1 /*
   2  * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "classfile/javaClasses.hpp"
  27 #include "compiler/compileLog.hpp"
  28 #include "gc/shared/barrierSet.hpp"
  29 #include "gc/shared/c2/barrierSetC2.hpp"
  30 #include "gc/shared/tlab_globals.hpp"
  31 #include "memory/allocation.inline.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "oops/objArrayKlass.hpp"
  34 #include "opto/addnode.hpp"
  35 #include "opto/arraycopynode.hpp"
  36 #include "opto/cfgnode.hpp"
  37 #include "opto/regalloc.hpp"
  38 #include "opto/compile.hpp"
  39 #include "opto/connode.hpp"
  40 #include "opto/convertnode.hpp"
  41 #include "opto/loopnode.hpp"
  42 #include "opto/machnode.hpp"
  43 #include "opto/matcher.hpp"
  44 #include "opto/memnode.hpp"
  45 #include "opto/mempointer.hpp"
  46 #include "opto/mulnode.hpp"
  47 #include "opto/narrowptrnode.hpp"
  48 #include "opto/phaseX.hpp"
  49 #include "opto/regmask.hpp"
  50 #include "opto/rootnode.hpp"
  51 #include "opto/traceMergeStoresTag.hpp"
  52 #include "opto/vectornode.hpp"
  53 #include "utilities/align.hpp"
  54 #include "utilities/copy.hpp"
  55 #include "utilities/macros.hpp"
  56 #include "utilities/powerOfTwo.hpp"
  57 #include "utilities/vmError.hpp"
  58 
  59 // Portions of code courtesy of Clifford Click
  60 
  61 // Optimization - Graph Style
  62 
  63 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem,  const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
  64 
  65 //=============================================================================
  66 uint MemNode::size_of() const { return sizeof(*this); }
  67 
  68 const TypePtr *MemNode::adr_type() const {
  69   Node* adr = in(Address);
  70   if (adr == nullptr)  return nullptr; // node is dead
  71   const TypePtr* cross_check = nullptr;
  72   DEBUG_ONLY(cross_check = _adr_type);
  73   return calculate_adr_type(adr->bottom_type(), cross_check);
  74 }
  75 
  76 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
  77   if (adr != nullptr) {
  78     if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
  79       return true;
  80     }
  81   }
  82   return false;
  83 }
  84 
  85 #ifndef PRODUCT
  86 void MemNode::dump_spec(outputStream *st) const {
  87   if (in(Address) == nullptr)  return; // node is dead
  88 #ifndef ASSERT
  89   // fake the missing field
  90   const TypePtr* _adr_type = nullptr;
  91   if (in(Address) != nullptr)
  92     _adr_type = in(Address)->bottom_type()->isa_ptr();
  93 #endif
  94   dump_adr_type(this, _adr_type, st);
  95 
  96   Compile* C = Compile::current();
  97   if (C->alias_type(_adr_type)->is_volatile()) {
  98     st->print(" Volatile!");
  99   }
 100   if (_unaligned_access) {
 101     st->print(" unaligned");
 102   }
 103   if (_mismatched_access) {
 104     st->print(" mismatched");
 105   }
 106   if (_unsafe_access) {
 107     st->print(" unsafe");
 108   }
 109 }
 110 
 111 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
 112   st->print(" @");
 113   if (adr_type == nullptr) {
 114     st->print("null");
 115   } else {
 116     adr_type->dump_on(st);
 117     Compile* C = Compile::current();
 118     Compile::AliasType* atp = nullptr;
 119     if (C->have_alias_type(adr_type))  atp = C->alias_type(adr_type);
 120     if (atp == nullptr)
 121       st->print(", idx=?\?;");
 122     else if (atp->index() == Compile::AliasIdxBot)
 123       st->print(", idx=Bot;");
 124     else if (atp->index() == Compile::AliasIdxTop)
 125       st->print(", idx=Top;");
 126     else if (atp->index() == Compile::AliasIdxRaw)
 127       st->print(", idx=Raw;");
 128     else {
 129       ciField* field = atp->field();
 130       if (field) {
 131         st->print(", name=");
 132         field->print_name_on(st);
 133       }
 134       st->print(", idx=%d;", atp->index());
 135     }
 136   }
 137 }
 138 
 139 extern void print_alias_types();
 140 
 141 #endif
 142 
 143 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
 144   assert((t_oop != nullptr), "sanity");
 145   bool is_instance = t_oop->is_known_instance_field();
 146   bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
 147                              (load != nullptr) && load->is_Load() &&
 148                              (phase->is_IterGVN() != nullptr);
 149   if (!(is_instance || is_boxed_value_load))
 150     return mchain;  // don't try to optimize non-instance types
 151   uint instance_id = t_oop->instance_id();
 152   Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
 153   Node *prev = nullptr;
 154   Node *result = mchain;
 155   while (prev != result) {
 156     prev = result;
 157     if (result == start_mem)
 158       break;  // hit one of our sentinels
 159     // skip over a call which does not affect this memory slice
 160     if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
 161       Node *proj_in = result->in(0);
 162       if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
 163         break;  // hit one of our sentinels
 164       } else if (proj_in->is_Call()) {
 165         // ArrayCopyNodes processed here as well
 166         CallNode *call = proj_in->as_Call();
 167         if (!call->may_modify(t_oop, phase)) { // returns false for instances
 168           result = call->in(TypeFunc::Memory);
 169         }
 170       } else if (proj_in->is_Initialize()) {
 171         AllocateNode* alloc = proj_in->as_Initialize()->allocation();
 172         // Stop if this is the initialization for the object instance which
 173         // contains this memory slice, otherwise skip over it.
 174         if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
 175           break;
 176         }
 177         if (is_instance) {
 178           result = proj_in->in(TypeFunc::Memory);
 179         } else if (is_boxed_value_load) {
 180           Node* klass = alloc->in(AllocateNode::KlassNode);
 181           const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
 182           if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
 183             result = proj_in->in(TypeFunc::Memory); // not related allocation
 184           }
 185         }
 186       } else if (proj_in->is_MemBar()) {
 187         ArrayCopyNode* ac = nullptr;
 188         if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
 189           break;
 190         }
 191         result = proj_in->in(TypeFunc::Memory);
 192       } else if (proj_in->is_top()) {
 193         break; // dead code
 194       } else {
 195         assert(false, "unexpected projection");
 196       }
 197     } else if (result->is_ClearArray()) {
 198       if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
 199         // Can not bypass initialization of the instance
 200         // we are looking for.
 201         break;
 202       }
 203       // Otherwise skip it (the call updated 'result' value).
 204     } else if (result->is_MergeMem()) {
 205       result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
 206     }
 207   }
 208   return result;
 209 }
 210 
 211 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
 212   const TypeOopPtr* t_oop = t_adr->isa_oopptr();
 213   if (t_oop == nullptr)
 214     return mchain;  // don't try to optimize non-oop types
 215   Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
 216   bool is_instance = t_oop->is_known_instance_field();
 217   PhaseIterGVN *igvn = phase->is_IterGVN();
 218   if (is_instance && igvn != nullptr && result->is_Phi()) {
 219     PhiNode *mphi = result->as_Phi();
 220     assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
 221     const TypePtr *t = mphi->adr_type();
 222     bool do_split = false;
 223     // In the following cases, Load memory input can be further optimized based on
 224     // its precise address type
 225     if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
 226       do_split = true;
 227     } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
 228       const TypeOopPtr* mem_t =
 229         t->is_oopptr()->cast_to_exactness(true)
 230         ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
 231         ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
 232       if (t_oop->isa_aryptr()) {
 233         mem_t = mem_t->is_aryptr()
 234                      ->cast_to_stable(t_oop->is_aryptr()->is_stable())
 235                      ->cast_to_size(t_oop->is_aryptr()->size())
 236                      ->with_offset(t_oop->is_aryptr()->offset())
 237                      ->is_aryptr();
 238       }
 239       do_split = mem_t == t_oop;
 240     }
 241     if (do_split) {
 242       // clone the Phi with our address type
 243       result = mphi->split_out_instance(t_adr, igvn);
 244     } else {
 245       assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
 246     }
 247   }
 248   return result;
 249 }
 250 
 251 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem,  const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
 252   uint alias_idx = phase->C->get_alias_index(tp);
 253   Node *mem = mmem;
 254 #ifdef ASSERT
 255   {
 256     // Check that current type is consistent with the alias index used during graph construction
 257     assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
 258     bool consistent =  adr_check == nullptr || adr_check->empty() ||
 259                        phase->C->must_alias(adr_check, alias_idx );
 260     // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
 261     if( !consistent && adr_check != nullptr && !adr_check->empty() &&
 262                tp->isa_aryptr() &&        tp->offset() == Type::OffsetBot &&
 263         adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
 264         ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
 265           adr_check->offset() == Type::klass_offset() ||
 266           adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
 267       // don't assert if it is dead code.
 268       consistent = true;
 269     }
 270     if( !consistent ) {
 271       st->print("alias_idx==%d, adr_check==", alias_idx);
 272       if( adr_check == nullptr ) {
 273         st->print("null");
 274       } else {
 275         adr_check->dump();
 276       }
 277       st->cr();
 278       print_alias_types();
 279       assert(consistent, "adr_check must match alias idx");
 280     }
 281   }
 282 #endif
 283   // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
 284   // means an array I have not precisely typed yet.  Do not do any
 285   // alias stuff with it any time soon.
 286   const TypeOopPtr *toop = tp->isa_oopptr();
 287   if (tp->base() != Type::AnyPtr &&
 288       !(toop &&
 289         toop->isa_instptr() &&
 290         toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
 291         toop->offset() == Type::OffsetBot)) {
 292     // IGVN _delay_transform may be set to true and if that is the case and mmem
 293     // is already a registered node then the validation inside transform will
 294     // complain.
 295     Node* m = mmem;
 296     PhaseIterGVN* igvn = phase->is_IterGVN();
 297     if (igvn == nullptr || !igvn->delay_transform()) {
 298       // compress paths and change unreachable cycles to TOP
 299       // If not, we can update the input infinitely along a MergeMem cycle
 300       // Equivalent code in PhiNode::Ideal
 301       m = phase->transform(mmem);
 302     }
 303     // If transformed to a MergeMem, get the desired slice
 304     // Otherwise the returned node represents memory for every slice
 305     mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
 306     // Update input if it is progress over what we have now
 307   }
 308   return mem;
 309 }
 310 
 311 //--------------------------Ideal_common---------------------------------------
 312 // Look for degenerate control and memory inputs.  Bypass MergeMem inputs.
 313 // Unhook non-raw memories from complete (macro-expanded) initializations.
 314 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
 315   // If our control input is a dead region, kill all below the region
 316   Node *ctl = in(MemNode::Control);
 317   if (ctl && remove_dead_region(phase, can_reshape))
 318     return this;
 319   ctl = in(MemNode::Control);
 320   // Don't bother trying to transform a dead node
 321   if (ctl && ctl->is_top())  return NodeSentinel;
 322 
 323   PhaseIterGVN *igvn = phase->is_IterGVN();
 324   // Wait if control on the worklist.
 325   if (ctl && can_reshape && igvn != nullptr) {
 326     Node* bol = nullptr;
 327     Node* cmp = nullptr;
 328     if (ctl->in(0)->is_If()) {
 329       assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
 330       bol = ctl->in(0)->in(1);
 331       if (bol->is_Bool())
 332         cmp = ctl->in(0)->in(1)->in(1);
 333     }
 334     if (igvn->_worklist.member(ctl) ||
 335         (bol != nullptr && igvn->_worklist.member(bol)) ||
 336         (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
 337       // This control path may be dead.
 338       // Delay this memory node transformation until the control is processed.
 339       igvn->_worklist.push(this);
 340       return NodeSentinel; // caller will return null
 341     }
 342   }
 343   // Ignore if memory is dead, or self-loop
 344   Node *mem = in(MemNode::Memory);
 345   if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
 346   assert(mem != this, "dead loop in MemNode::Ideal");
 347 
 348   if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
 349     // This memory slice may be dead.
 350     // Delay this mem node transformation until the memory is processed.
 351     igvn->_worklist.push(this);
 352     return NodeSentinel; // caller will return null
 353   }
 354 
 355   Node *address = in(MemNode::Address);
 356   const Type *t_adr = phase->type(address);
 357   if (t_adr == Type::TOP)              return NodeSentinel; // caller will return null
 358 
 359   if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
 360     // Unsafe off-heap access with zero address. Remove access and other control users
 361     // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
 362     assert(ctl != nullptr, "unsafe accesses should be control dependent");
 363     for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
 364       Node* u = ctl->fast_out(i);
 365       if (u != ctl) {
 366         igvn->rehash_node_delayed(u);
 367         int nb = u->replace_edge(ctl, phase->C->top(), igvn);
 368         --i, imax -= nb;
 369       }
 370     }
 371     Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
 372     Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
 373     phase->C->root()->add_req(halt);
 374     return this;
 375   }
 376 
 377   if (can_reshape && igvn != nullptr &&
 378       (igvn->_worklist.member(address) ||
 379        (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
 380     // The address's base and type may change when the address is processed.
 381     // Delay this mem node transformation until the address is processed.
 382     igvn->_worklist.push(this);
 383     return NodeSentinel; // caller will return null
 384   }
 385 
 386   // Do NOT remove or optimize the next lines: ensure a new alias index
 387   // is allocated for an oop pointer type before Escape Analysis.
 388   // Note: C++ will not remove it since the call has side effect.
 389   if (t_adr->isa_oopptr()) {
 390     int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
 391   }
 392 
 393   Node* base = nullptr;
 394   if (address->is_AddP()) {
 395     base = address->in(AddPNode::Base);
 396   }
 397   if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
 398       !t_adr->isa_rawptr()) {
 399     // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
 400     // Skip this node optimization if its address has TOP base.
 401     return NodeSentinel; // caller will return null
 402   }
 403 
 404   // Avoid independent memory operations
 405   Node* old_mem = mem;
 406 
 407   // The code which unhooks non-raw memories from complete (macro-expanded)
 408   // initializations was removed. After macro-expansion all stores caught
 409   // by Initialize node became raw stores and there is no information
 410   // which memory slices they modify. So it is unsafe to move any memory
 411   // operation above these stores. Also in most cases hooked non-raw memories
 412   // were already unhooked by using information from detect_ptr_independence()
 413   // and find_previous_store().
 414 
 415   if (mem->is_MergeMem()) {
 416     MergeMemNode* mmem = mem->as_MergeMem();
 417     const TypePtr *tp = t_adr->is_ptr();
 418 
 419     mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
 420   }
 421 
 422   if (mem != old_mem) {
 423     set_req_X(MemNode::Memory, mem, phase);
 424     if (phase->type(mem) == Type::TOP) return NodeSentinel;
 425     return this;
 426   }
 427 
 428   // let the subclass continue analyzing...
 429   return nullptr;
 430 }
 431 
 432 // Helper function for proving some simple control dominations.
 433 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
 434 // Already assumes that 'dom' is available at 'sub', and that 'sub'
 435 // is not a constant (dominated by the method's StartNode).
 436 // Used by MemNode::find_previous_store to prove that the
 437 // control input of a memory operation predates (dominates)
 438 // an allocation it wants to look past.
 439 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
 440 // dominate 'sub', 'DomResult::NotDominate' if not,
 441 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
 442 // dead code, but at the end of IGVN, we know the definite result
 443 // once the dead code is cleaned up.
 444 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) {
 445   if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
 446     return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 447   }
 448 
 449   // Check 'dom'. Skip Proj and CatchProj nodes.
 450   dom = dom->find_exact_control(dom);
 451   if (dom == nullptr || dom->is_top()) {
 452     return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 453   }
 454 
 455   if (dom == sub) {
 456     // For the case when, for example, 'sub' is Initialize and the original
 457     // 'dom' is Proj node of the 'sub'.
 458     return DomResult::NotDominate;
 459   }
 460 
 461   if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
 462     return DomResult::Dominate;
 463   }
 464 
 465   // 'dom' dominates 'sub' if its control edge and control edges
 466   // of all its inputs dominate or equal to sub's control edge.
 467 
 468   // Currently 'sub' is either Allocate, Initialize or Start nodes.
 469   // Or Region for the check in LoadNode::Ideal();
 470   // 'sub' should have sub->in(0) != nullptr.
 471   assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
 472          sub->is_Region() || sub->is_Call(), "expecting only these nodes");
 473 
 474   // Get control edge of 'sub'.
 475   Node* orig_sub = sub;
 476   sub = sub->find_exact_control(sub->in(0));
 477   if (sub == nullptr || sub->is_top()) {
 478     return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 479   }
 480 
 481   assert(sub->is_CFG(), "expecting control");
 482 
 483   if (sub == dom) {
 484     return DomResult::Dominate;
 485   }
 486 
 487   if (sub->is_Start() || sub->is_Root()) {
 488     return DomResult::NotDominate;
 489   }
 490 
 491   {
 492     // Check all control edges of 'dom'.
 493 
 494     ResourceMark rm;
 495     Node_List nlist;
 496     Unique_Node_List dom_list;
 497 
 498     dom_list.push(dom);
 499     bool only_dominating_controls = false;
 500 
 501     for (uint next = 0; next < dom_list.size(); next++) {
 502       Node* n = dom_list.at(next);
 503       if (n == orig_sub) {
 504         return DomResult::NotDominate; // One of dom's inputs dominated by sub.
 505       }
 506       if (!n->is_CFG() && n->pinned()) {
 507         // Check only own control edge for pinned non-control nodes.
 508         n = n->find_exact_control(n->in(0));
 509         if (n == nullptr || n->is_top()) {
 510           return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 511         }
 512         assert(n->is_CFG(), "expecting control");
 513         dom_list.push(n);
 514       } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
 515         only_dominating_controls = true;
 516       } else if (n->is_CFG()) {
 517         DomResult dom_result = n->dominates(sub, nlist);
 518         if (dom_result == DomResult::Dominate) {
 519           only_dominating_controls = true;
 520         } else {
 521           return dom_result;
 522         }
 523       } else {
 524         // First, own control edge.
 525         Node* m = n->find_exact_control(n->in(0));
 526         if (m != nullptr) {
 527           if (m->is_top()) {
 528             return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 529           }
 530           dom_list.push(m);
 531         }
 532         // Now, the rest of edges.
 533         uint cnt = n->req();
 534         for (uint i = 1; i < cnt; i++) {
 535           m = n->find_exact_control(n->in(i));
 536           if (m == nullptr || m->is_top()) {
 537             continue;
 538           }
 539           dom_list.push(m);
 540         }
 541       }
 542     }
 543     return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
 544   }
 545 }
 546 
 547 //---------------------detect_ptr_independence---------------------------------
 548 // Used by MemNode::find_previous_store to prove that two base
 549 // pointers are never equal.
 550 // The pointers are accompanied by their associated allocations,
 551 // if any, which have been previously discovered by the caller.
 552 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
 553                                       Node* p2, AllocateNode* a2,
 554                                       PhaseTransform* phase) {
 555   // Attempt to prove that these two pointers cannot be aliased.
 556   // They may both manifestly be allocations, and they should differ.
 557   // Or, if they are not both allocations, they can be distinct constants.
 558   // Otherwise, one is an allocation and the other a pre-existing value.
 559   if (a1 == nullptr && a2 == nullptr) {           // neither an allocation
 560     return (p1 != p2) && p1->is_Con() && p2->is_Con();
 561   } else if (a1 != nullptr && a2 != nullptr) {    // both allocations
 562     return (a1 != a2);
 563   } else if (a1 != nullptr) {                  // one allocation a1
 564     // (Note:  p2->is_Con implies p2->in(0)->is_Root, which dominates.)
 565     return all_controls_dominate(p2, a1);
 566   } else { //(a2 != null)                   // one allocation a2
 567     return all_controls_dominate(p1, a2);
 568   }
 569   return false;
 570 }
 571 
 572 
 573 // Find an arraycopy ac that produces the memory state represented by parameter mem.
 574 // Return ac if
 575 // (a) can_see_stored_value=true  and ac must have set the value for this load or if
 576 // (b) can_see_stored_value=false and ac could have set the value for this load or if
 577 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
 578 // In case (c) change the parameter mem to the memory input of ac to skip it
 579 // when searching stored value.
 580 // Otherwise return null.
 581 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
 582   ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
 583   if (ac != nullptr) {
 584     Node* ld_addp = in(MemNode::Address);
 585     Node* src = ac->in(ArrayCopyNode::Src);
 586     const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
 587 
 588     // This is a load from a cloned array. The corresponding arraycopy ac must
 589     // have set the value for the load and we can return ac but only if the load
 590     // is known to be within bounds. This is checked below.
 591     if (ary_t != nullptr && ld_addp->is_AddP()) {
 592       Node* ld_offs = ld_addp->in(AddPNode::Offset);
 593       BasicType ary_elem = ary_t->elem()->array_element_basic_type();
 594       jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
 595       jlong elemsize = type2aelembytes(ary_elem);
 596 
 597       const TypeX*   ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 598       const TypeInt* sizetype  = ary_t->size();
 599 
 600       if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
 601         // The load is known to be within bounds. It receives its value from ac.
 602         return ac;
 603       }
 604       // The load is known to be out-of-bounds.
 605     }
 606     // The load could be out-of-bounds. It must not be hoisted but must remain
 607     // dependent on the runtime range check. This is achieved by returning null.
 608   } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
 609     ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
 610 
 611     if (ac->is_arraycopy_validated() ||
 612         ac->is_copyof_validated() ||
 613         ac->is_copyofrange_validated()) {
 614       Node* ld_addp = in(MemNode::Address);
 615       if (ld_addp->is_AddP()) {
 616         Node* ld_base = ld_addp->in(AddPNode::Address);
 617         Node* ld_offs = ld_addp->in(AddPNode::Offset);
 618 
 619         Node* dest = ac->in(ArrayCopyNode::Dest);
 620 
 621         if (dest == ld_base) {
 622           const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 623           assert(!ld_offs_t->empty(), "dead reference should be checked already");
 624           // Take into account vector or unsafe access size
 625           jlong ld_size_in_bytes = (jlong)memory_size();
 626           jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
 627           offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
 628           if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
 629             return ac;
 630           }
 631           if (!can_see_stored_value) {
 632             mem = ac->in(TypeFunc::Memory);
 633             return ac;
 634           }
 635         }
 636       }
 637     }
 638   }
 639   return nullptr;
 640 }
 641 
 642 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
 643   if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
 644                                                mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
 645     if (ld_alloc != nullptr) {
 646       // Check if there is an array copy for a clone
 647       Node* mb = mem->in(0);
 648       ArrayCopyNode* ac = nullptr;
 649       if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
 650           mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
 651         ac = mb->in(0)->in(0)->as_ArrayCopy();
 652       } else {
 653         // Step over GC barrier when ReduceInitialCardMarks is disabled
 654         BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 655         Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
 656 
 657         if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
 658           ac = control_proj_ac->in(0)->as_ArrayCopy();
 659         }
 660       }
 661 
 662       if (ac != nullptr && ac->is_clonebasic()) {
 663         AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
 664         if (alloc != nullptr && alloc == ld_alloc) {
 665           return ac;
 666         }
 667       }
 668     }
 669   }
 670   return nullptr;
 671 }
 672 
 673 // The logic for reordering loads and stores uses four steps:
 674 // (a) Walk carefully past stores and initializations which we
 675 //     can prove are independent of this load.
 676 // (b) Observe that the next memory state makes an exact match
 677 //     with self (load or store), and locate the relevant store.
 678 // (c) Ensure that, if we were to wire self directly to the store,
 679 //     the optimizer would fold it up somehow.
 680 // (d) Do the rewiring, and return, depending on some other part of
 681 //     the optimizer to fold up the load.
 682 // This routine handles steps (a) and (b).  Steps (c) and (d) are
 683 // specific to loads and stores, so they are handled by the callers.
 684 // (Currently, only LoadNode::Ideal has steps (c), (d).  More later.)
 685 //
 686 Node* MemNode::find_previous_store(PhaseValues* phase) {
 687   Node*         ctrl   = in(MemNode::Control);
 688   Node*         adr    = in(MemNode::Address);
 689   intptr_t      offset = 0;
 690   Node*         base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
 691   AllocateNode* alloc  = AllocateNode::Ideal_allocation(base);
 692 
 693   if (offset == Type::OffsetBot)
 694     return nullptr;            // cannot unalias unless there are precise offsets
 695 
 696   const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
 697   const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
 698 
 699   intptr_t size_in_bytes = memory_size();
 700 
 701   Node* mem = in(MemNode::Memory);   // start searching here...
 702 
 703   int cnt = 50;             // Cycle limiter
 704   for (;;) {                // While we can dance past unrelated stores...
 705     if (--cnt < 0)  break;  // Caught in cycle or a complicated dance?
 706 
 707     Node* prev = mem;
 708     if (mem->is_Store()) {
 709       Node* st_adr = mem->in(MemNode::Address);
 710       intptr_t st_offset = 0;
 711       Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
 712       if (st_base == nullptr)
 713         break;              // inscrutable pointer
 714 
 715       // For raw accesses it's not enough to prove that constant offsets don't intersect.
 716       // We need the bases to be the equal in order for the offset check to make sense.
 717       if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
 718         break;
 719       }
 720 
 721       if (st_offset != offset && st_offset != Type::OffsetBot) {
 722         const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
 723         assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
 724         if (st_offset >= offset + size_in_bytes ||
 725             st_offset <= offset - MAX_STORE ||
 726             st_offset <= offset - mem->as_Store()->memory_size()) {
 727           // Success:  The offsets are provably independent.
 728           // (You may ask, why not just test st_offset != offset and be done?
 729           // The answer is that stores of different sizes can co-exist
 730           // in the same sequence of RawMem effects.  We sometimes initialize
 731           // a whole 'tile' of array elements with a single jint or jlong.)
 732           mem = mem->in(MemNode::Memory);
 733           continue;           // (a) advance through independent store memory
 734         }
 735       }
 736       if (st_base != base &&
 737           detect_ptr_independence(base, alloc,
 738                                   st_base,
 739                                   AllocateNode::Ideal_allocation(st_base),
 740                                   phase)) {
 741         // Success:  The bases are provably independent.
 742         mem = mem->in(MemNode::Memory);
 743         continue;           // (a) advance through independent store memory
 744       }
 745 
 746       // (b) At this point, if the bases or offsets do not agree, we lose,
 747       // since we have not managed to prove 'this' and 'mem' independent.
 748       if (st_base == base && st_offset == offset) {
 749         return mem;         // let caller handle steps (c), (d)
 750       }
 751 
 752     } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
 753       InitializeNode* st_init = mem->in(0)->as_Initialize();
 754       AllocateNode*  st_alloc = st_init->allocation();
 755       if (st_alloc == nullptr) {
 756         break;              // something degenerated
 757       }
 758       bool known_identical = false;
 759       bool known_independent = false;
 760       if (alloc == st_alloc) {
 761         known_identical = true;
 762       } else if (alloc != nullptr) {
 763         known_independent = true;
 764       } else if (all_controls_dominate(this, st_alloc)) {
 765         known_independent = true;
 766       }
 767 
 768       if (known_independent) {
 769         // The bases are provably independent: Either they are
 770         // manifestly distinct allocations, or else the control
 771         // of this load dominates the store's allocation.
 772         int alias_idx = phase->C->get_alias_index(adr_type());
 773         if (alias_idx == Compile::AliasIdxRaw) {
 774           mem = st_alloc->in(TypeFunc::Memory);
 775         } else {
 776           mem = st_init->memory(alias_idx);
 777         }
 778         continue;           // (a) advance through independent store memory
 779       }
 780 
 781       // (b) at this point, if we are not looking at a store initializing
 782       // the same allocation we are loading from, we lose.
 783       if (known_identical) {
 784         // From caller, can_see_stored_value will consult find_captured_store.
 785         return mem;         // let caller handle steps (c), (d)
 786       }
 787 
 788     } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
 789       if (prev != mem) {
 790         // Found an arraycopy but it doesn't affect that load
 791         continue;
 792       }
 793       // Found an arraycopy that may affect that load
 794       return mem;
 795     } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
 796       // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
 797       if (mem->is_Proj() && mem->in(0)->is_Call()) {
 798         // ArrayCopyNodes processed here as well.
 799         CallNode *call = mem->in(0)->as_Call();
 800         if (!call->may_modify(addr_t, phase)) {
 801           mem = call->in(TypeFunc::Memory);
 802           continue;         // (a) advance through independent call memory
 803         }
 804       } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
 805         ArrayCopyNode* ac = nullptr;
 806         if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
 807           break;
 808         }
 809         mem = mem->in(0)->in(TypeFunc::Memory);
 810         continue;           // (a) advance through independent MemBar memory
 811       } else if (mem->is_ClearArray()) {
 812         if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
 813           // (the call updated 'mem' value)
 814           continue;         // (a) advance through independent allocation memory
 815         } else {
 816           // Can not bypass initialization of the instance
 817           // we are looking for.
 818           return mem;
 819         }
 820       } else if (mem->is_MergeMem()) {
 821         int alias_idx = phase->C->get_alias_index(adr_type());
 822         mem = mem->as_MergeMem()->memory_at(alias_idx);
 823         continue;           // (a) advance through independent MergeMem memory
 824       }
 825     }
 826 
 827     // Unless there is an explicit 'continue', we must bail out here,
 828     // because 'mem' is an inscrutable memory state (e.g., a call).
 829     break;
 830   }
 831 
 832   return nullptr;              // bail out
 833 }
 834 
 835 //----------------------calculate_adr_type-------------------------------------
 836 // Helper function.  Notices when the given type of address hits top or bottom.
 837 // Also, asserts a cross-check of the type against the expected address type.
 838 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
 839   if (t == Type::TOP)  return nullptr; // does not touch memory any more?
 840   #ifdef ASSERT
 841   if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump())  cross_check = nullptr;
 842   #endif
 843   const TypePtr* tp = t->isa_ptr();
 844   if (tp == nullptr) {
 845     assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
 846     return TypePtr::BOTTOM;           // touches lots of memory
 847   } else {
 848     #ifdef ASSERT
 849     // %%%% [phh] We don't check the alias index if cross_check is
 850     //            TypeRawPtr::BOTTOM.  Needs to be investigated.
 851     if (cross_check != nullptr &&
 852         cross_check != TypePtr::BOTTOM &&
 853         cross_check != TypeRawPtr::BOTTOM) {
 854       // Recheck the alias index, to see if it has changed (due to a bug).
 855       Compile* C = Compile::current();
 856       assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
 857              "must stay in the original alias category");
 858       // The type of the address must be contained in the adr_type,
 859       // disregarding "null"-ness.
 860       // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
 861       const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
 862       assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
 863              "real address must not escape from expected memory type");
 864     }
 865     #endif
 866     return tp;
 867   }
 868 }
 869 
 870 uint8_t MemNode::barrier_data(const Node* n) {
 871   if (n->is_LoadStore()) {
 872     return n->as_LoadStore()->barrier_data();
 873   } else if (n->is_Mem()) {
 874     return n->as_Mem()->barrier_data();
 875   }
 876   return 0;
 877 }
 878 
 879 //=============================================================================
 880 // Should LoadNode::Ideal() attempt to remove control edges?
 881 bool LoadNode::can_remove_control() const {
 882   return !has_pinned_control_dependency();
 883 }
 884 uint LoadNode::size_of() const { return sizeof(*this); }
 885 bool LoadNode::cmp(const Node &n) const {
 886   LoadNode& load = (LoadNode &)n;
 887   return Type::equals(_type, load._type) &&
 888          _control_dependency == load._control_dependency &&
 889          _mo == load._mo;
 890 }
 891 const Type *LoadNode::bottom_type() const { return _type; }
 892 uint LoadNode::ideal_reg() const {
 893   return _type->ideal_reg();
 894 }
 895 
 896 #ifndef PRODUCT
 897 void LoadNode::dump_spec(outputStream *st) const {
 898   MemNode::dump_spec(st);
 899   if( !Verbose && !WizardMode ) {
 900     // standard dump does this in Verbose and WizardMode
 901     st->print(" #"); _type->dump_on(st);
 902   }
 903   if (!depends_only_on_test()) {
 904     st->print(" (does not depend only on test, ");
 905     if (control_dependency() == UnknownControl) {
 906       st->print("unknown control");
 907     } else if (control_dependency() == Pinned) {
 908       st->print("pinned");
 909     } else if (adr_type() == TypeRawPtr::BOTTOM) {
 910       st->print("raw access");
 911     } else {
 912       st->print("unknown reason");
 913     }
 914     st->print(")");
 915   }
 916 }
 917 #endif
 918 
 919 #ifdef ASSERT
 920 //----------------------------is_immutable_value-------------------------------
 921 // Helper function to allow a raw load without control edge for some cases
 922 bool LoadNode::is_immutable_value(Node* adr) {
 923   if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
 924       adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
 925 
 926     jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
 927     int offsets[] = {
 928       in_bytes(JavaThread::osthread_offset()),
 929       in_bytes(JavaThread::threadObj_offset()),
 930       in_bytes(JavaThread::vthread_offset()),
 931       in_bytes(JavaThread::scopedValueCache_offset()),
 932     };
 933 
 934     for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
 935       if (offset == offsets[i]) {
 936         return true;
 937       }
 938     }
 939   }
 940 
 941   return false;
 942 }
 943 #endif
 944 
 945 //----------------------------LoadNode::make-----------------------------------
 946 // Polymorphic factory method:
 947 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
 948                      ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
 949   Compile* C = gvn.C;
 950 
 951   // sanity check the alias category against the created node type
 952   assert(!(adr_type->isa_oopptr() &&
 953            adr_type->offset() == Type::klass_offset()),
 954          "use LoadKlassNode instead");
 955   assert(!(adr_type->isa_aryptr() &&
 956            adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
 957          "use LoadRangeNode instead");
 958   // Check control edge of raw loads
 959   assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
 960           // oop will be recorded in oop map if load crosses safepoint
 961           rt->isa_oopptr() || is_immutable_value(adr),
 962           "raw memory operations should have control edge");
 963   LoadNode* load = nullptr;
 964   switch (bt) {
 965   case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 966   case T_BYTE:    load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 967   case T_INT:     load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 968   case T_CHAR:    load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 969   case T_SHORT:   load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 970   case T_LONG:    load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
 971   case T_FLOAT:   load = new LoadFNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency); break;
 972   case T_DOUBLE:  load = new LoadDNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency, require_atomic_access); break;
 973   case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(),  mo, control_dependency); break;
 974   case T_OBJECT:
 975   case T_NARROWOOP:
 976 #ifdef _LP64
 977     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
 978       load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
 979     } else
 980 #endif
 981     {
 982       assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
 983       load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
 984     }
 985     break;
 986   default:
 987     ShouldNotReachHere();
 988     break;
 989   }
 990   assert(load != nullptr, "LoadNode should have been created");
 991   if (unaligned) {
 992     load->set_unaligned_access();
 993   }
 994   if (mismatched) {
 995     load->set_mismatched_access();
 996   }
 997   if (unsafe) {
 998     load->set_unsafe_access();
 999   }
1000   load->set_barrier_data(barrier_data);
1001   if (load->Opcode() == Op_LoadN) {
1002     Node* ld = gvn.transform(load);
1003     return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1004   }
1005 
1006   return load;
1007 }
1008 
1009 //------------------------------hash-------------------------------------------
1010 uint LoadNode::hash() const {
1011   // unroll addition of interesting fields
1012   return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1013 }
1014 
1015 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1016   if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1017     bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1018     bool is_stable_ary = FoldStableValues &&
1019                          (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1020                          tp->isa_aryptr()->is_stable();
1021 
1022     return (eliminate_boxing && non_volatile) || is_stable_ary;
1023   }
1024 
1025   return false;
1026 }
1027 
1028 LoadNode* LoadNode::pin_array_access_node() const {
1029   const TypePtr* adr_type = this->adr_type();
1030   if (adr_type != nullptr && adr_type->isa_aryptr()) {
1031     return clone_pinned();
1032   }
1033   return nullptr;
1034 }
1035 
1036 // Is the value loaded previously stored by an arraycopy? If so return
1037 // a load node that reads from the source array so we may be able to
1038 // optimize out the ArrayCopy node later.
1039 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1040   Node* ld_adr = in(MemNode::Address);
1041   intptr_t ld_off = 0;
1042   AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1043   Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1044   if (ac != nullptr) {
1045     assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1046 
1047     Node* mem = ac->in(TypeFunc::Memory);
1048     Node* ctl = ac->in(0);
1049     Node* src = ac->in(ArrayCopyNode::Src);
1050 
1051     if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1052       return nullptr;
1053     }
1054 
1055     // load depends on the tests that validate the arraycopy
1056     LoadNode* ld = clone_pinned();
1057     Node* addp = in(MemNode::Address)->clone();
1058     if (ac->as_ArrayCopy()->is_clonebasic()) {
1059       assert(ld_alloc != nullptr, "need an alloc");
1060       assert(addp->is_AddP(), "address must be addp");
1061       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1062       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1063       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1064       addp->set_req(AddPNode::Base, src);
1065       addp->set_req(AddPNode::Address, src);
1066     } else {
1067       assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1068              ac->as_ArrayCopy()->is_copyof_validated() ||
1069              ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1070       assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1071       addp->set_req(AddPNode::Base, src);
1072       addp->set_req(AddPNode::Address, src);
1073 
1074       const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1075       BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1076       if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1077 
1078       uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1079       uint shift  = exact_log2(type2aelembytes(ary_elem));
1080 
1081       Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1082 #ifdef _LP64
1083       diff = phase->transform(new ConvI2LNode(diff));
1084 #endif
1085       diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1086 
1087       Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1088       addp->set_req(AddPNode::Offset, offset);
1089     }
1090     addp = phase->transform(addp);
1091 #ifdef ASSERT
1092     const TypePtr* adr_type = phase->type(addp)->is_ptr();
1093     ld->_adr_type = adr_type;
1094 #endif
1095     ld->set_req(MemNode::Address, addp);
1096     ld->set_req(0, ctl);
1097     ld->set_req(MemNode::Memory, mem);
1098     return ld;
1099   }
1100   return nullptr;
1101 }
1102 
1103 
1104 //---------------------------can_see_stored_value------------------------------
1105 // This routine exists to make sure this set of tests is done the same
1106 // everywhere.  We need to make a coordinated change: first LoadNode::Ideal
1107 // will change the graph shape in a way which makes memory alive twice at the
1108 // same time (uses the Oracle model of aliasing), then some
1109 // LoadXNode::Identity will fold things back to the equivalence-class model
1110 // of aliasing.
1111 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1112   Node* ld_adr = in(MemNode::Address);
1113   intptr_t ld_off = 0;
1114   Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1115   Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1116   const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1117   Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1118   // This is more general than load from boxing objects.
1119   if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1120     uint alias_idx = atp->index();
1121     Node* result = nullptr;
1122     Node* current = st;
1123     // Skip through chains of MemBarNodes checking the MergeMems for
1124     // new states for the slice of this load.  Stop once any other
1125     // kind of node is encountered.  Loads from final memory can skip
1126     // through any kind of MemBar but normal loads shouldn't skip
1127     // through MemBarAcquire since the could allow them to move out of
1128     // a synchronized region. It is not safe to step over MemBarCPUOrder,
1129     // because alias info above them may be inaccurate (e.g., due to
1130     // mixed/mismatched unsafe accesses).
1131     bool is_final_mem = !atp->is_rewritable();
1132     while (current->is_Proj()) {
1133       int opc = current->in(0)->Opcode();
1134       if ((is_final_mem && (opc == Op_MemBarAcquire ||
1135                             opc == Op_MemBarAcquireLock ||
1136                             opc == Op_LoadFence)) ||
1137           opc == Op_MemBarRelease ||
1138           opc == Op_StoreFence ||
1139           opc == Op_MemBarReleaseLock ||
1140           opc == Op_MemBarStoreStore ||
1141           opc == Op_StoreStoreFence) {
1142         Node* mem = current->in(0)->in(TypeFunc::Memory);
1143         if (mem->is_MergeMem()) {
1144           MergeMemNode* merge = mem->as_MergeMem();
1145           Node* new_st = merge->memory_at(alias_idx);
1146           if (new_st == merge->base_memory()) {
1147             // Keep searching
1148             current = new_st;
1149             continue;
1150           }
1151           // Save the new memory state for the slice and fall through
1152           // to exit.
1153           result = new_st;
1154         }
1155       }
1156       break;
1157     }
1158     if (result != nullptr) {
1159       st = result;
1160     }
1161   }
1162 
1163   // Loop around twice in the case Load -> Initialize -> Store.
1164   // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1165   for (int trip = 0; trip <= 1; trip++) {
1166 
1167     if (st->is_Store()) {
1168       Node* st_adr = st->in(MemNode::Address);
1169       if (st_adr != ld_adr) {
1170         // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1171         intptr_t st_off = 0;
1172         Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1173         if (ld_base == nullptr)                                return nullptr;
1174         if (st_base == nullptr)                                return nullptr;
1175         if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1176         if (ld_off != st_off)                                  return nullptr;
1177         if (ld_off == Type::OffsetBot)                         return nullptr;
1178         // Same base, same offset.
1179         // Possible improvement for arrays: check index value instead of absolute offset.
1180 
1181         // At this point we have proven something like this setup:
1182         //   B = << base >>
1183         //   L =  LoadQ(AddP(Check/CastPP(B), #Off))
1184         //   S = StoreQ(AddP(             B , #Off), V)
1185         // (Actually, we haven't yet proven the Q's are the same.)
1186         // In other words, we are loading from a casted version of
1187         // the same pointer-and-offset that we stored to.
1188         // Casted version may carry a dependency and it is respected.
1189         // Thus, we are able to replace L by V.
1190       }
1191       // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1192       if (store_Opcode() != st->Opcode()) {
1193         return nullptr;
1194       }
1195       // LoadVector/StoreVector needs additional check to ensure the types match.
1196       if (st->is_StoreVector()) {
1197         const TypeVect*  in_vt = st->as_StoreVector()->vect_type();
1198         const TypeVect* out_vt = as_LoadVector()->vect_type();
1199         if (in_vt != out_vt) {
1200           return nullptr;
1201         }
1202       }
1203       return st->in(MemNode::ValueIn);
1204     }
1205 
1206     // A load from a freshly-created object always returns zero.
1207     // (This can happen after LoadNode::Ideal resets the load's memory input
1208     // to find_captured_store, which returned InitializeNode::zero_memory.)
1209     if (st->is_Proj() && st->in(0)->is_Allocate() &&
1210         (st->in(0) == ld_alloc) &&
1211         (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1212       // return a zero value for the load's basic type
1213       // (This is one of the few places where a generic PhaseTransform
1214       // can create new nodes.  Think of it as lazily manifesting
1215       // virtually pre-existing constants.)
1216       if (value_basic_type() != T_VOID) {
1217         if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1218           // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1219           // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1220           // by the ArrayCopyNode.
1221           return phase->zerocon(value_basic_type());
1222         }
1223       } else {
1224         // TODO: materialize all-zero vector constant
1225         assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1226       }
1227     }
1228 
1229     // A load from an initialization barrier can match a captured store.
1230     if (st->is_Proj() && st->in(0)->is_Initialize()) {
1231       InitializeNode* init = st->in(0)->as_Initialize();
1232       AllocateNode* alloc = init->allocation();
1233       if ((alloc != nullptr) && (alloc == ld_alloc)) {
1234         // examine a captured store value
1235         st = init->find_captured_store(ld_off, memory_size(), phase);
1236         if (st != nullptr) {
1237           continue;             // take one more trip around
1238         }
1239       }
1240     }
1241 
1242     // Load boxed value from result of valueOf() call is input parameter.
1243     if (this->is_Load() && ld_adr->is_AddP() &&
1244         (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1245       intptr_t ignore = 0;
1246       Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1247       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1248       base = bs->step_over_gc_barrier(base);
1249       if (base != nullptr && base->is_Proj() &&
1250           base->as_Proj()->_con == TypeFunc::Parms &&
1251           base->in(0)->is_CallStaticJava() &&
1252           base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1253         return base->in(0)->in(TypeFunc::Parms);
1254       }
1255     }
1256 
1257     break;
1258   }
1259 
1260   return nullptr;
1261 }
1262 
1263 //----------------------is_instance_field_load_with_local_phi------------------
1264 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1265   if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1266       in(Address)->is_AddP() ) {
1267     const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1268     // Only instances and boxed values.
1269     if( t_oop != nullptr &&
1270         (t_oop->is_ptr_to_boxed_value() ||
1271          t_oop->is_known_instance_field()) &&
1272         t_oop->offset() != Type::OffsetBot &&
1273         t_oop->offset() != Type::OffsetTop) {
1274       return true;
1275     }
1276   }
1277   return false;
1278 }
1279 
1280 //------------------------------Identity---------------------------------------
1281 // Loads are identity if previous store is to same address
1282 Node* LoadNode::Identity(PhaseGVN* phase) {
1283   // If the previous store-maker is the right kind of Store, and the store is
1284   // to the same address, then we are equal to the value stored.
1285   Node* mem = in(Memory);
1286   Node* value = can_see_stored_value(mem, phase);
1287   if( value ) {
1288     // byte, short & char stores truncate naturally.
1289     // A load has to load the truncated value which requires
1290     // some sort of masking operation and that requires an
1291     // Ideal call instead of an Identity call.
1292     if (memory_size() < BytesPerInt) {
1293       // If the input to the store does not fit with the load's result type,
1294       // it must be truncated via an Ideal call.
1295       if (!phase->type(value)->higher_equal(phase->type(this)))
1296         return this;
1297     }
1298     // (This works even when value is a Con, but LoadNode::Value
1299     // usually runs first, producing the singleton type of the Con.)
1300     if (!has_pinned_control_dependency() || value->is_Con()) {
1301       return value;
1302     } else {
1303       return this;
1304     }
1305   }
1306 
1307   if (has_pinned_control_dependency()) {
1308     return this;
1309   }
1310   // Search for an existing data phi which was generated before for the same
1311   // instance's field to avoid infinite generation of phis in a loop.
1312   Node *region = mem->in(0);
1313   if (is_instance_field_load_with_local_phi(region)) {
1314     const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1315     int this_index  = phase->C->get_alias_index(addr_t);
1316     int this_offset = addr_t->offset();
1317     int this_iid    = addr_t->instance_id();
1318     if (!addr_t->is_known_instance() &&
1319          addr_t->is_ptr_to_boxed_value()) {
1320       // Use _idx of address base (could be Phi node) for boxed values.
1321       intptr_t   ignore = 0;
1322       Node*      base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1323       if (base == nullptr) {
1324         return this;
1325       }
1326       this_iid = base->_idx;
1327     }
1328     const Type* this_type = bottom_type();
1329     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1330       Node* phi = region->fast_out(i);
1331       if (phi->is_Phi() && phi != mem &&
1332           phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1333         return phi;
1334       }
1335     }
1336   }
1337 
1338   return this;
1339 }
1340 
1341 // Construct an equivalent unsigned load.
1342 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1343   BasicType bt = T_ILLEGAL;
1344   const Type* rt = nullptr;
1345   switch (Opcode()) {
1346     case Op_LoadUB: return this;
1347     case Op_LoadUS: return this;
1348     case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1349     case Op_LoadS: bt = T_CHAR;    rt = TypeInt::CHAR;  break;
1350     default:
1351       assert(false, "no unsigned variant: %s", Name());
1352       return nullptr;
1353   }
1354   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1355                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1356                         false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1357 }
1358 
1359 // Construct an equivalent signed load.
1360 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1361   BasicType bt = T_ILLEGAL;
1362   const Type* rt = nullptr;
1363   switch (Opcode()) {
1364     case Op_LoadUB: bt = T_BYTE;  rt = TypeInt::BYTE;  break;
1365     case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1366     case Op_LoadB: // fall through
1367     case Op_LoadS: // fall through
1368     case Op_LoadI: // fall through
1369     case Op_LoadL: return this;
1370     default:
1371       assert(false, "no signed variant: %s", Name());
1372       return nullptr;
1373   }
1374   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1375                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1376                         false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1377 }
1378 
1379 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1380   BasicType bt = rt->basic_type();
1381   switch (Opcode()) {
1382     case Op_LoadI: return (bt == T_FLOAT);
1383     case Op_LoadL: return (bt == T_DOUBLE);
1384     case Op_LoadF: return (bt == T_INT);
1385     case Op_LoadD: return (bt == T_LONG);
1386 
1387     default: return false;
1388   }
1389 }
1390 
1391 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1392   BasicType bt = rt->basic_type();
1393   assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1394   bool is_mismatched = is_mismatched_access();
1395   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1396   if (raw_type == nullptr) {
1397     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1398   }
1399   const int op = Opcode();
1400   bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1401                                (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1402   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1403                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1404                         require_atomic_access, is_unaligned_access(), is_mismatched);
1405 }
1406 
1407 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1408   BasicType bt = vt->basic_type();
1409   switch (Opcode()) {
1410     case Op_StoreI: return (bt == T_FLOAT);
1411     case Op_StoreL: return (bt == T_DOUBLE);
1412     case Op_StoreF: return (bt == T_INT);
1413     case Op_StoreD: return (bt == T_LONG);
1414 
1415     default: return false;
1416   }
1417 }
1418 
1419 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1420   BasicType bt = vt->basic_type();
1421   assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1422   const int op = Opcode();
1423   bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1424                                (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1425   StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1426                                   raw_adr_type(), val, bt, _mo, require_atomic_access);
1427 
1428   bool is_mismatched = is_mismatched_access();
1429   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1430   if (raw_type == nullptr) {
1431     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1432   }
1433   if (is_mismatched) {
1434     st->set_mismatched_access();
1435   }
1436   return st;
1437 }
1438 
1439 // We're loading from an object which has autobox behaviour.
1440 // If this object is result of a valueOf call we'll have a phi
1441 // merging a newly allocated object and a load from the cache.
1442 // We want to replace this load with the original incoming
1443 // argument to the valueOf call.
1444 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1445   assert(igvn->C->eliminate_boxing(), "sanity");
1446   intptr_t ignore = 0;
1447   Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1448   if ((base == nullptr) || base->is_Phi()) {
1449     // Push the loads from the phi that comes from valueOf up
1450     // through it to allow elimination of the loads and the recovery
1451     // of the original value. It is done in split_through_phi().
1452     return nullptr;
1453   } else if (base->is_Load() ||
1454              (base->is_DecodeN() && base->in(1)->is_Load())) {
1455     // Eliminate the load of boxed value for integer types from the cache
1456     // array by deriving the value from the index into the array.
1457     // Capture the offset of the load and then reverse the computation.
1458 
1459     // Get LoadN node which loads a boxing object from 'cache' array.
1460     if (base->is_DecodeN()) {
1461       base = base->in(1);
1462     }
1463     if (!base->in(Address)->is_AddP()) {
1464       return nullptr; // Complex address
1465     }
1466     AddPNode* address = base->in(Address)->as_AddP();
1467     Node* cache_base = address->in(AddPNode::Base);
1468     if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1469       // Get ConP node which is static 'cache' field.
1470       cache_base = cache_base->in(1);
1471     }
1472     if ((cache_base != nullptr) && cache_base->is_Con()) {
1473       const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1474       if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1475         Node* elements[4];
1476         int shift = exact_log2(type2aelembytes(T_OBJECT));
1477         int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1478         if (count > 0 && elements[0]->is_Con() &&
1479             (count == 1 ||
1480              (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1481                             elements[1]->in(2) == igvn->intcon(shift)))) {
1482           ciObjArray* array = base_type->const_oop()->as_obj_array();
1483           // Fetch the box object cache[0] at the base of the array and get its value
1484           ciInstance* box = array->obj_at(0)->as_instance();
1485           ciInstanceKlass* ik = box->klass()->as_instance_klass();
1486           assert(ik->is_box_klass(), "sanity");
1487           assert(ik->nof_nonstatic_fields() == 1, "change following code");
1488           if (ik->nof_nonstatic_fields() == 1) {
1489             // This should be true nonstatic_field_at requires calling
1490             // nof_nonstatic_fields so check it anyway
1491             ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1492             BasicType bt = c.basic_type();
1493             // Only integer types have boxing cache.
1494             assert(bt == T_BOOLEAN || bt == T_CHAR  ||
1495                    bt == T_BYTE    || bt == T_SHORT ||
1496                    bt == T_INT     || bt == T_LONG, "wrong type = %s", type2name(bt));
1497             jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1498             if (cache_low != (int)cache_low) {
1499               return nullptr; // should not happen since cache is array indexed by value
1500             }
1501             jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1502             if (offset != (int)offset) {
1503               return nullptr; // should not happen since cache is array indexed by value
1504             }
1505            // Add up all the offsets making of the address of the load
1506             Node* result = elements[0];
1507             for (int i = 1; i < count; i++) {
1508               result = igvn->transform(new AddXNode(result, elements[i]));
1509             }
1510             // Remove the constant offset from the address and then
1511             result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1512             // remove the scaling of the offset to recover the original index.
1513             if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1514               // Peel the shift off directly but wrap it in a dummy node
1515               // since Ideal can't return existing nodes
1516               igvn->_worklist.push(result); // remove dead node later
1517               result = new RShiftXNode(result->in(1), igvn->intcon(0));
1518             } else if (result->is_Add() && result->in(2)->is_Con() &&
1519                        result->in(1)->Opcode() == Op_LShiftX &&
1520                        result->in(1)->in(2) == igvn->intcon(shift)) {
1521               // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1522               // but for boxing cache access we know that X<<Z will not overflow
1523               // (there is range check) so we do this optimizatrion by hand here.
1524               igvn->_worklist.push(result); // remove dead node later
1525               Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1526               result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1527             } else {
1528               result = new RShiftXNode(result, igvn->intcon(shift));
1529             }
1530 #ifdef _LP64
1531             if (bt != T_LONG) {
1532               result = new ConvL2INode(igvn->transform(result));
1533             }
1534 #else
1535             if (bt == T_LONG) {
1536               result = new ConvI2LNode(igvn->transform(result));
1537             }
1538 #endif
1539             // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1540             // Need to preserve unboxing load type if it is unsigned.
1541             switch(this->Opcode()) {
1542               case Op_LoadUB:
1543                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1544                 break;
1545               case Op_LoadUS:
1546                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1547                 break;
1548             }
1549             return result;
1550           }
1551         }
1552       }
1553     }
1554   }
1555   return nullptr;
1556 }
1557 
1558 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1559   Node* region = phi->in(0);
1560   if (region == nullptr) {
1561     return false; // Wait stable graph
1562   }
1563   uint cnt = phi->req();
1564   for (uint i = 1; i < cnt; i++) {
1565     Node* rc = region->in(i);
1566     if (rc == nullptr || phase->type(rc) == Type::TOP)
1567       return false; // Wait stable graph
1568     Node* in = phi->in(i);
1569     if (in == nullptr || phase->type(in) == Type::TOP)
1570       return false; // Wait stable graph
1571   }
1572   return true;
1573 }
1574 
1575 //------------------------------split_through_phi------------------------------
1576 // Check whether a call to 'split_through_phi' would split this load through the
1577 // Phi *base*. This method is essentially a copy of the validations performed
1578 // by 'split_through_phi'. The first use of this method was in EA code as part
1579 // of simplification of allocation merges.
1580 // Some differences from original method (split_through_phi):
1581 //  - If base->is_CastPP(): base = base->in(1)
1582 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1583   Node* mem        = in(Memory);
1584   Node* address    = in(Address);
1585   intptr_t ignore  = 0;
1586   Node*    base    = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1587 
1588   if (base->is_CastPP()) {
1589     base = base->in(1);
1590   }
1591 
1592   if (req() > 3 || base == nullptr || !base->is_Phi()) {
1593     return false;
1594   }
1595 
1596   if (!mem->is_Phi()) {
1597     if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1598       return false;
1599     }
1600   } else if (base->in(0) != mem->in(0)) {
1601     if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1602       return false;
1603     }
1604   }
1605 
1606   return true;
1607 }
1608 
1609 //------------------------------split_through_phi------------------------------
1610 // Split instance or boxed field load through Phi.
1611 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1612   if (req() > 3) {
1613     assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1614     // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1615     return nullptr;
1616   }
1617   Node* mem     = in(Memory);
1618   Node* address = in(Address);
1619   const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1620 
1621   assert((t_oop != nullptr) &&
1622          (ignore_missing_instance_id ||
1623           t_oop->is_known_instance_field() ||
1624           t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1625 
1626   Compile* C = phase->C;
1627   intptr_t ignore = 0;
1628   Node*    base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1629   bool base_is_phi = (base != nullptr) && base->is_Phi();
1630   bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1631                            (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1632                            phase->type(base)->higher_equal(TypePtr::NOTNULL);
1633 
1634   if (!((mem->is_Phi() || base_is_phi) &&
1635         (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1636     return nullptr; // Neither memory or base are Phi
1637   }
1638 
1639   if (mem->is_Phi()) {
1640     if (!stable_phi(mem->as_Phi(), phase)) {
1641       return nullptr; // Wait stable graph
1642     }
1643     uint cnt = mem->req();
1644     // Check for loop invariant memory.
1645     if (cnt == 3) {
1646       for (uint i = 1; i < cnt; i++) {
1647         Node* in = mem->in(i);
1648         Node*  m = optimize_memory_chain(in, t_oop, this, phase);
1649         if (m == mem) {
1650           if (i == 1) {
1651             // if the first edge was a loop, check second edge too.
1652             // If both are replaceable - we are in an infinite loop
1653             Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1654             if (n == mem) {
1655               break;
1656             }
1657           }
1658           set_req(Memory, mem->in(cnt - i));
1659           return this; // made change
1660         }
1661       }
1662     }
1663   }
1664   if (base_is_phi) {
1665     if (!stable_phi(base->as_Phi(), phase)) {
1666       return nullptr; // Wait stable graph
1667     }
1668     uint cnt = base->req();
1669     // Check for loop invariant memory.
1670     if (cnt == 3) {
1671       for (uint i = 1; i < cnt; i++) {
1672         if (base->in(i) == base) {
1673           return nullptr; // Wait stable graph
1674         }
1675       }
1676     }
1677   }
1678 
1679   // Split through Phi (see original code in loopopts.cpp).
1680   assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1681 
1682   // Do nothing here if Identity will find a value
1683   // (to avoid infinite chain of value phis generation).
1684   if (this != Identity(phase)) {
1685     return nullptr;
1686   }
1687 
1688   // Select Region to split through.
1689   Node* region;
1690   DomResult dom_result = DomResult::Dominate;
1691   if (!base_is_phi) {
1692     assert(mem->is_Phi(), "sanity");
1693     region = mem->in(0);
1694     // Skip if the region dominates some control edge of the address.
1695     // We will check `dom_result` later.
1696     dom_result = MemNode::maybe_all_controls_dominate(address, region);
1697   } else if (!mem->is_Phi()) {
1698     assert(base_is_phi, "sanity");
1699     region = base->in(0);
1700     // Skip if the region dominates some control edge of the memory.
1701     // We will check `dom_result` later.
1702     dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1703   } else if (base->in(0) != mem->in(0)) {
1704     assert(base_is_phi && mem->is_Phi(), "sanity");
1705     dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1706     if (dom_result == DomResult::Dominate) {
1707       region = base->in(0);
1708     } else {
1709       dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1710       if (dom_result == DomResult::Dominate) {
1711         region = mem->in(0);
1712       }
1713       // Otherwise we encountered a complex graph.
1714     }
1715   } else {
1716     assert(base->in(0) == mem->in(0), "sanity");
1717     region = mem->in(0);
1718   }
1719 
1720   PhaseIterGVN* igvn = phase->is_IterGVN();
1721   if (dom_result != DomResult::Dominate) {
1722     if (dom_result == DomResult::EncounteredDeadCode) {
1723       // There is some dead code which eventually will be removed in IGVN.
1724       // Once this is the case, we get an unambiguous dominance result.
1725       // Push the node to the worklist again until the dead code is removed.
1726       igvn->_worklist.push(this);
1727     }
1728     return nullptr;
1729   }
1730 
1731   Node* phi = nullptr;
1732   const Type* this_type = this->bottom_type();
1733   if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1734     int this_index = C->get_alias_index(t_oop);
1735     int this_offset = t_oop->offset();
1736     int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1737     phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1738   } else if (ignore_missing_instance_id) {
1739     phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1740   } else {
1741     return nullptr;
1742   }
1743 
1744   for (uint i = 1; i < region->req(); i++) {
1745     Node* x;
1746     Node* the_clone = nullptr;
1747     Node* in = region->in(i);
1748     if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1749         in != nullptr && in->is_OuterStripMinedLoop()) {
1750       // No node should go in the outer strip mined loop
1751       in = in->in(LoopNode::EntryControl);
1752     }
1753     if (in == nullptr || in == C->top()) {
1754       x = C->top();      // Dead path?  Use a dead data op
1755     } else {
1756       x = this->clone();        // Else clone up the data op
1757       the_clone = x;            // Remember for possible deletion.
1758       // Alter data node to use pre-phi inputs
1759       if (this->in(0) == region) {
1760         x->set_req(0, in);
1761       } else {
1762         x->set_req(0, nullptr);
1763       }
1764       if (mem->is_Phi() && (mem->in(0) == region)) {
1765         x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1766       }
1767       if (address->is_Phi() && address->in(0) == region) {
1768         x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1769       }
1770       if (base_is_phi && (base->in(0) == region)) {
1771         Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1772         Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1773         x->set_req(Address, adr_x);
1774       }
1775     }
1776     // Check for a 'win' on some paths
1777     const Type *t = x->Value(igvn);
1778 
1779     bool singleton = t->singleton();
1780 
1781     // See comments in PhaseIdealLoop::split_thru_phi().
1782     if (singleton && t == Type::TOP) {
1783       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1784     }
1785 
1786     if (singleton) {
1787       x = igvn->makecon(t);
1788     } else {
1789       // We now call Identity to try to simplify the cloned node.
1790       // Note that some Identity methods call phase->type(this).
1791       // Make sure that the type array is big enough for
1792       // our new node, even though we may throw the node away.
1793       // (This tweaking with igvn only works because x is a new node.)
1794       igvn->set_type(x, t);
1795       // If x is a TypeNode, capture any more-precise type permanently into Node
1796       // otherwise it will be not updated during igvn->transform since
1797       // igvn->type(x) is set to x->Value() already.
1798       x->raise_bottom_type(t);
1799       Node* y = x->Identity(igvn);
1800       if (y != x) {
1801         x = y;
1802       } else {
1803         y = igvn->hash_find_insert(x);
1804         if (y) {
1805           x = y;
1806         } else {
1807           // Else x is a new node we are keeping
1808           // We do not need register_new_node_with_optimizer
1809           // because set_type has already been called.
1810           igvn->_worklist.push(x);
1811         }
1812       }
1813     }
1814     if (x != the_clone && the_clone != nullptr) {
1815       igvn->remove_dead_node(the_clone);
1816     }
1817     phi->set_req(i, x);
1818   }
1819   // Record Phi
1820   igvn->register_new_node_with_optimizer(phi);
1821   return phi;
1822 }
1823 
1824 AllocateNode* LoadNode::is_new_object_mark_load() const {
1825   if (Opcode() == Op_LoadX) {
1826     Node* address = in(MemNode::Address);
1827     AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1828     Node* mem = in(MemNode::Memory);
1829     if (alloc != nullptr && mem->is_Proj() &&
1830         mem->in(0) != nullptr &&
1831         mem->in(0) == alloc->initialization() &&
1832         alloc->initialization()->proj_out_or_null(0) != nullptr) {
1833       return alloc;
1834     }
1835   }
1836   return nullptr;
1837 }
1838 
1839 
1840 //------------------------------Ideal------------------------------------------
1841 // If the load is from Field memory and the pointer is non-null, it might be possible to
1842 // zero out the control input.
1843 // If the offset is constant and the base is an object allocation,
1844 // try to hook me up to the exact initializing store.
1845 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1846   if (has_pinned_control_dependency()) {
1847     return nullptr;
1848   }
1849   Node* p = MemNode::Ideal_common(phase, can_reshape);
1850   if (p)  return (p == NodeSentinel) ? nullptr : p;
1851 
1852   Node* ctrl    = in(MemNode::Control);
1853   Node* address = in(MemNode::Address);
1854   bool progress = false;
1855 
1856   bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1857          phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1858 
1859   // Skip up past a SafePoint control.  Cannot do this for Stores because
1860   // pointer stores & cardmarks must stay on the same side of a SafePoint.
1861   if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1862       phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw  &&
1863       !addr_mark &&
1864       (depends_only_on_test() || has_unknown_control_dependency())) {
1865     ctrl = ctrl->in(0);
1866     set_req(MemNode::Control,ctrl);
1867     progress = true;
1868   }
1869 
1870   intptr_t ignore = 0;
1871   Node*    base   = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1872   if (base != nullptr
1873       && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1874     // Check for useless control edge in some common special cases
1875     if (in(MemNode::Control) != nullptr
1876         && can_remove_control()
1877         && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1878         && all_controls_dominate(base, phase->C->start())) {
1879       // A method-invariant, non-null address (constant or 'this' argument).
1880       set_req(MemNode::Control, nullptr);
1881       progress = true;
1882     }
1883   }
1884 
1885   Node* mem = in(MemNode::Memory);
1886   const TypePtr *addr_t = phase->type(address)->isa_ptr();
1887 
1888   if (can_reshape && (addr_t != nullptr)) {
1889     // try to optimize our memory input
1890     Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1891     if (opt_mem != mem) {
1892       set_req_X(MemNode::Memory, opt_mem, phase);
1893       if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1894       return this;
1895     }
1896     const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1897     if ((t_oop != nullptr) &&
1898         (t_oop->is_known_instance_field() ||
1899          t_oop->is_ptr_to_boxed_value())) {
1900       PhaseIterGVN *igvn = phase->is_IterGVN();
1901       assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1902       if (igvn->_worklist.member(opt_mem)) {
1903         // Delay this transformation until memory Phi is processed.
1904         igvn->_worklist.push(this);
1905         return nullptr;
1906       }
1907       // Split instance field load through Phi.
1908       Node* result = split_through_phi(phase);
1909       if (result != nullptr) return result;
1910 
1911       if (t_oop->is_ptr_to_boxed_value()) {
1912         Node* result = eliminate_autobox(igvn);
1913         if (result != nullptr) return result;
1914       }
1915     }
1916   }
1917 
1918   // Is there a dominating load that loads the same value?  Leave
1919   // anything that is not a load of a field/array element (like
1920   // barriers etc.) alone
1921   if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1922     for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1923       Node *use = mem->fast_out(i);
1924       if (use != this &&
1925           use->Opcode() == Opcode() &&
1926           use->in(0) != nullptr &&
1927           use->in(0) != in(0) &&
1928           use->in(Address) == in(Address)) {
1929         Node* ctl = in(0);
1930         for (int i = 0; i < 10 && ctl != nullptr; i++) {
1931           ctl = IfNode::up_one_dom(ctl);
1932           if (ctl == use->in(0)) {
1933             set_req(0, use->in(0));
1934             return this;
1935           }
1936         }
1937       }
1938     }
1939   }
1940 
1941   // Check for prior store with a different base or offset; make Load
1942   // independent.  Skip through any number of them.  Bail out if the stores
1943   // are in an endless dead cycle and report no progress.  This is a key
1944   // transform for Reflection.  However, if after skipping through the Stores
1945   // we can't then fold up against a prior store do NOT do the transform as
1946   // this amounts to using the 'Oracle' model of aliasing.  It leaves the same
1947   // array memory alive twice: once for the hoisted Load and again after the
1948   // bypassed Store.  This situation only works if EVERYBODY who does
1949   // anti-dependence work knows how to bypass.  I.e. we need all
1950   // anti-dependence checks to ask the same Oracle.  Right now, that Oracle is
1951   // the alias index stuff.  So instead, peek through Stores and IFF we can
1952   // fold up, do so.
1953   Node* prev_mem = find_previous_store(phase);
1954   if (prev_mem != nullptr) {
1955     Node* value = can_see_arraycopy_value(prev_mem, phase);
1956     if (value != nullptr) {
1957       return value;
1958     }
1959   }
1960   // Steps (a), (b):  Walk past independent stores to find an exact match.
1961   if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
1962     // (c) See if we can fold up on the spot, but don't fold up here.
1963     // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1964     // just return a prior value, which is done by Identity calls.
1965     if (can_see_stored_value(prev_mem, phase)) {
1966       // Make ready for step (d):
1967       set_req_X(MemNode::Memory, prev_mem, phase);
1968       return this;
1969     }
1970   }
1971 
1972   return progress ? this : nullptr;
1973 }
1974 
1975 // Helper to recognize certain Klass fields which are invariant across
1976 // some group of array types (e.g., int[] or all T[] where T < Object).
1977 const Type*
1978 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1979                                  ciKlass* klass) const {
1980   assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
1981          "must not happen");
1982   if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1983     // The field is Klass::_access_flags.  Return its (constant) value.
1984     // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1985     assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
1986     return TypeInt::make(klass->access_flags());
1987   }
1988   if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
1989     // The field is Klass::_misc_flags.  Return its (constant) value.
1990     // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1991     assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
1992     return TypeInt::make(klass->misc_flags());
1993   }
1994   if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1995     // The field is Klass::_layout_helper.  Return its constant value if known.
1996     assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1997     return TypeInt::make(klass->layout_helper());
1998   }
1999 
2000   // No match.
2001   return nullptr;
2002 }
2003 
2004 //------------------------------Value-----------------------------------------
2005 const Type* LoadNode::Value(PhaseGVN* phase) const {
2006   // Either input is TOP ==> the result is TOP
2007   Node* mem = in(MemNode::Memory);
2008   const Type *t1 = phase->type(mem);
2009   if (t1 == Type::TOP)  return Type::TOP;
2010   Node* adr = in(MemNode::Address);
2011   const TypePtr* tp = phase->type(adr)->isa_ptr();
2012   if (tp == nullptr || tp->empty())  return Type::TOP;
2013   int off = tp->offset();
2014   assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2015   Compile* C = phase->C;
2016 
2017   // If we are loading from a freshly-allocated object, produce a zero,
2018   // if the load is provably beyond the header of the object.
2019   // (Also allow a variable load from a fresh array to produce zero.)
2020   const TypeOopPtr* tinst = tp->isa_oopptr();
2021   bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2022   Node* value = can_see_stored_value(mem, phase);
2023   if (value != nullptr && value->is_Con()) {
2024     assert(value->bottom_type()->higher_equal(_type), "sanity");
2025     return value->bottom_type();
2026   }
2027 
2028   // Try to guess loaded type from pointer type
2029   if (tp->isa_aryptr()) {
2030     const TypeAryPtr* ary = tp->is_aryptr();
2031     const Type* t = ary->elem();
2032 
2033     // Determine whether the reference is beyond the header or not, by comparing
2034     // the offset against the offset of the start of the array's data.
2035     // Different array types begin at slightly different offsets (12 vs. 16).
2036     // We choose T_BYTE as an example base type that is least restrictive
2037     // as to alignment, which will therefore produce the smallest
2038     // possible base offset.
2039     const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2040     const bool off_beyond_header = (off >= min_base_off);
2041 
2042     // Try to constant-fold a stable array element.
2043     if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2044       // Make sure the reference is not into the header and the offset is constant
2045       ciObject* aobj = ary->const_oop();
2046       if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2047         int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2048         const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2049                                                                       stable_dimension,
2050                                                                       value_basic_type(), is_unsigned());
2051         if (con_type != nullptr) {
2052           return con_type;
2053         }
2054       }
2055     }
2056 
2057     // Don't do this for integer types. There is only potential profit if
2058     // the element type t is lower than _type; that is, for int types, if _type is
2059     // more restrictive than t.  This only happens here if one is short and the other
2060     // char (both 16 bits), and in those cases we've made an intentional decision
2061     // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2062     // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2063     //
2064     // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2065     // where the _gvn.type of the AddP is wider than 8.  This occurs when an earlier
2066     // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2067     // subsumed by p1.  If p1 is on the worklist but has not yet been re-transformed,
2068     // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2069     // In fact, that could have been the original type of p1, and p1 could have
2070     // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2071     // expression (LShiftL quux 3) independently optimized to the constant 8.
2072     if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2073         && (_type->isa_vect() == nullptr)
2074         && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2075       // t might actually be lower than _type, if _type is a unique
2076       // concrete subclass of abstract class t.
2077       if (off_beyond_header || off == Type::OffsetBot) {  // is the offset beyond the header?
2078         const Type* jt = t->join_speculative(_type);
2079         // In any case, do not allow the join, per se, to empty out the type.
2080         if (jt->empty() && !t->empty()) {
2081           // This can happen if a interface-typed array narrows to a class type.
2082           jt = _type;
2083         }
2084 #ifdef ASSERT
2085         if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2086           // The pointers in the autobox arrays are always non-null
2087           Node* base = adr->in(AddPNode::Base);
2088           if ((base != nullptr) && base->is_DecodeN()) {
2089             // Get LoadN node which loads IntegerCache.cache field
2090             base = base->in(1);
2091           }
2092           if ((base != nullptr) && base->is_Con()) {
2093             const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2094             if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2095               // It could be narrow oop
2096               assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2097             }
2098           }
2099         }
2100 #endif
2101         return jt;
2102       }
2103     }
2104   } else if (tp->base() == Type::InstPtr) {
2105     assert( off != Type::OffsetBot ||
2106             // arrays can be cast to Objects
2107             !tp->isa_instptr() ||
2108             tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2109             // unsafe field access may not have a constant offset
2110             C->has_unsafe_access(),
2111             "Field accesses must be precise" );
2112     // For oop loads, we expect the _type to be precise.
2113 
2114     // Optimize loads from constant fields.
2115     const TypeInstPtr* tinst = tp->is_instptr();
2116     ciObject* const_oop = tinst->const_oop();
2117     if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2118       const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), value_basic_type());
2119       if (con_type != nullptr) {
2120         return con_type;
2121       }
2122     }
2123   } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2124     assert(off != Type::OffsetBot ||
2125             !tp->isa_instklassptr() ||
2126            // arrays can be cast to Objects
2127            tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2128            // also allow array-loading from the primary supertype
2129            // array during subtype checks
2130            Opcode() == Op_LoadKlass,
2131            "Field accesses must be precise");
2132     // For klass/static loads, we expect the _type to be precise
2133   } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2134     /* With mirrors being an indirect in the Klass*
2135      * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2136      * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2137      *
2138      * So check the type and klass of the node before the LoadP.
2139      */
2140     Node* adr2 = adr->in(MemNode::Address);
2141     const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2142     if (tkls != nullptr && !StressReflectiveCode) {
2143       if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2144         ciKlass* klass = tkls->exact_klass();
2145         assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2146         assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2147         return TypeInstPtr::make(klass->java_mirror());
2148       }
2149     }
2150   }
2151 
2152   const TypeKlassPtr *tkls = tp->isa_klassptr();
2153   if (tkls != nullptr) {
2154     if (tkls->is_loaded() && tkls->klass_is_exact()) {
2155       ciKlass* klass = tkls->exact_klass();
2156       // We are loading a field from a Klass metaobject whose identity
2157       // is known at compile time (the type is "exact" or "precise").
2158       // Check for fields we know are maintained as constants by the VM.
2159       if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2160         // The field is Klass::_super_check_offset.  Return its (constant) value.
2161         // (Folds up type checking code.)
2162         assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2163         return TypeInt::make(klass->super_check_offset());
2164       }
2165       if (UseCompactObjectHeaders) {
2166         if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2167           // The field is Klass::_prototype_header. Return its (constant) value.
2168           assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2169           return TypeX::make(klass->prototype_header());
2170         }
2171       }
2172       // Compute index into primary_supers array
2173       juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2174       // Check for overflowing; use unsigned compare to handle the negative case.
2175       if( depth < ciKlass::primary_super_limit() ) {
2176         // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2177         // (Folds up type checking code.)
2178         assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2179         ciKlass *ss = klass->super_of_depth(depth);
2180         return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2181       }
2182       const Type* aift = load_array_final_field(tkls, klass);
2183       if (aift != nullptr)  return aift;
2184     }
2185 
2186     // We can still check if we are loading from the primary_supers array at a
2187     // shallow enough depth.  Even though the klass is not exact, entries less
2188     // than or equal to its super depth are correct.
2189     if (tkls->is_loaded()) {
2190       ciKlass* klass = nullptr;
2191       if (tkls->isa_instklassptr()) {
2192         klass = tkls->is_instklassptr()->instance_klass();
2193       } else {
2194         int dims;
2195         const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2196         if (inner->isa_instklassptr()) {
2197           klass = inner->is_instklassptr()->instance_klass();
2198           klass = ciObjArrayKlass::make(klass, dims);
2199         }
2200       }
2201       if (klass != nullptr) {
2202         // Compute index into primary_supers array
2203         juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2204         // Check for overflowing; use unsigned compare to handle the negative case.
2205         if (depth < ciKlass::primary_super_limit() &&
2206             depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2207           // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2208           // (Folds up type checking code.)
2209           assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2210           ciKlass *ss = klass->super_of_depth(depth);
2211           return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2212         }
2213       }
2214     }
2215 
2216     // If the type is enough to determine that the thing is not an array,
2217     // we can give the layout_helper a positive interval type.
2218     // This will help short-circuit some reflective code.
2219     if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2220         tkls->isa_instklassptr() && // not directly typed as an array
2221         !tkls->is_instklassptr()->might_be_an_array() // not the supertype of all T[] (java.lang.Object) or has an interface that is not Serializable or Cloneable
2222     ) {
2223       assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2224       jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2225       // The key property of this type is that it folds up tests
2226       // for array-ness, since it proves that the layout_helper is positive.
2227       // Thus, a generic value like the basic object layout helper works fine.
2228       return TypeInt::make(min_size, max_jint, Type::WidenMin);
2229     }
2230   }
2231 
2232   bool is_vect = (_type->isa_vect() != nullptr);
2233   if (is_instance && !is_vect) {
2234     // If we have an instance type and our memory input is the
2235     // programs's initial memory state, there is no matching store,
2236     // so just return a zero of the appropriate type -
2237     // except if it is vectorized - then we have no zero constant.
2238     Node *mem = in(MemNode::Memory);
2239     if (mem->is_Parm() && mem->in(0)->is_Start()) {
2240       assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2241       return Type::get_zero_type(_type->basic_type());
2242     }
2243   }
2244 
2245   if (!UseCompactObjectHeaders) {
2246     Node* alloc = is_new_object_mark_load();
2247     if (alloc != nullptr) {
2248       return TypeX::make(markWord::prototype().value());
2249     }
2250   }
2251 
2252   return _type;
2253 }
2254 
2255 //------------------------------match_edge-------------------------------------
2256 // Do we Match on this edge index or not?  Match only the address.
2257 uint LoadNode::match_edge(uint idx) const {
2258   return idx == MemNode::Address;
2259 }
2260 
2261 //--------------------------LoadBNode::Ideal--------------------------------------
2262 //
2263 //  If the previous store is to the same address as this load,
2264 //  and the value stored was larger than a byte, replace this load
2265 //  with the value stored truncated to a byte.  If no truncation is
2266 //  needed, the replacement is done in LoadNode::Identity().
2267 //
2268 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2269   Node* mem = in(MemNode::Memory);
2270   Node* value = can_see_stored_value(mem,phase);
2271   if (value != nullptr) {
2272     Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2273     if (narrow != value) {
2274       return narrow;
2275     }
2276   }
2277   // Identity call will handle the case where truncation is not needed.
2278   return LoadNode::Ideal(phase, can_reshape);
2279 }
2280 
2281 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2282   Node* mem = in(MemNode::Memory);
2283   Node* value = can_see_stored_value(mem,phase);
2284   if (value != nullptr && value->is_Con() &&
2285       !value->bottom_type()->higher_equal(_type)) {
2286     // If the input to the store does not fit with the load's result type,
2287     // it must be truncated. We can't delay until Ideal call since
2288     // a singleton Value is needed for split_thru_phi optimization.
2289     int con = value->get_int();
2290     return TypeInt::make((con << 24) >> 24);
2291   }
2292   return LoadNode::Value(phase);
2293 }
2294 
2295 //--------------------------LoadUBNode::Ideal-------------------------------------
2296 //
2297 //  If the previous store is to the same address as this load,
2298 //  and the value stored was larger than a byte, replace this load
2299 //  with the value stored truncated to a byte.  If no truncation is
2300 //  needed, the replacement is done in LoadNode::Identity().
2301 //
2302 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2303   Node* mem = in(MemNode::Memory);
2304   Node* value = can_see_stored_value(mem, phase);
2305   if (value != nullptr) {
2306     Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2307     if (narrow != value) {
2308       return narrow;
2309     }
2310   }
2311   // Identity call will handle the case where truncation is not needed.
2312   return LoadNode::Ideal(phase, can_reshape);
2313 }
2314 
2315 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2316   Node* mem = in(MemNode::Memory);
2317   Node* value = can_see_stored_value(mem,phase);
2318   if (value != nullptr && value->is_Con() &&
2319       !value->bottom_type()->higher_equal(_type)) {
2320     // If the input to the store does not fit with the load's result type,
2321     // it must be truncated. We can't delay until Ideal call since
2322     // a singleton Value is needed for split_thru_phi optimization.
2323     int con = value->get_int();
2324     return TypeInt::make(con & 0xFF);
2325   }
2326   return LoadNode::Value(phase);
2327 }
2328 
2329 //--------------------------LoadUSNode::Ideal-------------------------------------
2330 //
2331 //  If the previous store is to the same address as this load,
2332 //  and the value stored was larger than a char, replace this load
2333 //  with the value stored truncated to a char.  If no truncation is
2334 //  needed, the replacement is done in LoadNode::Identity().
2335 //
2336 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2337   Node* mem = in(MemNode::Memory);
2338   Node* value = can_see_stored_value(mem,phase);
2339   if (value != nullptr) {
2340     Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2341     if (narrow != value) {
2342       return narrow;
2343     }
2344   }
2345   // Identity call will handle the case where truncation is not needed.
2346   return LoadNode::Ideal(phase, can_reshape);
2347 }
2348 
2349 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2350   Node* mem = in(MemNode::Memory);
2351   Node* value = can_see_stored_value(mem,phase);
2352   if (value != nullptr && value->is_Con() &&
2353       !value->bottom_type()->higher_equal(_type)) {
2354     // If the input to the store does not fit with the load's result type,
2355     // it must be truncated. We can't delay until Ideal call since
2356     // a singleton Value is needed for split_thru_phi optimization.
2357     int con = value->get_int();
2358     return TypeInt::make(con & 0xFFFF);
2359   }
2360   return LoadNode::Value(phase);
2361 }
2362 
2363 //--------------------------LoadSNode::Ideal--------------------------------------
2364 //
2365 //  If the previous store is to the same address as this load,
2366 //  and the value stored was larger than a short, replace this load
2367 //  with the value stored truncated to a short.  If no truncation is
2368 //  needed, the replacement is done in LoadNode::Identity().
2369 //
2370 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2371   Node* mem = in(MemNode::Memory);
2372   Node* value = can_see_stored_value(mem,phase);
2373   if (value != nullptr) {
2374     Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2375     if (narrow != value) {
2376       return narrow;
2377     }
2378   }
2379   // Identity call will handle the case where truncation is not needed.
2380   return LoadNode::Ideal(phase, can_reshape);
2381 }
2382 
2383 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2384   Node* mem = in(MemNode::Memory);
2385   Node* value = can_see_stored_value(mem,phase);
2386   if (value != nullptr && value->is_Con() &&
2387       !value->bottom_type()->higher_equal(_type)) {
2388     // If the input to the store does not fit with the load's result type,
2389     // it must be truncated. We can't delay until Ideal call since
2390     // a singleton Value is needed for split_thru_phi optimization.
2391     int con = value->get_int();
2392     return TypeInt::make((con << 16) >> 16);
2393   }
2394   return LoadNode::Value(phase);
2395 }
2396 
2397 //=============================================================================
2398 //----------------------------LoadKlassNode::make------------------------------
2399 // Polymorphic factory method:
2400 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2401   // sanity check the alias category against the created node type
2402   const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2403   assert(adr_type != nullptr, "expecting TypeKlassPtr");
2404 #ifdef _LP64
2405   if (adr_type->is_ptr_to_narrowklass()) {
2406     assert(UseCompressedClassPointers, "no compressed klasses");
2407     Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2408     return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2409   }
2410 #endif
2411   assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2412   return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2413 }
2414 
2415 //------------------------------Value------------------------------------------
2416 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2417   return klass_value_common(phase);
2418 }
2419 
2420 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2421   // Either input is TOP ==> the result is TOP
2422   const Type *t1 = phase->type( in(MemNode::Memory) );
2423   if (t1 == Type::TOP)  return Type::TOP;
2424   Node *adr = in(MemNode::Address);
2425   const Type *t2 = phase->type( adr );
2426   if (t2 == Type::TOP)  return Type::TOP;
2427   const TypePtr *tp = t2->is_ptr();
2428   if (TypePtr::above_centerline(tp->ptr()) ||
2429       tp->ptr() == TypePtr::Null)  return Type::TOP;
2430 
2431   // Return a more precise klass, if possible
2432   const TypeInstPtr *tinst = tp->isa_instptr();
2433   if (tinst != nullptr) {
2434     ciInstanceKlass* ik = tinst->instance_klass();
2435     int offset = tinst->offset();
2436     if (ik == phase->C->env()->Class_klass()
2437         && (offset == java_lang_Class::klass_offset() ||
2438             offset == java_lang_Class::array_klass_offset())) {
2439       // We are loading a special hidden field from a Class mirror object,
2440       // the field which points to the VM's Klass metaobject.
2441       ciType* t = tinst->java_mirror_type();
2442       // java_mirror_type returns non-null for compile-time Class constants.
2443       if (t != nullptr) {
2444         // constant oop => constant klass
2445         if (offset == java_lang_Class::array_klass_offset()) {
2446           if (t->is_void()) {
2447             // We cannot create a void array.  Since void is a primitive type return null
2448             // klass.  Users of this result need to do a null check on the returned klass.
2449             return TypePtr::NULL_PTR;
2450           }
2451           return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2452         }
2453         if (!t->is_klass()) {
2454           // a primitive Class (e.g., int.class) has null for a klass field
2455           return TypePtr::NULL_PTR;
2456         }
2457         // Fold up the load of the hidden field
2458         return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2459       }
2460       // non-constant mirror, so we can't tell what's going on
2461     }
2462     if (!tinst->is_loaded())
2463       return _type;             // Bail out if not loaded
2464     if (offset == Type::klass_offset()) {
2465       return tinst->as_klass_type(true);
2466     }
2467   }
2468 
2469   // Check for loading klass from an array
2470   const TypeAryPtr *tary = tp->isa_aryptr();
2471   if (tary != nullptr &&
2472       tary->offset() == Type::klass_offset()) {
2473     return tary->as_klass_type(true);
2474   }
2475 
2476   // Check for loading klass from an array klass
2477   const TypeKlassPtr *tkls = tp->isa_klassptr();
2478   if (tkls != nullptr && !StressReflectiveCode) {
2479     if (!tkls->is_loaded())
2480      return _type;             // Bail out if not loaded
2481     if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2482         tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2483       // // Always returning precise element type is incorrect,
2484       // // e.g., element type could be object and array may contain strings
2485       // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2486 
2487       // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2488       // according to the element type's subclassing.
2489       return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2490     }
2491     if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2492         tkls->offset() == in_bytes(Klass::super_offset())) {
2493       ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2494       // The field is Klass::_super.  Return its (constant) value.
2495       // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2496       return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2497     }
2498   }
2499 
2500   if (tkls != nullptr && !UseSecondarySupersCache
2501       && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset()))  {
2502     // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2503     return TypePtr::NULL_PTR;
2504   }
2505 
2506   // Bailout case
2507   return LoadNode::Value(phase);
2508 }
2509 
2510 //------------------------------Identity---------------------------------------
2511 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2512 // Also feed through the klass in Allocate(...klass...)._klass.
2513 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2514   return klass_identity_common(phase);
2515 }
2516 
2517 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2518   Node* x = LoadNode::Identity(phase);
2519   if (x != this)  return x;
2520 
2521   // Take apart the address into an oop and offset.
2522   // Return 'this' if we cannot.
2523   Node*    adr    = in(MemNode::Address);
2524   intptr_t offset = 0;
2525   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2526   if (base == nullptr)     return this;
2527   const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2528   if (toop == nullptr)     return this;
2529 
2530   // Step over potential GC barrier for OopHandle resolve
2531   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2532   if (bs->is_gc_barrier_node(base)) {
2533     base = bs->step_over_gc_barrier(base);
2534   }
2535 
2536   // We can fetch the klass directly through an AllocateNode.
2537   // This works even if the klass is not constant (clone or newArray).
2538   if (offset == Type::klass_offset()) {
2539     Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2540     if (allocated_klass != nullptr) {
2541       return allocated_klass;
2542     }
2543   }
2544 
2545   // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2546   // See inline_native_Class_query for occurrences of these patterns.
2547   // Java Example:  x.getClass().isAssignableFrom(y)
2548   //
2549   // This improves reflective code, often making the Class
2550   // mirror go completely dead.  (Current exception:  Class
2551   // mirrors may appear in debug info, but we could clean them out by
2552   // introducing a new debug info operator for Klass.java_mirror).
2553 
2554   if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2555       && offset == java_lang_Class::klass_offset()) {
2556     if (base->is_Load()) {
2557       Node* base2 = base->in(MemNode::Address);
2558       if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2559         Node* adr2 = base2->in(MemNode::Address);
2560         const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2561         if (tkls != nullptr && !tkls->empty()
2562             && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2563             && adr2->is_AddP()
2564            ) {
2565           int mirror_field = in_bytes(Klass::java_mirror_offset());
2566           if (tkls->offset() == mirror_field) {
2567             return adr2->in(AddPNode::Base);
2568           }
2569         }
2570       }
2571     }
2572   }
2573 
2574   return this;
2575 }
2576 
2577 LoadNode* LoadNode::clone_pinned() const {
2578   LoadNode* ld = clone()->as_Load();
2579   ld->_control_dependency = UnknownControl;
2580   return ld;
2581 }
2582 
2583 
2584 //------------------------------Value------------------------------------------
2585 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2586   const Type *t = klass_value_common(phase);
2587   if (t == Type::TOP)
2588     return t;
2589 
2590   return t->make_narrowklass();
2591 }
2592 
2593 //------------------------------Identity---------------------------------------
2594 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2595 // Also feed through the klass in Allocate(...klass...)._klass.
2596 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2597   Node *x = klass_identity_common(phase);
2598 
2599   const Type *t = phase->type( x );
2600   if( t == Type::TOP ) return x;
2601   if( t->isa_narrowklass()) return x;
2602   assert (!t->isa_narrowoop(), "no narrow oop here");
2603 
2604   return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2605 }
2606 
2607 //------------------------------Value-----------------------------------------
2608 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2609   // Either input is TOP ==> the result is TOP
2610   const Type *t1 = phase->type( in(MemNode::Memory) );
2611   if( t1 == Type::TOP ) return Type::TOP;
2612   Node *adr = in(MemNode::Address);
2613   const Type *t2 = phase->type( adr );
2614   if( t2 == Type::TOP ) return Type::TOP;
2615   const TypePtr *tp = t2->is_ptr();
2616   if (TypePtr::above_centerline(tp->ptr()))  return Type::TOP;
2617   const TypeAryPtr *tap = tp->isa_aryptr();
2618   if( !tap ) return _type;
2619   return tap->size();
2620 }
2621 
2622 //-------------------------------Ideal---------------------------------------
2623 // Feed through the length in AllocateArray(...length...)._length.
2624 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2625   Node* p = MemNode::Ideal_common(phase, can_reshape);
2626   if (p)  return (p == NodeSentinel) ? nullptr : p;
2627 
2628   // Take apart the address into an oop and offset.
2629   // Return 'this' if we cannot.
2630   Node*    adr    = in(MemNode::Address);
2631   intptr_t offset = 0;
2632   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase,  offset);
2633   if (base == nullptr)     return nullptr;
2634   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2635   if (tary == nullptr)     return nullptr;
2636 
2637   // We can fetch the length directly through an AllocateArrayNode.
2638   // This works even if the length is not constant (clone or newArray).
2639   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2640     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2641     if (alloc != nullptr) {
2642       Node* allocated_length = alloc->Ideal_length();
2643       Node* len = alloc->make_ideal_length(tary, phase);
2644       if (allocated_length != len) {
2645         // New CastII improves on this.
2646         return len;
2647       }
2648     }
2649   }
2650 
2651   return nullptr;
2652 }
2653 
2654 //------------------------------Identity---------------------------------------
2655 // Feed through the length in AllocateArray(...length...)._length.
2656 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2657   Node* x = LoadINode::Identity(phase);
2658   if (x != this)  return x;
2659 
2660   // Take apart the address into an oop and offset.
2661   // Return 'this' if we cannot.
2662   Node*    adr    = in(MemNode::Address);
2663   intptr_t offset = 0;
2664   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2665   if (base == nullptr)     return this;
2666   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2667   if (tary == nullptr)     return this;
2668 
2669   // We can fetch the length directly through an AllocateArrayNode.
2670   // This works even if the length is not constant (clone or newArray).
2671   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2672     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2673     if (alloc != nullptr) {
2674       Node* allocated_length = alloc->Ideal_length();
2675       // Do not allow make_ideal_length to allocate a CastII node.
2676       Node* len = alloc->make_ideal_length(tary, phase, false);
2677       if (allocated_length == len) {
2678         // Return allocated_length only if it would not be improved by a CastII.
2679         return allocated_length;
2680       }
2681     }
2682   }
2683 
2684   return this;
2685 
2686 }
2687 
2688 //=============================================================================
2689 //---------------------------StoreNode::make-----------------------------------
2690 // Polymorphic factory method:
2691 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo, bool require_atomic_access) {
2692   assert((mo == unordered || mo == release), "unexpected");
2693   Compile* C = gvn.C;
2694   assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2695          ctl != nullptr, "raw memory operations should have control edge");
2696 
2697   switch (bt) {
2698   case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2699   case T_BYTE:    return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2700   case T_INT:     return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2701   case T_CHAR:
2702   case T_SHORT:   return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2703   case T_LONG:    return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2704   case T_FLOAT:   return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2705   case T_DOUBLE:  return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2706   case T_METADATA:
2707   case T_ADDRESS:
2708   case T_OBJECT:
2709 #ifdef _LP64
2710     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2711       val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2712       return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2713     } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2714                (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2715                 adr->bottom_type()->isa_rawptr())) {
2716       val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2717       return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2718     }
2719 #endif
2720     {
2721       return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2722     }
2723   default:
2724     ShouldNotReachHere();
2725     return (StoreNode*)nullptr;
2726   }
2727 }
2728 
2729 //--------------------------bottom_type----------------------------------------
2730 const Type *StoreNode::bottom_type() const {
2731   return Type::MEMORY;
2732 }
2733 
2734 //------------------------------hash-------------------------------------------
2735 uint StoreNode::hash() const {
2736   // unroll addition of interesting fields
2737   //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2738 
2739   // Since they are not commoned, do not hash them:
2740   return NO_HASH;
2741 }
2742 
2743 // Link together multiple stores (B/S/C/I) into a longer one.
2744 //
2745 // Example: _store = StoreB[i+3]
2746 //
2747 //   RangeCheck[i+0]           RangeCheck[i+0]
2748 //   StoreB[i+0]
2749 //   RangeCheck[i+3]           RangeCheck[i+3]
2750 //   StoreB[i+1]         -->   pass:             fail:
2751 //   StoreB[i+2]               StoreI[i+0]       StoreB[i+0]
2752 //   StoreB[i+3]
2753 //
2754 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2755 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2756 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2757 // failing path.
2758 //
2759 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2760 //       - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2761 //                                       and possibly no RangeChecks remain between the stores.
2762 //       - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2763 //                              and those later RangeChecks can be removed. Example:
2764 //
2765 //                              RangeCheck[i+0]                         RangeCheck[i+0] <- before first store
2766 //                              StoreB[i+0]                             StoreB[i+0]     <- first store
2767 //                              RangeCheck[i+1]     --> smeared -->     RangeCheck[i+3] <- only RC between first and last store
2768 //                              StoreB[i+1]                             StoreB[i+1]     <- second store
2769 //                              RangeCheck[i+2]     --> removed
2770 //                              StoreB[i+2]                             StoreB[i+2]
2771 //                              RangeCheck[i+3]     --> removed
2772 //                              StoreB[i+3]                             StoreB[i+3]     <- last store
2773 //
2774 //                              Thus, it is a common pattern that between the first and last store in a chain
2775 //                              of adjacent stores there remains exactly one RangeCheck, located between the
2776 //                              first and the second store (e.g. RangeCheck[i+3]).
2777 //
2778 class MergePrimitiveStores : public StackObj {
2779 private:
2780   PhaseGVN* const _phase;
2781   StoreNode* const _store;
2782   // State machine with initial state Unknown
2783   // Allowed transitions:
2784   //   Unknown     -> Const
2785   //   Unknown     -> Platform
2786   //   Unknown     -> Reverse
2787   //   Unknown     -> NotAdjacent
2788   //   Const       -> Const
2789   //   Const       -> NotAdjacent
2790   //   Platform    -> Platform
2791   //   Platform    -> NotAdjacent
2792   //   Reverse     -> Reverse
2793   //   Reverse     -> NotAdjacent
2794   //   NotAdjacent -> NotAdjacent
2795   enum ValueOrder : uint8_t {
2796     Unknown,     // Initial state
2797     Const,       // Input values are const
2798     Platform,    // Platform order
2799     Reverse,     // Reverse platform order
2800     NotAdjacent  // Not adjacent
2801   };
2802   ValueOrder  _value_order;
2803 
2804   NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
2805 
2806 public:
2807   MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
2808     _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
2809     NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
2810     {}
2811 
2812   StoreNode* run();
2813 
2814 private:
2815   bool is_compatible_store(const StoreNode* other_store) const;
2816   bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
2817   bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
2818   static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
2819   enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
2820   static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
2821 
2822   class Status {
2823   private:
2824     StoreNode* _found_store;
2825     bool       _found_range_check;
2826 
2827     Status(StoreNode* found_store, bool found_range_check)
2828       : _found_store(found_store), _found_range_check(found_range_check) {}
2829 
2830   public:
2831     StoreNode* found_store() const { return _found_store; }
2832     bool found_range_check() const { return _found_range_check; }
2833     static Status make_failure() { return Status(nullptr, false); }
2834 
2835     static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
2836       if (cfg_status == CFGStatus::Failure) {
2837         return Status::make_failure();
2838       }
2839       return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
2840     }
2841 
2842 #ifndef PRODUCT
2843     void print_on(outputStream* st) const {
2844       if (_found_store == nullptr) {
2845         st->print_cr("None");
2846       } else {
2847         st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
2848                                          _found_range_check ? "RC" : "no-RC");
2849       }
2850     }
2851 #endif
2852   };
2853 
2854   enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
2855   Status find_adjacent_use_store(const StoreNode* def_store) const;
2856   Status find_adjacent_def_store(const StoreNode* use_store) const;
2857   Status find_use_store(const StoreNode* def_store) const;
2858   Status find_def_store(const StoreNode* use_store) const;
2859   Status find_use_store_unidirectional(const StoreNode* def_store) const;
2860   Status find_def_store_unidirectional(const StoreNode* use_store) const;
2861 
2862   void collect_merge_list(Node_List& merge_list) const;
2863   Node* make_merged_input_value(const Node_List& merge_list);
2864   StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
2865 
2866 #ifndef PRODUCT
2867   // Access to TraceMergeStores tags
2868   bool is_trace(TraceMergeStores::Tag tag) const {
2869     return _trace_tags.at(tag);
2870   }
2871 
2872   bool is_trace_basic() const {
2873     return is_trace(TraceMergeStores::Tag::BASIC);
2874   }
2875 
2876   bool is_trace_pointer_parsing() const {
2877     return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
2878   }
2879 
2880   bool is_trace_pointer_aliasing() const {
2881     return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
2882   }
2883 
2884   bool is_trace_pointer_adjacency() const {
2885     return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
2886   }
2887 
2888   bool is_trace_success() const {
2889     return is_trace(TraceMergeStores::Tag::SUCCESS);
2890   }
2891 #endif
2892 
2893   NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
2894 };
2895 
2896 StoreNode* MergePrimitiveStores::run() {
2897   // Check for B/S/C/I
2898   int opc = _store->Opcode();
2899   if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
2900     return nullptr;
2901   }
2902 
2903   NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
2904 
2905   // The _store must be the "last" store in a chain. If we find a use we could merge with
2906   // then that use or a store further down is the "last" store.
2907   Status status_use = find_adjacent_use_store(_store);
2908   NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
2909   if (status_use.found_store() != nullptr) {
2910     return nullptr;
2911   }
2912 
2913   // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
2914   Status status_def = find_adjacent_def_store(_store);
2915   NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
2916   Node* def_store = status_def.found_store();
2917   if (def_store == nullptr) {
2918     return nullptr;
2919   }
2920 
2921   // Initialize value order
2922   _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
2923                                                  _store->in(MemNode::ValueIn),
2924                                                  _store->memory_size());
2925   assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
2926 
2927   ResourceMark rm;
2928   Node_List merge_list;
2929   collect_merge_list(merge_list);
2930 
2931   Node* merged_input_value = make_merged_input_value(merge_list);
2932   if (merged_input_value == nullptr) { return nullptr; }
2933 
2934   StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
2935 
2936   NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
2937 
2938   return merged_store;
2939 }
2940 
2941 // Check compatibility between _store and other_store.
2942 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
2943   int opc = _store->Opcode();
2944   assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
2945 
2946   if (other_store == nullptr ||
2947       _store->Opcode() != other_store->Opcode()) {
2948     return false;
2949   }
2950 
2951   return true;
2952 }
2953 
2954 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
2955   if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
2956                               use_store->in(MemNode::ValueIn),
2957                               def_store->memory_size())) {
2958     return false;
2959   }
2960 
2961   ResourceMark rm;
2962 #ifndef PRODUCT
2963   const TraceMemPointer trace(is_trace_pointer_parsing(),
2964                               is_trace_pointer_aliasing(),
2965                               is_trace_pointer_adjacency(),
2966                               true);
2967 #endif
2968   const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
2969   const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
2970   return pointer_def.is_adjacent_to_and_before(pointer_use);
2971 }
2972 
2973 // Check input values n1 and n2 can be merged and return the value order
2974 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
2975                                                                                        const int memory_size) const {
2976   // Pattern: [n1 = ConI, n2 = ConI]
2977   if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
2978     return ValueOrder::Const;
2979   }
2980 
2981   Node const *base_n2;
2982   jint shift_n2;
2983   if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
2984     return ValueOrder::NotAdjacent;
2985   }
2986   Node const *base_n1;
2987   jint shift_n1;
2988   if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
2989     return ValueOrder::NotAdjacent;
2990   }
2991 
2992   int bits_per_store = memory_size * 8;
2993   if (base_n1 != base_n2 ||
2994       abs(shift_n1 - shift_n2) != bits_per_store ||
2995       shift_n1 % bits_per_store != 0) {
2996     // Values are not adjacent
2997     return ValueOrder::NotAdjacent;
2998   }
2999 
3000   // Detect value order
3001 #ifdef VM_LITTLE_ENDIAN
3002   return shift_n1 < shift_n2 ? ValueOrder::Platform     // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3003                              : ValueOrder::Reverse;     // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3004 #else
3005   return shift_n1 > shift_n2 ? ValueOrder::Platform     // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3006                              : ValueOrder::Reverse;     // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3007 #endif
3008 }
3009 
3010 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3011   ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3012 
3013   switch (input_value_order) {
3014     case ValueOrder::NotAdjacent:
3015       return false;
3016     case ValueOrder::Reverse:
3017       if (memory_size != 1 ||
3018           !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3019           !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3020           !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3021         // ReverseBytes are not supported by platform
3022         return false;
3023       }
3024       // fall-through.
3025     case ValueOrder::Const:
3026     case ValueOrder::Platform:
3027       if (_value_order == ValueOrder::Unknown) {
3028         // Initial state is Unknown, and we find a valid input value order
3029         return true;
3030       }
3031       // The value order can not be changed
3032       return _value_order == input_value_order;
3033     case ValueOrder::Unknown:
3034     default:
3035       ShouldNotReachHere();
3036   }
3037   return false;
3038 }
3039 
3040 // Detect pattern: n = base_out >> shift_out
3041 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3042   assert(n != nullptr, "precondition");
3043 
3044   int opc = n->Opcode();
3045   if (opc == Op_ConvL2I) {
3046     n = n->in(1);
3047     opc = n->Opcode();
3048   }
3049 
3050   if ((opc == Op_RShiftI ||
3051        opc == Op_RShiftL ||
3052        opc == Op_URShiftI ||
3053        opc == Op_URShiftL) &&
3054       n->in(2)->is_ConI()) {
3055     base_out = n->in(1);
3056     shift_out = n->in(2)->get_int();
3057     // The shift must be positive:
3058     return shift_out >= 0;
3059   }
3060 
3061   if (phase->type(n)->isa_int()  != nullptr ||
3062       phase->type(n)->isa_long() != nullptr) {
3063     // (base >> 0)
3064     base_out = n;
3065     shift_out = 0;
3066     return true;
3067   }
3068   return false;
3069 }
3070 
3071 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3072 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3073   assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3074 
3075   Node* ctrl_use = use_store->in(MemNode::Control);
3076   Node* ctrl_def = def_store->in(MemNode::Control);
3077   if (ctrl_use == nullptr || ctrl_def == nullptr) {
3078     return CFGStatus::Failure;
3079   }
3080 
3081   if (ctrl_use == ctrl_def) {
3082     // Same ctrl -> no RangeCheck in between.
3083     // Check: use_store must be the only use of def_store.
3084     if (def_store->outcnt() > 1) {
3085       return CFGStatus::Failure;
3086     }
3087     return CFGStatus::SuccessNoRangeCheck;
3088   }
3089 
3090   // Different ctrl -> could have RangeCheck in between.
3091   // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3092   //        2. ctrl separated by RangeCheck.
3093   if (def_store->outcnt() != 2) {
3094     return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3095   }
3096   int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3097   Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3098   if (merge_mem == nullptr ||
3099       merge_mem->outcnt() != 1) {
3100     return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3101   }
3102   if (!ctrl_use->is_IfProj() ||
3103       !ctrl_use->in(0)->is_RangeCheck() ||
3104       ctrl_use->in(0)->outcnt() != 2) {
3105     return CFGStatus::Failure; // Not RangeCheck.
3106   }
3107   ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3108   Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3109   if (trap != merge_mem->unique_out() ||
3110       ctrl_use->in(0)->in(0) != ctrl_def) {
3111     return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3112   }
3113 
3114   return CFGStatus::SuccessWithRangeCheck;
3115 }
3116 
3117 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3118   Status status_use = find_use_store(def_store);
3119   StoreNode* use_store = status_use.found_store();
3120   if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3121     return Status::make_failure();
3122   }
3123   return status_use;
3124 }
3125 
3126 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3127   Status status_def = find_def_store(use_store);
3128   StoreNode* def_store = status_def.found_store();
3129   if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3130     return Status::make_failure();
3131   }
3132   return status_def;
3133 }
3134 
3135 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3136   Status status_use = find_use_store_unidirectional(def_store);
3137 
3138 #ifdef ASSERT
3139   StoreNode* use_store = status_use.found_store();
3140   if (use_store != nullptr) {
3141     Status status_def = find_def_store_unidirectional(use_store);
3142     assert(status_def.found_store() == def_store &&
3143            status_def.found_range_check() == status_use.found_range_check(),
3144            "find_use_store and find_def_store must be symmetric");
3145   }
3146 #endif
3147 
3148   return status_use;
3149 }
3150 
3151 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3152   Status status_def = find_def_store_unidirectional(use_store);
3153 
3154 #ifdef ASSERT
3155   StoreNode* def_store = status_def.found_store();
3156   if (def_store != nullptr) {
3157     Status status_use = find_use_store_unidirectional(def_store);
3158     assert(status_use.found_store() == use_store &&
3159            status_use.found_range_check() == status_def.found_range_check(),
3160            "find_use_store and find_def_store must be symmetric");
3161   }
3162 #endif
3163 
3164   return status_def;
3165 }
3166 
3167 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3168   assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3169 
3170   for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3171     StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3172     if (is_compatible_store(use_store)) {
3173       return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3174     }
3175   }
3176 
3177   return Status::make_failure();
3178 }
3179 
3180 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3181   assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3182 
3183   StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3184   if (!is_compatible_store(def_store)) {
3185     return Status::make_failure();
3186   }
3187 
3188   return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3189 }
3190 
3191 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3192   // The merged store can be at most 8 bytes.
3193   const uint merge_list_max_size = 8 / _store->memory_size();
3194   assert(merge_list_max_size >= 2 &&
3195          merge_list_max_size <= 8 &&
3196          is_power_of_2(merge_list_max_size),
3197          "must be 2, 4 or 8");
3198 
3199   // Traverse up the chain of adjacent def stores.
3200   StoreNode* current = _store;
3201   merge_list.push(current);
3202   while (current != nullptr && merge_list.size() < merge_list_max_size) {
3203     Status status = find_adjacent_def_store(current);
3204     NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3205 
3206     current = status.found_store();
3207     if (current != nullptr) {
3208       merge_list.push(current);
3209 
3210       // We can have at most one RangeCheck.
3211       if (status.found_range_check()) {
3212         NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3213         break;
3214       }
3215     }
3216   }
3217 
3218   NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3219 
3220   // Truncate the merge_list to a power of 2.
3221   const uint pow2size = round_down_power_of_2(merge_list.size());
3222   assert(pow2size >= 2, "must be merging at least 2 stores");
3223   while (merge_list.size() > pow2size) { merge_list.pop(); }
3224 
3225   NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3226 }
3227 
3228 // Merge the input values of the smaller stores to a single larger input value.
3229 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3230   int new_memory_size = _store->memory_size() * merge_list.size();
3231   Node* first = merge_list.at(merge_list.size()-1);
3232   Node* merged_input_value = nullptr;
3233   if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3234     assert(_value_order == ValueOrder::Const, "must match");
3235     // Pattern: [ConI, ConI, ...] -> new constant
3236     jlong con = 0;
3237     jlong bits_per_store = _store->memory_size() * 8;
3238     jlong mask = (((jlong)1) << bits_per_store) - 1;
3239     for (uint i = 0; i < merge_list.size(); i++) {
3240       jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3241 #ifdef VM_LITTLE_ENDIAN
3242       con = con << bits_per_store;
3243       con = con | (mask & con_i);
3244 #else // VM_LITTLE_ENDIAN
3245       con_i = (mask & con_i) << (i * bits_per_store);
3246       con = con | con_i;
3247 #endif // VM_LITTLE_ENDIAN
3248     }
3249     merged_input_value = _phase->longcon(con);
3250   } else {
3251     assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3252     // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3253     //             |                                  |
3254     //           _store                             first
3255     //
3256     Node* hi = _store->in(MemNode::ValueIn);
3257     Node* lo = first->in(MemNode::ValueIn);
3258 #ifndef VM_LITTLE_ENDIAN
3259     // `_store` and `first` are swapped in the diagram above
3260     swap(hi, lo);
3261 #endif // !VM_LITTLE_ENDIAN
3262     if (_value_order == ValueOrder::Reverse) {
3263       swap(hi, lo);
3264     }
3265     Node const* hi_base;
3266     jint hi_shift;
3267     merged_input_value = lo;
3268     bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3269     assert(is_true, "must detect con RShift");
3270     if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3271       // look through
3272       merged_input_value = merged_input_value->in(1);
3273     }
3274     if (merged_input_value != hi_base) {
3275       // merged_input_value is not the base
3276       return nullptr;
3277     }
3278   }
3279 
3280   if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3281     // Example:
3282     //
3283     //   long base = ...;
3284     //   a[0] = (byte)(base >> 0);
3285     //   a[1] = (byte)(base >> 8);
3286     //
3287     merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3288   }
3289 
3290   assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3291          (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3292          "merged_input_value is either int or long, and new_memory_size is small enough");
3293 
3294   if (_value_order == ValueOrder::Reverse) {
3295     assert(_store->memory_size() == 1, "only implemented for bytes");
3296     if (new_memory_size == 8) {
3297       merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3298     } else if (new_memory_size == 4) {
3299       merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3300     } else {
3301       assert(new_memory_size == 2, "sanity check");
3302       merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3303     }
3304   }
3305   return merged_input_value;
3306 }
3307 
3308 //                                                                                                          //
3309 // first_ctrl    first_mem   first_adr                first_ctrl    first_mem         first_adr             //
3310 //  |                |           |                     |                |                 |                 //
3311 //  |                |           |                     |                +---------------+ |                 //
3312 //  |                |           |                     |                |               | |                 //
3313 //  |                | +---------+                     |                | +---------------+                 //
3314 //  |                | |                               |                | |             | |                 //
3315 //  +--------------+ | |  v1                           +------------------------------+ | |  v1             //
3316 //  |              | | |  |                            |                | |           | | |  |              //
3317 // RangeCheck     first_store                         RangeCheck        | |          first_store            //
3318 //  |                |  |                              |                | |                |                //
3319 // last_ctrl         |  +----> unc_trap               last_ctrl         | |                +----> unc_trap  //
3320 //  |                |                       ===>      |                | |                                 //
3321 //  +--------------+ | a2 v2                           |                | |                                 //
3322 //  |              | | |  |                            |                | |                                 //
3323 //  |             second_store                         |                | |                                 //
3324 //  |                |                                 |                | | [v1 v2   ...   vn]              //
3325 // ...              ...                                |                | |         |                       //
3326 //  |                |                                 |                | |         v                       //
3327 //  +--------------+ | an vn                           +--------------+ | | merged_input_value              //
3328 //                 | | |  |                                           | | |  |                              //
3329 //                last_store (= _store)                              merged_store                           //
3330 //                                                                                                          //
3331 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3332   Node* first_store = merge_list.at(merge_list.size()-1);
3333   Node* last_ctrl   = _store->in(MemNode::Control); // after (optional) RangeCheck
3334   Node* first_mem   = first_store->in(MemNode::Memory);
3335   Node* first_adr   = first_store->in(MemNode::Address);
3336 
3337   const TypePtr* new_adr_type = _store->adr_type();
3338 
3339   int new_memory_size = _store->memory_size() * merge_list.size();
3340   BasicType bt = T_ILLEGAL;
3341   switch (new_memory_size) {
3342     case 2: bt = T_SHORT; break;
3343     case 4: bt = T_INT;   break;
3344     case 8: bt = T_LONG;  break;
3345   }
3346 
3347   StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3348                                             new_adr_type, merged_input_value, bt, MemNode::unordered);
3349 
3350   // Marking the store mismatched is sufficient to prevent reordering, since array stores
3351   // are all on the same slice. Hence, we need no barriers.
3352   merged_store->set_mismatched_access();
3353 
3354   // Constants above may now also be be packed -> put candidate on worklist
3355   _phase->is_IterGVN()->_worklist.push(first_mem);
3356 
3357   return merged_store;
3358 }
3359 
3360 #ifndef PRODUCT
3361 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3362   stringStream ss;
3363   ss.print_cr("[TraceMergeStores]: Replace");
3364   for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3365     merge_list.at(i)->dump("\n", false, &ss);
3366   }
3367   ss.print_cr("[TraceMergeStores]: with");
3368   merged_input_value->dump("\n", false, &ss);
3369   merged_store->dump("\n", false, &ss);
3370   tty->print("%s", ss.as_string());
3371 }
3372 #endif
3373 
3374 //------------------------------Ideal------------------------------------------
3375 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3376 // When a store immediately follows a relevant allocation/initialization,
3377 // try to capture it into the initialization, or hoist it above.
3378 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3379   Node* p = MemNode::Ideal_common(phase, can_reshape);
3380   if (p)  return (p == NodeSentinel) ? nullptr : p;
3381 
3382   Node* mem     = in(MemNode::Memory);
3383   Node* address = in(MemNode::Address);
3384   Node* value   = in(MemNode::ValueIn);
3385   // Back-to-back stores to same address?  Fold em up.  Generally
3386   // unsafe if I have intervening uses.
3387   {
3388     Node* st = mem;
3389     // If Store 'st' has more than one use, we cannot fold 'st' away.
3390     // For example, 'st' might be the final state at a conditional
3391     // return.  Or, 'st' might be used by some node which is live at
3392     // the same time 'st' is live, which might be unschedulable.  So,
3393     // require exactly ONE user until such time as we clone 'mem' for
3394     // each of 'mem's uses (thus making the exactly-1-user-rule hold
3395     // true).
3396     while (st->is_Store() && st->outcnt() == 1) {
3397       // Looking at a dead closed cycle of memory?
3398       assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3399       assert(Opcode() == st->Opcode() ||
3400              st->Opcode() == Op_StoreVector ||
3401              Opcode() == Op_StoreVector ||
3402              st->Opcode() == Op_StoreVectorScatter ||
3403              Opcode() == Op_StoreVectorScatter ||
3404              phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3405              (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3406              (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3407              (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3408              "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3409 
3410       if (st->in(MemNode::Address)->eqv_uncast(address) &&
3411           st->as_Store()->memory_size() <= this->memory_size()) {
3412         Node* use = st->raw_out(0);
3413         if (phase->is_IterGVN()) {
3414           phase->is_IterGVN()->rehash_node_delayed(use);
3415         }
3416         // It's OK to do this in the parser, since DU info is always accurate,
3417         // and the parser always refers to nodes via SafePointNode maps.
3418         use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3419         return this;
3420       }
3421       st = st->in(MemNode::Memory);
3422     }
3423   }
3424 
3425 
3426   // Capture an unaliased, unconditional, simple store into an initializer.
3427   // Or, if it is independent of the allocation, hoist it above the allocation.
3428   if (ReduceFieldZeroing && /*can_reshape &&*/
3429       mem->is_Proj() && mem->in(0)->is_Initialize()) {
3430     InitializeNode* init = mem->in(0)->as_Initialize();
3431     intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3432     if (offset > 0) {
3433       Node* moved = init->capture_store(this, offset, phase, can_reshape);
3434       // If the InitializeNode captured me, it made a raw copy of me,
3435       // and I need to disappear.
3436       if (moved != nullptr) {
3437         // %%% hack to ensure that Ideal returns a new node:
3438         mem = MergeMemNode::make(mem);
3439         return mem;             // fold me away
3440       }
3441     }
3442   }
3443 
3444   // Fold reinterpret cast into memory operation:
3445   //    StoreX mem (MoveY2X v) => StoreY mem v
3446   if (value->is_Move()) {
3447     const Type* vt = value->in(1)->bottom_type();
3448     if (has_reinterpret_variant(vt)) {
3449       if (phase->C->post_loop_opts_phase()) {
3450         return convert_to_reinterpret_store(*phase, value->in(1), vt);
3451       } else {
3452         phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3453       }
3454     }
3455   }
3456 
3457   if (MergeStores && UseUnalignedAccesses) {
3458     if (phase->C->merge_stores_phase()) {
3459       MergePrimitiveStores merge(phase, this);
3460       Node* progress = merge.run();
3461       if (progress != nullptr) { return progress; }
3462     } else {
3463       // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3464       // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3465       // the stores, and we merge the wrong sequence of stores.
3466       // Example:
3467       //   StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3468       // Apply MergeStores:
3469       //   StoreI RangeCheck [   StoreL  ] RangeCheck StoreI
3470       // Remove more RangeChecks:
3471       //   StoreI            [   StoreL  ]            StoreI
3472       // But now it would have been better to do this instead:
3473       //   [         StoreL       ] [       StoreL         ]
3474       phase->C->record_for_merge_stores_igvn(this);
3475     }
3476   }
3477 
3478   return nullptr;                  // No further progress
3479 }
3480 
3481 //------------------------------Value-----------------------------------------
3482 const Type* StoreNode::Value(PhaseGVN* phase) const {
3483   // Either input is TOP ==> the result is TOP
3484   const Type *t1 = phase->type( in(MemNode::Memory) );
3485   if( t1 == Type::TOP ) return Type::TOP;
3486   const Type *t2 = phase->type( in(MemNode::Address) );
3487   if( t2 == Type::TOP ) return Type::TOP;
3488   const Type *t3 = phase->type( in(MemNode::ValueIn) );
3489   if( t3 == Type::TOP ) return Type::TOP;
3490   return Type::MEMORY;
3491 }
3492 
3493 //------------------------------Identity---------------------------------------
3494 // Remove redundant stores:
3495 //   Store(m, p, Load(m, p)) changes to m.
3496 //   Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3497 Node* StoreNode::Identity(PhaseGVN* phase) {
3498   Node* mem = in(MemNode::Memory);
3499   Node* adr = in(MemNode::Address);
3500   Node* val = in(MemNode::ValueIn);
3501 
3502   Node* result = this;
3503 
3504   // Load then Store?  Then the Store is useless
3505   if (val->is_Load() &&
3506       val->in(MemNode::Address)->eqv_uncast(adr) &&
3507       val->in(MemNode::Memory )->eqv_uncast(mem) &&
3508       val->as_Load()->store_Opcode() == Opcode()) {
3509     // Ensure vector type is the same
3510     if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3511       result = mem;
3512     }
3513   }
3514 
3515   // Two stores in a row of the same value?
3516   if (result == this &&
3517       mem->is_Store() &&
3518       mem->in(MemNode::Address)->eqv_uncast(adr) &&
3519       mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3520       mem->Opcode() == Opcode()) {
3521     if (!is_StoreVector()) {
3522       result = mem;
3523     } else {
3524       const StoreVectorNode* store_vector = as_StoreVector();
3525       const StoreVectorNode* mem_vector = mem->as_StoreVector();
3526       const Node* store_indices = store_vector->indices();
3527       const Node* mem_indices = mem_vector->indices();
3528       const Node* store_mask = store_vector->mask();
3529       const Node* mem_mask = mem_vector->mask();
3530       // Ensure types, indices, and masks match
3531       if (store_vector->vect_type() == mem_vector->vect_type() &&
3532           ((store_indices == nullptr) == (mem_indices == nullptr) &&
3533            (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3534           ((store_mask == nullptr) == (mem_mask == nullptr) &&
3535            (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3536         result = mem;
3537       }
3538     }
3539   }
3540 
3541   // Store of zero anywhere into a freshly-allocated object?
3542   // Then the store is useless.
3543   // (It must already have been captured by the InitializeNode.)
3544   if (result == this &&
3545       ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
3546     // a newly allocated object is already all-zeroes everywhere
3547     if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
3548       result = mem;
3549     }
3550 
3551     if (result == this) {
3552       // the store may also apply to zero-bits in an earlier object
3553       Node* prev_mem = find_previous_store(phase);
3554       // Steps (a), (b):  Walk past independent stores to find an exact match.
3555       if (prev_mem != nullptr) {
3556         Node* prev_val = can_see_stored_value(prev_mem, phase);
3557         if (prev_val != nullptr && prev_val == val) {
3558           // prev_val and val might differ by a cast; it would be good
3559           // to keep the more informative of the two.
3560           result = mem;
3561         }
3562       }
3563     }
3564   }
3565 
3566   PhaseIterGVN* igvn = phase->is_IterGVN();
3567   if (result != this && igvn != nullptr) {
3568     MemBarNode* trailing = trailing_membar();
3569     if (trailing != nullptr) {
3570 #ifdef ASSERT
3571       const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3572       assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3573 #endif
3574       trailing->remove(igvn);
3575     }
3576   }
3577 
3578   return result;
3579 }
3580 
3581 //------------------------------match_edge-------------------------------------
3582 // Do we Match on this edge index or not?  Match only memory & value
3583 uint StoreNode::match_edge(uint idx) const {
3584   return idx == MemNode::Address || idx == MemNode::ValueIn;
3585 }
3586 
3587 //------------------------------cmp--------------------------------------------
3588 // Do not common stores up together.  They generally have to be split
3589 // back up anyways, so do not bother.
3590 bool StoreNode::cmp( const Node &n ) const {
3591   return (&n == this);          // Always fail except on self
3592 }
3593 
3594 //------------------------------Ideal_masked_input-----------------------------
3595 // Check for a useless mask before a partial-word store
3596 // (StoreB ... (AndI valIn conIa) )
3597 // If (conIa & mask == mask) this simplifies to
3598 // (StoreB ... (valIn) )
3599 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3600   Node *val = in(MemNode::ValueIn);
3601   if( val->Opcode() == Op_AndI ) {
3602     const TypeInt *t = phase->type( val->in(2) )->isa_int();
3603     if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3604       set_req_X(MemNode::ValueIn, val->in(1), phase);
3605       return this;
3606     }
3607   }
3608   return nullptr;
3609 }
3610 
3611 
3612 //------------------------------Ideal_sign_extended_input----------------------
3613 // Check for useless sign-extension before a partial-word store
3614 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3615 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3616 // (StoreB ... (v))
3617 // If (conIL > conIR) under some conditions, it can be simplified into
3618 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3619 // This case happens when the value of the store was itself a left shift, that
3620 // gets merged into the inner left shift of the sign-extension. For instance,
3621 // if we have
3622 // array_of_shorts[0] = (short)(v << 2)
3623 // We get a structure such as:
3624 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3625 // that is simplified into
3626 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3627 // It is thus useful to handle cases where conIL > conIR. But this simplification
3628 // does not always hold. Let's see in which cases it's valid.
3629 //
3630 // Let's assume we have the following 32 bits integer v:
3631 // +----------------------------------+
3632 // |             v[0..31]             |
3633 // +----------------------------------+
3634 //  31                               0
3635 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3636 // potentially different magnitudes.
3637 // We denote num_rejected_bits the number of bits of the discarded part. In this
3638 // case, num_rejected_bits == 24.
3639 //
3640 // Statement (proved further below in case analysis):
3641 //   Given:
3642 //   - 0 <= conIL < BitsPerJavaInteger   (no wrap in shift, enforced by maskShiftAmount)
3643 //   - 0 <= conIR < BitsPerJavaInteger   (no wrap in shift, enforced by maskShiftAmount)
3644 //   - conIL >= conIR
3645 //   - num_rejected_bits >= conIR
3646 //   Then this form:
3647 //      (RShiftI _ (LShiftI _ v conIL) conIR)
3648 //   can be replaced with this form:
3649 //      (LShiftI _ v (conIL-conIR))
3650 //
3651 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3652 //       have to be correct, as the higher bits are rejected / truncated by the store.
3653 //
3654 // The hypotheses
3655 //   0 <= conIL < BitsPerJavaInteger
3656 //   0 <= conIR < BitsPerJavaInteger
3657 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3658 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3659 // to v << 1).
3660 //
3661 //
3662 // If you don't like case analysis, jump after the conclusion.
3663 // ### Case 1 : conIL == conIR
3664 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3665 // If we do the shift left then right by 24 bits, we get:
3666 // after: v << 24
3667 // +---------+------------------------+
3668 // | v[0..7] |           0            |
3669 // +---------+------------------------+
3670 //  31     24 23                      0
3671 // after: (v << 24) >> 24
3672 // +------------------------+---------+
3673 // |        sign bit        | v[0..7] |
3674 // +------------------------+---------+
3675 //  31                     8 7        0
3676 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3677 // result) are the same before and after, so, indeed, simplifying is correct.
3678 
3679 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3680 // If we do the shift left then right by 22 bits, we get:
3681 // after: v << 22
3682 // +---------+------------------------+
3683 // | v[0..9] |           0            |
3684 // +---------+------------------------+
3685 //  31     22 21                      0
3686 // after: (v << 22) >> 22
3687 // +------------------------+---------+
3688 // |        sign bit        | v[0..9] |
3689 // +------------------------+---------+
3690 //  31                    10 9        0
3691 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3692 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3693 // still correct.
3694 
3695 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3696 // If we do the shift left then right by 26 bits, we get:
3697 // after: v << 26
3698 // +---------+------------------------+
3699 // | v[0..5] |           0            |
3700 // +---------+------------------------+
3701 //  31     26 25                      0
3702 // after: (v << 26) >> 26
3703 // +------------------------+---------+
3704 // |        sign bit        | v[0..5] |
3705 // +------------------------+---------+
3706 //  31                     6 5        0
3707 // The non-rejected bits are made of
3708 // - 0-5 => the bits 0 to 5 of v
3709 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3710 // Simplifying this as v is not correct.
3711 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3712 //
3713 // ### Case 2: conIL > conIR
3714 // ###### Case 2.1: num_rejected_bits == conIR
3715 // We take conIL == 26 for this example.
3716 // after: v << 26
3717 // +---------+------------------------+
3718 // | v[0..5] |           0            |
3719 // +---------+------------------------+
3720 //  31     26 25                      0
3721 // after: (v << 26) >> 24
3722 // +------------------+---------+-----+
3723 // |     sign bit     | v[0..5] |  0  |
3724 // +------------------+---------+-----+
3725 //  31               8 7       2 1   0
3726 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3727 // The bits 6 and 7 of v have been thrown away after the shift left.
3728 // The simplification is still correct.
3729 //
3730 // ###### Case 2.2: num_rejected_bits > conIR.
3731 // Let's say conIL == 26 and conIR == 22.
3732 // after: v << 26
3733 // +---------+------------------------+
3734 // | v[0..5] |           0            |
3735 // +---------+------------------------+
3736 //  31     26 25                      0
3737 // after: (v << 26) >> 22
3738 // +------------------+---------+-----+
3739 // |     sign bit     | v[0..5] |  0  |
3740 // +------------------+---------+-----+
3741 //  31              10 9       4 3   0
3742 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3743 // - 0-3 => 0
3744 // - 4-7 => bits 0 to 3 of v
3745 // The simplification is still correct.
3746 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3747 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3748 //
3749 // ###### But! Case 2.3: num_rejected_bits < conIR.
3750 // Let's see that this case is not as easy to simplify.
3751 // Let's say conIL == 28 and conIR == 26.
3752 // after: v << 28
3753 // +---------+------------------------+
3754 // | v[0..3] |           0            |
3755 // +---------+------------------------+
3756 //  31     28 27                      0
3757 // after: (v << 28) >> 26
3758 // +------------------+---------+-----+
3759 // |     sign bit     | v[0..3] |  0  |
3760 // +------------------+---------+-----+
3761 //  31               6 5       2 1   0
3762 // The non-rejected bits are made of
3763 // - 0-1 => 0
3764 // - 2-5 => the bits 0 to 3 of v
3765 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3766 // Simplifying this as (v << 2) is not correct.
3767 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3768 //
3769 // ### Conclusion:
3770 // Our hypotheses are indeed sufficient:
3771 //   - 0 <= conIL < BitsPerJavaInteger
3772 //   - 0 <= conIR < BitsPerJavaInteger
3773 //   - conIL >= conIR
3774 //   - num_rejected_bits >= conIR
3775 //
3776 // ### A rationale without case analysis:
3777 // After the shift left, conIL upper  bits of v are discarded and conIL lower bit
3778 // zeroes are added. After the shift right, conIR lower bits of the previous result
3779 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3780 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3781 // the point of the simplification is to get an expression of the form
3782 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3783 // simplification is not correct if conIL < conIR.
3784 //
3785 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3786 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3787 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3788 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3789 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3790 //
3791 // We do not treat the case conIL < conIR here since the point of this function is
3792 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3793 // of treating conIL > conIR comes from the cases where the sign-extended value is
3794 // also left-shift expression. Computing the sign-extension of a right-shift expression
3795 // doesn't yield a situation such as
3796 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3797 // where conIL < conIR.
3798 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3799   Node* shr = in(MemNode::ValueIn);
3800   if (shr->Opcode() == Op_RShiftI) {
3801     const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
3802     if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
3803       Node* shl = shr->in(1);
3804       if (shl->Opcode() == Op_LShiftI) {
3805         const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
3806         if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
3807           if (conIL->get_con() == conIR->get_con()) {
3808             set_req_X(MemNode::ValueIn, shl->in(1), phase);
3809             return this;
3810           }
3811           if (conIL->get_con() > conIR->get_con()) {
3812             Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
3813             set_req_X(MemNode::ValueIn, new_shl, phase);
3814             return this;
3815           }
3816         }
3817       }
3818     }
3819   }
3820   return nullptr;
3821 }
3822 
3823 //------------------------------value_never_loaded-----------------------------------
3824 // Determine whether there are any possible loads of the value stored.
3825 // For simplicity, we actually check if there are any loads from the
3826 // address stored to, not just for loads of the value stored by this node.
3827 //
3828 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
3829   Node *adr = in(Address);
3830   const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
3831   if (adr_oop == nullptr)
3832     return false;
3833   if (!adr_oop->is_known_instance_field())
3834     return false; // if not a distinct instance, there may be aliases of the address
3835   for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
3836     Node *use = adr->fast_out(i);
3837     if (use->is_Load() || use->is_LoadStore()) {
3838       return false;
3839     }
3840   }
3841   return true;
3842 }
3843 
3844 MemBarNode* StoreNode::trailing_membar() const {
3845   if (is_release()) {
3846     MemBarNode* trailing_mb = nullptr;
3847     for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3848       Node* u = fast_out(i);
3849       if (u->is_MemBar()) {
3850         if (u->as_MemBar()->trailing_store()) {
3851           assert(u->Opcode() == Op_MemBarVolatile, "");
3852           assert(trailing_mb == nullptr, "only one");
3853           trailing_mb = u->as_MemBar();
3854 #ifdef ASSERT
3855           Node* leading = u->as_MemBar()->leading_membar();
3856           assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3857           assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3858           assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3859 #endif
3860         } else {
3861           assert(u->as_MemBar()->standalone(), "");
3862         }
3863       }
3864     }
3865     return trailing_mb;
3866   }
3867   return nullptr;
3868 }
3869 
3870 
3871 //=============================================================================
3872 //------------------------------Ideal------------------------------------------
3873 // If the store is from an AND mask that leaves the low bits untouched, then
3874 // we can skip the AND operation.  If the store is from a sign-extension
3875 // (a left shift, then right shift) we can skip both.
3876 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3877   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3878   if( progress != nullptr ) return progress;
3879 
3880   progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3881   if( progress != nullptr ) return progress;
3882 
3883   // Finally check the default case
3884   return StoreNode::Ideal(phase, can_reshape);
3885 }
3886 
3887 //=============================================================================
3888 //------------------------------Ideal------------------------------------------
3889 // If the store is from an AND mask that leaves the low bits untouched, then
3890 // we can skip the AND operation
3891 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3892   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3893   if( progress != nullptr ) return progress;
3894 
3895   progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3896   if( progress != nullptr ) return progress;
3897 
3898   // Finally check the default case
3899   return StoreNode::Ideal(phase, can_reshape);
3900 }
3901 
3902 //=============================================================================
3903 //----------------------------------SCMemProjNode------------------------------
3904 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3905 {
3906   if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
3907     return Type::TOP;
3908   }
3909   return bottom_type();
3910 }
3911 
3912 //=============================================================================
3913 //----------------------------------LoadStoreNode------------------------------
3914 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3915   : Node(required),
3916     _type(rt),
3917     _adr_type(at),
3918     _barrier_data(0)
3919 {
3920   init_req(MemNode::Control, c  );
3921   init_req(MemNode::Memory , mem);
3922   init_req(MemNode::Address, adr);
3923   init_req(MemNode::ValueIn, val);
3924   init_class_id(Class_LoadStore);
3925 }
3926 
3927 //------------------------------Value-----------------------------------------
3928 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3929   // Either input is TOP ==> the result is TOP
3930   if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3931     return Type::TOP;
3932   }
3933   const Type* t = phase->type(in(MemNode::Memory));
3934   if (t == Type::TOP) {
3935     return Type::TOP;
3936   }
3937   t = phase->type(in(MemNode::Address));
3938   if (t == Type::TOP) {
3939     return Type::TOP;
3940   }
3941   t = phase->type(in(MemNode::ValueIn));
3942   if (t == Type::TOP) {
3943     return Type::TOP;
3944   }
3945   return bottom_type();
3946 }
3947 
3948 uint LoadStoreNode::ideal_reg() const {
3949   return _type->ideal_reg();
3950 }
3951 
3952 // This method conservatively checks if the result of a LoadStoreNode is
3953 // used, that is, if it returns true, then it is definitely the case that
3954 // the result of the node is not needed.
3955 // For example, GetAndAdd can be matched into a lock_add instead of a
3956 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
3957 bool LoadStoreNode::result_not_used() const {
3958   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3959     Node *x = fast_out(i);
3960     if (x->Opcode() == Op_SCMemProj) {
3961       continue;
3962     }
3963     if (x->bottom_type() == TypeTuple::MEMBAR &&
3964         !x->is_Call() &&
3965         x->Opcode() != Op_Blackhole) {
3966       continue;
3967     }
3968     return false;
3969   }
3970   return true;
3971 }
3972 
3973 MemBarNode* LoadStoreNode::trailing_membar() const {
3974   MemBarNode* trailing = nullptr;
3975   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3976     Node* u = fast_out(i);
3977     if (u->is_MemBar()) {
3978       if (u->as_MemBar()->trailing_load_store()) {
3979         assert(u->Opcode() == Op_MemBarAcquire, "");
3980         assert(trailing == nullptr, "only one");
3981         trailing = u->as_MemBar();
3982 #ifdef ASSERT
3983         Node* leading = trailing->leading_membar();
3984         assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3985         assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3986         assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3987 #endif
3988       } else {
3989         assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3990       }
3991     }
3992   }
3993 
3994   return trailing;
3995 }
3996 
3997 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3998 
3999 //=============================================================================
4000 //----------------------------------LoadStoreConditionalNode--------------------
4001 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4002   init_req(ExpectedIn, ex );
4003 }
4004 
4005 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4006   // Either input is TOP ==> the result is TOP
4007   const Type* t = phase->type(in(ExpectedIn));
4008   if (t == Type::TOP) {
4009     return Type::TOP;
4010   }
4011   return LoadStoreNode::Value(phase);
4012 }
4013 
4014 //=============================================================================
4015 //-------------------------------adr_type--------------------------------------
4016 const TypePtr* ClearArrayNode::adr_type() const {
4017   Node *adr = in(3);
4018   if (adr == nullptr)  return nullptr; // node is dead
4019   return MemNode::calculate_adr_type(adr->bottom_type());
4020 }
4021 
4022 //------------------------------match_edge-------------------------------------
4023 // Do we Match on this edge index or not?  Do not match memory
4024 uint ClearArrayNode::match_edge(uint idx) const {
4025   return idx > 1;
4026 }
4027 
4028 //------------------------------Identity---------------------------------------
4029 // Clearing a zero length array does nothing
4030 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4031   return phase->type(in(2))->higher_equal(TypeX::ZERO)  ? in(1) : this;
4032 }
4033 
4034 //------------------------------Idealize---------------------------------------
4035 // Clearing a short array is faster with stores
4036 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4037   // Already know this is a large node, do not try to ideal it
4038   if (_is_large) return nullptr;
4039 
4040   const int unit = BytesPerLong;
4041   const TypeX* t = phase->type(in(2))->isa_intptr_t();
4042   if (!t)  return nullptr;
4043   if (!t->is_con())  return nullptr;
4044   intptr_t raw_count = t->get_con();
4045   intptr_t size = raw_count;
4046   if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4047   // Clearing nothing uses the Identity call.
4048   // Negative clears are possible on dead ClearArrays
4049   // (see jck test stmt114.stmt11402.val).
4050   if (size <= 0 || size % unit != 0)  return nullptr;
4051   intptr_t count = size / unit;
4052   // Length too long; communicate this to matchers and assemblers.
4053   // Assemblers are responsible to produce fast hardware clears for it.
4054   if (size > InitArrayShortSize) {
4055     return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
4056   } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4057     return nullptr;
4058   }
4059   if (!IdealizeClearArrayNode) return nullptr;
4060   Node *mem = in(1);
4061   if( phase->type(mem)==Type::TOP ) return nullptr;
4062   Node *adr = in(3);
4063   const Type* at = phase->type(adr);
4064   if( at==Type::TOP ) return nullptr;
4065   const TypePtr* atp = at->isa_ptr();
4066   // adjust atp to be the correct array element address type
4067   if (atp == nullptr)  atp = TypePtr::BOTTOM;
4068   else              atp = atp->add_offset(Type::OffsetBot);
4069   // Get base for derived pointer purposes
4070   if( adr->Opcode() != Op_AddP ) Unimplemented();
4071   Node *base = adr->in(1);
4072 
4073   Node *zero = phase->makecon(TypeLong::ZERO);
4074   Node *off  = phase->MakeConX(BytesPerLong);
4075   mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4076   count--;
4077   while( count-- ) {
4078     mem = phase->transform(mem);
4079     adr = phase->transform(new AddPNode(base,adr,off));
4080     mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4081   }
4082   return mem;
4083 }
4084 
4085 //----------------------------step_through----------------------------------
4086 // Return allocation input memory edge if it is different instance
4087 // or itself if it is the one we are looking for.
4088 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4089   Node* n = *np;
4090   assert(n->is_ClearArray(), "sanity");
4091   intptr_t offset;
4092   AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4093   // This method is called only before Allocate nodes are expanded
4094   // during macro nodes expansion. Before that ClearArray nodes are
4095   // only generated in PhaseMacroExpand::generate_arraycopy() (before
4096   // Allocate nodes are expanded) which follows allocations.
4097   assert(alloc != nullptr, "should have allocation");
4098   if (alloc->_idx == instance_id) {
4099     // Can not bypass initialization of the instance we are looking for.
4100     return false;
4101   }
4102   // Otherwise skip it.
4103   InitializeNode* init = alloc->initialization();
4104   if (init != nullptr)
4105     *np = init->in(TypeFunc::Memory);
4106   else
4107     *np = alloc->in(TypeFunc::Memory);
4108   return true;
4109 }
4110 
4111 //----------------------------clear_memory-------------------------------------
4112 // Generate code to initialize object storage to zero.
4113 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4114                                    intptr_t start_offset,
4115                                    Node* end_offset,
4116                                    PhaseGVN* phase) {
4117   intptr_t offset = start_offset;
4118 
4119   int unit = BytesPerLong;
4120   if ((offset % unit) != 0) {
4121     Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4122     adr = phase->transform(adr);
4123     const TypePtr* atp = TypeRawPtr::BOTTOM;
4124     mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4125     mem = phase->transform(mem);
4126     offset += BytesPerInt;
4127   }
4128   assert((offset % unit) == 0, "");
4129 
4130   // Initialize the remaining stuff, if any, with a ClearArray.
4131   return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
4132 }
4133 
4134 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4135                                    Node* start_offset,
4136                                    Node* end_offset,
4137                                    PhaseGVN* phase) {
4138   if (start_offset == end_offset) {
4139     // nothing to do
4140     return mem;
4141   }
4142 
4143   int unit = BytesPerLong;
4144   Node* zbase = start_offset;
4145   Node* zend  = end_offset;
4146 
4147   // Scale to the unit required by the CPU:
4148   if (!Matcher::init_array_count_is_in_bytes) {
4149     Node* shift = phase->intcon(exact_log2(unit));
4150     zbase = phase->transform(new URShiftXNode(zbase, shift) );
4151     zend  = phase->transform(new URShiftXNode(zend,  shift) );
4152   }
4153 
4154   // Bulk clear double-words
4155   Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4156   Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4157   mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
4158   return phase->transform(mem);
4159 }
4160 
4161 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4162                                    intptr_t start_offset,
4163                                    intptr_t end_offset,
4164                                    PhaseGVN* phase) {
4165   if (start_offset == end_offset) {
4166     // nothing to do
4167     return mem;
4168   }
4169 
4170   assert((end_offset % BytesPerInt) == 0, "odd end offset");
4171   intptr_t done_offset = end_offset;
4172   if ((done_offset % BytesPerLong) != 0) {
4173     done_offset -= BytesPerInt;
4174   }
4175   if (done_offset > start_offset) {
4176     mem = clear_memory(ctl, mem, dest,
4177                        start_offset, phase->MakeConX(done_offset), phase);
4178   }
4179   if (done_offset < end_offset) { // emit the final 32-bit store
4180     Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4181     adr = phase->transform(adr);
4182     const TypePtr* atp = TypeRawPtr::BOTTOM;
4183     mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4184     mem = phase->transform(mem);
4185     done_offset += BytesPerInt;
4186   }
4187   assert(done_offset == end_offset, "");
4188   return mem;
4189 }
4190 
4191 //=============================================================================
4192 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4193   : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4194     _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4195 #ifdef ASSERT
4196   , _pair_idx(0)
4197 #endif
4198 {
4199   init_class_id(Class_MemBar);
4200   Node* top = C->top();
4201   init_req(TypeFunc::I_O,top);
4202   init_req(TypeFunc::FramePtr,top);
4203   init_req(TypeFunc::ReturnAdr,top);
4204   if (precedent != nullptr)
4205     init_req(TypeFunc::Parms, precedent);
4206 }
4207 
4208 //------------------------------cmp--------------------------------------------
4209 uint MemBarNode::hash() const { return NO_HASH; }
4210 bool MemBarNode::cmp( const Node &n ) const {
4211   return (&n == this);          // Always fail except on self
4212 }
4213 
4214 //------------------------------make-------------------------------------------
4215 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4216   switch (opcode) {
4217   case Op_MemBarAcquire:     return new MemBarAcquireNode(C, atp, pn);
4218   case Op_LoadFence:         return new LoadFenceNode(C, atp, pn);
4219   case Op_MemBarRelease:     return new MemBarReleaseNode(C, atp, pn);
4220   case Op_StoreFence:        return new StoreFenceNode(C, atp, pn);
4221   case Op_MemBarStoreStore:  return new MemBarStoreStoreNode(C, atp, pn);
4222   case Op_StoreStoreFence:   return new StoreStoreFenceNode(C, atp, pn);
4223   case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4224   case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4225   case Op_MemBarVolatile:    return new MemBarVolatileNode(C, atp, pn);
4226   case Op_MemBarCPUOrder:    return new MemBarCPUOrderNode(C, atp, pn);
4227   case Op_OnSpinWait:        return new OnSpinWaitNode(C, atp, pn);
4228   case Op_Initialize:        return new InitializeNode(C, atp, pn);
4229   default: ShouldNotReachHere(); return nullptr;
4230   }
4231 }
4232 
4233 void MemBarNode::remove(PhaseIterGVN *igvn) {
4234   if (outcnt() != 2) {
4235     assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4236     assert(outcnt() == 1, "Only control then");
4237   }
4238   if (trailing_store() || trailing_load_store()) {
4239     MemBarNode* leading = leading_membar();
4240     if (leading != nullptr) {
4241       assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4242       leading->remove(igvn);
4243     }
4244   }
4245   if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4246     igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4247   }
4248   if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4249     igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4250   }
4251 }
4252 
4253 //------------------------------Ideal------------------------------------------
4254 // Return a node which is more "ideal" than the current node.  Strip out
4255 // control copies
4256 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4257   if (remove_dead_region(phase, can_reshape)) return this;
4258   // Don't bother trying to transform a dead node
4259   if (in(0) && in(0)->is_top()) {
4260     return nullptr;
4261   }
4262 
4263   bool progress = false;
4264   // Eliminate volatile MemBars for scalar replaced objects.
4265   if (can_reshape && req() == (Precedent+1)) {
4266     bool eliminate = false;
4267     int opc = Opcode();
4268     if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4269       // Volatile field loads and stores.
4270       Node* my_mem = in(MemBarNode::Precedent);
4271       // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4272       if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4273         // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4274         // replace this Precedent (decodeN) with the Load instead.
4275         if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1))  {
4276           Node* load_node = my_mem->in(1);
4277           set_req(MemBarNode::Precedent, load_node);
4278           phase->is_IterGVN()->_worklist.push(my_mem);
4279           my_mem = load_node;
4280         } else {
4281           assert(my_mem->unique_out() == this, "sanity");
4282           assert(!trailing_load_store(), "load store node can't be eliminated");
4283           del_req(Precedent);
4284           phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4285           my_mem = nullptr;
4286         }
4287         progress = true;
4288       }
4289       if (my_mem != nullptr && my_mem->is_Mem()) {
4290         const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4291         // Check for scalar replaced object reference.
4292         if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4293             t_oop->offset() != Type::OffsetBot &&
4294             t_oop->offset() != Type::OffsetTop) {
4295           eliminate = true;
4296         }
4297       }
4298     } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4299       // Final field stores.
4300       Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4301       if ((alloc != nullptr) && alloc->is_Allocate() &&
4302           alloc->as_Allocate()->does_not_escape_thread()) {
4303         // The allocated object does not escape.
4304         eliminate = true;
4305       }
4306     }
4307     if (eliminate) {
4308       // Replace MemBar projections by its inputs.
4309       PhaseIterGVN* igvn = phase->is_IterGVN();
4310       remove(igvn);
4311       // Must return either the original node (now dead) or a new node
4312       // (Do not return a top here, since that would break the uniqueness of top.)
4313       return new ConINode(TypeInt::ZERO);
4314     }
4315   }
4316   return progress ? this : nullptr;
4317 }
4318 
4319 //------------------------------Value------------------------------------------
4320 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4321   if( !in(0) ) return Type::TOP;
4322   if( phase->type(in(0)) == Type::TOP )
4323     return Type::TOP;
4324   return TypeTuple::MEMBAR;
4325 }
4326 
4327 //------------------------------match------------------------------------------
4328 // Construct projections for memory.
4329 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
4330   switch (proj->_con) {
4331   case TypeFunc::Control:
4332   case TypeFunc::Memory:
4333     return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4334   }
4335   ShouldNotReachHere();
4336   return nullptr;
4337 }
4338 
4339 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4340   trailing->_kind = TrailingStore;
4341   leading->_kind = LeadingStore;
4342 #ifdef ASSERT
4343   trailing->_pair_idx = leading->_idx;
4344   leading->_pair_idx = leading->_idx;
4345 #endif
4346 }
4347 
4348 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4349   trailing->_kind = TrailingLoadStore;
4350   leading->_kind = LeadingLoadStore;
4351 #ifdef ASSERT
4352   trailing->_pair_idx = leading->_idx;
4353   leading->_pair_idx = leading->_idx;
4354 #endif
4355 }
4356 
4357 MemBarNode* MemBarNode::trailing_membar() const {
4358   ResourceMark rm;
4359   Node* trailing = (Node*)this;
4360   VectorSet seen;
4361   Node_Stack multis(0);
4362   do {
4363     Node* c = trailing;
4364     uint i = 0;
4365     do {
4366       trailing = nullptr;
4367       for (; i < c->outcnt(); i++) {
4368         Node* next = c->raw_out(i);
4369         if (next != c && next->is_CFG()) {
4370           if (c->is_MultiBranch()) {
4371             if (multis.node() == c) {
4372               multis.set_index(i+1);
4373             } else {
4374               multis.push(c, i+1);
4375             }
4376           }
4377           trailing = next;
4378           break;
4379         }
4380       }
4381       if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4382         break;
4383       }
4384       while (multis.size() > 0) {
4385         c = multis.node();
4386         i = multis.index();
4387         if (i < c->req()) {
4388           break;
4389         }
4390         multis.pop();
4391       }
4392     } while (multis.size() > 0);
4393   } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4394 
4395   MemBarNode* mb = trailing->as_MemBar();
4396   assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4397          (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4398   assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4399   return mb;
4400 }
4401 
4402 MemBarNode* MemBarNode::leading_membar() const {
4403   ResourceMark rm;
4404   VectorSet seen;
4405   Node_Stack regions(0);
4406   Node* leading = in(0);
4407   while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4408     while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4409       leading = nullptr;
4410       while (regions.size() > 0 && leading == nullptr) {
4411         Node* r = regions.node();
4412         uint i = regions.index();
4413         if (i < r->req()) {
4414           leading = r->in(i);
4415           regions.set_index(i+1);
4416         } else {
4417           regions.pop();
4418         }
4419       }
4420       if (leading == nullptr) {
4421         assert(regions.size() == 0, "all paths should have been tried");
4422         return nullptr;
4423       }
4424     }
4425     if (leading->is_Region()) {
4426       regions.push(leading, 2);
4427       leading = leading->in(1);
4428     } else {
4429       leading = leading->in(0);
4430     }
4431   }
4432 #ifdef ASSERT
4433   Unique_Node_List wq;
4434   wq.push((Node*)this);
4435   uint found = 0;
4436   for (uint i = 0; i < wq.size(); i++) {
4437     Node* n = wq.at(i);
4438     if (n->is_Region()) {
4439       for (uint j = 1; j < n->req(); j++) {
4440         Node* in = n->in(j);
4441         if (in != nullptr && !in->is_top()) {
4442           wq.push(in);
4443         }
4444       }
4445     } else {
4446       if (n->is_MemBar() && n->as_MemBar()->leading()) {
4447         assert(n == leading, "consistency check failed");
4448         found++;
4449       } else {
4450         Node* in = n->in(0);
4451         if (in != nullptr && !in->is_top()) {
4452           wq.push(in);
4453         }
4454       }
4455     }
4456   }
4457   assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4458 #endif
4459   if (leading == nullptr) {
4460     return nullptr;
4461   }
4462   MemBarNode* mb = leading->as_MemBar();
4463   assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4464          (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4465   assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4466   return mb;
4467 }
4468 
4469 
4470 //===========================InitializeNode====================================
4471 // SUMMARY:
4472 // This node acts as a memory barrier on raw memory, after some raw stores.
4473 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4474 // The Initialize can 'capture' suitably constrained stores as raw inits.
4475 // It can coalesce related raw stores into larger units (called 'tiles').
4476 // It can avoid zeroing new storage for memory units which have raw inits.
4477 // At macro-expansion, it is marked 'complete', and does not optimize further.
4478 //
4479 // EXAMPLE:
4480 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4481 //   ctl = incoming control; mem* = incoming memory
4482 // (Note:  A star * on a memory edge denotes I/O and other standard edges.)
4483 // First allocate uninitialized memory and fill in the header:
4484 //   alloc = (Allocate ctl mem* 16 #short[].klass ...)
4485 //   ctl := alloc.Control; mem* := alloc.Memory*
4486 //   rawmem = alloc.Memory; rawoop = alloc.RawAddress
4487 // Then initialize to zero the non-header parts of the raw memory block:
4488 //   init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4489 //   ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4490 // After the initialize node executes, the object is ready for service:
4491 //   oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4492 // Suppose its body is immediately initialized as {1,2}:
4493 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4494 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
4495 //   mem.SLICE(#short[*]) := store2
4496 //
4497 // DETAILS:
4498 // An InitializeNode collects and isolates object initialization after
4499 // an AllocateNode and before the next possible safepoint.  As a
4500 // memory barrier (MemBarNode), it keeps critical stores from drifting
4501 // down past any safepoint or any publication of the allocation.
4502 // Before this barrier, a newly-allocated object may have uninitialized bits.
4503 // After this barrier, it may be treated as a real oop, and GC is allowed.
4504 //
4505 // The semantics of the InitializeNode include an implicit zeroing of
4506 // the new object from object header to the end of the object.
4507 // (The object header and end are determined by the AllocateNode.)
4508 //
4509 // Certain stores may be added as direct inputs to the InitializeNode.
4510 // These stores must update raw memory, and they must be to addresses
4511 // derived from the raw address produced by AllocateNode, and with
4512 // a constant offset.  They must be ordered by increasing offset.
4513 // The first one is at in(RawStores), the last at in(req()-1).
4514 // Unlike most memory operations, they are not linked in a chain,
4515 // but are displayed in parallel as users of the rawmem output of
4516 // the allocation.
4517 //
4518 // (See comments in InitializeNode::capture_store, which continue
4519 // the example given above.)
4520 //
4521 // When the associated Allocate is macro-expanded, the InitializeNode
4522 // may be rewritten to optimize collected stores.  A ClearArrayNode
4523 // may also be created at that point to represent any required zeroing.
4524 // The InitializeNode is then marked 'complete', prohibiting further
4525 // capturing of nearby memory operations.
4526 //
4527 // During macro-expansion, all captured initializations which store
4528 // constant values of 32 bits or smaller are coalesced (if advantageous)
4529 // into larger 'tiles' 32 or 64 bits.  This allows an object to be
4530 // initialized in fewer memory operations.  Memory words which are
4531 // covered by neither tiles nor non-constant stores are pre-zeroed
4532 // by explicit stores of zero.  (The code shape happens to do all
4533 // zeroing first, then all other stores, with both sequences occurring
4534 // in order of ascending offsets.)
4535 //
4536 // Alternatively, code may be inserted between an AllocateNode and its
4537 // InitializeNode, to perform arbitrary initialization of the new object.
4538 // E.g., the object copying intrinsics insert complex data transfers here.
4539 // The initialization must then be marked as 'complete' disable the
4540 // built-in zeroing semantics and the collection of initializing stores.
4541 //
4542 // While an InitializeNode is incomplete, reads from the memory state
4543 // produced by it are optimizable if they match the control edge and
4544 // new oop address associated with the allocation/initialization.
4545 // They return a stored value (if the offset matches) or else zero.
4546 // A write to the memory state, if it matches control and address,
4547 // and if it is to a constant offset, may be 'captured' by the
4548 // InitializeNode.  It is cloned as a raw memory operation and rewired
4549 // inside the initialization, to the raw oop produced by the allocation.
4550 // Operations on addresses which are provably distinct (e.g., to
4551 // other AllocateNodes) are allowed to bypass the initialization.
4552 //
4553 // The effect of all this is to consolidate object initialization
4554 // (both arrays and non-arrays, both piecewise and bulk) into a
4555 // single location, where it can be optimized as a unit.
4556 //
4557 // Only stores with an offset less than TrackedInitializationLimit words
4558 // will be considered for capture by an InitializeNode.  This puts a
4559 // reasonable limit on the complexity of optimized initializations.
4560 
4561 //---------------------------InitializeNode------------------------------------
4562 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4563   : MemBarNode(C, adr_type, rawoop),
4564     _is_complete(Incomplete), _does_not_escape(false)
4565 {
4566   init_class_id(Class_Initialize);
4567 
4568   assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4569   assert(in(RawAddress) == rawoop, "proper init");
4570   // Note:  allocation() can be null, for secondary initialization barriers
4571 }
4572 
4573 // Since this node is not matched, it will be processed by the
4574 // register allocator.  Declare that there are no constraints
4575 // on the allocation of the RawAddress edge.
4576 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4577   // This edge should be set to top, by the set_complete.  But be conservative.
4578   if (idx == InitializeNode::RawAddress)
4579     return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4580   return RegMask::Empty;
4581 }
4582 
4583 Node* InitializeNode::memory(uint alias_idx) {
4584   Node* mem = in(Memory);
4585   if (mem->is_MergeMem()) {
4586     return mem->as_MergeMem()->memory_at(alias_idx);
4587   } else {
4588     // incoming raw memory is not split
4589     return mem;
4590   }
4591 }
4592 
4593 bool InitializeNode::is_non_zero() {
4594   if (is_complete())  return false;
4595   remove_extra_zeroes();
4596   return (req() > RawStores);
4597 }
4598 
4599 void InitializeNode::set_complete(PhaseGVN* phase) {
4600   assert(!is_complete(), "caller responsibility");
4601   _is_complete = Complete;
4602 
4603   // After this node is complete, it contains a bunch of
4604   // raw-memory initializations.  There is no need for
4605   // it to have anything to do with non-raw memory effects.
4606   // Therefore, tell all non-raw users to re-optimize themselves,
4607   // after skipping the memory effects of this initialization.
4608   PhaseIterGVN* igvn = phase->is_IterGVN();
4609   if (igvn)  igvn->add_users_to_worklist(this);
4610 }
4611 
4612 // convenience function
4613 // return false if the init contains any stores already
4614 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4615   InitializeNode* init = initialization();
4616   if (init == nullptr || init->is_complete())  return false;
4617   init->remove_extra_zeroes();
4618   // for now, if this allocation has already collected any inits, bail:
4619   if (init->is_non_zero())  return false;
4620   init->set_complete(phase);
4621   return true;
4622 }
4623 
4624 void InitializeNode::remove_extra_zeroes() {
4625   if (req() == RawStores)  return;
4626   Node* zmem = zero_memory();
4627   uint fill = RawStores;
4628   for (uint i = fill; i < req(); i++) {
4629     Node* n = in(i);
4630     if (n->is_top() || n == zmem)  continue;  // skip
4631     if (fill < i)  set_req(fill, n);          // compact
4632     ++fill;
4633   }
4634   // delete any empty spaces created:
4635   while (fill < req()) {
4636     del_req(fill);
4637   }
4638 }
4639 
4640 // Helper for remembering which stores go with which offsets.
4641 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4642   if (!st->is_Store())  return -1;  // can happen to dead code via subsume_node
4643   intptr_t offset = -1;
4644   Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4645                                                phase, offset);
4646   if (base == nullptr)  return -1;  // something is dead,
4647   if (offset < 0)       return -1;  //        dead, dead
4648   return offset;
4649 }
4650 
4651 // Helper for proving that an initialization expression is
4652 // "simple enough" to be folded into an object initialization.
4653 // Attempts to prove that a store's initial value 'n' can be captured
4654 // within the initialization without creating a vicious cycle, such as:
4655 //     { Foo p = new Foo(); p.next = p; }
4656 // True for constants and parameters and small combinations thereof.
4657 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4658   ResourceMark rm;
4659   Unique_Node_List worklist;
4660   worklist.push(value);
4661 
4662   uint complexity_limit = 20;
4663   for (uint j = 0; j < worklist.size(); j++) {
4664     if (j >= complexity_limit) {
4665       return false;  // Bail out if processed too many nodes
4666     }
4667 
4668     Node* n = worklist.at(j);
4669     if (n == nullptr)   continue;   // (can this really happen?)
4670     if (n->is_Proj())   n = n->in(0);
4671     if (n == this)      return false;  // found a cycle
4672     if (n->is_Con())    continue;
4673     if (n->is_Start())  continue;   // params, etc., are OK
4674     if (n->is_Root())   continue;   // even better
4675 
4676     // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4677     if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4678       continue;
4679     }
4680 
4681     Node* ctl = n->in(0);
4682     if (ctl != nullptr && !ctl->is_top()) {
4683       if (ctl->is_Proj())  ctl = ctl->in(0);
4684       if (ctl == this)  return false;
4685 
4686       // If we already know that the enclosing memory op is pinned right after
4687       // the init, then any control flow that the store has picked up
4688       // must have preceded the init, or else be equal to the init.
4689       // Even after loop optimizations (which might change control edges)
4690       // a store is never pinned *before* the availability of its inputs.
4691       if (!MemNode::all_controls_dominate(n, this)) {
4692         return false;                  // failed to prove a good control
4693       }
4694     }
4695 
4696     // Check data edges for possible dependencies on 'this'.
4697     for (uint i = 1; i < n->req(); i++) {
4698       Node* m = n->in(i);
4699       if (m == nullptr || m == n || m->is_top())  continue;
4700 
4701       // Only process data inputs once
4702       worklist.push(m);
4703     }
4704   }
4705 
4706   return true;
4707 }
4708 
4709 // Here are all the checks a Store must pass before it can be moved into
4710 // an initialization.  Returns zero if a check fails.
4711 // On success, returns the (constant) offset to which the store applies,
4712 // within the initialized memory.
4713 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4714   const int FAIL = 0;
4715   if (st->req() != MemNode::ValueIn + 1)
4716     return FAIL;                // an inscrutable StoreNode (card mark?)
4717   Node* ctl = st->in(MemNode::Control);
4718   if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4719     return FAIL;                // must be unconditional after the initialization
4720   Node* mem = st->in(MemNode::Memory);
4721   if (!(mem->is_Proj() && mem->in(0) == this))
4722     return FAIL;                // must not be preceded by other stores
4723   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4724   if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4725       !bs->can_initialize_object(st)) {
4726     return FAIL;
4727   }
4728   Node* adr = st->in(MemNode::Address);
4729   intptr_t offset;
4730   AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4731   if (alloc == nullptr)
4732     return FAIL;                // inscrutable address
4733   if (alloc != allocation())
4734     return FAIL;                // wrong allocation!  (store needs to float up)
4735   int size_in_bytes = st->memory_size();
4736   if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4737     return FAIL;                // mismatched access
4738   }
4739   Node* val = st->in(MemNode::ValueIn);
4740 
4741   if (!detect_init_independence(val, phase))
4742     return FAIL;                // stored value must be 'simple enough'
4743 
4744   // The Store can be captured only if nothing after the allocation
4745   // and before the Store is using the memory location that the store
4746   // overwrites.
4747   bool failed = false;
4748   // If is_complete_with_arraycopy() is true the shape of the graph is
4749   // well defined and is safe so no need for extra checks.
4750   if (!is_complete_with_arraycopy()) {
4751     // We are going to look at each use of the memory state following
4752     // the allocation to make sure nothing reads the memory that the
4753     // Store writes.
4754     const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4755     int alias_idx = phase->C->get_alias_index(t_adr);
4756     ResourceMark rm;
4757     Unique_Node_List mems;
4758     mems.push(mem);
4759     Node* unique_merge = nullptr;
4760     for (uint next = 0; next < mems.size(); ++next) {
4761       Node *m  = mems.at(next);
4762       for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4763         Node *n = m->fast_out(j);
4764         if (n->outcnt() == 0) {
4765           continue;
4766         }
4767         if (n == st) {
4768           continue;
4769         } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4770           // If the control of this use is different from the control
4771           // of the Store which is right after the InitializeNode then
4772           // this node cannot be between the InitializeNode and the
4773           // Store.
4774           continue;
4775         } else if (n->is_MergeMem()) {
4776           if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4777             // We can hit a MergeMemNode (that will likely go away
4778             // later) that is a direct use of the memory state
4779             // following the InitializeNode on the same slice as the
4780             // store node that we'd like to capture. We need to check
4781             // the uses of the MergeMemNode.
4782             mems.push(n);
4783           }
4784         } else if (n->is_Mem()) {
4785           Node* other_adr = n->in(MemNode::Address);
4786           if (other_adr == adr) {
4787             failed = true;
4788             break;
4789           } else {
4790             const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4791             if (other_t_adr != nullptr) {
4792               int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4793               if (other_alias_idx == alias_idx) {
4794                 // A load from the same memory slice as the store right
4795                 // after the InitializeNode. We check the control of the
4796                 // object/array that is loaded from. If it's the same as
4797                 // the store control then we cannot capture the store.
4798                 assert(!n->is_Store(), "2 stores to same slice on same control?");
4799                 Node* base = other_adr;
4800                 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4801                 base = base->in(AddPNode::Base);
4802                 if (base != nullptr) {
4803                   base = base->uncast();
4804                   if (base->is_Proj() && base->in(0) == alloc) {
4805                     failed = true;
4806                     break;
4807                   }
4808                 }
4809               }
4810             }
4811           }
4812         } else {
4813           failed = true;
4814           break;
4815         }
4816       }
4817     }
4818   }
4819   if (failed) {
4820     if (!can_reshape) {
4821       // We decided we couldn't capture the store during parsing. We
4822       // should try again during the next IGVN once the graph is
4823       // cleaner.
4824       phase->C->record_for_igvn(st);
4825     }
4826     return FAIL;
4827   }
4828 
4829   return offset;                // success
4830 }
4831 
4832 // Find the captured store in(i) which corresponds to the range
4833 // [start..start+size) in the initialized object.
4834 // If there is one, return its index i.  If there isn't, return the
4835 // negative of the index where it should be inserted.
4836 // Return 0 if the queried range overlaps an initialization boundary
4837 // or if dead code is encountered.
4838 // If size_in_bytes is zero, do not bother with overlap checks.
4839 int InitializeNode::captured_store_insertion_point(intptr_t start,
4840                                                    int size_in_bytes,
4841                                                    PhaseValues* phase) {
4842   const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4843 
4844   if (is_complete())
4845     return FAIL;                // arraycopy got here first; punt
4846 
4847   assert(allocation() != nullptr, "must be present");
4848 
4849   // no negatives, no header fields:
4850   if (start < (intptr_t) allocation()->minimum_header_size())  return FAIL;
4851 
4852   // after a certain size, we bail out on tracking all the stores:
4853   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4854   if (start >= ti_limit)  return FAIL;
4855 
4856   for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4857     if (i >= limit)  return -(int)i; // not found; here is where to put it
4858 
4859     Node*    st     = in(i);
4860     intptr_t st_off = get_store_offset(st, phase);
4861     if (st_off < 0) {
4862       if (st != zero_memory()) {
4863         return FAIL;            // bail out if there is dead garbage
4864       }
4865     } else if (st_off > start) {
4866       // ...we are done, since stores are ordered
4867       if (st_off < start + size_in_bytes) {
4868         return FAIL;            // the next store overlaps
4869       }
4870       return -(int)i;           // not found; here is where to put it
4871     } else if (st_off < start) {
4872       assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4873       if (size_in_bytes != 0 &&
4874           start < st_off + MAX_STORE &&
4875           start < st_off + st->as_Store()->memory_size()) {
4876         return FAIL;            // the previous store overlaps
4877       }
4878     } else {
4879       if (size_in_bytes != 0 &&
4880           st->as_Store()->memory_size() != size_in_bytes) {
4881         return FAIL;            // mismatched store size
4882       }
4883       return i;
4884     }
4885 
4886     ++i;
4887   }
4888 }
4889 
4890 // Look for a captured store which initializes at the offset 'start'
4891 // with the given size.  If there is no such store, and no other
4892 // initialization interferes, then return zero_memory (the memory
4893 // projection of the AllocateNode).
4894 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4895                                           PhaseValues* phase) {
4896   assert(stores_are_sane(phase), "");
4897   int i = captured_store_insertion_point(start, size_in_bytes, phase);
4898   if (i == 0) {
4899     return nullptr;              // something is dead
4900   } else if (i < 0) {
4901     return zero_memory();       // just primordial zero bits here
4902   } else {
4903     Node* st = in(i);           // here is the store at this position
4904     assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4905     return st;
4906   }
4907 }
4908 
4909 // Create, as a raw pointer, an address within my new object at 'offset'.
4910 Node* InitializeNode::make_raw_address(intptr_t offset,
4911                                        PhaseGVN* phase) {
4912   Node* addr = in(RawAddress);
4913   if (offset != 0) {
4914     Compile* C = phase->C;
4915     addr = phase->transform( new AddPNode(C->top(), addr,
4916                                                  phase->MakeConX(offset)) );
4917   }
4918   return addr;
4919 }
4920 
4921 // Clone the given store, converting it into a raw store
4922 // initializing a field or element of my new object.
4923 // Caller is responsible for retiring the original store,
4924 // with subsume_node or the like.
4925 //
4926 // From the example above InitializeNode::InitializeNode,
4927 // here are the old stores to be captured:
4928 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4929 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
4930 //
4931 // Here is the changed code; note the extra edges on init:
4932 //   alloc = (Allocate ...)
4933 //   rawoop = alloc.RawAddress
4934 //   rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4935 //   rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4936 //   init = (Initialize alloc.Control alloc.Memory rawoop
4937 //                      rawstore1 rawstore2)
4938 //
4939 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4940                                     PhaseGVN* phase, bool can_reshape) {
4941   assert(stores_are_sane(phase), "");
4942 
4943   if (start < 0)  return nullptr;
4944   assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4945 
4946   Compile* C = phase->C;
4947   int size_in_bytes = st->memory_size();
4948   int i = captured_store_insertion_point(start, size_in_bytes, phase);
4949   if (i == 0)  return nullptr;  // bail out
4950   Node* prev_mem = nullptr;     // raw memory for the captured store
4951   if (i > 0) {
4952     prev_mem = in(i);           // there is a pre-existing store under this one
4953     set_req(i, C->top());       // temporarily disconnect it
4954     // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4955   } else {
4956     i = -i;                     // no pre-existing store
4957     prev_mem = zero_memory();   // a slice of the newly allocated object
4958     if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4959       set_req(--i, C->top());   // reuse this edge; it has been folded away
4960     else
4961       ins_req(i, C->top());     // build a new edge
4962   }
4963   Node* new_st = st->clone();
4964   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4965   new_st->set_req(MemNode::Control, in(Control));
4966   new_st->set_req(MemNode::Memory,  prev_mem);
4967   new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4968   bs->eliminate_gc_barrier_data(new_st);
4969   new_st = phase->transform(new_st);
4970 
4971   // At this point, new_st might have swallowed a pre-existing store
4972   // at the same offset, or perhaps new_st might have disappeared,
4973   // if it redundantly stored the same value (or zero to fresh memory).
4974 
4975   // In any case, wire it in:
4976   PhaseIterGVN* igvn = phase->is_IterGVN();
4977   if (igvn) {
4978     igvn->rehash_node_delayed(this);
4979   }
4980   set_req(i, new_st);
4981 
4982   // The caller may now kill the old guy.
4983   DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4984   assert(check_st == new_st || check_st == nullptr, "must be findable");
4985   assert(!is_complete(), "");
4986   return new_st;
4987 }
4988 
4989 static bool store_constant(jlong* tiles, int num_tiles,
4990                            intptr_t st_off, int st_size,
4991                            jlong con) {
4992   if ((st_off & (st_size-1)) != 0)
4993     return false;               // strange store offset (assume size==2**N)
4994   address addr = (address)tiles + st_off;
4995   assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4996   switch (st_size) {
4997   case sizeof(jbyte):  *(jbyte*) addr = (jbyte) con; break;
4998   case sizeof(jchar):  *(jchar*) addr = (jchar) con; break;
4999   case sizeof(jint):   *(jint*)  addr = (jint)  con; break;
5000   case sizeof(jlong):  *(jlong*) addr = (jlong) con; break;
5001   default: return false;        // strange store size (detect size!=2**N here)
5002   }
5003   return true;                  // return success to caller
5004 }
5005 
5006 // Coalesce subword constants into int constants and possibly
5007 // into long constants.  The goal, if the CPU permits,
5008 // is to initialize the object with a small number of 64-bit tiles.
5009 // Also, convert floating-point constants to bit patterns.
5010 // Non-constants are not relevant to this pass.
5011 //
5012 // In terms of the running example on InitializeNode::InitializeNode
5013 // and InitializeNode::capture_store, here is the transformation
5014 // of rawstore1 and rawstore2 into rawstore12:
5015 //   alloc = (Allocate ...)
5016 //   rawoop = alloc.RawAddress
5017 //   tile12 = 0x00010002
5018 //   rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5019 //   init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5020 //
5021 void
5022 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5023                                         Node* size_in_bytes,
5024                                         PhaseGVN* phase) {
5025   Compile* C = phase->C;
5026 
5027   assert(stores_are_sane(phase), "");
5028   // Note:  After this pass, they are not completely sane,
5029   // since there may be some overlaps.
5030 
5031   int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5032 
5033   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5034   intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5035   size_limit = MIN2(size_limit, ti_limit);
5036   size_limit = align_up(size_limit, BytesPerLong);
5037   int num_tiles = size_limit / BytesPerLong;
5038 
5039   // allocate space for the tile map:
5040   const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5041   jlong  tiles_buf[small_len];
5042   Node*  nodes_buf[small_len];
5043   jlong  inits_buf[small_len];
5044   jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5045                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5046   Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5047                   : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5048   jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5049                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5050   // tiles: exact bitwise model of all primitive constants
5051   // nodes: last constant-storing node subsumed into the tiles model
5052   // inits: which bytes (in each tile) are touched by any initializations
5053 
5054   //// Pass A: Fill in the tile model with any relevant stores.
5055 
5056   Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5057   Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5058   Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5059   Node* zmem = zero_memory(); // initially zero memory state
5060   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5061     Node* st = in(i);
5062     intptr_t st_off = get_store_offset(st, phase);
5063 
5064     // Figure out the store's offset and constant value:
5065     if (st_off < header_size)             continue; //skip (ignore header)
5066     if (st->in(MemNode::Memory) != zmem)  continue; //skip (odd store chain)
5067     int st_size = st->as_Store()->memory_size();
5068     if (st_off + st_size > size_limit)    break;
5069 
5070     // Record which bytes are touched, whether by constant or not.
5071     if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5072       continue;                 // skip (strange store size)
5073 
5074     const Type* val = phase->type(st->in(MemNode::ValueIn));
5075     if (!val->singleton())                continue; //skip (non-con store)
5076     BasicType type = val->basic_type();
5077 
5078     jlong con = 0;
5079     switch (type) {
5080     case T_INT:    con = val->is_int()->get_con();  break;
5081     case T_LONG:   con = val->is_long()->get_con(); break;
5082     case T_FLOAT:  con = jint_cast(val->getf());    break;
5083     case T_DOUBLE: con = jlong_cast(val->getd());   break;
5084     default:                              continue; //skip (odd store type)
5085     }
5086 
5087     if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5088         st->Opcode() == Op_StoreL) {
5089       continue;                 // This StoreL is already optimal.
5090     }
5091 
5092     // Store down the constant.
5093     store_constant(tiles, num_tiles, st_off, st_size, con);
5094 
5095     intptr_t j = st_off >> LogBytesPerLong;
5096 
5097     if (type == T_INT && st_size == BytesPerInt
5098         && (st_off & BytesPerInt) == BytesPerInt) {
5099       jlong lcon = tiles[j];
5100       if (!Matcher::isSimpleConstant64(lcon) &&
5101           st->Opcode() == Op_StoreI) {
5102         // This StoreI is already optimal by itself.
5103         jint* intcon = (jint*) &tiles[j];
5104         intcon[1] = 0;  // undo the store_constant()
5105 
5106         // If the previous store is also optimal by itself, back up and
5107         // undo the action of the previous loop iteration... if we can.
5108         // But if we can't, just let the previous half take care of itself.
5109         st = nodes[j];
5110         st_off -= BytesPerInt;
5111         con = intcon[0];
5112         if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5113           assert(st_off >= header_size, "still ignoring header");
5114           assert(get_store_offset(st, phase) == st_off, "must be");
5115           assert(in(i-1) == zmem, "must be");
5116           DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5117           assert(con == tcon->is_int()->get_con(), "must be");
5118           // Undo the effects of the previous loop trip, which swallowed st:
5119           intcon[0] = 0;        // undo store_constant()
5120           set_req(i-1, st);     // undo set_req(i, zmem)
5121           nodes[j] = nullptr;   // undo nodes[j] = st
5122           --old_subword;        // undo ++old_subword
5123         }
5124         continue;               // This StoreI is already optimal.
5125       }
5126     }
5127 
5128     // This store is not needed.
5129     set_req(i, zmem);
5130     nodes[j] = st;              // record for the moment
5131     if (st_size < BytesPerLong) // something has changed
5132           ++old_subword;        // includes int/float, but who's counting...
5133     else  ++old_long;
5134   }
5135 
5136   if ((old_subword + old_long) == 0)
5137     return;                     // nothing more to do
5138 
5139   //// Pass B: Convert any non-zero tiles into optimal constant stores.
5140   // Be sure to insert them before overlapping non-constant stores.
5141   // (E.g., byte[] x = { 1,2,y,4 }  =>  x[int 0] = 0x01020004, x[2]=y.)
5142   for (int j = 0; j < num_tiles; j++) {
5143     jlong con  = tiles[j];
5144     jlong init = inits[j];
5145     if (con == 0)  continue;
5146     jint con0,  con1;           // split the constant, address-wise
5147     jint init0, init1;          // split the init map, address-wise
5148     { union { jlong con; jint intcon[2]; } u;
5149       u.con = con;
5150       con0  = u.intcon[0];
5151       con1  = u.intcon[1];
5152       u.con = init;
5153       init0 = u.intcon[0];
5154       init1 = u.intcon[1];
5155     }
5156 
5157     Node* old = nodes[j];
5158     assert(old != nullptr, "need the prior store");
5159     intptr_t offset = (j * BytesPerLong);
5160 
5161     bool split = !Matcher::isSimpleConstant64(con);
5162 
5163     if (offset < header_size) {
5164       assert(offset + BytesPerInt >= header_size, "second int counts");
5165       assert(*(jint*)&tiles[j] == 0, "junk in header");
5166       split = true;             // only the second word counts
5167       // Example:  int a[] = { 42 ... }
5168     } else if (con0 == 0 && init0 == -1) {
5169       split = true;             // first word is covered by full inits
5170       // Example:  int a[] = { ... foo(), 42 ... }
5171     } else if (con1 == 0 && init1 == -1) {
5172       split = true;             // second word is covered by full inits
5173       // Example:  int a[] = { ... 42, foo() ... }
5174     }
5175 
5176     // Here's a case where init0 is neither 0 nor -1:
5177     //   byte a[] = { ... 0,0,foo(),0,  0,0,0,42 ... }
5178     // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5179     // In this case the tile is not split; it is (jlong)42.
5180     // The big tile is stored down, and then the foo() value is inserted.
5181     // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5182 
5183     Node* ctl = old->in(MemNode::Control);
5184     Node* adr = make_raw_address(offset, phase);
5185     const TypePtr* atp = TypeRawPtr::BOTTOM;
5186 
5187     // One or two coalesced stores to plop down.
5188     Node*    st[2];
5189     intptr_t off[2];
5190     int  nst = 0;
5191     if (!split) {
5192       ++new_long;
5193       off[nst] = offset;
5194       st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5195                                   phase->longcon(con), T_LONG, MemNode::unordered);
5196     } else {
5197       // Omit either if it is a zero.
5198       if (con0 != 0) {
5199         ++new_int;
5200         off[nst]  = offset;
5201         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5202                                     phase->intcon(con0), T_INT, MemNode::unordered);
5203       }
5204       if (con1 != 0) {
5205         ++new_int;
5206         offset += BytesPerInt;
5207         adr = make_raw_address(offset, phase);
5208         off[nst]  = offset;
5209         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5210                                     phase->intcon(con1), T_INT, MemNode::unordered);
5211       }
5212     }
5213 
5214     // Insert second store first, then the first before the second.
5215     // Insert each one just before any overlapping non-constant stores.
5216     while (nst > 0) {
5217       Node* st1 = st[--nst];
5218       C->copy_node_notes_to(st1, old);
5219       st1 = phase->transform(st1);
5220       offset = off[nst];
5221       assert(offset >= header_size, "do not smash header");
5222       int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5223       guarantee(ins_idx != 0, "must re-insert constant store");
5224       if (ins_idx < 0)  ins_idx = -ins_idx;  // never overlap
5225       if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5226         set_req(--ins_idx, st1);
5227       else
5228         ins_req(ins_idx, st1);
5229     }
5230   }
5231 
5232   if (PrintCompilation && WizardMode)
5233     tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5234                   old_subword, old_long, new_int, new_long);
5235   if (C->log() != nullptr)
5236     C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5237                    old_subword, old_long, new_int, new_long);
5238 
5239   // Clean up any remaining occurrences of zmem:
5240   remove_extra_zeroes();
5241 }
5242 
5243 // Explore forward from in(start) to find the first fully initialized
5244 // word, and return its offset.  Skip groups of subword stores which
5245 // together initialize full words.  If in(start) is itself part of a
5246 // fully initialized word, return the offset of in(start).  If there
5247 // are no following full-word stores, or if something is fishy, return
5248 // a negative value.
5249 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5250   int       int_map = 0;
5251   intptr_t  int_map_off = 0;
5252   const int FULL_MAP = right_n_bits(BytesPerInt);  // the int_map we hope for
5253 
5254   for (uint i = start, limit = req(); i < limit; i++) {
5255     Node* st = in(i);
5256 
5257     intptr_t st_off = get_store_offset(st, phase);
5258     if (st_off < 0)  break;  // return conservative answer
5259 
5260     int st_size = st->as_Store()->memory_size();
5261     if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5262       return st_off;            // we found a complete word init
5263     }
5264 
5265     // update the map:
5266 
5267     intptr_t this_int_off = align_down(st_off, BytesPerInt);
5268     if (this_int_off != int_map_off) {
5269       // reset the map:
5270       int_map = 0;
5271       int_map_off = this_int_off;
5272     }
5273 
5274     int subword_off = st_off - this_int_off;
5275     int_map |= right_n_bits(st_size) << subword_off;
5276     if ((int_map & FULL_MAP) == FULL_MAP) {
5277       return this_int_off;      // we found a complete word init
5278     }
5279 
5280     // Did this store hit or cross the word boundary?
5281     intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5282     if (next_int_off == this_int_off + BytesPerInt) {
5283       // We passed the current int, without fully initializing it.
5284       int_map_off = next_int_off;
5285       int_map >>= BytesPerInt;
5286     } else if (next_int_off > this_int_off + BytesPerInt) {
5287       // We passed the current and next int.
5288       return this_int_off + BytesPerInt;
5289     }
5290   }
5291 
5292   return -1;
5293 }
5294 
5295 
5296 // Called when the associated AllocateNode is expanded into CFG.
5297 // At this point, we may perform additional optimizations.
5298 // Linearize the stores by ascending offset, to make memory
5299 // activity as coherent as possible.
5300 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5301                                       intptr_t header_size,
5302                                       Node* size_in_bytes,
5303                                       PhaseIterGVN* phase) {
5304   assert(!is_complete(), "not already complete");
5305   assert(stores_are_sane(phase), "");
5306   assert(allocation() != nullptr, "must be present");
5307 
5308   remove_extra_zeroes();
5309 
5310   if (ReduceFieldZeroing || ReduceBulkZeroing)
5311     // reduce instruction count for common initialization patterns
5312     coalesce_subword_stores(header_size, size_in_bytes, phase);
5313 
5314   Node* zmem = zero_memory();   // initially zero memory state
5315   Node* inits = zmem;           // accumulating a linearized chain of inits
5316   #ifdef ASSERT
5317   intptr_t first_offset = allocation()->minimum_header_size();
5318   intptr_t last_init_off = first_offset;  // previous init offset
5319   intptr_t last_init_end = first_offset;  // previous init offset+size
5320   intptr_t last_tile_end = first_offset;  // previous tile offset+size
5321   #endif
5322   intptr_t zeroes_done = header_size;
5323 
5324   bool do_zeroing = true;       // we might give up if inits are very sparse
5325   int  big_init_gaps = 0;       // how many large gaps have we seen?
5326 
5327   if (UseTLAB && ZeroTLAB)  do_zeroing = false;
5328   if (!ReduceFieldZeroing && !ReduceBulkZeroing)  do_zeroing = false;
5329 
5330   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5331     Node* st = in(i);
5332     intptr_t st_off = get_store_offset(st, phase);
5333     if (st_off < 0)
5334       break;                    // unknown junk in the inits
5335     if (st->in(MemNode::Memory) != zmem)
5336       break;                    // complicated store chains somehow in list
5337 
5338     int st_size = st->as_Store()->memory_size();
5339     intptr_t next_init_off = st_off + st_size;
5340 
5341     if (do_zeroing && zeroes_done < next_init_off) {
5342       // See if this store needs a zero before it or under it.
5343       intptr_t zeroes_needed = st_off;
5344 
5345       if (st_size < BytesPerInt) {
5346         // Look for subword stores which only partially initialize words.
5347         // If we find some, we must lay down some word-level zeroes first,
5348         // underneath the subword stores.
5349         //
5350         // Examples:
5351         //   byte[] a = { p,q,r,s }  =>  a[0]=p,a[1]=q,a[2]=r,a[3]=s
5352         //   byte[] a = { x,y,0,0 }  =>  a[0..3] = 0, a[0]=x,a[1]=y
5353         //   byte[] a = { 0,0,z,0 }  =>  a[0..3] = 0, a[2]=z
5354         //
5355         // Note:  coalesce_subword_stores may have already done this,
5356         // if it was prompted by constant non-zero subword initializers.
5357         // But this case can still arise with non-constant stores.
5358 
5359         intptr_t next_full_store = find_next_fullword_store(i, phase);
5360 
5361         // In the examples above:
5362         //   in(i)          p   q   r   s     x   y     z
5363         //   st_off        12  13  14  15    12  13    14
5364         //   st_size        1   1   1   1     1   1     1
5365         //   next_full_s.  12  16  16  16    16  16    16
5366         //   z's_done      12  16  16  16    12  16    12
5367         //   z's_needed    12  16  16  16    16  16    16
5368         //   zsize          0   0   0   0     4   0     4
5369         if (next_full_store < 0) {
5370           // Conservative tack:  Zero to end of current word.
5371           zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5372         } else {
5373           // Zero to beginning of next fully initialized word.
5374           // Or, don't zero at all, if we are already in that word.
5375           assert(next_full_store >= zeroes_needed, "must go forward");
5376           assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5377           zeroes_needed = next_full_store;
5378         }
5379       }
5380 
5381       if (zeroes_needed > zeroes_done) {
5382         intptr_t zsize = zeroes_needed - zeroes_done;
5383         // Do some incremental zeroing on rawmem, in parallel with inits.
5384         zeroes_done = align_down(zeroes_done, BytesPerInt);
5385         rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5386                                               zeroes_done, zeroes_needed,
5387                                               phase);
5388         zeroes_done = zeroes_needed;
5389         if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5390           do_zeroing = false;   // leave the hole, next time
5391       }
5392     }
5393 
5394     // Collect the store and move on:
5395     phase->replace_input_of(st, MemNode::Memory, inits);
5396     inits = st;                 // put it on the linearized chain
5397     set_req(i, zmem);           // unhook from previous position
5398 
5399     if (zeroes_done == st_off)
5400       zeroes_done = next_init_off;
5401 
5402     assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5403 
5404     #ifdef ASSERT
5405     // Various order invariants.  Weaker than stores_are_sane because
5406     // a large constant tile can be filled in by smaller non-constant stores.
5407     assert(st_off >= last_init_off, "inits do not reverse");
5408     last_init_off = st_off;
5409     const Type* val = nullptr;
5410     if (st_size >= BytesPerInt &&
5411         (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5412         (int)val->basic_type() < (int)T_OBJECT) {
5413       assert(st_off >= last_tile_end, "tiles do not overlap");
5414       assert(st_off >= last_init_end, "tiles do not overwrite inits");
5415       last_tile_end = MAX2(last_tile_end, next_init_off);
5416     } else {
5417       intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5418       assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5419       assert(st_off      >= last_init_end, "inits do not overlap");
5420       last_init_end = next_init_off;  // it's a non-tile
5421     }
5422     #endif //ASSERT
5423   }
5424 
5425   remove_extra_zeroes();        // clear out all the zmems left over
5426   add_req(inits);
5427 
5428   if (!(UseTLAB && ZeroTLAB)) {
5429     // If anything remains to be zeroed, zero it all now.
5430     zeroes_done = align_down(zeroes_done, BytesPerInt);
5431     // if it is the last unused 4 bytes of an instance, forget about it
5432     intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5433     if (zeroes_done + BytesPerLong >= size_limit) {
5434       AllocateNode* alloc = allocation();
5435       assert(alloc != nullptr, "must be present");
5436       if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5437         Node* klass_node = alloc->in(AllocateNode::KlassNode);
5438         ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5439         if (zeroes_done == k->layout_helper())
5440           zeroes_done = size_limit;
5441       }
5442     }
5443     if (zeroes_done < size_limit) {
5444       rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5445                                             zeroes_done, size_in_bytes, phase);
5446     }
5447   }
5448 
5449   set_complete(phase);
5450   return rawmem;
5451 }
5452 
5453 
5454 #ifdef ASSERT
5455 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5456   if (is_complete())
5457     return true;                // stores could be anything at this point
5458   assert(allocation() != nullptr, "must be present");
5459   intptr_t last_off = allocation()->minimum_header_size();
5460   for (uint i = InitializeNode::RawStores; i < req(); i++) {
5461     Node* st = in(i);
5462     intptr_t st_off = get_store_offset(st, phase);
5463     if (st_off < 0)  continue;  // ignore dead garbage
5464     if (last_off > st_off) {
5465       tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5466       this->dump(2);
5467       assert(false, "ascending store offsets");
5468       return false;
5469     }
5470     last_off = st_off + st->as_Store()->memory_size();
5471   }
5472   return true;
5473 }
5474 #endif //ASSERT
5475 
5476 
5477 
5478 
5479 //============================MergeMemNode=====================================
5480 //
5481 // SEMANTICS OF MEMORY MERGES:  A MergeMem is a memory state assembled from several
5482 // contributing store or call operations.  Each contributor provides the memory
5483 // state for a particular "alias type" (see Compile::alias_type).  For example,
5484 // if a MergeMem has an input X for alias category #6, then any memory reference
5485 // to alias category #6 may use X as its memory state input, as an exact equivalent
5486 // to using the MergeMem as a whole.
5487 //   Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5488 //
5489 // (Here, the <N> notation gives the index of the relevant adr_type.)
5490 //
5491 // In one special case (and more cases in the future), alias categories overlap.
5492 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5493 // states.  Therefore, if a MergeMem has only one contributing input W for Bot,
5494 // it is exactly equivalent to that state W:
5495 //   MergeMem(<Bot>: W) <==> W
5496 //
5497 // Usually, the merge has more than one input.  In that case, where inputs
5498 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5499 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5500 //   Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5501 //   Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5502 //
5503 // A merge can take a "wide" memory state as one of its narrow inputs.
5504 // This simply means that the merge observes out only the relevant parts of
5505 // the wide input.  That is, wide memory states arriving at narrow merge inputs
5506 // are implicitly "filtered" or "sliced" as necessary.  (This is rare.)
5507 //
5508 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5509 // and that memory slices "leak through":
5510 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5511 //
5512 // But, in such a cascade, repeated memory slices can "block the leak":
5513 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5514 //
5515 // In the last example, Y is not part of the combined memory state of the
5516 // outermost MergeMem.  The system must, of course, prevent unschedulable
5517 // memory states from arising, so you can be sure that the state Y is somehow
5518 // a precursor to state Y'.
5519 //
5520 //
5521 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5522 // of each MergeMemNode array are exactly the numerical alias indexes, including
5523 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw.  The functions
5524 // Compile::alias_type (and kin) produce and manage these indexes.
5525 //
5526 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5527 // (Note that this provides quick access to the top node inside MergeMem methods,
5528 // without the need to reach out via TLS to Compile::current.)
5529 //
5530 // As a consequence of what was just described, a MergeMem that represents a full
5531 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5532 // containing all alias categories.
5533 //
5534 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5535 //
5536 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5537 // a memory state for the alias type <N>, or else the top node, meaning that
5538 // there is no particular input for that alias type.  Note that the length of
5539 // a MergeMem is variable, and may be extended at any time to accommodate new
5540 // memory states at larger alias indexes.  When merges grow, they are of course
5541 // filled with "top" in the unused in() positions.
5542 //
5543 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5544 // (Top was chosen because it works smoothly with passes like GCM.)
5545 //
5546 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM.  (It is
5547 // the type of random VM bits like TLS references.)  Since it is always the
5548 // first non-Bot memory slice, some low-level loops use it to initialize an
5549 // index variable:  for (i = AliasIdxRaw; i < req(); i++).
5550 //
5551 //
5552 // ACCESSORS:  There is a special accessor MergeMemNode::base_memory which returns
5553 // the distinguished "wide" state.  The accessor MergeMemNode::memory_at(N) returns
5554 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5555 // it returns the base memory.  To prevent bugs, memory_at does not accept <Top>
5556 // or <Bot> indexes.  The iterator MergeMemStream provides robust iteration over
5557 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5558 //
5559 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5560 // really that different from the other memory inputs.  An abbreviation called
5561 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5562 //
5563 //
5564 // PARTIAL MEMORY STATES:  During optimization, MergeMem nodes may arise that represent
5565 // partial memory states.  When a Phi splits through a MergeMem, the copy of the Phi
5566 // that "emerges though" the base memory will be marked as excluding the alias types
5567 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5568 //
5569 //   Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5570 //     ==Ideal=>  MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5571 //
5572 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5573 // (It is currently unimplemented.)  As you can see, the resulting merge is
5574 // actually a disjoint union of memory states, rather than an overlay.
5575 //
5576 
5577 //------------------------------MergeMemNode-----------------------------------
5578 Node* MergeMemNode::make_empty_memory() {
5579   Node* empty_memory = (Node*) Compile::current()->top();
5580   assert(empty_memory->is_top(), "correct sentinel identity");
5581   return empty_memory;
5582 }
5583 
5584 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5585   init_class_id(Class_MergeMem);
5586   // all inputs are nullified in Node::Node(int)
5587   // set_input(0, nullptr);  // no control input
5588 
5589   // Initialize the edges uniformly to top, for starters.
5590   Node* empty_mem = make_empty_memory();
5591   for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5592     init_req(i,empty_mem);
5593   }
5594   assert(empty_memory() == empty_mem, "");
5595 
5596   if( new_base != nullptr && new_base->is_MergeMem() ) {
5597     MergeMemNode* mdef = new_base->as_MergeMem();
5598     assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5599     for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5600       mms.set_memory(mms.memory2());
5601     }
5602     assert(base_memory() == mdef->base_memory(), "");
5603   } else {
5604     set_base_memory(new_base);
5605   }
5606 }
5607 
5608 // Make a new, untransformed MergeMem with the same base as 'mem'.
5609 // If mem is itself a MergeMem, populate the result with the same edges.
5610 MergeMemNode* MergeMemNode::make(Node* mem) {
5611   return new MergeMemNode(mem);
5612 }
5613 
5614 //------------------------------cmp--------------------------------------------
5615 uint MergeMemNode::hash() const { return NO_HASH; }
5616 bool MergeMemNode::cmp( const Node &n ) const {
5617   return (&n == this);          // Always fail except on self
5618 }
5619 
5620 //------------------------------Identity---------------------------------------
5621 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5622   // Identity if this merge point does not record any interesting memory
5623   // disambiguations.
5624   Node* base_mem = base_memory();
5625   Node* empty_mem = empty_memory();
5626   if (base_mem != empty_mem) {  // Memory path is not dead?
5627     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5628       Node* mem = in(i);
5629       if (mem != empty_mem && mem != base_mem) {
5630         return this;            // Many memory splits; no change
5631       }
5632     }
5633   }
5634   return base_mem;              // No memory splits; ID on the one true input
5635 }
5636 
5637 //------------------------------Ideal------------------------------------------
5638 // This method is invoked recursively on chains of MergeMem nodes
5639 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5640   // Remove chain'd MergeMems
5641   //
5642   // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5643   // relative to the "in(Bot)".  Since we are patching both at the same time,
5644   // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5645   // but rewrite each "in(i)" relative to the new "in(Bot)".
5646   Node *progress = nullptr;
5647 
5648 
5649   Node* old_base = base_memory();
5650   Node* empty_mem = empty_memory();
5651   if (old_base == empty_mem)
5652     return nullptr; // Dead memory path.
5653 
5654   MergeMemNode* old_mbase;
5655   if (old_base != nullptr && old_base->is_MergeMem())
5656     old_mbase = old_base->as_MergeMem();
5657   else
5658     old_mbase = nullptr;
5659   Node* new_base = old_base;
5660 
5661   // simplify stacked MergeMems in base memory
5662   if (old_mbase)  new_base = old_mbase->base_memory();
5663 
5664   // the base memory might contribute new slices beyond my req()
5665   if (old_mbase)  grow_to_match(old_mbase);
5666 
5667   // Note:  We do not call verify_sparse on entry, because inputs
5668   // can normalize to the base_memory via subsume_node or similar
5669   // mechanisms.  This method repairs that damage.
5670 
5671   assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5672 
5673   // Look at each slice.
5674   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5675     Node* old_in = in(i);
5676     // calculate the old memory value
5677     Node* old_mem = old_in;
5678     if (old_mem == empty_mem)  old_mem = old_base;
5679     assert(old_mem == memory_at(i), "");
5680 
5681     // maybe update (reslice) the old memory value
5682 
5683     // simplify stacked MergeMems
5684     Node* new_mem = old_mem;
5685     MergeMemNode* old_mmem;
5686     if (old_mem != nullptr && old_mem->is_MergeMem())
5687       old_mmem = old_mem->as_MergeMem();
5688     else
5689       old_mmem = nullptr;
5690     if (old_mmem == this) {
5691       // This can happen if loops break up and safepoints disappear.
5692       // A merge of BotPtr (default) with a RawPtr memory derived from a
5693       // safepoint can be rewritten to a merge of the same BotPtr with
5694       // the BotPtr phi coming into the loop.  If that phi disappears
5695       // also, we can end up with a self-loop of the mergemem.
5696       // In general, if loops degenerate and memory effects disappear,
5697       // a mergemem can be left looking at itself.  This simply means
5698       // that the mergemem's default should be used, since there is
5699       // no longer any apparent effect on this slice.
5700       // Note: If a memory slice is a MergeMem cycle, it is unreachable
5701       //       from start.  Update the input to TOP.
5702       new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5703     }
5704     else if (old_mmem != nullptr) {
5705       new_mem = old_mmem->memory_at(i);
5706     }
5707     // else preceding memory was not a MergeMem
5708 
5709     // maybe store down a new value
5710     Node* new_in = new_mem;
5711     if (new_in == new_base)  new_in = empty_mem;
5712 
5713     if (new_in != old_in) {
5714       // Warning:  Do not combine this "if" with the previous "if"
5715       // A memory slice might have be be rewritten even if it is semantically
5716       // unchanged, if the base_memory value has changed.
5717       set_req_X(i, new_in, phase);
5718       progress = this;          // Report progress
5719     }
5720   }
5721 
5722   if (new_base != old_base) {
5723     set_req_X(Compile::AliasIdxBot, new_base, phase);
5724     // Don't use set_base_memory(new_base), because we need to update du.
5725     assert(base_memory() == new_base, "");
5726     progress = this;
5727   }
5728 
5729   if( base_memory() == this ) {
5730     // a self cycle indicates this memory path is dead
5731     set_req(Compile::AliasIdxBot, empty_mem);
5732   }
5733 
5734   // Resolve external cycles by calling Ideal on a MergeMem base_memory
5735   // Recursion must occur after the self cycle check above
5736   if( base_memory()->is_MergeMem() ) {
5737     MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5738     Node *m = phase->transform(new_mbase);  // Rollup any cycles
5739     if( m != nullptr &&
5740         (m->is_top() ||
5741          (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5742       // propagate rollup of dead cycle to self
5743       set_req(Compile::AliasIdxBot, empty_mem);
5744     }
5745   }
5746 
5747   if( base_memory() == empty_mem ) {
5748     progress = this;
5749     // Cut inputs during Parse phase only.
5750     // During Optimize phase a dead MergeMem node will be subsumed by Top.
5751     if( !can_reshape ) {
5752       for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5753         if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5754       }
5755     }
5756   }
5757 
5758   if( !progress && base_memory()->is_Phi() && can_reshape ) {
5759     // Check if PhiNode::Ideal's "Split phis through memory merges"
5760     // transform should be attempted. Look for this->phi->this cycle.
5761     uint merge_width = req();
5762     if (merge_width > Compile::AliasIdxRaw) {
5763       PhiNode* phi = base_memory()->as_Phi();
5764       for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5765         if (phi->in(i) == this) {
5766           phase->is_IterGVN()->_worklist.push(phi);
5767           break;
5768         }
5769       }
5770     }
5771   }
5772 
5773   assert(progress || verify_sparse(), "please, no dups of base");
5774   return progress;
5775 }
5776 
5777 //-------------------------set_base_memory-------------------------------------
5778 void MergeMemNode::set_base_memory(Node *new_base) {
5779   Node* empty_mem = empty_memory();
5780   set_req(Compile::AliasIdxBot, new_base);
5781   assert(memory_at(req()) == new_base, "must set default memory");
5782   // Clear out other occurrences of new_base:
5783   if (new_base != empty_mem) {
5784     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5785       if (in(i) == new_base)  set_req(i, empty_mem);
5786     }
5787   }
5788 }
5789 
5790 //------------------------------out_RegMask------------------------------------
5791 const RegMask &MergeMemNode::out_RegMask() const {
5792   return RegMask::Empty;
5793 }
5794 
5795 //------------------------------dump_spec--------------------------------------
5796 #ifndef PRODUCT
5797 void MergeMemNode::dump_spec(outputStream *st) const {
5798   st->print(" {");
5799   Node* base_mem = base_memory();
5800   for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5801     Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
5802     if (mem == base_mem) { st->print(" -"); continue; }
5803     st->print( " N%d:", mem->_idx );
5804     Compile::current()->get_adr_type(i)->dump_on(st);
5805   }
5806   st->print(" }");
5807 }
5808 #endif // !PRODUCT
5809 
5810 
5811 #ifdef ASSERT
5812 static bool might_be_same(Node* a, Node* b) {
5813   if (a == b)  return true;
5814   if (!(a->is_Phi() || b->is_Phi()))  return false;
5815   // phis shift around during optimization
5816   return true;  // pretty stupid...
5817 }
5818 
5819 // verify a narrow slice (either incoming or outgoing)
5820 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5821   if (!VerifyAliases)                return;  // don't bother to verify unless requested
5822   if (VMError::is_error_reported())  return;  // muzzle asserts when debugging an error
5823   if (Node::in_dump())               return;  // muzzle asserts when printing
5824   assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5825   assert(n != nullptr, "");
5826   // Elide intervening MergeMem's
5827   while (n->is_MergeMem()) {
5828     n = n->as_MergeMem()->memory_at(alias_idx);
5829   }
5830   Compile* C = Compile::current();
5831   const TypePtr* n_adr_type = n->adr_type();
5832   if (n == m->empty_memory()) {
5833     // Implicit copy of base_memory()
5834   } else if (n_adr_type != TypePtr::BOTTOM) {
5835     assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
5836     assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5837   } else {
5838     // A few places like make_runtime_call "know" that VM calls are narrow,
5839     // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5840     bool expected_wide_mem = false;
5841     if (n == m->base_memory()) {
5842       expected_wide_mem = true;
5843     } else if (alias_idx == Compile::AliasIdxRaw ||
5844                n == m->memory_at(Compile::AliasIdxRaw)) {
5845       expected_wide_mem = true;
5846     } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5847       // memory can "leak through" calls on channels that
5848       // are write-once.  Allow this also.
5849       expected_wide_mem = true;
5850     }
5851     assert(expected_wide_mem, "expected narrow slice replacement");
5852   }
5853 }
5854 #else // !ASSERT
5855 #define verify_memory_slice(m,i,n) (void)(0)  // PRODUCT version is no-op
5856 #endif
5857 
5858 
5859 //-----------------------------memory_at---------------------------------------
5860 Node* MergeMemNode::memory_at(uint alias_idx) const {
5861   assert(alias_idx >= Compile::AliasIdxRaw ||
5862          (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
5863          "must avoid base_memory and AliasIdxTop");
5864 
5865   // Otherwise, it is a narrow slice.
5866   Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5867   if (is_empty_memory(n)) {
5868     // the array is sparse; empty slots are the "top" node
5869     n = base_memory();
5870     assert(Node::in_dump()
5871            || n == nullptr || n->bottom_type() == Type::TOP
5872            || n->adr_type() == nullptr // address is TOP
5873            || n->adr_type() == TypePtr::BOTTOM
5874            || n->adr_type() == TypeRawPtr::BOTTOM
5875            || !Compile::current()->do_aliasing(),
5876            "must be a wide memory");
5877     // do_aliasing == false if we are organizing the memory states manually.
5878     // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5879   } else {
5880     // make sure the stored slice is sane
5881     #ifdef ASSERT
5882     if (VMError::is_error_reported() || Node::in_dump()) {
5883     } else if (might_be_same(n, base_memory())) {
5884       // Give it a pass:  It is a mostly harmless repetition of the base.
5885       // This can arise normally from node subsumption during optimization.
5886     } else {
5887       verify_memory_slice(this, alias_idx, n);
5888     }
5889     #endif
5890   }
5891   return n;
5892 }
5893 
5894 //---------------------------set_memory_at-------------------------------------
5895 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5896   verify_memory_slice(this, alias_idx, n);
5897   Node* empty_mem = empty_memory();
5898   if (n == base_memory())  n = empty_mem;  // collapse default
5899   uint need_req = alias_idx+1;
5900   if (req() < need_req) {
5901     if (n == empty_mem)  return;  // already the default, so do not grow me
5902     // grow the sparse array
5903     do {
5904       add_req(empty_mem);
5905     } while (req() < need_req);
5906   }
5907   set_req( alias_idx, n );
5908 }
5909 
5910 
5911 
5912 //--------------------------iteration_setup------------------------------------
5913 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5914   if (other != nullptr) {
5915     grow_to_match(other);
5916     // invariant:  the finite support of mm2 is within mm->req()
5917     #ifdef ASSERT
5918     for (uint i = req(); i < other->req(); i++) {
5919       assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5920     }
5921     #endif
5922   }
5923   // Replace spurious copies of base_memory by top.
5924   Node* base_mem = base_memory();
5925   if (base_mem != nullptr && !base_mem->is_top()) {
5926     for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5927       if (in(i) == base_mem)
5928         set_req(i, empty_memory());
5929     }
5930   }
5931 }
5932 
5933 //---------------------------grow_to_match-------------------------------------
5934 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5935   Node* empty_mem = empty_memory();
5936   assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5937   // look for the finite support of the other memory
5938   for (uint i = other->req(); --i >= req(); ) {
5939     if (other->in(i) != empty_mem) {
5940       uint new_len = i+1;
5941       while (req() < new_len)  add_req(empty_mem);
5942       break;
5943     }
5944   }
5945 }
5946 
5947 //---------------------------verify_sparse-------------------------------------
5948 #ifndef PRODUCT
5949 bool MergeMemNode::verify_sparse() const {
5950   assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5951   Node* base_mem = base_memory();
5952   // The following can happen in degenerate cases, since empty==top.
5953   if (is_empty_memory(base_mem))  return true;
5954   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5955     assert(in(i) != nullptr, "sane slice");
5956     if (in(i) == base_mem)  return false;  // should have been the sentinel value!
5957   }
5958   return true;
5959 }
5960 
5961 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5962   Node* n;
5963   n = mm->in(idx);
5964   if (mem == n)  return true;  // might be empty_memory()
5965   n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5966   if (mem == n)  return true;
5967   return false;
5968 }
5969 #endif // !PRODUCT