1 /*
   2  * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/javaClasses.hpp"
  27 #include "compiler/compileLog.hpp"
  28 #include "gc/shared/barrierSet.hpp"
  29 #include "gc/shared/c2/barrierSetC2.hpp"
  30 #include "gc/shared/tlab_globals.hpp"
  31 #include "memory/allocation.inline.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "oops/objArrayKlass.hpp"
  34 #include "opto/addnode.hpp"
  35 #include "opto/arraycopynode.hpp"
  36 #include "opto/cfgnode.hpp"
  37 #include "opto/regalloc.hpp"
  38 #include "opto/compile.hpp"
  39 #include "opto/connode.hpp"
  40 #include "opto/convertnode.hpp"
  41 #include "opto/loopnode.hpp"
  42 #include "opto/machnode.hpp"
  43 #include "opto/matcher.hpp"
  44 #include "opto/memnode.hpp"
  45 #include "opto/mulnode.hpp"
  46 #include "opto/narrowptrnode.hpp"
  47 #include "opto/phaseX.hpp"
  48 #include "opto/regmask.hpp"
  49 #include "opto/rootnode.hpp"
  50 #include "opto/vectornode.hpp"
  51 #include "utilities/align.hpp"
  52 #include "utilities/copy.hpp"
  53 #include "utilities/macros.hpp"
  54 #include "utilities/powerOfTwo.hpp"
  55 #include "utilities/vmError.hpp"
  56 
  57 // Portions of code courtesy of Clifford Click
  58 
  59 // Optimization - Graph Style
  60 
  61 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem,  const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
  62 
  63 //=============================================================================
  64 uint MemNode::size_of() const { return sizeof(*this); }
  65 
  66 const TypePtr *MemNode::adr_type() const {
  67   Node* adr = in(Address);
  68   if (adr == nullptr)  return nullptr; // node is dead
  69   const TypePtr* cross_check = nullptr;
  70   DEBUG_ONLY(cross_check = _adr_type);
  71   return calculate_adr_type(adr->bottom_type(), cross_check);
  72 }
  73 
  74 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
  75   if (adr != nullptr) {
  76     if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
  77       return true;
  78     }
  79   }
  80   return false;
  81 }
  82 
  83 #ifndef PRODUCT
  84 void MemNode::dump_spec(outputStream *st) const {
  85   if (in(Address) == nullptr)  return; // node is dead
  86 #ifndef ASSERT
  87   // fake the missing field
  88   const TypePtr* _adr_type = nullptr;
  89   if (in(Address) != nullptr)
  90     _adr_type = in(Address)->bottom_type()->isa_ptr();
  91 #endif
  92   dump_adr_type(this, _adr_type, st);
  93 
  94   Compile* C = Compile::current();
  95   if (C->alias_type(_adr_type)->is_volatile()) {
  96     st->print(" Volatile!");
  97   }
  98   if (_unaligned_access) {
  99     st->print(" unaligned");
 100   }
 101   if (_mismatched_access) {
 102     st->print(" mismatched");
 103   }
 104   if (_unsafe_access) {
 105     st->print(" unsafe");
 106   }
 107 }
 108 
 109 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
 110   st->print(" @");
 111   if (adr_type == nullptr) {
 112     st->print("null");
 113   } else {
 114     adr_type->dump_on(st);
 115     Compile* C = Compile::current();
 116     Compile::AliasType* atp = nullptr;
 117     if (C->have_alias_type(adr_type))  atp = C->alias_type(adr_type);
 118     if (atp == nullptr)
 119       st->print(", idx=?\?;");
 120     else if (atp->index() == Compile::AliasIdxBot)
 121       st->print(", idx=Bot;");
 122     else if (atp->index() == Compile::AliasIdxTop)
 123       st->print(", idx=Top;");
 124     else if (atp->index() == Compile::AliasIdxRaw)
 125       st->print(", idx=Raw;");
 126     else {
 127       ciField* field = atp->field();
 128       if (field) {
 129         st->print(", name=");
 130         field->print_name_on(st);
 131       }
 132       st->print(", idx=%d;", atp->index());
 133     }
 134   }
 135 }
 136 
 137 extern void print_alias_types();
 138 
 139 #endif
 140 
 141 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
 142   assert((t_oop != nullptr), "sanity");
 143   bool is_instance = t_oop->is_known_instance_field();
 144   bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
 145                              (load != nullptr) && load->is_Load() &&
 146                              (phase->is_IterGVN() != nullptr);
 147   if (!(is_instance || is_boxed_value_load))
 148     return mchain;  // don't try to optimize non-instance types
 149   uint instance_id = t_oop->instance_id();
 150   Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
 151   Node *prev = nullptr;
 152   Node *result = mchain;
 153   while (prev != result) {
 154     prev = result;
 155     if (result == start_mem)
 156       break;  // hit one of our sentinels
 157     // skip over a call which does not affect this memory slice
 158     if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
 159       Node *proj_in = result->in(0);
 160       if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
 161         break;  // hit one of our sentinels
 162       } else if (proj_in->is_Call()) {
 163         // ArrayCopyNodes processed here as well
 164         CallNode *call = proj_in->as_Call();
 165         if (!call->may_modify(t_oop, phase)) { // returns false for instances
 166           result = call->in(TypeFunc::Memory);
 167         }
 168       } else if (proj_in->is_Initialize()) {
 169         AllocateNode* alloc = proj_in->as_Initialize()->allocation();
 170         // Stop if this is the initialization for the object instance which
 171         // contains this memory slice, otherwise skip over it.
 172         if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
 173           break;
 174         }
 175         if (is_instance) {
 176           result = proj_in->in(TypeFunc::Memory);
 177         } else if (is_boxed_value_load) {
 178           Node* klass = alloc->in(AllocateNode::KlassNode);
 179           const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
 180           if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
 181             result = proj_in->in(TypeFunc::Memory); // not related allocation
 182           }
 183         }
 184       } else if (proj_in->is_MemBar()) {
 185         ArrayCopyNode* ac = nullptr;
 186         if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
 187           break;
 188         }
 189         result = proj_in->in(TypeFunc::Memory);
 190       } else if (proj_in->is_top()) {
 191         break; // dead code
 192       } else {
 193         assert(false, "unexpected projection");
 194       }
 195     } else if (result->is_ClearArray()) {
 196       if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
 197         // Can not bypass initialization of the instance
 198         // we are looking for.
 199         break;
 200       }
 201       // Otherwise skip it (the call updated 'result' value).
 202     } else if (result->is_MergeMem()) {
 203       result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
 204     }
 205   }
 206   return result;
 207 }
 208 
 209 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
 210   const TypeOopPtr* t_oop = t_adr->isa_oopptr();
 211   if (t_oop == nullptr)
 212     return mchain;  // don't try to optimize non-oop types
 213   Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
 214   bool is_instance = t_oop->is_known_instance_field();
 215   PhaseIterGVN *igvn = phase->is_IterGVN();
 216   if (is_instance && igvn != nullptr && result->is_Phi()) {
 217     PhiNode *mphi = result->as_Phi();
 218     assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
 219     const TypePtr *t = mphi->adr_type();
 220     bool do_split = false;
 221     // In the following cases, Load memory input can be further optimized based on
 222     // its precise address type
 223     if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
 224       do_split = true;
 225     } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
 226       const TypeOopPtr* mem_t =
 227         t->is_oopptr()->cast_to_exactness(true)
 228         ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
 229         ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
 230       if (t_oop->isa_aryptr()) {
 231         mem_t = mem_t->is_aryptr()
 232                      ->cast_to_stable(t_oop->is_aryptr()->is_stable())
 233                      ->cast_to_size(t_oop->is_aryptr()->size())
 234                      ->with_offset(t_oop->is_aryptr()->offset())
 235                      ->is_aryptr();
 236       }
 237       do_split = mem_t == t_oop;
 238     }
 239     if (do_split) {
 240       // clone the Phi with our address type
 241       result = mphi->split_out_instance(t_adr, igvn);
 242     } else {
 243       assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
 244     }
 245   }
 246   return result;
 247 }
 248 
 249 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem,  const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
 250   uint alias_idx = phase->C->get_alias_index(tp);
 251   Node *mem = mmem;
 252 #ifdef ASSERT
 253   {
 254     // Check that current type is consistent with the alias index used during graph construction
 255     assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
 256     bool consistent =  adr_check == nullptr || adr_check->empty() ||
 257                        phase->C->must_alias(adr_check, alias_idx );
 258     // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
 259     if( !consistent && adr_check != nullptr && !adr_check->empty() &&
 260                tp->isa_aryptr() &&        tp->offset() == Type::OffsetBot &&
 261         adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
 262         ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
 263           adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
 264           adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
 265       // don't assert if it is dead code.
 266       consistent = true;
 267     }
 268     if( !consistent ) {
 269       st->print("alias_idx==%d, adr_check==", alias_idx);
 270       if( adr_check == nullptr ) {
 271         st->print("null");
 272       } else {
 273         adr_check->dump();
 274       }
 275       st->cr();
 276       print_alias_types();
 277       assert(consistent, "adr_check must match alias idx");
 278     }
 279   }
 280 #endif
 281   // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
 282   // means an array I have not precisely typed yet.  Do not do any
 283   // alias stuff with it any time soon.
 284   const TypeOopPtr *toop = tp->isa_oopptr();
 285   if (tp->base() != Type::AnyPtr &&
 286       !(toop &&
 287         toop->isa_instptr() &&
 288         toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
 289         toop->offset() == Type::OffsetBot)) {
 290     // compress paths and change unreachable cycles to TOP
 291     // If not, we can update the input infinitely along a MergeMem cycle
 292     // Equivalent code in PhiNode::Ideal
 293     Node* m  = phase->transform(mmem);
 294     // If transformed to a MergeMem, get the desired slice
 295     // Otherwise the returned node represents memory for every slice
 296     mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
 297     // Update input if it is progress over what we have now
 298   }
 299   return mem;
 300 }
 301 
 302 //--------------------------Ideal_common---------------------------------------
 303 // Look for degenerate control and memory inputs.  Bypass MergeMem inputs.
 304 // Unhook non-raw memories from complete (macro-expanded) initializations.
 305 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
 306   // If our control input is a dead region, kill all below the region
 307   Node *ctl = in(MemNode::Control);
 308   if (ctl && remove_dead_region(phase, can_reshape))
 309     return this;
 310   ctl = in(MemNode::Control);
 311   // Don't bother trying to transform a dead node
 312   if (ctl && ctl->is_top())  return NodeSentinel;
 313 
 314   PhaseIterGVN *igvn = phase->is_IterGVN();
 315   // Wait if control on the worklist.
 316   if (ctl && can_reshape && igvn != nullptr) {
 317     Node* bol = nullptr;
 318     Node* cmp = nullptr;
 319     if (ctl->in(0)->is_If()) {
 320       assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
 321       bol = ctl->in(0)->in(1);
 322       if (bol->is_Bool())
 323         cmp = ctl->in(0)->in(1)->in(1);
 324     }
 325     if (igvn->_worklist.member(ctl) ||
 326         (bol != nullptr && igvn->_worklist.member(bol)) ||
 327         (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
 328       // This control path may be dead.
 329       // Delay this memory node transformation until the control is processed.
 330       igvn->_worklist.push(this);
 331       return NodeSentinel; // caller will return null
 332     }
 333   }
 334   // Ignore if memory is dead, or self-loop
 335   Node *mem = in(MemNode::Memory);
 336   if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
 337   assert(mem != this, "dead loop in MemNode::Ideal");
 338 
 339   if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
 340     // This memory slice may be dead.
 341     // Delay this mem node transformation until the memory is processed.
 342     igvn->_worklist.push(this);
 343     return NodeSentinel; // caller will return null
 344   }
 345 
 346   Node *address = in(MemNode::Address);
 347   const Type *t_adr = phase->type(address);
 348   if (t_adr == Type::TOP)              return NodeSentinel; // caller will return null
 349 
 350   if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
 351     // Unsafe off-heap access with zero address. Remove access and other control users
 352     // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
 353     assert(ctl != nullptr, "unsafe accesses should be control dependent");
 354     for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
 355       Node* u = ctl->fast_out(i);
 356       if (u != ctl) {
 357         igvn->rehash_node_delayed(u);
 358         int nb = u->replace_edge(ctl, phase->C->top(), igvn);
 359         --i, imax -= nb;
 360       }
 361     }
 362     Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
 363     Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
 364     phase->C->root()->add_req(halt);
 365     return this;
 366   }
 367 
 368   if (can_reshape && igvn != nullptr &&
 369       (igvn->_worklist.member(address) ||
 370        (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
 371     // The address's base and type may change when the address is processed.
 372     // Delay this mem node transformation until the address is processed.
 373     igvn->_worklist.push(this);
 374     return NodeSentinel; // caller will return null
 375   }
 376 
 377   // Do NOT remove or optimize the next lines: ensure a new alias index
 378   // is allocated for an oop pointer type before Escape Analysis.
 379   // Note: C++ will not remove it since the call has side effect.
 380   if (t_adr->isa_oopptr()) {
 381     int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
 382   }
 383 
 384   Node* base = nullptr;
 385   if (address->is_AddP()) {
 386     base = address->in(AddPNode::Base);
 387   }
 388   if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
 389       !t_adr->isa_rawptr()) {
 390     // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
 391     // Skip this node optimization if its address has TOP base.
 392     return NodeSentinel; // caller will return null
 393   }
 394 
 395   // Avoid independent memory operations
 396   Node* old_mem = mem;
 397 
 398   // The code which unhooks non-raw memories from complete (macro-expanded)
 399   // initializations was removed. After macro-expansion all stores caught
 400   // by Initialize node became raw stores and there is no information
 401   // which memory slices they modify. So it is unsafe to move any memory
 402   // operation above these stores. Also in most cases hooked non-raw memories
 403   // were already unhooked by using information from detect_ptr_independence()
 404   // and find_previous_store().
 405 
 406   if (mem->is_MergeMem()) {
 407     MergeMemNode* mmem = mem->as_MergeMem();
 408     const TypePtr *tp = t_adr->is_ptr();
 409 
 410     mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
 411   }
 412 
 413   if (mem != old_mem) {
 414     set_req_X(MemNode::Memory, mem, phase);
 415     if (phase->type(mem) == Type::TOP) return NodeSentinel;
 416     return this;
 417   }
 418 
 419   // let the subclass continue analyzing...
 420   return nullptr;
 421 }
 422 
 423 // Helper function for proving some simple control dominations.
 424 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
 425 // Already assumes that 'dom' is available at 'sub', and that 'sub'
 426 // is not a constant (dominated by the method's StartNode).
 427 // Used by MemNode::find_previous_store to prove that the
 428 // control input of a memory operation predates (dominates)
 429 // an allocation it wants to look past.
 430 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
 431   if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top())
 432     return false; // Conservative answer for dead code
 433 
 434   // Check 'dom'. Skip Proj and CatchProj nodes.
 435   dom = dom->find_exact_control(dom);
 436   if (dom == nullptr || dom->is_top())
 437     return false; // Conservative answer for dead code
 438 
 439   if (dom == sub) {
 440     // For the case when, for example, 'sub' is Initialize and the original
 441     // 'dom' is Proj node of the 'sub'.
 442     return false;
 443   }
 444 
 445   if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
 446     return true;
 447 
 448   // 'dom' dominates 'sub' if its control edge and control edges
 449   // of all its inputs dominate or equal to sub's control edge.
 450 
 451   // Currently 'sub' is either Allocate, Initialize or Start nodes.
 452   // Or Region for the check in LoadNode::Ideal();
 453   // 'sub' should have sub->in(0) != nullptr.
 454   assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
 455          sub->is_Region() || sub->is_Call(), "expecting only these nodes");
 456 
 457   // Get control edge of 'sub'.
 458   Node* orig_sub = sub;
 459   sub = sub->find_exact_control(sub->in(0));
 460   if (sub == nullptr || sub->is_top())
 461     return false; // Conservative answer for dead code
 462 
 463   assert(sub->is_CFG(), "expecting control");
 464 
 465   if (sub == dom)
 466     return true;
 467 
 468   if (sub->is_Start() || sub->is_Root())
 469     return false;
 470 
 471   {
 472     // Check all control edges of 'dom'.
 473 
 474     ResourceMark rm;
 475     Node_List nlist;
 476     Unique_Node_List dom_list;
 477 
 478     dom_list.push(dom);
 479     bool only_dominating_controls = false;
 480 
 481     for (uint next = 0; next < dom_list.size(); next++) {
 482       Node* n = dom_list.at(next);
 483       if (n == orig_sub)
 484         return false; // One of dom's inputs dominated by sub.
 485       if (!n->is_CFG() && n->pinned()) {
 486         // Check only own control edge for pinned non-control nodes.
 487         n = n->find_exact_control(n->in(0));
 488         if (n == nullptr || n->is_top())
 489           return false; // Conservative answer for dead code
 490         assert(n->is_CFG(), "expecting control");
 491         dom_list.push(n);
 492       } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
 493         only_dominating_controls = true;
 494       } else if (n->is_CFG()) {
 495         if (n->dominates(sub, nlist))
 496           only_dominating_controls = true;
 497         else
 498           return false;
 499       } else {
 500         // First, own control edge.
 501         Node* m = n->find_exact_control(n->in(0));
 502         if (m != nullptr) {
 503           if (m->is_top())
 504             return false; // Conservative answer for dead code
 505           dom_list.push(m);
 506         }
 507         // Now, the rest of edges.
 508         uint cnt = n->req();
 509         for (uint i = 1; i < cnt; i++) {
 510           m = n->find_exact_control(n->in(i));
 511           if (m == nullptr || m->is_top())
 512             continue;
 513           dom_list.push(m);
 514         }
 515       }
 516     }
 517     return only_dominating_controls;
 518   }
 519 }
 520 
 521 //---------------------detect_ptr_independence---------------------------------
 522 // Used by MemNode::find_previous_store to prove that two base
 523 // pointers are never equal.
 524 // The pointers are accompanied by their associated allocations,
 525 // if any, which have been previously discovered by the caller.
 526 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
 527                                       Node* p2, AllocateNode* a2,
 528                                       PhaseTransform* phase) {
 529   // Attempt to prove that these two pointers cannot be aliased.
 530   // They may both manifestly be allocations, and they should differ.
 531   // Or, if they are not both allocations, they can be distinct constants.
 532   // Otherwise, one is an allocation and the other a pre-existing value.
 533   if (a1 == nullptr && a2 == nullptr) {           // neither an allocation
 534     return (p1 != p2) && p1->is_Con() && p2->is_Con();
 535   } else if (a1 != nullptr && a2 != nullptr) {    // both allocations
 536     return (a1 != a2);
 537   } else if (a1 != nullptr) {                  // one allocation a1
 538     // (Note:  p2->is_Con implies p2->in(0)->is_Root, which dominates.)
 539     return all_controls_dominate(p2, a1);
 540   } else { //(a2 != null)                   // one allocation a2
 541     return all_controls_dominate(p1, a2);
 542   }
 543   return false;
 544 }
 545 
 546 
 547 // Find an arraycopy ac that produces the memory state represented by parameter mem.
 548 // Return ac if
 549 // (a) can_see_stored_value=true  and ac must have set the value for this load or if
 550 // (b) can_see_stored_value=false and ac could have set the value for this load or if
 551 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
 552 // In case (c) change the parameter mem to the memory input of ac to skip it
 553 // when searching stored value.
 554 // Otherwise return null.
 555 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
 556   ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
 557   if (ac != nullptr) {
 558     Node* ld_addp = in(MemNode::Address);
 559     Node* src = ac->in(ArrayCopyNode::Src);
 560     const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
 561 
 562     // This is a load from a cloned array. The corresponding arraycopy ac must
 563     // have set the value for the load and we can return ac but only if the load
 564     // is known to be within bounds. This is checked below.
 565     if (ary_t != nullptr && ld_addp->is_AddP()) {
 566       Node* ld_offs = ld_addp->in(AddPNode::Offset);
 567       BasicType ary_elem = ary_t->elem()->array_element_basic_type();
 568       jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
 569       jlong elemsize = type2aelembytes(ary_elem);
 570 
 571       const TypeX*   ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 572       const TypeInt* sizetype  = ary_t->size();
 573 
 574       if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
 575         // The load is known to be within bounds. It receives its value from ac.
 576         return ac;
 577       }
 578       // The load is known to be out-of-bounds.
 579     }
 580     // The load could be out-of-bounds. It must not be hoisted but must remain
 581     // dependent on the runtime range check. This is achieved by returning null.
 582   } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
 583     ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
 584 
 585     if (ac->is_arraycopy_validated() ||
 586         ac->is_copyof_validated() ||
 587         ac->is_copyofrange_validated()) {
 588       Node* ld_addp = in(MemNode::Address);
 589       if (ld_addp->is_AddP()) {
 590         Node* ld_base = ld_addp->in(AddPNode::Address);
 591         Node* ld_offs = ld_addp->in(AddPNode::Offset);
 592 
 593         Node* dest = ac->in(ArrayCopyNode::Dest);
 594 
 595         if (dest == ld_base) {
 596           const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 597           assert(!ld_offs_t->empty(), "dead reference should be checked already");
 598           // Take into account vector or unsafe access size
 599           jlong ld_size_in_bytes = (jlong)memory_size();
 600           jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
 601           offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
 602           if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
 603             return ac;
 604           }
 605           if (!can_see_stored_value) {
 606             mem = ac->in(TypeFunc::Memory);
 607             return ac;
 608           }
 609         }
 610       }
 611     }
 612   }
 613   return nullptr;
 614 }
 615 
 616 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
 617   if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
 618                                                mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
 619     if (ld_alloc != nullptr) {
 620       // Check if there is an array copy for a clone
 621       Node* mb = mem->in(0);
 622       ArrayCopyNode* ac = nullptr;
 623       if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
 624           mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
 625         ac = mb->in(0)->in(0)->as_ArrayCopy();
 626       } else {
 627         // Step over GC barrier when ReduceInitialCardMarks is disabled
 628         BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 629         Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
 630 
 631         if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
 632           ac = control_proj_ac->in(0)->as_ArrayCopy();
 633         }
 634       }
 635 
 636       if (ac != nullptr && ac->is_clonebasic()) {
 637         AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
 638         if (alloc != nullptr && alloc == ld_alloc) {
 639           return ac;
 640         }
 641       }
 642     }
 643   }
 644   return nullptr;
 645 }
 646 
 647 // The logic for reordering loads and stores uses four steps:
 648 // (a) Walk carefully past stores and initializations which we
 649 //     can prove are independent of this load.
 650 // (b) Observe that the next memory state makes an exact match
 651 //     with self (load or store), and locate the relevant store.
 652 // (c) Ensure that, if we were to wire self directly to the store,
 653 //     the optimizer would fold it up somehow.
 654 // (d) Do the rewiring, and return, depending on some other part of
 655 //     the optimizer to fold up the load.
 656 // This routine handles steps (a) and (b).  Steps (c) and (d) are
 657 // specific to loads and stores, so they are handled by the callers.
 658 // (Currently, only LoadNode::Ideal has steps (c), (d).  More later.)
 659 //
 660 Node* MemNode::find_previous_store(PhaseValues* phase) {
 661   Node*         ctrl   = in(MemNode::Control);
 662   Node*         adr    = in(MemNode::Address);
 663   intptr_t      offset = 0;
 664   Node*         base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
 665   AllocateNode* alloc  = AllocateNode::Ideal_allocation(base);
 666 
 667   if (offset == Type::OffsetBot)
 668     return nullptr;            // cannot unalias unless there are precise offsets
 669 
 670   const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
 671   const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
 672 
 673   intptr_t size_in_bytes = memory_size();
 674 
 675   Node* mem = in(MemNode::Memory);   // start searching here...
 676 
 677   int cnt = 50;             // Cycle limiter
 678   for (;;) {                // While we can dance past unrelated stores...
 679     if (--cnt < 0)  break;  // Caught in cycle or a complicated dance?
 680 
 681     Node* prev = mem;
 682     if (mem->is_Store()) {
 683       Node* st_adr = mem->in(MemNode::Address);
 684       intptr_t st_offset = 0;
 685       Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
 686       if (st_base == nullptr)
 687         break;              // inscrutable pointer
 688 
 689       // For raw accesses it's not enough to prove that constant offsets don't intersect.
 690       // We need the bases to be the equal in order for the offset check to make sense.
 691       if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
 692         break;
 693       }
 694 
 695       if (st_offset != offset && st_offset != Type::OffsetBot) {
 696         const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
 697         assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
 698         if (st_offset >= offset + size_in_bytes ||
 699             st_offset <= offset - MAX_STORE ||
 700             st_offset <= offset - mem->as_Store()->memory_size()) {
 701           // Success:  The offsets are provably independent.
 702           // (You may ask, why not just test st_offset != offset and be done?
 703           // The answer is that stores of different sizes can co-exist
 704           // in the same sequence of RawMem effects.  We sometimes initialize
 705           // a whole 'tile' of array elements with a single jint or jlong.)
 706           mem = mem->in(MemNode::Memory);
 707           continue;           // (a) advance through independent store memory
 708         }
 709       }
 710       if (st_base != base &&
 711           detect_ptr_independence(base, alloc,
 712                                   st_base,
 713                                   AllocateNode::Ideal_allocation(st_base),
 714                                   phase)) {
 715         // Success:  The bases are provably independent.
 716         mem = mem->in(MemNode::Memory);
 717         continue;           // (a) advance through independent store memory
 718       }
 719 
 720       // (b) At this point, if the bases or offsets do not agree, we lose,
 721       // since we have not managed to prove 'this' and 'mem' independent.
 722       if (st_base == base && st_offset == offset) {
 723         return mem;         // let caller handle steps (c), (d)
 724       }
 725 
 726     } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
 727       InitializeNode* st_init = mem->in(0)->as_Initialize();
 728       AllocateNode*  st_alloc = st_init->allocation();
 729       if (st_alloc == nullptr)
 730         break;              // something degenerated
 731       bool known_identical = false;
 732       bool known_independent = false;
 733       if (alloc == st_alloc)
 734         known_identical = true;
 735       else if (alloc != nullptr)
 736         known_independent = true;
 737       else if (all_controls_dominate(this, st_alloc))
 738         known_independent = true;
 739 
 740       if (known_independent) {
 741         // The bases are provably independent: Either they are
 742         // manifestly distinct allocations, or else the control
 743         // of this load dominates the store's allocation.
 744         int alias_idx = phase->C->get_alias_index(adr_type());
 745         if (alias_idx == Compile::AliasIdxRaw) {
 746           mem = st_alloc->in(TypeFunc::Memory);
 747         } else {
 748           mem = st_init->memory(alias_idx);
 749         }
 750         continue;           // (a) advance through independent store memory
 751       }
 752 
 753       // (b) at this point, if we are not looking at a store initializing
 754       // the same allocation we are loading from, we lose.
 755       if (known_identical) {
 756         // From caller, can_see_stored_value will consult find_captured_store.
 757         return mem;         // let caller handle steps (c), (d)
 758       }
 759 
 760     } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
 761       if (prev != mem) {
 762         // Found an arraycopy but it doesn't affect that load
 763         continue;
 764       }
 765       // Found an arraycopy that may affect that load
 766       return mem;
 767     } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
 768       // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
 769       if (mem->is_Proj() && mem->in(0)->is_Call()) {
 770         // ArrayCopyNodes processed here as well.
 771         CallNode *call = mem->in(0)->as_Call();
 772         if (!call->may_modify(addr_t, phase)) {
 773           mem = call->in(TypeFunc::Memory);
 774           continue;         // (a) advance through independent call memory
 775         }
 776       } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
 777         ArrayCopyNode* ac = nullptr;
 778         if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
 779           break;
 780         }
 781         mem = mem->in(0)->in(TypeFunc::Memory);
 782         continue;           // (a) advance through independent MemBar memory
 783       } else if (mem->is_ClearArray()) {
 784         if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
 785           // (the call updated 'mem' value)
 786           continue;         // (a) advance through independent allocation memory
 787         } else {
 788           // Can not bypass initialization of the instance
 789           // we are looking for.
 790           return mem;
 791         }
 792       } else if (mem->is_MergeMem()) {
 793         int alias_idx = phase->C->get_alias_index(adr_type());
 794         mem = mem->as_MergeMem()->memory_at(alias_idx);
 795         continue;           // (a) advance through independent MergeMem memory
 796       }
 797     }
 798 
 799     // Unless there is an explicit 'continue', we must bail out here,
 800     // because 'mem' is an inscrutable memory state (e.g., a call).
 801     break;
 802   }
 803 
 804   return nullptr;              // bail out
 805 }
 806 
 807 //----------------------calculate_adr_type-------------------------------------
 808 // Helper function.  Notices when the given type of address hits top or bottom.
 809 // Also, asserts a cross-check of the type against the expected address type.
 810 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
 811   if (t == Type::TOP)  return nullptr; // does not touch memory any more?
 812   #ifdef ASSERT
 813   if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump())  cross_check = nullptr;
 814   #endif
 815   const TypePtr* tp = t->isa_ptr();
 816   if (tp == nullptr) {
 817     assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
 818     return TypePtr::BOTTOM;           // touches lots of memory
 819   } else {
 820     #ifdef ASSERT
 821     // %%%% [phh] We don't check the alias index if cross_check is
 822     //            TypeRawPtr::BOTTOM.  Needs to be investigated.
 823     if (cross_check != nullptr &&
 824         cross_check != TypePtr::BOTTOM &&
 825         cross_check != TypeRawPtr::BOTTOM) {
 826       // Recheck the alias index, to see if it has changed (due to a bug).
 827       Compile* C = Compile::current();
 828       assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
 829              "must stay in the original alias category");
 830       // The type of the address must be contained in the adr_type,
 831       // disregarding "null"-ness.
 832       // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
 833       const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
 834       assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
 835              "real address must not escape from expected memory type");
 836     }
 837     #endif
 838     return tp;
 839   }
 840 }
 841 
 842 uint8_t MemNode::barrier_data(const Node* n) {
 843   if (n->is_LoadStore()) {
 844     return n->as_LoadStore()->barrier_data();
 845   } else if (n->is_Mem()) {
 846     return n->as_Mem()->barrier_data();
 847   }
 848   return 0;
 849 }
 850 
 851 //=============================================================================
 852 // Should LoadNode::Ideal() attempt to remove control edges?
 853 bool LoadNode::can_remove_control() const {
 854   return !has_pinned_control_dependency();
 855 }
 856 uint LoadNode::size_of() const { return sizeof(*this); }
 857 bool LoadNode::cmp(const Node &n) const {
 858   LoadNode& load = (LoadNode &)n;
 859   return Type::equals(_type, load._type) &&
 860          _control_dependency == load._control_dependency &&
 861          _mo == load._mo;
 862 }
 863 const Type *LoadNode::bottom_type() const { return _type; }
 864 uint LoadNode::ideal_reg() const {
 865   return _type->ideal_reg();
 866 }
 867 
 868 #ifndef PRODUCT
 869 void LoadNode::dump_spec(outputStream *st) const {
 870   MemNode::dump_spec(st);
 871   if( !Verbose && !WizardMode ) {
 872     // standard dump does this in Verbose and WizardMode
 873     st->print(" #"); _type->dump_on(st);
 874   }
 875   if (!depends_only_on_test()) {
 876     st->print(" (does not depend only on test, ");
 877     if (control_dependency() == UnknownControl) {
 878       st->print("unknown control");
 879     } else if (control_dependency() == Pinned) {
 880       st->print("pinned");
 881     } else if (adr_type() == TypeRawPtr::BOTTOM) {
 882       st->print("raw access");
 883     } else {
 884       st->print("unknown reason");
 885     }
 886     st->print(")");
 887   }
 888 }
 889 #endif
 890 
 891 #ifdef ASSERT
 892 //----------------------------is_immutable_value-------------------------------
 893 // Helper function to allow a raw load without control edge for some cases
 894 bool LoadNode::is_immutable_value(Node* adr) {
 895   if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
 896       adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
 897 
 898     jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
 899     int offsets[] = {
 900       in_bytes(JavaThread::osthread_offset()),
 901       in_bytes(JavaThread::threadObj_offset()),
 902       in_bytes(JavaThread::vthread_offset()),
 903       in_bytes(JavaThread::scopedValueCache_offset()),
 904     };
 905 
 906     for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
 907       if (offset == offsets[i]) {
 908         return true;
 909       }
 910     }
 911   }
 912 
 913   return false;
 914 }
 915 #endif
 916 
 917 //----------------------------LoadNode::make-----------------------------------
 918 // Polymorphic factory method:
 919 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
 920                      ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
 921   Compile* C = gvn.C;
 922 
 923   // sanity check the alias category against the created node type
 924   assert(!(adr_type->isa_oopptr() &&
 925            adr_type->offset() == oopDesc::klass_offset_in_bytes()),
 926          "use LoadKlassNode instead");
 927   assert(!(adr_type->isa_aryptr() &&
 928            adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
 929          "use LoadRangeNode instead");
 930   // Check control edge of raw loads
 931   assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
 932           // oop will be recorded in oop map if load crosses safepoint
 933           rt->isa_oopptr() || is_immutable_value(adr),
 934           "raw memory operations should have control edge");
 935   LoadNode* load = nullptr;
 936   switch (bt) {
 937   case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 938   case T_BYTE:    load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 939   case T_INT:     load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 940   case T_CHAR:    load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 941   case T_SHORT:   load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 942   case T_LONG:    load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
 943   case T_FLOAT:   load = new LoadFNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency); break;
 944   case T_DOUBLE:  load = new LoadDNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency, require_atomic_access); break;
 945   case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(),  mo, control_dependency); break;
 946   case T_OBJECT:
 947   case T_NARROWOOP:
 948 #ifdef _LP64
 949     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
 950       load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
 951     } else
 952 #endif
 953     {
 954       assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
 955       load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
 956     }
 957     break;
 958   default:
 959     ShouldNotReachHere();
 960     break;
 961   }
 962   assert(load != nullptr, "LoadNode should have been created");
 963   if (unaligned) {
 964     load->set_unaligned_access();
 965   }
 966   if (mismatched) {
 967     load->set_mismatched_access();
 968   }
 969   if (unsafe) {
 970     load->set_unsafe_access();
 971   }
 972   load->set_barrier_data(barrier_data);
 973   if (load->Opcode() == Op_LoadN) {
 974     Node* ld = gvn.transform(load);
 975     return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
 976   }
 977 
 978   return load;
 979 }
 980 
 981 //------------------------------hash-------------------------------------------
 982 uint LoadNode::hash() const {
 983   // unroll addition of interesting fields
 984   return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
 985 }
 986 
 987 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
 988   if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
 989     bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
 990     bool is_stable_ary = FoldStableValues &&
 991                          (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
 992                          tp->isa_aryptr()->is_stable();
 993 
 994     return (eliminate_boxing && non_volatile) || is_stable_ary;
 995   }
 996 
 997   return false;
 998 }
 999 
1000 LoadNode* LoadNode::pin_array_access_node() const {
1001   const TypePtr* adr_type = this->adr_type();
1002   if (adr_type != nullptr && adr_type->isa_aryptr()) {
1003     return clone_pinned();
1004   }
1005   return nullptr;
1006 }
1007 
1008 // Is the value loaded previously stored by an arraycopy? If so return
1009 // a load node that reads from the source array so we may be able to
1010 // optimize out the ArrayCopy node later.
1011 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1012   Node* ld_adr = in(MemNode::Address);
1013   intptr_t ld_off = 0;
1014   AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1015   Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1016   if (ac != nullptr) {
1017     assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1018 
1019     Node* mem = ac->in(TypeFunc::Memory);
1020     Node* ctl = ac->in(0);
1021     Node* src = ac->in(ArrayCopyNode::Src);
1022 
1023     if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1024       return nullptr;
1025     }
1026 
1027     // load depends on the tests that validate the arraycopy
1028     LoadNode* ld = clone_pinned();
1029     Node* addp = in(MemNode::Address)->clone();
1030     if (ac->as_ArrayCopy()->is_clonebasic()) {
1031       assert(ld_alloc != nullptr, "need an alloc");
1032       assert(addp->is_AddP(), "address must be addp");
1033       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1034       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1035       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1036       addp->set_req(AddPNode::Base, src);
1037       addp->set_req(AddPNode::Address, src);
1038     } else {
1039       assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1040              ac->as_ArrayCopy()->is_copyof_validated() ||
1041              ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1042       assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1043       addp->set_req(AddPNode::Base, src);
1044       addp->set_req(AddPNode::Address, src);
1045 
1046       const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1047       BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1048       if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1049 
1050       uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1051       uint shift  = exact_log2(type2aelembytes(ary_elem));
1052 
1053       Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1054 #ifdef _LP64
1055       diff = phase->transform(new ConvI2LNode(diff));
1056 #endif
1057       diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1058 
1059       Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1060       addp->set_req(AddPNode::Offset, offset);
1061     }
1062     addp = phase->transform(addp);
1063 #ifdef ASSERT
1064     const TypePtr* adr_type = phase->type(addp)->is_ptr();
1065     ld->_adr_type = adr_type;
1066 #endif
1067     ld->set_req(MemNode::Address, addp);
1068     ld->set_req(0, ctl);
1069     ld->set_req(MemNode::Memory, mem);
1070     return ld;
1071   }
1072   return nullptr;
1073 }
1074 
1075 
1076 //---------------------------can_see_stored_value------------------------------
1077 // This routine exists to make sure this set of tests is done the same
1078 // everywhere.  We need to make a coordinated change: first LoadNode::Ideal
1079 // will change the graph shape in a way which makes memory alive twice at the
1080 // same time (uses the Oracle model of aliasing), then some
1081 // LoadXNode::Identity will fold things back to the equivalence-class model
1082 // of aliasing.
1083 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1084   Node* ld_adr = in(MemNode::Address);
1085   intptr_t ld_off = 0;
1086   Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1087   Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1088   const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1089   Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1090   // This is more general than load from boxing objects.
1091   if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1092     uint alias_idx = atp->index();
1093     Node* result = nullptr;
1094     Node* current = st;
1095     // Skip through chains of MemBarNodes checking the MergeMems for
1096     // new states for the slice of this load.  Stop once any other
1097     // kind of node is encountered.  Loads from final memory can skip
1098     // through any kind of MemBar but normal loads shouldn't skip
1099     // through MemBarAcquire since the could allow them to move out of
1100     // a synchronized region. It is not safe to step over MemBarCPUOrder,
1101     // because alias info above them may be inaccurate (e.g., due to
1102     // mixed/mismatched unsafe accesses).
1103     bool is_final_mem = !atp->is_rewritable();
1104     while (current->is_Proj()) {
1105       int opc = current->in(0)->Opcode();
1106       if ((is_final_mem && (opc == Op_MemBarAcquire ||
1107                             opc == Op_MemBarAcquireLock ||
1108                             opc == Op_LoadFence)) ||
1109           opc == Op_MemBarRelease ||
1110           opc == Op_StoreFence ||
1111           opc == Op_MemBarReleaseLock ||
1112           opc == Op_MemBarStoreStore ||
1113           opc == Op_StoreStoreFence) {
1114         Node* mem = current->in(0)->in(TypeFunc::Memory);
1115         if (mem->is_MergeMem()) {
1116           MergeMemNode* merge = mem->as_MergeMem();
1117           Node* new_st = merge->memory_at(alias_idx);
1118           if (new_st == merge->base_memory()) {
1119             // Keep searching
1120             current = new_st;
1121             continue;
1122           }
1123           // Save the new memory state for the slice and fall through
1124           // to exit.
1125           result = new_st;
1126         }
1127       }
1128       break;
1129     }
1130     if (result != nullptr) {
1131       st = result;
1132     }
1133   }
1134 
1135   // Loop around twice in the case Load -> Initialize -> Store.
1136   // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1137   for (int trip = 0; trip <= 1; trip++) {
1138 
1139     if (st->is_Store()) {
1140       Node* st_adr = st->in(MemNode::Address);
1141       if (st_adr != ld_adr) {
1142         // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1143         intptr_t st_off = 0;
1144         Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1145         if (ld_base == nullptr)                                return nullptr;
1146         if (st_base == nullptr)                                return nullptr;
1147         if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1148         if (ld_off != st_off)                                  return nullptr;
1149         if (ld_off == Type::OffsetBot)                         return nullptr;
1150         // Same base, same offset.
1151         // Possible improvement for arrays: check index value instead of absolute offset.
1152 
1153         // At this point we have proven something like this setup:
1154         //   B = << base >>
1155         //   L =  LoadQ(AddP(Check/CastPP(B), #Off))
1156         //   S = StoreQ(AddP(             B , #Off), V)
1157         // (Actually, we haven't yet proven the Q's are the same.)
1158         // In other words, we are loading from a casted version of
1159         // the same pointer-and-offset that we stored to.
1160         // Casted version may carry a dependency and it is respected.
1161         // Thus, we are able to replace L by V.
1162       }
1163       // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1164       if (store_Opcode() != st->Opcode()) {
1165         return nullptr;
1166       }
1167       // LoadVector/StoreVector needs additional check to ensure the types match.
1168       if (st->is_StoreVector()) {
1169         const TypeVect*  in_vt = st->as_StoreVector()->vect_type();
1170         const TypeVect* out_vt = as_LoadVector()->vect_type();
1171         if (in_vt != out_vt) {
1172           return nullptr;
1173         }
1174       }
1175       return st->in(MemNode::ValueIn);
1176     }
1177 
1178     // A load from a freshly-created object always returns zero.
1179     // (This can happen after LoadNode::Ideal resets the load's memory input
1180     // to find_captured_store, which returned InitializeNode::zero_memory.)
1181     if (st->is_Proj() && st->in(0)->is_Allocate() &&
1182         (st->in(0) == ld_alloc) &&
1183         (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1184       // return a zero value for the load's basic type
1185       // (This is one of the few places where a generic PhaseTransform
1186       // can create new nodes.  Think of it as lazily manifesting
1187       // virtually pre-existing constants.)
1188       if (memory_type() != T_VOID) {
1189         if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1190           // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1191           // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1192           // by the ArrayCopyNode.
1193           return phase->zerocon(memory_type());
1194         }
1195       } else {
1196         // TODO: materialize all-zero vector constant
1197         assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1198       }
1199     }
1200 
1201     // A load from an initialization barrier can match a captured store.
1202     if (st->is_Proj() && st->in(0)->is_Initialize()) {
1203       InitializeNode* init = st->in(0)->as_Initialize();
1204       AllocateNode* alloc = init->allocation();
1205       if ((alloc != nullptr) && (alloc == ld_alloc)) {
1206         // examine a captured store value
1207         st = init->find_captured_store(ld_off, memory_size(), phase);
1208         if (st != nullptr) {
1209           continue;             // take one more trip around
1210         }
1211       }
1212     }
1213 
1214     // Load boxed value from result of valueOf() call is input parameter.
1215     if (this->is_Load() && ld_adr->is_AddP() &&
1216         (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1217       intptr_t ignore = 0;
1218       Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1219       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1220       base = bs->step_over_gc_barrier(base);
1221       if (base != nullptr && base->is_Proj() &&
1222           base->as_Proj()->_con == TypeFunc::Parms &&
1223           base->in(0)->is_CallStaticJava() &&
1224           base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1225         return base->in(0)->in(TypeFunc::Parms);
1226       }
1227     }
1228 
1229     break;
1230   }
1231 
1232   return nullptr;
1233 }
1234 
1235 //----------------------is_instance_field_load_with_local_phi------------------
1236 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1237   if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1238       in(Address)->is_AddP() ) {
1239     const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1240     // Only instances and boxed values.
1241     if( t_oop != nullptr &&
1242         (t_oop->is_ptr_to_boxed_value() ||
1243          t_oop->is_known_instance_field()) &&
1244         t_oop->offset() != Type::OffsetBot &&
1245         t_oop->offset() != Type::OffsetTop) {
1246       return true;
1247     }
1248   }
1249   return false;
1250 }
1251 
1252 //------------------------------Identity---------------------------------------
1253 // Loads are identity if previous store is to same address
1254 Node* LoadNode::Identity(PhaseGVN* phase) {
1255   // If the previous store-maker is the right kind of Store, and the store is
1256   // to the same address, then we are equal to the value stored.
1257   Node* mem = in(Memory);
1258   Node* value = can_see_stored_value(mem, phase);
1259   if( value ) {
1260     // byte, short & char stores truncate naturally.
1261     // A load has to load the truncated value which requires
1262     // some sort of masking operation and that requires an
1263     // Ideal call instead of an Identity call.
1264     if (memory_size() < BytesPerInt) {
1265       // If the input to the store does not fit with the load's result type,
1266       // it must be truncated via an Ideal call.
1267       if (!phase->type(value)->higher_equal(phase->type(this)))
1268         return this;
1269     }
1270     // (This works even when value is a Con, but LoadNode::Value
1271     // usually runs first, producing the singleton type of the Con.)
1272     if (!has_pinned_control_dependency() || value->is_Con()) {
1273       return value;
1274     } else {
1275       return this;
1276     }
1277   }
1278 
1279   if (has_pinned_control_dependency()) {
1280     return this;
1281   }
1282   // Search for an existing data phi which was generated before for the same
1283   // instance's field to avoid infinite generation of phis in a loop.
1284   Node *region = mem->in(0);
1285   if (is_instance_field_load_with_local_phi(region)) {
1286     const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1287     int this_index  = phase->C->get_alias_index(addr_t);
1288     int this_offset = addr_t->offset();
1289     int this_iid    = addr_t->instance_id();
1290     if (!addr_t->is_known_instance() &&
1291          addr_t->is_ptr_to_boxed_value()) {
1292       // Use _idx of address base (could be Phi node) for boxed values.
1293       intptr_t   ignore = 0;
1294       Node*      base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1295       if (base == nullptr) {
1296         return this;
1297       }
1298       this_iid = base->_idx;
1299     }
1300     const Type* this_type = bottom_type();
1301     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1302       Node* phi = region->fast_out(i);
1303       if (phi->is_Phi() && phi != mem &&
1304           phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1305         return phi;
1306       }
1307     }
1308   }
1309 
1310   return this;
1311 }
1312 
1313 // Construct an equivalent unsigned load.
1314 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1315   BasicType bt = T_ILLEGAL;
1316   const Type* rt = nullptr;
1317   switch (Opcode()) {
1318     case Op_LoadUB: return this;
1319     case Op_LoadUS: return this;
1320     case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1321     case Op_LoadS: bt = T_CHAR;    rt = TypeInt::CHAR;  break;
1322     default:
1323       assert(false, "no unsigned variant: %s", Name());
1324       return nullptr;
1325   }
1326   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1327                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1328                         false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1329 }
1330 
1331 // Construct an equivalent signed load.
1332 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1333   BasicType bt = T_ILLEGAL;
1334   const Type* rt = nullptr;
1335   switch (Opcode()) {
1336     case Op_LoadUB: bt = T_BYTE;  rt = TypeInt::BYTE;  break;
1337     case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1338     case Op_LoadB: // fall through
1339     case Op_LoadS: // fall through
1340     case Op_LoadI: // fall through
1341     case Op_LoadL: return this;
1342     default:
1343       assert(false, "no signed variant: %s", Name());
1344       return nullptr;
1345   }
1346   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1347                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1348                         false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1349 }
1350 
1351 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1352   BasicType bt = rt->basic_type();
1353   switch (Opcode()) {
1354     case Op_LoadI: return (bt == T_FLOAT);
1355     case Op_LoadL: return (bt == T_DOUBLE);
1356     case Op_LoadF: return (bt == T_INT);
1357     case Op_LoadD: return (bt == T_LONG);
1358 
1359     default: return false;
1360   }
1361 }
1362 
1363 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1364   BasicType bt = rt->basic_type();
1365   assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1366   bool is_mismatched = is_mismatched_access();
1367   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1368   if (raw_type == nullptr) {
1369     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1370   }
1371   const int op = Opcode();
1372   bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1373                                (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1374   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1375                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1376                         require_atomic_access, is_unaligned_access(), is_mismatched);
1377 }
1378 
1379 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1380   BasicType bt = vt->basic_type();
1381   switch (Opcode()) {
1382     case Op_StoreI: return (bt == T_FLOAT);
1383     case Op_StoreL: return (bt == T_DOUBLE);
1384     case Op_StoreF: return (bt == T_INT);
1385     case Op_StoreD: return (bt == T_LONG);
1386 
1387     default: return false;
1388   }
1389 }
1390 
1391 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1392   BasicType bt = vt->basic_type();
1393   assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1394   const int op = Opcode();
1395   bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1396                                (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1397   StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1398                                   raw_adr_type(), val, bt, _mo, require_atomic_access);
1399 
1400   bool is_mismatched = is_mismatched_access();
1401   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1402   if (raw_type == nullptr) {
1403     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1404   }
1405   if (is_mismatched) {
1406     st->set_mismatched_access();
1407   }
1408   return st;
1409 }
1410 
1411 // We're loading from an object which has autobox behaviour.
1412 // If this object is result of a valueOf call we'll have a phi
1413 // merging a newly allocated object and a load from the cache.
1414 // We want to replace this load with the original incoming
1415 // argument to the valueOf call.
1416 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1417   assert(igvn->C->eliminate_boxing(), "sanity");
1418   intptr_t ignore = 0;
1419   Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1420   if ((base == nullptr) || base->is_Phi()) {
1421     // Push the loads from the phi that comes from valueOf up
1422     // through it to allow elimination of the loads and the recovery
1423     // of the original value. It is done in split_through_phi().
1424     return nullptr;
1425   } else if (base->is_Load() ||
1426              (base->is_DecodeN() && base->in(1)->is_Load())) {
1427     // Eliminate the load of boxed value for integer types from the cache
1428     // array by deriving the value from the index into the array.
1429     // Capture the offset of the load and then reverse the computation.
1430 
1431     // Get LoadN node which loads a boxing object from 'cache' array.
1432     if (base->is_DecodeN()) {
1433       base = base->in(1);
1434     }
1435     if (!base->in(Address)->is_AddP()) {
1436       return nullptr; // Complex address
1437     }
1438     AddPNode* address = base->in(Address)->as_AddP();
1439     Node* cache_base = address->in(AddPNode::Base);
1440     if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1441       // Get ConP node which is static 'cache' field.
1442       cache_base = cache_base->in(1);
1443     }
1444     if ((cache_base != nullptr) && cache_base->is_Con()) {
1445       const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1446       if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1447         Node* elements[4];
1448         int shift = exact_log2(type2aelembytes(T_OBJECT));
1449         int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1450         if (count > 0 && elements[0]->is_Con() &&
1451             (count == 1 ||
1452              (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1453                             elements[1]->in(2) == igvn->intcon(shift)))) {
1454           ciObjArray* array = base_type->const_oop()->as_obj_array();
1455           // Fetch the box object cache[0] at the base of the array and get its value
1456           ciInstance* box = array->obj_at(0)->as_instance();
1457           ciInstanceKlass* ik = box->klass()->as_instance_klass();
1458           assert(ik->is_box_klass(), "sanity");
1459           assert(ik->nof_nonstatic_fields() == 1, "change following code");
1460           if (ik->nof_nonstatic_fields() == 1) {
1461             // This should be true nonstatic_field_at requires calling
1462             // nof_nonstatic_fields so check it anyway
1463             ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1464             BasicType bt = c.basic_type();
1465             // Only integer types have boxing cache.
1466             assert(bt == T_BOOLEAN || bt == T_CHAR  ||
1467                    bt == T_BYTE    || bt == T_SHORT ||
1468                    bt == T_INT     || bt == T_LONG, "wrong type = %s", type2name(bt));
1469             jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1470             if (cache_low != (int)cache_low) {
1471               return nullptr; // should not happen since cache is array indexed by value
1472             }
1473             jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1474             if (offset != (int)offset) {
1475               return nullptr; // should not happen since cache is array indexed by value
1476             }
1477            // Add up all the offsets making of the address of the load
1478             Node* result = elements[0];
1479             for (int i = 1; i < count; i++) {
1480               result = igvn->transform(new AddXNode(result, elements[i]));
1481             }
1482             // Remove the constant offset from the address and then
1483             result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1484             // remove the scaling of the offset to recover the original index.
1485             if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1486               // Peel the shift off directly but wrap it in a dummy node
1487               // since Ideal can't return existing nodes
1488               igvn->_worklist.push(result); // remove dead node later
1489               result = new RShiftXNode(result->in(1), igvn->intcon(0));
1490             } else if (result->is_Add() && result->in(2)->is_Con() &&
1491                        result->in(1)->Opcode() == Op_LShiftX &&
1492                        result->in(1)->in(2) == igvn->intcon(shift)) {
1493               // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1494               // but for boxing cache access we know that X<<Z will not overflow
1495               // (there is range check) so we do this optimizatrion by hand here.
1496               igvn->_worklist.push(result); // remove dead node later
1497               Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1498               result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1499             } else {
1500               result = new RShiftXNode(result, igvn->intcon(shift));
1501             }
1502 #ifdef _LP64
1503             if (bt != T_LONG) {
1504               result = new ConvL2INode(igvn->transform(result));
1505             }
1506 #else
1507             if (bt == T_LONG) {
1508               result = new ConvI2LNode(igvn->transform(result));
1509             }
1510 #endif
1511             // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1512             // Need to preserve unboxing load type if it is unsigned.
1513             switch(this->Opcode()) {
1514               case Op_LoadUB:
1515                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1516                 break;
1517               case Op_LoadUS:
1518                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1519                 break;
1520             }
1521             return result;
1522           }
1523         }
1524       }
1525     }
1526   }
1527   return nullptr;
1528 }
1529 
1530 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1531   Node* region = phi->in(0);
1532   if (region == nullptr) {
1533     return false; // Wait stable graph
1534   }
1535   uint cnt = phi->req();
1536   for (uint i = 1; i < cnt; i++) {
1537     Node* rc = region->in(i);
1538     if (rc == nullptr || phase->type(rc) == Type::TOP)
1539       return false; // Wait stable graph
1540     Node* in = phi->in(i);
1541     if (in == nullptr || phase->type(in) == Type::TOP)
1542       return false; // Wait stable graph
1543   }
1544   return true;
1545 }
1546 
1547 //------------------------------split_through_phi------------------------------
1548 // Check whether a call to 'split_through_phi' would split this load through the
1549 // Phi *base*. This method is essentially a copy of the validations performed
1550 // by 'split_through_phi'. The first use of this method was in EA code as part
1551 // of simplification of allocation merges.
1552 // Some differences from original method (split_through_phi):
1553 //  - If base->is_CastPP(): base = base->in(1)
1554 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1555   Node* mem        = in(Memory);
1556   Node* address    = in(Address);
1557   intptr_t ignore  = 0;
1558   Node*    base    = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1559 
1560   if (base->is_CastPP()) {
1561     base = base->in(1);
1562   }
1563 
1564   if (req() > 3 || base == nullptr || !base->is_Phi()) {
1565     return false;
1566   }
1567 
1568   if (!mem->is_Phi()) {
1569     if (!MemNode::all_controls_dominate(mem, base->in(0)))
1570       return false;
1571   } else if (base->in(0) != mem->in(0)) {
1572     if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1573       return false;
1574     }
1575   }
1576 
1577   return true;
1578 }
1579 
1580 //------------------------------split_through_phi------------------------------
1581 // Split instance or boxed field load through Phi.
1582 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1583   if (req() > 3) {
1584     assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1585     // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1586     return nullptr;
1587   }
1588   Node* mem     = in(Memory);
1589   Node* address = in(Address);
1590   const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1591 
1592   assert((t_oop != nullptr) &&
1593          (ignore_missing_instance_id ||
1594           t_oop->is_known_instance_field() ||
1595           t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1596 
1597   Compile* C = phase->C;
1598   intptr_t ignore = 0;
1599   Node*    base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1600   bool base_is_phi = (base != nullptr) && base->is_Phi();
1601   bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1602                            (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1603                            phase->type(base)->higher_equal(TypePtr::NOTNULL);
1604 
1605   if (!((mem->is_Phi() || base_is_phi) &&
1606         (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1607     return nullptr; // Neither memory or base are Phi
1608   }
1609 
1610   if (mem->is_Phi()) {
1611     if (!stable_phi(mem->as_Phi(), phase)) {
1612       return nullptr; // Wait stable graph
1613     }
1614     uint cnt = mem->req();
1615     // Check for loop invariant memory.
1616     if (cnt == 3) {
1617       for (uint i = 1; i < cnt; i++) {
1618         Node* in = mem->in(i);
1619         Node*  m = optimize_memory_chain(in, t_oop, this, phase);
1620         if (m == mem) {
1621           if (i == 1) {
1622             // if the first edge was a loop, check second edge too.
1623             // If both are replaceable - we are in an infinite loop
1624             Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1625             if (n == mem) {
1626               break;
1627             }
1628           }
1629           set_req(Memory, mem->in(cnt - i));
1630           return this; // made change
1631         }
1632       }
1633     }
1634   }
1635   if (base_is_phi) {
1636     if (!stable_phi(base->as_Phi(), phase)) {
1637       return nullptr; // Wait stable graph
1638     }
1639     uint cnt = base->req();
1640     // Check for loop invariant memory.
1641     if (cnt == 3) {
1642       for (uint i = 1; i < cnt; i++) {
1643         if (base->in(i) == base) {
1644           return nullptr; // Wait stable graph
1645         }
1646       }
1647     }
1648   }
1649 
1650   // Split through Phi (see original code in loopopts.cpp).
1651   assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1652 
1653   // Do nothing here if Identity will find a value
1654   // (to avoid infinite chain of value phis generation).
1655   if (this != Identity(phase)) {
1656     return nullptr;
1657   }
1658 
1659   // Select Region to split through.
1660   Node* region;
1661   if (!base_is_phi) {
1662     assert(mem->is_Phi(), "sanity");
1663     region = mem->in(0);
1664     // Skip if the region dominates some control edge of the address.
1665     if (!MemNode::all_controls_dominate(address, region))
1666       return nullptr;
1667   } else if (!mem->is_Phi()) {
1668     assert(base_is_phi, "sanity");
1669     region = base->in(0);
1670     // Skip if the region dominates some control edge of the memory.
1671     if (!MemNode::all_controls_dominate(mem, region))
1672       return nullptr;
1673   } else if (base->in(0) != mem->in(0)) {
1674     assert(base_is_phi && mem->is_Phi(), "sanity");
1675     if (MemNode::all_controls_dominate(mem, base->in(0))) {
1676       region = base->in(0);
1677     } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1678       region = mem->in(0);
1679     } else {
1680       return nullptr; // complex graph
1681     }
1682   } else {
1683     assert(base->in(0) == mem->in(0), "sanity");
1684     region = mem->in(0);
1685   }
1686 
1687   Node* phi = nullptr;
1688   const Type* this_type = this->bottom_type();
1689   PhaseIterGVN* igvn = phase->is_IterGVN();
1690   if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1691     int this_index = C->get_alias_index(t_oop);
1692     int this_offset = t_oop->offset();
1693     int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1694     phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1695   } else if (ignore_missing_instance_id) {
1696     phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1697   } else {
1698     return nullptr;
1699   }
1700 
1701   for (uint i = 1; i < region->req(); i++) {
1702     Node* x;
1703     Node* the_clone = nullptr;
1704     Node* in = region->in(i);
1705     if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1706         in != nullptr && in->is_OuterStripMinedLoop()) {
1707       // No node should go in the outer strip mined loop
1708       in = in->in(LoopNode::EntryControl);
1709     }
1710     if (in == nullptr || in == C->top()) {
1711       x = C->top();      // Dead path?  Use a dead data op
1712     } else {
1713       x = this->clone();        // Else clone up the data op
1714       the_clone = x;            // Remember for possible deletion.
1715       // Alter data node to use pre-phi inputs
1716       if (this->in(0) == region) {
1717         x->set_req(0, in);
1718       } else {
1719         x->set_req(0, nullptr);
1720       }
1721       if (mem->is_Phi() && (mem->in(0) == region)) {
1722         x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1723       }
1724       if (address->is_Phi() && address->in(0) == region) {
1725         x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1726       }
1727       if (base_is_phi && (base->in(0) == region)) {
1728         Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1729         Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1730         x->set_req(Address, adr_x);
1731       }
1732     }
1733     // Check for a 'win' on some paths
1734     const Type *t = x->Value(igvn);
1735 
1736     bool singleton = t->singleton();
1737 
1738     // See comments in PhaseIdealLoop::split_thru_phi().
1739     if (singleton && t == Type::TOP) {
1740       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1741     }
1742 
1743     if (singleton) {
1744       x = igvn->makecon(t);
1745     } else {
1746       // We now call Identity to try to simplify the cloned node.
1747       // Note that some Identity methods call phase->type(this).
1748       // Make sure that the type array is big enough for
1749       // our new node, even though we may throw the node away.
1750       // (This tweaking with igvn only works because x is a new node.)
1751       igvn->set_type(x, t);
1752       // If x is a TypeNode, capture any more-precise type permanently into Node
1753       // otherwise it will be not updated during igvn->transform since
1754       // igvn->type(x) is set to x->Value() already.
1755       x->raise_bottom_type(t);
1756       Node* y = x->Identity(igvn);
1757       if (y != x) {
1758         x = y;
1759       } else {
1760         y = igvn->hash_find_insert(x);
1761         if (y) {
1762           x = y;
1763         } else {
1764           // Else x is a new node we are keeping
1765           // We do not need register_new_node_with_optimizer
1766           // because set_type has already been called.
1767           igvn->_worklist.push(x);
1768         }
1769       }
1770     }
1771     if (x != the_clone && the_clone != nullptr) {
1772       igvn->remove_dead_node(the_clone);
1773     }
1774     phi->set_req(i, x);
1775   }
1776   // Record Phi
1777   igvn->register_new_node_with_optimizer(phi);
1778   return phi;
1779 }
1780 
1781 AllocateNode* LoadNode::is_new_object_mark_load() const {
1782   if (Opcode() == Op_LoadX) {
1783     Node* address = in(MemNode::Address);
1784     AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1785     Node* mem = in(MemNode::Memory);
1786     if (alloc != nullptr && mem->is_Proj() &&
1787         mem->in(0) != nullptr &&
1788         mem->in(0) == alloc->initialization() &&
1789         alloc->initialization()->proj_out_or_null(0) != nullptr) {
1790       return alloc;
1791     }
1792   }
1793   return nullptr;
1794 }
1795 
1796 
1797 //------------------------------Ideal------------------------------------------
1798 // If the load is from Field memory and the pointer is non-null, it might be possible to
1799 // zero out the control input.
1800 // If the offset is constant and the base is an object allocation,
1801 // try to hook me up to the exact initializing store.
1802 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1803   if (has_pinned_control_dependency()) {
1804     return nullptr;
1805   }
1806   Node* p = MemNode::Ideal_common(phase, can_reshape);
1807   if (p)  return (p == NodeSentinel) ? nullptr : p;
1808 
1809   Node* ctrl    = in(MemNode::Control);
1810   Node* address = in(MemNode::Address);
1811   bool progress = false;
1812 
1813   bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1814          phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1815 
1816   // Skip up past a SafePoint control.  Cannot do this for Stores because
1817   // pointer stores & cardmarks must stay on the same side of a SafePoint.
1818   if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1819       phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw  &&
1820       !addr_mark &&
1821       (depends_only_on_test() || has_unknown_control_dependency())) {
1822     ctrl = ctrl->in(0);
1823     set_req(MemNode::Control,ctrl);
1824     progress = true;
1825   }
1826 
1827   intptr_t ignore = 0;
1828   Node*    base   = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1829   if (base != nullptr
1830       && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1831     // Check for useless control edge in some common special cases
1832     if (in(MemNode::Control) != nullptr
1833         && can_remove_control()
1834         && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1835         && all_controls_dominate(base, phase->C->start())) {
1836       // A method-invariant, non-null address (constant or 'this' argument).
1837       set_req(MemNode::Control, nullptr);
1838       progress = true;
1839     }
1840   }
1841 
1842   Node* mem = in(MemNode::Memory);
1843   const TypePtr *addr_t = phase->type(address)->isa_ptr();
1844 
1845   if (can_reshape && (addr_t != nullptr)) {
1846     // try to optimize our memory input
1847     Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1848     if (opt_mem != mem) {
1849       set_req_X(MemNode::Memory, opt_mem, phase);
1850       if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1851       return this;
1852     }
1853     const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1854     if ((t_oop != nullptr) &&
1855         (t_oop->is_known_instance_field() ||
1856          t_oop->is_ptr_to_boxed_value())) {
1857       PhaseIterGVN *igvn = phase->is_IterGVN();
1858       assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1859       if (igvn->_worklist.member(opt_mem)) {
1860         // Delay this transformation until memory Phi is processed.
1861         igvn->_worklist.push(this);
1862         return nullptr;
1863       }
1864       // Split instance field load through Phi.
1865       Node* result = split_through_phi(phase);
1866       if (result != nullptr) return result;
1867 
1868       if (t_oop->is_ptr_to_boxed_value()) {
1869         Node* result = eliminate_autobox(igvn);
1870         if (result != nullptr) return result;
1871       }
1872     }
1873   }
1874 
1875   // Is there a dominating load that loads the same value?  Leave
1876   // anything that is not a load of a field/array element (like
1877   // barriers etc.) alone
1878   if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1879     for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1880       Node *use = mem->fast_out(i);
1881       if (use != this &&
1882           use->Opcode() == Opcode() &&
1883           use->in(0) != nullptr &&
1884           use->in(0) != in(0) &&
1885           use->in(Address) == in(Address)) {
1886         Node* ctl = in(0);
1887         for (int i = 0; i < 10 && ctl != nullptr; i++) {
1888           ctl = IfNode::up_one_dom(ctl);
1889           if (ctl == use->in(0)) {
1890             set_req(0, use->in(0));
1891             return this;
1892           }
1893         }
1894       }
1895     }
1896   }
1897 
1898   // Check for prior store with a different base or offset; make Load
1899   // independent.  Skip through any number of them.  Bail out if the stores
1900   // are in an endless dead cycle and report no progress.  This is a key
1901   // transform for Reflection.  However, if after skipping through the Stores
1902   // we can't then fold up against a prior store do NOT do the transform as
1903   // this amounts to using the 'Oracle' model of aliasing.  It leaves the same
1904   // array memory alive twice: once for the hoisted Load and again after the
1905   // bypassed Store.  This situation only works if EVERYBODY who does
1906   // anti-dependence work knows how to bypass.  I.e. we need all
1907   // anti-dependence checks to ask the same Oracle.  Right now, that Oracle is
1908   // the alias index stuff.  So instead, peek through Stores and IFF we can
1909   // fold up, do so.
1910   Node* prev_mem = find_previous_store(phase);
1911   if (prev_mem != nullptr) {
1912     Node* value = can_see_arraycopy_value(prev_mem, phase);
1913     if (value != nullptr) {
1914       return value;
1915     }
1916   }
1917   // Steps (a), (b):  Walk past independent stores to find an exact match.
1918   if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
1919     // (c) See if we can fold up on the spot, but don't fold up here.
1920     // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1921     // just return a prior value, which is done by Identity calls.
1922     if (can_see_stored_value(prev_mem, phase)) {
1923       // Make ready for step (d):
1924       set_req_X(MemNode::Memory, prev_mem, phase);
1925       return this;
1926     }
1927   }
1928 
1929   return progress ? this : nullptr;
1930 }
1931 
1932 // Helper to recognize certain Klass fields which are invariant across
1933 // some group of array types (e.g., int[] or all T[] where T < Object).
1934 const Type*
1935 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1936                                  ciKlass* klass) const {
1937   if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1938     // The field is Klass::_modifier_flags.  Return its (constant) value.
1939     // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1940     assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1941     return TypeInt::make(klass->modifier_flags());
1942   }
1943   if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1944     // The field is Klass::_access_flags.  Return its (constant) value.
1945     // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1946     assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1947     return TypeInt::make(klass->access_flags());
1948   }
1949   if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1950     // The field is Klass::_layout_helper.  Return its constant value if known.
1951     assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1952     return TypeInt::make(klass->layout_helper());
1953   }
1954 
1955   // No match.
1956   return nullptr;
1957 }
1958 
1959 //------------------------------Value-----------------------------------------
1960 const Type* LoadNode::Value(PhaseGVN* phase) const {
1961   // Either input is TOP ==> the result is TOP
1962   Node* mem = in(MemNode::Memory);
1963   const Type *t1 = phase->type(mem);
1964   if (t1 == Type::TOP)  return Type::TOP;
1965   Node* adr = in(MemNode::Address);
1966   const TypePtr* tp = phase->type(adr)->isa_ptr();
1967   if (tp == nullptr || tp->empty())  return Type::TOP;
1968   int off = tp->offset();
1969   assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1970   Compile* C = phase->C;
1971 
1972   // Try to guess loaded type from pointer type
1973   if (tp->isa_aryptr()) {
1974     const TypeAryPtr* ary = tp->is_aryptr();
1975     const Type* t = ary->elem();
1976 
1977     // Determine whether the reference is beyond the header or not, by comparing
1978     // the offset against the offset of the start of the array's data.
1979     // Different array types begin at slightly different offsets (12 vs. 16).
1980     // We choose T_BYTE as an example base type that is least restrictive
1981     // as to alignment, which will therefore produce the smallest
1982     // possible base offset.
1983     const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1984     const bool off_beyond_header = (off >= min_base_off);
1985 
1986     // Try to constant-fold a stable array element.
1987     if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1988       // Make sure the reference is not into the header and the offset is constant
1989       ciObject* aobj = ary->const_oop();
1990       if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1991         int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1992         const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1993                                                                       stable_dimension,
1994                                                                       memory_type(), is_unsigned());
1995         if (con_type != nullptr) {
1996           return con_type;
1997         }
1998       }
1999     }
2000 
2001     // Don't do this for integer types. There is only potential profit if
2002     // the element type t is lower than _type; that is, for int types, if _type is
2003     // more restrictive than t.  This only happens here if one is short and the other
2004     // char (both 16 bits), and in those cases we've made an intentional decision
2005     // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2006     // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2007     //
2008     // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2009     // where the _gvn.type of the AddP is wider than 8.  This occurs when an earlier
2010     // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2011     // subsumed by p1.  If p1 is on the worklist but has not yet been re-transformed,
2012     // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2013     // In fact, that could have been the original type of p1, and p1 could have
2014     // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2015     // expression (LShiftL quux 3) independently optimized to the constant 8.
2016     if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2017         && (_type->isa_vect() == nullptr)
2018         && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2019       // t might actually be lower than _type, if _type is a unique
2020       // concrete subclass of abstract class t.
2021       if (off_beyond_header || off == Type::OffsetBot) {  // is the offset beyond the header?
2022         const Type* jt = t->join_speculative(_type);
2023         // In any case, do not allow the join, per se, to empty out the type.
2024         if (jt->empty() && !t->empty()) {
2025           // This can happen if a interface-typed array narrows to a class type.
2026           jt = _type;
2027         }
2028 #ifdef ASSERT
2029         if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2030           // The pointers in the autobox arrays are always non-null
2031           Node* base = adr->in(AddPNode::Base);
2032           if ((base != nullptr) && base->is_DecodeN()) {
2033             // Get LoadN node which loads IntegerCache.cache field
2034             base = base->in(1);
2035           }
2036           if ((base != nullptr) && base->is_Con()) {
2037             const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2038             if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2039               // It could be narrow oop
2040               assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2041             }
2042           }
2043         }
2044 #endif
2045         return jt;
2046       }
2047     }
2048   } else if (tp->base() == Type::InstPtr) {
2049     assert( off != Type::OffsetBot ||
2050             // arrays can be cast to Objects
2051             !tp->isa_instptr() ||
2052             tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2053             // unsafe field access may not have a constant offset
2054             C->has_unsafe_access(),
2055             "Field accesses must be precise" );
2056     // For oop loads, we expect the _type to be precise.
2057 
2058     // Optimize loads from constant fields.
2059     const TypeInstPtr* tinst = tp->is_instptr();
2060     ciObject* const_oop = tinst->const_oop();
2061     if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2062       const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
2063       if (con_type != nullptr) {
2064         return con_type;
2065       }
2066     }
2067   } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2068     assert(off != Type::OffsetBot ||
2069             !tp->isa_instklassptr() ||
2070            // arrays can be cast to Objects
2071            tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2072            // also allow array-loading from the primary supertype
2073            // array during subtype checks
2074            Opcode() == Op_LoadKlass,
2075            "Field accesses must be precise");
2076     // For klass/static loads, we expect the _type to be precise
2077   } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2078     /* With mirrors being an indirect in the Klass*
2079      * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2080      * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2081      *
2082      * So check the type and klass of the node before the LoadP.
2083      */
2084     Node* adr2 = adr->in(MemNode::Address);
2085     const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2086     if (tkls != nullptr && !StressReflectiveCode) {
2087       if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2088         ciKlass* klass = tkls->exact_klass();
2089         assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2090         assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2091         return TypeInstPtr::make(klass->java_mirror());
2092       }
2093     }
2094   }
2095 
2096   const TypeKlassPtr *tkls = tp->isa_klassptr();
2097   if (tkls != nullptr) {
2098     if (tkls->is_loaded() && tkls->klass_is_exact()) {
2099       ciKlass* klass = tkls->exact_klass();
2100       // We are loading a field from a Klass metaobject whose identity
2101       // is known at compile time (the type is "exact" or "precise").
2102       // Check for fields we know are maintained as constants by the VM.
2103       if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2104         // The field is Klass::_super_check_offset.  Return its (constant) value.
2105         // (Folds up type checking code.)
2106         assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2107         return TypeInt::make(klass->super_check_offset());
2108       }
2109       // Compute index into primary_supers array
2110       juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2111       // Check for overflowing; use unsigned compare to handle the negative case.
2112       if( depth < ciKlass::primary_super_limit() ) {
2113         // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2114         // (Folds up type checking code.)
2115         assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2116         ciKlass *ss = klass->super_of_depth(depth);
2117         return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2118       }
2119       const Type* aift = load_array_final_field(tkls, klass);
2120       if (aift != nullptr)  return aift;
2121     }
2122 
2123     // We can still check if we are loading from the primary_supers array at a
2124     // shallow enough depth.  Even though the klass is not exact, entries less
2125     // than or equal to its super depth are correct.
2126     if (tkls->is_loaded()) {
2127       ciKlass* klass = nullptr;
2128       if (tkls->isa_instklassptr()) {
2129         klass = tkls->is_instklassptr()->instance_klass();
2130       } else {
2131         int dims;
2132         const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2133         if (inner->isa_instklassptr()) {
2134           klass = inner->is_instklassptr()->instance_klass();
2135           klass = ciObjArrayKlass::make(klass, dims);
2136         }
2137       }
2138       if (klass != nullptr) {
2139         // Compute index into primary_supers array
2140         juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2141         // Check for overflowing; use unsigned compare to handle the negative case.
2142         if (depth < ciKlass::primary_super_limit() &&
2143             depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2144           // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2145           // (Folds up type checking code.)
2146           assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2147           ciKlass *ss = klass->super_of_depth(depth);
2148           return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2149         }
2150       }
2151     }
2152 
2153     // If the type is enough to determine that the thing is not an array,
2154     // we can give the layout_helper a positive interval type.
2155     // This will help short-circuit some reflective code.
2156     if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2157         tkls->isa_instklassptr() && // not directly typed as an array
2158         !tkls->is_instklassptr()->instance_klass()->is_java_lang_Object() // not the supertype of all T[] and specifically not Serializable & Cloneable
2159         ) {
2160       // Note:  When interfaces are reliable, we can narrow the interface
2161       // test to (klass != Serializable && klass != Cloneable).
2162       assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2163       jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2164       // The key property of this type is that it folds up tests
2165       // for array-ness, since it proves that the layout_helper is positive.
2166       // Thus, a generic value like the basic object layout helper works fine.
2167       return TypeInt::make(min_size, max_jint, Type::WidenMin);
2168     }
2169   }
2170 
2171   // If we are loading from a freshly-allocated object, produce a zero,
2172   // if the load is provably beyond the header of the object.
2173   // (Also allow a variable load from a fresh array to produce zero.)
2174   const TypeOopPtr *tinst = tp->isa_oopptr();
2175   bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2176   bool is_boxed_value = (tinst != nullptr) && tinst->is_ptr_to_boxed_value();
2177   if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2178     Node* value = can_see_stored_value(mem,phase);
2179     if (value != nullptr && value->is_Con()) {
2180       assert(value->bottom_type()->higher_equal(_type),"sanity");
2181       return value->bottom_type();
2182     }
2183   }
2184 
2185   bool is_vect = (_type->isa_vect() != nullptr);
2186   if (is_instance && !is_vect) {
2187     // If we have an instance type and our memory input is the
2188     // programs's initial memory state, there is no matching store,
2189     // so just return a zero of the appropriate type -
2190     // except if it is vectorized - then we have no zero constant.
2191     Node *mem = in(MemNode::Memory);
2192     if (mem->is_Parm() && mem->in(0)->is_Start()) {
2193       assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2194       return Type::get_zero_type(_type->basic_type());
2195     }
2196   }
2197 
2198   Node* alloc = is_new_object_mark_load();
2199   if (alloc != nullptr) {
2200     return TypeX::make(markWord::prototype().value());
2201   }
2202 
2203   return _type;
2204 }
2205 
2206 //------------------------------match_edge-------------------------------------
2207 // Do we Match on this edge index or not?  Match only the address.
2208 uint LoadNode::match_edge(uint idx) const {
2209   return idx == MemNode::Address;
2210 }
2211 
2212 //--------------------------LoadBNode::Ideal--------------------------------------
2213 //
2214 //  If the previous store is to the same address as this load,
2215 //  and the value stored was larger than a byte, replace this load
2216 //  with the value stored truncated to a byte.  If no truncation is
2217 //  needed, the replacement is done in LoadNode::Identity().
2218 //
2219 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2220   Node* mem = in(MemNode::Memory);
2221   Node* value = can_see_stored_value(mem,phase);
2222   if (value != nullptr) {
2223     Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2224     if (narrow != value) {
2225       return narrow;
2226     }
2227   }
2228   // Identity call will handle the case where truncation is not needed.
2229   return LoadNode::Ideal(phase, can_reshape);
2230 }
2231 
2232 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2233   Node* mem = in(MemNode::Memory);
2234   Node* value = can_see_stored_value(mem,phase);
2235   if (value != nullptr && value->is_Con() &&
2236       !value->bottom_type()->higher_equal(_type)) {
2237     // If the input to the store does not fit with the load's result type,
2238     // it must be truncated. We can't delay until Ideal call since
2239     // a singleton Value is needed for split_thru_phi optimization.
2240     int con = value->get_int();
2241     return TypeInt::make((con << 24) >> 24);
2242   }
2243   return LoadNode::Value(phase);
2244 }
2245 
2246 //--------------------------LoadUBNode::Ideal-------------------------------------
2247 //
2248 //  If the previous store is to the same address as this load,
2249 //  and the value stored was larger than a byte, replace this load
2250 //  with the value stored truncated to a byte.  If no truncation is
2251 //  needed, the replacement is done in LoadNode::Identity().
2252 //
2253 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2254   Node* mem = in(MemNode::Memory);
2255   Node* value = can_see_stored_value(mem, phase);
2256   if (value != nullptr) {
2257     Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2258     if (narrow != value) {
2259       return narrow;
2260     }
2261   }
2262   // Identity call will handle the case where truncation is not needed.
2263   return LoadNode::Ideal(phase, can_reshape);
2264 }
2265 
2266 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2267   Node* mem = in(MemNode::Memory);
2268   Node* value = can_see_stored_value(mem,phase);
2269   if (value != nullptr && value->is_Con() &&
2270       !value->bottom_type()->higher_equal(_type)) {
2271     // If the input to the store does not fit with the load's result type,
2272     // it must be truncated. We can't delay until Ideal call since
2273     // a singleton Value is needed for split_thru_phi optimization.
2274     int con = value->get_int();
2275     return TypeInt::make(con & 0xFF);
2276   }
2277   return LoadNode::Value(phase);
2278 }
2279 
2280 //--------------------------LoadUSNode::Ideal-------------------------------------
2281 //
2282 //  If the previous store is to the same address as this load,
2283 //  and the value stored was larger than a char, replace this load
2284 //  with the value stored truncated to a char.  If no truncation is
2285 //  needed, the replacement is done in LoadNode::Identity().
2286 //
2287 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2288   Node* mem = in(MemNode::Memory);
2289   Node* value = can_see_stored_value(mem,phase);
2290   if (value != nullptr) {
2291     Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2292     if (narrow != value) {
2293       return narrow;
2294     }
2295   }
2296   // Identity call will handle the case where truncation is not needed.
2297   return LoadNode::Ideal(phase, can_reshape);
2298 }
2299 
2300 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2301   Node* mem = in(MemNode::Memory);
2302   Node* value = can_see_stored_value(mem,phase);
2303   if (value != nullptr && value->is_Con() &&
2304       !value->bottom_type()->higher_equal(_type)) {
2305     // If the input to the store does not fit with the load's result type,
2306     // it must be truncated. We can't delay until Ideal call since
2307     // a singleton Value is needed for split_thru_phi optimization.
2308     int con = value->get_int();
2309     return TypeInt::make(con & 0xFFFF);
2310   }
2311   return LoadNode::Value(phase);
2312 }
2313 
2314 //--------------------------LoadSNode::Ideal--------------------------------------
2315 //
2316 //  If the previous store is to the same address as this load,
2317 //  and the value stored was larger than a short, replace this load
2318 //  with the value stored truncated to a short.  If no truncation is
2319 //  needed, the replacement is done in LoadNode::Identity().
2320 //
2321 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2322   Node* mem = in(MemNode::Memory);
2323   Node* value = can_see_stored_value(mem,phase);
2324   if (value != nullptr) {
2325     Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2326     if (narrow != value) {
2327       return narrow;
2328     }
2329   }
2330   // Identity call will handle the case where truncation is not needed.
2331   return LoadNode::Ideal(phase, can_reshape);
2332 }
2333 
2334 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2335   Node* mem = in(MemNode::Memory);
2336   Node* value = can_see_stored_value(mem,phase);
2337   if (value != nullptr && value->is_Con() &&
2338       !value->bottom_type()->higher_equal(_type)) {
2339     // If the input to the store does not fit with the load's result type,
2340     // it must be truncated. We can't delay until Ideal call since
2341     // a singleton Value is needed for split_thru_phi optimization.
2342     int con = value->get_int();
2343     return TypeInt::make((con << 16) >> 16);
2344   }
2345   return LoadNode::Value(phase);
2346 }
2347 
2348 //=============================================================================
2349 //----------------------------LoadKlassNode::make------------------------------
2350 // Polymorphic factory method:
2351 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2352   // sanity check the alias category against the created node type
2353   const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2354   assert(adr_type != nullptr, "expecting TypeKlassPtr");
2355 #ifdef _LP64
2356   if (adr_type->is_ptr_to_narrowklass()) {
2357     assert(UseCompressedClassPointers, "no compressed klasses");
2358     Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2359     return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2360   }
2361 #endif
2362   assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2363   return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2364 }
2365 
2366 //------------------------------Value------------------------------------------
2367 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2368   return klass_value_common(phase);
2369 }
2370 
2371 // In most cases, LoadKlassNode does not have the control input set. If the control
2372 // input is set, it must not be removed (by LoadNode::Ideal()).
2373 bool LoadKlassNode::can_remove_control() const {
2374   return false;
2375 }
2376 
2377 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2378   // Either input is TOP ==> the result is TOP
2379   const Type *t1 = phase->type( in(MemNode::Memory) );
2380   if (t1 == Type::TOP)  return Type::TOP;
2381   Node *adr = in(MemNode::Address);
2382   const Type *t2 = phase->type( adr );
2383   if (t2 == Type::TOP)  return Type::TOP;
2384   const TypePtr *tp = t2->is_ptr();
2385   if (TypePtr::above_centerline(tp->ptr()) ||
2386       tp->ptr() == TypePtr::Null)  return Type::TOP;
2387 
2388   // Return a more precise klass, if possible
2389   const TypeInstPtr *tinst = tp->isa_instptr();
2390   if (tinst != nullptr) {
2391     ciInstanceKlass* ik = tinst->instance_klass();
2392     int offset = tinst->offset();
2393     if (ik == phase->C->env()->Class_klass()
2394         && (offset == java_lang_Class::klass_offset() ||
2395             offset == java_lang_Class::array_klass_offset())) {
2396       // We are loading a special hidden field from a Class mirror object,
2397       // the field which points to the VM's Klass metaobject.
2398       ciType* t = tinst->java_mirror_type();
2399       // java_mirror_type returns non-null for compile-time Class constants.
2400       if (t != nullptr) {
2401         // constant oop => constant klass
2402         if (offset == java_lang_Class::array_klass_offset()) {
2403           if (t->is_void()) {
2404             // We cannot create a void array.  Since void is a primitive type return null
2405             // klass.  Users of this result need to do a null check on the returned klass.
2406             return TypePtr::NULL_PTR;
2407           }
2408           return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2409         }
2410         if (!t->is_klass()) {
2411           // a primitive Class (e.g., int.class) has null for a klass field
2412           return TypePtr::NULL_PTR;
2413         }
2414         // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2415         return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2416       }
2417       // non-constant mirror, so we can't tell what's going on
2418     }
2419     if (!tinst->is_loaded())
2420       return _type;             // Bail out if not loaded
2421     if (offset == oopDesc::klass_offset_in_bytes()) {
2422       return tinst->as_klass_type(true);
2423     }
2424   }
2425 
2426   // Check for loading klass from an array
2427   const TypeAryPtr *tary = tp->isa_aryptr();
2428   if (tary != nullptr &&
2429       tary->offset() == oopDesc::klass_offset_in_bytes()) {
2430     return tary->as_klass_type(true);
2431   }
2432 
2433   // Check for loading klass from an array klass
2434   const TypeKlassPtr *tkls = tp->isa_klassptr();
2435   if (tkls != nullptr && !StressReflectiveCode) {
2436     if (!tkls->is_loaded())
2437      return _type;             // Bail out if not loaded
2438     if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2439         tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2440       // // Always returning precise element type is incorrect,
2441       // // e.g., element type could be object and array may contain strings
2442       // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2443 
2444       // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2445       // according to the element type's subclassing.
2446       return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2447     }
2448     if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2449         tkls->offset() == in_bytes(Klass::super_offset())) {
2450       ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2451       // The field is Klass::_super.  Return its (constant) value.
2452       // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2453       return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2454     }
2455   }
2456 
2457   if (tkls != nullptr && !UseSecondarySupersCache
2458       && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset()))  {
2459     // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2460     return TypePtr::NULL_PTR;
2461   }
2462 
2463   // Bailout case
2464   return LoadNode::Value(phase);
2465 }
2466 
2467 //------------------------------Identity---------------------------------------
2468 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2469 // Also feed through the klass in Allocate(...klass...)._klass.
2470 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2471   return klass_identity_common(phase);
2472 }
2473 
2474 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2475   Node* x = LoadNode::Identity(phase);
2476   if (x != this)  return x;
2477 
2478   // Take apart the address into an oop and offset.
2479   // Return 'this' if we cannot.
2480   Node*    adr    = in(MemNode::Address);
2481   intptr_t offset = 0;
2482   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2483   if (base == nullptr)     return this;
2484   const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2485   if (toop == nullptr)     return this;
2486 
2487   // Step over potential GC barrier for OopHandle resolve
2488   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2489   if (bs->is_gc_barrier_node(base)) {
2490     base = bs->step_over_gc_barrier(base);
2491   }
2492 
2493   // We can fetch the klass directly through an AllocateNode.
2494   // This works even if the klass is not constant (clone or newArray).
2495   if (offset == oopDesc::klass_offset_in_bytes()) {
2496     Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2497     if (allocated_klass != nullptr) {
2498       return allocated_klass;
2499     }
2500   }
2501 
2502   // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2503   // See inline_native_Class_query for occurrences of these patterns.
2504   // Java Example:  x.getClass().isAssignableFrom(y)
2505   //
2506   // This improves reflective code, often making the Class
2507   // mirror go completely dead.  (Current exception:  Class
2508   // mirrors may appear in debug info, but we could clean them out by
2509   // introducing a new debug info operator for Klass.java_mirror).
2510 
2511   if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2512       && offset == java_lang_Class::klass_offset()) {
2513     if (base->is_Load()) {
2514       Node* base2 = base->in(MemNode::Address);
2515       if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2516         Node* adr2 = base2->in(MemNode::Address);
2517         const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2518         if (tkls != nullptr && !tkls->empty()
2519             && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2520             && adr2->is_AddP()
2521            ) {
2522           int mirror_field = in_bytes(Klass::java_mirror_offset());
2523           if (tkls->offset() == mirror_field) {
2524             return adr2->in(AddPNode::Base);
2525           }
2526         }
2527       }
2528     }
2529   }
2530 
2531   return this;
2532 }
2533 
2534 LoadNode* LoadNode::clone_pinned() const {
2535   LoadNode* ld = clone()->as_Load();
2536   ld->_control_dependency = UnknownControl;
2537   return ld;
2538 }
2539 
2540 
2541 //------------------------------Value------------------------------------------
2542 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2543   const Type *t = klass_value_common(phase);
2544   if (t == Type::TOP)
2545     return t;
2546 
2547   return t->make_narrowklass();
2548 }
2549 
2550 //------------------------------Identity---------------------------------------
2551 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2552 // Also feed through the klass in Allocate(...klass...)._klass.
2553 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2554   Node *x = klass_identity_common(phase);
2555 
2556   const Type *t = phase->type( x );
2557   if( t == Type::TOP ) return x;
2558   if( t->isa_narrowklass()) return x;
2559   assert (!t->isa_narrowoop(), "no narrow oop here");
2560 
2561   return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2562 }
2563 
2564 //------------------------------Value-----------------------------------------
2565 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2566   // Either input is TOP ==> the result is TOP
2567   const Type *t1 = phase->type( in(MemNode::Memory) );
2568   if( t1 == Type::TOP ) return Type::TOP;
2569   Node *adr = in(MemNode::Address);
2570   const Type *t2 = phase->type( adr );
2571   if( t2 == Type::TOP ) return Type::TOP;
2572   const TypePtr *tp = t2->is_ptr();
2573   if (TypePtr::above_centerline(tp->ptr()))  return Type::TOP;
2574   const TypeAryPtr *tap = tp->isa_aryptr();
2575   if( !tap ) return _type;
2576   return tap->size();
2577 }
2578 
2579 //-------------------------------Ideal---------------------------------------
2580 // Feed through the length in AllocateArray(...length...)._length.
2581 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2582   Node* p = MemNode::Ideal_common(phase, can_reshape);
2583   if (p)  return (p == NodeSentinel) ? nullptr : p;
2584 
2585   // Take apart the address into an oop and offset.
2586   // Return 'this' if we cannot.
2587   Node*    adr    = in(MemNode::Address);
2588   intptr_t offset = 0;
2589   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase,  offset);
2590   if (base == nullptr)     return nullptr;
2591   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2592   if (tary == nullptr)     return nullptr;
2593 
2594   // We can fetch the length directly through an AllocateArrayNode.
2595   // This works even if the length is not constant (clone or newArray).
2596   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2597     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2598     if (alloc != nullptr) {
2599       Node* allocated_length = alloc->Ideal_length();
2600       Node* len = alloc->make_ideal_length(tary, phase);
2601       if (allocated_length != len) {
2602         // New CastII improves on this.
2603         return len;
2604       }
2605     }
2606   }
2607 
2608   return nullptr;
2609 }
2610 
2611 //------------------------------Identity---------------------------------------
2612 // Feed through the length in AllocateArray(...length...)._length.
2613 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2614   Node* x = LoadINode::Identity(phase);
2615   if (x != this)  return x;
2616 
2617   // Take apart the address into an oop and offset.
2618   // Return 'this' if we cannot.
2619   Node*    adr    = in(MemNode::Address);
2620   intptr_t offset = 0;
2621   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2622   if (base == nullptr)     return this;
2623   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2624   if (tary == nullptr)     return this;
2625 
2626   // We can fetch the length directly through an AllocateArrayNode.
2627   // This works even if the length is not constant (clone or newArray).
2628   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2629     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2630     if (alloc != nullptr) {
2631       Node* allocated_length = alloc->Ideal_length();
2632       // Do not allow make_ideal_length to allocate a CastII node.
2633       Node* len = alloc->make_ideal_length(tary, phase, false);
2634       if (allocated_length == len) {
2635         // Return allocated_length only if it would not be improved by a CastII.
2636         return allocated_length;
2637       }
2638     }
2639   }
2640 
2641   return this;
2642 
2643 }
2644 
2645 //=============================================================================
2646 //---------------------------StoreNode::make-----------------------------------
2647 // Polymorphic factory method:
2648 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) {
2649   assert((mo == unordered || mo == release), "unexpected");
2650   Compile* C = gvn.C;
2651   assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2652          ctl != nullptr, "raw memory operations should have control edge");
2653 
2654   switch (bt) {
2655   case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2656   case T_BYTE:    return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2657   case T_INT:     return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2658   case T_CHAR:
2659   case T_SHORT:   return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2660   case T_LONG:    return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2661   case T_FLOAT:   return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2662   case T_DOUBLE:  return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2663   case T_METADATA:
2664   case T_ADDRESS:
2665   case T_OBJECT:
2666 #ifdef _LP64
2667     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2668       val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2669       return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2670     } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2671                (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2672                 adr->bottom_type()->isa_rawptr())) {
2673       val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2674       return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2675     }
2676 #endif
2677     {
2678       return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2679     }
2680   default:
2681     ShouldNotReachHere();
2682     return (StoreNode*)nullptr;
2683   }
2684 }
2685 
2686 //--------------------------bottom_type----------------------------------------
2687 const Type *StoreNode::bottom_type() const {
2688   return Type::MEMORY;
2689 }
2690 
2691 //------------------------------hash-------------------------------------------
2692 uint StoreNode::hash() const {
2693   // unroll addition of interesting fields
2694   //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2695 
2696   // Since they are not commoned, do not hash them:
2697   return NO_HASH;
2698 }
2699 
2700 // Class to parse array pointers, and determine if they are adjacent. We parse the form:
2701 //
2702 //   pointer =   base
2703 //             + constant_offset
2704 //             + LShiftL( ConvI2L(int_offset + int_con), int_offset_shift)
2705 //             + sum(other_offsets)
2706 //
2707 //
2708 // Note: we accumulate all constant offsets into constant_offset, even the int constant behind
2709 //       the "LShiftL(ConvI2L(...))" pattern. We convert "ConvI2L(int_offset + int_con)" to
2710 //       "ConvI2L(int_offset) + int_con", which is only safe if we can assume that either all
2711 //       compared addresses have an overflow for "int_offset + int_con" or none.
2712 //       For loads and stores on arrays, we know that if one overflows and the other not, then
2713 //       the two addresses lay almost max_int indices apart, but the maximal array size is
2714 //       only about half of that. Therefore, the RangeCheck on at least one of them must have
2715 //       failed.
2716 //
2717 //   constant_offset += LShiftL( ConvI2L(int_con), int_offset_shift)
2718 //
2719 //   pointer =   base
2720 //             + constant_offset
2721 //             + LShiftL( ConvI2L(int_offset), int_offset_shift)
2722 //             + sum(other_offsets)
2723 //
2724 class ArrayPointer {
2725 private:
2726   const bool _is_valid;          // The parsing succeeded
2727   const Node* _pointer;          // The final pointer to the position in the array
2728   const Node* _base;             // Base address of the array
2729   const jlong _constant_offset;  // Sum of collected constant offsets
2730   const Node* _int_offset;       // (optional) Offset behind LShiftL and ConvI2L
2731   const jint  _int_offset_shift; // (optional) Shift value for int_offset
2732   const GrowableArray<Node*>* _other_offsets; // List of other AddP offsets
2733 
2734   ArrayPointer(const bool is_valid,
2735                const Node* pointer,
2736                const Node* base,
2737                const jlong constant_offset,
2738                const Node* int_offset,
2739                const jint int_offset_shift,
2740                const GrowableArray<Node*>* other_offsets) :
2741       _is_valid(is_valid),
2742       _pointer(pointer),
2743       _base(base),
2744       _constant_offset(constant_offset),
2745       _int_offset(int_offset),
2746       _int_offset_shift(int_offset_shift),
2747       _other_offsets(other_offsets)
2748   {
2749     assert(_pointer != nullptr, "must always have pointer");
2750     assert(is_valid == (_base != nullptr), "have base exactly if valid");
2751     assert(is_valid == (_other_offsets != nullptr), "have other_offsets exactly if valid");
2752   }
2753 
2754   static ArrayPointer make_invalid(const Node* pointer) {
2755     return ArrayPointer(false, pointer, nullptr, 0, nullptr, 0, nullptr);
2756   }
2757 
2758   static bool parse_int_offset(Node* offset, Node*& int_offset, jint& int_offset_shift) {
2759     // offset = LShiftL( ConvI2L(int_offset), int_offset_shift)
2760     if (offset->Opcode() == Op_LShiftL &&
2761         offset->in(1)->Opcode() == Op_ConvI2L &&
2762         offset->in(2)->Opcode() == Op_ConI) {
2763       int_offset = offset->in(1)->in(1); // LShiftL -> ConvI2L -> int_offset
2764       int_offset_shift = offset->in(2)->get_int(); // LShiftL -> int_offset_shift
2765       return true;
2766     }
2767 
2768     // offset = ConvI2L(int_offset) = LShiftL( ConvI2L(int_offset), 0)
2769     if (offset->Opcode() == Op_ConvI2L) {
2770       int_offset = offset->in(1);
2771       int_offset_shift = 0;
2772       return true;
2773     }
2774 
2775     // parse failed
2776     return false;
2777   }
2778 
2779 public:
2780   // Parse the structure above the pointer
2781   static ArrayPointer make(PhaseGVN* phase, const Node* pointer) {
2782     assert(phase->type(pointer)->isa_aryptr() != nullptr, "must be array pointer");
2783     if (!pointer->is_AddP()) { return ArrayPointer::make_invalid(pointer); }
2784 
2785     const Node* base = pointer->in(AddPNode::Base);
2786     if (base == nullptr) { return ArrayPointer::make_invalid(pointer); }
2787 
2788     const int search_depth = 5;
2789     Node* offsets[search_depth];
2790     int count = pointer->as_AddP()->unpack_offsets(offsets, search_depth);
2791 
2792     // We expect at least a constant each
2793     if (count <= 0) { return ArrayPointer::make_invalid(pointer); }
2794 
2795     // We extract the form:
2796     //
2797     //   pointer =   base
2798     //             + constant_offset
2799     //             + LShiftL( ConvI2L(int_offset + int_con), int_offset_shift)
2800     //             + sum(other_offsets)
2801     //
2802     jlong constant_offset = 0;
2803     Node* int_offset = nullptr;
2804     jint int_offset_shift = 0;
2805     GrowableArray<Node*>* other_offsets = new GrowableArray<Node*>(count);
2806 
2807     for (int i = 0; i < count; i++) {
2808       Node* offset = offsets[i];
2809       if (offset->Opcode() == Op_ConI) {
2810         // Constant int offset
2811         constant_offset += offset->get_int();
2812       } else if (offset->Opcode() == Op_ConL) {
2813         // Constant long offset
2814         constant_offset += offset->get_long();
2815       } else if(int_offset == nullptr && parse_int_offset(offset, int_offset, int_offset_shift)) {
2816         // LShiftL( ConvI2L(int_offset), int_offset_shift)
2817         int_offset = int_offset->uncast();
2818         if (int_offset->Opcode() == Op_AddI && int_offset->in(2)->Opcode() == Op_ConI) {
2819           // LShiftL( ConvI2L(int_offset + int_con), int_offset_shift)
2820           constant_offset += ((jlong)int_offset->in(2)->get_int()) << int_offset_shift;
2821           int_offset = int_offset->in(1);
2822         }
2823       } else {
2824         // All others
2825         other_offsets->append(offset);
2826       }
2827     }
2828 
2829     return ArrayPointer(true, pointer, base, constant_offset, int_offset, int_offset_shift, other_offsets);
2830   }
2831 
2832   bool is_adjacent_to_and_before(const ArrayPointer& other, const jlong data_size) const {
2833     if (!_is_valid || !other._is_valid) { return false; }
2834 
2835     // Offset adjacent?
2836     if (this->_constant_offset + data_size != other._constant_offset) { return false; }
2837 
2838     // All other components identical?
2839     if (this->_base != other._base ||
2840         this->_int_offset != other._int_offset ||
2841         this->_int_offset_shift != other._int_offset_shift ||
2842         this->_other_offsets->length() != other._other_offsets->length()) {
2843       return false;
2844     }
2845 
2846     for (int i = 0; i < this->_other_offsets->length(); i++) {
2847       Node* o1 = this->_other_offsets->at(i);
2848       Node* o2 = other._other_offsets->at(i);
2849       if (o1 != o2) { return false; }
2850     }
2851 
2852     return true;
2853   }
2854 
2855 #ifndef PRODUCT
2856   void dump() {
2857     if (!_is_valid) {
2858       tty->print("ArrayPointer[%d %s, invalid]", _pointer->_idx, _pointer->Name());
2859       return;
2860     }
2861     tty->print("ArrayPointer[%d %s, base[%d %s] + %lld",
2862                _pointer->_idx, _pointer->Name(),
2863                _base->_idx, _base->Name(),
2864                (long long)_constant_offset);
2865     if (_int_offset != 0) {
2866       tty->print(" + I2L[%d %s] << %d",
2867                  _int_offset->_idx, _int_offset->Name(), _int_offset_shift);
2868     }
2869     for (int i = 0; i < _other_offsets->length(); i++) {
2870       Node* n = _other_offsets->at(i);
2871       tty->print(" + [%d %s]", n->_idx, n->Name());
2872     }
2873     tty->print_cr("]");
2874   }
2875 #endif
2876 };
2877 
2878 // Link together multiple stores (B/S/C/I) into a longer one.
2879 //
2880 // Example: _store = StoreB[i+3]
2881 //
2882 //   RangeCheck[i+0]           RangeCheck[i+0]
2883 //   StoreB[i+0]
2884 //   RangeCheck[i+3]           RangeCheck[i+3]
2885 //   StoreB[i+1]         -->   pass:             fail:
2886 //   StoreB[i+2]               StoreI[i+0]       StoreB[i+0]
2887 //   StoreB[i+3]
2888 //
2889 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2890 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2891 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2892 // failing path.
2893 //
2894 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2895 //       - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2896 //                                       and possibly no RangeChecks remain between the stores.
2897 //       - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2898 //                              and those later RangeChecks can be removed. Example:
2899 //
2900 //                              RangeCheck[i+0]                         RangeCheck[i+0] <- before first store
2901 //                              StoreB[i+0]                             StoreB[i+0]     <- first store
2902 //                              RangeCheck[i+1]     --> smeared -->     RangeCheck[i+3] <- only RC between first and last store
2903 //                              StoreB[i+1]                             StoreB[i+1]     <- second store
2904 //                              RangeCheck[i+2]     --> removed
2905 //                              StoreB[i+2]                             StoreB[i+2]
2906 //                              RangeCheck[i+3]     --> removed
2907 //                              StoreB[i+3]                             StoreB[i+3]     <- last store
2908 //
2909 //                              Thus, it is a common pattern that between the first and last store in a chain
2910 //                              of adjacent stores there remains exactly one RangeCheck, located between the
2911 //                              first and the second store (e.g. RangeCheck[i+3]).
2912 //
2913 class MergePrimitiveArrayStores : public StackObj {
2914 private:
2915   PhaseGVN* _phase;
2916   StoreNode* _store;
2917 
2918 public:
2919   MergePrimitiveArrayStores(PhaseGVN* phase, StoreNode* store) : _phase(phase), _store(store) {}
2920 
2921   StoreNode* run();
2922 
2923 private:
2924   bool is_compatible_store(const StoreNode* other_store) const;
2925   bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
2926   bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
2927   static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out);
2928   enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
2929   static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
2930 
2931   class Status {
2932   private:
2933     StoreNode* _found_store;
2934     bool       _found_range_check;
2935 
2936     Status(StoreNode* found_store, bool found_range_check)
2937       : _found_store(found_store), _found_range_check(found_range_check) {}
2938 
2939   public:
2940     StoreNode* found_store() const { return _found_store; }
2941     bool found_range_check() const { return _found_range_check; }
2942     static Status make_failure() { return Status(nullptr, false); }
2943 
2944     static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
2945       if (cfg_status == CFGStatus::Failure) {
2946         return Status::make_failure();
2947       }
2948       return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
2949     }
2950   };
2951 
2952   Status find_adjacent_use_store(const StoreNode* def_store) const;
2953   Status find_adjacent_def_store(const StoreNode* use_store) const;
2954   Status find_use_store(const StoreNode* def_store) const;
2955   Status find_def_store(const StoreNode* use_store) const;
2956   Status find_use_store_unidirectional(const StoreNode* def_store) const;
2957   Status find_def_store_unidirectional(const StoreNode* use_store) const;
2958 
2959   void collect_merge_list(Node_List& merge_list) const;
2960   Node* make_merged_input_value(const Node_List& merge_list);
2961   StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
2962 
2963   DEBUG_ONLY( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
2964 };
2965 
2966 StoreNode* MergePrimitiveArrayStores::run() {
2967   // Check for B/S/C/I
2968   int opc = _store->Opcode();
2969   if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
2970     return nullptr;
2971   }
2972 
2973   // Only merge stores on arrays, and the stores must have the same size as the elements.
2974   const TypePtr* ptr_t = _store->adr_type();
2975   if (ptr_t == nullptr) {
2976     return nullptr;
2977   }
2978   const TypeAryPtr* aryptr_t = ptr_t->isa_aryptr();
2979   if (aryptr_t == nullptr) {
2980     return nullptr;
2981   }
2982   BasicType bt = aryptr_t->elem()->array_element_basic_type();
2983   if (!is_java_primitive(bt) ||
2984       type2aelembytes(bt) != _store->memory_size()) {
2985     return nullptr;
2986   }
2987 
2988   // The _store must be the "last" store in a chain. If we find a use we could merge with
2989   // then that use or a store further down is the "last" store.
2990   Status status_use = find_adjacent_use_store(_store);
2991   if (status_use.found_store() != nullptr) {
2992     return nullptr;
2993   }
2994 
2995   // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
2996   Status status_def = find_adjacent_def_store(_store);
2997   if (status_def.found_store() == nullptr) {
2998     return nullptr;
2999   }
3000 
3001   ResourceMark rm;
3002   Node_List merge_list;
3003   collect_merge_list(merge_list);
3004 
3005   Node* merged_input_value = make_merged_input_value(merge_list);
3006   if (merged_input_value == nullptr) { return nullptr; }
3007 
3008   StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3009 
3010   DEBUG_ONLY( if(TraceMergeStores) { trace(merge_list, merged_input_value, merged_store); } )
3011 
3012   return merged_store;
3013 }
3014 
3015 // Check compatibility between _store and other_store.
3016 bool MergePrimitiveArrayStores::is_compatible_store(const StoreNode* other_store) const {
3017   int opc = _store->Opcode();
3018   assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3019   assert(_store->adr_type()->isa_aryptr() != nullptr, "must be array store");
3020 
3021   if (other_store == nullptr ||
3022       _store->Opcode() != other_store->Opcode() ||
3023       other_store->adr_type() == nullptr ||
3024       other_store->adr_type()->isa_aryptr() == nullptr) {
3025     return false;
3026   }
3027 
3028   // Check that the size of the stores, and the array elements are all the same.
3029   const TypeAryPtr* aryptr_t1 = _store->adr_type()->is_aryptr();
3030   const TypeAryPtr* aryptr_t2 = other_store->adr_type()->is_aryptr();
3031   BasicType aryptr_bt1 = aryptr_t1->elem()->array_element_basic_type();
3032   BasicType aryptr_bt2 = aryptr_t2->elem()->array_element_basic_type();
3033   if (!is_java_primitive(aryptr_bt1) || !is_java_primitive(aryptr_bt2)) {
3034     return false;
3035   }
3036   int size1 = type2aelembytes(aryptr_bt1);
3037   int size2 = type2aelembytes(aryptr_bt2);
3038   if (size1 != size2 ||
3039       size1 != _store->memory_size() ||
3040       _store->memory_size() != other_store->memory_size()) {
3041     return false;
3042   }
3043   return true;
3044 }
3045 
3046 bool MergePrimitiveArrayStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3047   if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3048                               use_store->in(MemNode::ValueIn),
3049                               def_store->memory_size())) {
3050     return false;
3051   }
3052 
3053   ResourceMark rm;
3054   ArrayPointer array_pointer_use = ArrayPointer::make(_phase, use_store->in(MemNode::Address));
3055   ArrayPointer array_pointer_def = ArrayPointer::make(_phase, def_store->in(MemNode::Address));
3056   if (!array_pointer_def.is_adjacent_to_and_before(array_pointer_use, use_store->memory_size())) {
3057     return false;
3058   }
3059 
3060   return true;
3061 }
3062 
3063 bool MergePrimitiveArrayStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3064   // Pattern: [n1 = ConI, n2 = ConI]
3065   if (n1->Opcode() == Op_ConI) {
3066     return n2->Opcode() == Op_ConI;
3067   }
3068 
3069   // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3070 #ifndef VM_LITTLE_ENDIAN
3071   // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3072   // Swapping n1 with n2 gives same pattern as on little endian platforms.
3073   swap(n1, n2);
3074 #endif // !VM_LITTLE_ENDIAN
3075   Node const* base_n2;
3076   jint shift_n2;
3077   if (!is_con_RShift(n2, base_n2, shift_n2)) {
3078     return false;
3079   }
3080   if (n1->Opcode() == Op_ConvL2I) {
3081     // look through
3082     n1 = n1->in(1);
3083   }
3084   Node const* base_n1;
3085   jint shift_n1;
3086   if (n1 == base_n2) {
3087     // n1 = base = base >> 0
3088     base_n1 = n1;
3089     shift_n1 = 0;
3090   } else if (!is_con_RShift(n1, base_n1, shift_n1)) {
3091     return false;
3092   }
3093   int bits_per_store = memory_size * 8;
3094   if (base_n1 != base_n2 ||
3095       shift_n1 + bits_per_store != shift_n2 ||
3096       shift_n1 % bits_per_store != 0) {
3097     return false;
3098   }
3099 
3100   // both load from same value with correct shift
3101   return true;
3102 }
3103 
3104 // Detect pattern: n = base_out >> shift_out
3105 bool MergePrimitiveArrayStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out) {
3106   assert(n != nullptr, "precondition");
3107 
3108   int opc = n->Opcode();
3109   if (opc == Op_ConvL2I) {
3110     n = n->in(1);
3111     opc = n->Opcode();
3112   }
3113 
3114   if ((opc == Op_RShiftI ||
3115        opc == Op_RShiftL ||
3116        opc == Op_URShiftI ||
3117        opc == Op_URShiftL) &&
3118       n->in(2)->is_ConI()) {
3119     base_out = n->in(1);
3120     shift_out = n->in(2)->get_int();
3121     // The shift must be positive:
3122     return shift_out >= 0;
3123   }
3124   return false;
3125 }
3126 
3127 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3128 MergePrimitiveArrayStores::CFGStatus MergePrimitiveArrayStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3129   assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3130 
3131   Node* ctrl_use = use_store->in(MemNode::Control);
3132   Node* ctrl_def = def_store->in(MemNode::Control);
3133   if (ctrl_use == nullptr || ctrl_def == nullptr) {
3134     return CFGStatus::Failure;
3135   }
3136 
3137   if (ctrl_use == ctrl_def) {
3138     // Same ctrl -> no RangeCheck in between.
3139     // Check: use_store must be the only use of def_store.
3140     if (def_store->outcnt() > 1) {
3141       return CFGStatus::Failure;
3142     }
3143     return CFGStatus::SuccessNoRangeCheck;
3144   }
3145 
3146   // Different ctrl -> could have RangeCheck in between.
3147   // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3148   //        2. ctrl separated by RangeCheck.
3149   if (def_store->outcnt() != 2) {
3150     return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3151   }
3152   int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3153   Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3154   if (merge_mem == nullptr ||
3155       merge_mem->outcnt() != 1) {
3156     return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3157   }
3158   if (!ctrl_use->is_IfProj() ||
3159       !ctrl_use->in(0)->is_RangeCheck() ||
3160       ctrl_use->in(0)->outcnt() != 2) {
3161     return CFGStatus::Failure; // Not RangeCheck.
3162   }
3163   ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3164   Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3165   if (trap != merge_mem->unique_out() ||
3166       ctrl_use->in(0)->in(0) != ctrl_def) {
3167     return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3168   }
3169 
3170   return CFGStatus::SuccessWithRangeCheck;
3171 }
3172 
3173 MergePrimitiveArrayStores::Status MergePrimitiveArrayStores::find_adjacent_use_store(const StoreNode* def_store) const {
3174   Status status_use = find_use_store(def_store);
3175   StoreNode* use_store = status_use.found_store();
3176   if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3177     return Status::make_failure();
3178   }
3179   return status_use;
3180 }
3181 
3182 MergePrimitiveArrayStores::Status MergePrimitiveArrayStores::find_adjacent_def_store(const StoreNode* use_store) const {
3183   Status status_def = find_def_store(use_store);
3184   StoreNode* def_store = status_def.found_store();
3185   if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3186     return Status::make_failure();
3187   }
3188   return status_def;
3189 }
3190 
3191 MergePrimitiveArrayStores::Status MergePrimitiveArrayStores::find_use_store(const StoreNode* def_store) const {
3192   Status status_use = find_use_store_unidirectional(def_store);
3193 
3194 #ifdef ASSERT
3195   StoreNode* use_store = status_use.found_store();
3196   if (use_store != nullptr) {
3197     Status status_def = find_def_store_unidirectional(use_store);
3198     assert(status_def.found_store() == def_store &&
3199            status_def.found_range_check() == status_use.found_range_check(),
3200            "find_use_store and find_def_store must be symmetric");
3201   }
3202 #endif
3203 
3204   return status_use;
3205 }
3206 
3207 MergePrimitiveArrayStores::Status MergePrimitiveArrayStores::find_def_store(const StoreNode* use_store) const {
3208   Status status_def = find_def_store_unidirectional(use_store);
3209 
3210 #ifdef ASSERT
3211   StoreNode* def_store = status_def.found_store();
3212   if (def_store != nullptr) {
3213     Status status_use = find_use_store_unidirectional(def_store);
3214     assert(status_use.found_store() == use_store &&
3215            status_use.found_range_check() == status_def.found_range_check(),
3216            "find_use_store and find_def_store must be symmetric");
3217   }
3218 #endif
3219 
3220   return status_def;
3221 }
3222 
3223 MergePrimitiveArrayStores::Status MergePrimitiveArrayStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3224   assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3225 
3226   for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3227     StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3228     if (is_compatible_store(use_store)) {
3229       return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3230     }
3231   }
3232 
3233   return Status::make_failure();
3234 }
3235 
3236 MergePrimitiveArrayStores::Status MergePrimitiveArrayStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3237   assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3238 
3239   StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3240   if (!is_compatible_store(def_store)) {
3241     return Status::make_failure();
3242   }
3243 
3244   return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3245 }
3246 
3247 void MergePrimitiveArrayStores::collect_merge_list(Node_List& merge_list) const {
3248   // The merged store can be at most 8 bytes.
3249   const uint merge_list_max_size = 8 / _store->memory_size();
3250   assert(merge_list_max_size >= 2 &&
3251          merge_list_max_size <= 8 &&
3252          is_power_of_2(merge_list_max_size),
3253          "must be 2, 4 or 8");
3254 
3255   // Traverse up the chain of adjacent def stores.
3256   StoreNode* current = _store;
3257   merge_list.push(current);
3258   while (current != nullptr && merge_list.size() < merge_list_max_size) {
3259     Status status = find_adjacent_def_store(current);
3260     current = status.found_store();
3261     if (current != nullptr) {
3262       merge_list.push(current);
3263 
3264       // We can have at most one RangeCheck.
3265       if (status.found_range_check()) {
3266         break;
3267       }
3268     }
3269   }
3270 
3271   // Truncate the merge_list to a power of 2.
3272   const uint pow2size = round_down_power_of_2(merge_list.size());
3273   assert(pow2size >= 2, "must be merging at least 2 stores");
3274   while (merge_list.size() > pow2size) { merge_list.pop(); }
3275 }
3276 
3277 // Merge the input values of the smaller stores to a single larger input value.
3278 Node* MergePrimitiveArrayStores::make_merged_input_value(const Node_List& merge_list) {
3279   int new_memory_size = _store->memory_size() * merge_list.size();
3280   Node* first = merge_list.at(merge_list.size()-1);
3281   Node* merged_input_value = nullptr;
3282   if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3283     // Pattern: [ConI, ConI, ...] -> new constant
3284     jlong con = 0;
3285     jlong bits_per_store = _store->memory_size() * 8;
3286     jlong mask = (((jlong)1) << bits_per_store) - 1;
3287     for (uint i = 0; i < merge_list.size(); i++) {
3288       jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3289 #ifdef VM_LITTLE_ENDIAN
3290       con = con << bits_per_store;
3291       con = con | (mask & con_i);
3292 #else // VM_LITTLE_ENDIAN
3293       con_i = (mask & con_i) << (i * bits_per_store);
3294       con = con | con_i;
3295 #endif // VM_LITTLE_ENDIAN
3296     }
3297     merged_input_value = _phase->longcon(con);
3298   } else {
3299     // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3300     //             |                                  |
3301     //           _store                             first
3302     //
3303     Node* hi = _store->in(MemNode::ValueIn);
3304     Node* lo = first->in(MemNode::ValueIn);
3305 #ifndef VM_LITTLE_ENDIAN
3306     // `_store` and `first` are swapped in the diagram above
3307     swap(hi, lo);
3308 #endif // !VM_LITTLE_ENDIAN
3309     Node const* hi_base;
3310     jint hi_shift;
3311     merged_input_value = lo;
3312     bool is_true = is_con_RShift(hi, hi_base, hi_shift);
3313     assert(is_true, "must detect con RShift");
3314     if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3315       // look through
3316       merged_input_value = merged_input_value->in(1);
3317     }
3318     if (merged_input_value != hi_base) {
3319       // merged_input_value is not the base
3320       return nullptr;
3321     }
3322   }
3323 
3324   if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3325     // Example:
3326     //
3327     //   long base = ...;
3328     //   a[0] = (byte)(base >> 0);
3329     //   a[1] = (byte)(base >> 8);
3330     //
3331     merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3332   }
3333 
3334   assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3335          (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3336          "merged_input_value is either int or long, and new_memory_size is small enough");
3337 
3338   return merged_input_value;
3339 }
3340 
3341 //                                                                                                          //
3342 // first_ctrl    first_mem   first_adr                first_ctrl    first_mem         first_adr             //
3343 //  |                |           |                     |                |                 |                 //
3344 //  |                |           |                     |                +---------------+ |                 //
3345 //  |                |           |                     |                |               | |                 //
3346 //  |                | +---------+                     |                | +---------------+                 //
3347 //  |                | |                               |                | |             | |                 //
3348 //  +--------------+ | |  v1                           +------------------------------+ | |  v1             //
3349 //  |              | | |  |                            |                | |           | | |  |              //
3350 // RangeCheck     first_store                         RangeCheck        | |          first_store            //
3351 //  |                |  |                              |                | |                |                //
3352 // last_ctrl         |  +----> unc_trap               last_ctrl         | |                +----> unc_trap  //
3353 //  |                |                       ===>      |                | |                                 //
3354 //  +--------------+ | a2 v2                           |                | |                                 //
3355 //  |              | | |  |                            |                | |                                 //
3356 //  |             second_store                         |                | |                                 //
3357 //  |                |                                 |                | | [v1 v2   ...   vn]              //
3358 // ...              ...                                |                | |         |                       //
3359 //  |                |                                 |                | |         v                       //
3360 //  +--------------+ | an vn                           +--------------+ | | merged_input_value              //
3361 //                 | | |  |                                           | | |  |                              //
3362 //                last_store (= _store)                              merged_store                           //
3363 //                                                                                                          //
3364 StoreNode* MergePrimitiveArrayStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3365   Node* first_store = merge_list.at(merge_list.size()-1);
3366   Node* last_ctrl   = _store->in(MemNode::Control); // after (optional) RangeCheck
3367   Node* first_mem   = first_store->in(MemNode::Memory);
3368   Node* first_adr   = first_store->in(MemNode::Address);
3369 
3370   const TypePtr* new_adr_type = _store->adr_type();
3371 
3372   int new_memory_size = _store->memory_size() * merge_list.size();
3373   BasicType bt = T_ILLEGAL;
3374   switch (new_memory_size) {
3375     case 2: bt = T_SHORT; break;
3376     case 4: bt = T_INT;   break;
3377     case 8: bt = T_LONG;  break;
3378   }
3379 
3380   StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3381                                             new_adr_type, merged_input_value, bt, MemNode::unordered);
3382 
3383   // Marking the store mismatched is sufficient to prevent reordering, since array stores
3384   // are all on the same slice. Hence, we need no barriers.
3385   merged_store->set_mismatched_access();
3386 
3387   // Constants above may now also be be packed -> put candidate on worklist
3388   _phase->is_IterGVN()->_worklist.push(first_mem);
3389 
3390   return merged_store;
3391 }
3392 
3393 #ifdef ASSERT
3394 void MergePrimitiveArrayStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3395   stringStream ss;
3396   ss.print_cr("[TraceMergeStores]: Replace");
3397   for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3398     merge_list.at(i)->dump("\n", false, &ss);
3399   }
3400   ss.print_cr("[TraceMergeStores]: with");
3401   merged_input_value->dump("\n", false, &ss);
3402   merged_store->dump("\n", false, &ss);
3403   tty->print("%s", ss.as_string());
3404 }
3405 #endif
3406 
3407 //------------------------------Ideal------------------------------------------
3408 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3409 // When a store immediately follows a relevant allocation/initialization,
3410 // try to capture it into the initialization, or hoist it above.
3411 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3412   Node* p = MemNode::Ideal_common(phase, can_reshape);
3413   if (p)  return (p == NodeSentinel) ? nullptr : p;
3414 
3415   Node* mem     = in(MemNode::Memory);
3416   Node* address = in(MemNode::Address);
3417   Node* value   = in(MemNode::ValueIn);
3418   // Back-to-back stores to same address?  Fold em up.  Generally
3419   // unsafe if I have intervening uses...  Also disallowed for StoreCM
3420   // since they must follow each StoreP operation.  Redundant StoreCMs
3421   // are eliminated just before matching in final_graph_reshape.
3422   {
3423     Node* st = mem;
3424     // If Store 'st' has more than one use, we cannot fold 'st' away.
3425     // For example, 'st' might be the final state at a conditional
3426     // return.  Or, 'st' might be used by some node which is live at
3427     // the same time 'st' is live, which might be unschedulable.  So,
3428     // require exactly ONE user until such time as we clone 'mem' for
3429     // each of 'mem's uses (thus making the exactly-1-user-rule hold
3430     // true).
3431     while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
3432       // Looking at a dead closed cycle of memory?
3433       assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3434       assert(Opcode() == st->Opcode() ||
3435              st->Opcode() == Op_StoreVector ||
3436              Opcode() == Op_StoreVector ||
3437              st->Opcode() == Op_StoreVectorScatter ||
3438              Opcode() == Op_StoreVectorScatter ||
3439              phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3440              (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3441              (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3442              (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3443              "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3444 
3445       if (st->in(MemNode::Address)->eqv_uncast(address) &&
3446           st->as_Store()->memory_size() <= this->memory_size()) {
3447         Node* use = st->raw_out(0);
3448         if (phase->is_IterGVN()) {
3449           phase->is_IterGVN()->rehash_node_delayed(use);
3450         }
3451         // It's OK to do this in the parser, since DU info is always accurate,
3452         // and the parser always refers to nodes via SafePointNode maps.
3453         use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3454         return this;
3455       }
3456       st = st->in(MemNode::Memory);
3457     }
3458   }
3459 
3460 
3461   // Capture an unaliased, unconditional, simple store into an initializer.
3462   // Or, if it is independent of the allocation, hoist it above the allocation.
3463   if (ReduceFieldZeroing && /*can_reshape &&*/
3464       mem->is_Proj() && mem->in(0)->is_Initialize()) {
3465     InitializeNode* init = mem->in(0)->as_Initialize();
3466     intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3467     if (offset > 0) {
3468       Node* moved = init->capture_store(this, offset, phase, can_reshape);
3469       // If the InitializeNode captured me, it made a raw copy of me,
3470       // and I need to disappear.
3471       if (moved != nullptr) {
3472         // %%% hack to ensure that Ideal returns a new node:
3473         mem = MergeMemNode::make(mem);
3474         return mem;             // fold me away
3475       }
3476     }
3477   }
3478 
3479   // Fold reinterpret cast into memory operation:
3480   //    StoreX mem (MoveY2X v) => StoreY mem v
3481   if (value->is_Move()) {
3482     const Type* vt = value->in(1)->bottom_type();
3483     if (has_reinterpret_variant(vt)) {
3484       if (phase->C->post_loop_opts_phase()) {
3485         return convert_to_reinterpret_store(*phase, value->in(1), vt);
3486       } else {
3487         phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3488       }
3489     }
3490   }
3491 
3492   if (MergeStores && UseUnalignedAccesses) {
3493     if (phase->C->post_loop_opts_phase()) {
3494       MergePrimitiveArrayStores merge(phase, this);
3495       Node* progress = merge.run();
3496       if (progress != nullptr) { return progress; }
3497     } else {
3498       phase->C->record_for_post_loop_opts_igvn(this);
3499     }
3500   }
3501 
3502   return nullptr;                  // No further progress
3503 }
3504 
3505 //------------------------------Value-----------------------------------------
3506 const Type* StoreNode::Value(PhaseGVN* phase) const {
3507   // Either input is TOP ==> the result is TOP
3508   const Type *t1 = phase->type( in(MemNode::Memory) );
3509   if( t1 == Type::TOP ) return Type::TOP;
3510   const Type *t2 = phase->type( in(MemNode::Address) );
3511   if( t2 == Type::TOP ) return Type::TOP;
3512   const Type *t3 = phase->type( in(MemNode::ValueIn) );
3513   if( t3 == Type::TOP ) return Type::TOP;
3514   return Type::MEMORY;
3515 }
3516 
3517 //------------------------------Identity---------------------------------------
3518 // Remove redundant stores:
3519 //   Store(m, p, Load(m, p)) changes to m.
3520 //   Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3521 Node* StoreNode::Identity(PhaseGVN* phase) {
3522   Node* mem = in(MemNode::Memory);
3523   Node* adr = in(MemNode::Address);
3524   Node* val = in(MemNode::ValueIn);
3525 
3526   Node* result = this;
3527 
3528   // Load then Store?  Then the Store is useless
3529   if (val->is_Load() &&
3530       val->in(MemNode::Address)->eqv_uncast(adr) &&
3531       val->in(MemNode::Memory )->eqv_uncast(mem) &&
3532       val->as_Load()->store_Opcode() == Opcode()) {
3533     // Ensure vector type is the same
3534     if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3535       result = mem;
3536     }
3537   }
3538 
3539   // Two stores in a row of the same value?
3540   if (result == this &&
3541       mem->is_Store() &&
3542       mem->in(MemNode::Address)->eqv_uncast(adr) &&
3543       mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3544       mem->Opcode() == Opcode()) {
3545     if (!is_StoreVector()) {
3546       result = mem;
3547     } else {
3548       const StoreVectorNode* store_vector = as_StoreVector();
3549       const StoreVectorNode* mem_vector = mem->as_StoreVector();
3550       const Node* store_indices = store_vector->indices();
3551       const Node* mem_indices = mem_vector->indices();
3552       const Node* store_mask = store_vector->mask();
3553       const Node* mem_mask = mem_vector->mask();
3554       // Ensure types, indices, and masks match
3555       if (store_vector->vect_type() == mem_vector->vect_type() &&
3556           ((store_indices == nullptr) == (mem_indices == nullptr) &&
3557            (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3558           ((store_mask == nullptr) == (mem_mask == nullptr) &&
3559            (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3560         result = mem;
3561       }
3562     }
3563   }
3564 
3565   // Store of zero anywhere into a freshly-allocated object?
3566   // Then the store is useless.
3567   // (It must already have been captured by the InitializeNode.)
3568   if (result == this &&
3569       ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
3570     // a newly allocated object is already all-zeroes everywhere
3571     if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
3572       result = mem;
3573     }
3574 
3575     if (result == this) {
3576       // the store may also apply to zero-bits in an earlier object
3577       Node* prev_mem = find_previous_store(phase);
3578       // Steps (a), (b):  Walk past independent stores to find an exact match.
3579       if (prev_mem != nullptr) {
3580         Node* prev_val = can_see_stored_value(prev_mem, phase);
3581         if (prev_val != nullptr && prev_val == val) {
3582           // prev_val and val might differ by a cast; it would be good
3583           // to keep the more informative of the two.
3584           result = mem;
3585         }
3586       }
3587     }
3588   }
3589 
3590   PhaseIterGVN* igvn = phase->is_IterGVN();
3591   if (result != this && igvn != nullptr) {
3592     MemBarNode* trailing = trailing_membar();
3593     if (trailing != nullptr) {
3594 #ifdef ASSERT
3595       const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3596       assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3597 #endif
3598       trailing->remove(igvn);
3599     }
3600   }
3601 
3602   return result;
3603 }
3604 
3605 //------------------------------match_edge-------------------------------------
3606 // Do we Match on this edge index or not?  Match only memory & value
3607 uint StoreNode::match_edge(uint idx) const {
3608   return idx == MemNode::Address || idx == MemNode::ValueIn;
3609 }
3610 
3611 //------------------------------cmp--------------------------------------------
3612 // Do not common stores up together.  They generally have to be split
3613 // back up anyways, so do not bother.
3614 bool StoreNode::cmp( const Node &n ) const {
3615   return (&n == this);          // Always fail except on self
3616 }
3617 
3618 //------------------------------Ideal_masked_input-----------------------------
3619 // Check for a useless mask before a partial-word store
3620 // (StoreB ... (AndI valIn conIa) )
3621 // If (conIa & mask == mask) this simplifies to
3622 // (StoreB ... (valIn) )
3623 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3624   Node *val = in(MemNode::ValueIn);
3625   if( val->Opcode() == Op_AndI ) {
3626     const TypeInt *t = phase->type( val->in(2) )->isa_int();
3627     if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3628       set_req_X(MemNode::ValueIn, val->in(1), phase);
3629       return this;
3630     }
3631   }
3632   return nullptr;
3633 }
3634 
3635 
3636 //------------------------------Ideal_sign_extended_input----------------------
3637 // Check for useless sign-extension before a partial-word store
3638 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
3639 // If (conIL == conIR && conIR <= num_bits)  this simplifies to
3640 // (StoreB ... (valIn) )
3641 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
3642   Node *val = in(MemNode::ValueIn);
3643   if( val->Opcode() == Op_RShiftI ) {
3644     const TypeInt *t = phase->type( val->in(2) )->isa_int();
3645     if( t && t->is_con() && (t->get_con() <= num_bits) ) {
3646       Node *shl = val->in(1);
3647       if( shl->Opcode() == Op_LShiftI ) {
3648         const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
3649         if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
3650           set_req_X(MemNode::ValueIn, shl->in(1), phase);
3651           return this;
3652         }
3653       }
3654     }
3655   }
3656   return nullptr;
3657 }
3658 
3659 //------------------------------value_never_loaded-----------------------------------
3660 // Determine whether there are any possible loads of the value stored.
3661 // For simplicity, we actually check if there are any loads from the
3662 // address stored to, not just for loads of the value stored by this node.
3663 //
3664 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
3665   Node *adr = in(Address);
3666   const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
3667   if (adr_oop == nullptr)
3668     return false;
3669   if (!adr_oop->is_known_instance_field())
3670     return false; // if not a distinct instance, there may be aliases of the address
3671   for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
3672     Node *use = adr->fast_out(i);
3673     if (use->is_Load() || use->is_LoadStore()) {
3674       return false;
3675     }
3676   }
3677   return true;
3678 }
3679 
3680 MemBarNode* StoreNode::trailing_membar() const {
3681   if (is_release()) {
3682     MemBarNode* trailing_mb = nullptr;
3683     for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3684       Node* u = fast_out(i);
3685       if (u->is_MemBar()) {
3686         if (u->as_MemBar()->trailing_store()) {
3687           assert(u->Opcode() == Op_MemBarVolatile, "");
3688           assert(trailing_mb == nullptr, "only one");
3689           trailing_mb = u->as_MemBar();
3690 #ifdef ASSERT
3691           Node* leading = u->as_MemBar()->leading_membar();
3692           assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3693           assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3694           assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3695 #endif
3696         } else {
3697           assert(u->as_MemBar()->standalone(), "");
3698         }
3699       }
3700     }
3701     return trailing_mb;
3702   }
3703   return nullptr;
3704 }
3705 
3706 
3707 //=============================================================================
3708 //------------------------------Ideal------------------------------------------
3709 // If the store is from an AND mask that leaves the low bits untouched, then
3710 // we can skip the AND operation.  If the store is from a sign-extension
3711 // (a left shift, then right shift) we can skip both.
3712 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3713   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3714   if( progress != nullptr ) return progress;
3715 
3716   progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3717   if( progress != nullptr ) return progress;
3718 
3719   // Finally check the default case
3720   return StoreNode::Ideal(phase, can_reshape);
3721 }
3722 
3723 //=============================================================================
3724 //------------------------------Ideal------------------------------------------
3725 // If the store is from an AND mask that leaves the low bits untouched, then
3726 // we can skip the AND operation
3727 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3728   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3729   if( progress != nullptr ) return progress;
3730 
3731   progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3732   if( progress != nullptr ) return progress;
3733 
3734   // Finally check the default case
3735   return StoreNode::Ideal(phase, can_reshape);
3736 }
3737 
3738 //=============================================================================
3739 //------------------------------Identity---------------------------------------
3740 Node* StoreCMNode::Identity(PhaseGVN* phase) {
3741   // No need to card mark when storing a null ptr
3742   Node* my_store = in(MemNode::OopStore);
3743   if (my_store->is_Store()) {
3744     const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
3745     if( t1 == TypePtr::NULL_PTR ) {
3746       return in(MemNode::Memory);
3747     }
3748   }
3749   return this;
3750 }
3751 
3752 //=============================================================================
3753 //------------------------------Ideal---------------------------------------
3754 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
3755   Node* progress = StoreNode::Ideal(phase, can_reshape);
3756   if (progress != nullptr) return progress;
3757 
3758   Node* my_store = in(MemNode::OopStore);
3759   if (my_store->is_MergeMem()) {
3760     Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
3761     set_req_X(MemNode::OopStore, mem, phase);
3762     return this;
3763   }
3764 
3765   return nullptr;
3766 }
3767 
3768 //------------------------------Value-----------------------------------------
3769 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
3770   // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
3771   // If extra input is TOP ==> the result is TOP
3772   const Type* t = phase->type(in(MemNode::OopStore));
3773   if (t == Type::TOP) {
3774     return Type::TOP;
3775   }
3776   return StoreNode::Value(phase);
3777 }
3778 
3779 
3780 //=============================================================================
3781 //----------------------------------SCMemProjNode------------------------------
3782 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3783 {
3784   if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
3785     return Type::TOP;
3786   }
3787   return bottom_type();
3788 }
3789 
3790 //=============================================================================
3791 //----------------------------------LoadStoreNode------------------------------
3792 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3793   : Node(required),
3794     _type(rt),
3795     _adr_type(at),
3796     _barrier_data(0)
3797 {
3798   init_req(MemNode::Control, c  );
3799   init_req(MemNode::Memory , mem);
3800   init_req(MemNode::Address, adr);
3801   init_req(MemNode::ValueIn, val);
3802   init_class_id(Class_LoadStore);
3803 }
3804 
3805 //------------------------------Value-----------------------------------------
3806 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3807   // Either input is TOP ==> the result is TOP
3808   if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3809     return Type::TOP;
3810   }
3811   const Type* t = phase->type(in(MemNode::Memory));
3812   if (t == Type::TOP) {
3813     return Type::TOP;
3814   }
3815   t = phase->type(in(MemNode::Address));
3816   if (t == Type::TOP) {
3817     return Type::TOP;
3818   }
3819   t = phase->type(in(MemNode::ValueIn));
3820   if (t == Type::TOP) {
3821     return Type::TOP;
3822   }
3823   return bottom_type();
3824 }
3825 
3826 uint LoadStoreNode::ideal_reg() const {
3827   return _type->ideal_reg();
3828 }
3829 
3830 // This method conservatively checks if the result of a LoadStoreNode is
3831 // used, that is, if it returns true, then it is definitely the case that
3832 // the result of the node is not needed.
3833 // For example, GetAndAdd can be matched into a lock_add instead of a
3834 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
3835 bool LoadStoreNode::result_not_used() const {
3836   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3837     Node *x = fast_out(i);
3838     if (x->Opcode() == Op_SCMemProj) {
3839       continue;
3840     }
3841     if (x->bottom_type() == TypeTuple::MEMBAR &&
3842         !x->is_Call() &&
3843         x->Opcode() != Op_Blackhole) {
3844       continue;
3845     }
3846     return false;
3847   }
3848   return true;
3849 }
3850 
3851 MemBarNode* LoadStoreNode::trailing_membar() const {
3852   MemBarNode* trailing = nullptr;
3853   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3854     Node* u = fast_out(i);
3855     if (u->is_MemBar()) {
3856       if (u->as_MemBar()->trailing_load_store()) {
3857         assert(u->Opcode() == Op_MemBarAcquire, "");
3858         assert(trailing == nullptr, "only one");
3859         trailing = u->as_MemBar();
3860 #ifdef ASSERT
3861         Node* leading = trailing->leading_membar();
3862         assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3863         assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3864         assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3865 #endif
3866       } else {
3867         assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3868       }
3869     }
3870   }
3871 
3872   return trailing;
3873 }
3874 
3875 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3876 
3877 //=============================================================================
3878 //----------------------------------LoadStoreConditionalNode--------------------
3879 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
3880   init_req(ExpectedIn, ex );
3881 }
3882 
3883 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3884   // Either input is TOP ==> the result is TOP
3885   const Type* t = phase->type(in(ExpectedIn));
3886   if (t == Type::TOP) {
3887     return Type::TOP;
3888   }
3889   return LoadStoreNode::Value(phase);
3890 }
3891 
3892 //=============================================================================
3893 //-------------------------------adr_type--------------------------------------
3894 const TypePtr* ClearArrayNode::adr_type() const {
3895   Node *adr = in(3);
3896   if (adr == nullptr)  return nullptr; // node is dead
3897   return MemNode::calculate_adr_type(adr->bottom_type());
3898 }
3899 
3900 //------------------------------match_edge-------------------------------------
3901 // Do we Match on this edge index or not?  Do not match memory
3902 uint ClearArrayNode::match_edge(uint idx) const {
3903   return idx > 1;
3904 }
3905 
3906 //------------------------------Identity---------------------------------------
3907 // Clearing a zero length array does nothing
3908 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3909   return phase->type(in(2))->higher_equal(TypeX::ZERO)  ? in(1) : this;
3910 }
3911 
3912 //------------------------------Idealize---------------------------------------
3913 // Clearing a short array is faster with stores
3914 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3915   // Already know this is a large node, do not try to ideal it
3916   if (_is_large) return nullptr;
3917 
3918   const int unit = BytesPerLong;
3919   const TypeX* t = phase->type(in(2))->isa_intptr_t();
3920   if (!t)  return nullptr;
3921   if (!t->is_con())  return nullptr;
3922   intptr_t raw_count = t->get_con();
3923   intptr_t size = raw_count;
3924   if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3925   // Clearing nothing uses the Identity call.
3926   // Negative clears are possible on dead ClearArrays
3927   // (see jck test stmt114.stmt11402.val).
3928   if (size <= 0 || size % unit != 0)  return nullptr;
3929   intptr_t count = size / unit;
3930   // Length too long; communicate this to matchers and assemblers.
3931   // Assemblers are responsible to produce fast hardware clears for it.
3932   if (size > InitArrayShortSize) {
3933     return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
3934   } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3935     return nullptr;
3936   }
3937   if (!IdealizeClearArrayNode) return nullptr;
3938   Node *mem = in(1);
3939   if( phase->type(mem)==Type::TOP ) return nullptr;
3940   Node *adr = in(3);
3941   const Type* at = phase->type(adr);
3942   if( at==Type::TOP ) return nullptr;
3943   const TypePtr* atp = at->isa_ptr();
3944   // adjust atp to be the correct array element address type
3945   if (atp == nullptr)  atp = TypePtr::BOTTOM;
3946   else              atp = atp->add_offset(Type::OffsetBot);
3947   // Get base for derived pointer purposes
3948   if( adr->Opcode() != Op_AddP ) Unimplemented();
3949   Node *base = adr->in(1);
3950 
3951   Node *zero = phase->makecon(TypeLong::ZERO);
3952   Node *off  = phase->MakeConX(BytesPerLong);
3953   mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3954   count--;
3955   while( count-- ) {
3956     mem = phase->transform(mem);
3957     adr = phase->transform(new AddPNode(base,adr,off));
3958     mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3959   }
3960   return mem;
3961 }
3962 
3963 //----------------------------step_through----------------------------------
3964 // Return allocation input memory edge if it is different instance
3965 // or itself if it is the one we are looking for.
3966 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
3967   Node* n = *np;
3968   assert(n->is_ClearArray(), "sanity");
3969   intptr_t offset;
3970   AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3971   // This method is called only before Allocate nodes are expanded
3972   // during macro nodes expansion. Before that ClearArray nodes are
3973   // only generated in PhaseMacroExpand::generate_arraycopy() (before
3974   // Allocate nodes are expanded) which follows allocations.
3975   assert(alloc != nullptr, "should have allocation");
3976   if (alloc->_idx == instance_id) {
3977     // Can not bypass initialization of the instance we are looking for.
3978     return false;
3979   }
3980   // Otherwise skip it.
3981   InitializeNode* init = alloc->initialization();
3982   if (init != nullptr)
3983     *np = init->in(TypeFunc::Memory);
3984   else
3985     *np = alloc->in(TypeFunc::Memory);
3986   return true;
3987 }
3988 
3989 //----------------------------clear_memory-------------------------------------
3990 // Generate code to initialize object storage to zero.
3991 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3992                                    intptr_t start_offset,
3993                                    Node* end_offset,
3994                                    PhaseGVN* phase) {
3995   intptr_t offset = start_offset;
3996 
3997   int unit = BytesPerLong;
3998   if ((offset % unit) != 0) {
3999     Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4000     adr = phase->transform(adr);
4001     const TypePtr* atp = TypeRawPtr::BOTTOM;
4002     mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4003     mem = phase->transform(mem);
4004     offset += BytesPerInt;
4005   }
4006   assert((offset % unit) == 0, "");
4007 
4008   // Initialize the remaining stuff, if any, with a ClearArray.
4009   return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
4010 }
4011 
4012 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4013                                    Node* start_offset,
4014                                    Node* end_offset,
4015                                    PhaseGVN* phase) {
4016   if (start_offset == end_offset) {
4017     // nothing to do
4018     return mem;
4019   }
4020 
4021   int unit = BytesPerLong;
4022   Node* zbase = start_offset;
4023   Node* zend  = end_offset;
4024 
4025   // Scale to the unit required by the CPU:
4026   if (!Matcher::init_array_count_is_in_bytes) {
4027     Node* shift = phase->intcon(exact_log2(unit));
4028     zbase = phase->transform(new URShiftXNode(zbase, shift) );
4029     zend  = phase->transform(new URShiftXNode(zend,  shift) );
4030   }
4031 
4032   // Bulk clear double-words
4033   Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4034   Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4035   mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
4036   return phase->transform(mem);
4037 }
4038 
4039 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4040                                    intptr_t start_offset,
4041                                    intptr_t end_offset,
4042                                    PhaseGVN* phase) {
4043   if (start_offset == end_offset) {
4044     // nothing to do
4045     return mem;
4046   }
4047 
4048   assert((end_offset % BytesPerInt) == 0, "odd end offset");
4049   intptr_t done_offset = end_offset;
4050   if ((done_offset % BytesPerLong) != 0) {
4051     done_offset -= BytesPerInt;
4052   }
4053   if (done_offset > start_offset) {
4054     mem = clear_memory(ctl, mem, dest,
4055                        start_offset, phase->MakeConX(done_offset), phase);
4056   }
4057   if (done_offset < end_offset) { // emit the final 32-bit store
4058     Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4059     adr = phase->transform(adr);
4060     const TypePtr* atp = TypeRawPtr::BOTTOM;
4061     mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4062     mem = phase->transform(mem);
4063     done_offset += BytesPerInt;
4064   }
4065   assert(done_offset == end_offset, "");
4066   return mem;
4067 }
4068 
4069 //=============================================================================
4070 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4071   : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4072     _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4073 #ifdef ASSERT
4074   , _pair_idx(0)
4075 #endif
4076 {
4077   init_class_id(Class_MemBar);
4078   Node* top = C->top();
4079   init_req(TypeFunc::I_O,top);
4080   init_req(TypeFunc::FramePtr,top);
4081   init_req(TypeFunc::ReturnAdr,top);
4082   if (precedent != nullptr)
4083     init_req(TypeFunc::Parms, precedent);
4084 }
4085 
4086 //------------------------------cmp--------------------------------------------
4087 uint MemBarNode::hash() const { return NO_HASH; }
4088 bool MemBarNode::cmp( const Node &n ) const {
4089   return (&n == this);          // Always fail except on self
4090 }
4091 
4092 //------------------------------make-------------------------------------------
4093 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4094   switch (opcode) {
4095   case Op_MemBarAcquire:     return new MemBarAcquireNode(C, atp, pn);
4096   case Op_LoadFence:         return new LoadFenceNode(C, atp, pn);
4097   case Op_MemBarRelease:     return new MemBarReleaseNode(C, atp, pn);
4098   case Op_StoreFence:        return new StoreFenceNode(C, atp, pn);
4099   case Op_MemBarStoreStore:  return new MemBarStoreStoreNode(C, atp, pn);
4100   case Op_StoreStoreFence:   return new StoreStoreFenceNode(C, atp, pn);
4101   case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4102   case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4103   case Op_MemBarVolatile:    return new MemBarVolatileNode(C, atp, pn);
4104   case Op_MemBarCPUOrder:    return new MemBarCPUOrderNode(C, atp, pn);
4105   case Op_OnSpinWait:        return new OnSpinWaitNode(C, atp, pn);
4106   case Op_Initialize:        return new InitializeNode(C, atp, pn);
4107   default: ShouldNotReachHere(); return nullptr;
4108   }
4109 }
4110 
4111 void MemBarNode::remove(PhaseIterGVN *igvn) {
4112   if (outcnt() != 2) {
4113     assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4114     assert(outcnt() == 1, "Only control then");
4115   }
4116   if (trailing_store() || trailing_load_store()) {
4117     MemBarNode* leading = leading_membar();
4118     if (leading != nullptr) {
4119       assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4120       leading->remove(igvn);
4121     }
4122   }
4123   if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4124     igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4125   }
4126   if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4127     igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4128   }
4129 }
4130 
4131 //------------------------------Ideal------------------------------------------
4132 // Return a node which is more "ideal" than the current node.  Strip out
4133 // control copies
4134 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4135   if (remove_dead_region(phase, can_reshape)) return this;
4136   // Don't bother trying to transform a dead node
4137   if (in(0) && in(0)->is_top()) {
4138     return nullptr;
4139   }
4140 
4141   bool progress = false;
4142   // Eliminate volatile MemBars for scalar replaced objects.
4143   if (can_reshape && req() == (Precedent+1)) {
4144     bool eliminate = false;
4145     int opc = Opcode();
4146     if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4147       // Volatile field loads and stores.
4148       Node* my_mem = in(MemBarNode::Precedent);
4149       // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4150       if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4151         // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4152         // replace this Precedent (decodeN) with the Load instead.
4153         if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1))  {
4154           Node* load_node = my_mem->in(1);
4155           set_req(MemBarNode::Precedent, load_node);
4156           phase->is_IterGVN()->_worklist.push(my_mem);
4157           my_mem = load_node;
4158         } else {
4159           assert(my_mem->unique_out() == this, "sanity");
4160           assert(!trailing_load_store(), "load store node can't be eliminated");
4161           del_req(Precedent);
4162           phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4163           my_mem = nullptr;
4164         }
4165         progress = true;
4166       }
4167       if (my_mem != nullptr && my_mem->is_Mem()) {
4168         const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4169         // Check for scalar replaced object reference.
4170         if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4171             t_oop->offset() != Type::OffsetBot &&
4172             t_oop->offset() != Type::OffsetTop) {
4173           eliminate = true;
4174         }
4175       }
4176     } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4177       // Final field stores.
4178       Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4179       if ((alloc != nullptr) && alloc->is_Allocate() &&
4180           alloc->as_Allocate()->does_not_escape_thread()) {
4181         // The allocated object does not escape.
4182         eliminate = true;
4183       }
4184     }
4185     if (eliminate) {
4186       // Replace MemBar projections by its inputs.
4187       PhaseIterGVN* igvn = phase->is_IterGVN();
4188       remove(igvn);
4189       // Must return either the original node (now dead) or a new node
4190       // (Do not return a top here, since that would break the uniqueness of top.)
4191       return new ConINode(TypeInt::ZERO);
4192     }
4193   }
4194   return progress ? this : nullptr;
4195 }
4196 
4197 //------------------------------Value------------------------------------------
4198 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4199   if( !in(0) ) return Type::TOP;
4200   if( phase->type(in(0)) == Type::TOP )
4201     return Type::TOP;
4202   return TypeTuple::MEMBAR;
4203 }
4204 
4205 //------------------------------match------------------------------------------
4206 // Construct projections for memory.
4207 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
4208   switch (proj->_con) {
4209   case TypeFunc::Control:
4210   case TypeFunc::Memory:
4211     return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4212   }
4213   ShouldNotReachHere();
4214   return nullptr;
4215 }
4216 
4217 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4218   trailing->_kind = TrailingStore;
4219   leading->_kind = LeadingStore;
4220 #ifdef ASSERT
4221   trailing->_pair_idx = leading->_idx;
4222   leading->_pair_idx = leading->_idx;
4223 #endif
4224 }
4225 
4226 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4227   trailing->_kind = TrailingLoadStore;
4228   leading->_kind = LeadingLoadStore;
4229 #ifdef ASSERT
4230   trailing->_pair_idx = leading->_idx;
4231   leading->_pair_idx = leading->_idx;
4232 #endif
4233 }
4234 
4235 MemBarNode* MemBarNode::trailing_membar() const {
4236   ResourceMark rm;
4237   Node* trailing = (Node*)this;
4238   VectorSet seen;
4239   Node_Stack multis(0);
4240   do {
4241     Node* c = trailing;
4242     uint i = 0;
4243     do {
4244       trailing = nullptr;
4245       for (; i < c->outcnt(); i++) {
4246         Node* next = c->raw_out(i);
4247         if (next != c && next->is_CFG()) {
4248           if (c->is_MultiBranch()) {
4249             if (multis.node() == c) {
4250               multis.set_index(i+1);
4251             } else {
4252               multis.push(c, i+1);
4253             }
4254           }
4255           trailing = next;
4256           break;
4257         }
4258       }
4259       if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4260         break;
4261       }
4262       while (multis.size() > 0) {
4263         c = multis.node();
4264         i = multis.index();
4265         if (i < c->req()) {
4266           break;
4267         }
4268         multis.pop();
4269       }
4270     } while (multis.size() > 0);
4271   } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4272 
4273   MemBarNode* mb = trailing->as_MemBar();
4274   assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4275          (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4276   assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4277   return mb;
4278 }
4279 
4280 MemBarNode* MemBarNode::leading_membar() const {
4281   ResourceMark rm;
4282   VectorSet seen;
4283   Node_Stack regions(0);
4284   Node* leading = in(0);
4285   while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4286     while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4287       leading = nullptr;
4288       while (regions.size() > 0 && leading == nullptr) {
4289         Node* r = regions.node();
4290         uint i = regions.index();
4291         if (i < r->req()) {
4292           leading = r->in(i);
4293           regions.set_index(i+1);
4294         } else {
4295           regions.pop();
4296         }
4297       }
4298       if (leading == nullptr) {
4299         assert(regions.size() == 0, "all paths should have been tried");
4300         return nullptr;
4301       }
4302     }
4303     if (leading->is_Region()) {
4304       regions.push(leading, 2);
4305       leading = leading->in(1);
4306     } else {
4307       leading = leading->in(0);
4308     }
4309   }
4310 #ifdef ASSERT
4311   Unique_Node_List wq;
4312   wq.push((Node*)this);
4313   uint found = 0;
4314   for (uint i = 0; i < wq.size(); i++) {
4315     Node* n = wq.at(i);
4316     if (n->is_Region()) {
4317       for (uint j = 1; j < n->req(); j++) {
4318         Node* in = n->in(j);
4319         if (in != nullptr && !in->is_top()) {
4320           wq.push(in);
4321         }
4322       }
4323     } else {
4324       if (n->is_MemBar() && n->as_MemBar()->leading()) {
4325         assert(n == leading, "consistency check failed");
4326         found++;
4327       } else {
4328         Node* in = n->in(0);
4329         if (in != nullptr && !in->is_top()) {
4330           wq.push(in);
4331         }
4332       }
4333     }
4334   }
4335   assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4336 #endif
4337   if (leading == nullptr) {
4338     return nullptr;
4339   }
4340   MemBarNode* mb = leading->as_MemBar();
4341   assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4342          (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4343   assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4344   return mb;
4345 }
4346 
4347 
4348 //===========================InitializeNode====================================
4349 // SUMMARY:
4350 // This node acts as a memory barrier on raw memory, after some raw stores.
4351 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4352 // The Initialize can 'capture' suitably constrained stores as raw inits.
4353 // It can coalesce related raw stores into larger units (called 'tiles').
4354 // It can avoid zeroing new storage for memory units which have raw inits.
4355 // At macro-expansion, it is marked 'complete', and does not optimize further.
4356 //
4357 // EXAMPLE:
4358 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4359 //   ctl = incoming control; mem* = incoming memory
4360 // (Note:  A star * on a memory edge denotes I/O and other standard edges.)
4361 // First allocate uninitialized memory and fill in the header:
4362 //   alloc = (Allocate ctl mem* 16 #short[].klass ...)
4363 //   ctl := alloc.Control; mem* := alloc.Memory*
4364 //   rawmem = alloc.Memory; rawoop = alloc.RawAddress
4365 // Then initialize to zero the non-header parts of the raw memory block:
4366 //   init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4367 //   ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4368 // After the initialize node executes, the object is ready for service:
4369 //   oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4370 // Suppose its body is immediately initialized as {1,2}:
4371 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4372 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
4373 //   mem.SLICE(#short[*]) := store2
4374 //
4375 // DETAILS:
4376 // An InitializeNode collects and isolates object initialization after
4377 // an AllocateNode and before the next possible safepoint.  As a
4378 // memory barrier (MemBarNode), it keeps critical stores from drifting
4379 // down past any safepoint or any publication of the allocation.
4380 // Before this barrier, a newly-allocated object may have uninitialized bits.
4381 // After this barrier, it may be treated as a real oop, and GC is allowed.
4382 //
4383 // The semantics of the InitializeNode include an implicit zeroing of
4384 // the new object from object header to the end of the object.
4385 // (The object header and end are determined by the AllocateNode.)
4386 //
4387 // Certain stores may be added as direct inputs to the InitializeNode.
4388 // These stores must update raw memory, and they must be to addresses
4389 // derived from the raw address produced by AllocateNode, and with
4390 // a constant offset.  They must be ordered by increasing offset.
4391 // The first one is at in(RawStores), the last at in(req()-1).
4392 // Unlike most memory operations, they are not linked in a chain,
4393 // but are displayed in parallel as users of the rawmem output of
4394 // the allocation.
4395 //
4396 // (See comments in InitializeNode::capture_store, which continue
4397 // the example given above.)
4398 //
4399 // When the associated Allocate is macro-expanded, the InitializeNode
4400 // may be rewritten to optimize collected stores.  A ClearArrayNode
4401 // may also be created at that point to represent any required zeroing.
4402 // The InitializeNode is then marked 'complete', prohibiting further
4403 // capturing of nearby memory operations.
4404 //
4405 // During macro-expansion, all captured initializations which store
4406 // constant values of 32 bits or smaller are coalesced (if advantageous)
4407 // into larger 'tiles' 32 or 64 bits.  This allows an object to be
4408 // initialized in fewer memory operations.  Memory words which are
4409 // covered by neither tiles nor non-constant stores are pre-zeroed
4410 // by explicit stores of zero.  (The code shape happens to do all
4411 // zeroing first, then all other stores, with both sequences occurring
4412 // in order of ascending offsets.)
4413 //
4414 // Alternatively, code may be inserted between an AllocateNode and its
4415 // InitializeNode, to perform arbitrary initialization of the new object.
4416 // E.g., the object copying intrinsics insert complex data transfers here.
4417 // The initialization must then be marked as 'complete' disable the
4418 // built-in zeroing semantics and the collection of initializing stores.
4419 //
4420 // While an InitializeNode is incomplete, reads from the memory state
4421 // produced by it are optimizable if they match the control edge and
4422 // new oop address associated with the allocation/initialization.
4423 // They return a stored value (if the offset matches) or else zero.
4424 // A write to the memory state, if it matches control and address,
4425 // and if it is to a constant offset, may be 'captured' by the
4426 // InitializeNode.  It is cloned as a raw memory operation and rewired
4427 // inside the initialization, to the raw oop produced by the allocation.
4428 // Operations on addresses which are provably distinct (e.g., to
4429 // other AllocateNodes) are allowed to bypass the initialization.
4430 //
4431 // The effect of all this is to consolidate object initialization
4432 // (both arrays and non-arrays, both piecewise and bulk) into a
4433 // single location, where it can be optimized as a unit.
4434 //
4435 // Only stores with an offset less than TrackedInitializationLimit words
4436 // will be considered for capture by an InitializeNode.  This puts a
4437 // reasonable limit on the complexity of optimized initializations.
4438 
4439 //---------------------------InitializeNode------------------------------------
4440 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4441   : MemBarNode(C, adr_type, rawoop),
4442     _is_complete(Incomplete), _does_not_escape(false)
4443 {
4444   init_class_id(Class_Initialize);
4445 
4446   assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4447   assert(in(RawAddress) == rawoop, "proper init");
4448   // Note:  allocation() can be null, for secondary initialization barriers
4449 }
4450 
4451 // Since this node is not matched, it will be processed by the
4452 // register allocator.  Declare that there are no constraints
4453 // on the allocation of the RawAddress edge.
4454 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4455   // This edge should be set to top, by the set_complete.  But be conservative.
4456   if (idx == InitializeNode::RawAddress)
4457     return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4458   return RegMask::Empty;
4459 }
4460 
4461 Node* InitializeNode::memory(uint alias_idx) {
4462   Node* mem = in(Memory);
4463   if (mem->is_MergeMem()) {
4464     return mem->as_MergeMem()->memory_at(alias_idx);
4465   } else {
4466     // incoming raw memory is not split
4467     return mem;
4468   }
4469 }
4470 
4471 bool InitializeNode::is_non_zero() {
4472   if (is_complete())  return false;
4473   remove_extra_zeroes();
4474   return (req() > RawStores);
4475 }
4476 
4477 void InitializeNode::set_complete(PhaseGVN* phase) {
4478   assert(!is_complete(), "caller responsibility");
4479   _is_complete = Complete;
4480 
4481   // After this node is complete, it contains a bunch of
4482   // raw-memory initializations.  There is no need for
4483   // it to have anything to do with non-raw memory effects.
4484   // Therefore, tell all non-raw users to re-optimize themselves,
4485   // after skipping the memory effects of this initialization.
4486   PhaseIterGVN* igvn = phase->is_IterGVN();
4487   if (igvn)  igvn->add_users_to_worklist(this);
4488 }
4489 
4490 // convenience function
4491 // return false if the init contains any stores already
4492 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4493   InitializeNode* init = initialization();
4494   if (init == nullptr || init->is_complete())  return false;
4495   init->remove_extra_zeroes();
4496   // for now, if this allocation has already collected any inits, bail:
4497   if (init->is_non_zero())  return false;
4498   init->set_complete(phase);
4499   return true;
4500 }
4501 
4502 void InitializeNode::remove_extra_zeroes() {
4503   if (req() == RawStores)  return;
4504   Node* zmem = zero_memory();
4505   uint fill = RawStores;
4506   for (uint i = fill; i < req(); i++) {
4507     Node* n = in(i);
4508     if (n->is_top() || n == zmem)  continue;  // skip
4509     if (fill < i)  set_req(fill, n);          // compact
4510     ++fill;
4511   }
4512   // delete any empty spaces created:
4513   while (fill < req()) {
4514     del_req(fill);
4515   }
4516 }
4517 
4518 // Helper for remembering which stores go with which offsets.
4519 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4520   if (!st->is_Store())  return -1;  // can happen to dead code via subsume_node
4521   intptr_t offset = -1;
4522   Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4523                                                phase, offset);
4524   if (base == nullptr)  return -1;  // something is dead,
4525   if (offset < 0)       return -1;  //        dead, dead
4526   return offset;
4527 }
4528 
4529 // Helper for proving that an initialization expression is
4530 // "simple enough" to be folded into an object initialization.
4531 // Attempts to prove that a store's initial value 'n' can be captured
4532 // within the initialization without creating a vicious cycle, such as:
4533 //     { Foo p = new Foo(); p.next = p; }
4534 // True for constants and parameters and small combinations thereof.
4535 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4536   ResourceMark rm;
4537   Unique_Node_List worklist;
4538   worklist.push(value);
4539 
4540   uint complexity_limit = 20;
4541   for (uint j = 0; j < worklist.size(); j++) {
4542     if (j >= complexity_limit) {
4543       return false;  // Bail out if processed too many nodes
4544     }
4545 
4546     Node* n = worklist.at(j);
4547     if (n == nullptr)   continue;   // (can this really happen?)
4548     if (n->is_Proj())   n = n->in(0);
4549     if (n == this)      return false;  // found a cycle
4550     if (n->is_Con())    continue;
4551     if (n->is_Start())  continue;   // params, etc., are OK
4552     if (n->is_Root())   continue;   // even better
4553 
4554     // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4555     if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4556       continue;
4557     }
4558 
4559     Node* ctl = n->in(0);
4560     if (ctl != nullptr && !ctl->is_top()) {
4561       if (ctl->is_Proj())  ctl = ctl->in(0);
4562       if (ctl == this)  return false;
4563 
4564       // If we already know that the enclosing memory op is pinned right after
4565       // the init, then any control flow that the store has picked up
4566       // must have preceded the init, or else be equal to the init.
4567       // Even after loop optimizations (which might change control edges)
4568       // a store is never pinned *before* the availability of its inputs.
4569       if (!MemNode::all_controls_dominate(n, this))
4570         return false;                  // failed to prove a good control
4571     }
4572 
4573     // Check data edges for possible dependencies on 'this'.
4574     for (uint i = 1; i < n->req(); i++) {
4575       Node* m = n->in(i);
4576       if (m == nullptr || m == n || m->is_top())  continue;
4577 
4578       // Only process data inputs once
4579       worklist.push(m);
4580     }
4581   }
4582 
4583   return true;
4584 }
4585 
4586 // Here are all the checks a Store must pass before it can be moved into
4587 // an initialization.  Returns zero if a check fails.
4588 // On success, returns the (constant) offset to which the store applies,
4589 // within the initialized memory.
4590 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4591   const int FAIL = 0;
4592   if (st->req() != MemNode::ValueIn + 1)
4593     return FAIL;                // an inscrutable StoreNode (card mark?)
4594   Node* ctl = st->in(MemNode::Control);
4595   if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4596     return FAIL;                // must be unconditional after the initialization
4597   Node* mem = st->in(MemNode::Memory);
4598   if (!(mem->is_Proj() && mem->in(0) == this))
4599     return FAIL;                // must not be preceded by other stores
4600   Node* adr = st->in(MemNode::Address);
4601   intptr_t offset;
4602   AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4603   if (alloc == nullptr)
4604     return FAIL;                // inscrutable address
4605   if (alloc != allocation())
4606     return FAIL;                // wrong allocation!  (store needs to float up)
4607   int size_in_bytes = st->memory_size();
4608   if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4609     return FAIL;                // mismatched access
4610   }
4611   Node* val = st->in(MemNode::ValueIn);
4612 
4613   if (!detect_init_independence(val, phase))
4614     return FAIL;                // stored value must be 'simple enough'
4615 
4616   // The Store can be captured only if nothing after the allocation
4617   // and before the Store is using the memory location that the store
4618   // overwrites.
4619   bool failed = false;
4620   // If is_complete_with_arraycopy() is true the shape of the graph is
4621   // well defined and is safe so no need for extra checks.
4622   if (!is_complete_with_arraycopy()) {
4623     // We are going to look at each use of the memory state following
4624     // the allocation to make sure nothing reads the memory that the
4625     // Store writes.
4626     const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4627     int alias_idx = phase->C->get_alias_index(t_adr);
4628     ResourceMark rm;
4629     Unique_Node_List mems;
4630     mems.push(mem);
4631     Node* unique_merge = nullptr;
4632     for (uint next = 0; next < mems.size(); ++next) {
4633       Node *m  = mems.at(next);
4634       for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4635         Node *n = m->fast_out(j);
4636         if (n->outcnt() == 0) {
4637           continue;
4638         }
4639         if (n == st) {
4640           continue;
4641         } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4642           // If the control of this use is different from the control
4643           // of the Store which is right after the InitializeNode then
4644           // this node cannot be between the InitializeNode and the
4645           // Store.
4646           continue;
4647         } else if (n->is_MergeMem()) {
4648           if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4649             // We can hit a MergeMemNode (that will likely go away
4650             // later) that is a direct use of the memory state
4651             // following the InitializeNode on the same slice as the
4652             // store node that we'd like to capture. We need to check
4653             // the uses of the MergeMemNode.
4654             mems.push(n);
4655           }
4656         } else if (n->is_Mem()) {
4657           Node* other_adr = n->in(MemNode::Address);
4658           if (other_adr == adr) {
4659             failed = true;
4660             break;
4661           } else {
4662             const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4663             if (other_t_adr != nullptr) {
4664               int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4665               if (other_alias_idx == alias_idx) {
4666                 // A load from the same memory slice as the store right
4667                 // after the InitializeNode. We check the control of the
4668                 // object/array that is loaded from. If it's the same as
4669                 // the store control then we cannot capture the store.
4670                 assert(!n->is_Store(), "2 stores to same slice on same control?");
4671                 Node* base = other_adr;
4672                 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4673                 base = base->in(AddPNode::Base);
4674                 if (base != nullptr) {
4675                   base = base->uncast();
4676                   if (base->is_Proj() && base->in(0) == alloc) {
4677                     failed = true;
4678                     break;
4679                   }
4680                 }
4681               }
4682             }
4683           }
4684         } else {
4685           failed = true;
4686           break;
4687         }
4688       }
4689     }
4690   }
4691   if (failed) {
4692     if (!can_reshape) {
4693       // We decided we couldn't capture the store during parsing. We
4694       // should try again during the next IGVN once the graph is
4695       // cleaner.
4696       phase->C->record_for_igvn(st);
4697     }
4698     return FAIL;
4699   }
4700 
4701   return offset;                // success
4702 }
4703 
4704 // Find the captured store in(i) which corresponds to the range
4705 // [start..start+size) in the initialized object.
4706 // If there is one, return its index i.  If there isn't, return the
4707 // negative of the index where it should be inserted.
4708 // Return 0 if the queried range overlaps an initialization boundary
4709 // or if dead code is encountered.
4710 // If size_in_bytes is zero, do not bother with overlap checks.
4711 int InitializeNode::captured_store_insertion_point(intptr_t start,
4712                                                    int size_in_bytes,
4713                                                    PhaseValues* phase) {
4714   const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4715 
4716   if (is_complete())
4717     return FAIL;                // arraycopy got here first; punt
4718 
4719   assert(allocation() != nullptr, "must be present");
4720 
4721   // no negatives, no header fields:
4722   if (start < (intptr_t) allocation()->minimum_header_size())  return FAIL;
4723 
4724   // after a certain size, we bail out on tracking all the stores:
4725   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4726   if (start >= ti_limit)  return FAIL;
4727 
4728   for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4729     if (i >= limit)  return -(int)i; // not found; here is where to put it
4730 
4731     Node*    st     = in(i);
4732     intptr_t st_off = get_store_offset(st, phase);
4733     if (st_off < 0) {
4734       if (st != zero_memory()) {
4735         return FAIL;            // bail out if there is dead garbage
4736       }
4737     } else if (st_off > start) {
4738       // ...we are done, since stores are ordered
4739       if (st_off < start + size_in_bytes) {
4740         return FAIL;            // the next store overlaps
4741       }
4742       return -(int)i;           // not found; here is where to put it
4743     } else if (st_off < start) {
4744       assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4745       if (size_in_bytes != 0 &&
4746           start < st_off + MAX_STORE &&
4747           start < st_off + st->as_Store()->memory_size()) {
4748         return FAIL;            // the previous store overlaps
4749       }
4750     } else {
4751       if (size_in_bytes != 0 &&
4752           st->as_Store()->memory_size() != size_in_bytes) {
4753         return FAIL;            // mismatched store size
4754       }
4755       return i;
4756     }
4757 
4758     ++i;
4759   }
4760 }
4761 
4762 // Look for a captured store which initializes at the offset 'start'
4763 // with the given size.  If there is no such store, and no other
4764 // initialization interferes, then return zero_memory (the memory
4765 // projection of the AllocateNode).
4766 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4767                                           PhaseValues* phase) {
4768   assert(stores_are_sane(phase), "");
4769   int i = captured_store_insertion_point(start, size_in_bytes, phase);
4770   if (i == 0) {
4771     return nullptr;              // something is dead
4772   } else if (i < 0) {
4773     return zero_memory();       // just primordial zero bits here
4774   } else {
4775     Node* st = in(i);           // here is the store at this position
4776     assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4777     return st;
4778   }
4779 }
4780 
4781 // Create, as a raw pointer, an address within my new object at 'offset'.
4782 Node* InitializeNode::make_raw_address(intptr_t offset,
4783                                        PhaseGVN* phase) {
4784   Node* addr = in(RawAddress);
4785   if (offset != 0) {
4786     Compile* C = phase->C;
4787     addr = phase->transform( new AddPNode(C->top(), addr,
4788                                                  phase->MakeConX(offset)) );
4789   }
4790   return addr;
4791 }
4792 
4793 // Clone the given store, converting it into a raw store
4794 // initializing a field or element of my new object.
4795 // Caller is responsible for retiring the original store,
4796 // with subsume_node or the like.
4797 //
4798 // From the example above InitializeNode::InitializeNode,
4799 // here are the old stores to be captured:
4800 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4801 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
4802 //
4803 // Here is the changed code; note the extra edges on init:
4804 //   alloc = (Allocate ...)
4805 //   rawoop = alloc.RawAddress
4806 //   rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4807 //   rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4808 //   init = (Initialize alloc.Control alloc.Memory rawoop
4809 //                      rawstore1 rawstore2)
4810 //
4811 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4812                                     PhaseGVN* phase, bool can_reshape) {
4813   assert(stores_are_sane(phase), "");
4814 
4815   if (start < 0)  return nullptr;
4816   assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4817 
4818   Compile* C = phase->C;
4819   int size_in_bytes = st->memory_size();
4820   int i = captured_store_insertion_point(start, size_in_bytes, phase);
4821   if (i == 0)  return nullptr;  // bail out
4822   Node* prev_mem = nullptr;     // raw memory for the captured store
4823   if (i > 0) {
4824     prev_mem = in(i);           // there is a pre-existing store under this one
4825     set_req(i, C->top());       // temporarily disconnect it
4826     // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4827   } else {
4828     i = -i;                     // no pre-existing store
4829     prev_mem = zero_memory();   // a slice of the newly allocated object
4830     if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4831       set_req(--i, C->top());   // reuse this edge; it has been folded away
4832     else
4833       ins_req(i, C->top());     // build a new edge
4834   }
4835   Node* new_st = st->clone();
4836   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4837   new_st->set_req(MemNode::Control, in(Control));
4838   new_st->set_req(MemNode::Memory,  prev_mem);
4839   new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4840   bs->eliminate_gc_barrier_data(new_st);
4841   new_st = phase->transform(new_st);
4842 
4843   // At this point, new_st might have swallowed a pre-existing store
4844   // at the same offset, or perhaps new_st might have disappeared,
4845   // if it redundantly stored the same value (or zero to fresh memory).
4846 
4847   // In any case, wire it in:
4848   PhaseIterGVN* igvn = phase->is_IterGVN();
4849   if (igvn) {
4850     igvn->rehash_node_delayed(this);
4851   }
4852   set_req(i, new_st);
4853 
4854   // The caller may now kill the old guy.
4855   DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4856   assert(check_st == new_st || check_st == nullptr, "must be findable");
4857   assert(!is_complete(), "");
4858   return new_st;
4859 }
4860 
4861 static bool store_constant(jlong* tiles, int num_tiles,
4862                            intptr_t st_off, int st_size,
4863                            jlong con) {
4864   if ((st_off & (st_size-1)) != 0)
4865     return false;               // strange store offset (assume size==2**N)
4866   address addr = (address)tiles + st_off;
4867   assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4868   switch (st_size) {
4869   case sizeof(jbyte):  *(jbyte*) addr = (jbyte) con; break;
4870   case sizeof(jchar):  *(jchar*) addr = (jchar) con; break;
4871   case sizeof(jint):   *(jint*)  addr = (jint)  con; break;
4872   case sizeof(jlong):  *(jlong*) addr = (jlong) con; break;
4873   default: return false;        // strange store size (detect size!=2**N here)
4874   }
4875   return true;                  // return success to caller
4876 }
4877 
4878 // Coalesce subword constants into int constants and possibly
4879 // into long constants.  The goal, if the CPU permits,
4880 // is to initialize the object with a small number of 64-bit tiles.
4881 // Also, convert floating-point constants to bit patterns.
4882 // Non-constants are not relevant to this pass.
4883 //
4884 // In terms of the running example on InitializeNode::InitializeNode
4885 // and InitializeNode::capture_store, here is the transformation
4886 // of rawstore1 and rawstore2 into rawstore12:
4887 //   alloc = (Allocate ...)
4888 //   rawoop = alloc.RawAddress
4889 //   tile12 = 0x00010002
4890 //   rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4891 //   init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4892 //
4893 void
4894 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4895                                         Node* size_in_bytes,
4896                                         PhaseGVN* phase) {
4897   Compile* C = phase->C;
4898 
4899   assert(stores_are_sane(phase), "");
4900   // Note:  After this pass, they are not completely sane,
4901   // since there may be some overlaps.
4902 
4903   int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4904 
4905   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4906   intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4907   size_limit = MIN2(size_limit, ti_limit);
4908   size_limit = align_up(size_limit, BytesPerLong);
4909   int num_tiles = size_limit / BytesPerLong;
4910 
4911   // allocate space for the tile map:
4912   const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4913   jlong  tiles_buf[small_len];
4914   Node*  nodes_buf[small_len];
4915   jlong  inits_buf[small_len];
4916   jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4917                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4918   Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4919                   : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4920   jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4921                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4922   // tiles: exact bitwise model of all primitive constants
4923   // nodes: last constant-storing node subsumed into the tiles model
4924   // inits: which bytes (in each tile) are touched by any initializations
4925 
4926   //// Pass A: Fill in the tile model with any relevant stores.
4927 
4928   Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4929   Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4930   Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4931   Node* zmem = zero_memory(); // initially zero memory state
4932   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4933     Node* st = in(i);
4934     intptr_t st_off = get_store_offset(st, phase);
4935 
4936     // Figure out the store's offset and constant value:
4937     if (st_off < header_size)             continue; //skip (ignore header)
4938     if (st->in(MemNode::Memory) != zmem)  continue; //skip (odd store chain)
4939     int st_size = st->as_Store()->memory_size();
4940     if (st_off + st_size > size_limit)    break;
4941 
4942     // Record which bytes are touched, whether by constant or not.
4943     if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4944       continue;                 // skip (strange store size)
4945 
4946     const Type* val = phase->type(st->in(MemNode::ValueIn));
4947     if (!val->singleton())                continue; //skip (non-con store)
4948     BasicType type = val->basic_type();
4949 
4950     jlong con = 0;
4951     switch (type) {
4952     case T_INT:    con = val->is_int()->get_con();  break;
4953     case T_LONG:   con = val->is_long()->get_con(); break;
4954     case T_FLOAT:  con = jint_cast(val->getf());    break;
4955     case T_DOUBLE: con = jlong_cast(val->getd());   break;
4956     default:                              continue; //skip (odd store type)
4957     }
4958 
4959     if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4960         st->Opcode() == Op_StoreL) {
4961       continue;                 // This StoreL is already optimal.
4962     }
4963 
4964     // Store down the constant.
4965     store_constant(tiles, num_tiles, st_off, st_size, con);
4966 
4967     intptr_t j = st_off >> LogBytesPerLong;
4968 
4969     if (type == T_INT && st_size == BytesPerInt
4970         && (st_off & BytesPerInt) == BytesPerInt) {
4971       jlong lcon = tiles[j];
4972       if (!Matcher::isSimpleConstant64(lcon) &&
4973           st->Opcode() == Op_StoreI) {
4974         // This StoreI is already optimal by itself.
4975         jint* intcon = (jint*) &tiles[j];
4976         intcon[1] = 0;  // undo the store_constant()
4977 
4978         // If the previous store is also optimal by itself, back up and
4979         // undo the action of the previous loop iteration... if we can.
4980         // But if we can't, just let the previous half take care of itself.
4981         st = nodes[j];
4982         st_off -= BytesPerInt;
4983         con = intcon[0];
4984         if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
4985           assert(st_off >= header_size, "still ignoring header");
4986           assert(get_store_offset(st, phase) == st_off, "must be");
4987           assert(in(i-1) == zmem, "must be");
4988           DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4989           assert(con == tcon->is_int()->get_con(), "must be");
4990           // Undo the effects of the previous loop trip, which swallowed st:
4991           intcon[0] = 0;        // undo store_constant()
4992           set_req(i-1, st);     // undo set_req(i, zmem)
4993           nodes[j] = nullptr;   // undo nodes[j] = st
4994           --old_subword;        // undo ++old_subword
4995         }
4996         continue;               // This StoreI is already optimal.
4997       }
4998     }
4999 
5000     // This store is not needed.
5001     set_req(i, zmem);
5002     nodes[j] = st;              // record for the moment
5003     if (st_size < BytesPerLong) // something has changed
5004           ++old_subword;        // includes int/float, but who's counting...
5005     else  ++old_long;
5006   }
5007 
5008   if ((old_subword + old_long) == 0)
5009     return;                     // nothing more to do
5010 
5011   //// Pass B: Convert any non-zero tiles into optimal constant stores.
5012   // Be sure to insert them before overlapping non-constant stores.
5013   // (E.g., byte[] x = { 1,2,y,4 }  =>  x[int 0] = 0x01020004, x[2]=y.)
5014   for (int j = 0; j < num_tiles; j++) {
5015     jlong con  = tiles[j];
5016     jlong init = inits[j];
5017     if (con == 0)  continue;
5018     jint con0,  con1;           // split the constant, address-wise
5019     jint init0, init1;          // split the init map, address-wise
5020     { union { jlong con; jint intcon[2]; } u;
5021       u.con = con;
5022       con0  = u.intcon[0];
5023       con1  = u.intcon[1];
5024       u.con = init;
5025       init0 = u.intcon[0];
5026       init1 = u.intcon[1];
5027     }
5028 
5029     Node* old = nodes[j];
5030     assert(old != nullptr, "need the prior store");
5031     intptr_t offset = (j * BytesPerLong);
5032 
5033     bool split = !Matcher::isSimpleConstant64(con);
5034 
5035     if (offset < header_size) {
5036       assert(offset + BytesPerInt >= header_size, "second int counts");
5037       assert(*(jint*)&tiles[j] == 0, "junk in header");
5038       split = true;             // only the second word counts
5039       // Example:  int a[] = { 42 ... }
5040     } else if (con0 == 0 && init0 == -1) {
5041       split = true;             // first word is covered by full inits
5042       // Example:  int a[] = { ... foo(), 42 ... }
5043     } else if (con1 == 0 && init1 == -1) {
5044       split = true;             // second word is covered by full inits
5045       // Example:  int a[] = { ... 42, foo() ... }
5046     }
5047 
5048     // Here's a case where init0 is neither 0 nor -1:
5049     //   byte a[] = { ... 0,0,foo(),0,  0,0,0,42 ... }
5050     // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5051     // In this case the tile is not split; it is (jlong)42.
5052     // The big tile is stored down, and then the foo() value is inserted.
5053     // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5054 
5055     Node* ctl = old->in(MemNode::Control);
5056     Node* adr = make_raw_address(offset, phase);
5057     const TypePtr* atp = TypeRawPtr::BOTTOM;
5058 
5059     // One or two coalesced stores to plop down.
5060     Node*    st[2];
5061     intptr_t off[2];
5062     int  nst = 0;
5063     if (!split) {
5064       ++new_long;
5065       off[nst] = offset;
5066       st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5067                                   phase->longcon(con), T_LONG, MemNode::unordered);
5068     } else {
5069       // Omit either if it is a zero.
5070       if (con0 != 0) {
5071         ++new_int;
5072         off[nst]  = offset;
5073         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5074                                     phase->intcon(con0), T_INT, MemNode::unordered);
5075       }
5076       if (con1 != 0) {
5077         ++new_int;
5078         offset += BytesPerInt;
5079         adr = make_raw_address(offset, phase);
5080         off[nst]  = offset;
5081         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5082                                     phase->intcon(con1), T_INT, MemNode::unordered);
5083       }
5084     }
5085 
5086     // Insert second store first, then the first before the second.
5087     // Insert each one just before any overlapping non-constant stores.
5088     while (nst > 0) {
5089       Node* st1 = st[--nst];
5090       C->copy_node_notes_to(st1, old);
5091       st1 = phase->transform(st1);
5092       offset = off[nst];
5093       assert(offset >= header_size, "do not smash header");
5094       int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5095       guarantee(ins_idx != 0, "must re-insert constant store");
5096       if (ins_idx < 0)  ins_idx = -ins_idx;  // never overlap
5097       if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5098         set_req(--ins_idx, st1);
5099       else
5100         ins_req(ins_idx, st1);
5101     }
5102   }
5103 
5104   if (PrintCompilation && WizardMode)
5105     tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5106                   old_subword, old_long, new_int, new_long);
5107   if (C->log() != nullptr)
5108     C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5109                    old_subword, old_long, new_int, new_long);
5110 
5111   // Clean up any remaining occurrences of zmem:
5112   remove_extra_zeroes();
5113 }
5114 
5115 // Explore forward from in(start) to find the first fully initialized
5116 // word, and return its offset.  Skip groups of subword stores which
5117 // together initialize full words.  If in(start) is itself part of a
5118 // fully initialized word, return the offset of in(start).  If there
5119 // are no following full-word stores, or if something is fishy, return
5120 // a negative value.
5121 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5122   int       int_map = 0;
5123   intptr_t  int_map_off = 0;
5124   const int FULL_MAP = right_n_bits(BytesPerInt);  // the int_map we hope for
5125 
5126   for (uint i = start, limit = req(); i < limit; i++) {
5127     Node* st = in(i);
5128 
5129     intptr_t st_off = get_store_offset(st, phase);
5130     if (st_off < 0)  break;  // return conservative answer
5131 
5132     int st_size = st->as_Store()->memory_size();
5133     if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5134       return st_off;            // we found a complete word init
5135     }
5136 
5137     // update the map:
5138 
5139     intptr_t this_int_off = align_down(st_off, BytesPerInt);
5140     if (this_int_off != int_map_off) {
5141       // reset the map:
5142       int_map = 0;
5143       int_map_off = this_int_off;
5144     }
5145 
5146     int subword_off = st_off - this_int_off;
5147     int_map |= right_n_bits(st_size) << subword_off;
5148     if ((int_map & FULL_MAP) == FULL_MAP) {
5149       return this_int_off;      // we found a complete word init
5150     }
5151 
5152     // Did this store hit or cross the word boundary?
5153     intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5154     if (next_int_off == this_int_off + BytesPerInt) {
5155       // We passed the current int, without fully initializing it.
5156       int_map_off = next_int_off;
5157       int_map >>= BytesPerInt;
5158     } else if (next_int_off > this_int_off + BytesPerInt) {
5159       // We passed the current and next int.
5160       return this_int_off + BytesPerInt;
5161     }
5162   }
5163 
5164   return -1;
5165 }
5166 
5167 
5168 // Called when the associated AllocateNode is expanded into CFG.
5169 // At this point, we may perform additional optimizations.
5170 // Linearize the stores by ascending offset, to make memory
5171 // activity as coherent as possible.
5172 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5173                                       intptr_t header_size,
5174                                       Node* size_in_bytes,
5175                                       PhaseIterGVN* phase) {
5176   assert(!is_complete(), "not already complete");
5177   assert(stores_are_sane(phase), "");
5178   assert(allocation() != nullptr, "must be present");
5179 
5180   remove_extra_zeroes();
5181 
5182   if (ReduceFieldZeroing || ReduceBulkZeroing)
5183     // reduce instruction count for common initialization patterns
5184     coalesce_subword_stores(header_size, size_in_bytes, phase);
5185 
5186   Node* zmem = zero_memory();   // initially zero memory state
5187   Node* inits = zmem;           // accumulating a linearized chain of inits
5188   #ifdef ASSERT
5189   intptr_t first_offset = allocation()->minimum_header_size();
5190   intptr_t last_init_off = first_offset;  // previous init offset
5191   intptr_t last_init_end = first_offset;  // previous init offset+size
5192   intptr_t last_tile_end = first_offset;  // previous tile offset+size
5193   #endif
5194   intptr_t zeroes_done = header_size;
5195 
5196   bool do_zeroing = true;       // we might give up if inits are very sparse
5197   int  big_init_gaps = 0;       // how many large gaps have we seen?
5198 
5199   if (UseTLAB && ZeroTLAB)  do_zeroing = false;
5200   if (!ReduceFieldZeroing && !ReduceBulkZeroing)  do_zeroing = false;
5201 
5202   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5203     Node* st = in(i);
5204     intptr_t st_off = get_store_offset(st, phase);
5205     if (st_off < 0)
5206       break;                    // unknown junk in the inits
5207     if (st->in(MemNode::Memory) != zmem)
5208       break;                    // complicated store chains somehow in list
5209 
5210     int st_size = st->as_Store()->memory_size();
5211     intptr_t next_init_off = st_off + st_size;
5212 
5213     if (do_zeroing && zeroes_done < next_init_off) {
5214       // See if this store needs a zero before it or under it.
5215       intptr_t zeroes_needed = st_off;
5216 
5217       if (st_size < BytesPerInt) {
5218         // Look for subword stores which only partially initialize words.
5219         // If we find some, we must lay down some word-level zeroes first,
5220         // underneath the subword stores.
5221         //
5222         // Examples:
5223         //   byte[] a = { p,q,r,s }  =>  a[0]=p,a[1]=q,a[2]=r,a[3]=s
5224         //   byte[] a = { x,y,0,0 }  =>  a[0..3] = 0, a[0]=x,a[1]=y
5225         //   byte[] a = { 0,0,z,0 }  =>  a[0..3] = 0, a[2]=z
5226         //
5227         // Note:  coalesce_subword_stores may have already done this,
5228         // if it was prompted by constant non-zero subword initializers.
5229         // But this case can still arise with non-constant stores.
5230 
5231         intptr_t next_full_store = find_next_fullword_store(i, phase);
5232 
5233         // In the examples above:
5234         //   in(i)          p   q   r   s     x   y     z
5235         //   st_off        12  13  14  15    12  13    14
5236         //   st_size        1   1   1   1     1   1     1
5237         //   next_full_s.  12  16  16  16    16  16    16
5238         //   z's_done      12  16  16  16    12  16    12
5239         //   z's_needed    12  16  16  16    16  16    16
5240         //   zsize          0   0   0   0     4   0     4
5241         if (next_full_store < 0) {
5242           // Conservative tack:  Zero to end of current word.
5243           zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5244         } else {
5245           // Zero to beginning of next fully initialized word.
5246           // Or, don't zero at all, if we are already in that word.
5247           assert(next_full_store >= zeroes_needed, "must go forward");
5248           assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5249           zeroes_needed = next_full_store;
5250         }
5251       }
5252 
5253       if (zeroes_needed > zeroes_done) {
5254         intptr_t zsize = zeroes_needed - zeroes_done;
5255         // Do some incremental zeroing on rawmem, in parallel with inits.
5256         zeroes_done = align_down(zeroes_done, BytesPerInt);
5257         rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5258                                               zeroes_done, zeroes_needed,
5259                                               phase);
5260         zeroes_done = zeroes_needed;
5261         if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5262           do_zeroing = false;   // leave the hole, next time
5263       }
5264     }
5265 
5266     // Collect the store and move on:
5267     phase->replace_input_of(st, MemNode::Memory, inits);
5268     inits = st;                 // put it on the linearized chain
5269     set_req(i, zmem);           // unhook from previous position
5270 
5271     if (zeroes_done == st_off)
5272       zeroes_done = next_init_off;
5273 
5274     assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5275 
5276     #ifdef ASSERT
5277     // Various order invariants.  Weaker than stores_are_sane because
5278     // a large constant tile can be filled in by smaller non-constant stores.
5279     assert(st_off >= last_init_off, "inits do not reverse");
5280     last_init_off = st_off;
5281     const Type* val = nullptr;
5282     if (st_size >= BytesPerInt &&
5283         (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5284         (int)val->basic_type() < (int)T_OBJECT) {
5285       assert(st_off >= last_tile_end, "tiles do not overlap");
5286       assert(st_off >= last_init_end, "tiles do not overwrite inits");
5287       last_tile_end = MAX2(last_tile_end, next_init_off);
5288     } else {
5289       intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5290       assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5291       assert(st_off      >= last_init_end, "inits do not overlap");
5292       last_init_end = next_init_off;  // it's a non-tile
5293     }
5294     #endif //ASSERT
5295   }
5296 
5297   remove_extra_zeroes();        // clear out all the zmems left over
5298   add_req(inits);
5299 
5300   if (!(UseTLAB && ZeroTLAB)) {
5301     // If anything remains to be zeroed, zero it all now.
5302     zeroes_done = align_down(zeroes_done, BytesPerInt);
5303     // if it is the last unused 4 bytes of an instance, forget about it
5304     intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5305     if (zeroes_done + BytesPerLong >= size_limit) {
5306       AllocateNode* alloc = allocation();
5307       assert(alloc != nullptr, "must be present");
5308       if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5309         Node* klass_node = alloc->in(AllocateNode::KlassNode);
5310         ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5311         if (zeroes_done == k->layout_helper())
5312           zeroes_done = size_limit;
5313       }
5314     }
5315     if (zeroes_done < size_limit) {
5316       rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5317                                             zeroes_done, size_in_bytes, phase);
5318     }
5319   }
5320 
5321   set_complete(phase);
5322   return rawmem;
5323 }
5324 
5325 
5326 #ifdef ASSERT
5327 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5328   if (is_complete())
5329     return true;                // stores could be anything at this point
5330   assert(allocation() != nullptr, "must be present");
5331   intptr_t last_off = allocation()->minimum_header_size();
5332   for (uint i = InitializeNode::RawStores; i < req(); i++) {
5333     Node* st = in(i);
5334     intptr_t st_off = get_store_offset(st, phase);
5335     if (st_off < 0)  continue;  // ignore dead garbage
5336     if (last_off > st_off) {
5337       tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
5338       this->dump(2);
5339       assert(false, "ascending store offsets");
5340       return false;
5341     }
5342     last_off = st_off + st->as_Store()->memory_size();
5343   }
5344   return true;
5345 }
5346 #endif //ASSERT
5347 
5348 
5349 
5350 
5351 //============================MergeMemNode=====================================
5352 //
5353 // SEMANTICS OF MEMORY MERGES:  A MergeMem is a memory state assembled from several
5354 // contributing store or call operations.  Each contributor provides the memory
5355 // state for a particular "alias type" (see Compile::alias_type).  For example,
5356 // if a MergeMem has an input X for alias category #6, then any memory reference
5357 // to alias category #6 may use X as its memory state input, as an exact equivalent
5358 // to using the MergeMem as a whole.
5359 //   Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5360 //
5361 // (Here, the <N> notation gives the index of the relevant adr_type.)
5362 //
5363 // In one special case (and more cases in the future), alias categories overlap.
5364 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5365 // states.  Therefore, if a MergeMem has only one contributing input W for Bot,
5366 // it is exactly equivalent to that state W:
5367 //   MergeMem(<Bot>: W) <==> W
5368 //
5369 // Usually, the merge has more than one input.  In that case, where inputs
5370 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5371 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5372 //   Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5373 //   Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5374 //
5375 // A merge can take a "wide" memory state as one of its narrow inputs.
5376 // This simply means that the merge observes out only the relevant parts of
5377 // the wide input.  That is, wide memory states arriving at narrow merge inputs
5378 // are implicitly "filtered" or "sliced" as necessary.  (This is rare.)
5379 //
5380 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5381 // and that memory slices "leak through":
5382 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5383 //
5384 // But, in such a cascade, repeated memory slices can "block the leak":
5385 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5386 //
5387 // In the last example, Y is not part of the combined memory state of the
5388 // outermost MergeMem.  The system must, of course, prevent unschedulable
5389 // memory states from arising, so you can be sure that the state Y is somehow
5390 // a precursor to state Y'.
5391 //
5392 //
5393 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5394 // of each MergeMemNode array are exactly the numerical alias indexes, including
5395 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw.  The functions
5396 // Compile::alias_type (and kin) produce and manage these indexes.
5397 //
5398 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5399 // (Note that this provides quick access to the top node inside MergeMem methods,
5400 // without the need to reach out via TLS to Compile::current.)
5401 //
5402 // As a consequence of what was just described, a MergeMem that represents a full
5403 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5404 // containing all alias categories.
5405 //
5406 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5407 //
5408 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5409 // a memory state for the alias type <N>, or else the top node, meaning that
5410 // there is no particular input for that alias type.  Note that the length of
5411 // a MergeMem is variable, and may be extended at any time to accommodate new
5412 // memory states at larger alias indexes.  When merges grow, they are of course
5413 // filled with "top" in the unused in() positions.
5414 //
5415 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5416 // (Top was chosen because it works smoothly with passes like GCM.)
5417 //
5418 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM.  (It is
5419 // the type of random VM bits like TLS references.)  Since it is always the
5420 // first non-Bot memory slice, some low-level loops use it to initialize an
5421 // index variable:  for (i = AliasIdxRaw; i < req(); i++).
5422 //
5423 //
5424 // ACCESSORS:  There is a special accessor MergeMemNode::base_memory which returns
5425 // the distinguished "wide" state.  The accessor MergeMemNode::memory_at(N) returns
5426 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5427 // it returns the base memory.  To prevent bugs, memory_at does not accept <Top>
5428 // or <Bot> indexes.  The iterator MergeMemStream provides robust iteration over
5429 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5430 //
5431 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5432 // really that different from the other memory inputs.  An abbreviation called
5433 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5434 //
5435 //
5436 // PARTIAL MEMORY STATES:  During optimization, MergeMem nodes may arise that represent
5437 // partial memory states.  When a Phi splits through a MergeMem, the copy of the Phi
5438 // that "emerges though" the base memory will be marked as excluding the alias types
5439 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5440 //
5441 //   Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5442 //     ==Ideal=>  MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5443 //
5444 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5445 // (It is currently unimplemented.)  As you can see, the resulting merge is
5446 // actually a disjoint union of memory states, rather than an overlay.
5447 //
5448 
5449 //------------------------------MergeMemNode-----------------------------------
5450 Node* MergeMemNode::make_empty_memory() {
5451   Node* empty_memory = (Node*) Compile::current()->top();
5452   assert(empty_memory->is_top(), "correct sentinel identity");
5453   return empty_memory;
5454 }
5455 
5456 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5457   init_class_id(Class_MergeMem);
5458   // all inputs are nullified in Node::Node(int)
5459   // set_input(0, nullptr);  // no control input
5460 
5461   // Initialize the edges uniformly to top, for starters.
5462   Node* empty_mem = make_empty_memory();
5463   for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5464     init_req(i,empty_mem);
5465   }
5466   assert(empty_memory() == empty_mem, "");
5467 
5468   if( new_base != nullptr && new_base->is_MergeMem() ) {
5469     MergeMemNode* mdef = new_base->as_MergeMem();
5470     assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5471     for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5472       mms.set_memory(mms.memory2());
5473     }
5474     assert(base_memory() == mdef->base_memory(), "");
5475   } else {
5476     set_base_memory(new_base);
5477   }
5478 }
5479 
5480 // Make a new, untransformed MergeMem with the same base as 'mem'.
5481 // If mem is itself a MergeMem, populate the result with the same edges.
5482 MergeMemNode* MergeMemNode::make(Node* mem) {
5483   return new MergeMemNode(mem);
5484 }
5485 
5486 //------------------------------cmp--------------------------------------------
5487 uint MergeMemNode::hash() const { return NO_HASH; }
5488 bool MergeMemNode::cmp( const Node &n ) const {
5489   return (&n == this);          // Always fail except on self
5490 }
5491 
5492 //------------------------------Identity---------------------------------------
5493 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5494   // Identity if this merge point does not record any interesting memory
5495   // disambiguations.
5496   Node* base_mem = base_memory();
5497   Node* empty_mem = empty_memory();
5498   if (base_mem != empty_mem) {  // Memory path is not dead?
5499     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5500       Node* mem = in(i);
5501       if (mem != empty_mem && mem != base_mem) {
5502         return this;            // Many memory splits; no change
5503       }
5504     }
5505   }
5506   return base_mem;              // No memory splits; ID on the one true input
5507 }
5508 
5509 //------------------------------Ideal------------------------------------------
5510 // This method is invoked recursively on chains of MergeMem nodes
5511 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5512   // Remove chain'd MergeMems
5513   //
5514   // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5515   // relative to the "in(Bot)".  Since we are patching both at the same time,
5516   // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5517   // but rewrite each "in(i)" relative to the new "in(Bot)".
5518   Node *progress = nullptr;
5519 
5520 
5521   Node* old_base = base_memory();
5522   Node* empty_mem = empty_memory();
5523   if (old_base == empty_mem)
5524     return nullptr; // Dead memory path.
5525 
5526   MergeMemNode* old_mbase;
5527   if (old_base != nullptr && old_base->is_MergeMem())
5528     old_mbase = old_base->as_MergeMem();
5529   else
5530     old_mbase = nullptr;
5531   Node* new_base = old_base;
5532 
5533   // simplify stacked MergeMems in base memory
5534   if (old_mbase)  new_base = old_mbase->base_memory();
5535 
5536   // the base memory might contribute new slices beyond my req()
5537   if (old_mbase)  grow_to_match(old_mbase);
5538 
5539   // Note:  We do not call verify_sparse on entry, because inputs
5540   // can normalize to the base_memory via subsume_node or similar
5541   // mechanisms.  This method repairs that damage.
5542 
5543   assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5544 
5545   // Look at each slice.
5546   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5547     Node* old_in = in(i);
5548     // calculate the old memory value
5549     Node* old_mem = old_in;
5550     if (old_mem == empty_mem)  old_mem = old_base;
5551     assert(old_mem == memory_at(i), "");
5552 
5553     // maybe update (reslice) the old memory value
5554 
5555     // simplify stacked MergeMems
5556     Node* new_mem = old_mem;
5557     MergeMemNode* old_mmem;
5558     if (old_mem != nullptr && old_mem->is_MergeMem())
5559       old_mmem = old_mem->as_MergeMem();
5560     else
5561       old_mmem = nullptr;
5562     if (old_mmem == this) {
5563       // This can happen if loops break up and safepoints disappear.
5564       // A merge of BotPtr (default) with a RawPtr memory derived from a
5565       // safepoint can be rewritten to a merge of the same BotPtr with
5566       // the BotPtr phi coming into the loop.  If that phi disappears
5567       // also, we can end up with a self-loop of the mergemem.
5568       // In general, if loops degenerate and memory effects disappear,
5569       // a mergemem can be left looking at itself.  This simply means
5570       // that the mergemem's default should be used, since there is
5571       // no longer any apparent effect on this slice.
5572       // Note: If a memory slice is a MergeMem cycle, it is unreachable
5573       //       from start.  Update the input to TOP.
5574       new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5575     }
5576     else if (old_mmem != nullptr) {
5577       new_mem = old_mmem->memory_at(i);
5578     }
5579     // else preceding memory was not a MergeMem
5580 
5581     // maybe store down a new value
5582     Node* new_in = new_mem;
5583     if (new_in == new_base)  new_in = empty_mem;
5584 
5585     if (new_in != old_in) {
5586       // Warning:  Do not combine this "if" with the previous "if"
5587       // A memory slice might have be be rewritten even if it is semantically
5588       // unchanged, if the base_memory value has changed.
5589       set_req_X(i, new_in, phase);
5590       progress = this;          // Report progress
5591     }
5592   }
5593 
5594   if (new_base != old_base) {
5595     set_req_X(Compile::AliasIdxBot, new_base, phase);
5596     // Don't use set_base_memory(new_base), because we need to update du.
5597     assert(base_memory() == new_base, "");
5598     progress = this;
5599   }
5600 
5601   if( base_memory() == this ) {
5602     // a self cycle indicates this memory path is dead
5603     set_req(Compile::AliasIdxBot, empty_mem);
5604   }
5605 
5606   // Resolve external cycles by calling Ideal on a MergeMem base_memory
5607   // Recursion must occur after the self cycle check above
5608   if( base_memory()->is_MergeMem() ) {
5609     MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5610     Node *m = phase->transform(new_mbase);  // Rollup any cycles
5611     if( m != nullptr &&
5612         (m->is_top() ||
5613          (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5614       // propagate rollup of dead cycle to self
5615       set_req(Compile::AliasIdxBot, empty_mem);
5616     }
5617   }
5618 
5619   if( base_memory() == empty_mem ) {
5620     progress = this;
5621     // Cut inputs during Parse phase only.
5622     // During Optimize phase a dead MergeMem node will be subsumed by Top.
5623     if( !can_reshape ) {
5624       for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5625         if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5626       }
5627     }
5628   }
5629 
5630   if( !progress && base_memory()->is_Phi() && can_reshape ) {
5631     // Check if PhiNode::Ideal's "Split phis through memory merges"
5632     // transform should be attempted. Look for this->phi->this cycle.
5633     uint merge_width = req();
5634     if (merge_width > Compile::AliasIdxRaw) {
5635       PhiNode* phi = base_memory()->as_Phi();
5636       for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5637         if (phi->in(i) == this) {
5638           phase->is_IterGVN()->_worklist.push(phi);
5639           break;
5640         }
5641       }
5642     }
5643   }
5644 
5645   assert(progress || verify_sparse(), "please, no dups of base");
5646   return progress;
5647 }
5648 
5649 //-------------------------set_base_memory-------------------------------------
5650 void MergeMemNode::set_base_memory(Node *new_base) {
5651   Node* empty_mem = empty_memory();
5652   set_req(Compile::AliasIdxBot, new_base);
5653   assert(memory_at(req()) == new_base, "must set default memory");
5654   // Clear out other occurrences of new_base:
5655   if (new_base != empty_mem) {
5656     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5657       if (in(i) == new_base)  set_req(i, empty_mem);
5658     }
5659   }
5660 }
5661 
5662 //------------------------------out_RegMask------------------------------------
5663 const RegMask &MergeMemNode::out_RegMask() const {
5664   return RegMask::Empty;
5665 }
5666 
5667 //------------------------------dump_spec--------------------------------------
5668 #ifndef PRODUCT
5669 void MergeMemNode::dump_spec(outputStream *st) const {
5670   st->print(" {");
5671   Node* base_mem = base_memory();
5672   for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5673     Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
5674     if (mem == base_mem) { st->print(" -"); continue; }
5675     st->print( " N%d:", mem->_idx );
5676     Compile::current()->get_adr_type(i)->dump_on(st);
5677   }
5678   st->print(" }");
5679 }
5680 #endif // !PRODUCT
5681 
5682 
5683 #ifdef ASSERT
5684 static bool might_be_same(Node* a, Node* b) {
5685   if (a == b)  return true;
5686   if (!(a->is_Phi() || b->is_Phi()))  return false;
5687   // phis shift around during optimization
5688   return true;  // pretty stupid...
5689 }
5690 
5691 // verify a narrow slice (either incoming or outgoing)
5692 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5693   if (!VerifyAliases)                return;  // don't bother to verify unless requested
5694   if (VMError::is_error_reported())  return;  // muzzle asserts when debugging an error
5695   if (Node::in_dump())               return;  // muzzle asserts when printing
5696   assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5697   assert(n != nullptr, "");
5698   // Elide intervening MergeMem's
5699   while (n->is_MergeMem()) {
5700     n = n->as_MergeMem()->memory_at(alias_idx);
5701   }
5702   Compile* C = Compile::current();
5703   const TypePtr* n_adr_type = n->adr_type();
5704   if (n == m->empty_memory()) {
5705     // Implicit copy of base_memory()
5706   } else if (n_adr_type != TypePtr::BOTTOM) {
5707     assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
5708     assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5709   } else {
5710     // A few places like make_runtime_call "know" that VM calls are narrow,
5711     // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5712     bool expected_wide_mem = false;
5713     if (n == m->base_memory()) {
5714       expected_wide_mem = true;
5715     } else if (alias_idx == Compile::AliasIdxRaw ||
5716                n == m->memory_at(Compile::AliasIdxRaw)) {
5717       expected_wide_mem = true;
5718     } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5719       // memory can "leak through" calls on channels that
5720       // are write-once.  Allow this also.
5721       expected_wide_mem = true;
5722     }
5723     assert(expected_wide_mem, "expected narrow slice replacement");
5724   }
5725 }
5726 #else // !ASSERT
5727 #define verify_memory_slice(m,i,n) (void)(0)  // PRODUCT version is no-op
5728 #endif
5729 
5730 
5731 //-----------------------------memory_at---------------------------------------
5732 Node* MergeMemNode::memory_at(uint alias_idx) const {
5733   assert(alias_idx >= Compile::AliasIdxRaw ||
5734          (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
5735          "must avoid base_memory and AliasIdxTop");
5736 
5737   // Otherwise, it is a narrow slice.
5738   Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5739   if (is_empty_memory(n)) {
5740     // the array is sparse; empty slots are the "top" node
5741     n = base_memory();
5742     assert(Node::in_dump()
5743            || n == nullptr || n->bottom_type() == Type::TOP
5744            || n->adr_type() == nullptr // address is TOP
5745            || n->adr_type() == TypePtr::BOTTOM
5746            || n->adr_type() == TypeRawPtr::BOTTOM
5747            || !Compile::current()->do_aliasing(),
5748            "must be a wide memory");
5749     // do_aliasing == false if we are organizing the memory states manually.
5750     // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5751   } else {
5752     // make sure the stored slice is sane
5753     #ifdef ASSERT
5754     if (VMError::is_error_reported() || Node::in_dump()) {
5755     } else if (might_be_same(n, base_memory())) {
5756       // Give it a pass:  It is a mostly harmless repetition of the base.
5757       // This can arise normally from node subsumption during optimization.
5758     } else {
5759       verify_memory_slice(this, alias_idx, n);
5760     }
5761     #endif
5762   }
5763   return n;
5764 }
5765 
5766 //---------------------------set_memory_at-------------------------------------
5767 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5768   verify_memory_slice(this, alias_idx, n);
5769   Node* empty_mem = empty_memory();
5770   if (n == base_memory())  n = empty_mem;  // collapse default
5771   uint need_req = alias_idx+1;
5772   if (req() < need_req) {
5773     if (n == empty_mem)  return;  // already the default, so do not grow me
5774     // grow the sparse array
5775     do {
5776       add_req(empty_mem);
5777     } while (req() < need_req);
5778   }
5779   set_req( alias_idx, n );
5780 }
5781 
5782 
5783 
5784 //--------------------------iteration_setup------------------------------------
5785 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5786   if (other != nullptr) {
5787     grow_to_match(other);
5788     // invariant:  the finite support of mm2 is within mm->req()
5789     #ifdef ASSERT
5790     for (uint i = req(); i < other->req(); i++) {
5791       assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5792     }
5793     #endif
5794   }
5795   // Replace spurious copies of base_memory by top.
5796   Node* base_mem = base_memory();
5797   if (base_mem != nullptr && !base_mem->is_top()) {
5798     for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5799       if (in(i) == base_mem)
5800         set_req(i, empty_memory());
5801     }
5802   }
5803 }
5804 
5805 //---------------------------grow_to_match-------------------------------------
5806 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5807   Node* empty_mem = empty_memory();
5808   assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5809   // look for the finite support of the other memory
5810   for (uint i = other->req(); --i >= req(); ) {
5811     if (other->in(i) != empty_mem) {
5812       uint new_len = i+1;
5813       while (req() < new_len)  add_req(empty_mem);
5814       break;
5815     }
5816   }
5817 }
5818 
5819 //---------------------------verify_sparse-------------------------------------
5820 #ifndef PRODUCT
5821 bool MergeMemNode::verify_sparse() const {
5822   assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5823   Node* base_mem = base_memory();
5824   // The following can happen in degenerate cases, since empty==top.
5825   if (is_empty_memory(base_mem))  return true;
5826   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5827     assert(in(i) != nullptr, "sane slice");
5828     if (in(i) == base_mem)  return false;  // should have been the sentinel value!
5829   }
5830   return true;
5831 }
5832 
5833 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5834   Node* n;
5835   n = mm->in(idx);
5836   if (mem == n)  return true;  // might be empty_memory()
5837   n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5838   if (mem == n)  return true;
5839   return false;
5840 }
5841 #endif // !PRODUCT