memnode.cpp revision 13249:a2753984d2c1
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/align.hpp" 46#include "utilities/copy.hpp" 47#include "utilities/vmError.hpp" 48 49// Portions of code courtesy of Clifford Click 50 51// Optimization - Graph Style 52 53static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 54 55//============================================================================= 56uint MemNode::size_of() const { return sizeof(*this); } 57 58const TypePtr *MemNode::adr_type() const { 59 Node* adr = in(Address); 60 if (adr == NULL) return NULL; // node is dead 61 const TypePtr* cross_check = NULL; 62 DEBUG_ONLY(cross_check = _adr_type); 63 return calculate_adr_type(adr->bottom_type(), cross_check); 64} 65 66bool MemNode::check_if_adr_maybe_raw(Node* adr) { 67 if (adr != NULL) { 68 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) { 69 return true; 70 } 71 } 72 return false; 73} 74 75#ifndef PRODUCT 76void MemNode::dump_spec(outputStream *st) const { 77 if (in(Address) == NULL) return; // node is dead 78#ifndef ASSERT 79 // fake the missing field 80 const TypePtr* _adr_type = NULL; 81 if (in(Address) != NULL) 82 _adr_type = in(Address)->bottom_type()->isa_ptr(); 83#endif 84 dump_adr_type(this, _adr_type, st); 85 86 Compile* C = Compile::current(); 87 if (C->alias_type(_adr_type)->is_volatile()) { 88 st->print(" Volatile!"); 89 } 90 if (_unaligned_access) { 91 st->print(" unaligned"); 92 } 93 if (_mismatched_access) { 94 st->print(" mismatched"); 95 } 96} 97 98void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 99 st->print(" @"); 100 if (adr_type == NULL) { 101 st->print("NULL"); 102 } else { 103 adr_type->dump_on(st); 104 Compile* C = Compile::current(); 105 Compile::AliasType* atp = NULL; 106 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 107 if (atp == NULL) 108 st->print(", idx=?\?;"); 109 else if (atp->index() == Compile::AliasIdxBot) 110 st->print(", idx=Bot;"); 111 else if (atp->index() == Compile::AliasIdxTop) 112 st->print(", idx=Top;"); 113 else if (atp->index() == Compile::AliasIdxRaw) 114 st->print(", idx=Raw;"); 115 else { 116 ciField* field = atp->field(); 117 if (field) { 118 st->print(", name="); 119 field->print_name_on(st); 120 } 121 st->print(", idx=%d;", atp->index()); 122 } 123 } 124} 125 126extern void print_alias_types(); 127 128#endif 129 130Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) { 131 assert((t_oop != NULL), "sanity"); 132 bool is_instance = t_oop->is_known_instance_field(); 133 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() && 134 (load != NULL) && load->is_Load() && 135 (phase->is_IterGVN() != NULL); 136 if (!(is_instance || is_boxed_value_load)) 137 return mchain; // don't try to optimize non-instance types 138 uint instance_id = t_oop->instance_id(); 139 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory); 140 Node *prev = NULL; 141 Node *result = mchain; 142 while (prev != result) { 143 prev = result; 144 if (result == start_mem) 145 break; // hit one of our sentinels 146 // skip over a call which does not affect this memory slice 147 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 148 Node *proj_in = result->in(0); 149 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 150 break; // hit one of our sentinels 151 } else if (proj_in->is_Call()) { 152 // ArrayCopyNodes processed here as well 153 CallNode *call = proj_in->as_Call(); 154 if (!call->may_modify(t_oop, phase)) { // returns false for instances 155 result = call->in(TypeFunc::Memory); 156 } 157 } else if (proj_in->is_Initialize()) { 158 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 159 // Stop if this is the initialization for the object instance which 160 // contains this memory slice, otherwise skip over it. 161 if ((alloc == NULL) || (alloc->_idx == instance_id)) { 162 break; 163 } 164 if (is_instance) { 165 result = proj_in->in(TypeFunc::Memory); 166 } else if (is_boxed_value_load) { 167 Node* klass = alloc->in(AllocateNode::KlassNode); 168 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 169 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) { 170 result = proj_in->in(TypeFunc::Memory); // not related allocation 171 } 172 } 173 } else if (proj_in->is_MemBar()) { 174 ArrayCopyNode* ac = NULL; 175 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) { 176 break; 177 } 178 result = proj_in->in(TypeFunc::Memory); 179 } else { 180 assert(false, "unexpected projection"); 181 } 182 } else if (result->is_ClearArray()) { 183 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) { 184 // Can not bypass initialization of the instance 185 // we are looking for. 186 break; 187 } 188 // Otherwise skip it (the call updated 'result' value). 189 } else if (result->is_MergeMem()) { 190 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty); 191 } 192 } 193 return result; 194} 195 196Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 197 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 198 if (t_oop == NULL) 199 return mchain; // don't try to optimize non-oop types 200 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 201 bool is_instance = t_oop->is_known_instance_field(); 202 PhaseIterGVN *igvn = phase->is_IterGVN(); 203 if (is_instance && igvn != NULL && result->is_Phi()) { 204 PhiNode *mphi = result->as_Phi(); 205 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 206 const TypePtr *t = mphi->adr_type(); 207 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 208 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 209 t->is_oopptr()->cast_to_exactness(true) 210 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 211 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) { 212 // clone the Phi with our address type 213 result = mphi->split_out_instance(t_adr, igvn); 214 } else { 215 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 216 } 217 } 218 return result; 219} 220 221static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 222 uint alias_idx = phase->C->get_alias_index(tp); 223 Node *mem = mmem; 224#ifdef ASSERT 225 { 226 // Check that current type is consistent with the alias index used during graph construction 227 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 228 bool consistent = adr_check == NULL || adr_check->empty() || 229 phase->C->must_alias(adr_check, alias_idx ); 230 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 231 if( !consistent && adr_check != NULL && !adr_check->empty() && 232 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 233 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 234 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 235 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 236 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 237 // don't assert if it is dead code. 238 consistent = true; 239 } 240 if( !consistent ) { 241 st->print("alias_idx==%d, adr_check==", alias_idx); 242 if( adr_check == NULL ) { 243 st->print("NULL"); 244 } else { 245 adr_check->dump(); 246 } 247 st->cr(); 248 print_alias_types(); 249 assert(consistent, "adr_check must match alias idx"); 250 } 251 } 252#endif 253 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 254 // means an array I have not precisely typed yet. Do not do any 255 // alias stuff with it any time soon. 256 const TypeOopPtr *toop = tp->isa_oopptr(); 257 if( tp->base() != Type::AnyPtr && 258 !(toop && 259 toop->klass() != NULL && 260 toop->klass()->is_java_lang_Object() && 261 toop->offset() == Type::OffsetBot) ) { 262 // compress paths and change unreachable cycles to TOP 263 // If not, we can update the input infinitely along a MergeMem cycle 264 // Equivalent code in PhiNode::Ideal 265 Node* m = phase->transform(mmem); 266 // If transformed to a MergeMem, get the desired slice 267 // Otherwise the returned node represents memory for every slice 268 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 269 // Update input if it is progress over what we have now 270 } 271 return mem; 272} 273 274//--------------------------Ideal_common--------------------------------------- 275// Look for degenerate control and memory inputs. Bypass MergeMem inputs. 276// Unhook non-raw memories from complete (macro-expanded) initializations. 277Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 278 // If our control input is a dead region, kill all below the region 279 Node *ctl = in(MemNode::Control); 280 if (ctl && remove_dead_region(phase, can_reshape)) 281 return this; 282 ctl = in(MemNode::Control); 283 // Don't bother trying to transform a dead node 284 if (ctl && ctl->is_top()) return NodeSentinel; 285 286 PhaseIterGVN *igvn = phase->is_IterGVN(); 287 // Wait if control on the worklist. 288 if (ctl && can_reshape && igvn != NULL) { 289 Node* bol = NULL; 290 Node* cmp = NULL; 291 if (ctl->in(0)->is_If()) { 292 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 293 bol = ctl->in(0)->in(1); 294 if (bol->is_Bool()) 295 cmp = ctl->in(0)->in(1)->in(1); 296 } 297 if (igvn->_worklist.member(ctl) || 298 (bol != NULL && igvn->_worklist.member(bol)) || 299 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 300 // This control path may be dead. 301 // Delay this memory node transformation until the control is processed. 302 phase->is_IterGVN()->_worklist.push(this); 303 return NodeSentinel; // caller will return NULL 304 } 305 } 306 // Ignore if memory is dead, or self-loop 307 Node *mem = in(MemNode::Memory); 308 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL 309 assert(mem != this, "dead loop in MemNode::Ideal"); 310 311 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 312 // This memory slice may be dead. 313 // Delay this mem node transformation until the memory is processed. 314 phase->is_IterGVN()->_worklist.push(this); 315 return NodeSentinel; // caller will return NULL 316 } 317 318 Node *address = in(MemNode::Address); 319 const Type *t_adr = phase->type(address); 320 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL 321 322 if (can_reshape && igvn != NULL && 323 (igvn->_worklist.member(address) || 324 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) { 325 // The address's base and type may change when the address is processed. 326 // Delay this mem node transformation until the address is processed. 327 phase->is_IterGVN()->_worklist.push(this); 328 return NodeSentinel; // caller will return NULL 329 } 330 331 // Do NOT remove or optimize the next lines: ensure a new alias index 332 // is allocated for an oop pointer type before Escape Analysis. 333 // Note: C++ will not remove it since the call has side effect. 334 if (t_adr->isa_oopptr()) { 335 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 336 } 337 338 Node* base = NULL; 339 if (address->is_AddP()) { 340 base = address->in(AddPNode::Base); 341 } 342 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 343 !t_adr->isa_rawptr()) { 344 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 345 // Skip this node optimization if its address has TOP base. 346 return NodeSentinel; // caller will return NULL 347 } 348 349 // Avoid independent memory operations 350 Node* old_mem = mem; 351 352 // The code which unhooks non-raw memories from complete (macro-expanded) 353 // initializations was removed. After macro-expansion all stores catched 354 // by Initialize node became raw stores and there is no information 355 // which memory slices they modify. So it is unsafe to move any memory 356 // operation above these stores. Also in most cases hooked non-raw memories 357 // were already unhooked by using information from detect_ptr_independence() 358 // and find_previous_store(). 359 360 if (mem->is_MergeMem()) { 361 MergeMemNode* mmem = mem->as_MergeMem(); 362 const TypePtr *tp = t_adr->is_ptr(); 363 364 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 365 } 366 367 if (mem != old_mem) { 368 set_req(MemNode::Memory, mem); 369 if (can_reshape && old_mem->outcnt() == 0) { 370 igvn->_worklist.push(old_mem); 371 } 372 if (phase->type( mem ) == Type::TOP) return NodeSentinel; 373 return this; 374 } 375 376 // let the subclass continue analyzing... 377 return NULL; 378} 379 380// Helper function for proving some simple control dominations. 381// Attempt to prove that all control inputs of 'dom' dominate 'sub'. 382// Already assumes that 'dom' is available at 'sub', and that 'sub' 383// is not a constant (dominated by the method's StartNode). 384// Used by MemNode::find_previous_store to prove that the 385// control input of a memory operation predates (dominates) 386// an allocation it wants to look past. 387bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 388 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 389 return false; // Conservative answer for dead code 390 391 // Check 'dom'. Skip Proj and CatchProj nodes. 392 dom = dom->find_exact_control(dom); 393 if (dom == NULL || dom->is_top()) 394 return false; // Conservative answer for dead code 395 396 if (dom == sub) { 397 // For the case when, for example, 'sub' is Initialize and the original 398 // 'dom' is Proj node of the 'sub'. 399 return false; 400 } 401 402 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 403 return true; 404 405 // 'dom' dominates 'sub' if its control edge and control edges 406 // of all its inputs dominate or equal to sub's control edge. 407 408 // Currently 'sub' is either Allocate, Initialize or Start nodes. 409 // Or Region for the check in LoadNode::Ideal(); 410 // 'sub' should have sub->in(0) != NULL. 411 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 412 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 413 414 // Get control edge of 'sub'. 415 Node* orig_sub = sub; 416 sub = sub->find_exact_control(sub->in(0)); 417 if (sub == NULL || sub->is_top()) 418 return false; // Conservative answer for dead code 419 420 assert(sub->is_CFG(), "expecting control"); 421 422 if (sub == dom) 423 return true; 424 425 if (sub->is_Start() || sub->is_Root()) 426 return false; 427 428 { 429 // Check all control edges of 'dom'. 430 431 ResourceMark rm; 432 Arena* arena = Thread::current()->resource_area(); 433 Node_List nlist(arena); 434 Unique_Node_List dom_list(arena); 435 436 dom_list.push(dom); 437 bool only_dominating_controls = false; 438 439 for (uint next = 0; next < dom_list.size(); next++) { 440 Node* n = dom_list.at(next); 441 if (n == orig_sub) 442 return false; // One of dom's inputs dominated by sub. 443 if (!n->is_CFG() && n->pinned()) { 444 // Check only own control edge for pinned non-control nodes. 445 n = n->find_exact_control(n->in(0)); 446 if (n == NULL || n->is_top()) 447 return false; // Conservative answer for dead code 448 assert(n->is_CFG(), "expecting control"); 449 dom_list.push(n); 450 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 451 only_dominating_controls = true; 452 } else if (n->is_CFG()) { 453 if (n->dominates(sub, nlist)) 454 only_dominating_controls = true; 455 else 456 return false; 457 } else { 458 // First, own control edge. 459 Node* m = n->find_exact_control(n->in(0)); 460 if (m != NULL) { 461 if (m->is_top()) 462 return false; // Conservative answer for dead code 463 dom_list.push(m); 464 } 465 // Now, the rest of edges. 466 uint cnt = n->req(); 467 for (uint i = 1; i < cnt; i++) { 468 m = n->find_exact_control(n->in(i)); 469 if (m == NULL || m->is_top()) 470 continue; 471 dom_list.push(m); 472 } 473 } 474 } 475 return only_dominating_controls; 476 } 477} 478 479//---------------------detect_ptr_independence--------------------------------- 480// Used by MemNode::find_previous_store to prove that two base 481// pointers are never equal. 482// The pointers are accompanied by their associated allocations, 483// if any, which have been previously discovered by the caller. 484bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 485 Node* p2, AllocateNode* a2, 486 PhaseTransform* phase) { 487 // Attempt to prove that these two pointers cannot be aliased. 488 // They may both manifestly be allocations, and they should differ. 489 // Or, if they are not both allocations, they can be distinct constants. 490 // Otherwise, one is an allocation and the other a pre-existing value. 491 if (a1 == NULL && a2 == NULL) { // neither an allocation 492 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 493 } else if (a1 != NULL && a2 != NULL) { // both allocations 494 return (a1 != a2); 495 } else if (a1 != NULL) { // one allocation a1 496 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 497 return all_controls_dominate(p2, a1); 498 } else { //(a2 != NULL) // one allocation a2 499 return all_controls_dominate(p1, a2); 500 } 501 return false; 502} 503 504 505// Find an arraycopy that must have set (can_see_stored_value=true) or 506// could have set (can_see_stored_value=false) the value for this load 507Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 508 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 509 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 510 Node* mb = mem->in(0); 511 if (mb->in(0) != NULL && mb->in(0)->is_Proj() && 512 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) { 513 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy(); 514 if (ac->is_clonebasic()) { 515 intptr_t offset; 516 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset); 517 assert(alloc != NULL && (!ReduceBulkZeroing || alloc->initialization()->is_complete_with_arraycopy()), "broken allocation"); 518 if (alloc == ld_alloc) { 519 return ac; 520 } 521 } 522 } 523 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) { 524 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy(); 525 526 if (ac->is_arraycopy_validated() || 527 ac->is_copyof_validated() || 528 ac->is_copyofrange_validated()) { 529 Node* ld_addp = in(MemNode::Address); 530 if (ld_addp->is_AddP()) { 531 Node* ld_base = ld_addp->in(AddPNode::Address); 532 Node* ld_offs = ld_addp->in(AddPNode::Offset); 533 534 Node* dest = ac->in(ArrayCopyNode::Dest); 535 536 if (dest == ld_base) { 537 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 538 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) { 539 return ac; 540 } 541 if (!can_see_stored_value) { 542 mem = ac->in(TypeFunc::Memory); 543 } 544 } 545 } 546 } 547 } 548 return NULL; 549} 550 551// The logic for reordering loads and stores uses four steps: 552// (a) Walk carefully past stores and initializations which we 553// can prove are independent of this load. 554// (b) Observe that the next memory state makes an exact match 555// with self (load or store), and locate the relevant store. 556// (c) Ensure that, if we were to wire self directly to the store, 557// the optimizer would fold it up somehow. 558// (d) Do the rewiring, and return, depending on some other part of 559// the optimizer to fold up the load. 560// This routine handles steps (a) and (b). Steps (c) and (d) are 561// specific to loads and stores, so they are handled by the callers. 562// (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 563// 564Node* MemNode::find_previous_store(PhaseTransform* phase) { 565 Node* ctrl = in(MemNode::Control); 566 Node* adr = in(MemNode::Address); 567 intptr_t offset = 0; 568 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 569 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 570 571 if (offset == Type::OffsetBot) 572 return NULL; // cannot unalias unless there are precise offsets 573 574 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr); 575 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 576 577 intptr_t size_in_bytes = memory_size(); 578 579 Node* mem = in(MemNode::Memory); // start searching here... 580 581 int cnt = 50; // Cycle limiter 582 for (;;) { // While we can dance past unrelated stores... 583 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 584 585 Node* prev = mem; 586 if (mem->is_Store()) { 587 Node* st_adr = mem->in(MemNode::Address); 588 intptr_t st_offset = 0; 589 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 590 if (st_base == NULL) 591 break; // inscrutable pointer 592 593 // For raw accesses it's not enough to prove that constant offsets don't intersect. 594 // We need the bases to be the equal in order for the offset check to make sense. 595 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) { 596 break; 597 } 598 599 if (st_offset != offset && st_offset != Type::OffsetBot) { 600 const int MAX_STORE = BytesPerLong; 601 if (st_offset >= offset + size_in_bytes || 602 st_offset <= offset - MAX_STORE || 603 st_offset <= offset - mem->as_Store()->memory_size()) { 604 // Success: The offsets are provably independent. 605 // (You may ask, why not just test st_offset != offset and be done? 606 // The answer is that stores of different sizes can co-exist 607 // in the same sequence of RawMem effects. We sometimes initialize 608 // a whole 'tile' of array elements with a single jint or jlong.) 609 mem = mem->in(MemNode::Memory); 610 continue; // (a) advance through independent store memory 611 } 612 } 613 if (st_base != base && 614 detect_ptr_independence(base, alloc, 615 st_base, 616 AllocateNode::Ideal_allocation(st_base, phase), 617 phase)) { 618 // Success: The bases are provably independent. 619 mem = mem->in(MemNode::Memory); 620 continue; // (a) advance through independent store memory 621 } 622 623 // (b) At this point, if the bases or offsets do not agree, we lose, 624 // since we have not managed to prove 'this' and 'mem' independent. 625 if (st_base == base && st_offset == offset) { 626 return mem; // let caller handle steps (c), (d) 627 } 628 629 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 630 InitializeNode* st_init = mem->in(0)->as_Initialize(); 631 AllocateNode* st_alloc = st_init->allocation(); 632 if (st_alloc == NULL) 633 break; // something degenerated 634 bool known_identical = false; 635 bool known_independent = false; 636 if (alloc == st_alloc) 637 known_identical = true; 638 else if (alloc != NULL) 639 known_independent = true; 640 else if (all_controls_dominate(this, st_alloc)) 641 known_independent = true; 642 643 if (known_independent) { 644 // The bases are provably independent: Either they are 645 // manifestly distinct allocations, or else the control 646 // of this load dominates the store's allocation. 647 int alias_idx = phase->C->get_alias_index(adr_type()); 648 if (alias_idx == Compile::AliasIdxRaw) { 649 mem = st_alloc->in(TypeFunc::Memory); 650 } else { 651 mem = st_init->memory(alias_idx); 652 } 653 continue; // (a) advance through independent store memory 654 } 655 656 // (b) at this point, if we are not looking at a store initializing 657 // the same allocation we are loading from, we lose. 658 if (known_identical) { 659 // From caller, can_see_stored_value will consult find_captured_store. 660 return mem; // let caller handle steps (c), (d) 661 } 662 663 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) { 664 if (prev != mem) { 665 // Found an arraycopy but it doesn't affect that load 666 continue; 667 } 668 // Found an arraycopy that may affect that load 669 return mem; 670 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 671 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 672 if (mem->is_Proj() && mem->in(0)->is_Call()) { 673 // ArrayCopyNodes processed here as well. 674 CallNode *call = mem->in(0)->as_Call(); 675 if (!call->may_modify(addr_t, phase)) { 676 mem = call->in(TypeFunc::Memory); 677 continue; // (a) advance through independent call memory 678 } 679 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 680 ArrayCopyNode* ac = NULL; 681 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) { 682 break; 683 } 684 mem = mem->in(0)->in(TypeFunc::Memory); 685 continue; // (a) advance through independent MemBar memory 686 } else if (mem->is_ClearArray()) { 687 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 688 // (the call updated 'mem' value) 689 continue; // (a) advance through independent allocation memory 690 } else { 691 // Can not bypass initialization of the instance 692 // we are looking for. 693 return mem; 694 } 695 } else if (mem->is_MergeMem()) { 696 int alias_idx = phase->C->get_alias_index(adr_type()); 697 mem = mem->as_MergeMem()->memory_at(alias_idx); 698 continue; // (a) advance through independent MergeMem memory 699 } 700 } 701 702 // Unless there is an explicit 'continue', we must bail out here, 703 // because 'mem' is an inscrutable memory state (e.g., a call). 704 break; 705 } 706 707 return NULL; // bail out 708} 709 710//----------------------calculate_adr_type------------------------------------- 711// Helper function. Notices when the given type of address hits top or bottom. 712// Also, asserts a cross-check of the type against the expected address type. 713const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 714 if (t == Type::TOP) return NULL; // does not touch memory any more? 715 #ifdef PRODUCT 716 cross_check = NULL; 717 #else 718 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL; 719 #endif 720 const TypePtr* tp = t->isa_ptr(); 721 if (tp == NULL) { 722 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 723 return TypePtr::BOTTOM; // touches lots of memory 724 } else { 725 #ifdef ASSERT 726 // %%%% [phh] We don't check the alias index if cross_check is 727 // TypeRawPtr::BOTTOM. Needs to be investigated. 728 if (cross_check != NULL && 729 cross_check != TypePtr::BOTTOM && 730 cross_check != TypeRawPtr::BOTTOM) { 731 // Recheck the alias index, to see if it has changed (due to a bug). 732 Compile* C = Compile::current(); 733 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 734 "must stay in the original alias category"); 735 // The type of the address must be contained in the adr_type, 736 // disregarding "null"-ness. 737 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 738 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 739 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 740 "real address must not escape from expected memory type"); 741 } 742 #endif 743 return tp; 744 } 745} 746 747//============================================================================= 748// Should LoadNode::Ideal() attempt to remove control edges? 749bool LoadNode::can_remove_control() const { 750 return true; 751} 752uint LoadNode::size_of() const { return sizeof(*this); } 753uint LoadNode::cmp( const Node &n ) const 754{ return !Type::cmp( _type, ((LoadNode&)n)._type ); } 755const Type *LoadNode::bottom_type() const { return _type; } 756uint LoadNode::ideal_reg() const { 757 return _type->ideal_reg(); 758} 759 760#ifndef PRODUCT 761void LoadNode::dump_spec(outputStream *st) const { 762 MemNode::dump_spec(st); 763 if( !Verbose && !WizardMode ) { 764 // standard dump does this in Verbose and WizardMode 765 st->print(" #"); _type->dump_on(st); 766 } 767 if (!depends_only_on_test()) { 768 st->print(" (does not depend only on test)"); 769 } 770} 771#endif 772 773#ifdef ASSERT 774//----------------------------is_immutable_value------------------------------- 775// Helper function to allow a raw load without control edge for some cases 776bool LoadNode::is_immutable_value(Node* adr) { 777 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 778 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 779 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 780 in_bytes(JavaThread::osthread_offset()))); 781} 782#endif 783 784//----------------------------LoadNode::make----------------------------------- 785// Polymorphic factory method: 786Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, 787 ControlDependency control_dependency, bool unaligned, bool mismatched) { 788 Compile* C = gvn.C; 789 790 // sanity check the alias category against the created node type 791 assert(!(adr_type->isa_oopptr() && 792 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 793 "use LoadKlassNode instead"); 794 assert(!(adr_type->isa_aryptr() && 795 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 796 "use LoadRangeNode instead"); 797 // Check control edge of raw loads 798 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 799 // oop will be recorded in oop map if load crosses safepoint 800 rt->isa_oopptr() || is_immutable_value(adr), 801 "raw memory operations should have control edge"); 802 LoadNode* load = NULL; 803 switch (bt) { 804 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 805 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 806 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 807 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 808 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break; 809 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break; 810 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 811 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break; 812 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break; 813 case T_OBJECT: 814#ifdef _LP64 815 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 816 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency); 817 } else 818#endif 819 { 820 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 821 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 822 } 823 break; 824 } 825 assert(load != NULL, "LoadNode should have been created"); 826 if (unaligned) { 827 load->set_unaligned_access(); 828 } 829 if (mismatched) { 830 load->set_mismatched_access(); 831 } 832 if (load->Opcode() == Op_LoadN) { 833 Node* ld = gvn.transform(load); 834 return new DecodeNNode(ld, ld->bottom_type()->make_ptr()); 835 } 836 837 return load; 838} 839 840LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 841 ControlDependency control_dependency, bool unaligned, bool mismatched) { 842 bool require_atomic = true; 843 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic); 844 if (unaligned) { 845 load->set_unaligned_access(); 846 } 847 if (mismatched) { 848 load->set_mismatched_access(); 849 } 850 return load; 851} 852 853LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, 854 ControlDependency control_dependency, bool unaligned, bool mismatched) { 855 bool require_atomic = true; 856 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic); 857 if (unaligned) { 858 load->set_unaligned_access(); 859 } 860 if (mismatched) { 861 load->set_mismatched_access(); 862 } 863 return load; 864} 865 866 867 868//------------------------------hash------------------------------------------- 869uint LoadNode::hash() const { 870 // unroll addition of interesting fields 871 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 872} 873 874static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 875 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 876 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 877 bool is_stable_ary = FoldStableValues && 878 (tp != NULL) && (tp->isa_aryptr() != NULL) && 879 tp->isa_aryptr()->is_stable(); 880 881 return (eliminate_boxing && non_volatile) || is_stable_ary; 882 } 883 884 return false; 885} 886 887// Is the value loaded previously stored by an arraycopy? If so return 888// a load node that reads from the source array so we may be able to 889// optimize out the ArrayCopy node later. 890Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const { 891 Node* ld_adr = in(MemNode::Address); 892 intptr_t ld_off = 0; 893 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 894 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 895 if (ac != NULL) { 896 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 897 898 Node* ld = clone(); 899 if (ac->as_ArrayCopy()->is_clonebasic()) { 900 assert(ld_alloc != NULL, "need an alloc"); 901 Node* addp = in(MemNode::Address)->clone(); 902 assert(addp->is_AddP(), "address must be addp"); 903 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern"); 904 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern"); 905 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base)); 906 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address)); 907 ld->set_req(MemNode::Address, phase->transform(addp)); 908 if (in(0) != NULL) { 909 assert(ld_alloc->in(0) != NULL, "alloc must have control"); 910 ld->set_req(0, ld_alloc->in(0)); 911 } 912 } else { 913 Node* src = ac->in(ArrayCopyNode::Src); 914 Node* addp = in(MemNode::Address)->clone(); 915 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 916 addp->set_req(AddPNode::Base, src); 917 addp->set_req(AddPNode::Address, src); 918 919 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 920 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 921 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 922 uint shift = exact_log2(type2aelembytes(ary_elem)); 923 924 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 925#ifdef _LP64 926 diff = phase->transform(new ConvI2LNode(diff)); 927#endif 928 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 929 930 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 931 addp->set_req(AddPNode::Offset, offset); 932 ld->set_req(MemNode::Address, phase->transform(addp)); 933 934 const TypeX *ld_offs_t = phase->type(offset)->isa_intptr_t(); 935 936 if (!ac->as_ArrayCopy()->can_replace_dest_load_with_src_load(ld_offs_t->_lo, ld_offs_t->_hi, phase)) { 937 return NULL; 938 } 939 940 if (in(0) != NULL) { 941 assert(ac->in(0) != NULL, "alloc must have control"); 942 ld->set_req(0, ac->in(0)); 943 } 944 } 945 // load depends on the tests that validate the arraycopy 946 ld->as_Load()->_control_dependency = Pinned; 947 return ld; 948 } 949 return NULL; 950} 951 952 953//---------------------------can_see_stored_value------------------------------ 954// This routine exists to make sure this set of tests is done the same 955// everywhere. We need to make a coordinated change: first LoadNode::Ideal 956// will change the graph shape in a way which makes memory alive twice at the 957// same time (uses the Oracle model of aliasing), then some 958// LoadXNode::Identity will fold things back to the equivalence-class model 959// of aliasing. 960Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 961 Node* ld_adr = in(MemNode::Address); 962 intptr_t ld_off = 0; 963 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 964 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 965 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 966 // This is more general than load from boxing objects. 967 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 968 uint alias_idx = atp->index(); 969 bool final = !atp->is_rewritable(); 970 Node* result = NULL; 971 Node* current = st; 972 // Skip through chains of MemBarNodes checking the MergeMems for 973 // new states for the slice of this load. Stop once any other 974 // kind of node is encountered. Loads from final memory can skip 975 // through any kind of MemBar but normal loads shouldn't skip 976 // through MemBarAcquire since the could allow them to move out of 977 // a synchronized region. 978 while (current->is_Proj()) { 979 int opc = current->in(0)->Opcode(); 980 if ((final && (opc == Op_MemBarAcquire || 981 opc == Op_MemBarAcquireLock || 982 opc == Op_LoadFence)) || 983 opc == Op_MemBarRelease || 984 opc == Op_StoreFence || 985 opc == Op_MemBarReleaseLock || 986 opc == Op_MemBarStoreStore || 987 opc == Op_MemBarCPUOrder) { 988 Node* mem = current->in(0)->in(TypeFunc::Memory); 989 if (mem->is_MergeMem()) { 990 MergeMemNode* merge = mem->as_MergeMem(); 991 Node* new_st = merge->memory_at(alias_idx); 992 if (new_st == merge->base_memory()) { 993 // Keep searching 994 current = new_st; 995 continue; 996 } 997 // Save the new memory state for the slice and fall through 998 // to exit. 999 result = new_st; 1000 } 1001 } 1002 break; 1003 } 1004 if (result != NULL) { 1005 st = result; 1006 } 1007 } 1008 1009 // Loop around twice in the case Load -> Initialize -> Store. 1010 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1011 for (int trip = 0; trip <= 1; trip++) { 1012 1013 if (st->is_Store()) { 1014 Node* st_adr = st->in(MemNode::Address); 1015 if (!phase->eqv(st_adr, ld_adr)) { 1016 // Try harder before giving up... Match raw and non-raw pointers. 1017 intptr_t st_off = 0; 1018 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 1019 if (alloc == NULL) return NULL; 1020 if (alloc != ld_alloc) return NULL; 1021 if (ld_off != st_off) return NULL; 1022 // At this point we have proven something like this setup: 1023 // A = Allocate(...) 1024 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 1025 // S = StoreQ(, AddP(, A.Parm , #Off), V) 1026 // (Actually, we haven't yet proven the Q's are the same.) 1027 // In other words, we are loading from a casted version of 1028 // the same pointer-and-offset that we stored to. 1029 // Thus, we are able to replace L by V. 1030 } 1031 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1032 if (store_Opcode() != st->Opcode()) 1033 return NULL; 1034 return st->in(MemNode::ValueIn); 1035 } 1036 1037 // A load from a freshly-created object always returns zero. 1038 // (This can happen after LoadNode::Ideal resets the load's memory input 1039 // to find_captured_store, which returned InitializeNode::zero_memory.) 1040 if (st->is_Proj() && st->in(0)->is_Allocate() && 1041 (st->in(0) == ld_alloc) && 1042 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1043 // return a zero value for the load's basic type 1044 // (This is one of the few places where a generic PhaseTransform 1045 // can create new nodes. Think of it as lazily manifesting 1046 // virtually pre-existing constants.) 1047 return phase->zerocon(memory_type()); 1048 } 1049 1050 // A load from an initialization barrier can match a captured store. 1051 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1052 InitializeNode* init = st->in(0)->as_Initialize(); 1053 AllocateNode* alloc = init->allocation(); 1054 if ((alloc != NULL) && (alloc == ld_alloc)) { 1055 // examine a captured store value 1056 st = init->find_captured_store(ld_off, memory_size(), phase); 1057 if (st != NULL) { 1058 continue; // take one more trip around 1059 } 1060 } 1061 } 1062 1063 // Load boxed value from result of valueOf() call is input parameter. 1064 if (this->is_Load() && ld_adr->is_AddP() && 1065 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1066 intptr_t ignore = 0; 1067 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1068 if (base != NULL && base->is_Proj() && 1069 base->as_Proj()->_con == TypeFunc::Parms && 1070 base->in(0)->is_CallStaticJava() && 1071 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1072 return base->in(0)->in(TypeFunc::Parms); 1073 } 1074 } 1075 1076 break; 1077 } 1078 1079 return NULL; 1080} 1081 1082//----------------------is_instance_field_load_with_local_phi------------------ 1083bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1084 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1085 in(Address)->is_AddP() ) { 1086 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1087 // Only instances and boxed values. 1088 if( t_oop != NULL && 1089 (t_oop->is_ptr_to_boxed_value() || 1090 t_oop->is_known_instance_field()) && 1091 t_oop->offset() != Type::OffsetBot && 1092 t_oop->offset() != Type::OffsetTop) { 1093 return true; 1094 } 1095 } 1096 return false; 1097} 1098 1099//------------------------------Identity--------------------------------------- 1100// Loads are identity if previous store is to same address 1101Node* LoadNode::Identity(PhaseGVN* phase) { 1102 // If the previous store-maker is the right kind of Store, and the store is 1103 // to the same address, then we are equal to the value stored. 1104 Node* mem = in(Memory); 1105 Node* value = can_see_stored_value(mem, phase); 1106 if( value ) { 1107 // byte, short & char stores truncate naturally. 1108 // A load has to load the truncated value which requires 1109 // some sort of masking operation and that requires an 1110 // Ideal call instead of an Identity call. 1111 if (memory_size() < BytesPerInt) { 1112 // If the input to the store does not fit with the load's result type, 1113 // it must be truncated via an Ideal call. 1114 if (!phase->type(value)->higher_equal(phase->type(this))) 1115 return this; 1116 } 1117 // (This works even when value is a Con, but LoadNode::Value 1118 // usually runs first, producing the singleton type of the Con.) 1119 return value; 1120 } 1121 1122 // Search for an existing data phi which was generated before for the same 1123 // instance's field to avoid infinite generation of phis in a loop. 1124 Node *region = mem->in(0); 1125 if (is_instance_field_load_with_local_phi(region)) { 1126 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1127 int this_index = phase->C->get_alias_index(addr_t); 1128 int this_offset = addr_t->offset(); 1129 int this_iid = addr_t->instance_id(); 1130 if (!addr_t->is_known_instance() && 1131 addr_t->is_ptr_to_boxed_value()) { 1132 // Use _idx of address base (could be Phi node) for boxed values. 1133 intptr_t ignore = 0; 1134 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1135 if (base == NULL) { 1136 return this; 1137 } 1138 this_iid = base->_idx; 1139 } 1140 const Type* this_type = bottom_type(); 1141 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1142 Node* phi = region->fast_out(i); 1143 if (phi->is_Phi() && phi != mem && 1144 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) { 1145 return phi; 1146 } 1147 } 1148 } 1149 1150 return this; 1151} 1152 1153// Construct an equivalent unsigned load. 1154Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) { 1155 BasicType bt = T_ILLEGAL; 1156 const Type* rt = NULL; 1157 switch (Opcode()) { 1158 case Op_LoadUB: return this; 1159 case Op_LoadUS: return this; 1160 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break; 1161 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break; 1162 default: 1163 assert(false, "no unsigned variant: %s", Name()); 1164 return NULL; 1165 } 1166 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1167 raw_adr_type(), rt, bt, _mo, _control_dependency, 1168 is_unaligned_access(), is_mismatched_access()); 1169} 1170 1171// Construct an equivalent signed load. 1172Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) { 1173 BasicType bt = T_ILLEGAL; 1174 const Type* rt = NULL; 1175 switch (Opcode()) { 1176 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break; 1177 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break; 1178 case Op_LoadB: // fall through 1179 case Op_LoadS: // fall through 1180 case Op_LoadI: // fall through 1181 case Op_LoadL: return this; 1182 default: 1183 assert(false, "no signed variant: %s", Name()); 1184 return NULL; 1185 } 1186 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), 1187 raw_adr_type(), rt, bt, _mo, _control_dependency, 1188 is_unaligned_access(), is_mismatched_access()); 1189} 1190 1191// We're loading from an object which has autobox behaviour. 1192// If this object is result of a valueOf call we'll have a phi 1193// merging a newly allocated object and a load from the cache. 1194// We want to replace this load with the original incoming 1195// argument to the valueOf call. 1196Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1197 assert(phase->C->eliminate_boxing(), "sanity"); 1198 intptr_t ignore = 0; 1199 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1200 if ((base == NULL) || base->is_Phi()) { 1201 // Push the loads from the phi that comes from valueOf up 1202 // through it to allow elimination of the loads and the recovery 1203 // of the original value. It is done in split_through_phi(). 1204 return NULL; 1205 } else if (base->is_Load() || 1206 base->is_DecodeN() && base->in(1)->is_Load()) { 1207 // Eliminate the load of boxed value for integer types from the cache 1208 // array by deriving the value from the index into the array. 1209 // Capture the offset of the load and then reverse the computation. 1210 1211 // Get LoadN node which loads a boxing object from 'cache' array. 1212 if (base->is_DecodeN()) { 1213 base = base->in(1); 1214 } 1215 if (!base->in(Address)->is_AddP()) { 1216 return NULL; // Complex address 1217 } 1218 AddPNode* address = base->in(Address)->as_AddP(); 1219 Node* cache_base = address->in(AddPNode::Base); 1220 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1221 // Get ConP node which is static 'cache' field. 1222 cache_base = cache_base->in(1); 1223 } 1224 if ((cache_base != NULL) && cache_base->is_Con()) { 1225 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1226 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1227 Node* elements[4]; 1228 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1229 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1230 if ((count > 0) && elements[0]->is_Con() && 1231 ((count == 1) || 1232 (count == 2) && elements[1]->Opcode() == Op_LShiftX && 1233 elements[1]->in(2) == phase->intcon(shift))) { 1234 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1235 // Fetch the box object cache[0] at the base of the array and get its value 1236 ciInstance* box = array->obj_at(0)->as_instance(); 1237 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1238 assert(ik->is_box_klass(), "sanity"); 1239 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1240 if (ik->nof_nonstatic_fields() == 1) { 1241 // This should be true nonstatic_field_at requires calling 1242 // nof_nonstatic_fields so check it anyway 1243 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1244 BasicType bt = c.basic_type(); 1245 // Only integer types have boxing cache. 1246 assert(bt == T_BOOLEAN || bt == T_CHAR || 1247 bt == T_BYTE || bt == T_SHORT || 1248 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt)); 1249 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1250 if (cache_low != (int)cache_low) { 1251 return NULL; // should not happen since cache is array indexed by value 1252 } 1253 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1254 if (offset != (int)offset) { 1255 return NULL; // should not happen since cache is array indexed by value 1256 } 1257 // Add up all the offsets making of the address of the load 1258 Node* result = elements[0]; 1259 for (int i = 1; i < count; i++) { 1260 result = phase->transform(new AddXNode(result, elements[i])); 1261 } 1262 // Remove the constant offset from the address and then 1263 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset))); 1264 // remove the scaling of the offset to recover the original index. 1265 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1266 // Peel the shift off directly but wrap it in a dummy node 1267 // since Ideal can't return existing nodes 1268 result = new RShiftXNode(result->in(1), phase->intcon(0)); 1269 } else if (result->is_Add() && result->in(2)->is_Con() && 1270 result->in(1)->Opcode() == Op_LShiftX && 1271 result->in(1)->in(2) == phase->intcon(shift)) { 1272 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1273 // but for boxing cache access we know that X<<Z will not overflow 1274 // (there is range check) so we do this optimizatrion by hand here. 1275 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift)); 1276 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con)); 1277 } else { 1278 result = new RShiftXNode(result, phase->intcon(shift)); 1279 } 1280#ifdef _LP64 1281 if (bt != T_LONG) { 1282 result = new ConvL2INode(phase->transform(result)); 1283 } 1284#else 1285 if (bt == T_LONG) { 1286 result = new ConvI2LNode(phase->transform(result)); 1287 } 1288#endif 1289 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1290 // Need to preserve unboxing load type if it is unsigned. 1291 switch(this->Opcode()) { 1292 case Op_LoadUB: 1293 result = new AndINode(phase->transform(result), phase->intcon(0xFF)); 1294 break; 1295 case Op_LoadUS: 1296 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF)); 1297 break; 1298 } 1299 return result; 1300 } 1301 } 1302 } 1303 } 1304 } 1305 return NULL; 1306} 1307 1308static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1309 Node* region = phi->in(0); 1310 if (region == NULL) { 1311 return false; // Wait stable graph 1312 } 1313 uint cnt = phi->req(); 1314 for (uint i = 1; i < cnt; i++) { 1315 Node* rc = region->in(i); 1316 if (rc == NULL || phase->type(rc) == Type::TOP) 1317 return false; // Wait stable graph 1318 Node* in = phi->in(i); 1319 if (in == NULL || phase->type(in) == Type::TOP) 1320 return false; // Wait stable graph 1321 } 1322 return true; 1323} 1324//------------------------------split_through_phi------------------------------ 1325// Split instance or boxed field load through Phi. 1326Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1327 Node* mem = in(Memory); 1328 Node* address = in(Address); 1329 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1330 1331 assert((t_oop != NULL) && 1332 (t_oop->is_known_instance_field() || 1333 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1334 1335 Compile* C = phase->C; 1336 intptr_t ignore = 0; 1337 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1338 bool base_is_phi = (base != NULL) && base->is_Phi(); 1339 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1340 (base != NULL) && (base == address->in(AddPNode::Base)) && 1341 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1342 1343 if (!((mem->is_Phi() || base_is_phi) && 1344 (load_boxed_values || t_oop->is_known_instance_field()))) { 1345 return NULL; // memory is not Phi 1346 } 1347 1348 if (mem->is_Phi()) { 1349 if (!stable_phi(mem->as_Phi(), phase)) { 1350 return NULL; // Wait stable graph 1351 } 1352 uint cnt = mem->req(); 1353 // Check for loop invariant memory. 1354 if (cnt == 3) { 1355 for (uint i = 1; i < cnt; i++) { 1356 Node* in = mem->in(i); 1357 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1358 if (m == mem) { 1359 set_req(Memory, mem->in(cnt - i)); 1360 return this; // made change 1361 } 1362 } 1363 } 1364 } 1365 if (base_is_phi) { 1366 if (!stable_phi(base->as_Phi(), phase)) { 1367 return NULL; // Wait stable graph 1368 } 1369 uint cnt = base->req(); 1370 // Check for loop invariant memory. 1371 if (cnt == 3) { 1372 for (uint i = 1; i < cnt; i++) { 1373 if (base->in(i) == base) { 1374 return NULL; // Wait stable graph 1375 } 1376 } 1377 } 1378 } 1379 1380 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0)); 1381 1382 // Split through Phi (see original code in loopopts.cpp). 1383 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1384 1385 // Do nothing here if Identity will find a value 1386 // (to avoid infinite chain of value phis generation). 1387 if (!phase->eqv(this, this->Identity(phase))) 1388 return NULL; 1389 1390 // Select Region to split through. 1391 Node* region; 1392 if (!base_is_phi) { 1393 assert(mem->is_Phi(), "sanity"); 1394 region = mem->in(0); 1395 // Skip if the region dominates some control edge of the address. 1396 if (!MemNode::all_controls_dominate(address, region)) 1397 return NULL; 1398 } else if (!mem->is_Phi()) { 1399 assert(base_is_phi, "sanity"); 1400 region = base->in(0); 1401 // Skip if the region dominates some control edge of the memory. 1402 if (!MemNode::all_controls_dominate(mem, region)) 1403 return NULL; 1404 } else if (base->in(0) != mem->in(0)) { 1405 assert(base_is_phi && mem->is_Phi(), "sanity"); 1406 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1407 region = base->in(0); 1408 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1409 region = mem->in(0); 1410 } else { 1411 return NULL; // complex graph 1412 } 1413 } else { 1414 assert(base->in(0) == mem->in(0), "sanity"); 1415 region = mem->in(0); 1416 } 1417 1418 const Type* this_type = this->bottom_type(); 1419 int this_index = C->get_alias_index(t_oop); 1420 int this_offset = t_oop->offset(); 1421 int this_iid = t_oop->instance_id(); 1422 if (!t_oop->is_known_instance() && load_boxed_values) { 1423 // Use _idx of address base for boxed values. 1424 this_iid = base->_idx; 1425 } 1426 PhaseIterGVN* igvn = phase->is_IterGVN(); 1427 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset); 1428 for (uint i = 1; i < region->req(); i++) { 1429 Node* x; 1430 Node* the_clone = NULL; 1431 if (region->in(i) == C->top()) { 1432 x = C->top(); // Dead path? Use a dead data op 1433 } else { 1434 x = this->clone(); // Else clone up the data op 1435 the_clone = x; // Remember for possible deletion. 1436 // Alter data node to use pre-phi inputs 1437 if (this->in(0) == region) { 1438 x->set_req(0, region->in(i)); 1439 } else { 1440 x->set_req(0, NULL); 1441 } 1442 if (mem->is_Phi() && (mem->in(0) == region)) { 1443 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1444 } 1445 if (address->is_Phi() && address->in(0) == region) { 1446 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1447 } 1448 if (base_is_phi && (base->in(0) == region)) { 1449 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1450 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1451 x->set_req(Address, adr_x); 1452 } 1453 } 1454 // Check for a 'win' on some paths 1455 const Type *t = x->Value(igvn); 1456 1457 bool singleton = t->singleton(); 1458 1459 // See comments in PhaseIdealLoop::split_thru_phi(). 1460 if (singleton && t == Type::TOP) { 1461 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1462 } 1463 1464 if (singleton) { 1465 x = igvn->makecon(t); 1466 } else { 1467 // We now call Identity to try to simplify the cloned node. 1468 // Note that some Identity methods call phase->type(this). 1469 // Make sure that the type array is big enough for 1470 // our new node, even though we may throw the node away. 1471 // (This tweaking with igvn only works because x is a new node.) 1472 igvn->set_type(x, t); 1473 // If x is a TypeNode, capture any more-precise type permanently into Node 1474 // otherwise it will be not updated during igvn->transform since 1475 // igvn->type(x) is set to x->Value() already. 1476 x->raise_bottom_type(t); 1477 Node *y = x->Identity(igvn); 1478 if (y != x) { 1479 x = y; 1480 } else { 1481 y = igvn->hash_find_insert(x); 1482 if (y) { 1483 x = y; 1484 } else { 1485 // Else x is a new node we are keeping 1486 // We do not need register_new_node_with_optimizer 1487 // because set_type has already been called. 1488 igvn->_worklist.push(x); 1489 } 1490 } 1491 } 1492 if (x != the_clone && the_clone != NULL) { 1493 igvn->remove_dead_node(the_clone); 1494 } 1495 phi->set_req(i, x); 1496 } 1497 // Record Phi 1498 igvn->register_new_node_with_optimizer(phi); 1499 return phi; 1500} 1501 1502//------------------------------Ideal------------------------------------------ 1503// If the load is from Field memory and the pointer is non-null, it might be possible to 1504// zero out the control input. 1505// If the offset is constant and the base is an object allocation, 1506// try to hook me up to the exact initializing store. 1507Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1508 Node* p = MemNode::Ideal_common(phase, can_reshape); 1509 if (p) return (p == NodeSentinel) ? NULL : p; 1510 1511 Node* ctrl = in(MemNode::Control); 1512 Node* address = in(MemNode::Address); 1513 bool progress = false; 1514 1515 // Skip up past a SafePoint control. Cannot do this for Stores because 1516 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1517 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1518 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1519 ctrl = ctrl->in(0); 1520 set_req(MemNode::Control,ctrl); 1521 progress = true; 1522 } 1523 1524 intptr_t ignore = 0; 1525 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1526 if (base != NULL 1527 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1528 // Check for useless control edge in some common special cases 1529 if (in(MemNode::Control) != NULL 1530 && can_remove_control() 1531 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1532 && all_controls_dominate(base, phase->C->start())) { 1533 // A method-invariant, non-null address (constant or 'this' argument). 1534 set_req(MemNode::Control, NULL); 1535 progress = true; 1536 } 1537 } 1538 1539 Node* mem = in(MemNode::Memory); 1540 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1541 1542 if (can_reshape && (addr_t != NULL)) { 1543 // try to optimize our memory input 1544 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1545 if (opt_mem != mem) { 1546 set_req(MemNode::Memory, opt_mem); 1547 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1548 return this; 1549 } 1550 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1551 if ((t_oop != NULL) && 1552 (t_oop->is_known_instance_field() || 1553 t_oop->is_ptr_to_boxed_value())) { 1554 PhaseIterGVN *igvn = phase->is_IterGVN(); 1555 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1556 // Delay this transformation until memory Phi is processed. 1557 phase->is_IterGVN()->_worklist.push(this); 1558 return NULL; 1559 } 1560 // Split instance field load through Phi. 1561 Node* result = split_through_phi(phase); 1562 if (result != NULL) return result; 1563 1564 if (t_oop->is_ptr_to_boxed_value()) { 1565 Node* result = eliminate_autobox(phase); 1566 if (result != NULL) return result; 1567 } 1568 } 1569 } 1570 1571 // Is there a dominating load that loads the same value? Leave 1572 // anything that is not a load of a field/array element (like 1573 // barriers etc.) alone 1574 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) { 1575 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 1576 Node *use = mem->fast_out(i); 1577 if (use != this && 1578 use->Opcode() == Opcode() && 1579 use->in(0) != NULL && 1580 use->in(0) != in(0) && 1581 use->in(Address) == in(Address)) { 1582 Node* ctl = in(0); 1583 for (int i = 0; i < 10 && ctl != NULL; i++) { 1584 ctl = IfNode::up_one_dom(ctl); 1585 if (ctl == use->in(0)) { 1586 set_req(0, use->in(0)); 1587 return this; 1588 } 1589 } 1590 } 1591 } 1592 } 1593 1594 // Check for prior store with a different base or offset; make Load 1595 // independent. Skip through any number of them. Bail out if the stores 1596 // are in an endless dead cycle and report no progress. This is a key 1597 // transform for Reflection. However, if after skipping through the Stores 1598 // we can't then fold up against a prior store do NOT do the transform as 1599 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1600 // array memory alive twice: once for the hoisted Load and again after the 1601 // bypassed Store. This situation only works if EVERYBODY who does 1602 // anti-dependence work knows how to bypass. I.e. we need all 1603 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1604 // the alias index stuff. So instead, peek through Stores and IFF we can 1605 // fold up, do so. 1606 Node* prev_mem = find_previous_store(phase); 1607 if (prev_mem != NULL) { 1608 Node* value = can_see_arraycopy_value(prev_mem, phase); 1609 if (value != NULL) { 1610 return value; 1611 } 1612 } 1613 // Steps (a), (b): Walk past independent stores to find an exact match. 1614 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1615 // (c) See if we can fold up on the spot, but don't fold up here. 1616 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1617 // just return a prior value, which is done by Identity calls. 1618 if (can_see_stored_value(prev_mem, phase)) { 1619 // Make ready for step (d): 1620 set_req(MemNode::Memory, prev_mem); 1621 return this; 1622 } 1623 } 1624 1625 return progress ? this : NULL; 1626} 1627 1628// Helper to recognize certain Klass fields which are invariant across 1629// some group of array types (e.g., int[] or all T[] where T < Object). 1630const Type* 1631LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1632 ciKlass* klass) const { 1633 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1634 // The field is Klass::_modifier_flags. Return its (constant) value. 1635 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1636 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1637 return TypeInt::make(klass->modifier_flags()); 1638 } 1639 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1640 // The field is Klass::_access_flags. Return its (constant) value. 1641 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1642 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1643 return TypeInt::make(klass->access_flags()); 1644 } 1645 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1646 // The field is Klass::_layout_helper. Return its constant value if known. 1647 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1648 return TypeInt::make(klass->layout_helper()); 1649 } 1650 1651 // No match. 1652 return NULL; 1653} 1654 1655//------------------------------Value----------------------------------------- 1656const Type* LoadNode::Value(PhaseGVN* phase) const { 1657 // Either input is TOP ==> the result is TOP 1658 Node* mem = in(MemNode::Memory); 1659 const Type *t1 = phase->type(mem); 1660 if (t1 == Type::TOP) return Type::TOP; 1661 Node* adr = in(MemNode::Address); 1662 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1663 if (tp == NULL || tp->empty()) return Type::TOP; 1664 int off = tp->offset(); 1665 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1666 Compile* C = phase->C; 1667 1668 // Try to guess loaded type from pointer type 1669 if (tp->isa_aryptr()) { 1670 const TypeAryPtr* ary = tp->is_aryptr(); 1671 const Type* t = ary->elem(); 1672 1673 // Determine whether the reference is beyond the header or not, by comparing 1674 // the offset against the offset of the start of the array's data. 1675 // Different array types begin at slightly different offsets (12 vs. 16). 1676 // We choose T_BYTE as an example base type that is least restrictive 1677 // as to alignment, which will therefore produce the smallest 1678 // possible base offset. 1679 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1680 const bool off_beyond_header = ((uint)off >= (uint)min_base_off); 1681 1682 // Try to constant-fold a stable array element. 1683 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) { 1684 // Make sure the reference is not into the header and the offset is constant 1685 ciObject* aobj = ary->const_oop(); 1686 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1687 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0); 1688 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, 1689 stable_dimension, 1690 memory_type(), is_unsigned()); 1691 if (con_type != NULL) { 1692 return con_type; 1693 } 1694 } 1695 } 1696 1697 // Don't do this for integer types. There is only potential profit if 1698 // the element type t is lower than _type; that is, for int types, if _type is 1699 // more restrictive than t. This only happens here if one is short and the other 1700 // char (both 16 bits), and in those cases we've made an intentional decision 1701 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1702 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1703 // 1704 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1705 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1706 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1707 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1708 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1709 // In fact, that could have been the original type of p1, and p1 could have 1710 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1711 // expression (LShiftL quux 3) independently optimized to the constant 8. 1712 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1713 && (_type->isa_vect() == NULL) 1714 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1715 // t might actually be lower than _type, if _type is a unique 1716 // concrete subclass of abstract class t. 1717 if (off_beyond_header) { // is the offset beyond the header? 1718 const Type* jt = t->join_speculative(_type); 1719 // In any case, do not allow the join, per se, to empty out the type. 1720 if (jt->empty() && !t->empty()) { 1721 // This can happen if a interface-typed array narrows to a class type. 1722 jt = _type; 1723 } 1724#ifdef ASSERT 1725 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1726 // The pointers in the autobox arrays are always non-null 1727 Node* base = adr->in(AddPNode::Base); 1728 if ((base != NULL) && base->is_DecodeN()) { 1729 // Get LoadN node which loads IntegerCache.cache field 1730 base = base->in(1); 1731 } 1732 if ((base != NULL) && base->is_Con()) { 1733 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1734 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1735 // It could be narrow oop 1736 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1737 } 1738 } 1739 } 1740#endif 1741 return jt; 1742 } 1743 } 1744 } else if (tp->base() == Type::InstPtr) { 1745 assert( off != Type::OffsetBot || 1746 // arrays can be cast to Objects 1747 tp->is_oopptr()->klass()->is_java_lang_Object() || 1748 // unsafe field access may not have a constant offset 1749 C->has_unsafe_access(), 1750 "Field accesses must be precise" ); 1751 // For oop loads, we expect the _type to be precise. 1752 1753 // Optimize loads from constant fields. 1754 const TypeInstPtr* tinst = tp->is_instptr(); 1755 ciObject* const_oop = tinst->const_oop(); 1756 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) { 1757 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type()); 1758 if (con_type != NULL) { 1759 return con_type; 1760 } 1761 } 1762 } else if (tp->base() == Type::KlassPtr) { 1763 assert( off != Type::OffsetBot || 1764 // arrays can be cast to Objects 1765 tp->is_klassptr()->klass()->is_java_lang_Object() || 1766 // also allow array-loading from the primary supertype 1767 // array during subtype checks 1768 Opcode() == Op_LoadKlass, 1769 "Field accesses must be precise" ); 1770 // For klass/static loads, we expect the _type to be precise 1771 } 1772 1773 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1774 if (tkls != NULL && !StressReflectiveCode) { 1775 ciKlass* klass = tkls->klass(); 1776 if (klass->is_loaded() && tkls->klass_is_exact()) { 1777 // We are loading a field from a Klass metaobject whose identity 1778 // is known at compile time (the type is "exact" or "precise"). 1779 // Check for fields we know are maintained as constants by the VM. 1780 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1781 // The field is Klass::_super_check_offset. Return its (constant) value. 1782 // (Folds up type checking code.) 1783 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1784 return TypeInt::make(klass->super_check_offset()); 1785 } 1786 // Compute index into primary_supers array 1787 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1788 // Check for overflowing; use unsigned compare to handle the negative case. 1789 if( depth < ciKlass::primary_super_limit() ) { 1790 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1791 // (Folds up type checking code.) 1792 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1793 ciKlass *ss = klass->super_of_depth(depth); 1794 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1795 } 1796 const Type* aift = load_array_final_field(tkls, klass); 1797 if (aift != NULL) return aift; 1798 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1799 // The field is Klass::_java_mirror. Return its (constant) value. 1800 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1801 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1802 return TypeInstPtr::make(klass->java_mirror()); 1803 } 1804 } 1805 1806 // We can still check if we are loading from the primary_supers array at a 1807 // shallow enough depth. Even though the klass is not exact, entries less 1808 // than or equal to its super depth are correct. 1809 if (klass->is_loaded() ) { 1810 ciType *inner = klass; 1811 while( inner->is_obj_array_klass() ) 1812 inner = inner->as_obj_array_klass()->base_element_type(); 1813 if( inner->is_instance_klass() && 1814 !inner->as_instance_klass()->flags().is_interface() ) { 1815 // Compute index into primary_supers array 1816 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1817 // Check for overflowing; use unsigned compare to handle the negative case. 1818 if( depth < ciKlass::primary_super_limit() && 1819 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1820 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1821 // (Folds up type checking code.) 1822 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1823 ciKlass *ss = klass->super_of_depth(depth); 1824 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1825 } 1826 } 1827 } 1828 1829 // If the type is enough to determine that the thing is not an array, 1830 // we can give the layout_helper a positive interval type. 1831 // This will help short-circuit some reflective code. 1832 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1833 && !klass->is_array_klass() // not directly typed as an array 1834 && !klass->is_interface() // specifically not Serializable & Cloneable 1835 && !klass->is_java_lang_Object() // not the supertype of all T[] 1836 ) { 1837 // Note: When interfaces are reliable, we can narrow the interface 1838 // test to (klass != Serializable && klass != Cloneable). 1839 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1840 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1841 // The key property of this type is that it folds up tests 1842 // for array-ness, since it proves that the layout_helper is positive. 1843 // Thus, a generic value like the basic object layout helper works fine. 1844 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1845 } 1846 } 1847 1848 // If we are loading from a freshly-allocated object, produce a zero, 1849 // if the load is provably beyond the header of the object. 1850 // (Also allow a variable load from a fresh array to produce zero.) 1851 const TypeOopPtr *tinst = tp->isa_oopptr(); 1852 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1853 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 1854 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 1855 Node* value = can_see_stored_value(mem,phase); 1856 if (value != NULL && value->is_Con()) { 1857 assert(value->bottom_type()->higher_equal(_type),"sanity"); 1858 return value->bottom_type(); 1859 } 1860 } 1861 1862 if (is_instance) { 1863 // If we have an instance type and our memory input is the 1864 // programs's initial memory state, there is no matching store, 1865 // so just return a zero of the appropriate type 1866 Node *mem = in(MemNode::Memory); 1867 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1868 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1869 return Type::get_zero_type(_type->basic_type()); 1870 } 1871 } 1872 return _type; 1873} 1874 1875//------------------------------match_edge------------------------------------- 1876// Do we Match on this edge index or not? Match only the address. 1877uint LoadNode::match_edge(uint idx) const { 1878 return idx == MemNode::Address; 1879} 1880 1881//--------------------------LoadBNode::Ideal-------------------------------------- 1882// 1883// If the previous store is to the same address as this load, 1884// and the value stored was larger than a byte, replace this load 1885// with the value stored truncated to a byte. If no truncation is 1886// needed, the replacement is done in LoadNode::Identity(). 1887// 1888Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1889 Node* mem = in(MemNode::Memory); 1890 Node* value = can_see_stored_value(mem,phase); 1891 if( value && !phase->type(value)->higher_equal( _type ) ) { 1892 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) ); 1893 return new RShiftINode(result, phase->intcon(24)); 1894 } 1895 // Identity call will handle the case where truncation is not needed. 1896 return LoadNode::Ideal(phase, can_reshape); 1897} 1898 1899const Type* LoadBNode::Value(PhaseGVN* phase) const { 1900 Node* mem = in(MemNode::Memory); 1901 Node* value = can_see_stored_value(mem,phase); 1902 if (value != NULL && value->is_Con() && 1903 !value->bottom_type()->higher_equal(_type)) { 1904 // If the input to the store does not fit with the load's result type, 1905 // it must be truncated. We can't delay until Ideal call since 1906 // a singleton Value is needed for split_thru_phi optimization. 1907 int con = value->get_int(); 1908 return TypeInt::make((con << 24) >> 24); 1909 } 1910 return LoadNode::Value(phase); 1911} 1912 1913//--------------------------LoadUBNode::Ideal------------------------------------- 1914// 1915// If the previous store is to the same address as this load, 1916// and the value stored was larger than a byte, replace this load 1917// with the value stored truncated to a byte. If no truncation is 1918// needed, the replacement is done in LoadNode::Identity(). 1919// 1920Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 1921 Node* mem = in(MemNode::Memory); 1922 Node* value = can_see_stored_value(mem, phase); 1923 if (value && !phase->type(value)->higher_equal(_type)) 1924 return new AndINode(value, phase->intcon(0xFF)); 1925 // Identity call will handle the case where truncation is not needed. 1926 return LoadNode::Ideal(phase, can_reshape); 1927} 1928 1929const Type* LoadUBNode::Value(PhaseGVN* phase) const { 1930 Node* mem = in(MemNode::Memory); 1931 Node* value = can_see_stored_value(mem,phase); 1932 if (value != NULL && value->is_Con() && 1933 !value->bottom_type()->higher_equal(_type)) { 1934 // If the input to the store does not fit with the load's result type, 1935 // it must be truncated. We can't delay until Ideal call since 1936 // a singleton Value is needed for split_thru_phi optimization. 1937 int con = value->get_int(); 1938 return TypeInt::make(con & 0xFF); 1939 } 1940 return LoadNode::Value(phase); 1941} 1942 1943//--------------------------LoadUSNode::Ideal------------------------------------- 1944// 1945// If the previous store is to the same address as this load, 1946// and the value stored was larger than a char, replace this load 1947// with the value stored truncated to a char. If no truncation is 1948// needed, the replacement is done in LoadNode::Identity(). 1949// 1950Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1951 Node* mem = in(MemNode::Memory); 1952 Node* value = can_see_stored_value(mem,phase); 1953 if( value && !phase->type(value)->higher_equal( _type ) ) 1954 return new AndINode(value,phase->intcon(0xFFFF)); 1955 // Identity call will handle the case where truncation is not needed. 1956 return LoadNode::Ideal(phase, can_reshape); 1957} 1958 1959const Type* LoadUSNode::Value(PhaseGVN* phase) const { 1960 Node* mem = in(MemNode::Memory); 1961 Node* value = can_see_stored_value(mem,phase); 1962 if (value != NULL && value->is_Con() && 1963 !value->bottom_type()->higher_equal(_type)) { 1964 // If the input to the store does not fit with the load's result type, 1965 // it must be truncated. We can't delay until Ideal call since 1966 // a singleton Value is needed for split_thru_phi optimization. 1967 int con = value->get_int(); 1968 return TypeInt::make(con & 0xFFFF); 1969 } 1970 return LoadNode::Value(phase); 1971} 1972 1973//--------------------------LoadSNode::Ideal-------------------------------------- 1974// 1975// If the previous store is to the same address as this load, 1976// and the value stored was larger than a short, replace this load 1977// with the value stored truncated to a short. If no truncation is 1978// needed, the replacement is done in LoadNode::Identity(). 1979// 1980Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1981 Node* mem = in(MemNode::Memory); 1982 Node* value = can_see_stored_value(mem,phase); 1983 if( value && !phase->type(value)->higher_equal( _type ) ) { 1984 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) ); 1985 return new RShiftINode(result, phase->intcon(16)); 1986 } 1987 // Identity call will handle the case where truncation is not needed. 1988 return LoadNode::Ideal(phase, can_reshape); 1989} 1990 1991const Type* LoadSNode::Value(PhaseGVN* phase) const { 1992 Node* mem = in(MemNode::Memory); 1993 Node* value = can_see_stored_value(mem,phase); 1994 if (value != NULL && value->is_Con() && 1995 !value->bottom_type()->higher_equal(_type)) { 1996 // If the input to the store does not fit with the load's result type, 1997 // it must be truncated. We can't delay until Ideal call since 1998 // a singleton Value is needed for split_thru_phi optimization. 1999 int con = value->get_int(); 2000 return TypeInt::make((con << 16) >> 16); 2001 } 2002 return LoadNode::Value(phase); 2003} 2004 2005//============================================================================= 2006//----------------------------LoadKlassNode::make------------------------------ 2007// Polymorphic factory method: 2008Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2009 // sanity check the alias category against the created node type 2010 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2011 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2012#ifdef _LP64 2013 if (adr_type->is_ptr_to_narrowklass()) { 2014 assert(UseCompressedClassPointers, "no compressed klasses"); 2015 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2016 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2017 } 2018#endif 2019 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2020 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2021} 2022 2023//------------------------------Value------------------------------------------ 2024const Type* LoadKlassNode::Value(PhaseGVN* phase) const { 2025 return klass_value_common(phase); 2026} 2027 2028// In most cases, LoadKlassNode does not have the control input set. If the control 2029// input is set, it must not be removed (by LoadNode::Ideal()). 2030bool LoadKlassNode::can_remove_control() const { 2031 return false; 2032} 2033 2034const Type* LoadNode::klass_value_common(PhaseGVN* phase) const { 2035 // Either input is TOP ==> the result is TOP 2036 const Type *t1 = phase->type( in(MemNode::Memory) ); 2037 if (t1 == Type::TOP) return Type::TOP; 2038 Node *adr = in(MemNode::Address); 2039 const Type *t2 = phase->type( adr ); 2040 if (t2 == Type::TOP) return Type::TOP; 2041 const TypePtr *tp = t2->is_ptr(); 2042 if (TypePtr::above_centerline(tp->ptr()) || 2043 tp->ptr() == TypePtr::Null) return Type::TOP; 2044 2045 // Return a more precise klass, if possible 2046 const TypeInstPtr *tinst = tp->isa_instptr(); 2047 if (tinst != NULL) { 2048 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2049 int offset = tinst->offset(); 2050 if (ik == phase->C->env()->Class_klass() 2051 && (offset == java_lang_Class::klass_offset_in_bytes() || 2052 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2053 // We are loading a special hidden field from a Class mirror object, 2054 // the field which points to the VM's Klass metaobject. 2055 ciType* t = tinst->java_mirror_type(); 2056 // java_mirror_type returns non-null for compile-time Class constants. 2057 if (t != NULL) { 2058 // constant oop => constant klass 2059 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2060 if (t->is_void()) { 2061 // We cannot create a void array. Since void is a primitive type return null 2062 // klass. Users of this result need to do a null check on the returned klass. 2063 return TypePtr::NULL_PTR; 2064 } 2065 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2066 } 2067 if (!t->is_klass()) { 2068 // a primitive Class (e.g., int.class) has NULL for a klass field 2069 return TypePtr::NULL_PTR; 2070 } 2071 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2072 return TypeKlassPtr::make(t->as_klass()); 2073 } 2074 // non-constant mirror, so we can't tell what's going on 2075 } 2076 if( !ik->is_loaded() ) 2077 return _type; // Bail out if not loaded 2078 if (offset == oopDesc::klass_offset_in_bytes()) { 2079 if (tinst->klass_is_exact()) { 2080 return TypeKlassPtr::make(ik); 2081 } 2082 // See if we can become precise: no subklasses and no interface 2083 // (Note: We need to support verified interfaces.) 2084 if (!ik->is_interface() && !ik->has_subklass()) { 2085 //assert(!UseExactTypes, "this code should be useless with exact types"); 2086 // Add a dependence; if any subclass added we need to recompile 2087 if (!ik->is_final()) { 2088 // %%% should use stronger assert_unique_concrete_subtype instead 2089 phase->C->dependencies()->assert_leaf_type(ik); 2090 } 2091 // Return precise klass 2092 return TypeKlassPtr::make(ik); 2093 } 2094 2095 // Return root of possible klass 2096 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2097 } 2098 } 2099 2100 // Check for loading klass from an array 2101 const TypeAryPtr *tary = tp->isa_aryptr(); 2102 if( tary != NULL ) { 2103 ciKlass *tary_klass = tary->klass(); 2104 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2105 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2106 if (tary->klass_is_exact()) { 2107 return TypeKlassPtr::make(tary_klass); 2108 } 2109 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2110 // If the klass is an object array, we defer the question to the 2111 // array component klass. 2112 if( ak->is_obj_array_klass() ) { 2113 assert( ak->is_loaded(), "" ); 2114 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2115 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2116 ciInstanceKlass* ik = base_k->as_instance_klass(); 2117 // See if we can become precise: no subklasses and no interface 2118 if (!ik->is_interface() && !ik->has_subklass()) { 2119 //assert(!UseExactTypes, "this code should be useless with exact types"); 2120 // Add a dependence; if any subclass added we need to recompile 2121 if (!ik->is_final()) { 2122 phase->C->dependencies()->assert_leaf_type(ik); 2123 } 2124 // Return precise array klass 2125 return TypeKlassPtr::make(ak); 2126 } 2127 } 2128 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2129 } else { // Found a type-array? 2130 //assert(!UseExactTypes, "this code should be useless with exact types"); 2131 assert( ak->is_type_array_klass(), "" ); 2132 return TypeKlassPtr::make(ak); // These are always precise 2133 } 2134 } 2135 } 2136 2137 // Check for loading klass from an array klass 2138 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2139 if (tkls != NULL && !StressReflectiveCode) { 2140 ciKlass* klass = tkls->klass(); 2141 if( !klass->is_loaded() ) 2142 return _type; // Bail out if not loaded 2143 if( klass->is_obj_array_klass() && 2144 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2145 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2146 // // Always returning precise element type is incorrect, 2147 // // e.g., element type could be object and array may contain strings 2148 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2149 2150 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2151 // according to the element type's subclassing. 2152 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2153 } 2154 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2155 tkls->offset() == in_bytes(Klass::super_offset())) { 2156 ciKlass* sup = klass->as_instance_klass()->super(); 2157 // The field is Klass::_super. Return its (constant) value. 2158 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2159 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2160 } 2161 } 2162 2163 // Bailout case 2164 return LoadNode::Value(phase); 2165} 2166 2167//------------------------------Identity--------------------------------------- 2168// To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2169// Also feed through the klass in Allocate(...klass...)._klass. 2170Node* LoadKlassNode::Identity(PhaseGVN* phase) { 2171 return klass_identity_common(phase); 2172} 2173 2174Node* LoadNode::klass_identity_common(PhaseGVN* phase) { 2175 Node* x = LoadNode::Identity(phase); 2176 if (x != this) return x; 2177 2178 // Take apart the address into an oop and and offset. 2179 // Return 'this' if we cannot. 2180 Node* adr = in(MemNode::Address); 2181 intptr_t offset = 0; 2182 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2183 if (base == NULL) return this; 2184 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2185 if (toop == NULL) return this; 2186 2187 // We can fetch the klass directly through an AllocateNode. 2188 // This works even if the klass is not constant (clone or newArray). 2189 if (offset == oopDesc::klass_offset_in_bytes()) { 2190 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2191 if (allocated_klass != NULL) { 2192 return allocated_klass; 2193 } 2194 } 2195 2196 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2197 // See inline_native_Class_query for occurrences of these patterns. 2198 // Java Example: x.getClass().isAssignableFrom(y) 2199 // 2200 // This improves reflective code, often making the Class 2201 // mirror go completely dead. (Current exception: Class 2202 // mirrors may appear in debug info, but we could clean them out by 2203 // introducing a new debug info operator for Klass*.java_mirror). 2204 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2205 && offset == java_lang_Class::klass_offset_in_bytes()) { 2206 // We are loading a special hidden field from a Class mirror, 2207 // the field which points to its Klass or ArrayKlass metaobject. 2208 if (base->is_Load()) { 2209 Node* adr2 = base->in(MemNode::Address); 2210 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2211 if (tkls != NULL && !tkls->empty() 2212 && (tkls->klass()->is_instance_klass() || 2213 tkls->klass()->is_array_klass()) 2214 && adr2->is_AddP() 2215 ) { 2216 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2217 if (tkls->offset() == mirror_field) { 2218 return adr2->in(AddPNode::Base); 2219 } 2220 } 2221 } 2222 } 2223 2224 return this; 2225} 2226 2227 2228//------------------------------Value------------------------------------------ 2229const Type* LoadNKlassNode::Value(PhaseGVN* phase) const { 2230 const Type *t = klass_value_common(phase); 2231 if (t == Type::TOP) 2232 return t; 2233 2234 return t->make_narrowklass(); 2235} 2236 2237//------------------------------Identity--------------------------------------- 2238// To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2239// Also feed through the klass in Allocate(...klass...)._klass. 2240Node* LoadNKlassNode::Identity(PhaseGVN* phase) { 2241 Node *x = klass_identity_common(phase); 2242 2243 const Type *t = phase->type( x ); 2244 if( t == Type::TOP ) return x; 2245 if( t->isa_narrowklass()) return x; 2246 assert (!t->isa_narrowoop(), "no narrow oop here"); 2247 2248 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2249} 2250 2251//------------------------------Value----------------------------------------- 2252const Type* LoadRangeNode::Value(PhaseGVN* phase) const { 2253 // Either input is TOP ==> the result is TOP 2254 const Type *t1 = phase->type( in(MemNode::Memory) ); 2255 if( t1 == Type::TOP ) return Type::TOP; 2256 Node *adr = in(MemNode::Address); 2257 const Type *t2 = phase->type( adr ); 2258 if( t2 == Type::TOP ) return Type::TOP; 2259 const TypePtr *tp = t2->is_ptr(); 2260 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2261 const TypeAryPtr *tap = tp->isa_aryptr(); 2262 if( !tap ) return _type; 2263 return tap->size(); 2264} 2265 2266//-------------------------------Ideal--------------------------------------- 2267// Feed through the length in AllocateArray(...length...)._length. 2268Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2269 Node* p = MemNode::Ideal_common(phase, can_reshape); 2270 if (p) return (p == NodeSentinel) ? NULL : p; 2271 2272 // Take apart the address into an oop and and offset. 2273 // Return 'this' if we cannot. 2274 Node* adr = in(MemNode::Address); 2275 intptr_t offset = 0; 2276 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2277 if (base == NULL) return NULL; 2278 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2279 if (tary == NULL) return NULL; 2280 2281 // We can fetch the length directly through an AllocateArrayNode. 2282 // This works even if the length is not constant (clone or newArray). 2283 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2284 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2285 if (alloc != NULL) { 2286 Node* allocated_length = alloc->Ideal_length(); 2287 Node* len = alloc->make_ideal_length(tary, phase); 2288 if (allocated_length != len) { 2289 // New CastII improves on this. 2290 return len; 2291 } 2292 } 2293 } 2294 2295 return NULL; 2296} 2297 2298//------------------------------Identity--------------------------------------- 2299// Feed through the length in AllocateArray(...length...)._length. 2300Node* LoadRangeNode::Identity(PhaseGVN* phase) { 2301 Node* x = LoadINode::Identity(phase); 2302 if (x != this) return x; 2303 2304 // Take apart the address into an oop and and offset. 2305 // Return 'this' if we cannot. 2306 Node* adr = in(MemNode::Address); 2307 intptr_t offset = 0; 2308 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2309 if (base == NULL) return this; 2310 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2311 if (tary == NULL) return this; 2312 2313 // We can fetch the length directly through an AllocateArrayNode. 2314 // This works even if the length is not constant (clone or newArray). 2315 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2316 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2317 if (alloc != NULL) { 2318 Node* allocated_length = alloc->Ideal_length(); 2319 // Do not allow make_ideal_length to allocate a CastII node. 2320 Node* len = alloc->make_ideal_length(tary, phase, false); 2321 if (allocated_length == len) { 2322 // Return allocated_length only if it would not be improved by a CastII. 2323 return allocated_length; 2324 } 2325 } 2326 } 2327 2328 return this; 2329 2330} 2331 2332//============================================================================= 2333//---------------------------StoreNode::make----------------------------------- 2334// Polymorphic factory method: 2335StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2336 assert((mo == unordered || mo == release), "unexpected"); 2337 Compile* C = gvn.C; 2338 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2339 ctl != NULL, "raw memory operations should have control edge"); 2340 2341 switch (bt) { 2342 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case 2343 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2344 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2345 case T_CHAR: 2346 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2347 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2348 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2349 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2350 case T_METADATA: 2351 case T_ADDRESS: 2352 case T_OBJECT: 2353#ifdef _LP64 2354 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2355 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2356 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2357 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2358 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2359 adr->bottom_type()->isa_rawptr())) { 2360 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2361 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2362 } 2363#endif 2364 { 2365 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2366 } 2367 } 2368 ShouldNotReachHere(); 2369 return (StoreNode*)NULL; 2370} 2371 2372StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2373 bool require_atomic = true; 2374 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2375} 2376 2377StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2378 bool require_atomic = true; 2379 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2380} 2381 2382 2383//--------------------------bottom_type---------------------------------------- 2384const Type *StoreNode::bottom_type() const { 2385 return Type::MEMORY; 2386} 2387 2388//------------------------------hash------------------------------------------- 2389uint StoreNode::hash() const { 2390 // unroll addition of interesting fields 2391 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2392 2393 // Since they are not commoned, do not hash them: 2394 return NO_HASH; 2395} 2396 2397//------------------------------Ideal------------------------------------------ 2398// Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2399// When a store immediately follows a relevant allocation/initialization, 2400// try to capture it into the initialization, or hoist it above. 2401Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2402 Node* p = MemNode::Ideal_common(phase, can_reshape); 2403 if (p) return (p == NodeSentinel) ? NULL : p; 2404 2405 Node* mem = in(MemNode::Memory); 2406 Node* address = in(MemNode::Address); 2407 // Back-to-back stores to same address? Fold em up. Generally 2408 // unsafe if I have intervening uses... Also disallowed for StoreCM 2409 // since they must follow each StoreP operation. Redundant StoreCMs 2410 // are eliminated just before matching in final_graph_reshape. 2411 { 2412 Node* st = mem; 2413 // If Store 'st' has more than one use, we cannot fold 'st' away. 2414 // For example, 'st' might be the final state at a conditional 2415 // return. Or, 'st' might be used by some node which is live at 2416 // the same time 'st' is live, which might be unschedulable. So, 2417 // require exactly ONE user until such time as we clone 'mem' for 2418 // each of 'mem's uses (thus making the exactly-1-user-rule hold 2419 // true). 2420 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) { 2421 // Looking at a dead closed cycle of memory? 2422 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2423 assert(Opcode() == st->Opcode() || 2424 st->Opcode() == Op_StoreVector || 2425 Opcode() == Op_StoreVector || 2426 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw || 2427 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode 2428 (is_mismatched_access() || st->as_Store()->is_mismatched_access()), 2429 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]); 2430 2431 if (st->in(MemNode::Address)->eqv_uncast(address) && 2432 st->as_Store()->memory_size() <= this->memory_size()) { 2433 Node* use = st->raw_out(0); 2434 phase->igvn_rehash_node_delayed(use); 2435 if (can_reshape) { 2436 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN()); 2437 } else { 2438 // It's OK to do this in the parser, since DU info is always accurate, 2439 // and the parser always refers to nodes via SafePointNode maps. 2440 use->set_req(MemNode::Memory, st->in(MemNode::Memory)); 2441 } 2442 return this; 2443 } 2444 st = st->in(MemNode::Memory); 2445 } 2446 } 2447 2448 2449 // Capture an unaliased, unconditional, simple store into an initializer. 2450 // Or, if it is independent of the allocation, hoist it above the allocation. 2451 if (ReduceFieldZeroing && /*can_reshape &&*/ 2452 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2453 InitializeNode* init = mem->in(0)->as_Initialize(); 2454 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2455 if (offset > 0) { 2456 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2457 // If the InitializeNode captured me, it made a raw copy of me, 2458 // and I need to disappear. 2459 if (moved != NULL) { 2460 // %%% hack to ensure that Ideal returns a new node: 2461 mem = MergeMemNode::make(mem); 2462 return mem; // fold me away 2463 } 2464 } 2465 } 2466 2467 return NULL; // No further progress 2468} 2469 2470//------------------------------Value----------------------------------------- 2471const Type* StoreNode::Value(PhaseGVN* phase) const { 2472 // Either input is TOP ==> the result is TOP 2473 const Type *t1 = phase->type( in(MemNode::Memory) ); 2474 if( t1 == Type::TOP ) return Type::TOP; 2475 const Type *t2 = phase->type( in(MemNode::Address) ); 2476 if( t2 == Type::TOP ) return Type::TOP; 2477 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2478 if( t3 == Type::TOP ) return Type::TOP; 2479 return Type::MEMORY; 2480} 2481 2482//------------------------------Identity--------------------------------------- 2483// Remove redundant stores: 2484// Store(m, p, Load(m, p)) changes to m. 2485// Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2486Node* StoreNode::Identity(PhaseGVN* phase) { 2487 Node* mem = in(MemNode::Memory); 2488 Node* adr = in(MemNode::Address); 2489 Node* val = in(MemNode::ValueIn); 2490 2491 // Load then Store? Then the Store is useless 2492 if (val->is_Load() && 2493 val->in(MemNode::Address)->eqv_uncast(adr) && 2494 val->in(MemNode::Memory )->eqv_uncast(mem) && 2495 val->as_Load()->store_Opcode() == Opcode()) { 2496 return mem; 2497 } 2498 2499 // Two stores in a row of the same value? 2500 if (mem->is_Store() && 2501 mem->in(MemNode::Address)->eqv_uncast(adr) && 2502 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2503 mem->Opcode() == Opcode()) { 2504 return mem; 2505 } 2506 2507 // Store of zero anywhere into a freshly-allocated object? 2508 // Then the store is useless. 2509 // (It must already have been captured by the InitializeNode.) 2510 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2511 // a newly allocated object is already all-zeroes everywhere 2512 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2513 return mem; 2514 } 2515 2516 // the store may also apply to zero-bits in an earlier object 2517 Node* prev_mem = find_previous_store(phase); 2518 // Steps (a), (b): Walk past independent stores to find an exact match. 2519 if (prev_mem != NULL) { 2520 Node* prev_val = can_see_stored_value(prev_mem, phase); 2521 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2522 // prev_val and val might differ by a cast; it would be good 2523 // to keep the more informative of the two. 2524 return mem; 2525 } 2526 } 2527 } 2528 2529 return this; 2530} 2531 2532//------------------------------match_edge------------------------------------- 2533// Do we Match on this edge index or not? Match only memory & value 2534uint StoreNode::match_edge(uint idx) const { 2535 return idx == MemNode::Address || idx == MemNode::ValueIn; 2536} 2537 2538//------------------------------cmp-------------------------------------------- 2539// Do not common stores up together. They generally have to be split 2540// back up anyways, so do not bother. 2541uint StoreNode::cmp( const Node &n ) const { 2542 return (&n == this); // Always fail except on self 2543} 2544 2545//------------------------------Ideal_masked_input----------------------------- 2546// Check for a useless mask before a partial-word store 2547// (StoreB ... (AndI valIn conIa) ) 2548// If (conIa & mask == mask) this simplifies to 2549// (StoreB ... (valIn) ) 2550Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2551 Node *val = in(MemNode::ValueIn); 2552 if( val->Opcode() == Op_AndI ) { 2553 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2554 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2555 set_req(MemNode::ValueIn, val->in(1)); 2556 return this; 2557 } 2558 } 2559 return NULL; 2560} 2561 2562 2563//------------------------------Ideal_sign_extended_input---------------------- 2564// Check for useless sign-extension before a partial-word store 2565// (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2566// If (conIL == conIR && conIR <= num_bits) this simplifies to 2567// (StoreB ... (valIn) ) 2568Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2569 Node *val = in(MemNode::ValueIn); 2570 if( val->Opcode() == Op_RShiftI ) { 2571 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2572 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2573 Node *shl = val->in(1); 2574 if( shl->Opcode() == Op_LShiftI ) { 2575 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2576 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2577 set_req(MemNode::ValueIn, shl->in(1)); 2578 return this; 2579 } 2580 } 2581 } 2582 } 2583 return NULL; 2584} 2585 2586//------------------------------value_never_loaded----------------------------------- 2587// Determine whether there are any possible loads of the value stored. 2588// For simplicity, we actually check if there are any loads from the 2589// address stored to, not just for loads of the value stored by this node. 2590// 2591bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2592 Node *adr = in(Address); 2593 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2594 if (adr_oop == NULL) 2595 return false; 2596 if (!adr_oop->is_known_instance_field()) 2597 return false; // if not a distinct instance, there may be aliases of the address 2598 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2599 Node *use = adr->fast_out(i); 2600 if (use->is_Load() || use->is_LoadStore()) { 2601 return false; 2602 } 2603 } 2604 return true; 2605} 2606 2607//============================================================================= 2608//------------------------------Ideal------------------------------------------ 2609// If the store is from an AND mask that leaves the low bits untouched, then 2610// we can skip the AND operation. If the store is from a sign-extension 2611// (a left shift, then right shift) we can skip both. 2612Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2613 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2614 if( progress != NULL ) return progress; 2615 2616 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2617 if( progress != NULL ) return progress; 2618 2619 // Finally check the default case 2620 return StoreNode::Ideal(phase, can_reshape); 2621} 2622 2623//============================================================================= 2624//------------------------------Ideal------------------------------------------ 2625// If the store is from an AND mask that leaves the low bits untouched, then 2626// we can skip the AND operation 2627Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2628 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2629 if( progress != NULL ) return progress; 2630 2631 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2632 if( progress != NULL ) return progress; 2633 2634 // Finally check the default case 2635 return StoreNode::Ideal(phase, can_reshape); 2636} 2637 2638//============================================================================= 2639//------------------------------Identity--------------------------------------- 2640Node* StoreCMNode::Identity(PhaseGVN* phase) { 2641 // No need to card mark when storing a null ptr 2642 Node* my_store = in(MemNode::OopStore); 2643 if (my_store->is_Store()) { 2644 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2645 if( t1 == TypePtr::NULL_PTR ) { 2646 return in(MemNode::Memory); 2647 } 2648 } 2649 return this; 2650} 2651 2652//============================================================================= 2653//------------------------------Ideal--------------------------------------- 2654Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2655 Node* progress = StoreNode::Ideal(phase, can_reshape); 2656 if (progress != NULL) return progress; 2657 2658 Node* my_store = in(MemNode::OopStore); 2659 if (my_store->is_MergeMem()) { 2660 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2661 set_req(MemNode::OopStore, mem); 2662 return this; 2663 } 2664 2665 return NULL; 2666} 2667 2668//------------------------------Value----------------------------------------- 2669const Type* StoreCMNode::Value(PhaseGVN* phase) const { 2670 // Either input is TOP ==> the result is TOP 2671 const Type *t = phase->type( in(MemNode::Memory) ); 2672 if( t == Type::TOP ) return Type::TOP; 2673 t = phase->type( in(MemNode::Address) ); 2674 if( t == Type::TOP ) return Type::TOP; 2675 t = phase->type( in(MemNode::ValueIn) ); 2676 if( t == Type::TOP ) return Type::TOP; 2677 // If extra input is TOP ==> the result is TOP 2678 t = phase->type( in(MemNode::OopStore) ); 2679 if( t == Type::TOP ) return Type::TOP; 2680 2681 return StoreNode::Value( phase ); 2682} 2683 2684 2685//============================================================================= 2686//----------------------------------SCMemProjNode------------------------------ 2687const Type* SCMemProjNode::Value(PhaseGVN* phase) const 2688{ 2689 return bottom_type(); 2690} 2691 2692//============================================================================= 2693//----------------------------------LoadStoreNode------------------------------ 2694LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2695 : Node(required), 2696 _type(rt), 2697 _adr_type(at) 2698{ 2699 init_req(MemNode::Control, c ); 2700 init_req(MemNode::Memory , mem); 2701 init_req(MemNode::Address, adr); 2702 init_req(MemNode::ValueIn, val); 2703 init_class_id(Class_LoadStore); 2704} 2705 2706uint LoadStoreNode::ideal_reg() const { 2707 return _type->ideal_reg(); 2708} 2709 2710bool LoadStoreNode::result_not_used() const { 2711 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2712 Node *x = fast_out(i); 2713 if (x->Opcode() == Op_SCMemProj) continue; 2714 return false; 2715 } 2716 return true; 2717} 2718 2719uint LoadStoreNode::size_of() const { return sizeof(*this); } 2720 2721//============================================================================= 2722//----------------------------------LoadStoreConditionalNode-------------------- 2723LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 2724 init_req(ExpectedIn, ex ); 2725} 2726 2727//============================================================================= 2728//-------------------------------adr_type-------------------------------------- 2729const TypePtr* ClearArrayNode::adr_type() const { 2730 Node *adr = in(3); 2731 if (adr == NULL) return NULL; // node is dead 2732 return MemNode::calculate_adr_type(adr->bottom_type()); 2733} 2734 2735//------------------------------match_edge------------------------------------- 2736// Do we Match on this edge index or not? Do not match memory 2737uint ClearArrayNode::match_edge(uint idx) const { 2738 return idx > 1; 2739} 2740 2741//------------------------------Identity--------------------------------------- 2742// Clearing a zero length array does nothing 2743Node* ClearArrayNode::Identity(PhaseGVN* phase) { 2744 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2745} 2746 2747//------------------------------Idealize--------------------------------------- 2748// Clearing a short array is faster with stores 2749Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2750 // Already know this is a large node, do not try to ideal it 2751 if (!IdealizeClearArrayNode || _is_large) return NULL; 2752 2753 const int unit = BytesPerLong; 2754 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2755 if (!t) return NULL; 2756 if (!t->is_con()) return NULL; 2757 intptr_t raw_count = t->get_con(); 2758 intptr_t size = raw_count; 2759 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2760 // Clearing nothing uses the Identity call. 2761 // Negative clears are possible on dead ClearArrays 2762 // (see jck test stmt114.stmt11402.val). 2763 if (size <= 0 || size % unit != 0) return NULL; 2764 intptr_t count = size / unit; 2765 // Length too long; communicate this to matchers and assemblers. 2766 // Assemblers are responsible to produce fast hardware clears for it. 2767 if (size > InitArrayShortSize) { 2768 return new ClearArrayNode(in(0), in(1), in(2), in(3), true); 2769 } 2770 Node *mem = in(1); 2771 if( phase->type(mem)==Type::TOP ) return NULL; 2772 Node *adr = in(3); 2773 const Type* at = phase->type(adr); 2774 if( at==Type::TOP ) return NULL; 2775 const TypePtr* atp = at->isa_ptr(); 2776 // adjust atp to be the correct array element address type 2777 if (atp == NULL) atp = TypePtr::BOTTOM; 2778 else atp = atp->add_offset(Type::OffsetBot); 2779 // Get base for derived pointer purposes 2780 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2781 Node *base = adr->in(1); 2782 2783 Node *zero = phase->makecon(TypeLong::ZERO); 2784 Node *off = phase->MakeConX(BytesPerLong); 2785 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2786 count--; 2787 while( count-- ) { 2788 mem = phase->transform(mem); 2789 adr = phase->transform(new AddPNode(base,adr,off)); 2790 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2791 } 2792 return mem; 2793} 2794 2795//----------------------------step_through---------------------------------- 2796// Return allocation input memory edge if it is different instance 2797// or itself if it is the one we are looking for. 2798bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2799 Node* n = *np; 2800 assert(n->is_ClearArray(), "sanity"); 2801 intptr_t offset; 2802 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2803 // This method is called only before Allocate nodes are expanded 2804 // during macro nodes expansion. Before that ClearArray nodes are 2805 // only generated in PhaseMacroExpand::generate_arraycopy() (before 2806 // Allocate nodes are expanded) which follows allocations. 2807 assert(alloc != NULL, "should have allocation"); 2808 if (alloc->_idx == instance_id) { 2809 // Can not bypass initialization of the instance we are looking for. 2810 return false; 2811 } 2812 // Otherwise skip it. 2813 InitializeNode* init = alloc->initialization(); 2814 if (init != NULL) 2815 *np = init->in(TypeFunc::Memory); 2816 else 2817 *np = alloc->in(TypeFunc::Memory); 2818 return true; 2819} 2820 2821//----------------------------clear_memory------------------------------------- 2822// Generate code to initialize object storage to zero. 2823Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2824 intptr_t start_offset, 2825 Node* end_offset, 2826 PhaseGVN* phase) { 2827 intptr_t offset = start_offset; 2828 2829 int unit = BytesPerLong; 2830 if ((offset % unit) != 0) { 2831 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 2832 adr = phase->transform(adr); 2833 const TypePtr* atp = TypeRawPtr::BOTTOM; 2834 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2835 mem = phase->transform(mem); 2836 offset += BytesPerInt; 2837 } 2838 assert((offset % unit) == 0, ""); 2839 2840 // Initialize the remaining stuff, if any, with a ClearArray. 2841 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2842} 2843 2844Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2845 Node* start_offset, 2846 Node* end_offset, 2847 PhaseGVN* phase) { 2848 if (start_offset == end_offset) { 2849 // nothing to do 2850 return mem; 2851 } 2852 2853 int unit = BytesPerLong; 2854 Node* zbase = start_offset; 2855 Node* zend = end_offset; 2856 2857 // Scale to the unit required by the CPU: 2858 if (!Matcher::init_array_count_is_in_bytes) { 2859 Node* shift = phase->intcon(exact_log2(unit)); 2860 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 2861 zend = phase->transform(new URShiftXNode(zend, shift) ); 2862 } 2863 2864 // Bulk clear double-words 2865 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 2866 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 2867 mem = new ClearArrayNode(ctl, mem, zsize, adr, false); 2868 return phase->transform(mem); 2869} 2870 2871Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2872 intptr_t start_offset, 2873 intptr_t end_offset, 2874 PhaseGVN* phase) { 2875 if (start_offset == end_offset) { 2876 // nothing to do 2877 return mem; 2878 } 2879 2880 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2881 intptr_t done_offset = end_offset; 2882 if ((done_offset % BytesPerLong) != 0) { 2883 done_offset -= BytesPerInt; 2884 } 2885 if (done_offset > start_offset) { 2886 mem = clear_memory(ctl, mem, dest, 2887 start_offset, phase->MakeConX(done_offset), phase); 2888 } 2889 if (done_offset < end_offset) { // emit the final 32-bit store 2890 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 2891 adr = phase->transform(adr); 2892 const TypePtr* atp = TypeRawPtr::BOTTOM; 2893 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2894 mem = phase->transform(mem); 2895 done_offset += BytesPerInt; 2896 } 2897 assert(done_offset == end_offset, ""); 2898 return mem; 2899} 2900 2901//============================================================================= 2902MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2903 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2904 _adr_type(C->get_adr_type(alias_idx)) 2905{ 2906 init_class_id(Class_MemBar); 2907 Node* top = C->top(); 2908 init_req(TypeFunc::I_O,top); 2909 init_req(TypeFunc::FramePtr,top); 2910 init_req(TypeFunc::ReturnAdr,top); 2911 if (precedent != NULL) 2912 init_req(TypeFunc::Parms, precedent); 2913} 2914 2915//------------------------------cmp-------------------------------------------- 2916uint MemBarNode::hash() const { return NO_HASH; } 2917uint MemBarNode::cmp( const Node &n ) const { 2918 return (&n == this); // Always fail except on self 2919} 2920 2921//------------------------------make------------------------------------------- 2922MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2923 switch (opcode) { 2924 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 2925 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 2926 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 2927 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 2928 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 2929 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 2930 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 2931 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 2932 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn); 2933 case Op_Initialize: return new InitializeNode(C, atp, pn); 2934 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 2935 default: ShouldNotReachHere(); return NULL; 2936 } 2937} 2938 2939//------------------------------Ideal------------------------------------------ 2940// Return a node which is more "ideal" than the current node. Strip out 2941// control copies 2942Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2943 if (remove_dead_region(phase, can_reshape)) return this; 2944 // Don't bother trying to transform a dead node 2945 if (in(0) && in(0)->is_top()) { 2946 return NULL; 2947 } 2948 2949 bool progress = false; 2950 // Eliminate volatile MemBars for scalar replaced objects. 2951 if (can_reshape && req() == (Precedent+1)) { 2952 bool eliminate = false; 2953 int opc = Opcode(); 2954 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 2955 // Volatile field loads and stores. 2956 Node* my_mem = in(MemBarNode::Precedent); 2957 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 2958 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 2959 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 2960 // replace this Precedent (decodeN) with the Load instead. 2961 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 2962 Node* load_node = my_mem->in(1); 2963 set_req(MemBarNode::Precedent, load_node); 2964 phase->is_IterGVN()->_worklist.push(my_mem); 2965 my_mem = load_node; 2966 } else { 2967 assert(my_mem->unique_out() == this, "sanity"); 2968 del_req(Precedent); 2969 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 2970 my_mem = NULL; 2971 } 2972 progress = true; 2973 } 2974 if (my_mem != NULL && my_mem->is_Mem()) { 2975 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 2976 // Check for scalar replaced object reference. 2977 if( t_oop != NULL && t_oop->is_known_instance_field() && 2978 t_oop->offset() != Type::OffsetBot && 2979 t_oop->offset() != Type::OffsetTop) { 2980 eliminate = true; 2981 } 2982 } 2983 } else if (opc == Op_MemBarRelease) { 2984 // Final field stores. 2985 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 2986 if ((alloc != NULL) && alloc->is_Allocate() && 2987 alloc->as_Allocate()->does_not_escape_thread()) { 2988 // The allocated object does not escape. 2989 eliminate = true; 2990 } 2991 } 2992 if (eliminate) { 2993 // Replace MemBar projections by its inputs. 2994 PhaseIterGVN* igvn = phase->is_IterGVN(); 2995 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 2996 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 2997 // Must return either the original node (now dead) or a new node 2998 // (Do not return a top here, since that would break the uniqueness of top.) 2999 return new ConINode(TypeInt::ZERO); 3000 } 3001 } 3002 return progress ? this : NULL; 3003} 3004 3005//------------------------------Value------------------------------------------ 3006const Type* MemBarNode::Value(PhaseGVN* phase) const { 3007 if( !in(0) ) return Type::TOP; 3008 if( phase->type(in(0)) == Type::TOP ) 3009 return Type::TOP; 3010 return TypeTuple::MEMBAR; 3011} 3012 3013//------------------------------match------------------------------------------ 3014// Construct projections for memory. 3015Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3016 switch (proj->_con) { 3017 case TypeFunc::Control: 3018 case TypeFunc::Memory: 3019 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3020 } 3021 ShouldNotReachHere(); 3022 return NULL; 3023} 3024 3025//===========================InitializeNode==================================== 3026// SUMMARY: 3027// This node acts as a memory barrier on raw memory, after some raw stores. 3028// The 'cooked' oop value feeds from the Initialize, not the Allocation. 3029// The Initialize can 'capture' suitably constrained stores as raw inits. 3030// It can coalesce related raw stores into larger units (called 'tiles'). 3031// It can avoid zeroing new storage for memory units which have raw inits. 3032// At macro-expansion, it is marked 'complete', and does not optimize further. 3033// 3034// EXAMPLE: 3035// The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3036// ctl = incoming control; mem* = incoming memory 3037// (Note: A star * on a memory edge denotes I/O and other standard edges.) 3038// First allocate uninitialized memory and fill in the header: 3039// alloc = (Allocate ctl mem* 16 #short[].klass ...) 3040// ctl := alloc.Control; mem* := alloc.Memory* 3041// rawmem = alloc.Memory; rawoop = alloc.RawAddress 3042// Then initialize to zero the non-header parts of the raw memory block: 3043// init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3044// ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3045// After the initialize node executes, the object is ready for service: 3046// oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3047// Suppose its body is immediately initialized as {1,2}: 3048// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3049// store2 = (StoreC init.Control store1 (+ oop 14) 2) 3050// mem.SLICE(#short[*]) := store2 3051// 3052// DETAILS: 3053// An InitializeNode collects and isolates object initialization after 3054// an AllocateNode and before the next possible safepoint. As a 3055// memory barrier (MemBarNode), it keeps critical stores from drifting 3056// down past any safepoint or any publication of the allocation. 3057// Before this barrier, a newly-allocated object may have uninitialized bits. 3058// After this barrier, it may be treated as a real oop, and GC is allowed. 3059// 3060// The semantics of the InitializeNode include an implicit zeroing of 3061// the new object from object header to the end of the object. 3062// (The object header and end are determined by the AllocateNode.) 3063// 3064// Certain stores may be added as direct inputs to the InitializeNode. 3065// These stores must update raw memory, and they must be to addresses 3066// derived from the raw address produced by AllocateNode, and with 3067// a constant offset. They must be ordered by increasing offset. 3068// The first one is at in(RawStores), the last at in(req()-1). 3069// Unlike most memory operations, they are not linked in a chain, 3070// but are displayed in parallel as users of the rawmem output of 3071// the allocation. 3072// 3073// (See comments in InitializeNode::capture_store, which continue 3074// the example given above.) 3075// 3076// When the associated Allocate is macro-expanded, the InitializeNode 3077// may be rewritten to optimize collected stores. A ClearArrayNode 3078// may also be created at that point to represent any required zeroing. 3079// The InitializeNode is then marked 'complete', prohibiting further 3080// capturing of nearby memory operations. 3081// 3082// During macro-expansion, all captured initializations which store 3083// constant values of 32 bits or smaller are coalesced (if advantageous) 3084// into larger 'tiles' 32 or 64 bits. This allows an object to be 3085// initialized in fewer memory operations. Memory words which are 3086// covered by neither tiles nor non-constant stores are pre-zeroed 3087// by explicit stores of zero. (The code shape happens to do all 3088// zeroing first, then all other stores, with both sequences occurring 3089// in order of ascending offsets.) 3090// 3091// Alternatively, code may be inserted between an AllocateNode and its 3092// InitializeNode, to perform arbitrary initialization of the new object. 3093// E.g., the object copying intrinsics insert complex data transfers here. 3094// The initialization must then be marked as 'complete' disable the 3095// built-in zeroing semantics and the collection of initializing stores. 3096// 3097// While an InitializeNode is incomplete, reads from the memory state 3098// produced by it are optimizable if they match the control edge and 3099// new oop address associated with the allocation/initialization. 3100// They return a stored value (if the offset matches) or else zero. 3101// A write to the memory state, if it matches control and address, 3102// and if it is to a constant offset, may be 'captured' by the 3103// InitializeNode. It is cloned as a raw memory operation and rewired 3104// inside the initialization, to the raw oop produced by the allocation. 3105// Operations on addresses which are provably distinct (e.g., to 3106// other AllocateNodes) are allowed to bypass the initialization. 3107// 3108// The effect of all this is to consolidate object initialization 3109// (both arrays and non-arrays, both piecewise and bulk) into a 3110// single location, where it can be optimized as a unit. 3111// 3112// Only stores with an offset less than TrackedInitializationLimit words 3113// will be considered for capture by an InitializeNode. This puts a 3114// reasonable limit on the complexity of optimized initializations. 3115 3116//---------------------------InitializeNode------------------------------------ 3117InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3118 : _is_complete(Incomplete), _does_not_escape(false), 3119 MemBarNode(C, adr_type, rawoop) 3120{ 3121 init_class_id(Class_Initialize); 3122 3123 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3124 assert(in(RawAddress) == rawoop, "proper init"); 3125 // Note: allocation() can be NULL, for secondary initialization barriers 3126} 3127 3128// Since this node is not matched, it will be processed by the 3129// register allocator. Declare that there are no constraints 3130// on the allocation of the RawAddress edge. 3131const RegMask &InitializeNode::in_RegMask(uint idx) const { 3132 // This edge should be set to top, by the set_complete. But be conservative. 3133 if (idx == InitializeNode::RawAddress) 3134 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3135 return RegMask::Empty; 3136} 3137 3138Node* InitializeNode::memory(uint alias_idx) { 3139 Node* mem = in(Memory); 3140 if (mem->is_MergeMem()) { 3141 return mem->as_MergeMem()->memory_at(alias_idx); 3142 } else { 3143 // incoming raw memory is not split 3144 return mem; 3145 } 3146} 3147 3148bool InitializeNode::is_non_zero() { 3149 if (is_complete()) return false; 3150 remove_extra_zeroes(); 3151 return (req() > RawStores); 3152} 3153 3154void InitializeNode::set_complete(PhaseGVN* phase) { 3155 assert(!is_complete(), "caller responsibility"); 3156 _is_complete = Complete; 3157 3158 // After this node is complete, it contains a bunch of 3159 // raw-memory initializations. There is no need for 3160 // it to have anything to do with non-raw memory effects. 3161 // Therefore, tell all non-raw users to re-optimize themselves, 3162 // after skipping the memory effects of this initialization. 3163 PhaseIterGVN* igvn = phase->is_IterGVN(); 3164 if (igvn) igvn->add_users_to_worklist(this); 3165} 3166 3167// convenience function 3168// return false if the init contains any stores already 3169bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3170 InitializeNode* init = initialization(); 3171 if (init == NULL || init->is_complete()) return false; 3172 init->remove_extra_zeroes(); 3173 // for now, if this allocation has already collected any inits, bail: 3174 if (init->is_non_zero()) return false; 3175 init->set_complete(phase); 3176 return true; 3177} 3178 3179void InitializeNode::remove_extra_zeroes() { 3180 if (req() == RawStores) return; 3181 Node* zmem = zero_memory(); 3182 uint fill = RawStores; 3183 for (uint i = fill; i < req(); i++) { 3184 Node* n = in(i); 3185 if (n->is_top() || n == zmem) continue; // skip 3186 if (fill < i) set_req(fill, n); // compact 3187 ++fill; 3188 } 3189 // delete any empty spaces created: 3190 while (fill < req()) { 3191 del_req(fill); 3192 } 3193} 3194 3195// Helper for remembering which stores go with which offsets. 3196intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3197 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3198 intptr_t offset = -1; 3199 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3200 phase, offset); 3201 if (base == NULL) return -1; // something is dead, 3202 if (offset < 0) return -1; // dead, dead 3203 return offset; 3204} 3205 3206// Helper for proving that an initialization expression is 3207// "simple enough" to be folded into an object initialization. 3208// Attempts to prove that a store's initial value 'n' can be captured 3209// within the initialization without creating a vicious cycle, such as: 3210// { Foo p = new Foo(); p.next = p; } 3211// True for constants and parameters and small combinations thereof. 3212bool InitializeNode::detect_init_independence(Node* n, int& count) { 3213 if (n == NULL) return true; // (can this really happen?) 3214 if (n->is_Proj()) n = n->in(0); 3215 if (n == this) return false; // found a cycle 3216 if (n->is_Con()) return true; 3217 if (n->is_Start()) return true; // params, etc., are OK 3218 if (n->is_Root()) return true; // even better 3219 3220 Node* ctl = n->in(0); 3221 if (ctl != NULL && !ctl->is_top()) { 3222 if (ctl->is_Proj()) ctl = ctl->in(0); 3223 if (ctl == this) return false; 3224 3225 // If we already know that the enclosing memory op is pinned right after 3226 // the init, then any control flow that the store has picked up 3227 // must have preceded the init, or else be equal to the init. 3228 // Even after loop optimizations (which might change control edges) 3229 // a store is never pinned *before* the availability of its inputs. 3230 if (!MemNode::all_controls_dominate(n, this)) 3231 return false; // failed to prove a good control 3232 } 3233 3234 // Check data edges for possible dependencies on 'this'. 3235 if ((count += 1) > 20) return false; // complexity limit 3236 for (uint i = 1; i < n->req(); i++) { 3237 Node* m = n->in(i); 3238 if (m == NULL || m == n || m->is_top()) continue; 3239 uint first_i = n->find_edge(m); 3240 if (i != first_i) continue; // process duplicate edge just once 3241 if (!detect_init_independence(m, count)) { 3242 return false; 3243 } 3244 } 3245 3246 return true; 3247} 3248 3249// Here are all the checks a Store must pass before it can be moved into 3250// an initialization. Returns zero if a check fails. 3251// On success, returns the (constant) offset to which the store applies, 3252// within the initialized memory. 3253intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) { 3254 const int FAIL = 0; 3255 if (st->is_unaligned_access()) { 3256 return FAIL; 3257 } 3258 if (st->req() != MemNode::ValueIn + 1) 3259 return FAIL; // an inscrutable StoreNode (card mark?) 3260 Node* ctl = st->in(MemNode::Control); 3261 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3262 return FAIL; // must be unconditional after the initialization 3263 Node* mem = st->in(MemNode::Memory); 3264 if (!(mem->is_Proj() && mem->in(0) == this)) 3265 return FAIL; // must not be preceded by other stores 3266 Node* adr = st->in(MemNode::Address); 3267 intptr_t offset; 3268 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3269 if (alloc == NULL) 3270 return FAIL; // inscrutable address 3271 if (alloc != allocation()) 3272 return FAIL; // wrong allocation! (store needs to float up) 3273 Node* val = st->in(MemNode::ValueIn); 3274 int complexity_count = 0; 3275 if (!detect_init_independence(val, complexity_count)) 3276 return FAIL; // stored value must be 'simple enough' 3277 3278 // The Store can be captured only if nothing after the allocation 3279 // and before the Store is using the memory location that the store 3280 // overwrites. 3281 bool failed = false; 3282 // If is_complete_with_arraycopy() is true the shape of the graph is 3283 // well defined and is safe so no need for extra checks. 3284 if (!is_complete_with_arraycopy()) { 3285 // We are going to look at each use of the memory state following 3286 // the allocation to make sure nothing reads the memory that the 3287 // Store writes. 3288 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3289 int alias_idx = phase->C->get_alias_index(t_adr); 3290 ResourceMark rm; 3291 Unique_Node_List mems; 3292 mems.push(mem); 3293 Node* unique_merge = NULL; 3294 for (uint next = 0; next < mems.size(); ++next) { 3295 Node *m = mems.at(next); 3296 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3297 Node *n = m->fast_out(j); 3298 if (n->outcnt() == 0) { 3299 continue; 3300 } 3301 if (n == st) { 3302 continue; 3303 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3304 // If the control of this use is different from the control 3305 // of the Store which is right after the InitializeNode then 3306 // this node cannot be between the InitializeNode and the 3307 // Store. 3308 continue; 3309 } else if (n->is_MergeMem()) { 3310 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3311 // We can hit a MergeMemNode (that will likely go away 3312 // later) that is a direct use of the memory state 3313 // following the InitializeNode on the same slice as the 3314 // store node that we'd like to capture. We need to check 3315 // the uses of the MergeMemNode. 3316 mems.push(n); 3317 } 3318 } else if (n->is_Mem()) { 3319 Node* other_adr = n->in(MemNode::Address); 3320 if (other_adr == adr) { 3321 failed = true; 3322 break; 3323 } else { 3324 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3325 if (other_t_adr != NULL) { 3326 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3327 if (other_alias_idx == alias_idx) { 3328 // A load from the same memory slice as the store right 3329 // after the InitializeNode. We check the control of the 3330 // object/array that is loaded from. If it's the same as 3331 // the store control then we cannot capture the store. 3332 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3333 Node* base = other_adr; 3334 assert(base->is_AddP(), "should be addp but is %s", base->Name()); 3335 base = base->in(AddPNode::Base); 3336 if (base != NULL) { 3337 base = base->uncast(); 3338 if (base->is_Proj() && base->in(0) == alloc) { 3339 failed = true; 3340 break; 3341 } 3342 } 3343 } 3344 } 3345 } 3346 } else { 3347 failed = true; 3348 break; 3349 } 3350 } 3351 } 3352 } 3353 if (failed) { 3354 if (!can_reshape) { 3355 // We decided we couldn't capture the store during parsing. We 3356 // should try again during the next IGVN once the graph is 3357 // cleaner. 3358 phase->C->record_for_igvn(st); 3359 } 3360 return FAIL; 3361 } 3362 3363 return offset; // success 3364} 3365 3366// Find the captured store in(i) which corresponds to the range 3367// [start..start+size) in the initialized object. 3368// If there is one, return its index i. If there isn't, return the 3369// negative of the index where it should be inserted. 3370// Return 0 if the queried range overlaps an initialization boundary 3371// or if dead code is encountered. 3372// If size_in_bytes is zero, do not bother with overlap checks. 3373int InitializeNode::captured_store_insertion_point(intptr_t start, 3374 int size_in_bytes, 3375 PhaseTransform* phase) { 3376 const int FAIL = 0, MAX_STORE = BytesPerLong; 3377 3378 if (is_complete()) 3379 return FAIL; // arraycopy got here first; punt 3380 3381 assert(allocation() != NULL, "must be present"); 3382 3383 // no negatives, no header fields: 3384 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3385 3386 // after a certain size, we bail out on tracking all the stores: 3387 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3388 if (start >= ti_limit) return FAIL; 3389 3390 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3391 if (i >= limit) return -(int)i; // not found; here is where to put it 3392 3393 Node* st = in(i); 3394 intptr_t st_off = get_store_offset(st, phase); 3395 if (st_off < 0) { 3396 if (st != zero_memory()) { 3397 return FAIL; // bail out if there is dead garbage 3398 } 3399 } else if (st_off > start) { 3400 // ...we are done, since stores are ordered 3401 if (st_off < start + size_in_bytes) { 3402 return FAIL; // the next store overlaps 3403 } 3404 return -(int)i; // not found; here is where to put it 3405 } else if (st_off < start) { 3406 if (size_in_bytes != 0 && 3407 start < st_off + MAX_STORE && 3408 start < st_off + st->as_Store()->memory_size()) { 3409 return FAIL; // the previous store overlaps 3410 } 3411 } else { 3412 if (size_in_bytes != 0 && 3413 st->as_Store()->memory_size() != size_in_bytes) { 3414 return FAIL; // mismatched store size 3415 } 3416 return i; 3417 } 3418 3419 ++i; 3420 } 3421} 3422 3423// Look for a captured store which initializes at the offset 'start' 3424// with the given size. If there is no such store, and no other 3425// initialization interferes, then return zero_memory (the memory 3426// projection of the AllocateNode). 3427Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3428 PhaseTransform* phase) { 3429 assert(stores_are_sane(phase), ""); 3430 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3431 if (i == 0) { 3432 return NULL; // something is dead 3433 } else if (i < 0) { 3434 return zero_memory(); // just primordial zero bits here 3435 } else { 3436 Node* st = in(i); // here is the store at this position 3437 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3438 return st; 3439 } 3440} 3441 3442// Create, as a raw pointer, an address within my new object at 'offset'. 3443Node* InitializeNode::make_raw_address(intptr_t offset, 3444 PhaseTransform* phase) { 3445 Node* addr = in(RawAddress); 3446 if (offset != 0) { 3447 Compile* C = phase->C; 3448 addr = phase->transform( new AddPNode(C->top(), addr, 3449 phase->MakeConX(offset)) ); 3450 } 3451 return addr; 3452} 3453 3454// Clone the given store, converting it into a raw store 3455// initializing a field or element of my new object. 3456// Caller is responsible for retiring the original store, 3457// with subsume_node or the like. 3458// 3459// From the example above InitializeNode::InitializeNode, 3460// here are the old stores to be captured: 3461// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3462// store2 = (StoreC init.Control store1 (+ oop 14) 2) 3463// 3464// Here is the changed code; note the extra edges on init: 3465// alloc = (Allocate ...) 3466// rawoop = alloc.RawAddress 3467// rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3468// rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3469// init = (Initialize alloc.Control alloc.Memory rawoop 3470// rawstore1 rawstore2) 3471// 3472Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3473 PhaseTransform* phase, bool can_reshape) { 3474 assert(stores_are_sane(phase), ""); 3475 3476 if (start < 0) return NULL; 3477 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3478 3479 Compile* C = phase->C; 3480 int size_in_bytes = st->memory_size(); 3481 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3482 if (i == 0) return NULL; // bail out 3483 Node* prev_mem = NULL; // raw memory for the captured store 3484 if (i > 0) { 3485 prev_mem = in(i); // there is a pre-existing store under this one 3486 set_req(i, C->top()); // temporarily disconnect it 3487 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3488 } else { 3489 i = -i; // no pre-existing store 3490 prev_mem = zero_memory(); // a slice of the newly allocated object 3491 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3492 set_req(--i, C->top()); // reuse this edge; it has been folded away 3493 else 3494 ins_req(i, C->top()); // build a new edge 3495 } 3496 Node* new_st = st->clone(); 3497 new_st->set_req(MemNode::Control, in(Control)); 3498 new_st->set_req(MemNode::Memory, prev_mem); 3499 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3500 new_st = phase->transform(new_st); 3501 3502 // At this point, new_st might have swallowed a pre-existing store 3503 // at the same offset, or perhaps new_st might have disappeared, 3504 // if it redundantly stored the same value (or zero to fresh memory). 3505 3506 // In any case, wire it in: 3507 phase->igvn_rehash_node_delayed(this); 3508 set_req(i, new_st); 3509 3510 // The caller may now kill the old guy. 3511 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3512 assert(check_st == new_st || check_st == NULL, "must be findable"); 3513 assert(!is_complete(), ""); 3514 return new_st; 3515} 3516 3517static bool store_constant(jlong* tiles, int num_tiles, 3518 intptr_t st_off, int st_size, 3519 jlong con) { 3520 if ((st_off & (st_size-1)) != 0) 3521 return false; // strange store offset (assume size==2**N) 3522 address addr = (address)tiles + st_off; 3523 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3524 switch (st_size) { 3525 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3526 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3527 case sizeof(jint): *(jint*) addr = (jint) con; break; 3528 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3529 default: return false; // strange store size (detect size!=2**N here) 3530 } 3531 return true; // return success to caller 3532} 3533 3534// Coalesce subword constants into int constants and possibly 3535// into long constants. The goal, if the CPU permits, 3536// is to initialize the object with a small number of 64-bit tiles. 3537// Also, convert floating-point constants to bit patterns. 3538// Non-constants are not relevant to this pass. 3539// 3540// In terms of the running example on InitializeNode::InitializeNode 3541// and InitializeNode::capture_store, here is the transformation 3542// of rawstore1 and rawstore2 into rawstore12: 3543// alloc = (Allocate ...) 3544// rawoop = alloc.RawAddress 3545// tile12 = 0x00010002 3546// rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3547// init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3548// 3549void 3550InitializeNode::coalesce_subword_stores(intptr_t header_size, 3551 Node* size_in_bytes, 3552 PhaseGVN* phase) { 3553 Compile* C = phase->C; 3554 3555 assert(stores_are_sane(phase), ""); 3556 // Note: After this pass, they are not completely sane, 3557 // since there may be some overlaps. 3558 3559 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3560 3561 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3562 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3563 size_limit = MIN2(size_limit, ti_limit); 3564 size_limit = align_up(size_limit, BytesPerLong); 3565 int num_tiles = size_limit / BytesPerLong; 3566 3567 // allocate space for the tile map: 3568 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3569 jlong tiles_buf[small_len]; 3570 Node* nodes_buf[small_len]; 3571 jlong inits_buf[small_len]; 3572 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3573 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3574 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3575 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3576 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3577 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3578 // tiles: exact bitwise model of all primitive constants 3579 // nodes: last constant-storing node subsumed into the tiles model 3580 // inits: which bytes (in each tile) are touched by any initializations 3581 3582 //// Pass A: Fill in the tile model with any relevant stores. 3583 3584 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3585 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3586 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3587 Node* zmem = zero_memory(); // initially zero memory state 3588 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3589 Node* st = in(i); 3590 intptr_t st_off = get_store_offset(st, phase); 3591 3592 // Figure out the store's offset and constant value: 3593 if (st_off < header_size) continue; //skip (ignore header) 3594 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3595 int st_size = st->as_Store()->memory_size(); 3596 if (st_off + st_size > size_limit) break; 3597 3598 // Record which bytes are touched, whether by constant or not. 3599 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3600 continue; // skip (strange store size) 3601 3602 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3603 if (!val->singleton()) continue; //skip (non-con store) 3604 BasicType type = val->basic_type(); 3605 3606 jlong con = 0; 3607 switch (type) { 3608 case T_INT: con = val->is_int()->get_con(); break; 3609 case T_LONG: con = val->is_long()->get_con(); break; 3610 case T_FLOAT: con = jint_cast(val->getf()); break; 3611 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3612 default: continue; //skip (odd store type) 3613 } 3614 3615 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3616 st->Opcode() == Op_StoreL) { 3617 continue; // This StoreL is already optimal. 3618 } 3619 3620 // Store down the constant. 3621 store_constant(tiles, num_tiles, st_off, st_size, con); 3622 3623 intptr_t j = st_off >> LogBytesPerLong; 3624 3625 if (type == T_INT && st_size == BytesPerInt 3626 && (st_off & BytesPerInt) == BytesPerInt) { 3627 jlong lcon = tiles[j]; 3628 if (!Matcher::isSimpleConstant64(lcon) && 3629 st->Opcode() == Op_StoreI) { 3630 // This StoreI is already optimal by itself. 3631 jint* intcon = (jint*) &tiles[j]; 3632 intcon[1] = 0; // undo the store_constant() 3633 3634 // If the previous store is also optimal by itself, back up and 3635 // undo the action of the previous loop iteration... if we can. 3636 // But if we can't, just let the previous half take care of itself. 3637 st = nodes[j]; 3638 st_off -= BytesPerInt; 3639 con = intcon[0]; 3640 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3641 assert(st_off >= header_size, "still ignoring header"); 3642 assert(get_store_offset(st, phase) == st_off, "must be"); 3643 assert(in(i-1) == zmem, "must be"); 3644 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3645 assert(con == tcon->is_int()->get_con(), "must be"); 3646 // Undo the effects of the previous loop trip, which swallowed st: 3647 intcon[0] = 0; // undo store_constant() 3648 set_req(i-1, st); // undo set_req(i, zmem) 3649 nodes[j] = NULL; // undo nodes[j] = st 3650 --old_subword; // undo ++old_subword 3651 } 3652 continue; // This StoreI is already optimal. 3653 } 3654 } 3655 3656 // This store is not needed. 3657 set_req(i, zmem); 3658 nodes[j] = st; // record for the moment 3659 if (st_size < BytesPerLong) // something has changed 3660 ++old_subword; // includes int/float, but who's counting... 3661 else ++old_long; 3662 } 3663 3664 if ((old_subword + old_long) == 0) 3665 return; // nothing more to do 3666 3667 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3668 // Be sure to insert them before overlapping non-constant stores. 3669 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3670 for (int j = 0; j < num_tiles; j++) { 3671 jlong con = tiles[j]; 3672 jlong init = inits[j]; 3673 if (con == 0) continue; 3674 jint con0, con1; // split the constant, address-wise 3675 jint init0, init1; // split the init map, address-wise 3676 { union { jlong con; jint intcon[2]; } u; 3677 u.con = con; 3678 con0 = u.intcon[0]; 3679 con1 = u.intcon[1]; 3680 u.con = init; 3681 init0 = u.intcon[0]; 3682 init1 = u.intcon[1]; 3683 } 3684 3685 Node* old = nodes[j]; 3686 assert(old != NULL, "need the prior store"); 3687 intptr_t offset = (j * BytesPerLong); 3688 3689 bool split = !Matcher::isSimpleConstant64(con); 3690 3691 if (offset < header_size) { 3692 assert(offset + BytesPerInt >= header_size, "second int counts"); 3693 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3694 split = true; // only the second word counts 3695 // Example: int a[] = { 42 ... } 3696 } else if (con0 == 0 && init0 == -1) { 3697 split = true; // first word is covered by full inits 3698 // Example: int a[] = { ... foo(), 42 ... } 3699 } else if (con1 == 0 && init1 == -1) { 3700 split = true; // second word is covered by full inits 3701 // Example: int a[] = { ... 42, foo() ... } 3702 } 3703 3704 // Here's a case where init0 is neither 0 nor -1: 3705 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3706 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3707 // In this case the tile is not split; it is (jlong)42. 3708 // The big tile is stored down, and then the foo() value is inserted. 3709 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3710 3711 Node* ctl = old->in(MemNode::Control); 3712 Node* adr = make_raw_address(offset, phase); 3713 const TypePtr* atp = TypeRawPtr::BOTTOM; 3714 3715 // One or two coalesced stores to plop down. 3716 Node* st[2]; 3717 intptr_t off[2]; 3718 int nst = 0; 3719 if (!split) { 3720 ++new_long; 3721 off[nst] = offset; 3722 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3723 phase->longcon(con), T_LONG, MemNode::unordered); 3724 } else { 3725 // Omit either if it is a zero. 3726 if (con0 != 0) { 3727 ++new_int; 3728 off[nst] = offset; 3729 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3730 phase->intcon(con0), T_INT, MemNode::unordered); 3731 } 3732 if (con1 != 0) { 3733 ++new_int; 3734 offset += BytesPerInt; 3735 adr = make_raw_address(offset, phase); 3736 off[nst] = offset; 3737 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3738 phase->intcon(con1), T_INT, MemNode::unordered); 3739 } 3740 } 3741 3742 // Insert second store first, then the first before the second. 3743 // Insert each one just before any overlapping non-constant stores. 3744 while (nst > 0) { 3745 Node* st1 = st[--nst]; 3746 C->copy_node_notes_to(st1, old); 3747 st1 = phase->transform(st1); 3748 offset = off[nst]; 3749 assert(offset >= header_size, "do not smash header"); 3750 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3751 guarantee(ins_idx != 0, "must re-insert constant store"); 3752 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3753 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3754 set_req(--ins_idx, st1); 3755 else 3756 ins_req(ins_idx, st1); 3757 } 3758 } 3759 3760 if (PrintCompilation && WizardMode) 3761 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3762 old_subword, old_long, new_int, new_long); 3763 if (C->log() != NULL) 3764 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3765 old_subword, old_long, new_int, new_long); 3766 3767 // Clean up any remaining occurrences of zmem: 3768 remove_extra_zeroes(); 3769} 3770 3771// Explore forward from in(start) to find the first fully initialized 3772// word, and return its offset. Skip groups of subword stores which 3773// together initialize full words. If in(start) is itself part of a 3774// fully initialized word, return the offset of in(start). If there 3775// are no following full-word stores, or if something is fishy, return 3776// a negative value. 3777intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3778 int int_map = 0; 3779 intptr_t int_map_off = 0; 3780 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3781 3782 for (uint i = start, limit = req(); i < limit; i++) { 3783 Node* st = in(i); 3784 3785 intptr_t st_off = get_store_offset(st, phase); 3786 if (st_off < 0) break; // return conservative answer 3787 3788 int st_size = st->as_Store()->memory_size(); 3789 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3790 return st_off; // we found a complete word init 3791 } 3792 3793 // update the map: 3794 3795 intptr_t this_int_off = align_down(st_off, BytesPerInt); 3796 if (this_int_off != int_map_off) { 3797 // reset the map: 3798 int_map = 0; 3799 int_map_off = this_int_off; 3800 } 3801 3802 int subword_off = st_off - this_int_off; 3803 int_map |= right_n_bits(st_size) << subword_off; 3804 if ((int_map & FULL_MAP) == FULL_MAP) { 3805 return this_int_off; // we found a complete word init 3806 } 3807 3808 // Did this store hit or cross the word boundary? 3809 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt); 3810 if (next_int_off == this_int_off + BytesPerInt) { 3811 // We passed the current int, without fully initializing it. 3812 int_map_off = next_int_off; 3813 int_map >>= BytesPerInt; 3814 } else if (next_int_off > this_int_off + BytesPerInt) { 3815 // We passed the current and next int. 3816 return this_int_off + BytesPerInt; 3817 } 3818 } 3819 3820 return -1; 3821} 3822 3823 3824// Called when the associated AllocateNode is expanded into CFG. 3825// At this point, we may perform additional optimizations. 3826// Linearize the stores by ascending offset, to make memory 3827// activity as coherent as possible. 3828Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3829 intptr_t header_size, 3830 Node* size_in_bytes, 3831 PhaseGVN* phase) { 3832 assert(!is_complete(), "not already complete"); 3833 assert(stores_are_sane(phase), ""); 3834 assert(allocation() != NULL, "must be present"); 3835 3836 remove_extra_zeroes(); 3837 3838 if (ReduceFieldZeroing || ReduceBulkZeroing) 3839 // reduce instruction count for common initialization patterns 3840 coalesce_subword_stores(header_size, size_in_bytes, phase); 3841 3842 Node* zmem = zero_memory(); // initially zero memory state 3843 Node* inits = zmem; // accumulating a linearized chain of inits 3844 #ifdef ASSERT 3845 intptr_t first_offset = allocation()->minimum_header_size(); 3846 intptr_t last_init_off = first_offset; // previous init offset 3847 intptr_t last_init_end = first_offset; // previous init offset+size 3848 intptr_t last_tile_end = first_offset; // previous tile offset+size 3849 #endif 3850 intptr_t zeroes_done = header_size; 3851 3852 bool do_zeroing = true; // we might give up if inits are very sparse 3853 int big_init_gaps = 0; // how many large gaps have we seen? 3854 3855 if (UseTLAB && ZeroTLAB) do_zeroing = false; 3856 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3857 3858 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3859 Node* st = in(i); 3860 intptr_t st_off = get_store_offset(st, phase); 3861 if (st_off < 0) 3862 break; // unknown junk in the inits 3863 if (st->in(MemNode::Memory) != zmem) 3864 break; // complicated store chains somehow in list 3865 3866 int st_size = st->as_Store()->memory_size(); 3867 intptr_t next_init_off = st_off + st_size; 3868 3869 if (do_zeroing && zeroes_done < next_init_off) { 3870 // See if this store needs a zero before it or under it. 3871 intptr_t zeroes_needed = st_off; 3872 3873 if (st_size < BytesPerInt) { 3874 // Look for subword stores which only partially initialize words. 3875 // If we find some, we must lay down some word-level zeroes first, 3876 // underneath the subword stores. 3877 // 3878 // Examples: 3879 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3880 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3881 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3882 // 3883 // Note: coalesce_subword_stores may have already done this, 3884 // if it was prompted by constant non-zero subword initializers. 3885 // But this case can still arise with non-constant stores. 3886 3887 intptr_t next_full_store = find_next_fullword_store(i, phase); 3888 3889 // In the examples above: 3890 // in(i) p q r s x y z 3891 // st_off 12 13 14 15 12 13 14 3892 // st_size 1 1 1 1 1 1 1 3893 // next_full_s. 12 16 16 16 16 16 16 3894 // z's_done 12 16 16 16 12 16 12 3895 // z's_needed 12 16 16 16 16 16 16 3896 // zsize 0 0 0 0 4 0 4 3897 if (next_full_store < 0) { 3898 // Conservative tack: Zero to end of current word. 3899 zeroes_needed = align_up(zeroes_needed, BytesPerInt); 3900 } else { 3901 // Zero to beginning of next fully initialized word. 3902 // Or, don't zero at all, if we are already in that word. 3903 assert(next_full_store >= zeroes_needed, "must go forward"); 3904 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3905 zeroes_needed = next_full_store; 3906 } 3907 } 3908 3909 if (zeroes_needed > zeroes_done) { 3910 intptr_t zsize = zeroes_needed - zeroes_done; 3911 // Do some incremental zeroing on rawmem, in parallel with inits. 3912 zeroes_done = align_down(zeroes_done, BytesPerInt); 3913 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3914 zeroes_done, zeroes_needed, 3915 phase); 3916 zeroes_done = zeroes_needed; 3917 if (zsize > InitArrayShortSize && ++big_init_gaps > 2) 3918 do_zeroing = false; // leave the hole, next time 3919 } 3920 } 3921 3922 // Collect the store and move on: 3923 st->set_req(MemNode::Memory, inits); 3924 inits = st; // put it on the linearized chain 3925 set_req(i, zmem); // unhook from previous position 3926 3927 if (zeroes_done == st_off) 3928 zeroes_done = next_init_off; 3929 3930 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3931 3932 #ifdef ASSERT 3933 // Various order invariants. Weaker than stores_are_sane because 3934 // a large constant tile can be filled in by smaller non-constant stores. 3935 assert(st_off >= last_init_off, "inits do not reverse"); 3936 last_init_off = st_off; 3937 const Type* val = NULL; 3938 if (st_size >= BytesPerInt && 3939 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3940 (int)val->basic_type() < (int)T_OBJECT) { 3941 assert(st_off >= last_tile_end, "tiles do not overlap"); 3942 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3943 last_tile_end = MAX2(last_tile_end, next_init_off); 3944 } else { 3945 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong); 3946 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3947 assert(st_off >= last_init_end, "inits do not overlap"); 3948 last_init_end = next_init_off; // it's a non-tile 3949 } 3950 #endif //ASSERT 3951 } 3952 3953 remove_extra_zeroes(); // clear out all the zmems left over 3954 add_req(inits); 3955 3956 if (!(UseTLAB && ZeroTLAB)) { 3957 // If anything remains to be zeroed, zero it all now. 3958 zeroes_done = align_down(zeroes_done, BytesPerInt); 3959 // if it is the last unused 4 bytes of an instance, forget about it 3960 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3961 if (zeroes_done + BytesPerLong >= size_limit) { 3962 AllocateNode* alloc = allocation(); 3963 assert(alloc != NULL, "must be present"); 3964 if (alloc != NULL && alloc->Opcode() == Op_Allocate) { 3965 Node* klass_node = alloc->in(AllocateNode::KlassNode); 3966 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3967 if (zeroes_done == k->layout_helper()) 3968 zeroes_done = size_limit; 3969 } 3970 } 3971 if (zeroes_done < size_limit) { 3972 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3973 zeroes_done, size_in_bytes, phase); 3974 } 3975 } 3976 3977 set_complete(phase); 3978 return rawmem; 3979} 3980 3981 3982#ifdef ASSERT 3983bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3984 if (is_complete()) 3985 return true; // stores could be anything at this point 3986 assert(allocation() != NULL, "must be present"); 3987 intptr_t last_off = allocation()->minimum_header_size(); 3988 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3989 Node* st = in(i); 3990 intptr_t st_off = get_store_offset(st, phase); 3991 if (st_off < 0) continue; // ignore dead garbage 3992 if (last_off > st_off) { 3993 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 3994 this->dump(2); 3995 assert(false, "ascending store offsets"); 3996 return false; 3997 } 3998 last_off = st_off + st->as_Store()->memory_size(); 3999 } 4000 return true; 4001} 4002#endif //ASSERT 4003 4004 4005 4006 4007//============================MergeMemNode===================================== 4008// 4009// SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4010// contributing store or call operations. Each contributor provides the memory 4011// state for a particular "alias type" (see Compile::alias_type). For example, 4012// if a MergeMem has an input X for alias category #6, then any memory reference 4013// to alias category #6 may use X as its memory state input, as an exact equivalent 4014// to using the MergeMem as a whole. 4015// Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4016// 4017// (Here, the <N> notation gives the index of the relevant adr_type.) 4018// 4019// In one special case (and more cases in the future), alias categories overlap. 4020// The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4021// states. Therefore, if a MergeMem has only one contributing input W for Bot, 4022// it is exactly equivalent to that state W: 4023// MergeMem(<Bot>: W) <==> W 4024// 4025// Usually, the merge has more than one input. In that case, where inputs 4026// overlap (i.e., one is Bot), the narrower alias type determines the memory 4027// state for that type, and the wider alias type (Bot) fills in everywhere else: 4028// Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4029// Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4030// 4031// A merge can take a "wide" memory state as one of its narrow inputs. 4032// This simply means that the merge observes out only the relevant parts of 4033// the wide input. That is, wide memory states arriving at narrow merge inputs 4034// are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4035// 4036// These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4037// and that memory slices "leak through": 4038// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4039// 4040// But, in such a cascade, repeated memory slices can "block the leak": 4041// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4042// 4043// In the last example, Y is not part of the combined memory state of the 4044// outermost MergeMem. The system must, of course, prevent unschedulable 4045// memory states from arising, so you can be sure that the state Y is somehow 4046// a precursor to state Y'. 4047// 4048// 4049// REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4050// of each MergeMemNode array are exactly the numerical alias indexes, including 4051// but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4052// Compile::alias_type (and kin) produce and manage these indexes. 4053// 4054// By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4055// (Note that this provides quick access to the top node inside MergeMem methods, 4056// without the need to reach out via TLS to Compile::current.) 4057// 4058// As a consequence of what was just described, a MergeMem that represents a full 4059// memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4060// containing all alias categories. 4061// 4062// MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4063// 4064// All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4065// a memory state for the alias type <N>, or else the top node, meaning that 4066// there is no particular input for that alias type. Note that the length of 4067// a MergeMem is variable, and may be extended at any time to accommodate new 4068// memory states at larger alias indexes. When merges grow, they are of course 4069// filled with "top" in the unused in() positions. 4070// 4071// This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4072// (Top was chosen because it works smoothly with passes like GCM.) 4073// 4074// For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4075// the type of random VM bits like TLS references.) Since it is always the 4076// first non-Bot memory slice, some low-level loops use it to initialize an 4077// index variable: for (i = AliasIdxRaw; i < req(); i++). 4078// 4079// 4080// ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4081// the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4082// the memory state for alias type <N>, or (if there is no particular slice at <N>, 4083// it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4084// or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4085// MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4086// 4087// %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4088// really that different from the other memory inputs. An abbreviation called 4089// "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4090// 4091// 4092// PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4093// partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4094// that "emerges though" the base memory will be marked as excluding the alias types 4095// of the other (narrow-memory) copies which "emerged through" the narrow edges: 4096// 4097// Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4098// ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4099// 4100// This strange "subtraction" effect is necessary to ensure IGVN convergence. 4101// (It is currently unimplemented.) As you can see, the resulting merge is 4102// actually a disjoint union of memory states, rather than an overlay. 4103// 4104 4105//------------------------------MergeMemNode----------------------------------- 4106Node* MergeMemNode::make_empty_memory() { 4107 Node* empty_memory = (Node*) Compile::current()->top(); 4108 assert(empty_memory->is_top(), "correct sentinel identity"); 4109 return empty_memory; 4110} 4111 4112MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4113 init_class_id(Class_MergeMem); 4114 // all inputs are nullified in Node::Node(int) 4115 // set_input(0, NULL); // no control input 4116 4117 // Initialize the edges uniformly to top, for starters. 4118 Node* empty_mem = make_empty_memory(); 4119 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4120 init_req(i,empty_mem); 4121 } 4122 assert(empty_memory() == empty_mem, ""); 4123 4124 if( new_base != NULL && new_base->is_MergeMem() ) { 4125 MergeMemNode* mdef = new_base->as_MergeMem(); 4126 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4127 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4128 mms.set_memory(mms.memory2()); 4129 } 4130 assert(base_memory() == mdef->base_memory(), ""); 4131 } else { 4132 set_base_memory(new_base); 4133 } 4134} 4135 4136// Make a new, untransformed MergeMem with the same base as 'mem'. 4137// If mem is itself a MergeMem, populate the result with the same edges. 4138MergeMemNode* MergeMemNode::make(Node* mem) { 4139 return new MergeMemNode(mem); 4140} 4141 4142//------------------------------cmp-------------------------------------------- 4143uint MergeMemNode::hash() const { return NO_HASH; } 4144uint MergeMemNode::cmp( const Node &n ) const { 4145 return (&n == this); // Always fail except on self 4146} 4147 4148//------------------------------Identity--------------------------------------- 4149Node* MergeMemNode::Identity(PhaseGVN* phase) { 4150 // Identity if this merge point does not record any interesting memory 4151 // disambiguations. 4152 Node* base_mem = base_memory(); 4153 Node* empty_mem = empty_memory(); 4154 if (base_mem != empty_mem) { // Memory path is not dead? 4155 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4156 Node* mem = in(i); 4157 if (mem != empty_mem && mem != base_mem) { 4158 return this; // Many memory splits; no change 4159 } 4160 } 4161 } 4162 return base_mem; // No memory splits; ID on the one true input 4163} 4164 4165//------------------------------Ideal------------------------------------------ 4166// This method is invoked recursively on chains of MergeMem nodes 4167Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4168 // Remove chain'd MergeMems 4169 // 4170 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4171 // relative to the "in(Bot)". Since we are patching both at the same time, 4172 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4173 // but rewrite each "in(i)" relative to the new "in(Bot)". 4174 Node *progress = NULL; 4175 4176 4177 Node* old_base = base_memory(); 4178 Node* empty_mem = empty_memory(); 4179 if (old_base == empty_mem) 4180 return NULL; // Dead memory path. 4181 4182 MergeMemNode* old_mbase; 4183 if (old_base != NULL && old_base->is_MergeMem()) 4184 old_mbase = old_base->as_MergeMem(); 4185 else 4186 old_mbase = NULL; 4187 Node* new_base = old_base; 4188 4189 // simplify stacked MergeMems in base memory 4190 if (old_mbase) new_base = old_mbase->base_memory(); 4191 4192 // the base memory might contribute new slices beyond my req() 4193 if (old_mbase) grow_to_match(old_mbase); 4194 4195 // Look carefully at the base node if it is a phi. 4196 PhiNode* phi_base; 4197 if (new_base != NULL && new_base->is_Phi()) 4198 phi_base = new_base->as_Phi(); 4199 else 4200 phi_base = NULL; 4201 4202 Node* phi_reg = NULL; 4203 uint phi_len = (uint)-1; 4204 if (phi_base != NULL && !phi_base->is_copy()) { 4205 // do not examine phi if degraded to a copy 4206 phi_reg = phi_base->region(); 4207 phi_len = phi_base->req(); 4208 // see if the phi is unfinished 4209 for (uint i = 1; i < phi_len; i++) { 4210 if (phi_base->in(i) == NULL) { 4211 // incomplete phi; do not look at it yet! 4212 phi_reg = NULL; 4213 phi_len = (uint)-1; 4214 break; 4215 } 4216 } 4217 } 4218 4219 // Note: We do not call verify_sparse on entry, because inputs 4220 // can normalize to the base_memory via subsume_node or similar 4221 // mechanisms. This method repairs that damage. 4222 4223 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4224 4225 // Look at each slice. 4226 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4227 Node* old_in = in(i); 4228 // calculate the old memory value 4229 Node* old_mem = old_in; 4230 if (old_mem == empty_mem) old_mem = old_base; 4231 assert(old_mem == memory_at(i), ""); 4232 4233 // maybe update (reslice) the old memory value 4234 4235 // simplify stacked MergeMems 4236 Node* new_mem = old_mem; 4237 MergeMemNode* old_mmem; 4238 if (old_mem != NULL && old_mem->is_MergeMem()) 4239 old_mmem = old_mem->as_MergeMem(); 4240 else 4241 old_mmem = NULL; 4242 if (old_mmem == this) { 4243 // This can happen if loops break up and safepoints disappear. 4244 // A merge of BotPtr (default) with a RawPtr memory derived from a 4245 // safepoint can be rewritten to a merge of the same BotPtr with 4246 // the BotPtr phi coming into the loop. If that phi disappears 4247 // also, we can end up with a self-loop of the mergemem. 4248 // In general, if loops degenerate and memory effects disappear, 4249 // a mergemem can be left looking at itself. This simply means 4250 // that the mergemem's default should be used, since there is 4251 // no longer any apparent effect on this slice. 4252 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4253 // from start. Update the input to TOP. 4254 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4255 } 4256 else if (old_mmem != NULL) { 4257 new_mem = old_mmem->memory_at(i); 4258 } 4259 // else preceding memory was not a MergeMem 4260 4261 // replace equivalent phis (unfortunately, they do not GVN together) 4262 if (new_mem != NULL && new_mem != new_base && 4263 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4264 if (new_mem->is_Phi()) { 4265 PhiNode* phi_mem = new_mem->as_Phi(); 4266 for (uint i = 1; i < phi_len; i++) { 4267 if (phi_base->in(i) != phi_mem->in(i)) { 4268 phi_mem = NULL; 4269 break; 4270 } 4271 } 4272 if (phi_mem != NULL) { 4273 // equivalent phi nodes; revert to the def 4274 new_mem = new_base; 4275 } 4276 } 4277 } 4278 4279 // maybe store down a new value 4280 Node* new_in = new_mem; 4281 if (new_in == new_base) new_in = empty_mem; 4282 4283 if (new_in != old_in) { 4284 // Warning: Do not combine this "if" with the previous "if" 4285 // A memory slice might have be be rewritten even if it is semantically 4286 // unchanged, if the base_memory value has changed. 4287 set_req(i, new_in); 4288 progress = this; // Report progress 4289 } 4290 } 4291 4292 if (new_base != old_base) { 4293 set_req(Compile::AliasIdxBot, new_base); 4294 // Don't use set_base_memory(new_base), because we need to update du. 4295 assert(base_memory() == new_base, ""); 4296 progress = this; 4297 } 4298 4299 if( base_memory() == this ) { 4300 // a self cycle indicates this memory path is dead 4301 set_req(Compile::AliasIdxBot, empty_mem); 4302 } 4303 4304 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4305 // Recursion must occur after the self cycle check above 4306 if( base_memory()->is_MergeMem() ) { 4307 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4308 Node *m = phase->transform(new_mbase); // Rollup any cycles 4309 if( m != NULL && (m->is_top() || 4310 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 4311 // propagate rollup of dead cycle to self 4312 set_req(Compile::AliasIdxBot, empty_mem); 4313 } 4314 } 4315 4316 if( base_memory() == empty_mem ) { 4317 progress = this; 4318 // Cut inputs during Parse phase only. 4319 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4320 if( !can_reshape ) { 4321 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4322 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4323 } 4324 } 4325 } 4326 4327 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4328 // Check if PhiNode::Ideal's "Split phis through memory merges" 4329 // transform should be attempted. Look for this->phi->this cycle. 4330 uint merge_width = req(); 4331 if (merge_width > Compile::AliasIdxRaw) { 4332 PhiNode* phi = base_memory()->as_Phi(); 4333 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4334 if (phi->in(i) == this) { 4335 phase->is_IterGVN()->_worklist.push(phi); 4336 break; 4337 } 4338 } 4339 } 4340 } 4341 4342 assert(progress || verify_sparse(), "please, no dups of base"); 4343 return progress; 4344} 4345 4346//-------------------------set_base_memory------------------------------------- 4347void MergeMemNode::set_base_memory(Node *new_base) { 4348 Node* empty_mem = empty_memory(); 4349 set_req(Compile::AliasIdxBot, new_base); 4350 assert(memory_at(req()) == new_base, "must set default memory"); 4351 // Clear out other occurrences of new_base: 4352 if (new_base != empty_mem) { 4353 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4354 if (in(i) == new_base) set_req(i, empty_mem); 4355 } 4356 } 4357} 4358 4359//------------------------------out_RegMask------------------------------------ 4360const RegMask &MergeMemNode::out_RegMask() const { 4361 return RegMask::Empty; 4362} 4363 4364//------------------------------dump_spec-------------------------------------- 4365#ifndef PRODUCT 4366void MergeMemNode::dump_spec(outputStream *st) const { 4367 st->print(" {"); 4368 Node* base_mem = base_memory(); 4369 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4370 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem; 4371 if (mem == base_mem) { st->print(" -"); continue; } 4372 st->print( " N%d:", mem->_idx ); 4373 Compile::current()->get_adr_type(i)->dump_on(st); 4374 } 4375 st->print(" }"); 4376} 4377#endif // !PRODUCT 4378 4379 4380#ifdef ASSERT 4381static bool might_be_same(Node* a, Node* b) { 4382 if (a == b) return true; 4383 if (!(a->is_Phi() || b->is_Phi())) return false; 4384 // phis shift around during optimization 4385 return true; // pretty stupid... 4386} 4387 4388// verify a narrow slice (either incoming or outgoing) 4389static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4390 if (!VerifyAliases) return; // don't bother to verify unless requested 4391 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 4392 if (Node::in_dump()) return; // muzzle asserts when printing 4393 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4394 assert(n != NULL, ""); 4395 // Elide intervening MergeMem's 4396 while (n->is_MergeMem()) { 4397 n = n->as_MergeMem()->memory_at(alias_idx); 4398 } 4399 Compile* C = Compile::current(); 4400 const TypePtr* n_adr_type = n->adr_type(); 4401 if (n == m->empty_memory()) { 4402 // Implicit copy of base_memory() 4403 } else if (n_adr_type != TypePtr::BOTTOM) { 4404 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4405 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4406 } else { 4407 // A few places like make_runtime_call "know" that VM calls are narrow, 4408 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4409 bool expected_wide_mem = false; 4410 if (n == m->base_memory()) { 4411 expected_wide_mem = true; 4412 } else if (alias_idx == Compile::AliasIdxRaw || 4413 n == m->memory_at(Compile::AliasIdxRaw)) { 4414 expected_wide_mem = true; 4415 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4416 // memory can "leak through" calls on channels that 4417 // are write-once. Allow this also. 4418 expected_wide_mem = true; 4419 } 4420 assert(expected_wide_mem, "expected narrow slice replacement"); 4421 } 4422} 4423#else // !ASSERT 4424#define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4425#endif 4426 4427 4428//-----------------------------memory_at--------------------------------------- 4429Node* MergeMemNode::memory_at(uint alias_idx) const { 4430 assert(alias_idx >= Compile::AliasIdxRaw || 4431 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4432 "must avoid base_memory and AliasIdxTop"); 4433 4434 // Otherwise, it is a narrow slice. 4435 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4436 Compile *C = Compile::current(); 4437 if (is_empty_memory(n)) { 4438 // the array is sparse; empty slots are the "top" node 4439 n = base_memory(); 4440 assert(Node::in_dump() 4441 || n == NULL || n->bottom_type() == Type::TOP 4442 || n->adr_type() == NULL // address is TOP 4443 || n->adr_type() == TypePtr::BOTTOM 4444 || n->adr_type() == TypeRawPtr::BOTTOM 4445 || Compile::current()->AliasLevel() == 0, 4446 "must be a wide memory"); 4447 // AliasLevel == 0 if we are organizing the memory states manually. 4448 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4449 } else { 4450 // make sure the stored slice is sane 4451 #ifdef ASSERT 4452 if (VMError::is_error_reported() || Node::in_dump()) { 4453 } else if (might_be_same(n, base_memory())) { 4454 // Give it a pass: It is a mostly harmless repetition of the base. 4455 // This can arise normally from node subsumption during optimization. 4456 } else { 4457 verify_memory_slice(this, alias_idx, n); 4458 } 4459 #endif 4460 } 4461 return n; 4462} 4463 4464//---------------------------set_memory_at------------------------------------- 4465void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4466 verify_memory_slice(this, alias_idx, n); 4467 Node* empty_mem = empty_memory(); 4468 if (n == base_memory()) n = empty_mem; // collapse default 4469 uint need_req = alias_idx+1; 4470 if (req() < need_req) { 4471 if (n == empty_mem) return; // already the default, so do not grow me 4472 // grow the sparse array 4473 do { 4474 add_req(empty_mem); 4475 } while (req() < need_req); 4476 } 4477 set_req( alias_idx, n ); 4478} 4479 4480 4481 4482//--------------------------iteration_setup------------------------------------ 4483void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4484 if (other != NULL) { 4485 grow_to_match(other); 4486 // invariant: the finite support of mm2 is within mm->req() 4487 #ifdef ASSERT 4488 for (uint i = req(); i < other->req(); i++) { 4489 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4490 } 4491 #endif 4492 } 4493 // Replace spurious copies of base_memory by top. 4494 Node* base_mem = base_memory(); 4495 if (base_mem != NULL && !base_mem->is_top()) { 4496 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4497 if (in(i) == base_mem) 4498 set_req(i, empty_memory()); 4499 } 4500 } 4501} 4502 4503//---------------------------grow_to_match------------------------------------- 4504void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4505 Node* empty_mem = empty_memory(); 4506 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4507 // look for the finite support of the other memory 4508 for (uint i = other->req(); --i >= req(); ) { 4509 if (other->in(i) != empty_mem) { 4510 uint new_len = i+1; 4511 while (req() < new_len) add_req(empty_mem); 4512 break; 4513 } 4514 } 4515} 4516 4517//---------------------------verify_sparse------------------------------------- 4518#ifndef PRODUCT 4519bool MergeMemNode::verify_sparse() const { 4520 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4521 Node* base_mem = base_memory(); 4522 // The following can happen in degenerate cases, since empty==top. 4523 if (is_empty_memory(base_mem)) return true; 4524 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4525 assert(in(i) != NULL, "sane slice"); 4526 if (in(i) == base_mem) return false; // should have been the sentinel value! 4527 } 4528 return true; 4529} 4530 4531bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4532 Node* n; 4533 n = mm->in(idx); 4534 if (mem == n) return true; // might be empty_memory() 4535 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4536 if (mem == n) return true; 4537 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4538 if (mem == n) return true; 4539 if (n == NULL) break; 4540 } 4541 return false; 4542} 4543#endif // !PRODUCT 4544