM) { 4018 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4019 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4020 } else { 4021 // A few places like make_runtime_call "know" that VM calls are narrow, 4022 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4023 bool expected_wide_mem = false; 4024 if (n == m->base_memory()) { 4025 expected_wide_mem = true; 4026 } else if (alias_idx == Compile::AliasIdxRaw || 4027 n == m->memory_at(Compile::AliasIdxRaw)) { 4028 expected_wide_mem = true; 4029 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4030 // memory can "leak through" calls on channels that 4031 // are write-once. Allow this also. 4032 expected_wide_mem = true; 4033 } 4034 assert(expected_wide_mem, "expected narrow slice replacement"); 4035 } 4036 } 4037 #else // !ASSERT 4038 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op 4039 #endif 4040 4041 4042 //-----------------------------memory_at--------------------------------------- 4043 Node* MergeMemNode::memory_at(uint alias_idx) const { 4044 assert(alias_idx >= Compile::AliasIdxRaw || 4045 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4046 "must avoid base_memory and AliasIdxTop"); 4047 4048 // Otherwise, it is a narrow slice. 4049 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4050 Compile *C = Compile::current(); 4051 if (is_empty_memory(n)) { 4052 // the array is sparse; empty slots are the "top" node 4053 n = base_memory(); 4054 assert(Node::in_dump() 4055 || n == NULL || n->bottom_type() == Type::TOP 4056 || n->adr_type() == NULL // address is TOP 4057 || n->adr_type() == TypePtr::BOTTOM 4058 || n->adr_type() == TypeRawPtr::BOTTOM 4059 || Compile::current()->AliasLevel() == 0, 4060 "must be a wide memory"); 4061 // AliasLevel == 0 if we are organizing the memory states manually. 4062 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4063 } else { 4064 // make sure the stored slice is sane 4065 #ifdef ASSERT 4066 if (is_error_reported() || Node::in_dump()) { 4067 } else if (might_be_same(n, base_memory())) { 4068 // Give it a pass: It is a mostly harmless repetition of the base. 4069 // This can arise normally from node subsumption during optimization. 4070 } else { 4071 verify_memory_slice(this, alias_idx, n); 4072 } 4073 #endif 4074 } 4075 return n; 4076 } 4077 4078 //---------------------------set_memory_at------------------------------------- 4079 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4080 verify_memory_slice(this, alias_idx, n); 4081 Node* empty_mem = empty_memory(); 4082 if (n == base_memory()) n = empty_mem; // collapse default 4083 uint need_req = alias_idx+1; 4084 if (req() < need_req) { 4085 if (n == empty_mem) return; // already the default, so do not grow me 4086 // grow the sparse array 4087 do { 4088 add_req(empty_mem); 4089 } while (req() < need_req); 4090 } 4091 set_req( alias_idx, n ); 4092 } 4093 4094 4095 4096 //--------------------------iteration_setup------------------------------------ 4097 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4098 if (other != NULL) { 4099 grow_to_match(other); 4100 // invariant: the finite support of mm2 is within mm->req() 4101 #ifdef ASSERT 4102 for (uint i = req(); i < other->req(); i++) { 4103 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4104 } 4105 #endif 4106 } 4107 // Replace spurious copies of base_memory by top. 4108 Node* base_mem = base_memory(); 4109 if (base_mem != NULL && !base_mem->is_top()) { 4110 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4111 if (in(i) == base_mem) 4112 set_req(i, empty_memory()); 4113 } 4114 } 4115 } 4116 4117 //---------------------------grow_to_match------------------------------------- 4118 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4119 Node* empty_mem = empty_memory(); 4120 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4121 // look for the finite support of the other memory 4122 for (uint i = other->req(); --i >= req(); ) { 4123 if (other->in(i) != empty_mem) { 4124 uint new_len = i+1; 4125 while (req() < new_len) add_req(empty_mem); 4126 break; 4127 } 4128 } 4129 } 4130 4131 //---------------------------verify_sparse------------------------------------- 4132 #ifndef PRODUCT 4133 bool MergeMemNode::verify_sparse() const { 4134 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4135 Node* base_mem = base_memory(); 4136 // The following can happen in degenerate cases, since empty==top. 4137 if (is_empty_memory(base_mem)) return true; 4138 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4139 assert(in(i) != NULL, "sane slice"); 4140 if (in(i) == base_mem) return false; // should have been the sentinel value! 4141 } 4142 return true; 4143 } 4144 4145 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4146 Node* n; 4147 n = mm->in(idx); 4148 if (mem == n) return true; // might be empty_memory() 4149 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4150 if (mem == n) return true; 4151 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4152 if (mem == n) return true; 4153 if (n == NULL) break; 4154 } 4155 return false; 4156 } 4157 #endif // !PRODUCT