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