1 /* 2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "compiler/compileLog.hpp" 28 #include "gc/shared/barrierSet.hpp" 29 #include "gc/shared/c2/barrierSetC2.hpp" 30 #include "memory/allocation.inline.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "oops/objArrayKlass.hpp" 33 #include "opto/addnode.hpp" 34 #include "opto/arraycopynode.hpp" 35 #include "opto/cfgnode.hpp" 36 #include "opto/compile.hpp" 37 #include "opto/connode.hpp" 38 #include "opto/convertnode.hpp" 39 #include "opto/loopnode.hpp" 40 #include "opto/machnode.hpp" 41 #include "opto/matcher.hpp" 42 #include "opto/memnode.hpp" 43 #include "opto/mulnode.hpp" 44 #include "opto/narrowptrnode.hpp" 45 #include "opto/phaseX.hpp" 46 #include "opto/regmask.hpp" 47 #include "opto/rootnode.hpp" 48 #include "opto/valuetypenode.hpp" 49 #include "utilities/align.hpp" 50 #include "utilities/copy.hpp" 51 #include "utilities/macros.hpp" 52 #include "utilities/vmError.hpp" 53 #if INCLUDE_ZGC 54 #include "gc/z/c2/zBarrierSetC2.hpp" 55 #endif 56 57 // Portions of code courtesy of Clifford Click 58 59 // Optimization - Graph Style 60 61 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 62 63 //============================================================================= 64 uint MemNode::size_of() const { return sizeof(*this); } 65 66 const TypePtr *MemNode::adr_type() const { 67 Node* adr = in(Address); 68 if (adr == NULL) return NULL; // node is dead 69 const TypePtr* cross_check = NULL; 70 DEBUG_ONLY(cross_check = _adr_type); 71 return calculate_adr_type(adr->bottom_type(), cross_check); 72 } 73 74 bool MemNode::check_if_adr_maybe_raw(Node* adr) { 75 if (adr != NULL) { 76 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) { 77 return true; 78 } 79 } 80 return false; 81 } 82 83 #ifndef PRODUCT 84 void MemNode::dump_spec(outputStream *st) const { 85 if (in(Address) == NULL) return; // node is dead 86 #ifndef ASSERT 87 // fake the missing field 88 const TypePtr* _adr_type = NULL; 89 if (in(Address) != NULL) 90 _adr_type = in(Address)->bottom_type()->isa_ptr(); 91 #endif 92 dump_adr_type(this, _adr_type, st); 93 94 Compile* C = Compile::current(); 95 if (C->alias_type(_adr_type)->is_volatile()) { 96 st->print(" Volatile!"); 97 } 98 if (_unaligned_access) { 99 st->print(" unaligned"); 100 } 101 if (_mismatched_access) { 102 st->print(" mismatched"); 103 } 104 if (_unsafe_access) { 105 st->print(" unsafe"); 106 } 107 } 108 109 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 110 st->print(" @"); 111 if (adr_type == NULL) { 112 st->print("NULL"); 113 } else { 114 adr_type->dump_on(st); 115 Compile* C = Compile::current(); 116 Compile::AliasType* atp = NULL; 117 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 118 if (atp == NULL) 119 st->print(", idx=?\?;"); 120 else if (atp->index() == Compile::AliasIdxBot) 121 st->print(", idx=Bot;"); 122 else if (atp->index() == Compile::AliasIdxTop) 123 st->print(", idx=Top;"); 124 else if (atp->index() == Compile::AliasIdxRaw) 125 st->print(", idx=Raw;"); 126 else { 127 ciField* field = atp->field(); 128 if (field) { 129 st->print(", name="); 130 field->print_name_on(st); 131 } 132 st->print(", idx=%d;", atp->index()); 133 } 134 } 135 } 136 137 extern void print_alias_types(); 138 139 #endif 140 141 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) { 142 assert((t_oop != NULL), "sanity"); 143 bool is_instance = t_oop->is_known_instance_field(); 144 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() && 145 (load != NULL) && load->is_Load() && 146 (phase->is_IterGVN() != NULL); 147 if (!(is_instance || is_boxed_value_load)) 148 return mchain; // don't try to optimize non-instance types 149 uint instance_id = t_oop->instance_id(); 150 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory); 151 Node *prev = NULL; 152 Node *result = mchain; 153 while (prev != result) { 154 prev = result; 155 if (result == start_mem) 156 break; // hit one of our sentinels 157 // skip over a call which does not affect this memory slice 158 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 159 Node *proj_in = result->in(0); 160 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 161 break; // hit one of our sentinels 162 } else if (proj_in->is_Call()) { 163 // ArrayCopyNodes processed here as well 164 CallNode *call = proj_in->as_Call(); 165 if (!call->may_modify(t_oop, phase)) { // returns false for instances 166 result = call->in(TypeFunc::Memory); 167 } 168 } else if (proj_in->is_Initialize()) { 169 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 170 // Stop if this is the initialization for the object instance which 171 // contains this memory slice, otherwise skip over it. 172 if ((alloc == NULL) || (alloc->_idx == instance_id)) { 173 break; 174 } 175 if (is_instance) { 176 result = proj_in->in(TypeFunc::Memory); 177 } else if (is_boxed_value_load) { 178 Node* klass = alloc->in(AllocateNode::KlassNode); 179 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 180 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) { 181 result = proj_in->in(TypeFunc::Memory); // not related allocation 182 } 183 } 184 } else if (proj_in->is_MemBar()) { 185 ArrayCopyNode* ac = NULL; 186 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) { 187 break; 188 } 189 result = proj_in->in(TypeFunc::Memory); 190 } else { 191 assert(false, "unexpected projection"); 192 } 193 } else if (result->is_ClearArray()) { 194 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) { 195 // Can not bypass initialization of the instance 196 // we are looking for. 197 break; 198 } 199 // Otherwise skip it (the call updated 'result' value). 200 } else if (result->is_MergeMem()) { 201 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty); 202 } 203 } 204 return result; 205 } 206 207 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 208 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 209 if (t_oop == NULL) 210 return mchain; // don't try to optimize non-oop types 211 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 212 bool is_instance = t_oop->is_known_instance_field(); 213 PhaseIterGVN *igvn = phase->is_IterGVN(); 214 if (is_instance && igvn != NULL && result->is_Phi()) { 215 PhiNode *mphi = result->as_Phi(); 216 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 217 const TypePtr *t = mphi->adr_type(); 218 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 219 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 220 t->is_oopptr()->cast_to_exactness(true) 221 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 222 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) { 223 // clone the Phi with our address type 224 result = mphi->split_out_instance(t_adr, igvn); 225 } else { 226 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 227 } 228 } 229 return result; 230 } 231 232 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 233 uint alias_idx = phase->C->get_alias_index(tp); 234 Node *mem = mmem; 235 #ifdef ASSERT 236 { 237 // Check that current type is consistent with the alias index used during graph construction 238 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 239 bool consistent = adr_check == NULL || adr_check->empty() || 240 phase->C->must_alias(adr_check, alias_idx ); 241 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 242 if( !consistent && adr_check != NULL && !adr_check->empty() && 243 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 244 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 245 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 246 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 247 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 248 // don't assert if it is dead code. 249 consistent = true; 250 } 251 if( !consistent ) { 252 st->print("alias_idx==%d, adr_check==", alias_idx); 253 if( adr_check == NULL ) { 254 st->print("NULL"); 255 } else { 256 adr_check->dump(); 257 } 258 st->cr(); 259 print_alias_types(); 260 assert(consistent, "adr_check must match alias idx"); 261 } 262 } 263 #endif 264 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 265 // means an array I have not precisely typed yet. Do not do any 266 // alias stuff with it any time soon. 267 const TypeOopPtr *toop = tp->isa_oopptr(); 268 if( tp->base() != Type::AnyPtr && 269 !(toop && 270 toop->klass() != NULL && 271 toop->klass()->is_java_lang_Object() && 272 toop->offset() == Type::OffsetBot) ) { 273 // compress paths and change unreachable cycles to TOP 274 // If not, we can update the input infinitely along a MergeMem cycle 275 // Equivalent code in PhiNode::Ideal 276 Node* m = phase->transform(mmem); 277 // If transformed to a MergeMem, get the desired slice 278 // Otherwise the returned node represents memory for every slice 279 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 280 // Update input if it is progress over what we have now 281 } 282 return mem; 283 } 284 285 //--------------------------Ideal_common--------------------------------------- 286 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. 287 // Unhook non-raw memories from complete (macro-expanded) initializations. 288 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 289 // If our control input is a dead region, kill all below the region 290 Node *ctl = in(MemNode::Control); 291 if (ctl && remove_dead_region(phase, can_reshape)) 292 return this; 293 ctl = in(MemNode::Control); 294 // Don't bother trying to transform a dead node 295 if (ctl && ctl->is_top()) return NodeSentinel; 296 297 PhaseIterGVN *igvn = phase->is_IterGVN(); 298 // Wait if control on the worklist. 299 if (ctl && can_reshape && igvn != NULL) { 300 Node* bol = NULL; 301 Node* cmp = NULL; 302 if (ctl->in(0)->is_If()) { 303 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 304 bol = ctl->in(0)->in(1); 305 if (bol->is_Bool()) 306 cmp = ctl->in(0)->in(1)->in(1); 307 } 308 if (igvn->_worklist.member(ctl) || 309 (bol != NULL && igvn->_worklist.member(bol)) || 310 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 311 // This control path may be dead. 312 // Delay this memory node transformation until the control is processed. 313 phase->is_IterGVN()->_worklist.push(this); 314 return NodeSentinel; // caller will return NULL 315 } 316 } 317 // Ignore if memory is dead, or self-loop 318 Node *mem = in(MemNode::Memory); 319 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL 320 assert(mem != this, "dead loop in MemNode::Ideal"); 321 322 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 323 // This memory slice may be dead. 324 // Delay this mem node transformation until the memory is processed. 325 phase->is_IterGVN()->_worklist.push(this); 326 return NodeSentinel; // caller will return NULL 327 } 328 329 Node *address = in(MemNode::Address); 330 const Type *t_adr = phase->type(address); 331 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL 332 333 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) { 334 // Unsafe off-heap access with zero address. Remove access and other control users 335 // to not confuse optimizations and add a HaltNode to fail if this is ever executed. 336 assert(ctl != NULL, "unsafe accesses should be control dependent"); 337 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) { 338 Node* u = ctl->fast_out(i); 339 if (u != ctl) { 340 igvn->rehash_node_delayed(u); 341 int nb = u->replace_edge(ctl, phase->C->top()); 342 --i, imax -= nb; 343 } 344 } 345 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr)); 346 Node* halt = igvn->transform(new HaltNode(ctl, frame)); 347 phase->C->root()->add_req(halt); 348 return this; 349 } 350 351 if (can_reshape && igvn != NULL && 352 (igvn->_worklist.member(address) || 353 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) { 354 // The address's base and type may change when the address is processed. 355 // Delay this mem node transformation until the address is processed. 356 phase->is_IterGVN()->_worklist.push(this); 357 return NodeSentinel; // caller will return NULL 358 } 359 360 // Do NOT remove or optimize the next lines: ensure a new alias index 361 // is allocated for an oop pointer type before Escape Analysis. 362 // Note: C++ will not remove it since the call has side effect. 363 if (t_adr->isa_oopptr()) { 364 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 365 } 366 367 Node* base = NULL; 368 if (address->is_AddP()) { 369 base = address->in(AddPNode::Base); 370 } 371 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 372 !t_adr->isa_rawptr()) { 373 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 374 // Skip this node optimization if its address has TOP base. 375 return NodeSentinel; // caller will return NULL 376 } 377 378 // Avoid independent memory operations 379 Node* old_mem = mem; 380 381 // The code which unhooks non-raw memories from complete (macro-expanded) 382 // initializations was removed. After macro-expansion all stores catched 383 // by Initialize node became raw stores and there is no information 384 // which memory slices they modify. So it is unsafe to move any memory 385 // operation above these stores. Also in most cases hooked non-raw memories 386 // were already unhooked by using information from detect_ptr_independence() 387 // and find_previous_store(). 388 389 if (mem->is_MergeMem()) { 390 MergeMemNode* mmem = mem->as_MergeMem(); 391 const TypePtr *tp = t_adr->is_ptr(); 392 393 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 394 } 395 396 if (mem != old_mem) { 397 set_req(MemNode::Memory, mem); 398 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) { 399 igvn->_worklist.push(old_mem); 400 } 401 if (phase->type(mem) == Type::TOP) return NodeSentinel; 402 return this; 403 } 404 405 // let the subclass continue analyzing... 406 return NULL; 407 } 408 409 // Helper function for proving some simple control dominations. 410 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 411 // Already assumes that 'dom' is available at 'sub', and that 'sub' 412 // is not a constant (dominated by the method's StartNode). 413 // Used by MemNode::find_previous_store to prove that the 414 // control input of a memory operation predates (dominates) 415 // an allocation it wants to look past. 416 bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 417 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 418 return false; // Conservative answer for dead code 419 420 // Check 'dom'. Skip Proj and CatchProj nodes. 421 dom = dom->find_exact_control(dom); 422 if (dom == NULL || dom->is_top()) 423 return false; // Conservative answer for dead code 424 425 if (dom == sub) { 426 // For the case when, for example, 'sub' is Initialize and the original 427 // 'dom' is Proj node of the 'sub'. 428 return false; 429 } 430 431 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 432 return true; 433 434 // 'dom' dominates 'sub' if its control edge and control edges 435 // of all its inputs dominate or equal to sub's control edge. 436 437 // Currently 'sub' is either Allocate, Initialize or Start nodes. 438 // Or Region for the check in LoadNode::Ideal(); 439 // 'sub' should have sub->in(0) != NULL. 440 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 441 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 442 443 // Get control edge of 'sub'. 444 Node* orig_sub = sub; 445 sub = sub->find_exact_control(sub->in(0)); 446 if (sub == NULL || sub->is_top()) 447 return false; // Conservative answer for dead code 448 449 assert(sub->is_CFG(), "expecting control"); 450 451 if (sub == dom) 452 return true; 453 454 if (sub->is_Start() || sub->is_Root()) 455 return false; 456 457 { 458 // Check all control edges of 'dom'. 459 460 ResourceMark rm; 461 Arena* arena = Thread::current()->resource_area(); 462 Node_List nlist(arena); 463 Unique_Node_List dom_list(arena); 464 465 dom_list.push(dom); 466 bool only_dominating_controls = false; 467 468 for (uint next = 0; next < dom_list.size(); next++) { 469 Node* n = dom_list.at(next); 470 if (n == orig_sub) 471 return false; // One of dom's inputs dominated by sub. 472 if (!n->is_CFG() && n->pinned()) { 473 // Check only own control edge for pinned non-control nodes. 474 n = n->find_exact_control(n->in(0)); 475 if (n == NULL || n->is_top()) 476 return false; // Conservative answer for dead code 477 assert(n->is_CFG(), "expecting control"); 478 dom_list.push(n); 479 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 480 only_dominating_controls = true; 481 } else if (n->is_CFG()) { 482 if (n->dominates(sub, nlist)) 483 only_dominating_controls = true; 484 else 485 return false; 486 } else { 487 // First, own control edge. 488 Node* m = n->find_exact_control(n->in(0)); 489 if (m != NULL) { 490 if (m->is_top()) 491 return false; // Conservative answer for dead code 492 dom_list.push(m); 493 } 494 // Now, the rest of edges. 495 uint cnt = n->req(); 496 for (uint i = 1; i < cnt; i++) { 497 m = n->find_exact_control(n->in(i)); 498 if (m == NULL || m->is_top()) 499 continue; 500 dom_list.push(m); 501 } 502 } 503 } 504 return only_dominating_controls; 505 } 506 } 507 508 //---------------------detect_ptr_independence--------------------------------- 509 // Used by MemNode::find_previous_store to prove that two base 510 // pointers are never equal. 511 // The pointers are accompanied by their associated allocations, 512 // if any, which have been previously discovered by the caller. 513 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 514 Node* p2, AllocateNode* a2, 515 PhaseTransform* phase) { 516 // Attempt to prove that these two pointers cannot be aliased. 517 // They may both manifestly be allocations, and they should differ. 518 // Or, if they are not both allocations, they can be distinct constants. 519 // Otherwise, one is an allocation and the other a pre-existing value. 520 if (a1 == NULL && a2 == NULL) { // neither an allocation 521 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 522 } else if (a1 != NULL && a2 != NULL) { // both allocations 523 return (a1 != a2); 524 } else if (a1 != NULL) { // one allocation a1 525 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 526 return all_controls_dominate(p2, a1); 527 } else { //(a2 != NULL) // one allocation a2 528 return all_controls_dominate(p1, a2); 529 } 530 return false; 531 } 532 533 534 // Find an arraycopy that must have set (can_see_stored_value=true) or 535 // could have set (can_see_stored_value=false) the value for this load 536 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 537 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 538 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 539 Node* mb = mem->in(0); 540 if (mb->in(0) != NULL && mb->in(0)->is_Proj() && 541 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) { 542 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy(); 543 if (ac->is_clonebasic()) { 544 intptr_t offset; 545 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset); 546 if (alloc != NULL && alloc == ld_alloc) { 547 return ac; 548 } 549 } 550 } 551 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) { 552 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy(); 553 554 if (ac->is_arraycopy_validated() || 555 ac->is_copyof_validated() || 556 ac->is_copyofrange_validated()) { 557 Node* ld_addp = in(MemNode::Address); 558 if (ld_addp->is_AddP()) { 559 Node* ld_base = ld_addp->in(AddPNode::Address); 560 Node* ld_offs = ld_addp->in(AddPNode::Offset); 561 562 Node* dest = ac->in(ArrayCopyNode::Dest); 563 564 if (dest == ld_base) { 565 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 566 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) { 567 return ac; 568 } 569 if (!can_see_stored_value) { 570 mem = ac->in(TypeFunc::Memory); 571 } 572 } 573 } 574 } 575 } 576 return NULL; 577 } 578 579 // The logic for reordering loads and stores uses four steps: 580 // (a) Walk carefully past stores and initializations which we 581 // can prove are independent of this load. 582 // (b) Observe that the next memory state makes an exact match 583 // with self (load or store), and locate the relevant store. 584 // (c) Ensure that, if we were to wire self directly to the store, 585 // the optimizer would fold it up somehow. 586 // (d) Do the rewiring, and return, depending on some other part of 587 // the optimizer to fold up the load. 588 // This routine handles steps (a) and (b). Steps (c) and (d) are 589 // specific to loads and stores, so they are handled by the callers. 590 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 591 // 592 Node* MemNode::find_previous_store(PhaseTransform* phase) { 593 Node* ctrl = in(MemNode::Control); 594 Node* adr = in(MemNode::Address); 595 intptr_t offset = 0; 596 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 597 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 598 599 if (offset == Type::OffsetBot) 600 return NULL; // cannot unalias unless there are precise offsets 601 602 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr); 603 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 604 605 intptr_t size_in_bytes = memory_size(); 606 607 Node* mem = in(MemNode::Memory); // start searching here... 608 609 int cnt = 50; // Cycle limiter 610 for (;;) { // While we can dance past unrelated stores... 611 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 612 613 Node* prev = mem; 614 if (mem->is_Store()) { 615 Node* st_adr = mem->in(MemNode::Address); 616 intptr_t st_offset = 0; 617 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 618 if (st_base == NULL) 619 break; // inscrutable pointer 620 621 // For raw accesses it's not enough to prove that constant offsets don't intersect. 622 // We need the bases to be the equal in order for the offset check to make sense. 623 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) { 624 break; 625 } 626 627 if (st_offset != offset && st_offset != Type::OffsetBot) { 628 const int MAX_STORE = BytesPerLong; 629 if (st_offset >= offset + size_in_bytes || 630 st_offset <= offset - MAX_STORE || 631 st_offset <= offset - mem->as_Store()->memory_size()) { 632 // Success: The offsets are provably independent. 633 // (You may ask, why not just test st_offset != offset and be done? 634 // The answer is that stores of different sizes can co-exist 635 // in the same sequence of RawMem effects. We sometimes initialize 636 // a whole 'tile' of array elements with a single jint or jlong.) 637 mem = mem->in(MemNode::Memory); 638 continue; // (a) advance through independent store memory 639 } 640 } 641 if (st_base != base && 642 detect_ptr_independence(base, alloc, 643 st_base, 644 AllocateNode::Ideal_allocation(st_base, phase), 645 phase)) { 646 // Success: The bases are provably independent. 647 mem = mem->in(MemNode::Memory); 648 continue; // (a) advance through independent store memory 649 } 650 651 // (b) At this point, if the bases or offsets do not agree, we lose, 652 // since we have not managed to prove 'this' and 'mem' independent. 653 if (st_base == base && st_offset == offset) { 654 return mem; // let caller handle steps (c), (d) 655 } 656 657 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 658 InitializeNode* st_init = mem->in(0)->as_Initialize(); 659 AllocateNode* st_alloc = st_init->allocation(); 660 if (st_alloc == NULL) 661 break; // something degenerated 662 bool known_identical = false; 663 bool known_independent = false; 664 if (alloc == st_alloc) 665 known_identical = true; 666 else if (alloc != NULL) 667 known_independent = true; 668 else if (all_controls_dominate(this, st_alloc)) 669 known_independent = true; 670 671 if (known_independent) { 672 // The bases are provably independent: Either they are 673 // manifestly distinct allocations, or else the control 674 // of this load dominates the store's allocation. 675 int alias_idx = phase->C->get_alias_index(adr_type()); 676 if (alias_idx == Compile::AliasIdxRaw) { 677 mem = st_alloc->in(TypeFunc::Memory); 678 } else { 679 mem = st_init->memory(alias_idx); 680 } 681 continue; // (a) advance through independent store memory 682 } 683 684 // (b) at this point, if we are not looking at a store initializing 685 // the same allocation we are loading from, we lose. 686 if (known_identical) { 687 // From caller, can_see_stored_value will consult find_captured_store. 688 return mem; // let caller handle steps (c), (d) 689 } 690 691 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) { 692 if (prev != mem) { 693 // Found an arraycopy but it doesn't affect that load 694 continue; 695 } 696 // Found an arraycopy that may affect that load 697 return mem; 698 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 699 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 700 if (mem->is_Proj() && mem->in(0)->is_Call()) { 701 // ArrayCopyNodes processed here as well. 702 CallNode *call = mem->in(0)->as_Call(); 703 if (!call->may_modify(addr_t, phase)) { 704 mem = call->in(TypeFunc::Memory); 705 continue; // (a) advance through independent call memory 706 } 707 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 708 ArrayCopyNode* ac = NULL; 709 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) { 710 break; 711 } 712 mem = mem->in(0)->in(TypeFunc::Memory); 713 continue; // (a) advance through independent MemBar memory 714 } else if (mem->is_ClearArray()) { 715 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 716 // (the call updated 'mem' value) 717 continue; // (a) advance through independent allocation memory 718 } else { 719 // Can not bypass initialization of the instance 720 // we are looking for. 721 return mem; 722 } 723 } else if (mem->is_MergeMem()) { 724 int alias_idx = phase->C->get_alias_index(adr_type()); 725 mem = mem->as_MergeMem()->memory_at(alias_idx); 726 continue; // (a) advance through independent MergeMem memory 727 } 728 } 729 730 // Unless there is an explicit 'continue', we must bail out here, 731 // because 'mem' is an inscrutable memory state (e.g., a call). 732 break; 733 } 734 735 return NULL; // bail out 736 } 737 738 //----------------------calculate_adr_type------------------------------------- 739 // Helper function. Notices when the given type of address hits top or bottom. 740 // Also, asserts a cross-check of the type against the expected address type. 741 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 742 if (t == Type::TOP) return NULL; // does not touch memory any more? 743 #ifdef PRODUCT 744 cross_check = NULL; 745 #else 746 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL; 747 #endif 748 const TypePtr* tp = t->isa_ptr(); 749 if (tp == NULL) { 750 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 751 return TypePtr::BOTTOM; // touches lots of memory 752 } else { 753 #ifdef ASSERT 754 // %%%% [phh] We don't check the alias index if cross_check is 755 // TypeRawPtr::BOTTOM. Needs to be investigated. 756 if (cross_check != NULL && 757 cross_check != TypePtr::BOTTOM && 758 cross_check != TypeRawPtr::BOTTOM) { 759 // Recheck the alias index, to see if it has changed (due to a bug). 760 Compile* C = Compile::current(); 761 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 762 "must stay in the original alias category"); 763 // The type of the address must be contained in the adr_type, 764 // disregarding "null"-ness. 765 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 766 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 767 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 768 "real address must not escape from expected memory type"); 769 } 770 #endif 771 return tp; 772 } 773 } 774 775 //============================================================================= 776 // Should LoadNode::Ideal() attempt to remove control edges? 777 bool LoadNode::can_remove_control() const { 778 return true; 779 } 780 uint LoadNode::size_of() const { return sizeof(*this); } 781 bool LoadNode::cmp( const Node &n ) const 782 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 783 const Type *LoadNode::bottom_type() const { return _type; } 784 uint LoadNode::ideal_reg() const { 785 return _type->ideal_reg(); 786 } 787 788 #ifndef PRODUCT 789 void LoadNode::dump_spec(outputStream *st) const { 790 MemNode::dump_spec(st); 791 if( !Verbose && !WizardMode ) { 792 // standard dump does this in Verbose and WizardMode 793 st->print(" #"); _type->dump_on(st); 794 } 795 if (!depends_only_on_test()) { 796 st->print(" (does not depend only on test)"); 797 } 798 } 799 #endif 800 801 #ifdef ASSERT 802 //----------------------------is_immutable_value------------------------------- 803 // Helper function to allow a raw load without control edge for some cases 804 bool LoadNode::is_immutable_value(Node* adr) { 805 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 806 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 807 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 808 in_bytes(JavaThread::osthread_offset()))); 809 } 810 #endif 811 812 //----------------------------LoadNode::make----------------------------------- 813 // Polymorphic factory method: 814 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, 815 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) { 816 Compile* C = gvn.C; 817 818 // sanity check the alias category against the created node type 819 assert(!(adr_type->isa_oopptr() && 820 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 821 "use LoadKlassNode instead"); 822 assert(!(adr_type->isa_aryptr() && 823 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 824 "use LoadRangeNode instead"); 825 // Check control edge of raw loads 826 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 827 // oop will be recorded in oop map if load crosses safepoint 828 rt->isa_oopptr() || is_immutable_value(adr), 829 "raw memory operations should have control edge"); 830 LoadNode* load = NULL; 831 switch (bt) { 832 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 833 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 834 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 835 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 836 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 837 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break; 838 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 839 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 840 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break; 841 case T_VALUETYPE: 842 case T_OBJECT: 843 #ifdef _LP64 844 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 845 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency); 846 } else 847 #endif 848 { 849 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 850 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 851 } 852 break; 853 default: 854 ShouldNotReachHere(); 855 break; 856 } 857 assert(load != NULL, "LoadNode should have been created"); 858 if (unaligned) { 859 load->set_unaligned_access(); 860 } 861 if (mismatched) { 862 load->set_mismatched_access(); 863 } 864 if (unsafe) { 865 load->set_unsafe_access(); 866 } 867 if (load->Opcode() == Op_LoadN) { 868 Node* ld = gvn.transform(load); 869 return new DecodeNNode(ld, ld->bottom_type()->make_ptr()); 870 } 871 872 return load; 873 } 874 875 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 876 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) { 877 bool require_atomic = true; 878 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic); 879 if (unaligned) { 880 load->set_unaligned_access(); 881 } 882 if (mismatched) { 883 load->set_mismatched_access(); 884 } 885 if (unsafe) { 886 load->set_unsafe_access(); 887 } 888 return load; 889 } 890 891 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 892 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) { 893 bool require_atomic = true; 894 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic); 895 if (unaligned) { 896 load->set_unaligned_access(); 897 } 898 if (mismatched) { 899 load->set_mismatched_access(); 900 } 901 if (unsafe) { 902 load->set_unsafe_access(); 903 } 904 return load; 905 } 906 907 908 909 //------------------------------hash------------------------------------------- 910 uint LoadNode::hash() const { 911 // unroll addition of interesting fields 912 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 913 } 914 915 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 916 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 917 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 918 bool is_stable_ary = FoldStableValues && 919 (tp != NULL) && (tp->isa_aryptr() != NULL) && 920 tp->isa_aryptr()->is_stable(); 921 922 return (eliminate_boxing && non_volatile) || is_stable_ary; 923 } 924 925 return false; 926 } 927 928 // Is the value loaded previously stored by an arraycopy? If so return 929 // a load node that reads from the source array so we may be able to 930 // optimize out the ArrayCopy node later. 931 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const { 932 Node* ld_adr = in(MemNode::Address); 933 intptr_t ld_off = 0; 934 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 935 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 936 if (ac != NULL) { 937 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 938 939 Node* mem = ac->in(TypeFunc::Memory); 940 Node* ctl = ac->in(0); 941 Node* src = ac->in(ArrayCopyNode::Src); 942 943 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) { 944 return NULL; 945 } 946 947 LoadNode* ld = clone()->as_Load(); 948 Node* addp = in(MemNode::Address)->clone(); 949 if (ac->as_ArrayCopy()->is_clonebasic()) { 950 assert(ld_alloc != NULL, "need an alloc"); 951 assert(addp->is_AddP(), "address must be addp"); 952 assert(ac->in(ArrayCopyNode::Dest)->is_AddP(), "dest must be an address"); 953 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 954 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base)), "strange pattern"); 955 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address)), "strange pattern"); 956 addp->set_req(AddPNode::Base, src->in(AddPNode::Base)); 957 addp->set_req(AddPNode::Address, src->in(AddPNode::Address)); 958 } else { 959 assert(ac->as_ArrayCopy()->is_arraycopy_validated() || 960 ac->as_ArrayCopy()->is_copyof_validated() || 961 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases"); 962 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 963 addp->set_req(AddPNode::Base, src); 964 addp->set_req(AddPNode::Address, src); 965 966 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 967 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 968 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 969 uint shift = exact_log2(type2aelembytes(ary_elem)); 970 971 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 972 #ifdef _LP64 973 diff = phase->transform(new ConvI2LNode(diff)); 974 #endif 975 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 976 977 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 978 addp->set_req(AddPNode::Offset, offset); 979 } 980 addp = phase->transform(addp); 981 #ifdef ASSERT 982 const TypePtr* adr_type = phase->type(addp)->is_ptr(); 983 ld->_adr_type = adr_type; 984 #endif 985 ld->set_req(MemNode::Address, addp); 986 ld->set_req(0, ctl); 987 ld->set_req(MemNode::Memory, mem); 988 // load depends on the tests that validate the arraycopy 989 ld->_control_dependency = UnknownControl; 990 return ld; 991 } 992 return NULL; 993 } 994 995 996 //---------------------------can_see_stored_value------------------------------ 997 // This routine exists to make sure this set of tests is done the same 998 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 999 // will change the graph shape in a way which makes memory alive twice at the 1000 // same time (uses the Oracle model of aliasing), then some 1001 // LoadXNode::Identity will fold things back to the equivalence-class model 1002 // of aliasing. 1003 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 1004 Node* ld_adr = in(MemNode::Address); 1005 intptr_t ld_off = 0; 1006 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off); 1007 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase); 1008 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 1009 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 1010 // This is more general than load from boxing objects. 1011 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 1012 uint alias_idx = atp->index(); 1013 bool final = !atp->is_rewritable(); 1014 Node* result = NULL; 1015 Node* current = st; 1016 // Skip through chains of MemBarNodes checking the MergeMems for 1017 // new states for the slice of this load. Stop once any other 1018 // kind of node is encountered. Loads from final memory can skip 1019 // through any kind of MemBar but normal loads shouldn't skip 1020 // through MemBarAcquire since the could allow them to move out of 1021 // a synchronized region. 1022 while (current->is_Proj()) { 1023 int opc = current->in(0)->Opcode(); 1024 if ((final && (opc == Op_MemBarAcquire || 1025 opc == Op_MemBarAcquireLock || 1026 opc == Op_LoadFence)) || 1027 opc == Op_MemBarRelease || 1028 opc == Op_StoreFence || 1029 opc == Op_MemBarReleaseLock || 1030 opc == Op_MemBarStoreStore || 1031 opc == Op_MemBarCPUOrder) { 1032 Node* mem = current->in(0)->in(TypeFunc::Memory); 1033 if (mem->is_MergeMem()) { 1034 MergeMemNode* merge = mem->as_MergeMem(); 1035 Node* new_st = merge->memory_at(alias_idx); 1036 if (new_st == merge->base_memory()) { 1037 // Keep searching 1038 current = new_st; 1039 continue; 1040 } 1041 // Save the new memory state for the slice and fall through 1042 // to exit. 1043 result = new_st; 1044 } 1045 } 1046 break; 1047 } 1048 if (result != NULL) { 1049 st = result; 1050 } 1051 } 1052 1053 // Loop around twice in the case Load -> Initialize -> Store. 1054 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1055 for (int trip = 0; trip <= 1; trip++) { 1056 1057 if (st->is_Store()) { 1058 Node* st_adr = st->in(MemNode::Address); 1059 if (!phase->eqv(st_adr, ld_adr)) { 1060 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers). 1061 intptr_t st_off = 0; 1062 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off); 1063 if (ld_base == NULL) return NULL; 1064 if (st_base == NULL) return NULL; 1065 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL; 1066 if (ld_off != st_off) return NULL; 1067 if (ld_off == Type::OffsetBot) return NULL; 1068 // Same base, same offset. 1069 // Possible improvement for arrays: check index value instead of absolute offset. 1070 1071 // At this point we have proven something like this setup: 1072 // B = << base >> 1073 // L = LoadQ(AddP(Check/CastPP(B), #Off)) 1074 // S = StoreQ(AddP( B , #Off), V) 1075 // (Actually, we haven't yet proven the Q's are the same.) 1076 // In other words, we are loading from a casted version of 1077 // the same pointer-and-offset that we stored to. 1078 // Casted version may carry a dependency and it is respected. 1079 // Thus, we are able to replace L by V. 1080 } 1081 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1082 if (store_Opcode() != st->Opcode()) 1083 return NULL; 1084 return st->in(MemNode::ValueIn); 1085 } 1086 1087 // A load from a freshly-created object always returns zero. 1088 // (This can happen after LoadNode::Ideal resets the load's memory input 1089 // to find_captured_store, which returned InitializeNode::zero_memory.) 1090 if (st->is_Proj() && st->in(0)->is_Allocate() && 1091 (st->in(0) == ld_alloc) && 1092 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1093 // return a zero value for the load's basic type 1094 // (This is one of the few places where a generic PhaseTransform 1095 // can create new nodes. Think of it as lazily manifesting 1096 // virtually pre-existing constants.) 1097 assert(memory_type() != T_VALUETYPE, "should not be used for value types"); 1098 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue); 1099 if (default_value != NULL) { 1100 return default_value; 1101 } 1102 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null"); 1103 return phase->zerocon(memory_type()); 1104 } 1105 1106 // A load from an initialization barrier can match a captured store. 1107 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1108 InitializeNode* init = st->in(0)->as_Initialize(); 1109 AllocateNode* alloc = init->allocation(); 1110 if ((alloc != NULL) && (alloc == ld_alloc)) { 1111 // examine a captured store value 1112 st = init->find_captured_store(ld_off, memory_size(), phase); 1113 if (st != NULL) { 1114 continue; // take one more trip around 1115 } 1116 } 1117 } 1118 1119 // Load boxed value from result of valueOf() call is input parameter. 1120 if (this->is_Load() && ld_adr->is_AddP() && 1121 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1122 intptr_t ignore = 0; 1123 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1124 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 1125 base = bs->step_over_gc_barrier(base); 1126 if (base != NULL && base->is_Proj() && 1127 base->as_Proj()->_con == TypeFunc::Parms && 1128 base->in(0)->is_CallStaticJava() && 1129 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1130 return base->in(0)->in(TypeFunc::Parms); 1131 } 1132 } 1133 1134 break; 1135 } 1136 1137 return NULL; 1138 } 1139 1140 //----------------------is_instance_field_load_with_local_phi------------------ 1141 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1142 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1143 in(Address)->is_AddP() ) { 1144 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1145 // Only instances and boxed values. 1146 if( t_oop != NULL && 1147 (t_oop->is_ptr_to_boxed_value() || 1148 t_oop->is_known_instance_field()) && 1149 t_oop->offset() != Type::OffsetBot && 1150 t_oop->offset() != Type::OffsetTop) { 1151 return true; 1152 } 1153 } 1154 return false; 1155 } 1156 1157 //------------------------------Identity--------------------------------------- 1158 // Loads are identity if previous store is to same address 1159 Node* LoadNode::Identity(PhaseGVN* phase) { 1160 // Loading from a ValueTypePtr? The ValueTypePtr has the values of 1161 // all fields as input. Look for the field with matching offset. 1162 Node* addr = in(Address); 1163 intptr_t offset; 1164 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset); 1165 if (base != NULL && base->is_ValueTypePtr() && offset > oopDesc::klass_offset_in_bytes()) { 1166 Node* value = base->as_ValueTypePtr()->field_value_by_offset((int)offset, true); 1167 if (value->is_ValueType()) { 1168 // Non-flattened value type field 1169 ValueTypeNode* vt = value->as_ValueType(); 1170 if (vt->is_allocated(phase)) { 1171 value = vt->get_oop(); 1172 } else { 1173 // Not yet allocated, bail out 1174 value = NULL; 1175 } 1176 } 1177 if (value != NULL) { 1178 if (Opcode() == Op_LoadN) { 1179 // Encode oop value if we are loading a narrow oop 1180 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded"); 1181 value = phase->transform(new EncodePNode(value, bottom_type())); 1182 } 1183 return value; 1184 } 1185 } 1186 1187 // If the previous store-maker is the right kind of Store, and the store is 1188 // to the same address, then we are equal to the value stored. 1189 Node* mem = in(Memory); 1190 Node* value = can_see_stored_value(mem, phase); 1191 if( value ) { 1192 // byte, short & char stores truncate naturally. 1193 // A load has to load the truncated value which requires 1194 // some sort of masking operation and that requires an 1195 // Ideal call instead of an Identity call. 1196 if (memory_size() < BytesPerInt) { 1197 // If the input to the store does not fit with the load's result type, 1198 // it must be truncated via an Ideal call. 1199 if (!phase->type(value)->higher_equal(phase->type(this))) 1200 return this; 1201 } 1202 // (This works even when value is a Con, but LoadNode::Value 1203 // usually runs first, producing the singleton type of the Con.) 1204 return value; 1205 } 1206 1207 // Search for an existing data phi which was generated before for the same 1208 // instance's field to avoid infinite generation of phis in a loop. 1209 Node *region = mem->in(0); 1210 if (is_instance_field_load_with_local_phi(region)) { 1211 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1212 int this_index = phase->C->get_alias_index(addr_t); 1213 int this_offset = addr_t->offset(); 1214 int this_iid = addr_t->instance_id(); 1215 if (!addr_t->is_known_instance() && 1216 addr_t->is_ptr_to_boxed_value()) { 1217 // Use _idx of address base (could be Phi node) for boxed values. 1218 intptr_t ignore = 0; 1219 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1220 if (base == NULL) { 1221 return this; 1222 } 1223 this_iid = base->_idx; 1224 } 1225 const Type* this_type = bottom_type(); 1226 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1227 Node* phi = region->fast_out(i); 1228 if (phi->is_Phi() && phi != mem && 1229 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) { 1230 return phi; 1231 } 1232 } 1233 } 1234 1235 return this; 1236 } 1237 1238 // Construct an equivalent unsigned load. 1239 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) { 1240 BasicType bt = T_ILLEGAL; 1241 const Type* rt = NULL; 1242 switch (Opcode()) { 1243 case Op_LoadUB: return this; 1244 case Op_LoadUS: return this; 1245 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break; 1246 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break; 1247 default: 1248 assert(false, "no unsigned variant: %s", Name()); 1249 return NULL; 1250 } 1251 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1252 raw_adr_type(), rt, bt, _mo, _control_dependency, 1253 is_unaligned_access(), is_mismatched_access()); 1254 } 1255 1256 // Construct an equivalent signed load. 1257 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) { 1258 BasicType bt = T_ILLEGAL; 1259 const Type* rt = NULL; 1260 switch (Opcode()) { 1261 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break; 1262 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break; 1263 case Op_LoadB: // fall through 1264 case Op_LoadS: // fall through 1265 case Op_LoadI: // fall through 1266 case Op_LoadL: return this; 1267 default: 1268 assert(false, "no signed variant: %s", Name()); 1269 return NULL; 1270 } 1271 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1272 raw_adr_type(), rt, bt, _mo, _control_dependency, 1273 is_unaligned_access(), is_mismatched_access()); 1274 } 1275 1276 // We're loading from an object which has autobox behaviour. 1277 // If this object is result of a valueOf call we'll have a phi 1278 // merging a newly allocated object and a load from the cache. 1279 // We want to replace this load with the original incoming 1280 // argument to the valueOf call. 1281 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1282 assert(phase->C->eliminate_boxing(), "sanity"); 1283 intptr_t ignore = 0; 1284 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1285 if ((base == NULL) || base->is_Phi()) { 1286 // Push the loads from the phi that comes from valueOf up 1287 // through it to allow elimination of the loads and the recovery 1288 // of the original value. It is done in split_through_phi(). 1289 return NULL; 1290 } else if (base->is_Load() || 1291 (base->is_DecodeN() && base->in(1)->is_Load())) { 1292 // Eliminate the load of boxed value for integer types from the cache 1293 // array by deriving the value from the index into the array. 1294 // Capture the offset of the load and then reverse the computation. 1295 1296 // Get LoadN node which loads a boxing object from 'cache' array. 1297 if (base->is_DecodeN()) { 1298 base = base->in(1); 1299 } 1300 if (!base->in(Address)->is_AddP()) { 1301 return NULL; // Complex address 1302 } 1303 AddPNode* address = base->in(Address)->as_AddP(); 1304 Node* cache_base = address->in(AddPNode::Base); 1305 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1306 // Get ConP node which is static 'cache' field. 1307 cache_base = cache_base->in(1); 1308 } 1309 if ((cache_base != NULL) && cache_base->is_Con()) { 1310 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1311 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1312 Node* elements[4]; 1313 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1314 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1315 if (count > 0 && elements[0]->is_Con() && 1316 (count == 1 || 1317 (count == 2 && elements[1]->Opcode() == Op_LShiftX && 1318 elements[1]->in(2) == phase->intcon(shift)))) { 1319 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1320 // Fetch the box object cache[0] at the base of the array and get its value 1321 ciInstance* box = array->obj_at(0)->as_instance(); 1322 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1323 assert(ik->is_box_klass(), "sanity"); 1324 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1325 if (ik->nof_nonstatic_fields() == 1) { 1326 // This should be true nonstatic_field_at requires calling 1327 // nof_nonstatic_fields so check it anyway 1328 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1329 BasicType bt = c.basic_type(); 1330 // Only integer types have boxing cache. 1331 assert(bt == T_BOOLEAN || bt == T_CHAR || 1332 bt == T_BYTE || bt == T_SHORT || 1333 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt)); 1334 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1335 if (cache_low != (int)cache_low) { 1336 return NULL; // should not happen since cache is array indexed by value 1337 } 1338 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1339 if (offset != (int)offset) { 1340 return NULL; // should not happen since cache is array indexed by value 1341 } 1342 // Add up all the offsets making of the address of the load 1343 Node* result = elements[0]; 1344 for (int i = 1; i < count; i++) { 1345 result = phase->transform(new AddXNode(result, elements[i])); 1346 } 1347 // Remove the constant offset from the address and then 1348 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset))); 1349 // remove the scaling of the offset to recover the original index. 1350 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1351 // Peel the shift off directly but wrap it in a dummy node 1352 // since Ideal can't return existing nodes 1353 result = new RShiftXNode(result->in(1), phase->intcon(0)); 1354 } else if (result->is_Add() && result->in(2)->is_Con() && 1355 result->in(1)->Opcode() == Op_LShiftX && 1356 result->in(1)->in(2) == phase->intcon(shift)) { 1357 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1358 // but for boxing cache access we know that X<<Z will not overflow 1359 // (there is range check) so we do this optimizatrion by hand here. 1360 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift)); 1361 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con)); 1362 } else { 1363 result = new RShiftXNode(result, phase->intcon(shift)); 1364 } 1365 #ifdef _LP64 1366 if (bt != T_LONG) { 1367 result = new ConvL2INode(phase->transform(result)); 1368 } 1369 #else 1370 if (bt == T_LONG) { 1371 result = new ConvI2LNode(phase->transform(result)); 1372 } 1373 #endif 1374 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1375 // Need to preserve unboxing load type if it is unsigned. 1376 switch(this->Opcode()) { 1377 case Op_LoadUB: 1378 result = new AndINode(phase->transform(result), phase->intcon(0xFF)); 1379 break; 1380 case Op_LoadUS: 1381 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF)); 1382 break; 1383 } 1384 return result; 1385 } 1386 } 1387 } 1388 } 1389 } 1390 return NULL; 1391 } 1392 1393 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1394 Node* region = phi->in(0); 1395 if (region == NULL) { 1396 return false; // Wait stable graph 1397 } 1398 uint cnt = phi->req(); 1399 for (uint i = 1; i < cnt; i++) { 1400 Node* rc = region->in(i); 1401 if (rc == NULL || phase->type(rc) == Type::TOP) 1402 return false; // Wait stable graph 1403 Node* in = phi->in(i); 1404 if (in == NULL || phase->type(in) == Type::TOP) 1405 return false; // Wait stable graph 1406 } 1407 return true; 1408 } 1409 //------------------------------split_through_phi------------------------------ 1410 // Split instance or boxed field load through Phi. 1411 Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1412 Node* mem = in(Memory); 1413 Node* address = in(Address); 1414 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1415 1416 assert((t_oop != NULL) && 1417 (t_oop->is_known_instance_field() || 1418 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1419 1420 Compile* C = phase->C; 1421 intptr_t ignore = 0; 1422 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1423 bool base_is_phi = (base != NULL) && base->is_Phi(); 1424 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1425 (base != NULL) && (base == address->in(AddPNode::Base)) && 1426 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1427 1428 if (!((mem->is_Phi() || base_is_phi) && 1429 (load_boxed_values || t_oop->is_known_instance_field()))) { 1430 return NULL; // memory is not Phi 1431 } 1432 1433 if (mem->is_Phi()) { 1434 if (!stable_phi(mem->as_Phi(), phase)) { 1435 return NULL; // Wait stable graph 1436 } 1437 uint cnt = mem->req(); 1438 // Check for loop invariant memory. 1439 if (cnt == 3) { 1440 for (uint i = 1; i < cnt; i++) { 1441 Node* in = mem->in(i); 1442 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1443 if (m == mem) { 1444 if (i == 1) { 1445 // if the first edge was a loop, check second edge too. 1446 // If both are replaceable - we are in an infinite loop 1447 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase); 1448 if (n == mem) { 1449 break; 1450 } 1451 } 1452 set_req(Memory, mem->in(cnt - i)); 1453 return this; // made change 1454 } 1455 } 1456 } 1457 } 1458 if (base_is_phi) { 1459 if (!stable_phi(base->as_Phi(), phase)) { 1460 return NULL; // Wait stable graph 1461 } 1462 uint cnt = base->req(); 1463 // Check for loop invariant memory. 1464 if (cnt == 3) { 1465 for (uint i = 1; i < cnt; i++) { 1466 if (base->in(i) == base) { 1467 return NULL; // Wait stable graph 1468 } 1469 } 1470 } 1471 } 1472 1473 // Split through Phi (see original code in loopopts.cpp). 1474 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1475 1476 // Do nothing here if Identity will find a value 1477 // (to avoid infinite chain of value phis generation). 1478 if (!phase->eqv(this, phase->apply_identity(this))) 1479 return NULL; 1480 1481 // Select Region to split through. 1482 Node* region; 1483 if (!base_is_phi) { 1484 assert(mem->is_Phi(), "sanity"); 1485 region = mem->in(0); 1486 // Skip if the region dominates some control edge of the address. 1487 if (!MemNode::all_controls_dominate(address, region)) 1488 return NULL; 1489 } else if (!mem->is_Phi()) { 1490 assert(base_is_phi, "sanity"); 1491 region = base->in(0); 1492 // Skip if the region dominates some control edge of the memory. 1493 if (!MemNode::all_controls_dominate(mem, region)) 1494 return NULL; 1495 } else if (base->in(0) != mem->in(0)) { 1496 assert(base_is_phi && mem->is_Phi(), "sanity"); 1497 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1498 region = base->in(0); 1499 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1500 region = mem->in(0); 1501 } else { 1502 return NULL; // complex graph 1503 } 1504 } else { 1505 assert(base->in(0) == mem->in(0), "sanity"); 1506 region = mem->in(0); 1507 } 1508 1509 const Type* this_type = this->bottom_type(); 1510 int this_index = C->get_alias_index(t_oop); 1511 int this_offset = t_oop->offset(); 1512 int this_iid = t_oop->instance_id(); 1513 if (!t_oop->is_known_instance() && load_boxed_values) { 1514 // Use _idx of address base for boxed values. 1515 this_iid = base->_idx; 1516 } 1517 PhaseIterGVN* igvn = phase->is_IterGVN(); 1518 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset); 1519 for (uint i = 1; i < region->req(); i++) { 1520 Node* x; 1521 Node* the_clone = NULL; 1522 if (region->in(i) == C->top()) { 1523 x = C->top(); // Dead path? Use a dead data op 1524 } else { 1525 x = this->clone(); // Else clone up the data op 1526 the_clone = x; // Remember for possible deletion. 1527 // Alter data node to use pre-phi inputs 1528 if (this->in(0) == region) { 1529 x->set_req(0, region->in(i)); 1530 } else { 1531 x->set_req(0, NULL); 1532 } 1533 if (mem->is_Phi() && (mem->in(0) == region)) { 1534 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1535 } 1536 if (address->is_Phi() && address->in(0) == region) { 1537 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1538 } 1539 if (base_is_phi && (base->in(0) == region)) { 1540 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1541 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1542 x->set_req(Address, adr_x); 1543 } 1544 } 1545 // Check for a 'win' on some paths 1546 const Type *t = x->Value(igvn); 1547 1548 bool singleton = t->singleton(); 1549 1550 // See comments in PhaseIdealLoop::split_thru_phi(). 1551 if (singleton && t == Type::TOP) { 1552 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1553 } 1554 1555 if (singleton) { 1556 x = igvn->makecon(t); 1557 } else { 1558 // We now call Identity to try to simplify the cloned node. 1559 // Note that some Identity methods call phase->type(this). 1560 // Make sure that the type array is big enough for 1561 // our new node, even though we may throw the node away. 1562 // (This tweaking with igvn only works because x is a new node.) 1563 igvn->set_type(x, t); 1564 // If x is a TypeNode, capture any more-precise type permanently into Node 1565 // otherwise it will be not updated during igvn->transform since 1566 // igvn->type(x) is set to x->Value() already. 1567 x->raise_bottom_type(t); 1568 Node *y = igvn->apply_identity(x); 1569 if (y != x) { 1570 x = y; 1571 } else { 1572 y = igvn->hash_find_insert(x); 1573 if (y) { 1574 x = y; 1575 } else { 1576 // Else x is a new node we are keeping 1577 // We do not need register_new_node_with_optimizer 1578 // because set_type has already been called. 1579 igvn->_worklist.push(x); 1580 } 1581 } 1582 } 1583 if (x != the_clone && the_clone != NULL) { 1584 igvn->remove_dead_node(the_clone); 1585 } 1586 phi->set_req(i, x); 1587 } 1588 // Record Phi 1589 igvn->register_new_node_with_optimizer(phi); 1590 return phi; 1591 } 1592 1593 //------------------------------Ideal------------------------------------------ 1594 // If the load is from Field memory and the pointer is non-null, it might be possible to 1595 // zero out the control input. 1596 // If the offset is constant and the base is an object allocation, 1597 // try to hook me up to the exact initializing store. 1598 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1599 Node* p = MemNode::Ideal_common(phase, can_reshape); 1600 if (p) return (p == NodeSentinel) ? NULL : p; 1601 1602 Node* ctrl = in(MemNode::Control); 1603 Node* address = in(MemNode::Address); 1604 bool progress = false; 1605 1606 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) && 1607 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes()); 1608 1609 // Skip up past a SafePoint control. Cannot do this for Stores because 1610 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1611 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1612 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw && 1613 !addr_mark && 1614 (depends_only_on_test() || has_unknown_control_dependency())) { 1615 ctrl = ctrl->in(0); 1616 set_req(MemNode::Control,ctrl); 1617 progress = true; 1618 } 1619 1620 intptr_t ignore = 0; 1621 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1622 if (base != NULL 1623 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1624 // Check for useless control edge in some common special cases 1625 if (in(MemNode::Control) != NULL 1626 && can_remove_control() 1627 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1628 && all_controls_dominate(base, phase->C->start())) { 1629 // A method-invariant, non-null address (constant or 'this' argument). 1630 set_req(MemNode::Control, NULL); 1631 progress = true; 1632 } 1633 } 1634 1635 Node* mem = in(MemNode::Memory); 1636 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1637 1638 if (can_reshape && (addr_t != NULL)) { 1639 // try to optimize our memory input 1640 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1641 if (opt_mem != mem) { 1642 set_req(MemNode::Memory, opt_mem); 1643 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1644 return this; 1645 } 1646 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1647 if ((t_oop != NULL) && 1648 (t_oop->is_known_instance_field() || 1649 t_oop->is_ptr_to_boxed_value())) { 1650 PhaseIterGVN *igvn = phase->is_IterGVN(); 1651 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1652 // Delay this transformation until memory Phi is processed. 1653 phase->is_IterGVN()->_worklist.push(this); 1654 return NULL; 1655 } 1656 // Split instance field load through Phi. 1657 Node* result = split_through_phi(phase); 1658 if (result != NULL) return result; 1659 1660 if (t_oop->is_ptr_to_boxed_value()) { 1661 Node* result = eliminate_autobox(phase); 1662 if (result != NULL) return result; 1663 } 1664 } 1665 } 1666 1667 // Is there a dominating load that loads the same value? Leave 1668 // anything that is not a load of a field/array element (like 1669 // barriers etc.) alone 1670 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) { 1671 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 1672 Node *use = mem->fast_out(i); 1673 if (use != this && 1674 use->Opcode() == Opcode() && 1675 use->in(0) != NULL && 1676 use->in(0) != in(0) && 1677 use->in(Address) == in(Address)) { 1678 Node* ctl = in(0); 1679 for (int i = 0; i < 10 && ctl != NULL; i++) { 1680 ctl = IfNode::up_one_dom(ctl); 1681 if (ctl == use->in(0)) { 1682 set_req(0, use->in(0)); 1683 return this; 1684 } 1685 } 1686 } 1687 } 1688 } 1689 1690 // Check for prior store with a different base or offset; make Load 1691 // independent. Skip through any number of them. Bail out if the stores 1692 // are in an endless dead cycle and report no progress. This is a key 1693 // transform for Reflection. However, if after skipping through the Stores 1694 // we can't then fold up against a prior store do NOT do the transform as 1695 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1696 // array memory alive twice: once for the hoisted Load and again after the 1697 // bypassed Store. This situation only works if EVERYBODY who does 1698 // anti-dependence work knows how to bypass. I.e. we need all 1699 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1700 // the alias index stuff. So instead, peek through Stores and IFF we can 1701 // fold up, do so. 1702 Node* prev_mem = find_previous_store(phase); 1703 if (prev_mem != NULL) { 1704 Node* value = can_see_arraycopy_value(prev_mem, phase); 1705 if (value != NULL) { 1706 return value; 1707 } 1708 } 1709 // Steps (a), (b): Walk past independent stores to find an exact match. 1710 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1711 // (c) See if we can fold up on the spot, but don't fold up here. 1712 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1713 // just return a prior value, which is done by Identity calls. 1714 if (can_see_stored_value(prev_mem, phase)) { 1715 // Make ready for step (d): 1716 set_req(MemNode::Memory, prev_mem); 1717 return this; 1718 } 1719 } 1720 1721 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase); 1722 if (alloc != NULL && mem->is_Proj() && 1723 mem->in(0) != NULL && 1724 mem->in(0) == alloc->initialization() && 1725 Opcode() == Op_LoadX && 1726 alloc->initialization()->proj_out_or_null(0) != NULL) { 1727 InitializeNode* init = alloc->initialization(); 1728 Node* control = init->proj_out(0); 1729 return alloc->make_ideal_mark(phase, address, control, mem, NULL); 1730 } 1731 1732 return progress ? this : NULL; 1733 } 1734 1735 // Helper to recognize certain Klass fields which are invariant across 1736 // some group of array types (e.g., int[] or all T[] where T < Object). 1737 const Type* 1738 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1739 ciKlass* klass) const { 1740 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1741 // The field is Klass::_modifier_flags. Return its (constant) value. 1742 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1743 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1744 return TypeInt::make(klass->modifier_flags()); 1745 } 1746 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1747 // The field is Klass::_access_flags. Return its (constant) value. 1748 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1749 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1750 return TypeInt::make(klass->access_flags()); 1751 } 1752 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1753 // The field is Klass::_layout_helper. Return its constant value if known. 1754 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1755 return TypeInt::make(klass->layout_helper()); 1756 } 1757 1758 // No match. 1759 return NULL; 1760 } 1761 1762 //------------------------------Value----------------------------------------- 1763 const Type* LoadNode::Value(PhaseGVN* phase) const { 1764 // Either input is TOP ==> the result is TOP 1765 Node* mem = in(MemNode::Memory); 1766 const Type *t1 = phase->type(mem); 1767 if (t1 == Type::TOP) return Type::TOP; 1768 Node* adr = in(MemNode::Address); 1769 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1770 if (tp == NULL || tp->empty()) return Type::TOP; 1771 int off = tp->offset(); 1772 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1773 Compile* C = phase->C; 1774 1775 // Try to guess loaded type from pointer type 1776 if (tp->isa_aryptr()) { 1777 const TypeAryPtr* ary = tp->is_aryptr(); 1778 const Type* t = ary->elem(); 1779 1780 // Determine whether the reference is beyond the header or not, by comparing 1781 // the offset against the offset of the start of the array's data. 1782 // Different array types begin at slightly different offsets (12 vs. 16). 1783 // We choose T_BYTE as an example base type that is least restrictive 1784 // as to alignment, which will therefore produce the smallest 1785 // possible base offset. 1786 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1787 const bool off_beyond_header = (off >= min_base_off); 1788 1789 // Try to constant-fold a stable array element. 1790 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) { 1791 // Make sure the reference is not into the header and the offset is constant 1792 ciObject* aobj = ary->const_oop(); 1793 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1794 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0); 1795 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, 1796 stable_dimension, 1797 memory_type(), is_unsigned()); 1798 if (con_type != NULL) { 1799 return con_type; 1800 } 1801 } 1802 } 1803 1804 // Don't do this for integer types. There is only potential profit if 1805 // the element type t is lower than _type; that is, for int types, if _type is 1806 // more restrictive than t. This only happens here if one is short and the other 1807 // char (both 16 bits), and in those cases we've made an intentional decision 1808 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1809 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1810 // 1811 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1812 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1813 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1814 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1815 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1816 // In fact, that could have been the original type of p1, and p1 could have 1817 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1818 // expression (LShiftL quux 3) independently optimized to the constant 8. 1819 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1820 && (_type->isa_vect() == NULL) 1821 && t->isa_valuetype() == NULL 1822 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1823 // t might actually be lower than _type, if _type is a unique 1824 // concrete subclass of abstract class t. 1825 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header? 1826 const Type* jt = t->join_speculative(_type); 1827 // In any case, do not allow the join, per se, to empty out the type. 1828 if (jt->empty() && !t->empty()) { 1829 // This can happen if a interface-typed array narrows to a class type. 1830 jt = _type; 1831 } 1832 #ifdef ASSERT 1833 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1834 // The pointers in the autobox arrays are always non-null 1835 Node* base = adr->in(AddPNode::Base); 1836 if ((base != NULL) && base->is_DecodeN()) { 1837 // Get LoadN node which loads IntegerCache.cache field 1838 base = base->in(1); 1839 } 1840 if ((base != NULL) && base->is_Con()) { 1841 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1842 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1843 // It could be narrow oop 1844 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1845 } 1846 } 1847 } 1848 #endif 1849 return jt; 1850 } 1851 } 1852 } else if (tp->base() == Type::InstPtr) { 1853 assert( off != Type::OffsetBot || 1854 // arrays can be cast to Objects 1855 tp->is_oopptr()->klass()->is_java_lang_Object() || 1856 tp->is_oopptr()->klass() == ciEnv::current()->Class_klass() || 1857 // unsafe field access may not have a constant offset 1858 C->has_unsafe_access(), 1859 "Field accesses must be precise" ); 1860 // For oop loads, we expect the _type to be precise. 1861 1862 const TypeInstPtr* tinst = tp->is_instptr(); 1863 BasicType bt = memory_type(); 1864 1865 // Fold component and value mirror loads 1866 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 1867 if (ik == phase->C->env()->Class_klass() && (off == java_lang_Class::component_mirror_offset_in_bytes() || 1868 off == java_lang_Class::inline_mirror_offset_in_bytes())) { 1869 ciType* mirror_type = tinst->java_mirror_type(); 1870 if (mirror_type != NULL) { 1871 const Type* const_oop = TypePtr::NULL_PTR; 1872 if (mirror_type->is_array_klass()) { 1873 const_oop = TypeInstPtr::make(mirror_type->as_array_klass()->component_mirror_instance()); 1874 } else if (mirror_type->is_valuetype()) { 1875 const_oop = TypeInstPtr::make(mirror_type->as_value_klass()->inline_mirror_instance()); 1876 } 1877 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop; 1878 } 1879 } 1880 1881 // Optimize loads from constant fields. 1882 ciObject* const_oop = tinst->const_oop(); 1883 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) { 1884 ciType* mirror_type = const_oop->as_instance()->java_mirror_type(); 1885 if (mirror_type != NULL && mirror_type->is_valuetype()) { 1886 ciValueKlass* vk = mirror_type->as_value_klass(); 1887 if (off == vk->default_value_offset()) { 1888 // Loading a special hidden field that contains the oop of the default value type 1889 const Type* const_oop = TypeInstPtr::make(vk->default_value_instance()); 1890 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop; 1891 } 1892 } 1893 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt); 1894 if (con_type != NULL) { 1895 return con_type; 1896 } 1897 } 1898 } else if (tp->base() == Type::KlassPtr) { 1899 assert( off != Type::OffsetBot || 1900 // arrays can be cast to Objects 1901 tp->is_klassptr()->klass() == NULL || 1902 tp->is_klassptr()->klass()->is_java_lang_Object() || 1903 // also allow array-loading from the primary supertype 1904 // array during subtype checks 1905 Opcode() == Op_LoadKlass, 1906 "Field accesses must be precise" ); 1907 // For klass/static loads, we expect the _type to be precise 1908 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) { 1909 if (adr->is_Load() && off == 0) { 1910 /* With mirrors being an indirect in the Klass* 1911 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset)) 1912 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass). 1913 * 1914 * So check the type and klass of the node before the LoadP. 1915 */ 1916 Node* adr2 = adr->in(MemNode::Address); 1917 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 1918 if (tkls != NULL) { 1919 ciKlass* klass = tkls->klass(); 1920 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1921 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1922 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1923 return TypeInstPtr::make(klass->java_mirror()); 1924 } 1925 } 1926 } else { 1927 // Check for a load of the default value offset from the ValueKlassFixedBlock: 1928 // LoadI(LoadP(value_klass, adr_valueklass_fixed_block_offset), default_value_offset_offset) 1929 intptr_t offset = 0; 1930 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 1931 if (base != NULL && base->is_Load() && offset == in_bytes(ValueKlass::default_value_offset_offset())) { 1932 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr(); 1933 if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->isa_valuetype() && 1934 tkls->offset() == in_bytes(InstanceKlass::adr_valueklass_fixed_block_offset())) { 1935 assert(base->Opcode() == Op_LoadP, "must load an oop from klass"); 1936 assert(Opcode() == Op_LoadI, "must load an int from fixed block"); 1937 return TypeInt::make(tkls->klass()->as_value_klass()->default_value_offset()); 1938 } 1939 } 1940 } 1941 } 1942 1943 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1944 if (tkls != NULL && !StressReflectiveCode) { 1945 ciKlass* klass = tkls->klass(); 1946 if (tkls->is_loaded() && tkls->klass_is_exact()) { 1947 // We are loading a field from a Klass metaobject whose identity 1948 // is known at compile time (the type is "exact" or "precise"). 1949 // Check for fields we know are maintained as constants by the VM. 1950 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1951 // The field is Klass::_super_check_offset. Return its (constant) value. 1952 // (Folds up type checking code.) 1953 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1954 return TypeInt::make(klass->super_check_offset()); 1955 } 1956 // Compute index into primary_supers array 1957 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1958 // Check for overflowing; use unsigned compare to handle the negative case. 1959 if( depth < ciKlass::primary_super_limit() ) { 1960 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1961 // (Folds up type checking code.) 1962 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1963 ciKlass *ss = klass->super_of_depth(depth); 1964 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1965 } 1966 const Type* aift = load_array_final_field(tkls, klass); 1967 if (aift != NULL) return aift; 1968 } 1969 1970 // We can still check if we are loading from the primary_supers array at a 1971 // shallow enough depth. Even though the klass is not exact, entries less 1972 // than or equal to its super depth are correct. 1973 if (tkls->is_loaded()) { 1974 ciType *inner = klass; 1975 while( inner->is_obj_array_klass() ) 1976 inner = inner->as_obj_array_klass()->base_element_type(); 1977 if( inner->is_instance_klass() && 1978 !inner->as_instance_klass()->flags().is_interface() ) { 1979 // Compute index into primary_supers array 1980 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1981 // Check for overflowing; use unsigned compare to handle the negative case. 1982 if( depth < ciKlass::primary_super_limit() && 1983 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1984 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1985 // (Folds up type checking code.) 1986 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1987 ciKlass *ss = klass->super_of_depth(depth); 1988 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1989 } 1990 } 1991 } 1992 1993 // If the type is enough to determine that the thing is not an array, 1994 // we can give the layout_helper a positive interval type. 1995 // This will help short-circuit some reflective code. 1996 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1997 && !klass->is_array_klass() // not directly typed as an array 1998 && !klass->is_interface() // specifically not Serializable & Cloneable 1999 && !klass->is_java_lang_Object() // not the supertype of all T[] 2000 ) { 2001 // Note: When interfaces are reliable, we can narrow the interface 2002 // test to (klass != Serializable && klass != Cloneable). 2003 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 2004 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 2005 // The key property of this type is that it folds up tests 2006 // for array-ness, since it proves that the layout_helper is positive. 2007 // Thus, a generic value like the basic object layout helper works fine. 2008 return TypeInt::make(min_size, max_jint, Type::WidenMin); 2009 } 2010 } 2011 2012 // If we are loading from a freshly-allocated object, produce a zero, 2013 // if the load is provably beyond the header of the object. 2014 // (Also allow a variable load from a fresh array to produce zero.) 2015 const TypeOopPtr *tinst = tp->isa_oopptr(); 2016 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 2017 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 2018 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 2019 Node* value = can_see_stored_value(mem,phase); 2020 if (value != NULL && value->is_Con()) { 2021 assert(value->bottom_type()->higher_equal(_type),"sanity"); 2022 return value->bottom_type(); 2023 } 2024 } 2025 2026 if (is_instance) { 2027 // If we have an instance type and our memory input is the 2028 // programs's initial memory state, there is no matching store, 2029 // so just return a zero of the appropriate type 2030 Node *mem = in(MemNode::Memory); 2031 if (mem->is_Parm() && mem->in(0)->is_Start()) { 2032 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 2033 return Type::get_zero_type(_type->basic_type()); 2034 } 2035 } 2036 return _type; 2037 } 2038 2039 //------------------------------match_edge------------------------------------- 2040 // Do we Match on this edge index or not? Match only the address. 2041 uint LoadNode::match_edge(uint idx) const { 2042 return idx == MemNode::Address; 2043 } 2044 2045 //--------------------------LoadBNode::Ideal-------------------------------------- 2046 // 2047 // If the previous store is to the same address as this load, 2048 // and the value stored was larger than a byte, replace this load 2049 // with the value stored truncated to a byte. If no truncation is 2050 // needed, the replacement is done in LoadNode::Identity(). 2051 // 2052 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2053 Node* mem = in(MemNode::Memory); 2054 Node* value = can_see_stored_value(mem,phase); 2055 if( value && !phase->type(value)->higher_equal( _type ) ) { 2056 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) ); 2057 return new RShiftINode(result, phase->intcon(24)); 2058 } 2059 // Identity call will handle the case where truncation is not needed. 2060 return LoadNode::Ideal(phase, can_reshape); 2061 } 2062 2063 const Type* LoadBNode::Value(PhaseGVN* phase) const { 2064 Node* mem = in(MemNode::Memory); 2065 Node* value = can_see_stored_value(mem,phase); 2066 if (value != NULL && value->is_Con() && 2067 !value->bottom_type()->higher_equal(_type)) { 2068 // If the input to the store does not fit with the load's result type, 2069 // it must be truncated. We can't delay until Ideal call since 2070 // a singleton Value is needed for split_thru_phi optimization. 2071 int con = value->get_int(); 2072 return TypeInt::make((con << 24) >> 24); 2073 } 2074 return LoadNode::Value(phase); 2075 } 2076 2077 //--------------------------LoadUBNode::Ideal------------------------------------- 2078 // 2079 // If the previous store is to the same address as this load, 2080 // and the value stored was larger than a byte, replace this load 2081 // with the value stored truncated to a byte. If no truncation is 2082 // needed, the replacement is done in LoadNode::Identity(). 2083 // 2084 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2085 Node* mem = in(MemNode::Memory); 2086 Node* value = can_see_stored_value(mem, phase); 2087 if (value && !phase->type(value)->higher_equal(_type)) 2088 return new AndINode(value, phase->intcon(0xFF)); 2089 // Identity call will handle the case where truncation is not needed. 2090 return LoadNode::Ideal(phase, can_reshape); 2091 } 2092 2093 const Type* LoadUBNode::Value(PhaseGVN* phase) const { 2094 Node* mem = in(MemNode::Memory); 2095 Node* value = can_see_stored_value(mem,phase); 2096 if (value != NULL && value->is_Con() && 2097 !value->bottom_type()->higher_equal(_type)) { 2098 // If the input to the store does not fit with the load's result type, 2099 // it must be truncated. We can't delay until Ideal call since 2100 // a singleton Value is needed for split_thru_phi optimization. 2101 int con = value->get_int(); 2102 return TypeInt::make(con & 0xFF); 2103 } 2104 return LoadNode::Value(phase); 2105 } 2106 2107 //--------------------------LoadUSNode::Ideal------------------------------------- 2108 // 2109 // If the previous store is to the same address as this load, 2110 // and the value stored was larger than a char, replace this load 2111 // with the value stored truncated to a char. If no truncation is 2112 // needed, the replacement is done in LoadNode::Identity(). 2113 // 2114 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2115 Node* mem = in(MemNode::Memory); 2116 Node* value = can_see_stored_value(mem,phase); 2117 if( value && !phase->type(value)->higher_equal( _type ) ) 2118 return new AndINode(value,phase->intcon(0xFFFF)); 2119 // Identity call will handle the case where truncation is not needed. 2120 return LoadNode::Ideal(phase, can_reshape); 2121 } 2122 2123 const Type* LoadUSNode::Value(PhaseGVN* phase) const { 2124 Node* mem = in(MemNode::Memory); 2125 Node* value = can_see_stored_value(mem,phase); 2126 if (value != NULL && value->is_Con() && 2127 !value->bottom_type()->higher_equal(_type)) { 2128 // If the input to the store does not fit with the load's result type, 2129 // it must be truncated. We can't delay until Ideal call since 2130 // a singleton Value is needed for split_thru_phi optimization. 2131 int con = value->get_int(); 2132 return TypeInt::make(con & 0xFFFF); 2133 } 2134 return LoadNode::Value(phase); 2135 } 2136 2137 //--------------------------LoadSNode::Ideal-------------------------------------- 2138 // 2139 // If the previous store is to the same address as this load, 2140 // and the value stored was larger than a short, replace this load 2141 // with the value stored truncated to a short. If no truncation is 2142 // needed, the replacement is done in LoadNode::Identity(). 2143 // 2144 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2145 Node* mem = in(MemNode::Memory); 2146 Node* value = can_see_stored_value(mem,phase); 2147 if( value && !phase->type(value)->higher_equal( _type ) ) { 2148 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) ); 2149 return new RShiftINode(result, phase->intcon(16)); 2150 } 2151 // Identity call will handle the case where truncation is not needed. 2152 return LoadNode::Ideal(phase, can_reshape); 2153 } 2154 2155 const Type* LoadSNode::Value(PhaseGVN* phase) const { 2156 Node* mem = in(MemNode::Memory); 2157 Node* value = can_see_stored_value(mem,phase); 2158 if (value != NULL && value->is_Con() && 2159 !value->bottom_type()->higher_equal(_type)) { 2160 // If the input to the store does not fit with the load's result type, 2161 // it must be truncated. We can't delay until Ideal call since 2162 // a singleton Value is needed for split_thru_phi optimization. 2163 int con = value->get_int(); 2164 return TypeInt::make((con << 16) >> 16); 2165 } 2166 return LoadNode::Value(phase); 2167 } 2168 2169 //============================================================================= 2170 //----------------------------LoadKlassNode::make------------------------------ 2171 // Polymorphic factory method: 2172 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2173 // sanity check the alias category against the created node type 2174 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2175 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2176 #ifdef _LP64 2177 if (adr_type->is_ptr_to_narrowklass()) { 2178 assert(UseCompressedClassPointers, "no compressed klasses"); 2179 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2180 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2181 } 2182 #endif 2183 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2184 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2185 } 2186 2187 //------------------------------Value------------------------------------------ 2188 const Type* LoadKlassNode::Value(PhaseGVN* phase) const { 2189 return klass_value_common(phase); 2190 } 2191 2192 // In most cases, LoadKlassNode does not have the control input set. If the control 2193 // input is set, it must not be removed (by LoadNode::Ideal()). 2194 bool LoadKlassNode::can_remove_control() const { 2195 return false; 2196 } 2197 2198 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const { 2199 // Either input is TOP ==> the result is TOP 2200 const Type *t1 = phase->type( in(MemNode::Memory) ); 2201 if (t1 == Type::TOP) return Type::TOP; 2202 Node *adr = in(MemNode::Address); 2203 const Type *t2 = phase->type( adr ); 2204 if (t2 == Type::TOP) return Type::TOP; 2205 const TypePtr *tp = t2->is_ptr(); 2206 if (TypePtr::above_centerline(tp->ptr()) || 2207 tp->ptr() == TypePtr::Null) return Type::TOP; 2208 2209 // Return a more precise klass, if possible 2210 const TypeInstPtr *tinst = tp->isa_instptr(); 2211 if (tinst != NULL) { 2212 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2213 int offset = tinst->offset(); 2214 if (ik == phase->C->env()->Class_klass() 2215 && (offset == java_lang_Class::klass_offset_in_bytes() || 2216 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2217 // We are loading a special hidden field from a Class mirror object, 2218 // the field which points to the VM's Klass metaobject. 2219 bool is_indirect_type = true; 2220 ciType* t = tinst->java_mirror_type(&is_indirect_type); 2221 // java_mirror_type returns non-null for compile-time Class constants. 2222 if (t != NULL) { 2223 // constant oop => constant klass 2224 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2225 if (t->is_void()) { 2226 // We cannot create a void array. Since void is a primitive type return null 2227 // klass. Users of this result need to do a null check on the returned klass. 2228 return TypePtr::NULL_PTR; 2229 } 2230 return TypeKlassPtr::make(ciArrayKlass::make(t, /* never_null */ !is_indirect_type)); 2231 } 2232 if (!t->is_klass()) { 2233 // a primitive Class (e.g., int.class) has NULL for a klass field 2234 return TypePtr::NULL_PTR; 2235 } 2236 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2237 return TypeKlassPtr::make(t->as_klass()); 2238 } 2239 // non-constant mirror, so we can't tell what's going on 2240 } 2241 if( !ik->is_loaded() ) 2242 return _type; // Bail out if not loaded 2243 if (offset == oopDesc::klass_offset_in_bytes()) { 2244 if (tinst->klass_is_exact()) { 2245 return TypeKlassPtr::make(ik); 2246 } 2247 // See if we can become precise: no subklasses and no interface 2248 // (Note: We need to support verified interfaces.) 2249 if (!ik->is_interface() && !ik->has_subklass()) { 2250 //assert(!UseExactTypes, "this code should be useless with exact types"); 2251 // Add a dependence; if any subclass added we need to recompile 2252 if (!ik->is_final()) { 2253 // %%% should use stronger assert_unique_concrete_subtype instead 2254 phase->C->dependencies()->assert_leaf_type(ik); 2255 } 2256 // Return precise klass 2257 return TypeKlassPtr::make(ik); 2258 } 2259 2260 // Return root of possible klass 2261 return TypeKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0)); 2262 } 2263 } 2264 2265 // Check for loading klass from an array 2266 const TypeAryPtr *tary = tp->isa_aryptr(); 2267 if (tary != NULL) { 2268 ciKlass *tary_klass = tary->klass(); 2269 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2270 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2271 ciArrayKlass* ak = tary_klass->as_array_klass(); 2272 // Do not fold klass loads from [V?. The runtime type might be [V due to [V <: [V? 2273 // and the klass for [V is not equal to the klass for [V?. 2274 if (tary->klass_is_exact()) { 2275 return TypeKlassPtr::make(tary_klass); 2276 } 2277 2278 // If the klass is an object array, we defer the question to the 2279 // array component klass. 2280 if (ak->is_obj_array_klass()) { 2281 assert(ak->is_loaded(), ""); 2282 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2283 if (base_k->is_loaded() && base_k->is_instance_klass()) { 2284 ciInstanceKlass *ik = base_k->as_instance_klass(); 2285 // See if we can become precise: no subklasses and no interface 2286 if (!ik->is_interface() && !ik->has_subklass() && (!ik->is_valuetype() || ak->storage_properties().is_null_free())) { 2287 //assert(!UseExactTypes, "this code should be useless with exact types"); 2288 // Add a dependence; if any subclass added we need to recompile 2289 if (!ik->is_final()) { 2290 phase->C->dependencies()->assert_leaf_type(ik); 2291 } 2292 // Return precise array klass 2293 return TypeKlassPtr::make(ak); 2294 } 2295 } 2296 return TypeKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0)); 2297 } else if (ak->is_type_array_klass()) { 2298 //assert(!UseExactTypes, "this code should be useless with exact types"); 2299 return TypeKlassPtr::make(ak); // These are always precise 2300 } 2301 } 2302 } 2303 2304 // Check for loading klass from an array klass 2305 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2306 if (tkls != NULL && !StressReflectiveCode) { 2307 if (!tkls->is_loaded()) { 2308 return _type; // Bail out if not loaded 2309 } 2310 ciKlass* klass = tkls->klass(); 2311 if( klass->is_obj_array_klass() && 2312 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2313 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2314 // // Always returning precise element type is incorrect, 2315 // // e.g., element type could be object and array may contain strings 2316 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2317 2318 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2319 // according to the element type's subclassing. 2320 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0)); 2321 } else if (klass->is_value_array_klass() && 2322 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2323 ciKlass* elem = klass->as_value_array_klass()->element_klass(); 2324 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0)); 2325 } 2326 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2327 tkls->offset() == in_bytes(Klass::super_offset())) { 2328 ciKlass* sup = klass->as_instance_klass()->super(); 2329 // The field is Klass::_super. Return its (constant) value. 2330 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2331 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2332 } 2333 } 2334 2335 // Bailout case 2336 return LoadNode::Value(phase); 2337 } 2338 2339 //------------------------------Identity--------------------------------------- 2340 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2341 // Also feed through the klass in Allocate(...klass...)._klass. 2342 Node* LoadKlassNode::Identity(PhaseGVN* phase) { 2343 return klass_identity_common(phase); 2344 } 2345 2346 const Type* GetNullFreePropertyNode::Value(PhaseGVN* phase) const { 2347 if (in(1) != NULL) { 2348 const Type* in1_t = phase->type(in(1)); 2349 if (in1_t == Type::TOP) { 2350 return Type::TOP; 2351 } 2352 const TypeKlassPtr* tk = in1_t->make_ptr()->is_klassptr(); 2353 ciArrayKlass* ak = tk->klass()->as_array_klass(); 2354 ciKlass* elem = ak->element_klass(); 2355 if (tk->klass_is_exact() || (!elem->is_java_lang_Object() && !elem->is_interface() && !elem->is_valuetype())) { 2356 int props_shift = in1_t->isa_narrowklass() ? oopDesc::narrow_storage_props_shift : oopDesc::wide_storage_props_shift; 2357 ArrayStorageProperties props = ak->storage_properties(); 2358 intptr_t storage_properties = props.encode<intptr_t>(props_shift); 2359 if (in1_t->isa_narrowklass()) { 2360 return TypeInt::make((int)storage_properties); 2361 } 2362 return TypeX::make(storage_properties); 2363 } 2364 } 2365 return bottom_type(); 2366 } 2367 2368 Node* GetNullFreePropertyNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2369 if (!can_reshape) { 2370 return NULL; 2371 } 2372 if (in(1) != NULL && in(1)->is_Phi()) { 2373 Node* phi = in(1); 2374 Node* r = phi->in(0); 2375 Node* new_phi = new PhiNode(r, bottom_type()); 2376 for (uint i = 1; i < r->req(); i++) { 2377 Node* in = phi->in(i); 2378 if (in == NULL) continue; 2379 new_phi->init_req(i, phase->transform(new GetNullFreePropertyNode(in))); 2380 } 2381 return new_phi; 2382 } 2383 return NULL; 2384 } 2385 2386 Node* LoadNode::klass_identity_common(PhaseGVN* phase) { 2387 Node* x = LoadNode::Identity(phase); 2388 if (x != this) return x; 2389 2390 // Take apart the address into an oop and and offset. 2391 // Return 'this' if we cannot. 2392 Node* adr = in(MemNode::Address); 2393 intptr_t offset = 0; 2394 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2395 if (base == NULL) return this; 2396 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2397 if (toop == NULL) return this; 2398 2399 // Step over potential GC barrier for OopHandle resolve 2400 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 2401 if (bs->is_gc_barrier_node(base)) { 2402 base = bs->step_over_gc_barrier(base); 2403 } 2404 2405 // We can fetch the klass directly through an AllocateNode. 2406 // This works even if the klass is not constant (clone or newArray). 2407 if (offset == oopDesc::klass_offset_in_bytes()) { 2408 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2409 if (allocated_klass != NULL) { 2410 return allocated_klass; 2411 } 2412 } 2413 2414 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2415 // See inline_native_Class_query for occurrences of these patterns. 2416 // Java Example: x.getClass().isAssignableFrom(y) 2417 // 2418 // This improves reflective code, often making the Class 2419 // mirror go completely dead. (Current exception: Class 2420 // mirrors may appear in debug info, but we could clean them out by 2421 // introducing a new debug info operator for Klass.java_mirror). 2422 2423 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2424 && offset == java_lang_Class::klass_offset_in_bytes()) { 2425 if (base->is_Load()) { 2426 Node* base2 = base->in(MemNode::Address); 2427 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */ 2428 Node* adr2 = base2->in(MemNode::Address); 2429 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2430 if (tkls != NULL && !tkls->empty() 2431 && (tkls->klass()->is_instance_klass() || 2432 tkls->klass()->is_array_klass()) 2433 && adr2->is_AddP() 2434 ) { 2435 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2436 if (tkls->offset() == mirror_field) { 2437 return adr2->in(AddPNode::Base); 2438 } 2439 } 2440 } 2441 } 2442 } 2443 2444 return this; 2445 } 2446 2447 2448 //------------------------------Value------------------------------------------ 2449 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const { 2450 const Type *t = klass_value_common(phase); 2451 if (t == Type::TOP) 2452 return t; 2453 2454 return t->make_narrowklass(); 2455 } 2456 2457 //------------------------------Identity--------------------------------------- 2458 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2459 // Also feed through the klass in Allocate(...klass...)._klass. 2460 Node* LoadNKlassNode::Identity(PhaseGVN* phase) { 2461 Node *x = klass_identity_common(phase); 2462 2463 const Type *t = phase->type( x ); 2464 if( t == Type::TOP ) return x; 2465 if( t->isa_narrowklass()) return x; 2466 assert (!t->isa_narrowoop(), "no narrow oop here"); 2467 2468 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2469 } 2470 2471 //------------------------------Value----------------------------------------- 2472 const Type* LoadRangeNode::Value(PhaseGVN* phase) const { 2473 // Either input is TOP ==> the result is TOP 2474 const Type *t1 = phase->type( in(MemNode::Memory) ); 2475 if( t1 == Type::TOP ) return Type::TOP; 2476 Node *adr = in(MemNode::Address); 2477 const Type *t2 = phase->type( adr ); 2478 if( t2 == Type::TOP ) return Type::TOP; 2479 const TypePtr *tp = t2->is_ptr(); 2480 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2481 const TypeAryPtr *tap = tp->isa_aryptr(); 2482 if( !tap ) return _type; 2483 return tap->size(); 2484 } 2485 2486 //-------------------------------Ideal--------------------------------------- 2487 // Feed through the length in AllocateArray(...length...)._length. 2488 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2489 Node* p = MemNode::Ideal_common(phase, can_reshape); 2490 if (p) return (p == NodeSentinel) ? NULL : p; 2491 2492 // Take apart the address into an oop and and offset. 2493 // Return 'this' if we cannot. 2494 Node* adr = in(MemNode::Address); 2495 intptr_t offset = 0; 2496 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2497 if (base == NULL) return NULL; 2498 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2499 if (tary == NULL) return NULL; 2500 2501 // We can fetch the length directly through an AllocateArrayNode. 2502 // This works even if the length is not constant (clone or newArray). 2503 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2504 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2505 if (alloc != NULL) { 2506 Node* allocated_length = alloc->Ideal_length(); 2507 Node* len = alloc->make_ideal_length(tary, phase); 2508 if (allocated_length != len) { 2509 // New CastII improves on this. 2510 return len; 2511 } 2512 } 2513 } 2514 2515 return NULL; 2516 } 2517 2518 //------------------------------Identity--------------------------------------- 2519 // Feed through the length in AllocateArray(...length...)._length. 2520 Node* LoadRangeNode::Identity(PhaseGVN* phase) { 2521 Node* x = LoadINode::Identity(phase); 2522 if (x != this) return x; 2523 2524 // Take apart the address into an oop and and offset. 2525 // Return 'this' if we cannot. 2526 Node* adr = in(MemNode::Address); 2527 intptr_t offset = 0; 2528 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2529 if (base == NULL) return this; 2530 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2531 if (tary == NULL) return this; 2532 2533 // We can fetch the length directly through an AllocateArrayNode. 2534 // This works even if the length is not constant (clone or newArray). 2535 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2536 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2537 if (alloc != NULL) { 2538 Node* allocated_length = alloc->Ideal_length(); 2539 // Do not allow make_ideal_length to allocate a CastII node. 2540 Node* len = alloc->make_ideal_length(tary, phase, false); 2541 if (allocated_length == len) { 2542 // Return allocated_length only if it would not be improved by a CastII. 2543 return allocated_length; 2544 } 2545 } 2546 } 2547 2548 return this; 2549 2550 } 2551 2552 //============================================================================= 2553 //---------------------------StoreNode::make----------------------------------- 2554 // Polymorphic factory method: 2555 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2556 assert((mo == unordered || mo == release), "unexpected"); 2557 Compile* C = gvn.C; 2558 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2559 ctl != NULL, "raw memory operations should have control edge"); 2560 2561 switch (bt) { 2562 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case 2563 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2564 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2565 case T_CHAR: 2566 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2567 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2568 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2569 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2570 case T_METADATA: 2571 case T_ADDRESS: 2572 case T_VALUETYPE: 2573 case T_OBJECT: 2574 #ifdef _LP64 2575 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2576 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2577 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2578 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2579 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2580 adr->bottom_type()->isa_rawptr())) { 2581 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2582 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2583 } 2584 #endif 2585 { 2586 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2587 } 2588 default: 2589 ShouldNotReachHere(); 2590 return (StoreNode*)NULL; 2591 } 2592 } 2593 2594 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2595 bool require_atomic = true; 2596 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2597 } 2598 2599 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2600 bool require_atomic = true; 2601 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2602 } 2603 2604 2605 //--------------------------bottom_type---------------------------------------- 2606 const Type *StoreNode::bottom_type() const { 2607 return Type::MEMORY; 2608 } 2609 2610 //------------------------------hash------------------------------------------- 2611 uint StoreNode::hash() const { 2612 // unroll addition of interesting fields 2613 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2614 2615 // Since they are not commoned, do not hash them: 2616 return NO_HASH; 2617 } 2618 2619 //------------------------------Ideal------------------------------------------ 2620 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2621 // When a store immediately follows a relevant allocation/initialization, 2622 // try to capture it into the initialization, or hoist it above. 2623 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2624 Node* p = MemNode::Ideal_common(phase, can_reshape); 2625 if (p) return (p == NodeSentinel) ? NULL : p; 2626 2627 Node* mem = in(MemNode::Memory); 2628 Node* address = in(MemNode::Address); 2629 // Back-to-back stores to same address? Fold em up. Generally 2630 // unsafe if I have intervening uses... Also disallowed for StoreCM 2631 // since they must follow each StoreP operation. Redundant StoreCMs 2632 // are eliminated just before matching in final_graph_reshape. 2633 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::VALUES) { 2634 Node* st = mem; 2635 // If Store 'st' has more than one use, we cannot fold 'st' away. 2636 // For example, 'st' might be the final state at a conditional 2637 // return. Or, 'st' might be used by some node which is live at 2638 // the same time 'st' is live, which might be unschedulable. So, 2639 // require exactly ONE user until such time as we clone 'mem' for 2640 // each of 'mem's uses (thus making the exactly-1-user-rule hold 2641 // true). 2642 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) { 2643 // Looking at a dead closed cycle of memory? 2644 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2645 assert(Opcode() == st->Opcode() || 2646 st->Opcode() == Op_StoreVector || 2647 Opcode() == Op_StoreVector || 2648 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw || 2649 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode 2650 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy 2651 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) || 2652 (is_mismatched_access() || st->as_Store()->is_mismatched_access()), 2653 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]); 2654 2655 if (st->in(MemNode::Address)->eqv_uncast(address) && 2656 st->as_Store()->memory_size() <= this->memory_size()) { 2657 Node* use = st->raw_out(0); 2658 phase->igvn_rehash_node_delayed(use); 2659 if (can_reshape) { 2660 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN()); 2661 } else { 2662 // It's OK to do this in the parser, since DU info is always accurate, 2663 // and the parser always refers to nodes via SafePointNode maps. 2664 use->set_req(MemNode::Memory, st->in(MemNode::Memory)); 2665 } 2666 return this; 2667 } 2668 st = st->in(MemNode::Memory); 2669 } 2670 } 2671 2672 2673 // Capture an unaliased, unconditional, simple store into an initializer. 2674 // Or, if it is independent of the allocation, hoist it above the allocation. 2675 if (ReduceFieldZeroing && /*can_reshape &&*/ 2676 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2677 InitializeNode* init = mem->in(0)->as_Initialize(); 2678 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2679 if (offset > 0) { 2680 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2681 // If the InitializeNode captured me, it made a raw copy of me, 2682 // and I need to disappear. 2683 if (moved != NULL) { 2684 // %%% hack to ensure that Ideal returns a new node: 2685 mem = MergeMemNode::make(mem); 2686 return mem; // fold me away 2687 } 2688 } 2689 } 2690 2691 return NULL; // No further progress 2692 } 2693 2694 //------------------------------Value----------------------------------------- 2695 const Type* StoreNode::Value(PhaseGVN* phase) const { 2696 // Either input is TOP ==> the result is TOP 2697 const Type *t1 = phase->type( in(MemNode::Memory) ); 2698 if( t1 == Type::TOP ) return Type::TOP; 2699 const Type *t2 = phase->type( in(MemNode::Address) ); 2700 if( t2 == Type::TOP ) return Type::TOP; 2701 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2702 if( t3 == Type::TOP ) return Type::TOP; 2703 return Type::MEMORY; 2704 } 2705 2706 //------------------------------Identity--------------------------------------- 2707 // Remove redundant stores: 2708 // Store(m, p, Load(m, p)) changes to m. 2709 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2710 Node* StoreNode::Identity(PhaseGVN* phase) { 2711 Node* mem = in(MemNode::Memory); 2712 Node* adr = in(MemNode::Address); 2713 Node* val = in(MemNode::ValueIn); 2714 2715 Node* result = this; 2716 2717 // Load then Store? Then the Store is useless 2718 if (val->is_Load() && 2719 val->in(MemNode::Address)->eqv_uncast(adr) && 2720 val->in(MemNode::Memory )->eqv_uncast(mem) && 2721 val->as_Load()->store_Opcode() == Opcode()) { 2722 result = mem; 2723 } 2724 2725 // Two stores in a row of the same value? 2726 if (result == this && 2727 mem->is_Store() && 2728 mem->in(MemNode::Address)->eqv_uncast(adr) && 2729 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2730 mem->Opcode() == Opcode()) { 2731 result = mem; 2732 } 2733 2734 // Store of zero anywhere into a freshly-allocated object? 2735 // Then the store is useless. 2736 // (It must already have been captured by the InitializeNode.) 2737 if (result == this && ReduceFieldZeroing) { 2738 // a newly allocated object is already all-zeroes everywhere 2739 if (mem->is_Proj() && mem->in(0)->is_Allocate() && 2740 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) { 2741 assert(!phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == NULL, "storing null to value array is forbidden"); 2742 result = mem; 2743 } 2744 2745 if (result == this) { 2746 // the store may also apply to zero-bits in an earlier object 2747 Node* prev_mem = find_previous_store(phase); 2748 // Steps (a), (b): Walk past independent stores to find an exact match. 2749 if (prev_mem != NULL) { 2750 Node* prev_val = can_see_stored_value(prev_mem, phase); 2751 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2752 // prev_val and val might differ by a cast; it would be good 2753 // to keep the more informative of the two. 2754 if (phase->type(val)->is_zero_type()) { 2755 result = mem; 2756 } else if (prev_mem->is_Proj() && prev_mem->in(0)->is_Initialize()) { 2757 InitializeNode* init = prev_mem->in(0)->as_Initialize(); 2758 AllocateNode* alloc = init->allocation(); 2759 if (alloc != NULL && alloc->in(AllocateNode::DefaultValue) == val) { 2760 result = mem; 2761 } 2762 } 2763 } 2764 } 2765 } 2766 } 2767 2768 if (result != this && phase->is_IterGVN() != NULL) { 2769 MemBarNode* trailing = trailing_membar(); 2770 if (trailing != NULL) { 2771 #ifdef ASSERT 2772 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr(); 2773 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects"); 2774 #endif 2775 PhaseIterGVN* igvn = phase->is_IterGVN(); 2776 trailing->remove(igvn); 2777 } 2778 } 2779 2780 return result; 2781 } 2782 2783 //------------------------------match_edge------------------------------------- 2784 // Do we Match on this edge index or not? Match only memory & value 2785 uint StoreNode::match_edge(uint idx) const { 2786 return idx == MemNode::Address || idx == MemNode::ValueIn; 2787 } 2788 2789 //------------------------------cmp-------------------------------------------- 2790 // Do not common stores up together. They generally have to be split 2791 // back up anyways, so do not bother. 2792 bool StoreNode::cmp( const Node &n ) const { 2793 return (&n == this); // Always fail except on self 2794 } 2795 2796 //------------------------------Ideal_masked_input----------------------------- 2797 // Check for a useless mask before a partial-word store 2798 // (StoreB ... (AndI valIn conIa) ) 2799 // If (conIa & mask == mask) this simplifies to 2800 // (StoreB ... (valIn) ) 2801 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2802 Node *val = in(MemNode::ValueIn); 2803 if( val->Opcode() == Op_AndI ) { 2804 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2805 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2806 set_req(MemNode::ValueIn, val->in(1)); 2807 return this; 2808 } 2809 } 2810 return NULL; 2811 } 2812 2813 2814 //------------------------------Ideal_sign_extended_input---------------------- 2815 // Check for useless sign-extension before a partial-word store 2816 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2817 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2818 // (StoreB ... (valIn) ) 2819 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2820 Node *val = in(MemNode::ValueIn); 2821 if( val->Opcode() == Op_RShiftI ) { 2822 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2823 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2824 Node *shl = val->in(1); 2825 if( shl->Opcode() == Op_LShiftI ) { 2826 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2827 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2828 set_req(MemNode::ValueIn, shl->in(1)); 2829 return this; 2830 } 2831 } 2832 } 2833 } 2834 return NULL; 2835 } 2836 2837 //------------------------------value_never_loaded----------------------------------- 2838 // Determine whether there are any possible loads of the value stored. 2839 // For simplicity, we actually check if there are any loads from the 2840 // address stored to, not just for loads of the value stored by this node. 2841 // 2842 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2843 Node *adr = in(Address); 2844 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2845 if (adr_oop == NULL) 2846 return false; 2847 if (!adr_oop->is_known_instance_field()) 2848 return false; // if not a distinct instance, there may be aliases of the address 2849 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2850 Node *use = adr->fast_out(i); 2851 if (use->is_Load() || use->is_LoadStore()) { 2852 return false; 2853 } 2854 } 2855 return true; 2856 } 2857 2858 MemBarNode* StoreNode::trailing_membar() const { 2859 if (is_release()) { 2860 MemBarNode* trailing_mb = NULL; 2861 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2862 Node* u = fast_out(i); 2863 if (u->is_MemBar()) { 2864 if (u->as_MemBar()->trailing_store()) { 2865 assert(u->Opcode() == Op_MemBarVolatile, ""); 2866 assert(trailing_mb == NULL, "only one"); 2867 trailing_mb = u->as_MemBar(); 2868 #ifdef ASSERT 2869 Node* leading = u->as_MemBar()->leading_membar(); 2870 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 2871 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair"); 2872 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair"); 2873 #endif 2874 } else { 2875 assert(u->as_MemBar()->standalone(), ""); 2876 } 2877 } 2878 } 2879 return trailing_mb; 2880 } 2881 return NULL; 2882 } 2883 2884 2885 //============================================================================= 2886 //------------------------------Ideal------------------------------------------ 2887 // If the store is from an AND mask that leaves the low bits untouched, then 2888 // we can skip the AND operation. If the store is from a sign-extension 2889 // (a left shift, then right shift) we can skip both. 2890 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2891 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2892 if( progress != NULL ) return progress; 2893 2894 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2895 if( progress != NULL ) return progress; 2896 2897 // Finally check the default case 2898 return StoreNode::Ideal(phase, can_reshape); 2899 } 2900 2901 //============================================================================= 2902 //------------------------------Ideal------------------------------------------ 2903 // If the store is from an AND mask that leaves the low bits untouched, then 2904 // we can skip the AND operation 2905 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2906 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2907 if( progress != NULL ) return progress; 2908 2909 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2910 if( progress != NULL ) return progress; 2911 2912 // Finally check the default case 2913 return StoreNode::Ideal(phase, can_reshape); 2914 } 2915 2916 //============================================================================= 2917 //------------------------------Identity--------------------------------------- 2918 Node* StoreCMNode::Identity(PhaseGVN* phase) { 2919 // No need to card mark when storing a null ptr 2920 Node* my_store = in(MemNode::OopStore); 2921 if (my_store->is_Store()) { 2922 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2923 if( t1 == TypePtr::NULL_PTR ) { 2924 return in(MemNode::Memory); 2925 } 2926 } 2927 return this; 2928 } 2929 2930 //============================================================================= 2931 //------------------------------Ideal--------------------------------------- 2932 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2933 Node* progress = StoreNode::Ideal(phase, can_reshape); 2934 if (progress != NULL) return progress; 2935 2936 Node* my_store = in(MemNode::OopStore); 2937 if (my_store->is_MergeMem()) { 2938 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2939 set_req(MemNode::OopStore, mem); 2940 return this; 2941 } 2942 2943 return NULL; 2944 } 2945 2946 //------------------------------Value----------------------------------------- 2947 const Type* StoreCMNode::Value(PhaseGVN* phase) const { 2948 // Either input is TOP ==> the result is TOP 2949 const Type *t = phase->type( in(MemNode::Memory) ); 2950 if( t == Type::TOP ) return Type::TOP; 2951 t = phase->type( in(MemNode::Address) ); 2952 if( t == Type::TOP ) return Type::TOP; 2953 t = phase->type( in(MemNode::ValueIn) ); 2954 if( t == Type::TOP ) return Type::TOP; 2955 // If extra input is TOP ==> the result is TOP 2956 t = phase->type( in(MemNode::OopStore) ); 2957 if( t == Type::TOP ) return Type::TOP; 2958 2959 return StoreNode::Value( phase ); 2960 } 2961 2962 2963 //============================================================================= 2964 //----------------------------------SCMemProjNode------------------------------ 2965 const Type* SCMemProjNode::Value(PhaseGVN* phase) const 2966 { 2967 return bottom_type(); 2968 } 2969 2970 //============================================================================= 2971 //----------------------------------LoadStoreNode------------------------------ 2972 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2973 : Node(required), 2974 _type(rt), 2975 _adr_type(at), 2976 _has_barrier(false) 2977 { 2978 init_req(MemNode::Control, c ); 2979 init_req(MemNode::Memory , mem); 2980 init_req(MemNode::Address, adr); 2981 init_req(MemNode::ValueIn, val); 2982 init_class_id(Class_LoadStore); 2983 } 2984 2985 uint LoadStoreNode::ideal_reg() const { 2986 return _type->ideal_reg(); 2987 } 2988 2989 bool LoadStoreNode::result_not_used() const { 2990 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2991 Node *x = fast_out(i); 2992 if (x->Opcode() == Op_SCMemProj) continue; 2993 return false; 2994 } 2995 return true; 2996 } 2997 2998 MemBarNode* LoadStoreNode::trailing_membar() const { 2999 MemBarNode* trailing = NULL; 3000 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 3001 Node* u = fast_out(i); 3002 if (u->is_MemBar()) { 3003 if (u->as_MemBar()->trailing_load_store()) { 3004 assert(u->Opcode() == Op_MemBarAcquire, ""); 3005 assert(trailing == NULL, "only one"); 3006 trailing = u->as_MemBar(); 3007 #ifdef ASSERT 3008 Node* leading = trailing->leading_membar(); 3009 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 3010 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair"); 3011 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair"); 3012 #endif 3013 } else { 3014 assert(u->as_MemBar()->standalone(), "wrong barrier kind"); 3015 } 3016 } 3017 } 3018 3019 return trailing; 3020 } 3021 3022 uint LoadStoreNode::size_of() const { return sizeof(*this); } 3023 3024 //============================================================================= 3025 //----------------------------------LoadStoreConditionalNode-------------------- 3026 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 3027 init_req(ExpectedIn, ex ); 3028 } 3029 3030 //============================================================================= 3031 //-------------------------------adr_type-------------------------------------- 3032 const TypePtr* ClearArrayNode::adr_type() const { 3033 Node *adr = in(3); 3034 if (adr == NULL) return NULL; // node is dead 3035 return MemNode::calculate_adr_type(adr->bottom_type()); 3036 } 3037 3038 //------------------------------match_edge------------------------------------- 3039 // Do we Match on this edge index or not? Do not match memory 3040 uint ClearArrayNode::match_edge(uint idx) const { 3041 return idx > 1; 3042 } 3043 3044 //------------------------------Identity--------------------------------------- 3045 // Clearing a zero length array does nothing 3046 Node* ClearArrayNode::Identity(PhaseGVN* phase) { 3047 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 3048 } 3049 3050 //------------------------------Idealize--------------------------------------- 3051 // Clearing a short array is faster with stores 3052 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3053 // Already know this is a large node, do not try to ideal it 3054 if (!IdealizeClearArrayNode || _is_large) return NULL; 3055 3056 const int unit = BytesPerLong; 3057 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 3058 if (!t) return NULL; 3059 if (!t->is_con()) return NULL; 3060 intptr_t raw_count = t->get_con(); 3061 intptr_t size = raw_count; 3062 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 3063 // Clearing nothing uses the Identity call. 3064 // Negative clears are possible on dead ClearArrays 3065 // (see jck test stmt114.stmt11402.val). 3066 if (size <= 0 || size % unit != 0) return NULL; 3067 intptr_t count = size / unit; 3068 // Length too long; communicate this to matchers and assemblers. 3069 // Assemblers are responsible to produce fast hardware clears for it. 3070 if (size > InitArrayShortSize) { 3071 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true); 3072 } 3073 Node *mem = in(1); 3074 if( phase->type(mem)==Type::TOP ) return NULL; 3075 Node *adr = in(3); 3076 const Type* at = phase->type(adr); 3077 if( at==Type::TOP ) return NULL; 3078 const TypePtr* atp = at->isa_ptr(); 3079 // adjust atp to be the correct array element address type 3080 if (atp == NULL) atp = TypePtr::BOTTOM; 3081 else atp = atp->add_offset(Type::OffsetBot); 3082 // Get base for derived pointer purposes 3083 if( adr->Opcode() != Op_AddP ) Unimplemented(); 3084 Node *base = adr->in(1); 3085 3086 Node *val = in(4); 3087 Node *off = phase->MakeConX(BytesPerLong); 3088 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false); 3089 count--; 3090 while( count-- ) { 3091 mem = phase->transform(mem); 3092 adr = phase->transform(new AddPNode(base,adr,off)); 3093 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false); 3094 } 3095 return mem; 3096 } 3097 3098 //----------------------------step_through---------------------------------- 3099 // Return allocation input memory edge if it is different instance 3100 // or itself if it is the one we are looking for. 3101 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 3102 Node* n = *np; 3103 assert(n->is_ClearArray(), "sanity"); 3104 intptr_t offset; 3105 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 3106 // This method is called only before Allocate nodes are expanded 3107 // during macro nodes expansion. Before that ClearArray nodes are 3108 // only generated in PhaseMacroExpand::generate_arraycopy() (before 3109 // Allocate nodes are expanded) which follows allocations. 3110 assert(alloc != NULL, "should have allocation"); 3111 if (alloc->_idx == instance_id) { 3112 // Can not bypass initialization of the instance we are looking for. 3113 return false; 3114 } 3115 // Otherwise skip it. 3116 InitializeNode* init = alloc->initialization(); 3117 if (init != NULL) 3118 *np = init->in(TypeFunc::Memory); 3119 else 3120 *np = alloc->in(TypeFunc::Memory); 3121 return true; 3122 } 3123 3124 //----------------------------clear_memory------------------------------------- 3125 // Generate code to initialize object storage to zero. 3126 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3127 Node* val, 3128 Node* raw_val, 3129 intptr_t start_offset, 3130 Node* end_offset, 3131 PhaseGVN* phase) { 3132 intptr_t offset = start_offset; 3133 3134 int unit = BytesPerLong; 3135 if ((offset % unit) != 0) { 3136 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 3137 adr = phase->transform(adr); 3138 const TypePtr* atp = TypeRawPtr::BOTTOM; 3139 if (val != NULL) { 3140 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop"); 3141 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered); 3142 } else { 3143 assert(raw_val == NULL, "val may not be null"); 3144 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 3145 } 3146 mem = phase->transform(mem); 3147 offset += BytesPerInt; 3148 } 3149 assert((offset % unit) == 0, ""); 3150 3151 // Initialize the remaining stuff, if any, with a ClearArray. 3152 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase); 3153 } 3154 3155 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3156 Node* raw_val, 3157 Node* start_offset, 3158 Node* end_offset, 3159 PhaseGVN* phase) { 3160 if (start_offset == end_offset) { 3161 // nothing to do 3162 return mem; 3163 } 3164 3165 int unit = BytesPerLong; 3166 Node* zbase = start_offset; 3167 Node* zend = end_offset; 3168 3169 // Scale to the unit required by the CPU: 3170 if (!Matcher::init_array_count_is_in_bytes) { 3171 Node* shift = phase->intcon(exact_log2(unit)); 3172 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 3173 zend = phase->transform(new URShiftXNode(zend, shift) ); 3174 } 3175 3176 // Bulk clear double-words 3177 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 3178 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 3179 if (raw_val == NULL) { 3180 raw_val = phase->MakeConX(0); 3181 } 3182 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false); 3183 return phase->transform(mem); 3184 } 3185 3186 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3187 Node* val, 3188 Node* raw_val, 3189 intptr_t start_offset, 3190 intptr_t end_offset, 3191 PhaseGVN* phase) { 3192 if (start_offset == end_offset) { 3193 // nothing to do 3194 return mem; 3195 } 3196 3197 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 3198 intptr_t done_offset = end_offset; 3199 if ((done_offset % BytesPerLong) != 0) { 3200 done_offset -= BytesPerInt; 3201 } 3202 if (done_offset > start_offset) { 3203 mem = clear_memory(ctl, mem, dest, val, raw_val, 3204 start_offset, phase->MakeConX(done_offset), phase); 3205 } 3206 if (done_offset < end_offset) { // emit the final 32-bit store 3207 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 3208 adr = phase->transform(adr); 3209 const TypePtr* atp = TypeRawPtr::BOTTOM; 3210 if (val != NULL) { 3211 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop"); 3212 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered); 3213 } else { 3214 assert(raw_val == NULL, "val may not be null"); 3215 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 3216 } 3217 mem = phase->transform(mem); 3218 done_offset += BytesPerInt; 3219 } 3220 assert(done_offset == end_offset, ""); 3221 return mem; 3222 } 3223 3224 //============================================================================= 3225 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 3226 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 3227 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone) 3228 #ifdef ASSERT 3229 , _pair_idx(0) 3230 #endif 3231 { 3232 init_class_id(Class_MemBar); 3233 Node* top = C->top(); 3234 init_req(TypeFunc::I_O,top); 3235 init_req(TypeFunc::FramePtr,top); 3236 init_req(TypeFunc::ReturnAdr,top); 3237 if (precedent != NULL) 3238 init_req(TypeFunc::Parms, precedent); 3239 } 3240 3241 //------------------------------cmp-------------------------------------------- 3242 uint MemBarNode::hash() const { return NO_HASH; } 3243 bool MemBarNode::cmp( const Node &n ) const { 3244 return (&n == this); // Always fail except on self 3245 } 3246 3247 //------------------------------make------------------------------------------- 3248 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 3249 switch (opcode) { 3250 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 3251 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 3252 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 3253 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 3254 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 3255 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 3256 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 3257 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 3258 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn); 3259 case Op_Initialize: return new InitializeNode(C, atp, pn); 3260 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 3261 default: ShouldNotReachHere(); return NULL; 3262 } 3263 } 3264 3265 void MemBarNode::remove(PhaseIterGVN *igvn) { 3266 if (outcnt() != 2) { 3267 return; 3268 } 3269 if (trailing_store() || trailing_load_store()) { 3270 MemBarNode* leading = leading_membar(); 3271 if (leading != NULL) { 3272 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars"); 3273 leading->remove(igvn); 3274 } 3275 } 3276 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 3277 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 3278 } 3279 3280 //------------------------------Ideal------------------------------------------ 3281 // Return a node which is more "ideal" than the current node. Strip out 3282 // control copies 3283 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3284 if (remove_dead_region(phase, can_reshape)) return this; 3285 // Don't bother trying to transform a dead node 3286 if (in(0) && in(0)->is_top()) { 3287 return NULL; 3288 } 3289 3290 bool progress = false; 3291 // Eliminate volatile MemBars for scalar replaced objects. 3292 if (can_reshape && req() == (Precedent+1)) { 3293 bool eliminate = false; 3294 int opc = Opcode(); 3295 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 3296 // Volatile field loads and stores. 3297 Node* my_mem = in(MemBarNode::Precedent); 3298 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 3299 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 3300 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 3301 // replace this Precedent (decodeN) with the Load instead. 3302 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 3303 Node* load_node = my_mem->in(1); 3304 set_req(MemBarNode::Precedent, load_node); 3305 phase->is_IterGVN()->_worklist.push(my_mem); 3306 my_mem = load_node; 3307 } else { 3308 assert(my_mem->unique_out() == this, "sanity"); 3309 del_req(Precedent); 3310 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 3311 my_mem = NULL; 3312 } 3313 progress = true; 3314 } 3315 if (my_mem != NULL && my_mem->is_Mem()) { 3316 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 3317 // Check for scalar replaced object reference. 3318 if( t_oop != NULL && t_oop->is_known_instance_field() && 3319 t_oop->offset() != Type::OffsetBot && 3320 t_oop->offset() != Type::OffsetTop) { 3321 eliminate = true; 3322 } 3323 } 3324 } else if (opc == Op_MemBarRelease) { 3325 // Final field stores. 3326 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 3327 if ((alloc != NULL) && alloc->is_Allocate() && 3328 alloc->as_Allocate()->does_not_escape_thread()) { 3329 // The allocated object does not escape. 3330 eliminate = true; 3331 } 3332 } 3333 if (eliminate) { 3334 // Replace MemBar projections by its inputs. 3335 PhaseIterGVN* igvn = phase->is_IterGVN(); 3336 remove(igvn); 3337 // Must return either the original node (now dead) or a new node 3338 // (Do not return a top here, since that would break the uniqueness of top.) 3339 return new ConINode(TypeInt::ZERO); 3340 } 3341 } 3342 return progress ? this : NULL; 3343 } 3344 3345 //------------------------------Value------------------------------------------ 3346 const Type* MemBarNode::Value(PhaseGVN* phase) const { 3347 if( !in(0) ) return Type::TOP; 3348 if( phase->type(in(0)) == Type::TOP ) 3349 return Type::TOP; 3350 return TypeTuple::MEMBAR; 3351 } 3352 3353 //------------------------------match------------------------------------------ 3354 // Construct projections for memory. 3355 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) { 3356 switch (proj->_con) { 3357 case TypeFunc::Control: 3358 case TypeFunc::Memory: 3359 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3360 } 3361 ShouldNotReachHere(); 3362 return NULL; 3363 } 3364 3365 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3366 trailing->_kind = TrailingStore; 3367 leading->_kind = LeadingStore; 3368 #ifdef ASSERT 3369 trailing->_pair_idx = leading->_idx; 3370 leading->_pair_idx = leading->_idx; 3371 #endif 3372 } 3373 3374 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3375 trailing->_kind = TrailingLoadStore; 3376 leading->_kind = LeadingLoadStore; 3377 #ifdef ASSERT 3378 trailing->_pair_idx = leading->_idx; 3379 leading->_pair_idx = leading->_idx; 3380 #endif 3381 } 3382 3383 MemBarNode* MemBarNode::trailing_membar() const { 3384 ResourceMark rm; 3385 Node* trailing = (Node*)this; 3386 VectorSet seen(Thread::current()->resource_area()); 3387 Node_Stack multis(0); 3388 do { 3389 Node* c = trailing; 3390 uint i = 0; 3391 do { 3392 trailing = NULL; 3393 for (; i < c->outcnt(); i++) { 3394 Node* next = c->raw_out(i); 3395 if (next != c && next->is_CFG()) { 3396 if (c->is_MultiBranch()) { 3397 if (multis.node() == c) { 3398 multis.set_index(i+1); 3399 } else { 3400 multis.push(c, i+1); 3401 } 3402 } 3403 trailing = next; 3404 break; 3405 } 3406 } 3407 if (trailing != NULL && !seen.test_set(trailing->_idx)) { 3408 break; 3409 } 3410 while (multis.size() > 0) { 3411 c = multis.node(); 3412 i = multis.index(); 3413 if (i < c->req()) { 3414 break; 3415 } 3416 multis.pop(); 3417 } 3418 } while (multis.size() > 0); 3419 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing()); 3420 3421 MemBarNode* mb = trailing->as_MemBar(); 3422 assert((mb->_kind == TrailingStore && _kind == LeadingStore) || 3423 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar"); 3424 assert(mb->_pair_idx == _pair_idx, "bad trailing membar"); 3425 return mb; 3426 } 3427 3428 MemBarNode* MemBarNode::leading_membar() const { 3429 ResourceMark rm; 3430 VectorSet seen(Thread::current()->resource_area()); 3431 Node_Stack regions(0); 3432 Node* leading = in(0); 3433 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) { 3434 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) { 3435 leading = NULL; 3436 while (regions.size() > 0 && leading == NULL) { 3437 Node* r = regions.node(); 3438 uint i = regions.index(); 3439 if (i < r->req()) { 3440 leading = r->in(i); 3441 regions.set_index(i+1); 3442 } else { 3443 regions.pop(); 3444 } 3445 } 3446 if (leading == NULL) { 3447 assert(regions.size() == 0, "all paths should have been tried"); 3448 return NULL; 3449 } 3450 } 3451 if (leading->is_Region()) { 3452 regions.push(leading, 2); 3453 leading = leading->in(1); 3454 } else { 3455 leading = leading->in(0); 3456 } 3457 } 3458 #ifdef ASSERT 3459 Unique_Node_List wq; 3460 wq.push((Node*)this); 3461 uint found = 0; 3462 for (uint i = 0; i < wq.size(); i++) { 3463 Node* n = wq.at(i); 3464 if (n->is_Region()) { 3465 for (uint j = 1; j < n->req(); j++) { 3466 Node* in = n->in(j); 3467 if (in != NULL && !in->is_top()) { 3468 wq.push(in); 3469 } 3470 } 3471 } else { 3472 if (n->is_MemBar() && n->as_MemBar()->leading()) { 3473 assert(n == leading, "consistency check failed"); 3474 found++; 3475 } else { 3476 Node* in = n->in(0); 3477 if (in != NULL && !in->is_top()) { 3478 wq.push(in); 3479 } 3480 } 3481 } 3482 } 3483 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed"); 3484 #endif 3485 if (leading == NULL) { 3486 return NULL; 3487 } 3488 MemBarNode* mb = leading->as_MemBar(); 3489 assert((mb->_kind == LeadingStore && _kind == TrailingStore) || 3490 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar"); 3491 assert(mb->_pair_idx == _pair_idx, "bad leading membar"); 3492 return mb; 3493 } 3494 3495 //===========================InitializeNode==================================== 3496 // SUMMARY: 3497 // This node acts as a memory barrier on raw memory, after some raw stores. 3498 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 3499 // The Initialize can 'capture' suitably constrained stores as raw inits. 3500 // It can coalesce related raw stores into larger units (called 'tiles'). 3501 // It can avoid zeroing new storage for memory units which have raw inits. 3502 // At macro-expansion, it is marked 'complete', and does not optimize further. 3503 // 3504 // EXAMPLE: 3505 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3506 // ctl = incoming control; mem* = incoming memory 3507 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 3508 // First allocate uninitialized memory and fill in the header: 3509 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 3510 // ctl := alloc.Control; mem* := alloc.Memory* 3511 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 3512 // Then initialize to zero the non-header parts of the raw memory block: 3513 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3514 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3515 // After the initialize node executes, the object is ready for service: 3516 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3517 // Suppose its body is immediately initialized as {1,2}: 3518 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3519 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3520 // mem.SLICE(#short[*]) := store2 3521 // 3522 // DETAILS: 3523 // An InitializeNode collects and isolates object initialization after 3524 // an AllocateNode and before the next possible safepoint. As a 3525 // memory barrier (MemBarNode), it keeps critical stores from drifting 3526 // down past any safepoint or any publication of the allocation. 3527 // Before this barrier, a newly-allocated object may have uninitialized bits. 3528 // After this barrier, it may be treated as a real oop, and GC is allowed. 3529 // 3530 // The semantics of the InitializeNode include an implicit zeroing of 3531 // the new object from object header to the end of the object. 3532 // (The object header and end are determined by the AllocateNode.) 3533 // 3534 // Certain stores may be added as direct inputs to the InitializeNode. 3535 // These stores must update raw memory, and they must be to addresses 3536 // derived from the raw address produced by AllocateNode, and with 3537 // a constant offset. They must be ordered by increasing offset. 3538 // The first one is at in(RawStores), the last at in(req()-1). 3539 // Unlike most memory operations, they are not linked in a chain, 3540 // but are displayed in parallel as users of the rawmem output of 3541 // the allocation. 3542 // 3543 // (See comments in InitializeNode::capture_store, which continue 3544 // the example given above.) 3545 // 3546 // When the associated Allocate is macro-expanded, the InitializeNode 3547 // may be rewritten to optimize collected stores. A ClearArrayNode 3548 // may also be created at that point to represent any required zeroing. 3549 // The InitializeNode is then marked 'complete', prohibiting further 3550 // capturing of nearby memory operations. 3551 // 3552 // During macro-expansion, all captured initializations which store 3553 // constant values of 32 bits or smaller are coalesced (if advantageous) 3554 // into larger 'tiles' 32 or 64 bits. This allows an object to be 3555 // initialized in fewer memory operations. Memory words which are 3556 // covered by neither tiles nor non-constant stores are pre-zeroed 3557 // by explicit stores of zero. (The code shape happens to do all 3558 // zeroing first, then all other stores, with both sequences occurring 3559 // in order of ascending offsets.) 3560 // 3561 // Alternatively, code may be inserted between an AllocateNode and its 3562 // InitializeNode, to perform arbitrary initialization of the new object. 3563 // E.g., the object copying intrinsics insert complex data transfers here. 3564 // The initialization must then be marked as 'complete' disable the 3565 // built-in zeroing semantics and the collection of initializing stores. 3566 // 3567 // While an InitializeNode is incomplete, reads from the memory state 3568 // produced by it are optimizable if they match the control edge and 3569 // new oop address associated with the allocation/initialization. 3570 // They return a stored value (if the offset matches) or else zero. 3571 // A write to the memory state, if it matches control and address, 3572 // and if it is to a constant offset, may be 'captured' by the 3573 // InitializeNode. It is cloned as a raw memory operation and rewired 3574 // inside the initialization, to the raw oop produced by the allocation. 3575 // Operations on addresses which are provably distinct (e.g., to 3576 // other AllocateNodes) are allowed to bypass the initialization. 3577 // 3578 // The effect of all this is to consolidate object initialization 3579 // (both arrays and non-arrays, both piecewise and bulk) into a 3580 // single location, where it can be optimized as a unit. 3581 // 3582 // Only stores with an offset less than TrackedInitializationLimit words 3583 // will be considered for capture by an InitializeNode. This puts a 3584 // reasonable limit on the complexity of optimized initializations. 3585 3586 //---------------------------InitializeNode------------------------------------ 3587 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3588 : MemBarNode(C, adr_type, rawoop), 3589 _is_complete(Incomplete), _does_not_escape(false) 3590 { 3591 init_class_id(Class_Initialize); 3592 3593 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3594 assert(in(RawAddress) == rawoop, "proper init"); 3595 // Note: allocation() can be NULL, for secondary initialization barriers 3596 } 3597 3598 // Since this node is not matched, it will be processed by the 3599 // register allocator. Declare that there are no constraints 3600 // on the allocation of the RawAddress edge. 3601 const RegMask &InitializeNode::in_RegMask(uint idx) const { 3602 // This edge should be set to top, by the set_complete. But be conservative. 3603 if (idx == InitializeNode::RawAddress) 3604 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3605 return RegMask::Empty; 3606 } 3607 3608 Node* InitializeNode::memory(uint alias_idx) { 3609 Node* mem = in(Memory); 3610 if (mem->is_MergeMem()) { 3611 return mem->as_MergeMem()->memory_at(alias_idx); 3612 } else { 3613 // incoming raw memory is not split 3614 return mem; 3615 } 3616 } 3617 3618 bool InitializeNode::is_non_zero() { 3619 if (is_complete()) return false; 3620 remove_extra_zeroes(); 3621 return (req() > RawStores); 3622 } 3623 3624 void InitializeNode::set_complete(PhaseGVN* phase) { 3625 assert(!is_complete(), "caller responsibility"); 3626 _is_complete = Complete; 3627 3628 // After this node is complete, it contains a bunch of 3629 // raw-memory initializations. There is no need for 3630 // it to have anything to do with non-raw memory effects. 3631 // Therefore, tell all non-raw users to re-optimize themselves, 3632 // after skipping the memory effects of this initialization. 3633 PhaseIterGVN* igvn = phase->is_IterGVN(); 3634 if (igvn) igvn->add_users_to_worklist(this); 3635 } 3636 3637 // convenience function 3638 // return false if the init contains any stores already 3639 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3640 InitializeNode* init = initialization(); 3641 if (init == NULL || init->is_complete()) { 3642 return false; 3643 } 3644 init->remove_extra_zeroes(); 3645 // for now, if this allocation has already collected any inits, bail: 3646 if (init->is_non_zero()) return false; 3647 init->set_complete(phase); 3648 return true; 3649 } 3650 3651 void InitializeNode::remove_extra_zeroes() { 3652 if (req() == RawStores) return; 3653 Node* zmem = zero_memory(); 3654 uint fill = RawStores; 3655 for (uint i = fill; i < req(); i++) { 3656 Node* n = in(i); 3657 if (n->is_top() || n == zmem) continue; // skip 3658 if (fill < i) set_req(fill, n); // compact 3659 ++fill; 3660 } 3661 // delete any empty spaces created: 3662 while (fill < req()) { 3663 del_req(fill); 3664 } 3665 } 3666 3667 // Helper for remembering which stores go with which offsets. 3668 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3669 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3670 intptr_t offset = -1; 3671 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3672 phase, offset); 3673 if (base == NULL) return -1; // something is dead, 3674 if (offset < 0) return -1; // dead, dead 3675 return offset; 3676 } 3677 3678 // Helper for proving that an initialization expression is 3679 // "simple enough" to be folded into an object initialization. 3680 // Attempts to prove that a store's initial value 'n' can be captured 3681 // within the initialization without creating a vicious cycle, such as: 3682 // { Foo p = new Foo(); p.next = p; } 3683 // True for constants and parameters and small combinations thereof. 3684 bool InitializeNode::detect_init_independence(Node* n, int& count) { 3685 if (n == NULL) return true; // (can this really happen?) 3686 if (n->is_Proj()) n = n->in(0); 3687 if (n == this) return false; // found a cycle 3688 if (n->is_Con()) return true; 3689 if (n->is_Start()) return true; // params, etc., are OK 3690 if (n->is_Root()) return true; // even better 3691 3692 Node* ctl = n->in(0); 3693 if (ctl != NULL && !ctl->is_top()) { 3694 if (ctl->is_Proj()) ctl = ctl->in(0); 3695 if (ctl == this) return false; 3696 3697 // If we already know that the enclosing memory op is pinned right after 3698 // the init, then any control flow that the store has picked up 3699 // must have preceded the init, or else be equal to the init. 3700 // Even after loop optimizations (which might change control edges) 3701 // a store is never pinned *before* the availability of its inputs. 3702 if (!MemNode::all_controls_dominate(n, this)) 3703 return false; // failed to prove a good control 3704 } 3705 3706 // Check data edges for possible dependencies on 'this'. 3707 if ((count += 1) > 20) return false; // complexity limit 3708 for (uint i = 1; i < n->req(); i++) { 3709 Node* m = n->in(i); 3710 if (m == NULL || m == n || m->is_top()) continue; 3711 uint first_i = n->find_edge(m); 3712 if (i != first_i) continue; // process duplicate edge just once 3713 if (!detect_init_independence(m, count)) { 3714 return false; 3715 } 3716 } 3717 3718 return true; 3719 } 3720 3721 // Here are all the checks a Store must pass before it can be moved into 3722 // an initialization. Returns zero if a check fails. 3723 // On success, returns the (constant) offset to which the store applies, 3724 // within the initialized memory. 3725 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) { 3726 const int FAIL = 0; 3727 if (st->req() != MemNode::ValueIn + 1) 3728 return FAIL; // an inscrutable StoreNode (card mark?) 3729 Node* ctl = st->in(MemNode::Control); 3730 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3731 return FAIL; // must be unconditional after the initialization 3732 Node* mem = st->in(MemNode::Memory); 3733 if (!(mem->is_Proj() && mem->in(0) == this)) 3734 return FAIL; // must not be preceded by other stores 3735 Node* adr = st->in(MemNode::Address); 3736 intptr_t offset; 3737 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3738 if (alloc == NULL) 3739 return FAIL; // inscrutable address 3740 if (alloc != allocation()) 3741 return FAIL; // wrong allocation! (store needs to float up) 3742 int size_in_bytes = st->memory_size(); 3743 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) { 3744 return FAIL; // mismatched access 3745 } 3746 Node* val = st->in(MemNode::ValueIn); 3747 int complexity_count = 0; 3748 if (!detect_init_independence(val, complexity_count)) 3749 return FAIL; // stored value must be 'simple enough' 3750 3751 // The Store can be captured only if nothing after the allocation 3752 // and before the Store is using the memory location that the store 3753 // overwrites. 3754 bool failed = false; 3755 // If is_complete_with_arraycopy() is true the shape of the graph is 3756 // well defined and is safe so no need for extra checks. 3757 if (!is_complete_with_arraycopy()) { 3758 // We are going to look at each use of the memory state following 3759 // the allocation to make sure nothing reads the memory that the 3760 // Store writes. 3761 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3762 int alias_idx = phase->C->get_alias_index(t_adr); 3763 ResourceMark rm; 3764 Unique_Node_List mems; 3765 mems.push(mem); 3766 Node* unique_merge = NULL; 3767 for (uint next = 0; next < mems.size(); ++next) { 3768 Node *m = mems.at(next); 3769 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3770 Node *n = m->fast_out(j); 3771 if (n->outcnt() == 0) { 3772 continue; 3773 } 3774 if (n == st) { 3775 continue; 3776 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3777 // If the control of this use is different from the control 3778 // of the Store which is right after the InitializeNode then 3779 // this node cannot be between the InitializeNode and the 3780 // Store. 3781 continue; 3782 } else if (n->is_MergeMem()) { 3783 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3784 // We can hit a MergeMemNode (that will likely go away 3785 // later) that is a direct use of the memory state 3786 // following the InitializeNode on the same slice as the 3787 // store node that we'd like to capture. We need to check 3788 // the uses of the MergeMemNode. 3789 mems.push(n); 3790 } 3791 } else if (n->is_Mem()) { 3792 Node* other_adr = n->in(MemNode::Address); 3793 if (other_adr == adr) { 3794 failed = true; 3795 break; 3796 } else { 3797 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3798 if (other_t_adr != NULL) { 3799 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3800 if (other_alias_idx == alias_idx) { 3801 // A load from the same memory slice as the store right 3802 // after the InitializeNode. We check the control of the 3803 // object/array that is loaded from. If it's the same as 3804 // the store control then we cannot capture the store. 3805 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3806 Node* base = other_adr; 3807 assert(base->is_AddP(), "should be addp but is %s", base->Name()); 3808 base = base->in(AddPNode::Base); 3809 if (base != NULL) { 3810 base = base->uncast(); 3811 if (base->is_Proj() && base->in(0) == alloc) { 3812 failed = true; 3813 break; 3814 } 3815 } 3816 } 3817 } 3818 } 3819 } else { 3820 failed = true; 3821 break; 3822 } 3823 } 3824 } 3825 } 3826 if (failed) { 3827 if (!can_reshape) { 3828 // We decided we couldn't capture the store during parsing. We 3829 // should try again during the next IGVN once the graph is 3830 // cleaner. 3831 phase->C->record_for_igvn(st); 3832 } 3833 return FAIL; 3834 } 3835 3836 return offset; // success 3837 } 3838 3839 // Find the captured store in(i) which corresponds to the range 3840 // [start..start+size) in the initialized object. 3841 // If there is one, return its index i. If there isn't, return the 3842 // negative of the index where it should be inserted. 3843 // Return 0 if the queried range overlaps an initialization boundary 3844 // or if dead code is encountered. 3845 // If size_in_bytes is zero, do not bother with overlap checks. 3846 int InitializeNode::captured_store_insertion_point(intptr_t start, 3847 int size_in_bytes, 3848 PhaseTransform* phase) { 3849 const int FAIL = 0, MAX_STORE = BytesPerLong; 3850 3851 if (is_complete()) 3852 return FAIL; // arraycopy got here first; punt 3853 3854 assert(allocation() != NULL, "must be present"); 3855 3856 // no negatives, no header fields: 3857 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3858 3859 // after a certain size, we bail out on tracking all the stores: 3860 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3861 if (start >= ti_limit) return FAIL; 3862 3863 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3864 if (i >= limit) return -(int)i; // not found; here is where to put it 3865 3866 Node* st = in(i); 3867 intptr_t st_off = get_store_offset(st, phase); 3868 if (st_off < 0) { 3869 if (st != zero_memory()) { 3870 return FAIL; // bail out if there is dead garbage 3871 } 3872 } else if (st_off > start) { 3873 // ...we are done, since stores are ordered 3874 if (st_off < start + size_in_bytes) { 3875 return FAIL; // the next store overlaps 3876 } 3877 return -(int)i; // not found; here is where to put it 3878 } else if (st_off < start) { 3879 if (size_in_bytes != 0 && 3880 start < st_off + MAX_STORE && 3881 start < st_off + st->as_Store()->memory_size()) { 3882 return FAIL; // the previous store overlaps 3883 } 3884 } else { 3885 if (size_in_bytes != 0 && 3886 st->as_Store()->memory_size() != size_in_bytes) { 3887 return FAIL; // mismatched store size 3888 } 3889 return i; 3890 } 3891 3892 ++i; 3893 } 3894 } 3895 3896 // Look for a captured store which initializes at the offset 'start' 3897 // with the given size. If there is no such store, and no other 3898 // initialization interferes, then return zero_memory (the memory 3899 // projection of the AllocateNode). 3900 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3901 PhaseTransform* phase) { 3902 assert(stores_are_sane(phase), ""); 3903 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3904 if (i == 0) { 3905 return NULL; // something is dead 3906 } else if (i < 0) { 3907 return zero_memory(); // just primordial zero bits here 3908 } else { 3909 Node* st = in(i); // here is the store at this position 3910 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3911 return st; 3912 } 3913 } 3914 3915 // Create, as a raw pointer, an address within my new object at 'offset'. 3916 Node* InitializeNode::make_raw_address(intptr_t offset, 3917 PhaseTransform* phase) { 3918 Node* addr = in(RawAddress); 3919 if (offset != 0) { 3920 Compile* C = phase->C; 3921 addr = phase->transform( new AddPNode(C->top(), addr, 3922 phase->MakeConX(offset)) ); 3923 } 3924 return addr; 3925 } 3926 3927 // Clone the given store, converting it into a raw store 3928 // initializing a field or element of my new object. 3929 // Caller is responsible for retiring the original store, 3930 // with subsume_node or the like. 3931 // 3932 // From the example above InitializeNode::InitializeNode, 3933 // here are the old stores to be captured: 3934 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3935 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3936 // 3937 // Here is the changed code; note the extra edges on init: 3938 // alloc = (Allocate ...) 3939 // rawoop = alloc.RawAddress 3940 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3941 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3942 // init = (Initialize alloc.Control alloc.Memory rawoop 3943 // rawstore1 rawstore2) 3944 // 3945 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3946 PhaseTransform* phase, bool can_reshape) { 3947 assert(stores_are_sane(phase), ""); 3948 3949 if (start < 0) return NULL; 3950 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3951 3952 Compile* C = phase->C; 3953 int size_in_bytes = st->memory_size(); 3954 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3955 if (i == 0) return NULL; // bail out 3956 Node* prev_mem = NULL; // raw memory for the captured store 3957 if (i > 0) { 3958 prev_mem = in(i); // there is a pre-existing store under this one 3959 set_req(i, C->top()); // temporarily disconnect it 3960 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3961 } else { 3962 i = -i; // no pre-existing store 3963 prev_mem = zero_memory(); // a slice of the newly allocated object 3964 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3965 set_req(--i, C->top()); // reuse this edge; it has been folded away 3966 else 3967 ins_req(i, C->top()); // build a new edge 3968 } 3969 Node* new_st = st->clone(); 3970 new_st->set_req(MemNode::Control, in(Control)); 3971 new_st->set_req(MemNode::Memory, prev_mem); 3972 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3973 new_st = phase->transform(new_st); 3974 3975 // At this point, new_st might have swallowed a pre-existing store 3976 // at the same offset, or perhaps new_st might have disappeared, 3977 // if it redundantly stored the same value (or zero to fresh memory). 3978 3979 // In any case, wire it in: 3980 phase->igvn_rehash_node_delayed(this); 3981 set_req(i, new_st); 3982 3983 // The caller may now kill the old guy. 3984 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3985 assert(check_st == new_st || check_st == NULL, "must be findable"); 3986 assert(!is_complete(), ""); 3987 return new_st; 3988 } 3989 3990 static bool store_constant(jlong* tiles, int num_tiles, 3991 intptr_t st_off, int st_size, 3992 jlong con) { 3993 if ((st_off & (st_size-1)) != 0) 3994 return false; // strange store offset (assume size==2**N) 3995 address addr = (address)tiles + st_off; 3996 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3997 switch (st_size) { 3998 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3999 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 4000 case sizeof(jint): *(jint*) addr = (jint) con; break; 4001 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 4002 default: return false; // strange store size (detect size!=2**N here) 4003 } 4004 return true; // return success to caller 4005 } 4006 4007 // Coalesce subword constants into int constants and possibly 4008 // into long constants. The goal, if the CPU permits, 4009 // is to initialize the object with a small number of 64-bit tiles. 4010 // Also, convert floating-point constants to bit patterns. 4011 // Non-constants are not relevant to this pass. 4012 // 4013 // In terms of the running example on InitializeNode::InitializeNode 4014 // and InitializeNode::capture_store, here is the transformation 4015 // of rawstore1 and rawstore2 into rawstore12: 4016 // alloc = (Allocate ...) 4017 // rawoop = alloc.RawAddress 4018 // tile12 = 0x00010002 4019 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 4020 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 4021 // 4022 void 4023 InitializeNode::coalesce_subword_stores(intptr_t header_size, 4024 Node* size_in_bytes, 4025 PhaseGVN* phase) { 4026 Compile* C = phase->C; 4027 4028 assert(stores_are_sane(phase), ""); 4029 // Note: After this pass, they are not completely sane, 4030 // since there may be some overlaps. 4031 4032 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 4033 4034 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 4035 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 4036 size_limit = MIN2(size_limit, ti_limit); 4037 size_limit = align_up(size_limit, BytesPerLong); 4038 int num_tiles = size_limit / BytesPerLong; 4039 4040 // allocate space for the tile map: 4041 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 4042 jlong tiles_buf[small_len]; 4043 Node* nodes_buf[small_len]; 4044 jlong inits_buf[small_len]; 4045 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 4046 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 4047 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 4048 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 4049 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 4050 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 4051 // tiles: exact bitwise model of all primitive constants 4052 // nodes: last constant-storing node subsumed into the tiles model 4053 // inits: which bytes (in each tile) are touched by any initializations 4054 4055 //// Pass A: Fill in the tile model with any relevant stores. 4056 4057 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 4058 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 4059 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 4060 Node* zmem = zero_memory(); // initially zero memory state 4061 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 4062 Node* st = in(i); 4063 intptr_t st_off = get_store_offset(st, phase); 4064 4065 // Figure out the store's offset and constant value: 4066 if (st_off < header_size) continue; //skip (ignore header) 4067 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 4068 int st_size = st->as_Store()->memory_size(); 4069 if (st_off + st_size > size_limit) break; 4070 4071 // Record which bytes are touched, whether by constant or not. 4072 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 4073 continue; // skip (strange store size) 4074 4075 const Type* val = phase->type(st->in(MemNode::ValueIn)); 4076 if (!val->singleton()) continue; //skip (non-con store) 4077 BasicType type = val->basic_type(); 4078 4079 jlong con = 0; 4080 switch (type) { 4081 case T_INT: con = val->is_int()->get_con(); break; 4082 case T_LONG: con = val->is_long()->get_con(); break; 4083 case T_FLOAT: con = jint_cast(val->getf()); break; 4084 case T_DOUBLE: con = jlong_cast(val->getd()); break; 4085 default: continue; //skip (odd store type) 4086 } 4087 4088 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 4089 st->Opcode() == Op_StoreL) { 4090 continue; // This StoreL is already optimal. 4091 } 4092 4093 // Store down the constant. 4094 store_constant(tiles, num_tiles, st_off, st_size, con); 4095 4096 intptr_t j = st_off >> LogBytesPerLong; 4097 4098 if (type == T_INT && st_size == BytesPerInt 4099 && (st_off & BytesPerInt) == BytesPerInt) { 4100 jlong lcon = tiles[j]; 4101 if (!Matcher::isSimpleConstant64(lcon) && 4102 st->Opcode() == Op_StoreI) { 4103 // This StoreI is already optimal by itself. 4104 jint* intcon = (jint*) &tiles[j]; 4105 intcon[1] = 0; // undo the store_constant() 4106 4107 // If the previous store is also optimal by itself, back up and 4108 // undo the action of the previous loop iteration... if we can. 4109 // But if we can't, just let the previous half take care of itself. 4110 st = nodes[j]; 4111 st_off -= BytesPerInt; 4112 con = intcon[0]; 4113 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 4114 assert(st_off >= header_size, "still ignoring header"); 4115 assert(get_store_offset(st, phase) == st_off, "must be"); 4116 assert(in(i-1) == zmem, "must be"); 4117 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 4118 assert(con == tcon->is_int()->get_con(), "must be"); 4119 // Undo the effects of the previous loop trip, which swallowed st: 4120 intcon[0] = 0; // undo store_constant() 4121 set_req(i-1, st); // undo set_req(i, zmem) 4122 nodes[j] = NULL; // undo nodes[j] = st 4123 --old_subword; // undo ++old_subword 4124 } 4125 continue; // This StoreI is already optimal. 4126 } 4127 } 4128 4129 // This store is not needed. 4130 set_req(i, zmem); 4131 nodes[j] = st; // record for the moment 4132 if (st_size < BytesPerLong) // something has changed 4133 ++old_subword; // includes int/float, but who's counting... 4134 else ++old_long; 4135 } 4136 4137 if ((old_subword + old_long) == 0) 4138 return; // nothing more to do 4139 4140 //// Pass B: Convert any non-zero tiles into optimal constant stores. 4141 // Be sure to insert them before overlapping non-constant stores. 4142 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 4143 for (int j = 0; j < num_tiles; j++) { 4144 jlong con = tiles[j]; 4145 jlong init = inits[j]; 4146 if (con == 0) continue; 4147 jint con0, con1; // split the constant, address-wise 4148 jint init0, init1; // split the init map, address-wise 4149 { union { jlong con; jint intcon[2]; } u; 4150 u.con = con; 4151 con0 = u.intcon[0]; 4152 con1 = u.intcon[1]; 4153 u.con = init; 4154 init0 = u.intcon[0]; 4155 init1 = u.intcon[1]; 4156 } 4157 4158 Node* old = nodes[j]; 4159 assert(old != NULL, "need the prior store"); 4160 intptr_t offset = (j * BytesPerLong); 4161 4162 bool split = !Matcher::isSimpleConstant64(con); 4163 4164 if (offset < header_size) { 4165 assert(offset + BytesPerInt >= header_size, "second int counts"); 4166 assert(*(jint*)&tiles[j] == 0, "junk in header"); 4167 split = true; // only the second word counts 4168 // Example: int a[] = { 42 ... } 4169 } else if (con0 == 0 && init0 == -1) { 4170 split = true; // first word is covered by full inits 4171 // Example: int a[] = { ... foo(), 42 ... } 4172 } else if (con1 == 0 && init1 == -1) { 4173 split = true; // second word is covered by full inits 4174 // Example: int a[] = { ... 42, foo() ... } 4175 } 4176 4177 // Here's a case where init0 is neither 0 nor -1: 4178 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 4179 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 4180 // In this case the tile is not split; it is (jlong)42. 4181 // The big tile is stored down, and then the foo() value is inserted. 4182 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 4183 4184 Node* ctl = old->in(MemNode::Control); 4185 Node* adr = make_raw_address(offset, phase); 4186 const TypePtr* atp = TypeRawPtr::BOTTOM; 4187 4188 // One or two coalesced stores to plop down. 4189 Node* st[2]; 4190 intptr_t off[2]; 4191 int nst = 0; 4192 if (!split) { 4193 ++new_long; 4194 off[nst] = offset; 4195 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4196 phase->longcon(con), T_LONG, MemNode::unordered); 4197 } else { 4198 // Omit either if it is a zero. 4199 if (con0 != 0) { 4200 ++new_int; 4201 off[nst] = offset; 4202 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4203 phase->intcon(con0), T_INT, MemNode::unordered); 4204 } 4205 if (con1 != 0) { 4206 ++new_int; 4207 offset += BytesPerInt; 4208 adr = make_raw_address(offset, phase); 4209 off[nst] = offset; 4210 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4211 phase->intcon(con1), T_INT, MemNode::unordered); 4212 } 4213 } 4214 4215 // Insert second store first, then the first before the second. 4216 // Insert each one just before any overlapping non-constant stores. 4217 while (nst > 0) { 4218 Node* st1 = st[--nst]; 4219 C->copy_node_notes_to(st1, old); 4220 st1 = phase->transform(st1); 4221 offset = off[nst]; 4222 assert(offset >= header_size, "do not smash header"); 4223 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 4224 guarantee(ins_idx != 0, "must re-insert constant store"); 4225 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 4226 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 4227 set_req(--ins_idx, st1); 4228 else 4229 ins_req(ins_idx, st1); 4230 } 4231 } 4232 4233 if (PrintCompilation && WizardMode) 4234 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 4235 old_subword, old_long, new_int, new_long); 4236 if (C->log() != NULL) 4237 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 4238 old_subword, old_long, new_int, new_long); 4239 4240 // Clean up any remaining occurrences of zmem: 4241 remove_extra_zeroes(); 4242 } 4243 4244 // Explore forward from in(start) to find the first fully initialized 4245 // word, and return its offset. Skip groups of subword stores which 4246 // together initialize full words. If in(start) is itself part of a 4247 // fully initialized word, return the offset of in(start). If there 4248 // are no following full-word stores, or if something is fishy, return 4249 // a negative value. 4250 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 4251 int int_map = 0; 4252 intptr_t int_map_off = 0; 4253 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 4254 4255 for (uint i = start, limit = req(); i < limit; i++) { 4256 Node* st = in(i); 4257 4258 intptr_t st_off = get_store_offset(st, phase); 4259 if (st_off < 0) break; // return conservative answer 4260 4261 int st_size = st->as_Store()->memory_size(); 4262 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 4263 return st_off; // we found a complete word init 4264 } 4265 4266 // update the map: 4267 4268 intptr_t this_int_off = align_down(st_off, BytesPerInt); 4269 if (this_int_off != int_map_off) { 4270 // reset the map: 4271 int_map = 0; 4272 int_map_off = this_int_off; 4273 } 4274 4275 int subword_off = st_off - this_int_off; 4276 int_map |= right_n_bits(st_size) << subword_off; 4277 if ((int_map & FULL_MAP) == FULL_MAP) { 4278 return this_int_off; // we found a complete word init 4279 } 4280 4281 // Did this store hit or cross the word boundary? 4282 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt); 4283 if (next_int_off == this_int_off + BytesPerInt) { 4284 // We passed the current int, without fully initializing it. 4285 int_map_off = next_int_off; 4286 int_map >>= BytesPerInt; 4287 } else if (next_int_off > this_int_off + BytesPerInt) { 4288 // We passed the current and next int. 4289 return this_int_off + BytesPerInt; 4290 } 4291 } 4292 4293 return -1; 4294 } 4295 4296 4297 // Called when the associated AllocateNode is expanded into CFG. 4298 // At this point, we may perform additional optimizations. 4299 // Linearize the stores by ascending offset, to make memory 4300 // activity as coherent as possible. 4301 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 4302 intptr_t header_size, 4303 Node* size_in_bytes, 4304 PhaseGVN* phase) { 4305 assert(!is_complete(), "not already complete"); 4306 assert(stores_are_sane(phase), ""); 4307 assert(allocation() != NULL, "must be present"); 4308 4309 remove_extra_zeroes(); 4310 4311 if (ReduceFieldZeroing || ReduceBulkZeroing) 4312 // reduce instruction count for common initialization patterns 4313 coalesce_subword_stores(header_size, size_in_bytes, phase); 4314 4315 Node* zmem = zero_memory(); // initially zero memory state 4316 Node* inits = zmem; // accumulating a linearized chain of inits 4317 #ifdef ASSERT 4318 intptr_t first_offset = allocation()->minimum_header_size(); 4319 intptr_t last_init_off = first_offset; // previous init offset 4320 intptr_t last_init_end = first_offset; // previous init offset+size 4321 intptr_t last_tile_end = first_offset; // previous tile offset+size 4322 #endif 4323 intptr_t zeroes_done = header_size; 4324 4325 bool do_zeroing = true; // we might give up if inits are very sparse 4326 int big_init_gaps = 0; // how many large gaps have we seen? 4327 4328 if (UseTLAB && ZeroTLAB) do_zeroing = false; 4329 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 4330 4331 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 4332 Node* st = in(i); 4333 intptr_t st_off = get_store_offset(st, phase); 4334 if (st_off < 0) 4335 break; // unknown junk in the inits 4336 if (st->in(MemNode::Memory) != zmem) 4337 break; // complicated store chains somehow in list 4338 4339 int st_size = st->as_Store()->memory_size(); 4340 intptr_t next_init_off = st_off + st_size; 4341 4342 if (do_zeroing && zeroes_done < next_init_off) { 4343 // See if this store needs a zero before it or under it. 4344 intptr_t zeroes_needed = st_off; 4345 4346 if (st_size < BytesPerInt) { 4347 // Look for subword stores which only partially initialize words. 4348 // If we find some, we must lay down some word-level zeroes first, 4349 // underneath the subword stores. 4350 // 4351 // Examples: 4352 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 4353 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 4354 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 4355 // 4356 // Note: coalesce_subword_stores may have already done this, 4357 // if it was prompted by constant non-zero subword initializers. 4358 // But this case can still arise with non-constant stores. 4359 4360 intptr_t next_full_store = find_next_fullword_store(i, phase); 4361 4362 // In the examples above: 4363 // in(i) p q r s x y z 4364 // st_off 12 13 14 15 12 13 14 4365 // st_size 1 1 1 1 1 1 1 4366 // next_full_s. 12 16 16 16 16 16 16 4367 // z's_done 12 16 16 16 12 16 12 4368 // z's_needed 12 16 16 16 16 16 16 4369 // zsize 0 0 0 0 4 0 4 4370 if (next_full_store < 0) { 4371 // Conservative tack: Zero to end of current word. 4372 zeroes_needed = align_up(zeroes_needed, BytesPerInt); 4373 } else { 4374 // Zero to beginning of next fully initialized word. 4375 // Or, don't zero at all, if we are already in that word. 4376 assert(next_full_store >= zeroes_needed, "must go forward"); 4377 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 4378 zeroes_needed = next_full_store; 4379 } 4380 } 4381 4382 if (zeroes_needed > zeroes_done) { 4383 intptr_t zsize = zeroes_needed - zeroes_done; 4384 // Do some incremental zeroing on rawmem, in parallel with inits. 4385 zeroes_done = align_down(zeroes_done, BytesPerInt); 4386 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4387 allocation()->in(AllocateNode::DefaultValue), 4388 allocation()->in(AllocateNode::RawDefaultValue), 4389 zeroes_done, zeroes_needed, 4390 phase); 4391 zeroes_done = zeroes_needed; 4392 if (zsize > InitArrayShortSize && ++big_init_gaps > 2) 4393 do_zeroing = false; // leave the hole, next time 4394 } 4395 } 4396 4397 // Collect the store and move on: 4398 st->set_req(MemNode::Memory, inits); 4399 inits = st; // put it on the linearized chain 4400 set_req(i, zmem); // unhook from previous position 4401 4402 if (zeroes_done == st_off) 4403 zeroes_done = next_init_off; 4404 4405 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 4406 4407 #ifdef ASSERT 4408 // Various order invariants. Weaker than stores_are_sane because 4409 // a large constant tile can be filled in by smaller non-constant stores. 4410 assert(st_off >= last_init_off, "inits do not reverse"); 4411 last_init_off = st_off; 4412 const Type* val = NULL; 4413 if (st_size >= BytesPerInt && 4414 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 4415 (int)val->basic_type() < (int)T_OBJECT) { 4416 assert(st_off >= last_tile_end, "tiles do not overlap"); 4417 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 4418 last_tile_end = MAX2(last_tile_end, next_init_off); 4419 } else { 4420 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong); 4421 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 4422 assert(st_off >= last_init_end, "inits do not overlap"); 4423 last_init_end = next_init_off; // it's a non-tile 4424 } 4425 #endif //ASSERT 4426 } 4427 4428 remove_extra_zeroes(); // clear out all the zmems left over 4429 add_req(inits); 4430 4431 if (!(UseTLAB && ZeroTLAB)) { 4432 // If anything remains to be zeroed, zero it all now. 4433 zeroes_done = align_down(zeroes_done, BytesPerInt); 4434 // if it is the last unused 4 bytes of an instance, forget about it 4435 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 4436 if (zeroes_done + BytesPerLong >= size_limit) { 4437 AllocateNode* alloc = allocation(); 4438 assert(alloc != NULL, "must be present"); 4439 if (alloc != NULL && alloc->Opcode() == Op_Allocate) { 4440 Node* klass_node = alloc->in(AllocateNode::KlassNode); 4441 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 4442 if (zeroes_done == k->layout_helper()) 4443 zeroes_done = size_limit; 4444 } 4445 } 4446 if (zeroes_done < size_limit) { 4447 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4448 allocation()->in(AllocateNode::DefaultValue), 4449 allocation()->in(AllocateNode::RawDefaultValue), 4450 zeroes_done, size_in_bytes, phase); 4451 } 4452 } 4453 4454 set_complete(phase); 4455 return rawmem; 4456 } 4457 4458 4459 #ifdef ASSERT 4460 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 4461 if (is_complete()) 4462 return true; // stores could be anything at this point 4463 assert(allocation() != NULL, "must be present"); 4464 intptr_t last_off = allocation()->minimum_header_size(); 4465 for (uint i = InitializeNode::RawStores; i < req(); i++) { 4466 Node* st = in(i); 4467 intptr_t st_off = get_store_offset(st, phase); 4468 if (st_off < 0) continue; // ignore dead garbage 4469 if (last_off > st_off) { 4470 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 4471 this->dump(2); 4472 assert(false, "ascending store offsets"); 4473 return false; 4474 } 4475 last_off = st_off + st->as_Store()->memory_size(); 4476 } 4477 return true; 4478 } 4479 #endif //ASSERT 4480 4481 4482 4483 4484 //============================MergeMemNode===================================== 4485 // 4486 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4487 // contributing store or call operations. Each contributor provides the memory 4488 // state for a particular "alias type" (see Compile::alias_type). For example, 4489 // if a MergeMem has an input X for alias category #6, then any memory reference 4490 // to alias category #6 may use X as its memory state input, as an exact equivalent 4491 // to using the MergeMem as a whole. 4492 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4493 // 4494 // (Here, the <N> notation gives the index of the relevant adr_type.) 4495 // 4496 // In one special case (and more cases in the future), alias categories overlap. 4497 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4498 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 4499 // it is exactly equivalent to that state W: 4500 // MergeMem(<Bot>: W) <==> W 4501 // 4502 // Usually, the merge has more than one input. In that case, where inputs 4503 // overlap (i.e., one is Bot), the narrower alias type determines the memory 4504 // state for that type, and the wider alias type (Bot) fills in everywhere else: 4505 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4506 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4507 // 4508 // A merge can take a "wide" memory state as one of its narrow inputs. 4509 // This simply means that the merge observes out only the relevant parts of 4510 // the wide input. That is, wide memory states arriving at narrow merge inputs 4511 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4512 // 4513 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4514 // and that memory slices "leak through": 4515 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4516 // 4517 // But, in such a cascade, repeated memory slices can "block the leak": 4518 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4519 // 4520 // In the last example, Y is not part of the combined memory state of the 4521 // outermost MergeMem. The system must, of course, prevent unschedulable 4522 // memory states from arising, so you can be sure that the state Y is somehow 4523 // a precursor to state Y'. 4524 // 4525 // 4526 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4527 // of each MergeMemNode array are exactly the numerical alias indexes, including 4528 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4529 // Compile::alias_type (and kin) produce and manage these indexes. 4530 // 4531 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4532 // (Note that this provides quick access to the top node inside MergeMem methods, 4533 // without the need to reach out via TLS to Compile::current.) 4534 // 4535 // As a consequence of what was just described, a MergeMem that represents a full 4536 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4537 // containing all alias categories. 4538 // 4539 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4540 // 4541 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4542 // a memory state for the alias type <N>, or else the top node, meaning that 4543 // there is no particular input for that alias type. Note that the length of 4544 // a MergeMem is variable, and may be extended at any time to accommodate new 4545 // memory states at larger alias indexes. When merges grow, they are of course 4546 // filled with "top" in the unused in() positions. 4547 // 4548 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4549 // (Top was chosen because it works smoothly with passes like GCM.) 4550 // 4551 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4552 // the type of random VM bits like TLS references.) Since it is always the 4553 // first non-Bot memory slice, some low-level loops use it to initialize an 4554 // index variable: for (i = AliasIdxRaw; i < req(); i++). 4555 // 4556 // 4557 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4558 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4559 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 4560 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4561 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4562 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4563 // 4564 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4565 // really that different from the other memory inputs. An abbreviation called 4566 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4567 // 4568 // 4569 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4570 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4571 // that "emerges though" the base memory will be marked as excluding the alias types 4572 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 4573 // 4574 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4575 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4576 // 4577 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 4578 // (It is currently unimplemented.) As you can see, the resulting merge is 4579 // actually a disjoint union of memory states, rather than an overlay. 4580 // 4581 4582 //------------------------------MergeMemNode----------------------------------- 4583 Node* MergeMemNode::make_empty_memory() { 4584 Node* empty_memory = (Node*) Compile::current()->top(); 4585 assert(empty_memory->is_top(), "correct sentinel identity"); 4586 return empty_memory; 4587 } 4588 4589 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4590 init_class_id(Class_MergeMem); 4591 // all inputs are nullified in Node::Node(int) 4592 // set_input(0, NULL); // no control input 4593 4594 // Initialize the edges uniformly to top, for starters. 4595 Node* empty_mem = make_empty_memory(); 4596 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4597 init_req(i,empty_mem); 4598 } 4599 assert(empty_memory() == empty_mem, ""); 4600 4601 if( new_base != NULL && new_base->is_MergeMem() ) { 4602 MergeMemNode* mdef = new_base->as_MergeMem(); 4603 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4604 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4605 mms.set_memory(mms.memory2()); 4606 } 4607 assert(base_memory() == mdef->base_memory(), ""); 4608 } else { 4609 set_base_memory(new_base); 4610 } 4611 } 4612 4613 // Make a new, untransformed MergeMem with the same base as 'mem'. 4614 // If mem is itself a MergeMem, populate the result with the same edges. 4615 MergeMemNode* MergeMemNode::make(Node* mem) { 4616 return new MergeMemNode(mem); 4617 } 4618 4619 //------------------------------cmp-------------------------------------------- 4620 uint MergeMemNode::hash() const { return NO_HASH; } 4621 bool MergeMemNode::cmp( const Node &n ) const { 4622 return (&n == this); // Always fail except on self 4623 } 4624 4625 //------------------------------Identity--------------------------------------- 4626 Node* MergeMemNode::Identity(PhaseGVN* phase) { 4627 // Identity if this merge point does not record any interesting memory 4628 // disambiguations. 4629 Node* base_mem = base_memory(); 4630 Node* empty_mem = empty_memory(); 4631 if (base_mem != empty_mem) { // Memory path is not dead? 4632 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4633 Node* mem = in(i); 4634 if (mem != empty_mem && mem != base_mem) { 4635 return this; // Many memory splits; no change 4636 } 4637 } 4638 } 4639 return base_mem; // No memory splits; ID on the one true input 4640 } 4641 4642 //------------------------------Ideal------------------------------------------ 4643 // This method is invoked recursively on chains of MergeMem nodes 4644 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4645 // Remove chain'd MergeMems 4646 // 4647 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4648 // relative to the "in(Bot)". Since we are patching both at the same time, 4649 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4650 // but rewrite each "in(i)" relative to the new "in(Bot)". 4651 Node *progress = NULL; 4652 4653 4654 Node* old_base = base_memory(); 4655 Node* empty_mem = empty_memory(); 4656 if (old_base == empty_mem) 4657 return NULL; // Dead memory path. 4658 4659 MergeMemNode* old_mbase; 4660 if (old_base != NULL && old_base->is_MergeMem()) 4661 old_mbase = old_base->as_MergeMem(); 4662 else 4663 old_mbase = NULL; 4664 Node* new_base = old_base; 4665 4666 // simplify stacked MergeMems in base memory 4667 if (old_mbase) new_base = old_mbase->base_memory(); 4668 4669 // the base memory might contribute new slices beyond my req() 4670 if (old_mbase) grow_to_match(old_mbase); 4671 4672 // Look carefully at the base node if it is a phi. 4673 PhiNode* phi_base; 4674 if (new_base != NULL && new_base->is_Phi()) 4675 phi_base = new_base->as_Phi(); 4676 else 4677 phi_base = NULL; 4678 4679 Node* phi_reg = NULL; 4680 uint phi_len = (uint)-1; 4681 if (phi_base != NULL && !phi_base->is_copy()) { 4682 // do not examine phi if degraded to a copy 4683 phi_reg = phi_base->region(); 4684 phi_len = phi_base->req(); 4685 // see if the phi is unfinished 4686 for (uint i = 1; i < phi_len; i++) { 4687 if (phi_base->in(i) == NULL) { 4688 // incomplete phi; do not look at it yet! 4689 phi_reg = NULL; 4690 phi_len = (uint)-1; 4691 break; 4692 } 4693 } 4694 } 4695 4696 // Note: We do not call verify_sparse on entry, because inputs 4697 // can normalize to the base_memory via subsume_node or similar 4698 // mechanisms. This method repairs that damage. 4699 4700 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4701 4702 // Look at each slice. 4703 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4704 Node* old_in = in(i); 4705 // calculate the old memory value 4706 Node* old_mem = old_in; 4707 if (old_mem == empty_mem) old_mem = old_base; 4708 assert(old_mem == memory_at(i), ""); 4709 4710 // maybe update (reslice) the old memory value 4711 4712 // simplify stacked MergeMems 4713 Node* new_mem = old_mem; 4714 MergeMemNode* old_mmem; 4715 if (old_mem != NULL && old_mem->is_MergeMem()) 4716 old_mmem = old_mem->as_MergeMem(); 4717 else 4718 old_mmem = NULL; 4719 if (old_mmem == this) { 4720 // This can happen if loops break up and safepoints disappear. 4721 // A merge of BotPtr (default) with a RawPtr memory derived from a 4722 // safepoint can be rewritten to a merge of the same BotPtr with 4723 // the BotPtr phi coming into the loop. If that phi disappears 4724 // also, we can end up with a self-loop of the mergemem. 4725 // In general, if loops degenerate and memory effects disappear, 4726 // a mergemem can be left looking at itself. This simply means 4727 // that the mergemem's default should be used, since there is 4728 // no longer any apparent effect on this slice. 4729 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4730 // from start. Update the input to TOP. 4731 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4732 } 4733 else if (old_mmem != NULL) { 4734 new_mem = old_mmem->memory_at(i); 4735 } 4736 // else preceding memory was not a MergeMem 4737 4738 // replace equivalent phis (unfortunately, they do not GVN together) 4739 if (new_mem != NULL && new_mem != new_base && 4740 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4741 if (new_mem->is_Phi()) { 4742 PhiNode* phi_mem = new_mem->as_Phi(); 4743 for (uint i = 1; i < phi_len; i++) { 4744 if (phi_base->in(i) != phi_mem->in(i)) { 4745 phi_mem = NULL; 4746 break; 4747 } 4748 } 4749 if (phi_mem != NULL) { 4750 // equivalent phi nodes; revert to the def 4751 new_mem = new_base; 4752 } 4753 } 4754 } 4755 4756 // maybe store down a new value 4757 Node* new_in = new_mem; 4758 if (new_in == new_base) new_in = empty_mem; 4759 4760 if (new_in != old_in) { 4761 // Warning: Do not combine this "if" with the previous "if" 4762 // A memory slice might have be be rewritten even if it is semantically 4763 // unchanged, if the base_memory value has changed. 4764 set_req(i, new_in); 4765 progress = this; // Report progress 4766 } 4767 } 4768 4769 if (new_base != old_base) { 4770 set_req(Compile::AliasIdxBot, new_base); 4771 // Don't use set_base_memory(new_base), because we need to update du. 4772 assert(base_memory() == new_base, ""); 4773 progress = this; 4774 } 4775 4776 if( base_memory() == this ) { 4777 // a self cycle indicates this memory path is dead 4778 set_req(Compile::AliasIdxBot, empty_mem); 4779 } 4780 4781 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4782 // Recursion must occur after the self cycle check above 4783 if( base_memory()->is_MergeMem() ) { 4784 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4785 Node *m = phase->transform(new_mbase); // Rollup any cycles 4786 if( m != NULL && 4787 (m->is_top() || 4788 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) { 4789 // propagate rollup of dead cycle to self 4790 set_req(Compile::AliasIdxBot, empty_mem); 4791 } 4792 } 4793 4794 if( base_memory() == empty_mem ) { 4795 progress = this; 4796 // Cut inputs during Parse phase only. 4797 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4798 if( !can_reshape ) { 4799 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4800 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4801 } 4802 } 4803 } 4804 4805 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4806 // Check if PhiNode::Ideal's "Split phis through memory merges" 4807 // transform should be attempted. Look for this->phi->this cycle. 4808 uint merge_width = req(); 4809 if (merge_width > Compile::AliasIdxRaw) { 4810 PhiNode* phi = base_memory()->as_Phi(); 4811 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4812 if (phi->in(i) == this) { 4813 phase->is_IterGVN()->_worklist.push(phi); 4814 break; 4815 } 4816 } 4817 } 4818 } 4819 4820 assert(progress || verify_sparse(), "please, no dups of base"); 4821 return progress; 4822 } 4823 4824 //-------------------------set_base_memory------------------------------------- 4825 void MergeMemNode::set_base_memory(Node *new_base) { 4826 Node* empty_mem = empty_memory(); 4827 set_req(Compile::AliasIdxBot, new_base); 4828 assert(memory_at(req()) == new_base, "must set default memory"); 4829 // Clear out other occurrences of new_base: 4830 if (new_base != empty_mem) { 4831 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4832 if (in(i) == new_base) set_req(i, empty_mem); 4833 } 4834 } 4835 } 4836 4837 //------------------------------out_RegMask------------------------------------ 4838 const RegMask &MergeMemNode::out_RegMask() const { 4839 return RegMask::Empty; 4840 } 4841 4842 //------------------------------dump_spec-------------------------------------- 4843 #ifndef PRODUCT 4844 void MergeMemNode::dump_spec(outputStream *st) const { 4845 st->print(" {"); 4846 Node* base_mem = base_memory(); 4847 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4848 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem; 4849 if (mem == base_mem) { st->print(" -"); continue; } 4850 st->print( " N%d:", mem->_idx ); 4851 Compile::current()->get_adr_type(i)->dump_on(st); 4852 } 4853 st->print(" }"); 4854 } 4855 #endif // !PRODUCT 4856 4857 4858 #ifdef ASSERT 4859 static bool might_be_same(Node* a, Node* b) { 4860 if (a == b) return true; 4861 if (!(a->is_Phi() || b->is_Phi())) return false; 4862 // phis shift around during optimization 4863 return true; // pretty stupid... 4864 } 4865 4866 // verify a narrow slice (either incoming or outgoing) 4867 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4868 if (!VerifyAliases) return; // don't bother to verify unless requested 4869 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 4870 if (Node::in_dump()) return; // muzzle asserts when printing 4871 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4872 assert(n != NULL, ""); 4873 // Elide intervening MergeMem's 4874 while (n->is_MergeMem()) { 4875 n = n->as_MergeMem()->memory_at(alias_idx); 4876 } 4877 Compile* C = Compile::current(); 4878 const TypePtr* n_adr_type = n->adr_type(); 4879 if (n == m->empty_memory()) { 4880 // Implicit copy of base_memory() 4881 } else if (n_adr_type != TypePtr::BOTTOM) { 4882 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4883 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4884 } else { 4885 // A few places like make_runtime_call "know" that VM calls are narrow, 4886 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4887 bool expected_wide_mem = false; 4888 if (n == m->base_memory()) { 4889 expected_wide_mem = true; 4890 } else if (alias_idx == Compile::AliasIdxRaw || 4891 n == m->memory_at(Compile::AliasIdxRaw)) { 4892 expected_wide_mem = true; 4893 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4894 // memory can "leak through" calls on channels that 4895 // are write-once. Allow this also. 4896 expected_wide_mem = true; 4897 } 4898 assert(expected_wide_mem, "expected narrow slice replacement"); 4899 } 4900 } 4901 #else // !ASSERT 4902 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4903 #endif 4904 4905 4906 //-----------------------------memory_at--------------------------------------- 4907 Node* MergeMemNode::memory_at(uint alias_idx) const { 4908 assert(alias_idx >= Compile::AliasIdxRaw || 4909 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4910 "must avoid base_memory and AliasIdxTop"); 4911 4912 // Otherwise, it is a narrow slice. 4913 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4914 Compile *C = Compile::current(); 4915 if (is_empty_memory(n)) { 4916 // the array is sparse; empty slots are the "top" node 4917 n = base_memory(); 4918 assert(Node::in_dump() 4919 || n == NULL || n->bottom_type() == Type::TOP 4920 || n->adr_type() == NULL // address is TOP 4921 || n->adr_type() == TypePtr::BOTTOM 4922 || n->adr_type() == TypeRawPtr::BOTTOM 4923 || Compile::current()->AliasLevel() == 0, 4924 "must be a wide memory"); 4925 // AliasLevel == 0 if we are organizing the memory states manually. 4926 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4927 } else { 4928 // make sure the stored slice is sane 4929 #ifdef ASSERT 4930 if (VMError::is_error_reported() || Node::in_dump()) { 4931 } else if (might_be_same(n, base_memory())) { 4932 // Give it a pass: It is a mostly harmless repetition of the base. 4933 // This can arise normally from node subsumption during optimization. 4934 } else { 4935 verify_memory_slice(this, alias_idx, n); 4936 } 4937 #endif 4938 } 4939 return n; 4940 } 4941 4942 //---------------------------set_memory_at------------------------------------- 4943 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4944 verify_memory_slice(this, alias_idx, n); 4945 Node* empty_mem = empty_memory(); 4946 if (n == base_memory()) n = empty_mem; // collapse default 4947 uint need_req = alias_idx+1; 4948 if (req() < need_req) { 4949 if (n == empty_mem) return; // already the default, so do not grow me 4950 // grow the sparse array 4951 do { 4952 add_req(empty_mem); 4953 } while (req() < need_req); 4954 } 4955 set_req( alias_idx, n ); 4956 } 4957 4958 4959 4960 //--------------------------iteration_setup------------------------------------ 4961 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4962 if (other != NULL) { 4963 grow_to_match(other); 4964 // invariant: the finite support of mm2 is within mm->req() 4965 #ifdef ASSERT 4966 for (uint i = req(); i < other->req(); i++) { 4967 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4968 } 4969 #endif 4970 } 4971 // Replace spurious copies of base_memory by top. 4972 Node* base_mem = base_memory(); 4973 if (base_mem != NULL && !base_mem->is_top()) { 4974 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4975 if (in(i) == base_mem) 4976 set_req(i, empty_memory()); 4977 } 4978 } 4979 } 4980 4981 //---------------------------grow_to_match------------------------------------- 4982 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4983 Node* empty_mem = empty_memory(); 4984 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4985 // look for the finite support of the other memory 4986 for (uint i = other->req(); --i >= req(); ) { 4987 if (other->in(i) != empty_mem) { 4988 uint new_len = i+1; 4989 while (req() < new_len) add_req(empty_mem); 4990 break; 4991 } 4992 } 4993 } 4994 4995 //---------------------------verify_sparse------------------------------------- 4996 #ifndef PRODUCT 4997 bool MergeMemNode::verify_sparse() const { 4998 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4999 Node* base_mem = base_memory(); 5000 // The following can happen in degenerate cases, since empty==top. 5001 if (is_empty_memory(base_mem)) return true; 5002 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 5003 assert(in(i) != NULL, "sane slice"); 5004 if (in(i) == base_mem) return false; // should have been the sentinel value! 5005 } 5006 return true; 5007 } 5008 5009 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 5010 Node* n; 5011 n = mm->in(idx); 5012 if (mem == n) return true; // might be empty_memory() 5013 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 5014 if (mem == n) return true; 5015 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 5016 if (mem == n) return true; 5017 if (n == NULL) break; 5018 } 5019 return false; 5020 } 5021 #endif // !PRODUCT