memnode.cpp revision 235:9c2ecc2ffb12
1/* 2 * Copyright 1997-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 20 * CA 95054 USA or visit www.sun.com if you need additional information or 21 * have any questions. 22 * 23 */ 24 25// Portions of code courtesy of Clifford Click 26 27// Optimization - Graph Style 28 29#include "incls/_precompiled.incl" 30#include "incls/_memnode.cpp.incl" 31 32static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 33 34//============================================================================= 35uint MemNode::size_of() const { return sizeof(*this); } 36 37const TypePtr *MemNode::adr_type() const { 38 Node* adr = in(Address); 39 const TypePtr* cross_check = NULL; 40 DEBUG_ONLY(cross_check = _adr_type); 41 return calculate_adr_type(adr->bottom_type(), cross_check); 42} 43 44#ifndef PRODUCT 45void MemNode::dump_spec(outputStream *st) const { 46 if (in(Address) == NULL) return; // node is dead 47#ifndef ASSERT 48 // fake the missing field 49 const TypePtr* _adr_type = NULL; 50 if (in(Address) != NULL) 51 _adr_type = in(Address)->bottom_type()->isa_ptr(); 52#endif 53 dump_adr_type(this, _adr_type, st); 54 55 Compile* C = Compile::current(); 56 if( C->alias_type(_adr_type)->is_volatile() ) 57 st->print(" Volatile!"); 58} 59 60void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 61 st->print(" @"); 62 if (adr_type == NULL) { 63 st->print("NULL"); 64 } else { 65 adr_type->dump_on(st); 66 Compile* C = Compile::current(); 67 Compile::AliasType* atp = NULL; 68 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 69 if (atp == NULL) 70 st->print(", idx=?\?;"); 71 else if (atp->index() == Compile::AliasIdxBot) 72 st->print(", idx=Bot;"); 73 else if (atp->index() == Compile::AliasIdxTop) 74 st->print(", idx=Top;"); 75 else if (atp->index() == Compile::AliasIdxRaw) 76 st->print(", idx=Raw;"); 77 else { 78 ciField* field = atp->field(); 79 if (field) { 80 st->print(", name="); 81 field->print_name_on(st); 82 } 83 st->print(", idx=%d;", atp->index()); 84 } 85 } 86} 87 88extern void print_alias_types(); 89 90#endif 91 92Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) { 93 const TypeOopPtr *tinst = t_adr->isa_oopptr(); 94 if (tinst == NULL || !tinst->is_known_instance_field()) 95 return mchain; // don't try to optimize non-instance types 96 uint instance_id = tinst->instance_id(); 97 Node *prev = NULL; 98 Node *result = mchain; 99 while (prev != result) { 100 prev = result; 101 // skip over a call which does not affect this memory slice 102 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 103 Node *proj_in = result->in(0); 104 if (proj_in->is_Call()) { 105 CallNode *call = proj_in->as_Call(); 106 if (!call->may_modify(t_adr, phase)) { 107 result = call->in(TypeFunc::Memory); 108 } 109 } else if (proj_in->is_Initialize()) { 110 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 111 // Stop if this is the initialization for the object instance which 112 // which contains this memory slice, otherwise skip over it. 113 if (alloc != NULL && alloc->_idx != instance_id) { 114 result = proj_in->in(TypeFunc::Memory); 115 } 116 } else if (proj_in->is_MemBar()) { 117 result = proj_in->in(TypeFunc::Memory); 118 } 119 } else if (result->is_MergeMem()) { 120 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty); 121 } 122 } 123 return result; 124} 125 126Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) { 127 const TypeOopPtr *t_oop = t_adr->isa_oopptr(); 128 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field(); 129 PhaseIterGVN *igvn = phase->is_IterGVN(); 130 Node *result = mchain; 131 result = optimize_simple_memory_chain(result, t_adr, phase); 132 if (is_instance && igvn != NULL && result->is_Phi()) { 133 PhiNode *mphi = result->as_Phi(); 134 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 135 const TypePtr *t = mphi->adr_type(); 136 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 137 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 138 t->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) { 139 // clone the Phi with our address type 140 result = mphi->split_out_instance(t_adr, igvn); 141 } else { 142 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 143 } 144 } 145 return result; 146} 147 148static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 149 uint alias_idx = phase->C->get_alias_index(tp); 150 Node *mem = mmem; 151#ifdef ASSERT 152 { 153 // Check that current type is consistent with the alias index used during graph construction 154 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 155 bool consistent = adr_check == NULL || adr_check->empty() || 156 phase->C->must_alias(adr_check, alias_idx ); 157 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 158 if( !consistent && adr_check != NULL && !adr_check->empty() && 159 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 160 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 161 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 162 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 163 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 164 // don't assert if it is dead code. 165 consistent = true; 166 } 167 if( !consistent ) { 168 st->print("alias_idx==%d, adr_check==", alias_idx); 169 if( adr_check == NULL ) { 170 st->print("NULL"); 171 } else { 172 adr_check->dump(); 173 } 174 st->cr(); 175 print_alias_types(); 176 assert(consistent, "adr_check must match alias idx"); 177 } 178 } 179#endif 180 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally 181 // means an array I have not precisely typed yet. Do not do any 182 // alias stuff with it any time soon. 183 const TypeOopPtr *tinst = tp->isa_oopptr(); 184 if( tp->base() != Type::AnyPtr && 185 !(tinst && 186 tinst->klass()->is_java_lang_Object() && 187 tinst->offset() == Type::OffsetBot) ) { 188 // compress paths and change unreachable cycles to TOP 189 // If not, we can update the input infinitely along a MergeMem cycle 190 // Equivalent code in PhiNode::Ideal 191 Node* m = phase->transform(mmem); 192 // If tranformed to a MergeMem, get the desired slice 193 // Otherwise the returned node represents memory for every slice 194 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 195 // Update input if it is progress over what we have now 196 } 197 return mem; 198} 199 200//--------------------------Ideal_common--------------------------------------- 201// Look for degenerate control and memory inputs. Bypass MergeMem inputs. 202// Unhook non-raw memories from complete (macro-expanded) initializations. 203Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 204 // If our control input is a dead region, kill all below the region 205 Node *ctl = in(MemNode::Control); 206 if (ctl && remove_dead_region(phase, can_reshape)) 207 return this; 208 209 // Ignore if memory is dead, or self-loop 210 Node *mem = in(MemNode::Memory); 211 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL 212 assert( mem != this, "dead loop in MemNode::Ideal" ); 213 214 Node *address = in(MemNode::Address); 215 const Type *t_adr = phase->type( address ); 216 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL 217 218 // Avoid independent memory operations 219 Node* old_mem = mem; 220 221 // The code which unhooks non-raw memories from complete (macro-expanded) 222 // initializations was removed. After macro-expansion all stores catched 223 // by Initialize node became raw stores and there is no information 224 // which memory slices they modify. So it is unsafe to move any memory 225 // operation above these stores. Also in most cases hooked non-raw memories 226 // were already unhooked by using information from detect_ptr_independence() 227 // and find_previous_store(). 228 229 if (mem->is_MergeMem()) { 230 MergeMemNode* mmem = mem->as_MergeMem(); 231 const TypePtr *tp = t_adr->is_ptr(); 232 233 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 234 } 235 236 if (mem != old_mem) { 237 set_req(MemNode::Memory, mem); 238 return this; 239 } 240 241 // let the subclass continue analyzing... 242 return NULL; 243} 244 245// Helper function for proving some simple control dominations. 246// Attempt to prove that all control inputs of 'dom' dominate 'sub'. 247// Already assumes that 'dom' is available at 'sub', and that 'sub' 248// is not a constant (dominated by the method's StartNode). 249// Used by MemNode::find_previous_store to prove that the 250// control input of a memory operation predates (dominates) 251// an allocation it wants to look past. 252bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 253 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 254 return false; // Conservative answer for dead code 255 256 // Check 'dom'. Skip Proj and CatchProj nodes. 257 dom = dom->find_exact_control(dom); 258 if (dom == NULL || dom->is_top()) 259 return false; // Conservative answer for dead code 260 261 if (dom == sub) { 262 // For the case when, for example, 'sub' is Initialize and the original 263 // 'dom' is Proj node of the 'sub'. 264 return false; 265 } 266 267 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 268 return true; 269 270 // 'dom' dominates 'sub' if its control edge and control edges 271 // of all its inputs dominate or equal to sub's control edge. 272 273 // Currently 'sub' is either Allocate, Initialize or Start nodes. 274 // Or Region for the check in LoadNode::Ideal(); 275 // 'sub' should have sub->in(0) != NULL. 276 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 277 sub->is_Region(), "expecting only these nodes"); 278 279 // Get control edge of 'sub'. 280 Node* orig_sub = sub; 281 sub = sub->find_exact_control(sub->in(0)); 282 if (sub == NULL || sub->is_top()) 283 return false; // Conservative answer for dead code 284 285 assert(sub->is_CFG(), "expecting control"); 286 287 if (sub == dom) 288 return true; 289 290 if (sub->is_Start() || sub->is_Root()) 291 return false; 292 293 { 294 // Check all control edges of 'dom'. 295 296 ResourceMark rm; 297 Arena* arena = Thread::current()->resource_area(); 298 Node_List nlist(arena); 299 Unique_Node_List dom_list(arena); 300 301 dom_list.push(dom); 302 bool only_dominating_controls = false; 303 304 for (uint next = 0; next < dom_list.size(); next++) { 305 Node* n = dom_list.at(next); 306 if (n == orig_sub) 307 return false; // One of dom's inputs dominated by sub. 308 if (!n->is_CFG() && n->pinned()) { 309 // Check only own control edge for pinned non-control nodes. 310 n = n->find_exact_control(n->in(0)); 311 if (n == NULL || n->is_top()) 312 return false; // Conservative answer for dead code 313 assert(n->is_CFG(), "expecting control"); 314 dom_list.push(n); 315 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 316 only_dominating_controls = true; 317 } else if (n->is_CFG()) { 318 if (n->dominates(sub, nlist)) 319 only_dominating_controls = true; 320 else 321 return false; 322 } else { 323 // First, own control edge. 324 Node* m = n->find_exact_control(n->in(0)); 325 if (m != NULL) { 326 if (m->is_top()) 327 return false; // Conservative answer for dead code 328 dom_list.push(m); 329 } 330 // Now, the rest of edges. 331 uint cnt = n->req(); 332 for (uint i = 1; i < cnt; i++) { 333 m = n->find_exact_control(n->in(i)); 334 if (m == NULL || m->is_top()) 335 continue; 336 dom_list.push(m); 337 } 338 } 339 } 340 return only_dominating_controls; 341 } 342} 343 344//---------------------detect_ptr_independence--------------------------------- 345// Used by MemNode::find_previous_store to prove that two base 346// pointers are never equal. 347// The pointers are accompanied by their associated allocations, 348// if any, which have been previously discovered by the caller. 349bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 350 Node* p2, AllocateNode* a2, 351 PhaseTransform* phase) { 352 // Attempt to prove that these two pointers cannot be aliased. 353 // They may both manifestly be allocations, and they should differ. 354 // Or, if they are not both allocations, they can be distinct constants. 355 // Otherwise, one is an allocation and the other a pre-existing value. 356 if (a1 == NULL && a2 == NULL) { // neither an allocation 357 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 358 } else if (a1 != NULL && a2 != NULL) { // both allocations 359 return (a1 != a2); 360 } else if (a1 != NULL) { // one allocation a1 361 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 362 return all_controls_dominate(p2, a1); 363 } else { //(a2 != NULL) // one allocation a2 364 return all_controls_dominate(p1, a2); 365 } 366 return false; 367} 368 369 370// The logic for reordering loads and stores uses four steps: 371// (a) Walk carefully past stores and initializations which we 372// can prove are independent of this load. 373// (b) Observe that the next memory state makes an exact match 374// with self (load or store), and locate the relevant store. 375// (c) Ensure that, if we were to wire self directly to the store, 376// the optimizer would fold it up somehow. 377// (d) Do the rewiring, and return, depending on some other part of 378// the optimizer to fold up the load. 379// This routine handles steps (a) and (b). Steps (c) and (d) are 380// specific to loads and stores, so they are handled by the callers. 381// (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 382// 383Node* MemNode::find_previous_store(PhaseTransform* phase) { 384 Node* ctrl = in(MemNode::Control); 385 Node* adr = in(MemNode::Address); 386 intptr_t offset = 0; 387 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 388 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 389 390 if (offset == Type::OffsetBot) 391 return NULL; // cannot unalias unless there are precise offsets 392 393 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 394 395 intptr_t size_in_bytes = memory_size(); 396 397 Node* mem = in(MemNode::Memory); // start searching here... 398 399 int cnt = 50; // Cycle limiter 400 for (;;) { // While we can dance past unrelated stores... 401 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 402 403 if (mem->is_Store()) { 404 Node* st_adr = mem->in(MemNode::Address); 405 intptr_t st_offset = 0; 406 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 407 if (st_base == NULL) 408 break; // inscrutable pointer 409 if (st_offset != offset && st_offset != Type::OffsetBot) { 410 const int MAX_STORE = BytesPerLong; 411 if (st_offset >= offset + size_in_bytes || 412 st_offset <= offset - MAX_STORE || 413 st_offset <= offset - mem->as_Store()->memory_size()) { 414 // Success: The offsets are provably independent. 415 // (You may ask, why not just test st_offset != offset and be done? 416 // The answer is that stores of different sizes can co-exist 417 // in the same sequence of RawMem effects. We sometimes initialize 418 // a whole 'tile' of array elements with a single jint or jlong.) 419 mem = mem->in(MemNode::Memory); 420 continue; // (a) advance through independent store memory 421 } 422 } 423 if (st_base != base && 424 detect_ptr_independence(base, alloc, 425 st_base, 426 AllocateNode::Ideal_allocation(st_base, phase), 427 phase)) { 428 // Success: The bases are provably independent. 429 mem = mem->in(MemNode::Memory); 430 continue; // (a) advance through independent store memory 431 } 432 433 // (b) At this point, if the bases or offsets do not agree, we lose, 434 // since we have not managed to prove 'this' and 'mem' independent. 435 if (st_base == base && st_offset == offset) { 436 return mem; // let caller handle steps (c), (d) 437 } 438 439 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 440 InitializeNode* st_init = mem->in(0)->as_Initialize(); 441 AllocateNode* st_alloc = st_init->allocation(); 442 if (st_alloc == NULL) 443 break; // something degenerated 444 bool known_identical = false; 445 bool known_independent = false; 446 if (alloc == st_alloc) 447 known_identical = true; 448 else if (alloc != NULL) 449 known_independent = true; 450 else if (all_controls_dominate(this, st_alloc)) 451 known_independent = true; 452 453 if (known_independent) { 454 // The bases are provably independent: Either they are 455 // manifestly distinct allocations, or else the control 456 // of this load dominates the store's allocation. 457 int alias_idx = phase->C->get_alias_index(adr_type()); 458 if (alias_idx == Compile::AliasIdxRaw) { 459 mem = st_alloc->in(TypeFunc::Memory); 460 } else { 461 mem = st_init->memory(alias_idx); 462 } 463 continue; // (a) advance through independent store memory 464 } 465 466 // (b) at this point, if we are not looking at a store initializing 467 // the same allocation we are loading from, we lose. 468 if (known_identical) { 469 // From caller, can_see_stored_value will consult find_captured_store. 470 return mem; // let caller handle steps (c), (d) 471 } 472 473 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 474 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 475 if (mem->is_Proj() && mem->in(0)->is_Call()) { 476 CallNode *call = mem->in(0)->as_Call(); 477 if (!call->may_modify(addr_t, phase)) { 478 mem = call->in(TypeFunc::Memory); 479 continue; // (a) advance through independent call memory 480 } 481 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 482 mem = mem->in(0)->in(TypeFunc::Memory); 483 continue; // (a) advance through independent MemBar memory 484 } else if (mem->is_MergeMem()) { 485 int alias_idx = phase->C->get_alias_index(adr_type()); 486 mem = mem->as_MergeMem()->memory_at(alias_idx); 487 continue; // (a) advance through independent MergeMem memory 488 } 489 } 490 491 // Unless there is an explicit 'continue', we must bail out here, 492 // because 'mem' is an inscrutable memory state (e.g., a call). 493 break; 494 } 495 496 return NULL; // bail out 497} 498 499//----------------------calculate_adr_type------------------------------------- 500// Helper function. Notices when the given type of address hits top or bottom. 501// Also, asserts a cross-check of the type against the expected address type. 502const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 503 if (t == Type::TOP) return NULL; // does not touch memory any more? 504 #ifdef PRODUCT 505 cross_check = NULL; 506 #else 507 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL; 508 #endif 509 const TypePtr* tp = t->isa_ptr(); 510 if (tp == NULL) { 511 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 512 return TypePtr::BOTTOM; // touches lots of memory 513 } else { 514 #ifdef ASSERT 515 // %%%% [phh] We don't check the alias index if cross_check is 516 // TypeRawPtr::BOTTOM. Needs to be investigated. 517 if (cross_check != NULL && 518 cross_check != TypePtr::BOTTOM && 519 cross_check != TypeRawPtr::BOTTOM) { 520 // Recheck the alias index, to see if it has changed (due to a bug). 521 Compile* C = Compile::current(); 522 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 523 "must stay in the original alias category"); 524 // The type of the address must be contained in the adr_type, 525 // disregarding "null"-ness. 526 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 527 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 528 assert(cross_check->meet(tp_notnull) == cross_check, 529 "real address must not escape from expected memory type"); 530 } 531 #endif 532 return tp; 533 } 534} 535 536//------------------------adr_phi_is_loop_invariant---------------------------- 537// A helper function for Ideal_DU_postCCP to check if a Phi in a counted 538// loop is loop invariant. Make a quick traversal of Phi and associated 539// CastPP nodes, looking to see if they are a closed group within the loop. 540bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) { 541 // The idea is that the phi-nest must boil down to only CastPP nodes 542 // with the same data. This implies that any path into the loop already 543 // includes such a CastPP, and so the original cast, whatever its input, 544 // must be covered by an equivalent cast, with an earlier control input. 545 ResourceMark rm; 546 547 // The loop entry input of the phi should be the unique dominating 548 // node for every Phi/CastPP in the loop. 549 Unique_Node_List closure; 550 closure.push(adr_phi->in(LoopNode::EntryControl)); 551 552 // Add the phi node and the cast to the worklist. 553 Unique_Node_List worklist; 554 worklist.push(adr_phi); 555 if( cast != NULL ){ 556 if( !cast->is_ConstraintCast() ) return false; 557 worklist.push(cast); 558 } 559 560 // Begin recursive walk of phi nodes. 561 while( worklist.size() ){ 562 // Take a node off the worklist 563 Node *n = worklist.pop(); 564 if( !closure.member(n) ){ 565 // Add it to the closure. 566 closure.push(n); 567 // Make a sanity check to ensure we don't waste too much time here. 568 if( closure.size() > 20) return false; 569 // This node is OK if: 570 // - it is a cast of an identical value 571 // - or it is a phi node (then we add its inputs to the worklist) 572 // Otherwise, the node is not OK, and we presume the cast is not invariant 573 if( n->is_ConstraintCast() ){ 574 worklist.push(n->in(1)); 575 } else if( n->is_Phi() ) { 576 for( uint i = 1; i < n->req(); i++ ) { 577 worklist.push(n->in(i)); 578 } 579 } else { 580 return false; 581 } 582 } 583 } 584 585 // Quit when the worklist is empty, and we've found no offending nodes. 586 return true; 587} 588 589//------------------------------Ideal_DU_postCCP------------------------------- 590// Find any cast-away of null-ness and keep its control. Null cast-aways are 591// going away in this pass and we need to make this memory op depend on the 592// gating null check. 593Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) { 594 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address)); 595} 596 597// I tried to leave the CastPP's in. This makes the graph more accurate in 598// some sense; we get to keep around the knowledge that an oop is not-null 599// after some test. Alas, the CastPP's interfere with GVN (some values are 600// the regular oop, some are the CastPP of the oop, all merge at Phi's which 601// cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed 602// some of the more trivial cases in the optimizer. Removing more useless 603// Phi's started allowing Loads to illegally float above null checks. I gave 604// up on this approach. CNC 10/20/2000 605// This static method may be called not from MemNode (EncodePNode calls it). 606// Only the control edge of the node 'n' might be updated. 607Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) { 608 Node *skipped_cast = NULL; 609 // Need a null check? Regular static accesses do not because they are 610 // from constant addresses. Array ops are gated by the range check (which 611 // always includes a NULL check). Just check field ops. 612 if( n->in(MemNode::Control) == NULL ) { 613 // Scan upwards for the highest location we can place this memory op. 614 while( true ) { 615 switch( adr->Opcode() ) { 616 617 case Op_AddP: // No change to NULL-ness, so peek thru AddP's 618 adr = adr->in(AddPNode::Base); 619 continue; 620 621 case Op_DecodeN: // No change to NULL-ness, so peek thru 622 adr = adr->in(1); 623 continue; 624 625 case Op_CastPP: 626 // If the CastPP is useless, just peek on through it. 627 if( ccp->type(adr) == ccp->type(adr->in(1)) ) { 628 // Remember the cast that we've peeked though. If we peek 629 // through more than one, then we end up remembering the highest 630 // one, that is, if in a loop, the one closest to the top. 631 skipped_cast = adr; 632 adr = adr->in(1); 633 continue; 634 } 635 // CastPP is going away in this pass! We need this memory op to be 636 // control-dependent on the test that is guarding the CastPP. 637 ccp->hash_delete(n); 638 n->set_req(MemNode::Control, adr->in(0)); 639 ccp->hash_insert(n); 640 return n; 641 642 case Op_Phi: 643 // Attempt to float above a Phi to some dominating point. 644 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) { 645 // If we've already peeked through a Cast (which could have set the 646 // control), we can't float above a Phi, because the skipped Cast 647 // may not be loop invariant. 648 if (adr_phi_is_loop_invariant(adr, skipped_cast)) { 649 adr = adr->in(1); 650 continue; 651 } 652 } 653 654 // Intentional fallthrough! 655 656 // No obvious dominating point. The mem op is pinned below the Phi 657 // by the Phi itself. If the Phi goes away (no true value is merged) 658 // then the mem op can float, but not indefinitely. It must be pinned 659 // behind the controls leading to the Phi. 660 case Op_CheckCastPP: 661 // These usually stick around to change address type, however a 662 // useless one can be elided and we still need to pick up a control edge 663 if (adr->in(0) == NULL) { 664 // This CheckCastPP node has NO control and is likely useless. But we 665 // need check further up the ancestor chain for a control input to keep 666 // the node in place. 4959717. 667 skipped_cast = adr; 668 adr = adr->in(1); 669 continue; 670 } 671 ccp->hash_delete(n); 672 n->set_req(MemNode::Control, adr->in(0)); 673 ccp->hash_insert(n); 674 return n; 675 676 // List of "safe" opcodes; those that implicitly block the memory 677 // op below any null check. 678 case Op_CastX2P: // no null checks on native pointers 679 case Op_Parm: // 'this' pointer is not null 680 case Op_LoadP: // Loading from within a klass 681 case Op_LoadN: // Loading from within a klass 682 case Op_LoadKlass: // Loading from within a klass 683 case Op_LoadNKlass: // Loading from within a klass 684 case Op_ConP: // Loading from a klass 685 case Op_ConN: // Loading from a klass 686 case Op_CreateEx: // Sucking up the guts of an exception oop 687 case Op_Con: // Reading from TLS 688 case Op_CMoveP: // CMoveP is pinned 689 case Op_CMoveN: // CMoveN is pinned 690 break; // No progress 691 692 case Op_Proj: // Direct call to an allocation routine 693 case Op_SCMemProj: // Memory state from store conditional ops 694#ifdef ASSERT 695 { 696 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value"); 697 const Node* call = adr->in(0); 698 if (call->is_CallJava()) { 699 const CallJavaNode* call_java = call->as_CallJava(); 700 const TypeTuple *r = call_java->tf()->range(); 701 assert(r->cnt() > TypeFunc::Parms, "must return value"); 702 const Type* ret_type = r->field_at(TypeFunc::Parms); 703 assert(ret_type && ret_type->isa_ptr(), "must return pointer"); 704 // We further presume that this is one of 705 // new_instance_Java, new_array_Java, or 706 // the like, but do not assert for this. 707 } else if (call->is_Allocate()) { 708 // similar case to new_instance_Java, etc. 709 } else if (!call->is_CallLeaf()) { 710 // Projections from fetch_oop (OSR) are allowed as well. 711 ShouldNotReachHere(); 712 } 713 } 714#endif 715 break; 716 default: 717 ShouldNotReachHere(); 718 } 719 break; 720 } 721 } 722 723 return NULL; // No progress 724} 725 726 727//============================================================================= 728uint LoadNode::size_of() const { return sizeof(*this); } 729uint LoadNode::cmp( const Node &n ) const 730{ return !Type::cmp( _type, ((LoadNode&)n)._type ); } 731const Type *LoadNode::bottom_type() const { return _type; } 732uint LoadNode::ideal_reg() const { 733 return Matcher::base2reg[_type->base()]; 734} 735 736#ifndef PRODUCT 737void LoadNode::dump_spec(outputStream *st) const { 738 MemNode::dump_spec(st); 739 if( !Verbose && !WizardMode ) { 740 // standard dump does this in Verbose and WizardMode 741 st->print(" #"); _type->dump_on(st); 742 } 743} 744#endif 745 746 747//----------------------------LoadNode::make----------------------------------- 748// Polymorphic factory method: 749Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) { 750 Compile* C = gvn.C; 751 752 // sanity check the alias category against the created node type 753 assert(!(adr_type->isa_oopptr() && 754 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 755 "use LoadKlassNode instead"); 756 assert(!(adr_type->isa_aryptr() && 757 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 758 "use LoadRangeNode instead"); 759 switch (bt) { 760 case T_BOOLEAN: 761 case T_BYTE: return new (C, 3) LoadBNode(ctl, mem, adr, adr_type, rt->is_int() ); 762 case T_INT: return new (C, 3) LoadINode(ctl, mem, adr, adr_type, rt->is_int() ); 763 case T_CHAR: return new (C, 3) LoadCNode(ctl, mem, adr, adr_type, rt->is_int() ); 764 case T_SHORT: return new (C, 3) LoadSNode(ctl, mem, adr, adr_type, rt->is_int() ); 765 case T_LONG: return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long() ); 766 case T_FLOAT: return new (C, 3) LoadFNode(ctl, mem, adr, adr_type, rt ); 767 case T_DOUBLE: return new (C, 3) LoadDNode(ctl, mem, adr, adr_type, rt ); 768 case T_ADDRESS: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr() ); 769 case T_OBJECT: 770#ifdef _LP64 771 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 772 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop())); 773 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr()); 774 } else 775#endif 776 { 777 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 778 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr()); 779 } 780 } 781 ShouldNotReachHere(); 782 return (LoadNode*)NULL; 783} 784 785LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) { 786 bool require_atomic = true; 787 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic); 788} 789 790 791 792 793//------------------------------hash------------------------------------------- 794uint LoadNode::hash() const { 795 // unroll addition of interesting fields 796 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 797} 798 799//---------------------------can_see_stored_value------------------------------ 800// This routine exists to make sure this set of tests is done the same 801// everywhere. We need to make a coordinated change: first LoadNode::Ideal 802// will change the graph shape in a way which makes memory alive twice at the 803// same time (uses the Oracle model of aliasing), then some 804// LoadXNode::Identity will fold things back to the equivalence-class model 805// of aliasing. 806Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 807 Node* ld_adr = in(MemNode::Address); 808 809 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 810 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL; 811 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw && 812 atp->field() != NULL && !atp->field()->is_volatile()) { 813 uint alias_idx = atp->index(); 814 bool final = atp->field()->is_final(); 815 Node* result = NULL; 816 Node* current = st; 817 // Skip through chains of MemBarNodes checking the MergeMems for 818 // new states for the slice of this load. Stop once any other 819 // kind of node is encountered. Loads from final memory can skip 820 // through any kind of MemBar but normal loads shouldn't skip 821 // through MemBarAcquire since the could allow them to move out of 822 // a synchronized region. 823 while (current->is_Proj()) { 824 int opc = current->in(0)->Opcode(); 825 if ((final && opc == Op_MemBarAcquire) || 826 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) { 827 Node* mem = current->in(0)->in(TypeFunc::Memory); 828 if (mem->is_MergeMem()) { 829 MergeMemNode* merge = mem->as_MergeMem(); 830 Node* new_st = merge->memory_at(alias_idx); 831 if (new_st == merge->base_memory()) { 832 // Keep searching 833 current = merge->base_memory(); 834 continue; 835 } 836 // Save the new memory state for the slice and fall through 837 // to exit. 838 result = new_st; 839 } 840 } 841 break; 842 } 843 if (result != NULL) { 844 st = result; 845 } 846 } 847 848 849 // Loop around twice in the case Load -> Initialize -> Store. 850 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 851 for (int trip = 0; trip <= 1; trip++) { 852 853 if (st->is_Store()) { 854 Node* st_adr = st->in(MemNode::Address); 855 if (!phase->eqv(st_adr, ld_adr)) { 856 // Try harder before giving up... Match raw and non-raw pointers. 857 intptr_t st_off = 0; 858 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 859 if (alloc == NULL) return NULL; 860 intptr_t ld_off = 0; 861 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 862 if (alloc != allo2) return NULL; 863 if (ld_off != st_off) return NULL; 864 // At this point we have proven something like this setup: 865 // A = Allocate(...) 866 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 867 // S = StoreQ(, AddP(, A.Parm , #Off), V) 868 // (Actually, we haven't yet proven the Q's are the same.) 869 // In other words, we are loading from a casted version of 870 // the same pointer-and-offset that we stored to. 871 // Thus, we are able to replace L by V. 872 } 873 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 874 if (store_Opcode() != st->Opcode()) 875 return NULL; 876 return st->in(MemNode::ValueIn); 877 } 878 879 intptr_t offset = 0; // scratch 880 881 // A load from a freshly-created object always returns zero. 882 // (This can happen after LoadNode::Ideal resets the load's memory input 883 // to find_captured_store, which returned InitializeNode::zero_memory.) 884 if (st->is_Proj() && st->in(0)->is_Allocate() && 885 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) && 886 offset >= st->in(0)->as_Allocate()->minimum_header_size()) { 887 // return a zero value for the load's basic type 888 // (This is one of the few places where a generic PhaseTransform 889 // can create new nodes. Think of it as lazily manifesting 890 // virtually pre-existing constants.) 891 return phase->zerocon(memory_type()); 892 } 893 894 // A load from an initialization barrier can match a captured store. 895 if (st->is_Proj() && st->in(0)->is_Initialize()) { 896 InitializeNode* init = st->in(0)->as_Initialize(); 897 AllocateNode* alloc = init->allocation(); 898 if (alloc != NULL && 899 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) { 900 // examine a captured store value 901 st = init->find_captured_store(offset, memory_size(), phase); 902 if (st != NULL) 903 continue; // take one more trip around 904 } 905 } 906 907 break; 908 } 909 910 return NULL; 911} 912 913//----------------------is_instance_field_load_with_local_phi------------------ 914bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 915 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl && 916 in(MemNode::Address)->is_AddP() ) { 917 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr(); 918 // Only instances. 919 if( t_oop != NULL && t_oop->is_known_instance_field() && 920 t_oop->offset() != Type::OffsetBot && 921 t_oop->offset() != Type::OffsetTop) { 922 return true; 923 } 924 } 925 return false; 926} 927 928//------------------------------Identity--------------------------------------- 929// Loads are identity if previous store is to same address 930Node *LoadNode::Identity( PhaseTransform *phase ) { 931 // If the previous store-maker is the right kind of Store, and the store is 932 // to the same address, then we are equal to the value stored. 933 Node* mem = in(MemNode::Memory); 934 Node* value = can_see_stored_value(mem, phase); 935 if( value ) { 936 // byte, short & char stores truncate naturally. 937 // A load has to load the truncated value which requires 938 // some sort of masking operation and that requires an 939 // Ideal call instead of an Identity call. 940 if (memory_size() < BytesPerInt) { 941 // If the input to the store does not fit with the load's result type, 942 // it must be truncated via an Ideal call. 943 if (!phase->type(value)->higher_equal(phase->type(this))) 944 return this; 945 } 946 // (This works even when value is a Con, but LoadNode::Value 947 // usually runs first, producing the singleton type of the Con.) 948 return value; 949 } 950 951 // Search for an existing data phi which was generated before for the same 952 // instance's field to avoid infinite genertion of phis in a loop. 953 Node *region = mem->in(0); 954 if (is_instance_field_load_with_local_phi(region)) { 955 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr(); 956 int this_index = phase->C->get_alias_index(addr_t); 957 int this_offset = addr_t->offset(); 958 int this_id = addr_t->is_oopptr()->instance_id(); 959 const Type* this_type = bottom_type(); 960 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 961 Node* phi = region->fast_out(i); 962 if (phi->is_Phi() && phi != mem && 963 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) { 964 return phi; 965 } 966 } 967 } 968 969 return this; 970} 971 972 973// Returns true if the AliasType refers to the field that holds the 974// cached box array. Currently only handles the IntegerCache case. 975static bool is_autobox_cache(Compile::AliasType* atp) { 976 if (atp != NULL && atp->field() != NULL) { 977 ciField* field = atp->field(); 978 ciSymbol* klass = field->holder()->name(); 979 if (field->name() == ciSymbol::cache_field_name() && 980 field->holder()->uses_default_loader() && 981 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 982 return true; 983 } 984 } 985 return false; 986} 987 988// Fetch the base value in the autobox array 989static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) { 990 if (atp != NULL && atp->field() != NULL) { 991 ciField* field = atp->field(); 992 ciSymbol* klass = field->holder()->name(); 993 if (field->name() == ciSymbol::cache_field_name() && 994 field->holder()->uses_default_loader() && 995 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 996 assert(field->is_constant(), "what?"); 997 ciObjArray* array = field->constant_value().as_object()->as_obj_array(); 998 // Fetch the box object at the base of the array and get its value 999 ciInstance* box = array->obj_at(0)->as_instance(); 1000 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1001 if (ik->nof_nonstatic_fields() == 1) { 1002 // This should be true nonstatic_field_at requires calling 1003 // nof_nonstatic_fields so check it anyway 1004 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1005 cache_offset = c.as_int(); 1006 } 1007 return true; 1008 } 1009 } 1010 return false; 1011} 1012 1013// Returns true if the AliasType refers to the value field of an 1014// autobox object. Currently only handles Integer. 1015static bool is_autobox_object(Compile::AliasType* atp) { 1016 if (atp != NULL && atp->field() != NULL) { 1017 ciField* field = atp->field(); 1018 ciSymbol* klass = field->holder()->name(); 1019 if (field->name() == ciSymbol::value_name() && 1020 field->holder()->uses_default_loader() && 1021 klass == ciSymbol::java_lang_Integer()) { 1022 return true; 1023 } 1024 } 1025 return false; 1026} 1027 1028 1029// We're loading from an object which has autobox behaviour. 1030// If this object is result of a valueOf call we'll have a phi 1031// merging a newly allocated object and a load from the cache. 1032// We want to replace this load with the original incoming 1033// argument to the valueOf call. 1034Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1035 Node* base = in(Address)->in(AddPNode::Base); 1036 if (base->is_Phi() && base->req() == 3) { 1037 AllocateNode* allocation = NULL; 1038 int allocation_index = -1; 1039 int load_index = -1; 1040 for (uint i = 1; i < base->req(); i++) { 1041 allocation = AllocateNode::Ideal_allocation(base->in(i), phase); 1042 if (allocation != NULL) { 1043 allocation_index = i; 1044 load_index = 3 - allocation_index; 1045 break; 1046 } 1047 } 1048 LoadNode* load = NULL; 1049 if (allocation != NULL && base->in(load_index)->is_Load()) { 1050 load = base->in(load_index)->as_Load(); 1051 } 1052 if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) { 1053 // Push the loads from the phi that comes from valueOf up 1054 // through it to allow elimination of the loads and the recovery 1055 // of the original value. 1056 Node* mem_phi = in(Memory); 1057 Node* offset = in(Address)->in(AddPNode::Offset); 1058 1059 Node* in1 = clone(); 1060 Node* in1_addr = in1->in(Address)->clone(); 1061 in1_addr->set_req(AddPNode::Base, base->in(allocation_index)); 1062 in1_addr->set_req(AddPNode::Address, base->in(allocation_index)); 1063 in1_addr->set_req(AddPNode::Offset, offset); 1064 in1->set_req(0, base->in(allocation_index)); 1065 in1->set_req(Address, in1_addr); 1066 in1->set_req(Memory, mem_phi->in(allocation_index)); 1067 1068 Node* in2 = clone(); 1069 Node* in2_addr = in2->in(Address)->clone(); 1070 in2_addr->set_req(AddPNode::Base, base->in(load_index)); 1071 in2_addr->set_req(AddPNode::Address, base->in(load_index)); 1072 in2_addr->set_req(AddPNode::Offset, offset); 1073 in2->set_req(0, base->in(load_index)); 1074 in2->set_req(Address, in2_addr); 1075 in2->set_req(Memory, mem_phi->in(load_index)); 1076 1077 in1_addr = phase->transform(in1_addr); 1078 in1 = phase->transform(in1); 1079 in2_addr = phase->transform(in2_addr); 1080 in2 = phase->transform(in2); 1081 1082 PhiNode* result = PhiNode::make_blank(base->in(0), this); 1083 result->set_req(allocation_index, in1); 1084 result->set_req(load_index, in2); 1085 return result; 1086 } 1087 } else if (base->is_Load()) { 1088 // Eliminate the load of Integer.value for integers from the cache 1089 // array by deriving the value from the index into the array. 1090 // Capture the offset of the load and then reverse the computation. 1091 Node* load_base = base->in(Address)->in(AddPNode::Base); 1092 if (load_base != NULL) { 1093 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type()); 1094 intptr_t cache_offset; 1095 int shift = -1; 1096 Node* cache = NULL; 1097 if (is_autobox_cache(atp)) { 1098 shift = exact_log2(type2aelembytes(T_OBJECT)); 1099 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset); 1100 } 1101 if (cache != NULL && base->in(Address)->is_AddP()) { 1102 Node* elements[4]; 1103 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements)); 1104 int cache_low; 1105 if (count > 0 && fetch_autobox_base(atp, cache_low)) { 1106 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift); 1107 // Add up all the offsets making of the address of the load 1108 Node* result = elements[0]; 1109 for (int i = 1; i < count; i++) { 1110 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i])); 1111 } 1112 // Remove the constant offset from the address and then 1113 // remove the scaling of the offset to recover the original index. 1114 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset))); 1115 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1116 // Peel the shift off directly but wrap it in a dummy node 1117 // since Ideal can't return existing nodes 1118 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0)); 1119 } else { 1120 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift)); 1121 } 1122#ifdef _LP64 1123 result = new (phase->C, 2) ConvL2INode(phase->transform(result)); 1124#endif 1125 return result; 1126 } 1127 } 1128 } 1129 } 1130 return NULL; 1131} 1132 1133//------------------------------split_through_phi------------------------------ 1134// Split instance field load through Phi. 1135Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1136 Node* mem = in(MemNode::Memory); 1137 Node* address = in(MemNode::Address); 1138 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1139 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1140 1141 assert(mem->is_Phi() && (t_oop != NULL) && 1142 t_oop->is_known_instance_field(), "invalide conditions"); 1143 1144 Node *region = mem->in(0); 1145 if (region == NULL) { 1146 return NULL; // Wait stable graph 1147 } 1148 uint cnt = mem->req(); 1149 for( uint i = 1; i < cnt; i++ ) { 1150 Node *in = mem->in(i); 1151 if( in == NULL ) { 1152 return NULL; // Wait stable graph 1153 } 1154 } 1155 // Check for loop invariant. 1156 if (cnt == 3) { 1157 for( uint i = 1; i < cnt; i++ ) { 1158 Node *in = mem->in(i); 1159 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase); 1160 if (m == mem) { 1161 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi. 1162 return this; 1163 } 1164 } 1165 } 1166 // Split through Phi (see original code in loopopts.cpp). 1167 assert(phase->C->have_alias_type(addr_t), "instance should have alias type"); 1168 1169 // Do nothing here if Identity will find a value 1170 // (to avoid infinite chain of value phis generation). 1171 if ( !phase->eqv(this, this->Identity(phase)) ) 1172 return NULL; 1173 1174 // Skip the split if the region dominates some control edge of the address. 1175 if (cnt == 3 && !MemNode::all_controls_dominate(address, region)) 1176 return NULL; 1177 1178 const Type* this_type = this->bottom_type(); 1179 int this_index = phase->C->get_alias_index(addr_t); 1180 int this_offset = addr_t->offset(); 1181 int this_iid = addr_t->is_oopptr()->instance_id(); 1182 int wins = 0; 1183 PhaseIterGVN *igvn = phase->is_IterGVN(); 1184 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset); 1185 for( uint i = 1; i < region->req(); i++ ) { 1186 Node *x; 1187 Node* the_clone = NULL; 1188 if( region->in(i) == phase->C->top() ) { 1189 x = phase->C->top(); // Dead path? Use a dead data op 1190 } else { 1191 x = this->clone(); // Else clone up the data op 1192 the_clone = x; // Remember for possible deletion. 1193 // Alter data node to use pre-phi inputs 1194 if( this->in(0) == region ) { 1195 x->set_req( 0, region->in(i) ); 1196 } else { 1197 x->set_req( 0, NULL ); 1198 } 1199 for( uint j = 1; j < this->req(); j++ ) { 1200 Node *in = this->in(j); 1201 if( in->is_Phi() && in->in(0) == region ) 1202 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone 1203 } 1204 } 1205 // Check for a 'win' on some paths 1206 const Type *t = x->Value(igvn); 1207 1208 bool singleton = t->singleton(); 1209 1210 // See comments in PhaseIdealLoop::split_thru_phi(). 1211 if( singleton && t == Type::TOP ) { 1212 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1213 } 1214 1215 if( singleton ) { 1216 wins++; 1217 x = igvn->makecon(t); 1218 } else { 1219 // We now call Identity to try to simplify the cloned node. 1220 // Note that some Identity methods call phase->type(this). 1221 // Make sure that the type array is big enough for 1222 // our new node, even though we may throw the node away. 1223 // (This tweaking with igvn only works because x is a new node.) 1224 igvn->set_type(x, t); 1225 Node *y = x->Identity(igvn); 1226 if( y != x ) { 1227 wins++; 1228 x = y; 1229 } else { 1230 y = igvn->hash_find(x); 1231 if( y ) { 1232 wins++; 1233 x = y; 1234 } else { 1235 // Else x is a new node we are keeping 1236 // We do not need register_new_node_with_optimizer 1237 // because set_type has already been called. 1238 igvn->_worklist.push(x); 1239 } 1240 } 1241 } 1242 if (x != the_clone && the_clone != NULL) 1243 igvn->remove_dead_node(the_clone); 1244 phi->set_req(i, x); 1245 } 1246 if( wins > 0 ) { 1247 // Record Phi 1248 igvn->register_new_node_with_optimizer(phi); 1249 return phi; 1250 } 1251 igvn->remove_dead_node(phi); 1252 return NULL; 1253} 1254 1255//------------------------------Ideal------------------------------------------ 1256// If the load is from Field memory and the pointer is non-null, we can 1257// zero out the control input. 1258// If the offset is constant and the base is an object allocation, 1259// try to hook me up to the exact initializing store. 1260Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1261 Node* p = MemNode::Ideal_common(phase, can_reshape); 1262 if (p) return (p == NodeSentinel) ? NULL : p; 1263 1264 Node* ctrl = in(MemNode::Control); 1265 Node* address = in(MemNode::Address); 1266 1267 // Skip up past a SafePoint control. Cannot do this for Stores because 1268 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1269 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1270 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1271 ctrl = ctrl->in(0); 1272 set_req(MemNode::Control,ctrl); 1273 } 1274 1275 // Check for useless control edge in some common special cases 1276 if (in(MemNode::Control) != NULL) { 1277 intptr_t ignore = 0; 1278 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1279 if (base != NULL 1280 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1281 && all_controls_dominate(base, phase->C->start())) { 1282 // A method-invariant, non-null address (constant or 'this' argument). 1283 set_req(MemNode::Control, NULL); 1284 } 1285 } 1286 1287 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) { 1288 Node* base = in(Address)->in(AddPNode::Base); 1289 if (base != NULL) { 1290 Compile::AliasType* atp = phase->C->alias_type(adr_type()); 1291 if (is_autobox_object(atp)) { 1292 Node* result = eliminate_autobox(phase); 1293 if (result != NULL) return result; 1294 } 1295 } 1296 } 1297 1298 Node* mem = in(MemNode::Memory); 1299 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1300 1301 if (addr_t != NULL) { 1302 // try to optimize our memory input 1303 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase); 1304 if (opt_mem != mem) { 1305 set_req(MemNode::Memory, opt_mem); 1306 return this; 1307 } 1308 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1309 if (can_reshape && opt_mem->is_Phi() && 1310 (t_oop != NULL) && t_oop->is_known_instance_field()) { 1311 // Split instance field load through Phi. 1312 Node* result = split_through_phi(phase); 1313 if (result != NULL) return result; 1314 } 1315 } 1316 1317 // Check for prior store with a different base or offset; make Load 1318 // independent. Skip through any number of them. Bail out if the stores 1319 // are in an endless dead cycle and report no progress. This is a key 1320 // transform for Reflection. However, if after skipping through the Stores 1321 // we can't then fold up against a prior store do NOT do the transform as 1322 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1323 // array memory alive twice: once for the hoisted Load and again after the 1324 // bypassed Store. This situation only works if EVERYBODY who does 1325 // anti-dependence work knows how to bypass. I.e. we need all 1326 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1327 // the alias index stuff. So instead, peek through Stores and IFF we can 1328 // fold up, do so. 1329 Node* prev_mem = find_previous_store(phase); 1330 // Steps (a), (b): Walk past independent stores to find an exact match. 1331 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1332 // (c) See if we can fold up on the spot, but don't fold up here. 1333 // Fold-up might require truncation (for LoadB/LoadS/LoadC) or 1334 // just return a prior value, which is done by Identity calls. 1335 if (can_see_stored_value(prev_mem, phase)) { 1336 // Make ready for step (d): 1337 set_req(MemNode::Memory, prev_mem); 1338 return this; 1339 } 1340 } 1341 1342 return NULL; // No further progress 1343} 1344 1345// Helper to recognize certain Klass fields which are invariant across 1346// some group of array types (e.g., int[] or all T[] where T < Object). 1347const Type* 1348LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1349 ciKlass* klass) const { 1350 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { 1351 // The field is Klass::_modifier_flags. Return its (constant) value. 1352 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1353 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1354 return TypeInt::make(klass->modifier_flags()); 1355 } 1356 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { 1357 // The field is Klass::_access_flags. Return its (constant) value. 1358 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1359 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1360 return TypeInt::make(klass->access_flags()); 1361 } 1362 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) { 1363 // The field is Klass::_layout_helper. Return its constant value if known. 1364 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1365 return TypeInt::make(klass->layout_helper()); 1366 } 1367 1368 // No match. 1369 return NULL; 1370} 1371 1372//------------------------------Value----------------------------------------- 1373const Type *LoadNode::Value( PhaseTransform *phase ) const { 1374 // Either input is TOP ==> the result is TOP 1375 Node* mem = in(MemNode::Memory); 1376 const Type *t1 = phase->type(mem); 1377 if (t1 == Type::TOP) return Type::TOP; 1378 Node* adr = in(MemNode::Address); 1379 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1380 if (tp == NULL || tp->empty()) return Type::TOP; 1381 int off = tp->offset(); 1382 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1383 1384 // Try to guess loaded type from pointer type 1385 if (tp->base() == Type::AryPtr) { 1386 const Type *t = tp->is_aryptr()->elem(); 1387 // Don't do this for integer types. There is only potential profit if 1388 // the element type t is lower than _type; that is, for int types, if _type is 1389 // more restrictive than t. This only happens here if one is short and the other 1390 // char (both 16 bits), and in those cases we've made an intentional decision 1391 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1392 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1393 // 1394 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1395 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1396 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1397 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1398 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1399 // In fact, that could have been the original type of p1, and p1 could have 1400 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1401 // expression (LShiftL quux 3) independently optimized to the constant 8. 1402 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1403 && Opcode() != Op_LoadKlass) { 1404 // t might actually be lower than _type, if _type is a unique 1405 // concrete subclass of abstract class t. 1406 // Make sure the reference is not into the header, by comparing 1407 // the offset against the offset of the start of the array's data. 1408 // Different array types begin at slightly different offsets (12 vs. 16). 1409 // We choose T_BYTE as an example base type that is least restrictive 1410 // as to alignment, which will therefore produce the smallest 1411 // possible base offset. 1412 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1413 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header? 1414 const Type* jt = t->join(_type); 1415 // In any case, do not allow the join, per se, to empty out the type. 1416 if (jt->empty() && !t->empty()) { 1417 // This can happen if a interface-typed array narrows to a class type. 1418 jt = _type; 1419 } 1420 1421 if (EliminateAutoBox) { 1422 // The pointers in the autobox arrays are always non-null 1423 Node* base = in(Address)->in(AddPNode::Base); 1424 if (base != NULL) { 1425 Compile::AliasType* atp = phase->C->alias_type(base->adr_type()); 1426 if (is_autobox_cache(atp)) { 1427 return jt->join(TypePtr::NOTNULL)->is_ptr(); 1428 } 1429 } 1430 } 1431 return jt; 1432 } 1433 } 1434 } else if (tp->base() == Type::InstPtr) { 1435 assert( off != Type::OffsetBot || 1436 // arrays can be cast to Objects 1437 tp->is_oopptr()->klass()->is_java_lang_Object() || 1438 // unsafe field access may not have a constant offset 1439 phase->C->has_unsafe_access(), 1440 "Field accesses must be precise" ); 1441 // For oop loads, we expect the _type to be precise 1442 } else if (tp->base() == Type::KlassPtr) { 1443 assert( off != Type::OffsetBot || 1444 // arrays can be cast to Objects 1445 tp->is_klassptr()->klass()->is_java_lang_Object() || 1446 // also allow array-loading from the primary supertype 1447 // array during subtype checks 1448 Opcode() == Op_LoadKlass, 1449 "Field accesses must be precise" ); 1450 // For klass/static loads, we expect the _type to be precise 1451 } 1452 1453 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1454 if (tkls != NULL && !StressReflectiveCode) { 1455 ciKlass* klass = tkls->klass(); 1456 if (klass->is_loaded() && tkls->klass_is_exact()) { 1457 // We are loading a field from a Klass metaobject whose identity 1458 // is known at compile time (the type is "exact" or "precise"). 1459 // Check for fields we know are maintained as constants by the VM. 1460 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) { 1461 // The field is Klass::_super_check_offset. Return its (constant) value. 1462 // (Folds up type checking code.) 1463 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1464 return TypeInt::make(klass->super_check_offset()); 1465 } 1466 // Compute index into primary_supers array 1467 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); 1468 // Check for overflowing; use unsigned compare to handle the negative case. 1469 if( depth < ciKlass::primary_super_limit() ) { 1470 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1471 // (Folds up type checking code.) 1472 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1473 ciKlass *ss = klass->super_of_depth(depth); 1474 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1475 } 1476 const Type* aift = load_array_final_field(tkls, klass); 1477 if (aift != NULL) return aift; 1478 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc) 1479 && klass->is_array_klass()) { 1480 // The field is arrayKlass::_component_mirror. Return its (constant) value. 1481 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.) 1482 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror"); 1483 return TypeInstPtr::make(klass->as_array_klass()->component_mirror()); 1484 } 1485 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) { 1486 // The field is Klass::_java_mirror. Return its (constant) value. 1487 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1488 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1489 return TypeInstPtr::make(klass->java_mirror()); 1490 } 1491 } 1492 1493 // We can still check if we are loading from the primary_supers array at a 1494 // shallow enough depth. Even though the klass is not exact, entries less 1495 // than or equal to its super depth are correct. 1496 if (klass->is_loaded() ) { 1497 ciType *inner = klass->klass(); 1498 while( inner->is_obj_array_klass() ) 1499 inner = inner->as_obj_array_klass()->base_element_type(); 1500 if( inner->is_instance_klass() && 1501 !inner->as_instance_klass()->flags().is_interface() ) { 1502 // Compute index into primary_supers array 1503 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); 1504 // Check for overflowing; use unsigned compare to handle the negative case. 1505 if( depth < ciKlass::primary_super_limit() && 1506 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1507 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1508 // (Folds up type checking code.) 1509 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1510 ciKlass *ss = klass->super_of_depth(depth); 1511 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1512 } 1513 } 1514 } 1515 1516 // If the type is enough to determine that the thing is not an array, 1517 // we can give the layout_helper a positive interval type. 1518 // This will help short-circuit some reflective code. 1519 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc) 1520 && !klass->is_array_klass() // not directly typed as an array 1521 && !klass->is_interface() // specifically not Serializable & Cloneable 1522 && !klass->is_java_lang_Object() // not the supertype of all T[] 1523 ) { 1524 // Note: When interfaces are reliable, we can narrow the interface 1525 // test to (klass != Serializable && klass != Cloneable). 1526 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1527 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1528 // The key property of this type is that it folds up tests 1529 // for array-ness, since it proves that the layout_helper is positive. 1530 // Thus, a generic value like the basic object layout helper works fine. 1531 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1532 } 1533 } 1534 1535 // If we are loading from a freshly-allocated object, produce a zero, 1536 // if the load is provably beyond the header of the object. 1537 // (Also allow a variable load from a fresh array to produce zero.) 1538 if (ReduceFieldZeroing) { 1539 Node* value = can_see_stored_value(mem,phase); 1540 if (value != NULL && value->is_Con()) 1541 return value->bottom_type(); 1542 } 1543 1544 const TypeOopPtr *tinst = tp->isa_oopptr(); 1545 if (tinst != NULL && tinst->is_known_instance_field()) { 1546 // If we have an instance type and our memory input is the 1547 // programs's initial memory state, there is no matching store, 1548 // so just return a zero of the appropriate type 1549 Node *mem = in(MemNode::Memory); 1550 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1551 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1552 return Type::get_zero_type(_type->basic_type()); 1553 } 1554 } 1555 return _type; 1556} 1557 1558//------------------------------match_edge------------------------------------- 1559// Do we Match on this edge index or not? Match only the address. 1560uint LoadNode::match_edge(uint idx) const { 1561 return idx == MemNode::Address; 1562} 1563 1564//--------------------------LoadBNode::Ideal-------------------------------------- 1565// 1566// If the previous store is to the same address as this load, 1567// and the value stored was larger than a byte, replace this load 1568// with the value stored truncated to a byte. If no truncation is 1569// needed, the replacement is done in LoadNode::Identity(). 1570// 1571Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1572 Node* mem = in(MemNode::Memory); 1573 Node* value = can_see_stored_value(mem,phase); 1574 if( value && !phase->type(value)->higher_equal( _type ) ) { 1575 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) ); 1576 return new (phase->C, 3) RShiftINode(result, phase->intcon(24)); 1577 } 1578 // Identity call will handle the case where truncation is not needed. 1579 return LoadNode::Ideal(phase, can_reshape); 1580} 1581 1582//--------------------------LoadCNode::Ideal-------------------------------------- 1583// 1584// If the previous store is to the same address as this load, 1585// and the value stored was larger than a char, replace this load 1586// with the value stored truncated to a char. If no truncation is 1587// needed, the replacement is done in LoadNode::Identity(). 1588// 1589Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1590 Node* mem = in(MemNode::Memory); 1591 Node* value = can_see_stored_value(mem,phase); 1592 if( value && !phase->type(value)->higher_equal( _type ) ) 1593 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF)); 1594 // Identity call will handle the case where truncation is not needed. 1595 return LoadNode::Ideal(phase, can_reshape); 1596} 1597 1598//--------------------------LoadSNode::Ideal-------------------------------------- 1599// 1600// If the previous store is to the same address as this load, 1601// and the value stored was larger than a short, replace this load 1602// with the value stored truncated to a short. If no truncation is 1603// needed, the replacement is done in LoadNode::Identity(). 1604// 1605Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1606 Node* mem = in(MemNode::Memory); 1607 Node* value = can_see_stored_value(mem,phase); 1608 if( value && !phase->type(value)->higher_equal( _type ) ) { 1609 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) ); 1610 return new (phase->C, 3) RShiftINode(result, phase->intcon(16)); 1611 } 1612 // Identity call will handle the case where truncation is not needed. 1613 return LoadNode::Ideal(phase, can_reshape); 1614} 1615 1616//============================================================================= 1617//----------------------------LoadKlassNode::make------------------------------ 1618// Polymorphic factory method: 1619Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) { 1620 Compile* C = gvn.C; 1621 Node *ctl = NULL; 1622 // sanity check the alias category against the created node type 1623 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr(); 1624 assert(adr_type != NULL, "expecting TypeOopPtr"); 1625#ifdef _LP64 1626 if (adr_type->is_ptr_to_narrowoop()) { 1627 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop())); 1628 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr()); 1629 } 1630#endif 1631 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 1632 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk); 1633} 1634 1635//------------------------------Value------------------------------------------ 1636const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { 1637 return klass_value_common(phase); 1638} 1639 1640const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const { 1641 // Either input is TOP ==> the result is TOP 1642 const Type *t1 = phase->type( in(MemNode::Memory) ); 1643 if (t1 == Type::TOP) return Type::TOP; 1644 Node *adr = in(MemNode::Address); 1645 const Type *t2 = phase->type( adr ); 1646 if (t2 == Type::TOP) return Type::TOP; 1647 const TypePtr *tp = t2->is_ptr(); 1648 if (TypePtr::above_centerline(tp->ptr()) || 1649 tp->ptr() == TypePtr::Null) return Type::TOP; 1650 1651 // Return a more precise klass, if possible 1652 const TypeInstPtr *tinst = tp->isa_instptr(); 1653 if (tinst != NULL) { 1654 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 1655 int offset = tinst->offset(); 1656 if (ik == phase->C->env()->Class_klass() 1657 && (offset == java_lang_Class::klass_offset_in_bytes() || 1658 offset == java_lang_Class::array_klass_offset_in_bytes())) { 1659 // We are loading a special hidden field from a Class mirror object, 1660 // the field which points to the VM's Klass metaobject. 1661 ciType* t = tinst->java_mirror_type(); 1662 // java_mirror_type returns non-null for compile-time Class constants. 1663 if (t != NULL) { 1664 // constant oop => constant klass 1665 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 1666 return TypeKlassPtr::make(ciArrayKlass::make(t)); 1667 } 1668 if (!t->is_klass()) { 1669 // a primitive Class (e.g., int.class) has NULL for a klass field 1670 return TypePtr::NULL_PTR; 1671 } 1672 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 1673 return TypeKlassPtr::make(t->as_klass()); 1674 } 1675 // non-constant mirror, so we can't tell what's going on 1676 } 1677 if( !ik->is_loaded() ) 1678 return _type; // Bail out if not loaded 1679 if (offset == oopDesc::klass_offset_in_bytes()) { 1680 if (tinst->klass_is_exact()) { 1681 return TypeKlassPtr::make(ik); 1682 } 1683 // See if we can become precise: no subklasses and no interface 1684 // (Note: We need to support verified interfaces.) 1685 if (!ik->is_interface() && !ik->has_subklass()) { 1686 //assert(!UseExactTypes, "this code should be useless with exact types"); 1687 // Add a dependence; if any subclass added we need to recompile 1688 if (!ik->is_final()) { 1689 // %%% should use stronger assert_unique_concrete_subtype instead 1690 phase->C->dependencies()->assert_leaf_type(ik); 1691 } 1692 // Return precise klass 1693 return TypeKlassPtr::make(ik); 1694 } 1695 1696 // Return root of possible klass 1697 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 1698 } 1699 } 1700 1701 // Check for loading klass from an array 1702 const TypeAryPtr *tary = tp->isa_aryptr(); 1703 if( tary != NULL ) { 1704 ciKlass *tary_klass = tary->klass(); 1705 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 1706 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 1707 if (tary->klass_is_exact()) { 1708 return TypeKlassPtr::make(tary_klass); 1709 } 1710 ciArrayKlass *ak = tary->klass()->as_array_klass(); 1711 // If the klass is an object array, we defer the question to the 1712 // array component klass. 1713 if( ak->is_obj_array_klass() ) { 1714 assert( ak->is_loaded(), "" ); 1715 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 1716 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 1717 ciInstanceKlass* ik = base_k->as_instance_klass(); 1718 // See if we can become precise: no subklasses and no interface 1719 if (!ik->is_interface() && !ik->has_subklass()) { 1720 //assert(!UseExactTypes, "this code should be useless with exact types"); 1721 // Add a dependence; if any subclass added we need to recompile 1722 if (!ik->is_final()) { 1723 phase->C->dependencies()->assert_leaf_type(ik); 1724 } 1725 // Return precise array klass 1726 return TypeKlassPtr::make(ak); 1727 } 1728 } 1729 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 1730 } else { // Found a type-array? 1731 //assert(!UseExactTypes, "this code should be useless with exact types"); 1732 assert( ak->is_type_array_klass(), "" ); 1733 return TypeKlassPtr::make(ak); // These are always precise 1734 } 1735 } 1736 } 1737 1738 // Check for loading klass from an array klass 1739 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1740 if (tkls != NULL && !StressReflectiveCode) { 1741 ciKlass* klass = tkls->klass(); 1742 if( !klass->is_loaded() ) 1743 return _type; // Bail out if not loaded 1744 if( klass->is_obj_array_klass() && 1745 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) { 1746 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 1747 // // Always returning precise element type is incorrect, 1748 // // e.g., element type could be object and array may contain strings 1749 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 1750 1751 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 1752 // according to the element type's subclassing. 1753 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 1754 } 1755 if( klass->is_instance_klass() && tkls->klass_is_exact() && 1756 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) { 1757 ciKlass* sup = klass->as_instance_klass()->super(); 1758 // The field is Klass::_super. Return its (constant) value. 1759 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 1760 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 1761 } 1762 } 1763 1764 // Bailout case 1765 return LoadNode::Value(phase); 1766} 1767 1768//------------------------------Identity--------------------------------------- 1769// To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 1770// Also feed through the klass in Allocate(...klass...)._klass. 1771Node* LoadKlassNode::Identity( PhaseTransform *phase ) { 1772 return klass_identity_common(phase); 1773} 1774 1775Node* LoadNode::klass_identity_common(PhaseTransform *phase ) { 1776 Node* x = LoadNode::Identity(phase); 1777 if (x != this) return x; 1778 1779 // Take apart the address into an oop and and offset. 1780 // Return 'this' if we cannot. 1781 Node* adr = in(MemNode::Address); 1782 intptr_t offset = 0; 1783 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 1784 if (base == NULL) return this; 1785 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 1786 if (toop == NULL) return this; 1787 1788 // We can fetch the klass directly through an AllocateNode. 1789 // This works even if the klass is not constant (clone or newArray). 1790 if (offset == oopDesc::klass_offset_in_bytes()) { 1791 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 1792 if (allocated_klass != NULL) { 1793 return allocated_klass; 1794 } 1795 } 1796 1797 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop. 1798 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass. 1799 // See inline_native_Class_query for occurrences of these patterns. 1800 // Java Example: x.getClass().isAssignableFrom(y) 1801 // Java Example: Array.newInstance(x.getClass().getComponentType(), n) 1802 // 1803 // This improves reflective code, often making the Class 1804 // mirror go completely dead. (Current exception: Class 1805 // mirrors may appear in debug info, but we could clean them out by 1806 // introducing a new debug info operator for klassOop.java_mirror). 1807 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 1808 && (offset == java_lang_Class::klass_offset_in_bytes() || 1809 offset == java_lang_Class::array_klass_offset_in_bytes())) { 1810 // We are loading a special hidden field from a Class mirror, 1811 // the field which points to its Klass or arrayKlass metaobject. 1812 if (base->is_Load()) { 1813 Node* adr2 = base->in(MemNode::Address); 1814 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 1815 if (tkls != NULL && !tkls->empty() 1816 && (tkls->klass()->is_instance_klass() || 1817 tkls->klass()->is_array_klass()) 1818 && adr2->is_AddP() 1819 ) { 1820 int mirror_field = Klass::java_mirror_offset_in_bytes(); 1821 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 1822 mirror_field = in_bytes(arrayKlass::component_mirror_offset()); 1823 } 1824 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) { 1825 return adr2->in(AddPNode::Base); 1826 } 1827 } 1828 } 1829 } 1830 1831 return this; 1832} 1833 1834 1835//------------------------------Value------------------------------------------ 1836const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const { 1837 const Type *t = klass_value_common(phase); 1838 if (t == Type::TOP) 1839 return t; 1840 1841 return t->make_narrowoop(); 1842} 1843 1844//------------------------------Identity--------------------------------------- 1845// To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 1846// Also feed through the klass in Allocate(...klass...)._klass. 1847Node* LoadNKlassNode::Identity( PhaseTransform *phase ) { 1848 Node *x = klass_identity_common(phase); 1849 1850 const Type *t = phase->type( x ); 1851 if( t == Type::TOP ) return x; 1852 if( t->isa_narrowoop()) return x; 1853 1854 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop())); 1855} 1856 1857//------------------------------Value----------------------------------------- 1858const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { 1859 // Either input is TOP ==> the result is TOP 1860 const Type *t1 = phase->type( in(MemNode::Memory) ); 1861 if( t1 == Type::TOP ) return Type::TOP; 1862 Node *adr = in(MemNode::Address); 1863 const Type *t2 = phase->type( adr ); 1864 if( t2 == Type::TOP ) return Type::TOP; 1865 const TypePtr *tp = t2->is_ptr(); 1866 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 1867 const TypeAryPtr *tap = tp->isa_aryptr(); 1868 if( !tap ) return _type; 1869 return tap->size(); 1870} 1871 1872//------------------------------Identity--------------------------------------- 1873// Feed through the length in AllocateArray(...length...)._length. 1874Node* LoadRangeNode::Identity( PhaseTransform *phase ) { 1875 Node* x = LoadINode::Identity(phase); 1876 if (x != this) return x; 1877 1878 // Take apart the address into an oop and and offset. 1879 // Return 'this' if we cannot. 1880 Node* adr = in(MemNode::Address); 1881 intptr_t offset = 0; 1882 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 1883 if (base == NULL) return this; 1884 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 1885 if (tary == NULL) return this; 1886 1887 // We can fetch the length directly through an AllocateArrayNode. 1888 // This works even if the length is not constant (clone or newArray). 1889 if (offset == arrayOopDesc::length_offset_in_bytes()) { 1890 Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase); 1891 if (allocated_length != NULL) { 1892 return allocated_length; 1893 } 1894 } 1895 1896 return this; 1897 1898} 1899//============================================================================= 1900//---------------------------StoreNode::make----------------------------------- 1901// Polymorphic factory method: 1902StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) { 1903 Compile* C = gvn.C; 1904 1905 switch (bt) { 1906 case T_BOOLEAN: 1907 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val); 1908 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val); 1909 case T_CHAR: 1910 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val); 1911 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val); 1912 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val); 1913 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val); 1914 case T_ADDRESS: 1915 case T_OBJECT: 1916#ifdef _LP64 1917 if (adr->bottom_type()->is_ptr_to_narrowoop() || 1918 (UseCompressedOops && val->bottom_type()->isa_klassptr() && 1919 adr->bottom_type()->isa_rawptr())) { 1920 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop())); 1921 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val); 1922 } else 1923#endif 1924 { 1925 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val); 1926 } 1927 } 1928 ShouldNotReachHere(); 1929 return (StoreNode*)NULL; 1930} 1931 1932StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) { 1933 bool require_atomic = true; 1934 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic); 1935} 1936 1937 1938//--------------------------bottom_type---------------------------------------- 1939const Type *StoreNode::bottom_type() const { 1940 return Type::MEMORY; 1941} 1942 1943//------------------------------hash------------------------------------------- 1944uint StoreNode::hash() const { 1945 // unroll addition of interesting fields 1946 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 1947 1948 // Since they are not commoned, do not hash them: 1949 return NO_HASH; 1950} 1951 1952//------------------------------Ideal------------------------------------------ 1953// Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 1954// When a store immediately follows a relevant allocation/initialization, 1955// try to capture it into the initialization, or hoist it above. 1956Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1957 Node* p = MemNode::Ideal_common(phase, can_reshape); 1958 if (p) return (p == NodeSentinel) ? NULL : p; 1959 1960 Node* mem = in(MemNode::Memory); 1961 Node* address = in(MemNode::Address); 1962 1963 // Back-to-back stores to same address? Fold em up. 1964 // Generally unsafe if I have intervening uses... 1965 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) { 1966 // Looking at a dead closed cycle of memory? 1967 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 1968 1969 assert(Opcode() == mem->Opcode() || 1970 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, 1971 "no mismatched stores, except on raw memory"); 1972 1973 if (mem->outcnt() == 1 && // check for intervening uses 1974 mem->as_Store()->memory_size() <= this->memory_size()) { 1975 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. 1976 // For example, 'mem' might be the final state at a conditional return. 1977 // Or, 'mem' might be used by some node which is live at the same time 1978 // 'this' is live, which might be unschedulable. So, require exactly 1979 // ONE user, the 'this' store, until such time as we clone 'mem' for 1980 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). 1981 if (can_reshape) { // (%%% is this an anachronism?) 1982 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), 1983 phase->is_IterGVN()); 1984 } else { 1985 // It's OK to do this in the parser, since DU info is always accurate, 1986 // and the parser always refers to nodes via SafePointNode maps. 1987 set_req(MemNode::Memory, mem->in(MemNode::Memory)); 1988 } 1989 return this; 1990 } 1991 } 1992 1993 // Capture an unaliased, unconditional, simple store into an initializer. 1994 // Or, if it is independent of the allocation, hoist it above the allocation. 1995 if (ReduceFieldZeroing && /*can_reshape &&*/ 1996 mem->is_Proj() && mem->in(0)->is_Initialize()) { 1997 InitializeNode* init = mem->in(0)->as_Initialize(); 1998 intptr_t offset = init->can_capture_store(this, phase); 1999 if (offset > 0) { 2000 Node* moved = init->capture_store(this, offset, phase); 2001 // If the InitializeNode captured me, it made a raw copy of me, 2002 // and I need to disappear. 2003 if (moved != NULL) { 2004 // %%% hack to ensure that Ideal returns a new node: 2005 mem = MergeMemNode::make(phase->C, mem); 2006 return mem; // fold me away 2007 } 2008 } 2009 } 2010 2011 return NULL; // No further progress 2012} 2013 2014//------------------------------Value----------------------------------------- 2015const Type *StoreNode::Value( PhaseTransform *phase ) const { 2016 // Either input is TOP ==> the result is TOP 2017 const Type *t1 = phase->type( in(MemNode::Memory) ); 2018 if( t1 == Type::TOP ) return Type::TOP; 2019 const Type *t2 = phase->type( in(MemNode::Address) ); 2020 if( t2 == Type::TOP ) return Type::TOP; 2021 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2022 if( t3 == Type::TOP ) return Type::TOP; 2023 return Type::MEMORY; 2024} 2025 2026//------------------------------Identity--------------------------------------- 2027// Remove redundant stores: 2028// Store(m, p, Load(m, p)) changes to m. 2029// Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2030Node *StoreNode::Identity( PhaseTransform *phase ) { 2031 Node* mem = in(MemNode::Memory); 2032 Node* adr = in(MemNode::Address); 2033 Node* val = in(MemNode::ValueIn); 2034 2035 // Load then Store? Then the Store is useless 2036 if (val->is_Load() && 2037 phase->eqv_uncast( val->in(MemNode::Address), adr ) && 2038 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) && 2039 val->as_Load()->store_Opcode() == Opcode()) { 2040 return mem; 2041 } 2042 2043 // Two stores in a row of the same value? 2044 if (mem->is_Store() && 2045 phase->eqv_uncast( mem->in(MemNode::Address), adr ) && 2046 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) && 2047 mem->Opcode() == Opcode()) { 2048 return mem; 2049 } 2050 2051 // Store of zero anywhere into a freshly-allocated object? 2052 // Then the store is useless. 2053 // (It must already have been captured by the InitializeNode.) 2054 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2055 // a newly allocated object is already all-zeroes everywhere 2056 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2057 return mem; 2058 } 2059 2060 // the store may also apply to zero-bits in an earlier object 2061 Node* prev_mem = find_previous_store(phase); 2062 // Steps (a), (b): Walk past independent stores to find an exact match. 2063 if (prev_mem != NULL) { 2064 Node* prev_val = can_see_stored_value(prev_mem, phase); 2065 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2066 // prev_val and val might differ by a cast; it would be good 2067 // to keep the more informative of the two. 2068 return mem; 2069 } 2070 } 2071 } 2072 2073 return this; 2074} 2075 2076//------------------------------match_edge------------------------------------- 2077// Do we Match on this edge index or not? Match only memory & value 2078uint StoreNode::match_edge(uint idx) const { 2079 return idx == MemNode::Address || idx == MemNode::ValueIn; 2080} 2081 2082//------------------------------cmp-------------------------------------------- 2083// Do not common stores up together. They generally have to be split 2084// back up anyways, so do not bother. 2085uint StoreNode::cmp( const Node &n ) const { 2086 return (&n == this); // Always fail except on self 2087} 2088 2089//------------------------------Ideal_masked_input----------------------------- 2090// Check for a useless mask before a partial-word store 2091// (StoreB ... (AndI valIn conIa) ) 2092// If (conIa & mask == mask) this simplifies to 2093// (StoreB ... (valIn) ) 2094Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2095 Node *val = in(MemNode::ValueIn); 2096 if( val->Opcode() == Op_AndI ) { 2097 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2098 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2099 set_req(MemNode::ValueIn, val->in(1)); 2100 return this; 2101 } 2102 } 2103 return NULL; 2104} 2105 2106 2107//------------------------------Ideal_sign_extended_input---------------------- 2108// Check for useless sign-extension before a partial-word store 2109// (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2110// If (conIL == conIR && conIR <= num_bits) this simplifies to 2111// (StoreB ... (valIn) ) 2112Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2113 Node *val = in(MemNode::ValueIn); 2114 if( val->Opcode() == Op_RShiftI ) { 2115 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2116 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2117 Node *shl = val->in(1); 2118 if( shl->Opcode() == Op_LShiftI ) { 2119 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2120 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2121 set_req(MemNode::ValueIn, shl->in(1)); 2122 return this; 2123 } 2124 } 2125 } 2126 } 2127 return NULL; 2128} 2129 2130//------------------------------value_never_loaded----------------------------------- 2131// Determine whether there are any possible loads of the value stored. 2132// For simplicity, we actually check if there are any loads from the 2133// address stored to, not just for loads of the value stored by this node. 2134// 2135bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2136 Node *adr = in(Address); 2137 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2138 if (adr_oop == NULL) 2139 return false; 2140 if (!adr_oop->is_known_instance_field()) 2141 return false; // if not a distinct instance, there may be aliases of the address 2142 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2143 Node *use = adr->fast_out(i); 2144 int opc = use->Opcode(); 2145 if (use->is_Load() || use->is_LoadStore()) { 2146 return false; 2147 } 2148 } 2149 return true; 2150} 2151 2152//============================================================================= 2153//------------------------------Ideal------------------------------------------ 2154// If the store is from an AND mask that leaves the low bits untouched, then 2155// we can skip the AND operation. If the store is from a sign-extension 2156// (a left shift, then right shift) we can skip both. 2157Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2158 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2159 if( progress != NULL ) return progress; 2160 2161 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2162 if( progress != NULL ) return progress; 2163 2164 // Finally check the default case 2165 return StoreNode::Ideal(phase, can_reshape); 2166} 2167 2168//============================================================================= 2169//------------------------------Ideal------------------------------------------ 2170// If the store is from an AND mask that leaves the low bits untouched, then 2171// we can skip the AND operation 2172Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2173 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2174 if( progress != NULL ) return progress; 2175 2176 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2177 if( progress != NULL ) return progress; 2178 2179 // Finally check the default case 2180 return StoreNode::Ideal(phase, can_reshape); 2181} 2182 2183//============================================================================= 2184//------------------------------Identity--------------------------------------- 2185Node *StoreCMNode::Identity( PhaseTransform *phase ) { 2186 // No need to card mark when storing a null ptr 2187 Node* my_store = in(MemNode::OopStore); 2188 if (my_store->is_Store()) { 2189 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2190 if( t1 == TypePtr::NULL_PTR ) { 2191 return in(MemNode::Memory); 2192 } 2193 } 2194 return this; 2195} 2196 2197//------------------------------Value----------------------------------------- 2198const Type *StoreCMNode::Value( PhaseTransform *phase ) const { 2199 // Either input is TOP ==> the result is TOP 2200 const Type *t = phase->type( in(MemNode::Memory) ); 2201 if( t == Type::TOP ) return Type::TOP; 2202 t = phase->type( in(MemNode::Address) ); 2203 if( t == Type::TOP ) return Type::TOP; 2204 t = phase->type( in(MemNode::ValueIn) ); 2205 if( t == Type::TOP ) return Type::TOP; 2206 // If extra input is TOP ==> the result is TOP 2207 t = phase->type( in(MemNode::OopStore) ); 2208 if( t == Type::TOP ) return Type::TOP; 2209 2210 return StoreNode::Value( phase ); 2211} 2212 2213 2214//============================================================================= 2215//----------------------------------SCMemProjNode------------------------------ 2216const Type * SCMemProjNode::Value( PhaseTransform *phase ) const 2217{ 2218 return bottom_type(); 2219} 2220 2221//============================================================================= 2222LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) { 2223 init_req(MemNode::Control, c ); 2224 init_req(MemNode::Memory , mem); 2225 init_req(MemNode::Address, adr); 2226 init_req(MemNode::ValueIn, val); 2227 init_req( ExpectedIn, ex ); 2228 init_class_id(Class_LoadStore); 2229 2230} 2231 2232//============================================================================= 2233//-------------------------------adr_type-------------------------------------- 2234// Do we Match on this edge index or not? Do not match memory 2235const TypePtr* ClearArrayNode::adr_type() const { 2236 Node *adr = in(3); 2237 return MemNode::calculate_adr_type(adr->bottom_type()); 2238} 2239 2240//------------------------------match_edge------------------------------------- 2241// Do we Match on this edge index or not? Do not match memory 2242uint ClearArrayNode::match_edge(uint idx) const { 2243 return idx > 1; 2244} 2245 2246//------------------------------Identity--------------------------------------- 2247// Clearing a zero length array does nothing 2248Node *ClearArrayNode::Identity( PhaseTransform *phase ) { 2249 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2250} 2251 2252//------------------------------Idealize--------------------------------------- 2253// Clearing a short array is faster with stores 2254Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2255 const int unit = BytesPerLong; 2256 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2257 if (!t) return NULL; 2258 if (!t->is_con()) return NULL; 2259 intptr_t raw_count = t->get_con(); 2260 intptr_t size = raw_count; 2261 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2262 // Clearing nothing uses the Identity call. 2263 // Negative clears are possible on dead ClearArrays 2264 // (see jck test stmt114.stmt11402.val). 2265 if (size <= 0 || size % unit != 0) return NULL; 2266 intptr_t count = size / unit; 2267 // Length too long; use fast hardware clear 2268 if (size > Matcher::init_array_short_size) return NULL; 2269 Node *mem = in(1); 2270 if( phase->type(mem)==Type::TOP ) return NULL; 2271 Node *adr = in(3); 2272 const Type* at = phase->type(adr); 2273 if( at==Type::TOP ) return NULL; 2274 const TypePtr* atp = at->isa_ptr(); 2275 // adjust atp to be the correct array element address type 2276 if (atp == NULL) atp = TypePtr::BOTTOM; 2277 else atp = atp->add_offset(Type::OffsetBot); 2278 // Get base for derived pointer purposes 2279 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2280 Node *base = adr->in(1); 2281 2282 Node *zero = phase->makecon(TypeLong::ZERO); 2283 Node *off = phase->MakeConX(BytesPerLong); 2284 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2285 count--; 2286 while( count-- ) { 2287 mem = phase->transform(mem); 2288 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off)); 2289 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2290 } 2291 return mem; 2292} 2293 2294//----------------------------clear_memory------------------------------------- 2295// Generate code to initialize object storage to zero. 2296Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2297 intptr_t start_offset, 2298 Node* end_offset, 2299 PhaseGVN* phase) { 2300 Compile* C = phase->C; 2301 intptr_t offset = start_offset; 2302 2303 int unit = BytesPerLong; 2304 if ((offset % unit) != 0) { 2305 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset)); 2306 adr = phase->transform(adr); 2307 const TypePtr* atp = TypeRawPtr::BOTTOM; 2308 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2309 mem = phase->transform(mem); 2310 offset += BytesPerInt; 2311 } 2312 assert((offset % unit) == 0, ""); 2313 2314 // Initialize the remaining stuff, if any, with a ClearArray. 2315 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2316} 2317 2318Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2319 Node* start_offset, 2320 Node* end_offset, 2321 PhaseGVN* phase) { 2322 if (start_offset == end_offset) { 2323 // nothing to do 2324 return mem; 2325 } 2326 2327 Compile* C = phase->C; 2328 int unit = BytesPerLong; 2329 Node* zbase = start_offset; 2330 Node* zend = end_offset; 2331 2332 // Scale to the unit required by the CPU: 2333 if (!Matcher::init_array_count_is_in_bytes) { 2334 Node* shift = phase->intcon(exact_log2(unit)); 2335 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) ); 2336 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) ); 2337 } 2338 2339 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) ); 2340 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT); 2341 2342 // Bulk clear double-words 2343 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) ); 2344 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr); 2345 return phase->transform(mem); 2346} 2347 2348Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2349 intptr_t start_offset, 2350 intptr_t end_offset, 2351 PhaseGVN* phase) { 2352 if (start_offset == end_offset) { 2353 // nothing to do 2354 return mem; 2355 } 2356 2357 Compile* C = phase->C; 2358 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2359 intptr_t done_offset = end_offset; 2360 if ((done_offset % BytesPerLong) != 0) { 2361 done_offset -= BytesPerInt; 2362 } 2363 if (done_offset > start_offset) { 2364 mem = clear_memory(ctl, mem, dest, 2365 start_offset, phase->MakeConX(done_offset), phase); 2366 } 2367 if (done_offset < end_offset) { // emit the final 32-bit store 2368 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset)); 2369 adr = phase->transform(adr); 2370 const TypePtr* atp = TypeRawPtr::BOTTOM; 2371 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2372 mem = phase->transform(mem); 2373 done_offset += BytesPerInt; 2374 } 2375 assert(done_offset == end_offset, ""); 2376 return mem; 2377} 2378 2379//============================================================================= 2380// Do we match on this edge? No memory edges 2381uint StrCompNode::match_edge(uint idx) const { 2382 return idx == 5 || idx == 6; 2383} 2384 2385//------------------------------Ideal------------------------------------------ 2386// Return a node which is more "ideal" than the current node. Strip out 2387// control copies 2388Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2389 return remove_dead_region(phase, can_reshape) ? this : NULL; 2390} 2391 2392//------------------------------Ideal------------------------------------------ 2393// Return a node which is more "ideal" than the current node. Strip out 2394// control copies 2395Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2396 return remove_dead_region(phase, can_reshape) ? this : NULL; 2397} 2398 2399 2400//============================================================================= 2401MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2402 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2403 _adr_type(C->get_adr_type(alias_idx)) 2404{ 2405 init_class_id(Class_MemBar); 2406 Node* top = C->top(); 2407 init_req(TypeFunc::I_O,top); 2408 init_req(TypeFunc::FramePtr,top); 2409 init_req(TypeFunc::ReturnAdr,top); 2410 if (precedent != NULL) 2411 init_req(TypeFunc::Parms, precedent); 2412} 2413 2414//------------------------------cmp-------------------------------------------- 2415uint MemBarNode::hash() const { return NO_HASH; } 2416uint MemBarNode::cmp( const Node &n ) const { 2417 return (&n == this); // Always fail except on self 2418} 2419 2420//------------------------------make------------------------------------------- 2421MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2422 int len = Precedent + (pn == NULL? 0: 1); 2423 switch (opcode) { 2424 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn); 2425 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn); 2426 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn); 2427 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn); 2428 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn); 2429 default: ShouldNotReachHere(); return NULL; 2430 } 2431} 2432 2433//------------------------------Ideal------------------------------------------ 2434// Return a node which is more "ideal" than the current node. Strip out 2435// control copies 2436Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2437 if (remove_dead_region(phase, can_reshape)) return this; 2438 return NULL; 2439} 2440 2441//------------------------------Value------------------------------------------ 2442const Type *MemBarNode::Value( PhaseTransform *phase ) const { 2443 if( !in(0) ) return Type::TOP; 2444 if( phase->type(in(0)) == Type::TOP ) 2445 return Type::TOP; 2446 return TypeTuple::MEMBAR; 2447} 2448 2449//------------------------------match------------------------------------------ 2450// Construct projections for memory. 2451Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 2452 switch (proj->_con) { 2453 case TypeFunc::Control: 2454 case TypeFunc::Memory: 2455 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 2456 } 2457 ShouldNotReachHere(); 2458 return NULL; 2459} 2460 2461//===========================InitializeNode==================================== 2462// SUMMARY: 2463// This node acts as a memory barrier on raw memory, after some raw stores. 2464// The 'cooked' oop value feeds from the Initialize, not the Allocation. 2465// The Initialize can 'capture' suitably constrained stores as raw inits. 2466// It can coalesce related raw stores into larger units (called 'tiles'). 2467// It can avoid zeroing new storage for memory units which have raw inits. 2468// At macro-expansion, it is marked 'complete', and does not optimize further. 2469// 2470// EXAMPLE: 2471// The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 2472// ctl = incoming control; mem* = incoming memory 2473// (Note: A star * on a memory edge denotes I/O and other standard edges.) 2474// First allocate uninitialized memory and fill in the header: 2475// alloc = (Allocate ctl mem* 16 #short[].klass ...) 2476// ctl := alloc.Control; mem* := alloc.Memory* 2477// rawmem = alloc.Memory; rawoop = alloc.RawAddress 2478// Then initialize to zero the non-header parts of the raw memory block: 2479// init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 2480// ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 2481// After the initialize node executes, the object is ready for service: 2482// oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 2483// Suppose its body is immediately initialized as {1,2}: 2484// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 2485// store2 = (StoreC init.Control store1 (+ oop 14) 2) 2486// mem.SLICE(#short[*]) := store2 2487// 2488// DETAILS: 2489// An InitializeNode collects and isolates object initialization after 2490// an AllocateNode and before the next possible safepoint. As a 2491// memory barrier (MemBarNode), it keeps critical stores from drifting 2492// down past any safepoint or any publication of the allocation. 2493// Before this barrier, a newly-allocated object may have uninitialized bits. 2494// After this barrier, it may be treated as a real oop, and GC is allowed. 2495// 2496// The semantics of the InitializeNode include an implicit zeroing of 2497// the new object from object header to the end of the object. 2498// (The object header and end are determined by the AllocateNode.) 2499// 2500// Certain stores may be added as direct inputs to the InitializeNode. 2501// These stores must update raw memory, and they must be to addresses 2502// derived from the raw address produced by AllocateNode, and with 2503// a constant offset. They must be ordered by increasing offset. 2504// The first one is at in(RawStores), the last at in(req()-1). 2505// Unlike most memory operations, they are not linked in a chain, 2506// but are displayed in parallel as users of the rawmem output of 2507// the allocation. 2508// 2509// (See comments in InitializeNode::capture_store, which continue 2510// the example given above.) 2511// 2512// When the associated Allocate is macro-expanded, the InitializeNode 2513// may be rewritten to optimize collected stores. A ClearArrayNode 2514// may also be created at that point to represent any required zeroing. 2515// The InitializeNode is then marked 'complete', prohibiting further 2516// capturing of nearby memory operations. 2517// 2518// During macro-expansion, all captured initializations which store 2519// constant values of 32 bits or smaller are coalesced (if advantagous) 2520// into larger 'tiles' 32 or 64 bits. This allows an object to be 2521// initialized in fewer memory operations. Memory words which are 2522// covered by neither tiles nor non-constant stores are pre-zeroed 2523// by explicit stores of zero. (The code shape happens to do all 2524// zeroing first, then all other stores, with both sequences occurring 2525// in order of ascending offsets.) 2526// 2527// Alternatively, code may be inserted between an AllocateNode and its 2528// InitializeNode, to perform arbitrary initialization of the new object. 2529// E.g., the object copying intrinsics insert complex data transfers here. 2530// The initialization must then be marked as 'complete' disable the 2531// built-in zeroing semantics and the collection of initializing stores. 2532// 2533// While an InitializeNode is incomplete, reads from the memory state 2534// produced by it are optimizable if they match the control edge and 2535// new oop address associated with the allocation/initialization. 2536// They return a stored value (if the offset matches) or else zero. 2537// A write to the memory state, if it matches control and address, 2538// and if it is to a constant offset, may be 'captured' by the 2539// InitializeNode. It is cloned as a raw memory operation and rewired 2540// inside the initialization, to the raw oop produced by the allocation. 2541// Operations on addresses which are provably distinct (e.g., to 2542// other AllocateNodes) are allowed to bypass the initialization. 2543// 2544// The effect of all this is to consolidate object initialization 2545// (both arrays and non-arrays, both piecewise and bulk) into a 2546// single location, where it can be optimized as a unit. 2547// 2548// Only stores with an offset less than TrackedInitializationLimit words 2549// will be considered for capture by an InitializeNode. This puts a 2550// reasonable limit on the complexity of optimized initializations. 2551 2552//---------------------------InitializeNode------------------------------------ 2553InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 2554 : _is_complete(false), 2555 MemBarNode(C, adr_type, rawoop) 2556{ 2557 init_class_id(Class_Initialize); 2558 2559 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 2560 assert(in(RawAddress) == rawoop, "proper init"); 2561 // Note: allocation() can be NULL, for secondary initialization barriers 2562} 2563 2564// Since this node is not matched, it will be processed by the 2565// register allocator. Declare that there are no constraints 2566// on the allocation of the RawAddress edge. 2567const RegMask &InitializeNode::in_RegMask(uint idx) const { 2568 // This edge should be set to top, by the set_complete. But be conservative. 2569 if (idx == InitializeNode::RawAddress) 2570 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 2571 return RegMask::Empty; 2572} 2573 2574Node* InitializeNode::memory(uint alias_idx) { 2575 Node* mem = in(Memory); 2576 if (mem->is_MergeMem()) { 2577 return mem->as_MergeMem()->memory_at(alias_idx); 2578 } else { 2579 // incoming raw memory is not split 2580 return mem; 2581 } 2582} 2583 2584bool InitializeNode::is_non_zero() { 2585 if (is_complete()) return false; 2586 remove_extra_zeroes(); 2587 return (req() > RawStores); 2588} 2589 2590void InitializeNode::set_complete(PhaseGVN* phase) { 2591 assert(!is_complete(), "caller responsibility"); 2592 _is_complete = true; 2593 2594 // After this node is complete, it contains a bunch of 2595 // raw-memory initializations. There is no need for 2596 // it to have anything to do with non-raw memory effects. 2597 // Therefore, tell all non-raw users to re-optimize themselves, 2598 // after skipping the memory effects of this initialization. 2599 PhaseIterGVN* igvn = phase->is_IterGVN(); 2600 if (igvn) igvn->add_users_to_worklist(this); 2601} 2602 2603// convenience function 2604// return false if the init contains any stores already 2605bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 2606 InitializeNode* init = initialization(); 2607 if (init == NULL || init->is_complete()) return false; 2608 init->remove_extra_zeroes(); 2609 // for now, if this allocation has already collected any inits, bail: 2610 if (init->is_non_zero()) return false; 2611 init->set_complete(phase); 2612 return true; 2613} 2614 2615void InitializeNode::remove_extra_zeroes() { 2616 if (req() == RawStores) return; 2617 Node* zmem = zero_memory(); 2618 uint fill = RawStores; 2619 for (uint i = fill; i < req(); i++) { 2620 Node* n = in(i); 2621 if (n->is_top() || n == zmem) continue; // skip 2622 if (fill < i) set_req(fill, n); // compact 2623 ++fill; 2624 } 2625 // delete any empty spaces created: 2626 while (fill < req()) { 2627 del_req(fill); 2628 } 2629} 2630 2631// Helper for remembering which stores go with which offsets. 2632intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 2633 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 2634 intptr_t offset = -1; 2635 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 2636 phase, offset); 2637 if (base == NULL) return -1; // something is dead, 2638 if (offset < 0) return -1; // dead, dead 2639 return offset; 2640} 2641 2642// Helper for proving that an initialization expression is 2643// "simple enough" to be folded into an object initialization. 2644// Attempts to prove that a store's initial value 'n' can be captured 2645// within the initialization without creating a vicious cycle, such as: 2646// { Foo p = new Foo(); p.next = p; } 2647// True for constants and parameters and small combinations thereof. 2648bool InitializeNode::detect_init_independence(Node* n, 2649 bool st_is_pinned, 2650 int& count) { 2651 if (n == NULL) return true; // (can this really happen?) 2652 if (n->is_Proj()) n = n->in(0); 2653 if (n == this) return false; // found a cycle 2654 if (n->is_Con()) return true; 2655 if (n->is_Start()) return true; // params, etc., are OK 2656 if (n->is_Root()) return true; // even better 2657 2658 Node* ctl = n->in(0); 2659 if (ctl != NULL && !ctl->is_top()) { 2660 if (ctl->is_Proj()) ctl = ctl->in(0); 2661 if (ctl == this) return false; 2662 2663 // If we already know that the enclosing memory op is pinned right after 2664 // the init, then any control flow that the store has picked up 2665 // must have preceded the init, or else be equal to the init. 2666 // Even after loop optimizations (which might change control edges) 2667 // a store is never pinned *before* the availability of its inputs. 2668 if (!MemNode::all_controls_dominate(n, this)) 2669 return false; // failed to prove a good control 2670 2671 } 2672 2673 // Check data edges for possible dependencies on 'this'. 2674 if ((count += 1) > 20) return false; // complexity limit 2675 for (uint i = 1; i < n->req(); i++) { 2676 Node* m = n->in(i); 2677 if (m == NULL || m == n || m->is_top()) continue; 2678 uint first_i = n->find_edge(m); 2679 if (i != first_i) continue; // process duplicate edge just once 2680 if (!detect_init_independence(m, st_is_pinned, count)) { 2681 return false; 2682 } 2683 } 2684 2685 return true; 2686} 2687 2688// Here are all the checks a Store must pass before it can be moved into 2689// an initialization. Returns zero if a check fails. 2690// On success, returns the (constant) offset to which the store applies, 2691// within the initialized memory. 2692intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) { 2693 const int FAIL = 0; 2694 if (st->req() != MemNode::ValueIn + 1) 2695 return FAIL; // an inscrutable StoreNode (card mark?) 2696 Node* ctl = st->in(MemNode::Control); 2697 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 2698 return FAIL; // must be unconditional after the initialization 2699 Node* mem = st->in(MemNode::Memory); 2700 if (!(mem->is_Proj() && mem->in(0) == this)) 2701 return FAIL; // must not be preceded by other stores 2702 Node* adr = st->in(MemNode::Address); 2703 intptr_t offset; 2704 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 2705 if (alloc == NULL) 2706 return FAIL; // inscrutable address 2707 if (alloc != allocation()) 2708 return FAIL; // wrong allocation! (store needs to float up) 2709 Node* val = st->in(MemNode::ValueIn); 2710 int complexity_count = 0; 2711 if (!detect_init_independence(val, true, complexity_count)) 2712 return FAIL; // stored value must be 'simple enough' 2713 2714 return offset; // success 2715} 2716 2717// Find the captured store in(i) which corresponds to the range 2718// [start..start+size) in the initialized object. 2719// If there is one, return its index i. If there isn't, return the 2720// negative of the index where it should be inserted. 2721// Return 0 if the queried range overlaps an initialization boundary 2722// or if dead code is encountered. 2723// If size_in_bytes is zero, do not bother with overlap checks. 2724int InitializeNode::captured_store_insertion_point(intptr_t start, 2725 int size_in_bytes, 2726 PhaseTransform* phase) { 2727 const int FAIL = 0, MAX_STORE = BytesPerLong; 2728 2729 if (is_complete()) 2730 return FAIL; // arraycopy got here first; punt 2731 2732 assert(allocation() != NULL, "must be present"); 2733 2734 // no negatives, no header fields: 2735 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 2736 2737 // after a certain size, we bail out on tracking all the stores: 2738 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 2739 if (start >= ti_limit) return FAIL; 2740 2741 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 2742 if (i >= limit) return -(int)i; // not found; here is where to put it 2743 2744 Node* st = in(i); 2745 intptr_t st_off = get_store_offset(st, phase); 2746 if (st_off < 0) { 2747 if (st != zero_memory()) { 2748 return FAIL; // bail out if there is dead garbage 2749 } 2750 } else if (st_off > start) { 2751 // ...we are done, since stores are ordered 2752 if (st_off < start + size_in_bytes) { 2753 return FAIL; // the next store overlaps 2754 } 2755 return -(int)i; // not found; here is where to put it 2756 } else if (st_off < start) { 2757 if (size_in_bytes != 0 && 2758 start < st_off + MAX_STORE && 2759 start < st_off + st->as_Store()->memory_size()) { 2760 return FAIL; // the previous store overlaps 2761 } 2762 } else { 2763 if (size_in_bytes != 0 && 2764 st->as_Store()->memory_size() != size_in_bytes) { 2765 return FAIL; // mismatched store size 2766 } 2767 return i; 2768 } 2769 2770 ++i; 2771 } 2772} 2773 2774// Look for a captured store which initializes at the offset 'start' 2775// with the given size. If there is no such store, and no other 2776// initialization interferes, then return zero_memory (the memory 2777// projection of the AllocateNode). 2778Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 2779 PhaseTransform* phase) { 2780 assert(stores_are_sane(phase), ""); 2781 int i = captured_store_insertion_point(start, size_in_bytes, phase); 2782 if (i == 0) { 2783 return NULL; // something is dead 2784 } else if (i < 0) { 2785 return zero_memory(); // just primordial zero bits here 2786 } else { 2787 Node* st = in(i); // here is the store at this position 2788 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 2789 return st; 2790 } 2791} 2792 2793// Create, as a raw pointer, an address within my new object at 'offset'. 2794Node* InitializeNode::make_raw_address(intptr_t offset, 2795 PhaseTransform* phase) { 2796 Node* addr = in(RawAddress); 2797 if (offset != 0) { 2798 Compile* C = phase->C; 2799 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr, 2800 phase->MakeConX(offset)) ); 2801 } 2802 return addr; 2803} 2804 2805// Clone the given store, converting it into a raw store 2806// initializing a field or element of my new object. 2807// Caller is responsible for retiring the original store, 2808// with subsume_node or the like. 2809// 2810// From the example above InitializeNode::InitializeNode, 2811// here are the old stores to be captured: 2812// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 2813// store2 = (StoreC init.Control store1 (+ oop 14) 2) 2814// 2815// Here is the changed code; note the extra edges on init: 2816// alloc = (Allocate ...) 2817// rawoop = alloc.RawAddress 2818// rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 2819// rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 2820// init = (Initialize alloc.Control alloc.Memory rawoop 2821// rawstore1 rawstore2) 2822// 2823Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 2824 PhaseTransform* phase) { 2825 assert(stores_are_sane(phase), ""); 2826 2827 if (start < 0) return NULL; 2828 assert(can_capture_store(st, phase) == start, "sanity"); 2829 2830 Compile* C = phase->C; 2831 int size_in_bytes = st->memory_size(); 2832 int i = captured_store_insertion_point(start, size_in_bytes, phase); 2833 if (i == 0) return NULL; // bail out 2834 Node* prev_mem = NULL; // raw memory for the captured store 2835 if (i > 0) { 2836 prev_mem = in(i); // there is a pre-existing store under this one 2837 set_req(i, C->top()); // temporarily disconnect it 2838 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 2839 } else { 2840 i = -i; // no pre-existing store 2841 prev_mem = zero_memory(); // a slice of the newly allocated object 2842 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 2843 set_req(--i, C->top()); // reuse this edge; it has been folded away 2844 else 2845 ins_req(i, C->top()); // build a new edge 2846 } 2847 Node* new_st = st->clone(); 2848 new_st->set_req(MemNode::Control, in(Control)); 2849 new_st->set_req(MemNode::Memory, prev_mem); 2850 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 2851 new_st = phase->transform(new_st); 2852 2853 // At this point, new_st might have swallowed a pre-existing store 2854 // at the same offset, or perhaps new_st might have disappeared, 2855 // if it redundantly stored the same value (or zero to fresh memory). 2856 2857 // In any case, wire it in: 2858 set_req(i, new_st); 2859 2860 // The caller may now kill the old guy. 2861 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 2862 assert(check_st == new_st || check_st == NULL, "must be findable"); 2863 assert(!is_complete(), ""); 2864 return new_st; 2865} 2866 2867static bool store_constant(jlong* tiles, int num_tiles, 2868 intptr_t st_off, int st_size, 2869 jlong con) { 2870 if ((st_off & (st_size-1)) != 0) 2871 return false; // strange store offset (assume size==2**N) 2872 address addr = (address)tiles + st_off; 2873 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 2874 switch (st_size) { 2875 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 2876 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 2877 case sizeof(jint): *(jint*) addr = (jint) con; break; 2878 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 2879 default: return false; // strange store size (detect size!=2**N here) 2880 } 2881 return true; // return success to caller 2882} 2883 2884// Coalesce subword constants into int constants and possibly 2885// into long constants. The goal, if the CPU permits, 2886// is to initialize the object with a small number of 64-bit tiles. 2887// Also, convert floating-point constants to bit patterns. 2888// Non-constants are not relevant to this pass. 2889// 2890// In terms of the running example on InitializeNode::InitializeNode 2891// and InitializeNode::capture_store, here is the transformation 2892// of rawstore1 and rawstore2 into rawstore12: 2893// alloc = (Allocate ...) 2894// rawoop = alloc.RawAddress 2895// tile12 = 0x00010002 2896// rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 2897// init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 2898// 2899void 2900InitializeNode::coalesce_subword_stores(intptr_t header_size, 2901 Node* size_in_bytes, 2902 PhaseGVN* phase) { 2903 Compile* C = phase->C; 2904 2905 assert(stores_are_sane(phase), ""); 2906 // Note: After this pass, they are not completely sane, 2907 // since there may be some overlaps. 2908 2909 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 2910 2911 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 2912 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 2913 size_limit = MIN2(size_limit, ti_limit); 2914 size_limit = align_size_up(size_limit, BytesPerLong); 2915 int num_tiles = size_limit / BytesPerLong; 2916 2917 // allocate space for the tile map: 2918 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 2919 jlong tiles_buf[small_len]; 2920 Node* nodes_buf[small_len]; 2921 jlong inits_buf[small_len]; 2922 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 2923 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 2924 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 2925 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 2926 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 2927 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 2928 // tiles: exact bitwise model of all primitive constants 2929 // nodes: last constant-storing node subsumed into the tiles model 2930 // inits: which bytes (in each tile) are touched by any initializations 2931 2932 //// Pass A: Fill in the tile model with any relevant stores. 2933 2934 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 2935 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 2936 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 2937 Node* zmem = zero_memory(); // initially zero memory state 2938 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 2939 Node* st = in(i); 2940 intptr_t st_off = get_store_offset(st, phase); 2941 2942 // Figure out the store's offset and constant value: 2943 if (st_off < header_size) continue; //skip (ignore header) 2944 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 2945 int st_size = st->as_Store()->memory_size(); 2946 if (st_off + st_size > size_limit) break; 2947 2948 // Record which bytes are touched, whether by constant or not. 2949 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 2950 continue; // skip (strange store size) 2951 2952 const Type* val = phase->type(st->in(MemNode::ValueIn)); 2953 if (!val->singleton()) continue; //skip (non-con store) 2954 BasicType type = val->basic_type(); 2955 2956 jlong con = 0; 2957 switch (type) { 2958 case T_INT: con = val->is_int()->get_con(); break; 2959 case T_LONG: con = val->is_long()->get_con(); break; 2960 case T_FLOAT: con = jint_cast(val->getf()); break; 2961 case T_DOUBLE: con = jlong_cast(val->getd()); break; 2962 default: continue; //skip (odd store type) 2963 } 2964 2965 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 2966 st->Opcode() == Op_StoreL) { 2967 continue; // This StoreL is already optimal. 2968 } 2969 2970 // Store down the constant. 2971 store_constant(tiles, num_tiles, st_off, st_size, con); 2972 2973 intptr_t j = st_off >> LogBytesPerLong; 2974 2975 if (type == T_INT && st_size == BytesPerInt 2976 && (st_off & BytesPerInt) == BytesPerInt) { 2977 jlong lcon = tiles[j]; 2978 if (!Matcher::isSimpleConstant64(lcon) && 2979 st->Opcode() == Op_StoreI) { 2980 // This StoreI is already optimal by itself. 2981 jint* intcon = (jint*) &tiles[j]; 2982 intcon[1] = 0; // undo the store_constant() 2983 2984 // If the previous store is also optimal by itself, back up and 2985 // undo the action of the previous loop iteration... if we can. 2986 // But if we can't, just let the previous half take care of itself. 2987 st = nodes[j]; 2988 st_off -= BytesPerInt; 2989 con = intcon[0]; 2990 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 2991 assert(st_off >= header_size, "still ignoring header"); 2992 assert(get_store_offset(st, phase) == st_off, "must be"); 2993 assert(in(i-1) == zmem, "must be"); 2994 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 2995 assert(con == tcon->is_int()->get_con(), "must be"); 2996 // Undo the effects of the previous loop trip, which swallowed st: 2997 intcon[0] = 0; // undo store_constant() 2998 set_req(i-1, st); // undo set_req(i, zmem) 2999 nodes[j] = NULL; // undo nodes[j] = st 3000 --old_subword; // undo ++old_subword 3001 } 3002 continue; // This StoreI is already optimal. 3003 } 3004 } 3005 3006 // This store is not needed. 3007 set_req(i, zmem); 3008 nodes[j] = st; // record for the moment 3009 if (st_size < BytesPerLong) // something has changed 3010 ++old_subword; // includes int/float, but who's counting... 3011 else ++old_long; 3012 } 3013 3014 if ((old_subword + old_long) == 0) 3015 return; // nothing more to do 3016 3017 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3018 // Be sure to insert them before overlapping non-constant stores. 3019 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3020 for (int j = 0; j < num_tiles; j++) { 3021 jlong con = tiles[j]; 3022 jlong init = inits[j]; 3023 if (con == 0) continue; 3024 jint con0, con1; // split the constant, address-wise 3025 jint init0, init1; // split the init map, address-wise 3026 { union { jlong con; jint intcon[2]; } u; 3027 u.con = con; 3028 con0 = u.intcon[0]; 3029 con1 = u.intcon[1]; 3030 u.con = init; 3031 init0 = u.intcon[0]; 3032 init1 = u.intcon[1]; 3033 } 3034 3035 Node* old = nodes[j]; 3036 assert(old != NULL, "need the prior store"); 3037 intptr_t offset = (j * BytesPerLong); 3038 3039 bool split = !Matcher::isSimpleConstant64(con); 3040 3041 if (offset < header_size) { 3042 assert(offset + BytesPerInt >= header_size, "second int counts"); 3043 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3044 split = true; // only the second word counts 3045 // Example: int a[] = { 42 ... } 3046 } else if (con0 == 0 && init0 == -1) { 3047 split = true; // first word is covered by full inits 3048 // Example: int a[] = { ... foo(), 42 ... } 3049 } else if (con1 == 0 && init1 == -1) { 3050 split = true; // second word is covered by full inits 3051 // Example: int a[] = { ... 42, foo() ... } 3052 } 3053 3054 // Here's a case where init0 is neither 0 nor -1: 3055 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3056 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3057 // In this case the tile is not split; it is (jlong)42. 3058 // The big tile is stored down, and then the foo() value is inserted. 3059 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3060 3061 Node* ctl = old->in(MemNode::Control); 3062 Node* adr = make_raw_address(offset, phase); 3063 const TypePtr* atp = TypeRawPtr::BOTTOM; 3064 3065 // One or two coalesced stores to plop down. 3066 Node* st[2]; 3067 intptr_t off[2]; 3068 int nst = 0; 3069 if (!split) { 3070 ++new_long; 3071 off[nst] = offset; 3072 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3073 phase->longcon(con), T_LONG); 3074 } else { 3075 // Omit either if it is a zero. 3076 if (con0 != 0) { 3077 ++new_int; 3078 off[nst] = offset; 3079 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3080 phase->intcon(con0), T_INT); 3081 } 3082 if (con1 != 0) { 3083 ++new_int; 3084 offset += BytesPerInt; 3085 adr = make_raw_address(offset, phase); 3086 off[nst] = offset; 3087 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3088 phase->intcon(con1), T_INT); 3089 } 3090 } 3091 3092 // Insert second store first, then the first before the second. 3093 // Insert each one just before any overlapping non-constant stores. 3094 while (nst > 0) { 3095 Node* st1 = st[--nst]; 3096 C->copy_node_notes_to(st1, old); 3097 st1 = phase->transform(st1); 3098 offset = off[nst]; 3099 assert(offset >= header_size, "do not smash header"); 3100 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3101 guarantee(ins_idx != 0, "must re-insert constant store"); 3102 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3103 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3104 set_req(--ins_idx, st1); 3105 else 3106 ins_req(ins_idx, st1); 3107 } 3108 } 3109 3110 if (PrintCompilation && WizardMode) 3111 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3112 old_subword, old_long, new_int, new_long); 3113 if (C->log() != NULL) 3114 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3115 old_subword, old_long, new_int, new_long); 3116 3117 // Clean up any remaining occurrences of zmem: 3118 remove_extra_zeroes(); 3119} 3120 3121// Explore forward from in(start) to find the first fully initialized 3122// word, and return its offset. Skip groups of subword stores which 3123// together initialize full words. If in(start) is itself part of a 3124// fully initialized word, return the offset of in(start). If there 3125// are no following full-word stores, or if something is fishy, return 3126// a negative value. 3127intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3128 int int_map = 0; 3129 intptr_t int_map_off = 0; 3130 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3131 3132 for (uint i = start, limit = req(); i < limit; i++) { 3133 Node* st = in(i); 3134 3135 intptr_t st_off = get_store_offset(st, phase); 3136 if (st_off < 0) break; // return conservative answer 3137 3138 int st_size = st->as_Store()->memory_size(); 3139 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3140 return st_off; // we found a complete word init 3141 } 3142 3143 // update the map: 3144 3145 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); 3146 if (this_int_off != int_map_off) { 3147 // reset the map: 3148 int_map = 0; 3149 int_map_off = this_int_off; 3150 } 3151 3152 int subword_off = st_off - this_int_off; 3153 int_map |= right_n_bits(st_size) << subword_off; 3154 if ((int_map & FULL_MAP) == FULL_MAP) { 3155 return this_int_off; // we found a complete word init 3156 } 3157 3158 // Did this store hit or cross the word boundary? 3159 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); 3160 if (next_int_off == this_int_off + BytesPerInt) { 3161 // We passed the current int, without fully initializing it. 3162 int_map_off = next_int_off; 3163 int_map >>= BytesPerInt; 3164 } else if (next_int_off > this_int_off + BytesPerInt) { 3165 // We passed the current and next int. 3166 return this_int_off + BytesPerInt; 3167 } 3168 } 3169 3170 return -1; 3171} 3172 3173 3174// Called when the associated AllocateNode is expanded into CFG. 3175// At this point, we may perform additional optimizations. 3176// Linearize the stores by ascending offset, to make memory 3177// activity as coherent as possible. 3178Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3179 intptr_t header_size, 3180 Node* size_in_bytes, 3181 PhaseGVN* phase) { 3182 assert(!is_complete(), "not already complete"); 3183 assert(stores_are_sane(phase), ""); 3184 assert(allocation() != NULL, "must be present"); 3185 3186 remove_extra_zeroes(); 3187 3188 if (ReduceFieldZeroing || ReduceBulkZeroing) 3189 // reduce instruction count for common initialization patterns 3190 coalesce_subword_stores(header_size, size_in_bytes, phase); 3191 3192 Node* zmem = zero_memory(); // initially zero memory state 3193 Node* inits = zmem; // accumulating a linearized chain of inits 3194 #ifdef ASSERT 3195 intptr_t first_offset = allocation()->minimum_header_size(); 3196 intptr_t last_init_off = first_offset; // previous init offset 3197 intptr_t last_init_end = first_offset; // previous init offset+size 3198 intptr_t last_tile_end = first_offset; // previous tile offset+size 3199 #endif 3200 intptr_t zeroes_done = header_size; 3201 3202 bool do_zeroing = true; // we might give up if inits are very sparse 3203 int big_init_gaps = 0; // how many large gaps have we seen? 3204 3205 if (ZeroTLAB) do_zeroing = false; 3206 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3207 3208 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3209 Node* st = in(i); 3210 intptr_t st_off = get_store_offset(st, phase); 3211 if (st_off < 0) 3212 break; // unknown junk in the inits 3213 if (st->in(MemNode::Memory) != zmem) 3214 break; // complicated store chains somehow in list 3215 3216 int st_size = st->as_Store()->memory_size(); 3217 intptr_t next_init_off = st_off + st_size; 3218 3219 if (do_zeroing && zeroes_done < next_init_off) { 3220 // See if this store needs a zero before it or under it. 3221 intptr_t zeroes_needed = st_off; 3222 3223 if (st_size < BytesPerInt) { 3224 // Look for subword stores which only partially initialize words. 3225 // If we find some, we must lay down some word-level zeroes first, 3226 // underneath the subword stores. 3227 // 3228 // Examples: 3229 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3230 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3231 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3232 // 3233 // Note: coalesce_subword_stores may have already done this, 3234 // if it was prompted by constant non-zero subword initializers. 3235 // But this case can still arise with non-constant stores. 3236 3237 intptr_t next_full_store = find_next_fullword_store(i, phase); 3238 3239 // In the examples above: 3240 // in(i) p q r s x y z 3241 // st_off 12 13 14 15 12 13 14 3242 // st_size 1 1 1 1 1 1 1 3243 // next_full_s. 12 16 16 16 16 16 16 3244 // z's_done 12 16 16 16 12 16 12 3245 // z's_needed 12 16 16 16 16 16 16 3246 // zsize 0 0 0 0 4 0 4 3247 if (next_full_store < 0) { 3248 // Conservative tack: Zero to end of current word. 3249 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); 3250 } else { 3251 // Zero to beginning of next fully initialized word. 3252 // Or, don't zero at all, if we are already in that word. 3253 assert(next_full_store >= zeroes_needed, "must go forward"); 3254 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3255 zeroes_needed = next_full_store; 3256 } 3257 } 3258 3259 if (zeroes_needed > zeroes_done) { 3260 intptr_t zsize = zeroes_needed - zeroes_done; 3261 // Do some incremental zeroing on rawmem, in parallel with inits. 3262 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3263 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3264 zeroes_done, zeroes_needed, 3265 phase); 3266 zeroes_done = zeroes_needed; 3267 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) 3268 do_zeroing = false; // leave the hole, next time 3269 } 3270 } 3271 3272 // Collect the store and move on: 3273 st->set_req(MemNode::Memory, inits); 3274 inits = st; // put it on the linearized chain 3275 set_req(i, zmem); // unhook from previous position 3276 3277 if (zeroes_done == st_off) 3278 zeroes_done = next_init_off; 3279 3280 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3281 3282 #ifdef ASSERT 3283 // Various order invariants. Weaker than stores_are_sane because 3284 // a large constant tile can be filled in by smaller non-constant stores. 3285 assert(st_off >= last_init_off, "inits do not reverse"); 3286 last_init_off = st_off; 3287 const Type* val = NULL; 3288 if (st_size >= BytesPerInt && 3289 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3290 (int)val->basic_type() < (int)T_OBJECT) { 3291 assert(st_off >= last_tile_end, "tiles do not overlap"); 3292 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3293 last_tile_end = MAX2(last_tile_end, next_init_off); 3294 } else { 3295 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); 3296 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3297 assert(st_off >= last_init_end, "inits do not overlap"); 3298 last_init_end = next_init_off; // it's a non-tile 3299 } 3300 #endif //ASSERT 3301 } 3302 3303 remove_extra_zeroes(); // clear out all the zmems left over 3304 add_req(inits); 3305 3306 if (!ZeroTLAB) { 3307 // If anything remains to be zeroed, zero it all now. 3308 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3309 // if it is the last unused 4 bytes of an instance, forget about it 3310 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3311 if (zeroes_done + BytesPerLong >= size_limit) { 3312 assert(allocation() != NULL, ""); 3313 Node* klass_node = allocation()->in(AllocateNode::KlassNode); 3314 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3315 if (zeroes_done == k->layout_helper()) 3316 zeroes_done = size_limit; 3317 } 3318 if (zeroes_done < size_limit) { 3319 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3320 zeroes_done, size_in_bytes, phase); 3321 } 3322 } 3323 3324 set_complete(phase); 3325 return rawmem; 3326} 3327 3328 3329#ifdef ASSERT 3330bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3331 if (is_complete()) 3332 return true; // stores could be anything at this point 3333 assert(allocation() != NULL, "must be present"); 3334 intptr_t last_off = allocation()->minimum_header_size(); 3335 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3336 Node* st = in(i); 3337 intptr_t st_off = get_store_offset(st, phase); 3338 if (st_off < 0) continue; // ignore dead garbage 3339 if (last_off > st_off) { 3340 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off); 3341 this->dump(2); 3342 assert(false, "ascending store offsets"); 3343 return false; 3344 } 3345 last_off = st_off + st->as_Store()->memory_size(); 3346 } 3347 return true; 3348} 3349#endif //ASSERT 3350 3351 3352 3353 3354//============================MergeMemNode===================================== 3355// 3356// SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 3357// contributing store or call operations. Each contributor provides the memory 3358// state for a particular "alias type" (see Compile::alias_type). For example, 3359// if a MergeMem has an input X for alias category #6, then any memory reference 3360// to alias category #6 may use X as its memory state input, as an exact equivalent 3361// to using the MergeMem as a whole. 3362// Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 3363// 3364// (Here, the <N> notation gives the index of the relevant adr_type.) 3365// 3366// In one special case (and more cases in the future), alias categories overlap. 3367// The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 3368// states. Therefore, if a MergeMem has only one contributing input W for Bot, 3369// it is exactly equivalent to that state W: 3370// MergeMem(<Bot>: W) <==> W 3371// 3372// Usually, the merge has more than one input. In that case, where inputs 3373// overlap (i.e., one is Bot), the narrower alias type determines the memory 3374// state for that type, and the wider alias type (Bot) fills in everywhere else: 3375// Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 3376// Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 3377// 3378// A merge can take a "wide" memory state as one of its narrow inputs. 3379// This simply means that the merge observes out only the relevant parts of 3380// the wide input. That is, wide memory states arriving at narrow merge inputs 3381// are implicitly "filtered" or "sliced" as necessary. (This is rare.) 3382// 3383// These rules imply that MergeMem nodes may cascade (via their <Bot> links), 3384// and that memory slices "leak through": 3385// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 3386// 3387// But, in such a cascade, repeated memory slices can "block the leak": 3388// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 3389// 3390// In the last example, Y is not part of the combined memory state of the 3391// outermost MergeMem. The system must, of course, prevent unschedulable 3392// memory states from arising, so you can be sure that the state Y is somehow 3393// a precursor to state Y'. 3394// 3395// 3396// REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 3397// of each MergeMemNode array are exactly the numerical alias indexes, including 3398// but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 3399// Compile::alias_type (and kin) produce and manage these indexes. 3400// 3401// By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 3402// (Note that this provides quick access to the top node inside MergeMem methods, 3403// without the need to reach out via TLS to Compile::current.) 3404// 3405// As a consequence of what was just described, a MergeMem that represents a full 3406// memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 3407// containing all alias categories. 3408// 3409// MergeMem nodes never (?) have control inputs, so in(0) is NULL. 3410// 3411// All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 3412// a memory state for the alias type <N>, or else the top node, meaning that 3413// there is no particular input for that alias type. Note that the length of 3414// a MergeMem is variable, and may be extended at any time to accommodate new 3415// memory states at larger alias indexes. When merges grow, they are of course 3416// filled with "top" in the unused in() positions. 3417// 3418// This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 3419// (Top was chosen because it works smoothly with passes like GCM.) 3420// 3421// For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 3422// the type of random VM bits like TLS references.) Since it is always the 3423// first non-Bot memory slice, some low-level loops use it to initialize an 3424// index variable: for (i = AliasIdxRaw; i < req(); i++). 3425// 3426// 3427// ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 3428// the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 3429// the memory state for alias type <N>, or (if there is no particular slice at <N>, 3430// it returns the base memory. To prevent bugs, memory_at does not accept <Top> 3431// or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 3432// MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 3433// 3434// %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 3435// really that different from the other memory inputs. An abbreviation called 3436// "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 3437// 3438// 3439// PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 3440// partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 3441// that "emerges though" the base memory will be marked as excluding the alias types 3442// of the other (narrow-memory) copies which "emerged through" the narrow edges: 3443// 3444// Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 3445// ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 3446// 3447// This strange "subtraction" effect is necessary to ensure IGVN convergence. 3448// (It is currently unimplemented.) As you can see, the resulting merge is 3449// actually a disjoint union of memory states, rather than an overlay. 3450// 3451 3452//------------------------------MergeMemNode----------------------------------- 3453Node* MergeMemNode::make_empty_memory() { 3454 Node* empty_memory = (Node*) Compile::current()->top(); 3455 assert(empty_memory->is_top(), "correct sentinel identity"); 3456 return empty_memory; 3457} 3458 3459MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 3460 init_class_id(Class_MergeMem); 3461 // all inputs are nullified in Node::Node(int) 3462 // set_input(0, NULL); // no control input 3463 3464 // Initialize the edges uniformly to top, for starters. 3465 Node* empty_mem = make_empty_memory(); 3466 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 3467 init_req(i,empty_mem); 3468 } 3469 assert(empty_memory() == empty_mem, ""); 3470 3471 if( new_base != NULL && new_base->is_MergeMem() ) { 3472 MergeMemNode* mdef = new_base->as_MergeMem(); 3473 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 3474 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 3475 mms.set_memory(mms.memory2()); 3476 } 3477 assert(base_memory() == mdef->base_memory(), ""); 3478 } else { 3479 set_base_memory(new_base); 3480 } 3481} 3482 3483// Make a new, untransformed MergeMem with the same base as 'mem'. 3484// If mem is itself a MergeMem, populate the result with the same edges. 3485MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) { 3486 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem); 3487} 3488 3489//------------------------------cmp-------------------------------------------- 3490uint MergeMemNode::hash() const { return NO_HASH; } 3491uint MergeMemNode::cmp( const Node &n ) const { 3492 return (&n == this); // Always fail except on self 3493} 3494 3495//------------------------------Identity--------------------------------------- 3496Node* MergeMemNode::Identity(PhaseTransform *phase) { 3497 // Identity if this merge point does not record any interesting memory 3498 // disambiguations. 3499 Node* base_mem = base_memory(); 3500 Node* empty_mem = empty_memory(); 3501 if (base_mem != empty_mem) { // Memory path is not dead? 3502 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3503 Node* mem = in(i); 3504 if (mem != empty_mem && mem != base_mem) { 3505 return this; // Many memory splits; no change 3506 } 3507 } 3508 } 3509 return base_mem; // No memory splits; ID on the one true input 3510} 3511 3512//------------------------------Ideal------------------------------------------ 3513// This method is invoked recursively on chains of MergeMem nodes 3514Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3515 // Remove chain'd MergeMems 3516 // 3517 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 3518 // relative to the "in(Bot)". Since we are patching both at the same time, 3519 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 3520 // but rewrite each "in(i)" relative to the new "in(Bot)". 3521 Node *progress = NULL; 3522 3523 3524 Node* old_base = base_memory(); 3525 Node* empty_mem = empty_memory(); 3526 if (old_base == empty_mem) 3527 return NULL; // Dead memory path. 3528 3529 MergeMemNode* old_mbase; 3530 if (old_base != NULL && old_base->is_MergeMem()) 3531 old_mbase = old_base->as_MergeMem(); 3532 else 3533 old_mbase = NULL; 3534 Node* new_base = old_base; 3535 3536 // simplify stacked MergeMems in base memory 3537 if (old_mbase) new_base = old_mbase->base_memory(); 3538 3539 // the base memory might contribute new slices beyond my req() 3540 if (old_mbase) grow_to_match(old_mbase); 3541 3542 // Look carefully at the base node if it is a phi. 3543 PhiNode* phi_base; 3544 if (new_base != NULL && new_base->is_Phi()) 3545 phi_base = new_base->as_Phi(); 3546 else 3547 phi_base = NULL; 3548 3549 Node* phi_reg = NULL; 3550 uint phi_len = (uint)-1; 3551 if (phi_base != NULL && !phi_base->is_copy()) { 3552 // do not examine phi if degraded to a copy 3553 phi_reg = phi_base->region(); 3554 phi_len = phi_base->req(); 3555 // see if the phi is unfinished 3556 for (uint i = 1; i < phi_len; i++) { 3557 if (phi_base->in(i) == NULL) { 3558 // incomplete phi; do not look at it yet! 3559 phi_reg = NULL; 3560 phi_len = (uint)-1; 3561 break; 3562 } 3563 } 3564 } 3565 3566 // Note: We do not call verify_sparse on entry, because inputs 3567 // can normalize to the base_memory via subsume_node or similar 3568 // mechanisms. This method repairs that damage. 3569 3570 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 3571 3572 // Look at each slice. 3573 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3574 Node* old_in = in(i); 3575 // calculate the old memory value 3576 Node* old_mem = old_in; 3577 if (old_mem == empty_mem) old_mem = old_base; 3578 assert(old_mem == memory_at(i), ""); 3579 3580 // maybe update (reslice) the old memory value 3581 3582 // simplify stacked MergeMems 3583 Node* new_mem = old_mem; 3584 MergeMemNode* old_mmem; 3585 if (old_mem != NULL && old_mem->is_MergeMem()) 3586 old_mmem = old_mem->as_MergeMem(); 3587 else 3588 old_mmem = NULL; 3589 if (old_mmem == this) { 3590 // This can happen if loops break up and safepoints disappear. 3591 // A merge of BotPtr (default) with a RawPtr memory derived from a 3592 // safepoint can be rewritten to a merge of the same BotPtr with 3593 // the BotPtr phi coming into the loop. If that phi disappears 3594 // also, we can end up with a self-loop of the mergemem. 3595 // In general, if loops degenerate and memory effects disappear, 3596 // a mergemem can be left looking at itself. This simply means 3597 // that the mergemem's default should be used, since there is 3598 // no longer any apparent effect on this slice. 3599 // Note: If a memory slice is a MergeMem cycle, it is unreachable 3600 // from start. Update the input to TOP. 3601 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 3602 } 3603 else if (old_mmem != NULL) { 3604 new_mem = old_mmem->memory_at(i); 3605 } 3606 // else preceeding memory was not a MergeMem 3607 3608 // replace equivalent phis (unfortunately, they do not GVN together) 3609 if (new_mem != NULL && new_mem != new_base && 3610 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 3611 if (new_mem->is_Phi()) { 3612 PhiNode* phi_mem = new_mem->as_Phi(); 3613 for (uint i = 1; i < phi_len; i++) { 3614 if (phi_base->in(i) != phi_mem->in(i)) { 3615 phi_mem = NULL; 3616 break; 3617 } 3618 } 3619 if (phi_mem != NULL) { 3620 // equivalent phi nodes; revert to the def 3621 new_mem = new_base; 3622 } 3623 } 3624 } 3625 3626 // maybe store down a new value 3627 Node* new_in = new_mem; 3628 if (new_in == new_base) new_in = empty_mem; 3629 3630 if (new_in != old_in) { 3631 // Warning: Do not combine this "if" with the previous "if" 3632 // A memory slice might have be be rewritten even if it is semantically 3633 // unchanged, if the base_memory value has changed. 3634 set_req(i, new_in); 3635 progress = this; // Report progress 3636 } 3637 } 3638 3639 if (new_base != old_base) { 3640 set_req(Compile::AliasIdxBot, new_base); 3641 // Don't use set_base_memory(new_base), because we need to update du. 3642 assert(base_memory() == new_base, ""); 3643 progress = this; 3644 } 3645 3646 if( base_memory() == this ) { 3647 // a self cycle indicates this memory path is dead 3648 set_req(Compile::AliasIdxBot, empty_mem); 3649 } 3650 3651 // Resolve external cycles by calling Ideal on a MergeMem base_memory 3652 // Recursion must occur after the self cycle check above 3653 if( base_memory()->is_MergeMem() ) { 3654 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 3655 Node *m = phase->transform(new_mbase); // Rollup any cycles 3656 if( m != NULL && (m->is_top() || 3657 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 3658 // propagate rollup of dead cycle to self 3659 set_req(Compile::AliasIdxBot, empty_mem); 3660 } 3661 } 3662 3663 if( base_memory() == empty_mem ) { 3664 progress = this; 3665 // Cut inputs during Parse phase only. 3666 // During Optimize phase a dead MergeMem node will be subsumed by Top. 3667 if( !can_reshape ) { 3668 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3669 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 3670 } 3671 } 3672 } 3673 3674 if( !progress && base_memory()->is_Phi() && can_reshape ) { 3675 // Check if PhiNode::Ideal's "Split phis through memory merges" 3676 // transform should be attempted. Look for this->phi->this cycle. 3677 uint merge_width = req(); 3678 if (merge_width > Compile::AliasIdxRaw) { 3679 PhiNode* phi = base_memory()->as_Phi(); 3680 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 3681 if (phi->in(i) == this) { 3682 phase->is_IterGVN()->_worklist.push(phi); 3683 break; 3684 } 3685 } 3686 } 3687 } 3688 3689 assert(progress || verify_sparse(), "please, no dups of base"); 3690 return progress; 3691} 3692 3693//-------------------------set_base_memory------------------------------------- 3694void MergeMemNode::set_base_memory(Node *new_base) { 3695 Node* empty_mem = empty_memory(); 3696 set_req(Compile::AliasIdxBot, new_base); 3697 assert(memory_at(req()) == new_base, "must set default memory"); 3698 // Clear out other occurrences of new_base: 3699 if (new_base != empty_mem) { 3700 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3701 if (in(i) == new_base) set_req(i, empty_mem); 3702 } 3703 } 3704} 3705 3706//------------------------------out_RegMask------------------------------------ 3707const RegMask &MergeMemNode::out_RegMask() const { 3708 return RegMask::Empty; 3709} 3710 3711//------------------------------dump_spec-------------------------------------- 3712#ifndef PRODUCT 3713void MergeMemNode::dump_spec(outputStream *st) const { 3714 st->print(" {"); 3715 Node* base_mem = base_memory(); 3716 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 3717 Node* mem = memory_at(i); 3718 if (mem == base_mem) { st->print(" -"); continue; } 3719 st->print( " N%d:", mem->_idx ); 3720 Compile::current()->get_adr_type(i)->dump_on(st); 3721 } 3722 st->print(" }"); 3723} 3724#endif // !PRODUCT 3725 3726 3727#ifdef ASSERT 3728static bool might_be_same(Node* a, Node* b) { 3729 if (a == b) return true; 3730 if (!(a->is_Phi() || b->is_Phi())) return false; 3731 // phis shift around during optimization 3732 return true; // pretty stupid... 3733} 3734 3735// verify a narrow slice (either incoming or outgoing) 3736static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 3737 if (!VerifyAliases) return; // don't bother to verify unless requested 3738 if (is_error_reported()) return; // muzzle asserts when debugging an error 3739 if (Node::in_dump()) return; // muzzle asserts when printing 3740 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 3741 assert(n != NULL, ""); 3742 // Elide intervening MergeMem's 3743 while (n->is_MergeMem()) { 3744 n = n->as_MergeMem()->memory_at(alias_idx); 3745 } 3746 Compile* C = Compile::current(); 3747 const TypePtr* n_adr_type = n->adr_type(); 3748 if (n == m->empty_memory()) { 3749 // Implicit copy of base_memory() 3750 } else if (n_adr_type != TypePtr::BOTTOM) { 3751 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 3752 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 3753 } else { 3754 // A few places like make_runtime_call "know" that VM calls are narrow, 3755 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 3756 bool expected_wide_mem = false; 3757 if (n == m->base_memory()) { 3758 expected_wide_mem = true; 3759 } else if (alias_idx == Compile::AliasIdxRaw || 3760 n == m->memory_at(Compile::AliasIdxRaw)) { 3761 expected_wide_mem = true; 3762 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 3763 // memory can "leak through" calls on channels that 3764 // are write-once. Allow this also. 3765 expected_wide_mem = true; 3766 } 3767 assert(expected_wide_mem, "expected narrow slice replacement"); 3768 } 3769} 3770#else // !ASSERT 3771#define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op 3772#endif 3773 3774 3775//-----------------------------memory_at--------------------------------------- 3776Node* MergeMemNode::memory_at(uint alias_idx) const { 3777 assert(alias_idx >= Compile::AliasIdxRaw || 3778 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 3779 "must avoid base_memory and AliasIdxTop"); 3780 3781 // Otherwise, it is a narrow slice. 3782 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 3783 Compile *C = Compile::current(); 3784 if (is_empty_memory(n)) { 3785 // the array is sparse; empty slots are the "top" node 3786 n = base_memory(); 3787 assert(Node::in_dump() 3788 || n == NULL || n->bottom_type() == Type::TOP 3789 || n->adr_type() == TypePtr::BOTTOM 3790 || n->adr_type() == TypeRawPtr::BOTTOM 3791 || Compile::current()->AliasLevel() == 0, 3792 "must be a wide memory"); 3793 // AliasLevel == 0 if we are organizing the memory states manually. 3794 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 3795 } else { 3796 // make sure the stored slice is sane 3797 #ifdef ASSERT 3798 if (is_error_reported() || Node::in_dump()) { 3799 } else if (might_be_same(n, base_memory())) { 3800 // Give it a pass: It is a mostly harmless repetition of the base. 3801 // This can arise normally from node subsumption during optimization. 3802 } else { 3803 verify_memory_slice(this, alias_idx, n); 3804 } 3805 #endif 3806 } 3807 return n; 3808} 3809 3810//---------------------------set_memory_at------------------------------------- 3811void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 3812 verify_memory_slice(this, alias_idx, n); 3813 Node* empty_mem = empty_memory(); 3814 if (n == base_memory()) n = empty_mem; // collapse default 3815 uint need_req = alias_idx+1; 3816 if (req() < need_req) { 3817 if (n == empty_mem) return; // already the default, so do not grow me 3818 // grow the sparse array 3819 do { 3820 add_req(empty_mem); 3821 } while (req() < need_req); 3822 } 3823 set_req( alias_idx, n ); 3824} 3825 3826 3827 3828//--------------------------iteration_setup------------------------------------ 3829void MergeMemNode::iteration_setup(const MergeMemNode* other) { 3830 if (other != NULL) { 3831 grow_to_match(other); 3832 // invariant: the finite support of mm2 is within mm->req() 3833 #ifdef ASSERT 3834 for (uint i = req(); i < other->req(); i++) { 3835 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 3836 } 3837 #endif 3838 } 3839 // Replace spurious copies of base_memory by top. 3840 Node* base_mem = base_memory(); 3841 if (base_mem != NULL && !base_mem->is_top()) { 3842 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 3843 if (in(i) == base_mem) 3844 set_req(i, empty_memory()); 3845 } 3846 } 3847} 3848 3849//---------------------------grow_to_match------------------------------------- 3850void MergeMemNode::grow_to_match(const MergeMemNode* other) { 3851 Node* empty_mem = empty_memory(); 3852 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 3853 // look for the finite support of the other memory 3854 for (uint i = other->req(); --i >= req(); ) { 3855 if (other->in(i) != empty_mem) { 3856 uint new_len = i+1; 3857 while (req() < new_len) add_req(empty_mem); 3858 break; 3859 } 3860 } 3861} 3862 3863//---------------------------verify_sparse------------------------------------- 3864#ifndef PRODUCT 3865bool MergeMemNode::verify_sparse() const { 3866 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 3867 Node* base_mem = base_memory(); 3868 // The following can happen in degenerate cases, since empty==top. 3869 if (is_empty_memory(base_mem)) return true; 3870 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3871 assert(in(i) != NULL, "sane slice"); 3872 if (in(i) == base_mem) return false; // should have been the sentinel value! 3873 } 3874 return true; 3875} 3876 3877bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 3878 Node* n; 3879 n = mm->in(idx); 3880 if (mem == n) return true; // might be empty_memory() 3881 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 3882 if (mem == n) return true; 3883 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 3884 if (mem == n) return true; 3885 if (n == NULL) break; 3886 } 3887 return false; 3888} 3889#endif // !PRODUCT 3890