memnode.cpp revision 196:d1605aabd0a1
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_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_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_instance() && 138 t->is_oopptr()->cast_to_instance(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_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 const TypeNarrowOop* narrowtype; 773 if (rt->isa_narrowoop()) { 774 narrowtype = rt->is_narrowoop(); 775 } else { 776 narrowtype = rt->is_oopptr()->make_narrowoop(); 777 } 778 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, narrowtype)); 779 780 return DecodeNNode::decode(&gvn, load); 781 } else 782#endif 783 { 784 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 785 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr()); 786 } 787 } 788 ShouldNotReachHere(); 789 return (LoadNode*)NULL; 790} 791 792LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) { 793 bool require_atomic = true; 794 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic); 795} 796 797 798 799 800//------------------------------hash------------------------------------------- 801uint LoadNode::hash() const { 802 // unroll addition of interesting fields 803 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 804} 805 806//---------------------------can_see_stored_value------------------------------ 807// This routine exists to make sure this set of tests is done the same 808// everywhere. We need to make a coordinated change: first LoadNode::Ideal 809// will change the graph shape in a way which makes memory alive twice at the 810// same time (uses the Oracle model of aliasing), then some 811// LoadXNode::Identity will fold things back to the equivalence-class model 812// of aliasing. 813Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 814 Node* ld_adr = in(MemNode::Address); 815 816 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 817 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL; 818 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw && 819 atp->field() != NULL && !atp->field()->is_volatile()) { 820 uint alias_idx = atp->index(); 821 bool final = atp->field()->is_final(); 822 Node* result = NULL; 823 Node* current = st; 824 // Skip through chains of MemBarNodes checking the MergeMems for 825 // new states for the slice of this load. Stop once any other 826 // kind of node is encountered. Loads from final memory can skip 827 // through any kind of MemBar but normal loads shouldn't skip 828 // through MemBarAcquire since the could allow them to move out of 829 // a synchronized region. 830 while (current->is_Proj()) { 831 int opc = current->in(0)->Opcode(); 832 if ((final && opc == Op_MemBarAcquire) || 833 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) { 834 Node* mem = current->in(0)->in(TypeFunc::Memory); 835 if (mem->is_MergeMem()) { 836 MergeMemNode* merge = mem->as_MergeMem(); 837 Node* new_st = merge->memory_at(alias_idx); 838 if (new_st == merge->base_memory()) { 839 // Keep searching 840 current = merge->base_memory(); 841 continue; 842 } 843 // Save the new memory state for the slice and fall through 844 // to exit. 845 result = new_st; 846 } 847 } 848 break; 849 } 850 if (result != NULL) { 851 st = result; 852 } 853 } 854 855 856 // Loop around twice in the case Load -> Initialize -> Store. 857 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 858 for (int trip = 0; trip <= 1; trip++) { 859 860 if (st->is_Store()) { 861 Node* st_adr = st->in(MemNode::Address); 862 if (!phase->eqv(st_adr, ld_adr)) { 863 // Try harder before giving up... Match raw and non-raw pointers. 864 intptr_t st_off = 0; 865 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 866 if (alloc == NULL) return NULL; 867 intptr_t ld_off = 0; 868 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 869 if (alloc != allo2) return NULL; 870 if (ld_off != st_off) return NULL; 871 // At this point we have proven something like this setup: 872 // A = Allocate(...) 873 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 874 // S = StoreQ(, AddP(, A.Parm , #Off), V) 875 // (Actually, we haven't yet proven the Q's are the same.) 876 // In other words, we are loading from a casted version of 877 // the same pointer-and-offset that we stored to. 878 // Thus, we are able to replace L by V. 879 } 880 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 881 if (store_Opcode() != st->Opcode()) 882 return NULL; 883 return st->in(MemNode::ValueIn); 884 } 885 886 intptr_t offset = 0; // scratch 887 888 // A load from a freshly-created object always returns zero. 889 // (This can happen after LoadNode::Ideal resets the load's memory input 890 // to find_captured_store, which returned InitializeNode::zero_memory.) 891 if (st->is_Proj() && st->in(0)->is_Allocate() && 892 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) && 893 offset >= st->in(0)->as_Allocate()->minimum_header_size()) { 894 // return a zero value for the load's basic type 895 // (This is one of the few places where a generic PhaseTransform 896 // can create new nodes. Think of it as lazily manifesting 897 // virtually pre-existing constants.) 898 return phase->zerocon(memory_type()); 899 } 900 901 // A load from an initialization barrier can match a captured store. 902 if (st->is_Proj() && st->in(0)->is_Initialize()) { 903 InitializeNode* init = st->in(0)->as_Initialize(); 904 AllocateNode* alloc = init->allocation(); 905 if (alloc != NULL && 906 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) { 907 // examine a captured store value 908 st = init->find_captured_store(offset, memory_size(), phase); 909 if (st != NULL) 910 continue; // take one more trip around 911 } 912 } 913 914 break; 915 } 916 917 return NULL; 918} 919 920//----------------------is_instance_field_load_with_local_phi------------------ 921bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 922 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl && 923 in(MemNode::Address)->is_AddP() ) { 924 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr(); 925 // Only instances. 926 if( t_oop != NULL && t_oop->is_instance_field() && 927 t_oop->offset() != Type::OffsetBot && 928 t_oop->offset() != Type::OffsetTop) { 929 return true; 930 } 931 } 932 return false; 933} 934 935//------------------------------Identity--------------------------------------- 936// Loads are identity if previous store is to same address 937Node *LoadNode::Identity( PhaseTransform *phase ) { 938 // If the previous store-maker is the right kind of Store, and the store is 939 // to the same address, then we are equal to the value stored. 940 Node* mem = in(MemNode::Memory); 941 Node* value = can_see_stored_value(mem, phase); 942 if( value ) { 943 // byte, short & char stores truncate naturally. 944 // A load has to load the truncated value which requires 945 // some sort of masking operation and that requires an 946 // Ideal call instead of an Identity call. 947 if (memory_size() < BytesPerInt) { 948 // If the input to the store does not fit with the load's result type, 949 // it must be truncated via an Ideal call. 950 if (!phase->type(value)->higher_equal(phase->type(this))) 951 return this; 952 } 953 // (This works even when value is a Con, but LoadNode::Value 954 // usually runs first, producing the singleton type of the Con.) 955 return value; 956 } 957 958 // Search for an existing data phi which was generated before for the same 959 // instance's field to avoid infinite genertion of phis in a loop. 960 Node *region = mem->in(0); 961 if (is_instance_field_load_with_local_phi(region)) { 962 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr(); 963 int this_index = phase->C->get_alias_index(addr_t); 964 int this_offset = addr_t->offset(); 965 int this_id = addr_t->is_oopptr()->instance_id(); 966 const Type* this_type = bottom_type(); 967 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 968 Node* phi = region->fast_out(i); 969 if (phi->is_Phi() && phi != mem && 970 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) { 971 return phi; 972 } 973 } 974 } 975 976 return this; 977} 978 979 980// Returns true if the AliasType refers to the field that holds the 981// cached box array. Currently only handles the IntegerCache case. 982static bool is_autobox_cache(Compile::AliasType* atp) { 983 if (atp != NULL && atp->field() != NULL) { 984 ciField* field = atp->field(); 985 ciSymbol* klass = field->holder()->name(); 986 if (field->name() == ciSymbol::cache_field_name() && 987 field->holder()->uses_default_loader() && 988 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 989 return true; 990 } 991 } 992 return false; 993} 994 995// Fetch the base value in the autobox array 996static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) { 997 if (atp != NULL && atp->field() != NULL) { 998 ciField* field = atp->field(); 999 ciSymbol* klass = field->holder()->name(); 1000 if (field->name() == ciSymbol::cache_field_name() && 1001 field->holder()->uses_default_loader() && 1002 klass == ciSymbol::java_lang_Integer_IntegerCache()) { 1003 assert(field->is_constant(), "what?"); 1004 ciObjArray* array = field->constant_value().as_object()->as_obj_array(); 1005 // Fetch the box object at the base of the array and get its value 1006 ciInstance* box = array->obj_at(0)->as_instance(); 1007 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1008 if (ik->nof_nonstatic_fields() == 1) { 1009 // This should be true nonstatic_field_at requires calling 1010 // nof_nonstatic_fields so check it anyway 1011 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1012 cache_offset = c.as_int(); 1013 } 1014 return true; 1015 } 1016 } 1017 return false; 1018} 1019 1020// Returns true if the AliasType refers to the value field of an 1021// autobox object. Currently only handles Integer. 1022static bool is_autobox_object(Compile::AliasType* atp) { 1023 if (atp != NULL && atp->field() != NULL) { 1024 ciField* field = atp->field(); 1025 ciSymbol* klass = field->holder()->name(); 1026 if (field->name() == ciSymbol::value_name() && 1027 field->holder()->uses_default_loader() && 1028 klass == ciSymbol::java_lang_Integer()) { 1029 return true; 1030 } 1031 } 1032 return false; 1033} 1034 1035 1036// We're loading from an object which has autobox behaviour. 1037// If this object is result of a valueOf call we'll have a phi 1038// merging a newly allocated object and a load from the cache. 1039// We want to replace this load with the original incoming 1040// argument to the valueOf call. 1041Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1042 Node* base = in(Address)->in(AddPNode::Base); 1043 if (base->is_Phi() && base->req() == 3) { 1044 AllocateNode* allocation = NULL; 1045 int allocation_index = -1; 1046 int load_index = -1; 1047 for (uint i = 1; i < base->req(); i++) { 1048 allocation = AllocateNode::Ideal_allocation(base->in(i), phase); 1049 if (allocation != NULL) { 1050 allocation_index = i; 1051 load_index = 3 - allocation_index; 1052 break; 1053 } 1054 } 1055 LoadNode* load = NULL; 1056 if (allocation != NULL && base->in(load_index)->is_Load()) { 1057 load = base->in(load_index)->as_Load(); 1058 } 1059 if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) { 1060 // Push the loads from the phi that comes from valueOf up 1061 // through it to allow elimination of the loads and the recovery 1062 // of the original value. 1063 Node* mem_phi = in(Memory); 1064 Node* offset = in(Address)->in(AddPNode::Offset); 1065 1066 Node* in1 = clone(); 1067 Node* in1_addr = in1->in(Address)->clone(); 1068 in1_addr->set_req(AddPNode::Base, base->in(allocation_index)); 1069 in1_addr->set_req(AddPNode::Address, base->in(allocation_index)); 1070 in1_addr->set_req(AddPNode::Offset, offset); 1071 in1->set_req(0, base->in(allocation_index)); 1072 in1->set_req(Address, in1_addr); 1073 in1->set_req(Memory, mem_phi->in(allocation_index)); 1074 1075 Node* in2 = clone(); 1076 Node* in2_addr = in2->in(Address)->clone(); 1077 in2_addr->set_req(AddPNode::Base, base->in(load_index)); 1078 in2_addr->set_req(AddPNode::Address, base->in(load_index)); 1079 in2_addr->set_req(AddPNode::Offset, offset); 1080 in2->set_req(0, base->in(load_index)); 1081 in2->set_req(Address, in2_addr); 1082 in2->set_req(Memory, mem_phi->in(load_index)); 1083 1084 in1_addr = phase->transform(in1_addr); 1085 in1 = phase->transform(in1); 1086 in2_addr = phase->transform(in2_addr); 1087 in2 = phase->transform(in2); 1088 1089 PhiNode* result = PhiNode::make_blank(base->in(0), this); 1090 result->set_req(allocation_index, in1); 1091 result->set_req(load_index, in2); 1092 return result; 1093 } 1094 } else if (base->is_Load()) { 1095 // Eliminate the load of Integer.value for integers from the cache 1096 // array by deriving the value from the index into the array. 1097 // Capture the offset of the load and then reverse the computation. 1098 Node* load_base = base->in(Address)->in(AddPNode::Base); 1099 if (load_base != NULL) { 1100 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type()); 1101 intptr_t cache_offset; 1102 int shift = -1; 1103 Node* cache = NULL; 1104 if (is_autobox_cache(atp)) { 1105 shift = exact_log2(type2aelembytes(T_OBJECT)); 1106 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset); 1107 } 1108 if (cache != NULL && base->in(Address)->is_AddP()) { 1109 Node* elements[4]; 1110 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements)); 1111 int cache_low; 1112 if (count > 0 && fetch_autobox_base(atp, cache_low)) { 1113 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift); 1114 // Add up all the offsets making of the address of the load 1115 Node* result = elements[0]; 1116 for (int i = 1; i < count; i++) { 1117 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i])); 1118 } 1119 // Remove the constant offset from the address and then 1120 // remove the scaling of the offset to recover the original index. 1121 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset))); 1122 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1123 // Peel the shift off directly but wrap it in a dummy node 1124 // since Ideal can't return existing nodes 1125 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0)); 1126 } else { 1127 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift)); 1128 } 1129#ifdef _LP64 1130 result = new (phase->C, 2) ConvL2INode(phase->transform(result)); 1131#endif 1132 return result; 1133 } 1134 } 1135 } 1136 } 1137 return NULL; 1138} 1139 1140//------------------------------split_through_phi------------------------------ 1141// Split instance field load through Phi. 1142Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1143 Node* mem = in(MemNode::Memory); 1144 Node* address = in(MemNode::Address); 1145 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1146 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1147 1148 assert(mem->is_Phi() && (t_oop != NULL) && 1149 t_oop->is_instance_field(), "invalide conditions"); 1150 1151 Node *region = mem->in(0); 1152 if (region == NULL) { 1153 return NULL; // Wait stable graph 1154 } 1155 uint cnt = mem->req(); 1156 for( uint i = 1; i < cnt; i++ ) { 1157 Node *in = mem->in(i); 1158 if( in == NULL ) { 1159 return NULL; // Wait stable graph 1160 } 1161 } 1162 // Check for loop invariant. 1163 if (cnt == 3) { 1164 for( uint i = 1; i < cnt; i++ ) { 1165 Node *in = mem->in(i); 1166 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase); 1167 if (m == mem) { 1168 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi. 1169 return this; 1170 } 1171 } 1172 } 1173 // Split through Phi (see original code in loopopts.cpp). 1174 assert(phase->C->have_alias_type(addr_t), "instance should have alias type"); 1175 1176 // Do nothing here if Identity will find a value 1177 // (to avoid infinite chain of value phis generation). 1178 if ( !phase->eqv(this, this->Identity(phase)) ) 1179 return NULL; 1180 1181 // Skip the split if the region dominates some control edge of the address. 1182 if (cnt == 3 && !MemNode::all_controls_dominate(address, region)) 1183 return NULL; 1184 1185 const Type* this_type = this->bottom_type(); 1186 int this_index = phase->C->get_alias_index(addr_t); 1187 int this_offset = addr_t->offset(); 1188 int this_iid = addr_t->is_oopptr()->instance_id(); 1189 int wins = 0; 1190 PhaseIterGVN *igvn = phase->is_IterGVN(); 1191 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset); 1192 for( uint i = 1; i < region->req(); i++ ) { 1193 Node *x; 1194 Node* the_clone = NULL; 1195 if( region->in(i) == phase->C->top() ) { 1196 x = phase->C->top(); // Dead path? Use a dead data op 1197 } else { 1198 x = this->clone(); // Else clone up the data op 1199 the_clone = x; // Remember for possible deletion. 1200 // Alter data node to use pre-phi inputs 1201 if( this->in(0) == region ) { 1202 x->set_req( 0, region->in(i) ); 1203 } else { 1204 x->set_req( 0, NULL ); 1205 } 1206 for( uint j = 1; j < this->req(); j++ ) { 1207 Node *in = this->in(j); 1208 if( in->is_Phi() && in->in(0) == region ) 1209 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone 1210 } 1211 } 1212 // Check for a 'win' on some paths 1213 const Type *t = x->Value(igvn); 1214 1215 bool singleton = t->singleton(); 1216 1217 // See comments in PhaseIdealLoop::split_thru_phi(). 1218 if( singleton && t == Type::TOP ) { 1219 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1220 } 1221 1222 if( singleton ) { 1223 wins++; 1224 x = igvn->makecon(t); 1225 } else { 1226 // We now call Identity to try to simplify the cloned node. 1227 // Note that some Identity methods call phase->type(this). 1228 // Make sure that the type array is big enough for 1229 // our new node, even though we may throw the node away. 1230 // (This tweaking with igvn only works because x is a new node.) 1231 igvn->set_type(x, t); 1232 Node *y = x->Identity(igvn); 1233 if( y != x ) { 1234 wins++; 1235 x = y; 1236 } else { 1237 y = igvn->hash_find(x); 1238 if( y ) { 1239 wins++; 1240 x = y; 1241 } else { 1242 // Else x is a new node we are keeping 1243 // We do not need register_new_node_with_optimizer 1244 // because set_type has already been called. 1245 igvn->_worklist.push(x); 1246 } 1247 } 1248 } 1249 if (x != the_clone && the_clone != NULL) 1250 igvn->remove_dead_node(the_clone); 1251 phi->set_req(i, x); 1252 } 1253 if( wins > 0 ) { 1254 // Record Phi 1255 igvn->register_new_node_with_optimizer(phi); 1256 return phi; 1257 } 1258 igvn->remove_dead_node(phi); 1259 return NULL; 1260} 1261 1262//------------------------------Ideal------------------------------------------ 1263// If the load is from Field memory and the pointer is non-null, we can 1264// zero out the control input. 1265// If the offset is constant and the base is an object allocation, 1266// try to hook me up to the exact initializing store. 1267Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1268 Node* p = MemNode::Ideal_common(phase, can_reshape); 1269 if (p) return (p == NodeSentinel) ? NULL : p; 1270 1271 Node* ctrl = in(MemNode::Control); 1272 Node* address = in(MemNode::Address); 1273 1274 // Skip up past a SafePoint control. Cannot do this for Stores because 1275 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1276 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1277 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1278 ctrl = ctrl->in(0); 1279 set_req(MemNode::Control,ctrl); 1280 } 1281 1282 // Check for useless control edge in some common special cases 1283 if (in(MemNode::Control) != NULL) { 1284 intptr_t ignore = 0; 1285 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1286 if (base != NULL 1287 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1288 && all_controls_dominate(base, phase->C->start())) { 1289 // A method-invariant, non-null address (constant or 'this' argument). 1290 set_req(MemNode::Control, NULL); 1291 } 1292 } 1293 1294 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) { 1295 Node* base = in(Address)->in(AddPNode::Base); 1296 if (base != NULL) { 1297 Compile::AliasType* atp = phase->C->alias_type(adr_type()); 1298 if (is_autobox_object(atp)) { 1299 Node* result = eliminate_autobox(phase); 1300 if (result != NULL) return result; 1301 } 1302 } 1303 } 1304 1305 Node* mem = in(MemNode::Memory); 1306 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1307 1308 if (addr_t != NULL) { 1309 // try to optimize our memory input 1310 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase); 1311 if (opt_mem != mem) { 1312 set_req(MemNode::Memory, opt_mem); 1313 return this; 1314 } 1315 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1316 if (can_reshape && opt_mem->is_Phi() && 1317 (t_oop != NULL) && t_oop->is_instance_field()) { 1318 // Split instance field load through Phi. 1319 Node* result = split_through_phi(phase); 1320 if (result != NULL) return result; 1321 } 1322 } 1323 1324 // Check for prior store with a different base or offset; make Load 1325 // independent. Skip through any number of them. Bail out if the stores 1326 // are in an endless dead cycle and report no progress. This is a key 1327 // transform for Reflection. However, if after skipping through the Stores 1328 // we can't then fold up against a prior store do NOT do the transform as 1329 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1330 // array memory alive twice: once for the hoisted Load and again after the 1331 // bypassed Store. This situation only works if EVERYBODY who does 1332 // anti-dependence work knows how to bypass. I.e. we need all 1333 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1334 // the alias index stuff. So instead, peek through Stores and IFF we can 1335 // fold up, do so. 1336 Node* prev_mem = find_previous_store(phase); 1337 // Steps (a), (b): Walk past independent stores to find an exact match. 1338 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1339 // (c) See if we can fold up on the spot, but don't fold up here. 1340 // Fold-up might require truncation (for LoadB/LoadS/LoadC) or 1341 // just return a prior value, which is done by Identity calls. 1342 if (can_see_stored_value(prev_mem, phase)) { 1343 // Make ready for step (d): 1344 set_req(MemNode::Memory, prev_mem); 1345 return this; 1346 } 1347 } 1348 1349 return NULL; // No further progress 1350} 1351 1352// Helper to recognize certain Klass fields which are invariant across 1353// some group of array types (e.g., int[] or all T[] where T < Object). 1354const Type* 1355LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1356 ciKlass* klass) const { 1357 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { 1358 // The field is Klass::_modifier_flags. Return its (constant) value. 1359 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1360 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1361 return TypeInt::make(klass->modifier_flags()); 1362 } 1363 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { 1364 // The field is Klass::_access_flags. Return its (constant) value. 1365 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1366 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1367 return TypeInt::make(klass->access_flags()); 1368 } 1369 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) { 1370 // The field is Klass::_layout_helper. Return its constant value if known. 1371 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1372 return TypeInt::make(klass->layout_helper()); 1373 } 1374 1375 // No match. 1376 return NULL; 1377} 1378 1379//------------------------------Value----------------------------------------- 1380const Type *LoadNode::Value( PhaseTransform *phase ) const { 1381 // Either input is TOP ==> the result is TOP 1382 Node* mem = in(MemNode::Memory); 1383 const Type *t1 = phase->type(mem); 1384 if (t1 == Type::TOP) return Type::TOP; 1385 Node* adr = in(MemNode::Address); 1386 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1387 if (tp == NULL || tp->empty()) return Type::TOP; 1388 int off = tp->offset(); 1389 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1390 1391 // Try to guess loaded type from pointer type 1392 if (tp->base() == Type::AryPtr) { 1393 const Type *t = tp->is_aryptr()->elem(); 1394 // Don't do this for integer types. There is only potential profit if 1395 // the element type t is lower than _type; that is, for int types, if _type is 1396 // more restrictive than t. This only happens here if one is short and the other 1397 // char (both 16 bits), and in those cases we've made an intentional decision 1398 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1399 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1400 // 1401 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1402 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1403 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1404 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1405 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1406 // In fact, that could have been the original type of p1, and p1 could have 1407 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1408 // expression (LShiftL quux 3) independently optimized to the constant 8. 1409 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1410 && Opcode() != Op_LoadKlass) { 1411 // t might actually be lower than _type, if _type is a unique 1412 // concrete subclass of abstract class t. 1413 // Make sure the reference is not into the header, by comparing 1414 // the offset against the offset of the start of the array's data. 1415 // Different array types begin at slightly different offsets (12 vs. 16). 1416 // We choose T_BYTE as an example base type that is least restrictive 1417 // as to alignment, which will therefore produce the smallest 1418 // possible base offset. 1419 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1420 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header? 1421 const Type* jt = t->join(_type); 1422 // In any case, do not allow the join, per se, to empty out the type. 1423 if (jt->empty() && !t->empty()) { 1424 // This can happen if a interface-typed array narrows to a class type. 1425 jt = _type; 1426 } 1427 1428 if (EliminateAutoBox) { 1429 // The pointers in the autobox arrays are always non-null 1430 Node* base = in(Address)->in(AddPNode::Base); 1431 if (base != NULL) { 1432 Compile::AliasType* atp = phase->C->alias_type(base->adr_type()); 1433 if (is_autobox_cache(atp)) { 1434 return jt->join(TypePtr::NOTNULL)->is_ptr(); 1435 } 1436 } 1437 } 1438 return jt; 1439 } 1440 } 1441 } else if (tp->base() == Type::InstPtr) { 1442 assert( off != Type::OffsetBot || 1443 // arrays can be cast to Objects 1444 tp->is_oopptr()->klass()->is_java_lang_Object() || 1445 // unsafe field access may not have a constant offset 1446 phase->C->has_unsafe_access(), 1447 "Field accesses must be precise" ); 1448 // For oop loads, we expect the _type to be precise 1449 } else if (tp->base() == Type::KlassPtr) { 1450 assert( off != Type::OffsetBot || 1451 // arrays can be cast to Objects 1452 tp->is_klassptr()->klass()->is_java_lang_Object() || 1453 // also allow array-loading from the primary supertype 1454 // array during subtype checks 1455 Opcode() == Op_LoadKlass, 1456 "Field accesses must be precise" ); 1457 // For klass/static loads, we expect the _type to be precise 1458 } 1459 1460 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1461 if (tkls != NULL && !StressReflectiveCode) { 1462 ciKlass* klass = tkls->klass(); 1463 if (klass->is_loaded() && tkls->klass_is_exact()) { 1464 // We are loading a field from a Klass metaobject whose identity 1465 // is known at compile time (the type is "exact" or "precise"). 1466 // Check for fields we know are maintained as constants by the VM. 1467 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) { 1468 // The field is Klass::_super_check_offset. Return its (constant) value. 1469 // (Folds up type checking code.) 1470 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1471 return TypeInt::make(klass->super_check_offset()); 1472 } 1473 // Compute index into primary_supers array 1474 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); 1475 // Check for overflowing; use unsigned compare to handle the negative case. 1476 if( depth < ciKlass::primary_super_limit() ) { 1477 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1478 // (Folds up type checking code.) 1479 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1480 ciKlass *ss = klass->super_of_depth(depth); 1481 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1482 } 1483 const Type* aift = load_array_final_field(tkls, klass); 1484 if (aift != NULL) return aift; 1485 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc) 1486 && klass->is_array_klass()) { 1487 // The field is arrayKlass::_component_mirror. Return its (constant) value. 1488 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.) 1489 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror"); 1490 return TypeInstPtr::make(klass->as_array_klass()->component_mirror()); 1491 } 1492 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) { 1493 // The field is Klass::_java_mirror. Return its (constant) value. 1494 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1495 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1496 return TypeInstPtr::make(klass->java_mirror()); 1497 } 1498 } 1499 1500 // We can still check if we are loading from the primary_supers array at a 1501 // shallow enough depth. Even though the klass is not exact, entries less 1502 // than or equal to its super depth are correct. 1503 if (klass->is_loaded() ) { 1504 ciType *inner = klass->klass(); 1505 while( inner->is_obj_array_klass() ) 1506 inner = inner->as_obj_array_klass()->base_element_type(); 1507 if( inner->is_instance_klass() && 1508 !inner->as_instance_klass()->flags().is_interface() ) { 1509 // Compute index into primary_supers array 1510 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); 1511 // Check for overflowing; use unsigned compare to handle the negative case. 1512 if( depth < ciKlass::primary_super_limit() && 1513 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1514 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1515 // (Folds up type checking code.) 1516 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1517 ciKlass *ss = klass->super_of_depth(depth); 1518 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1519 } 1520 } 1521 } 1522 1523 // If the type is enough to determine that the thing is not an array, 1524 // we can give the layout_helper a positive interval type. 1525 // This will help short-circuit some reflective code. 1526 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc) 1527 && !klass->is_array_klass() // not directly typed as an array 1528 && !klass->is_interface() // specifically not Serializable & Cloneable 1529 && !klass->is_java_lang_Object() // not the supertype of all T[] 1530 ) { 1531 // Note: When interfaces are reliable, we can narrow the interface 1532 // test to (klass != Serializable && klass != Cloneable). 1533 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1534 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1535 // The key property of this type is that it folds up tests 1536 // for array-ness, since it proves that the layout_helper is positive. 1537 // Thus, a generic value like the basic object layout helper works fine. 1538 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1539 } 1540 } 1541 1542 // If we are loading from a freshly-allocated object, produce a zero, 1543 // if the load is provably beyond the header of the object. 1544 // (Also allow a variable load from a fresh array to produce zero.) 1545 if (ReduceFieldZeroing) { 1546 Node* value = can_see_stored_value(mem,phase); 1547 if (value != NULL && value->is_Con()) 1548 return value->bottom_type(); 1549 } 1550 1551 const TypeOopPtr *tinst = tp->isa_oopptr(); 1552 if (tinst != NULL && tinst->is_instance_field()) { 1553 // If we have an instance type and our memory input is the 1554 // programs's initial memory state, there is no matching store, 1555 // so just return a zero of the appropriate type 1556 Node *mem = in(MemNode::Memory); 1557 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1558 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1559 return Type::get_zero_type(_type->basic_type()); 1560 } 1561 } 1562 return _type; 1563} 1564 1565//------------------------------match_edge------------------------------------- 1566// Do we Match on this edge index or not? Match only the address. 1567uint LoadNode::match_edge(uint idx) const { 1568 return idx == MemNode::Address; 1569} 1570 1571//--------------------------LoadBNode::Ideal-------------------------------------- 1572// 1573// If the previous store is to the same address as this load, 1574// and the value stored was larger than a byte, replace this load 1575// with the value stored truncated to a byte. If no truncation is 1576// needed, the replacement is done in LoadNode::Identity(). 1577// 1578Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1579 Node* mem = in(MemNode::Memory); 1580 Node* value = can_see_stored_value(mem,phase); 1581 if( value && !phase->type(value)->higher_equal( _type ) ) { 1582 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) ); 1583 return new (phase->C, 3) RShiftINode(result, phase->intcon(24)); 1584 } 1585 // Identity call will handle the case where truncation is not needed. 1586 return LoadNode::Ideal(phase, can_reshape); 1587} 1588 1589//--------------------------LoadCNode::Ideal-------------------------------------- 1590// 1591// If the previous store is to the same address as this load, 1592// and the value stored was larger than a char, replace this load 1593// with the value stored truncated to a char. If no truncation is 1594// needed, the replacement is done in LoadNode::Identity(). 1595// 1596Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1597 Node* mem = in(MemNode::Memory); 1598 Node* value = can_see_stored_value(mem,phase); 1599 if( value && !phase->type(value)->higher_equal( _type ) ) 1600 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF)); 1601 // Identity call will handle the case where truncation is not needed. 1602 return LoadNode::Ideal(phase, can_reshape); 1603} 1604 1605//--------------------------LoadSNode::Ideal-------------------------------------- 1606// 1607// If the previous store is to the same address as this load, 1608// and the value stored was larger than a short, replace this load 1609// with the value stored truncated to a short. If no truncation is 1610// needed, the replacement is done in LoadNode::Identity(). 1611// 1612Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1613 Node* mem = in(MemNode::Memory); 1614 Node* value = can_see_stored_value(mem,phase); 1615 if( value && !phase->type(value)->higher_equal( _type ) ) { 1616 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) ); 1617 return new (phase->C, 3) RShiftINode(result, phase->intcon(16)); 1618 } 1619 // Identity call will handle the case where truncation is not needed. 1620 return LoadNode::Ideal(phase, can_reshape); 1621} 1622 1623//============================================================================= 1624//----------------------------LoadKlassNode::make------------------------------ 1625// Polymorphic factory method: 1626Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) { 1627 Compile* C = gvn.C; 1628 Node *ctl = NULL; 1629 // sanity check the alias category against the created node type 1630 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr(); 1631 assert(adr_type != NULL, "expecting TypeOopPtr"); 1632#ifdef _LP64 1633 if (adr_type->is_ptr_to_narrowoop()) { 1634 const TypeNarrowOop* narrowtype = tk->is_oopptr()->make_narrowoop(); 1635 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, narrowtype)); 1636 return DecodeNNode::decode(&gvn, load_klass); 1637 } 1638#endif 1639 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 1640 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk); 1641} 1642 1643//------------------------------Value------------------------------------------ 1644const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { 1645 return klass_value_common(phase); 1646} 1647 1648const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const { 1649 // Either input is TOP ==> the result is TOP 1650 const Type *t1 = phase->type( in(MemNode::Memory) ); 1651 if (t1 == Type::TOP) return Type::TOP; 1652 Node *adr = in(MemNode::Address); 1653 const Type *t2 = phase->type( adr ); 1654 if (t2 == Type::TOP) return Type::TOP; 1655 const TypePtr *tp = t2->is_ptr(); 1656 if (TypePtr::above_centerline(tp->ptr()) || 1657 tp->ptr() == TypePtr::Null) return Type::TOP; 1658 1659 // Return a more precise klass, if possible 1660 const TypeInstPtr *tinst = tp->isa_instptr(); 1661 if (tinst != NULL) { 1662 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 1663 int offset = tinst->offset(); 1664 if (ik == phase->C->env()->Class_klass() 1665 && (offset == java_lang_Class::klass_offset_in_bytes() || 1666 offset == java_lang_Class::array_klass_offset_in_bytes())) { 1667 // We are loading a special hidden field from a Class mirror object, 1668 // the field which points to the VM's Klass metaobject. 1669 ciType* t = tinst->java_mirror_type(); 1670 // java_mirror_type returns non-null for compile-time Class constants. 1671 if (t != NULL) { 1672 // constant oop => constant klass 1673 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 1674 return TypeKlassPtr::make(ciArrayKlass::make(t)); 1675 } 1676 if (!t->is_klass()) { 1677 // a primitive Class (e.g., int.class) has NULL for a klass field 1678 return TypePtr::NULL_PTR; 1679 } 1680 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 1681 return TypeKlassPtr::make(t->as_klass()); 1682 } 1683 // non-constant mirror, so we can't tell what's going on 1684 } 1685 if( !ik->is_loaded() ) 1686 return _type; // Bail out if not loaded 1687 if (offset == oopDesc::klass_offset_in_bytes()) { 1688 if (tinst->klass_is_exact()) { 1689 return TypeKlassPtr::make(ik); 1690 } 1691 // See if we can become precise: no subklasses and no interface 1692 // (Note: We need to support verified interfaces.) 1693 if (!ik->is_interface() && !ik->has_subklass()) { 1694 //assert(!UseExactTypes, "this code should be useless with exact types"); 1695 // Add a dependence; if any subclass added we need to recompile 1696 if (!ik->is_final()) { 1697 // %%% should use stronger assert_unique_concrete_subtype instead 1698 phase->C->dependencies()->assert_leaf_type(ik); 1699 } 1700 // Return precise klass 1701 return TypeKlassPtr::make(ik); 1702 } 1703 1704 // Return root of possible klass 1705 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 1706 } 1707 } 1708 1709 // Check for loading klass from an array 1710 const TypeAryPtr *tary = tp->isa_aryptr(); 1711 if( tary != NULL ) { 1712 ciKlass *tary_klass = tary->klass(); 1713 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 1714 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 1715 if (tary->klass_is_exact()) { 1716 return TypeKlassPtr::make(tary_klass); 1717 } 1718 ciArrayKlass *ak = tary->klass()->as_array_klass(); 1719 // If the klass is an object array, we defer the question to the 1720 // array component klass. 1721 if( ak->is_obj_array_klass() ) { 1722 assert( ak->is_loaded(), "" ); 1723 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 1724 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 1725 ciInstanceKlass* ik = base_k->as_instance_klass(); 1726 // See if we can become precise: no subklasses and no interface 1727 if (!ik->is_interface() && !ik->has_subklass()) { 1728 //assert(!UseExactTypes, "this code should be useless with exact types"); 1729 // Add a dependence; if any subclass added we need to recompile 1730 if (!ik->is_final()) { 1731 phase->C->dependencies()->assert_leaf_type(ik); 1732 } 1733 // Return precise array klass 1734 return TypeKlassPtr::make(ak); 1735 } 1736 } 1737 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 1738 } else { // Found a type-array? 1739 //assert(!UseExactTypes, "this code should be useless with exact types"); 1740 assert( ak->is_type_array_klass(), "" ); 1741 return TypeKlassPtr::make(ak); // These are always precise 1742 } 1743 } 1744 } 1745 1746 // Check for loading klass from an array klass 1747 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1748 if (tkls != NULL && !StressReflectiveCode) { 1749 ciKlass* klass = tkls->klass(); 1750 if( !klass->is_loaded() ) 1751 return _type; // Bail out if not loaded 1752 if( klass->is_obj_array_klass() && 1753 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) { 1754 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 1755 // // Always returning precise element type is incorrect, 1756 // // e.g., element type could be object and array may contain strings 1757 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 1758 1759 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 1760 // according to the element type's subclassing. 1761 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 1762 } 1763 if( klass->is_instance_klass() && tkls->klass_is_exact() && 1764 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) { 1765 ciKlass* sup = klass->as_instance_klass()->super(); 1766 // The field is Klass::_super. Return its (constant) value. 1767 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 1768 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 1769 } 1770 } 1771 1772 // Bailout case 1773 return LoadNode::Value(phase); 1774} 1775 1776//------------------------------Identity--------------------------------------- 1777// To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 1778// Also feed through the klass in Allocate(...klass...)._klass. 1779Node* LoadKlassNode::Identity( PhaseTransform *phase ) { 1780 return klass_identity_common(phase); 1781} 1782 1783Node* LoadNode::klass_identity_common(PhaseTransform *phase ) { 1784 Node* x = LoadNode::Identity(phase); 1785 if (x != this) return x; 1786 1787 // Take apart the address into an oop and and offset. 1788 // Return 'this' if we cannot. 1789 Node* adr = in(MemNode::Address); 1790 intptr_t offset = 0; 1791 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 1792 if (base == NULL) return this; 1793 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 1794 if (toop == NULL) return this; 1795 1796 // We can fetch the klass directly through an AllocateNode. 1797 // This works even if the klass is not constant (clone or newArray). 1798 if (offset == oopDesc::klass_offset_in_bytes()) { 1799 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 1800 if (allocated_klass != NULL) { 1801 return allocated_klass; 1802 } 1803 } 1804 1805 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop. 1806 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass. 1807 // See inline_native_Class_query for occurrences of these patterns. 1808 // Java Example: x.getClass().isAssignableFrom(y) 1809 // Java Example: Array.newInstance(x.getClass().getComponentType(), n) 1810 // 1811 // This improves reflective code, often making the Class 1812 // mirror go completely dead. (Current exception: Class 1813 // mirrors may appear in debug info, but we could clean them out by 1814 // introducing a new debug info operator for klassOop.java_mirror). 1815 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 1816 && (offset == java_lang_Class::klass_offset_in_bytes() || 1817 offset == java_lang_Class::array_klass_offset_in_bytes())) { 1818 // We are loading a special hidden field from a Class mirror, 1819 // the field which points to its Klass or arrayKlass metaobject. 1820 if (base->is_Load()) { 1821 Node* adr2 = base->in(MemNode::Address); 1822 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 1823 if (tkls != NULL && !tkls->empty() 1824 && (tkls->klass()->is_instance_klass() || 1825 tkls->klass()->is_array_klass()) 1826 && adr2->is_AddP() 1827 ) { 1828 int mirror_field = Klass::java_mirror_offset_in_bytes(); 1829 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 1830 mirror_field = in_bytes(arrayKlass::component_mirror_offset()); 1831 } 1832 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) { 1833 return adr2->in(AddPNode::Base); 1834 } 1835 } 1836 } 1837 } 1838 1839 return this; 1840} 1841 1842 1843//------------------------------Value------------------------------------------ 1844const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const { 1845 const Type *t = klass_value_common(phase); 1846 1847 if (t == TypePtr::NULL_PTR) { 1848 return TypeNarrowOop::NULL_PTR; 1849 } 1850 if (t != Type::TOP && !t->isa_narrowoop()) { 1851 assert(t->is_oopptr(), "sanity"); 1852 t = t->is_oopptr()->make_narrowoop(); 1853 } 1854 return t; 1855} 1856 1857//------------------------------Identity--------------------------------------- 1858// To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 1859// Also feed through the klass in Allocate(...klass...)._klass. 1860Node* LoadNKlassNode::Identity( PhaseTransform *phase ) { 1861 Node *x = klass_identity_common(phase); 1862 1863 const Type *t = phase->type( x ); 1864 if( t == Type::TOP ) return x; 1865 if( t->isa_narrowoop()) return x; 1866 1867 return EncodePNode::encode(phase, x); 1868} 1869 1870//------------------------------Value----------------------------------------- 1871const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { 1872 // Either input is TOP ==> the result is TOP 1873 const Type *t1 = phase->type( in(MemNode::Memory) ); 1874 if( t1 == Type::TOP ) return Type::TOP; 1875 Node *adr = in(MemNode::Address); 1876 const Type *t2 = phase->type( adr ); 1877 if( t2 == Type::TOP ) return Type::TOP; 1878 const TypePtr *tp = t2->is_ptr(); 1879 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 1880 const TypeAryPtr *tap = tp->isa_aryptr(); 1881 if( !tap ) return _type; 1882 return tap->size(); 1883} 1884 1885//------------------------------Identity--------------------------------------- 1886// Feed through the length in AllocateArray(...length...)._length. 1887Node* LoadRangeNode::Identity( PhaseTransform *phase ) { 1888 Node* x = LoadINode::Identity(phase); 1889 if (x != this) return x; 1890 1891 // Take apart the address into an oop and and offset. 1892 // Return 'this' if we cannot. 1893 Node* adr = in(MemNode::Address); 1894 intptr_t offset = 0; 1895 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 1896 if (base == NULL) return this; 1897 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 1898 if (tary == NULL) return this; 1899 1900 // We can fetch the length directly through an AllocateArrayNode. 1901 // This works even if the length is not constant (clone or newArray). 1902 if (offset == arrayOopDesc::length_offset_in_bytes()) { 1903 Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase); 1904 if (allocated_length != NULL) { 1905 return allocated_length; 1906 } 1907 } 1908 1909 return this; 1910 1911} 1912//============================================================================= 1913//---------------------------StoreNode::make----------------------------------- 1914// Polymorphic factory method: 1915StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) { 1916 Compile* C = gvn.C; 1917 1918 switch (bt) { 1919 case T_BOOLEAN: 1920 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val); 1921 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val); 1922 case T_CHAR: 1923 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val); 1924 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val); 1925 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val); 1926 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val); 1927 case T_ADDRESS: 1928 case T_OBJECT: 1929#ifdef _LP64 1930 if (adr->bottom_type()->is_ptr_to_narrowoop() || 1931 (UseCompressedOops && val->bottom_type()->isa_klassptr() && 1932 adr->bottom_type()->isa_rawptr())) { 1933 const TypePtr* type = val->bottom_type()->is_ptr(); 1934 Node* cp = EncodePNode::encode(&gvn, val); 1935 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, cp); 1936 } else 1937#endif 1938 { 1939 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val); 1940 } 1941 } 1942 ShouldNotReachHere(); 1943 return (StoreNode*)NULL; 1944} 1945 1946StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) { 1947 bool require_atomic = true; 1948 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic); 1949} 1950 1951 1952//--------------------------bottom_type---------------------------------------- 1953const Type *StoreNode::bottom_type() const { 1954 return Type::MEMORY; 1955} 1956 1957//------------------------------hash------------------------------------------- 1958uint StoreNode::hash() const { 1959 // unroll addition of interesting fields 1960 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 1961 1962 // Since they are not commoned, do not hash them: 1963 return NO_HASH; 1964} 1965 1966//------------------------------Ideal------------------------------------------ 1967// Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 1968// When a store immediately follows a relevant allocation/initialization, 1969// try to capture it into the initialization, or hoist it above. 1970Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1971 Node* p = MemNode::Ideal_common(phase, can_reshape); 1972 if (p) return (p == NodeSentinel) ? NULL : p; 1973 1974 Node* mem = in(MemNode::Memory); 1975 Node* address = in(MemNode::Address); 1976 1977 // Back-to-back stores to same address? Fold em up. 1978 // Generally unsafe if I have intervening uses... 1979 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) { 1980 // Looking at a dead closed cycle of memory? 1981 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 1982 1983 assert(Opcode() == mem->Opcode() || 1984 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, 1985 "no mismatched stores, except on raw memory"); 1986 1987 if (mem->outcnt() == 1 && // check for intervening uses 1988 mem->as_Store()->memory_size() <= this->memory_size()) { 1989 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. 1990 // For example, 'mem' might be the final state at a conditional return. 1991 // Or, 'mem' might be used by some node which is live at the same time 1992 // 'this' is live, which might be unschedulable. So, require exactly 1993 // ONE user, the 'this' store, until such time as we clone 'mem' for 1994 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). 1995 if (can_reshape) { // (%%% is this an anachronism?) 1996 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), 1997 phase->is_IterGVN()); 1998 } else { 1999 // It's OK to do this in the parser, since DU info is always accurate, 2000 // and the parser always refers to nodes via SafePointNode maps. 2001 set_req(MemNode::Memory, mem->in(MemNode::Memory)); 2002 } 2003 return this; 2004 } 2005 } 2006 2007 // Capture an unaliased, unconditional, simple store into an initializer. 2008 // Or, if it is independent of the allocation, hoist it above the allocation. 2009 if (ReduceFieldZeroing && /*can_reshape &&*/ 2010 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2011 InitializeNode* init = mem->in(0)->as_Initialize(); 2012 intptr_t offset = init->can_capture_store(this, phase); 2013 if (offset > 0) { 2014 Node* moved = init->capture_store(this, offset, phase); 2015 // If the InitializeNode captured me, it made a raw copy of me, 2016 // and I need to disappear. 2017 if (moved != NULL) { 2018 // %%% hack to ensure that Ideal returns a new node: 2019 mem = MergeMemNode::make(phase->C, mem); 2020 return mem; // fold me away 2021 } 2022 } 2023 } 2024 2025 return NULL; // No further progress 2026} 2027 2028//------------------------------Value----------------------------------------- 2029const Type *StoreNode::Value( PhaseTransform *phase ) const { 2030 // Either input is TOP ==> the result is TOP 2031 const Type *t1 = phase->type( in(MemNode::Memory) ); 2032 if( t1 == Type::TOP ) return Type::TOP; 2033 const Type *t2 = phase->type( in(MemNode::Address) ); 2034 if( t2 == Type::TOP ) return Type::TOP; 2035 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2036 if( t3 == Type::TOP ) return Type::TOP; 2037 return Type::MEMORY; 2038} 2039 2040//------------------------------Identity--------------------------------------- 2041// Remove redundant stores: 2042// Store(m, p, Load(m, p)) changes to m. 2043// Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2044Node *StoreNode::Identity( PhaseTransform *phase ) { 2045 Node* mem = in(MemNode::Memory); 2046 Node* adr = in(MemNode::Address); 2047 Node* val = in(MemNode::ValueIn); 2048 2049 // Load then Store? Then the Store is useless 2050 if (val->is_Load() && 2051 phase->eqv_uncast( val->in(MemNode::Address), adr ) && 2052 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) && 2053 val->as_Load()->store_Opcode() == Opcode()) { 2054 return mem; 2055 } 2056 2057 // Two stores in a row of the same value? 2058 if (mem->is_Store() && 2059 phase->eqv_uncast( mem->in(MemNode::Address), adr ) && 2060 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) && 2061 mem->Opcode() == Opcode()) { 2062 return mem; 2063 } 2064 2065 // Store of zero anywhere into a freshly-allocated object? 2066 // Then the store is useless. 2067 // (It must already have been captured by the InitializeNode.) 2068 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2069 // a newly allocated object is already all-zeroes everywhere 2070 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2071 return mem; 2072 } 2073 2074 // the store may also apply to zero-bits in an earlier object 2075 Node* prev_mem = find_previous_store(phase); 2076 // Steps (a), (b): Walk past independent stores to find an exact match. 2077 if (prev_mem != NULL) { 2078 Node* prev_val = can_see_stored_value(prev_mem, phase); 2079 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2080 // prev_val and val might differ by a cast; it would be good 2081 // to keep the more informative of the two. 2082 return mem; 2083 } 2084 } 2085 } 2086 2087 return this; 2088} 2089 2090//------------------------------match_edge------------------------------------- 2091// Do we Match on this edge index or not? Match only memory & value 2092uint StoreNode::match_edge(uint idx) const { 2093 return idx == MemNode::Address || idx == MemNode::ValueIn; 2094} 2095 2096//------------------------------cmp-------------------------------------------- 2097// Do not common stores up together. They generally have to be split 2098// back up anyways, so do not bother. 2099uint StoreNode::cmp( const Node &n ) const { 2100 return (&n == this); // Always fail except on self 2101} 2102 2103//------------------------------Ideal_masked_input----------------------------- 2104// Check for a useless mask before a partial-word store 2105// (StoreB ... (AndI valIn conIa) ) 2106// If (conIa & mask == mask) this simplifies to 2107// (StoreB ... (valIn) ) 2108Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2109 Node *val = in(MemNode::ValueIn); 2110 if( val->Opcode() == Op_AndI ) { 2111 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2112 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2113 set_req(MemNode::ValueIn, val->in(1)); 2114 return this; 2115 } 2116 } 2117 return NULL; 2118} 2119 2120 2121//------------------------------Ideal_sign_extended_input---------------------- 2122// Check for useless sign-extension before a partial-word store 2123// (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2124// If (conIL == conIR && conIR <= num_bits) this simplifies to 2125// (StoreB ... (valIn) ) 2126Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2127 Node *val = in(MemNode::ValueIn); 2128 if( val->Opcode() == Op_RShiftI ) { 2129 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2130 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2131 Node *shl = val->in(1); 2132 if( shl->Opcode() == Op_LShiftI ) { 2133 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2134 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2135 set_req(MemNode::ValueIn, shl->in(1)); 2136 return this; 2137 } 2138 } 2139 } 2140 } 2141 return NULL; 2142} 2143 2144//------------------------------value_never_loaded----------------------------------- 2145// Determine whether there are any possible loads of the value stored. 2146// For simplicity, we actually check if there are any loads from the 2147// address stored to, not just for loads of the value stored by this node. 2148// 2149bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2150 Node *adr = in(Address); 2151 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2152 if (adr_oop == NULL) 2153 return false; 2154 if (!adr_oop->is_instance_field()) 2155 return false; // if not a distinct instance, there may be aliases of the address 2156 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2157 Node *use = adr->fast_out(i); 2158 int opc = use->Opcode(); 2159 if (use->is_Load() || use->is_LoadStore()) { 2160 return false; 2161 } 2162 } 2163 return true; 2164} 2165 2166//============================================================================= 2167//------------------------------Ideal------------------------------------------ 2168// If the store is from an AND mask that leaves the low bits untouched, then 2169// we can skip the AND operation. If the store is from a sign-extension 2170// (a left shift, then right shift) we can skip both. 2171Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2172 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2173 if( progress != NULL ) return progress; 2174 2175 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2176 if( progress != NULL ) return progress; 2177 2178 // Finally check the default case 2179 return StoreNode::Ideal(phase, can_reshape); 2180} 2181 2182//============================================================================= 2183//------------------------------Ideal------------------------------------------ 2184// If the store is from an AND mask that leaves the low bits untouched, then 2185// we can skip the AND operation 2186Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2187 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2188 if( progress != NULL ) return progress; 2189 2190 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2191 if( progress != NULL ) return progress; 2192 2193 // Finally check the default case 2194 return StoreNode::Ideal(phase, can_reshape); 2195} 2196 2197//============================================================================= 2198//------------------------------Identity--------------------------------------- 2199Node *StoreCMNode::Identity( PhaseTransform *phase ) { 2200 // No need to card mark when storing a null ptr 2201 Node* my_store = in(MemNode::OopStore); 2202 if (my_store->is_Store()) { 2203 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2204 if( t1 == TypePtr::NULL_PTR ) { 2205 return in(MemNode::Memory); 2206 } 2207 } 2208 return this; 2209} 2210 2211//------------------------------Value----------------------------------------- 2212const Type *StoreCMNode::Value( PhaseTransform *phase ) const { 2213 // Either input is TOP ==> the result is TOP 2214 const Type *t = phase->type( in(MemNode::Memory) ); 2215 if( t == Type::TOP ) return Type::TOP; 2216 t = phase->type( in(MemNode::Address) ); 2217 if( t == Type::TOP ) return Type::TOP; 2218 t = phase->type( in(MemNode::ValueIn) ); 2219 if( t == Type::TOP ) return Type::TOP; 2220 // If extra input is TOP ==> the result is TOP 2221 t = phase->type( in(MemNode::OopStore) ); 2222 if( t == Type::TOP ) return Type::TOP; 2223 2224 return StoreNode::Value( phase ); 2225} 2226 2227 2228//============================================================================= 2229//----------------------------------SCMemProjNode------------------------------ 2230const Type * SCMemProjNode::Value( PhaseTransform *phase ) const 2231{ 2232 return bottom_type(); 2233} 2234 2235//============================================================================= 2236LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) { 2237 init_req(MemNode::Control, c ); 2238 init_req(MemNode::Memory , mem); 2239 init_req(MemNode::Address, adr); 2240 init_req(MemNode::ValueIn, val); 2241 init_req( ExpectedIn, ex ); 2242 init_class_id(Class_LoadStore); 2243 2244} 2245 2246//============================================================================= 2247//-------------------------------adr_type-------------------------------------- 2248// Do we Match on this edge index or not? Do not match memory 2249const TypePtr* ClearArrayNode::adr_type() const { 2250 Node *adr = in(3); 2251 return MemNode::calculate_adr_type(adr->bottom_type()); 2252} 2253 2254//------------------------------match_edge------------------------------------- 2255// Do we Match on this edge index or not? Do not match memory 2256uint ClearArrayNode::match_edge(uint idx) const { 2257 return idx > 1; 2258} 2259 2260//------------------------------Identity--------------------------------------- 2261// Clearing a zero length array does nothing 2262Node *ClearArrayNode::Identity( PhaseTransform *phase ) { 2263 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2264} 2265 2266//------------------------------Idealize--------------------------------------- 2267// Clearing a short array is faster with stores 2268Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2269 const int unit = BytesPerLong; 2270 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2271 if (!t) return NULL; 2272 if (!t->is_con()) return NULL; 2273 intptr_t raw_count = t->get_con(); 2274 intptr_t size = raw_count; 2275 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2276 // Clearing nothing uses the Identity call. 2277 // Negative clears are possible on dead ClearArrays 2278 // (see jck test stmt114.stmt11402.val). 2279 if (size <= 0 || size % unit != 0) return NULL; 2280 intptr_t count = size / unit; 2281 // Length too long; use fast hardware clear 2282 if (size > Matcher::init_array_short_size) return NULL; 2283 Node *mem = in(1); 2284 if( phase->type(mem)==Type::TOP ) return NULL; 2285 Node *adr = in(3); 2286 const Type* at = phase->type(adr); 2287 if( at==Type::TOP ) return NULL; 2288 const TypePtr* atp = at->isa_ptr(); 2289 // adjust atp to be the correct array element address type 2290 if (atp == NULL) atp = TypePtr::BOTTOM; 2291 else atp = atp->add_offset(Type::OffsetBot); 2292 // Get base for derived pointer purposes 2293 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2294 Node *base = adr->in(1); 2295 2296 Node *zero = phase->makecon(TypeLong::ZERO); 2297 Node *off = phase->MakeConX(BytesPerLong); 2298 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2299 count--; 2300 while( count-- ) { 2301 mem = phase->transform(mem); 2302 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off)); 2303 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); 2304 } 2305 return mem; 2306} 2307 2308//----------------------------clear_memory------------------------------------- 2309// Generate code to initialize object storage to zero. 2310Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2311 intptr_t start_offset, 2312 Node* end_offset, 2313 PhaseGVN* phase) { 2314 Compile* C = phase->C; 2315 intptr_t offset = start_offset; 2316 2317 int unit = BytesPerLong; 2318 if ((offset % unit) != 0) { 2319 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset)); 2320 adr = phase->transform(adr); 2321 const TypePtr* atp = TypeRawPtr::BOTTOM; 2322 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2323 mem = phase->transform(mem); 2324 offset += BytesPerInt; 2325 } 2326 assert((offset % unit) == 0, ""); 2327 2328 // Initialize the remaining stuff, if any, with a ClearArray. 2329 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2330} 2331 2332Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2333 Node* start_offset, 2334 Node* end_offset, 2335 PhaseGVN* phase) { 2336 if (start_offset == end_offset) { 2337 // nothing to do 2338 return mem; 2339 } 2340 2341 Compile* C = phase->C; 2342 int unit = BytesPerLong; 2343 Node* zbase = start_offset; 2344 Node* zend = end_offset; 2345 2346 // Scale to the unit required by the CPU: 2347 if (!Matcher::init_array_count_is_in_bytes) { 2348 Node* shift = phase->intcon(exact_log2(unit)); 2349 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) ); 2350 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) ); 2351 } 2352 2353 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) ); 2354 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT); 2355 2356 // Bulk clear double-words 2357 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) ); 2358 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr); 2359 return phase->transform(mem); 2360} 2361 2362Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2363 intptr_t start_offset, 2364 intptr_t end_offset, 2365 PhaseGVN* phase) { 2366 if (start_offset == end_offset) { 2367 // nothing to do 2368 return mem; 2369 } 2370 2371 Compile* C = phase->C; 2372 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2373 intptr_t done_offset = end_offset; 2374 if ((done_offset % BytesPerLong) != 0) { 2375 done_offset -= BytesPerInt; 2376 } 2377 if (done_offset > start_offset) { 2378 mem = clear_memory(ctl, mem, dest, 2379 start_offset, phase->MakeConX(done_offset), phase); 2380 } 2381 if (done_offset < end_offset) { // emit the final 32-bit store 2382 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset)); 2383 adr = phase->transform(adr); 2384 const TypePtr* atp = TypeRawPtr::BOTTOM; 2385 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); 2386 mem = phase->transform(mem); 2387 done_offset += BytesPerInt; 2388 } 2389 assert(done_offset == end_offset, ""); 2390 return mem; 2391} 2392 2393//============================================================================= 2394// Do we match on this edge? No memory edges 2395uint StrCompNode::match_edge(uint idx) const { 2396 return idx == 5 || idx == 6; 2397} 2398 2399//------------------------------Ideal------------------------------------------ 2400// Return a node which is more "ideal" than the current node. Strip out 2401// control copies 2402Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2403 return remove_dead_region(phase, can_reshape) ? this : NULL; 2404} 2405 2406//------------------------------Ideal------------------------------------------ 2407// Return a node which is more "ideal" than the current node. Strip out 2408// control copies 2409Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2410 return remove_dead_region(phase, can_reshape) ? this : NULL; 2411} 2412 2413 2414//============================================================================= 2415MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2416 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2417 _adr_type(C->get_adr_type(alias_idx)) 2418{ 2419 init_class_id(Class_MemBar); 2420 Node* top = C->top(); 2421 init_req(TypeFunc::I_O,top); 2422 init_req(TypeFunc::FramePtr,top); 2423 init_req(TypeFunc::ReturnAdr,top); 2424 if (precedent != NULL) 2425 init_req(TypeFunc::Parms, precedent); 2426} 2427 2428//------------------------------cmp-------------------------------------------- 2429uint MemBarNode::hash() const { return NO_HASH; } 2430uint MemBarNode::cmp( const Node &n ) const { 2431 return (&n == this); // Always fail except on self 2432} 2433 2434//------------------------------make------------------------------------------- 2435MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2436 int len = Precedent + (pn == NULL? 0: 1); 2437 switch (opcode) { 2438 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn); 2439 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn); 2440 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn); 2441 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn); 2442 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn); 2443 default: ShouldNotReachHere(); return NULL; 2444 } 2445} 2446 2447//------------------------------Ideal------------------------------------------ 2448// Return a node which is more "ideal" than the current node. Strip out 2449// control copies 2450Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2451 if (remove_dead_region(phase, can_reshape)) return this; 2452 return NULL; 2453} 2454 2455//------------------------------Value------------------------------------------ 2456const Type *MemBarNode::Value( PhaseTransform *phase ) const { 2457 if( !in(0) ) return Type::TOP; 2458 if( phase->type(in(0)) == Type::TOP ) 2459 return Type::TOP; 2460 return TypeTuple::MEMBAR; 2461} 2462 2463//------------------------------match------------------------------------------ 2464// Construct projections for memory. 2465Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 2466 switch (proj->_con) { 2467 case TypeFunc::Control: 2468 case TypeFunc::Memory: 2469 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 2470 } 2471 ShouldNotReachHere(); 2472 return NULL; 2473} 2474 2475//===========================InitializeNode==================================== 2476// SUMMARY: 2477// This node acts as a memory barrier on raw memory, after some raw stores. 2478// The 'cooked' oop value feeds from the Initialize, not the Allocation. 2479// The Initialize can 'capture' suitably constrained stores as raw inits. 2480// It can coalesce related raw stores into larger units (called 'tiles'). 2481// It can avoid zeroing new storage for memory units which have raw inits. 2482// At macro-expansion, it is marked 'complete', and does not optimize further. 2483// 2484// EXAMPLE: 2485// The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 2486// ctl = incoming control; mem* = incoming memory 2487// (Note: A star * on a memory edge denotes I/O and other standard edges.) 2488// First allocate uninitialized memory and fill in the header: 2489// alloc = (Allocate ctl mem* 16 #short[].klass ...) 2490// ctl := alloc.Control; mem* := alloc.Memory* 2491// rawmem = alloc.Memory; rawoop = alloc.RawAddress 2492// Then initialize to zero the non-header parts of the raw memory block: 2493// init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 2494// ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 2495// After the initialize node executes, the object is ready for service: 2496// oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 2497// Suppose its body is immediately initialized as {1,2}: 2498// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 2499// store2 = (StoreC init.Control store1 (+ oop 14) 2) 2500// mem.SLICE(#short[*]) := store2 2501// 2502// DETAILS: 2503// An InitializeNode collects and isolates object initialization after 2504// an AllocateNode and before the next possible safepoint. As a 2505// memory barrier (MemBarNode), it keeps critical stores from drifting 2506// down past any safepoint or any publication of the allocation. 2507// Before this barrier, a newly-allocated object may have uninitialized bits. 2508// After this barrier, it may be treated as a real oop, and GC is allowed. 2509// 2510// The semantics of the InitializeNode include an implicit zeroing of 2511// the new object from object header to the end of the object. 2512// (The object header and end are determined by the AllocateNode.) 2513// 2514// Certain stores may be added as direct inputs to the InitializeNode. 2515// These stores must update raw memory, and they must be to addresses 2516// derived from the raw address produced by AllocateNode, and with 2517// a constant offset. They must be ordered by increasing offset. 2518// The first one is at in(RawStores), the last at in(req()-1). 2519// Unlike most memory operations, they are not linked in a chain, 2520// but are displayed in parallel as users of the rawmem output of 2521// the allocation. 2522// 2523// (See comments in InitializeNode::capture_store, which continue 2524// the example given above.) 2525// 2526// When the associated Allocate is macro-expanded, the InitializeNode 2527// may be rewritten to optimize collected stores. A ClearArrayNode 2528// may also be created at that point to represent any required zeroing. 2529// The InitializeNode is then marked 'complete', prohibiting further 2530// capturing of nearby memory operations. 2531// 2532// During macro-expansion, all captured initializations which store 2533// constant values of 32 bits or smaller are coalesced (if advantagous) 2534// into larger 'tiles' 32 or 64 bits. This allows an object to be 2535// initialized in fewer memory operations. Memory words which are 2536// covered by neither tiles nor non-constant stores are pre-zeroed 2537// by explicit stores of zero. (The code shape happens to do all 2538// zeroing first, then all other stores, with both sequences occurring 2539// in order of ascending offsets.) 2540// 2541// Alternatively, code may be inserted between an AllocateNode and its 2542// InitializeNode, to perform arbitrary initialization of the new object. 2543// E.g., the object copying intrinsics insert complex data transfers here. 2544// The initialization must then be marked as 'complete' disable the 2545// built-in zeroing semantics and the collection of initializing stores. 2546// 2547// While an InitializeNode is incomplete, reads from the memory state 2548// produced by it are optimizable if they match the control edge and 2549// new oop address associated with the allocation/initialization. 2550// They return a stored value (if the offset matches) or else zero. 2551// A write to the memory state, if it matches control and address, 2552// and if it is to a constant offset, may be 'captured' by the 2553// InitializeNode. It is cloned as a raw memory operation and rewired 2554// inside the initialization, to the raw oop produced by the allocation. 2555// Operations on addresses which are provably distinct (e.g., to 2556// other AllocateNodes) are allowed to bypass the initialization. 2557// 2558// The effect of all this is to consolidate object initialization 2559// (both arrays and non-arrays, both piecewise and bulk) into a 2560// single location, where it can be optimized as a unit. 2561// 2562// Only stores with an offset less than TrackedInitializationLimit words 2563// will be considered for capture by an InitializeNode. This puts a 2564// reasonable limit on the complexity of optimized initializations. 2565 2566//---------------------------InitializeNode------------------------------------ 2567InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 2568 : _is_complete(false), 2569 MemBarNode(C, adr_type, rawoop) 2570{ 2571 init_class_id(Class_Initialize); 2572 2573 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 2574 assert(in(RawAddress) == rawoop, "proper init"); 2575 // Note: allocation() can be NULL, for secondary initialization barriers 2576} 2577 2578// Since this node is not matched, it will be processed by the 2579// register allocator. Declare that there are no constraints 2580// on the allocation of the RawAddress edge. 2581const RegMask &InitializeNode::in_RegMask(uint idx) const { 2582 // This edge should be set to top, by the set_complete. But be conservative. 2583 if (idx == InitializeNode::RawAddress) 2584 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 2585 return RegMask::Empty; 2586} 2587 2588Node* InitializeNode::memory(uint alias_idx) { 2589 Node* mem = in(Memory); 2590 if (mem->is_MergeMem()) { 2591 return mem->as_MergeMem()->memory_at(alias_idx); 2592 } else { 2593 // incoming raw memory is not split 2594 return mem; 2595 } 2596} 2597 2598bool InitializeNode::is_non_zero() { 2599 if (is_complete()) return false; 2600 remove_extra_zeroes(); 2601 return (req() > RawStores); 2602} 2603 2604void InitializeNode::set_complete(PhaseGVN* phase) { 2605 assert(!is_complete(), "caller responsibility"); 2606 _is_complete = true; 2607 2608 // After this node is complete, it contains a bunch of 2609 // raw-memory initializations. There is no need for 2610 // it to have anything to do with non-raw memory effects. 2611 // Therefore, tell all non-raw users to re-optimize themselves, 2612 // after skipping the memory effects of this initialization. 2613 PhaseIterGVN* igvn = phase->is_IterGVN(); 2614 if (igvn) igvn->add_users_to_worklist(this); 2615} 2616 2617// convenience function 2618// return false if the init contains any stores already 2619bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 2620 InitializeNode* init = initialization(); 2621 if (init == NULL || init->is_complete()) return false; 2622 init->remove_extra_zeroes(); 2623 // for now, if this allocation has already collected any inits, bail: 2624 if (init->is_non_zero()) return false; 2625 init->set_complete(phase); 2626 return true; 2627} 2628 2629void InitializeNode::remove_extra_zeroes() { 2630 if (req() == RawStores) return; 2631 Node* zmem = zero_memory(); 2632 uint fill = RawStores; 2633 for (uint i = fill; i < req(); i++) { 2634 Node* n = in(i); 2635 if (n->is_top() || n == zmem) continue; // skip 2636 if (fill < i) set_req(fill, n); // compact 2637 ++fill; 2638 } 2639 // delete any empty spaces created: 2640 while (fill < req()) { 2641 del_req(fill); 2642 } 2643} 2644 2645// Helper for remembering which stores go with which offsets. 2646intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 2647 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 2648 intptr_t offset = -1; 2649 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 2650 phase, offset); 2651 if (base == NULL) return -1; // something is dead, 2652 if (offset < 0) return -1; // dead, dead 2653 return offset; 2654} 2655 2656// Helper for proving that an initialization expression is 2657// "simple enough" to be folded into an object initialization. 2658// Attempts to prove that a store's initial value 'n' can be captured 2659// within the initialization without creating a vicious cycle, such as: 2660// { Foo p = new Foo(); p.next = p; } 2661// True for constants and parameters and small combinations thereof. 2662bool InitializeNode::detect_init_independence(Node* n, 2663 bool st_is_pinned, 2664 int& count) { 2665 if (n == NULL) return true; // (can this really happen?) 2666 if (n->is_Proj()) n = n->in(0); 2667 if (n == this) return false; // found a cycle 2668 if (n->is_Con()) return true; 2669 if (n->is_Start()) return true; // params, etc., are OK 2670 if (n->is_Root()) return true; // even better 2671 2672 Node* ctl = n->in(0); 2673 if (ctl != NULL && !ctl->is_top()) { 2674 if (ctl->is_Proj()) ctl = ctl->in(0); 2675 if (ctl == this) return false; 2676 2677 // If we already know that the enclosing memory op is pinned right after 2678 // the init, then any control flow that the store has picked up 2679 // must have preceded the init, or else be equal to the init. 2680 // Even after loop optimizations (which might change control edges) 2681 // a store is never pinned *before* the availability of its inputs. 2682 if (!MemNode::all_controls_dominate(n, this)) 2683 return false; // failed to prove a good control 2684 2685 } 2686 2687 // Check data edges for possible dependencies on 'this'. 2688 if ((count += 1) > 20) return false; // complexity limit 2689 for (uint i = 1; i < n->req(); i++) { 2690 Node* m = n->in(i); 2691 if (m == NULL || m == n || m->is_top()) continue; 2692 uint first_i = n->find_edge(m); 2693 if (i != first_i) continue; // process duplicate edge just once 2694 if (!detect_init_independence(m, st_is_pinned, count)) { 2695 return false; 2696 } 2697 } 2698 2699 return true; 2700} 2701 2702// Here are all the checks a Store must pass before it can be moved into 2703// an initialization. Returns zero if a check fails. 2704// On success, returns the (constant) offset to which the store applies, 2705// within the initialized memory. 2706intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) { 2707 const int FAIL = 0; 2708 if (st->req() != MemNode::ValueIn + 1) 2709 return FAIL; // an inscrutable StoreNode (card mark?) 2710 Node* ctl = st->in(MemNode::Control); 2711 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 2712 return FAIL; // must be unconditional after the initialization 2713 Node* mem = st->in(MemNode::Memory); 2714 if (!(mem->is_Proj() && mem->in(0) == this)) 2715 return FAIL; // must not be preceded by other stores 2716 Node* adr = st->in(MemNode::Address); 2717 intptr_t offset; 2718 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 2719 if (alloc == NULL) 2720 return FAIL; // inscrutable address 2721 if (alloc != allocation()) 2722 return FAIL; // wrong allocation! (store needs to float up) 2723 Node* val = st->in(MemNode::ValueIn); 2724 int complexity_count = 0; 2725 if (!detect_init_independence(val, true, complexity_count)) 2726 return FAIL; // stored value must be 'simple enough' 2727 2728 return offset; // success 2729} 2730 2731// Find the captured store in(i) which corresponds to the range 2732// [start..start+size) in the initialized object. 2733// If there is one, return its index i. If there isn't, return the 2734// negative of the index where it should be inserted. 2735// Return 0 if the queried range overlaps an initialization boundary 2736// or if dead code is encountered. 2737// If size_in_bytes is zero, do not bother with overlap checks. 2738int InitializeNode::captured_store_insertion_point(intptr_t start, 2739 int size_in_bytes, 2740 PhaseTransform* phase) { 2741 const int FAIL = 0, MAX_STORE = BytesPerLong; 2742 2743 if (is_complete()) 2744 return FAIL; // arraycopy got here first; punt 2745 2746 assert(allocation() != NULL, "must be present"); 2747 2748 // no negatives, no header fields: 2749 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 2750 2751 // after a certain size, we bail out on tracking all the stores: 2752 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 2753 if (start >= ti_limit) return FAIL; 2754 2755 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 2756 if (i >= limit) return -(int)i; // not found; here is where to put it 2757 2758 Node* st = in(i); 2759 intptr_t st_off = get_store_offset(st, phase); 2760 if (st_off < 0) { 2761 if (st != zero_memory()) { 2762 return FAIL; // bail out if there is dead garbage 2763 } 2764 } else if (st_off > start) { 2765 // ...we are done, since stores are ordered 2766 if (st_off < start + size_in_bytes) { 2767 return FAIL; // the next store overlaps 2768 } 2769 return -(int)i; // not found; here is where to put it 2770 } else if (st_off < start) { 2771 if (size_in_bytes != 0 && 2772 start < st_off + MAX_STORE && 2773 start < st_off + st->as_Store()->memory_size()) { 2774 return FAIL; // the previous store overlaps 2775 } 2776 } else { 2777 if (size_in_bytes != 0 && 2778 st->as_Store()->memory_size() != size_in_bytes) { 2779 return FAIL; // mismatched store size 2780 } 2781 return i; 2782 } 2783 2784 ++i; 2785 } 2786} 2787 2788// Look for a captured store which initializes at the offset 'start' 2789// with the given size. If there is no such store, and no other 2790// initialization interferes, then return zero_memory (the memory 2791// projection of the AllocateNode). 2792Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 2793 PhaseTransform* phase) { 2794 assert(stores_are_sane(phase), ""); 2795 int i = captured_store_insertion_point(start, size_in_bytes, phase); 2796 if (i == 0) { 2797 return NULL; // something is dead 2798 } else if (i < 0) { 2799 return zero_memory(); // just primordial zero bits here 2800 } else { 2801 Node* st = in(i); // here is the store at this position 2802 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 2803 return st; 2804 } 2805} 2806 2807// Create, as a raw pointer, an address within my new object at 'offset'. 2808Node* InitializeNode::make_raw_address(intptr_t offset, 2809 PhaseTransform* phase) { 2810 Node* addr = in(RawAddress); 2811 if (offset != 0) { 2812 Compile* C = phase->C; 2813 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr, 2814 phase->MakeConX(offset)) ); 2815 } 2816 return addr; 2817} 2818 2819// Clone the given store, converting it into a raw store 2820// initializing a field or element of my new object. 2821// Caller is responsible for retiring the original store, 2822// with subsume_node or the like. 2823// 2824// From the example above InitializeNode::InitializeNode, 2825// here are the old stores to be captured: 2826// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 2827// store2 = (StoreC init.Control store1 (+ oop 14) 2) 2828// 2829// Here is the changed code; note the extra edges on init: 2830// alloc = (Allocate ...) 2831// rawoop = alloc.RawAddress 2832// rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 2833// rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 2834// init = (Initialize alloc.Control alloc.Memory rawoop 2835// rawstore1 rawstore2) 2836// 2837Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 2838 PhaseTransform* phase) { 2839 assert(stores_are_sane(phase), ""); 2840 2841 if (start < 0) return NULL; 2842 assert(can_capture_store(st, phase) == start, "sanity"); 2843 2844 Compile* C = phase->C; 2845 int size_in_bytes = st->memory_size(); 2846 int i = captured_store_insertion_point(start, size_in_bytes, phase); 2847 if (i == 0) return NULL; // bail out 2848 Node* prev_mem = NULL; // raw memory for the captured store 2849 if (i > 0) { 2850 prev_mem = in(i); // there is a pre-existing store under this one 2851 set_req(i, C->top()); // temporarily disconnect it 2852 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 2853 } else { 2854 i = -i; // no pre-existing store 2855 prev_mem = zero_memory(); // a slice of the newly allocated object 2856 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 2857 set_req(--i, C->top()); // reuse this edge; it has been folded away 2858 else 2859 ins_req(i, C->top()); // build a new edge 2860 } 2861 Node* new_st = st->clone(); 2862 new_st->set_req(MemNode::Control, in(Control)); 2863 new_st->set_req(MemNode::Memory, prev_mem); 2864 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 2865 new_st = phase->transform(new_st); 2866 2867 // At this point, new_st might have swallowed a pre-existing store 2868 // at the same offset, or perhaps new_st might have disappeared, 2869 // if it redundantly stored the same value (or zero to fresh memory). 2870 2871 // In any case, wire it in: 2872 set_req(i, new_st); 2873 2874 // The caller may now kill the old guy. 2875 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 2876 assert(check_st == new_st || check_st == NULL, "must be findable"); 2877 assert(!is_complete(), ""); 2878 return new_st; 2879} 2880 2881static bool store_constant(jlong* tiles, int num_tiles, 2882 intptr_t st_off, int st_size, 2883 jlong con) { 2884 if ((st_off & (st_size-1)) != 0) 2885 return false; // strange store offset (assume size==2**N) 2886 address addr = (address)tiles + st_off; 2887 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 2888 switch (st_size) { 2889 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 2890 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 2891 case sizeof(jint): *(jint*) addr = (jint) con; break; 2892 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 2893 default: return false; // strange store size (detect size!=2**N here) 2894 } 2895 return true; // return success to caller 2896} 2897 2898// Coalesce subword constants into int constants and possibly 2899// into long constants. The goal, if the CPU permits, 2900// is to initialize the object with a small number of 64-bit tiles. 2901// Also, convert floating-point constants to bit patterns. 2902// Non-constants are not relevant to this pass. 2903// 2904// In terms of the running example on InitializeNode::InitializeNode 2905// and InitializeNode::capture_store, here is the transformation 2906// of rawstore1 and rawstore2 into rawstore12: 2907// alloc = (Allocate ...) 2908// rawoop = alloc.RawAddress 2909// tile12 = 0x00010002 2910// rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 2911// init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 2912// 2913void 2914InitializeNode::coalesce_subword_stores(intptr_t header_size, 2915 Node* size_in_bytes, 2916 PhaseGVN* phase) { 2917 Compile* C = phase->C; 2918 2919 assert(stores_are_sane(phase), ""); 2920 // Note: After this pass, they are not completely sane, 2921 // since there may be some overlaps. 2922 2923 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 2924 2925 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 2926 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 2927 size_limit = MIN2(size_limit, ti_limit); 2928 size_limit = align_size_up(size_limit, BytesPerLong); 2929 int num_tiles = size_limit / BytesPerLong; 2930 2931 // allocate space for the tile map: 2932 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 2933 jlong tiles_buf[small_len]; 2934 Node* nodes_buf[small_len]; 2935 jlong inits_buf[small_len]; 2936 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 2937 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 2938 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 2939 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 2940 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 2941 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 2942 // tiles: exact bitwise model of all primitive constants 2943 // nodes: last constant-storing node subsumed into the tiles model 2944 // inits: which bytes (in each tile) are touched by any initializations 2945 2946 //// Pass A: Fill in the tile model with any relevant stores. 2947 2948 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 2949 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 2950 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 2951 Node* zmem = zero_memory(); // initially zero memory state 2952 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 2953 Node* st = in(i); 2954 intptr_t st_off = get_store_offset(st, phase); 2955 2956 // Figure out the store's offset and constant value: 2957 if (st_off < header_size) continue; //skip (ignore header) 2958 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 2959 int st_size = st->as_Store()->memory_size(); 2960 if (st_off + st_size > size_limit) break; 2961 2962 // Record which bytes are touched, whether by constant or not. 2963 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 2964 continue; // skip (strange store size) 2965 2966 const Type* val = phase->type(st->in(MemNode::ValueIn)); 2967 if (!val->singleton()) continue; //skip (non-con store) 2968 BasicType type = val->basic_type(); 2969 2970 jlong con = 0; 2971 switch (type) { 2972 case T_INT: con = val->is_int()->get_con(); break; 2973 case T_LONG: con = val->is_long()->get_con(); break; 2974 case T_FLOAT: con = jint_cast(val->getf()); break; 2975 case T_DOUBLE: con = jlong_cast(val->getd()); break; 2976 default: continue; //skip (odd store type) 2977 } 2978 2979 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 2980 st->Opcode() == Op_StoreL) { 2981 continue; // This StoreL is already optimal. 2982 } 2983 2984 // Store down the constant. 2985 store_constant(tiles, num_tiles, st_off, st_size, con); 2986 2987 intptr_t j = st_off >> LogBytesPerLong; 2988 2989 if (type == T_INT && st_size == BytesPerInt 2990 && (st_off & BytesPerInt) == BytesPerInt) { 2991 jlong lcon = tiles[j]; 2992 if (!Matcher::isSimpleConstant64(lcon) && 2993 st->Opcode() == Op_StoreI) { 2994 // This StoreI is already optimal by itself. 2995 jint* intcon = (jint*) &tiles[j]; 2996 intcon[1] = 0; // undo the store_constant() 2997 2998 // If the previous store is also optimal by itself, back up and 2999 // undo the action of the previous loop iteration... if we can. 3000 // But if we can't, just let the previous half take care of itself. 3001 st = nodes[j]; 3002 st_off -= BytesPerInt; 3003 con = intcon[0]; 3004 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3005 assert(st_off >= header_size, "still ignoring header"); 3006 assert(get_store_offset(st, phase) == st_off, "must be"); 3007 assert(in(i-1) == zmem, "must be"); 3008 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3009 assert(con == tcon->is_int()->get_con(), "must be"); 3010 // Undo the effects of the previous loop trip, which swallowed st: 3011 intcon[0] = 0; // undo store_constant() 3012 set_req(i-1, st); // undo set_req(i, zmem) 3013 nodes[j] = NULL; // undo nodes[j] = st 3014 --old_subword; // undo ++old_subword 3015 } 3016 continue; // This StoreI is already optimal. 3017 } 3018 } 3019 3020 // This store is not needed. 3021 set_req(i, zmem); 3022 nodes[j] = st; // record for the moment 3023 if (st_size < BytesPerLong) // something has changed 3024 ++old_subword; // includes int/float, but who's counting... 3025 else ++old_long; 3026 } 3027 3028 if ((old_subword + old_long) == 0) 3029 return; // nothing more to do 3030 3031 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3032 // Be sure to insert them before overlapping non-constant stores. 3033 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3034 for (int j = 0; j < num_tiles; j++) { 3035 jlong con = tiles[j]; 3036 jlong init = inits[j]; 3037 if (con == 0) continue; 3038 jint con0, con1; // split the constant, address-wise 3039 jint init0, init1; // split the init map, address-wise 3040 { union { jlong con; jint intcon[2]; } u; 3041 u.con = con; 3042 con0 = u.intcon[0]; 3043 con1 = u.intcon[1]; 3044 u.con = init; 3045 init0 = u.intcon[0]; 3046 init1 = u.intcon[1]; 3047 } 3048 3049 Node* old = nodes[j]; 3050 assert(old != NULL, "need the prior store"); 3051 intptr_t offset = (j * BytesPerLong); 3052 3053 bool split = !Matcher::isSimpleConstant64(con); 3054 3055 if (offset < header_size) { 3056 assert(offset + BytesPerInt >= header_size, "second int counts"); 3057 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3058 split = true; // only the second word counts 3059 // Example: int a[] = { 42 ... } 3060 } else if (con0 == 0 && init0 == -1) { 3061 split = true; // first word is covered by full inits 3062 // Example: int a[] = { ... foo(), 42 ... } 3063 } else if (con1 == 0 && init1 == -1) { 3064 split = true; // second word is covered by full inits 3065 // Example: int a[] = { ... 42, foo() ... } 3066 } 3067 3068 // Here's a case where init0 is neither 0 nor -1: 3069 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3070 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3071 // In this case the tile is not split; it is (jlong)42. 3072 // The big tile is stored down, and then the foo() value is inserted. 3073 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3074 3075 Node* ctl = old->in(MemNode::Control); 3076 Node* adr = make_raw_address(offset, phase); 3077 const TypePtr* atp = TypeRawPtr::BOTTOM; 3078 3079 // One or two coalesced stores to plop down. 3080 Node* st[2]; 3081 intptr_t off[2]; 3082 int nst = 0; 3083 if (!split) { 3084 ++new_long; 3085 off[nst] = offset; 3086 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3087 phase->longcon(con), T_LONG); 3088 } else { 3089 // Omit either if it is a zero. 3090 if (con0 != 0) { 3091 ++new_int; 3092 off[nst] = offset; 3093 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3094 phase->intcon(con0), T_INT); 3095 } 3096 if (con1 != 0) { 3097 ++new_int; 3098 offset += BytesPerInt; 3099 adr = make_raw_address(offset, phase); 3100 off[nst] = offset; 3101 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3102 phase->intcon(con1), T_INT); 3103 } 3104 } 3105 3106 // Insert second store first, then the first before the second. 3107 // Insert each one just before any overlapping non-constant stores. 3108 while (nst > 0) { 3109 Node* st1 = st[--nst]; 3110 C->copy_node_notes_to(st1, old); 3111 st1 = phase->transform(st1); 3112 offset = off[nst]; 3113 assert(offset >= header_size, "do not smash header"); 3114 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3115 guarantee(ins_idx != 0, "must re-insert constant store"); 3116 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3117 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3118 set_req(--ins_idx, st1); 3119 else 3120 ins_req(ins_idx, st1); 3121 } 3122 } 3123 3124 if (PrintCompilation && WizardMode) 3125 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3126 old_subword, old_long, new_int, new_long); 3127 if (C->log() != NULL) 3128 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3129 old_subword, old_long, new_int, new_long); 3130 3131 // Clean up any remaining occurrences of zmem: 3132 remove_extra_zeroes(); 3133} 3134 3135// Explore forward from in(start) to find the first fully initialized 3136// word, and return its offset. Skip groups of subword stores which 3137// together initialize full words. If in(start) is itself part of a 3138// fully initialized word, return the offset of in(start). If there 3139// are no following full-word stores, or if something is fishy, return 3140// a negative value. 3141intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3142 int int_map = 0; 3143 intptr_t int_map_off = 0; 3144 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3145 3146 for (uint i = start, limit = req(); i < limit; i++) { 3147 Node* st = in(i); 3148 3149 intptr_t st_off = get_store_offset(st, phase); 3150 if (st_off < 0) break; // return conservative answer 3151 3152 int st_size = st->as_Store()->memory_size(); 3153 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3154 return st_off; // we found a complete word init 3155 } 3156 3157 // update the map: 3158 3159 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); 3160 if (this_int_off != int_map_off) { 3161 // reset the map: 3162 int_map = 0; 3163 int_map_off = this_int_off; 3164 } 3165 3166 int subword_off = st_off - this_int_off; 3167 int_map |= right_n_bits(st_size) << subword_off; 3168 if ((int_map & FULL_MAP) == FULL_MAP) { 3169 return this_int_off; // we found a complete word init 3170 } 3171 3172 // Did this store hit or cross the word boundary? 3173 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); 3174 if (next_int_off == this_int_off + BytesPerInt) { 3175 // We passed the current int, without fully initializing it. 3176 int_map_off = next_int_off; 3177 int_map >>= BytesPerInt; 3178 } else if (next_int_off > this_int_off + BytesPerInt) { 3179 // We passed the current and next int. 3180 return this_int_off + BytesPerInt; 3181 } 3182 } 3183 3184 return -1; 3185} 3186 3187 3188// Called when the associated AllocateNode is expanded into CFG. 3189// At this point, we may perform additional optimizations. 3190// Linearize the stores by ascending offset, to make memory 3191// activity as coherent as possible. 3192Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3193 intptr_t header_size, 3194 Node* size_in_bytes, 3195 PhaseGVN* phase) { 3196 assert(!is_complete(), "not already complete"); 3197 assert(stores_are_sane(phase), ""); 3198 assert(allocation() != NULL, "must be present"); 3199 3200 remove_extra_zeroes(); 3201 3202 if (ReduceFieldZeroing || ReduceBulkZeroing) 3203 // reduce instruction count for common initialization patterns 3204 coalesce_subword_stores(header_size, size_in_bytes, phase); 3205 3206 Node* zmem = zero_memory(); // initially zero memory state 3207 Node* inits = zmem; // accumulating a linearized chain of inits 3208 #ifdef ASSERT 3209 intptr_t first_offset = allocation()->minimum_header_size(); 3210 intptr_t last_init_off = first_offset; // previous init offset 3211 intptr_t last_init_end = first_offset; // previous init offset+size 3212 intptr_t last_tile_end = first_offset; // previous tile offset+size 3213 #endif 3214 intptr_t zeroes_done = header_size; 3215 3216 bool do_zeroing = true; // we might give up if inits are very sparse 3217 int big_init_gaps = 0; // how many large gaps have we seen? 3218 3219 if (ZeroTLAB) do_zeroing = false; 3220 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3221 3222 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3223 Node* st = in(i); 3224 intptr_t st_off = get_store_offset(st, phase); 3225 if (st_off < 0) 3226 break; // unknown junk in the inits 3227 if (st->in(MemNode::Memory) != zmem) 3228 break; // complicated store chains somehow in list 3229 3230 int st_size = st->as_Store()->memory_size(); 3231 intptr_t next_init_off = st_off + st_size; 3232 3233 if (do_zeroing && zeroes_done < next_init_off) { 3234 // See if this store needs a zero before it or under it. 3235 intptr_t zeroes_needed = st_off; 3236 3237 if (st_size < BytesPerInt) { 3238 // Look for subword stores which only partially initialize words. 3239 // If we find some, we must lay down some word-level zeroes first, 3240 // underneath the subword stores. 3241 // 3242 // Examples: 3243 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3244 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3245 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3246 // 3247 // Note: coalesce_subword_stores may have already done this, 3248 // if it was prompted by constant non-zero subword initializers. 3249 // But this case can still arise with non-constant stores. 3250 3251 intptr_t next_full_store = find_next_fullword_store(i, phase); 3252 3253 // In the examples above: 3254 // in(i) p q r s x y z 3255 // st_off 12 13 14 15 12 13 14 3256 // st_size 1 1 1 1 1 1 1 3257 // next_full_s. 12 16 16 16 16 16 16 3258 // z's_done 12 16 16 16 12 16 12 3259 // z's_needed 12 16 16 16 16 16 16 3260 // zsize 0 0 0 0 4 0 4 3261 if (next_full_store < 0) { 3262 // Conservative tack: Zero to end of current word. 3263 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); 3264 } else { 3265 // Zero to beginning of next fully initialized word. 3266 // Or, don't zero at all, if we are already in that word. 3267 assert(next_full_store >= zeroes_needed, "must go forward"); 3268 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3269 zeroes_needed = next_full_store; 3270 } 3271 } 3272 3273 if (zeroes_needed > zeroes_done) { 3274 intptr_t zsize = zeroes_needed - zeroes_done; 3275 // Do some incremental zeroing on rawmem, in parallel with inits. 3276 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3277 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3278 zeroes_done, zeroes_needed, 3279 phase); 3280 zeroes_done = zeroes_needed; 3281 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) 3282 do_zeroing = false; // leave the hole, next time 3283 } 3284 } 3285 3286 // Collect the store and move on: 3287 st->set_req(MemNode::Memory, inits); 3288 inits = st; // put it on the linearized chain 3289 set_req(i, zmem); // unhook from previous position 3290 3291 if (zeroes_done == st_off) 3292 zeroes_done = next_init_off; 3293 3294 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3295 3296 #ifdef ASSERT 3297 // Various order invariants. Weaker than stores_are_sane because 3298 // a large constant tile can be filled in by smaller non-constant stores. 3299 assert(st_off >= last_init_off, "inits do not reverse"); 3300 last_init_off = st_off; 3301 const Type* val = NULL; 3302 if (st_size >= BytesPerInt && 3303 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3304 (int)val->basic_type() < (int)T_OBJECT) { 3305 assert(st_off >= last_tile_end, "tiles do not overlap"); 3306 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3307 last_tile_end = MAX2(last_tile_end, next_init_off); 3308 } else { 3309 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); 3310 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3311 assert(st_off >= last_init_end, "inits do not overlap"); 3312 last_init_end = next_init_off; // it's a non-tile 3313 } 3314 #endif //ASSERT 3315 } 3316 3317 remove_extra_zeroes(); // clear out all the zmems left over 3318 add_req(inits); 3319 3320 if (!ZeroTLAB) { 3321 // If anything remains to be zeroed, zero it all now. 3322 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3323 // if it is the last unused 4 bytes of an instance, forget about it 3324 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3325 if (zeroes_done + BytesPerLong >= size_limit) { 3326 assert(allocation() != NULL, ""); 3327 Node* klass_node = allocation()->in(AllocateNode::KlassNode); 3328 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3329 if (zeroes_done == k->layout_helper()) 3330 zeroes_done = size_limit; 3331 } 3332 if (zeroes_done < size_limit) { 3333 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3334 zeroes_done, size_in_bytes, phase); 3335 } 3336 } 3337 3338 set_complete(phase); 3339 return rawmem; 3340} 3341 3342 3343#ifdef ASSERT 3344bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3345 if (is_complete()) 3346 return true; // stores could be anything at this point 3347 assert(allocation() != NULL, "must be present"); 3348 intptr_t last_off = allocation()->minimum_header_size(); 3349 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3350 Node* st = in(i); 3351 intptr_t st_off = get_store_offset(st, phase); 3352 if (st_off < 0) continue; // ignore dead garbage 3353 if (last_off > st_off) { 3354 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off); 3355 this->dump(2); 3356 assert(false, "ascending store offsets"); 3357 return false; 3358 } 3359 last_off = st_off + st->as_Store()->memory_size(); 3360 } 3361 return true; 3362} 3363#endif //ASSERT 3364 3365 3366 3367 3368//============================MergeMemNode===================================== 3369// 3370// SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 3371// contributing store or call operations. Each contributor provides the memory 3372// state for a particular "alias type" (see Compile::alias_type). For example, 3373// if a MergeMem has an input X for alias category #6, then any memory reference 3374// to alias category #6 may use X as its memory state input, as an exact equivalent 3375// to using the MergeMem as a whole. 3376// Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 3377// 3378// (Here, the <N> notation gives the index of the relevant adr_type.) 3379// 3380// In one special case (and more cases in the future), alias categories overlap. 3381// The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 3382// states. Therefore, if a MergeMem has only one contributing input W for Bot, 3383// it is exactly equivalent to that state W: 3384// MergeMem(<Bot>: W) <==> W 3385// 3386// Usually, the merge has more than one input. In that case, where inputs 3387// overlap (i.e., one is Bot), the narrower alias type determines the memory 3388// state for that type, and the wider alias type (Bot) fills in everywhere else: 3389// Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 3390// Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 3391// 3392// A merge can take a "wide" memory state as one of its narrow inputs. 3393// This simply means that the merge observes out only the relevant parts of 3394// the wide input. That is, wide memory states arriving at narrow merge inputs 3395// are implicitly "filtered" or "sliced" as necessary. (This is rare.) 3396// 3397// These rules imply that MergeMem nodes may cascade (via their <Bot> links), 3398// and that memory slices "leak through": 3399// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 3400// 3401// But, in such a cascade, repeated memory slices can "block the leak": 3402// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 3403// 3404// In the last example, Y is not part of the combined memory state of the 3405// outermost MergeMem. The system must, of course, prevent unschedulable 3406// memory states from arising, so you can be sure that the state Y is somehow 3407// a precursor to state Y'. 3408// 3409// 3410// REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 3411// of each MergeMemNode array are exactly the numerical alias indexes, including 3412// but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 3413// Compile::alias_type (and kin) produce and manage these indexes. 3414// 3415// By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 3416// (Note that this provides quick access to the top node inside MergeMem methods, 3417// without the need to reach out via TLS to Compile::current.) 3418// 3419// As a consequence of what was just described, a MergeMem that represents a full 3420// memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 3421// containing all alias categories. 3422// 3423// MergeMem nodes never (?) have control inputs, so in(0) is NULL. 3424// 3425// All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 3426// a memory state for the alias type <N>, or else the top node, meaning that 3427// there is no particular input for that alias type. Note that the length of 3428// a MergeMem is variable, and may be extended at any time to accommodate new 3429// memory states at larger alias indexes. When merges grow, they are of course 3430// filled with "top" in the unused in() positions. 3431// 3432// This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 3433// (Top was chosen because it works smoothly with passes like GCM.) 3434// 3435// For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 3436// the type of random VM bits like TLS references.) Since it is always the 3437// first non-Bot memory slice, some low-level loops use it to initialize an 3438// index variable: for (i = AliasIdxRaw; i < req(); i++). 3439// 3440// 3441// ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 3442// the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 3443// the memory state for alias type <N>, or (if there is no particular slice at <N>, 3444// it returns the base memory. To prevent bugs, memory_at does not accept <Top> 3445// or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 3446// MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 3447// 3448// %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 3449// really that different from the other memory inputs. An abbreviation called 3450// "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 3451// 3452// 3453// PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 3454// partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 3455// that "emerges though" the base memory will be marked as excluding the alias types 3456// of the other (narrow-memory) copies which "emerged through" the narrow edges: 3457// 3458// Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 3459// ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 3460// 3461// This strange "subtraction" effect is necessary to ensure IGVN convergence. 3462// (It is currently unimplemented.) As you can see, the resulting merge is 3463// actually a disjoint union of memory states, rather than an overlay. 3464// 3465 3466//------------------------------MergeMemNode----------------------------------- 3467Node* MergeMemNode::make_empty_memory() { 3468 Node* empty_memory = (Node*) Compile::current()->top(); 3469 assert(empty_memory->is_top(), "correct sentinel identity"); 3470 return empty_memory; 3471} 3472 3473MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 3474 init_class_id(Class_MergeMem); 3475 // all inputs are nullified in Node::Node(int) 3476 // set_input(0, NULL); // no control input 3477 3478 // Initialize the edges uniformly to top, for starters. 3479 Node* empty_mem = make_empty_memory(); 3480 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 3481 init_req(i,empty_mem); 3482 } 3483 assert(empty_memory() == empty_mem, ""); 3484 3485 if( new_base != NULL && new_base->is_MergeMem() ) { 3486 MergeMemNode* mdef = new_base->as_MergeMem(); 3487 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 3488 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 3489 mms.set_memory(mms.memory2()); 3490 } 3491 assert(base_memory() == mdef->base_memory(), ""); 3492 } else { 3493 set_base_memory(new_base); 3494 } 3495} 3496 3497// Make a new, untransformed MergeMem with the same base as 'mem'. 3498// If mem is itself a MergeMem, populate the result with the same edges. 3499MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) { 3500 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem); 3501} 3502 3503//------------------------------cmp-------------------------------------------- 3504uint MergeMemNode::hash() const { return NO_HASH; } 3505uint MergeMemNode::cmp( const Node &n ) const { 3506 return (&n == this); // Always fail except on self 3507} 3508 3509//------------------------------Identity--------------------------------------- 3510Node* MergeMemNode::Identity(PhaseTransform *phase) { 3511 // Identity if this merge point does not record any interesting memory 3512 // disambiguations. 3513 Node* base_mem = base_memory(); 3514 Node* empty_mem = empty_memory(); 3515 if (base_mem != empty_mem) { // Memory path is not dead? 3516 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3517 Node* mem = in(i); 3518 if (mem != empty_mem && mem != base_mem) { 3519 return this; // Many memory splits; no change 3520 } 3521 } 3522 } 3523 return base_mem; // No memory splits; ID on the one true input 3524} 3525 3526//------------------------------Ideal------------------------------------------ 3527// This method is invoked recursively on chains of MergeMem nodes 3528Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3529 // Remove chain'd MergeMems 3530 // 3531 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 3532 // relative to the "in(Bot)". Since we are patching both at the same time, 3533 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 3534 // but rewrite each "in(i)" relative to the new "in(Bot)". 3535 Node *progress = NULL; 3536 3537 3538 Node* old_base = base_memory(); 3539 Node* empty_mem = empty_memory(); 3540 if (old_base == empty_mem) 3541 return NULL; // Dead memory path. 3542 3543 MergeMemNode* old_mbase; 3544 if (old_base != NULL && old_base->is_MergeMem()) 3545 old_mbase = old_base->as_MergeMem(); 3546 else 3547 old_mbase = NULL; 3548 Node* new_base = old_base; 3549 3550 // simplify stacked MergeMems in base memory 3551 if (old_mbase) new_base = old_mbase->base_memory(); 3552 3553 // the base memory might contribute new slices beyond my req() 3554 if (old_mbase) grow_to_match(old_mbase); 3555 3556 // Look carefully at the base node if it is a phi. 3557 PhiNode* phi_base; 3558 if (new_base != NULL && new_base->is_Phi()) 3559 phi_base = new_base->as_Phi(); 3560 else 3561 phi_base = NULL; 3562 3563 Node* phi_reg = NULL; 3564 uint phi_len = (uint)-1; 3565 if (phi_base != NULL && !phi_base->is_copy()) { 3566 // do not examine phi if degraded to a copy 3567 phi_reg = phi_base->region(); 3568 phi_len = phi_base->req(); 3569 // see if the phi is unfinished 3570 for (uint i = 1; i < phi_len; i++) { 3571 if (phi_base->in(i) == NULL) { 3572 // incomplete phi; do not look at it yet! 3573 phi_reg = NULL; 3574 phi_len = (uint)-1; 3575 break; 3576 } 3577 } 3578 } 3579 3580 // Note: We do not call verify_sparse on entry, because inputs 3581 // can normalize to the base_memory via subsume_node or similar 3582 // mechanisms. This method repairs that damage. 3583 3584 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 3585 3586 // Look at each slice. 3587 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3588 Node* old_in = in(i); 3589 // calculate the old memory value 3590 Node* old_mem = old_in; 3591 if (old_mem == empty_mem) old_mem = old_base; 3592 assert(old_mem == memory_at(i), ""); 3593 3594 // maybe update (reslice) the old memory value 3595 3596 // simplify stacked MergeMems 3597 Node* new_mem = old_mem; 3598 MergeMemNode* old_mmem; 3599 if (old_mem != NULL && old_mem->is_MergeMem()) 3600 old_mmem = old_mem->as_MergeMem(); 3601 else 3602 old_mmem = NULL; 3603 if (old_mmem == this) { 3604 // This can happen if loops break up and safepoints disappear. 3605 // A merge of BotPtr (default) with a RawPtr memory derived from a 3606 // safepoint can be rewritten to a merge of the same BotPtr with 3607 // the BotPtr phi coming into the loop. If that phi disappears 3608 // also, we can end up with a self-loop of the mergemem. 3609 // In general, if loops degenerate and memory effects disappear, 3610 // a mergemem can be left looking at itself. This simply means 3611 // that the mergemem's default should be used, since there is 3612 // no longer any apparent effect on this slice. 3613 // Note: If a memory slice is a MergeMem cycle, it is unreachable 3614 // from start. Update the input to TOP. 3615 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 3616 } 3617 else if (old_mmem != NULL) { 3618 new_mem = old_mmem->memory_at(i); 3619 } 3620 // else preceeding memory was not a MergeMem 3621 3622 // replace equivalent phis (unfortunately, they do not GVN together) 3623 if (new_mem != NULL && new_mem != new_base && 3624 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 3625 if (new_mem->is_Phi()) { 3626 PhiNode* phi_mem = new_mem->as_Phi(); 3627 for (uint i = 1; i < phi_len; i++) { 3628 if (phi_base->in(i) != phi_mem->in(i)) { 3629 phi_mem = NULL; 3630 break; 3631 } 3632 } 3633 if (phi_mem != NULL) { 3634 // equivalent phi nodes; revert to the def 3635 new_mem = new_base; 3636 } 3637 } 3638 } 3639 3640 // maybe store down a new value 3641 Node* new_in = new_mem; 3642 if (new_in == new_base) new_in = empty_mem; 3643 3644 if (new_in != old_in) { 3645 // Warning: Do not combine this "if" with the previous "if" 3646 // A memory slice might have be be rewritten even if it is semantically 3647 // unchanged, if the base_memory value has changed. 3648 set_req(i, new_in); 3649 progress = this; // Report progress 3650 } 3651 } 3652 3653 if (new_base != old_base) { 3654 set_req(Compile::AliasIdxBot, new_base); 3655 // Don't use set_base_memory(new_base), because we need to update du. 3656 assert(base_memory() == new_base, ""); 3657 progress = this; 3658 } 3659 3660 if( base_memory() == this ) { 3661 // a self cycle indicates this memory path is dead 3662 set_req(Compile::AliasIdxBot, empty_mem); 3663 } 3664 3665 // Resolve external cycles by calling Ideal on a MergeMem base_memory 3666 // Recursion must occur after the self cycle check above 3667 if( base_memory()->is_MergeMem() ) { 3668 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 3669 Node *m = phase->transform(new_mbase); // Rollup any cycles 3670 if( m != NULL && (m->is_top() || 3671 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 3672 // propagate rollup of dead cycle to self 3673 set_req(Compile::AliasIdxBot, empty_mem); 3674 } 3675 } 3676 3677 if( base_memory() == empty_mem ) { 3678 progress = this; 3679 // Cut inputs during Parse phase only. 3680 // During Optimize phase a dead MergeMem node will be subsumed by Top. 3681 if( !can_reshape ) { 3682 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3683 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 3684 } 3685 } 3686 } 3687 3688 if( !progress && base_memory()->is_Phi() && can_reshape ) { 3689 // Check if PhiNode::Ideal's "Split phis through memory merges" 3690 // transform should be attempted. Look for this->phi->this cycle. 3691 uint merge_width = req(); 3692 if (merge_width > Compile::AliasIdxRaw) { 3693 PhiNode* phi = base_memory()->as_Phi(); 3694 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 3695 if (phi->in(i) == this) { 3696 phase->is_IterGVN()->_worklist.push(phi); 3697 break; 3698 } 3699 } 3700 } 3701 } 3702 3703 assert(progress || verify_sparse(), "please, no dups of base"); 3704 return progress; 3705} 3706 3707//-------------------------set_base_memory------------------------------------- 3708void MergeMemNode::set_base_memory(Node *new_base) { 3709 Node* empty_mem = empty_memory(); 3710 set_req(Compile::AliasIdxBot, new_base); 3711 assert(memory_at(req()) == new_base, "must set default memory"); 3712 // Clear out other occurrences of new_base: 3713 if (new_base != empty_mem) { 3714 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3715 if (in(i) == new_base) set_req(i, empty_mem); 3716 } 3717 } 3718} 3719 3720//------------------------------out_RegMask------------------------------------ 3721const RegMask &MergeMemNode::out_RegMask() const { 3722 return RegMask::Empty; 3723} 3724 3725//------------------------------dump_spec-------------------------------------- 3726#ifndef PRODUCT 3727void MergeMemNode::dump_spec(outputStream *st) const { 3728 st->print(" {"); 3729 Node* base_mem = base_memory(); 3730 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 3731 Node* mem = memory_at(i); 3732 if (mem == base_mem) { st->print(" -"); continue; } 3733 st->print( " N%d:", mem->_idx ); 3734 Compile::current()->get_adr_type(i)->dump_on(st); 3735 } 3736 st->print(" }"); 3737} 3738#endif // !PRODUCT 3739 3740 3741#ifdef ASSERT 3742static bool might_be_same(Node* a, Node* b) { 3743 if (a == b) return true; 3744 if (!(a->is_Phi() || b->is_Phi())) return false; 3745 // phis shift around during optimization 3746 return true; // pretty stupid... 3747} 3748 3749// verify a narrow slice (either incoming or outgoing) 3750static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 3751 if (!VerifyAliases) return; // don't bother to verify unless requested 3752 if (is_error_reported()) return; // muzzle asserts when debugging an error 3753 if (Node::in_dump()) return; // muzzle asserts when printing 3754 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 3755 assert(n != NULL, ""); 3756 // Elide intervening MergeMem's 3757 while (n->is_MergeMem()) { 3758 n = n->as_MergeMem()->memory_at(alias_idx); 3759 } 3760 Compile* C = Compile::current(); 3761 const TypePtr* n_adr_type = n->adr_type(); 3762 if (n == m->empty_memory()) { 3763 // Implicit copy of base_memory() 3764 } else if (n_adr_type != TypePtr::BOTTOM) { 3765 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 3766 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 3767 } else { 3768 // A few places like make_runtime_call "know" that VM calls are narrow, 3769 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 3770 bool expected_wide_mem = false; 3771 if (n == m->base_memory()) { 3772 expected_wide_mem = true; 3773 } else if (alias_idx == Compile::AliasIdxRaw || 3774 n == m->memory_at(Compile::AliasIdxRaw)) { 3775 expected_wide_mem = true; 3776 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 3777 // memory can "leak through" calls on channels that 3778 // are write-once. Allow this also. 3779 expected_wide_mem = true; 3780 } 3781 assert(expected_wide_mem, "expected narrow slice replacement"); 3782 } 3783} 3784#else // !ASSERT 3785#define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op 3786#endif 3787 3788 3789//-----------------------------memory_at--------------------------------------- 3790Node* MergeMemNode::memory_at(uint alias_idx) const { 3791 assert(alias_idx >= Compile::AliasIdxRaw || 3792 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 3793 "must avoid base_memory and AliasIdxTop"); 3794 3795 // Otherwise, it is a narrow slice. 3796 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 3797 Compile *C = Compile::current(); 3798 if (is_empty_memory(n)) { 3799 // the array is sparse; empty slots are the "top" node 3800 n = base_memory(); 3801 assert(Node::in_dump() 3802 || n == NULL || n->bottom_type() == Type::TOP 3803 || n->adr_type() == TypePtr::BOTTOM 3804 || n->adr_type() == TypeRawPtr::BOTTOM 3805 || Compile::current()->AliasLevel() == 0, 3806 "must be a wide memory"); 3807 // AliasLevel == 0 if we are organizing the memory states manually. 3808 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 3809 } else { 3810 // make sure the stored slice is sane 3811 #ifdef ASSERT 3812 if (is_error_reported() || Node::in_dump()) { 3813 } else if (might_be_same(n, base_memory())) { 3814 // Give it a pass: It is a mostly harmless repetition of the base. 3815 // This can arise normally from node subsumption during optimization. 3816 } else { 3817 verify_memory_slice(this, alias_idx, n); 3818 } 3819 #endif 3820 } 3821 return n; 3822} 3823 3824//---------------------------set_memory_at------------------------------------- 3825void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 3826 verify_memory_slice(this, alias_idx, n); 3827 Node* empty_mem = empty_memory(); 3828 if (n == base_memory()) n = empty_mem; // collapse default 3829 uint need_req = alias_idx+1; 3830 if (req() < need_req) { 3831 if (n == empty_mem) return; // already the default, so do not grow me 3832 // grow the sparse array 3833 do { 3834 add_req(empty_mem); 3835 } while (req() < need_req); 3836 } 3837 set_req( alias_idx, n ); 3838} 3839 3840 3841 3842//--------------------------iteration_setup------------------------------------ 3843void MergeMemNode::iteration_setup(const MergeMemNode* other) { 3844 if (other != NULL) { 3845 grow_to_match(other); 3846 // invariant: the finite support of mm2 is within mm->req() 3847 #ifdef ASSERT 3848 for (uint i = req(); i < other->req(); i++) { 3849 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 3850 } 3851 #endif 3852 } 3853 // Replace spurious copies of base_memory by top. 3854 Node* base_mem = base_memory(); 3855 if (base_mem != NULL && !base_mem->is_top()) { 3856 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 3857 if (in(i) == base_mem) 3858 set_req(i, empty_memory()); 3859 } 3860 } 3861} 3862 3863//---------------------------grow_to_match------------------------------------- 3864void MergeMemNode::grow_to_match(const MergeMemNode* other) { 3865 Node* empty_mem = empty_memory(); 3866 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 3867 // look for the finite support of the other memory 3868 for (uint i = other->req(); --i >= req(); ) { 3869 if (other->in(i) != empty_mem) { 3870 uint new_len = i+1; 3871 while (req() < new_len) add_req(empty_mem); 3872 break; 3873 } 3874 } 3875} 3876 3877//---------------------------verify_sparse------------------------------------- 3878#ifndef PRODUCT 3879bool MergeMemNode::verify_sparse() const { 3880 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 3881 Node* base_mem = base_memory(); 3882 // The following can happen in degenerate cases, since empty==top. 3883 if (is_empty_memory(base_mem)) return true; 3884 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 3885 assert(in(i) != NULL, "sane slice"); 3886 if (in(i) == base_mem) return false; // should have been the sentinel value! 3887 } 3888 return true; 3889} 3890 3891bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 3892 Node* n; 3893 n = mm->in(idx); 3894 if (mem == n) return true; // might be empty_memory() 3895 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 3896 if (mem == n) return true; 3897 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 3898 if (mem == n) return true; 3899 if (n == NULL) break; 3900 } 3901 return false; 3902} 3903#endif // !PRODUCT 3904