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 "ci/ciFlatArrayKlass.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "compiler/compileLog.hpp"
  30 #include "gc/shared/barrierSet.hpp"
  31 #include "gc/shared/c2/barrierSetC2.hpp"
  32 #include "gc/shared/tlab_globals.hpp"
  33 #include "memory/allocation.inline.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "oops/objArrayKlass.hpp"
  36 #include "opto/addnode.hpp"
  37 #include "opto/arraycopynode.hpp"
  38 #include "opto/cfgnode.hpp"
  39 #include "opto/regalloc.hpp"
  40 #include "opto/compile.hpp"
  41 #include "opto/connode.hpp"
  42 #include "opto/convertnode.hpp"
  43 #include "opto/inlinetypenode.hpp"
  44 #include "opto/loopnode.hpp"
  45 #include "opto/machnode.hpp"
  46 #include "opto/matcher.hpp"
  47 #include "opto/memnode.hpp"
  48 #include "opto/mempointer.hpp"
  49 #include "opto/mulnode.hpp"
  50 #include "opto/narrowptrnode.hpp"
  51 #include "opto/phaseX.hpp"
  52 #include "opto/regmask.hpp"
  53 #include "opto/rootnode.hpp"
  54 #include "opto/traceMergeStoresTag.hpp"
  55 #include "opto/vectornode.hpp"
  56 #include "utilities/align.hpp"
  57 #include "utilities/copy.hpp"
  58 #include "utilities/macros.hpp"
  59 #include "utilities/powerOfTwo.hpp"
  60 #include "utilities/vmError.hpp"
  61 
  62 // Portions of code courtesy of Clifford Click
  63 
  64 // Optimization - Graph Style
  65 
  66 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem,  const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
  67 
  68 //=============================================================================
  69 uint MemNode::size_of() const { return sizeof(*this); }
  70 
  71 const TypePtr *MemNode::adr_type() const {
  72   Node* adr = in(Address);
  73   if (adr == nullptr)  return nullptr; // node is dead
  74   const TypePtr* cross_check = nullptr;
  75   DEBUG_ONLY(cross_check = _adr_type);
  76   return calculate_adr_type(adr->bottom_type(), cross_check);
  77 }
  78 
  79 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
  80   if (adr != nullptr) {
  81     if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
  82       return true;
  83     }
  84   }
  85   return false;
  86 }
  87 
  88 #ifndef PRODUCT
  89 void MemNode::dump_spec(outputStream *st) const {
  90   if (in(Address) == nullptr)  return; // node is dead
  91 #ifndef ASSERT
  92   // fake the missing field
  93   const TypePtr* _adr_type = nullptr;
  94   if (in(Address) != nullptr)
  95     _adr_type = in(Address)->bottom_type()->isa_ptr();
  96 #endif
  97   dump_adr_type(this, _adr_type, st);
  98 
  99   Compile* C = Compile::current();
 100   if (C->alias_type(_adr_type)->is_volatile()) {
 101     st->print(" Volatile!");
 102   }
 103   if (_unaligned_access) {
 104     st->print(" unaligned");
 105   }
 106   if (_mismatched_access) {
 107     st->print(" mismatched");
 108   }
 109   if (_unsafe_access) {
 110     st->print(" unsafe");
 111   }
 112 }
 113 
 114 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
 115   st->print(" @");
 116   if (adr_type == nullptr) {
 117     st->print("null");
 118   } else {
 119     adr_type->dump_on(st);
 120     Compile* C = Compile::current();
 121     Compile::AliasType* atp = nullptr;
 122     if (C->have_alias_type(adr_type))  atp = C->alias_type(adr_type);
 123     if (atp == nullptr)
 124       st->print(", idx=?\?;");
 125     else if (atp->index() == Compile::AliasIdxBot)
 126       st->print(", idx=Bot;");
 127     else if (atp->index() == Compile::AliasIdxTop)
 128       st->print(", idx=Top;");
 129     else if (atp->index() == Compile::AliasIdxRaw)
 130       st->print(", idx=Raw;");
 131     else {
 132       ciField* field = atp->field();
 133       if (field) {
 134         st->print(", name=");
 135         field->print_name_on(st);
 136       }
 137       st->print(", idx=%d;", atp->index());
 138     }
 139   }
 140 }
 141 
 142 extern void print_alias_types();
 143 
 144 #endif
 145 
 146 // If call is a constructor call on receiver, returns the class which declares the target method,
 147 // else returns nullptr. This information can then be used to deduce if call modifies a field of
 148 // receiver. Specifically, if the field is declared in a class that is a subclass of the one
 149 // declaring the constructor, then the field is set inside the constructor, else the field must be
 150 // set before the constructor invocation. E.g. A field Super.x will be set during the execution of
 151 // Sub::<init>, while a field Sub.y must be set before Super::<init> is invoked.
 152 static ciInstanceKlass* find_constructor_call_method_holder(Node* call, Node* receiver) {
 153   if (!call->is_CallJava()) {
 154     return nullptr;
 155   }
 156 
 157   ciMethod* target = call->as_CallJava()->method();
 158   if (target == nullptr || !target->is_object_constructor()) {
 159     return nullptr;
 160   }
 161 
 162   assert(call->req() > TypeFunc::Parms, "constructor must have at least 1 argument");
 163   Node* parm = call->in(TypeFunc::Parms)->uncast();
 164   receiver = receiver->uncast();
 165   if (parm == receiver || (parm->is_InlineType() && parm->as_InlineType()->get_oop()->uncast() == receiver)) {
 166     return target->holder();
 167   }
 168 
 169   return nullptr;
 170 }
 171 
 172 // Find the memory output corresponding to the fall-through path of a call
 173 static Node* find_call_fallthrough_mem_output(CallNode* call) {
 174   ResourceMark rm;
 175   CallProjections* projs = call->extract_projections(false, false);
 176   Node* res = projs->fallthrough_memproj;
 177   assert(res != nullptr, "must have a fallthrough mem output");
 178   return res;
 179 }
 180 
 181 // Try to find a better memory input for a load from a strict final field of an object that is
 182 // allocated in the current compilation unit, or is the first parameter when we are in a
 183 // constructor
 184 static Node* optimize_strict_final_load_memory_from_local_object(ciField* field, ProjNode* base_uncasted) {
 185   if (!EnableValhalla) {
 186     // In this method we depends on the fact that strict fields are set before the invocation of
 187     // super(), I'm not sure if this is true without Valhalla
 188     return nullptr;
 189   }
 190 
 191   // The node that can be passed into a constructor
 192   Node* base = base_uncasted;
 193   if (!base_uncasted->is_Parm()) {
 194     assert(base_uncasted->_con == AllocateNode::RawAddress && base_uncasted->in(0)->is_Allocate(), "must be the RawAddress of an AllocateNode");
 195     base = base_uncasted->in(0)->as_Allocate()->result_cast();
 196     assert(base != nullptr && base->in(1) == base_uncasted, "must find a valid base");
 197   }
 198 
 199   // Try to see if there is a constructor call on the base
 200   for (DUIterator_Fast imax, i = base->fast_outs(imax); i < imax; i++) {
 201     Node* out = base->fast_out(i);
 202     ciInstanceKlass* target_holder = find_constructor_call_method_holder(out, base);
 203     if (target_holder == nullptr) {
 204       continue;
 205     } else if (target_holder->is_subclass_of(field->holder())) {
 206       return find_call_fallthrough_mem_output(out->as_CallJava());
 207     } else {
 208       Node* res = out->in(TypeFunc::Memory);
 209       assert(res != nullptr, "should have a memory input");
 210       return res;
 211     }
 212   }
 213 
 214   return nullptr;
 215 }
 216 
 217 // Try to find a better memory input for a load from a strict final field
 218 static Node* try_optimize_strict_final_load_memory(PhaseGVN* phase, ciField* field, Node* adr, ProjNode*& base_local) {
 219   intptr_t offset = 0;
 220   Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
 221   if (base == nullptr) {
 222     return nullptr;
 223   }
 224 
 225   Node* base_uncasted = base->uncast();
 226   if (base_uncasted->is_Proj()) {
 227     MultiNode* multi = base_uncasted->in(0)->as_Multi();
 228     if (multi->is_Allocate()) {
 229       // The result of an AllocateNode, try to find the constructor call
 230       base_local = base_uncasted->as_Proj();
 231       return optimize_strict_final_load_memory_from_local_object(field, base_uncasted->as_Proj());
 232     } else if (multi->is_Call()) {
 233       // The oop is returned from a call, the memory can be the fallthrough output of the call
 234       return find_call_fallthrough_mem_output(multi->as_Call());
 235     } else if (multi->is_Start()) {
 236       // The oop is a parameter
 237       if (phase->C->method()->is_object_constructor() && base_uncasted->as_Proj()->_con == TypeFunc::Parms) {
 238         // The receiver of a constructor is similar to the result of an AllocateNode
 239         base_local = base_uncasted->as_Proj();
 240         return optimize_strict_final_load_memory_from_local_object(field, base_uncasted->as_Proj());
 241       } else {
 242         // Use the start memory otherwise
 243         return multi->proj_out(TypeFunc::Memory);
 244       }
 245     }
 246   }
 247 
 248   return nullptr;
 249 }
 250 
 251 // Whether a call can modify a strict final field of base_local, given that base_local is allocated
 252 // inside the current compilation unit, or is the first parameter when the compilation root is a
 253 // constructor. This is equivalent to asking whether base_local is the receiver of the constructor
 254 // invocation call and the class declaring the target method is a subclass of the class declaring
 255 // field.
 256 static bool call_can_modify_local_object(ciField* field, CallNode* call, Node* base_local) {
 257   ciInstanceKlass* target_holder = find_constructor_call_method_holder(call, base_local);
 258   return target_holder != nullptr && target_holder->is_subclass_of(field->holder());
 259 }
 260 
 261 Node* MemNode::optimize_simple_memory_chain(Node* mchain, const TypeOopPtr* t_oop, Node* load, PhaseGVN* phase) {
 262   assert(t_oop != nullptr, "sanity");
 263   bool is_instance = t_oop->is_known_instance_field();
 264 
 265   ciField* field = phase->C->alias_type(t_oop)->field();
 266   bool is_strict_final_load = false;
 267 
 268   // After macro expansion, an allocation may become a call, changing the memory input to the
 269   // memory output of that call would be illegal. As a result, disallow this transformation after
 270   // macro expansion.
 271   if (phase->is_IterGVN() && phase->C->allow_macro_nodes() && load != nullptr && load->is_Load() && !load->as_Load()->is_mismatched_access()) {
 272     if (EnableValhalla) {
 273       if (field != nullptr && (field->holder()->is_inlinetype() || field->holder()->is_abstract_value_klass())) {
 274         is_strict_final_load = true;
 275       }
 276 #ifdef ASSERT
 277       if (t_oop->is_inlinetypeptr() && t_oop->inline_klass()->contains_field_offset(t_oop->offset())) {
 278         assert(is_strict_final_load, "sanity check for basic cases");
 279       }
 280 #endif
 281     } else {
 282       is_strict_final_load = field != nullptr && t_oop->is_ptr_to_boxed_value();
 283     }
 284   }
 285 
 286   if (!is_instance && !is_strict_final_load) {
 287     return mchain;
 288   }
 289 
 290   Node* result = mchain;
 291   ProjNode* base_local = nullptr;
 292 
 293   if (is_strict_final_load) {
 294     Node* adr = load->in(MemNode::Address);
 295     assert(phase->type(adr) == t_oop, "inconsistent type");
 296     Node* tmp = try_optimize_strict_final_load_memory(phase, field, adr, base_local);
 297     if (tmp != nullptr) {
 298       result = tmp;
 299     }
 300   }
 301 
 302   uint instance_id = t_oop->instance_id();
 303   Node* start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
 304   Node* prev = nullptr;
 305   while (prev != result) {
 306     prev = result;
 307     if (result == start_mem) {
 308       // start_mem is the earliest memory possible
 309       break;
 310     }
 311 
 312     // skip over a call which does not affect this memory slice
 313     if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
 314       Node* proj_in = result->in(0);
 315       if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
 316         // This is the allocation that creates the object from which we are loading from
 317         break;
 318       } else if (proj_in->is_Call()) {
 319         // ArrayCopyNodes processed here as well
 320         CallNode* call = proj_in->as_Call();
 321         if (!call->may_modify(t_oop, phase)) {
 322           result = call->in(TypeFunc::Memory);
 323         } else if (is_strict_final_load && base_local != nullptr && !call_can_modify_local_object(field, call, base_local)) {
 324           result = call->in(TypeFunc::Memory);
 325         }
 326       } else if (proj_in->is_Initialize()) {
 327         AllocateNode* alloc = proj_in->as_Initialize()->allocation();
 328         // Stop if this is the initialization for the object instance which
 329         // contains this memory slice, otherwise skip over it.
 330         if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
 331           break;
 332         }
 333         if (is_instance) {
 334           result = proj_in->in(TypeFunc::Memory);
 335         } else if (is_strict_final_load) {
 336           Node* klass = alloc->in(AllocateNode::KlassNode);
 337           const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
 338           if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
 339             // Allocation of another type, must be another object
 340             result = proj_in->in(TypeFunc::Memory);
 341           } else if (base_local != nullptr && (base_local->is_Parm() || base_local->in(0) != alloc)) {
 342             // Allocation of another object
 343             result = proj_in->in(TypeFunc::Memory);
 344           }
 345         }
 346       } else if (proj_in->is_MemBar()) {
 347         ArrayCopyNode* ac = nullptr;
 348         if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
 349           break;
 350         }
 351         result = proj_in->in(TypeFunc::Memory);
 352       } else if (proj_in->is_top()) {
 353         break; // dead code
 354       } else {
 355         assert(false, "unexpected projection");
 356       }
 357     } else if (result->is_ClearArray()) {
 358       if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
 359         // Can not bypass initialization of the instance
 360         // we are looking for.
 361         break;
 362       }
 363       // Otherwise skip it (the call updated 'result' value).
 364     } else if (result->is_MergeMem()) {
 365       result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
 366     }
 367   }
 368   return result;
 369 }
 370 
 371 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
 372   const TypeOopPtr* t_oop = t_adr->isa_oopptr();
 373   if (t_oop == nullptr)
 374     return mchain;  // don't try to optimize non-oop types
 375   Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
 376   bool is_instance = t_oop->is_known_instance_field();
 377   PhaseIterGVN *igvn = phase->is_IterGVN();
 378   if (is_instance && igvn != nullptr && result->is_Phi()) {
 379     PhiNode *mphi = result->as_Phi();
 380     assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
 381     const TypePtr *t = mphi->adr_type();
 382     bool do_split = false;
 383     // In the following cases, Load memory input can be further optimized based on
 384     // its precise address type
 385     if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
 386       do_split = true;
 387     } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
 388       const TypeOopPtr* mem_t =
 389         t->is_oopptr()->cast_to_exactness(true)
 390         ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
 391         ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
 392       if (t_oop->isa_aryptr()) {
 393         mem_t = mem_t->is_aryptr()
 394                      ->cast_to_stable(t_oop->is_aryptr()->is_stable())
 395                      ->cast_to_size(t_oop->is_aryptr()->size())
 396                      ->cast_to_not_flat(t_oop->is_aryptr()->is_not_flat())
 397                      ->cast_to_not_null_free(t_oop->is_aryptr()->is_not_null_free())
 398                      ->with_offset(t_oop->is_aryptr()->offset())
 399                      ->is_aryptr();
 400       }
 401       do_split = mem_t == t_oop;
 402     }
 403     if (do_split) {
 404       // clone the Phi with our address type
 405       result = mphi->split_out_instance(t_adr, igvn);
 406     } else {
 407       assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
 408     }
 409   }
 410   return result;
 411 }
 412 
 413 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem,  const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
 414   uint alias_idx = phase->C->get_alias_index(tp);
 415   Node *mem = mmem;
 416 #ifdef ASSERT
 417   {
 418     // Check that current type is consistent with the alias index used during graph construction
 419     assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
 420     bool consistent =  adr_check == nullptr || adr_check->empty() ||
 421                        phase->C->must_alias(adr_check, alias_idx );
 422     // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
 423     if( !consistent && adr_check != nullptr && !adr_check->empty() &&
 424         tp->isa_aryptr() &&        tp->offset() == Type::OffsetBot &&
 425         adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
 426         ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
 427           adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
 428           adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
 429       // don't assert if it is dead code.
 430       consistent = true;
 431     }
 432     if( !consistent ) {
 433       st->print("alias_idx==%d, adr_check==", alias_idx);
 434       if( adr_check == nullptr ) {
 435         st->print("null");
 436       } else {
 437         adr_check->dump();
 438       }
 439       st->cr();
 440       print_alias_types();
 441       assert(consistent, "adr_check must match alias idx");
 442     }
 443   }
 444 #endif
 445   // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
 446   // means an array I have not precisely typed yet.  Do not do any
 447   // alias stuff with it any time soon.
 448   const TypeOopPtr *toop = tp->isa_oopptr();
 449   if (tp->base() != Type::AnyPtr &&
 450       !(toop &&
 451         toop->isa_instptr() &&
 452         toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
 453         toop->offset() == Type::OffsetBot)) {
 454     // compress paths and change unreachable cycles to TOP
 455     // If not, we can update the input infinitely along a MergeMem cycle
 456     // Equivalent code in PhiNode::Ideal
 457     Node* m  = phase->transform(mmem);
 458     // If transformed to a MergeMem, get the desired slice
 459     // Otherwise the returned node represents memory for every slice
 460     mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
 461     // Update input if it is progress over what we have now
 462   }
 463   return mem;
 464 }
 465 
 466 //--------------------------Ideal_common---------------------------------------
 467 // Look for degenerate control and memory inputs.  Bypass MergeMem inputs.
 468 // Unhook non-raw memories from complete (macro-expanded) initializations.
 469 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
 470   // If our control input is a dead region, kill all below the region
 471   Node *ctl = in(MemNode::Control);
 472   if (ctl && remove_dead_region(phase, can_reshape))
 473     return this;
 474   ctl = in(MemNode::Control);
 475   // Don't bother trying to transform a dead node
 476   if (ctl && ctl->is_top())  return NodeSentinel;
 477 
 478   PhaseIterGVN *igvn = phase->is_IterGVN();
 479   // Wait if control on the worklist.
 480   if (ctl && can_reshape && igvn != nullptr) {
 481     Node* bol = nullptr;
 482     Node* cmp = nullptr;
 483     if (ctl->in(0)->is_If()) {
 484       assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
 485       bol = ctl->in(0)->in(1);
 486       if (bol->is_Bool())
 487         cmp = ctl->in(0)->in(1)->in(1);
 488     }
 489     if (igvn->_worklist.member(ctl) ||
 490         (bol != nullptr && igvn->_worklist.member(bol)) ||
 491         (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
 492       // This control path may be dead.
 493       // Delay this memory node transformation until the control is processed.
 494       igvn->_worklist.push(this);
 495       return NodeSentinel; // caller will return null
 496     }
 497   }
 498   // Ignore if memory is dead, or self-loop
 499   Node *mem = in(MemNode::Memory);
 500   if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
 501   assert(mem != this, "dead loop in MemNode::Ideal");
 502 
 503   if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
 504     // This memory slice may be dead.
 505     // Delay this mem node transformation until the memory is processed.
 506     igvn->_worklist.push(this);
 507     return NodeSentinel; // caller will return null
 508   }
 509 
 510   Node *address = in(MemNode::Address);
 511   const Type *t_adr = phase->type(address);
 512   if (t_adr == Type::TOP)              return NodeSentinel; // caller will return null
 513 
 514   if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
 515     // Unsafe off-heap access with zero address. Remove access and other control users
 516     // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
 517     assert(ctl != nullptr, "unsafe accesses should be control dependent");
 518     for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
 519       Node* u = ctl->fast_out(i);
 520       if (u != ctl) {
 521         igvn->rehash_node_delayed(u);
 522         int nb = u->replace_edge(ctl, phase->C->top(), igvn);
 523         --i, imax -= nb;
 524       }
 525     }
 526     Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
 527     Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
 528     phase->C->root()->add_req(halt);
 529     return this;
 530   }
 531 
 532   if (can_reshape && igvn != nullptr &&
 533       (igvn->_worklist.member(address) ||
 534        (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
 535     // The address's base and type may change when the address is processed.
 536     // Delay this mem node transformation until the address is processed.
 537     igvn->_worklist.push(this);
 538     return NodeSentinel; // caller will return null
 539   }
 540 
 541   // Do NOT remove or optimize the next lines: ensure a new alias index
 542   // is allocated for an oop pointer type before Escape Analysis.
 543   // Note: C++ will not remove it since the call has side effect.
 544   if (t_adr->isa_oopptr()) {
 545     int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
 546   }
 547 
 548   Node* base = nullptr;
 549   if (address->is_AddP()) {
 550     base = address->in(AddPNode::Base);
 551   }
 552   if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
 553       !t_adr->isa_rawptr()) {
 554     // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
 555     // Skip this node optimization if its address has TOP base.
 556     return NodeSentinel; // caller will return null
 557   }
 558 
 559   // Avoid independent memory operations
 560   Node* old_mem = mem;
 561 
 562   // The code which unhooks non-raw memories from complete (macro-expanded)
 563   // initializations was removed. After macro-expansion all stores caught
 564   // by Initialize node became raw stores and there is no information
 565   // which memory slices they modify. So it is unsafe to move any memory
 566   // operation above these stores. Also in most cases hooked non-raw memories
 567   // were already unhooked by using information from detect_ptr_independence()
 568   // and find_previous_store().
 569 
 570   if (mem->is_MergeMem()) {
 571     MergeMemNode* mmem = mem->as_MergeMem();
 572     const TypePtr *tp = t_adr->is_ptr();
 573 
 574     mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
 575   }
 576 
 577   if (mem != old_mem) {
 578     set_req_X(MemNode::Memory, mem, phase);
 579     if (phase->type(mem) == Type::TOP) return NodeSentinel;
 580     return this;
 581   }
 582 
 583   // let the subclass continue analyzing...
 584   return nullptr;
 585 }
 586 
 587 // Helper function for proving some simple control dominations.
 588 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
 589 // Already assumes that 'dom' is available at 'sub', and that 'sub'
 590 // is not a constant (dominated by the method's StartNode).
 591 // Used by MemNode::find_previous_store to prove that the
 592 // control input of a memory operation predates (dominates)
 593 // an allocation it wants to look past.
 594 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
 595 // dominate 'sub', 'DomResult::NotDominate' if not,
 596 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
 597 // dead code, but at the end of IGVN, we know the definite result
 598 // once the dead code is cleaned up.
 599 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) {
 600   if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
 601     return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 602   }
 603 
 604   // Check 'dom'. Skip Proj and CatchProj nodes.
 605   dom = dom->find_exact_control(dom);
 606   if (dom == nullptr || dom->is_top()) {
 607     return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 608   }
 609 
 610   if (dom == sub) {
 611     // For the case when, for example, 'sub' is Initialize and the original
 612     // 'dom' is Proj node of the 'sub'.
 613     return DomResult::NotDominate;
 614   }
 615 
 616   if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
 617     return DomResult::Dominate;
 618   }
 619 
 620   // 'dom' dominates 'sub' if its control edge and control edges
 621   // of all its inputs dominate or equal to sub's control edge.
 622 
 623   // Currently 'sub' is either Allocate, Initialize or Start nodes.
 624   // Or Region for the check in LoadNode::Ideal();
 625   // 'sub' should have sub->in(0) != nullptr.
 626   assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
 627          sub->is_Region() || sub->is_Call(), "expecting only these nodes");
 628 
 629   // Get control edge of 'sub'.
 630   Node* orig_sub = sub;
 631   sub = sub->find_exact_control(sub->in(0));
 632   if (sub == nullptr || sub->is_top()) {
 633     return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 634   }
 635 
 636   assert(sub->is_CFG(), "expecting control");
 637 
 638   if (sub == dom) {
 639     return DomResult::Dominate;
 640   }
 641 
 642   if (sub->is_Start() || sub->is_Root()) {
 643     return DomResult::NotDominate;
 644   }
 645 
 646   {
 647     // Check all control edges of 'dom'.
 648 
 649     ResourceMark rm;
 650     Node_List nlist;
 651     Unique_Node_List dom_list;
 652 
 653     dom_list.push(dom);
 654     bool only_dominating_controls = false;
 655 
 656     for (uint next = 0; next < dom_list.size(); next++) {
 657       Node* n = dom_list.at(next);
 658       if (n == orig_sub) {
 659         return DomResult::NotDominate; // One of dom's inputs dominated by sub.
 660       }
 661       if (!n->is_CFG() && n->pinned()) {
 662         // Check only own control edge for pinned non-control nodes.
 663         n = n->find_exact_control(n->in(0));
 664         if (n == nullptr || n->is_top()) {
 665           return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 666         }
 667         assert(n->is_CFG(), "expecting control");
 668         dom_list.push(n);
 669       } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
 670         only_dominating_controls = true;
 671       } else if (n->is_CFG()) {
 672         DomResult dom_result = n->dominates(sub, nlist);
 673         if (dom_result == DomResult::Dominate) {
 674           only_dominating_controls = true;
 675         } else {
 676           return dom_result;
 677         }
 678       } else {
 679         // First, own control edge.
 680         Node* m = n->find_exact_control(n->in(0));
 681         if (m != nullptr) {
 682           if (m->is_top()) {
 683             return DomResult::EncounteredDeadCode; // Conservative answer for dead code
 684           }
 685           dom_list.push(m);
 686         }
 687         // Now, the rest of edges.
 688         uint cnt = n->req();
 689         for (uint i = 1; i < cnt; i++) {
 690           m = n->find_exact_control(n->in(i));
 691           if (m == nullptr || m->is_top()) {
 692             continue;
 693           }
 694           dom_list.push(m);
 695         }
 696       }
 697     }
 698     return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
 699   }
 700 }
 701 
 702 //---------------------detect_ptr_independence---------------------------------
 703 // Used by MemNode::find_previous_store to prove that two base
 704 // pointers are never equal.
 705 // The pointers are accompanied by their associated allocations,
 706 // if any, which have been previously discovered by the caller.
 707 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
 708                                       Node* p2, AllocateNode* a2,
 709                                       PhaseTransform* phase) {
 710   // Attempt to prove that these two pointers cannot be aliased.
 711   // They may both manifestly be allocations, and they should differ.
 712   // Or, if they are not both allocations, they can be distinct constants.
 713   // Otherwise, one is an allocation and the other a pre-existing value.
 714   if (a1 == nullptr && a2 == nullptr) {           // neither an allocation
 715     return (p1 != p2) && p1->is_Con() && p2->is_Con();
 716   } else if (a1 != nullptr && a2 != nullptr) {    // both allocations
 717     return (a1 != a2);
 718   } else if (a1 != nullptr) {                  // one allocation a1
 719     // (Note:  p2->is_Con implies p2->in(0)->is_Root, which dominates.)
 720     return all_controls_dominate(p2, a1);
 721   } else { //(a2 != null)                   // one allocation a2
 722     return all_controls_dominate(p1, a2);
 723   }
 724   return false;
 725 }
 726 
 727 
 728 // Find an arraycopy ac that produces the memory state represented by parameter mem.
 729 // Return ac if
 730 // (a) can_see_stored_value=true  and ac must have set the value for this load or if
 731 // (b) can_see_stored_value=false and ac could have set the value for this load or if
 732 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
 733 // In case (c) change the parameter mem to the memory input of ac to skip it
 734 // when searching stored value.
 735 // Otherwise return null.
 736 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
 737   ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
 738   if (ac != nullptr) {
 739     Node* ld_addp = in(MemNode::Address);
 740     Node* src = ac->in(ArrayCopyNode::Src);
 741     const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
 742 
 743     // This is a load from a cloned array. The corresponding arraycopy ac must
 744     // have set the value for the load and we can return ac but only if the load
 745     // is known to be within bounds. This is checked below.
 746     if (ary_t != nullptr && ld_addp->is_AddP()) {
 747       Node* ld_offs = ld_addp->in(AddPNode::Offset);
 748       BasicType ary_elem = ary_t->elem()->array_element_basic_type();
 749       jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
 750       jlong elemsize = type2aelembytes(ary_elem);
 751 
 752       const TypeX*   ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 753       const TypeInt* sizetype  = ary_t->size();
 754 
 755       if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
 756         // The load is known to be within bounds. It receives its value from ac.
 757         return ac;
 758       }
 759       // The load is known to be out-of-bounds.
 760     }
 761     // The load could be out-of-bounds. It must not be hoisted but must remain
 762     // dependent on the runtime range check. This is achieved by returning null.
 763   } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
 764     ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
 765 
 766     if (ac->is_arraycopy_validated() ||
 767         ac->is_copyof_validated() ||
 768         ac->is_copyofrange_validated()) {
 769       Node* ld_addp = in(MemNode::Address);
 770       if (ld_addp->is_AddP()) {
 771         Node* ld_base = ld_addp->in(AddPNode::Address);
 772         Node* ld_offs = ld_addp->in(AddPNode::Offset);
 773 
 774         Node* dest = ac->in(ArrayCopyNode::Dest);
 775 
 776         if (dest == ld_base) {
 777           const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 778           assert(!ld_offs_t->empty(), "dead reference should be checked already");
 779           // Take into account vector or unsafe access size
 780           jlong ld_size_in_bytes = (jlong)memory_size();
 781           jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
 782           offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
 783           if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
 784             return ac;
 785           }
 786           if (!can_see_stored_value) {
 787             mem = ac->in(TypeFunc::Memory);
 788             return ac;
 789           }
 790         }
 791       }
 792     }
 793   }
 794   return nullptr;
 795 }
 796 
 797 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
 798   if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
 799                                                mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
 800     if (ld_alloc != nullptr) {
 801       // Check if there is an array copy for a clone
 802       Node* mb = mem->in(0);
 803       ArrayCopyNode* ac = nullptr;
 804       if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
 805           mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
 806         ac = mb->in(0)->in(0)->as_ArrayCopy();
 807       } else {
 808         // Step over GC barrier when ReduceInitialCardMarks is disabled
 809         BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 810         Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
 811 
 812         if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
 813           ac = control_proj_ac->in(0)->as_ArrayCopy();
 814         }
 815       }
 816 
 817       if (ac != nullptr && ac->is_clonebasic()) {
 818         AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
 819         if (alloc != nullptr && alloc == ld_alloc) {
 820           return ac;
 821         }
 822       }
 823     }
 824   }
 825   return nullptr;
 826 }
 827 
 828 // The logic for reordering loads and stores uses four steps:
 829 // (a) Walk carefully past stores and initializations which we
 830 //     can prove are independent of this load.
 831 // (b) Observe that the next memory state makes an exact match
 832 //     with self (load or store), and locate the relevant store.
 833 // (c) Ensure that, if we were to wire self directly to the store,
 834 //     the optimizer would fold it up somehow.
 835 // (d) Do the rewiring, and return, depending on some other part of
 836 //     the optimizer to fold up the load.
 837 // This routine handles steps (a) and (b).  Steps (c) and (d) are
 838 // specific to loads and stores, so they are handled by the callers.
 839 // (Currently, only LoadNode::Ideal has steps (c), (d).  More later.)
 840 //
 841 Node* MemNode::find_previous_store(PhaseValues* phase) {
 842   Node*         ctrl   = in(MemNode::Control);
 843   Node*         adr    = in(MemNode::Address);
 844   intptr_t      offset = 0;
 845   Node*         base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
 846   AllocateNode* alloc  = AllocateNode::Ideal_allocation(base);
 847 
 848   if (offset == Type::OffsetBot)
 849     return nullptr;            // cannot unalias unless there are precise offsets
 850 
 851   const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
 852   const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
 853 
 854   intptr_t size_in_bytes = memory_size();
 855 
 856   Node* mem = in(MemNode::Memory);   // start searching here...
 857 
 858   int cnt = 50;             // Cycle limiter
 859   for (;;) {                // While we can dance past unrelated stores...
 860     if (--cnt < 0)  break;  // Caught in cycle or a complicated dance?
 861 
 862     Node* prev = mem;
 863     if (mem->is_Store()) {
 864       Node* st_adr = mem->in(MemNode::Address);
 865       intptr_t st_offset = 0;
 866       Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
 867       if (st_base == nullptr)
 868         break;              // inscrutable pointer
 869 
 870       // For raw accesses it's not enough to prove that constant offsets don't intersect.
 871       // We need the bases to be the equal in order for the offset check to make sense.
 872       if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
 873         break;
 874       }
 875 
 876       if (st_offset != offset && st_offset != Type::OffsetBot) {
 877         const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
 878         assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
 879         if (st_offset >= offset + size_in_bytes ||
 880             st_offset <= offset - MAX_STORE ||
 881             st_offset <= offset - mem->as_Store()->memory_size()) {
 882           // Success:  The offsets are provably independent.
 883           // (You may ask, why not just test st_offset != offset and be done?
 884           // The answer is that stores of different sizes can co-exist
 885           // in the same sequence of RawMem effects.  We sometimes initialize
 886           // a whole 'tile' of array elements with a single jint or jlong.)
 887           mem = mem->in(MemNode::Memory);
 888           continue;           // (a) advance through independent store memory
 889         }
 890       }
 891       if (st_base != base &&
 892           detect_ptr_independence(base, alloc,
 893                                   st_base,
 894                                   AllocateNode::Ideal_allocation(st_base),
 895                                   phase)) {
 896         // Success:  The bases are provably independent.
 897         mem = mem->in(MemNode::Memory);
 898         continue;           // (a) advance through independent store memory
 899       }
 900 
 901       // (b) At this point, if the bases or offsets do not agree, we lose,
 902       // since we have not managed to prove 'this' and 'mem' independent.
 903       if (st_base == base && st_offset == offset) {
 904         return mem;         // let caller handle steps (c), (d)
 905       }
 906 
 907     } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
 908       InitializeNode* st_init = mem->in(0)->as_Initialize();
 909       AllocateNode*  st_alloc = st_init->allocation();
 910       if (st_alloc == nullptr) {
 911         break;              // something degenerated
 912       }
 913       bool known_identical = false;
 914       bool known_independent = false;
 915       if (alloc == st_alloc) {
 916         known_identical = true;
 917       } else if (alloc != nullptr) {
 918         known_independent = true;
 919       } else if (all_controls_dominate(this, st_alloc)) {
 920         known_independent = true;
 921       }
 922 
 923       if (known_independent) {
 924         // The bases are provably independent: Either they are
 925         // manifestly distinct allocations, or else the control
 926         // of this load dominates the store's allocation.
 927         int alias_idx = phase->C->get_alias_index(adr_type());
 928         if (alias_idx == Compile::AliasIdxRaw) {
 929           mem = st_alloc->in(TypeFunc::Memory);
 930         } else {
 931           mem = st_init->memory(alias_idx);
 932         }
 933         continue;           // (a) advance through independent store memory
 934       }
 935 
 936       // (b) at this point, if we are not looking at a store initializing
 937       // the same allocation we are loading from, we lose.
 938       if (known_identical) {
 939         // From caller, can_see_stored_value will consult find_captured_store.
 940         return mem;         // let caller handle steps (c), (d)
 941       }
 942 
 943     } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
 944       if (prev != mem) {
 945         // Found an arraycopy but it doesn't affect that load
 946         continue;
 947       }
 948       // Found an arraycopy that may affect that load
 949       return mem;
 950     } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
 951       // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
 952       if (mem->is_Proj() && mem->in(0)->is_Call()) {
 953         // ArrayCopyNodes processed here as well.
 954         CallNode *call = mem->in(0)->as_Call();
 955         if (!call->may_modify(addr_t, phase)) {
 956           mem = call->in(TypeFunc::Memory);
 957           continue;         // (a) advance through independent call memory
 958         }
 959       } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
 960         ArrayCopyNode* ac = nullptr;
 961         if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
 962           break;
 963         }
 964         mem = mem->in(0)->in(TypeFunc::Memory);
 965         continue;           // (a) advance through independent MemBar memory
 966       } else if (mem->is_ClearArray()) {
 967         if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
 968           // (the call updated 'mem' value)
 969           continue;         // (a) advance through independent allocation memory
 970         } else {
 971           // Can not bypass initialization of the instance
 972           // we are looking for.
 973           return mem;
 974         }
 975       } else if (mem->is_MergeMem()) {
 976         int alias_idx = phase->C->get_alias_index(adr_type());
 977         mem = mem->as_MergeMem()->memory_at(alias_idx);
 978         continue;           // (a) advance through independent MergeMem memory
 979       }
 980     }
 981 
 982     // Unless there is an explicit 'continue', we must bail out here,
 983     // because 'mem' is an inscrutable memory state (e.g., a call).
 984     break;
 985   }
 986 
 987   return nullptr;              // bail out
 988 }
 989 
 990 //----------------------calculate_adr_type-------------------------------------
 991 // Helper function.  Notices when the given type of address hits top or bottom.
 992 // Also, asserts a cross-check of the type against the expected address type.
 993 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
 994   if (t == Type::TOP)  return nullptr; // does not touch memory any more?
 995   #ifdef ASSERT
 996   if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump())  cross_check = nullptr;
 997   #endif
 998   const TypePtr* tp = t->isa_ptr();
 999   if (tp == nullptr) {
1000     assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
1001     return TypePtr::BOTTOM;           // touches lots of memory
1002   } else {
1003     #ifdef ASSERT
1004     // %%%% [phh] We don't check the alias index if cross_check is
1005     //            TypeRawPtr::BOTTOM.  Needs to be investigated.
1006     if (cross_check != nullptr &&
1007         cross_check != TypePtr::BOTTOM &&
1008         cross_check != TypeRawPtr::BOTTOM) {
1009       // Recheck the alias index, to see if it has changed (due to a bug).
1010       Compile* C = Compile::current();
1011       assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
1012              "must stay in the original alias category");
1013       // The type of the address must be contained in the adr_type,
1014       // disregarding "null"-ness.
1015       // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
1016       const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
1017       assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
1018              "real address must not escape from expected memory type");
1019     }
1020     #endif
1021     return tp;
1022   }
1023 }
1024 
1025 uint8_t MemNode::barrier_data(const Node* n) {
1026   if (n->is_LoadStore()) {
1027     return n->as_LoadStore()->barrier_data();
1028   } else if (n->is_Mem()) {
1029     return n->as_Mem()->barrier_data();
1030   }
1031   return 0;
1032 }
1033 
1034 //=============================================================================
1035 // Should LoadNode::Ideal() attempt to remove control edges?
1036 bool LoadNode::can_remove_control() const {
1037   return !has_pinned_control_dependency();
1038 }
1039 uint LoadNode::size_of() const { return sizeof(*this); }
1040 bool LoadNode::cmp(const Node &n) const {
1041   LoadNode& load = (LoadNode &)n;
1042   return Type::equals(_type, load._type) &&
1043          _control_dependency == load._control_dependency &&
1044          _mo == load._mo;
1045 }
1046 const Type *LoadNode::bottom_type() const { return _type; }
1047 uint LoadNode::ideal_reg() const {
1048   return _type->ideal_reg();
1049 }
1050 
1051 #ifndef PRODUCT
1052 void LoadNode::dump_spec(outputStream *st) const {
1053   MemNode::dump_spec(st);
1054   if( !Verbose && !WizardMode ) {
1055     // standard dump does this in Verbose and WizardMode
1056     st->print(" #"); _type->dump_on(st);
1057   }
1058   if (!depends_only_on_test()) {
1059     st->print(" (does not depend only on test, ");
1060     if (control_dependency() == UnknownControl) {
1061       st->print("unknown control");
1062     } else if (control_dependency() == Pinned) {
1063       st->print("pinned");
1064     } else if (adr_type() == TypeRawPtr::BOTTOM) {
1065       st->print("raw access");
1066     } else {
1067       st->print("unknown reason");
1068     }
1069     st->print(")");
1070   }
1071 }
1072 #endif
1073 
1074 #ifdef ASSERT
1075 //----------------------------is_immutable_value-------------------------------
1076 // Helper function to allow a raw load without control edge for some cases
1077 bool LoadNode::is_immutable_value(Node* adr) {
1078   if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
1079       adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
1080 
1081     jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
1082     int offsets[] = {
1083       in_bytes(JavaThread::osthread_offset()),
1084       in_bytes(JavaThread::threadObj_offset()),
1085       in_bytes(JavaThread::vthread_offset()),
1086       in_bytes(JavaThread::scopedValueCache_offset()),
1087     };
1088 
1089     for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
1090       if (offset == offsets[i]) {
1091         return true;
1092       }
1093     }
1094   }
1095 
1096   return false;
1097 }
1098 #endif
1099 
1100 //----------------------------LoadNode::make-----------------------------------
1101 // Polymorphic factory method:
1102 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
1103                      ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
1104   Compile* C = gvn.C;
1105 
1106   // sanity check the alias category against the created node type
1107   assert(!(adr_type->isa_oopptr() &&
1108            adr_type->offset() == oopDesc::klass_offset_in_bytes()),
1109          "use LoadKlassNode instead");
1110   assert(!(adr_type->isa_aryptr() &&
1111            adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
1112          "use LoadRangeNode instead");
1113   // Check control edge of raw loads
1114   assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
1115           // oop will be recorded in oop map if load crosses safepoint
1116           rt->isa_oopptr() || is_immutable_value(adr),
1117           "raw memory operations should have control edge");
1118   LoadNode* load = nullptr;
1119   switch (bt) {
1120   case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
1121   case T_BYTE:    load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
1122   case T_INT:     load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
1123   case T_CHAR:    load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
1124   case T_SHORT:   load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
1125   case T_LONG:    load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
1126   case T_FLOAT:   load = new LoadFNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency); break;
1127   case T_DOUBLE:  load = new LoadDNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency, require_atomic_access); break;
1128   case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(),  mo, control_dependency); break;
1129   case T_OBJECT:
1130   case T_NARROWOOP:
1131 #ifdef _LP64
1132     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1133       load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
1134     } else
1135 #endif
1136     {
1137       assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
1138       load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
1139     }
1140     break;
1141   default:
1142     ShouldNotReachHere();
1143     break;
1144   }
1145   assert(load != nullptr, "LoadNode should have been created");
1146   if (unaligned) {
1147     load->set_unaligned_access();
1148   }
1149   if (mismatched) {
1150     load->set_mismatched_access();
1151   }
1152   if (unsafe) {
1153     load->set_unsafe_access();
1154   }
1155   load->set_barrier_data(barrier_data);
1156   if (load->Opcode() == Op_LoadN) {
1157     Node* ld = gvn.transform(load);
1158     return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1159   }
1160 
1161   return load;
1162 }
1163 
1164 //------------------------------hash-------------------------------------------
1165 uint LoadNode::hash() const {
1166   // unroll addition of interesting fields
1167   return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1168 }
1169 
1170 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1171   if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1172     bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1173     bool is_stable_ary = FoldStableValues &&
1174                          (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1175                          tp->isa_aryptr()->is_stable();
1176 
1177     return (eliminate_boxing && non_volatile) || is_stable_ary || tp->is_inlinetypeptr();
1178   }
1179 
1180   return false;
1181 }
1182 
1183 LoadNode* LoadNode::pin_array_access_node() const {
1184   const TypePtr* adr_type = this->adr_type();
1185   if (adr_type != nullptr && adr_type->isa_aryptr()) {
1186     return clone_pinned();
1187   }
1188   return nullptr;
1189 }
1190 
1191 // Is the value loaded previously stored by an arraycopy? If so return
1192 // a load node that reads from the source array so we may be able to
1193 // optimize out the ArrayCopy node later.
1194 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1195   Node* ld_adr = in(MemNode::Address);
1196   intptr_t ld_off = 0;
1197   AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1198   Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1199   if (ac != nullptr) {
1200     assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1201 
1202     Node* mem = ac->in(TypeFunc::Memory);
1203     Node* ctl = ac->in(0);
1204     Node* src = ac->in(ArrayCopyNode::Src);
1205 
1206     if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1207       return nullptr;
1208     }
1209 
1210     // load depends on the tests that validate the arraycopy
1211     LoadNode* ld = clone_pinned();
1212     Node* addp = in(MemNode::Address)->clone();
1213     if (ac->as_ArrayCopy()->is_clonebasic()) {
1214       assert(ld_alloc != nullptr, "need an alloc");
1215       assert(addp->is_AddP(), "address must be addp");
1216       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1217       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1218       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1219       addp->set_req(AddPNode::Base, src);
1220       addp->set_req(AddPNode::Address, src);
1221     } else {
1222       assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1223              ac->as_ArrayCopy()->is_copyof_validated() ||
1224              ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1225       assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1226       addp->set_req(AddPNode::Base, src);
1227       addp->set_req(AddPNode::Address, src);
1228 
1229       const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1230       BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1231       if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1232 
1233       uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1234       uint shift  = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem));
1235 
1236       Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1237 #ifdef _LP64
1238       diff = phase->transform(new ConvI2LNode(diff));
1239 #endif
1240       diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1241 
1242       Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1243       addp->set_req(AddPNode::Offset, offset);
1244     }
1245     addp = phase->transform(addp);
1246 #ifdef ASSERT
1247     const TypePtr* adr_type = phase->type(addp)->is_ptr();
1248     ld->_adr_type = adr_type;
1249 #endif
1250     ld->set_req(MemNode::Address, addp);
1251     ld->set_req(0, ctl);
1252     ld->set_req(MemNode::Memory, mem);
1253     return ld;
1254   }
1255   return nullptr;
1256 }
1257 
1258 static Node* see_through_inline_type(PhaseValues* phase, const MemNode* load, Node* base, int offset) {
1259   if (!load->is_mismatched_access() && base != nullptr && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) {
1260     InlineTypeNode* vt = base->as_InlineType();
1261     assert(!vt->is_larval(), "must not load from a larval object");
1262     Node* value = vt->field_value_by_offset(offset, true);
1263     assert(value != nullptr, "must see some value");
1264     return value;
1265   }
1266 
1267   return nullptr;
1268 }
1269 
1270 //---------------------------can_see_stored_value------------------------------
1271 // This routine exists to make sure this set of tests is done the same
1272 // everywhere.  We need to make a coordinated change: first LoadNode::Ideal
1273 // will change the graph shape in a way which makes memory alive twice at the
1274 // same time (uses the Oracle model of aliasing), then some
1275 // LoadXNode::Identity will fold things back to the equivalence-class model
1276 // of aliasing.
1277 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1278   Node* ld_adr = in(MemNode::Address);
1279   intptr_t ld_off = 0;
1280   Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1281   // Try to see through an InlineTypeNode
1282   // LoadN is special because the input is not compressed
1283   if (Opcode() != Op_LoadN) {
1284     Node* value = see_through_inline_type(phase, this, ld_base, ld_off);
1285     if (value != nullptr) {
1286       return value;
1287     }
1288   }
1289 
1290   Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1291   const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1292   Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1293   // This is more general than load from boxing objects.
1294   if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1295     uint alias_idx = atp->index();
1296     Node* result = nullptr;
1297     Node* current = st;
1298     // Skip through chains of MemBarNodes checking the MergeMems for
1299     // new states for the slice of this load.  Stop once any other
1300     // kind of node is encountered.  Loads from final memory can skip
1301     // through any kind of MemBar but normal loads shouldn't skip
1302     // through MemBarAcquire since the could allow them to move out of
1303     // a synchronized region. It is not safe to step over MemBarCPUOrder,
1304     // because alias info above them may be inaccurate (e.g., due to
1305     // mixed/mismatched unsafe accesses).
1306     bool is_final_mem = !atp->is_rewritable();
1307     while (current->is_Proj()) {
1308       int opc = current->in(0)->Opcode();
1309       if ((is_final_mem && (opc == Op_MemBarAcquire ||
1310                             opc == Op_MemBarAcquireLock ||
1311                             opc == Op_LoadFence)) ||
1312           opc == Op_MemBarRelease ||
1313           opc == Op_StoreFence ||
1314           opc == Op_MemBarReleaseLock ||
1315           opc == Op_MemBarStoreStore ||
1316           opc == Op_StoreStoreFence) {
1317         Node* mem = current->in(0)->in(TypeFunc::Memory);
1318         if (mem->is_MergeMem()) {
1319           MergeMemNode* merge = mem->as_MergeMem();
1320           Node* new_st = merge->memory_at(alias_idx);
1321           if (new_st == merge->base_memory()) {
1322             // Keep searching
1323             current = new_st;
1324             continue;
1325           }
1326           // Save the new memory state for the slice and fall through
1327           // to exit.
1328           result = new_st;
1329         }
1330       }
1331       break;
1332     }
1333     if (result != nullptr) {
1334       st = result;
1335     }
1336   }
1337 
1338   // Loop around twice in the case Load -> Initialize -> Store.
1339   // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1340   for (int trip = 0; trip <= 1; trip++) {
1341 
1342     if (st->is_Store()) {
1343       Node* st_adr = st->in(MemNode::Address);
1344       if (st_adr != ld_adr) {
1345         // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1346         intptr_t st_off = 0;
1347         Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1348         if (ld_base == nullptr)                                return nullptr;
1349         if (st_base == nullptr)                                return nullptr;
1350         if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1351         if (ld_off != st_off)                                  return nullptr;
1352         if (ld_off == Type::OffsetBot)                         return nullptr;
1353         // Same base, same offset.
1354         // Possible improvement for arrays: check index value instead of absolute offset.
1355 
1356         // At this point we have proven something like this setup:
1357         //   B = << base >>
1358         //   L =  LoadQ(AddP(Check/CastPP(B), #Off))
1359         //   S = StoreQ(AddP(             B , #Off), V)
1360         // (Actually, we haven't yet proven the Q's are the same.)
1361         // In other words, we are loading from a casted version of
1362         // the same pointer-and-offset that we stored to.
1363         // Casted version may carry a dependency and it is respected.
1364         // Thus, we are able to replace L by V.
1365       }
1366       // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1367       if (store_Opcode() != st->Opcode()) {
1368         return nullptr;
1369       }
1370       // LoadVector/StoreVector needs additional check to ensure the types match.
1371       if (st->is_StoreVector()) {
1372         const TypeVect*  in_vt = st->as_StoreVector()->vect_type();
1373         const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1374         if (in_vt != out_vt) {
1375           return nullptr;
1376         }
1377       }
1378       return st->in(MemNode::ValueIn);
1379     }
1380 
1381     // A load from a freshly-created object always returns zero.
1382     // (This can happen after LoadNode::Ideal resets the load's memory input
1383     // to find_captured_store, which returned InitializeNode::zero_memory.)
1384     if (st->is_Proj() && st->in(0)->is_Allocate() &&
1385         (st->in(0) == ld_alloc) &&
1386         (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1387       // return a zero value for the load's basic type
1388       // (This is one of the few places where a generic PhaseTransform
1389       // can create new nodes.  Think of it as lazily manifesting
1390       // virtually pre-existing constants.)
1391       Node* init_value = ld_alloc->in(AllocateNode::InitValue);
1392       if (init_value != nullptr) {
1393         // TODO 8350865 Is this correct for non-all-zero init values? Don't we need field_value_by_offset?
1394         return init_value;
1395       }
1396       assert(ld_alloc->in(AllocateNode::RawInitValue) == nullptr, "init value may not be null");
1397       if (memory_type() != T_VOID) {
1398         if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1399           // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1400           // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1401           // by the ArrayCopyNode.
1402           return phase->zerocon(memory_type());
1403         }
1404       } else {
1405         // TODO: materialize all-zero vector constant
1406         assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1407       }
1408     }
1409 
1410     // A load from an initialization barrier can match a captured store.
1411     if (st->is_Proj() && st->in(0)->is_Initialize()) {
1412       InitializeNode* init = st->in(0)->as_Initialize();
1413       AllocateNode* alloc = init->allocation();
1414       if ((alloc != nullptr) && (alloc == ld_alloc)) {
1415         // examine a captured store value
1416         st = init->find_captured_store(ld_off, memory_size(), phase);
1417         if (st != nullptr) {
1418           continue;             // take one more trip around
1419         }
1420       }
1421     }
1422 
1423     // Load boxed value from result of valueOf() call is input parameter.
1424     if (this->is_Load() && ld_adr->is_AddP() &&
1425         (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1426       intptr_t ignore = 0;
1427       Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1428       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1429       base = bs->step_over_gc_barrier(base);
1430       if (base != nullptr && base->is_Proj() &&
1431           base->as_Proj()->_con == TypeFunc::Parms &&
1432           base->in(0)->is_CallStaticJava() &&
1433           base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1434         return base->in(0)->in(TypeFunc::Parms);
1435       }
1436     }
1437 
1438     break;
1439   }
1440 
1441   return nullptr;
1442 }
1443 
1444 //----------------------is_instance_field_load_with_local_phi------------------
1445 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1446   if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1447       in(Address)->is_AddP() ) {
1448     const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1449     // Only instances and boxed values.
1450     if( t_oop != nullptr &&
1451         (t_oop->is_ptr_to_boxed_value() ||
1452          t_oop->is_known_instance_field()) &&
1453         t_oop->offset() != Type::OffsetBot &&
1454         t_oop->offset() != Type::OffsetTop) {
1455       return true;
1456     }
1457   }
1458   return false;
1459 }
1460 
1461 //------------------------------Identity---------------------------------------
1462 // Loads are identity if previous store is to same address
1463 Node* LoadNode::Identity(PhaseGVN* phase) {
1464   // If the previous store-maker is the right kind of Store, and the store is
1465   // to the same address, then we are equal to the value stored.
1466   Node* mem = in(Memory);
1467   Node* value = can_see_stored_value(mem, phase);
1468   if( value ) {
1469     // byte, short & char stores truncate naturally.
1470     // A load has to load the truncated value which requires
1471     // some sort of masking operation and that requires an
1472     // Ideal call instead of an Identity call.
1473     if (memory_size() < BytesPerInt) {
1474       // If the input to the store does not fit with the load's result type,
1475       // it must be truncated via an Ideal call.
1476       if (!phase->type(value)->higher_equal(phase->type(this)))
1477         return this;
1478     }
1479     // (This works even when value is a Con, but LoadNode::Value
1480     // usually runs first, producing the singleton type of the Con.)
1481     if (!has_pinned_control_dependency() || value->is_Con()) {
1482       return value;
1483     } else {
1484       return this;
1485     }
1486   }
1487 
1488   if (has_pinned_control_dependency()) {
1489     return this;
1490   }
1491   // Search for an existing data phi which was generated before for the same
1492   // instance's field to avoid infinite generation of phis in a loop.
1493   Node *region = mem->in(0);
1494   if (is_instance_field_load_with_local_phi(region)) {
1495     const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1496     int this_index  = phase->C->get_alias_index(addr_t);
1497     int this_offset = addr_t->offset();
1498     int this_iid    = addr_t->instance_id();
1499     if (!addr_t->is_known_instance() &&
1500          addr_t->is_ptr_to_boxed_value()) {
1501       // Use _idx of address base (could be Phi node) for boxed values.
1502       intptr_t   ignore = 0;
1503       Node*      base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1504       if (base == nullptr) {
1505         return this;
1506       }
1507       this_iid = base->_idx;
1508     }
1509     const Type* this_type = bottom_type();
1510     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1511       Node* phi = region->fast_out(i);
1512       if (phi->is_Phi() && phi != mem &&
1513           phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1514         return phi;
1515       }
1516     }
1517   }
1518 
1519   return this;
1520 }
1521 
1522 // Construct an equivalent unsigned load.
1523 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1524   BasicType bt = T_ILLEGAL;
1525   const Type* rt = nullptr;
1526   switch (Opcode()) {
1527     case Op_LoadUB: return this;
1528     case Op_LoadUS: return this;
1529     case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1530     case Op_LoadS: bt = T_CHAR;    rt = TypeInt::CHAR;  break;
1531     default:
1532       assert(false, "no unsigned variant: %s", Name());
1533       return nullptr;
1534   }
1535   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1536                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1537                         false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1538 }
1539 
1540 // Construct an equivalent signed load.
1541 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1542   BasicType bt = T_ILLEGAL;
1543   const Type* rt = nullptr;
1544   switch (Opcode()) {
1545     case Op_LoadUB: bt = T_BYTE;  rt = TypeInt::BYTE;  break;
1546     case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1547     case Op_LoadB: // fall through
1548     case Op_LoadS: // fall through
1549     case Op_LoadI: // fall through
1550     case Op_LoadL: return this;
1551     default:
1552       assert(false, "no signed variant: %s", Name());
1553       return nullptr;
1554   }
1555   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1556                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1557                         false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1558 }
1559 
1560 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1561   BasicType bt = rt->basic_type();
1562   switch (Opcode()) {
1563     case Op_LoadI: return (bt == T_FLOAT);
1564     case Op_LoadL: return (bt == T_DOUBLE);
1565     case Op_LoadF: return (bt == T_INT);
1566     case Op_LoadD: return (bt == T_LONG);
1567 
1568     default: return false;
1569   }
1570 }
1571 
1572 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1573   BasicType bt = rt->basic_type();
1574   assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1575   bool is_mismatched = is_mismatched_access();
1576   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1577   if (raw_type == nullptr) {
1578     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1579   }
1580   const int op = Opcode();
1581   bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1582                                (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1583   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1584                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1585                         require_atomic_access, is_unaligned_access(), is_mismatched);
1586 }
1587 
1588 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1589   BasicType bt = vt->basic_type();
1590   switch (Opcode()) {
1591     case Op_StoreI: return (bt == T_FLOAT);
1592     case Op_StoreL: return (bt == T_DOUBLE);
1593     case Op_StoreF: return (bt == T_INT);
1594     case Op_StoreD: return (bt == T_LONG);
1595 
1596     default: return false;
1597   }
1598 }
1599 
1600 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1601   BasicType bt = vt->basic_type();
1602   assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1603   const int op = Opcode();
1604   bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1605                                (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1606   StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1607                                   raw_adr_type(), val, bt, _mo, require_atomic_access);
1608 
1609   bool is_mismatched = is_mismatched_access();
1610   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1611   if (raw_type == nullptr) {
1612     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1613   }
1614   if (is_mismatched) {
1615     st->set_mismatched_access();
1616   }
1617   return st;
1618 }
1619 
1620 // We're loading from an object which has autobox behaviour.
1621 // If this object is result of a valueOf call we'll have a phi
1622 // merging a newly allocated object and a load from the cache.
1623 // We want to replace this load with the original incoming
1624 // argument to the valueOf call.
1625 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1626   assert(igvn->C->eliminate_boxing(), "sanity");
1627   intptr_t ignore = 0;
1628   Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1629   if ((base == nullptr) || base->is_Phi()) {
1630     // Push the loads from the phi that comes from valueOf up
1631     // through it to allow elimination of the loads and the recovery
1632     // of the original value. It is done in split_through_phi().
1633     return nullptr;
1634   } else if (base->is_Load() ||
1635              (base->is_DecodeN() && base->in(1)->is_Load())) {
1636     // Eliminate the load of boxed value for integer types from the cache
1637     // array by deriving the value from the index into the array.
1638     // Capture the offset of the load and then reverse the computation.
1639 
1640     // Get LoadN node which loads a boxing object from 'cache' array.
1641     if (base->is_DecodeN()) {
1642       base = base->in(1);
1643     }
1644     if (!base->in(Address)->is_AddP()) {
1645       return nullptr; // Complex address
1646     }
1647     AddPNode* address = base->in(Address)->as_AddP();
1648     Node* cache_base = address->in(AddPNode::Base);
1649     if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1650       // Get ConP node which is static 'cache' field.
1651       cache_base = cache_base->in(1);
1652     }
1653     if ((cache_base != nullptr) && cache_base->is_Con()) {
1654       const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1655       if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1656         Node* elements[4];
1657         int shift = exact_log2(type2aelembytes(T_OBJECT));
1658         int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1659         if (count > 0 && elements[0]->is_Con() &&
1660             (count == 1 ||
1661              (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1662                             elements[1]->in(2) == igvn->intcon(shift)))) {
1663           ciObjArray* array = base_type->const_oop()->as_obj_array();
1664           // Fetch the box object cache[0] at the base of the array and get its value
1665           ciInstance* box = array->obj_at(0)->as_instance();
1666           ciInstanceKlass* ik = box->klass()->as_instance_klass();
1667           assert(ik->is_box_klass(), "sanity");
1668           assert(ik->nof_nonstatic_fields() == 1, "change following code");
1669           if (ik->nof_nonstatic_fields() == 1) {
1670             // This should be true nonstatic_field_at requires calling
1671             // nof_nonstatic_fields so check it anyway
1672             ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1673             BasicType bt = c.basic_type();
1674             // Only integer types have boxing cache.
1675             assert(bt == T_BOOLEAN || bt == T_CHAR  ||
1676                    bt == T_BYTE    || bt == T_SHORT ||
1677                    bt == T_INT     || bt == T_LONG, "wrong type = %s", type2name(bt));
1678             jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1679             if (cache_low != (int)cache_low) {
1680               return nullptr; // should not happen since cache is array indexed by value
1681             }
1682             jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1683             if (offset != (int)offset) {
1684               return nullptr; // should not happen since cache is array indexed by value
1685             }
1686            // Add up all the offsets making of the address of the load
1687             Node* result = elements[0];
1688             for (int i = 1; i < count; i++) {
1689               result = igvn->transform(new AddXNode(result, elements[i]));
1690             }
1691             // Remove the constant offset from the address and then
1692             result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1693             // remove the scaling of the offset to recover the original index.
1694             if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1695               // Peel the shift off directly but wrap it in a dummy node
1696               // since Ideal can't return existing nodes
1697               igvn->_worklist.push(result); // remove dead node later
1698               result = new RShiftXNode(result->in(1), igvn->intcon(0));
1699             } else if (result->is_Add() && result->in(2)->is_Con() &&
1700                        result->in(1)->Opcode() == Op_LShiftX &&
1701                        result->in(1)->in(2) == igvn->intcon(shift)) {
1702               // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1703               // but for boxing cache access we know that X<<Z will not overflow
1704               // (there is range check) so we do this optimizatrion by hand here.
1705               igvn->_worklist.push(result); // remove dead node later
1706               Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1707               result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1708             } else {
1709               result = new RShiftXNode(result, igvn->intcon(shift));
1710             }
1711 #ifdef _LP64
1712             if (bt != T_LONG) {
1713               result = new ConvL2INode(igvn->transform(result));
1714             }
1715 #else
1716             if (bt == T_LONG) {
1717               result = new ConvI2LNode(igvn->transform(result));
1718             }
1719 #endif
1720             // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1721             // Need to preserve unboxing load type if it is unsigned.
1722             switch(this->Opcode()) {
1723               case Op_LoadUB:
1724                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1725                 break;
1726               case Op_LoadUS:
1727                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1728                 break;
1729             }
1730             return result;
1731           }
1732         }
1733       }
1734     }
1735   }
1736   return nullptr;
1737 }
1738 
1739 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1740   Node* region = phi->in(0);
1741   if (region == nullptr) {
1742     return false; // Wait stable graph
1743   }
1744   uint cnt = phi->req();
1745   for (uint i = 1; i < cnt; i++) {
1746     Node* rc = region->in(i);
1747     if (rc == nullptr || phase->type(rc) == Type::TOP)
1748       return false; // Wait stable graph
1749     Node* in = phi->in(i);
1750     if (in == nullptr || phase->type(in) == Type::TOP)
1751       return false; // Wait stable graph
1752   }
1753   return true;
1754 }
1755 
1756 //------------------------------split_through_phi------------------------------
1757 // Check whether a call to 'split_through_phi' would split this load through the
1758 // Phi *base*. This method is essentially a copy of the validations performed
1759 // by 'split_through_phi'. The first use of this method was in EA code as part
1760 // of simplification of allocation merges.
1761 // Some differences from original method (split_through_phi):
1762 //  - If base->is_CastPP(): base = base->in(1)
1763 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1764   Node* mem        = in(Memory);
1765   Node* address    = in(Address);
1766   intptr_t ignore  = 0;
1767   Node*    base    = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1768 
1769   if (base->is_CastPP()) {
1770     base = base->in(1);
1771   }
1772 
1773   if (req() > 3 || base == nullptr || !base->is_Phi()) {
1774     return false;
1775   }
1776 
1777   if (!mem->is_Phi()) {
1778     if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1779       return false;
1780     }
1781   } else if (base->in(0) != mem->in(0)) {
1782     if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1783       return false;
1784     }
1785   }
1786 
1787   return true;
1788 }
1789 
1790 //------------------------------split_through_phi------------------------------
1791 // Split instance or boxed field load through Phi.
1792 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1793   if (req() > 3) {
1794     assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1795     // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1796     return nullptr;
1797   }
1798   Node* mem     = in(Memory);
1799   Node* address = in(Address);
1800   const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1801 
1802   assert((t_oop != nullptr) &&
1803          (ignore_missing_instance_id ||
1804           t_oop->is_known_instance_field() ||
1805           t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1806 
1807   Compile* C = phase->C;
1808   intptr_t ignore = 0;
1809   Node*    base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1810   bool base_is_phi = (base != nullptr) && base->is_Phi();
1811   bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1812                            (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1813                            phase->type(base)->higher_equal(TypePtr::NOTNULL);
1814 
1815   if (!((mem->is_Phi() || base_is_phi) &&
1816         (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1817     return nullptr; // Neither memory or base are Phi
1818   }
1819 
1820   if (mem->is_Phi()) {
1821     if (!stable_phi(mem->as_Phi(), phase)) {
1822       return nullptr; // Wait stable graph
1823     }
1824     uint cnt = mem->req();
1825     // Check for loop invariant memory.
1826     if (cnt == 3) {
1827       for (uint i = 1; i < cnt; i++) {
1828         Node* in = mem->in(i);
1829         Node*  m = optimize_memory_chain(in, t_oop, this, phase);
1830         if (m == mem) {
1831           if (i == 1) {
1832             // if the first edge was a loop, check second edge too.
1833             // If both are replaceable - we are in an infinite loop
1834             Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1835             if (n == mem) {
1836               break;
1837             }
1838           }
1839           set_req(Memory, mem->in(cnt - i));
1840           return this; // made change
1841         }
1842       }
1843     }
1844   }
1845   if (base_is_phi) {
1846     if (!stable_phi(base->as_Phi(), phase)) {
1847       return nullptr; // Wait stable graph
1848     }
1849     uint cnt = base->req();
1850     // Check for loop invariant memory.
1851     if (cnt == 3) {
1852       for (uint i = 1; i < cnt; i++) {
1853         if (base->in(i) == base) {
1854           return nullptr; // Wait stable graph
1855         }
1856       }
1857     }
1858   }
1859 
1860   // Split through Phi (see original code in loopopts.cpp).
1861   assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1862 
1863   // Do nothing here if Identity will find a value
1864   // (to avoid infinite chain of value phis generation).
1865   if (this != Identity(phase)) {
1866     return nullptr;
1867   }
1868 
1869   // Select Region to split through.
1870   Node* region;
1871   DomResult dom_result = DomResult::Dominate;
1872   if (!base_is_phi) {
1873     assert(mem->is_Phi(), "sanity");
1874     region = mem->in(0);
1875     // Skip if the region dominates some control edge of the address.
1876     // We will check `dom_result` later.
1877     dom_result = MemNode::maybe_all_controls_dominate(address, region);
1878   } else if (!mem->is_Phi()) {
1879     assert(base_is_phi, "sanity");
1880     region = base->in(0);
1881     // Skip if the region dominates some control edge of the memory.
1882     // We will check `dom_result` later.
1883     dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1884   } else if (base->in(0) != mem->in(0)) {
1885     assert(base_is_phi && mem->is_Phi(), "sanity");
1886     dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1887     if (dom_result == DomResult::Dominate) {
1888       region = base->in(0);
1889     } else {
1890       dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1891       if (dom_result == DomResult::Dominate) {
1892         region = mem->in(0);
1893       }
1894       // Otherwise we encountered a complex graph.
1895     }
1896   } else {
1897     assert(base->in(0) == mem->in(0), "sanity");
1898     region = mem->in(0);
1899   }
1900 
1901   PhaseIterGVN* igvn = phase->is_IterGVN();
1902   if (dom_result != DomResult::Dominate) {
1903     if (dom_result == DomResult::EncounteredDeadCode) {
1904       // There is some dead code which eventually will be removed in IGVN.
1905       // Once this is the case, we get an unambiguous dominance result.
1906       // Push the node to the worklist again until the dead code is removed.
1907       igvn->_worklist.push(this);
1908     }
1909     return nullptr;
1910   }
1911 
1912   Node* phi = nullptr;
1913   const Type* this_type = this->bottom_type();
1914   if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1915     int this_index = C->get_alias_index(t_oop);
1916     int this_offset = t_oop->offset();
1917     int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1918     phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1919   } else if (ignore_missing_instance_id) {
1920     phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1921   } else {
1922     return nullptr;
1923   }
1924 
1925   for (uint i = 1; i < region->req(); i++) {
1926     Node* x;
1927     Node* the_clone = nullptr;
1928     Node* in = region->in(i);
1929     if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1930         in != nullptr && in->is_OuterStripMinedLoop()) {
1931       // No node should go in the outer strip mined loop
1932       in = in->in(LoopNode::EntryControl);
1933     }
1934     if (in == nullptr || in == C->top()) {
1935       x = C->top();      // Dead path?  Use a dead data op
1936     } else {
1937       x = this->clone();        // Else clone up the data op
1938       the_clone = x;            // Remember for possible deletion.
1939       // Alter data node to use pre-phi inputs
1940       if (this->in(0) == region) {
1941         x->set_req(0, in);
1942       } else {
1943         x->set_req(0, nullptr);
1944       }
1945       if (mem->is_Phi() && (mem->in(0) == region)) {
1946         x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1947       }
1948       if (address->is_Phi() && address->in(0) == region) {
1949         x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1950       }
1951       if (base_is_phi && (base->in(0) == region)) {
1952         Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1953         Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1954         x->set_req(Address, adr_x);
1955       }
1956     }
1957     // Check for a 'win' on some paths
1958     const Type *t = x->Value(igvn);
1959 
1960     bool singleton = t->singleton();
1961 
1962     // See comments in PhaseIdealLoop::split_thru_phi().
1963     if (singleton && t == Type::TOP) {
1964       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1965     }
1966 
1967     if (singleton) {
1968       x = igvn->makecon(t);
1969     } else {
1970       // We now call Identity to try to simplify the cloned node.
1971       // Note that some Identity methods call phase->type(this).
1972       // Make sure that the type array is big enough for
1973       // our new node, even though we may throw the node away.
1974       // (This tweaking with igvn only works because x is a new node.)
1975       igvn->set_type(x, t);
1976       // If x is a TypeNode, capture any more-precise type permanently into Node
1977       // otherwise it will be not updated during igvn->transform since
1978       // igvn->type(x) is set to x->Value() already.
1979       x->raise_bottom_type(t);
1980       Node* y = x->Identity(igvn);
1981       if (y != x) {
1982         x = y;
1983       } else {
1984         y = igvn->hash_find_insert(x);
1985         if (y) {
1986           x = y;
1987         } else {
1988           // Else x is a new node we are keeping
1989           // We do not need register_new_node_with_optimizer
1990           // because set_type has already been called.
1991           igvn->_worklist.push(x);
1992         }
1993       }
1994     }
1995     if (x != the_clone && the_clone != nullptr) {
1996       igvn->remove_dead_node(the_clone);
1997     }
1998     phi->set_req(i, x);
1999   }
2000   // Record Phi
2001   igvn->register_new_node_with_optimizer(phi);
2002   return phi;
2003 }
2004 
2005 AllocateNode* LoadNode::is_new_object_mark_load() const {
2006   if (Opcode() == Op_LoadX) {
2007     Node* address = in(MemNode::Address);
2008     AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
2009     Node* mem = in(MemNode::Memory);
2010     if (alloc != nullptr && mem->is_Proj() &&
2011         mem->in(0) != nullptr &&
2012         mem->in(0) == alloc->initialization() &&
2013         alloc->initialization()->proj_out_or_null(0) != nullptr) {
2014       return alloc;
2015     }
2016   }
2017   return nullptr;
2018 }
2019 
2020 
2021 //------------------------------Ideal------------------------------------------
2022 // If the load is from Field memory and the pointer is non-null, it might be possible to
2023 // zero out the control input.
2024 // If the offset is constant and the base is an object allocation,
2025 // try to hook me up to the exact initializing store.
2026 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2027   if (has_pinned_control_dependency()) {
2028     return nullptr;
2029   }
2030   Node* p = MemNode::Ideal_common(phase, can_reshape);
2031   if (p)  return (p == NodeSentinel) ? nullptr : p;
2032 
2033   Node* ctrl    = in(MemNode::Control);
2034   Node* address = in(MemNode::Address);
2035   bool progress = false;
2036 
2037   bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
2038          phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
2039 
2040   // Skip up past a SafePoint control.  Cannot do this for Stores because
2041   // pointer stores & cardmarks must stay on the same side of a SafePoint.
2042   if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
2043       phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw  &&
2044       !addr_mark &&
2045       (depends_only_on_test() || has_unknown_control_dependency())) {
2046     ctrl = ctrl->in(0);
2047     set_req(MemNode::Control,ctrl);
2048     progress = true;
2049   }
2050 
2051   intptr_t ignore = 0;
2052   Node*    base   = AddPNode::Ideal_base_and_offset(address, phase, ignore);
2053   if (base != nullptr
2054       && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
2055     // Check for useless control edge in some common special cases
2056     if (in(MemNode::Control) != nullptr
2057         && !(phase->type(address)->is_inlinetypeptr() && is_mismatched_access())
2058         && can_remove_control()
2059         && phase->type(base)->higher_equal(TypePtr::NOTNULL)
2060         && all_controls_dominate(base, phase->C->start())) {
2061       // A method-invariant, non-null address (constant or 'this' argument).
2062       set_req(MemNode::Control, nullptr);
2063       progress = true;
2064     }
2065   }
2066 
2067   Node* mem = in(MemNode::Memory);
2068   const TypePtr *addr_t = phase->type(address)->isa_ptr();
2069 
2070   if (can_reshape && (addr_t != nullptr)) {
2071     // try to optimize our memory input
2072     Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
2073     if (opt_mem != mem) {
2074       set_req_X(MemNode::Memory, opt_mem, phase);
2075       if (phase->type( opt_mem ) == Type::TOP) return nullptr;
2076       return this;
2077     }
2078     const TypeOopPtr *t_oop = addr_t->isa_oopptr();
2079     if ((t_oop != nullptr) &&
2080         (t_oop->is_known_instance_field() ||
2081          t_oop->is_ptr_to_boxed_value())) {
2082       PhaseIterGVN *igvn = phase->is_IterGVN();
2083       assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
2084       if (igvn->_worklist.member(opt_mem)) {
2085         // Delay this transformation until memory Phi is processed.
2086         igvn->_worklist.push(this);
2087         return nullptr;
2088       }
2089       // Split instance field load through Phi.
2090       Node* result = split_through_phi(phase);
2091       if (result != nullptr) return result;
2092 
2093       if (t_oop->is_ptr_to_boxed_value()) {
2094         Node* result = eliminate_autobox(igvn);
2095         if (result != nullptr) return result;
2096       }
2097     }
2098   }
2099 
2100   // Is there a dominating load that loads the same value?  Leave
2101   // anything that is not a load of a field/array element (like
2102   // barriers etc.) alone
2103   if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
2104     for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
2105       Node *use = mem->fast_out(i);
2106       if (use != this &&
2107           use->Opcode() == Opcode() &&
2108           use->in(0) != nullptr &&
2109           use->in(0) != in(0) &&
2110           use->in(Address) == in(Address)) {
2111         Node* ctl = in(0);
2112         for (int i = 0; i < 10 && ctl != nullptr; i++) {
2113           ctl = IfNode::up_one_dom(ctl);
2114           if (ctl == use->in(0)) {
2115             set_req(0, use->in(0));
2116             return this;
2117           }
2118         }
2119       }
2120     }
2121   }
2122 
2123   // Check for prior store with a different base or offset; make Load
2124   // independent.  Skip through any number of them.  Bail out if the stores
2125   // are in an endless dead cycle and report no progress.  This is a key
2126   // transform for Reflection.  However, if after skipping through the Stores
2127   // we can't then fold up against a prior store do NOT do the transform as
2128   // this amounts to using the 'Oracle' model of aliasing.  It leaves the same
2129   // array memory alive twice: once for the hoisted Load and again after the
2130   // bypassed Store.  This situation only works if EVERYBODY who does
2131   // anti-dependence work knows how to bypass.  I.e. we need all
2132   // anti-dependence checks to ask the same Oracle.  Right now, that Oracle is
2133   // the alias index stuff.  So instead, peek through Stores and IFF we can
2134   // fold up, do so.
2135   Node* prev_mem = find_previous_store(phase);
2136   if (prev_mem != nullptr) {
2137     Node* value = can_see_arraycopy_value(prev_mem, phase);
2138     if (value != nullptr) {
2139       return value;
2140     }
2141   }
2142   // Steps (a), (b):  Walk past independent stores to find an exact match.
2143   if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
2144     // (c) See if we can fold up on the spot, but don't fold up here.
2145     // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
2146     // just return a prior value, which is done by Identity calls.
2147     if (can_see_stored_value(prev_mem, phase)) {
2148       // Make ready for step (d):
2149       set_req_X(MemNode::Memory, prev_mem, phase);
2150       return this;
2151     }
2152   }
2153 
2154   if (progress) {
2155     return this;
2156   }
2157 
2158   if (!can_reshape) {
2159     phase->record_for_igvn(this);
2160   }
2161   return nullptr;
2162 }
2163 
2164 // Helper to recognize certain Klass fields which are invariant across
2165 // some group of array types (e.g., int[] or all T[] where T < Object).
2166 const Type*
2167 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
2168                                  ciKlass* klass) const {
2169   assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
2170          "must not happen");
2171   if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
2172     // The field is Klass::_access_flags.  Return its (constant) value.
2173     // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
2174     assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
2175     return TypeInt::make(klass->access_flags());
2176   }
2177   if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
2178     // The field is Klass::_misc_flags.  Return its (constant) value.
2179     // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
2180     assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
2181     return TypeInt::make(klass->misc_flags());
2182   }
2183   if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
2184     // The field is Klass::_layout_helper.  Return its constant value if known.
2185     assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2186     return TypeInt::make(klass->layout_helper());
2187   }
2188 
2189   // No match.
2190   return nullptr;
2191 }
2192 
2193 //------------------------------Value-----------------------------------------
2194 const Type* LoadNode::Value(PhaseGVN* phase) const {
2195   // Either input is TOP ==> the result is TOP
2196   Node* mem = in(MemNode::Memory);
2197   const Type *t1 = phase->type(mem);
2198   if (t1 == Type::TOP)  return Type::TOP;
2199   Node* adr = in(MemNode::Address);
2200   const TypePtr* tp = phase->type(adr)->isa_ptr();
2201   if (tp == nullptr || tp->empty())  return Type::TOP;
2202   int off = tp->offset();
2203   assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2204   Compile* C = phase->C;
2205 
2206   // If we are loading from a freshly-allocated object, produce a zero,
2207   // if the load is provably beyond the header of the object.
2208   // (Also allow a variable load from a fresh array to produce zero.)
2209   const TypeOopPtr* tinst = tp->isa_oopptr();
2210   bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2211   Node* value = can_see_stored_value(mem, phase);
2212   if (value != nullptr && value->is_Con()) {
2213     assert(value->bottom_type()->higher_equal(_type), "sanity");
2214     return value->bottom_type();
2215   }
2216 
2217   // Try to guess loaded type from pointer type
2218   if (tp->isa_aryptr()) {
2219     const TypeAryPtr* ary = tp->is_aryptr();
2220     const Type* t = ary->elem();
2221 
2222     // Determine whether the reference is beyond the header or not, by comparing
2223     // the offset against the offset of the start of the array's data.
2224     // Different array types begin at slightly different offsets (12 vs. 16).
2225     // We choose T_BYTE as an example base type that is least restrictive
2226     // as to alignment, which will therefore produce the smallest
2227     // possible base offset.
2228     const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2229     const bool off_beyond_header = (off >= min_base_off);
2230 
2231     // Try to constant-fold a stable array element.
2232     if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2233       // Make sure the reference is not into the header and the offset is constant
2234       ciObject* aobj = ary->const_oop();
2235       if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2236         int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2237         const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2238                                                                       stable_dimension,
2239                                                                       memory_type(), is_unsigned());
2240         if (con_type != nullptr) {
2241           return con_type;
2242         }
2243       }
2244     }
2245 
2246     // Don't do this for integer types. There is only potential profit if
2247     // the element type t is lower than _type; that is, for int types, if _type is
2248     // more restrictive than t.  This only happens here if one is short and the other
2249     // char (both 16 bits), and in those cases we've made an intentional decision
2250     // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2251     // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2252     //
2253     // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2254     // where the _gvn.type of the AddP is wider than 8.  This occurs when an earlier
2255     // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2256     // subsumed by p1.  If p1 is on the worklist but has not yet been re-transformed,
2257     // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2258     // In fact, that could have been the original type of p1, and p1 could have
2259     // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2260     // expression (LShiftL quux 3) independently optimized to the constant 8.
2261     if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2262         && (_type->isa_vect() == nullptr)
2263         && !ary->is_flat()
2264         && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2265       // t might actually be lower than _type, if _type is a unique
2266       // concrete subclass of abstract class t.
2267       if (off_beyond_header || off == Type::OffsetBot) {  // is the offset beyond the header?
2268         const Type* jt = t->join_speculative(_type);
2269         // In any case, do not allow the join, per se, to empty out the type.
2270         if (jt->empty() && !t->empty()) {
2271           // This can happen if a interface-typed array narrows to a class type.
2272           jt = _type;
2273         }
2274 #ifdef ASSERT
2275         if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2276           // The pointers in the autobox arrays are always non-null
2277           Node* base = adr->in(AddPNode::Base);
2278           if ((base != nullptr) && base->is_DecodeN()) {
2279             // Get LoadN node which loads IntegerCache.cache field
2280             base = base->in(1);
2281           }
2282           if ((base != nullptr) && base->is_Con()) {
2283             const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2284             if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2285               // It could be narrow oop
2286               assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2287             }
2288           }
2289         }
2290 #endif
2291         return jt;
2292       }
2293     }
2294   } else if (tp->base() == Type::InstPtr) {
2295     assert( off != Type::OffsetBot ||
2296             // arrays can be cast to Objects
2297             !tp->isa_instptr() ||
2298             tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2299             // Default value load
2300             tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() ||
2301             // unsafe field access may not have a constant offset
2302             C->has_unsafe_access(),
2303             "Field accesses must be precise" );
2304     // For oop loads, we expect the _type to be precise.
2305 
2306     const TypeInstPtr* tinst = tp->is_instptr();
2307     BasicType bt = memory_type();
2308 
2309     // Optimize loads from constant fields.
2310     ciObject* const_oop = tinst->const_oop();
2311     if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2312       const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2313       if (con_type != nullptr) {
2314         return con_type;
2315       }
2316     }
2317   } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2318     assert(off != Type::OffsetBot ||
2319             !tp->isa_instklassptr() ||
2320            // arrays can be cast to Objects
2321            tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2322            // also allow array-loading from the primary supertype
2323            // array during subtype checks
2324            Opcode() == Op_LoadKlass,
2325            "Field accesses must be precise");
2326     // For klass/static loads, we expect the _type to be precise
2327   } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2328     /* With mirrors being an indirect in the Klass*
2329      * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2330      * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2331      *
2332      * So check the type and klass of the node before the LoadP.
2333      */
2334     Node* adr2 = adr->in(MemNode::Address);
2335     const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2336     if (tkls != nullptr && !StressReflectiveCode) {
2337       if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2338         ciKlass* klass = tkls->exact_klass();
2339         assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2340         assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2341         return TypeInstPtr::make(klass->java_mirror());
2342       }
2343     }
2344   }
2345 
2346   const TypeKlassPtr *tkls = tp->isa_klassptr();
2347   if (tkls != nullptr) {
2348     if (tkls->is_loaded() && tkls->klass_is_exact()) {
2349       ciKlass* klass = tkls->exact_klass();
2350       // We are loading a field from a Klass metaobject whose identity
2351       // is known at compile time (the type is "exact" or "precise").
2352       // Check for fields we know are maintained as constants by the VM.
2353       if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2354         // The field is Klass::_super_check_offset.  Return its (constant) value.
2355         // (Folds up type checking code.)
2356         assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2357         return TypeInt::make(klass->super_check_offset());
2358       }
2359       if (UseCompactObjectHeaders) { // TODO: Should EnableValhalla also take this path ?
2360         if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2361           // The field is Klass::_prototype_header. Return its (constant) value.
2362           assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2363           return TypeX::make(klass->prototype_header());
2364         }
2365       }
2366       // Compute index into primary_supers array
2367       juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2368       // Check for overflowing; use unsigned compare to handle the negative case.
2369       if( depth < ciKlass::primary_super_limit() ) {
2370         // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2371         // (Folds up type checking code.)
2372         assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2373         ciKlass *ss = klass->super_of_depth(depth);
2374         return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2375       }
2376       const Type* aift = load_array_final_field(tkls, klass);
2377       if (aift != nullptr)  return aift;
2378     }
2379 
2380     // We can still check if we are loading from the primary_supers array at a
2381     // shallow enough depth.  Even though the klass is not exact, entries less
2382     // than or equal to its super depth are correct.
2383     if (tkls->is_loaded()) {
2384       ciKlass* klass = nullptr;
2385       if (tkls->isa_instklassptr()) {
2386         klass = tkls->is_instklassptr()->instance_klass();
2387       } else {
2388         int dims;
2389         const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2390         if (inner->isa_instklassptr()) {
2391           klass = inner->is_instklassptr()->instance_klass();
2392           klass = ciObjArrayKlass::make(klass, dims);
2393         }
2394       }
2395       if (klass != nullptr) {
2396         // Compute index into primary_supers array
2397         juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2398         // Check for overflowing; use unsigned compare to handle the negative case.
2399         if (depth < ciKlass::primary_super_limit() &&
2400             depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2401           // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2402           // (Folds up type checking code.)
2403           assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2404           ciKlass *ss = klass->super_of_depth(depth);
2405           return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2406         }
2407       }
2408     }
2409 
2410     // If the type is enough to determine that the thing is not an array,
2411     // we can give the layout_helper a positive interval type.
2412     // This will help short-circuit some reflective code.
2413     if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2414         tkls->isa_instklassptr() && // not directly typed as an array
2415         !tkls->is_instklassptr()->instance_klass()->is_java_lang_Object() // not the supertype of all T[] and specifically not Serializable & Cloneable
2416         ) {
2417       // Note:  When interfaces are reliable, we can narrow the interface
2418       // test to (klass != Serializable && klass != Cloneable).
2419       assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2420       jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2421       // The key property of this type is that it folds up tests
2422       // for array-ness, since it proves that the layout_helper is positive.
2423       // Thus, a generic value like the basic object layout helper works fine.
2424       return TypeInt::make(min_size, max_jint, Type::WidenMin);
2425     }
2426   }
2427 
2428   bool is_vect = (_type->isa_vect() != nullptr);
2429   if (is_instance && !is_vect) {
2430     // If we have an instance type and our memory input is the
2431     // programs's initial memory state, there is no matching store,
2432     // so just return a zero of the appropriate type -
2433     // except if it is vectorized - then we have no zero constant.
2434     Node *mem = in(MemNode::Memory);
2435     if (mem->is_Parm() && mem->in(0)->is_Start()) {
2436       assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2437       // TODO 8350865 This is needed for flat array accesses, somehow the memory of the loads bypasses the intrinsic
2438       // Run TestArrays.test6 in Scenario4, we need more tests for this. TestBasicFunctionality::test20 also needs this.
2439       if (tp->isa_aryptr() && tp->is_aryptr()->is_flat() && !UseFieldFlattening) {
2440         return _type;
2441       }
2442       return Type::get_zero_type(_type->basic_type());
2443     }
2444   }
2445   if (!UseCompactObjectHeaders) {
2446     Node* alloc = is_new_object_mark_load();
2447     if (alloc != nullptr) {
2448       if (EnableValhalla) {
2449         // The mark word may contain property bits (inline, flat, null-free)
2450         Node* klass_node = alloc->in(AllocateNode::KlassNode);
2451         const TypeKlassPtr* tkls = phase->type(klass_node)->isa_klassptr();
2452         if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact()) {
2453           return TypeX::make(tkls->exact_klass()->prototype_header());
2454         }
2455       } else {
2456         return TypeX::make(markWord::prototype().value());
2457       }
2458     }
2459   }
2460 
2461   return _type;
2462 }
2463 
2464 //------------------------------match_edge-------------------------------------
2465 // Do we Match on this edge index or not?  Match only the address.
2466 uint LoadNode::match_edge(uint idx) const {
2467   return idx == MemNode::Address;
2468 }
2469 
2470 //--------------------------LoadBNode::Ideal--------------------------------------
2471 //
2472 //  If the previous store is to the same address as this load,
2473 //  and the value stored was larger than a byte, replace this load
2474 //  with the value stored truncated to a byte.  If no truncation is
2475 //  needed, the replacement is done in LoadNode::Identity().
2476 //
2477 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2478   Node* mem = in(MemNode::Memory);
2479   Node* value = can_see_stored_value(mem,phase);
2480   if (value != nullptr) {
2481     Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2482     if (narrow != value) {
2483       return narrow;
2484     }
2485   }
2486   // Identity call will handle the case where truncation is not needed.
2487   return LoadNode::Ideal(phase, can_reshape);
2488 }
2489 
2490 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2491   Node* mem = in(MemNode::Memory);
2492   Node* value = can_see_stored_value(mem,phase);
2493   if (value != nullptr && value->is_Con() &&
2494       !value->bottom_type()->higher_equal(_type)) {
2495     // If the input to the store does not fit with the load's result type,
2496     // it must be truncated. We can't delay until Ideal call since
2497     // a singleton Value is needed for split_thru_phi optimization.
2498     int con = value->get_int();
2499     return TypeInt::make((con << 24) >> 24);
2500   }
2501   return LoadNode::Value(phase);
2502 }
2503 
2504 //--------------------------LoadUBNode::Ideal-------------------------------------
2505 //
2506 //  If the previous store is to the same address as this load,
2507 //  and the value stored was larger than a byte, replace this load
2508 //  with the value stored truncated to a byte.  If no truncation is
2509 //  needed, the replacement is done in LoadNode::Identity().
2510 //
2511 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2512   Node* mem = in(MemNode::Memory);
2513   Node* value = can_see_stored_value(mem, phase);
2514   if (value != nullptr) {
2515     Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2516     if (narrow != value) {
2517       return narrow;
2518     }
2519   }
2520   // Identity call will handle the case where truncation is not needed.
2521   return LoadNode::Ideal(phase, can_reshape);
2522 }
2523 
2524 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2525   Node* mem = in(MemNode::Memory);
2526   Node* value = can_see_stored_value(mem,phase);
2527   if (value != nullptr && value->is_Con() &&
2528       !value->bottom_type()->higher_equal(_type)) {
2529     // If the input to the store does not fit with the load's result type,
2530     // it must be truncated. We can't delay until Ideal call since
2531     // a singleton Value is needed for split_thru_phi optimization.
2532     int con = value->get_int();
2533     return TypeInt::make(con & 0xFF);
2534   }
2535   return LoadNode::Value(phase);
2536 }
2537 
2538 //--------------------------LoadUSNode::Ideal-------------------------------------
2539 //
2540 //  If the previous store is to the same address as this load,
2541 //  and the value stored was larger than a char, replace this load
2542 //  with the value stored truncated to a char.  If no truncation is
2543 //  needed, the replacement is done in LoadNode::Identity().
2544 //
2545 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2546   Node* mem = in(MemNode::Memory);
2547   Node* value = can_see_stored_value(mem,phase);
2548   if (value != nullptr) {
2549     Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2550     if (narrow != value) {
2551       return narrow;
2552     }
2553   }
2554   // Identity call will handle the case where truncation is not needed.
2555   return LoadNode::Ideal(phase, can_reshape);
2556 }
2557 
2558 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2559   Node* mem = in(MemNode::Memory);
2560   Node* value = can_see_stored_value(mem,phase);
2561   if (value != nullptr && value->is_Con() &&
2562       !value->bottom_type()->higher_equal(_type)) {
2563     // If the input to the store does not fit with the load's result type,
2564     // it must be truncated. We can't delay until Ideal call since
2565     // a singleton Value is needed for split_thru_phi optimization.
2566     int con = value->get_int();
2567     return TypeInt::make(con & 0xFFFF);
2568   }
2569   return LoadNode::Value(phase);
2570 }
2571 
2572 //--------------------------LoadSNode::Ideal--------------------------------------
2573 //
2574 //  If the previous store is to the same address as this load,
2575 //  and the value stored was larger than a short, replace this load
2576 //  with the value stored truncated to a short.  If no truncation is
2577 //  needed, the replacement is done in LoadNode::Identity().
2578 //
2579 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2580   Node* mem = in(MemNode::Memory);
2581   Node* value = can_see_stored_value(mem,phase);
2582   if (value != nullptr) {
2583     Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2584     if (narrow != value) {
2585       return narrow;
2586     }
2587   }
2588   // Identity call will handle the case where truncation is not needed.
2589   return LoadNode::Ideal(phase, can_reshape);
2590 }
2591 
2592 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2593   Node* mem = in(MemNode::Memory);
2594   Node* value = can_see_stored_value(mem,phase);
2595   if (value != nullptr && value->is_Con() &&
2596       !value->bottom_type()->higher_equal(_type)) {
2597     // If the input to the store does not fit with the load's result type,
2598     // it must be truncated. We can't delay until Ideal call since
2599     // a singleton Value is needed for split_thru_phi optimization.
2600     int con = value->get_int();
2601     return TypeInt::make((con << 16) >> 16);
2602   }
2603   return LoadNode::Value(phase);
2604 }
2605 
2606 Node* LoadNNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2607   // Loading from an InlineType, find the input and make an EncodeP
2608   Node* addr = in(Address);
2609   intptr_t offset;
2610   Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
2611   Node* value = see_through_inline_type(phase, this, base, offset);
2612   if (value != nullptr) {
2613     return new EncodePNode(value, type());
2614   }
2615 
2616   return LoadNode::Ideal(phase, can_reshape);
2617 }
2618 
2619 //=============================================================================
2620 //----------------------------LoadKlassNode::make------------------------------
2621 // Polymorphic factory method:
2622 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2623   // sanity check the alias category against the created node type
2624   const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2625   assert(adr_type != nullptr, "expecting TypeKlassPtr");
2626 #ifdef _LP64
2627   if (adr_type->is_ptr_to_narrowklass()) {
2628     assert(UseCompressedClassPointers, "no compressed klasses");
2629     Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2630     return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2631   }
2632 #endif
2633   assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2634   return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2635 }
2636 
2637 //------------------------------Value------------------------------------------
2638 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2639   return klass_value_common(phase);
2640 }
2641 
2642 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2643   // Either input is TOP ==> the result is TOP
2644   const Type *t1 = phase->type( in(MemNode::Memory) );
2645   if (t1 == Type::TOP)  return Type::TOP;
2646   Node *adr = in(MemNode::Address);
2647   const Type *t2 = phase->type( adr );
2648   if (t2 == Type::TOP)  return Type::TOP;
2649   const TypePtr *tp = t2->is_ptr();
2650   if (TypePtr::above_centerline(tp->ptr()) ||
2651       tp->ptr() == TypePtr::Null)  return Type::TOP;
2652 
2653   // Return a more precise klass, if possible
2654   const TypeInstPtr *tinst = tp->isa_instptr();
2655   if (tinst != nullptr) {
2656     ciInstanceKlass* ik = tinst->instance_klass();
2657     int offset = tinst->offset();
2658     if (ik == phase->C->env()->Class_klass()
2659         && (offset == java_lang_Class::klass_offset() ||
2660             offset == java_lang_Class::array_klass_offset())) {
2661       // We are loading a special hidden field from a Class mirror object,
2662       // the field which points to the VM's Klass metaobject.
2663       bool is_null_free_array = false;
2664       ciType* t = tinst->java_mirror_type(&is_null_free_array);
2665       // java_mirror_type returns non-null for compile-time Class constants.
2666       if (t != nullptr) {
2667         // constant oop => constant klass
2668         if (offset == java_lang_Class::array_klass_offset()) {
2669           if (t->is_void()) {
2670             // We cannot create a void array.  Since void is a primitive type return null
2671             // klass.  Users of this result need to do a null check on the returned klass.
2672             return TypePtr::NULL_PTR;
2673           }
2674           const TypeKlassPtr* tklass = TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2675           if (is_null_free_array) {
2676             tklass = tklass->is_aryklassptr()->cast_to_null_free();
2677           }
2678           return tklass;
2679         }
2680         if (!t->is_klass()) {
2681           // a primitive Class (e.g., int.class) has null for a klass field
2682           return TypePtr::NULL_PTR;
2683         }
2684         // Fold up the load of the hidden field
2685         const TypeKlassPtr* tklass = TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2686         if (is_null_free_array) {
2687           tklass = tklass->is_aryklassptr()->cast_to_null_free();
2688         }
2689         return tklass;
2690       }
2691       // non-constant mirror, so we can't tell what's going on
2692     }
2693     if (!tinst->is_loaded())
2694       return _type;             // Bail out if not loaded
2695     if (offset == oopDesc::klass_offset_in_bytes()) {
2696       return tinst->as_klass_type(true);
2697     }
2698   }
2699 
2700   // Check for loading klass from an array
2701   const TypeAryPtr* tary = tp->isa_aryptr();
2702   if (tary != nullptr &&
2703       tary->offset() == oopDesc::klass_offset_in_bytes()) {
2704     return tary->as_klass_type(true);
2705   }
2706 
2707   // Check for loading klass from an array klass
2708   const TypeKlassPtr *tkls = tp->isa_klassptr();
2709   if (tkls != nullptr && !StressReflectiveCode) {
2710     if (!tkls->is_loaded())
2711      return _type;             // Bail out if not loaded
2712     if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2713         tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2714       // // Always returning precise element type is incorrect,
2715       // // e.g., element type could be object and array may contain strings
2716       // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2717 
2718       // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2719       // according to the element type's subclassing.
2720       return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2721     }
2722     if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2723         tkls->offset() == in_bytes(Klass::super_offset())) {
2724       ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2725       // The field is Klass::_super.  Return its (constant) value.
2726       // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2727       return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2728     }
2729   }
2730 
2731   if (tkls != nullptr && !UseSecondarySupersCache
2732       && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset()))  {
2733     // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2734     return TypePtr::NULL_PTR;
2735   }
2736 
2737   // Bailout case
2738   return LoadNode::Value(phase);
2739 }
2740 
2741 //------------------------------Identity---------------------------------------
2742 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2743 // Also feed through the klass in Allocate(...klass...)._klass.
2744 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2745   return klass_identity_common(phase);
2746 }
2747 
2748 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2749   Node* x = LoadNode::Identity(phase);
2750   if (x != this)  return x;
2751 
2752   // Take apart the address into an oop and offset.
2753   // Return 'this' if we cannot.
2754   Node*    adr    = in(MemNode::Address);
2755   intptr_t offset = 0;
2756   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2757   if (base == nullptr)     return this;
2758   const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2759   if (toop == nullptr)     return this;
2760 
2761   // Step over potential GC barrier for OopHandle resolve
2762   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2763   if (bs->is_gc_barrier_node(base)) {
2764     base = bs->step_over_gc_barrier(base);
2765   }
2766 
2767   // We can fetch the klass directly through an AllocateNode.
2768   // This works even if the klass is not constant (clone or newArray).
2769   if (offset == oopDesc::klass_offset_in_bytes()) {
2770     Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2771     if (allocated_klass != nullptr) {
2772       return allocated_klass;
2773     }
2774   }
2775 
2776   // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2777   // See inline_native_Class_query for occurrences of these patterns.
2778   // Java Example:  x.getClass().isAssignableFrom(y)
2779   //
2780   // This improves reflective code, often making the Class
2781   // mirror go completely dead.  (Current exception:  Class
2782   // mirrors may appear in debug info, but we could clean them out by
2783   // introducing a new debug info operator for Klass.java_mirror).
2784 
2785   if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2786       && offset == java_lang_Class::klass_offset()) {
2787     if (base->is_Load()) {
2788       Node* base2 = base->in(MemNode::Address);
2789       if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2790         Node* adr2 = base2->in(MemNode::Address);
2791         const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2792         if (tkls != nullptr && !tkls->empty()
2793             && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2794             && adr2->is_AddP()
2795            ) {
2796           int mirror_field = in_bytes(Klass::java_mirror_offset());
2797           if (tkls->offset() == mirror_field) {
2798             return adr2->in(AddPNode::Base);
2799           }
2800         }
2801       }
2802     }
2803   }
2804 
2805   return this;
2806 }
2807 
2808 LoadNode* LoadNode::clone_pinned() const {
2809   LoadNode* ld = clone()->as_Load();
2810   ld->_control_dependency = UnknownControl;
2811   return ld;
2812 }
2813 
2814 
2815 //------------------------------Value------------------------------------------
2816 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2817   const Type *t = klass_value_common(phase);
2818   if (t == Type::TOP)
2819     return t;
2820 
2821   return t->make_narrowklass();
2822 }
2823 
2824 //------------------------------Identity---------------------------------------
2825 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2826 // Also feed through the klass in Allocate(...klass...)._klass.
2827 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2828   Node *x = klass_identity_common(phase);
2829 
2830   const Type *t = phase->type( x );
2831   if( t == Type::TOP ) return x;
2832   if( t->isa_narrowklass()) return x;
2833   assert (!t->isa_narrowoop(), "no narrow oop here");
2834 
2835   return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2836 }
2837 
2838 //------------------------------Value-----------------------------------------
2839 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2840   // Either input is TOP ==> the result is TOP
2841   const Type *t1 = phase->type( in(MemNode::Memory) );
2842   if( t1 == Type::TOP ) return Type::TOP;
2843   Node *adr = in(MemNode::Address);
2844   const Type *t2 = phase->type( adr );
2845   if( t2 == Type::TOP ) return Type::TOP;
2846   const TypePtr *tp = t2->is_ptr();
2847   if (TypePtr::above_centerline(tp->ptr()))  return Type::TOP;
2848   const TypeAryPtr *tap = tp->isa_aryptr();
2849   if( !tap ) return _type;
2850   return tap->size();
2851 }
2852 
2853 //-------------------------------Ideal---------------------------------------
2854 // Feed through the length in AllocateArray(...length...)._length.
2855 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2856   Node* p = MemNode::Ideal_common(phase, can_reshape);
2857   if (p)  return (p == NodeSentinel) ? nullptr : p;
2858 
2859   // Take apart the address into an oop and offset.
2860   // Return 'this' if we cannot.
2861   Node*    adr    = in(MemNode::Address);
2862   intptr_t offset = 0;
2863   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase,  offset);
2864   if (base == nullptr)     return nullptr;
2865   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2866   if (tary == nullptr)     return nullptr;
2867 
2868   // We can fetch the length directly through an AllocateArrayNode.
2869   // This works even if the length is not constant (clone or newArray).
2870   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2871     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2872     if (alloc != nullptr) {
2873       Node* allocated_length = alloc->Ideal_length();
2874       Node* len = alloc->make_ideal_length(tary, phase);
2875       if (allocated_length != len) {
2876         // New CastII improves on this.
2877         return len;
2878       }
2879     }
2880   }
2881 
2882   return nullptr;
2883 }
2884 
2885 //------------------------------Identity---------------------------------------
2886 // Feed through the length in AllocateArray(...length...)._length.
2887 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2888   Node* x = LoadINode::Identity(phase);
2889   if (x != this)  return x;
2890 
2891   // Take apart the address into an oop and offset.
2892   // Return 'this' if we cannot.
2893   Node*    adr    = in(MemNode::Address);
2894   intptr_t offset = 0;
2895   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2896   if (base == nullptr)     return this;
2897   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2898   if (tary == nullptr)     return this;
2899 
2900   // We can fetch the length directly through an AllocateArrayNode.
2901   // This works even if the length is not constant (clone or newArray).
2902   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2903     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2904     if (alloc != nullptr) {
2905       Node* allocated_length = alloc->Ideal_length();
2906       // Do not allow make_ideal_length to allocate a CastII node.
2907       Node* len = alloc->make_ideal_length(tary, phase, false);
2908       if (allocated_length == len) {
2909         // Return allocated_length only if it would not be improved by a CastII.
2910         return allocated_length;
2911       }
2912     }
2913   }
2914 
2915   return this;
2916 
2917 }
2918 
2919 //=============================================================================
2920 //---------------------------StoreNode::make-----------------------------------
2921 // Polymorphic factory method:
2922 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) {
2923   assert((mo == unordered || mo == release), "unexpected");
2924   Compile* C = gvn.C;
2925   assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2926          ctl != nullptr, "raw memory operations should have control edge");
2927 
2928   switch (bt) {
2929   case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2930   case T_BYTE:    return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2931   case T_INT:     return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2932   case T_CHAR:
2933   case T_SHORT:   return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2934   case T_LONG:    return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2935   case T_FLOAT:   return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2936   case T_DOUBLE:  return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2937   case T_METADATA:
2938   case T_ADDRESS:
2939   case T_OBJECT:
2940 #ifdef _LP64
2941     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2942       val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2943       return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2944     } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2945                (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2946                 adr->bottom_type()->isa_rawptr())) {
2947       val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2948       return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2949     }
2950 #endif
2951     {
2952       return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2953     }
2954   default:
2955     ShouldNotReachHere();
2956     return (StoreNode*)nullptr;
2957   }
2958 }
2959 
2960 //--------------------------bottom_type----------------------------------------
2961 const Type *StoreNode::bottom_type() const {
2962   return Type::MEMORY;
2963 }
2964 
2965 //------------------------------hash-------------------------------------------
2966 uint StoreNode::hash() const {
2967   // unroll addition of interesting fields
2968   //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2969 
2970   // Since they are not commoned, do not hash them:
2971   return NO_HASH;
2972 }
2973 
2974 // Link together multiple stores (B/S/C/I) into a longer one.
2975 //
2976 // Example: _store = StoreB[i+3]
2977 //
2978 //   RangeCheck[i+0]           RangeCheck[i+0]
2979 //   StoreB[i+0]
2980 //   RangeCheck[i+3]           RangeCheck[i+3]
2981 //   StoreB[i+1]         -->   pass:             fail:
2982 //   StoreB[i+2]               StoreI[i+0]       StoreB[i+0]
2983 //   StoreB[i+3]
2984 //
2985 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2986 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2987 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2988 // failing path.
2989 //
2990 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2991 //       - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2992 //                                       and possibly no RangeChecks remain between the stores.
2993 //       - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2994 //                              and those later RangeChecks can be removed. Example:
2995 //
2996 //                              RangeCheck[i+0]                         RangeCheck[i+0] <- before first store
2997 //                              StoreB[i+0]                             StoreB[i+0]     <- first store
2998 //                              RangeCheck[i+1]     --> smeared -->     RangeCheck[i+3] <- only RC between first and last store
2999 //                              StoreB[i+1]                             StoreB[i+1]     <- second store
3000 //                              RangeCheck[i+2]     --> removed
3001 //                              StoreB[i+2]                             StoreB[i+2]
3002 //                              RangeCheck[i+3]     --> removed
3003 //                              StoreB[i+3]                             StoreB[i+3]     <- last store
3004 //
3005 //                              Thus, it is a common pattern that between the first and last store in a chain
3006 //                              of adjacent stores there remains exactly one RangeCheck, located between the
3007 //                              first and the second store (e.g. RangeCheck[i+3]).
3008 //
3009 class MergePrimitiveStores : public StackObj {
3010 private:
3011   PhaseGVN* const _phase;
3012   StoreNode* const _store;
3013   // State machine with initial state Unknown
3014   // Allowed transitions:
3015   //   Unknown     -> Const
3016   //   Unknown     -> Platform
3017   //   Unknown     -> Reverse
3018   //   Unknown     -> NotAdjacent
3019   //   Const       -> Const
3020   //   Const       -> NotAdjacent
3021   //   Platform    -> Platform
3022   //   Platform    -> NotAdjacent
3023   //   Reverse     -> Reverse
3024   //   Reverse     -> NotAdjacent
3025   //   NotAdjacent -> NotAdjacent
3026   enum ValueOrder : uint8_t {
3027     Unknown,     // Initial state
3028     Const,       // Input values are const
3029     Platform,    // Platform order
3030     Reverse,     // Reverse platform order
3031     NotAdjacent  // Not adjacent
3032   };
3033   ValueOrder  _value_order;
3034 
3035   NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
3036 
3037 public:
3038   MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
3039     _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
3040     NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
3041     {}
3042 
3043   StoreNode* run();
3044 
3045 private:
3046   bool is_compatible_store(const StoreNode* other_store) const;
3047   bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
3048   bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
3049   static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
3050   enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
3051   static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
3052 
3053   class Status {
3054   private:
3055     StoreNode* _found_store;
3056     bool       _found_range_check;
3057 
3058     Status(StoreNode* found_store, bool found_range_check)
3059       : _found_store(found_store), _found_range_check(found_range_check) {}
3060 
3061   public:
3062     StoreNode* found_store() const { return _found_store; }
3063     bool found_range_check() const { return _found_range_check; }
3064     static Status make_failure() { return Status(nullptr, false); }
3065 
3066     static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
3067       if (cfg_status == CFGStatus::Failure) {
3068         return Status::make_failure();
3069       }
3070       return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
3071     }
3072 
3073 #ifndef PRODUCT
3074     void print_on(outputStream* st) const {
3075       if (_found_store == nullptr) {
3076         st->print_cr("None");
3077       } else {
3078         st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
3079                                          _found_range_check ? "RC" : "no-RC");
3080       }
3081     }
3082 #endif
3083   };
3084 
3085   enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
3086   Status find_adjacent_use_store(const StoreNode* def_store) const;
3087   Status find_adjacent_def_store(const StoreNode* use_store) const;
3088   Status find_use_store(const StoreNode* def_store) const;
3089   Status find_def_store(const StoreNode* use_store) const;
3090   Status find_use_store_unidirectional(const StoreNode* def_store) const;
3091   Status find_def_store_unidirectional(const StoreNode* use_store) const;
3092 
3093   void collect_merge_list(Node_List& merge_list) const;
3094   Node* make_merged_input_value(const Node_List& merge_list);
3095   StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
3096 
3097 #ifndef PRODUCT
3098   // Access to TraceMergeStores tags
3099   bool is_trace(TraceMergeStores::Tag tag) const {
3100     return _trace_tags.at(tag);
3101   }
3102 
3103   bool is_trace_basic() const {
3104     return is_trace(TraceMergeStores::Tag::BASIC);
3105   }
3106 
3107   bool is_trace_pointer_parsing() const {
3108     return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
3109   }
3110 
3111   bool is_trace_pointer_aliasing() const {
3112     return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
3113   }
3114 
3115   bool is_trace_pointer_adjacency() const {
3116     return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
3117   }
3118 
3119   bool is_trace_success() const {
3120     return is_trace(TraceMergeStores::Tag::SUCCESS);
3121   }
3122 #endif
3123 
3124   NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
3125 };
3126 
3127 StoreNode* MergePrimitiveStores::run() {
3128   // Check for B/S/C/I
3129   int opc = _store->Opcode();
3130   if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
3131     return nullptr;
3132   }
3133 
3134   NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
3135 
3136   // The _store must be the "last" store in a chain. If we find a use we could merge with
3137   // then that use or a store further down is the "last" store.
3138   Status status_use = find_adjacent_use_store(_store);
3139   NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
3140   if (status_use.found_store() != nullptr) {
3141     return nullptr;
3142   }
3143 
3144   // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
3145   Status status_def = find_adjacent_def_store(_store);
3146   NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
3147   Node* def_store = status_def.found_store();
3148   if (def_store == nullptr) {
3149     return nullptr;
3150   }
3151 
3152   // Initialize value order
3153   _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
3154                                                  _store->in(MemNode::ValueIn),
3155                                                  _store->memory_size());
3156   assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
3157 
3158   ResourceMark rm;
3159   Node_List merge_list;
3160   collect_merge_list(merge_list);
3161 
3162   Node* merged_input_value = make_merged_input_value(merge_list);
3163   if (merged_input_value == nullptr) { return nullptr; }
3164 
3165   StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3166 
3167   NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
3168 
3169   return merged_store;
3170 }
3171 
3172 // Check compatibility between _store and other_store.
3173 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
3174   int opc = _store->Opcode();
3175   assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3176 
3177   if (other_store == nullptr ||
3178       _store->Opcode() != other_store->Opcode()) {
3179     return false;
3180   }
3181 
3182   return true;
3183 }
3184 
3185 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3186   if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3187                               use_store->in(MemNode::ValueIn),
3188                               def_store->memory_size())) {
3189     return false;
3190   }
3191 
3192   ResourceMark rm;
3193 #ifndef PRODUCT
3194   const TraceMemPointer trace(is_trace_pointer_parsing(),
3195                               is_trace_pointer_aliasing(),
3196                               is_trace_pointer_adjacency(),
3197                               true);
3198 #endif
3199   const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
3200   const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
3201   return pointer_def.is_adjacent_to_and_before(pointer_use);
3202 }
3203 
3204 // Check input values n1 and n2 can be merged and return the value order
3205 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
3206                                                                                        const int memory_size) const {
3207   // Pattern: [n1 = ConI, n2 = ConI]
3208   if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
3209     return ValueOrder::Const;
3210   }
3211 
3212   Node const *base_n2;
3213   jint shift_n2;
3214   if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
3215     return ValueOrder::NotAdjacent;
3216   }
3217   Node const *base_n1;
3218   jint shift_n1;
3219   if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
3220     return ValueOrder::NotAdjacent;
3221   }
3222 
3223   int bits_per_store = memory_size * 8;
3224   if (base_n1 != base_n2 ||
3225       abs(shift_n1 - shift_n2) != bits_per_store ||
3226       shift_n1 % bits_per_store != 0) {
3227     // Values are not adjacent
3228     return ValueOrder::NotAdjacent;
3229   }
3230 
3231   // Detect value order
3232 #ifdef VM_LITTLE_ENDIAN
3233   return shift_n1 < shift_n2 ? ValueOrder::Platform     // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3234                              : ValueOrder::Reverse;     // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3235 #else
3236   return shift_n1 > shift_n2 ? ValueOrder::Platform     // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3237                              : ValueOrder::Reverse;     // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3238 #endif
3239 }
3240 
3241 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3242   ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3243 
3244   switch (input_value_order) {
3245     case ValueOrder::NotAdjacent:
3246       return false;
3247     case ValueOrder::Reverse:
3248       if (memory_size != 1 ||
3249           !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3250           !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3251           !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3252         // ReverseBytes are not supported by platform
3253         return false;
3254       }
3255       // fall-through.
3256     case ValueOrder::Const:
3257     case ValueOrder::Platform:
3258       if (_value_order == ValueOrder::Unknown) {
3259         // Initial state is Unknown, and we find a valid input value order
3260         return true;
3261       }
3262       // The value order can not be changed
3263       return _value_order == input_value_order;
3264     case ValueOrder::Unknown:
3265     default:
3266       ShouldNotReachHere();
3267   }
3268   return false;
3269 }
3270 
3271 // Detect pattern: n = base_out >> shift_out
3272 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3273   assert(n != nullptr, "precondition");
3274 
3275   int opc = n->Opcode();
3276   if (opc == Op_ConvL2I) {
3277     n = n->in(1);
3278     opc = n->Opcode();
3279   }
3280 
3281   if ((opc == Op_RShiftI ||
3282        opc == Op_RShiftL ||
3283        opc == Op_URShiftI ||
3284        opc == Op_URShiftL) &&
3285       n->in(2)->is_ConI()) {
3286     base_out = n->in(1);
3287     shift_out = n->in(2)->get_int();
3288     // The shift must be positive:
3289     return shift_out >= 0;
3290   }
3291 
3292   if (phase->type(n)->isa_int()  != nullptr ||
3293       phase->type(n)->isa_long() != nullptr) {
3294     // (base >> 0)
3295     base_out = n;
3296     shift_out = 0;
3297     return true;
3298   }
3299   return false;
3300 }
3301 
3302 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3303 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3304   assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3305 
3306   Node* ctrl_use = use_store->in(MemNode::Control);
3307   Node* ctrl_def = def_store->in(MemNode::Control);
3308   if (ctrl_use == nullptr || ctrl_def == nullptr) {
3309     return CFGStatus::Failure;
3310   }
3311 
3312   if (ctrl_use == ctrl_def) {
3313     // Same ctrl -> no RangeCheck in between.
3314     // Check: use_store must be the only use of def_store.
3315     if (def_store->outcnt() > 1) {
3316       return CFGStatus::Failure;
3317     }
3318     return CFGStatus::SuccessNoRangeCheck;
3319   }
3320 
3321   // Different ctrl -> could have RangeCheck in between.
3322   // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3323   //        2. ctrl separated by RangeCheck.
3324   if (def_store->outcnt() != 2) {
3325     return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3326   }
3327   int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3328   Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3329   if (merge_mem == nullptr ||
3330       merge_mem->outcnt() != 1) {
3331     return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3332   }
3333   if (!ctrl_use->is_IfProj() ||
3334       !ctrl_use->in(0)->is_RangeCheck() ||
3335       ctrl_use->in(0)->outcnt() != 2) {
3336     return CFGStatus::Failure; // Not RangeCheck.
3337   }
3338   ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3339   Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3340   if (trap != merge_mem->unique_out() ||
3341       ctrl_use->in(0)->in(0) != ctrl_def) {
3342     return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3343   }
3344 
3345   return CFGStatus::SuccessWithRangeCheck;
3346 }
3347 
3348 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3349   Status status_use = find_use_store(def_store);
3350   StoreNode* use_store = status_use.found_store();
3351   if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3352     return Status::make_failure();
3353   }
3354   return status_use;
3355 }
3356 
3357 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3358   Status status_def = find_def_store(use_store);
3359   StoreNode* def_store = status_def.found_store();
3360   if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3361     return Status::make_failure();
3362   }
3363   return status_def;
3364 }
3365 
3366 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3367   Status status_use = find_use_store_unidirectional(def_store);
3368 
3369 #ifdef ASSERT
3370   StoreNode* use_store = status_use.found_store();
3371   if (use_store != nullptr) {
3372     Status status_def = find_def_store_unidirectional(use_store);
3373     assert(status_def.found_store() == def_store &&
3374            status_def.found_range_check() == status_use.found_range_check(),
3375            "find_use_store and find_def_store must be symmetric");
3376   }
3377 #endif
3378 
3379   return status_use;
3380 }
3381 
3382 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3383   Status status_def = find_def_store_unidirectional(use_store);
3384 
3385 #ifdef ASSERT
3386   StoreNode* def_store = status_def.found_store();
3387   if (def_store != nullptr) {
3388     Status status_use = find_use_store_unidirectional(def_store);
3389     assert(status_use.found_store() == use_store &&
3390            status_use.found_range_check() == status_def.found_range_check(),
3391            "find_use_store and find_def_store must be symmetric");
3392   }
3393 #endif
3394 
3395   return status_def;
3396 }
3397 
3398 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3399   assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3400 
3401   for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3402     StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3403     if (is_compatible_store(use_store)) {
3404       return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3405     }
3406   }
3407 
3408   return Status::make_failure();
3409 }
3410 
3411 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3412   assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3413 
3414   StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3415   if (!is_compatible_store(def_store)) {
3416     return Status::make_failure();
3417   }
3418 
3419   return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3420 }
3421 
3422 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3423   // The merged store can be at most 8 bytes.
3424   const uint merge_list_max_size = 8 / _store->memory_size();
3425   assert(merge_list_max_size >= 2 &&
3426          merge_list_max_size <= 8 &&
3427          is_power_of_2(merge_list_max_size),
3428          "must be 2, 4 or 8");
3429 
3430   // Traverse up the chain of adjacent def stores.
3431   StoreNode* current = _store;
3432   merge_list.push(current);
3433   while (current != nullptr && merge_list.size() < merge_list_max_size) {
3434     Status status = find_adjacent_def_store(current);
3435     NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3436 
3437     current = status.found_store();
3438     if (current != nullptr) {
3439       merge_list.push(current);
3440 
3441       // We can have at most one RangeCheck.
3442       if (status.found_range_check()) {
3443         NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3444         break;
3445       }
3446     }
3447   }
3448 
3449   NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3450 
3451   // Truncate the merge_list to a power of 2.
3452   const uint pow2size = round_down_power_of_2(merge_list.size());
3453   assert(pow2size >= 2, "must be merging at least 2 stores");
3454   while (merge_list.size() > pow2size) { merge_list.pop(); }
3455 
3456   NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3457 }
3458 
3459 // Merge the input values of the smaller stores to a single larger input value.
3460 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3461   int new_memory_size = _store->memory_size() * merge_list.size();
3462   Node* first = merge_list.at(merge_list.size()-1);
3463   Node* merged_input_value = nullptr;
3464   if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3465     assert(_value_order == ValueOrder::Const, "must match");
3466     // Pattern: [ConI, ConI, ...] -> new constant
3467     jlong con = 0;
3468     jlong bits_per_store = _store->memory_size() * 8;
3469     jlong mask = (((jlong)1) << bits_per_store) - 1;
3470     for (uint i = 0; i < merge_list.size(); i++) {
3471       jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3472 #ifdef VM_LITTLE_ENDIAN
3473       con = con << bits_per_store;
3474       con = con | (mask & con_i);
3475 #else // VM_LITTLE_ENDIAN
3476       con_i = (mask & con_i) << (i * bits_per_store);
3477       con = con | con_i;
3478 #endif // VM_LITTLE_ENDIAN
3479     }
3480     merged_input_value = _phase->longcon(con);
3481   } else {
3482     assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3483     // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3484     //             |                                  |
3485     //           _store                             first
3486     //
3487     Node* hi = _store->in(MemNode::ValueIn);
3488     Node* lo = first->in(MemNode::ValueIn);
3489 #ifndef VM_LITTLE_ENDIAN
3490     // `_store` and `first` are swapped in the diagram above
3491     swap(hi, lo);
3492 #endif // !VM_LITTLE_ENDIAN
3493     if (_value_order == ValueOrder::Reverse) {
3494       swap(hi, lo);
3495     }
3496     Node const* hi_base;
3497     jint hi_shift;
3498     merged_input_value = lo;
3499     bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3500     assert(is_true, "must detect con RShift");
3501     if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3502       // look through
3503       merged_input_value = merged_input_value->in(1);
3504     }
3505     if (merged_input_value != hi_base) {
3506       // merged_input_value is not the base
3507       return nullptr;
3508     }
3509   }
3510 
3511   if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3512     // Example:
3513     //
3514     //   long base = ...;
3515     //   a[0] = (byte)(base >> 0);
3516     //   a[1] = (byte)(base >> 8);
3517     //
3518     merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3519   }
3520 
3521   assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3522          (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3523          "merged_input_value is either int or long, and new_memory_size is small enough");
3524 
3525   if (_value_order == ValueOrder::Reverse) {
3526     assert(_store->memory_size() == 1, "only implemented for bytes");
3527     if (new_memory_size == 8) {
3528       merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3529     } else if (new_memory_size == 4) {
3530       merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3531     } else {
3532       assert(new_memory_size == 2, "sanity check");
3533       merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3534     }
3535   }
3536   return merged_input_value;
3537 }
3538 
3539 //                                                                                                          //
3540 // first_ctrl    first_mem   first_adr                first_ctrl    first_mem         first_adr             //
3541 //  |                |           |                     |                |                 |                 //
3542 //  |                |           |                     |                +---------------+ |                 //
3543 //  |                |           |                     |                |               | |                 //
3544 //  |                | +---------+                     |                | +---------------+                 //
3545 //  |                | |                               |                | |             | |                 //
3546 //  +--------------+ | |  v1                           +------------------------------+ | |  v1             //
3547 //  |              | | |  |                            |                | |           | | |  |              //
3548 // RangeCheck     first_store                         RangeCheck        | |          first_store            //
3549 //  |                |  |                              |                | |                |                //
3550 // last_ctrl         |  +----> unc_trap               last_ctrl         | |                +----> unc_trap  //
3551 //  |                |                       ===>      |                | |                                 //
3552 //  +--------------+ | a2 v2                           |                | |                                 //
3553 //  |              | | |  |                            |                | |                                 //
3554 //  |             second_store                         |                | |                                 //
3555 //  |                |                                 |                | | [v1 v2   ...   vn]              //
3556 // ...              ...                                |                | |         |                       //
3557 //  |                |                                 |                | |         v                       //
3558 //  +--------------+ | an vn                           +--------------+ | | merged_input_value              //
3559 //                 | | |  |                                           | | |  |                              //
3560 //                last_store (= _store)                              merged_store                           //
3561 //                                                                                                          //
3562 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3563   Node* first_store = merge_list.at(merge_list.size()-1);
3564   Node* last_ctrl   = _store->in(MemNode::Control); // after (optional) RangeCheck
3565   Node* first_mem   = first_store->in(MemNode::Memory);
3566   Node* first_adr   = first_store->in(MemNode::Address);
3567 
3568   const TypePtr* new_adr_type = _store->adr_type();
3569 
3570   int new_memory_size = _store->memory_size() * merge_list.size();
3571   BasicType bt = T_ILLEGAL;
3572   switch (new_memory_size) {
3573     case 2: bt = T_SHORT; break;
3574     case 4: bt = T_INT;   break;
3575     case 8: bt = T_LONG;  break;
3576   }
3577 
3578   StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3579                                             new_adr_type, merged_input_value, bt, MemNode::unordered);
3580 
3581   // Marking the store mismatched is sufficient to prevent reordering, since array stores
3582   // are all on the same slice. Hence, we need no barriers.
3583   merged_store->set_mismatched_access();
3584 
3585   // Constants above may now also be be packed -> put candidate on worklist
3586   _phase->is_IterGVN()->_worklist.push(first_mem);
3587 
3588   return merged_store;
3589 }
3590 
3591 #ifndef PRODUCT
3592 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3593   stringStream ss;
3594   ss.print_cr("[TraceMergeStores]: Replace");
3595   for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3596     merge_list.at(i)->dump("\n", false, &ss);
3597   }
3598   ss.print_cr("[TraceMergeStores]: with");
3599   merged_input_value->dump("\n", false, &ss);
3600   merged_store->dump("\n", false, &ss);
3601   tty->print("%s", ss.as_string());
3602 }
3603 #endif
3604 
3605 //------------------------------Ideal------------------------------------------
3606 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3607 // When a store immediately follows a relevant allocation/initialization,
3608 // try to capture it into the initialization, or hoist it above.
3609 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3610   Node* p = MemNode::Ideal_common(phase, can_reshape);
3611   if (p)  return (p == NodeSentinel) ? nullptr : p;
3612 
3613   Node* mem     = in(MemNode::Memory);
3614   Node* address = in(MemNode::Address);
3615   Node* value   = in(MemNode::ValueIn);
3616   // Back-to-back stores to same address?  Fold em up.  Generally
3617   // unsafe if I have intervening uses...
3618   if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
3619     Node* st = mem;
3620     // If Store 'st' has more than one use, we cannot fold 'st' away.
3621     // For example, 'st' might be the final state at a conditional
3622     // return.  Or, 'st' might be used by some node which is live at
3623     // the same time 'st' is live, which might be unschedulable.  So,
3624     // require exactly ONE user until such time as we clone 'mem' for
3625     // each of 'mem's uses (thus making the exactly-1-user-rule hold
3626     // true).
3627     while (st->is_Store() && st->outcnt() == 1) {
3628       // Looking at a dead closed cycle of memory?
3629       assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3630       assert(Opcode() == st->Opcode() ||
3631              st->Opcode() == Op_StoreVector ||
3632              Opcode() == Op_StoreVector ||
3633              st->Opcode() == Op_StoreVectorScatter ||
3634              Opcode() == Op_StoreVectorScatter ||
3635              phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3636              (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3637              (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3638              (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
3639              (st->adr_type()->isa_aryptr() && st->adr_type()->is_aryptr()->is_flat()) || // TODO 8343835
3640              (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3641              "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3642 
3643       if (st->in(MemNode::Address)->eqv_uncast(address) &&
3644           st->as_Store()->memory_size() <= this->memory_size()) {
3645         Node* use = st->raw_out(0);
3646         if (phase->is_IterGVN()) {
3647           phase->is_IterGVN()->rehash_node_delayed(use);
3648         }
3649         // It's OK to do this in the parser, since DU info is always accurate,
3650         // and the parser always refers to nodes via SafePointNode maps.
3651         use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3652         return this;
3653       }
3654       st = st->in(MemNode::Memory);
3655     }
3656   }
3657 
3658 
3659   // Capture an unaliased, unconditional, simple store into an initializer.
3660   // Or, if it is independent of the allocation, hoist it above the allocation.
3661   if (ReduceFieldZeroing && /*can_reshape &&*/
3662       mem->is_Proj() && mem->in(0)->is_Initialize()) {
3663     InitializeNode* init = mem->in(0)->as_Initialize();
3664     intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3665     if (offset > 0) {
3666       Node* moved = init->capture_store(this, offset, phase, can_reshape);
3667       // If the InitializeNode captured me, it made a raw copy of me,
3668       // and I need to disappear.
3669       if (moved != nullptr) {
3670         // %%% hack to ensure that Ideal returns a new node:
3671         mem = MergeMemNode::make(mem);
3672         return mem;             // fold me away
3673       }
3674     }
3675   }
3676 
3677   // Fold reinterpret cast into memory operation:
3678   //    StoreX mem (MoveY2X v) => StoreY mem v
3679   if (value->is_Move()) {
3680     const Type* vt = value->in(1)->bottom_type();
3681     if (has_reinterpret_variant(vt)) {
3682       if (phase->C->post_loop_opts_phase()) {
3683         return convert_to_reinterpret_store(*phase, value->in(1), vt);
3684       } else {
3685         phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3686       }
3687     }
3688   }
3689 
3690   if (MergeStores && UseUnalignedAccesses) {
3691     if (phase->C->merge_stores_phase()) {
3692       MergePrimitiveStores merge(phase, this);
3693       Node* progress = merge.run();
3694       if (progress != nullptr) { return progress; }
3695     } else {
3696       // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3697       // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3698       // the stores, and we merge the wrong sequence of stores.
3699       // Example:
3700       //   StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3701       // Apply MergeStores:
3702       //   StoreI RangeCheck [   StoreL  ] RangeCheck StoreI
3703       // Remove more RangeChecks:
3704       //   StoreI            [   StoreL  ]            StoreI
3705       // But now it would have been better to do this instead:
3706       //   [         StoreL       ] [       StoreL         ]
3707       phase->C->record_for_merge_stores_igvn(this);
3708     }
3709   }
3710 
3711   return nullptr;                  // No further progress
3712 }
3713 
3714 //------------------------------Value-----------------------------------------
3715 const Type* StoreNode::Value(PhaseGVN* phase) const {
3716   // Either input is TOP ==> the result is TOP
3717   const Type *t1 = phase->type( in(MemNode::Memory) );
3718   if( t1 == Type::TOP ) return Type::TOP;
3719   const Type *t2 = phase->type( in(MemNode::Address) );
3720   if( t2 == Type::TOP ) return Type::TOP;
3721   const Type *t3 = phase->type( in(MemNode::ValueIn) );
3722   if( t3 == Type::TOP ) return Type::TOP;
3723   return Type::MEMORY;
3724 }
3725 
3726 //------------------------------Identity---------------------------------------
3727 // Remove redundant stores:
3728 //   Store(m, p, Load(m, p)) changes to m.
3729 //   Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3730 Node* StoreNode::Identity(PhaseGVN* phase) {
3731   Node* mem = in(MemNode::Memory);
3732   Node* adr = in(MemNode::Address);
3733   Node* val = in(MemNode::ValueIn);
3734 
3735   Node* result = this;
3736 
3737   // Load then Store?  Then the Store is useless
3738   if (val->is_Load() &&
3739       val->in(MemNode::Address)->eqv_uncast(adr) &&
3740       val->in(MemNode::Memory )->eqv_uncast(mem) &&
3741       val->as_Load()->store_Opcode() == Opcode()) {
3742     // Ensure vector type is the same
3743     if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3744       result = mem;
3745     }
3746   }
3747 
3748   // Two stores in a row of the same value?
3749   if (result == this &&
3750       mem->is_Store() &&
3751       mem->in(MemNode::Address)->eqv_uncast(adr) &&
3752       mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3753       mem->Opcode() == Opcode()) {
3754     if (!is_StoreVector()) {
3755       result = mem;
3756     } else {
3757       const StoreVectorNode* store_vector = as_StoreVector();
3758       const StoreVectorNode* mem_vector = mem->as_StoreVector();
3759       const Node* store_indices = store_vector->indices();
3760       const Node* mem_indices = mem_vector->indices();
3761       const Node* store_mask = store_vector->mask();
3762       const Node* mem_mask = mem_vector->mask();
3763       // Ensure types, indices, and masks match
3764       if (store_vector->vect_type() == mem_vector->vect_type() &&
3765           ((store_indices == nullptr) == (mem_indices == nullptr) &&
3766            (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3767           ((store_mask == nullptr) == (mem_mask == nullptr) &&
3768            (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3769         result = mem;
3770       }
3771     }
3772   }
3773 
3774   // Store of zero anywhere into a freshly-allocated object?
3775   // Then the store is useless.
3776   // (It must already have been captured by the InitializeNode.)
3777   if (result == this && ReduceFieldZeroing) {
3778     // a newly allocated object is already all-zeroes everywhere
3779     if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
3780         (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::InitValue) == val)) {
3781       result = mem;
3782     }
3783 
3784     if (result == this && phase->type(val)->is_zero_type()) {
3785       // the store may also apply to zero-bits in an earlier object
3786       Node* prev_mem = find_previous_store(phase);
3787       // Steps (a), (b):  Walk past independent stores to find an exact match.
3788       if (prev_mem != nullptr) {
3789         Node* prev_val = can_see_stored_value(prev_mem, phase);
3790         if (prev_val != nullptr && prev_val == val) {
3791           // prev_val and val might differ by a cast; it would be good
3792           // to keep the more informative of the two.
3793           result = mem;
3794         }
3795       }
3796     }
3797   }
3798 
3799   PhaseIterGVN* igvn = phase->is_IterGVN();
3800   if (result != this && igvn != nullptr) {
3801     MemBarNode* trailing = trailing_membar();
3802     if (trailing != nullptr) {
3803 #ifdef ASSERT
3804       const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3805       assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3806 #endif
3807       trailing->remove(igvn);
3808     }
3809   }
3810 
3811   return result;
3812 }
3813 
3814 //------------------------------match_edge-------------------------------------
3815 // Do we Match on this edge index or not?  Match only memory & value
3816 uint StoreNode::match_edge(uint idx) const {
3817   return idx == MemNode::Address || idx == MemNode::ValueIn;
3818 }
3819 
3820 //------------------------------cmp--------------------------------------------
3821 // Do not common stores up together.  They generally have to be split
3822 // back up anyways, so do not bother.
3823 bool StoreNode::cmp( const Node &n ) const {
3824   return (&n == this);          // Always fail except on self
3825 }
3826 
3827 //------------------------------Ideal_masked_input-----------------------------
3828 // Check for a useless mask before a partial-word store
3829 // (StoreB ... (AndI valIn conIa) )
3830 // If (conIa & mask == mask) this simplifies to
3831 // (StoreB ... (valIn) )
3832 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3833   Node *val = in(MemNode::ValueIn);
3834   if( val->Opcode() == Op_AndI ) {
3835     const TypeInt *t = phase->type( val->in(2) )->isa_int();
3836     if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3837       set_req_X(MemNode::ValueIn, val->in(1), phase);
3838       return this;
3839     }
3840   }
3841   return nullptr;
3842 }
3843 
3844 
3845 //------------------------------Ideal_sign_extended_input----------------------
3846 // Check for useless sign-extension before a partial-word store
3847 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3848 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3849 // (StoreB ... (v))
3850 // If (conIL > conIR) under some conditions, it can be simplified into
3851 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3852 // This case happens when the value of the store was itself a left shift, that
3853 // gets merged into the inner left shift of the sign-extension. For instance,
3854 // if we have
3855 // array_of_shorts[0] = (short)(v << 2)
3856 // We get a structure such as:
3857 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3858 // that is simplified into
3859 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3860 // It is thus useful to handle cases where conIL > conIR. But this simplification
3861 // does not always hold. Let's see in which cases it's valid.
3862 //
3863 // Let's assume we have the following 32 bits integer v:
3864 // +----------------------------------+
3865 // |             v[0..31]             |
3866 // +----------------------------------+
3867 //  31                               0
3868 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3869 // potentially different magnitudes.
3870 // We denote num_rejected_bits the number of bits of the discarded part. In this
3871 // case, num_rejected_bits == 24.
3872 //
3873 // Statement (proved further below in case analysis):
3874 //   Given:
3875 //   - 0 <= conIL < BitsPerJavaInteger   (no wrap in shift, enforced by maskShiftAmount)
3876 //   - 0 <= conIR < BitsPerJavaInteger   (no wrap in shift, enforced by maskShiftAmount)
3877 //   - conIL >= conIR
3878 //   - num_rejected_bits >= conIR
3879 //   Then this form:
3880 //      (RShiftI _ (LShiftI _ v conIL) conIR)
3881 //   can be replaced with this form:
3882 //      (LShiftI _ v (conIL-conIR))
3883 //
3884 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3885 //       have to be correct, as the higher bits are rejected / truncated by the store.
3886 //
3887 // The hypotheses
3888 //   0 <= conIL < BitsPerJavaInteger
3889 //   0 <= conIR < BitsPerJavaInteger
3890 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3891 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3892 // to v << 1).
3893 //
3894 //
3895 // If you don't like case analysis, jump after the conclusion.
3896 // ### Case 1 : conIL == conIR
3897 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3898 // If we do the shift left then right by 24 bits, we get:
3899 // after: v << 24
3900 // +---------+------------------------+
3901 // | v[0..7] |           0            |
3902 // +---------+------------------------+
3903 //  31     24 23                      0
3904 // after: (v << 24) >> 24
3905 // +------------------------+---------+
3906 // |        sign bit        | v[0..7] |
3907 // +------------------------+---------+
3908 //  31                     8 7        0
3909 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3910 // result) are the same before and after, so, indeed, simplifying is correct.
3911 
3912 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3913 // If we do the shift left then right by 22 bits, we get:
3914 // after: v << 22
3915 // +---------+------------------------+
3916 // | v[0..9] |           0            |
3917 // +---------+------------------------+
3918 //  31     22 21                      0
3919 // after: (v << 22) >> 22
3920 // +------------------------+---------+
3921 // |        sign bit        | v[0..9] |
3922 // +------------------------+---------+
3923 //  31                    10 9        0
3924 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3925 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3926 // still correct.
3927 
3928 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3929 // If we do the shift left then right by 26 bits, we get:
3930 // after: v << 26
3931 // +---------+------------------------+
3932 // | v[0..5] |           0            |
3933 // +---------+------------------------+
3934 //  31     26 25                      0
3935 // after: (v << 26) >> 26
3936 // +------------------------+---------+
3937 // |        sign bit        | v[0..5] |
3938 // +------------------------+---------+
3939 //  31                     6 5        0
3940 // The non-rejected bits are made of
3941 // - 0-5 => the bits 0 to 5 of v
3942 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3943 // Simplifying this as v is not correct.
3944 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3945 //
3946 // ### Case 2: conIL > conIR
3947 // ###### Case 2.1: num_rejected_bits == conIR
3948 // We take conIL == 26 for this example.
3949 // after: v << 26
3950 // +---------+------------------------+
3951 // | v[0..5] |           0            |
3952 // +---------+------------------------+
3953 //  31     26 25                      0
3954 // after: (v << 26) >> 24
3955 // +------------------+---------+-----+
3956 // |     sign bit     | v[0..5] |  0  |
3957 // +------------------+---------+-----+
3958 //  31               8 7       2 1   0
3959 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3960 // The bits 6 and 7 of v have been thrown away after the shift left.
3961 // The simplification is still correct.
3962 //
3963 // ###### Case 2.2: num_rejected_bits > conIR.
3964 // Let's say conIL == 26 and conIR == 22.
3965 // after: v << 26
3966 // +---------+------------------------+
3967 // | v[0..5] |           0            |
3968 // +---------+------------------------+
3969 //  31     26 25                      0
3970 // after: (v << 26) >> 22
3971 // +------------------+---------+-----+
3972 // |     sign bit     | v[0..5] |  0  |
3973 // +------------------+---------+-----+
3974 //  31              10 9       4 3   0
3975 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3976 // - 0-3 => 0
3977 // - 4-7 => bits 0 to 3 of v
3978 // The simplification is still correct.
3979 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3980 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3981 //
3982 // ###### But! Case 2.3: num_rejected_bits < conIR.
3983 // Let's see that this case is not as easy to simplify.
3984 // Let's say conIL == 28 and conIR == 26.
3985 // after: v << 28
3986 // +---------+------------------------+
3987 // | v[0..3] |           0            |
3988 // +---------+------------------------+
3989 //  31     28 27                      0
3990 // after: (v << 28) >> 26
3991 // +------------------+---------+-----+
3992 // |     sign bit     | v[0..3] |  0  |
3993 // +------------------+---------+-----+
3994 //  31               6 5       2 1   0
3995 // The non-rejected bits are made of
3996 // - 0-1 => 0
3997 // - 2-5 => the bits 0 to 3 of v
3998 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3999 // Simplifying this as (v << 2) is not correct.
4000 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
4001 //
4002 // ### Conclusion:
4003 // Our hypotheses are indeed sufficient:
4004 //   - 0 <= conIL < BitsPerJavaInteger
4005 //   - 0 <= conIR < BitsPerJavaInteger
4006 //   - conIL >= conIR
4007 //   - num_rejected_bits >= conIR
4008 //
4009 // ### A rationale without case analysis:
4010 // After the shift left, conIL upper  bits of v are discarded and conIL lower bit
4011 // zeroes are added. After the shift right, conIR lower bits of the previous result
4012 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
4013 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
4014 // the point of the simplification is to get an expression of the form
4015 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
4016 // simplification is not correct if conIL < conIR.
4017 //
4018 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
4019 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
4020 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
4021 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
4022 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
4023 //
4024 // We do not treat the case conIL < conIR here since the point of this function is
4025 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
4026 // of treating conIL > conIR comes from the cases where the sign-extended value is
4027 // also left-shift expression. Computing the sign-extension of a right-shift expression
4028 // doesn't yield a situation such as
4029 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
4030 // where conIL < conIR.
4031 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
4032   Node* shr = in(MemNode::ValueIn);
4033   if (shr->Opcode() == Op_RShiftI) {
4034     const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
4035     if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
4036       Node* shl = shr->in(1);
4037       if (shl->Opcode() == Op_LShiftI) {
4038         const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
4039         if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
4040           if (conIL->get_con() == conIR->get_con()) {
4041             set_req_X(MemNode::ValueIn, shl->in(1), phase);
4042             return this;
4043           }
4044           if (conIL->get_con() > conIR->get_con()) {
4045             Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
4046             set_req_X(MemNode::ValueIn, new_shl, phase);
4047             return this;
4048           }
4049         }
4050       }
4051     }
4052   }
4053   return nullptr;
4054 }
4055 
4056 //------------------------------value_never_loaded-----------------------------------
4057 // Determine whether there are any possible loads of the value stored.
4058 // For simplicity, we actually check if there are any loads from the
4059 // address stored to, not just for loads of the value stored by this node.
4060 //
4061 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
4062   Node *adr = in(Address);
4063   const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
4064   if (adr_oop == nullptr)
4065     return false;
4066   if (!adr_oop->is_known_instance_field())
4067     return false; // if not a distinct instance, there may be aliases of the address
4068   for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
4069     Node *use = adr->fast_out(i);
4070     if (use->is_Load() || use->is_LoadStore()) {
4071       return false;
4072     }
4073   }
4074   return true;
4075 }
4076 
4077 MemBarNode* StoreNode::trailing_membar() const {
4078   if (is_release()) {
4079     MemBarNode* trailing_mb = nullptr;
4080     for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4081       Node* u = fast_out(i);
4082       if (u->is_MemBar()) {
4083         if (u->as_MemBar()->trailing_store()) {
4084           assert(u->Opcode() == Op_MemBarVolatile, "");
4085           assert(trailing_mb == nullptr, "only one");
4086           trailing_mb = u->as_MemBar();
4087 #ifdef ASSERT
4088           Node* leading = u->as_MemBar()->leading_membar();
4089           assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4090           assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
4091           assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
4092 #endif
4093         } else {
4094           assert(u->as_MemBar()->standalone(), "");
4095         }
4096       }
4097     }
4098     return trailing_mb;
4099   }
4100   return nullptr;
4101 }
4102 
4103 
4104 //=============================================================================
4105 //------------------------------Ideal------------------------------------------
4106 // If the store is from an AND mask that leaves the low bits untouched, then
4107 // we can skip the AND operation.  If the store is from a sign-extension
4108 // (a left shift, then right shift) we can skip both.
4109 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
4110   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
4111   if( progress != nullptr ) return progress;
4112 
4113   progress = StoreNode::Ideal_sign_extended_input(phase, 24);
4114   if( progress != nullptr ) return progress;
4115 
4116   // Finally check the default case
4117   return StoreNode::Ideal(phase, can_reshape);
4118 }
4119 
4120 //=============================================================================
4121 //------------------------------Ideal------------------------------------------
4122 // If the store is from an AND mask that leaves the low bits untouched, then
4123 // we can skip the AND operation
4124 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
4125   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
4126   if( progress != nullptr ) return progress;
4127 
4128   progress = StoreNode::Ideal_sign_extended_input(phase, 16);
4129   if( progress != nullptr ) return progress;
4130 
4131   // Finally check the default case
4132   return StoreNode::Ideal(phase, can_reshape);
4133 }
4134 
4135 //=============================================================================
4136 //----------------------------------SCMemProjNode------------------------------
4137 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
4138 {
4139   if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
4140     return Type::TOP;
4141   }
4142   return bottom_type();
4143 }
4144 
4145 //=============================================================================
4146 //----------------------------------LoadStoreNode------------------------------
4147 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
4148   : Node(required),
4149     _type(rt),
4150     _adr_type(at),
4151     _barrier_data(0)
4152 {
4153   init_req(MemNode::Control, c  );
4154   init_req(MemNode::Memory , mem);
4155   init_req(MemNode::Address, adr);
4156   init_req(MemNode::ValueIn, val);
4157   init_class_id(Class_LoadStore);
4158 }
4159 
4160 //------------------------------Value-----------------------------------------
4161 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
4162   // Either input is TOP ==> the result is TOP
4163   if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
4164     return Type::TOP;
4165   }
4166   const Type* t = phase->type(in(MemNode::Memory));
4167   if (t == Type::TOP) {
4168     return Type::TOP;
4169   }
4170   t = phase->type(in(MemNode::Address));
4171   if (t == Type::TOP) {
4172     return Type::TOP;
4173   }
4174   t = phase->type(in(MemNode::ValueIn));
4175   if (t == Type::TOP) {
4176     return Type::TOP;
4177   }
4178   return bottom_type();
4179 }
4180 
4181 uint LoadStoreNode::ideal_reg() const {
4182   return _type->ideal_reg();
4183 }
4184 
4185 // This method conservatively checks if the result of a LoadStoreNode is
4186 // used, that is, if it returns true, then it is definitely the case that
4187 // the result of the node is not needed.
4188 // For example, GetAndAdd can be matched into a lock_add instead of a
4189 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
4190 bool LoadStoreNode::result_not_used() const {
4191   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4192     Node *x = fast_out(i);
4193     if (x->Opcode() == Op_SCMemProj) {
4194       continue;
4195     }
4196     if (x->bottom_type() == TypeTuple::MEMBAR &&
4197         !x->is_Call() &&
4198         x->Opcode() != Op_Blackhole) {
4199       continue;
4200     }
4201     return false;
4202   }
4203   return true;
4204 }
4205 
4206 MemBarNode* LoadStoreNode::trailing_membar() const {
4207   MemBarNode* trailing = nullptr;
4208   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4209     Node* u = fast_out(i);
4210     if (u->is_MemBar()) {
4211       if (u->as_MemBar()->trailing_load_store()) {
4212         assert(u->Opcode() == Op_MemBarAcquire, "");
4213         assert(trailing == nullptr, "only one");
4214         trailing = u->as_MemBar();
4215 #ifdef ASSERT
4216         Node* leading = trailing->leading_membar();
4217         assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4218         assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
4219         assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
4220 #endif
4221       } else {
4222         assert(u->as_MemBar()->standalone(), "wrong barrier kind");
4223       }
4224     }
4225   }
4226 
4227   return trailing;
4228 }
4229 
4230 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4231 
4232 //=============================================================================
4233 //----------------------------------LoadStoreConditionalNode--------------------
4234 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4235   init_req(ExpectedIn, ex );
4236 }
4237 
4238 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4239   // Either input is TOP ==> the result is TOP
4240   const Type* t = phase->type(in(ExpectedIn));
4241   if (t == Type::TOP) {
4242     return Type::TOP;
4243   }
4244   return LoadStoreNode::Value(phase);
4245 }
4246 
4247 //=============================================================================
4248 //-------------------------------adr_type--------------------------------------
4249 const TypePtr* ClearArrayNode::adr_type() const {
4250   Node *adr = in(3);
4251   if (adr == nullptr)  return nullptr; // node is dead
4252   return MemNode::calculate_adr_type(adr->bottom_type());
4253 }
4254 
4255 //------------------------------match_edge-------------------------------------
4256 // Do we Match on this edge index or not?  Do not match memory
4257 uint ClearArrayNode::match_edge(uint idx) const {
4258   return idx > 1;
4259 }
4260 
4261 //------------------------------Identity---------------------------------------
4262 // Clearing a zero length array does nothing
4263 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4264   return phase->type(in(2))->higher_equal(TypeX::ZERO)  ? in(1) : this;
4265 }
4266 
4267 //------------------------------Idealize---------------------------------------
4268 // Clearing a short array is faster with stores
4269 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4270   // Already know this is a large node, do not try to ideal it
4271   if (_is_large) return nullptr;
4272 
4273   const int unit = BytesPerLong;
4274   const TypeX* t = phase->type(in(2))->isa_intptr_t();
4275   if (!t)  return nullptr;
4276   if (!t->is_con())  return nullptr;
4277   intptr_t raw_count = t->get_con();
4278   intptr_t size = raw_count;
4279   if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4280   // Clearing nothing uses the Identity call.
4281   // Negative clears are possible on dead ClearArrays
4282   // (see jck test stmt114.stmt11402.val).
4283   if (size <= 0 || size % unit != 0)  return nullptr;
4284   intptr_t count = size / unit;
4285   // Length too long; communicate this to matchers and assemblers.
4286   // Assemblers are responsible to produce fast hardware clears for it.
4287   if (size > InitArrayShortSize) {
4288     return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
4289   } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4290     return nullptr;
4291   }
4292   if (!IdealizeClearArrayNode) return nullptr;
4293   Node *mem = in(1);
4294   if( phase->type(mem)==Type::TOP ) return nullptr;
4295   Node *adr = in(3);
4296   const Type* at = phase->type(adr);
4297   if( at==Type::TOP ) return nullptr;
4298   const TypePtr* atp = at->isa_ptr();
4299   // adjust atp to be the correct array element address type
4300   if (atp == nullptr)  atp = TypePtr::BOTTOM;
4301   else              atp = atp->add_offset(Type::OffsetBot);
4302   // Get base for derived pointer purposes
4303   if( adr->Opcode() != Op_AddP ) Unimplemented();
4304   Node *base = adr->in(1);
4305 
4306   Node *val = in(4);
4307   Node *off  = phase->MakeConX(BytesPerLong);
4308   mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4309   count--;
4310   while( count-- ) {
4311     mem = phase->transform(mem);
4312     adr = phase->transform(new AddPNode(base,adr,off));
4313     mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4314   }
4315   return mem;
4316 }
4317 
4318 //----------------------------step_through----------------------------------
4319 // Return allocation input memory edge if it is different instance
4320 // or itself if it is the one we are looking for.
4321 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4322   Node* n = *np;
4323   assert(n->is_ClearArray(), "sanity");
4324   intptr_t offset;
4325   AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4326   // This method is called only before Allocate nodes are expanded
4327   // during macro nodes expansion. Before that ClearArray nodes are
4328   // only generated in PhaseMacroExpand::generate_arraycopy() (before
4329   // Allocate nodes are expanded) which follows allocations.
4330   assert(alloc != nullptr, "should have allocation");
4331   if (alloc->_idx == instance_id) {
4332     // Can not bypass initialization of the instance we are looking for.
4333     return false;
4334   }
4335   // Otherwise skip it.
4336   InitializeNode* init = alloc->initialization();
4337   if (init != nullptr)
4338     *np = init->in(TypeFunc::Memory);
4339   else
4340     *np = alloc->in(TypeFunc::Memory);
4341   return true;
4342 }
4343 
4344 //----------------------------clear_memory-------------------------------------
4345 // Generate code to initialize object storage to zero.
4346 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4347                                    Node* val,
4348                                    Node* raw_val,
4349                                    intptr_t start_offset,
4350                                    Node* end_offset,
4351                                    PhaseGVN* phase) {
4352   intptr_t offset = start_offset;
4353 
4354   int unit = BytesPerLong;
4355   if ((offset % unit) != 0) {
4356     Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4357     adr = phase->transform(adr);
4358     const TypePtr* atp = TypeRawPtr::BOTTOM;
4359     if (val != nullptr) {
4360       assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4361       mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4362     } else {
4363       assert(raw_val == nullptr, "val may not be null");
4364       mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4365     }
4366     mem = phase->transform(mem);
4367     offset += BytesPerInt;
4368   }
4369   assert((offset % unit) == 0, "");
4370 
4371   // Initialize the remaining stuff, if any, with a ClearArray.
4372   return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
4373 }
4374 
4375 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4376                                    Node* raw_val,
4377                                    Node* start_offset,
4378                                    Node* end_offset,
4379                                    PhaseGVN* phase) {
4380   if (start_offset == end_offset) {
4381     // nothing to do
4382     return mem;
4383   }
4384 
4385   int unit = BytesPerLong;
4386   Node* zbase = start_offset;
4387   Node* zend  = end_offset;
4388 
4389   // Scale to the unit required by the CPU:
4390   if (!Matcher::init_array_count_is_in_bytes) {
4391     Node* shift = phase->intcon(exact_log2(unit));
4392     zbase = phase->transform(new URShiftXNode(zbase, shift) );
4393     zend  = phase->transform(new URShiftXNode(zend,  shift) );
4394   }
4395 
4396   // Bulk clear double-words
4397   Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4398   Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4399   if (raw_val == nullptr) {
4400     raw_val = phase->MakeConX(0);
4401   }
4402   mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
4403   return phase->transform(mem);
4404 }
4405 
4406 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4407                                    Node* val,
4408                                    Node* raw_val,
4409                                    intptr_t start_offset,
4410                                    intptr_t end_offset,
4411                                    PhaseGVN* phase) {
4412   if (start_offset == end_offset) {
4413     // nothing to do
4414     return mem;
4415   }
4416 
4417   assert((end_offset % BytesPerInt) == 0, "odd end offset");
4418   intptr_t done_offset = end_offset;
4419   if ((done_offset % BytesPerLong) != 0) {
4420     done_offset -= BytesPerInt;
4421   }
4422   if (done_offset > start_offset) {
4423     mem = clear_memory(ctl, mem, dest, val, raw_val,
4424                        start_offset, phase->MakeConX(done_offset), phase);
4425   }
4426   if (done_offset < end_offset) { // emit the final 32-bit store
4427     Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4428     adr = phase->transform(adr);
4429     const TypePtr* atp = TypeRawPtr::BOTTOM;
4430     if (val != nullptr) {
4431       assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4432       mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4433     } else {
4434       assert(raw_val == nullptr, "val may not be null");
4435       mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4436     }
4437     mem = phase->transform(mem);
4438     done_offset += BytesPerInt;
4439   }
4440   assert(done_offset == end_offset, "");
4441   return mem;
4442 }
4443 
4444 //=============================================================================
4445 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4446   : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4447     _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4448 #ifdef ASSERT
4449   , _pair_idx(0)
4450 #endif
4451 {
4452   init_class_id(Class_MemBar);
4453   Node* top = C->top();
4454   init_req(TypeFunc::I_O,top);
4455   init_req(TypeFunc::FramePtr,top);
4456   init_req(TypeFunc::ReturnAdr,top);
4457   if (precedent != nullptr)
4458     init_req(TypeFunc::Parms, precedent);
4459 }
4460 
4461 //------------------------------cmp--------------------------------------------
4462 uint MemBarNode::hash() const { return NO_HASH; }
4463 bool MemBarNode::cmp( const Node &n ) const {
4464   return (&n == this);          // Always fail except on self
4465 }
4466 
4467 //------------------------------make-------------------------------------------
4468 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4469   switch (opcode) {
4470   case Op_MemBarAcquire:     return new MemBarAcquireNode(C, atp, pn);
4471   case Op_LoadFence:         return new LoadFenceNode(C, atp, pn);
4472   case Op_MemBarRelease:     return new MemBarReleaseNode(C, atp, pn);
4473   case Op_StoreFence:        return new StoreFenceNode(C, atp, pn);
4474   case Op_MemBarStoreStore:  return new MemBarStoreStoreNode(C, atp, pn);
4475   case Op_StoreStoreFence:   return new StoreStoreFenceNode(C, atp, pn);
4476   case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4477   case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4478   case Op_MemBarVolatile:    return new MemBarVolatileNode(C, atp, pn);
4479   case Op_MemBarCPUOrder:    return new MemBarCPUOrderNode(C, atp, pn);
4480   case Op_OnSpinWait:        return new OnSpinWaitNode(C, atp, pn);
4481   case Op_Initialize:        return new InitializeNode(C, atp, pn);
4482   default: ShouldNotReachHere(); return nullptr;
4483   }
4484 }
4485 
4486 void MemBarNode::remove(PhaseIterGVN *igvn) {
4487   if (outcnt() != 2) {
4488     assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4489     assert(outcnt() == 1, "Only control then");
4490   }
4491   if (trailing_store() || trailing_load_store()) {
4492     MemBarNode* leading = leading_membar();
4493     if (leading != nullptr) {
4494       assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4495       leading->remove(igvn);
4496     }
4497   }
4498   if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4499     igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4500   }
4501   if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4502     igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4503   }
4504 }
4505 
4506 //------------------------------Ideal------------------------------------------
4507 // Return a node which is more "ideal" than the current node.  Strip out
4508 // control copies
4509 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4510   if (remove_dead_region(phase, can_reshape)) return this;
4511   // Don't bother trying to transform a dead node
4512   if (in(0) && in(0)->is_top()) {
4513     return nullptr;
4514   }
4515 
4516   bool progress = false;
4517   // Eliminate volatile MemBars for scalar replaced objects.
4518   if (can_reshape && req() == (Precedent+1)) {
4519     bool eliminate = false;
4520     int opc = Opcode();
4521     if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4522       // Volatile field loads and stores.
4523       Node* my_mem = in(MemBarNode::Precedent);
4524       // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4525       if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4526         // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4527         // replace this Precedent (decodeN) with the Load instead.
4528         if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1))  {
4529           Node* load_node = my_mem->in(1);
4530           set_req(MemBarNode::Precedent, load_node);
4531           phase->is_IterGVN()->_worklist.push(my_mem);
4532           my_mem = load_node;
4533         } else {
4534           assert(my_mem->unique_out() == this, "sanity");
4535           assert(!trailing_load_store(), "load store node can't be eliminated");
4536           del_req(Precedent);
4537           phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4538           my_mem = nullptr;
4539         }
4540         progress = true;
4541       }
4542       if (my_mem != nullptr && my_mem->is_Mem()) {
4543         const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4544         // Check for scalar replaced object reference.
4545         if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4546             t_oop->offset() != Type::OffsetBot &&
4547             t_oop->offset() != Type::OffsetTop) {
4548           eliminate = true;
4549         }
4550       }
4551     } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4552       // Final field stores.
4553       Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4554       if ((alloc != nullptr) && alloc->is_Allocate() &&
4555           alloc->as_Allocate()->does_not_escape_thread()) {
4556         // The allocated object does not escape.
4557         eliminate = true;
4558       }
4559     }
4560     if (eliminate) {
4561       // Replace MemBar projections by its inputs.
4562       PhaseIterGVN* igvn = phase->is_IterGVN();
4563       remove(igvn);
4564       // Must return either the original node (now dead) or a new node
4565       // (Do not return a top here, since that would break the uniqueness of top.)
4566       return new ConINode(TypeInt::ZERO);
4567     }
4568   }
4569   return progress ? this : nullptr;
4570 }
4571 
4572 //------------------------------Value------------------------------------------
4573 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4574   if( !in(0) ) return Type::TOP;
4575   if( phase->type(in(0)) == Type::TOP )
4576     return Type::TOP;
4577   return TypeTuple::MEMBAR;
4578 }
4579 
4580 //------------------------------match------------------------------------------
4581 // Construct projections for memory.
4582 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
4583   switch (proj->_con) {
4584   case TypeFunc::Control:
4585   case TypeFunc::Memory:
4586     return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4587   }
4588   ShouldNotReachHere();
4589   return nullptr;
4590 }
4591 
4592 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4593   trailing->_kind = TrailingStore;
4594   leading->_kind = LeadingStore;
4595 #ifdef ASSERT
4596   trailing->_pair_idx = leading->_idx;
4597   leading->_pair_idx = leading->_idx;
4598 #endif
4599 }
4600 
4601 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4602   trailing->_kind = TrailingLoadStore;
4603   leading->_kind = LeadingLoadStore;
4604 #ifdef ASSERT
4605   trailing->_pair_idx = leading->_idx;
4606   leading->_pair_idx = leading->_idx;
4607 #endif
4608 }
4609 
4610 MemBarNode* MemBarNode::trailing_membar() const {
4611   ResourceMark rm;
4612   Node* trailing = (Node*)this;
4613   VectorSet seen;
4614   Node_Stack multis(0);
4615   do {
4616     Node* c = trailing;
4617     uint i = 0;
4618     do {
4619       trailing = nullptr;
4620       for (; i < c->outcnt(); i++) {
4621         Node* next = c->raw_out(i);
4622         if (next != c && next->is_CFG()) {
4623           if (c->is_MultiBranch()) {
4624             if (multis.node() == c) {
4625               multis.set_index(i+1);
4626             } else {
4627               multis.push(c, i+1);
4628             }
4629           }
4630           trailing = next;
4631           break;
4632         }
4633       }
4634       if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4635         break;
4636       }
4637       while (multis.size() > 0) {
4638         c = multis.node();
4639         i = multis.index();
4640         if (i < c->req()) {
4641           break;
4642         }
4643         multis.pop();
4644       }
4645     } while (multis.size() > 0);
4646   } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4647 
4648   MemBarNode* mb = trailing->as_MemBar();
4649   assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4650          (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4651   assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4652   return mb;
4653 }
4654 
4655 MemBarNode* MemBarNode::leading_membar() const {
4656   ResourceMark rm;
4657   VectorSet seen;
4658   Node_Stack regions(0);
4659   Node* leading = in(0);
4660   while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4661     while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4662       leading = nullptr;
4663       while (regions.size() > 0 && leading == nullptr) {
4664         Node* r = regions.node();
4665         uint i = regions.index();
4666         if (i < r->req()) {
4667           leading = r->in(i);
4668           regions.set_index(i+1);
4669         } else {
4670           regions.pop();
4671         }
4672       }
4673       if (leading == nullptr) {
4674         assert(regions.size() == 0, "all paths should have been tried");
4675         return nullptr;
4676       }
4677     }
4678     if (leading->is_Region()) {
4679       regions.push(leading, 2);
4680       leading = leading->in(1);
4681     } else {
4682       leading = leading->in(0);
4683     }
4684   }
4685 #ifdef ASSERT
4686   Unique_Node_List wq;
4687   wq.push((Node*)this);
4688   uint found = 0;
4689   for (uint i = 0; i < wq.size(); i++) {
4690     Node* n = wq.at(i);
4691     if (n->is_Region()) {
4692       for (uint j = 1; j < n->req(); j++) {
4693         Node* in = n->in(j);
4694         if (in != nullptr && !in->is_top()) {
4695           wq.push(in);
4696         }
4697       }
4698     } else {
4699       if (n->is_MemBar() && n->as_MemBar()->leading()) {
4700         assert(n == leading, "consistency check failed");
4701         found++;
4702       } else {
4703         Node* in = n->in(0);
4704         if (in != nullptr && !in->is_top()) {
4705           wq.push(in);
4706         }
4707       }
4708     }
4709   }
4710   assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4711 #endif
4712   if (leading == nullptr) {
4713     return nullptr;
4714   }
4715   MemBarNode* mb = leading->as_MemBar();
4716   assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4717          (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4718   assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4719   return mb;
4720 }
4721 
4722 
4723 //===========================InitializeNode====================================
4724 // SUMMARY:
4725 // This node acts as a memory barrier on raw memory, after some raw stores.
4726 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4727 // The Initialize can 'capture' suitably constrained stores as raw inits.
4728 // It can coalesce related raw stores into larger units (called 'tiles').
4729 // It can avoid zeroing new storage for memory units which have raw inits.
4730 // At macro-expansion, it is marked 'complete', and does not optimize further.
4731 //
4732 // EXAMPLE:
4733 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4734 //   ctl = incoming control; mem* = incoming memory
4735 // (Note:  A star * on a memory edge denotes I/O and other standard edges.)
4736 // First allocate uninitialized memory and fill in the header:
4737 //   alloc = (Allocate ctl mem* 16 #short[].klass ...)
4738 //   ctl := alloc.Control; mem* := alloc.Memory*
4739 //   rawmem = alloc.Memory; rawoop = alloc.RawAddress
4740 // Then initialize to zero the non-header parts of the raw memory block:
4741 //   init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4742 //   ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4743 // After the initialize node executes, the object is ready for service:
4744 //   oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4745 // Suppose its body is immediately initialized as {1,2}:
4746 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4747 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
4748 //   mem.SLICE(#short[*]) := store2
4749 //
4750 // DETAILS:
4751 // An InitializeNode collects and isolates object initialization after
4752 // an AllocateNode and before the next possible safepoint.  As a
4753 // memory barrier (MemBarNode), it keeps critical stores from drifting
4754 // down past any safepoint or any publication of the allocation.
4755 // Before this barrier, a newly-allocated object may have uninitialized bits.
4756 // After this barrier, it may be treated as a real oop, and GC is allowed.
4757 //
4758 // The semantics of the InitializeNode include an implicit zeroing of
4759 // the new object from object header to the end of the object.
4760 // (The object header and end are determined by the AllocateNode.)
4761 //
4762 // Certain stores may be added as direct inputs to the InitializeNode.
4763 // These stores must update raw memory, and they must be to addresses
4764 // derived from the raw address produced by AllocateNode, and with
4765 // a constant offset.  They must be ordered by increasing offset.
4766 // The first one is at in(RawStores), the last at in(req()-1).
4767 // Unlike most memory operations, they are not linked in a chain,
4768 // but are displayed in parallel as users of the rawmem output of
4769 // the allocation.
4770 //
4771 // (See comments in InitializeNode::capture_store, which continue
4772 // the example given above.)
4773 //
4774 // When the associated Allocate is macro-expanded, the InitializeNode
4775 // may be rewritten to optimize collected stores.  A ClearArrayNode
4776 // may also be created at that point to represent any required zeroing.
4777 // The InitializeNode is then marked 'complete', prohibiting further
4778 // capturing of nearby memory operations.
4779 //
4780 // During macro-expansion, all captured initializations which store
4781 // constant values of 32 bits or smaller are coalesced (if advantageous)
4782 // into larger 'tiles' 32 or 64 bits.  This allows an object to be
4783 // initialized in fewer memory operations.  Memory words which are
4784 // covered by neither tiles nor non-constant stores are pre-zeroed
4785 // by explicit stores of zero.  (The code shape happens to do all
4786 // zeroing first, then all other stores, with both sequences occurring
4787 // in order of ascending offsets.)
4788 //
4789 // Alternatively, code may be inserted between an AllocateNode and its
4790 // InitializeNode, to perform arbitrary initialization of the new object.
4791 // E.g., the object copying intrinsics insert complex data transfers here.
4792 // The initialization must then be marked as 'complete' disable the
4793 // built-in zeroing semantics and the collection of initializing stores.
4794 //
4795 // While an InitializeNode is incomplete, reads from the memory state
4796 // produced by it are optimizable if they match the control edge and
4797 // new oop address associated with the allocation/initialization.
4798 // They return a stored value (if the offset matches) or else zero.
4799 // A write to the memory state, if it matches control and address,
4800 // and if it is to a constant offset, may be 'captured' by the
4801 // InitializeNode.  It is cloned as a raw memory operation and rewired
4802 // inside the initialization, to the raw oop produced by the allocation.
4803 // Operations on addresses which are provably distinct (e.g., to
4804 // other AllocateNodes) are allowed to bypass the initialization.
4805 //
4806 // The effect of all this is to consolidate object initialization
4807 // (both arrays and non-arrays, both piecewise and bulk) into a
4808 // single location, where it can be optimized as a unit.
4809 //
4810 // Only stores with an offset less than TrackedInitializationLimit words
4811 // will be considered for capture by an InitializeNode.  This puts a
4812 // reasonable limit on the complexity of optimized initializations.
4813 
4814 //---------------------------InitializeNode------------------------------------
4815 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4816   : MemBarNode(C, adr_type, rawoop),
4817     _is_complete(Incomplete), _does_not_escape(false)
4818 {
4819   init_class_id(Class_Initialize);
4820 
4821   assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4822   assert(in(RawAddress) == rawoop, "proper init");
4823   // Note:  allocation() can be null, for secondary initialization barriers
4824 }
4825 
4826 // Since this node is not matched, it will be processed by the
4827 // register allocator.  Declare that there are no constraints
4828 // on the allocation of the RawAddress edge.
4829 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4830   // This edge should be set to top, by the set_complete.  But be conservative.
4831   if (idx == InitializeNode::RawAddress)
4832     return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4833   return RegMask::Empty;
4834 }
4835 
4836 Node* InitializeNode::memory(uint alias_idx) {
4837   Node* mem = in(Memory);
4838   if (mem->is_MergeMem()) {
4839     return mem->as_MergeMem()->memory_at(alias_idx);
4840   } else {
4841     // incoming raw memory is not split
4842     return mem;
4843   }
4844 }
4845 
4846 bool InitializeNode::is_non_zero() {
4847   if (is_complete())  return false;
4848   remove_extra_zeroes();
4849   return (req() > RawStores);
4850 }
4851 
4852 void InitializeNode::set_complete(PhaseGVN* phase) {
4853   assert(!is_complete(), "caller responsibility");
4854   _is_complete = Complete;
4855 
4856   // After this node is complete, it contains a bunch of
4857   // raw-memory initializations.  There is no need for
4858   // it to have anything to do with non-raw memory effects.
4859   // Therefore, tell all non-raw users to re-optimize themselves,
4860   // after skipping the memory effects of this initialization.
4861   PhaseIterGVN* igvn = phase->is_IterGVN();
4862   if (igvn)  igvn->add_users_to_worklist(this);
4863 }
4864 
4865 // convenience function
4866 // return false if the init contains any stores already
4867 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4868   InitializeNode* init = initialization();
4869   if (init == nullptr || init->is_complete()) {
4870     return false;
4871   }
4872   init->remove_extra_zeroes();
4873   // for now, if this allocation has already collected any inits, bail:
4874   if (init->is_non_zero())  return false;
4875   init->set_complete(phase);
4876   return true;
4877 }
4878 
4879 void InitializeNode::remove_extra_zeroes() {
4880   if (req() == RawStores)  return;
4881   Node* zmem = zero_memory();
4882   uint fill = RawStores;
4883   for (uint i = fill; i < req(); i++) {
4884     Node* n = in(i);
4885     if (n->is_top() || n == zmem)  continue;  // skip
4886     if (fill < i)  set_req(fill, n);          // compact
4887     ++fill;
4888   }
4889   // delete any empty spaces created:
4890   while (fill < req()) {
4891     del_req(fill);
4892   }
4893 }
4894 
4895 // Helper for remembering which stores go with which offsets.
4896 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4897   if (!st->is_Store())  return -1;  // can happen to dead code via subsume_node
4898   intptr_t offset = -1;
4899   Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4900                                                phase, offset);
4901   if (base == nullptr)  return -1;  // something is dead,
4902   if (offset < 0)       return -1;  //        dead, dead
4903   return offset;
4904 }
4905 
4906 // Helper for proving that an initialization expression is
4907 // "simple enough" to be folded into an object initialization.
4908 // Attempts to prove that a store's initial value 'n' can be captured
4909 // within the initialization without creating a vicious cycle, such as:
4910 //     { Foo p = new Foo(); p.next = p; }
4911 // True for constants and parameters and small combinations thereof.
4912 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4913   ResourceMark rm;
4914   Unique_Node_List worklist;
4915   worklist.push(value);
4916 
4917   uint complexity_limit = 20;
4918   for (uint j = 0; j < worklist.size(); j++) {
4919     if (j >= complexity_limit) {
4920       return false;  // Bail out if processed too many nodes
4921     }
4922 
4923     Node* n = worklist.at(j);
4924     if (n == nullptr)   continue;   // (can this really happen?)
4925     if (n->is_Proj())   n = n->in(0);
4926     if (n == this)      return false;  // found a cycle
4927     if (n->is_Con())    continue;
4928     if (n->is_Start())  continue;   // params, etc., are OK
4929     if (n->is_Root())   continue;   // even better
4930 
4931     // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4932     if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4933       continue;
4934     }
4935 
4936     Node* ctl = n->in(0);
4937     if (ctl != nullptr && !ctl->is_top()) {
4938       if (ctl->is_Proj())  ctl = ctl->in(0);
4939       if (ctl == this)  return false;
4940 
4941       // If we already know that the enclosing memory op is pinned right after
4942       // the init, then any control flow that the store has picked up
4943       // must have preceded the init, or else be equal to the init.
4944       // Even after loop optimizations (which might change control edges)
4945       // a store is never pinned *before* the availability of its inputs.
4946       if (!MemNode::all_controls_dominate(n, this)) {
4947         return false;                  // failed to prove a good control
4948       }
4949     }
4950 
4951     // Check data edges for possible dependencies on 'this'.
4952     for (uint i = 1; i < n->req(); i++) {
4953       Node* m = n->in(i);
4954       if (m == nullptr || m == n || m->is_top())  continue;
4955 
4956       // Only process data inputs once
4957       worklist.push(m);
4958     }
4959   }
4960 
4961   return true;
4962 }
4963 
4964 // Here are all the checks a Store must pass before it can be moved into
4965 // an initialization.  Returns zero if a check fails.
4966 // On success, returns the (constant) offset to which the store applies,
4967 // within the initialized memory.
4968 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4969   const int FAIL = 0;
4970   if (st->req() != MemNode::ValueIn + 1)
4971     return FAIL;                // an inscrutable StoreNode (card mark?)
4972   Node* ctl = st->in(MemNode::Control);
4973   if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4974     return FAIL;                // must be unconditional after the initialization
4975   Node* mem = st->in(MemNode::Memory);
4976   if (!(mem->is_Proj() && mem->in(0) == this))
4977     return FAIL;                // must not be preceded by other stores
4978   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4979   if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4980       !bs->can_initialize_object(st)) {
4981     return FAIL;
4982   }
4983   Node* adr = st->in(MemNode::Address);
4984   intptr_t offset;
4985   AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4986   if (alloc == nullptr)
4987     return FAIL;                // inscrutable address
4988   if (alloc != allocation())
4989     return FAIL;                // wrong allocation!  (store needs to float up)
4990   int size_in_bytes = st->memory_size();
4991   if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4992     return FAIL;                // mismatched access
4993   }
4994   Node* val = st->in(MemNode::ValueIn);
4995 
4996   if (!detect_init_independence(val, phase))
4997     return FAIL;                // stored value must be 'simple enough'
4998 
4999   // The Store can be captured only if nothing after the allocation
5000   // and before the Store is using the memory location that the store
5001   // overwrites.
5002   bool failed = false;
5003   // If is_complete_with_arraycopy() is true the shape of the graph is
5004   // well defined and is safe so no need for extra checks.
5005   if (!is_complete_with_arraycopy()) {
5006     // We are going to look at each use of the memory state following
5007     // the allocation to make sure nothing reads the memory that the
5008     // Store writes.
5009     const TypePtr* t_adr = phase->type(adr)->isa_ptr();
5010     int alias_idx = phase->C->get_alias_index(t_adr);
5011     ResourceMark rm;
5012     Unique_Node_List mems;
5013     mems.push(mem);
5014     Node* unique_merge = nullptr;
5015     for (uint next = 0; next < mems.size(); ++next) {
5016       Node *m  = mems.at(next);
5017       for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
5018         Node *n = m->fast_out(j);
5019         if (n->outcnt() == 0) {
5020           continue;
5021         }
5022         if (n == st) {
5023           continue;
5024         } else if (n->in(0) != nullptr && n->in(0) != ctl) {
5025           // If the control of this use is different from the control
5026           // of the Store which is right after the InitializeNode then
5027           // this node cannot be between the InitializeNode and the
5028           // Store.
5029           continue;
5030         } else if (n->is_MergeMem()) {
5031           if (n->as_MergeMem()->memory_at(alias_idx) == m) {
5032             // We can hit a MergeMemNode (that will likely go away
5033             // later) that is a direct use of the memory state
5034             // following the InitializeNode on the same slice as the
5035             // store node that we'd like to capture. We need to check
5036             // the uses of the MergeMemNode.
5037             mems.push(n);
5038           }
5039         } else if (n->is_Mem()) {
5040           Node* other_adr = n->in(MemNode::Address);
5041           if (other_adr == adr) {
5042             failed = true;
5043             break;
5044           } else {
5045             const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
5046             if (other_t_adr != nullptr) {
5047               int other_alias_idx = phase->C->get_alias_index(other_t_adr);
5048               if (other_alias_idx == alias_idx) {
5049                 // A load from the same memory slice as the store right
5050                 // after the InitializeNode. We check the control of the
5051                 // object/array that is loaded from. If it's the same as
5052                 // the store control then we cannot capture the store.
5053                 assert(!n->is_Store(), "2 stores to same slice on same control?");
5054                 Node* base = other_adr;
5055                 if (base->is_Phi()) {
5056                   // In rare case, base may be a PhiNode and it may read
5057                   // the same memory slice between InitializeNode and store.
5058                   failed = true;
5059                   break;
5060                 }
5061                 assert(base->is_AddP(), "should be addp but is %s", base->Name());
5062                 base = base->in(AddPNode::Base);
5063                 if (base != nullptr) {
5064                   base = base->uncast();
5065                   if (base->is_Proj() && base->in(0) == alloc) {
5066                     failed = true;
5067                     break;
5068                   }
5069                 }
5070               }
5071             }
5072           }
5073         } else {
5074           failed = true;
5075           break;
5076         }
5077       }
5078     }
5079   }
5080   if (failed) {
5081     if (!can_reshape) {
5082       // We decided we couldn't capture the store during parsing. We
5083       // should try again during the next IGVN once the graph is
5084       // cleaner.
5085       phase->C->record_for_igvn(st);
5086     }
5087     return FAIL;
5088   }
5089 
5090   return offset;                // success
5091 }
5092 
5093 // Find the captured store in(i) which corresponds to the range
5094 // [start..start+size) in the initialized object.
5095 // If there is one, return its index i.  If there isn't, return the
5096 // negative of the index where it should be inserted.
5097 // Return 0 if the queried range overlaps an initialization boundary
5098 // or if dead code is encountered.
5099 // If size_in_bytes is zero, do not bother with overlap checks.
5100 int InitializeNode::captured_store_insertion_point(intptr_t start,
5101                                                    int size_in_bytes,
5102                                                    PhaseValues* phase) {
5103   const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
5104 
5105   if (is_complete())
5106     return FAIL;                // arraycopy got here first; punt
5107 
5108   assert(allocation() != nullptr, "must be present");
5109 
5110   // no negatives, no header fields:
5111   if (start < (intptr_t) allocation()->minimum_header_size())  return FAIL;
5112 
5113   // after a certain size, we bail out on tracking all the stores:
5114   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5115   if (start >= ti_limit)  return FAIL;
5116 
5117   for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
5118     if (i >= limit)  return -(int)i; // not found; here is where to put it
5119 
5120     Node*    st     = in(i);
5121     intptr_t st_off = get_store_offset(st, phase);
5122     if (st_off < 0) {
5123       if (st != zero_memory()) {
5124         return FAIL;            // bail out if there is dead garbage
5125       }
5126     } else if (st_off > start) {
5127       // ...we are done, since stores are ordered
5128       if (st_off < start + size_in_bytes) {
5129         return FAIL;            // the next store overlaps
5130       }
5131       return -(int)i;           // not found; here is where to put it
5132     } else if (st_off < start) {
5133       assert(st->as_Store()->memory_size() <= MAX_STORE, "");
5134       if (size_in_bytes != 0 &&
5135           start < st_off + MAX_STORE &&
5136           start < st_off + st->as_Store()->memory_size()) {
5137         return FAIL;            // the previous store overlaps
5138       }
5139     } else {
5140       if (size_in_bytes != 0 &&
5141           st->as_Store()->memory_size() != size_in_bytes) {
5142         return FAIL;            // mismatched store size
5143       }
5144       return i;
5145     }
5146 
5147     ++i;
5148   }
5149 }
5150 
5151 // Look for a captured store which initializes at the offset 'start'
5152 // with the given size.  If there is no such store, and no other
5153 // initialization interferes, then return zero_memory (the memory
5154 // projection of the AllocateNode).
5155 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
5156                                           PhaseValues* phase) {
5157   assert(stores_are_sane(phase), "");
5158   int i = captured_store_insertion_point(start, size_in_bytes, phase);
5159   if (i == 0) {
5160     return nullptr;              // something is dead
5161   } else if (i < 0) {
5162     return zero_memory();       // just primordial zero bits here
5163   } else {
5164     Node* st = in(i);           // here is the store at this position
5165     assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
5166     return st;
5167   }
5168 }
5169 
5170 // Create, as a raw pointer, an address within my new object at 'offset'.
5171 Node* InitializeNode::make_raw_address(intptr_t offset,
5172                                        PhaseGVN* phase) {
5173   Node* addr = in(RawAddress);
5174   if (offset != 0) {
5175     Compile* C = phase->C;
5176     addr = phase->transform( new AddPNode(C->top(), addr,
5177                                                  phase->MakeConX(offset)) );
5178   }
5179   return addr;
5180 }
5181 
5182 // Clone the given store, converting it into a raw store
5183 // initializing a field or element of my new object.
5184 // Caller is responsible for retiring the original store,
5185 // with subsume_node or the like.
5186 //
5187 // From the example above InitializeNode::InitializeNode,
5188 // here are the old stores to be captured:
5189 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
5190 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
5191 //
5192 // Here is the changed code; note the extra edges on init:
5193 //   alloc = (Allocate ...)
5194 //   rawoop = alloc.RawAddress
5195 //   rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
5196 //   rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
5197 //   init = (Initialize alloc.Control alloc.Memory rawoop
5198 //                      rawstore1 rawstore2)
5199 //
5200 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
5201                                     PhaseGVN* phase, bool can_reshape) {
5202   assert(stores_are_sane(phase), "");
5203 
5204   if (start < 0)  return nullptr;
5205   assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
5206 
5207   Compile* C = phase->C;
5208   int size_in_bytes = st->memory_size();
5209   int i = captured_store_insertion_point(start, size_in_bytes, phase);
5210   if (i == 0)  return nullptr;  // bail out
5211   Node* prev_mem = nullptr;     // raw memory for the captured store
5212   if (i > 0) {
5213     prev_mem = in(i);           // there is a pre-existing store under this one
5214     set_req(i, C->top());       // temporarily disconnect it
5215     // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
5216   } else {
5217     i = -i;                     // no pre-existing store
5218     prev_mem = zero_memory();   // a slice of the newly allocated object
5219     if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
5220       set_req(--i, C->top());   // reuse this edge; it has been folded away
5221     else
5222       ins_req(i, C->top());     // build a new edge
5223   }
5224   Node* new_st = st->clone();
5225   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5226   new_st->set_req(MemNode::Control, in(Control));
5227   new_st->set_req(MemNode::Memory,  prev_mem);
5228   new_st->set_req(MemNode::Address, make_raw_address(start, phase));
5229   bs->eliminate_gc_barrier_data(new_st);
5230   new_st = phase->transform(new_st);
5231 
5232   // At this point, new_st might have swallowed a pre-existing store
5233   // at the same offset, or perhaps new_st might have disappeared,
5234   // if it redundantly stored the same value (or zero to fresh memory).
5235 
5236   // In any case, wire it in:
5237   PhaseIterGVN* igvn = phase->is_IterGVN();
5238   if (igvn) {
5239     igvn->rehash_node_delayed(this);
5240   }
5241   set_req(i, new_st);
5242 
5243   // The caller may now kill the old guy.
5244   DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
5245   assert(check_st == new_st || check_st == nullptr, "must be findable");
5246   assert(!is_complete(), "");
5247   return new_st;
5248 }
5249 
5250 static bool store_constant(jlong* tiles, int num_tiles,
5251                            intptr_t st_off, int st_size,
5252                            jlong con) {
5253   if ((st_off & (st_size-1)) != 0)
5254     return false;               // strange store offset (assume size==2**N)
5255   address addr = (address)tiles + st_off;
5256   assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5257   switch (st_size) {
5258   case sizeof(jbyte):  *(jbyte*) addr = (jbyte) con; break;
5259   case sizeof(jchar):  *(jchar*) addr = (jchar) con; break;
5260   case sizeof(jint):   *(jint*)  addr = (jint)  con; break;
5261   case sizeof(jlong):  *(jlong*) addr = (jlong) con; break;
5262   default: return false;        // strange store size (detect size!=2**N here)
5263   }
5264   return true;                  // return success to caller
5265 }
5266 
5267 // Coalesce subword constants into int constants and possibly
5268 // into long constants.  The goal, if the CPU permits,
5269 // is to initialize the object with a small number of 64-bit tiles.
5270 // Also, convert floating-point constants to bit patterns.
5271 // Non-constants are not relevant to this pass.
5272 //
5273 // In terms of the running example on InitializeNode::InitializeNode
5274 // and InitializeNode::capture_store, here is the transformation
5275 // of rawstore1 and rawstore2 into rawstore12:
5276 //   alloc = (Allocate ...)
5277 //   rawoop = alloc.RawAddress
5278 //   tile12 = 0x00010002
5279 //   rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5280 //   init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5281 //
5282 void
5283 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5284                                         Node* size_in_bytes,
5285                                         PhaseGVN* phase) {
5286   Compile* C = phase->C;
5287 
5288   assert(stores_are_sane(phase), "");
5289   // Note:  After this pass, they are not completely sane,
5290   // since there may be some overlaps.
5291 
5292   int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5293 
5294   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5295   intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5296   size_limit = MIN2(size_limit, ti_limit);
5297   size_limit = align_up(size_limit, BytesPerLong);
5298   int num_tiles = size_limit / BytesPerLong;
5299 
5300   // allocate space for the tile map:
5301   const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5302   jlong  tiles_buf[small_len];
5303   Node*  nodes_buf[small_len];
5304   jlong  inits_buf[small_len];
5305   jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5306                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5307   Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5308                   : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5309   jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5310                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5311   // tiles: exact bitwise model of all primitive constants
5312   // nodes: last constant-storing node subsumed into the tiles model
5313   // inits: which bytes (in each tile) are touched by any initializations
5314 
5315   //// Pass A: Fill in the tile model with any relevant stores.
5316 
5317   Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5318   Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5319   Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5320   Node* zmem = zero_memory(); // initially zero memory state
5321   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5322     Node* st = in(i);
5323     intptr_t st_off = get_store_offset(st, phase);
5324 
5325     // Figure out the store's offset and constant value:
5326     if (st_off < header_size)             continue; //skip (ignore header)
5327     if (st->in(MemNode::Memory) != zmem)  continue; //skip (odd store chain)
5328     int st_size = st->as_Store()->memory_size();
5329     if (st_off + st_size > size_limit)    break;
5330 
5331     // Record which bytes are touched, whether by constant or not.
5332     if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5333       continue;                 // skip (strange store size)
5334 
5335     const Type* val = phase->type(st->in(MemNode::ValueIn));
5336     if (!val->singleton())                continue; //skip (non-con store)
5337     BasicType type = val->basic_type();
5338 
5339     jlong con = 0;
5340     switch (type) {
5341     case T_INT:    con = val->is_int()->get_con();  break;
5342     case T_LONG:   con = val->is_long()->get_con(); break;
5343     case T_FLOAT:  con = jint_cast(val->getf());    break;
5344     case T_DOUBLE: con = jlong_cast(val->getd());   break;
5345     default:                              continue; //skip (odd store type)
5346     }
5347 
5348     if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5349         st->Opcode() == Op_StoreL) {
5350       continue;                 // This StoreL is already optimal.
5351     }
5352 
5353     // Store down the constant.
5354     store_constant(tiles, num_tiles, st_off, st_size, con);
5355 
5356     intptr_t j = st_off >> LogBytesPerLong;
5357 
5358     if (type == T_INT && st_size == BytesPerInt
5359         && (st_off & BytesPerInt) == BytesPerInt) {
5360       jlong lcon = tiles[j];
5361       if (!Matcher::isSimpleConstant64(lcon) &&
5362           st->Opcode() == Op_StoreI) {
5363         // This StoreI is already optimal by itself.
5364         jint* intcon = (jint*) &tiles[j];
5365         intcon[1] = 0;  // undo the store_constant()
5366 
5367         // If the previous store is also optimal by itself, back up and
5368         // undo the action of the previous loop iteration... if we can.
5369         // But if we can't, just let the previous half take care of itself.
5370         st = nodes[j];
5371         st_off -= BytesPerInt;
5372         con = intcon[0];
5373         if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5374           assert(st_off >= header_size, "still ignoring header");
5375           assert(get_store_offset(st, phase) == st_off, "must be");
5376           assert(in(i-1) == zmem, "must be");
5377           DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5378           assert(con == tcon->is_int()->get_con(), "must be");
5379           // Undo the effects of the previous loop trip, which swallowed st:
5380           intcon[0] = 0;        // undo store_constant()
5381           set_req(i-1, st);     // undo set_req(i, zmem)
5382           nodes[j] = nullptr;   // undo nodes[j] = st
5383           --old_subword;        // undo ++old_subword
5384         }
5385         continue;               // This StoreI is already optimal.
5386       }
5387     }
5388 
5389     // This store is not needed.
5390     set_req(i, zmem);
5391     nodes[j] = st;              // record for the moment
5392     if (st_size < BytesPerLong) // something has changed
5393           ++old_subword;        // includes int/float, but who's counting...
5394     else  ++old_long;
5395   }
5396 
5397   if ((old_subword + old_long) == 0)
5398     return;                     // nothing more to do
5399 
5400   //// Pass B: Convert any non-zero tiles into optimal constant stores.
5401   // Be sure to insert them before overlapping non-constant stores.
5402   // (E.g., byte[] x = { 1,2,y,4 }  =>  x[int 0] = 0x01020004, x[2]=y.)
5403   for (int j = 0; j < num_tiles; j++) {
5404     jlong con  = tiles[j];
5405     jlong init = inits[j];
5406     if (con == 0)  continue;
5407     jint con0,  con1;           // split the constant, address-wise
5408     jint init0, init1;          // split the init map, address-wise
5409     { union { jlong con; jint intcon[2]; } u;
5410       u.con = con;
5411       con0  = u.intcon[0];
5412       con1  = u.intcon[1];
5413       u.con = init;
5414       init0 = u.intcon[0];
5415       init1 = u.intcon[1];
5416     }
5417 
5418     Node* old = nodes[j];
5419     assert(old != nullptr, "need the prior store");
5420     intptr_t offset = (j * BytesPerLong);
5421 
5422     bool split = !Matcher::isSimpleConstant64(con);
5423 
5424     if (offset < header_size) {
5425       assert(offset + BytesPerInt >= header_size, "second int counts");
5426       assert(*(jint*)&tiles[j] == 0, "junk in header");
5427       split = true;             // only the second word counts
5428       // Example:  int a[] = { 42 ... }
5429     } else if (con0 == 0 && init0 == -1) {
5430       split = true;             // first word is covered by full inits
5431       // Example:  int a[] = { ... foo(), 42 ... }
5432     } else if (con1 == 0 && init1 == -1) {
5433       split = true;             // second word is covered by full inits
5434       // Example:  int a[] = { ... 42, foo() ... }
5435     }
5436 
5437     // Here's a case where init0 is neither 0 nor -1:
5438     //   byte a[] = { ... 0,0,foo(),0,  0,0,0,42 ... }
5439     // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5440     // In this case the tile is not split; it is (jlong)42.
5441     // The big tile is stored down, and then the foo() value is inserted.
5442     // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5443 
5444     Node* ctl = old->in(MemNode::Control);
5445     Node* adr = make_raw_address(offset, phase);
5446     const TypePtr* atp = TypeRawPtr::BOTTOM;
5447 
5448     // One or two coalesced stores to plop down.
5449     Node*    st[2];
5450     intptr_t off[2];
5451     int  nst = 0;
5452     if (!split) {
5453       ++new_long;
5454       off[nst] = offset;
5455       st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5456                                   phase->longcon(con), T_LONG, MemNode::unordered);
5457     } else {
5458       // Omit either if it is a zero.
5459       if (con0 != 0) {
5460         ++new_int;
5461         off[nst]  = offset;
5462         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5463                                     phase->intcon(con0), T_INT, MemNode::unordered);
5464       }
5465       if (con1 != 0) {
5466         ++new_int;
5467         offset += BytesPerInt;
5468         adr = make_raw_address(offset, phase);
5469         off[nst]  = offset;
5470         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5471                                     phase->intcon(con1), T_INT, MemNode::unordered);
5472       }
5473     }
5474 
5475     // Insert second store first, then the first before the second.
5476     // Insert each one just before any overlapping non-constant stores.
5477     while (nst > 0) {
5478       Node* st1 = st[--nst];
5479       C->copy_node_notes_to(st1, old);
5480       st1 = phase->transform(st1);
5481       offset = off[nst];
5482       assert(offset >= header_size, "do not smash header");
5483       int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5484       guarantee(ins_idx != 0, "must re-insert constant store");
5485       if (ins_idx < 0)  ins_idx = -ins_idx;  // never overlap
5486       if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5487         set_req(--ins_idx, st1);
5488       else
5489         ins_req(ins_idx, st1);
5490     }
5491   }
5492 
5493   if (PrintCompilation && WizardMode)
5494     tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5495                   old_subword, old_long, new_int, new_long);
5496   if (C->log() != nullptr)
5497     C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5498                    old_subword, old_long, new_int, new_long);
5499 
5500   // Clean up any remaining occurrences of zmem:
5501   remove_extra_zeroes();
5502 }
5503 
5504 // Explore forward from in(start) to find the first fully initialized
5505 // word, and return its offset.  Skip groups of subword stores which
5506 // together initialize full words.  If in(start) is itself part of a
5507 // fully initialized word, return the offset of in(start).  If there
5508 // are no following full-word stores, or if something is fishy, return
5509 // a negative value.
5510 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5511   int       int_map = 0;
5512   intptr_t  int_map_off = 0;
5513   const int FULL_MAP = right_n_bits(BytesPerInt);  // the int_map we hope for
5514 
5515   for (uint i = start, limit = req(); i < limit; i++) {
5516     Node* st = in(i);
5517 
5518     intptr_t st_off = get_store_offset(st, phase);
5519     if (st_off < 0)  break;  // return conservative answer
5520 
5521     int st_size = st->as_Store()->memory_size();
5522     if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5523       return st_off;            // we found a complete word init
5524     }
5525 
5526     // update the map:
5527 
5528     intptr_t this_int_off = align_down(st_off, BytesPerInt);
5529     if (this_int_off != int_map_off) {
5530       // reset the map:
5531       int_map = 0;
5532       int_map_off = this_int_off;
5533     }
5534 
5535     int subword_off = st_off - this_int_off;
5536     int_map |= right_n_bits(st_size) << subword_off;
5537     if ((int_map & FULL_MAP) == FULL_MAP) {
5538       return this_int_off;      // we found a complete word init
5539     }
5540 
5541     // Did this store hit or cross the word boundary?
5542     intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5543     if (next_int_off == this_int_off + BytesPerInt) {
5544       // We passed the current int, without fully initializing it.
5545       int_map_off = next_int_off;
5546       int_map >>= BytesPerInt;
5547     } else if (next_int_off > this_int_off + BytesPerInt) {
5548       // We passed the current and next int.
5549       return this_int_off + BytesPerInt;
5550     }
5551   }
5552 
5553   return -1;
5554 }
5555 
5556 
5557 // Called when the associated AllocateNode is expanded into CFG.
5558 // At this point, we may perform additional optimizations.
5559 // Linearize the stores by ascending offset, to make memory
5560 // activity as coherent as possible.
5561 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5562                                       intptr_t header_size,
5563                                       Node* size_in_bytes,
5564                                       PhaseIterGVN* phase) {
5565   assert(!is_complete(), "not already complete");
5566   assert(stores_are_sane(phase), "");
5567   assert(allocation() != nullptr, "must be present");
5568 
5569   remove_extra_zeroes();
5570 
5571   if (ReduceFieldZeroing || ReduceBulkZeroing)
5572     // reduce instruction count for common initialization patterns
5573     coalesce_subword_stores(header_size, size_in_bytes, phase);
5574 
5575   Node* zmem = zero_memory();   // initially zero memory state
5576   Node* inits = zmem;           // accumulating a linearized chain of inits
5577   #ifdef ASSERT
5578   intptr_t first_offset = allocation()->minimum_header_size();
5579   intptr_t last_init_off = first_offset;  // previous init offset
5580   intptr_t last_init_end = first_offset;  // previous init offset+size
5581   intptr_t last_tile_end = first_offset;  // previous tile offset+size
5582   #endif
5583   intptr_t zeroes_done = header_size;
5584 
5585   bool do_zeroing = true;       // we might give up if inits are very sparse
5586   int  big_init_gaps = 0;       // how many large gaps have we seen?
5587 
5588   if (UseTLAB && ZeroTLAB)  do_zeroing = false;
5589   if (!ReduceFieldZeroing && !ReduceBulkZeroing)  do_zeroing = false;
5590 
5591   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5592     Node* st = in(i);
5593     intptr_t st_off = get_store_offset(st, phase);
5594     if (st_off < 0)
5595       break;                    // unknown junk in the inits
5596     if (st->in(MemNode::Memory) != zmem)
5597       break;                    // complicated store chains somehow in list
5598 
5599     int st_size = st->as_Store()->memory_size();
5600     intptr_t next_init_off = st_off + st_size;
5601 
5602     if (do_zeroing && zeroes_done < next_init_off) {
5603       // See if this store needs a zero before it or under it.
5604       intptr_t zeroes_needed = st_off;
5605 
5606       if (st_size < BytesPerInt) {
5607         // Look for subword stores which only partially initialize words.
5608         // If we find some, we must lay down some word-level zeroes first,
5609         // underneath the subword stores.
5610         //
5611         // Examples:
5612         //   byte[] a = { p,q,r,s }  =>  a[0]=p,a[1]=q,a[2]=r,a[3]=s
5613         //   byte[] a = { x,y,0,0 }  =>  a[0..3] = 0, a[0]=x,a[1]=y
5614         //   byte[] a = { 0,0,z,0 }  =>  a[0..3] = 0, a[2]=z
5615         //
5616         // Note:  coalesce_subword_stores may have already done this,
5617         // if it was prompted by constant non-zero subword initializers.
5618         // But this case can still arise with non-constant stores.
5619 
5620         intptr_t next_full_store = find_next_fullword_store(i, phase);
5621 
5622         // In the examples above:
5623         //   in(i)          p   q   r   s     x   y     z
5624         //   st_off        12  13  14  15    12  13    14
5625         //   st_size        1   1   1   1     1   1     1
5626         //   next_full_s.  12  16  16  16    16  16    16
5627         //   z's_done      12  16  16  16    12  16    12
5628         //   z's_needed    12  16  16  16    16  16    16
5629         //   zsize          0   0   0   0     4   0     4
5630         if (next_full_store < 0) {
5631           // Conservative tack:  Zero to end of current word.
5632           zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5633         } else {
5634           // Zero to beginning of next fully initialized word.
5635           // Or, don't zero at all, if we are already in that word.
5636           assert(next_full_store >= zeroes_needed, "must go forward");
5637           assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5638           zeroes_needed = next_full_store;
5639         }
5640       }
5641 
5642       if (zeroes_needed > zeroes_done) {
5643         intptr_t zsize = zeroes_needed - zeroes_done;
5644         // Do some incremental zeroing on rawmem, in parallel with inits.
5645         zeroes_done = align_down(zeroes_done, BytesPerInt);
5646         rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5647                                               allocation()->in(AllocateNode::InitValue),
5648                                               allocation()->in(AllocateNode::RawInitValue),
5649                                               zeroes_done, zeroes_needed,
5650                                               phase);
5651         zeroes_done = zeroes_needed;
5652         if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5653           do_zeroing = false;   // leave the hole, next time
5654       }
5655     }
5656 
5657     // Collect the store and move on:
5658     phase->replace_input_of(st, MemNode::Memory, inits);
5659     inits = st;                 // put it on the linearized chain
5660     set_req(i, zmem);           // unhook from previous position
5661 
5662     if (zeroes_done == st_off)
5663       zeroes_done = next_init_off;
5664 
5665     assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5666 
5667     #ifdef ASSERT
5668     // Various order invariants.  Weaker than stores_are_sane because
5669     // a large constant tile can be filled in by smaller non-constant stores.
5670     assert(st_off >= last_init_off, "inits do not reverse");
5671     last_init_off = st_off;
5672     const Type* val = nullptr;
5673     if (st_size >= BytesPerInt &&
5674         (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5675         (int)val->basic_type() < (int)T_OBJECT) {
5676       assert(st_off >= last_tile_end, "tiles do not overlap");
5677       assert(st_off >= last_init_end, "tiles do not overwrite inits");
5678       last_tile_end = MAX2(last_tile_end, next_init_off);
5679     } else {
5680       intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5681       assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5682       assert(st_off      >= last_init_end, "inits do not overlap");
5683       last_init_end = next_init_off;  // it's a non-tile
5684     }
5685     #endif //ASSERT
5686   }
5687 
5688   remove_extra_zeroes();        // clear out all the zmems left over
5689   add_req(inits);
5690 
5691   if (!(UseTLAB && ZeroTLAB)) {
5692     // If anything remains to be zeroed, zero it all now.
5693     zeroes_done = align_down(zeroes_done, BytesPerInt);
5694     // if it is the last unused 4 bytes of an instance, forget about it
5695     intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5696     if (zeroes_done + BytesPerLong >= size_limit) {
5697       AllocateNode* alloc = allocation();
5698       assert(alloc != nullptr, "must be present");
5699       if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5700         Node* klass_node = alloc->in(AllocateNode::KlassNode);
5701         ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5702         if (zeroes_done == k->layout_helper())
5703           zeroes_done = size_limit;
5704       }
5705     }
5706     if (zeroes_done < size_limit) {
5707       rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5708                                             allocation()->in(AllocateNode::InitValue),
5709                                             allocation()->in(AllocateNode::RawInitValue),
5710                                             zeroes_done, size_in_bytes, phase);
5711     }
5712   }
5713 
5714   set_complete(phase);
5715   return rawmem;
5716 }
5717 
5718 
5719 #ifdef ASSERT
5720 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5721   if (is_complete())
5722     return true;                // stores could be anything at this point
5723   assert(allocation() != nullptr, "must be present");
5724   intptr_t last_off = allocation()->minimum_header_size();
5725   for (uint i = InitializeNode::RawStores; i < req(); i++) {
5726     Node* st = in(i);
5727     intptr_t st_off = get_store_offset(st, phase);
5728     if (st_off < 0)  continue;  // ignore dead garbage
5729     if (last_off > st_off) {
5730       tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5731       this->dump(2);
5732       assert(false, "ascending store offsets");
5733       return false;
5734     }
5735     last_off = st_off + st->as_Store()->memory_size();
5736   }
5737   return true;
5738 }
5739 #endif //ASSERT
5740 
5741 
5742 
5743 
5744 //============================MergeMemNode=====================================
5745 //
5746 // SEMANTICS OF MEMORY MERGES:  A MergeMem is a memory state assembled from several
5747 // contributing store or call operations.  Each contributor provides the memory
5748 // state for a particular "alias type" (see Compile::alias_type).  For example,
5749 // if a MergeMem has an input X for alias category #6, then any memory reference
5750 // to alias category #6 may use X as its memory state input, as an exact equivalent
5751 // to using the MergeMem as a whole.
5752 //   Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5753 //
5754 // (Here, the <N> notation gives the index of the relevant adr_type.)
5755 //
5756 // In one special case (and more cases in the future), alias categories overlap.
5757 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5758 // states.  Therefore, if a MergeMem has only one contributing input W for Bot,
5759 // it is exactly equivalent to that state W:
5760 //   MergeMem(<Bot>: W) <==> W
5761 //
5762 // Usually, the merge has more than one input.  In that case, where inputs
5763 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5764 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5765 //   Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5766 //   Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5767 //
5768 // A merge can take a "wide" memory state as one of its narrow inputs.
5769 // This simply means that the merge observes out only the relevant parts of
5770 // the wide input.  That is, wide memory states arriving at narrow merge inputs
5771 // are implicitly "filtered" or "sliced" as necessary.  (This is rare.)
5772 //
5773 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5774 // and that memory slices "leak through":
5775 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5776 //
5777 // But, in such a cascade, repeated memory slices can "block the leak":
5778 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5779 //
5780 // In the last example, Y is not part of the combined memory state of the
5781 // outermost MergeMem.  The system must, of course, prevent unschedulable
5782 // memory states from arising, so you can be sure that the state Y is somehow
5783 // a precursor to state Y'.
5784 //
5785 //
5786 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5787 // of each MergeMemNode array are exactly the numerical alias indexes, including
5788 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw.  The functions
5789 // Compile::alias_type (and kin) produce and manage these indexes.
5790 //
5791 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5792 // (Note that this provides quick access to the top node inside MergeMem methods,
5793 // without the need to reach out via TLS to Compile::current.)
5794 //
5795 // As a consequence of what was just described, a MergeMem that represents a full
5796 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5797 // containing all alias categories.
5798 //
5799 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5800 //
5801 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5802 // a memory state for the alias type <N>, or else the top node, meaning that
5803 // there is no particular input for that alias type.  Note that the length of
5804 // a MergeMem is variable, and may be extended at any time to accommodate new
5805 // memory states at larger alias indexes.  When merges grow, they are of course
5806 // filled with "top" in the unused in() positions.
5807 //
5808 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5809 // (Top was chosen because it works smoothly with passes like GCM.)
5810 //
5811 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM.  (It is
5812 // the type of random VM bits like TLS references.)  Since it is always the
5813 // first non-Bot memory slice, some low-level loops use it to initialize an
5814 // index variable:  for (i = AliasIdxRaw; i < req(); i++).
5815 //
5816 //
5817 // ACCESSORS:  There is a special accessor MergeMemNode::base_memory which returns
5818 // the distinguished "wide" state.  The accessor MergeMemNode::memory_at(N) returns
5819 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5820 // it returns the base memory.  To prevent bugs, memory_at does not accept <Top>
5821 // or <Bot> indexes.  The iterator MergeMemStream provides robust iteration over
5822 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5823 //
5824 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5825 // really that different from the other memory inputs.  An abbreviation called
5826 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5827 //
5828 //
5829 // PARTIAL MEMORY STATES:  During optimization, MergeMem nodes may arise that represent
5830 // partial memory states.  When a Phi splits through a MergeMem, the copy of the Phi
5831 // that "emerges though" the base memory will be marked as excluding the alias types
5832 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5833 //
5834 //   Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5835 //     ==Ideal=>  MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5836 //
5837 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5838 // (It is currently unimplemented.)  As you can see, the resulting merge is
5839 // actually a disjoint union of memory states, rather than an overlay.
5840 //
5841 
5842 //------------------------------MergeMemNode-----------------------------------
5843 Node* MergeMemNode::make_empty_memory() {
5844   Node* empty_memory = (Node*) Compile::current()->top();
5845   assert(empty_memory->is_top(), "correct sentinel identity");
5846   return empty_memory;
5847 }
5848 
5849 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5850   init_class_id(Class_MergeMem);
5851   // all inputs are nullified in Node::Node(int)
5852   // set_input(0, nullptr);  // no control input
5853 
5854   // Initialize the edges uniformly to top, for starters.
5855   Node* empty_mem = make_empty_memory();
5856   for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5857     init_req(i,empty_mem);
5858   }
5859   assert(empty_memory() == empty_mem, "");
5860 
5861   if( new_base != nullptr && new_base->is_MergeMem() ) {
5862     MergeMemNode* mdef = new_base->as_MergeMem();
5863     assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5864     for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5865       mms.set_memory(mms.memory2());
5866     }
5867     assert(base_memory() == mdef->base_memory(), "");
5868   } else {
5869     set_base_memory(new_base);
5870   }
5871 }
5872 
5873 // Make a new, untransformed MergeMem with the same base as 'mem'.
5874 // If mem is itself a MergeMem, populate the result with the same edges.
5875 MergeMemNode* MergeMemNode::make(Node* mem) {
5876   return new MergeMemNode(mem);
5877 }
5878 
5879 //------------------------------cmp--------------------------------------------
5880 uint MergeMemNode::hash() const { return NO_HASH; }
5881 bool MergeMemNode::cmp( const Node &n ) const {
5882   return (&n == this);          // Always fail except on self
5883 }
5884 
5885 //------------------------------Identity---------------------------------------
5886 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5887   // Identity if this merge point does not record any interesting memory
5888   // disambiguations.
5889   Node* base_mem = base_memory();
5890   Node* empty_mem = empty_memory();
5891   if (base_mem != empty_mem) {  // Memory path is not dead?
5892     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5893       Node* mem = in(i);
5894       if (mem != empty_mem && mem != base_mem) {
5895         return this;            // Many memory splits; no change
5896       }
5897     }
5898   }
5899   return base_mem;              // No memory splits; ID on the one true input
5900 }
5901 
5902 //------------------------------Ideal------------------------------------------
5903 // This method is invoked recursively on chains of MergeMem nodes
5904 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5905   // Remove chain'd MergeMems
5906   //
5907   // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5908   // relative to the "in(Bot)".  Since we are patching both at the same time,
5909   // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5910   // but rewrite each "in(i)" relative to the new "in(Bot)".
5911   Node *progress = nullptr;
5912 
5913 
5914   Node* old_base = base_memory();
5915   Node* empty_mem = empty_memory();
5916   if (old_base == empty_mem)
5917     return nullptr; // Dead memory path.
5918 
5919   MergeMemNode* old_mbase;
5920   if (old_base != nullptr && old_base->is_MergeMem())
5921     old_mbase = old_base->as_MergeMem();
5922   else
5923     old_mbase = nullptr;
5924   Node* new_base = old_base;
5925 
5926   // simplify stacked MergeMems in base memory
5927   if (old_mbase)  new_base = old_mbase->base_memory();
5928 
5929   // the base memory might contribute new slices beyond my req()
5930   if (old_mbase)  grow_to_match(old_mbase);
5931 
5932   // Note:  We do not call verify_sparse on entry, because inputs
5933   // can normalize to the base_memory via subsume_node or similar
5934   // mechanisms.  This method repairs that damage.
5935 
5936   assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5937 
5938   // Look at each slice.
5939   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5940     Node* old_in = in(i);
5941     // calculate the old memory value
5942     Node* old_mem = old_in;
5943     if (old_mem == empty_mem)  old_mem = old_base;
5944     assert(old_mem == memory_at(i), "");
5945 
5946     // maybe update (reslice) the old memory value
5947 
5948     // simplify stacked MergeMems
5949     Node* new_mem = old_mem;
5950     MergeMemNode* old_mmem;
5951     if (old_mem != nullptr && old_mem->is_MergeMem())
5952       old_mmem = old_mem->as_MergeMem();
5953     else
5954       old_mmem = nullptr;
5955     if (old_mmem == this) {
5956       // This can happen if loops break up and safepoints disappear.
5957       // A merge of BotPtr (default) with a RawPtr memory derived from a
5958       // safepoint can be rewritten to a merge of the same BotPtr with
5959       // the BotPtr phi coming into the loop.  If that phi disappears
5960       // also, we can end up with a self-loop of the mergemem.
5961       // In general, if loops degenerate and memory effects disappear,
5962       // a mergemem can be left looking at itself.  This simply means
5963       // that the mergemem's default should be used, since there is
5964       // no longer any apparent effect on this slice.
5965       // Note: If a memory slice is a MergeMem cycle, it is unreachable
5966       //       from start.  Update the input to TOP.
5967       new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5968     }
5969     else if (old_mmem != nullptr) {
5970       new_mem = old_mmem->memory_at(i);
5971     }
5972     // else preceding memory was not a MergeMem
5973 
5974     // maybe store down a new value
5975     Node* new_in = new_mem;
5976     if (new_in == new_base)  new_in = empty_mem;
5977 
5978     if (new_in != old_in) {
5979       // Warning:  Do not combine this "if" with the previous "if"
5980       // A memory slice might have be be rewritten even if it is semantically
5981       // unchanged, if the base_memory value has changed.
5982       set_req_X(i, new_in, phase);
5983       progress = this;          // Report progress
5984     }
5985   }
5986 
5987   if (new_base != old_base) {
5988     set_req_X(Compile::AliasIdxBot, new_base, phase);
5989     // Don't use set_base_memory(new_base), because we need to update du.
5990     assert(base_memory() == new_base, "");
5991     progress = this;
5992   }
5993 
5994   if( base_memory() == this ) {
5995     // a self cycle indicates this memory path is dead
5996     set_req(Compile::AliasIdxBot, empty_mem);
5997   }
5998 
5999   // Resolve external cycles by calling Ideal on a MergeMem base_memory
6000   // Recursion must occur after the self cycle check above
6001   if( base_memory()->is_MergeMem() ) {
6002     MergeMemNode *new_mbase = base_memory()->as_MergeMem();
6003     Node *m = phase->transform(new_mbase);  // Rollup any cycles
6004     if( m != nullptr &&
6005         (m->is_top() ||
6006          (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
6007       // propagate rollup of dead cycle to self
6008       set_req(Compile::AliasIdxBot, empty_mem);
6009     }
6010   }
6011 
6012   if( base_memory() == empty_mem ) {
6013     progress = this;
6014     // Cut inputs during Parse phase only.
6015     // During Optimize phase a dead MergeMem node will be subsumed by Top.
6016     if( !can_reshape ) {
6017       for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6018         if( in(i) != empty_mem ) { set_req(i, empty_mem); }
6019       }
6020     }
6021   }
6022 
6023   if( !progress && base_memory()->is_Phi() && can_reshape ) {
6024     // Check if PhiNode::Ideal's "Split phis through memory merges"
6025     // transform should be attempted. Look for this->phi->this cycle.
6026     uint merge_width = req();
6027     if (merge_width > Compile::AliasIdxRaw) {
6028       PhiNode* phi = base_memory()->as_Phi();
6029       for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
6030         if (phi->in(i) == this) {
6031           phase->is_IterGVN()->_worklist.push(phi);
6032           break;
6033         }
6034       }
6035     }
6036   }
6037 
6038   assert(progress || verify_sparse(), "please, no dups of base");
6039   return progress;
6040 }
6041 
6042 //-------------------------set_base_memory-------------------------------------
6043 void MergeMemNode::set_base_memory(Node *new_base) {
6044   Node* empty_mem = empty_memory();
6045   set_req(Compile::AliasIdxBot, new_base);
6046   assert(memory_at(req()) == new_base, "must set default memory");
6047   // Clear out other occurrences of new_base:
6048   if (new_base != empty_mem) {
6049     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6050       if (in(i) == new_base)  set_req(i, empty_mem);
6051     }
6052   }
6053 }
6054 
6055 //------------------------------out_RegMask------------------------------------
6056 const RegMask &MergeMemNode::out_RegMask() const {
6057   return RegMask::Empty;
6058 }
6059 
6060 //------------------------------dump_spec--------------------------------------
6061 #ifndef PRODUCT
6062 void MergeMemNode::dump_spec(outputStream *st) const {
6063   st->print(" {");
6064   Node* base_mem = base_memory();
6065   for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
6066     Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
6067     if (mem == base_mem) { st->print(" -"); continue; }
6068     st->print( " N%d:", mem->_idx );
6069     Compile::current()->get_adr_type(i)->dump_on(st);
6070   }
6071   st->print(" }");
6072 }
6073 #endif // !PRODUCT
6074 
6075 
6076 #ifdef ASSERT
6077 static bool might_be_same(Node* a, Node* b) {
6078   if (a == b)  return true;
6079   if (!(a->is_Phi() || b->is_Phi()))  return false;
6080   // phis shift around during optimization
6081   return true;  // pretty stupid...
6082 }
6083 
6084 // verify a narrow slice (either incoming or outgoing)
6085 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
6086   if (!VerifyAliases)                return;  // don't bother to verify unless requested
6087   if (VMError::is_error_reported())  return;  // muzzle asserts when debugging an error
6088   if (Node::in_dump())               return;  // muzzle asserts when printing
6089   assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
6090   assert(n != nullptr, "");
6091   // Elide intervening MergeMem's
6092   while (n->is_MergeMem()) {
6093     n = n->as_MergeMem()->memory_at(alias_idx);
6094   }
6095   Compile* C = Compile::current();
6096   const TypePtr* n_adr_type = n->adr_type();
6097   if (n == m->empty_memory()) {
6098     // Implicit copy of base_memory()
6099   } else if (n_adr_type != TypePtr::BOTTOM) {
6100     assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
6101     assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
6102   } else {
6103     // A few places like make_runtime_call "know" that VM calls are narrow,
6104     // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
6105     bool expected_wide_mem = false;
6106     if (n == m->base_memory()) {
6107       expected_wide_mem = true;
6108     } else if (alias_idx == Compile::AliasIdxRaw ||
6109                n == m->memory_at(Compile::AliasIdxRaw)) {
6110       expected_wide_mem = true;
6111     } else if (!C->alias_type(alias_idx)->is_rewritable()) {
6112       // memory can "leak through" calls on channels that
6113       // are write-once.  Allow this also.
6114       expected_wide_mem = true;
6115     }
6116     assert(expected_wide_mem, "expected narrow slice replacement");
6117   }
6118 }
6119 #else // !ASSERT
6120 #define verify_memory_slice(m,i,n) (void)(0)  // PRODUCT version is no-op
6121 #endif
6122 
6123 
6124 //-----------------------------memory_at---------------------------------------
6125 Node* MergeMemNode::memory_at(uint alias_idx) const {
6126   assert(alias_idx >= Compile::AliasIdxRaw ||
6127          (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
6128          "must avoid base_memory and AliasIdxTop");
6129 
6130   // Otherwise, it is a narrow slice.
6131   Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
6132   if (is_empty_memory(n)) {
6133     // the array is sparse; empty slots are the "top" node
6134     n = base_memory();
6135     assert(Node::in_dump()
6136            || n == nullptr || n->bottom_type() == Type::TOP
6137            || n->adr_type() == nullptr // address is TOP
6138            || n->adr_type() == TypePtr::BOTTOM
6139            || n->adr_type() == TypeRawPtr::BOTTOM
6140            || !Compile::current()->do_aliasing(),
6141            "must be a wide memory");
6142     // do_aliasing == false if we are organizing the memory states manually.
6143     // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
6144   } else {
6145     // make sure the stored slice is sane
6146     #ifdef ASSERT
6147     if (VMError::is_error_reported() || Node::in_dump()) {
6148     } else if (might_be_same(n, base_memory())) {
6149       // Give it a pass:  It is a mostly harmless repetition of the base.
6150       // This can arise normally from node subsumption during optimization.
6151     } else {
6152       verify_memory_slice(this, alias_idx, n);
6153     }
6154     #endif
6155   }
6156   return n;
6157 }
6158 
6159 //---------------------------set_memory_at-------------------------------------
6160 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
6161   verify_memory_slice(this, alias_idx, n);
6162   Node* empty_mem = empty_memory();
6163   if (n == base_memory())  n = empty_mem;  // collapse default
6164   uint need_req = alias_idx+1;
6165   if (req() < need_req) {
6166     if (n == empty_mem)  return;  // already the default, so do not grow me
6167     // grow the sparse array
6168     do {
6169       add_req(empty_mem);
6170     } while (req() < need_req);
6171   }
6172   set_req( alias_idx, n );
6173 }
6174 
6175 
6176 
6177 //--------------------------iteration_setup------------------------------------
6178 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
6179   if (other != nullptr) {
6180     grow_to_match(other);
6181     // invariant:  the finite support of mm2 is within mm->req()
6182     #ifdef ASSERT
6183     for (uint i = req(); i < other->req(); i++) {
6184       assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
6185     }
6186     #endif
6187   }
6188   // Replace spurious copies of base_memory by top.
6189   Node* base_mem = base_memory();
6190   if (base_mem != nullptr && !base_mem->is_top()) {
6191     for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
6192       if (in(i) == base_mem)
6193         set_req(i, empty_memory());
6194     }
6195   }
6196 }
6197 
6198 //---------------------------grow_to_match-------------------------------------
6199 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
6200   Node* empty_mem = empty_memory();
6201   assert(other->is_empty_memory(empty_mem), "consistent sentinels");
6202   // look for the finite support of the other memory
6203   for (uint i = other->req(); --i >= req(); ) {
6204     if (other->in(i) != empty_mem) {
6205       uint new_len = i+1;
6206       while (req() < new_len)  add_req(empty_mem);
6207       break;
6208     }
6209   }
6210 }
6211 
6212 //---------------------------verify_sparse-------------------------------------
6213 #ifndef PRODUCT
6214 bool MergeMemNode::verify_sparse() const {
6215   assert(is_empty_memory(make_empty_memory()), "sane sentinel");
6216   Node* base_mem = base_memory();
6217   // The following can happen in degenerate cases, since empty==top.
6218   if (is_empty_memory(base_mem))  return true;
6219   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6220     assert(in(i) != nullptr, "sane slice");
6221     if (in(i) == base_mem)  return false;  // should have been the sentinel value!
6222   }
6223   return true;
6224 }
6225 
6226 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
6227   Node* n;
6228   n = mm->in(idx);
6229   if (mem == n)  return true;  // might be empty_memory()
6230   n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
6231   if (mem == n)  return true;
6232   return false;
6233 }
6234 #endif // !PRODUCT