1 /* 2 * Copyright (c) 1997, 2021, 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/javaClasses.hpp" 27 #include "compiler/compileLog.hpp" 28 #include "gc/shared/barrierSet.hpp" 29 #include "gc/shared/c2/barrierSetC2.hpp" 30 #include "gc/shared/tlab_globals.hpp" 31 #include "memory/allocation.inline.hpp" 32 #include "memory/resourceArea.hpp" 33 #include "oops/objArrayKlass.hpp" 34 #include "opto/addnode.hpp" 35 #include "opto/arraycopynode.hpp" 36 #include "opto/cfgnode.hpp" 37 #include "opto/regalloc.hpp" 38 #include "opto/compile.hpp" 39 #include "opto/connode.hpp" 40 #include "opto/convertnode.hpp" 41 #include "opto/loopnode.hpp" 42 #include "opto/machnode.hpp" 43 #include "opto/matcher.hpp" 44 #include "opto/memnode.hpp" 45 #include "opto/mulnode.hpp" 46 #include "opto/narrowptrnode.hpp" 47 #include "opto/phaseX.hpp" 48 #include "opto/regmask.hpp" 49 #include "opto/rootnode.hpp" 50 #include "opto/vectornode.hpp" 51 #include "utilities/align.hpp" 52 #include "utilities/copy.hpp" 53 #include "utilities/macros.hpp" 54 #include "utilities/powerOfTwo.hpp" 55 #include "utilities/vmError.hpp" 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 igvn->_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 igvn->_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(), igvn); 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, "unsafe off-heap access with zero address")); 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 igvn->_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 Node_List nlist; 462 Unique_Node_List dom_list; 463 464 dom_list.push(dom); 465 bool only_dominating_controls = false; 466 467 for (uint next = 0; next < dom_list.size(); next++) { 468 Node* n = dom_list.at(next); 469 if (n == orig_sub) 470 return false; // One of dom's inputs dominated by sub. 471 if (!n->is_CFG() && n->pinned()) { 472 // Check only own control edge for pinned non-control nodes. 473 n = n->find_exact_control(n->in(0)); 474 if (n == NULL || n->is_top()) 475 return false; // Conservative answer for dead code 476 assert(n->is_CFG(), "expecting control"); 477 dom_list.push(n); 478 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 479 only_dominating_controls = true; 480 } else if (n->is_CFG()) { 481 if (n->dominates(sub, nlist)) 482 only_dominating_controls = true; 483 else 484 return false; 485 } else { 486 // First, own control edge. 487 Node* m = n->find_exact_control(n->in(0)); 488 if (m != NULL) { 489 if (m->is_top()) 490 return false; // Conservative answer for dead code 491 dom_list.push(m); 492 } 493 // Now, the rest of edges. 494 uint cnt = n->req(); 495 for (uint i = 1; i < cnt; i++) { 496 m = n->find_exact_control(n->in(i)); 497 if (m == NULL || m->is_top()) 498 continue; 499 dom_list.push(m); 500 } 501 } 502 } 503 return only_dominating_controls; 504 } 505 } 506 507 //---------------------detect_ptr_independence--------------------------------- 508 // Used by MemNode::find_previous_store to prove that two base 509 // pointers are never equal. 510 // The pointers are accompanied by their associated allocations, 511 // if any, which have been previously discovered by the caller. 512 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 513 Node* p2, AllocateNode* a2, 514 PhaseTransform* phase) { 515 // Attempt to prove that these two pointers cannot be aliased. 516 // They may both manifestly be allocations, and they should differ. 517 // Or, if they are not both allocations, they can be distinct constants. 518 // Otherwise, one is an allocation and the other a pre-existing value. 519 if (a1 == NULL && a2 == NULL) { // neither an allocation 520 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 521 } else if (a1 != NULL && a2 != NULL) { // both allocations 522 return (a1 != a2); 523 } else if (a1 != NULL) { // one allocation a1 524 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 525 return all_controls_dominate(p2, a1); 526 } else { //(a2 != NULL) // one allocation a2 527 return all_controls_dominate(p1, a2); 528 } 529 return false; 530 } 531 532 533 // Find an arraycopy ac that produces the memory state represented by parameter mem. 534 // Return ac if 535 // (a) can_see_stored_value=true and ac must have set the value for this load or if 536 // (b) can_see_stored_value=false and ac could have set the value for this load or if 537 // (c) can_see_stored_value=false and ac cannot have set the value for this load. 538 // In case (c) change the parameter mem to the memory input of ac to skip it 539 // when searching stored value. 540 // Otherwise return NULL. 541 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 542 ArrayCopyNode* ac = find_array_copy_clone(phase, ld_alloc, mem); 543 if (ac != NULL) { 544 Node* ld_addp = in(MemNode::Address); 545 Node* src = ac->in(ArrayCopyNode::Src); 546 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr(); 547 548 // This is a load from a cloned array. The corresponding arraycopy ac must 549 // have set the value for the load and we can return ac but only if the load 550 // is known to be within bounds. This is checked below. 551 if (ary_t != NULL && ld_addp->is_AddP()) { 552 Node* ld_offs = ld_addp->in(AddPNode::Offset); 553 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 554 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem); 555 jlong elemsize = type2aelembytes(ary_elem); 556 557 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 558 const TypeInt* sizetype = ary_t->size(); 559 560 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) { 561 // The load is known to be within bounds. It receives its value from ac. 562 return ac; 563 } 564 // The load is known to be out-of-bounds. 565 } 566 // The load could be out-of-bounds. It must not be hoisted but must remain 567 // dependent on the runtime range check. This is achieved by returning NULL. 568 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) { 569 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy(); 570 571 if (ac->is_arraycopy_validated() || 572 ac->is_copyof_validated() || 573 ac->is_copyofrange_validated()) { 574 Node* ld_addp = in(MemNode::Address); 575 if (ld_addp->is_AddP()) { 576 Node* ld_base = ld_addp->in(AddPNode::Address); 577 Node* ld_offs = ld_addp->in(AddPNode::Offset); 578 579 Node* dest = ac->in(ArrayCopyNode::Dest); 580 581 if (dest == ld_base) { 582 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 583 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) { 584 return ac; 585 } 586 if (!can_see_stored_value) { 587 mem = ac->in(TypeFunc::Memory); 588 return ac; 589 } 590 } 591 } 592 } 593 } 594 return NULL; 595 } 596 597 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseTransform* phase, Node* ld_alloc, Node* mem) const { 598 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 599 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 600 if (ld_alloc != NULL) { 601 // Check if there is an array copy for a clone 602 Node* mb = mem->in(0); 603 ArrayCopyNode* ac = NULL; 604 if (mb->in(0) != NULL && mb->in(0)->is_Proj() && 605 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) { 606 ac = mb->in(0)->in(0)->as_ArrayCopy(); 607 } else { 608 // Step over GC barrier when ReduceInitialCardMarks is disabled 609 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 610 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0)); 611 612 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) { 613 ac = control_proj_ac->in(0)->as_ArrayCopy(); 614 } 615 } 616 617 if (ac != NULL && ac->is_clonebasic()) { 618 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase); 619 if (alloc != NULL && alloc == ld_alloc) { 620 return ac; 621 } 622 } 623 } 624 } 625 return NULL; 626 } 627 628 // The logic for reordering loads and stores uses four steps: 629 // (a) Walk carefully past stores and initializations which we 630 // can prove are independent of this load. 631 // (b) Observe that the next memory state makes an exact match 632 // with self (load or store), and locate the relevant store. 633 // (c) Ensure that, if we were to wire self directly to the store, 634 // the optimizer would fold it up somehow. 635 // (d) Do the rewiring, and return, depending on some other part of 636 // the optimizer to fold up the load. 637 // This routine handles steps (a) and (b). Steps (c) and (d) are 638 // specific to loads and stores, so they are handled by the callers. 639 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 640 // 641 Node* MemNode::find_previous_store(PhaseTransform* phase) { 642 Node* ctrl = in(MemNode::Control); 643 Node* adr = in(MemNode::Address); 644 intptr_t offset = 0; 645 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 646 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 647 648 if (offset == Type::OffsetBot) 649 return NULL; // cannot unalias unless there are precise offsets 650 651 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr); 652 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 653 654 intptr_t size_in_bytes = memory_size(); 655 656 Node* mem = in(MemNode::Memory); // start searching here... 657 658 int cnt = 50; // Cycle limiter 659 for (;;) { // While we can dance past unrelated stores... 660 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 661 662 Node* prev = mem; 663 if (mem->is_Store()) { 664 Node* st_adr = mem->in(MemNode::Address); 665 intptr_t st_offset = 0; 666 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 667 if (st_base == NULL) 668 break; // inscrutable pointer 669 670 // For raw accesses it's not enough to prove that constant offsets don't intersect. 671 // We need the bases to be the equal in order for the offset check to make sense. 672 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) { 673 break; 674 } 675 676 if (st_offset != offset && st_offset != Type::OffsetBot) { 677 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize); 678 assert(mem->as_Store()->memory_size() <= MAX_STORE, ""); 679 if (st_offset >= offset + size_in_bytes || 680 st_offset <= offset - MAX_STORE || 681 st_offset <= offset - mem->as_Store()->memory_size()) { 682 // Success: The offsets are provably independent. 683 // (You may ask, why not just test st_offset != offset and be done? 684 // The answer is that stores of different sizes can co-exist 685 // in the same sequence of RawMem effects. We sometimes initialize 686 // a whole 'tile' of array elements with a single jint or jlong.) 687 mem = mem->in(MemNode::Memory); 688 continue; // (a) advance through independent store memory 689 } 690 } 691 if (st_base != base && 692 detect_ptr_independence(base, alloc, 693 st_base, 694 AllocateNode::Ideal_allocation(st_base, phase), 695 phase)) { 696 // Success: The bases are provably independent. 697 mem = mem->in(MemNode::Memory); 698 continue; // (a) advance through independent store memory 699 } 700 701 // (b) At this point, if the bases or offsets do not agree, we lose, 702 // since we have not managed to prove 'this' and 'mem' independent. 703 if (st_base == base && st_offset == offset) { 704 return mem; // let caller handle steps (c), (d) 705 } 706 707 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 708 InitializeNode* st_init = mem->in(0)->as_Initialize(); 709 AllocateNode* st_alloc = st_init->allocation(); 710 if (st_alloc == NULL) 711 break; // something degenerated 712 bool known_identical = false; 713 bool known_independent = false; 714 if (alloc == st_alloc) 715 known_identical = true; 716 else if (alloc != NULL) 717 known_independent = true; 718 else if (all_controls_dominate(this, st_alloc)) 719 known_independent = true; 720 721 if (known_independent) { 722 // The bases are provably independent: Either they are 723 // manifestly distinct allocations, or else the control 724 // of this load dominates the store's allocation. 725 int alias_idx = phase->C->get_alias_index(adr_type()); 726 if (alias_idx == Compile::AliasIdxRaw) { 727 mem = st_alloc->in(TypeFunc::Memory); 728 } else { 729 mem = st_init->memory(alias_idx); 730 } 731 continue; // (a) advance through independent store memory 732 } 733 734 // (b) at this point, if we are not looking at a store initializing 735 // the same allocation we are loading from, we lose. 736 if (known_identical) { 737 // From caller, can_see_stored_value will consult find_captured_store. 738 return mem; // let caller handle steps (c), (d) 739 } 740 741 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) { 742 if (prev != mem) { 743 // Found an arraycopy but it doesn't affect that load 744 continue; 745 } 746 // Found an arraycopy that may affect that load 747 return mem; 748 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 749 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 750 if (mem->is_Proj() && mem->in(0)->is_Call()) { 751 // ArrayCopyNodes processed here as well. 752 CallNode *call = mem->in(0)->as_Call(); 753 if (!call->may_modify(addr_t, phase)) { 754 mem = call->in(TypeFunc::Memory); 755 continue; // (a) advance through independent call memory 756 } 757 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 758 ArrayCopyNode* ac = NULL; 759 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) { 760 break; 761 } 762 mem = mem->in(0)->in(TypeFunc::Memory); 763 continue; // (a) advance through independent MemBar memory 764 } else if (mem->is_ClearArray()) { 765 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 766 // (the call updated 'mem' value) 767 continue; // (a) advance through independent allocation memory 768 } else { 769 // Can not bypass initialization of the instance 770 // we are looking for. 771 return mem; 772 } 773 } else if (mem->is_MergeMem()) { 774 int alias_idx = phase->C->get_alias_index(adr_type()); 775 mem = mem->as_MergeMem()->memory_at(alias_idx); 776 continue; // (a) advance through independent MergeMem memory 777 } 778 } 779 780 // Unless there is an explicit 'continue', we must bail out here, 781 // because 'mem' is an inscrutable memory state (e.g., a call). 782 break; 783 } 784 785 return NULL; // bail out 786 } 787 788 //----------------------calculate_adr_type------------------------------------- 789 // Helper function. Notices when the given type of address hits top or bottom. 790 // Also, asserts a cross-check of the type against the expected address type. 791 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 792 if (t == Type::TOP) return NULL; // does not touch memory any more? 793 #ifdef ASSERT 794 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL; 795 #endif 796 const TypePtr* tp = t->isa_ptr(); 797 if (tp == NULL) { 798 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 799 return TypePtr::BOTTOM; // touches lots of memory 800 } else { 801 #ifdef ASSERT 802 // %%%% [phh] We don't check the alias index if cross_check is 803 // TypeRawPtr::BOTTOM. Needs to be investigated. 804 if (cross_check != NULL && 805 cross_check != TypePtr::BOTTOM && 806 cross_check != TypeRawPtr::BOTTOM) { 807 // Recheck the alias index, to see if it has changed (due to a bug). 808 Compile* C = Compile::current(); 809 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 810 "must stay in the original alias category"); 811 // The type of the address must be contained in the adr_type, 812 // disregarding "null"-ness. 813 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 814 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 815 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 816 "real address must not escape from expected memory type"); 817 } 818 #endif 819 return tp; 820 } 821 } 822 823 //============================================================================= 824 // Should LoadNode::Ideal() attempt to remove control edges? 825 bool LoadNode::can_remove_control() const { 826 return !has_pinned_control_dependency(); 827 } 828 uint LoadNode::size_of() const { return sizeof(*this); } 829 bool LoadNode::cmp( const Node &n ) const 830 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 831 const Type *LoadNode::bottom_type() const { return _type; } 832 uint LoadNode::ideal_reg() const { 833 return _type->ideal_reg(); 834 } 835 836 #ifndef PRODUCT 837 void LoadNode::dump_spec(outputStream *st) const { 838 MemNode::dump_spec(st); 839 if( !Verbose && !WizardMode ) { 840 // standard dump does this in Verbose and WizardMode 841 st->print(" #"); _type->dump_on(st); 842 } 843 if (!depends_only_on_test()) { 844 st->print(" (does not depend only on test, "); 845 if (control_dependency() == UnknownControl) { 846 st->print("unknown control"); 847 } else if (control_dependency() == Pinned) { 848 st->print("pinned"); 849 } else if (adr_type() == TypeRawPtr::BOTTOM) { 850 st->print("raw access"); 851 } else { 852 st->print("unknown reason"); 853 } 854 st->print(")"); 855 } 856 } 857 #endif 858 859 #ifdef ASSERT 860 //----------------------------is_immutable_value------------------------------- 861 // Helper function to allow a raw load without control edge for some cases 862 bool LoadNode::is_immutable_value(Node* adr) { 863 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 864 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 865 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 866 in_bytes(JavaThread::osthread_offset()) || 867 adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 868 in_bytes(JavaThread::threadObj_offset()))); 869 } 870 #endif 871 872 //----------------------------LoadNode::make----------------------------------- 873 // Polymorphic factory method: 874 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo, 875 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) { 876 Compile* C = gvn.C; 877 878 // sanity check the alias category against the created node type 879 assert(!(adr_type->isa_oopptr() && 880 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 881 "use LoadKlassNode instead"); 882 assert(!(adr_type->isa_aryptr() && 883 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 884 "use LoadRangeNode instead"); 885 // Check control edge of raw loads 886 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 887 // oop will be recorded in oop map if load crosses safepoint 888 rt->isa_oopptr() || is_immutable_value(adr), 889 "raw memory operations should have control edge"); 890 LoadNode* load = NULL; 891 switch (bt) { 892 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 893 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 894 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 895 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 896 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 897 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break; 898 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 899 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break; 900 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break; 901 case T_OBJECT: 902 #ifdef _LP64 903 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 904 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency); 905 } else 906 #endif 907 { 908 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 909 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 910 } 911 break; 912 default: 913 ShouldNotReachHere(); 914 break; 915 } 916 assert(load != NULL, "LoadNode should have been created"); 917 if (unaligned) { 918 load->set_unaligned_access(); 919 } 920 if (mismatched) { 921 load->set_mismatched_access(); 922 } 923 if (unsafe) { 924 load->set_unsafe_access(); 925 } 926 load->set_barrier_data(barrier_data); 927 if (load->Opcode() == Op_LoadN) { 928 Node* ld = gvn.transform(load); 929 return new DecodeNNode(ld, ld->bottom_type()->make_ptr()); 930 } 931 932 return load; 933 } 934 935 //------------------------------hash------------------------------------------- 936 uint LoadNode::hash() const { 937 // unroll addition of interesting fields 938 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 939 } 940 941 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 942 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 943 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 944 bool is_stable_ary = FoldStableValues && 945 (tp != NULL) && (tp->isa_aryptr() != NULL) && 946 tp->isa_aryptr()->is_stable(); 947 948 return (eliminate_boxing && non_volatile) || is_stable_ary; 949 } 950 951 return false; 952 } 953 954 // Is the value loaded previously stored by an arraycopy? If so return 955 // a load node that reads from the source array so we may be able to 956 // optimize out the ArrayCopy node later. 957 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const { 958 Node* ld_adr = in(MemNode::Address); 959 intptr_t ld_off = 0; 960 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 961 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 962 if (ac != NULL) { 963 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 964 965 Node* mem = ac->in(TypeFunc::Memory); 966 Node* ctl = ac->in(0); 967 Node* src = ac->in(ArrayCopyNode::Src); 968 969 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) { 970 return NULL; 971 } 972 973 LoadNode* ld = clone()->as_Load(); 974 Node* addp = in(MemNode::Address)->clone(); 975 if (ac->as_ArrayCopy()->is_clonebasic()) { 976 assert(ld_alloc != NULL, "need an alloc"); 977 assert(addp->is_AddP(), "address must be addp"); 978 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 979 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern"); 980 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern"); 981 addp->set_req(AddPNode::Base, src); 982 addp->set_req(AddPNode::Address, src); 983 } else { 984 assert(ac->as_ArrayCopy()->is_arraycopy_validated() || 985 ac->as_ArrayCopy()->is_copyof_validated() || 986 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases"); 987 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 988 addp->set_req(AddPNode::Base, src); 989 addp->set_req(AddPNode::Address, src); 990 991 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 992 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 993 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 994 uint shift = exact_log2(type2aelembytes(ary_elem)); 995 996 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 997 #ifdef _LP64 998 diff = phase->transform(new ConvI2LNode(diff)); 999 #endif 1000 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 1001 1002 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 1003 addp->set_req(AddPNode::Offset, offset); 1004 } 1005 addp = phase->transform(addp); 1006 #ifdef ASSERT 1007 const TypePtr* adr_type = phase->type(addp)->is_ptr(); 1008 ld->_adr_type = adr_type; 1009 #endif 1010 ld->set_req(MemNode::Address, addp); 1011 ld->set_req(0, ctl); 1012 ld->set_req(MemNode::Memory, mem); 1013 // load depends on the tests that validate the arraycopy 1014 ld->_control_dependency = UnknownControl; 1015 return ld; 1016 } 1017 return NULL; 1018 } 1019 1020 1021 //---------------------------can_see_stored_value------------------------------ 1022 // This routine exists to make sure this set of tests is done the same 1023 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 1024 // will change the graph shape in a way which makes memory alive twice at the 1025 // same time (uses the Oracle model of aliasing), then some 1026 // LoadXNode::Identity will fold things back to the equivalence-class model 1027 // of aliasing. 1028 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 1029 Node* ld_adr = in(MemNode::Address); 1030 intptr_t ld_off = 0; 1031 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off); 1032 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase); 1033 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 1034 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 1035 // This is more general than load from boxing objects. 1036 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 1037 uint alias_idx = atp->index(); 1038 Node* result = NULL; 1039 Node* current = st; 1040 // Skip through chains of MemBarNodes checking the MergeMems for 1041 // new states for the slice of this load. Stop once any other 1042 // kind of node is encountered. Loads from final memory can skip 1043 // through any kind of MemBar but normal loads shouldn't skip 1044 // through MemBarAcquire since the could allow them to move out of 1045 // a synchronized region. It is not safe to step over MemBarCPUOrder, 1046 // because alias info above them may be inaccurate (e.g., due to 1047 // mixed/mismatched unsafe accesses). 1048 bool is_final_mem = !atp->is_rewritable(); 1049 while (current->is_Proj()) { 1050 int opc = current->in(0)->Opcode(); 1051 if ((is_final_mem && (opc == Op_MemBarAcquire || 1052 opc == Op_MemBarAcquireLock || 1053 opc == Op_LoadFence)) || 1054 opc == Op_MemBarRelease || 1055 opc == Op_StoreFence || 1056 opc == Op_MemBarReleaseLock || 1057 opc == Op_MemBarStoreStore || 1058 opc == Op_StoreStoreFence) { 1059 Node* mem = current->in(0)->in(TypeFunc::Memory); 1060 if (mem->is_MergeMem()) { 1061 MergeMemNode* merge = mem->as_MergeMem(); 1062 Node* new_st = merge->memory_at(alias_idx); 1063 if (new_st == merge->base_memory()) { 1064 // Keep searching 1065 current = new_st; 1066 continue; 1067 } 1068 // Save the new memory state for the slice and fall through 1069 // to exit. 1070 result = new_st; 1071 } 1072 } 1073 break; 1074 } 1075 if (result != NULL) { 1076 st = result; 1077 } 1078 } 1079 1080 // Loop around twice in the case Load -> Initialize -> Store. 1081 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1082 for (int trip = 0; trip <= 1; trip++) { 1083 1084 if (st->is_Store()) { 1085 Node* st_adr = st->in(MemNode::Address); 1086 if (st_adr != ld_adr) { 1087 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers). 1088 intptr_t st_off = 0; 1089 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off); 1090 if (ld_base == NULL) return NULL; 1091 if (st_base == NULL) return NULL; 1092 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL; 1093 if (ld_off != st_off) return NULL; 1094 if (ld_off == Type::OffsetBot) return NULL; 1095 // Same base, same offset. 1096 // Possible improvement for arrays: check index value instead of absolute offset. 1097 1098 // At this point we have proven something like this setup: 1099 // B = << base >> 1100 // L = LoadQ(AddP(Check/CastPP(B), #Off)) 1101 // S = StoreQ(AddP( B , #Off), V) 1102 // (Actually, we haven't yet proven the Q's are the same.) 1103 // In other words, we are loading from a casted version of 1104 // the same pointer-and-offset that we stored to. 1105 // Casted version may carry a dependency and it is respected. 1106 // Thus, we are able to replace L by V. 1107 } 1108 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1109 if (store_Opcode() != st->Opcode()) { 1110 return NULL; 1111 } 1112 // LoadVector/StoreVector needs additional check to ensure the types match. 1113 if (store_Opcode() == Op_StoreVector) { 1114 const TypeVect* in_vt = st->as_StoreVector()->vect_type(); 1115 const TypeVect* out_vt = as_LoadVector()->vect_type(); 1116 if (in_vt != out_vt) { 1117 return NULL; 1118 } 1119 } 1120 return st->in(MemNode::ValueIn); 1121 } 1122 1123 // A load from a freshly-created object always returns zero. 1124 // (This can happen after LoadNode::Ideal resets the load's memory input 1125 // to find_captured_store, which returned InitializeNode::zero_memory.) 1126 if (st->is_Proj() && st->in(0)->is_Allocate() && 1127 (st->in(0) == ld_alloc) && 1128 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1129 // return a zero value for the load's basic type 1130 // (This is one of the few places where a generic PhaseTransform 1131 // can create new nodes. Think of it as lazily manifesting 1132 // virtually pre-existing constants.) 1133 if (memory_type() != T_VOID) { 1134 if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == NULL) { 1135 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an 1136 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done 1137 // by the ArrayCopyNode. 1138 return phase->zerocon(memory_type()); 1139 } 1140 } else { 1141 // TODO: materialize all-zero vector constant 1142 assert(!isa_Load() || as_Load()->type()->isa_vect(), ""); 1143 } 1144 } 1145 1146 // A load from an initialization barrier can match a captured store. 1147 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1148 InitializeNode* init = st->in(0)->as_Initialize(); 1149 AllocateNode* alloc = init->allocation(); 1150 if ((alloc != NULL) && (alloc == ld_alloc)) { 1151 // examine a captured store value 1152 st = init->find_captured_store(ld_off, memory_size(), phase); 1153 if (st != NULL) { 1154 continue; // take one more trip around 1155 } 1156 } 1157 } 1158 1159 // Load boxed value from result of valueOf() call is input parameter. 1160 if (this->is_Load() && ld_adr->is_AddP() && 1161 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1162 intptr_t ignore = 0; 1163 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1164 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 1165 base = bs->step_over_gc_barrier(base); 1166 if (base != NULL && base->is_Proj() && 1167 base->as_Proj()->_con == TypeFunc::Parms && 1168 base->in(0)->is_CallStaticJava() && 1169 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1170 return base->in(0)->in(TypeFunc::Parms); 1171 } 1172 } 1173 1174 break; 1175 } 1176 1177 return NULL; 1178 } 1179 1180 //----------------------is_instance_field_load_with_local_phi------------------ 1181 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1182 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1183 in(Address)->is_AddP() ) { 1184 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1185 // Only instances and boxed values. 1186 if( t_oop != NULL && 1187 (t_oop->is_ptr_to_boxed_value() || 1188 t_oop->is_known_instance_field()) && 1189 t_oop->offset() != Type::OffsetBot && 1190 t_oop->offset() != Type::OffsetTop) { 1191 return true; 1192 } 1193 } 1194 return false; 1195 } 1196 1197 //------------------------------Identity--------------------------------------- 1198 // Loads are identity if previous store is to same address 1199 Node* LoadNode::Identity(PhaseGVN* phase) { 1200 // If the previous store-maker is the right kind of Store, and the store is 1201 // to the same address, then we are equal to the value stored. 1202 Node* mem = in(Memory); 1203 Node* value = can_see_stored_value(mem, phase); 1204 if( value ) { 1205 // byte, short & char stores truncate naturally. 1206 // A load has to load the truncated value which requires 1207 // some sort of masking operation and that requires an 1208 // Ideal call instead of an Identity call. 1209 if (memory_size() < BytesPerInt) { 1210 // If the input to the store does not fit with the load's result type, 1211 // it must be truncated via an Ideal call. 1212 if (!phase->type(value)->higher_equal(phase->type(this))) 1213 return this; 1214 } 1215 // (This works even when value is a Con, but LoadNode::Value 1216 // usually runs first, producing the singleton type of the Con.) 1217 if (!has_pinned_control_dependency() || value->is_Con()) { 1218 return value; 1219 } else { 1220 return this; 1221 } 1222 } 1223 1224 if (has_pinned_control_dependency()) { 1225 return this; 1226 } 1227 // Search for an existing data phi which was generated before for the same 1228 // instance's field to avoid infinite generation of phis in a loop. 1229 Node *region = mem->in(0); 1230 if (is_instance_field_load_with_local_phi(region)) { 1231 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1232 int this_index = phase->C->get_alias_index(addr_t); 1233 int this_offset = addr_t->offset(); 1234 int this_iid = addr_t->instance_id(); 1235 if (!addr_t->is_known_instance() && 1236 addr_t->is_ptr_to_boxed_value()) { 1237 // Use _idx of address base (could be Phi node) for boxed values. 1238 intptr_t ignore = 0; 1239 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1240 if (base == NULL) { 1241 return this; 1242 } 1243 this_iid = base->_idx; 1244 } 1245 const Type* this_type = bottom_type(); 1246 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1247 Node* phi = region->fast_out(i); 1248 if (phi->is_Phi() && phi != mem && 1249 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) { 1250 return phi; 1251 } 1252 } 1253 } 1254 1255 return this; 1256 } 1257 1258 // Construct an equivalent unsigned load. 1259 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) { 1260 BasicType bt = T_ILLEGAL; 1261 const Type* rt = NULL; 1262 switch (Opcode()) { 1263 case Op_LoadUB: return this; 1264 case Op_LoadUS: return this; 1265 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break; 1266 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break; 1267 default: 1268 assert(false, "no unsigned 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 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access()); 1274 } 1275 1276 // Construct an equivalent signed load. 1277 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) { 1278 BasicType bt = T_ILLEGAL; 1279 const Type* rt = NULL; 1280 switch (Opcode()) { 1281 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break; 1282 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break; 1283 case Op_LoadB: // fall through 1284 case Op_LoadS: // fall through 1285 case Op_LoadI: // fall through 1286 case Op_LoadL: return this; 1287 default: 1288 assert(false, "no signed variant: %s", Name()); 1289 return NULL; 1290 } 1291 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1292 raw_adr_type(), rt, bt, _mo, _control_dependency, 1293 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access()); 1294 } 1295 1296 bool LoadNode::has_reinterpret_variant(const Type* rt) { 1297 BasicType bt = rt->basic_type(); 1298 switch (Opcode()) { 1299 case Op_LoadI: return (bt == T_FLOAT); 1300 case Op_LoadL: return (bt == T_DOUBLE); 1301 case Op_LoadF: return (bt == T_INT); 1302 case Op_LoadD: return (bt == T_LONG); 1303 1304 default: return false; 1305 } 1306 } 1307 1308 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) { 1309 BasicType bt = rt->basic_type(); 1310 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt)); 1311 bool is_mismatched = is_mismatched_access(); 1312 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr(); 1313 if (raw_type == NULL) { 1314 is_mismatched = true; // conservatively match all non-raw accesses as mismatched 1315 } 1316 const int op = Opcode(); 1317 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) || 1318 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access()); 1319 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1320 raw_adr_type(), rt, bt, _mo, _control_dependency, 1321 require_atomic_access, is_unaligned_access(), is_mismatched); 1322 } 1323 1324 bool StoreNode::has_reinterpret_variant(const Type* vt) { 1325 BasicType bt = vt->basic_type(); 1326 switch (Opcode()) { 1327 case Op_StoreI: return (bt == T_FLOAT); 1328 case Op_StoreL: return (bt == T_DOUBLE); 1329 case Op_StoreF: return (bt == T_INT); 1330 case Op_StoreD: return (bt == T_LONG); 1331 1332 default: return false; 1333 } 1334 } 1335 1336 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) { 1337 BasicType bt = vt->basic_type(); 1338 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt)); 1339 const int op = Opcode(); 1340 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) || 1341 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access()); 1342 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1343 raw_adr_type(), val, bt, _mo, require_atomic_access); 1344 1345 bool is_mismatched = is_mismatched_access(); 1346 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr(); 1347 if (raw_type == NULL) { 1348 is_mismatched = true; // conservatively match all non-raw accesses as mismatched 1349 } 1350 if (is_mismatched) { 1351 st->set_mismatched_access(); 1352 } 1353 return st; 1354 } 1355 1356 // We're loading from an object which has autobox behaviour. 1357 // If this object is result of a valueOf call we'll have a phi 1358 // merging a newly allocated object and a load from the cache. 1359 // We want to replace this load with the original incoming 1360 // argument to the valueOf call. 1361 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) { 1362 assert(igvn->C->eliminate_boxing(), "sanity"); 1363 intptr_t ignore = 0; 1364 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore); 1365 if ((base == NULL) || base->is_Phi()) { 1366 // Push the loads from the phi that comes from valueOf up 1367 // through it to allow elimination of the loads and the recovery 1368 // of the original value. It is done in split_through_phi(). 1369 return NULL; 1370 } else if (base->is_Load() || 1371 (base->is_DecodeN() && base->in(1)->is_Load())) { 1372 // Eliminate the load of boxed value for integer types from the cache 1373 // array by deriving the value from the index into the array. 1374 // Capture the offset of the load and then reverse the computation. 1375 1376 // Get LoadN node which loads a boxing object from 'cache' array. 1377 if (base->is_DecodeN()) { 1378 base = base->in(1); 1379 } 1380 if (!base->in(Address)->is_AddP()) { 1381 return NULL; // Complex address 1382 } 1383 AddPNode* address = base->in(Address)->as_AddP(); 1384 Node* cache_base = address->in(AddPNode::Base); 1385 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1386 // Get ConP node which is static 'cache' field. 1387 cache_base = cache_base->in(1); 1388 } 1389 if ((cache_base != NULL) && cache_base->is_Con()) { 1390 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1391 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1392 Node* elements[4]; 1393 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1394 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1395 if (count > 0 && elements[0]->is_Con() && 1396 (count == 1 || 1397 (count == 2 && elements[1]->Opcode() == Op_LShiftX && 1398 elements[1]->in(2) == igvn->intcon(shift)))) { 1399 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1400 // Fetch the box object cache[0] at the base of the array and get its value 1401 ciInstance* box = array->obj_at(0)->as_instance(); 1402 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1403 assert(ik->is_box_klass(), "sanity"); 1404 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1405 if (ik->nof_nonstatic_fields() == 1) { 1406 // This should be true nonstatic_field_at requires calling 1407 // nof_nonstatic_fields so check it anyway 1408 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1409 BasicType bt = c.basic_type(); 1410 // Only integer types have boxing cache. 1411 assert(bt == T_BOOLEAN || bt == T_CHAR || 1412 bt == T_BYTE || bt == T_SHORT || 1413 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt)); 1414 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1415 if (cache_low != (int)cache_low) { 1416 return NULL; // should not happen since cache is array indexed by value 1417 } 1418 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1419 if (offset != (int)offset) { 1420 return NULL; // should not happen since cache is array indexed by value 1421 } 1422 // Add up all the offsets making of the address of the load 1423 Node* result = elements[0]; 1424 for (int i = 1; i < count; i++) { 1425 result = igvn->transform(new AddXNode(result, elements[i])); 1426 } 1427 // Remove the constant offset from the address and then 1428 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset))); 1429 // remove the scaling of the offset to recover the original index. 1430 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) { 1431 // Peel the shift off directly but wrap it in a dummy node 1432 // since Ideal can't return existing nodes 1433 igvn->_worklist.push(result); // remove dead node later 1434 result = new RShiftXNode(result->in(1), igvn->intcon(0)); 1435 } else if (result->is_Add() && result->in(2)->is_Con() && 1436 result->in(1)->Opcode() == Op_LShiftX && 1437 result->in(1)->in(2) == igvn->intcon(shift)) { 1438 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1439 // but for boxing cache access we know that X<<Z will not overflow 1440 // (there is range check) so we do this optimizatrion by hand here. 1441 igvn->_worklist.push(result); // remove dead node later 1442 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift)); 1443 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con)); 1444 } else { 1445 result = new RShiftXNode(result, igvn->intcon(shift)); 1446 } 1447 #ifdef _LP64 1448 if (bt != T_LONG) { 1449 result = new ConvL2INode(igvn->transform(result)); 1450 } 1451 #else 1452 if (bt == T_LONG) { 1453 result = new ConvI2LNode(igvn->transform(result)); 1454 } 1455 #endif 1456 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1457 // Need to preserve unboxing load type if it is unsigned. 1458 switch(this->Opcode()) { 1459 case Op_LoadUB: 1460 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF)); 1461 break; 1462 case Op_LoadUS: 1463 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF)); 1464 break; 1465 } 1466 return result; 1467 } 1468 } 1469 } 1470 } 1471 } 1472 return NULL; 1473 } 1474 1475 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1476 Node* region = phi->in(0); 1477 if (region == NULL) { 1478 return false; // Wait stable graph 1479 } 1480 uint cnt = phi->req(); 1481 for (uint i = 1; i < cnt; i++) { 1482 Node* rc = region->in(i); 1483 if (rc == NULL || phase->type(rc) == Type::TOP) 1484 return false; // Wait stable graph 1485 Node* in = phi->in(i); 1486 if (in == NULL || phase->type(in) == Type::TOP) 1487 return false; // Wait stable graph 1488 } 1489 return true; 1490 } 1491 //------------------------------split_through_phi------------------------------ 1492 // Split instance or boxed field load through Phi. 1493 Node* LoadNode::split_through_phi(PhaseGVN* phase) { 1494 if (req() > 3) { 1495 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs"); 1496 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account 1497 return NULL; 1498 } 1499 Node* mem = in(Memory); 1500 Node* address = in(Address); 1501 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1502 1503 assert((t_oop != NULL) && 1504 (t_oop->is_known_instance_field() || 1505 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1506 1507 Compile* C = phase->C; 1508 intptr_t ignore = 0; 1509 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1510 bool base_is_phi = (base != NULL) && base->is_Phi(); 1511 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1512 (base != NULL) && (base == address->in(AddPNode::Base)) && 1513 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1514 1515 if (!((mem->is_Phi() || base_is_phi) && 1516 (load_boxed_values || t_oop->is_known_instance_field()))) { 1517 return NULL; // memory is not Phi 1518 } 1519 1520 if (mem->is_Phi()) { 1521 if (!stable_phi(mem->as_Phi(), phase)) { 1522 return NULL; // Wait stable graph 1523 } 1524 uint cnt = mem->req(); 1525 // Check for loop invariant memory. 1526 if (cnt == 3) { 1527 for (uint i = 1; i < cnt; i++) { 1528 Node* in = mem->in(i); 1529 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1530 if (m == mem) { 1531 if (i == 1) { 1532 // if the first edge was a loop, check second edge too. 1533 // If both are replaceable - we are in an infinite loop 1534 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase); 1535 if (n == mem) { 1536 break; 1537 } 1538 } 1539 set_req(Memory, mem->in(cnt - i)); 1540 return this; // made change 1541 } 1542 } 1543 } 1544 } 1545 if (base_is_phi) { 1546 if (!stable_phi(base->as_Phi(), phase)) { 1547 return NULL; // Wait stable graph 1548 } 1549 uint cnt = base->req(); 1550 // Check for loop invariant memory. 1551 if (cnt == 3) { 1552 for (uint i = 1; i < cnt; i++) { 1553 if (base->in(i) == base) { 1554 return NULL; // Wait stable graph 1555 } 1556 } 1557 } 1558 } 1559 1560 // Split through Phi (see original code in loopopts.cpp). 1561 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1562 1563 // Do nothing here if Identity will find a value 1564 // (to avoid infinite chain of value phis generation). 1565 if (this != Identity(phase)) { 1566 return NULL; 1567 } 1568 1569 // Select Region to split through. 1570 Node* region; 1571 if (!base_is_phi) { 1572 assert(mem->is_Phi(), "sanity"); 1573 region = mem->in(0); 1574 // Skip if the region dominates some control edge of the address. 1575 if (!MemNode::all_controls_dominate(address, region)) 1576 return NULL; 1577 } else if (!mem->is_Phi()) { 1578 assert(base_is_phi, "sanity"); 1579 region = base->in(0); 1580 // Skip if the region dominates some control edge of the memory. 1581 if (!MemNode::all_controls_dominate(mem, region)) 1582 return NULL; 1583 } else if (base->in(0) != mem->in(0)) { 1584 assert(base_is_phi && mem->is_Phi(), "sanity"); 1585 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1586 region = base->in(0); 1587 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1588 region = mem->in(0); 1589 } else { 1590 return NULL; // complex graph 1591 } 1592 } else { 1593 assert(base->in(0) == mem->in(0), "sanity"); 1594 region = mem->in(0); 1595 } 1596 1597 const Type* this_type = this->bottom_type(); 1598 int this_index = C->get_alias_index(t_oop); 1599 int this_offset = t_oop->offset(); 1600 int this_iid = t_oop->instance_id(); 1601 if (!t_oop->is_known_instance() && load_boxed_values) { 1602 // Use _idx of address base for boxed values. 1603 this_iid = base->_idx; 1604 } 1605 PhaseIterGVN* igvn = phase->is_IterGVN(); 1606 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset); 1607 for (uint i = 1; i < region->req(); i++) { 1608 Node* x; 1609 Node* the_clone = NULL; 1610 Node* in = region->in(i); 1611 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl && 1612 in != NULL && in->is_OuterStripMinedLoop()) { 1613 // No node should go in the outer strip mined loop 1614 in = in->in(LoopNode::EntryControl); 1615 } 1616 if (in == NULL || in == C->top()) { 1617 x = C->top(); // Dead path? Use a dead data op 1618 } else { 1619 x = this->clone(); // Else clone up the data op 1620 the_clone = x; // Remember for possible deletion. 1621 // Alter data node to use pre-phi inputs 1622 if (this->in(0) == region) { 1623 x->set_req(0, in); 1624 } else { 1625 x->set_req(0, NULL); 1626 } 1627 if (mem->is_Phi() && (mem->in(0) == region)) { 1628 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1629 } 1630 if (address->is_Phi() && address->in(0) == region) { 1631 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1632 } 1633 if (base_is_phi && (base->in(0) == region)) { 1634 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1635 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1636 x->set_req(Address, adr_x); 1637 } 1638 } 1639 // Check for a 'win' on some paths 1640 const Type *t = x->Value(igvn); 1641 1642 bool singleton = t->singleton(); 1643 1644 // See comments in PhaseIdealLoop::split_thru_phi(). 1645 if (singleton && t == Type::TOP) { 1646 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1647 } 1648 1649 if (singleton) { 1650 x = igvn->makecon(t); 1651 } else { 1652 // We now call Identity to try to simplify the cloned node. 1653 // Note that some Identity methods call phase->type(this). 1654 // Make sure that the type array is big enough for 1655 // our new node, even though we may throw the node away. 1656 // (This tweaking with igvn only works because x is a new node.) 1657 igvn->set_type(x, t); 1658 // If x is a TypeNode, capture any more-precise type permanently into Node 1659 // otherwise it will be not updated during igvn->transform since 1660 // igvn->type(x) is set to x->Value() already. 1661 x->raise_bottom_type(t); 1662 Node* y = x->Identity(igvn); 1663 if (y != x) { 1664 x = y; 1665 } else { 1666 y = igvn->hash_find_insert(x); 1667 if (y) { 1668 x = y; 1669 } else { 1670 // Else x is a new node we are keeping 1671 // We do not need register_new_node_with_optimizer 1672 // because set_type has already been called. 1673 igvn->_worklist.push(x); 1674 } 1675 } 1676 } 1677 if (x != the_clone && the_clone != NULL) { 1678 igvn->remove_dead_node(the_clone); 1679 } 1680 phi->set_req(i, x); 1681 } 1682 // Record Phi 1683 igvn->register_new_node_with_optimizer(phi); 1684 return phi; 1685 } 1686 1687 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const { 1688 if (Opcode() == Op_LoadX) { 1689 Node* address = in(MemNode::Address); 1690 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase); 1691 Node* mem = in(MemNode::Memory); 1692 if (alloc != NULL && mem->is_Proj() && 1693 mem->in(0) != NULL && 1694 mem->in(0) == alloc->initialization() && 1695 alloc->initialization()->proj_out_or_null(0) != NULL) { 1696 return alloc; 1697 } 1698 } 1699 return NULL; 1700 } 1701 1702 1703 //------------------------------Ideal------------------------------------------ 1704 // If the load is from Field memory and the pointer is non-null, it might be possible to 1705 // zero out the control input. 1706 // If the offset is constant and the base is an object allocation, 1707 // try to hook me up to the exact initializing store. 1708 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1709 if (has_pinned_control_dependency()) { 1710 return NULL; 1711 } 1712 Node* p = MemNode::Ideal_common(phase, can_reshape); 1713 if (p) return (p == NodeSentinel) ? NULL : p; 1714 1715 Node* ctrl = in(MemNode::Control); 1716 Node* address = in(MemNode::Address); 1717 bool progress = false; 1718 1719 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) && 1720 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes()); 1721 1722 // Skip up past a SafePoint control. Cannot do this for Stores because 1723 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1724 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1725 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw && 1726 !addr_mark && 1727 (depends_only_on_test() || has_unknown_control_dependency())) { 1728 ctrl = ctrl->in(0); 1729 set_req(MemNode::Control,ctrl); 1730 progress = true; 1731 } 1732 1733 intptr_t ignore = 0; 1734 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1735 if (base != NULL 1736 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1737 // Check for useless control edge in some common special cases 1738 if (in(MemNode::Control) != NULL 1739 && can_remove_control() 1740 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1741 && all_controls_dominate(base, phase->C->start())) { 1742 // A method-invariant, non-null address (constant or 'this' argument). 1743 set_req(MemNode::Control, NULL); 1744 progress = true; 1745 } 1746 } 1747 1748 Node* mem = in(MemNode::Memory); 1749 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1750 1751 if (can_reshape && (addr_t != NULL)) { 1752 // try to optimize our memory input 1753 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1754 if (opt_mem != mem) { 1755 set_req_X(MemNode::Memory, opt_mem, phase); 1756 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1757 return this; 1758 } 1759 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1760 if ((t_oop != NULL) && 1761 (t_oop->is_known_instance_field() || 1762 t_oop->is_ptr_to_boxed_value())) { 1763 PhaseIterGVN *igvn = phase->is_IterGVN(); 1764 assert(igvn != NULL, "must be PhaseIterGVN when can_reshape is true"); 1765 if (igvn->_worklist.member(opt_mem)) { 1766 // Delay this transformation until memory Phi is processed. 1767 igvn->_worklist.push(this); 1768 return NULL; 1769 } 1770 // Split instance field load through Phi. 1771 Node* result = split_through_phi(phase); 1772 if (result != NULL) return result; 1773 1774 if (t_oop->is_ptr_to_boxed_value()) { 1775 Node* result = eliminate_autobox(igvn); 1776 if (result != NULL) return result; 1777 } 1778 } 1779 } 1780 1781 // Is there a dominating load that loads the same value? Leave 1782 // anything that is not a load of a field/array element (like 1783 // barriers etc.) alone 1784 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) { 1785 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 1786 Node *use = mem->fast_out(i); 1787 if (use != this && 1788 use->Opcode() == Opcode() && 1789 use->in(0) != NULL && 1790 use->in(0) != in(0) && 1791 use->in(Address) == in(Address)) { 1792 Node* ctl = in(0); 1793 for (int i = 0; i < 10 && ctl != NULL; i++) { 1794 ctl = IfNode::up_one_dom(ctl); 1795 if (ctl == use->in(0)) { 1796 set_req(0, use->in(0)); 1797 return this; 1798 } 1799 } 1800 } 1801 } 1802 } 1803 1804 // Check for prior store with a different base or offset; make Load 1805 // independent. Skip through any number of them. Bail out if the stores 1806 // are in an endless dead cycle and report no progress. This is a key 1807 // transform for Reflection. However, if after skipping through the Stores 1808 // we can't then fold up against a prior store do NOT do the transform as 1809 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1810 // array memory alive twice: once for the hoisted Load and again after the 1811 // bypassed Store. This situation only works if EVERYBODY who does 1812 // anti-dependence work knows how to bypass. I.e. we need all 1813 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1814 // the alias index stuff. So instead, peek through Stores and IFF we can 1815 // fold up, do so. 1816 Node* prev_mem = find_previous_store(phase); 1817 if (prev_mem != NULL) { 1818 Node* value = can_see_arraycopy_value(prev_mem, phase); 1819 if (value != NULL) { 1820 return value; 1821 } 1822 } 1823 // Steps (a), (b): Walk past independent stores to find an exact match. 1824 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1825 // (c) See if we can fold up on the spot, but don't fold up here. 1826 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1827 // just return a prior value, which is done by Identity calls. 1828 if (can_see_stored_value(prev_mem, phase)) { 1829 // Make ready for step (d): 1830 set_req_X(MemNode::Memory, prev_mem, phase); 1831 return this; 1832 } 1833 } 1834 1835 AllocateNode* alloc = is_new_object_mark_load(phase); 1836 if (alloc != NULL && alloc->Opcode() == Op_Allocate && UseBiasedLocking) { 1837 InitializeNode* init = alloc->initialization(); 1838 Node* control = init->proj_out(0); 1839 return alloc->make_ideal_mark(phase, address, control, mem); 1840 } 1841 1842 return progress ? this : NULL; 1843 } 1844 1845 // Helper to recognize certain Klass fields which are invariant across 1846 // some group of array types (e.g., int[] or all T[] where T < Object). 1847 const Type* 1848 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1849 ciKlass* klass) const { 1850 if (UseCompactObjectHeaders) { 1851 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) { 1852 // The field is Klass::_prototype_header. Return its (constant) value. 1853 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header"); 1854 return TypeX::make(klass->prototype_header()); 1855 } 1856 } 1857 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1858 // The field is Klass::_modifier_flags. Return its (constant) value. 1859 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1860 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1861 return TypeInt::make(klass->modifier_flags()); 1862 } 1863 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1864 // The field is Klass::_access_flags. Return its (constant) value. 1865 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1866 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1867 return TypeInt::make(klass->access_flags()); 1868 } 1869 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1870 // The field is Klass::_layout_helper. Return its constant value if known. 1871 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1872 return TypeInt::make(klass->layout_helper()); 1873 } 1874 1875 // No match. 1876 return NULL; 1877 } 1878 1879 //------------------------------Value----------------------------------------- 1880 const Type* LoadNode::Value(PhaseGVN* phase) const { 1881 // Either input is TOP ==> the result is TOP 1882 Node* mem = in(MemNode::Memory); 1883 const Type *t1 = phase->type(mem); 1884 if (t1 == Type::TOP) return Type::TOP; 1885 Node* adr = in(MemNode::Address); 1886 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1887 if (tp == NULL || tp->empty()) return Type::TOP; 1888 int off = tp->offset(); 1889 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1890 Compile* C = phase->C; 1891 1892 // Try to guess loaded type from pointer type 1893 if (tp->isa_aryptr()) { 1894 const TypeAryPtr* ary = tp->is_aryptr(); 1895 const Type* t = ary->elem(); 1896 1897 // Determine whether the reference is beyond the header or not, by comparing 1898 // the offset against the offset of the start of the array's data. 1899 // Different array types begin at slightly different offsets (12 vs. 16). 1900 // We choose T_BYTE as an example base type that is least restrictive 1901 // as to alignment, which will therefore produce the smallest 1902 // possible base offset. 1903 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1904 const bool off_beyond_header = (off >= min_base_off); 1905 1906 // Try to constant-fold a stable array element. 1907 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) { 1908 // Make sure the reference is not into the header and the offset is constant 1909 ciObject* aobj = ary->const_oop(); 1910 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1911 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0); 1912 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, 1913 stable_dimension, 1914 memory_type(), is_unsigned()); 1915 if (con_type != NULL) { 1916 return con_type; 1917 } 1918 } 1919 } 1920 1921 // Don't do this for integer types. There is only potential profit if 1922 // the element type t is lower than _type; that is, for int types, if _type is 1923 // more restrictive than t. This only happens here if one is short and the other 1924 // char (both 16 bits), and in those cases we've made an intentional decision 1925 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1926 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1927 // 1928 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1929 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1930 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1931 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1932 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1933 // In fact, that could have been the original type of p1, and p1 could have 1934 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1935 // expression (LShiftL quux 3) independently optimized to the constant 8. 1936 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1937 && (_type->isa_vect() == NULL) 1938 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1939 // t might actually be lower than _type, if _type is a unique 1940 // concrete subclass of abstract class t. 1941 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header? 1942 const Type* jt = t->join_speculative(_type); 1943 // In any case, do not allow the join, per se, to empty out the type. 1944 if (jt->empty() && !t->empty()) { 1945 // This can happen if a interface-typed array narrows to a class type. 1946 jt = _type; 1947 } 1948 #ifdef ASSERT 1949 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1950 // The pointers in the autobox arrays are always non-null 1951 Node* base = adr->in(AddPNode::Base); 1952 if ((base != NULL) && base->is_DecodeN()) { 1953 // Get LoadN node which loads IntegerCache.cache field 1954 base = base->in(1); 1955 } 1956 if ((base != NULL) && base->is_Con()) { 1957 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1958 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1959 // It could be narrow oop 1960 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1961 } 1962 } 1963 } 1964 #endif 1965 return jt; 1966 } 1967 } 1968 } else if (tp->base() == Type::InstPtr) { 1969 assert( off != Type::OffsetBot || 1970 // arrays can be cast to Objects 1971 tp->is_oopptr()->klass()->is_java_lang_Object() || 1972 // unsafe field access may not have a constant offset 1973 C->has_unsafe_access(), 1974 "Field accesses must be precise" ); 1975 // For oop loads, we expect the _type to be precise. 1976 1977 // Optimize loads from constant fields. 1978 const TypeInstPtr* tinst = tp->is_instptr(); 1979 ciObject* const_oop = tinst->const_oop(); 1980 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) { 1981 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type()); 1982 if (con_type != NULL) { 1983 return con_type; 1984 } 1985 } 1986 } else if (tp->base() == Type::KlassPtr) { 1987 assert( off != Type::OffsetBot || 1988 // arrays can be cast to Objects 1989 tp->is_klassptr()->klass()->is_java_lang_Object() || 1990 // also allow array-loading from the primary supertype 1991 // array during subtype checks 1992 Opcode() == Op_LoadKlass, 1993 "Field accesses must be precise" ); 1994 // For klass/static loads, we expect the _type to be precise 1995 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) { 1996 /* With mirrors being an indirect in the Klass* 1997 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset)) 1998 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass). 1999 * 2000 * So check the type and klass of the node before the LoadP. 2001 */ 2002 Node* adr2 = adr->in(MemNode::Address); 2003 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2004 if (tkls != NULL && !StressReflectiveCode) { 2005 ciKlass* klass = tkls->klass(); 2006 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 2007 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 2008 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 2009 return TypeInstPtr::make(klass->java_mirror()); 2010 } 2011 } 2012 } 2013 2014 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2015 if (tkls != NULL && !StressReflectiveCode) { 2016 ciKlass* klass = tkls->klass(); 2017 if (klass->is_loaded() && tkls->klass_is_exact()) { 2018 // We are loading a field from a Klass metaobject whose identity 2019 // is known at compile time (the type is "exact" or "precise"). 2020 // Check for fields we know are maintained as constants by the VM. 2021 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 2022 // The field is Klass::_super_check_offset. Return its (constant) value. 2023 // (Folds up type checking code.) 2024 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 2025 return TypeInt::make(klass->super_check_offset()); 2026 } 2027 if (UseCompactObjectHeaders) { 2028 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) { 2029 // The field is Klass::_prototype_header. Return its (constant) value. 2030 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header"); 2031 return TypeX::make(klass->prototype_header()); 2032 } 2033 } 2034 // Compute index into primary_supers array 2035 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 2036 // Check for overflowing; use unsigned compare to handle the negative case. 2037 if( depth < ciKlass::primary_super_limit() ) { 2038 // The field is an element of Klass::_primary_supers. Return its (constant) value. 2039 // (Folds up type checking code.) 2040 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 2041 ciKlass *ss = klass->super_of_depth(depth); 2042 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 2043 } 2044 const Type* aift = load_array_final_field(tkls, klass); 2045 if (aift != NULL) return aift; 2046 } 2047 2048 // We can still check if we are loading from the primary_supers array at a 2049 // shallow enough depth. Even though the klass is not exact, entries less 2050 // than or equal to its super depth are correct. 2051 if (klass->is_loaded() ) { 2052 ciType *inner = klass; 2053 while( inner->is_obj_array_klass() ) 2054 inner = inner->as_obj_array_klass()->base_element_type(); 2055 if( inner->is_instance_klass() && 2056 !inner->as_instance_klass()->flags().is_interface() ) { 2057 // Compute index into primary_supers array 2058 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 2059 // Check for overflowing; use unsigned compare to handle the negative case. 2060 if( depth < ciKlass::primary_super_limit() && 2061 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 2062 // The field is an element of Klass::_primary_supers. Return its (constant) value. 2063 // (Folds up type checking code.) 2064 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 2065 ciKlass *ss = klass->super_of_depth(depth); 2066 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 2067 } 2068 } 2069 } 2070 2071 // If the type is enough to determine that the thing is not an array, 2072 // we can give the layout_helper a positive interval type. 2073 // This will help short-circuit some reflective code. 2074 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 2075 && !klass->is_array_klass() // not directly typed as an array 2076 && !klass->is_interface() // specifically not Serializable & Cloneable 2077 && !klass->is_java_lang_Object() // not the supertype of all T[] 2078 ) { 2079 // Note: When interfaces are reliable, we can narrow the interface 2080 // test to (klass != Serializable && klass != Cloneable). 2081 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 2082 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 2083 // The key property of this type is that it folds up tests 2084 // for array-ness, since it proves that the layout_helper is positive. 2085 // Thus, a generic value like the basic object layout helper works fine. 2086 return TypeInt::make(min_size, max_jint, Type::WidenMin); 2087 } 2088 } 2089 2090 // If we are loading from a freshly-allocated object, produce a zero, 2091 // if the load is provably beyond the header of the object. 2092 // (Also allow a variable load from a fresh array to produce zero.) 2093 const TypeOopPtr *tinst = tp->isa_oopptr(); 2094 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 2095 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 2096 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 2097 Node* value = can_see_stored_value(mem,phase); 2098 if (value != NULL && value->is_Con()) { 2099 assert(value->bottom_type()->higher_equal(_type),"sanity"); 2100 return value->bottom_type(); 2101 } 2102 } 2103 2104 bool is_vect = (_type->isa_vect() != NULL); 2105 if (is_instance && !is_vect) { 2106 // If we have an instance type and our memory input is the 2107 // programs's initial memory state, there is no matching store, 2108 // so just return a zero of the appropriate type - 2109 // except if it is vectorized - then we have no zero constant. 2110 Node *mem = in(MemNode::Memory); 2111 if (mem->is_Parm() && mem->in(0)->is_Start()) { 2112 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 2113 return Type::get_zero_type(_type->basic_type()); 2114 } 2115 } 2116 2117 Node* alloc = is_new_object_mark_load(phase); 2118 if (alloc != NULL && !(alloc->Opcode() == Op_Allocate && UseBiasedLocking) && !UseCompactObjectHeaders) { 2119 return TypeX::make(markWord::prototype().value()); 2120 } 2121 2122 return _type; 2123 } 2124 2125 //------------------------------match_edge------------------------------------- 2126 // Do we Match on this edge index or not? Match only the address. 2127 uint LoadNode::match_edge(uint idx) const { 2128 return idx == MemNode::Address; 2129 } 2130 2131 //--------------------------LoadBNode::Ideal-------------------------------------- 2132 // 2133 // If the previous store is to the same address as this load, 2134 // and the value stored was larger than a byte, replace this load 2135 // with the value stored truncated to a byte. If no truncation is 2136 // needed, the replacement is done in LoadNode::Identity(). 2137 // 2138 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2139 Node* mem = in(MemNode::Memory); 2140 Node* value = can_see_stored_value(mem,phase); 2141 if (value != NULL) { 2142 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false); 2143 if (narrow != value) { 2144 return narrow; 2145 } 2146 } 2147 // Identity call will handle the case where truncation is not needed. 2148 return LoadNode::Ideal(phase, can_reshape); 2149 } 2150 2151 const Type* LoadBNode::Value(PhaseGVN* phase) const { 2152 Node* mem = in(MemNode::Memory); 2153 Node* value = can_see_stored_value(mem,phase); 2154 if (value != NULL && value->is_Con() && 2155 !value->bottom_type()->higher_equal(_type)) { 2156 // If the input to the store does not fit with the load's result type, 2157 // it must be truncated. We can't delay until Ideal call since 2158 // a singleton Value is needed for split_thru_phi optimization. 2159 int con = value->get_int(); 2160 return TypeInt::make((con << 24) >> 24); 2161 } 2162 return LoadNode::Value(phase); 2163 } 2164 2165 //--------------------------LoadUBNode::Ideal------------------------------------- 2166 // 2167 // If the previous store is to the same address as this load, 2168 // and the value stored was larger than a byte, replace this load 2169 // with the value stored truncated to a byte. If no truncation is 2170 // needed, the replacement is done in LoadNode::Identity(). 2171 // 2172 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2173 Node* mem = in(MemNode::Memory); 2174 Node* value = can_see_stored_value(mem, phase); 2175 if (value != NULL) { 2176 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false); 2177 if (narrow != value) { 2178 return narrow; 2179 } 2180 } 2181 // Identity call will handle the case where truncation is not needed. 2182 return LoadNode::Ideal(phase, can_reshape); 2183 } 2184 2185 const Type* LoadUBNode::Value(PhaseGVN* phase) const { 2186 Node* mem = in(MemNode::Memory); 2187 Node* value = can_see_stored_value(mem,phase); 2188 if (value != NULL && value->is_Con() && 2189 !value->bottom_type()->higher_equal(_type)) { 2190 // If the input to the store does not fit with the load's result type, 2191 // it must be truncated. We can't delay until Ideal call since 2192 // a singleton Value is needed for split_thru_phi optimization. 2193 int con = value->get_int(); 2194 return TypeInt::make(con & 0xFF); 2195 } 2196 return LoadNode::Value(phase); 2197 } 2198 2199 //--------------------------LoadUSNode::Ideal------------------------------------- 2200 // 2201 // If the previous store is to the same address as this load, 2202 // and the value stored was larger than a char, replace this load 2203 // with the value stored truncated to a char. If no truncation is 2204 // needed, the replacement is done in LoadNode::Identity(). 2205 // 2206 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2207 Node* mem = in(MemNode::Memory); 2208 Node* value = can_see_stored_value(mem,phase); 2209 if (value != NULL) { 2210 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false); 2211 if (narrow != value) { 2212 return narrow; 2213 } 2214 } 2215 // Identity call will handle the case where truncation is not needed. 2216 return LoadNode::Ideal(phase, can_reshape); 2217 } 2218 2219 const Type* LoadUSNode::Value(PhaseGVN* phase) const { 2220 Node* mem = in(MemNode::Memory); 2221 Node* value = can_see_stored_value(mem,phase); 2222 if (value != NULL && value->is_Con() && 2223 !value->bottom_type()->higher_equal(_type)) { 2224 // If the input to the store does not fit with the load's result type, 2225 // it must be truncated. We can't delay until Ideal call since 2226 // a singleton Value is needed for split_thru_phi optimization. 2227 int con = value->get_int(); 2228 return TypeInt::make(con & 0xFFFF); 2229 } 2230 return LoadNode::Value(phase); 2231 } 2232 2233 //--------------------------LoadSNode::Ideal-------------------------------------- 2234 // 2235 // If the previous store is to the same address as this load, 2236 // and the value stored was larger than a short, replace this load 2237 // with the value stored truncated to a short. If no truncation is 2238 // needed, the replacement is done in LoadNode::Identity(). 2239 // 2240 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) { 2241 Node* mem = in(MemNode::Memory); 2242 Node* value = can_see_stored_value(mem,phase); 2243 if (value != NULL) { 2244 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false); 2245 if (narrow != value) { 2246 return narrow; 2247 } 2248 } 2249 // Identity call will handle the case where truncation is not needed. 2250 return LoadNode::Ideal(phase, can_reshape); 2251 } 2252 2253 const Type* LoadSNode::Value(PhaseGVN* phase) const { 2254 Node* mem = in(MemNode::Memory); 2255 Node* value = can_see_stored_value(mem,phase); 2256 if (value != NULL && value->is_Con() && 2257 !value->bottom_type()->higher_equal(_type)) { 2258 // If the input to the store does not fit with the load's result type, 2259 // it must be truncated. We can't delay until Ideal call since 2260 // a singleton Value is needed for split_thru_phi optimization. 2261 int con = value->get_int(); 2262 return TypeInt::make((con << 16) >> 16); 2263 } 2264 return LoadNode::Value(phase); 2265 } 2266 2267 //============================================================================= 2268 //----------------------------LoadKlassNode::make------------------------------ 2269 // Polymorphic factory method: 2270 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2271 // sanity check the alias category against the created node type 2272 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2273 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2274 #ifdef _LP64 2275 if (adr_type->is_ptr_to_narrowklass()) { 2276 assert(UseCompressedClassPointers, "no compressed klasses"); 2277 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2278 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2279 } 2280 #endif 2281 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2282 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2283 } 2284 2285 //------------------------------Value------------------------------------------ 2286 const Type* LoadKlassNode::Value(PhaseGVN* phase) const { 2287 return klass_value_common(phase); 2288 } 2289 2290 // In most cases, LoadKlassNode does not have the control input set. If the control 2291 // input is set, it must not be removed (by LoadNode::Ideal()). 2292 bool LoadKlassNode::can_remove_control() const { 2293 return false; 2294 } 2295 2296 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const { 2297 // Either input is TOP ==> the result is TOP 2298 const Type *t1 = phase->type( in(MemNode::Memory) ); 2299 if (t1 == Type::TOP) return Type::TOP; 2300 Node *adr = in(MemNode::Address); 2301 const Type *t2 = phase->type( adr ); 2302 if (t2 == Type::TOP) return Type::TOP; 2303 const TypePtr *tp = t2->is_ptr(); 2304 if (TypePtr::above_centerline(tp->ptr()) || 2305 tp->ptr() == TypePtr::Null) return Type::TOP; 2306 2307 // Return a more precise klass, if possible 2308 const TypeInstPtr *tinst = tp->isa_instptr(); 2309 if (tinst != NULL) { 2310 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2311 int offset = tinst->offset(); 2312 if (ik == phase->C->env()->Class_klass() 2313 && (offset == java_lang_Class::klass_offset() || 2314 offset == java_lang_Class::array_klass_offset())) { 2315 // We are loading a special hidden field from a Class mirror object, 2316 // the field which points to the VM's Klass metaobject. 2317 ciType* t = tinst->java_mirror_type(); 2318 // java_mirror_type returns non-null for compile-time Class constants. 2319 if (t != NULL) { 2320 // constant oop => constant klass 2321 if (offset == java_lang_Class::array_klass_offset()) { 2322 if (t->is_void()) { 2323 // We cannot create a void array. Since void is a primitive type return null 2324 // klass. Users of this result need to do a null check on the returned klass. 2325 return TypePtr::NULL_PTR; 2326 } 2327 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2328 } 2329 if (!t->is_klass()) { 2330 // a primitive Class (e.g., int.class) has NULL for a klass field 2331 return TypePtr::NULL_PTR; 2332 } 2333 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2334 return TypeKlassPtr::make(t->as_klass()); 2335 } 2336 // non-constant mirror, so we can't tell what's going on 2337 } 2338 if( !ik->is_loaded() ) 2339 return _type; // Bail out if not loaded 2340 if (offset == oopDesc::klass_offset_in_bytes()) { 2341 if (tinst->klass_is_exact()) { 2342 return TypeKlassPtr::make(ik); 2343 } 2344 // See if we can become precise: no subklasses and no interface 2345 // (Note: We need to support verified interfaces.) 2346 if (!ik->is_interface() && !ik->has_subklass()) { 2347 // Add a dependence; if any subclass added we need to recompile 2348 if (!ik->is_final()) { 2349 // %%% should use stronger assert_unique_concrete_subtype instead 2350 phase->C->dependencies()->assert_leaf_type(ik); 2351 } 2352 // Return precise klass 2353 return TypeKlassPtr::make(ik); 2354 } 2355 2356 // Return root of possible klass 2357 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2358 } 2359 } 2360 2361 // Check for loading klass from an array 2362 const TypeAryPtr *tary = tp->isa_aryptr(); 2363 if( tary != NULL ) { 2364 ciKlass *tary_klass = tary->klass(); 2365 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2366 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2367 if (tary->klass_is_exact()) { 2368 return TypeKlassPtr::make(tary_klass); 2369 } 2370 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2371 // If the klass is an object array, we defer the question to the 2372 // array component klass. 2373 if( ak->is_obj_array_klass() ) { 2374 assert( ak->is_loaded(), "" ); 2375 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2376 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2377 ciInstanceKlass* ik = base_k->as_instance_klass(); 2378 // See if we can become precise: no subklasses and no interface 2379 if (!ik->is_interface() && !ik->has_subklass()) { 2380 // Add a dependence; if any subclass added we need to recompile 2381 if (!ik->is_final()) { 2382 phase->C->dependencies()->assert_leaf_type(ik); 2383 } 2384 // Return precise array klass 2385 return TypeKlassPtr::make(ak); 2386 } 2387 } 2388 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2389 } else { // Found a type-array? 2390 assert( ak->is_type_array_klass(), "" ); 2391 return TypeKlassPtr::make(ak); // These are always precise 2392 } 2393 } 2394 } 2395 2396 // Check for loading klass from an array klass 2397 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2398 if (tkls != NULL && !StressReflectiveCode) { 2399 ciKlass* klass = tkls->klass(); 2400 if( !klass->is_loaded() ) 2401 return _type; // Bail out if not loaded 2402 if( klass->is_obj_array_klass() && 2403 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2404 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2405 // // Always returning precise element type is incorrect, 2406 // // e.g., element type could be object and array may contain strings 2407 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2408 2409 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2410 // according to the element type's subclassing. 2411 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2412 } 2413 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2414 tkls->offset() == in_bytes(Klass::super_offset())) { 2415 ciKlass* sup = klass->as_instance_klass()->super(); 2416 // The field is Klass::_super. Return its (constant) value. 2417 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2418 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2419 } 2420 } 2421 2422 // Bailout case 2423 return LoadNode::Value(phase); 2424 } 2425 2426 //------------------------------Identity--------------------------------------- 2427 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2428 // Also feed through the klass in Allocate(...klass...)._klass. 2429 Node* LoadKlassNode::Identity(PhaseGVN* phase) { 2430 return klass_identity_common(phase); 2431 } 2432 2433 Node* LoadNode::klass_identity_common(PhaseGVN* phase) { 2434 Node* x = LoadNode::Identity(phase); 2435 if (x != this) return x; 2436 2437 // Take apart the address into an oop and and offset. 2438 // Return 'this' if we cannot. 2439 Node* adr = in(MemNode::Address); 2440 intptr_t offset = 0; 2441 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2442 if (base == NULL) return this; 2443 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2444 if (toop == NULL) return this; 2445 2446 // Step over potential GC barrier for OopHandle resolve 2447 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 2448 if (bs->is_gc_barrier_node(base)) { 2449 base = bs->step_over_gc_barrier(base); 2450 } 2451 2452 // We can fetch the klass directly through an AllocateNode. 2453 // This works even if the klass is not constant (clone or newArray). 2454 if (offset == oopDesc::klass_offset_in_bytes()) { 2455 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2456 if (allocated_klass != NULL) { 2457 return allocated_klass; 2458 } 2459 } 2460 2461 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2462 // See inline_native_Class_query for occurrences of these patterns. 2463 // Java Example: x.getClass().isAssignableFrom(y) 2464 // 2465 // This improves reflective code, often making the Class 2466 // mirror go completely dead. (Current exception: Class 2467 // mirrors may appear in debug info, but we could clean them out by 2468 // introducing a new debug info operator for Klass.java_mirror). 2469 2470 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2471 && offset == java_lang_Class::klass_offset()) { 2472 if (base->is_Load()) { 2473 Node* base2 = base->in(MemNode::Address); 2474 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */ 2475 Node* adr2 = base2->in(MemNode::Address); 2476 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2477 if (tkls != NULL && !tkls->empty() 2478 && (tkls->klass()->is_instance_klass() || 2479 tkls->klass()->is_array_klass()) 2480 && adr2->is_AddP() 2481 ) { 2482 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2483 if (tkls->offset() == mirror_field) { 2484 return adr2->in(AddPNode::Base); 2485 } 2486 } 2487 } 2488 } 2489 } 2490 2491 return this; 2492 } 2493 2494 2495 //------------------------------Value------------------------------------------ 2496 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const { 2497 const Type *t = klass_value_common(phase); 2498 if (t == Type::TOP) 2499 return t; 2500 2501 return t->make_narrowklass(); 2502 } 2503 2504 //------------------------------Identity--------------------------------------- 2505 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2506 // Also feed through the klass in Allocate(...klass...)._klass. 2507 Node* LoadNKlassNode::Identity(PhaseGVN* phase) { 2508 Node *x = klass_identity_common(phase); 2509 2510 const Type *t = phase->type( x ); 2511 if( t == Type::TOP ) return x; 2512 if( t->isa_narrowklass()) return x; 2513 assert (!t->isa_narrowoop(), "no narrow oop here"); 2514 2515 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2516 } 2517 2518 //------------------------------Value----------------------------------------- 2519 const Type* LoadRangeNode::Value(PhaseGVN* phase) const { 2520 // Either input is TOP ==> the result is TOP 2521 const Type *t1 = phase->type( in(MemNode::Memory) ); 2522 if( t1 == Type::TOP ) return Type::TOP; 2523 Node *adr = in(MemNode::Address); 2524 const Type *t2 = phase->type( adr ); 2525 if( t2 == Type::TOP ) return Type::TOP; 2526 const TypePtr *tp = t2->is_ptr(); 2527 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2528 const TypeAryPtr *tap = tp->isa_aryptr(); 2529 if( !tap ) return _type; 2530 return tap->size(); 2531 } 2532 2533 //-------------------------------Ideal--------------------------------------- 2534 // Feed through the length in AllocateArray(...length...)._length. 2535 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2536 Node* p = MemNode::Ideal_common(phase, can_reshape); 2537 if (p) return (p == NodeSentinel) ? NULL : p; 2538 2539 // Take apart the address into an oop and and offset. 2540 // Return 'this' if we cannot. 2541 Node* adr = in(MemNode::Address); 2542 intptr_t offset = 0; 2543 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2544 if (base == NULL) return NULL; 2545 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2546 if (tary == NULL) return NULL; 2547 2548 // We can fetch the length directly through an AllocateArrayNode. 2549 // This works even if the length is not constant (clone or newArray). 2550 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2551 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2552 if (alloc != NULL) { 2553 Node* allocated_length = alloc->Ideal_length(); 2554 Node* len = alloc->make_ideal_length(tary, phase); 2555 if (allocated_length != len) { 2556 // New CastII improves on this. 2557 return len; 2558 } 2559 } 2560 } 2561 2562 return NULL; 2563 } 2564 2565 //------------------------------Identity--------------------------------------- 2566 // Feed through the length in AllocateArray(...length...)._length. 2567 Node* LoadRangeNode::Identity(PhaseGVN* phase) { 2568 Node* x = LoadINode::Identity(phase); 2569 if (x != this) return x; 2570 2571 // Take apart the address into an oop and and offset. 2572 // Return 'this' if we cannot. 2573 Node* adr = in(MemNode::Address); 2574 intptr_t offset = 0; 2575 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2576 if (base == NULL) return this; 2577 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2578 if (tary == NULL) return this; 2579 2580 // We can fetch the length directly through an AllocateArrayNode. 2581 // This works even if the length is not constant (clone or newArray). 2582 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2583 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2584 if (alloc != NULL) { 2585 Node* allocated_length = alloc->Ideal_length(); 2586 // Do not allow make_ideal_length to allocate a CastII node. 2587 Node* len = alloc->make_ideal_length(tary, phase, false); 2588 if (allocated_length == len) { 2589 // Return allocated_length only if it would not be improved by a CastII. 2590 return allocated_length; 2591 } 2592 } 2593 } 2594 2595 return this; 2596 2597 } 2598 2599 //============================================================================= 2600 //---------------------------StoreNode::make----------------------------------- 2601 // Polymorphic factory method: 2602 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo, bool require_atomic_access) { 2603 assert((mo == unordered || mo == release), "unexpected"); 2604 Compile* C = gvn.C; 2605 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2606 ctl != NULL, "raw memory operations should have control edge"); 2607 2608 switch (bt) { 2609 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case 2610 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2611 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2612 case T_CHAR: 2613 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2614 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access); 2615 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2616 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access); 2617 case T_METADATA: 2618 case T_ADDRESS: 2619 case T_OBJECT: 2620 #ifdef _LP64 2621 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2622 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2623 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2624 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2625 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2626 adr->bottom_type()->isa_rawptr())) { 2627 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2628 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2629 } 2630 #endif 2631 { 2632 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2633 } 2634 default: 2635 ShouldNotReachHere(); 2636 return (StoreNode*)NULL; 2637 } 2638 } 2639 2640 //--------------------------bottom_type---------------------------------------- 2641 const Type *StoreNode::bottom_type() const { 2642 return Type::MEMORY; 2643 } 2644 2645 //------------------------------hash------------------------------------------- 2646 uint StoreNode::hash() const { 2647 // unroll addition of interesting fields 2648 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2649 2650 // Since they are not commoned, do not hash them: 2651 return NO_HASH; 2652 } 2653 2654 //------------------------------Ideal------------------------------------------ 2655 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2656 // When a store immediately follows a relevant allocation/initialization, 2657 // try to capture it into the initialization, or hoist it above. 2658 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2659 Node* p = MemNode::Ideal_common(phase, can_reshape); 2660 if (p) return (p == NodeSentinel) ? NULL : p; 2661 2662 Node* mem = in(MemNode::Memory); 2663 Node* address = in(MemNode::Address); 2664 Node* value = in(MemNode::ValueIn); 2665 // Back-to-back stores to same address? Fold em up. Generally 2666 // unsafe if I have intervening uses... Also disallowed for StoreCM 2667 // since they must follow each StoreP operation. Redundant StoreCMs 2668 // are eliminated just before matching in final_graph_reshape. 2669 { 2670 Node* st = mem; 2671 // If Store 'st' has more than one use, we cannot fold 'st' away. 2672 // For example, 'st' might be the final state at a conditional 2673 // return. Or, 'st' might be used by some node which is live at 2674 // the same time 'st' is live, which might be unschedulable. So, 2675 // require exactly ONE user until such time as we clone 'mem' for 2676 // each of 'mem's uses (thus making the exactly-1-user-rule hold 2677 // true). 2678 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) { 2679 // Looking at a dead closed cycle of memory? 2680 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2681 assert(Opcode() == st->Opcode() || 2682 st->Opcode() == Op_StoreVector || 2683 Opcode() == Op_StoreVector || 2684 st->Opcode() == Op_StoreVectorScatter || 2685 Opcode() == Op_StoreVectorScatter || 2686 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw || 2687 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode 2688 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy 2689 (is_mismatched_access() || st->as_Store()->is_mismatched_access()), 2690 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]); 2691 2692 if (st->in(MemNode::Address)->eqv_uncast(address) && 2693 st->as_Store()->memory_size() <= this->memory_size()) { 2694 Node* use = st->raw_out(0); 2695 if (phase->is_IterGVN()) { 2696 phase->is_IterGVN()->rehash_node_delayed(use); 2697 } 2698 // It's OK to do this in the parser, since DU info is always accurate, 2699 // and the parser always refers to nodes via SafePointNode maps. 2700 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase); 2701 return this; 2702 } 2703 st = st->in(MemNode::Memory); 2704 } 2705 } 2706 2707 2708 // Capture an unaliased, unconditional, simple store into an initializer. 2709 // Or, if it is independent of the allocation, hoist it above the allocation. 2710 if (ReduceFieldZeroing && /*can_reshape &&*/ 2711 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2712 InitializeNode* init = mem->in(0)->as_Initialize(); 2713 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2714 if (offset > 0) { 2715 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2716 // If the InitializeNode captured me, it made a raw copy of me, 2717 // and I need to disappear. 2718 if (moved != NULL) { 2719 // %%% hack to ensure that Ideal returns a new node: 2720 mem = MergeMemNode::make(mem); 2721 return mem; // fold me away 2722 } 2723 } 2724 } 2725 2726 // Fold reinterpret cast into memory operation: 2727 // StoreX mem (MoveY2X v) => StoreY mem v 2728 if (value->is_Move()) { 2729 const Type* vt = value->in(1)->bottom_type(); 2730 if (has_reinterpret_variant(vt)) { 2731 if (phase->C->post_loop_opts_phase()) { 2732 return convert_to_reinterpret_store(*phase, value->in(1), vt); 2733 } else { 2734 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over 2735 } 2736 } 2737 } 2738 2739 return NULL; // No further progress 2740 } 2741 2742 //------------------------------Value----------------------------------------- 2743 const Type* StoreNode::Value(PhaseGVN* phase) const { 2744 // Either input is TOP ==> the result is TOP 2745 const Type *t1 = phase->type( in(MemNode::Memory) ); 2746 if( t1 == Type::TOP ) return Type::TOP; 2747 const Type *t2 = phase->type( in(MemNode::Address) ); 2748 if( t2 == Type::TOP ) return Type::TOP; 2749 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2750 if( t3 == Type::TOP ) return Type::TOP; 2751 return Type::MEMORY; 2752 } 2753 2754 //------------------------------Identity--------------------------------------- 2755 // Remove redundant stores: 2756 // Store(m, p, Load(m, p)) changes to m. 2757 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2758 Node* StoreNode::Identity(PhaseGVN* phase) { 2759 Node* mem = in(MemNode::Memory); 2760 Node* adr = in(MemNode::Address); 2761 Node* val = in(MemNode::ValueIn); 2762 2763 Node* result = this; 2764 2765 // Load then Store? Then the Store is useless 2766 if (val->is_Load() && 2767 val->in(MemNode::Address)->eqv_uncast(adr) && 2768 val->in(MemNode::Memory )->eqv_uncast(mem) && 2769 val->as_Load()->store_Opcode() == Opcode()) { 2770 result = mem; 2771 } 2772 2773 // Two stores in a row of the same value? 2774 if (result == this && 2775 mem->is_Store() && 2776 mem->in(MemNode::Address)->eqv_uncast(adr) && 2777 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2778 mem->Opcode() == Opcode()) { 2779 result = mem; 2780 } 2781 2782 // Store of zero anywhere into a freshly-allocated object? 2783 // Then the store is useless. 2784 // (It must already have been captured by the InitializeNode.) 2785 if (result == this && 2786 ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2787 // a newly allocated object is already all-zeroes everywhere 2788 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2789 result = mem; 2790 } 2791 2792 if (result == this) { 2793 // the store may also apply to zero-bits in an earlier object 2794 Node* prev_mem = find_previous_store(phase); 2795 // Steps (a), (b): Walk past independent stores to find an exact match. 2796 if (prev_mem != NULL) { 2797 Node* prev_val = can_see_stored_value(prev_mem, phase); 2798 if (prev_val != NULL && prev_val == val) { 2799 // prev_val and val might differ by a cast; it would be good 2800 // to keep the more informative of the two. 2801 result = mem; 2802 } 2803 } 2804 } 2805 } 2806 2807 PhaseIterGVN* igvn = phase->is_IterGVN(); 2808 if (result != this && igvn != NULL) { 2809 MemBarNode* trailing = trailing_membar(); 2810 if (trailing != NULL) { 2811 #ifdef ASSERT 2812 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr(); 2813 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects"); 2814 #endif 2815 trailing->remove(igvn); 2816 } 2817 } 2818 2819 return result; 2820 } 2821 2822 //------------------------------match_edge------------------------------------- 2823 // Do we Match on this edge index or not? Match only memory & value 2824 uint StoreNode::match_edge(uint idx) const { 2825 return idx == MemNode::Address || idx == MemNode::ValueIn; 2826 } 2827 2828 //------------------------------cmp-------------------------------------------- 2829 // Do not common stores up together. They generally have to be split 2830 // back up anyways, so do not bother. 2831 bool StoreNode::cmp( const Node &n ) const { 2832 return (&n == this); // Always fail except on self 2833 } 2834 2835 //------------------------------Ideal_masked_input----------------------------- 2836 // Check for a useless mask before a partial-word store 2837 // (StoreB ... (AndI valIn conIa) ) 2838 // If (conIa & mask == mask) this simplifies to 2839 // (StoreB ... (valIn) ) 2840 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2841 Node *val = in(MemNode::ValueIn); 2842 if( val->Opcode() == Op_AndI ) { 2843 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2844 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2845 set_req_X(MemNode::ValueIn, val->in(1), phase); 2846 return this; 2847 } 2848 } 2849 return NULL; 2850 } 2851 2852 2853 //------------------------------Ideal_sign_extended_input---------------------- 2854 // Check for useless sign-extension before a partial-word store 2855 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2856 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2857 // (StoreB ... (valIn) ) 2858 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2859 Node *val = in(MemNode::ValueIn); 2860 if( val->Opcode() == Op_RShiftI ) { 2861 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2862 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2863 Node *shl = val->in(1); 2864 if( shl->Opcode() == Op_LShiftI ) { 2865 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2866 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2867 set_req_X(MemNode::ValueIn, shl->in(1), phase); 2868 return this; 2869 } 2870 } 2871 } 2872 } 2873 return NULL; 2874 } 2875 2876 //------------------------------value_never_loaded----------------------------------- 2877 // Determine whether there are any possible loads of the value stored. 2878 // For simplicity, we actually check if there are any loads from the 2879 // address stored to, not just for loads of the value stored by this node. 2880 // 2881 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2882 Node *adr = in(Address); 2883 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2884 if (adr_oop == NULL) 2885 return false; 2886 if (!adr_oop->is_known_instance_field()) 2887 return false; // if not a distinct instance, there may be aliases of the address 2888 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2889 Node *use = adr->fast_out(i); 2890 if (use->is_Load() || use->is_LoadStore()) { 2891 return false; 2892 } 2893 } 2894 return true; 2895 } 2896 2897 MemBarNode* StoreNode::trailing_membar() const { 2898 if (is_release()) { 2899 MemBarNode* trailing_mb = NULL; 2900 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2901 Node* u = fast_out(i); 2902 if (u->is_MemBar()) { 2903 if (u->as_MemBar()->trailing_store()) { 2904 assert(u->Opcode() == Op_MemBarVolatile, ""); 2905 assert(trailing_mb == NULL, "only one"); 2906 trailing_mb = u->as_MemBar(); 2907 #ifdef ASSERT 2908 Node* leading = u->as_MemBar()->leading_membar(); 2909 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 2910 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair"); 2911 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair"); 2912 #endif 2913 } else { 2914 assert(u->as_MemBar()->standalone(), ""); 2915 } 2916 } 2917 } 2918 return trailing_mb; 2919 } 2920 return NULL; 2921 } 2922 2923 2924 //============================================================================= 2925 //------------------------------Ideal------------------------------------------ 2926 // If the store is from an AND mask that leaves the low bits untouched, then 2927 // we can skip the AND operation. If the store is from a sign-extension 2928 // (a left shift, then right shift) we can skip both. 2929 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2930 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2931 if( progress != NULL ) return progress; 2932 2933 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2934 if( progress != NULL ) return progress; 2935 2936 // Finally check the default case 2937 return StoreNode::Ideal(phase, can_reshape); 2938 } 2939 2940 //============================================================================= 2941 //------------------------------Ideal------------------------------------------ 2942 // If the store is from an AND mask that leaves the low bits untouched, then 2943 // we can skip the AND operation 2944 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2945 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2946 if( progress != NULL ) return progress; 2947 2948 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2949 if( progress != NULL ) return progress; 2950 2951 // Finally check the default case 2952 return StoreNode::Ideal(phase, can_reshape); 2953 } 2954 2955 //============================================================================= 2956 //------------------------------Identity--------------------------------------- 2957 Node* StoreCMNode::Identity(PhaseGVN* phase) { 2958 // No need to card mark when storing a null ptr 2959 Node* my_store = in(MemNode::OopStore); 2960 if (my_store->is_Store()) { 2961 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2962 if( t1 == TypePtr::NULL_PTR ) { 2963 return in(MemNode::Memory); 2964 } 2965 } 2966 return this; 2967 } 2968 2969 //============================================================================= 2970 //------------------------------Ideal--------------------------------------- 2971 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2972 Node* progress = StoreNode::Ideal(phase, can_reshape); 2973 if (progress != NULL) return progress; 2974 2975 Node* my_store = in(MemNode::OopStore); 2976 if (my_store->is_MergeMem()) { 2977 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2978 set_req_X(MemNode::OopStore, mem, phase); 2979 return this; 2980 } 2981 2982 return NULL; 2983 } 2984 2985 //------------------------------Value----------------------------------------- 2986 const Type* StoreCMNode::Value(PhaseGVN* phase) const { 2987 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value). 2988 // If extra input is TOP ==> the result is TOP 2989 const Type* t = phase->type(in(MemNode::OopStore)); 2990 if (t == Type::TOP) { 2991 return Type::TOP; 2992 } 2993 return StoreNode::Value(phase); 2994 } 2995 2996 2997 //============================================================================= 2998 //----------------------------------SCMemProjNode------------------------------ 2999 const Type* SCMemProjNode::Value(PhaseGVN* phase) const 3000 { 3001 if (in(0) == NULL || phase->type(in(0)) == Type::TOP) { 3002 return Type::TOP; 3003 } 3004 return bottom_type(); 3005 } 3006 3007 //============================================================================= 3008 //----------------------------------LoadStoreNode------------------------------ 3009 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 3010 : Node(required), 3011 _type(rt), 3012 _adr_type(at), 3013 _barrier_data(0) 3014 { 3015 init_req(MemNode::Control, c ); 3016 init_req(MemNode::Memory , mem); 3017 init_req(MemNode::Address, adr); 3018 init_req(MemNode::ValueIn, val); 3019 init_class_id(Class_LoadStore); 3020 } 3021 3022 //------------------------------Value----------------------------------------- 3023 const Type* LoadStoreNode::Value(PhaseGVN* phase) const { 3024 // Either input is TOP ==> the result is TOP 3025 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) { 3026 return Type::TOP; 3027 } 3028 const Type* t = phase->type(in(MemNode::Memory)); 3029 if (t == Type::TOP) { 3030 return Type::TOP; 3031 } 3032 t = phase->type(in(MemNode::Address)); 3033 if (t == Type::TOP) { 3034 return Type::TOP; 3035 } 3036 t = phase->type(in(MemNode::ValueIn)); 3037 if (t == Type::TOP) { 3038 return Type::TOP; 3039 } 3040 return bottom_type(); 3041 } 3042 3043 uint LoadStoreNode::ideal_reg() const { 3044 return _type->ideal_reg(); 3045 } 3046 3047 bool LoadStoreNode::result_not_used() const { 3048 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 3049 Node *x = fast_out(i); 3050 if (x->Opcode() == Op_SCMemProj) continue; 3051 return false; 3052 } 3053 return true; 3054 } 3055 3056 MemBarNode* LoadStoreNode::trailing_membar() const { 3057 MemBarNode* trailing = NULL; 3058 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 3059 Node* u = fast_out(i); 3060 if (u->is_MemBar()) { 3061 if (u->as_MemBar()->trailing_load_store()) { 3062 assert(u->Opcode() == Op_MemBarAcquire, ""); 3063 assert(trailing == NULL, "only one"); 3064 trailing = u->as_MemBar(); 3065 #ifdef ASSERT 3066 Node* leading = trailing->leading_membar(); 3067 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar"); 3068 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair"); 3069 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair"); 3070 #endif 3071 } else { 3072 assert(u->as_MemBar()->standalone(), "wrong barrier kind"); 3073 } 3074 } 3075 } 3076 3077 return trailing; 3078 } 3079 3080 uint LoadStoreNode::size_of() const { return sizeof(*this); } 3081 3082 //============================================================================= 3083 //----------------------------------LoadStoreConditionalNode-------------------- 3084 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 3085 init_req(ExpectedIn, ex ); 3086 } 3087 3088 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const { 3089 // Either input is TOP ==> the result is TOP 3090 const Type* t = phase->type(in(ExpectedIn)); 3091 if (t == Type::TOP) { 3092 return Type::TOP; 3093 } 3094 return LoadStoreNode::Value(phase); 3095 } 3096 3097 //============================================================================= 3098 //-------------------------------adr_type-------------------------------------- 3099 const TypePtr* ClearArrayNode::adr_type() const { 3100 Node *adr = in(3); 3101 if (adr == NULL) return NULL; // node is dead 3102 return MemNode::calculate_adr_type(adr->bottom_type()); 3103 } 3104 3105 //------------------------------match_edge------------------------------------- 3106 // Do we Match on this edge index or not? Do not match memory 3107 uint ClearArrayNode::match_edge(uint idx) const { 3108 return idx > 1; 3109 } 3110 3111 //------------------------------Identity--------------------------------------- 3112 // Clearing a zero length array does nothing 3113 Node* ClearArrayNode::Identity(PhaseGVN* phase) { 3114 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 3115 } 3116 3117 //------------------------------Idealize--------------------------------------- 3118 // Clearing a short array is faster with stores 3119 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3120 // Already know this is a large node, do not try to ideal it 3121 if (_is_large) return NULL; 3122 3123 const int unit = BytesPerLong; 3124 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 3125 if (!t) return NULL; 3126 if (!t->is_con()) return NULL; 3127 intptr_t raw_count = t->get_con(); 3128 intptr_t size = raw_count; 3129 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 3130 // Clearing nothing uses the Identity call. 3131 // Negative clears are possible on dead ClearArrays 3132 // (see jck test stmt114.stmt11402.val). 3133 if (size <= 0 || size % unit != 0) return NULL; 3134 intptr_t count = size / unit; 3135 // Length too long; communicate this to matchers and assemblers. 3136 // Assemblers are responsible to produce fast hardware clears for it. 3137 if (size > InitArrayShortSize) { 3138 return new ClearArrayNode(in(0), in(1), in(2), in(3), true); 3139 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) { 3140 return NULL; 3141 } 3142 if (!IdealizeClearArrayNode) return NULL; 3143 Node *mem = in(1); 3144 if( phase->type(mem)==Type::TOP ) return NULL; 3145 Node *adr = in(3); 3146 const Type* at = phase->type(adr); 3147 if( at==Type::TOP ) return NULL; 3148 const TypePtr* atp = at->isa_ptr(); 3149 // adjust atp to be the correct array element address type 3150 if (atp == NULL) atp = TypePtr::BOTTOM; 3151 else atp = atp->add_offset(Type::OffsetBot); 3152 // Get base for derived pointer purposes 3153 if( adr->Opcode() != Op_AddP ) Unimplemented(); 3154 Node *base = adr->in(1); 3155 3156 Node *zero = phase->makecon(TypeLong::ZERO); 3157 Node *off = phase->MakeConX(BytesPerLong); 3158 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 3159 count--; 3160 while( count-- ) { 3161 mem = phase->transform(mem); 3162 adr = phase->transform(new AddPNode(base,adr,off)); 3163 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 3164 } 3165 return mem; 3166 } 3167 3168 //----------------------------step_through---------------------------------- 3169 // Return allocation input memory edge if it is different instance 3170 // or itself if it is the one we are looking for. 3171 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 3172 Node* n = *np; 3173 assert(n->is_ClearArray(), "sanity"); 3174 intptr_t offset; 3175 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 3176 // This method is called only before Allocate nodes are expanded 3177 // during macro nodes expansion. Before that ClearArray nodes are 3178 // only generated in PhaseMacroExpand::generate_arraycopy() (before 3179 // Allocate nodes are expanded) which follows allocations. 3180 assert(alloc != NULL, "should have allocation"); 3181 if (alloc->_idx == instance_id) { 3182 // Can not bypass initialization of the instance we are looking for. 3183 return false; 3184 } 3185 // Otherwise skip it. 3186 InitializeNode* init = alloc->initialization(); 3187 if (init != NULL) 3188 *np = init->in(TypeFunc::Memory); 3189 else 3190 *np = alloc->in(TypeFunc::Memory); 3191 return true; 3192 } 3193 3194 //----------------------------clear_memory------------------------------------- 3195 // Generate code to initialize object storage to zero. 3196 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3197 intptr_t start_offset, 3198 Node* end_offset, 3199 PhaseGVN* phase) { 3200 intptr_t offset = start_offset; 3201 3202 int unit = BytesPerLong; 3203 if ((offset % unit) != 0) { 3204 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 3205 adr = phase->transform(adr); 3206 const TypePtr* atp = TypeRawPtr::BOTTOM; 3207 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 3208 mem = phase->transform(mem); 3209 offset += BytesPerInt; 3210 } 3211 assert((offset % unit) == 0, ""); 3212 3213 // Initialize the remaining stuff, if any, with a ClearArray. 3214 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 3215 } 3216 3217 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3218 Node* start_offset, 3219 Node* end_offset, 3220 PhaseGVN* phase) { 3221 if (start_offset == end_offset) { 3222 // nothing to do 3223 return mem; 3224 } 3225 3226 int unit = BytesPerLong; 3227 Node* zbase = start_offset; 3228 Node* zend = end_offset; 3229 3230 // Scale to the unit required by the CPU: 3231 if (!Matcher::init_array_count_is_in_bytes) { 3232 Node* shift = phase->intcon(exact_log2(unit)); 3233 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 3234 zend = phase->transform(new URShiftXNode(zend, shift) ); 3235 } 3236 3237 // Bulk clear double-words 3238 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 3239 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 3240 mem = new ClearArrayNode(ctl, mem, zsize, adr, false); 3241 return phase->transform(mem); 3242 } 3243 3244 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 3245 intptr_t start_offset, 3246 intptr_t end_offset, 3247 PhaseGVN* phase) { 3248 if (start_offset == end_offset) { 3249 // nothing to do 3250 return mem; 3251 } 3252 3253 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 3254 intptr_t done_offset = end_offset; 3255 if ((done_offset % BytesPerLong) != 0) { 3256 done_offset -= BytesPerInt; 3257 } 3258 if (done_offset > start_offset) { 3259 mem = clear_memory(ctl, mem, dest, 3260 start_offset, phase->MakeConX(done_offset), phase); 3261 } 3262 if (done_offset < end_offset) { // emit the final 32-bit store 3263 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 3264 adr = phase->transform(adr); 3265 const TypePtr* atp = TypeRawPtr::BOTTOM; 3266 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 3267 mem = phase->transform(mem); 3268 done_offset += BytesPerInt; 3269 } 3270 assert(done_offset == end_offset, ""); 3271 return mem; 3272 } 3273 3274 //============================================================================= 3275 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 3276 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 3277 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone) 3278 #ifdef ASSERT 3279 , _pair_idx(0) 3280 #endif 3281 { 3282 init_class_id(Class_MemBar); 3283 Node* top = C->top(); 3284 init_req(TypeFunc::I_O,top); 3285 init_req(TypeFunc::FramePtr,top); 3286 init_req(TypeFunc::ReturnAdr,top); 3287 if (precedent != NULL) 3288 init_req(TypeFunc::Parms, precedent); 3289 } 3290 3291 //------------------------------cmp-------------------------------------------- 3292 uint MemBarNode::hash() const { return NO_HASH; } 3293 bool MemBarNode::cmp( const Node &n ) const { 3294 return (&n == this); // Always fail except on self 3295 } 3296 3297 //------------------------------make------------------------------------------- 3298 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 3299 switch (opcode) { 3300 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 3301 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 3302 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 3303 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 3304 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 3305 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn); 3306 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 3307 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 3308 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 3309 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 3310 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn); 3311 case Op_Initialize: return new InitializeNode(C, atp, pn); 3312 default: ShouldNotReachHere(); return NULL; 3313 } 3314 } 3315 3316 void MemBarNode::remove(PhaseIterGVN *igvn) { 3317 if (outcnt() != 2) { 3318 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory"); 3319 assert(outcnt() == 1, "Only control then"); 3320 } 3321 if (trailing_store() || trailing_load_store()) { 3322 MemBarNode* leading = leading_membar(); 3323 if (leading != NULL) { 3324 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars"); 3325 leading->remove(igvn); 3326 } 3327 } 3328 if (proj_out_or_null(TypeFunc::Memory) != NULL) { 3329 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 3330 } 3331 if (proj_out_or_null(TypeFunc::Control) != NULL) { 3332 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 3333 } 3334 } 3335 3336 //------------------------------Ideal------------------------------------------ 3337 // Return a node which is more "ideal" than the current node. Strip out 3338 // control copies 3339 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3340 if (remove_dead_region(phase, can_reshape)) return this; 3341 // Don't bother trying to transform a dead node 3342 if (in(0) && in(0)->is_top()) { 3343 return NULL; 3344 } 3345 3346 bool progress = false; 3347 // Eliminate volatile MemBars for scalar replaced objects. 3348 if (can_reshape && req() == (Precedent+1)) { 3349 bool eliminate = false; 3350 int opc = Opcode(); 3351 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 3352 // Volatile field loads and stores. 3353 Node* my_mem = in(MemBarNode::Precedent); 3354 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 3355 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 3356 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 3357 // replace this Precedent (decodeN) with the Load instead. 3358 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 3359 Node* load_node = my_mem->in(1); 3360 set_req(MemBarNode::Precedent, load_node); 3361 phase->is_IterGVN()->_worklist.push(my_mem); 3362 my_mem = load_node; 3363 } else { 3364 assert(my_mem->unique_out() == this, "sanity"); 3365 del_req(Precedent); 3366 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 3367 my_mem = NULL; 3368 } 3369 progress = true; 3370 } 3371 if (my_mem != NULL && my_mem->is_Mem()) { 3372 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 3373 // Check for scalar replaced object reference. 3374 if( t_oop != NULL && t_oop->is_known_instance_field() && 3375 t_oop->offset() != Type::OffsetBot && 3376 t_oop->offset() != Type::OffsetTop) { 3377 eliminate = true; 3378 } 3379 } 3380 } else if (opc == Op_MemBarRelease) { 3381 // Final field stores. 3382 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 3383 if ((alloc != NULL) && alloc->is_Allocate() && 3384 alloc->as_Allocate()->does_not_escape_thread()) { 3385 // The allocated object does not escape. 3386 eliminate = true; 3387 } 3388 } 3389 if (eliminate) { 3390 // Replace MemBar projections by its inputs. 3391 PhaseIterGVN* igvn = phase->is_IterGVN(); 3392 remove(igvn); 3393 // Must return either the original node (now dead) or a new node 3394 // (Do not return a top here, since that would break the uniqueness of top.) 3395 return new ConINode(TypeInt::ZERO); 3396 } 3397 } 3398 return progress ? this : NULL; 3399 } 3400 3401 //------------------------------Value------------------------------------------ 3402 const Type* MemBarNode::Value(PhaseGVN* phase) const { 3403 if( !in(0) ) return Type::TOP; 3404 if( phase->type(in(0)) == Type::TOP ) 3405 return Type::TOP; 3406 return TypeTuple::MEMBAR; 3407 } 3408 3409 //------------------------------match------------------------------------------ 3410 // Construct projections for memory. 3411 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3412 switch (proj->_con) { 3413 case TypeFunc::Control: 3414 case TypeFunc::Memory: 3415 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3416 } 3417 ShouldNotReachHere(); 3418 return NULL; 3419 } 3420 3421 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3422 trailing->_kind = TrailingStore; 3423 leading->_kind = LeadingStore; 3424 #ifdef ASSERT 3425 trailing->_pair_idx = leading->_idx; 3426 leading->_pair_idx = leading->_idx; 3427 #endif 3428 } 3429 3430 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) { 3431 trailing->_kind = TrailingLoadStore; 3432 leading->_kind = LeadingLoadStore; 3433 #ifdef ASSERT 3434 trailing->_pair_idx = leading->_idx; 3435 leading->_pair_idx = leading->_idx; 3436 #endif 3437 } 3438 3439 MemBarNode* MemBarNode::trailing_membar() const { 3440 ResourceMark rm; 3441 Node* trailing = (Node*)this; 3442 VectorSet seen; 3443 Node_Stack multis(0); 3444 do { 3445 Node* c = trailing; 3446 uint i = 0; 3447 do { 3448 trailing = NULL; 3449 for (; i < c->outcnt(); i++) { 3450 Node* next = c->raw_out(i); 3451 if (next != c && next->is_CFG()) { 3452 if (c->is_MultiBranch()) { 3453 if (multis.node() == c) { 3454 multis.set_index(i+1); 3455 } else { 3456 multis.push(c, i+1); 3457 } 3458 } 3459 trailing = next; 3460 break; 3461 } 3462 } 3463 if (trailing != NULL && !seen.test_set(trailing->_idx)) { 3464 break; 3465 } 3466 while (multis.size() > 0) { 3467 c = multis.node(); 3468 i = multis.index(); 3469 if (i < c->req()) { 3470 break; 3471 } 3472 multis.pop(); 3473 } 3474 } while (multis.size() > 0); 3475 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing()); 3476 3477 MemBarNode* mb = trailing->as_MemBar(); 3478 assert((mb->_kind == TrailingStore && _kind == LeadingStore) || 3479 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar"); 3480 assert(mb->_pair_idx == _pair_idx, "bad trailing membar"); 3481 return mb; 3482 } 3483 3484 MemBarNode* MemBarNode::leading_membar() const { 3485 ResourceMark rm; 3486 VectorSet seen; 3487 Node_Stack regions(0); 3488 Node* leading = in(0); 3489 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) { 3490 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) { 3491 leading = NULL; 3492 while (regions.size() > 0 && leading == NULL) { 3493 Node* r = regions.node(); 3494 uint i = regions.index(); 3495 if (i < r->req()) { 3496 leading = r->in(i); 3497 regions.set_index(i+1); 3498 } else { 3499 regions.pop(); 3500 } 3501 } 3502 if (leading == NULL) { 3503 assert(regions.size() == 0, "all paths should have been tried"); 3504 return NULL; 3505 } 3506 } 3507 if (leading->is_Region()) { 3508 regions.push(leading, 2); 3509 leading = leading->in(1); 3510 } else { 3511 leading = leading->in(0); 3512 } 3513 } 3514 #ifdef ASSERT 3515 Unique_Node_List wq; 3516 wq.push((Node*)this); 3517 uint found = 0; 3518 for (uint i = 0; i < wq.size(); i++) { 3519 Node* n = wq.at(i); 3520 if (n->is_Region()) { 3521 for (uint j = 1; j < n->req(); j++) { 3522 Node* in = n->in(j); 3523 if (in != NULL && !in->is_top()) { 3524 wq.push(in); 3525 } 3526 } 3527 } else { 3528 if (n->is_MemBar() && n->as_MemBar()->leading()) { 3529 assert(n == leading, "consistency check failed"); 3530 found++; 3531 } else { 3532 Node* in = n->in(0); 3533 if (in != NULL && !in->is_top()) { 3534 wq.push(in); 3535 } 3536 } 3537 } 3538 } 3539 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed"); 3540 #endif 3541 if (leading == NULL) { 3542 return NULL; 3543 } 3544 MemBarNode* mb = leading->as_MemBar(); 3545 assert((mb->_kind == LeadingStore && _kind == TrailingStore) || 3546 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar"); 3547 assert(mb->_pair_idx == _pair_idx, "bad leading membar"); 3548 return mb; 3549 } 3550 3551 3552 //===========================InitializeNode==================================== 3553 // SUMMARY: 3554 // This node acts as a memory barrier on raw memory, after some raw stores. 3555 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 3556 // The Initialize can 'capture' suitably constrained stores as raw inits. 3557 // It can coalesce related raw stores into larger units (called 'tiles'). 3558 // It can avoid zeroing new storage for memory units which have raw inits. 3559 // At macro-expansion, it is marked 'complete', and does not optimize further. 3560 // 3561 // EXAMPLE: 3562 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3563 // ctl = incoming control; mem* = incoming memory 3564 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 3565 // First allocate uninitialized memory and fill in the header: 3566 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 3567 // ctl := alloc.Control; mem* := alloc.Memory* 3568 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 3569 // Then initialize to zero the non-header parts of the raw memory block: 3570 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3571 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3572 // After the initialize node executes, the object is ready for service: 3573 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3574 // Suppose its body is immediately initialized as {1,2}: 3575 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3576 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3577 // mem.SLICE(#short[*]) := store2 3578 // 3579 // DETAILS: 3580 // An InitializeNode collects and isolates object initialization after 3581 // an AllocateNode and before the next possible safepoint. As a 3582 // memory barrier (MemBarNode), it keeps critical stores from drifting 3583 // down past any safepoint or any publication of the allocation. 3584 // Before this barrier, a newly-allocated object may have uninitialized bits. 3585 // After this barrier, it may be treated as a real oop, and GC is allowed. 3586 // 3587 // The semantics of the InitializeNode include an implicit zeroing of 3588 // the new object from object header to the end of the object. 3589 // (The object header and end are determined by the AllocateNode.) 3590 // 3591 // Certain stores may be added as direct inputs to the InitializeNode. 3592 // These stores must update raw memory, and they must be to addresses 3593 // derived from the raw address produced by AllocateNode, and with 3594 // a constant offset. They must be ordered by increasing offset. 3595 // The first one is at in(RawStores), the last at in(req()-1). 3596 // Unlike most memory operations, they are not linked in a chain, 3597 // but are displayed in parallel as users of the rawmem output of 3598 // the allocation. 3599 // 3600 // (See comments in InitializeNode::capture_store, which continue 3601 // the example given above.) 3602 // 3603 // When the associated Allocate is macro-expanded, the InitializeNode 3604 // may be rewritten to optimize collected stores. A ClearArrayNode 3605 // may also be created at that point to represent any required zeroing. 3606 // The InitializeNode is then marked 'complete', prohibiting further 3607 // capturing of nearby memory operations. 3608 // 3609 // During macro-expansion, all captured initializations which store 3610 // constant values of 32 bits or smaller are coalesced (if advantageous) 3611 // into larger 'tiles' 32 or 64 bits. This allows an object to be 3612 // initialized in fewer memory operations. Memory words which are 3613 // covered by neither tiles nor non-constant stores are pre-zeroed 3614 // by explicit stores of zero. (The code shape happens to do all 3615 // zeroing first, then all other stores, with both sequences occurring 3616 // in order of ascending offsets.) 3617 // 3618 // Alternatively, code may be inserted between an AllocateNode and its 3619 // InitializeNode, to perform arbitrary initialization of the new object. 3620 // E.g., the object copying intrinsics insert complex data transfers here. 3621 // The initialization must then be marked as 'complete' disable the 3622 // built-in zeroing semantics and the collection of initializing stores. 3623 // 3624 // While an InitializeNode is incomplete, reads from the memory state 3625 // produced by it are optimizable if they match the control edge and 3626 // new oop address associated with the allocation/initialization. 3627 // They return a stored value (if the offset matches) or else zero. 3628 // A write to the memory state, if it matches control and address, 3629 // and if it is to a constant offset, may be 'captured' by the 3630 // InitializeNode. It is cloned as a raw memory operation and rewired 3631 // inside the initialization, to the raw oop produced by the allocation. 3632 // Operations on addresses which are provably distinct (e.g., to 3633 // other AllocateNodes) are allowed to bypass the initialization. 3634 // 3635 // The effect of all this is to consolidate object initialization 3636 // (both arrays and non-arrays, both piecewise and bulk) into a 3637 // single location, where it can be optimized as a unit. 3638 // 3639 // Only stores with an offset less than TrackedInitializationLimit words 3640 // will be considered for capture by an InitializeNode. This puts a 3641 // reasonable limit on the complexity of optimized initializations. 3642 3643 //---------------------------InitializeNode------------------------------------ 3644 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3645 : MemBarNode(C, adr_type, rawoop), 3646 _is_complete(Incomplete), _does_not_escape(false) 3647 { 3648 init_class_id(Class_Initialize); 3649 3650 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3651 assert(in(RawAddress) == rawoop, "proper init"); 3652 // Note: allocation() can be NULL, for secondary initialization barriers 3653 } 3654 3655 // Since this node is not matched, it will be processed by the 3656 // register allocator. Declare that there are no constraints 3657 // on the allocation of the RawAddress edge. 3658 const RegMask &InitializeNode::in_RegMask(uint idx) const { 3659 // This edge should be set to top, by the set_complete. But be conservative. 3660 if (idx == InitializeNode::RawAddress) 3661 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3662 return RegMask::Empty; 3663 } 3664 3665 Node* InitializeNode::memory(uint alias_idx) { 3666 Node* mem = in(Memory); 3667 if (mem->is_MergeMem()) { 3668 return mem->as_MergeMem()->memory_at(alias_idx); 3669 } else { 3670 // incoming raw memory is not split 3671 return mem; 3672 } 3673 } 3674 3675 bool InitializeNode::is_non_zero() { 3676 if (is_complete()) return false; 3677 remove_extra_zeroes(); 3678 return (req() > RawStores); 3679 } 3680 3681 void InitializeNode::set_complete(PhaseGVN* phase) { 3682 assert(!is_complete(), "caller responsibility"); 3683 _is_complete = Complete; 3684 3685 // After this node is complete, it contains a bunch of 3686 // raw-memory initializations. There is no need for 3687 // it to have anything to do with non-raw memory effects. 3688 // Therefore, tell all non-raw users to re-optimize themselves, 3689 // after skipping the memory effects of this initialization. 3690 PhaseIterGVN* igvn = phase->is_IterGVN(); 3691 if (igvn) igvn->add_users_to_worklist(this); 3692 } 3693 3694 // convenience function 3695 // return false if the init contains any stores already 3696 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3697 InitializeNode* init = initialization(); 3698 if (init == NULL || init->is_complete()) return false; 3699 init->remove_extra_zeroes(); 3700 // for now, if this allocation has already collected any inits, bail: 3701 if (init->is_non_zero()) return false; 3702 init->set_complete(phase); 3703 return true; 3704 } 3705 3706 void InitializeNode::remove_extra_zeroes() { 3707 if (req() == RawStores) return; 3708 Node* zmem = zero_memory(); 3709 uint fill = RawStores; 3710 for (uint i = fill; i < req(); i++) { 3711 Node* n = in(i); 3712 if (n->is_top() || n == zmem) continue; // skip 3713 if (fill < i) set_req(fill, n); // compact 3714 ++fill; 3715 } 3716 // delete any empty spaces created: 3717 while (fill < req()) { 3718 del_req(fill); 3719 } 3720 } 3721 3722 // Helper for remembering which stores go with which offsets. 3723 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3724 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3725 intptr_t offset = -1; 3726 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3727 phase, offset); 3728 if (base == NULL) return -1; // something is dead, 3729 if (offset < 0) return -1; // dead, dead 3730 return offset; 3731 } 3732 3733 // Helper for proving that an initialization expression is 3734 // "simple enough" to be folded into an object initialization. 3735 // Attempts to prove that a store's initial value 'n' can be captured 3736 // within the initialization without creating a vicious cycle, such as: 3737 // { Foo p = new Foo(); p.next = p; } 3738 // True for constants and parameters and small combinations thereof. 3739 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) { 3740 ResourceMark rm; 3741 Unique_Node_List worklist; 3742 worklist.push(value); 3743 3744 uint complexity_limit = 20; 3745 for (uint j = 0; j < worklist.size(); j++) { 3746 if (j >= complexity_limit) { 3747 return false; // Bail out if processed too many nodes 3748 } 3749 3750 Node* n = worklist.at(j); 3751 if (n == NULL) continue; // (can this really happen?) 3752 if (n->is_Proj()) n = n->in(0); 3753 if (n == this) return false; // found a cycle 3754 if (n->is_Con()) continue; 3755 if (n->is_Start()) continue; // params, etc., are OK 3756 if (n->is_Root()) continue; // even better 3757 3758 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation 3759 if (n->is_CFG() && phase->is_dominator(n, allocation())) { 3760 continue; 3761 } 3762 3763 Node* ctl = n->in(0); 3764 if (ctl != NULL && !ctl->is_top()) { 3765 if (ctl->is_Proj()) ctl = ctl->in(0); 3766 if (ctl == this) return false; 3767 3768 // If we already know that the enclosing memory op is pinned right after 3769 // the init, then any control flow that the store has picked up 3770 // must have preceded the init, or else be equal to the init. 3771 // Even after loop optimizations (which might change control edges) 3772 // a store is never pinned *before* the availability of its inputs. 3773 if (!MemNode::all_controls_dominate(n, this)) 3774 return false; // failed to prove a good control 3775 } 3776 3777 // Check data edges for possible dependencies on 'this'. 3778 for (uint i = 1; i < n->req(); i++) { 3779 Node* m = n->in(i); 3780 if (m == NULL || m == n || m->is_top()) continue; 3781 3782 // Only process data inputs once 3783 worklist.push(m); 3784 } 3785 } 3786 3787 return true; 3788 } 3789 3790 // Here are all the checks a Store must pass before it can be moved into 3791 // an initialization. Returns zero if a check fails. 3792 // On success, returns the (constant) offset to which the store applies, 3793 // within the initialized memory. 3794 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) { 3795 const int FAIL = 0; 3796 if (st->req() != MemNode::ValueIn + 1) 3797 return FAIL; // an inscrutable StoreNode (card mark?) 3798 Node* ctl = st->in(MemNode::Control); 3799 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3800 return FAIL; // must be unconditional after the initialization 3801 Node* mem = st->in(MemNode::Memory); 3802 if (!(mem->is_Proj() && mem->in(0) == this)) 3803 return FAIL; // must not be preceded by other stores 3804 Node* adr = st->in(MemNode::Address); 3805 intptr_t offset; 3806 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3807 if (alloc == NULL) 3808 return FAIL; // inscrutable address 3809 if (alloc != allocation()) 3810 return FAIL; // wrong allocation! (store needs to float up) 3811 int size_in_bytes = st->memory_size(); 3812 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) { 3813 return FAIL; // mismatched access 3814 } 3815 Node* val = st->in(MemNode::ValueIn); 3816 3817 if (!detect_init_independence(val, phase)) 3818 return FAIL; // stored value must be 'simple enough' 3819 3820 // The Store can be captured only if nothing after the allocation 3821 // and before the Store is using the memory location that the store 3822 // overwrites. 3823 bool failed = false; 3824 // If is_complete_with_arraycopy() is true the shape of the graph is 3825 // well defined and is safe so no need for extra checks. 3826 if (!is_complete_with_arraycopy()) { 3827 // We are going to look at each use of the memory state following 3828 // the allocation to make sure nothing reads the memory that the 3829 // Store writes. 3830 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3831 int alias_idx = phase->C->get_alias_index(t_adr); 3832 ResourceMark rm; 3833 Unique_Node_List mems; 3834 mems.push(mem); 3835 Node* unique_merge = NULL; 3836 for (uint next = 0; next < mems.size(); ++next) { 3837 Node *m = mems.at(next); 3838 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3839 Node *n = m->fast_out(j); 3840 if (n->outcnt() == 0) { 3841 continue; 3842 } 3843 if (n == st) { 3844 continue; 3845 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3846 // If the control of this use is different from the control 3847 // of the Store which is right after the InitializeNode then 3848 // this node cannot be between the InitializeNode and the 3849 // Store. 3850 continue; 3851 } else if (n->is_MergeMem()) { 3852 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3853 // We can hit a MergeMemNode (that will likely go away 3854 // later) that is a direct use of the memory state 3855 // following the InitializeNode on the same slice as the 3856 // store node that we'd like to capture. We need to check 3857 // the uses of the MergeMemNode. 3858 mems.push(n); 3859 } 3860 } else if (n->is_Mem()) { 3861 Node* other_adr = n->in(MemNode::Address); 3862 if (other_adr == adr) { 3863 failed = true; 3864 break; 3865 } else { 3866 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3867 if (other_t_adr != NULL) { 3868 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3869 if (other_alias_idx == alias_idx) { 3870 // A load from the same memory slice as the store right 3871 // after the InitializeNode. We check the control of the 3872 // object/array that is loaded from. If it's the same as 3873 // the store control then we cannot capture the store. 3874 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3875 Node* base = other_adr; 3876 assert(base->is_AddP(), "should be addp but is %s", base->Name()); 3877 base = base->in(AddPNode::Base); 3878 if (base != NULL) { 3879 base = base->uncast(); 3880 if (base->is_Proj() && base->in(0) == alloc) { 3881 failed = true; 3882 break; 3883 } 3884 } 3885 } 3886 } 3887 } 3888 } else { 3889 failed = true; 3890 break; 3891 } 3892 } 3893 } 3894 } 3895 if (failed) { 3896 if (!can_reshape) { 3897 // We decided we couldn't capture the store during parsing. We 3898 // should try again during the next IGVN once the graph is 3899 // cleaner. 3900 phase->C->record_for_igvn(st); 3901 } 3902 return FAIL; 3903 } 3904 3905 return offset; // success 3906 } 3907 3908 // Find the captured store in(i) which corresponds to the range 3909 // [start..start+size) in the initialized object. 3910 // If there is one, return its index i. If there isn't, return the 3911 // negative of the index where it should be inserted. 3912 // Return 0 if the queried range overlaps an initialization boundary 3913 // or if dead code is encountered. 3914 // If size_in_bytes is zero, do not bother with overlap checks. 3915 int InitializeNode::captured_store_insertion_point(intptr_t start, 3916 int size_in_bytes, 3917 PhaseTransform* phase) { 3918 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize); 3919 3920 if (is_complete()) 3921 return FAIL; // arraycopy got here first; punt 3922 3923 assert(allocation() != NULL, "must be present"); 3924 3925 // no negatives, no header fields: 3926 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3927 3928 // after a certain size, we bail out on tracking all the stores: 3929 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3930 if (start >= ti_limit) return FAIL; 3931 3932 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3933 if (i >= limit) return -(int)i; // not found; here is where to put it 3934 3935 Node* st = in(i); 3936 intptr_t st_off = get_store_offset(st, phase); 3937 if (st_off < 0) { 3938 if (st != zero_memory()) { 3939 return FAIL; // bail out if there is dead garbage 3940 } 3941 } else if (st_off > start) { 3942 // ...we are done, since stores are ordered 3943 if (st_off < start + size_in_bytes) { 3944 return FAIL; // the next store overlaps 3945 } 3946 return -(int)i; // not found; here is where to put it 3947 } else if (st_off < start) { 3948 assert(st->as_Store()->memory_size() <= MAX_STORE, ""); 3949 if (size_in_bytes != 0 && 3950 start < st_off + MAX_STORE && 3951 start < st_off + st->as_Store()->memory_size()) { 3952 return FAIL; // the previous store overlaps 3953 } 3954 } else { 3955 if (size_in_bytes != 0 && 3956 st->as_Store()->memory_size() != size_in_bytes) { 3957 return FAIL; // mismatched store size 3958 } 3959 return i; 3960 } 3961 3962 ++i; 3963 } 3964 } 3965 3966 // Look for a captured store which initializes at the offset 'start' 3967 // with the given size. If there is no such store, and no other 3968 // initialization interferes, then return zero_memory (the memory 3969 // projection of the AllocateNode). 3970 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3971 PhaseTransform* phase) { 3972 assert(stores_are_sane(phase), ""); 3973 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3974 if (i == 0) { 3975 return NULL; // something is dead 3976 } else if (i < 0) { 3977 return zero_memory(); // just primordial zero bits here 3978 } else { 3979 Node* st = in(i); // here is the store at this position 3980 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3981 return st; 3982 } 3983 } 3984 3985 // Create, as a raw pointer, an address within my new object at 'offset'. 3986 Node* InitializeNode::make_raw_address(intptr_t offset, 3987 PhaseTransform* phase) { 3988 Node* addr = in(RawAddress); 3989 if (offset != 0) { 3990 Compile* C = phase->C; 3991 addr = phase->transform( new AddPNode(C->top(), addr, 3992 phase->MakeConX(offset)) ); 3993 } 3994 return addr; 3995 } 3996 3997 // Clone the given store, converting it into a raw store 3998 // initializing a field or element of my new object. 3999 // Caller is responsible for retiring the original store, 4000 // with subsume_node or the like. 4001 // 4002 // From the example above InitializeNode::InitializeNode, 4003 // here are the old stores to be captured: 4004 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 4005 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 4006 // 4007 // Here is the changed code; note the extra edges on init: 4008 // alloc = (Allocate ...) 4009 // rawoop = alloc.RawAddress 4010 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 4011 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 4012 // init = (Initialize alloc.Control alloc.Memory rawoop 4013 // rawstore1 rawstore2) 4014 // 4015 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 4016 PhaseGVN* phase, bool can_reshape) { 4017 assert(stores_are_sane(phase), ""); 4018 4019 if (start < 0) return NULL; 4020 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 4021 4022 Compile* C = phase->C; 4023 int size_in_bytes = st->memory_size(); 4024 int i = captured_store_insertion_point(start, size_in_bytes, phase); 4025 if (i == 0) return NULL; // bail out 4026 Node* prev_mem = NULL; // raw memory for the captured store 4027 if (i > 0) { 4028 prev_mem = in(i); // there is a pre-existing store under this one 4029 set_req(i, C->top()); // temporarily disconnect it 4030 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 4031 } else { 4032 i = -i; // no pre-existing store 4033 prev_mem = zero_memory(); // a slice of the newly allocated object 4034 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 4035 set_req(--i, C->top()); // reuse this edge; it has been folded away 4036 else 4037 ins_req(i, C->top()); // build a new edge 4038 } 4039 Node* new_st = st->clone(); 4040 new_st->set_req(MemNode::Control, in(Control)); 4041 new_st->set_req(MemNode::Memory, prev_mem); 4042 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 4043 new_st = phase->transform(new_st); 4044 4045 // At this point, new_st might have swallowed a pre-existing store 4046 // at the same offset, or perhaps new_st might have disappeared, 4047 // if it redundantly stored the same value (or zero to fresh memory). 4048 4049 // In any case, wire it in: 4050 PhaseIterGVN* igvn = phase->is_IterGVN(); 4051 if (igvn) { 4052 igvn->rehash_node_delayed(this); 4053 } 4054 set_req(i, new_st); 4055 4056 // The caller may now kill the old guy. 4057 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 4058 assert(check_st == new_st || check_st == NULL, "must be findable"); 4059 assert(!is_complete(), ""); 4060 return new_st; 4061 } 4062 4063 static bool store_constant(jlong* tiles, int num_tiles, 4064 intptr_t st_off, int st_size, 4065 jlong con) { 4066 if ((st_off & (st_size-1)) != 0) 4067 return false; // strange store offset (assume size==2**N) 4068 address addr = (address)tiles + st_off; 4069 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 4070 switch (st_size) { 4071 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 4072 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 4073 case sizeof(jint): *(jint*) addr = (jint) con; break; 4074 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 4075 default: return false; // strange store size (detect size!=2**N here) 4076 } 4077 return true; // return success to caller 4078 } 4079 4080 // Coalesce subword constants into int constants and possibly 4081 // into long constants. The goal, if the CPU permits, 4082 // is to initialize the object with a small number of 64-bit tiles. 4083 // Also, convert floating-point constants to bit patterns. 4084 // Non-constants are not relevant to this pass. 4085 // 4086 // In terms of the running example on InitializeNode::InitializeNode 4087 // and InitializeNode::capture_store, here is the transformation 4088 // of rawstore1 and rawstore2 into rawstore12: 4089 // alloc = (Allocate ...) 4090 // rawoop = alloc.RawAddress 4091 // tile12 = 0x00010002 4092 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 4093 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 4094 // 4095 void 4096 InitializeNode::coalesce_subword_stores(intptr_t header_size, 4097 Node* size_in_bytes, 4098 PhaseGVN* phase) { 4099 Compile* C = phase->C; 4100 4101 assert(stores_are_sane(phase), ""); 4102 // Note: After this pass, they are not completely sane, 4103 // since there may be some overlaps. 4104 4105 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 4106 4107 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 4108 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 4109 size_limit = MIN2(size_limit, ti_limit); 4110 size_limit = align_up(size_limit, BytesPerLong); 4111 int num_tiles = size_limit / BytesPerLong; 4112 4113 // allocate space for the tile map: 4114 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 4115 jlong tiles_buf[small_len]; 4116 Node* nodes_buf[small_len]; 4117 jlong inits_buf[small_len]; 4118 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 4119 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 4120 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 4121 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 4122 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 4123 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 4124 // tiles: exact bitwise model of all primitive constants 4125 // nodes: last constant-storing node subsumed into the tiles model 4126 // inits: which bytes (in each tile) are touched by any initializations 4127 4128 //// Pass A: Fill in the tile model with any relevant stores. 4129 4130 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 4131 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 4132 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 4133 Node* zmem = zero_memory(); // initially zero memory state 4134 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 4135 Node* st = in(i); 4136 intptr_t st_off = get_store_offset(st, phase); 4137 4138 // Figure out the store's offset and constant value: 4139 if (st_off < header_size) continue; //skip (ignore header) 4140 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 4141 int st_size = st->as_Store()->memory_size(); 4142 if (st_off + st_size > size_limit) break; 4143 4144 // Record which bytes are touched, whether by constant or not. 4145 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 4146 continue; // skip (strange store size) 4147 4148 const Type* val = phase->type(st->in(MemNode::ValueIn)); 4149 if (!val->singleton()) continue; //skip (non-con store) 4150 BasicType type = val->basic_type(); 4151 4152 jlong con = 0; 4153 switch (type) { 4154 case T_INT: con = val->is_int()->get_con(); break; 4155 case T_LONG: con = val->is_long()->get_con(); break; 4156 case T_FLOAT: con = jint_cast(val->getf()); break; 4157 case T_DOUBLE: con = jlong_cast(val->getd()); break; 4158 default: continue; //skip (odd store type) 4159 } 4160 4161 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 4162 st->Opcode() == Op_StoreL) { 4163 continue; // This StoreL is already optimal. 4164 } 4165 4166 // Store down the constant. 4167 store_constant(tiles, num_tiles, st_off, st_size, con); 4168 4169 intptr_t j = st_off >> LogBytesPerLong; 4170 4171 if (type == T_INT && st_size == BytesPerInt 4172 && (st_off & BytesPerInt) == BytesPerInt) { 4173 jlong lcon = tiles[j]; 4174 if (!Matcher::isSimpleConstant64(lcon) && 4175 st->Opcode() == Op_StoreI) { 4176 // This StoreI is already optimal by itself. 4177 jint* intcon = (jint*) &tiles[j]; 4178 intcon[1] = 0; // undo the store_constant() 4179 4180 // If the previous store is also optimal by itself, back up and 4181 // undo the action of the previous loop iteration... if we can. 4182 // But if we can't, just let the previous half take care of itself. 4183 st = nodes[j]; 4184 st_off -= BytesPerInt; 4185 con = intcon[0]; 4186 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 4187 assert(st_off >= header_size, "still ignoring header"); 4188 assert(get_store_offset(st, phase) == st_off, "must be"); 4189 assert(in(i-1) == zmem, "must be"); 4190 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 4191 assert(con == tcon->is_int()->get_con(), "must be"); 4192 // Undo the effects of the previous loop trip, which swallowed st: 4193 intcon[0] = 0; // undo store_constant() 4194 set_req(i-1, st); // undo set_req(i, zmem) 4195 nodes[j] = NULL; // undo nodes[j] = st 4196 --old_subword; // undo ++old_subword 4197 } 4198 continue; // This StoreI is already optimal. 4199 } 4200 } 4201 4202 // This store is not needed. 4203 set_req(i, zmem); 4204 nodes[j] = st; // record for the moment 4205 if (st_size < BytesPerLong) // something has changed 4206 ++old_subword; // includes int/float, but who's counting... 4207 else ++old_long; 4208 } 4209 4210 if ((old_subword + old_long) == 0) 4211 return; // nothing more to do 4212 4213 //// Pass B: Convert any non-zero tiles into optimal constant stores. 4214 // Be sure to insert them before overlapping non-constant stores. 4215 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 4216 for (int j = 0; j < num_tiles; j++) { 4217 jlong con = tiles[j]; 4218 jlong init = inits[j]; 4219 if (con == 0) continue; 4220 jint con0, con1; // split the constant, address-wise 4221 jint init0, init1; // split the init map, address-wise 4222 { union { jlong con; jint intcon[2]; } u; 4223 u.con = con; 4224 con0 = u.intcon[0]; 4225 con1 = u.intcon[1]; 4226 u.con = init; 4227 init0 = u.intcon[0]; 4228 init1 = u.intcon[1]; 4229 } 4230 4231 Node* old = nodes[j]; 4232 assert(old != NULL, "need the prior store"); 4233 intptr_t offset = (j * BytesPerLong); 4234 4235 bool split = !Matcher::isSimpleConstant64(con); 4236 4237 if (offset < header_size) { 4238 assert(offset + BytesPerInt >= header_size, "second int counts"); 4239 assert(*(jint*)&tiles[j] == 0, "junk in header"); 4240 split = true; // only the second word counts 4241 // Example: int a[] = { 42 ... } 4242 } else if (con0 == 0 && init0 == -1) { 4243 split = true; // first word is covered by full inits 4244 // Example: int a[] = { ... foo(), 42 ... } 4245 } else if (con1 == 0 && init1 == -1) { 4246 split = true; // second word is covered by full inits 4247 // Example: int a[] = { ... 42, foo() ... } 4248 } 4249 4250 // Here's a case where init0 is neither 0 nor -1: 4251 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 4252 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 4253 // In this case the tile is not split; it is (jlong)42. 4254 // The big tile is stored down, and then the foo() value is inserted. 4255 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 4256 4257 Node* ctl = old->in(MemNode::Control); 4258 Node* adr = make_raw_address(offset, phase); 4259 const TypePtr* atp = TypeRawPtr::BOTTOM; 4260 4261 // One or two coalesced stores to plop down. 4262 Node* st[2]; 4263 intptr_t off[2]; 4264 int nst = 0; 4265 if (!split) { 4266 ++new_long; 4267 off[nst] = offset; 4268 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4269 phase->longcon(con), T_LONG, MemNode::unordered); 4270 } else { 4271 // Omit either if it is a zero. 4272 if (con0 != 0) { 4273 ++new_int; 4274 off[nst] = offset; 4275 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4276 phase->intcon(con0), T_INT, MemNode::unordered); 4277 } 4278 if (con1 != 0) { 4279 ++new_int; 4280 offset += BytesPerInt; 4281 adr = make_raw_address(offset, phase); 4282 off[nst] = offset; 4283 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 4284 phase->intcon(con1), T_INT, MemNode::unordered); 4285 } 4286 } 4287 4288 // Insert second store first, then the first before the second. 4289 // Insert each one just before any overlapping non-constant stores. 4290 while (nst > 0) { 4291 Node* st1 = st[--nst]; 4292 C->copy_node_notes_to(st1, old); 4293 st1 = phase->transform(st1); 4294 offset = off[nst]; 4295 assert(offset >= header_size, "do not smash header"); 4296 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 4297 guarantee(ins_idx != 0, "must re-insert constant store"); 4298 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 4299 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 4300 set_req(--ins_idx, st1); 4301 else 4302 ins_req(ins_idx, st1); 4303 } 4304 } 4305 4306 if (PrintCompilation && WizardMode) 4307 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 4308 old_subword, old_long, new_int, new_long); 4309 if (C->log() != NULL) 4310 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 4311 old_subword, old_long, new_int, new_long); 4312 4313 // Clean up any remaining occurrences of zmem: 4314 remove_extra_zeroes(); 4315 } 4316 4317 // Explore forward from in(start) to find the first fully initialized 4318 // word, and return its offset. Skip groups of subword stores which 4319 // together initialize full words. If in(start) is itself part of a 4320 // fully initialized word, return the offset of in(start). If there 4321 // are no following full-word stores, or if something is fishy, return 4322 // a negative value. 4323 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 4324 int int_map = 0; 4325 intptr_t int_map_off = 0; 4326 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 4327 4328 for (uint i = start, limit = req(); i < limit; i++) { 4329 Node* st = in(i); 4330 4331 intptr_t st_off = get_store_offset(st, phase); 4332 if (st_off < 0) break; // return conservative answer 4333 4334 int st_size = st->as_Store()->memory_size(); 4335 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 4336 return st_off; // we found a complete word init 4337 } 4338 4339 // update the map: 4340 4341 intptr_t this_int_off = align_down(st_off, BytesPerInt); 4342 if (this_int_off != int_map_off) { 4343 // reset the map: 4344 int_map = 0; 4345 int_map_off = this_int_off; 4346 } 4347 4348 int subword_off = st_off - this_int_off; 4349 int_map |= right_n_bits(st_size) << subword_off; 4350 if ((int_map & FULL_MAP) == FULL_MAP) { 4351 return this_int_off; // we found a complete word init 4352 } 4353 4354 // Did this store hit or cross the word boundary? 4355 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt); 4356 if (next_int_off == this_int_off + BytesPerInt) { 4357 // We passed the current int, without fully initializing it. 4358 int_map_off = next_int_off; 4359 int_map >>= BytesPerInt; 4360 } else if (next_int_off > this_int_off + BytesPerInt) { 4361 // We passed the current and next int. 4362 return this_int_off + BytesPerInt; 4363 } 4364 } 4365 4366 return -1; 4367 } 4368 4369 4370 // Called when the associated AllocateNode is expanded into CFG. 4371 // At this point, we may perform additional optimizations. 4372 // Linearize the stores by ascending offset, to make memory 4373 // activity as coherent as possible. 4374 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 4375 intptr_t header_size, 4376 Node* size_in_bytes, 4377 PhaseIterGVN* phase) { 4378 assert(!is_complete(), "not already complete"); 4379 assert(stores_are_sane(phase), ""); 4380 assert(allocation() != NULL, "must be present"); 4381 4382 remove_extra_zeroes(); 4383 4384 if (ReduceFieldZeroing || ReduceBulkZeroing) 4385 // reduce instruction count for common initialization patterns 4386 coalesce_subword_stores(header_size, size_in_bytes, phase); 4387 4388 Node* zmem = zero_memory(); // initially zero memory state 4389 Node* inits = zmem; // accumulating a linearized chain of inits 4390 #ifdef ASSERT 4391 intptr_t first_offset = allocation()->minimum_header_size(); 4392 intptr_t last_init_off = first_offset; // previous init offset 4393 intptr_t last_init_end = first_offset; // previous init offset+size 4394 intptr_t last_tile_end = first_offset; // previous tile offset+size 4395 #endif 4396 intptr_t zeroes_done = header_size; 4397 4398 bool do_zeroing = true; // we might give up if inits are very sparse 4399 int big_init_gaps = 0; // how many large gaps have we seen? 4400 4401 if (UseTLAB && ZeroTLAB) do_zeroing = false; 4402 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 4403 4404 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 4405 Node* st = in(i); 4406 intptr_t st_off = get_store_offset(st, phase); 4407 if (st_off < 0) 4408 break; // unknown junk in the inits 4409 if (st->in(MemNode::Memory) != zmem) 4410 break; // complicated store chains somehow in list 4411 4412 int st_size = st->as_Store()->memory_size(); 4413 intptr_t next_init_off = st_off + st_size; 4414 4415 if (do_zeroing && zeroes_done < next_init_off) { 4416 // See if this store needs a zero before it or under it. 4417 intptr_t zeroes_needed = st_off; 4418 4419 if (st_size < BytesPerInt) { 4420 // Look for subword stores which only partially initialize words. 4421 // If we find some, we must lay down some word-level zeroes first, 4422 // underneath the subword stores. 4423 // 4424 // Examples: 4425 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 4426 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 4427 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 4428 // 4429 // Note: coalesce_subword_stores may have already done this, 4430 // if it was prompted by constant non-zero subword initializers. 4431 // But this case can still arise with non-constant stores. 4432 4433 intptr_t next_full_store = find_next_fullword_store(i, phase); 4434 4435 // In the examples above: 4436 // in(i) p q r s x y z 4437 // st_off 12 13 14 15 12 13 14 4438 // st_size 1 1 1 1 1 1 1 4439 // next_full_s. 12 16 16 16 16 16 16 4440 // z's_done 12 16 16 16 12 16 12 4441 // z's_needed 12 16 16 16 16 16 16 4442 // zsize 0 0 0 0 4 0 4 4443 if (next_full_store < 0) { 4444 // Conservative tack: Zero to end of current word. 4445 zeroes_needed = align_up(zeroes_needed, BytesPerInt); 4446 } else { 4447 // Zero to beginning of next fully initialized word. 4448 // Or, don't zero at all, if we are already in that word. 4449 assert(next_full_store >= zeroes_needed, "must go forward"); 4450 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 4451 zeroes_needed = next_full_store; 4452 } 4453 } 4454 4455 if (zeroes_needed > zeroes_done) { 4456 intptr_t zsize = zeroes_needed - zeroes_done; 4457 // Do some incremental zeroing on rawmem, in parallel with inits. 4458 zeroes_done = align_down(zeroes_done, BytesPerInt); 4459 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4460 zeroes_done, zeroes_needed, 4461 phase); 4462 zeroes_done = zeroes_needed; 4463 if (zsize > InitArrayShortSize && ++big_init_gaps > 2) 4464 do_zeroing = false; // leave the hole, next time 4465 } 4466 } 4467 4468 // Collect the store and move on: 4469 phase->replace_input_of(st, MemNode::Memory, inits); 4470 inits = st; // put it on the linearized chain 4471 set_req(i, zmem); // unhook from previous position 4472 4473 if (zeroes_done == st_off) 4474 zeroes_done = next_init_off; 4475 4476 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 4477 4478 #ifdef ASSERT 4479 // Various order invariants. Weaker than stores_are_sane because 4480 // a large constant tile can be filled in by smaller non-constant stores. 4481 assert(st_off >= last_init_off, "inits do not reverse"); 4482 last_init_off = st_off; 4483 const Type* val = NULL; 4484 if (st_size >= BytesPerInt && 4485 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 4486 (int)val->basic_type() < (int)T_OBJECT) { 4487 assert(st_off >= last_tile_end, "tiles do not overlap"); 4488 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 4489 last_tile_end = MAX2(last_tile_end, next_init_off); 4490 } else { 4491 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong); 4492 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 4493 assert(st_off >= last_init_end, "inits do not overlap"); 4494 last_init_end = next_init_off; // it's a non-tile 4495 } 4496 #endif //ASSERT 4497 } 4498 4499 remove_extra_zeroes(); // clear out all the zmems left over 4500 add_req(inits); 4501 4502 if (!(UseTLAB && ZeroTLAB)) { 4503 // If anything remains to be zeroed, zero it all now. 4504 zeroes_done = align_down(zeroes_done, BytesPerInt); 4505 // if it is the last unused 4 bytes of an instance, forget about it 4506 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 4507 if (zeroes_done + BytesPerLong >= size_limit) { 4508 AllocateNode* alloc = allocation(); 4509 assert(alloc != NULL, "must be present"); 4510 if (alloc != NULL && alloc->Opcode() == Op_Allocate) { 4511 Node* klass_node = alloc->in(AllocateNode::KlassNode); 4512 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 4513 if (zeroes_done == k->layout_helper()) 4514 zeroes_done = size_limit; 4515 } 4516 } 4517 if (zeroes_done < size_limit) { 4518 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 4519 zeroes_done, size_in_bytes, phase); 4520 } 4521 } 4522 4523 set_complete(phase); 4524 return rawmem; 4525 } 4526 4527 4528 #ifdef ASSERT 4529 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 4530 if (is_complete()) 4531 return true; // stores could be anything at this point 4532 assert(allocation() != NULL, "must be present"); 4533 intptr_t last_off = allocation()->minimum_header_size(); 4534 for (uint i = InitializeNode::RawStores; i < req(); i++) { 4535 Node* st = in(i); 4536 intptr_t st_off = get_store_offset(st, phase); 4537 if (st_off < 0) continue; // ignore dead garbage 4538 if (last_off > st_off) { 4539 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 4540 this->dump(2); 4541 assert(false, "ascending store offsets"); 4542 return false; 4543 } 4544 last_off = st_off + st->as_Store()->memory_size(); 4545 } 4546 return true; 4547 } 4548 #endif //ASSERT 4549 4550 4551 4552 4553 //============================MergeMemNode===================================== 4554 // 4555 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4556 // contributing store or call operations. Each contributor provides the memory 4557 // state for a particular "alias type" (see Compile::alias_type). For example, 4558 // if a MergeMem has an input X for alias category #6, then any memory reference 4559 // to alias category #6 may use X as its memory state input, as an exact equivalent 4560 // to using the MergeMem as a whole. 4561 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4562 // 4563 // (Here, the <N> notation gives the index of the relevant adr_type.) 4564 // 4565 // In one special case (and more cases in the future), alias categories overlap. 4566 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4567 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 4568 // it is exactly equivalent to that state W: 4569 // MergeMem(<Bot>: W) <==> W 4570 // 4571 // Usually, the merge has more than one input. In that case, where inputs 4572 // overlap (i.e., one is Bot), the narrower alias type determines the memory 4573 // state for that type, and the wider alias type (Bot) fills in everywhere else: 4574 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4575 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4576 // 4577 // A merge can take a "wide" memory state as one of its narrow inputs. 4578 // This simply means that the merge observes out only the relevant parts of 4579 // the wide input. That is, wide memory states arriving at narrow merge inputs 4580 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4581 // 4582 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4583 // and that memory slices "leak through": 4584 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4585 // 4586 // But, in such a cascade, repeated memory slices can "block the leak": 4587 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4588 // 4589 // In the last example, Y is not part of the combined memory state of the 4590 // outermost MergeMem. The system must, of course, prevent unschedulable 4591 // memory states from arising, so you can be sure that the state Y is somehow 4592 // a precursor to state Y'. 4593 // 4594 // 4595 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4596 // of each MergeMemNode array are exactly the numerical alias indexes, including 4597 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4598 // Compile::alias_type (and kin) produce and manage these indexes. 4599 // 4600 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4601 // (Note that this provides quick access to the top node inside MergeMem methods, 4602 // without the need to reach out via TLS to Compile::current.) 4603 // 4604 // As a consequence of what was just described, a MergeMem that represents a full 4605 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4606 // containing all alias categories. 4607 // 4608 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4609 // 4610 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4611 // a memory state for the alias type <N>, or else the top node, meaning that 4612 // there is no particular input for that alias type. Note that the length of 4613 // a MergeMem is variable, and may be extended at any time to accommodate new 4614 // memory states at larger alias indexes. When merges grow, they are of course 4615 // filled with "top" in the unused in() positions. 4616 // 4617 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4618 // (Top was chosen because it works smoothly with passes like GCM.) 4619 // 4620 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4621 // the type of random VM bits like TLS references.) Since it is always the 4622 // first non-Bot memory slice, some low-level loops use it to initialize an 4623 // index variable: for (i = AliasIdxRaw; i < req(); i++). 4624 // 4625 // 4626 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4627 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4628 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 4629 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4630 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4631 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4632 // 4633 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4634 // really that different from the other memory inputs. An abbreviation called 4635 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4636 // 4637 // 4638 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4639 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4640 // that "emerges though" the base memory will be marked as excluding the alias types 4641 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 4642 // 4643 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4644 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4645 // 4646 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 4647 // (It is currently unimplemented.) As you can see, the resulting merge is 4648 // actually a disjoint union of memory states, rather than an overlay. 4649 // 4650 4651 //------------------------------MergeMemNode----------------------------------- 4652 Node* MergeMemNode::make_empty_memory() { 4653 Node* empty_memory = (Node*) Compile::current()->top(); 4654 assert(empty_memory->is_top(), "correct sentinel identity"); 4655 return empty_memory; 4656 } 4657 4658 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4659 init_class_id(Class_MergeMem); 4660 // all inputs are nullified in Node::Node(int) 4661 // set_input(0, NULL); // no control input 4662 4663 // Initialize the edges uniformly to top, for starters. 4664 Node* empty_mem = make_empty_memory(); 4665 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4666 init_req(i,empty_mem); 4667 } 4668 assert(empty_memory() == empty_mem, ""); 4669 4670 if( new_base != NULL && new_base->is_MergeMem() ) { 4671 MergeMemNode* mdef = new_base->as_MergeMem(); 4672 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4673 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4674 mms.set_memory(mms.memory2()); 4675 } 4676 assert(base_memory() == mdef->base_memory(), ""); 4677 } else { 4678 set_base_memory(new_base); 4679 } 4680 } 4681 4682 // Make a new, untransformed MergeMem with the same base as 'mem'. 4683 // If mem is itself a MergeMem, populate the result with the same edges. 4684 MergeMemNode* MergeMemNode::make(Node* mem) { 4685 return new MergeMemNode(mem); 4686 } 4687 4688 //------------------------------cmp-------------------------------------------- 4689 uint MergeMemNode::hash() const { return NO_HASH; } 4690 bool MergeMemNode::cmp( const Node &n ) const { 4691 return (&n == this); // Always fail except on self 4692 } 4693 4694 //------------------------------Identity--------------------------------------- 4695 Node* MergeMemNode::Identity(PhaseGVN* phase) { 4696 // Identity if this merge point does not record any interesting memory 4697 // disambiguations. 4698 Node* base_mem = base_memory(); 4699 Node* empty_mem = empty_memory(); 4700 if (base_mem != empty_mem) { // Memory path is not dead? 4701 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4702 Node* mem = in(i); 4703 if (mem != empty_mem && mem != base_mem) { 4704 return this; // Many memory splits; no change 4705 } 4706 } 4707 } 4708 return base_mem; // No memory splits; ID on the one true input 4709 } 4710 4711 //------------------------------Ideal------------------------------------------ 4712 // This method is invoked recursively on chains of MergeMem nodes 4713 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4714 // Remove chain'd MergeMems 4715 // 4716 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4717 // relative to the "in(Bot)". Since we are patching both at the same time, 4718 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4719 // but rewrite each "in(i)" relative to the new "in(Bot)". 4720 Node *progress = NULL; 4721 4722 4723 Node* old_base = base_memory(); 4724 Node* empty_mem = empty_memory(); 4725 if (old_base == empty_mem) 4726 return NULL; // Dead memory path. 4727 4728 MergeMemNode* old_mbase; 4729 if (old_base != NULL && old_base->is_MergeMem()) 4730 old_mbase = old_base->as_MergeMem(); 4731 else 4732 old_mbase = NULL; 4733 Node* new_base = old_base; 4734 4735 // simplify stacked MergeMems in base memory 4736 if (old_mbase) new_base = old_mbase->base_memory(); 4737 4738 // the base memory might contribute new slices beyond my req() 4739 if (old_mbase) grow_to_match(old_mbase); 4740 4741 // Look carefully at the base node if it is a phi. 4742 PhiNode* phi_base; 4743 if (new_base != NULL && new_base->is_Phi()) 4744 phi_base = new_base->as_Phi(); 4745 else 4746 phi_base = NULL; 4747 4748 Node* phi_reg = NULL; 4749 uint phi_len = (uint)-1; 4750 if (phi_base != NULL) { 4751 phi_reg = phi_base->region(); 4752 phi_len = phi_base->req(); 4753 // see if the phi is unfinished 4754 for (uint i = 1; i < phi_len; i++) { 4755 if (phi_base->in(i) == NULL) { 4756 // incomplete phi; do not look at it yet! 4757 phi_reg = NULL; 4758 phi_len = (uint)-1; 4759 break; 4760 } 4761 } 4762 } 4763 4764 // Note: We do not call verify_sparse on entry, because inputs 4765 // can normalize to the base_memory via subsume_node or similar 4766 // mechanisms. This method repairs that damage. 4767 4768 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4769 4770 // Look at each slice. 4771 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4772 Node* old_in = in(i); 4773 // calculate the old memory value 4774 Node* old_mem = old_in; 4775 if (old_mem == empty_mem) old_mem = old_base; 4776 assert(old_mem == memory_at(i), ""); 4777 4778 // maybe update (reslice) the old memory value 4779 4780 // simplify stacked MergeMems 4781 Node* new_mem = old_mem; 4782 MergeMemNode* old_mmem; 4783 if (old_mem != NULL && old_mem->is_MergeMem()) 4784 old_mmem = old_mem->as_MergeMem(); 4785 else 4786 old_mmem = NULL; 4787 if (old_mmem == this) { 4788 // This can happen if loops break up and safepoints disappear. 4789 // A merge of BotPtr (default) with a RawPtr memory derived from a 4790 // safepoint can be rewritten to a merge of the same BotPtr with 4791 // the BotPtr phi coming into the loop. If that phi disappears 4792 // also, we can end up with a self-loop of the mergemem. 4793 // In general, if loops degenerate and memory effects disappear, 4794 // a mergemem can be left looking at itself. This simply means 4795 // that the mergemem's default should be used, since there is 4796 // no longer any apparent effect on this slice. 4797 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4798 // from start. Update the input to TOP. 4799 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4800 } 4801 else if (old_mmem != NULL) { 4802 new_mem = old_mmem->memory_at(i); 4803 } 4804 // else preceding memory was not a MergeMem 4805 4806 // maybe store down a new value 4807 Node* new_in = new_mem; 4808 if (new_in == new_base) new_in = empty_mem; 4809 4810 if (new_in != old_in) { 4811 // Warning: Do not combine this "if" with the previous "if" 4812 // A memory slice might have be be rewritten even if it is semantically 4813 // unchanged, if the base_memory value has changed. 4814 set_req_X(i, new_in, phase); 4815 progress = this; // Report progress 4816 } 4817 } 4818 4819 if (new_base != old_base) { 4820 set_req_X(Compile::AliasIdxBot, new_base, phase); 4821 // Don't use set_base_memory(new_base), because we need to update du. 4822 assert(base_memory() == new_base, ""); 4823 progress = this; 4824 } 4825 4826 if( base_memory() == this ) { 4827 // a self cycle indicates this memory path is dead 4828 set_req(Compile::AliasIdxBot, empty_mem); 4829 } 4830 4831 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4832 // Recursion must occur after the self cycle check above 4833 if( base_memory()->is_MergeMem() ) { 4834 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4835 Node *m = phase->transform(new_mbase); // Rollup any cycles 4836 if( m != NULL && 4837 (m->is_top() || 4838 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) { 4839 // propagate rollup of dead cycle to self 4840 set_req(Compile::AliasIdxBot, empty_mem); 4841 } 4842 } 4843 4844 if( base_memory() == empty_mem ) { 4845 progress = this; 4846 // Cut inputs during Parse phase only. 4847 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4848 if( !can_reshape ) { 4849 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4850 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4851 } 4852 } 4853 } 4854 4855 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4856 // Check if PhiNode::Ideal's "Split phis through memory merges" 4857 // transform should be attempted. Look for this->phi->this cycle. 4858 uint merge_width = req(); 4859 if (merge_width > Compile::AliasIdxRaw) { 4860 PhiNode* phi = base_memory()->as_Phi(); 4861 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4862 if (phi->in(i) == this) { 4863 phase->is_IterGVN()->_worklist.push(phi); 4864 break; 4865 } 4866 } 4867 } 4868 } 4869 4870 assert(progress || verify_sparse(), "please, no dups of base"); 4871 return progress; 4872 } 4873 4874 //-------------------------set_base_memory------------------------------------- 4875 void MergeMemNode::set_base_memory(Node *new_base) { 4876 Node* empty_mem = empty_memory(); 4877 set_req(Compile::AliasIdxBot, new_base); 4878 assert(memory_at(req()) == new_base, "must set default memory"); 4879 // Clear out other occurrences of new_base: 4880 if (new_base != empty_mem) { 4881 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4882 if (in(i) == new_base) set_req(i, empty_mem); 4883 } 4884 } 4885 } 4886 4887 //------------------------------out_RegMask------------------------------------ 4888 const RegMask &MergeMemNode::out_RegMask() const { 4889 return RegMask::Empty; 4890 } 4891 4892 //------------------------------dump_spec-------------------------------------- 4893 #ifndef PRODUCT 4894 void MergeMemNode::dump_spec(outputStream *st) const { 4895 st->print(" {"); 4896 Node* base_mem = base_memory(); 4897 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4898 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem; 4899 if (mem == base_mem) { st->print(" -"); continue; } 4900 st->print( " N%d:", mem->_idx ); 4901 Compile::current()->get_adr_type(i)->dump_on(st); 4902 } 4903 st->print(" }"); 4904 } 4905 #endif // !PRODUCT 4906 4907 4908 #ifdef ASSERT 4909 static bool might_be_same(Node* a, Node* b) { 4910 if (a == b) return true; 4911 if (!(a->is_Phi() || b->is_Phi())) return false; 4912 // phis shift around during optimization 4913 return true; // pretty stupid... 4914 } 4915 4916 // verify a narrow slice (either incoming or outgoing) 4917 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4918 if (!VerifyAliases) return; // don't bother to verify unless requested 4919 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 4920 if (Node::in_dump()) return; // muzzle asserts when printing 4921 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4922 assert(n != NULL, ""); 4923 // Elide intervening MergeMem's 4924 while (n->is_MergeMem()) { 4925 n = n->as_MergeMem()->memory_at(alias_idx); 4926 } 4927 Compile* C = Compile::current(); 4928 const TypePtr* n_adr_type = n->adr_type(); 4929 if (n == m->empty_memory()) { 4930 // Implicit copy of base_memory() 4931 } else if (n_adr_type != TypePtr::BOTTOM) { 4932 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4933 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4934 } else { 4935 // A few places like make_runtime_call "know" that VM calls are narrow, 4936 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4937 bool expected_wide_mem = false; 4938 if (n == m->base_memory()) { 4939 expected_wide_mem = true; 4940 } else if (alias_idx == Compile::AliasIdxRaw || 4941 n == m->memory_at(Compile::AliasIdxRaw)) { 4942 expected_wide_mem = true; 4943 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4944 // memory can "leak through" calls on channels that 4945 // are write-once. Allow this also. 4946 expected_wide_mem = true; 4947 } 4948 assert(expected_wide_mem, "expected narrow slice replacement"); 4949 } 4950 } 4951 #else // !ASSERT 4952 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4953 #endif 4954 4955 4956 //-----------------------------memory_at--------------------------------------- 4957 Node* MergeMemNode::memory_at(uint alias_idx) const { 4958 assert(alias_idx >= Compile::AliasIdxRaw || 4959 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4960 "must avoid base_memory and AliasIdxTop"); 4961 4962 // Otherwise, it is a narrow slice. 4963 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4964 Compile *C = Compile::current(); 4965 if (is_empty_memory(n)) { 4966 // the array is sparse; empty slots are the "top" node 4967 n = base_memory(); 4968 assert(Node::in_dump() 4969 || n == NULL || n->bottom_type() == Type::TOP 4970 || n->adr_type() == NULL // address is TOP 4971 || n->adr_type() == TypePtr::BOTTOM 4972 || n->adr_type() == TypeRawPtr::BOTTOM 4973 || Compile::current()->AliasLevel() == 0, 4974 "must be a wide memory"); 4975 // AliasLevel == 0 if we are organizing the memory states manually. 4976 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4977 } else { 4978 // make sure the stored slice is sane 4979 #ifdef ASSERT 4980 if (VMError::is_error_reported() || Node::in_dump()) { 4981 } else if (might_be_same(n, base_memory())) { 4982 // Give it a pass: It is a mostly harmless repetition of the base. 4983 // This can arise normally from node subsumption during optimization. 4984 } else { 4985 verify_memory_slice(this, alias_idx, n); 4986 } 4987 #endif 4988 } 4989 return n; 4990 } 4991 4992 //---------------------------set_memory_at------------------------------------- 4993 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4994 verify_memory_slice(this, alias_idx, n); 4995 Node* empty_mem = empty_memory(); 4996 if (n == base_memory()) n = empty_mem; // collapse default 4997 uint need_req = alias_idx+1; 4998 if (req() < need_req) { 4999 if (n == empty_mem) return; // already the default, so do not grow me 5000 // grow the sparse array 5001 do { 5002 add_req(empty_mem); 5003 } while (req() < need_req); 5004 } 5005 set_req( alias_idx, n ); 5006 } 5007 5008 5009 5010 //--------------------------iteration_setup------------------------------------ 5011 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 5012 if (other != NULL) { 5013 grow_to_match(other); 5014 // invariant: the finite support of mm2 is within mm->req() 5015 #ifdef ASSERT 5016 for (uint i = req(); i < other->req(); i++) { 5017 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 5018 } 5019 #endif 5020 } 5021 // Replace spurious copies of base_memory by top. 5022 Node* base_mem = base_memory(); 5023 if (base_mem != NULL && !base_mem->is_top()) { 5024 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 5025 if (in(i) == base_mem) 5026 set_req(i, empty_memory()); 5027 } 5028 } 5029 } 5030 5031 //---------------------------grow_to_match------------------------------------- 5032 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 5033 Node* empty_mem = empty_memory(); 5034 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 5035 // look for the finite support of the other memory 5036 for (uint i = other->req(); --i >= req(); ) { 5037 if (other->in(i) != empty_mem) { 5038 uint new_len = i+1; 5039 while (req() < new_len) add_req(empty_mem); 5040 break; 5041 } 5042 } 5043 } 5044 5045 //---------------------------verify_sparse------------------------------------- 5046 #ifndef PRODUCT 5047 bool MergeMemNode::verify_sparse() const { 5048 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 5049 Node* base_mem = base_memory(); 5050 // The following can happen in degenerate cases, since empty==top. 5051 if (is_empty_memory(base_mem)) return true; 5052 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 5053 assert(in(i) != NULL, "sane slice"); 5054 if (in(i) == base_mem) return false; // should have been the sentinel value! 5055 } 5056 return true; 5057 } 5058 5059 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 5060 Node* n; 5061 n = mm->in(idx); 5062 if (mem == n) return true; // might be empty_memory() 5063 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 5064 if (mem == n) return true; 5065 return false; 5066 } 5067 #endif // !PRODUCT