memnode.cpp revision 13243:7235bc30c0d7
1/* 2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25#include "precompiled.hpp" 26#include "classfile/systemDictionary.hpp" 27#include "compiler/compileLog.hpp" 28#include "memory/allocation.inline.hpp" 29#include "memory/resourceArea.hpp" 30#include "oops/objArrayKlass.hpp" 31#include "opto/addnode.hpp" 32#include "opto/arraycopynode.hpp" 33#include "opto/cfgnode.hpp" 34#include "opto/compile.hpp" 35#include "opto/connode.hpp" 36#include "opto/convertnode.hpp" 37#include "opto/loopnode.hpp" 38#include "opto/machnode.hpp" 39#include "opto/matcher.hpp" 40#include "opto/memnode.hpp" 41#include "opto/mulnode.hpp" 42#include "opto/narrowptrnode.hpp" 43#include "opto/phaseX.hpp" 44#include "opto/regmask.hpp" 45#include "utilities/copy.hpp" 46#include "utilities/vmError.hpp" 47 48// Portions of code courtesy of Clifford Click 49 50// Optimization - Graph Style 51 52static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 53 54//============================================================================= 55uint MemNode::size_of() const { return sizeof(*this); } 56 57const TypePtr *MemNode::adr_type() const { 58 Node* adr = in(Address); 59 if (adr == NULL) return NULL; // node is dead 60 const TypePtr* cross_check = NULL; 61 DEBUG_ONLY(cross_check = _adr_type); 62 return calculate_adr_type(adr->bottom_type(), cross_check); 63} 64 65bool MemNode::check_if_adr_maybe_raw(Node* adr) { 66 if (adr != NULL) { 67 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) { 68 return true; 69 } 70 } 71 return false; 72} 73 74#ifndef PRODUCT 75void MemNode::dump_spec(outputStream *st) const { 76 if (in(Address) == NULL) return; // node is dead 77#ifndef ASSERT 78 // fake the missing field 79 const TypePtr* _adr_type = NULL; 80 if (in(Address) != NULL) 81 _adr_type = in(Address)->bottom_type()->isa_ptr(); 82#endif 83 dump_adr_type(this, _adr_type, st); 84 85 Compile* C = Compile::current(); 86 if (C->alias_type(_adr_type)->is_volatile()) { 87 st->print(" Volatile!"); 88 } 89 if (_unaligned_access) { 90 st->print(" unaligned"); 91 } 92 if (_mismatched_access) { 93 st->print(" mismatched"); 94 } 95} 96 97void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 98 st->print(" @"); 99 if (adr_type == NULL) { 100 st->print("NULL"); 101 } else { 102 adr_type->dump_on(st); 103 Compile* C = Compile::current(); 104 Compile::AliasType* atp = NULL; 105 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 106 if (atp == NULL) 107 st->print(", idx=?\?;"); 108 else if (atp->index() == Compile::AliasIdxBot) 109 st->print(", idx=Bot;"); 110 else if (atp->index() == Compile::AliasIdxTop) 111 st->print(", idx=Top;"); 112 else if (atp->index() == Compile::AliasIdxRaw) 113 st->print(", idx=Raw;"); 114 else { 115 ciField* field = atp->field(); 116 if (field) { 117 st->print(", name="); 118 field->print_name_on(st); 119 } 120 st->print(", idx=%d;", atp->index()); 121 } 122 } 123} 124 125extern void print_alias_types(); 126 127#endif 128 129Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) { 130 assert((t_oop != NULL), "sanity"); 131 bool is_instance = t_oop->is_known_instance_field(); 132 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() && 133 (load != NULL) && load->is_Load() && 134 (phase->is_IterGVN() != NULL); 135 if (!(is_instance || is_boxed_value_load)) 136 return mchain; // don't try to optimize non-instance types 137 uint instance_id = t_oop->instance_id(); 138 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory); 139 Node *prev = NULL; 140 Node *result = mchain; 141 while (prev != result) { 142 prev = result; 143 if (result == start_mem) 144 break; // hit one of our sentinels 145 // skip over a call which does not affect this memory slice 146 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 147 Node *proj_in = result->in(0); 148 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 149 break; // hit one of our sentinels 150 } else if (proj_in->is_Call()) { 151 // ArrayCopyNodes processed here as well 152 CallNode *call = proj_in->as_Call(); 153 if (!call->may_modify(t_oop, phase)) { // returns false for instances 154 result = call->in(TypeFunc::Memory); 155 } 156 } else if (proj_in->is_Initialize()) { 157 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 158 // Stop if this is the initialization for the object instance which 159 // contains this memory slice, otherwise skip over it. 160 if ((alloc == NULL) || (alloc->_idx == instance_id)) { 161 break; 162 } 163 if (is_instance) { 164 result = proj_in->in(TypeFunc::Memory); 165 } else if (is_boxed_value_load) { 166 Node* klass = alloc->in(AllocateNode::KlassNode); 167 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 168 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) { 169 result = proj_in->in(TypeFunc::Memory); // not related allocation 170 } 171 } 172 } else if (proj_in->is_MemBar()) { 173 ArrayCopyNode* ac = NULL; 174 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) { 175 break; 176 } 177 result = proj_in->in(TypeFunc::Memory); 178 } else { 179 assert(false, "unexpected projection"); 180 } 181 } else if (result->is_ClearArray()) { 182 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) { 183 // Can not bypass initialization of the instance 184 // we are looking for. 185 break; 186 } 187 // Otherwise skip it (the call updated 'result' value). 188 } else if (result->is_MergeMem()) { 189 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty); 190 } 191 } 192 return result; 193} 194 195Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 196 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 197 if (t_oop == NULL) 198 return mchain; // don't try to optimize non-oop types 199 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 200 bool is_instance = t_oop->is_known_instance_field(); 201 PhaseIterGVN *igvn = phase->is_IterGVN(); 202 if (is_instance && igvn != NULL && result->is_Phi()) { 203 PhiNode *mphi = result->as_Phi(); 204 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 205 const TypePtr *t = mphi->adr_type(); 206 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 207 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 208 t->is_oopptr()->cast_to_exactness(true) 209 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 210 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) { 211 // clone the Phi with our address type 212 result = mphi->split_out_instance(t_adr, igvn); 213 } else { 214 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 215 } 216 } 217 return result; 218} 219 220static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 221 uint alias_idx = phase->C->get_alias_index(tp); 222 Node *mem = mmem; 223#ifdef ASSERT 224 { 225 // Check that current type is consistent with the alias index used during graph construction 226 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 227 bool consistent = adr_check == NULL || adr_check->empty() || 228 phase->C->must_alias(adr_check, alias_idx ); 229 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 230 if( !consistent && adr_check != NULL && !adr_check->empty() && 231 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 232 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 233 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 234 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 235 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 236 // don't assert if it is dead code. 237 consistent = true; 238 } 239 if( !consistent ) { 240 st->print("alias_idx==%d, adr_check==", alias_idx); 241 if( adr_check == NULL ) { 242 st->print("NULL"); 243 } else { 244 adr_check->dump(); 245 } 246 st->cr(); 247 print_alias_types(); 248 assert(consistent, "adr_check must match alias idx"); 249 } 250 } 251#endif 252 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 253 // means an array I have not precisely typed yet. Do not do any 254 // alias stuff with it any time soon. 255 const TypeOopPtr *toop = tp->isa_oopptr(); 256 if( tp->base() != Type::AnyPtr && 257 !(toop && 258 toop->klass() != NULL && 259 toop->klass()->is_java_lang_Object() && 260 toop->offset() == Type::OffsetBot) ) { 261 // compress paths and change unreachable cycles to TOP 262 // If not, we can update the input infinitely along a MergeMem cycle 263 // Equivalent code in PhiNode::Ideal 264 Node* m = phase->transform(mmem); 265 // If transformed to a MergeMem, get the desired slice 266 // Otherwise the returned node represents memory for every slice 267 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 268 // Update input if it is progress over what we have now 269 } 270 return mem; 271} 272 273//--------------------------Ideal_common--------------------------------------- 274// Look for degenerate control and memory inputs. Bypass MergeMem inputs. 275// Unhook non-raw memories from complete (macro-expanded) initializations. 276Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 277 // If our control input is a dead region, kill all below the region 278 Node *ctl = in(MemNode::Control); 279 if (ctl && remove_dead_region(phase, can_reshape)) 280 return this; 281 ctl = in(MemNode::Control); 282 // Don't bother trying to transform a dead node 283 if (ctl && ctl->is_top()) return NodeSentinel; 284 285 PhaseIterGVN *igvn = phase->is_IterGVN(); 286 // Wait if control on the worklist. 287 if (ctl && can_reshape && igvn != NULL) { 288 Node* bol = NULL; 289 Node* cmp = NULL; 290 if (ctl->in(0)->is_If()) { 291 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 292 bol = ctl->in(0)->in(1); 293 if (bol->is_Bool()) 294 cmp = ctl->in(0)->in(1)->in(1); 295 } 296 if (igvn->_worklist.member(ctl) || 297 (bol != NULL && igvn->_worklist.member(bol)) || 298 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 299 // This control path may be dead. 300 // Delay this memory node transformation until the control is processed. 301 phase->is_IterGVN()->_worklist.push(this); 302 return NodeSentinel; // caller will return NULL 303 } 304 } 305 // Ignore if memory is dead, or self-loop 306 Node *mem = in(MemNode::Memory); 307 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL 308 assert(mem != this, "dead loop in MemNode::Ideal"); 309 310 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 311 // This memory slice may be dead. 312 // Delay this mem node transformation until the memory is processed. 313 phase->is_IterGVN()->_worklist.push(this); 314 return NodeSentinel; // caller will return NULL 315 } 316 317 Node *address = in(MemNode::Address); 318 const Type *t_adr = phase->type(address); 319 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL 320 321 if (can_reshape && igvn != NULL && 322 (igvn->_worklist.member(address) || 323 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) { 324 // The address's base and type may change when the address is processed. 325 // Delay this mem node transformation until the address is processed. 326 phase->is_IterGVN()->_worklist.push(this); 327 return NodeSentinel; // caller will return NULL 328 } 329 330 // Do NOT remove or optimize the next lines: ensure a new alias index 331 // is allocated for an oop pointer type before Escape Analysis. 332 // Note: C++ will not remove it since the call has side effect. 333 if (t_adr->isa_oopptr()) { 334 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 335 } 336 337 Node* base = NULL; 338 if (address->is_AddP()) { 339 base = address->in(AddPNode::Base); 340 } 341 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 342 !t_adr->isa_rawptr()) { 343 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 344 // Skip this node optimization if its address has TOP base. 345 return NodeSentinel; // caller will return NULL 346 } 347 348 // Avoid independent memory operations 349 Node* old_mem = mem; 350 351 // The code which unhooks non-raw memories from complete (macro-expanded) 352 // initializations was removed. After macro-expansion all stores catched 353 // by Initialize node became raw stores and there is no information 354 // which memory slices they modify. So it is unsafe to move any memory 355 // operation above these stores. Also in most cases hooked non-raw memories 356 // were already unhooked by using information from detect_ptr_independence() 357 // and find_previous_store(). 358 359 if (mem->is_MergeMem()) { 360 MergeMemNode* mmem = mem->as_MergeMem(); 361 const TypePtr *tp = t_adr->is_ptr(); 362 363 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 364 } 365 366 if (mem != old_mem) { 367 set_req(MemNode::Memory, mem); 368 if (can_reshape && old_mem->outcnt() == 0) { 369 igvn->_worklist.push(old_mem); 370 } 371 if (phase->type( mem ) == Type::TOP) return NodeSentinel; 372 return this; 373 } 374 375 // let the subclass continue analyzing... 376 return NULL; 377} 378 379// Helper function for proving some simple control dominations. 380// Attempt to prove that all control inputs of 'dom' dominate 'sub'. 381// Already assumes that 'dom' is available at 'sub', and that 'sub' 382// is not a constant (dominated by the method's StartNode). 383// Used by MemNode::find_previous_store to prove that the 384// control input of a memory operation predates (dominates) 385// an allocation it wants to look past. 386bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 387 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 388 return false; // Conservative answer for dead code 389 390 // Check 'dom'. Skip Proj and CatchProj nodes. 391 dom = dom->find_exact_control(dom); 392 if (dom == NULL || dom->is_top()) 393 return false; // Conservative answer for dead code 394 395 if (dom == sub) { 396 // For the case when, for example, 'sub' is Initialize and the original 397 // 'dom' is Proj node of the 'sub'. 398 return false; 399 } 400 401 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 402 return true; 403 404 // 'dom' dominates 'sub' if its control edge and control edges 405 // of all its inputs dominate or equal to sub's control edge. 406 407 // Currently 'sub' is either Allocate, Initialize or Start nodes. 408 // Or Region for the check in LoadNode::Ideal(); 409 // 'sub' should have sub->in(0) != NULL. 410 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 411 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 412 413 // Get control edge of 'sub'. 414 Node* orig_sub = sub; 415 sub = sub->find_exact_control(sub->in(0)); 416 if (sub == NULL || sub->is_top()) 417 return false; // Conservative answer for dead code 418 419 assert(sub->is_CFG(), "expecting control"); 420 421 if (sub == dom) 422 return true; 423 424 if (sub->is_Start() || sub->is_Root()) 425 return false; 426 427 { 428 // Check all control edges of 'dom'. 429 430 ResourceMark rm; 431 Arena* arena = Thread::current()->resource_area(); 432 Node_List nlist(arena); 433 Unique_Node_List dom_list(arena); 434 435 dom_list.push(dom); 436 bool only_dominating_controls = false; 437 438 for (uint next = 0; next < dom_list.size(); next++) { 439 Node* n = dom_list.at(next); 440 if (n == orig_sub) 441 return false; // One of dom's inputs dominated by sub. 442 if (!n->is_CFG() && n->pinned()) { 443 // Check only own control edge for pinned non-control nodes. 444 n = n->find_exact_control(n->in(0)); 445 if (n == NULL || n->is_top()) 446 return false; // Conservative answer for dead code 447 assert(n->is_CFG(), "expecting control"); 448 dom_list.push(n); 449 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 450 only_dominating_controls = true; 451 } else if (n->is_CFG()) { 452 if (n->dominates(sub, nlist)) 453 only_dominating_controls = true; 454 else 455 return false; 456 } else { 457 // First, own control edge. 458 Node* m = n->find_exact_control(n->in(0)); 459 if (m != NULL) { 460 if (m->is_top()) 461 return false; // Conservative answer for dead code 462 dom_list.push(m); 463 } 464 // Now, the rest of edges. 465 uint cnt = n->req(); 466 for (uint i = 1; i < cnt; i++) { 467 m = n->find_exact_control(n->in(i)); 468 if (m == NULL || m->is_top()) 469 continue; 470 dom_list.push(m); 471 } 472 } 473 } 474 return only_dominating_controls; 475 } 476} 477 478//---------------------detect_ptr_independence--------------------------------- 479// Used by MemNode::find_previous_store to prove that two base 480// pointers are never equal. 481// The pointers are accompanied by their associated allocations, 482// if any, which have been previously discovered by the caller. 483bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 484 Node* p2, AllocateNode* a2, 485 PhaseTransform* phase) { 486 // Attempt to prove that these two pointers cannot be aliased. 487 // They may both manifestly be allocations, and they should differ. 488 // Or, if they are not both allocations, they can be distinct constants. 489 // Otherwise, one is an allocation and the other a pre-existing value. 490 if (a1 == NULL && a2 == NULL) { // neither an allocation 491 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 492 } else if (a1 != NULL && a2 != NULL) { // both allocations 493 return (a1 != a2); 494 } else if (a1 != NULL) { // one allocation a1 495 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 496 return all_controls_dominate(p2, a1); 497 } else { //(a2 != NULL) // one allocation a2 498 return all_controls_dominate(p1, a2); 499 } 500 return false; 501} 502 503 504// Find an arraycopy that must have set (can_see_stored_value=true) or 505// could have set (can_see_stored_value=false) the value for this load 506Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 507 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 508 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 509 Node* mb = mem->in(0); 510 if (mb->in(0) != NULL && mb->in(0)->is_Proj() && 511 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) { 512 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy(); 513 if (ac->is_clonebasic()) { 514 intptr_t offset; 515 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset); 516 assert(alloc != NULL && (!ReduceBulkZeroing || alloc->initialization()->is_complete_with_arraycopy()), "broken allocation"); 517 if (alloc == ld_alloc) { 518 return ac; 519 } 520 } 521 } 522 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) { 523 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy(); 524 525 if (ac->is_arraycopy_validated() || 526 ac->is_copyof_validated() || 527 ac->is_copyofrange_validated()) { 528 Node* ld_addp = in(MemNode::Address); 529 if (ld_addp->is_AddP()) { 530 Node* ld_base = ld_addp->in(AddPNode::Address); 531 Node* ld_offs = ld_addp->in(AddPNode::Offset); 532 533 Node* dest = ac->in(ArrayCopyNode::Dest); 534 535 if (dest == ld_base) { 536 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 537 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) { 538 return ac; 539 } 540 if (!can_see_stored_value) { 541 mem = ac->in(TypeFunc::Memory); 542 } 543 } 544 } 545 } 546 } 547 return NULL; 548} 549 550// The logic for reordering loads and stores uses four steps: 551// (a) Walk carefully past stores and initializations which we 552// can prove are independent of this load. 553// (b) Observe that the next memory state makes an exact match 554// with self (load or store), and locate the relevant store. 555// (c) Ensure that, if we were to wire self directly to the store, 556// the optimizer would fold it up somehow. 557// (d) Do the rewiring, and return, depending on some other part of 558// the optimizer to fold up the load. 559// This routine handles steps (a) and (b). Steps (c) and (d) are 560// specific to loads and stores, so they are handled by the callers. 561// (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 562// 563Node* MemNode::find_previous_store(PhaseTransform* phase) { 564 Node* ctrl = in(MemNode::Control); 565 Node* adr = in(MemNode::Address); 566 intptr_t offset = 0; 567 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 568 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 569 570 if (offset == Type::OffsetBot) 571 return NULL; // cannot unalias unless there are precise offsets 572 573 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr); 574 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 575 576 intptr_t size_in_bytes = memory_size(); 577 578 Node* mem = in(MemNode::Memory); // start searching here... 579 580 int cnt = 50; // Cycle limiter 581 for (;;) { // While we can dance past unrelated stores... 582 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 583 584 Node* prev = mem; 585 if (mem->is_Store()) { 586 Node* st_adr = mem->in(MemNode::Address); 587 intptr_t st_offset = 0; 588 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 589 if (st_base == NULL) 590 break; // inscrutable pointer 591 592 // For raw accesses it's not enough to prove that constant offsets don't intersect. 593 // We need the bases to be the equal in order for the offset check to make sense. 594 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) { 595 break; 596 } 597 598 if (st_offset != offset && st_offset != Type::OffsetBot) { 599 const int MAX_STORE = BytesPerLong; 600 if (st_offset >= offset + size_in_bytes || 601 st_offset <= offset - MAX_STORE || 602 st_offset <= offset - mem->as_Store()->memory_size()) { 603 // Success: The offsets are provably independent. 604 // (You may ask, why not just test st_offset != offset and be done? 605 // The answer is that stores of different sizes can co-exist 606 // in the same sequence of RawMem effects. We sometimes initialize 607 // a whole 'tile' of array elements with a single jint or jlong.) 608 mem = mem->in(MemNode::Memory); 609 continue; // (a) advance through independent store memory 610 } 611 } 612 if (st_base != base && 613 detect_ptr_independence(base, alloc, 614 st_base, 615 AllocateNode::Ideal_allocation(st_base, phase), 616 phase)) { 617 // Success: The bases are provably independent. 618 mem = mem->in(MemNode::Memory); 619 continue; // (a) advance through independent store memory 620 } 621 622 // (b) At this point, if the bases or offsets do not agree, we lose, 623 // since we have not managed to prove 'this' and 'mem' independent. 624 if (st_base == base && st_offset == offset) { 625 return mem; // let caller handle steps (c), (d) 626 } 627 628 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 629 InitializeNode* st_init = mem->in(0)->as_Initialize(); 630 AllocateNode* st_alloc = st_init->allocation(); 631 if (st_alloc == NULL) 632 break; // something degenerated 633 bool known_identical = false; 634 bool known_independent = false; 635 if (alloc == st_alloc) 636 known_identical = true; 637 else if (alloc != NULL) 638 known_independent = true; 639 else if (all_controls_dominate(this, st_alloc)) 640 known_independent = true; 641 642 if (known_independent) { 643 // The bases are provably independent: Either they are 644 // manifestly distinct allocations, or else the control 645 // of this load dominates the store's allocation. 646 int alias_idx = phase->C->get_alias_index(adr_type()); 647 if (alias_idx == Compile::AliasIdxRaw) { 648 mem = st_alloc->in(TypeFunc::Memory); 649 } else { 650 mem = st_init->memory(alias_idx); 651 } 652 continue; // (a) advance through independent store memory 653 } 654 655 // (b) at this point, if we are not looking at a store initializing 656 // the same allocation we are loading from, we lose. 657 if (known_identical) { 658 // From caller, can_see_stored_value will consult find_captured_store. 659 return mem; // let caller handle steps (c), (d) 660 } 661 662 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) { 663 if (prev != mem) { 664 // Found an arraycopy but it doesn't affect that load 665 continue; 666 } 667 // Found an arraycopy that may affect that load 668 return mem; 669 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 670 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 671 if (mem->is_Proj() && mem->in(0)->is_Call()) { 672 // ArrayCopyNodes processed here as well. 673 CallNode *call = mem->in(0)->as_Call(); 674 if (!call->may_modify(addr_t, phase)) { 675 mem = call->in(TypeFunc::Memory); 676 continue; // (a) advance through independent call memory 677 } 678 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 679 ArrayCopyNode* ac = NULL; 680 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) { 681 break; 682 } 683 mem = mem->in(0)->in(TypeFunc::Memory); 684 continue; // (a) advance through independent MemBar memory 685 } else if (mem->is_ClearArray()) { 686 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 687 // (the call updated 'mem' value) 688 continue; // (a) advance through independent allocation memory 689 } else { 690 // Can not bypass initialization of the instance 691 // we are looking for. 692 return mem; 693 } 694 } else if (mem->is_MergeMem()) { 695 int alias_idx = phase->C->get_alias_index(adr_type()); 696 mem = mem->as_MergeMem()->memory_at(alias_idx); 697 continue; // (a) advance through independent MergeMem memory 698 } 699 } 700 701 // Unless there is an explicit 'continue', we must bail out here, 702 // because 'mem' is an inscrutable memory state (e.g., a call). 703 break; 704 } 705 706 return NULL; // bail out 707} 708 709//----------------------calculate_adr_type------------------------------------- 710// Helper function. Notices when the given type of address hits top or bottom. 711// Also, asserts a cross-check of the type against the expected address type. 712const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 713 if (t == Type::TOP) return NULL; // does not touch memory any more? 714 #ifdef PRODUCT 715 cross_check = NULL; 716 #else 717 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL; 718 #endif 719 const TypePtr* tp = t->isa_ptr(); 720 if (tp == NULL) { 721 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 722 return TypePtr::BOTTOM; // touches lots of memory 723 } else { 724 #ifdef ASSERT 725 // %%%% [phh] We don't check the alias index if cross_check is 726 // TypeRawPtr::BOTTOM. Needs to be investigated. 727 if (cross_check != NULL && 728 cross_check != TypePtr::BOTTOM && 729 cross_check != TypeRawPtr::BOTTOM) { 730 // Recheck the alias index, to see if it has changed (due to a bug). 731 Compile* C = Compile::current(); 732 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 733 "must stay in the original alias category"); 734 // The type of the address must be contained in the adr_type, 735 // disregarding "null"-ness. 736 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 737 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 738 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 739 "real address must not escape from expected memory type"); 740 } 741 #endif 742 return tp; 743 } 744} 745 746//============================================================================= 747// Should LoadNode::Ideal() attempt to remove control edges? 748bool LoadNode::can_remove_control() const { 749 return true; 750} 751uint LoadNode::size_of() const { return sizeof(*this); } 752uint LoadNode::cmp( const Node &n ) const 753{ return !Type::cmp( _type, ((LoadNode&)n)._type ); } 754const Type *LoadNode::bottom_type() const { return _type; } 755uint LoadNode::ideal_reg() const { 756 return _type->ideal_reg(); 757} 758 759#ifndef PRODUCT 760void LoadNode::dump_spec(outputStream *st) const { 761 MemNode::dump_spec(st); 762 if( !Verbose && !WizardMode ) { 763 // standard dump does this in Verbose and WizardMode 764 st->print(" #"); _type->dump_on(st); 765 } 766 if (!depends_only_on_test()) { 767 st->print(" (does not depend only on test)"); 768 } 769} 770#endif 771 772#ifdef ASSERT 773//----------------------------is_immutable_value------------------------------- 774// Helper function to allow a raw load without control edge for some cases 775bool LoadNode::is_immutable_value(Node* adr) { 776 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 777 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 778 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 779 in_bytes(JavaThread::osthread_offset()))); 780} 781#endif 782 783//----------------------------LoadNode::make----------------------------------- 784// Polymorphic factory method: 785Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, 786 ControlDependency control_dependency, bool unaligned, bool mismatched) { 787 Compile* C = gvn.C; 788 789 // sanity check the alias category against the created node type 790 assert(!(adr_type->isa_oopptr() && 791 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 792 "use LoadKlassNode instead"); 793 assert(!(adr_type->isa_aryptr() && 794 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 795 "use LoadRangeNode instead"); 796 // Check control edge of raw loads 797 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 798 // oop will be recorded in oop map if load crosses safepoint 799 rt->isa_oopptr() || is_immutable_value(adr), 800 "raw memory operations should have control edge"); 801 LoadNode* load = NULL; 802 switch (bt) { 803 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 804 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 805 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 806 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 807 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 808 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break; 809 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 810 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 811 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break; 812 case T_OBJECT: 813#ifdef _LP64 814 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 815 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency); 816 } else 817#endif 818 { 819 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 820 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 821 } 822 break; 823 } 824 assert(load != NULL, "LoadNode should have been created"); 825 if (unaligned) { 826 load->set_unaligned_access(); 827 } 828 if (mismatched) { 829 load->set_mismatched_access(); 830 } 831 if (load->Opcode() == Op_LoadN) { 832 Node* ld = gvn.transform(load); 833 return new DecodeNNode(ld, ld->bottom_type()->make_ptr()); 834 } 835 836 return load; 837} 838 839LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 840 ControlDependency control_dependency, bool unaligned, bool mismatched) { 841 bool require_atomic = true; 842 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic); 843 if (unaligned) { 844 load->set_unaligned_access(); 845 } 846 if (mismatched) { 847 load->set_mismatched_access(); 848 } 849 return load; 850} 851 852LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 853 ControlDependency control_dependency, bool unaligned, bool mismatched) { 854 bool require_atomic = true; 855 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic); 856 if (unaligned) { 857 load->set_unaligned_access(); 858 } 859 if (mismatched) { 860 load->set_mismatched_access(); 861 } 862 return load; 863} 864 865 866 867//------------------------------hash------------------------------------------- 868uint LoadNode::hash() const { 869 // unroll addition of interesting fields 870 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 871} 872 873static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 874 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 875 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 876 bool is_stable_ary = FoldStableValues && 877 (tp != NULL) && (tp->isa_aryptr() != NULL) && 878 tp->isa_aryptr()->is_stable(); 879 880 return (eliminate_boxing && non_volatile) || is_stable_ary; 881 } 882 883 return false; 884} 885 886// Is the value loaded previously stored by an arraycopy? If so return 887// a load node that reads from the source array so we may be able to 888// optimize out the ArrayCopy node later. 889Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const { 890 Node* ld_adr = in(MemNode::Address); 891 intptr_t ld_off = 0; 892 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 893 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 894 if (ac != NULL) { 895 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 896 897 Node* ld = clone(); 898 if (ac->as_ArrayCopy()->is_clonebasic()) { 899 assert(ld_alloc != NULL, "need an alloc"); 900 Node* addp = in(MemNode::Address)->clone(); 901 assert(addp->is_AddP(), "address must be addp"); 902 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern"); 903 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern"); 904 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base)); 905 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address)); 906 ld->set_req(MemNode::Address, phase->transform(addp)); 907 if (in(0) != NULL) { 908 assert(ld_alloc->in(0) != NULL, "alloc must have control"); 909 ld->set_req(0, ld_alloc->in(0)); 910 } 911 } else { 912 Node* src = ac->in(ArrayCopyNode::Src); 913 Node* addp = in(MemNode::Address)->clone(); 914 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 915 addp->set_req(AddPNode::Base, src); 916 addp->set_req(AddPNode::Address, src); 917 918 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 919 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 920 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 921 uint shift = exact_log2(type2aelembytes(ary_elem)); 922 923 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 924#ifdef _LP64 925 diff = phase->transform(new ConvI2LNode(diff)); 926#endif 927 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 928 929 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 930 addp->set_req(AddPNode::Offset, offset); 931 ld->set_req(MemNode::Address, phase->transform(addp)); 932 933 const TypeX *ld_offs_t = phase->type(offset)->isa_intptr_t(); 934 935 if (!ac->as_ArrayCopy()->can_replace_dest_load_with_src_load(ld_offs_t->_lo, ld_offs_t->_hi, phase)) { 936 return NULL; 937 } 938 939 if (in(0) != NULL) { 940 assert(ac->in(0) != NULL, "alloc must have control"); 941 ld->set_req(0, ac->in(0)); 942 } 943 } 944 // load depends on the tests that validate the arraycopy 945 ld->as_Load()->_control_dependency = Pinned; 946 return ld; 947 } 948 return NULL; 949} 950 951 952//---------------------------can_see_stored_value------------------------------ 953// This routine exists to make sure this set of tests is done the same 954// everywhere. We need to make a coordinated change: first LoadNode::Ideal 955// will change the graph shape in a way which makes memory alive twice at the 956// same time (uses the Oracle model of aliasing), then some 957// LoadXNode::Identity will fold things back to the equivalence-class model 958// of aliasing. 959Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 960 Node* ld_adr = in(MemNode::Address); 961 intptr_t ld_off = 0; 962 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 963 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 964 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 965 // This is more general than load from boxing objects. 966 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 967 uint alias_idx = atp->index(); 968 bool final = !atp->is_rewritable(); 969 Node* result = NULL; 970 Node* current = st; 971 // Skip through chains of MemBarNodes checking the MergeMems for 972 // new states for the slice of this load. Stop once any other 973 // kind of node is encountered. Loads from final memory can skip 974 // through any kind of MemBar but normal loads shouldn't skip 975 // through MemBarAcquire since the could allow them to move out of 976 // a synchronized region. 977 while (current->is_Proj()) { 978 int opc = current->in(0)->Opcode(); 979 if ((final && (opc == Op_MemBarAcquire || 980 opc == Op_MemBarAcquireLock || 981 opc == Op_LoadFence)) || 982 opc == Op_MemBarRelease || 983 opc == Op_StoreFence || 984 opc == Op_MemBarReleaseLock || 985 opc == Op_MemBarStoreStore || 986 opc == Op_MemBarCPUOrder) { 987 Node* mem = current->in(0)->in(TypeFunc::Memory); 988 if (mem->is_MergeMem()) { 989 MergeMemNode* merge = mem->as_MergeMem(); 990 Node* new_st = merge->memory_at(alias_idx); 991 if (new_st == merge->base_memory()) { 992 // Keep searching 993 current = new_st; 994 continue; 995 } 996 // Save the new memory state for the slice and fall through 997 // to exit. 998 result = new_st; 999 } 1000 } 1001 break; 1002 } 1003 if (result != NULL) { 1004 st = result; 1005 } 1006 } 1007 1008 // Loop around twice in the case Load -> Initialize -> Store. 1009 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1010 for (int trip = 0; trip <= 1; trip++) { 1011 1012 if (st->is_Store()) { 1013 Node* st_adr = st->in(MemNode::Address); 1014 if (!phase->eqv(st_adr, ld_adr)) { 1015 // Try harder before giving up... Match raw and non-raw pointers. 1016 intptr_t st_off = 0; 1017 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 1018 if (alloc == NULL) return NULL; 1019 if (alloc != ld_alloc) return NULL; 1020 if (ld_off != st_off) return NULL; 1021 // At this point we have proven something like this setup: 1022 // A = Allocate(...) 1023 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 1024 // S = StoreQ(, AddP(, A.Parm , #Off), V) 1025 // (Actually, we haven't yet proven the Q's are the same.) 1026 // In other words, we are loading from a casted version of 1027 // the same pointer-and-offset that we stored to. 1028 // Thus, we are able to replace L by V. 1029 } 1030 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1031 if (store_Opcode() != st->Opcode()) 1032 return NULL; 1033 return st->in(MemNode::ValueIn); 1034 } 1035 1036 // A load from a freshly-created object always returns zero. 1037 // (This can happen after LoadNode::Ideal resets the load's memory input 1038 // to find_captured_store, which returned InitializeNode::zero_memory.) 1039 if (st->is_Proj() && st->in(0)->is_Allocate() && 1040 (st->in(0) == ld_alloc) && 1041 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1042 // return a zero value for the load's basic type 1043 // (This is one of the few places where a generic PhaseTransform 1044 // can create new nodes. Think of it as lazily manifesting 1045 // virtually pre-existing constants.) 1046 return phase->zerocon(memory_type()); 1047 } 1048 1049 // A load from an initialization barrier can match a captured store. 1050 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1051 InitializeNode* init = st->in(0)->as_Initialize(); 1052 AllocateNode* alloc = init->allocation(); 1053 if ((alloc != NULL) && (alloc == ld_alloc)) { 1054 // examine a captured store value 1055 st = init->find_captured_store(ld_off, memory_size(), phase); 1056 if (st != NULL) { 1057 continue; // take one more trip around 1058 } 1059 } 1060 } 1061 1062 // Load boxed value from result of valueOf() call is input parameter. 1063 if (this->is_Load() && ld_adr->is_AddP() && 1064 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1065 intptr_t ignore = 0; 1066 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1067 if (base != NULL && base->is_Proj() && 1068 base->as_Proj()->_con == TypeFunc::Parms && 1069 base->in(0)->is_CallStaticJava() && 1070 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1071 return base->in(0)->in(TypeFunc::Parms); 1072 } 1073 } 1074 1075 break; 1076 } 1077 1078 return NULL; 1079} 1080 1081//----------------------is_instance_field_load_with_local_phi------------------ 1082bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1083 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1084 in(Address)->is_AddP() ) { 1085 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1086 // Only instances and boxed values. 1087 if( t_oop != NULL && 1088 (t_oop->is_ptr_to_boxed_value() || 1089 t_oop->is_known_instance_field()) && 1090 t_oop->offset() != Type::OffsetBot && 1091 t_oop->offset() != Type::OffsetTop) { 1092 return true; 1093 } 1094 } 1095 return false; 1096} 1097 1098//------------------------------Identity--------------------------------------- 1099// Loads are identity if previous store is to same address 1100Node* LoadNode::Identity(PhaseGVN* phase) { 1101 // If the previous store-maker is the right kind of Store, and the store is 1102 // to the same address, then we are equal to the value stored. 1103 Node* mem = in(Memory); 1104 Node* value = can_see_stored_value(mem, phase); 1105 if( value ) { 1106 // byte, short & char stores truncate naturally. 1107 // A load has to load the truncated value which requires 1108 // some sort of masking operation and that requires an 1109 // Ideal call instead of an Identity call. 1110 if (memory_size() < BytesPerInt) { 1111 // If the input to the store does not fit with the load's result type, 1112 // it must be truncated via an Ideal call. 1113 if (!phase->type(value)->higher_equal(phase->type(this))) 1114 return this; 1115 } 1116 // (This works even when value is a Con, but LoadNode::Value 1117 // usually runs first, producing the singleton type of the Con.) 1118 return value; 1119 } 1120 1121 // Search for an existing data phi which was generated before for the same 1122 // instance's field to avoid infinite generation of phis in a loop. 1123 Node *region = mem->in(0); 1124 if (is_instance_field_load_with_local_phi(region)) { 1125 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1126 int this_index = phase->C->get_alias_index(addr_t); 1127 int this_offset = addr_t->offset(); 1128 int this_iid = addr_t->instance_id(); 1129 if (!addr_t->is_known_instance() && 1130 addr_t->is_ptr_to_boxed_value()) { 1131 // Use _idx of address base (could be Phi node) for boxed values. 1132 intptr_t ignore = 0; 1133 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1134 if (base == NULL) { 1135 return this; 1136 } 1137 this_iid = base->_idx; 1138 } 1139 const Type* this_type = bottom_type(); 1140 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1141 Node* phi = region->fast_out(i); 1142 if (phi->is_Phi() && phi != mem && 1143 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) { 1144 return phi; 1145 } 1146 } 1147 } 1148 1149 return this; 1150} 1151 1152// Construct an equivalent unsigned load. 1153Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) { 1154 BasicType bt = T_ILLEGAL; 1155 const Type* rt = NULL; 1156 switch (Opcode()) { 1157 case Op_LoadUB: return this; 1158 case Op_LoadUS: return this; 1159 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break; 1160 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break; 1161 default: 1162 assert(false, "no unsigned variant: %s", Name()); 1163 return NULL; 1164 } 1165 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1166 raw_adr_type(), rt, bt, _mo, _control_dependency, 1167 is_unaligned_access(), is_mismatched_access()); 1168} 1169 1170// Construct an equivalent signed load. 1171Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) { 1172 BasicType bt = T_ILLEGAL; 1173 const Type* rt = NULL; 1174 switch (Opcode()) { 1175 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break; 1176 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break; 1177 case Op_LoadB: // fall through 1178 case Op_LoadS: // fall through 1179 case Op_LoadI: // fall through 1180 case Op_LoadL: return this; 1181 default: 1182 assert(false, "no signed variant: %s", Name()); 1183 return NULL; 1184 } 1185 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1186 raw_adr_type(), rt, bt, _mo, _control_dependency, 1187 is_unaligned_access(), is_mismatched_access()); 1188} 1189 1190// We're loading from an object which has autobox behaviour. 1191// If this object is result of a valueOf call we'll have a phi 1192// merging a newly allocated object and a load from the cache. 1193// We want to replace this load with the original incoming 1194// argument to the valueOf call. 1195Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1196 assert(phase->C->eliminate_boxing(), "sanity"); 1197 intptr_t ignore = 0; 1198 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1199 if ((base == NULL) || base->is_Phi()) { 1200 // Push the loads from the phi that comes from valueOf up 1201 // through it to allow elimination of the loads and the recovery 1202 // of the original value. It is done in split_through_phi(). 1203 return NULL; 1204 } else if (base->is_Load() || 1205 base->is_DecodeN() && base->in(1)->is_Load()) { 1206 // Eliminate the load of boxed value for integer types from the cache 1207 // array by deriving the value from the index into the array. 1208 // Capture the offset of the load and then reverse the computation. 1209 1210 // Get LoadN node which loads a boxing object from 'cache' array. 1211 if (base->is_DecodeN()) { 1212 base = base->in(1); 1213 } 1214 if (!base->in(Address)->is_AddP()) { 1215 return NULL; // Complex address 1216 } 1217 AddPNode* address = base->in(Address)->as_AddP(); 1218 Node* cache_base = address->in(AddPNode::Base); 1219 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1220 // Get ConP node which is static 'cache' field. 1221 cache_base = cache_base->in(1); 1222 } 1223 if ((cache_base != NULL) && cache_base->is_Con()) { 1224 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1225 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1226 Node* elements[4]; 1227 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1228 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1229 if ((count > 0) && elements[0]->is_Con() && 1230 ((count == 1) || 1231 (count == 2) && elements[1]->Opcode() == Op_LShiftX && 1232 elements[1]->in(2) == phase->intcon(shift))) { 1233 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1234 // Fetch the box object cache[0] at the base of the array and get its value 1235 ciInstance* box = array->obj_at(0)->as_instance(); 1236 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1237 assert(ik->is_box_klass(), "sanity"); 1238 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1239 if (ik->nof_nonstatic_fields() == 1) { 1240 // This should be true nonstatic_field_at requires calling 1241 // nof_nonstatic_fields so check it anyway 1242 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1243 BasicType bt = c.basic_type(); 1244 // Only integer types have boxing cache. 1245 assert(bt == T_BOOLEAN || bt == T_CHAR || 1246 bt == T_BYTE || bt == T_SHORT || 1247 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt)); 1248 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1249 if (cache_low != (int)cache_low) { 1250 return NULL; // should not happen since cache is array indexed by value 1251 } 1252 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1253 if (offset != (int)offset) { 1254 return NULL; // should not happen since cache is array indexed by value 1255 } 1256 // Add up all the offsets making of the address of the load 1257 Node* result = elements[0]; 1258 for (int i = 1; i < count; i++) { 1259 result = phase->transform(new AddXNode(result, elements[i])); 1260 } 1261 // Remove the constant offset from the address and then 1262 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset))); 1263 // remove the scaling of the offset to recover the original index. 1264 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1265 // Peel the shift off directly but wrap it in a dummy node 1266 // since Ideal can't return existing nodes 1267 result = new RShiftXNode(result->in(1), phase->intcon(0)); 1268 } else if (result->is_Add() && result->in(2)->is_Con() && 1269 result->in(1)->Opcode() == Op_LShiftX && 1270 result->in(1)->in(2) == phase->intcon(shift)) { 1271 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1272 // but for boxing cache access we know that X<<Z will not overflow 1273 // (there is range check) so we do this optimizatrion by hand here. 1274 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift)); 1275 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con)); 1276 } else { 1277 result = new RShiftXNode(result, phase->intcon(shift)); 1278 } 1279#ifdef _LP64 1280 if (bt != T_LONG) { 1281 result = new ConvL2INode(phase->transform(result)); 1282 } 1283#else 1284 if (bt == T_LONG) { 1285 result = new ConvI2LNode(phase->transform(result)); 1286 } 1287#endif 1288 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1289 // Need to preserve unboxing load type if it is unsigned. 1290 switch(this->Opcode()) { 1291 case Op_LoadUB: 1292 result = new AndINode(phase->transform(result), phase->intcon(0xFF)); 1293 break; 1294 case Op_LoadUS: 1295 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF)); 1296 break; 1297 } 1298 return result; 1299 } 1300 } 1301 } 1302 } 1303 } 1304 return NULL; 1305} 1306 1307static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1308 Node* region = phi->in(0); 1309 if (region == NULL) { 1310 return false; // Wait stable graph 1311 } 1312 uint cnt = phi->req(); 1313 for (uint i = 1; i < cnt; i++) { 1314 Node* rc = region->in(i); 1315 if (rc == NULL || phase->type(rc) == Type::TOP) 1316 return false; // Wait stable graph 1317 Node* in = phi->in(i); 1318 if (in == NULL || phase->type(in) == Type::TOP) 1319 return false; // Wait stable graph 1320 } 1321 return true; 1322} 1323//------------------------------split_through_phi------------------------------ 1324// Split instance or boxed field load through Phi. 1325Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1326 Node* mem = in(Memory); 1327 Node* address = in(Address); 1328 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1329 1330 assert((t_oop != NULL) && 1331 (t_oop->is_known_instance_field() || 1332 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1333 1334 Compile* C = phase->C; 1335 intptr_t ignore = 0; 1336 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1337 bool base_is_phi = (base != NULL) && base->is_Phi(); 1338 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1339 (base != NULL) && (base == address->in(AddPNode::Base)) && 1340 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1341 1342 if (!((mem->is_Phi() || base_is_phi) && 1343 (load_boxed_values || t_oop->is_known_instance_field()))) { 1344 return NULL; // memory is not Phi 1345 } 1346 1347 if (mem->is_Phi()) { 1348 if (!stable_phi(mem->as_Phi(), phase)) { 1349 return NULL; // Wait stable graph 1350 } 1351 uint cnt = mem->req(); 1352 // Check for loop invariant memory. 1353 if (cnt == 3) { 1354 for (uint i = 1; i < cnt; i++) { 1355 Node* in = mem->in(i); 1356 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1357 if (m == mem) { 1358 set_req(Memory, mem->in(cnt - i)); 1359 return this; // made change 1360 } 1361 } 1362 } 1363 } 1364 if (base_is_phi) { 1365 if (!stable_phi(base->as_Phi(), phase)) { 1366 return NULL; // Wait stable graph 1367 } 1368 uint cnt = base->req(); 1369 // Check for loop invariant memory. 1370 if (cnt == 3) { 1371 for (uint i = 1; i < cnt; i++) { 1372 if (base->in(i) == base) { 1373 return NULL; // Wait stable graph 1374 } 1375 } 1376 } 1377 } 1378 1379 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0)); 1380 1381 // Split through Phi (see original code in loopopts.cpp). 1382 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1383 1384 // Do nothing here if Identity will find a value 1385 // (to avoid infinite chain of value phis generation). 1386 if (!phase->eqv(this, this->Identity(phase))) 1387 return NULL; 1388 1389 // Select Region to split through. 1390 Node* region; 1391 if (!base_is_phi) { 1392 assert(mem->is_Phi(), "sanity"); 1393 region = mem->in(0); 1394 // Skip if the region dominates some control edge of the address. 1395 if (!MemNode::all_controls_dominate(address, region)) 1396 return NULL; 1397 } else if (!mem->is_Phi()) { 1398 assert(base_is_phi, "sanity"); 1399 region = base->in(0); 1400 // Skip if the region dominates some control edge of the memory. 1401 if (!MemNode::all_controls_dominate(mem, region)) 1402 return NULL; 1403 } else if (base->in(0) != mem->in(0)) { 1404 assert(base_is_phi && mem->is_Phi(), "sanity"); 1405 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1406 region = base->in(0); 1407 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1408 region = mem->in(0); 1409 } else { 1410 return NULL; // complex graph 1411 } 1412 } else { 1413 assert(base->in(0) == mem->in(0), "sanity"); 1414 region = mem->in(0); 1415 } 1416 1417 const Type* this_type = this->bottom_type(); 1418 int this_index = C->get_alias_index(t_oop); 1419 int this_offset = t_oop->offset(); 1420 int this_iid = t_oop->instance_id(); 1421 if (!t_oop->is_known_instance() && load_boxed_values) { 1422 // Use _idx of address base for boxed values. 1423 this_iid = base->_idx; 1424 } 1425 PhaseIterGVN* igvn = phase->is_IterGVN(); 1426 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset); 1427 for (uint i = 1; i < region->req(); i++) { 1428 Node* x; 1429 Node* the_clone = NULL; 1430 if (region->in(i) == C->top()) { 1431 x = C->top(); // Dead path? Use a dead data op 1432 } else { 1433 x = this->clone(); // Else clone up the data op 1434 the_clone = x; // Remember for possible deletion. 1435 // Alter data node to use pre-phi inputs 1436 if (this->in(0) == region) { 1437 x->set_req(0, region->in(i)); 1438 } else { 1439 x->set_req(0, NULL); 1440 } 1441 if (mem->is_Phi() && (mem->in(0) == region)) { 1442 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1443 } 1444 if (address->is_Phi() && address->in(0) == region) { 1445 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1446 } 1447 if (base_is_phi && (base->in(0) == region)) { 1448 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1449 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1450 x->set_req(Address, adr_x); 1451 } 1452 } 1453 // Check for a 'win' on some paths 1454 const Type *t = x->Value(igvn); 1455 1456 bool singleton = t->singleton(); 1457 1458 // See comments in PhaseIdealLoop::split_thru_phi(). 1459 if (singleton && t == Type::TOP) { 1460 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1461 } 1462 1463 if (singleton) { 1464 x = igvn->makecon(t); 1465 } else { 1466 // We now call Identity to try to simplify the cloned node. 1467 // Note that some Identity methods call phase->type(this). 1468 // Make sure that the type array is big enough for 1469 // our new node, even though we may throw the node away. 1470 // (This tweaking with igvn only works because x is a new node.) 1471 igvn->set_type(x, t); 1472 // If x is a TypeNode, capture any more-precise type permanently into Node 1473 // otherwise it will be not updated during igvn->transform since 1474 // igvn->type(x) is set to x->Value() already. 1475 x->raise_bottom_type(t); 1476 Node *y = x->Identity(igvn); 1477 if (y != x) { 1478 x = y; 1479 } else { 1480 y = igvn->hash_find_insert(x); 1481 if (y) { 1482 x = y; 1483 } else { 1484 // Else x is a new node we are keeping 1485 // We do not need register_new_node_with_optimizer 1486 // because set_type has already been called. 1487 igvn->_worklist.push(x); 1488 } 1489 } 1490 } 1491 if (x != the_clone && the_clone != NULL) { 1492 igvn->remove_dead_node(the_clone); 1493 } 1494 phi->set_req(i, x); 1495 } 1496 // Record Phi 1497 igvn->register_new_node_with_optimizer(phi); 1498 return phi; 1499} 1500 1501//------------------------------Ideal------------------------------------------ 1502// If the load is from Field memory and the pointer is non-null, it might be possible to 1503// zero out the control input. 1504// If the offset is constant and the base is an object allocation, 1505// try to hook me up to the exact initializing store. 1506Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1507 Node* p = MemNode::Ideal_common(phase, can_reshape); 1508 if (p) return (p == NodeSentinel) ? NULL : p; 1509 1510 Node* ctrl = in(MemNode::Control); 1511 Node* address = in(MemNode::Address); 1512 bool progress = false; 1513 1514 // Skip up past a SafePoint control. Cannot do this for Stores because 1515 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1516 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1517 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1518 ctrl = ctrl->in(0); 1519 set_req(MemNode::Control,ctrl); 1520 progress = true; 1521 } 1522 1523 intptr_t ignore = 0; 1524 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1525 if (base != NULL 1526 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1527 // Check for useless control edge in some common special cases 1528 if (in(MemNode::Control) != NULL 1529 && can_remove_control() 1530 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1531 && all_controls_dominate(base, phase->C->start())) { 1532 // A method-invariant, non-null address (constant or 'this' argument). 1533 set_req(MemNode::Control, NULL); 1534 progress = true; 1535 } 1536 } 1537 1538 Node* mem = in(MemNode::Memory); 1539 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1540 1541 if (can_reshape && (addr_t != NULL)) { 1542 // try to optimize our memory input 1543 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1544 if (opt_mem != mem) { 1545 set_req(MemNode::Memory, opt_mem); 1546 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1547 return this; 1548 } 1549 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1550 if ((t_oop != NULL) && 1551 (t_oop->is_known_instance_field() || 1552 t_oop->is_ptr_to_boxed_value())) { 1553 PhaseIterGVN *igvn = phase->is_IterGVN(); 1554 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1555 // Delay this transformation until memory Phi is processed. 1556 phase->is_IterGVN()->_worklist.push(this); 1557 return NULL; 1558 } 1559 // Split instance field load through Phi. 1560 Node* result = split_through_phi(phase); 1561 if (result != NULL) return result; 1562 1563 if (t_oop->is_ptr_to_boxed_value()) { 1564 Node* result = eliminate_autobox(phase); 1565 if (result != NULL) return result; 1566 } 1567 } 1568 } 1569 1570 // Is there a dominating load that loads the same value? Leave 1571 // anything that is not a load of a field/array element (like 1572 // barriers etc.) alone 1573 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) { 1574 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 1575 Node *use = mem->fast_out(i); 1576 if (use != this && 1577 use->Opcode() == Opcode() && 1578 use->in(0) != NULL && 1579 use->in(0) != in(0) && 1580 use->in(Address) == in(Address)) { 1581 Node* ctl = in(0); 1582 for (int i = 0; i < 10 && ctl != NULL; i++) { 1583 ctl = IfNode::up_one_dom(ctl); 1584 if (ctl == use->in(0)) { 1585 set_req(0, use->in(0)); 1586 return this; 1587 } 1588 } 1589 } 1590 } 1591 } 1592 1593 // Check for prior store with a different base or offset; make Load 1594 // independent. Skip through any number of them. Bail out if the stores 1595 // are in an endless dead cycle and report no progress. This is a key 1596 // transform for Reflection. However, if after skipping through the Stores 1597 // we can't then fold up against a prior store do NOT do the transform as 1598 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1599 // array memory alive twice: once for the hoisted Load and again after the 1600 // bypassed Store. This situation only works if EVERYBODY who does 1601 // anti-dependence work knows how to bypass. I.e. we need all 1602 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1603 // the alias index stuff. So instead, peek through Stores and IFF we can 1604 // fold up, do so. 1605 Node* prev_mem = find_previous_store(phase); 1606 if (prev_mem != NULL) { 1607 Node* value = can_see_arraycopy_value(prev_mem, phase); 1608 if (value != NULL) { 1609 return value; 1610 } 1611 } 1612 // Steps (a), (b): Walk past independent stores to find an exact match. 1613 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1614 // (c) See if we can fold up on the spot, but don't fold up here. 1615 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1616 // just return a prior value, which is done by Identity calls. 1617 if (can_see_stored_value(prev_mem, phase)) { 1618 // Make ready for step (d): 1619 set_req(MemNode::Memory, prev_mem); 1620 return this; 1621 } 1622 } 1623 1624 return progress ? this : NULL; 1625} 1626 1627// Helper to recognize certain Klass fields which are invariant across 1628// some group of array types (e.g., int[] or all T[] where T < Object). 1629const Type* 1630LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1631 ciKlass* klass) const { 1632 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1633 // The field is Klass::_modifier_flags. Return its (constant) value. 1634 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1635 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1636 return TypeInt::make(klass->modifier_flags()); 1637 } 1638 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1639 // The field is Klass::_access_flags. Return its (constant) value. 1640 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1641 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1642 return TypeInt::make(klass->access_flags()); 1643 } 1644 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1645 // The field is Klass::_layout_helper. Return its constant value if known. 1646 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1647 return TypeInt::make(klass->layout_helper()); 1648 } 1649 1650 // No match. 1651 return NULL; 1652} 1653 1654//------------------------------Value----------------------------------------- 1655const Type* LoadNode::Value(PhaseGVN* phase) const { 1656 // Either input is TOP ==> the result is TOP 1657 Node* mem = in(MemNode::Memory); 1658 const Type *t1 = phase->type(mem); 1659 if (t1 == Type::TOP) return Type::TOP; 1660 Node* adr = in(MemNode::Address); 1661 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1662 if (tp == NULL || tp->empty()) return Type::TOP; 1663 int off = tp->offset(); 1664 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1665 Compile* C = phase->C; 1666 1667 // Try to guess loaded type from pointer type 1668 if (tp->isa_aryptr()) { 1669 const TypeAryPtr* ary = tp->is_aryptr(); 1670 const Type* t = ary->elem(); 1671 1672 // Determine whether the reference is beyond the header or not, by comparing 1673 // the offset against the offset of the start of the array's data. 1674 // Different array types begin at slightly different offsets (12 vs. 16). 1675 // We choose T_BYTE as an example base type that is least restrictive 1676 // as to alignment, which will therefore produce the smallest 1677 // possible base offset. 1678 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1679 const bool off_beyond_header = ((uint)off >= (uint)min_base_off); 1680 1681 // Try to constant-fold a stable array element. 1682 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) { 1683 // Make sure the reference is not into the header and the offset is constant 1684 ciObject* aobj = ary->const_oop(); 1685 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1686 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0); 1687 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, 1688 stable_dimension, 1689 memory_type(), is_unsigned()); 1690 if (con_type != NULL) { 1691 return con_type; 1692 } 1693 } 1694 } 1695 1696 // Don't do this for integer types. There is only potential profit if 1697 // the element type t is lower than _type; that is, for int types, if _type is 1698 // more restrictive than t. This only happens here if one is short and the other 1699 // char (both 16 bits), and in those cases we've made an intentional decision 1700 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1701 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1702 // 1703 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1704 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1705 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1706 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1707 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1708 // In fact, that could have been the original type of p1, and p1 could have 1709 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1710 // expression (LShiftL quux 3) independently optimized to the constant 8. 1711 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1712 && (_type->isa_vect() == NULL) 1713 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1714 // t might actually be lower than _type, if _type is a unique 1715 // concrete subclass of abstract class t. 1716 if (off_beyond_header) { // is the offset beyond the header? 1717 const Type* jt = t->join_speculative(_type); 1718 // In any case, do not allow the join, per se, to empty out the type. 1719 if (jt->empty() && !t->empty()) { 1720 // This can happen if a interface-typed array narrows to a class type. 1721 jt = _type; 1722 } 1723#ifdef ASSERT 1724 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1725 // The pointers in the autobox arrays are always non-null 1726 Node* base = adr->in(AddPNode::Base); 1727 if ((base != NULL) && base->is_DecodeN()) { 1728 // Get LoadN node which loads IntegerCache.cache field 1729 base = base->in(1); 1730 } 1731 if ((base != NULL) && base->is_Con()) { 1732 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1733 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1734 // It could be narrow oop 1735 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1736 } 1737 } 1738 } 1739#endif 1740 return jt; 1741 } 1742 } 1743 } else if (tp->base() == Type::InstPtr) { 1744 assert( off != Type::OffsetBot || 1745 // arrays can be cast to Objects 1746 tp->is_oopptr()->klass()->is_java_lang_Object() || 1747 // unsafe field access may not have a constant offset 1748 C->has_unsafe_access(), 1749 "Field accesses must be precise" ); 1750 // For oop loads, we expect the _type to be precise. 1751 1752 // Optimize loads from constant fields. 1753 const TypeInstPtr* tinst = tp->is_instptr(); 1754 ciObject* const_oop = tinst->const_oop(); 1755 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) { 1756 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type()); 1757 if (con_type != NULL) { 1758 return con_type; 1759 } 1760 } 1761 } else if (tp->base() == Type::KlassPtr) { 1762 assert( off != Type::OffsetBot || 1763 // arrays can be cast to Objects 1764 tp->is_klassptr()->klass()->is_java_lang_Object() || 1765 // also allow array-loading from the primary supertype 1766 // array during subtype checks 1767 Opcode() == Op_LoadKlass, 1768 "Field accesses must be precise" ); 1769 // For klass/static loads, we expect the _type to be precise 1770 } 1771 1772 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1773 if (tkls != NULL && !StressReflectiveCode) { 1774 ciKlass* klass = tkls->klass(); 1775 if (klass->is_loaded() && tkls->klass_is_exact()) { 1776 // We are loading a field from a Klass metaobject whose identity 1777 // is known at compile time (the type is "exact" or "precise"). 1778 // Check for fields we know are maintained as constants by the VM. 1779 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1780 // The field is Klass::_super_check_offset. Return its (constant) value. 1781 // (Folds up type checking code.) 1782 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1783 return TypeInt::make(klass->super_check_offset()); 1784 } 1785 // Compute index into primary_supers array 1786 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1787 // Check for overflowing; use unsigned compare to handle the negative case. 1788 if( depth < ciKlass::primary_super_limit() ) { 1789 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1790 // (Folds up type checking code.) 1791 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1792 ciKlass *ss = klass->super_of_depth(depth); 1793 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1794 } 1795 const Type* aift = load_array_final_field(tkls, klass); 1796 if (aift != NULL) return aift; 1797 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1798 // The field is Klass::_java_mirror. Return its (constant) value. 1799 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1800 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1801 return TypeInstPtr::make(klass->java_mirror()); 1802 } 1803 } 1804 1805 // We can still check if we are loading from the primary_supers array at a 1806 // shallow enough depth. Even though the klass is not exact, entries less 1807 // than or equal to its super depth are correct. 1808 if (klass->is_loaded() ) { 1809 ciType *inner = klass; 1810 while( inner->is_obj_array_klass() ) 1811 inner = inner->as_obj_array_klass()->base_element_type(); 1812 if( inner->is_instance_klass() && 1813 !inner->as_instance_klass()->flags().is_interface() ) { 1814 // Compute index into primary_supers array 1815 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1816 // Check for overflowing; use unsigned compare to handle the negative case. 1817 if( depth < ciKlass::primary_super_limit() && 1818 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1819 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1820 // (Folds up type checking code.) 1821 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1822 ciKlass *ss = klass->super_of_depth(depth); 1823 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1824 } 1825 } 1826 } 1827 1828 // If the type is enough to determine that the thing is not an array, 1829 // we can give the layout_helper a positive interval type. 1830 // This will help short-circuit some reflective code. 1831 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1832 && !klass->is_array_klass() // not directly typed as an array 1833 && !klass->is_interface() // specifically not Serializable & Cloneable 1834 && !klass->is_java_lang_Object() // not the supertype of all T[] 1835 ) { 1836 // Note: When interfaces are reliable, we can narrow the interface 1837 // test to (klass != Serializable && klass != Cloneable). 1838 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1839 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1840 // The key property of this type is that it folds up tests 1841 // for array-ness, since it proves that the layout_helper is positive. 1842 // Thus, a generic value like the basic object layout helper works fine. 1843 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1844 } 1845 } 1846 1847 // If we are loading from a freshly-allocated object, produce a zero, 1848 // if the load is provably beyond the header of the object. 1849 // (Also allow a variable load from a fresh array to produce zero.) 1850 const TypeOopPtr *tinst = tp->isa_oopptr(); 1851 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1852 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 1853 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 1854 Node* value = can_see_stored_value(mem,phase); 1855 if (value != NULL && value->is_Con()) { 1856 assert(value->bottom_type()->higher_equal(_type),"sanity"); 1857 return value->bottom_type(); 1858 } 1859 } 1860 1861 if (is_instance) { 1862 // If we have an instance type and our memory input is the 1863 // programs's initial memory state, there is no matching store, 1864 // so just return a zero of the appropriate type 1865 Node *mem = in(MemNode::Memory); 1866 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1867 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1868 return Type::get_zero_type(_type->basic_type()); 1869 } 1870 } 1871 return _type; 1872} 1873 1874//------------------------------match_edge------------------------------------- 1875// Do we Match on this edge index or not? Match only the address. 1876uint LoadNode::match_edge(uint idx) const { 1877 return idx == MemNode::Address; 1878} 1879 1880//--------------------------LoadBNode::Ideal-------------------------------------- 1881// 1882// If the previous store is to the same address as this load, 1883// and the value stored was larger than a byte, replace this load 1884// with the value stored truncated to a byte. If no truncation is 1885// needed, the replacement is done in LoadNode::Identity(). 1886// 1887Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1888 Node* mem = in(MemNode::Memory); 1889 Node* value = can_see_stored_value(mem,phase); 1890 if( value && !phase->type(value)->higher_equal( _type ) ) { 1891 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) ); 1892 return new RShiftINode(result, phase->intcon(24)); 1893 } 1894 // Identity call will handle the case where truncation is not needed. 1895 return LoadNode::Ideal(phase, can_reshape); 1896} 1897 1898const Type* LoadBNode::Value(PhaseGVN* phase) const { 1899 Node* mem = in(MemNode::Memory); 1900 Node* value = can_see_stored_value(mem,phase); 1901 if (value != NULL && value->is_Con() && 1902 !value->bottom_type()->higher_equal(_type)) { 1903 // If the input to the store does not fit with the load's result type, 1904 // it must be truncated. We can't delay until Ideal call since 1905 // a singleton Value is needed for split_thru_phi optimization. 1906 int con = value->get_int(); 1907 return TypeInt::make((con << 24) >> 24); 1908 } 1909 return LoadNode::Value(phase); 1910} 1911 1912//--------------------------LoadUBNode::Ideal------------------------------------- 1913// 1914// If the previous store is to the same address as this load, 1915// and the value stored was larger than a byte, replace this load 1916// with the value stored truncated to a byte. If no truncation is 1917// needed, the replacement is done in LoadNode::Identity(). 1918// 1919Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 1920 Node* mem = in(MemNode::Memory); 1921 Node* value = can_see_stored_value(mem, phase); 1922 if (value && !phase->type(value)->higher_equal(_type)) 1923 return new AndINode(value, phase->intcon(0xFF)); 1924 // Identity call will handle the case where truncation is not needed. 1925 return LoadNode::Ideal(phase, can_reshape); 1926} 1927 1928const Type* LoadUBNode::Value(PhaseGVN* phase) const { 1929 Node* mem = in(MemNode::Memory); 1930 Node* value = can_see_stored_value(mem,phase); 1931 if (value != NULL && value->is_Con() && 1932 !value->bottom_type()->higher_equal(_type)) { 1933 // If the input to the store does not fit with the load's result type, 1934 // it must be truncated. We can't delay until Ideal call since 1935 // a singleton Value is needed for split_thru_phi optimization. 1936 int con = value->get_int(); 1937 return TypeInt::make(con & 0xFF); 1938 } 1939 return LoadNode::Value(phase); 1940} 1941 1942//--------------------------LoadUSNode::Ideal------------------------------------- 1943// 1944// If the previous store is to the same address as this load, 1945// and the value stored was larger than a char, replace this load 1946// with the value stored truncated to a char. If no truncation is 1947// needed, the replacement is done in LoadNode::Identity(). 1948// 1949Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1950 Node* mem = in(MemNode::Memory); 1951 Node* value = can_see_stored_value(mem,phase); 1952 if( value && !phase->type(value)->higher_equal( _type ) ) 1953 return new AndINode(value,phase->intcon(0xFFFF)); 1954 // Identity call will handle the case where truncation is not needed. 1955 return LoadNode::Ideal(phase, can_reshape); 1956} 1957 1958const Type* LoadUSNode::Value(PhaseGVN* phase) const { 1959 Node* mem = in(MemNode::Memory); 1960 Node* value = can_see_stored_value(mem,phase); 1961 if (value != NULL && value->is_Con() && 1962 !value->bottom_type()->higher_equal(_type)) { 1963 // If the input to the store does not fit with the load's result type, 1964 // it must be truncated. We can't delay until Ideal call since 1965 // a singleton Value is needed for split_thru_phi optimization. 1966 int con = value->get_int(); 1967 return TypeInt::make(con & 0xFFFF); 1968 } 1969 return LoadNode::Value(phase); 1970} 1971 1972//--------------------------LoadSNode::Ideal-------------------------------------- 1973// 1974// If the previous store is to the same address as this load, 1975// and the value stored was larger than a short, replace this load 1976// with the value stored truncated to a short. If no truncation is 1977// needed, the replacement is done in LoadNode::Identity(). 1978// 1979Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1980 Node* mem = in(MemNode::Memory); 1981 Node* value = can_see_stored_value(mem,phase); 1982 if( value && !phase->type(value)->higher_equal( _type ) ) { 1983 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) ); 1984 return new RShiftINode(result, phase->intcon(16)); 1985 } 1986 // Identity call will handle the case where truncation is not needed. 1987 return LoadNode::Ideal(phase, can_reshape); 1988} 1989 1990const Type* LoadSNode::Value(PhaseGVN* phase) const { 1991 Node* mem = in(MemNode::Memory); 1992 Node* value = can_see_stored_value(mem,phase); 1993 if (value != NULL && value->is_Con() && 1994 !value->bottom_type()->higher_equal(_type)) { 1995 // If the input to the store does not fit with the load's result type, 1996 // it must be truncated. We can't delay until Ideal call since 1997 // a singleton Value is needed for split_thru_phi optimization. 1998 int con = value->get_int(); 1999 return TypeInt::make((con << 16) >> 16); 2000 } 2001 return LoadNode::Value(phase); 2002} 2003 2004//============================================================================= 2005//----------------------------LoadKlassNode::make------------------------------ 2006// Polymorphic factory method: 2007Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2008 // sanity check the alias category against the created node type 2009 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2010 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2011#ifdef _LP64 2012 if (adr_type->is_ptr_to_narrowklass()) { 2013 assert(UseCompressedClassPointers, "no compressed klasses"); 2014 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2015 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2016 } 2017#endif 2018 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2019 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2020} 2021 2022//------------------------------Value------------------------------------------ 2023const Type* LoadKlassNode::Value(PhaseGVN* phase) const { 2024 return klass_value_common(phase); 2025} 2026 2027// In most cases, LoadKlassNode does not have the control input set. If the control 2028// input is set, it must not be removed (by LoadNode::Ideal()). 2029bool LoadKlassNode::can_remove_control() const { 2030 return false; 2031} 2032 2033const Type* LoadNode::klass_value_common(PhaseGVN* phase) const { 2034 // Either input is TOP ==> the result is TOP 2035 const Type *t1 = phase->type( in(MemNode::Memory) ); 2036 if (t1 == Type::TOP) return Type::TOP; 2037 Node *adr = in(MemNode::Address); 2038 const Type *t2 = phase->type( adr ); 2039 if (t2 == Type::TOP) return Type::TOP; 2040 const TypePtr *tp = t2->is_ptr(); 2041 if (TypePtr::above_centerline(tp->ptr()) || 2042 tp->ptr() == TypePtr::Null) return Type::TOP; 2043 2044 // Return a more precise klass, if possible 2045 const TypeInstPtr *tinst = tp->isa_instptr(); 2046 if (tinst != NULL) { 2047 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2048 int offset = tinst->offset(); 2049 if (ik == phase->C->env()->Class_klass() 2050 && (offset == java_lang_Class::klass_offset_in_bytes() || 2051 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2052 // We are loading a special hidden field from a Class mirror object, 2053 // the field which points to the VM's Klass metaobject. 2054 ciType* t = tinst->java_mirror_type(); 2055 // java_mirror_type returns non-null for compile-time Class constants. 2056 if (t != NULL) { 2057 // constant oop => constant klass 2058 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2059 if (t->is_void()) { 2060 // We cannot create a void array. Since void is a primitive type return null 2061 // klass. Users of this result need to do a null check on the returned klass. 2062 return TypePtr::NULL_PTR; 2063 } 2064 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2065 } 2066 if (!t->is_klass()) { 2067 // a primitive Class (e.g., int.class) has NULL for a klass field 2068 return TypePtr::NULL_PTR; 2069 } 2070 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2071 return TypeKlassPtr::make(t->as_klass()); 2072 } 2073 // non-constant mirror, so we can't tell what's going on 2074 } 2075 if( !ik->is_loaded() ) 2076 return _type; // Bail out if not loaded 2077 if (offset == oopDesc::klass_offset_in_bytes()) { 2078 if (tinst->klass_is_exact()) { 2079 return TypeKlassPtr::make(ik); 2080 } 2081 // See if we can become precise: no subklasses and no interface 2082 // (Note: We need to support verified interfaces.) 2083 if (!ik->is_interface() && !ik->has_subklass()) { 2084 //assert(!UseExactTypes, "this code should be useless with exact types"); 2085 // Add a dependence; if any subclass added we need to recompile 2086 if (!ik->is_final()) { 2087 // %%% should use stronger assert_unique_concrete_subtype instead 2088 phase->C->dependencies()->assert_leaf_type(ik); 2089 } 2090 // Return precise klass 2091 return TypeKlassPtr::make(ik); 2092 } 2093 2094 // Return root of possible klass 2095 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2096 } 2097 } 2098 2099 // Check for loading klass from an array 2100 const TypeAryPtr *tary = tp->isa_aryptr(); 2101 if( tary != NULL ) { 2102 ciKlass *tary_klass = tary->klass(); 2103 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2104 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2105 if (tary->klass_is_exact()) { 2106 return TypeKlassPtr::make(tary_klass); 2107 } 2108 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2109 // If the klass is an object array, we defer the question to the 2110 // array component klass. 2111 if( ak->is_obj_array_klass() ) { 2112 assert( ak->is_loaded(), "" ); 2113 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2114 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2115 ciInstanceKlass* ik = base_k->as_instance_klass(); 2116 // See if we can become precise: no subklasses and no interface 2117 if (!ik->is_interface() && !ik->has_subklass()) { 2118 //assert(!UseExactTypes, "this code should be useless with exact types"); 2119 // Add a dependence; if any subclass added we need to recompile 2120 if (!ik->is_final()) { 2121 phase->C->dependencies()->assert_leaf_type(ik); 2122 } 2123 // Return precise array klass 2124 return TypeKlassPtr::make(ak); 2125 } 2126 } 2127 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2128 } else { // Found a type-array? 2129 //assert(!UseExactTypes, "this code should be useless with exact types"); 2130 assert( ak->is_type_array_klass(), "" ); 2131 return TypeKlassPtr::make(ak); // These are always precise 2132 } 2133 } 2134 } 2135 2136 // Check for loading klass from an array klass 2137 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2138 if (tkls != NULL && !StressReflectiveCode) { 2139 ciKlass* klass = tkls->klass(); 2140 if( !klass->is_loaded() ) 2141 return _type; // Bail out if not loaded 2142 if( klass->is_obj_array_klass() && 2143 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2144 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2145 // // Always returning precise element type is incorrect, 2146 // // e.g., element type could be object and array may contain strings 2147 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2148 2149 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2150 // according to the element type's subclassing. 2151 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2152 } 2153 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2154 tkls->offset() == in_bytes(Klass::super_offset())) { 2155 ciKlass* sup = klass->as_instance_klass()->super(); 2156 // The field is Klass::_super. Return its (constant) value. 2157 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2158 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2159 } 2160 } 2161 2162 // Bailout case 2163 return LoadNode::Value(phase); 2164} 2165 2166//------------------------------Identity--------------------------------------- 2167// To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2168// Also feed through the klass in Allocate(...klass...)._klass. 2169Node* LoadKlassNode::Identity(PhaseGVN* phase) { 2170 return klass_identity_common(phase); 2171} 2172 2173Node* LoadNode::klass_identity_common(PhaseGVN* phase) { 2174 Node* x = LoadNode::Identity(phase); 2175 if (x != this) return x; 2176 2177 // Take apart the address into an oop and and offset. 2178 // Return 'this' if we cannot. 2179 Node* adr = in(MemNode::Address); 2180 intptr_t offset = 0; 2181 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2182 if (base == NULL) return this; 2183 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2184 if (toop == NULL) return this; 2185 2186 // We can fetch the klass directly through an AllocateNode. 2187 // This works even if the klass is not constant (clone or newArray). 2188 if (offset == oopDesc::klass_offset_in_bytes()) { 2189 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2190 if (allocated_klass != NULL) { 2191 return allocated_klass; 2192 } 2193 } 2194 2195 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2196 // See inline_native_Class_query for occurrences of these patterns. 2197 // Java Example: x.getClass().isAssignableFrom(y) 2198 // 2199 // This improves reflective code, often making the Class 2200 // mirror go completely dead. (Current exception: Class 2201 // mirrors may appear in debug info, but we could clean them out by 2202 // introducing a new debug info operator for Klass*.java_mirror). 2203 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2204 && offset == java_lang_Class::klass_offset_in_bytes()) { 2205 // We are loading a special hidden field from a Class mirror, 2206 // the field which points to its Klass or ArrayKlass metaobject. 2207 if (base->is_Load()) { 2208 Node* adr2 = base->in(MemNode::Address); 2209 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2210 if (tkls != NULL && !tkls->empty() 2211 && (tkls->klass()->is_instance_klass() || 2212 tkls->klass()->is_array_klass()) 2213 && adr2->is_AddP() 2214 ) { 2215 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2216 if (tkls->offset() == mirror_field) { 2217 return adr2->in(AddPNode::Base); 2218 } 2219 } 2220 } 2221 } 2222 2223 return this; 2224} 2225 2226 2227//------------------------------Value------------------------------------------ 2228const Type* LoadNKlassNode::Value(PhaseGVN* phase) const { 2229 const Type *t = klass_value_common(phase); 2230 if (t == Type::TOP) 2231 return t; 2232 2233 return t->make_narrowklass(); 2234} 2235 2236//------------------------------Identity--------------------------------------- 2237// To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2238// Also feed through the klass in Allocate(...klass...)._klass. 2239Node* LoadNKlassNode::Identity(PhaseGVN* phase) { 2240 Node *x = klass_identity_common(phase); 2241 2242 const Type *t = phase->type( x ); 2243 if( t == Type::TOP ) return x; 2244 if( t->isa_narrowklass()) return x; 2245 assert (!t->isa_narrowoop(), "no narrow oop here"); 2246 2247 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2248} 2249 2250//------------------------------Value----------------------------------------- 2251const Type* LoadRangeNode::Value(PhaseGVN* phase) const { 2252 // Either input is TOP ==> the result is TOP 2253 const Type *t1 = phase->type( in(MemNode::Memory) ); 2254 if( t1 == Type::TOP ) return Type::TOP; 2255 Node *adr = in(MemNode::Address); 2256 const Type *t2 = phase->type( adr ); 2257 if( t2 == Type::TOP ) return Type::TOP; 2258 const TypePtr *tp = t2->is_ptr(); 2259 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2260 const TypeAryPtr *tap = tp->isa_aryptr(); 2261 if( !tap ) return _type; 2262 return tap->size(); 2263} 2264 2265//-------------------------------Ideal--------------------------------------- 2266// Feed through the length in AllocateArray(...length...)._length. 2267Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2268 Node* p = MemNode::Ideal_common(phase, can_reshape); 2269 if (p) return (p == NodeSentinel) ? NULL : p; 2270 2271 // Take apart the address into an oop and and offset. 2272 // Return 'this' if we cannot. 2273 Node* adr = in(MemNode::Address); 2274 intptr_t offset = 0; 2275 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2276 if (base == NULL) return NULL; 2277 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2278 if (tary == NULL) return NULL; 2279 2280 // We can fetch the length directly through an AllocateArrayNode. 2281 // This works even if the length is not constant (clone or newArray). 2282 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2283 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2284 if (alloc != NULL) { 2285 Node* allocated_length = alloc->Ideal_length(); 2286 Node* len = alloc->make_ideal_length(tary, phase); 2287 if (allocated_length != len) { 2288 // New CastII improves on this. 2289 return len; 2290 } 2291 } 2292 } 2293 2294 return NULL; 2295} 2296 2297//------------------------------Identity--------------------------------------- 2298// Feed through the length in AllocateArray(...length...)._length. 2299Node* LoadRangeNode::Identity(PhaseGVN* phase) { 2300 Node* x = LoadINode::Identity(phase); 2301 if (x != this) return x; 2302 2303 // Take apart the address into an oop and and offset. 2304 // Return 'this' if we cannot. 2305 Node* adr = in(MemNode::Address); 2306 intptr_t offset = 0; 2307 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2308 if (base == NULL) return this; 2309 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2310 if (tary == NULL) return this; 2311 2312 // We can fetch the length directly through an AllocateArrayNode. 2313 // This works even if the length is not constant (clone or newArray). 2314 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2315 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2316 if (alloc != NULL) { 2317 Node* allocated_length = alloc->Ideal_length(); 2318 // Do not allow make_ideal_length to allocate a CastII node. 2319 Node* len = alloc->make_ideal_length(tary, phase, false); 2320 if (allocated_length == len) { 2321 // Return allocated_length only if it would not be improved by a CastII. 2322 return allocated_length; 2323 } 2324 } 2325 } 2326 2327 return this; 2328 2329} 2330 2331//============================================================================= 2332//---------------------------StoreNode::make----------------------------------- 2333// Polymorphic factory method: 2334StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2335 assert((mo == unordered || mo == release), "unexpected"); 2336 Compile* C = gvn.C; 2337 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2338 ctl != NULL, "raw memory operations should have control edge"); 2339 2340 switch (bt) { 2341 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case 2342 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2343 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2344 case T_CHAR: 2345 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2346 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2347 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2348 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2349 case T_METADATA: 2350 case T_ADDRESS: 2351 case T_OBJECT: 2352#ifdef _LP64 2353 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2354 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2355 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2356 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2357 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2358 adr->bottom_type()->isa_rawptr())) { 2359 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2360 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2361 } 2362#endif 2363 { 2364 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2365 } 2366 } 2367 ShouldNotReachHere(); 2368 return (StoreNode*)NULL; 2369} 2370 2371StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2372 bool require_atomic = true; 2373 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2374} 2375 2376StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2377 bool require_atomic = true; 2378 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2379} 2380 2381 2382//--------------------------bottom_type---------------------------------------- 2383const Type *StoreNode::bottom_type() const { 2384 return Type::MEMORY; 2385} 2386 2387//------------------------------hash------------------------------------------- 2388uint StoreNode::hash() const { 2389 // unroll addition of interesting fields 2390 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2391 2392 // Since they are not commoned, do not hash them: 2393 return NO_HASH; 2394} 2395 2396//------------------------------Ideal------------------------------------------ 2397// Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2398// When a store immediately follows a relevant allocation/initialization, 2399// try to capture it into the initialization, or hoist it above. 2400Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2401 Node* p = MemNode::Ideal_common(phase, can_reshape); 2402 if (p) return (p == NodeSentinel) ? NULL : p; 2403 2404 Node* mem = in(MemNode::Memory); 2405 Node* address = in(MemNode::Address); 2406 // Back-to-back stores to same address? Fold em up. Generally 2407 // unsafe if I have intervening uses... Also disallowed for StoreCM 2408 // since they must follow each StoreP operation. Redundant StoreCMs 2409 // are eliminated just before matching in final_graph_reshape. 2410 { 2411 Node* st = mem; 2412 // If Store 'st' has more than one use, we cannot fold 'st' away. 2413 // For example, 'st' might be the final state at a conditional 2414 // return. Or, 'st' might be used by some node which is live at 2415 // the same time 'st' is live, which might be unschedulable. So, 2416 // require exactly ONE user until such time as we clone 'mem' for 2417 // each of 'mem's uses (thus making the exactly-1-user-rule hold 2418 // true). 2419 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) { 2420 // Looking at a dead closed cycle of memory? 2421 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2422 assert(Opcode() == st->Opcode() || 2423 st->Opcode() == Op_StoreVector || 2424 Opcode() == Op_StoreVector || 2425 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw || 2426 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode 2427 (is_mismatched_access() || st->as_Store()->is_mismatched_access()), 2428 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]); 2429 2430 if (st->in(MemNode::Address)->eqv_uncast(address) && 2431 st->as_Store()->memory_size() <= this->memory_size()) { 2432 Node* use = st->raw_out(0); 2433 phase->igvn_rehash_node_delayed(use); 2434 if (can_reshape) { 2435 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN()); 2436 } else { 2437 // It's OK to do this in the parser, since DU info is always accurate, 2438 // and the parser always refers to nodes via SafePointNode maps. 2439 use->set_req(MemNode::Memory, st->in(MemNode::Memory)); 2440 } 2441 return this; 2442 } 2443 st = st->in(MemNode::Memory); 2444 } 2445 } 2446 2447 2448 // Capture an unaliased, unconditional, simple store into an initializer. 2449 // Or, if it is independent of the allocation, hoist it above the allocation. 2450 if (ReduceFieldZeroing && /*can_reshape &&*/ 2451 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2452 InitializeNode* init = mem->in(0)->as_Initialize(); 2453 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2454 if (offset > 0) { 2455 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2456 // If the InitializeNode captured me, it made a raw copy of me, 2457 // and I need to disappear. 2458 if (moved != NULL) { 2459 // %%% hack to ensure that Ideal returns a new node: 2460 mem = MergeMemNode::make(mem); 2461 return mem; // fold me away 2462 } 2463 } 2464 } 2465 2466 return NULL; // No further progress 2467} 2468 2469//------------------------------Value----------------------------------------- 2470const Type* StoreNode::Value(PhaseGVN* phase) const { 2471 // Either input is TOP ==> the result is TOP 2472 const Type *t1 = phase->type( in(MemNode::Memory) ); 2473 if( t1 == Type::TOP ) return Type::TOP; 2474 const Type *t2 = phase->type( in(MemNode::Address) ); 2475 if( t2 == Type::TOP ) return Type::TOP; 2476 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2477 if( t3 == Type::TOP ) return Type::TOP; 2478 return Type::MEMORY; 2479} 2480 2481//------------------------------Identity--------------------------------------- 2482// Remove redundant stores: 2483// Store(m, p, Load(m, p)) changes to m. 2484// Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2485Node* StoreNode::Identity(PhaseGVN* phase) { 2486 Node* mem = in(MemNode::Memory); 2487 Node* adr = in(MemNode::Address); 2488 Node* val = in(MemNode::ValueIn); 2489 2490 // Load then Store? Then the Store is useless 2491 if (val->is_Load() && 2492 val->in(MemNode::Address)->eqv_uncast(adr) && 2493 val->in(MemNode::Memory )->eqv_uncast(mem) && 2494 val->as_Load()->store_Opcode() == Opcode()) { 2495 return mem; 2496 } 2497 2498 // Two stores in a row of the same value? 2499 if (mem->is_Store() && 2500 mem->in(MemNode::Address)->eqv_uncast(adr) && 2501 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2502 mem->Opcode() == Opcode()) { 2503 return mem; 2504 } 2505 2506 // Store of zero anywhere into a freshly-allocated object? 2507 // Then the store is useless. 2508 // (It must already have been captured by the InitializeNode.) 2509 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2510 // a newly allocated object is already all-zeroes everywhere 2511 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2512 return mem; 2513 } 2514 2515 // the store may also apply to zero-bits in an earlier object 2516 Node* prev_mem = find_previous_store(phase); 2517 // Steps (a), (b): Walk past independent stores to find an exact match. 2518 if (prev_mem != NULL) { 2519 Node* prev_val = can_see_stored_value(prev_mem, phase); 2520 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2521 // prev_val and val might differ by a cast; it would be good 2522 // to keep the more informative of the two. 2523 return mem; 2524 } 2525 } 2526 } 2527 2528 return this; 2529} 2530 2531//------------------------------match_edge------------------------------------- 2532// Do we Match on this edge index or not? Match only memory & value 2533uint StoreNode::match_edge(uint idx) const { 2534 return idx == MemNode::Address || idx == MemNode::ValueIn; 2535} 2536 2537//------------------------------cmp-------------------------------------------- 2538// Do not common stores up together. They generally have to be split 2539// back up anyways, so do not bother. 2540uint StoreNode::cmp( const Node &n ) const { 2541 return (&n == this); // Always fail except on self 2542} 2543 2544//------------------------------Ideal_masked_input----------------------------- 2545// Check for a useless mask before a partial-word store 2546// (StoreB ... (AndI valIn conIa) ) 2547// If (conIa & mask == mask) this simplifies to 2548// (StoreB ... (valIn) ) 2549Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2550 Node *val = in(MemNode::ValueIn); 2551 if( val->Opcode() == Op_AndI ) { 2552 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2553 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2554 set_req(MemNode::ValueIn, val->in(1)); 2555 return this; 2556 } 2557 } 2558 return NULL; 2559} 2560 2561 2562//------------------------------Ideal_sign_extended_input---------------------- 2563// Check for useless sign-extension before a partial-word store 2564// (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2565// If (conIL == conIR && conIR <= num_bits) this simplifies to 2566// (StoreB ... (valIn) ) 2567Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2568 Node *val = in(MemNode::ValueIn); 2569 if( val->Opcode() == Op_RShiftI ) { 2570 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2571 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2572 Node *shl = val->in(1); 2573 if( shl->Opcode() == Op_LShiftI ) { 2574 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2575 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2576 set_req(MemNode::ValueIn, shl->in(1)); 2577 return this; 2578 } 2579 } 2580 } 2581 } 2582 return NULL; 2583} 2584 2585//------------------------------value_never_loaded----------------------------------- 2586// Determine whether there are any possible loads of the value stored. 2587// For simplicity, we actually check if there are any loads from the 2588// address stored to, not just for loads of the value stored by this node. 2589// 2590bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2591 Node *adr = in(Address); 2592 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2593 if (adr_oop == NULL) 2594 return false; 2595 if (!adr_oop->is_known_instance_field()) 2596 return false; // if not a distinct instance, there may be aliases of the address 2597 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2598 Node *use = adr->fast_out(i); 2599 if (use->is_Load() || use->is_LoadStore()) { 2600 return false; 2601 } 2602 } 2603 return true; 2604} 2605 2606//============================================================================= 2607//------------------------------Ideal------------------------------------------ 2608// If the store is from an AND mask that leaves the low bits untouched, then 2609// we can skip the AND operation. If the store is from a sign-extension 2610// (a left shift, then right shift) we can skip both. 2611Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2612 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2613 if( progress != NULL ) return progress; 2614 2615 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2616 if( progress != NULL ) return progress; 2617 2618 // Finally check the default case 2619 return StoreNode::Ideal(phase, can_reshape); 2620} 2621 2622//============================================================================= 2623//------------------------------Ideal------------------------------------------ 2624// If the store is from an AND mask that leaves the low bits untouched, then 2625// we can skip the AND operation 2626Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2627 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2628 if( progress != NULL ) return progress; 2629 2630 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2631 if( progress != NULL ) return progress; 2632 2633 // Finally check the default case 2634 return StoreNode::Ideal(phase, can_reshape); 2635} 2636 2637//============================================================================= 2638//------------------------------Identity--------------------------------------- 2639Node* StoreCMNode::Identity(PhaseGVN* phase) { 2640 // No need to card mark when storing a null ptr 2641 Node* my_store = in(MemNode::OopStore); 2642 if (my_store->is_Store()) { 2643 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2644 if( t1 == TypePtr::NULL_PTR ) { 2645 return in(MemNode::Memory); 2646 } 2647 } 2648 return this; 2649} 2650 2651//============================================================================= 2652//------------------------------Ideal--------------------------------------- 2653Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2654 Node* progress = StoreNode::Ideal(phase, can_reshape); 2655 if (progress != NULL) return progress; 2656 2657 Node* my_store = in(MemNode::OopStore); 2658 if (my_store->is_MergeMem()) { 2659 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2660 set_req(MemNode::OopStore, mem); 2661 return this; 2662 } 2663 2664 return NULL; 2665} 2666 2667//------------------------------Value----------------------------------------- 2668const Type* StoreCMNode::Value(PhaseGVN* phase) const { 2669 // Either input is TOP ==> the result is TOP 2670 const Type *t = phase->type( in(MemNode::Memory) ); 2671 if( t == Type::TOP ) return Type::TOP; 2672 t = phase->type( in(MemNode::Address) ); 2673 if( t == Type::TOP ) return Type::TOP; 2674 t = phase->type( in(MemNode::ValueIn) ); 2675 if( t == Type::TOP ) return Type::TOP; 2676 // If extra input is TOP ==> the result is TOP 2677 t = phase->type( in(MemNode::OopStore) ); 2678 if( t == Type::TOP ) return Type::TOP; 2679 2680 return StoreNode::Value( phase ); 2681} 2682 2683 2684//============================================================================= 2685//----------------------------------SCMemProjNode------------------------------ 2686const Type* SCMemProjNode::Value(PhaseGVN* phase) const 2687{ 2688 return bottom_type(); 2689} 2690 2691//============================================================================= 2692//----------------------------------LoadStoreNode------------------------------ 2693LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2694 : Node(required), 2695 _type(rt), 2696 _adr_type(at) 2697{ 2698 init_req(MemNode::Control, c ); 2699 init_req(MemNode::Memory , mem); 2700 init_req(MemNode::Address, adr); 2701 init_req(MemNode::ValueIn, val); 2702 init_class_id(Class_LoadStore); 2703} 2704 2705uint LoadStoreNode::ideal_reg() const { 2706 return _type->ideal_reg(); 2707} 2708 2709bool LoadStoreNode::result_not_used() const { 2710 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2711 Node *x = fast_out(i); 2712 if (x->Opcode() == Op_SCMemProj) continue; 2713 return false; 2714 } 2715 return true; 2716} 2717 2718uint LoadStoreNode::size_of() const { return sizeof(*this); } 2719 2720//============================================================================= 2721//----------------------------------LoadStoreConditionalNode-------------------- 2722LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 2723 init_req(ExpectedIn, ex ); 2724} 2725 2726//============================================================================= 2727//-------------------------------adr_type-------------------------------------- 2728const TypePtr* ClearArrayNode::adr_type() const { 2729 Node *adr = in(3); 2730 if (adr == NULL) return NULL; // node is dead 2731 return MemNode::calculate_adr_type(adr->bottom_type()); 2732} 2733 2734//------------------------------match_edge------------------------------------- 2735// Do we Match on this edge index or not? Do not match memory 2736uint ClearArrayNode::match_edge(uint idx) const { 2737 return idx > 1; 2738} 2739 2740//------------------------------Identity--------------------------------------- 2741// Clearing a zero length array does nothing 2742Node* ClearArrayNode::Identity(PhaseGVN* phase) { 2743 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2744} 2745 2746//------------------------------Idealize--------------------------------------- 2747// Clearing a short array is faster with stores 2748Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2749 // Already know this is a large node, do not try to ideal it 2750 if (!IdealizeClearArrayNode || _is_large) return NULL; 2751 2752 const int unit = BytesPerLong; 2753 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2754 if (!t) return NULL; 2755 if (!t->is_con()) return NULL; 2756 intptr_t raw_count = t->get_con(); 2757 intptr_t size = raw_count; 2758 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2759 // Clearing nothing uses the Identity call. 2760 // Negative clears are possible on dead ClearArrays 2761 // (see jck test stmt114.stmt11402.val). 2762 if (size <= 0 || size % unit != 0) return NULL; 2763 intptr_t count = size / unit; 2764 // Length too long; communicate this to matchers and assemblers. 2765 // Assemblers are responsible to produce fast hardware clears for it. 2766 if (size > InitArrayShortSize) { 2767 return new ClearArrayNode(in(0), in(1), in(2), in(3), true); 2768 } 2769 Node *mem = in(1); 2770 if( phase->type(mem)==Type::TOP ) return NULL; 2771 Node *adr = in(3); 2772 const Type* at = phase->type(adr); 2773 if( at==Type::TOP ) return NULL; 2774 const TypePtr* atp = at->isa_ptr(); 2775 // adjust atp to be the correct array element address type 2776 if (atp == NULL) atp = TypePtr::BOTTOM; 2777 else atp = atp->add_offset(Type::OffsetBot); 2778 // Get base for derived pointer purposes 2779 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2780 Node *base = adr->in(1); 2781 2782 Node *zero = phase->makecon(TypeLong::ZERO); 2783 Node *off = phase->MakeConX(BytesPerLong); 2784 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2785 count--; 2786 while( count-- ) { 2787 mem = phase->transform(mem); 2788 adr = phase->transform(new AddPNode(base,adr,off)); 2789 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2790 } 2791 return mem; 2792} 2793 2794//----------------------------step_through---------------------------------- 2795// Return allocation input memory edge if it is different instance 2796// or itself if it is the one we are looking for. 2797bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2798 Node* n = *np; 2799 assert(n->is_ClearArray(), "sanity"); 2800 intptr_t offset; 2801 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2802 // This method is called only before Allocate nodes are expanded 2803 // during macro nodes expansion. Before that ClearArray nodes are 2804 // only generated in PhaseMacroExpand::generate_arraycopy() (before 2805 // Allocate nodes are expanded) which follows allocations. 2806 assert(alloc != NULL, "should have allocation"); 2807 if (alloc->_idx == instance_id) { 2808 // Can not bypass initialization of the instance we are looking for. 2809 return false; 2810 } 2811 // Otherwise skip it. 2812 InitializeNode* init = alloc->initialization(); 2813 if (init != NULL) 2814 *np = init->in(TypeFunc::Memory); 2815 else 2816 *np = alloc->in(TypeFunc::Memory); 2817 return true; 2818} 2819 2820//----------------------------clear_memory------------------------------------- 2821// Generate code to initialize object storage to zero. 2822Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2823 intptr_t start_offset, 2824 Node* end_offset, 2825 PhaseGVN* phase) { 2826 intptr_t offset = start_offset; 2827 2828 int unit = BytesPerLong; 2829 if ((offset % unit) != 0) { 2830 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 2831 adr = phase->transform(adr); 2832 const TypePtr* atp = TypeRawPtr::BOTTOM; 2833 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2834 mem = phase->transform(mem); 2835 offset += BytesPerInt; 2836 } 2837 assert((offset % unit) == 0, ""); 2838 2839 // Initialize the remaining stuff, if any, with a ClearArray. 2840 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2841} 2842 2843Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2844 Node* start_offset, 2845 Node* end_offset, 2846 PhaseGVN* phase) { 2847 if (start_offset == end_offset) { 2848 // nothing to do 2849 return mem; 2850 } 2851 2852 int unit = BytesPerLong; 2853 Node* zbase = start_offset; 2854 Node* zend = end_offset; 2855 2856 // Scale to the unit required by the CPU: 2857 if (!Matcher::init_array_count_is_in_bytes) { 2858 Node* shift = phase->intcon(exact_log2(unit)); 2859 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 2860 zend = phase->transform(new URShiftXNode(zend, shift) ); 2861 } 2862 2863 // Bulk clear double-words 2864 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 2865 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 2866 mem = new ClearArrayNode(ctl, mem, zsize, adr, false); 2867 return phase->transform(mem); 2868} 2869 2870Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2871 intptr_t start_offset, 2872 intptr_t end_offset, 2873 PhaseGVN* phase) { 2874 if (start_offset == end_offset) { 2875 // nothing to do 2876 return mem; 2877 } 2878 2879 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2880 intptr_t done_offset = end_offset; 2881 if ((done_offset % BytesPerLong) != 0) { 2882 done_offset -= BytesPerInt; 2883 } 2884 if (done_offset > start_offset) { 2885 mem = clear_memory(ctl, mem, dest, 2886 start_offset, phase->MakeConX(done_offset), phase); 2887 } 2888 if (done_offset < end_offset) { // emit the final 32-bit store 2889 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 2890 adr = phase->transform(adr); 2891 const TypePtr* atp = TypeRawPtr::BOTTOM; 2892 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2893 mem = phase->transform(mem); 2894 done_offset += BytesPerInt; 2895 } 2896 assert(done_offset == end_offset, ""); 2897 return mem; 2898} 2899 2900//============================================================================= 2901MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2902 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2903 _adr_type(C->get_adr_type(alias_idx)) 2904{ 2905 init_class_id(Class_MemBar); 2906 Node* top = C->top(); 2907 init_req(TypeFunc::I_O,top); 2908 init_req(TypeFunc::FramePtr,top); 2909 init_req(TypeFunc::ReturnAdr,top); 2910 if (precedent != NULL) 2911 init_req(TypeFunc::Parms, precedent); 2912} 2913 2914//------------------------------cmp-------------------------------------------- 2915uint MemBarNode::hash() const { return NO_HASH; } 2916uint MemBarNode::cmp( const Node &n ) const { 2917 return (&n == this); // Always fail except on self 2918} 2919 2920//------------------------------make------------------------------------------- 2921MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2922 switch (opcode) { 2923 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 2924 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 2925 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 2926 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 2927 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 2928 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 2929 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 2930 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 2931 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn); 2932 case Op_Initialize: return new InitializeNode(C, atp, pn); 2933 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 2934 default: ShouldNotReachHere(); return NULL; 2935 } 2936} 2937 2938//------------------------------Ideal------------------------------------------ 2939// Return a node which is more "ideal" than the current node. Strip out 2940// control copies 2941Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2942 if (remove_dead_region(phase, can_reshape)) return this; 2943 // Don't bother trying to transform a dead node 2944 if (in(0) && in(0)->is_top()) { 2945 return NULL; 2946 } 2947 2948 bool progress = false; 2949 // Eliminate volatile MemBars for scalar replaced objects. 2950 if (can_reshape && req() == (Precedent+1)) { 2951 bool eliminate = false; 2952 int opc = Opcode(); 2953 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 2954 // Volatile field loads and stores. 2955 Node* my_mem = in(MemBarNode::Precedent); 2956 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 2957 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 2958 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 2959 // replace this Precedent (decodeN) with the Load instead. 2960 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 2961 Node* load_node = my_mem->in(1); 2962 set_req(MemBarNode::Precedent, load_node); 2963 phase->is_IterGVN()->_worklist.push(my_mem); 2964 my_mem = load_node; 2965 } else { 2966 assert(my_mem->unique_out() == this, "sanity"); 2967 del_req(Precedent); 2968 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 2969 my_mem = NULL; 2970 } 2971 progress = true; 2972 } 2973 if (my_mem != NULL && my_mem->is_Mem()) { 2974 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 2975 // Check for scalar replaced object reference. 2976 if( t_oop != NULL && t_oop->is_known_instance_field() && 2977 t_oop->offset() != Type::OffsetBot && 2978 t_oop->offset() != Type::OffsetTop) { 2979 eliminate = true; 2980 } 2981 } 2982 } else if (opc == Op_MemBarRelease) { 2983 // Final field stores. 2984 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 2985 if ((alloc != NULL) && alloc->is_Allocate() && 2986 alloc->as_Allocate()->does_not_escape_thread()) { 2987 // The allocated object does not escape. 2988 eliminate = true; 2989 } 2990 } 2991 if (eliminate) { 2992 // Replace MemBar projections by its inputs. 2993 PhaseIterGVN* igvn = phase->is_IterGVN(); 2994 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 2995 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 2996 // Must return either the original node (now dead) or a new node 2997 // (Do not return a top here, since that would break the uniqueness of top.) 2998 return new ConINode(TypeInt::ZERO); 2999 } 3000 } 3001 return progress ? this : NULL; 3002} 3003 3004//------------------------------Value------------------------------------------ 3005const Type* MemBarNode::Value(PhaseGVN* phase) const { 3006 if( !in(0) ) return Type::TOP; 3007 if( phase->type(in(0)) == Type::TOP ) 3008 return Type::TOP; 3009 return TypeTuple::MEMBAR; 3010} 3011 3012//------------------------------match------------------------------------------ 3013// Construct projections for memory. 3014Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3015 switch (proj->_con) { 3016 case TypeFunc::Control: 3017 case TypeFunc::Memory: 3018 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3019 } 3020 ShouldNotReachHere(); 3021 return NULL; 3022} 3023 3024//===========================InitializeNode==================================== 3025// SUMMARY: 3026// This node acts as a memory barrier on raw memory, after some raw stores. 3027// The 'cooked' oop value feeds from the Initialize, not the Allocation. 3028// The Initialize can 'capture' suitably constrained stores as raw inits. 3029// It can coalesce related raw stores into larger units (called 'tiles'). 3030// It can avoid zeroing new storage for memory units which have raw inits. 3031// At macro-expansion, it is marked 'complete', and does not optimize further. 3032// 3033// EXAMPLE: 3034// The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3035// ctl = incoming control; mem* = incoming memory 3036// (Note: A star * on a memory edge denotes I/O and other standard edges.) 3037// First allocate uninitialized memory and fill in the header: 3038// alloc = (Allocate ctl mem* 16 #short[].klass ...) 3039// ctl := alloc.Control; mem* := alloc.Memory* 3040// rawmem = alloc.Memory; rawoop = alloc.RawAddress 3041// Then initialize to zero the non-header parts of the raw memory block: 3042// init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3043// ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3044// After the initialize node executes, the object is ready for service: 3045// oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3046// Suppose its body is immediately initialized as {1,2}: 3047// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3048// store2 = (StoreC init.Control store1 (+ oop 14) 2) 3049// mem.SLICE(#short[*]) := store2 3050// 3051// DETAILS: 3052// An InitializeNode collects and isolates object initialization after 3053// an AllocateNode and before the next possible safepoint. As a 3054// memory barrier (MemBarNode), it keeps critical stores from drifting 3055// down past any safepoint or any publication of the allocation. 3056// Before this barrier, a newly-allocated object may have uninitialized bits. 3057// After this barrier, it may be treated as a real oop, and GC is allowed. 3058// 3059// The semantics of the InitializeNode include an implicit zeroing of 3060// the new object from object header to the end of the object. 3061// (The object header and end are determined by the AllocateNode.) 3062// 3063// Certain stores may be added as direct inputs to the InitializeNode. 3064// These stores must update raw memory, and they must be to addresses 3065// derived from the raw address produced by AllocateNode, and with 3066// a constant offset. They must be ordered by increasing offset. 3067// The first one is at in(RawStores), the last at in(req()-1). 3068// Unlike most memory operations, they are not linked in a chain, 3069// but are displayed in parallel as users of the rawmem output of 3070// the allocation. 3071// 3072// (See comments in InitializeNode::capture_store, which continue 3073// the example given above.) 3074// 3075// When the associated Allocate is macro-expanded, the InitializeNode 3076// may be rewritten to optimize collected stores. A ClearArrayNode 3077// may also be created at that point to represent any required zeroing. 3078// The InitializeNode is then marked 'complete', prohibiting further 3079// capturing of nearby memory operations. 3080// 3081// During macro-expansion, all captured initializations which store 3082// constant values of 32 bits or smaller are coalesced (if advantageous) 3083// into larger 'tiles' 32 or 64 bits. This allows an object to be 3084// initialized in fewer memory operations. Memory words which are 3085// covered by neither tiles nor non-constant stores are pre-zeroed 3086// by explicit stores of zero. (The code shape happens to do all 3087// zeroing first, then all other stores, with both sequences occurring 3088// in order of ascending offsets.) 3089// 3090// Alternatively, code may be inserted between an AllocateNode and its 3091// InitializeNode, to perform arbitrary initialization of the new object. 3092// E.g., the object copying intrinsics insert complex data transfers here. 3093// The initialization must then be marked as 'complete' disable the 3094// built-in zeroing semantics and the collection of initializing stores. 3095// 3096// While an InitializeNode is incomplete, reads from the memory state 3097// produced by it are optimizable if they match the control edge and 3098// new oop address associated with the allocation/initialization. 3099// They return a stored value (if the offset matches) or else zero. 3100// A write to the memory state, if it matches control and address, 3101// and if it is to a constant offset, may be 'captured' by the 3102// InitializeNode. It is cloned as a raw memory operation and rewired 3103// inside the initialization, to the raw oop produced by the allocation. 3104// Operations on addresses which are provably distinct (e.g., to 3105// other AllocateNodes) are allowed to bypass the initialization. 3106// 3107// The effect of all this is to consolidate object initialization 3108// (both arrays and non-arrays, both piecewise and bulk) into a 3109// single location, where it can be optimized as a unit. 3110// 3111// Only stores with an offset less than TrackedInitializationLimit words 3112// will be considered for capture by an InitializeNode. This puts a 3113// reasonable limit on the complexity of optimized initializations. 3114 3115//---------------------------InitializeNode------------------------------------ 3116InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3117 : _is_complete(Incomplete), _does_not_escape(false), 3118 MemBarNode(C, adr_type, rawoop) 3119{ 3120 init_class_id(Class_Initialize); 3121 3122 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3123 assert(in(RawAddress) == rawoop, "proper init"); 3124 // Note: allocation() can be NULL, for secondary initialization barriers 3125} 3126 3127// Since this node is not matched, it will be processed by the 3128// register allocator. Declare that there are no constraints 3129// on the allocation of the RawAddress edge. 3130const RegMask &InitializeNode::in_RegMask(uint idx) const { 3131 // This edge should be set to top, by the set_complete. But be conservative. 3132 if (idx == InitializeNode::RawAddress) 3133 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3134 return RegMask::Empty; 3135} 3136 3137Node* InitializeNode::memory(uint alias_idx) { 3138 Node* mem = in(Memory); 3139 if (mem->is_MergeMem()) { 3140 return mem->as_MergeMem()->memory_at(alias_idx); 3141 } else { 3142 // incoming raw memory is not split 3143 return mem; 3144 } 3145} 3146 3147bool InitializeNode::is_non_zero() { 3148 if (is_complete()) return false; 3149 remove_extra_zeroes(); 3150 return (req() > RawStores); 3151} 3152 3153void InitializeNode::set_complete(PhaseGVN* phase) { 3154 assert(!is_complete(), "caller responsibility"); 3155 _is_complete = Complete; 3156 3157 // After this node is complete, it contains a bunch of 3158 // raw-memory initializations. There is no need for 3159 // it to have anything to do with non-raw memory effects. 3160 // Therefore, tell all non-raw users to re-optimize themselves, 3161 // after skipping the memory effects of this initialization. 3162 PhaseIterGVN* igvn = phase->is_IterGVN(); 3163 if (igvn) igvn->add_users_to_worklist(this); 3164} 3165 3166// convenience function 3167// return false if the init contains any stores already 3168bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3169 InitializeNode* init = initialization(); 3170 if (init == NULL || init->is_complete()) return false; 3171 init->remove_extra_zeroes(); 3172 // for now, if this allocation has already collected any inits, bail: 3173 if (init->is_non_zero()) return false; 3174 init->set_complete(phase); 3175 return true; 3176} 3177 3178void InitializeNode::remove_extra_zeroes() { 3179 if (req() == RawStores) return; 3180 Node* zmem = zero_memory(); 3181 uint fill = RawStores; 3182 for (uint i = fill; i < req(); i++) { 3183 Node* n = in(i); 3184 if (n->is_top() || n == zmem) continue; // skip 3185 if (fill < i) set_req(fill, n); // compact 3186 ++fill; 3187 } 3188 // delete any empty spaces created: 3189 while (fill < req()) { 3190 del_req(fill); 3191 } 3192} 3193 3194// Helper for remembering which stores go with which offsets. 3195intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3196 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3197 intptr_t offset = -1; 3198 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3199 phase, offset); 3200 if (base == NULL) return -1; // something is dead, 3201 if (offset < 0) return -1; // dead, dead 3202 return offset; 3203} 3204 3205// Helper for proving that an initialization expression is 3206// "simple enough" to be folded into an object initialization. 3207// Attempts to prove that a store's initial value 'n' can be captured 3208// within the initialization without creating a vicious cycle, such as: 3209// { Foo p = new Foo(); p.next = p; } 3210// True for constants and parameters and small combinations thereof. 3211bool InitializeNode::detect_init_independence(Node* n, int& count) { 3212 if (n == NULL) return true; // (can this really happen?) 3213 if (n->is_Proj()) n = n->in(0); 3214 if (n == this) return false; // found a cycle 3215 if (n->is_Con()) return true; 3216 if (n->is_Start()) return true; // params, etc., are OK 3217 if (n->is_Root()) return true; // even better 3218 3219 Node* ctl = n->in(0); 3220 if (ctl != NULL && !ctl->is_top()) { 3221 if (ctl->is_Proj()) ctl = ctl->in(0); 3222 if (ctl == this) return false; 3223 3224 // If we already know that the enclosing memory op is pinned right after 3225 // the init, then any control flow that the store has picked up 3226 // must have preceded the init, or else be equal to the init. 3227 // Even after loop optimizations (which might change control edges) 3228 // a store is never pinned *before* the availability of its inputs. 3229 if (!MemNode::all_controls_dominate(n, this)) 3230 return false; // failed to prove a good control 3231 } 3232 3233 // Check data edges for possible dependencies on 'this'. 3234 if ((count += 1) > 20) return false; // complexity limit 3235 for (uint i = 1; i < n->req(); i++) { 3236 Node* m = n->in(i); 3237 if (m == NULL || m == n || m->is_top()) continue; 3238 uint first_i = n->find_edge(m); 3239 if (i != first_i) continue; // process duplicate edge just once 3240 if (!detect_init_independence(m, count)) { 3241 return false; 3242 } 3243 } 3244 3245 return true; 3246} 3247 3248// Here are all the checks a Store must pass before it can be moved into 3249// an initialization. Returns zero if a check fails. 3250// On success, returns the (constant) offset to which the store applies, 3251// within the initialized memory. 3252intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) { 3253 const int FAIL = 0; 3254 if (st->is_unaligned_access()) { 3255 return FAIL; 3256 } 3257 if (st->req() != MemNode::ValueIn + 1) 3258 return FAIL; // an inscrutable StoreNode (card mark?) 3259 Node* ctl = st->in(MemNode::Control); 3260 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3261 return FAIL; // must be unconditional after the initialization 3262 Node* mem = st->in(MemNode::Memory); 3263 if (!(mem->is_Proj() && mem->in(0) == this)) 3264 return FAIL; // must not be preceded by other stores 3265 Node* adr = st->in(MemNode::Address); 3266 intptr_t offset; 3267 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3268 if (alloc == NULL) 3269 return FAIL; // inscrutable address 3270 if (alloc != allocation()) 3271 return FAIL; // wrong allocation! (store needs to float up) 3272 Node* val = st->in(MemNode::ValueIn); 3273 int complexity_count = 0; 3274 if (!detect_init_independence(val, complexity_count)) 3275 return FAIL; // stored value must be 'simple enough' 3276 3277 // The Store can be captured only if nothing after the allocation 3278 // and before the Store is using the memory location that the store 3279 // overwrites. 3280 bool failed = false; 3281 // If is_complete_with_arraycopy() is true the shape of the graph is 3282 // well defined and is safe so no need for extra checks. 3283 if (!is_complete_with_arraycopy()) { 3284 // We are going to look at each use of the memory state following 3285 // the allocation to make sure nothing reads the memory that the 3286 // Store writes. 3287 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3288 int alias_idx = phase->C->get_alias_index(t_adr); 3289 ResourceMark rm; 3290 Unique_Node_List mems; 3291 mems.push(mem); 3292 Node* unique_merge = NULL; 3293 for (uint next = 0; next < mems.size(); ++next) { 3294 Node *m = mems.at(next); 3295 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3296 Node *n = m->fast_out(j); 3297 if (n->outcnt() == 0) { 3298 continue; 3299 } 3300 if (n == st) { 3301 continue; 3302 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3303 // If the control of this use is different from the control 3304 // of the Store which is right after the InitializeNode then 3305 // this node cannot be between the InitializeNode and the 3306 // Store. 3307 continue; 3308 } else if (n->is_MergeMem()) { 3309 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3310 // We can hit a MergeMemNode (that will likely go away 3311 // later) that is a direct use of the memory state 3312 // following the InitializeNode on the same slice as the 3313 // store node that we'd like to capture. We need to check 3314 // the uses of the MergeMemNode. 3315 mems.push(n); 3316 } 3317 } else if (n->is_Mem()) { 3318 Node* other_adr = n->in(MemNode::Address); 3319 if (other_adr == adr) { 3320 failed = true; 3321 break; 3322 } else { 3323 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3324 if (other_t_adr != NULL) { 3325 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3326 if (other_alias_idx == alias_idx) { 3327 // A load from the same memory slice as the store right 3328 // after the InitializeNode. We check the control of the 3329 // object/array that is loaded from. If it's the same as 3330 // the store control then we cannot capture the store. 3331 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3332 Node* base = other_adr; 3333 assert(base->is_AddP(), "should be addp but is %s", base->Name()); 3334 base = base->in(AddPNode::Base); 3335 if (base != NULL) { 3336 base = base->uncast(); 3337 if (base->is_Proj() && base->in(0) == alloc) { 3338 failed = true; 3339 break; 3340 } 3341 } 3342 } 3343 } 3344 } 3345 } else { 3346 failed = true; 3347 break; 3348 } 3349 } 3350 } 3351 } 3352 if (failed) { 3353 if (!can_reshape) { 3354 // We decided we couldn't capture the store during parsing. We 3355 // should try again during the next IGVN once the graph is 3356 // cleaner. 3357 phase->C->record_for_igvn(st); 3358 } 3359 return FAIL; 3360 } 3361 3362 return offset; // success 3363} 3364 3365// Find the captured store in(i) which corresponds to the range 3366// [start..start+size) in the initialized object. 3367// If there is one, return its index i. If there isn't, return the 3368// negative of the index where it should be inserted. 3369// Return 0 if the queried range overlaps an initialization boundary 3370// or if dead code is encountered. 3371// If size_in_bytes is zero, do not bother with overlap checks. 3372int InitializeNode::captured_store_insertion_point(intptr_t start, 3373 int size_in_bytes, 3374 PhaseTransform* phase) { 3375 const int FAIL = 0, MAX_STORE = BytesPerLong; 3376 3377 if (is_complete()) 3378 return FAIL; // arraycopy got here first; punt 3379 3380 assert(allocation() != NULL, "must be present"); 3381 3382 // no negatives, no header fields: 3383 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3384 3385 // after a certain size, we bail out on tracking all the stores: 3386 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3387 if (start >= ti_limit) return FAIL; 3388 3389 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3390 if (i >= limit) return -(int)i; // not found; here is where to put it 3391 3392 Node* st = in(i); 3393 intptr_t st_off = get_store_offset(st, phase); 3394 if (st_off < 0) { 3395 if (st != zero_memory()) { 3396 return FAIL; // bail out if there is dead garbage 3397 } 3398 } else if (st_off > start) { 3399 // ...we are done, since stores are ordered 3400 if (st_off < start + size_in_bytes) { 3401 return FAIL; // the next store overlaps 3402 } 3403 return -(int)i; // not found; here is where to put it 3404 } else if (st_off < start) { 3405 if (size_in_bytes != 0 && 3406 start < st_off + MAX_STORE && 3407 start < st_off + st->as_Store()->memory_size()) { 3408 return FAIL; // the previous store overlaps 3409 } 3410 } else { 3411 if (size_in_bytes != 0 && 3412 st->as_Store()->memory_size() != size_in_bytes) { 3413 return FAIL; // mismatched store size 3414 } 3415 return i; 3416 } 3417 3418 ++i; 3419 } 3420} 3421 3422// Look for a captured store which initializes at the offset 'start' 3423// with the given size. If there is no such store, and no other 3424// initialization interferes, then return zero_memory (the memory 3425// projection of the AllocateNode). 3426Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3427 PhaseTransform* phase) { 3428 assert(stores_are_sane(phase), ""); 3429 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3430 if (i == 0) { 3431 return NULL; // something is dead 3432 } else if (i < 0) { 3433 return zero_memory(); // just primordial zero bits here 3434 } else { 3435 Node* st = in(i); // here is the store at this position 3436 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3437 return st; 3438 } 3439} 3440 3441// Create, as a raw pointer, an address within my new object at 'offset'. 3442Node* InitializeNode::make_raw_address(intptr_t offset, 3443 PhaseTransform* phase) { 3444 Node* addr = in(RawAddress); 3445 if (offset != 0) { 3446 Compile* C = phase->C; 3447 addr = phase->transform( new AddPNode(C->top(), addr, 3448 phase->MakeConX(offset)) ); 3449 } 3450 return addr; 3451} 3452 3453// Clone the given store, converting it into a raw store 3454// initializing a field or element of my new object. 3455// Caller is responsible for retiring the original store, 3456// with subsume_node or the like. 3457// 3458// From the example above InitializeNode::InitializeNode, 3459// here are the old stores to be captured: 3460// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3461// store2 = (StoreC init.Control store1 (+ oop 14) 2) 3462// 3463// Here is the changed code; note the extra edges on init: 3464// alloc = (Allocate ...) 3465// rawoop = alloc.RawAddress 3466// rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3467// rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3468// init = (Initialize alloc.Control alloc.Memory rawoop 3469// rawstore1 rawstore2) 3470// 3471Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3472 PhaseTransform* phase, bool can_reshape) { 3473 assert(stores_are_sane(phase), ""); 3474 3475 if (start < 0) return NULL; 3476 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3477 3478 Compile* C = phase->C; 3479 int size_in_bytes = st->memory_size(); 3480 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3481 if (i == 0) return NULL; // bail out 3482 Node* prev_mem = NULL; // raw memory for the captured store 3483 if (i > 0) { 3484 prev_mem = in(i); // there is a pre-existing store under this one 3485 set_req(i, C->top()); // temporarily disconnect it 3486 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3487 } else { 3488 i = -i; // no pre-existing store 3489 prev_mem = zero_memory(); // a slice of the newly allocated object 3490 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3491 set_req(--i, C->top()); // reuse this edge; it has been folded away 3492 else 3493 ins_req(i, C->top()); // build a new edge 3494 } 3495 Node* new_st = st->clone(); 3496 new_st->set_req(MemNode::Control, in(Control)); 3497 new_st->set_req(MemNode::Memory, prev_mem); 3498 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3499 new_st = phase->transform(new_st); 3500 3501 // At this point, new_st might have swallowed a pre-existing store 3502 // at the same offset, or perhaps new_st might have disappeared, 3503 // if it redundantly stored the same value (or zero to fresh memory). 3504 3505 // In any case, wire it in: 3506 phase->igvn_rehash_node_delayed(this); 3507 set_req(i, new_st); 3508 3509 // The caller may now kill the old guy. 3510 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3511 assert(check_st == new_st || check_st == NULL, "must be findable"); 3512 assert(!is_complete(), ""); 3513 return new_st; 3514} 3515 3516static bool store_constant(jlong* tiles, int num_tiles, 3517 intptr_t st_off, int st_size, 3518 jlong con) { 3519 if ((st_off & (st_size-1)) != 0) 3520 return false; // strange store offset (assume size==2**N) 3521 address addr = (address)tiles + st_off; 3522 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3523 switch (st_size) { 3524 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3525 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3526 case sizeof(jint): *(jint*) addr = (jint) con; break; 3527 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3528 default: return false; // strange store size (detect size!=2**N here) 3529 } 3530 return true; // return success to caller 3531} 3532 3533// Coalesce subword constants into int constants and possibly 3534// into long constants. The goal, if the CPU permits, 3535// is to initialize the object with a small number of 64-bit tiles. 3536// Also, convert floating-point constants to bit patterns. 3537// Non-constants are not relevant to this pass. 3538// 3539// In terms of the running example on InitializeNode::InitializeNode 3540// and InitializeNode::capture_store, here is the transformation 3541// of rawstore1 and rawstore2 into rawstore12: 3542// alloc = (Allocate ...) 3543// rawoop = alloc.RawAddress 3544// tile12 = 0x00010002 3545// rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3546// init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3547// 3548void 3549InitializeNode::coalesce_subword_stores(intptr_t header_size, 3550 Node* size_in_bytes, 3551 PhaseGVN* phase) { 3552 Compile* C = phase->C; 3553 3554 assert(stores_are_sane(phase), ""); 3555 // Note: After this pass, they are not completely sane, 3556 // since there may be some overlaps. 3557 3558 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3559 3560 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3561 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3562 size_limit = MIN2(size_limit, ti_limit); 3563 size_limit = align_up(size_limit, BytesPerLong); 3564 int num_tiles = size_limit / BytesPerLong; 3565 3566 // allocate space for the tile map: 3567 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3568 jlong tiles_buf[small_len]; 3569 Node* nodes_buf[small_len]; 3570 jlong inits_buf[small_len]; 3571 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3572 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3573 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3574 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3575 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3576 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3577 // tiles: exact bitwise model of all primitive constants 3578 // nodes: last constant-storing node subsumed into the tiles model 3579 // inits: which bytes (in each tile) are touched by any initializations 3580 3581 //// Pass A: Fill in the tile model with any relevant stores. 3582 3583 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3584 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3585 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3586 Node* zmem = zero_memory(); // initially zero memory state 3587 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3588 Node* st = in(i); 3589 intptr_t st_off = get_store_offset(st, phase); 3590 3591 // Figure out the store's offset and constant value: 3592 if (st_off < header_size) continue; //skip (ignore header) 3593 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3594 int st_size = st->as_Store()->memory_size(); 3595 if (st_off + st_size > size_limit) break; 3596 3597 // Record which bytes are touched, whether by constant or not. 3598 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3599 continue; // skip (strange store size) 3600 3601 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3602 if (!val->singleton()) continue; //skip (non-con store) 3603 BasicType type = val->basic_type(); 3604 3605 jlong con = 0; 3606 switch (type) { 3607 case T_INT: con = val->is_int()->get_con(); break; 3608 case T_LONG: con = val->is_long()->get_con(); break; 3609 case T_FLOAT: con = jint_cast(val->getf()); break; 3610 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3611 default: continue; //skip (odd store type) 3612 } 3613 3614 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3615 st->Opcode() == Op_StoreL) { 3616 continue; // This StoreL is already optimal. 3617 } 3618 3619 // Store down the constant. 3620 store_constant(tiles, num_tiles, st_off, st_size, con); 3621 3622 intptr_t j = st_off >> LogBytesPerLong; 3623 3624 if (type == T_INT && st_size == BytesPerInt 3625 && (st_off & BytesPerInt) == BytesPerInt) { 3626 jlong lcon = tiles[j]; 3627 if (!Matcher::isSimpleConstant64(lcon) && 3628 st->Opcode() == Op_StoreI) { 3629 // This StoreI is already optimal by itself. 3630 jint* intcon = (jint*) &tiles[j]; 3631 intcon[1] = 0; // undo the store_constant() 3632 3633 // If the previous store is also optimal by itself, back up and 3634 // undo the action of the previous loop iteration... if we can. 3635 // But if we can't, just let the previous half take care of itself. 3636 st = nodes[j]; 3637 st_off -= BytesPerInt; 3638 con = intcon[0]; 3639 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3640 assert(st_off >= header_size, "still ignoring header"); 3641 assert(get_store_offset(st, phase) == st_off, "must be"); 3642 assert(in(i-1) == zmem, "must be"); 3643 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3644 assert(con == tcon->is_int()->get_con(), "must be"); 3645 // Undo the effects of the previous loop trip, which swallowed st: 3646 intcon[0] = 0; // undo store_constant() 3647 set_req(i-1, st); // undo set_req(i, zmem) 3648 nodes[j] = NULL; // undo nodes[j] = st 3649 --old_subword; // undo ++old_subword 3650 } 3651 continue; // This StoreI is already optimal. 3652 } 3653 } 3654 3655 // This store is not needed. 3656 set_req(i, zmem); 3657 nodes[j] = st; // record for the moment 3658 if (st_size < BytesPerLong) // something has changed 3659 ++old_subword; // includes int/float, but who's counting... 3660 else ++old_long; 3661 } 3662 3663 if ((old_subword + old_long) == 0) 3664 return; // nothing more to do 3665 3666 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3667 // Be sure to insert them before overlapping non-constant stores. 3668 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3669 for (int j = 0; j < num_tiles; j++) { 3670 jlong con = tiles[j]; 3671 jlong init = inits[j]; 3672 if (con == 0) continue; 3673 jint con0, con1; // split the constant, address-wise 3674 jint init0, init1; // split the init map, address-wise 3675 { union { jlong con; jint intcon[2]; } u; 3676 u.con = con; 3677 con0 = u.intcon[0]; 3678 con1 = u.intcon[1]; 3679 u.con = init; 3680 init0 = u.intcon[0]; 3681 init1 = u.intcon[1]; 3682 } 3683 3684 Node* old = nodes[j]; 3685 assert(old != NULL, "need the prior store"); 3686 intptr_t offset = (j * BytesPerLong); 3687 3688 bool split = !Matcher::isSimpleConstant64(con); 3689 3690 if (offset < header_size) { 3691 assert(offset + BytesPerInt >= header_size, "second int counts"); 3692 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3693 split = true; // only the second word counts 3694 // Example: int a[] = { 42 ... } 3695 } else if (con0 == 0 && init0 == -1) { 3696 split = true; // first word is covered by full inits 3697 // Example: int a[] = { ... foo(), 42 ... } 3698 } else if (con1 == 0 && init1 == -1) { 3699 split = true; // second word is covered by full inits 3700 // Example: int a[] = { ... 42, foo() ... } 3701 } 3702 3703 // Here's a case where init0 is neither 0 nor -1: 3704 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3705 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3706 // In this case the tile is not split; it is (jlong)42. 3707 // The big tile is stored down, and then the foo() value is inserted. 3708 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3709 3710 Node* ctl = old->in(MemNode::Control); 3711 Node* adr = make_raw_address(offset, phase); 3712 const TypePtr* atp = TypeRawPtr::BOTTOM; 3713 3714 // One or two coalesced stores to plop down. 3715 Node* st[2]; 3716 intptr_t off[2]; 3717 int nst = 0; 3718 if (!split) { 3719 ++new_long; 3720 off[nst] = offset; 3721 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3722 phase->longcon(con), T_LONG, MemNode::unordered); 3723 } else { 3724 // Omit either if it is a zero. 3725 if (con0 != 0) { 3726 ++new_int; 3727 off[nst] = offset; 3728 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3729 phase->intcon(con0), T_INT, MemNode::unordered); 3730 } 3731 if (con1 != 0) { 3732 ++new_int; 3733 offset += BytesPerInt; 3734 adr = make_raw_address(offset, phase); 3735 off[nst] = offset; 3736 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3737 phase->intcon(con1), T_INT, MemNode::unordered); 3738 } 3739 } 3740 3741 // Insert second store first, then the first before the second. 3742 // Insert each one just before any overlapping non-constant stores. 3743 while (nst > 0) { 3744 Node* st1 = st[--nst]; 3745 C->copy_node_notes_to(st1, old); 3746 st1 = phase->transform(st1); 3747 offset = off[nst]; 3748 assert(offset >= header_size, "do not smash header"); 3749 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3750 guarantee(ins_idx != 0, "must re-insert constant store"); 3751 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3752 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3753 set_req(--ins_idx, st1); 3754 else 3755 ins_req(ins_idx, st1); 3756 } 3757 } 3758 3759 if (PrintCompilation && WizardMode) 3760 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3761 old_subword, old_long, new_int, new_long); 3762 if (C->log() != NULL) 3763 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3764 old_subword, old_long, new_int, new_long); 3765 3766 // Clean up any remaining occurrences of zmem: 3767 remove_extra_zeroes(); 3768} 3769 3770// Explore forward from in(start) to find the first fully initialized 3771// word, and return its offset. Skip groups of subword stores which 3772// together initialize full words. If in(start) is itself part of a 3773// fully initialized word, return the offset of in(start). If there 3774// are no following full-word stores, or if something is fishy, return 3775// a negative value. 3776intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3777 int int_map = 0; 3778 intptr_t int_map_off = 0; 3779 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3780 3781 for (uint i = start, limit = req(); i < limit; i++) { 3782 Node* st = in(i); 3783 3784 intptr_t st_off = get_store_offset(st, phase); 3785 if (st_off < 0) break; // return conservative answer 3786 3787 int st_size = st->as_Store()->memory_size(); 3788 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3789 return st_off; // we found a complete word init 3790 } 3791 3792 // update the map: 3793 3794 intptr_t this_int_off = align_down(st_off, BytesPerInt); 3795 if (this_int_off != int_map_off) { 3796 // reset the map: 3797 int_map = 0; 3798 int_map_off = this_int_off; 3799 } 3800 3801 int subword_off = st_off - this_int_off; 3802 int_map |= right_n_bits(st_size) << subword_off; 3803 if ((int_map & FULL_MAP) == FULL_MAP) { 3804 return this_int_off; // we found a complete word init 3805 } 3806 3807 // Did this store hit or cross the word boundary? 3808 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt); 3809 if (next_int_off == this_int_off + BytesPerInt) { 3810 // We passed the current int, without fully initializing it. 3811 int_map_off = next_int_off; 3812 int_map >>= BytesPerInt; 3813 } else if (next_int_off > this_int_off + BytesPerInt) { 3814 // We passed the current and next int. 3815 return this_int_off + BytesPerInt; 3816 } 3817 } 3818 3819 return -1; 3820} 3821 3822 3823// Called when the associated AllocateNode is expanded into CFG. 3824// At this point, we may perform additional optimizations. 3825// Linearize the stores by ascending offset, to make memory 3826// activity as coherent as possible. 3827Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3828 intptr_t header_size, 3829 Node* size_in_bytes, 3830 PhaseGVN* phase) { 3831 assert(!is_complete(), "not already complete"); 3832 assert(stores_are_sane(phase), ""); 3833 assert(allocation() != NULL, "must be present"); 3834 3835 remove_extra_zeroes(); 3836 3837 if (ReduceFieldZeroing || ReduceBulkZeroing) 3838 // reduce instruction count for common initialization patterns 3839 coalesce_subword_stores(header_size, size_in_bytes, phase); 3840 3841 Node* zmem = zero_memory(); // initially zero memory state 3842 Node* inits = zmem; // accumulating a linearized chain of inits 3843 #ifdef ASSERT 3844 intptr_t first_offset = allocation()->minimum_header_size(); 3845 intptr_t last_init_off = first_offset; // previous init offset 3846 intptr_t last_init_end = first_offset; // previous init offset+size 3847 intptr_t last_tile_end = first_offset; // previous tile offset+size 3848 #endif 3849 intptr_t zeroes_done = header_size; 3850 3851 bool do_zeroing = true; // we might give up if inits are very sparse 3852 int big_init_gaps = 0; // how many large gaps have we seen? 3853 3854 if (UseTLAB && ZeroTLAB) do_zeroing = false; 3855 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3856 3857 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3858 Node* st = in(i); 3859 intptr_t st_off = get_store_offset(st, phase); 3860 if (st_off < 0) 3861 break; // unknown junk in the inits 3862 if (st->in(MemNode::Memory) != zmem) 3863 break; // complicated store chains somehow in list 3864 3865 int st_size = st->as_Store()->memory_size(); 3866 intptr_t next_init_off = st_off + st_size; 3867 3868 if (do_zeroing && zeroes_done < next_init_off) { 3869 // See if this store needs a zero before it or under it. 3870 intptr_t zeroes_needed = st_off; 3871 3872 if (st_size < BytesPerInt) { 3873 // Look for subword stores which only partially initialize words. 3874 // If we find some, we must lay down some word-level zeroes first, 3875 // underneath the subword stores. 3876 // 3877 // Examples: 3878 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3879 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3880 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3881 // 3882 // Note: coalesce_subword_stores may have already done this, 3883 // if it was prompted by constant non-zero subword initializers. 3884 // But this case can still arise with non-constant stores. 3885 3886 intptr_t next_full_store = find_next_fullword_store(i, phase); 3887 3888 // In the examples above: 3889 // in(i) p q r s x y z 3890 // st_off 12 13 14 15 12 13 14 3891 // st_size 1 1 1 1 1 1 1 3892 // next_full_s. 12 16 16 16 16 16 16 3893 // z's_done 12 16 16 16 12 16 12 3894 // z's_needed 12 16 16 16 16 16 16 3895 // zsize 0 0 0 0 4 0 4 3896 if (next_full_store < 0) { 3897 // Conservative tack: Zero to end of current word. 3898 zeroes_needed = align_up(zeroes_needed, BytesPerInt); 3899 } else { 3900 // Zero to beginning of next fully initialized word. 3901 // Or, don't zero at all, if we are already in that word. 3902 assert(next_full_store >= zeroes_needed, "must go forward"); 3903 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3904 zeroes_needed = next_full_store; 3905 } 3906 } 3907 3908 if (zeroes_needed > zeroes_done) { 3909 intptr_t zsize = zeroes_needed - zeroes_done; 3910 // Do some incremental zeroing on rawmem, in parallel with inits. 3911 zeroes_done = align_down(zeroes_done, BytesPerInt); 3912 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3913 zeroes_done, zeroes_needed, 3914 phase); 3915 zeroes_done = zeroes_needed; 3916 if (zsize > InitArrayShortSize && ++big_init_gaps > 2) 3917 do_zeroing = false; // leave the hole, next time 3918 } 3919 } 3920 3921 // Collect the store and move on: 3922 st->set_req(MemNode::Memory, inits); 3923 inits = st; // put it on the linearized chain 3924 set_req(i, zmem); // unhook from previous position 3925 3926 if (zeroes_done == st_off) 3927 zeroes_done = next_init_off; 3928 3929 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3930 3931 #ifdef ASSERT 3932 // Various order invariants. Weaker than stores_are_sane because 3933 // a large constant tile can be filled in by smaller non-constant stores. 3934 assert(st_off >= last_init_off, "inits do not reverse"); 3935 last_init_off = st_off; 3936 const Type* val = NULL; 3937 if (st_size >= BytesPerInt && 3938 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3939 (int)val->basic_type() < (int)T_OBJECT) { 3940 assert(st_off >= last_tile_end, "tiles do not overlap"); 3941 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3942 last_tile_end = MAX2(last_tile_end, next_init_off); 3943 } else { 3944 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong); 3945 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3946 assert(st_off >= last_init_end, "inits do not overlap"); 3947 last_init_end = next_init_off; // it's a non-tile 3948 } 3949 #endif //ASSERT 3950 } 3951 3952 remove_extra_zeroes(); // clear out all the zmems left over 3953 add_req(inits); 3954 3955 if (!(UseTLAB && ZeroTLAB)) { 3956 // If anything remains to be zeroed, zero it all now. 3957 zeroes_done = align_down(zeroes_done, BytesPerInt); 3958 // if it is the last unused 4 bytes of an instance, forget about it 3959 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3960 if (zeroes_done + BytesPerLong >= size_limit) { 3961 AllocateNode* alloc = allocation(); 3962 assert(alloc != NULL, "must be present"); 3963 if (alloc != NULL && alloc->Opcode() == Op_Allocate) { 3964 Node* klass_node = alloc->in(AllocateNode::KlassNode); 3965 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3966 if (zeroes_done == k->layout_helper()) 3967 zeroes_done = size_limit; 3968 } 3969 } 3970 if (zeroes_done < size_limit) { 3971 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3972 zeroes_done, size_in_bytes, phase); 3973 } 3974 } 3975 3976 set_complete(phase); 3977 return rawmem; 3978} 3979 3980 3981#ifdef ASSERT 3982bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3983 if (is_complete()) 3984 return true; // stores could be anything at this point 3985 assert(allocation() != NULL, "must be present"); 3986 intptr_t last_off = allocation()->minimum_header_size(); 3987 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3988 Node* st = in(i); 3989 intptr_t st_off = get_store_offset(st, phase); 3990 if (st_off < 0) continue; // ignore dead garbage 3991 if (last_off > st_off) { 3992 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 3993 this->dump(2); 3994 assert(false, "ascending store offsets"); 3995 return false; 3996 } 3997 last_off = st_off + st->as_Store()->memory_size(); 3998 } 3999 return true; 4000} 4001#endif //ASSERT 4002 4003 4004 4005 4006//============================MergeMemNode===================================== 4007// 4008// SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4009// contributing store or call operations. Each contributor provides the memory 4010// state for a particular "alias type" (see Compile::alias_type). For example, 4011// if a MergeMem has an input X for alias category #6, then any memory reference 4012// to alias category #6 may use X as its memory state input, as an exact equivalent 4013// to using the MergeMem as a whole. 4014// Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4015// 4016// (Here, the <N> notation gives the index of the relevant adr_type.) 4017// 4018// In one special case (and more cases in the future), alias categories overlap. 4019// The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4020// states. Therefore, if a MergeMem has only one contributing input W for Bot, 4021// it is exactly equivalent to that state W: 4022// MergeMem(<Bot>: W) <==> W 4023// 4024// Usually, the merge has more than one input. In that case, where inputs 4025// overlap (i.e., one is Bot), the narrower alias type determines the memory 4026// state for that type, and the wider alias type (Bot) fills in everywhere else: 4027// Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4028// Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4029// 4030// A merge can take a "wide" memory state as one of its narrow inputs. 4031// This simply means that the merge observes out only the relevant parts of 4032// the wide input. That is, wide memory states arriving at narrow merge inputs 4033// are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4034// 4035// These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4036// and that memory slices "leak through": 4037// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4038// 4039// But, in such a cascade, repeated memory slices can "block the leak": 4040// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4041// 4042// In the last example, Y is not part of the combined memory state of the 4043// outermost MergeMem. The system must, of course, prevent unschedulable 4044// memory states from arising, so you can be sure that the state Y is somehow 4045// a precursor to state Y'. 4046// 4047// 4048// REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4049// of each MergeMemNode array are exactly the numerical alias indexes, including 4050// but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4051// Compile::alias_type (and kin) produce and manage these indexes. 4052// 4053// By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4054// (Note that this provides quick access to the top node inside MergeMem methods, 4055// without the need to reach out via TLS to Compile::current.) 4056// 4057// As a consequence of what was just described, a MergeMem that represents a full 4058// memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4059// containing all alias categories. 4060// 4061// MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4062// 4063// All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4064// a memory state for the alias type <N>, or else the top node, meaning that 4065// there is no particular input for that alias type. Note that the length of 4066// a MergeMem is variable, and may be extended at any time to accommodate new 4067// memory states at larger alias indexes. When merges grow, they are of course 4068// filled with "top" in the unused in() positions. 4069// 4070// This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4071// (Top was chosen because it works smoothly with passes like GCM.) 4072// 4073// For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4074// the type of random VM bits like TLS references.) Since it is always the 4075// first non-Bot memory slice, some low-level loops use it to initialize an 4076// index variable: for (i = AliasIdxRaw; i < req(); i++). 4077// 4078// 4079// ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4080// the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4081// the memory state for alias type <N>, or (if there is no particular slice at <N>, 4082// it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4083// or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4084// MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4085// 4086// %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4087// really that different from the other memory inputs. An abbreviation called 4088// "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4089// 4090// 4091// PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4092// partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4093// that "emerges though" the base memory will be marked as excluding the alias types 4094// of the other (narrow-memory) copies which "emerged through" the narrow edges: 4095// 4096// Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4097// ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4098// 4099// This strange "subtraction" effect is necessary to ensure IGVN convergence. 4100// (It is currently unimplemented.) As you can see, the resulting merge is 4101// actually a disjoint union of memory states, rather than an overlay. 4102// 4103 4104//------------------------------MergeMemNode----------------------------------- 4105Node* MergeMemNode::make_empty_memory() { 4106 Node* empty_memory = (Node*) Compile::current()->top(); 4107 assert(empty_memory->is_top(), "correct sentinel identity"); 4108 return empty_memory; 4109} 4110 4111MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4112 init_class_id(Class_MergeMem); 4113 // all inputs are nullified in Node::Node(int) 4114 // set_input(0, NULL); // no control input 4115 4116 // Initialize the edges uniformly to top, for starters. 4117 Node* empty_mem = make_empty_memory(); 4118 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4119 init_req(i,empty_mem); 4120 } 4121 assert(empty_memory() == empty_mem, ""); 4122 4123 if( new_base != NULL && new_base->is_MergeMem() ) { 4124 MergeMemNode* mdef = new_base->as_MergeMem(); 4125 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4126 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4127 mms.set_memory(mms.memory2()); 4128 } 4129 assert(base_memory() == mdef->base_memory(), ""); 4130 } else { 4131 set_base_memory(new_base); 4132 } 4133} 4134 4135// Make a new, untransformed MergeMem with the same base as 'mem'. 4136// If mem is itself a MergeMem, populate the result with the same edges. 4137MergeMemNode* MergeMemNode::make(Node* mem) { 4138 return new MergeMemNode(mem); 4139} 4140 4141//------------------------------cmp-------------------------------------------- 4142uint MergeMemNode::hash() const { return NO_HASH; } 4143uint MergeMemNode::cmp( const Node &n ) const { 4144 return (&n == this); // Always fail except on self 4145} 4146 4147//------------------------------Identity--------------------------------------- 4148Node* MergeMemNode::Identity(PhaseGVN* phase) { 4149 // Identity if this merge point does not record any interesting memory 4150 // disambiguations. 4151 Node* base_mem = base_memory(); 4152 Node* empty_mem = empty_memory(); 4153 if (base_mem != empty_mem) { // Memory path is not dead? 4154 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4155 Node* mem = in(i); 4156 if (mem != empty_mem && mem != base_mem) { 4157 return this; // Many memory splits; no change 4158 } 4159 } 4160 } 4161 return base_mem; // No memory splits; ID on the one true input 4162} 4163 4164//------------------------------Ideal------------------------------------------ 4165// This method is invoked recursively on chains of MergeMem nodes 4166Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4167 // Remove chain'd MergeMems 4168 // 4169 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4170 // relative to the "in(Bot)". Since we are patching both at the same time, 4171 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4172 // but rewrite each "in(i)" relative to the new "in(Bot)". 4173 Node *progress = NULL; 4174 4175 4176 Node* old_base = base_memory(); 4177 Node* empty_mem = empty_memory(); 4178 if (old_base == empty_mem) 4179 return NULL; // Dead memory path. 4180 4181 MergeMemNode* old_mbase; 4182 if (old_base != NULL && old_base->is_MergeMem()) 4183 old_mbase = old_base->as_MergeMem(); 4184 else 4185 old_mbase = NULL; 4186 Node* new_base = old_base; 4187 4188 // simplify stacked MergeMems in base memory 4189 if (old_mbase) new_base = old_mbase->base_memory(); 4190 4191 // the base memory might contribute new slices beyond my req() 4192 if (old_mbase) grow_to_match(old_mbase); 4193 4194 // Look carefully at the base node if it is a phi. 4195 PhiNode* phi_base; 4196 if (new_base != NULL && new_base->is_Phi()) 4197 phi_base = new_base->as_Phi(); 4198 else 4199 phi_base = NULL; 4200 4201 Node* phi_reg = NULL; 4202 uint phi_len = (uint)-1; 4203 if (phi_base != NULL && !phi_base->is_copy()) { 4204 // do not examine phi if degraded to a copy 4205 phi_reg = phi_base->region(); 4206 phi_len = phi_base->req(); 4207 // see if the phi is unfinished 4208 for (uint i = 1; i < phi_len; i++) { 4209 if (phi_base->in(i) == NULL) { 4210 // incomplete phi; do not look at it yet! 4211 phi_reg = NULL; 4212 phi_len = (uint)-1; 4213 break; 4214 } 4215 } 4216 } 4217 4218 // Note: We do not call verify_sparse on entry, because inputs 4219 // can normalize to the base_memory via subsume_node or similar 4220 // mechanisms. This method repairs that damage. 4221 4222 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4223 4224 // Look at each slice. 4225 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4226 Node* old_in = in(i); 4227 // calculate the old memory value 4228 Node* old_mem = old_in; 4229 if (old_mem == empty_mem) old_mem = old_base; 4230 assert(old_mem == memory_at(i), ""); 4231 4232 // maybe update (reslice) the old memory value 4233 4234 // simplify stacked MergeMems 4235 Node* new_mem = old_mem; 4236 MergeMemNode* old_mmem; 4237 if (old_mem != NULL && old_mem->is_MergeMem()) 4238 old_mmem = old_mem->as_MergeMem(); 4239 else 4240 old_mmem = NULL; 4241 if (old_mmem == this) { 4242 // This can happen if loops break up and safepoints disappear. 4243 // A merge of BotPtr (default) with a RawPtr memory derived from a 4244 // safepoint can be rewritten to a merge of the same BotPtr with 4245 // the BotPtr phi coming into the loop. If that phi disappears 4246 // also, we can end up with a self-loop of the mergemem. 4247 // In general, if loops degenerate and memory effects disappear, 4248 // a mergemem can be left looking at itself. This simply means 4249 // that the mergemem's default should be used, since there is 4250 // no longer any apparent effect on this slice. 4251 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4252 // from start. Update the input to TOP. 4253 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4254 } 4255 else if (old_mmem != NULL) { 4256 new_mem = old_mmem->memory_at(i); 4257 } 4258 // else preceding memory was not a MergeMem 4259 4260 // replace equivalent phis (unfortunately, they do not GVN together) 4261 if (new_mem != NULL && new_mem != new_base && 4262 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4263 if (new_mem->is_Phi()) { 4264 PhiNode* phi_mem = new_mem->as_Phi(); 4265 for (uint i = 1; i < phi_len; i++) { 4266 if (phi_base->in(i) != phi_mem->in(i)) { 4267 phi_mem = NULL; 4268 break; 4269 } 4270 } 4271 if (phi_mem != NULL) { 4272 // equivalent phi nodes; revert to the def 4273 new_mem = new_base; 4274 } 4275 } 4276 } 4277 4278 // maybe store down a new value 4279 Node* new_in = new_mem; 4280 if (new_in == new_base) new_in = empty_mem; 4281 4282 if (new_in != old_in) { 4283 // Warning: Do not combine this "if" with the previous "if" 4284 // A memory slice might have be be rewritten even if it is semantically 4285 // unchanged, if the base_memory value has changed. 4286 set_req(i, new_in); 4287 progress = this; // Report progress 4288 } 4289 } 4290 4291 if (new_base != old_base) { 4292 set_req(Compile::AliasIdxBot, new_base); 4293 // Don't use set_base_memory(new_base), because we need to update du. 4294 assert(base_memory() == new_base, ""); 4295 progress = this; 4296 } 4297 4298 if( base_memory() == this ) { 4299 // a self cycle indicates this memory path is dead 4300 set_req(Compile::AliasIdxBot, empty_mem); 4301 } 4302 4303 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4304 // Recursion must occur after the self cycle check above 4305 if( base_memory()->is_MergeMem() ) { 4306 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4307 Node *m = phase->transform(new_mbase); // Rollup any cycles 4308 if( m != NULL && (m->is_top() || 4309 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 4310 // propagate rollup of dead cycle to self 4311 set_req(Compile::AliasIdxBot, empty_mem); 4312 } 4313 } 4314 4315 if( base_memory() == empty_mem ) { 4316 progress = this; 4317 // Cut inputs during Parse phase only. 4318 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4319 if( !can_reshape ) { 4320 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4321 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4322 } 4323 } 4324 } 4325 4326 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4327 // Check if PhiNode::Ideal's "Split phis through memory merges" 4328 // transform should be attempted. Look for this->phi->this cycle. 4329 uint merge_width = req(); 4330 if (merge_width > Compile::AliasIdxRaw) { 4331 PhiNode* phi = base_memory()->as_Phi(); 4332 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4333 if (phi->in(i) == this) { 4334 phase->is_IterGVN()->_worklist.push(phi); 4335 break; 4336 } 4337 } 4338 } 4339 } 4340 4341 assert(progress || verify_sparse(), "please, no dups of base"); 4342 return progress; 4343} 4344 4345//-------------------------set_base_memory------------------------------------- 4346void MergeMemNode::set_base_memory(Node *new_base) { 4347 Node* empty_mem = empty_memory(); 4348 set_req(Compile::AliasIdxBot, new_base); 4349 assert(memory_at(req()) == new_base, "must set default memory"); 4350 // Clear out other occurrences of new_base: 4351 if (new_base != empty_mem) { 4352 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4353 if (in(i) == new_base) set_req(i, empty_mem); 4354 } 4355 } 4356} 4357 4358//------------------------------out_RegMask------------------------------------ 4359const RegMask &MergeMemNode::out_RegMask() const { 4360 return RegMask::Empty; 4361} 4362 4363//------------------------------dump_spec-------------------------------------- 4364#ifndef PRODUCT 4365void MergeMemNode::dump_spec(outputStream *st) const { 4366 st->print(" {"); 4367 Node* base_mem = base_memory(); 4368 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4369 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem; 4370 if (mem == base_mem) { st->print(" -"); continue; } 4371 st->print( " N%d:", mem->_idx ); 4372 Compile::current()->get_adr_type(i)->dump_on(st); 4373 } 4374 st->print(" }"); 4375} 4376#endif // !PRODUCT 4377 4378 4379#ifdef ASSERT 4380static bool might_be_same(Node* a, Node* b) { 4381 if (a == b) return true; 4382 if (!(a->is_Phi() || b->is_Phi())) return false; 4383 // phis shift around during optimization 4384 return true; // pretty stupid... 4385} 4386 4387// verify a narrow slice (either incoming or outgoing) 4388static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4389 if (!VerifyAliases) return; // don't bother to verify unless requested 4390 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 4391 if (Node::in_dump()) return; // muzzle asserts when printing 4392 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4393 assert(n != NULL, ""); 4394 // Elide intervening MergeMem's 4395 while (n->is_MergeMem()) { 4396 n = n->as_MergeMem()->memory_at(alias_idx); 4397 } 4398 Compile* C = Compile::current(); 4399 const TypePtr* n_adr_type = n->adr_type(); 4400 if (n == m->empty_memory()) { 4401 // Implicit copy of base_memory() 4402 } else if (n_adr_type != TypePtr::BOTTOM) { 4403 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4404 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4405 } else { 4406 // A few places like make_runtime_call "know" that VM calls are narrow, 4407 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4408 bool expected_wide_mem = false; 4409 if (n == m->base_memory()) { 4410 expected_wide_mem = true; 4411 } else if (alias_idx == Compile::AliasIdxRaw || 4412 n == m->memory_at(Compile::AliasIdxRaw)) { 4413 expected_wide_mem = true; 4414 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4415 // memory can "leak through" calls on channels that 4416 // are write-once. Allow this also. 4417 expected_wide_mem = true; 4418 } 4419 assert(expected_wide_mem, "expected narrow slice replacement"); 4420 } 4421} 4422#else // !ASSERT 4423#define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4424#endif 4425 4426 4427//-----------------------------memory_at--------------------------------------- 4428Node* MergeMemNode::memory_at(uint alias_idx) const { 4429 assert(alias_idx >= Compile::AliasIdxRaw || 4430 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4431 "must avoid base_memory and AliasIdxTop"); 4432 4433 // Otherwise, it is a narrow slice. 4434 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4435 Compile *C = Compile::current(); 4436 if (is_empty_memory(n)) { 4437 // the array is sparse; empty slots are the "top" node 4438 n = base_memory(); 4439 assert(Node::in_dump() 4440 || n == NULL || n->bottom_type() == Type::TOP 4441 || n->adr_type() == NULL // address is TOP 4442 || n->adr_type() == TypePtr::BOTTOM 4443 || n->adr_type() == TypeRawPtr::BOTTOM 4444 || Compile::current()->AliasLevel() == 0, 4445 "must be a wide memory"); 4446 // AliasLevel == 0 if we are organizing the memory states manually. 4447 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4448 } else { 4449 // make sure the stored slice is sane 4450 #ifdef ASSERT 4451 if (VMError::is_error_reported() || Node::in_dump()) { 4452 } else if (might_be_same(n, base_memory())) { 4453 // Give it a pass: It is a mostly harmless repetition of the base. 4454 // This can arise normally from node subsumption during optimization. 4455 } else { 4456 verify_memory_slice(this, alias_idx, n); 4457 } 4458 #endif 4459 } 4460 return n; 4461} 4462 4463//---------------------------set_memory_at------------------------------------- 4464void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4465 verify_memory_slice(this, alias_idx, n); 4466 Node* empty_mem = empty_memory(); 4467 if (n == base_memory()) n = empty_mem; // collapse default 4468 uint need_req = alias_idx+1; 4469 if (req() < need_req) { 4470 if (n == empty_mem) return; // already the default, so do not grow me 4471 // grow the sparse array 4472 do { 4473 add_req(empty_mem); 4474 } while (req() < need_req); 4475 } 4476 set_req( alias_idx, n ); 4477} 4478 4479 4480 4481//--------------------------iteration_setup------------------------------------ 4482void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4483 if (other != NULL) { 4484 grow_to_match(other); 4485 // invariant: the finite support of mm2 is within mm->req() 4486 #ifdef ASSERT 4487 for (uint i = req(); i < other->req(); i++) { 4488 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4489 } 4490 #endif 4491 } 4492 // Replace spurious copies of base_memory by top. 4493 Node* base_mem = base_memory(); 4494 if (base_mem != NULL && !base_mem->is_top()) { 4495 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4496 if (in(i) == base_mem) 4497 set_req(i, empty_memory()); 4498 } 4499 } 4500} 4501 4502//---------------------------grow_to_match------------------------------------- 4503void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4504 Node* empty_mem = empty_memory(); 4505 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4506 // look for the finite support of the other memory 4507 for (uint i = other->req(); --i >= req(); ) { 4508 if (other->in(i) != empty_mem) { 4509 uint new_len = i+1; 4510 while (req() < new_len) add_req(empty_mem); 4511 break; 4512 } 4513 } 4514} 4515 4516//---------------------------verify_sparse------------------------------------- 4517#ifndef PRODUCT 4518bool MergeMemNode::verify_sparse() const { 4519 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4520 Node* base_mem = base_memory(); 4521 // The following can happen in degenerate cases, since empty==top. 4522 if (is_empty_memory(base_mem)) return true; 4523 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4524 assert(in(i) != NULL, "sane slice"); 4525 if (in(i) == base_mem) return false; // should have been the sentinel value! 4526 } 4527 return true; 4528} 4529 4530bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4531 Node* n; 4532 n = mm->in(idx); 4533 if (mem == n) return true; // might be empty_memory() 4534 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4535 if (mem == n) return true; 4536 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4537 if (mem == n) return true; 4538 if (n == NULL) break; 4539 } 4540 return false; 4541} 4542#endif // !PRODUCT 4543