1 /*
   2  * Copyright (c) 1997, 2021, 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 == NULL)  return NULL; // node is dead
  72   const TypePtr* cross_check = NULL;
  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 != NULL) {
  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) == NULL)  return; // node is dead
  89 #ifndef ASSERT
  90   // fake the missing field
  91   const TypePtr* _adr_type = NULL;
  92   if (in(Address) != NULL)
  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 == NULL) {
 115     st->print("NULL");
 116   } else {
 117     adr_type->dump_on(st);
 118     Compile* C = Compile::current();
 119     Compile::AliasType* atp = NULL;
 120     if (C->have_alias_type(adr_type))  atp = C->alias_type(adr_type);
 121     if (atp == NULL)
 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 != NULL), "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 != NULL) && load->is_Load() &&
 149                              (phase->is_IterGVN() != NULL);
 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 = NULL;
 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 == NULL) || (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->klass()->equals(t_oop->klass())) {
 184             result = proj_in->in(TypeFunc::Memory); // not related allocation
 185           }
 186         }
 187       } else if (proj_in->is_MemBar()) {
 188         ArrayCopyNode* ac = NULL;
 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 {
 194         assert(false, "unexpected projection");
 195       }
 196     } else if (result->is_ClearArray()) {
 197       if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
 198         // Can not bypass initialization of the instance
 199         // we are looking for.
 200         break;
 201       }
 202       // Otherwise skip it (the call updated 'result' value).
 203     } else if (result->is_MergeMem()) {
 204       result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
 205     }
 206   }
 207   return result;
 208 }
 209 
 210 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
 211   const TypeOopPtr* t_oop = t_adr->isa_oopptr();
 212   if (t_oop == NULL)
 213     return mchain;  // don't try to optimize non-oop types
 214   Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
 215   bool is_instance = t_oop->is_known_instance_field();
 216   PhaseIterGVN *igvn = phase->is_IterGVN();
 217   if (is_instance && igvn != NULL && result->is_Phi()) {
 218     PhiNode *mphi = result->as_Phi();
 219     assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
 220     const TypePtr *t = mphi->adr_type();
 221     if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
 222         (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
 223          t->is_oopptr()->cast_to_exactness(true)
 224            ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
 225             ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
 226       // clone the Phi with our address type
 227       result = mphi->split_out_instance(t_adr, igvn);
 228     } else {
 229       assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
 230     }
 231   }
 232   return result;
 233 }
 234 
 235 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem,  const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
 236   uint alias_idx = phase->C->get_alias_index(tp);
 237   Node *mem = mmem;
 238 #ifdef ASSERT
 239   {
 240     // Check that current type is consistent with the alias index used during graph construction
 241     assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
 242     bool consistent =  adr_check == NULL || adr_check->empty() ||
 243                        phase->C->must_alias(adr_check, alias_idx );
 244     // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
 245     if( !consistent && adr_check != NULL && !adr_check->empty() &&
 246         tp->isa_aryptr() &&        tp->offset() == Type::OffsetBot &&
 247         adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
 248         ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
 249           adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
 250           adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
 251       // don't assert if it is dead code.
 252       consistent = true;
 253     }
 254     if( !consistent ) {
 255       st->print("alias_idx==%d, adr_check==", alias_idx);
 256       if( adr_check == NULL ) {
 257         st->print("NULL");
 258       } else {
 259         adr_check->dump();
 260       }
 261       st->cr();
 262       print_alias_types();
 263       assert(consistent, "adr_check must match alias idx");
 264     }
 265   }
 266 #endif
 267   // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
 268   // means an array I have not precisely typed yet.  Do not do any
 269   // alias stuff with it any time soon.
 270   const TypeOopPtr *toop = tp->isa_oopptr();
 271   if( tp->base() != Type::AnyPtr &&
 272       !(toop &&
 273         toop->klass() != NULL &&
 274         toop->klass()->is_java_lang_Object() &&
 275         toop->offset() == Type::OffsetBot) ) {
 276     // compress paths and change unreachable cycles to TOP
 277     // If not, we can update the input infinitely along a MergeMem cycle
 278     // Equivalent code in PhiNode::Ideal
 279     Node* m  = phase->transform(mmem);
 280     // If transformed to a MergeMem, get the desired slice
 281     // Otherwise the returned node represents memory for every slice
 282     mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
 283     // Update input if it is progress over what we have now
 284   }
 285   return mem;
 286 }
 287 
 288 //--------------------------Ideal_common---------------------------------------
 289 // Look for degenerate control and memory inputs.  Bypass MergeMem inputs.
 290 // Unhook non-raw memories from complete (macro-expanded) initializations.
 291 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
 292   // If our control input is a dead region, kill all below the region
 293   Node *ctl = in(MemNode::Control);
 294   if (ctl && remove_dead_region(phase, can_reshape))
 295     return this;
 296   ctl = in(MemNode::Control);
 297   // Don't bother trying to transform a dead node
 298   if (ctl && ctl->is_top())  return NodeSentinel;
 299 
 300   PhaseIterGVN *igvn = phase->is_IterGVN();
 301   // Wait if control on the worklist.
 302   if (ctl && can_reshape && igvn != NULL) {
 303     Node* bol = NULL;
 304     Node* cmp = NULL;
 305     if (ctl->in(0)->is_If()) {
 306       assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
 307       bol = ctl->in(0)->in(1);
 308       if (bol->is_Bool())
 309         cmp = ctl->in(0)->in(1)->in(1);
 310     }
 311     if (igvn->_worklist.member(ctl) ||
 312         (bol != NULL && igvn->_worklist.member(bol)) ||
 313         (cmp != NULL && igvn->_worklist.member(cmp)) ) {
 314       // This control path may be dead.
 315       // Delay this memory node transformation until the control is processed.
 316       igvn->_worklist.push(this);
 317       return NodeSentinel; // caller will return NULL
 318     }
 319   }
 320   // Ignore if memory is dead, or self-loop
 321   Node *mem = in(MemNode::Memory);
 322   if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
 323   assert(mem != this, "dead loop in MemNode::Ideal");
 324 
 325   if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
 326     // This memory slice may be dead.
 327     // Delay this mem node transformation until the memory is processed.
 328     igvn->_worklist.push(this);
 329     return NodeSentinel; // caller will return NULL
 330   }
 331 
 332   Node *address = in(MemNode::Address);
 333   const Type *t_adr = phase->type(address);
 334   if (t_adr == Type::TOP)              return NodeSentinel; // caller will return NULL
 335 
 336   if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
 337     // Unsafe off-heap access with zero address. Remove access and other control users
 338     // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
 339     assert(ctl != NULL, "unsafe accesses should be control dependent");
 340     for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
 341       Node* u = ctl->fast_out(i);
 342       if (u != ctl) {
 343         igvn->rehash_node_delayed(u);
 344         int nb = u->replace_edge(ctl, phase->C->top(), igvn);
 345         --i, imax -= nb;
 346       }
 347     }
 348     Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
 349     Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
 350     phase->C->root()->add_req(halt);
 351     return this;
 352   }
 353 
 354   if (can_reshape && igvn != NULL &&
 355       (igvn->_worklist.member(address) ||
 356        (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
 357     // The address's base and type may change when the address is processed.
 358     // Delay this mem node transformation until the address is processed.
 359     igvn->_worklist.push(this);
 360     return NodeSentinel; // caller will return NULL
 361   }
 362 
 363   // Do NOT remove or optimize the next lines: ensure a new alias index
 364   // is allocated for an oop pointer type before Escape Analysis.
 365   // Note: C++ will not remove it since the call has side effect.
 366   if (t_adr->isa_oopptr()) {
 367     int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
 368   }
 369 
 370   Node* base = NULL;
 371   if (address->is_AddP()) {
 372     base = address->in(AddPNode::Base);
 373   }
 374   if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
 375       !t_adr->isa_rawptr()) {
 376     // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
 377     // Skip this node optimization if its address has TOP base.
 378     return NodeSentinel; // caller will return NULL
 379   }
 380 
 381   // Avoid independent memory operations
 382   Node* old_mem = mem;
 383 
 384   // The code which unhooks non-raw memories from complete (macro-expanded)
 385   // initializations was removed. After macro-expansion all stores catched
 386   // by Initialize node became raw stores and there is no information
 387   // which memory slices they modify. So it is unsafe to move any memory
 388   // operation above these stores. Also in most cases hooked non-raw memories
 389   // were already unhooked by using information from detect_ptr_independence()
 390   // and find_previous_store().
 391 
 392   if (mem->is_MergeMem()) {
 393     MergeMemNode* mmem = mem->as_MergeMem();
 394     const TypePtr *tp = t_adr->is_ptr();
 395 
 396     mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
 397   }
 398 
 399   if (mem != old_mem) {
 400     set_req(MemNode::Memory, mem);
 401     if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
 402       igvn->_worklist.push(old_mem);
 403     }
 404     if (phase->type(mem) == Type::TOP) return NodeSentinel;
 405     return this;
 406   }
 407 
 408   // let the subclass continue analyzing...
 409   return NULL;
 410 }
 411 
 412 // Helper function for proving some simple control dominations.
 413 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
 414 // Already assumes that 'dom' is available at 'sub', and that 'sub'
 415 // is not a constant (dominated by the method's StartNode).
 416 // Used by MemNode::find_previous_store to prove that the
 417 // control input of a memory operation predates (dominates)
 418 // an allocation it wants to look past.
 419 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
 420   if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
 421     return false; // Conservative answer for dead code
 422 
 423   // Check 'dom'. Skip Proj and CatchProj nodes.
 424   dom = dom->find_exact_control(dom);
 425   if (dom == NULL || dom->is_top())
 426     return false; // Conservative answer for dead code
 427 
 428   if (dom == sub) {
 429     // For the case when, for example, 'sub' is Initialize and the original
 430     // 'dom' is Proj node of the 'sub'.
 431     return false;
 432   }
 433 
 434   if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
 435     return true;
 436 
 437   // 'dom' dominates 'sub' if its control edge and control edges
 438   // of all its inputs dominate or equal to sub's control edge.
 439 
 440   // Currently 'sub' is either Allocate, Initialize or Start nodes.
 441   // Or Region for the check in LoadNode::Ideal();
 442   // 'sub' should have sub->in(0) != NULL.
 443   assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
 444          sub->is_Region() || sub->is_Call(), "expecting only these nodes");
 445 
 446   // Get control edge of 'sub'.
 447   Node* orig_sub = sub;
 448   sub = sub->find_exact_control(sub->in(0));
 449   if (sub == NULL || sub->is_top())
 450     return false; // Conservative answer for dead code
 451 
 452   assert(sub->is_CFG(), "expecting control");
 453 
 454   if (sub == dom)
 455     return true;
 456 
 457   if (sub->is_Start() || sub->is_Root())
 458     return false;
 459 
 460   {
 461     // Check all control edges of 'dom'.
 462 
 463     ResourceMark rm;
 464     Node_List nlist;
 465     Unique_Node_List dom_list;
 466 
 467     dom_list.push(dom);
 468     bool only_dominating_controls = false;
 469 
 470     for (uint next = 0; next < dom_list.size(); next++) {
 471       Node* n = dom_list.at(next);
 472       if (n == orig_sub)
 473         return false; // One of dom's inputs dominated by sub.
 474       if (!n->is_CFG() && n->pinned()) {
 475         // Check only own control edge for pinned non-control nodes.
 476         n = n->find_exact_control(n->in(0));
 477         if (n == NULL || n->is_top())
 478           return false; // Conservative answer for dead code
 479         assert(n->is_CFG(), "expecting control");
 480         dom_list.push(n);
 481       } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
 482         only_dominating_controls = true;
 483       } else if (n->is_CFG()) {
 484         if (n->dominates(sub, nlist))
 485           only_dominating_controls = true;
 486         else
 487           return false;
 488       } else {
 489         // First, own control edge.
 490         Node* m = n->find_exact_control(n->in(0));
 491         if (m != NULL) {
 492           if (m->is_top())
 493             return false; // Conservative answer for dead code
 494           dom_list.push(m);
 495         }
 496         // Now, the rest of edges.
 497         uint cnt = n->req();
 498         for (uint i = 1; i < cnt; i++) {
 499           m = n->find_exact_control(n->in(i));
 500           if (m == NULL || m->is_top())
 501             continue;
 502           dom_list.push(m);
 503         }
 504       }
 505     }
 506     return only_dominating_controls;
 507   }
 508 }
 509 
 510 //---------------------detect_ptr_independence---------------------------------
 511 // Used by MemNode::find_previous_store to prove that two base
 512 // pointers are never equal.
 513 // The pointers are accompanied by their associated allocations,
 514 // if any, which have been previously discovered by the caller.
 515 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
 516                                       Node* p2, AllocateNode* a2,
 517                                       PhaseTransform* phase) {
 518   // Attempt to prove that these two pointers cannot be aliased.
 519   // They may both manifestly be allocations, and they should differ.
 520   // Or, if they are not both allocations, they can be distinct constants.
 521   // Otherwise, one is an allocation and the other a pre-existing value.
 522   if (a1 == NULL && a2 == NULL) {           // neither an allocation
 523     return (p1 != p2) && p1->is_Con() && p2->is_Con();
 524   } else if (a1 != NULL && a2 != NULL) {    // both allocations
 525     return (a1 != a2);
 526   } else if (a1 != NULL) {                  // one allocation a1
 527     // (Note:  p2->is_Con implies p2->in(0)->is_Root, which dominates.)
 528     return all_controls_dominate(p2, a1);
 529   } else { //(a2 != NULL)                   // one allocation a2
 530     return all_controls_dominate(p1, a2);
 531   }
 532   return false;
 533 }
 534 
 535 
 536 // Find an arraycopy ac that produces the memory state represented by parameter mem.
 537 // Return ac if
 538 // (a) can_see_stored_value=true  and ac must have set the value for this load or if
 539 // (b) can_see_stored_value=false and ac could have set the value for this load or if
 540 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
 541 // In case (c) change the parameter mem to the memory input of ac to skip it
 542 // when searching stored value.
 543 // Otherwise return NULL.
 544 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
 545   ArrayCopyNode* ac = find_array_copy_clone(phase, ld_alloc, mem);
 546   if (ac != NULL) {
 547     Node* ld_addp = in(MemNode::Address);
 548     Node* src = ac->in(ArrayCopyNode::Src);
 549     const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
 550 
 551     // This is a load from a cloned array. The corresponding arraycopy ac must
 552     // have set the value for the load and we can return ac but only if the load
 553     // is known to be within bounds. This is checked below.
 554     if (ary_t != NULL && ld_addp->is_AddP()) {
 555       Node* ld_offs = ld_addp->in(AddPNode::Offset);
 556       BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
 557       jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
 558       jlong elemsize = type2aelembytes(ary_elem);
 559 
 560       const TypeX*   ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 561       const TypeInt* sizetype  = ary_t->size();
 562 
 563       if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
 564         // The load is known to be within bounds. It receives its value from ac.
 565         return ac;
 566       }
 567       // The load is known to be out-of-bounds.
 568     }
 569     // The load could be out-of-bounds. It must not be hoisted but must remain
 570     // dependent on the runtime range check. This is achieved by returning NULL.
 571   } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
 572     ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
 573 
 574     if (ac->is_arraycopy_validated() ||
 575         ac->is_copyof_validated() ||
 576         ac->is_copyofrange_validated()) {
 577       Node* ld_addp = in(MemNode::Address);
 578       if (ld_addp->is_AddP()) {
 579         Node* ld_base = ld_addp->in(AddPNode::Address);
 580         Node* ld_offs = ld_addp->in(AddPNode::Offset);
 581 
 582         Node* dest = ac->in(ArrayCopyNode::Dest);
 583 
 584         if (dest == ld_base) {
 585           const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
 586           if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
 587             return ac;
 588           }
 589           if (!can_see_stored_value) {
 590             mem = ac->in(TypeFunc::Memory);
 591             return ac;
 592           }
 593         }
 594       }
 595     }
 596   }
 597   return NULL;
 598 }
 599 
 600 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseTransform* phase, Node* ld_alloc, Node* mem) const {
 601   if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
 602                                                mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
 603     if (ld_alloc != NULL) {
 604       // Check if there is an array copy for a clone
 605       Node* mb = mem->in(0);
 606       ArrayCopyNode* ac = NULL;
 607       if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
 608           mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
 609         ac = mb->in(0)->in(0)->as_ArrayCopy();
 610       } else {
 611         // Step over GC barrier when ReduceInitialCardMarks is disabled
 612         BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 613         Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
 614 
 615         if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
 616           ac = control_proj_ac->in(0)->as_ArrayCopy();
 617         }
 618       }
 619 
 620       if (ac != NULL && ac->is_clonebasic()) {
 621         AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase);
 622         if (alloc != NULL && alloc == ld_alloc) {
 623           return ac;
 624         }
 625       }
 626     }
 627   }
 628   return NULL;
 629 }
 630 
 631 // The logic for reordering loads and stores uses four steps:
 632 // (a) Walk carefully past stores and initializations which we
 633 //     can prove are independent of this load.
 634 // (b) Observe that the next memory state makes an exact match
 635 //     with self (load or store), and locate the relevant store.
 636 // (c) Ensure that, if we were to wire self directly to the store,
 637 //     the optimizer would fold it up somehow.
 638 // (d) Do the rewiring, and return, depending on some other part of
 639 //     the optimizer to fold up the load.
 640 // This routine handles steps (a) and (b).  Steps (c) and (d) are
 641 // specific to loads and stores, so they are handled by the callers.
 642 // (Currently, only LoadNode::Ideal has steps (c), (d).  More later.)
 643 //
 644 Node* MemNode::find_previous_store(PhaseTransform* phase) {
 645   Node*         ctrl   = in(MemNode::Control);
 646   Node*         adr    = in(MemNode::Address);
 647   intptr_t      offset = 0;
 648   Node*         base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
 649   AllocateNode* alloc  = AllocateNode::Ideal_allocation(base, phase);
 650 
 651   if (offset == Type::OffsetBot)
 652     return NULL;            // cannot unalias unless there are precise offsets
 653 
 654   const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
 655   const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
 656 
 657   intptr_t size_in_bytes = memory_size();
 658 
 659   Node* mem = in(MemNode::Memory);   // start searching here...
 660 
 661   int cnt = 50;             // Cycle limiter
 662   for (;;) {                // While we can dance past unrelated stores...
 663     if (--cnt < 0)  break;  // Caught in cycle or a complicated dance?
 664 
 665     Node* prev = mem;
 666     if (mem->is_Store()) {
 667       Node* st_adr = mem->in(MemNode::Address);
 668       intptr_t st_offset = 0;
 669       Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
 670       if (st_base == NULL)
 671         break;              // inscrutable pointer
 672 
 673       // For raw accesses it's not enough to prove that constant offsets don't intersect.
 674       // We need the bases to be the equal in order for the offset check to make sense.
 675       if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
 676         break;
 677       }
 678 
 679       if (st_offset != offset && st_offset != Type::OffsetBot) {
 680         const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
 681         assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
 682         if (st_offset >= offset + size_in_bytes ||
 683             st_offset <= offset - MAX_STORE ||
 684             st_offset <= offset - mem->as_Store()->memory_size()) {
 685           // Success:  The offsets are provably independent.
 686           // (You may ask, why not just test st_offset != offset and be done?
 687           // The answer is that stores of different sizes can co-exist
 688           // in the same sequence of RawMem effects.  We sometimes initialize
 689           // a whole 'tile' of array elements with a single jint or jlong.)
 690           mem = mem->in(MemNode::Memory);
 691           continue;           // (a) advance through independent store memory
 692         }
 693       }
 694       if (st_base != base &&
 695           detect_ptr_independence(base, alloc,
 696                                   st_base,
 697                                   AllocateNode::Ideal_allocation(st_base, phase),
 698                                   phase)) {
 699         // Success:  The bases are provably independent.
 700         mem = mem->in(MemNode::Memory);
 701         continue;           // (a) advance through independent store memory
 702       }
 703 
 704       // (b) At this point, if the bases or offsets do not agree, we lose,
 705       // since we have not managed to prove 'this' and 'mem' independent.
 706       if (st_base == base && st_offset == offset) {
 707         return mem;         // let caller handle steps (c), (d)
 708       }
 709 
 710     } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
 711       InitializeNode* st_init = mem->in(0)->as_Initialize();
 712       AllocateNode*  st_alloc = st_init->allocation();
 713       if (st_alloc == NULL)
 714         break;              // something degenerated
 715       bool known_identical = false;
 716       bool known_independent = false;
 717       if (alloc == st_alloc)
 718         known_identical = true;
 719       else if (alloc != NULL)
 720         known_independent = true;
 721       else if (all_controls_dominate(this, st_alloc))
 722         known_independent = true;
 723 
 724       if (known_independent) {
 725         // The bases are provably independent: Either they are
 726         // manifestly distinct allocations, or else the control
 727         // of this load dominates the store's allocation.
 728         int alias_idx = phase->C->get_alias_index(adr_type());
 729         if (alias_idx == Compile::AliasIdxRaw) {
 730           mem = st_alloc->in(TypeFunc::Memory);
 731         } else {
 732           mem = st_init->memory(alias_idx);
 733         }
 734         continue;           // (a) advance through independent store memory
 735       }
 736 
 737       // (b) at this point, if we are not looking at a store initializing
 738       // the same allocation we are loading from, we lose.
 739       if (known_identical) {
 740         // From caller, can_see_stored_value will consult find_captured_store.
 741         return mem;         // let caller handle steps (c), (d)
 742       }
 743 
 744     } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
 745       if (prev != mem) {
 746         // Found an arraycopy but it doesn't affect that load
 747         continue;
 748       }
 749       // Found an arraycopy that may affect that load
 750       return mem;
 751     } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
 752       // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
 753       if (mem->is_Proj() && mem->in(0)->is_Call()) {
 754         // ArrayCopyNodes processed here as well.
 755         CallNode *call = mem->in(0)->as_Call();
 756         if (!call->may_modify(addr_t, phase)) {
 757           mem = call->in(TypeFunc::Memory);
 758           continue;         // (a) advance through independent call memory
 759         }
 760       } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
 761         ArrayCopyNode* ac = NULL;
 762         if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
 763           break;
 764         }
 765         mem = mem->in(0)->in(TypeFunc::Memory);
 766         continue;           // (a) advance through independent MemBar memory
 767       } else if (mem->is_ClearArray()) {
 768         if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
 769           // (the call updated 'mem' value)
 770           continue;         // (a) advance through independent allocation memory
 771         } else {
 772           // Can not bypass initialization of the instance
 773           // we are looking for.
 774           return mem;
 775         }
 776       } else if (mem->is_MergeMem()) {
 777         int alias_idx = phase->C->get_alias_index(adr_type());
 778         mem = mem->as_MergeMem()->memory_at(alias_idx);
 779         continue;           // (a) advance through independent MergeMem memory
 780       }
 781     }
 782 
 783     // Unless there is an explicit 'continue', we must bail out here,
 784     // because 'mem' is an inscrutable memory state (e.g., a call).
 785     break;
 786   }
 787 
 788   return NULL;              // bail out
 789 }
 790 
 791 //----------------------calculate_adr_type-------------------------------------
 792 // Helper function.  Notices when the given type of address hits top or bottom.
 793 // Also, asserts a cross-check of the type against the expected address type.
 794 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
 795   if (t == Type::TOP)  return NULL; // does not touch memory any more?
 796   #ifdef ASSERT
 797   if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump())  cross_check = NULL;
 798   #endif
 799   const TypePtr* tp = t->isa_ptr();
 800   if (tp == NULL) {
 801     assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
 802     return TypePtr::BOTTOM;           // touches lots of memory
 803   } else {
 804     #ifdef ASSERT
 805     // %%%% [phh] We don't check the alias index if cross_check is
 806     //            TypeRawPtr::BOTTOM.  Needs to be investigated.
 807     if (cross_check != NULL &&
 808         cross_check != TypePtr::BOTTOM &&
 809         cross_check != TypeRawPtr::BOTTOM) {
 810       // Recheck the alias index, to see if it has changed (due to a bug).
 811       Compile* C = Compile::current();
 812       assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
 813              "must stay in the original alias category");
 814       // The type of the address must be contained in the adr_type,
 815       // disregarding "null"-ness.
 816       // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
 817       const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
 818       assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
 819              "real address must not escape from expected memory type");
 820     }
 821     #endif
 822     return tp;
 823   }
 824 }
 825 
 826 //=============================================================================
 827 // Should LoadNode::Ideal() attempt to remove control edges?
 828 bool LoadNode::can_remove_control() const {
 829   return true;
 830 }
 831 uint LoadNode::size_of() const { return sizeof(*this); }
 832 bool LoadNode::cmp( const Node &n ) const
 833 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
 834 const Type *LoadNode::bottom_type() const { return _type; }
 835 uint LoadNode::ideal_reg() const {
 836   return _type->ideal_reg();
 837 }
 838 
 839 #ifndef PRODUCT
 840 void LoadNode::dump_spec(outputStream *st) const {
 841   MemNode::dump_spec(st);
 842   if( !Verbose && !WizardMode ) {
 843     // standard dump does this in Verbose and WizardMode
 844     st->print(" #"); _type->dump_on(st);
 845   }
 846   if (!depends_only_on_test()) {
 847     st->print(" (does not depend only on test)");
 848   }
 849 }
 850 #endif
 851 
 852 #ifdef ASSERT
 853 //----------------------------is_immutable_value-------------------------------
 854 // Helper function to allow a raw load without control edge for some cases
 855 bool LoadNode::is_immutable_value(Node* adr) {
 856   return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
 857           adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
 858           (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
 859            in_bytes(JavaThread::osthread_offset()) ||
 860            adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
 861            in_bytes(JavaThread::threadObj_offset())));
 862 }
 863 #endif
 864 
 865 //----------------------------LoadNode::make-----------------------------------
 866 // Polymorphic factory method:
 867 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
 868                      ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
 869   Compile* C = gvn.C;
 870 
 871   // sanity check the alias category against the created node type
 872   assert(!(adr_type->isa_oopptr() &&
 873            adr_type->offset() == oopDesc::klass_offset_in_bytes()),
 874          "use LoadKlassNode instead");
 875   assert(!(adr_type->isa_aryptr() &&
 876            adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
 877          "use LoadRangeNode instead");
 878   // Check control edge of raw loads
 879   assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
 880           // oop will be recorded in oop map if load crosses safepoint
 881           rt->isa_oopptr() || is_immutable_value(adr),
 882           "raw memory operations should have control edge");
 883   LoadNode* load = NULL;
 884   switch (bt) {
 885   case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 886   case T_BYTE:    load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 887   case T_INT:     load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 888   case T_CHAR:    load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 889   case T_SHORT:   load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency); break;
 890   case T_LONG:    load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
 891   case T_FLOAT:   load = new LoadFNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency); break;
 892   case T_DOUBLE:  load = new LoadDNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency); break;
 893   case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(),  mo, control_dependency); break;
 894   case T_PRIMITIVE_OBJECT:
 895   case T_OBJECT:
 896 #ifdef _LP64
 897     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
 898       load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
 899     } else
 900 #endif
 901     {
 902       assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
 903       load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
 904     }
 905     break;
 906   default:
 907     ShouldNotReachHere();
 908     break;
 909   }
 910   assert(load != NULL, "LoadNode should have been created");
 911   if (unaligned) {
 912     load->set_unaligned_access();
 913   }
 914   if (mismatched) {
 915     load->set_mismatched_access();
 916   }
 917   if (unsafe) {
 918     load->set_unsafe_access();
 919   }
 920   load->set_barrier_data(barrier_data);
 921   if (load->Opcode() == Op_LoadN) {
 922     Node* ld = gvn.transform(load);
 923     return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
 924   }
 925 
 926   return load;
 927 }
 928 
 929 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
 930                                   ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
 931   bool require_atomic = true;
 932   LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
 933   if (unaligned) {
 934     load->set_unaligned_access();
 935   }
 936   if (mismatched) {
 937     load->set_mismatched_access();
 938   }
 939   if (unsafe) {
 940     load->set_unsafe_access();
 941   }
 942   load->set_barrier_data(barrier_data);
 943   return load;
 944 }
 945 
 946 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
 947                                   ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
 948   bool require_atomic = true;
 949   LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
 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   return load;
 961 }
 962 
 963 
 964 
 965 //------------------------------hash-------------------------------------------
 966 uint LoadNode::hash() const {
 967   // unroll addition of interesting fields
 968   return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
 969 }
 970 
 971 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
 972   if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
 973     bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
 974     bool is_stable_ary = FoldStableValues &&
 975                          (tp != NULL) && (tp->isa_aryptr() != NULL) &&
 976                          tp->isa_aryptr()->is_stable();
 977 
 978     return (eliminate_boxing && non_volatile) || is_stable_ary;
 979   }
 980 
 981   return false;
 982 }
 983 
 984 // Is the value loaded previously stored by an arraycopy? If so return
 985 // a load node that reads from the source array so we may be able to
 986 // optimize out the ArrayCopy node later.
 987 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
 988   Node* ld_adr = in(MemNode::Address);
 989   intptr_t ld_off = 0;
 990   AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
 991   Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
 992   if (ac != NULL) {
 993     assert(ac->is_ArrayCopy(), "what kind of node can this be?");
 994 
 995     Node* mem = ac->in(TypeFunc::Memory);
 996     Node* ctl = ac->in(0);
 997     Node* src = ac->in(ArrayCopyNode::Src);
 998 
 999     if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1000       return NULL;
1001     }
1002 
1003     LoadNode* ld = clone()->as_Load();
1004     Node* addp = in(MemNode::Address)->clone();
1005     if (ac->as_ArrayCopy()->is_clonebasic()) {
1006       assert(ld_alloc != NULL, "need an alloc");
1007       assert(addp->is_AddP(), "address must be addp");
1008       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1009       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1010       assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1011       addp->set_req(AddPNode::Base, src);
1012       addp->set_req(AddPNode::Address, src);
1013     } else {
1014       assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1015              ac->as_ArrayCopy()->is_copyof_validated() ||
1016              ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1017       assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1018       addp->set_req(AddPNode::Base, src);
1019       addp->set_req(AddPNode::Address, src);
1020 
1021       const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1022       BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
1023       uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1024       uint shift  = exact_log2(type2aelembytes(ary_elem));
1025       if (ary_t->klass()->is_flat_array_klass()) {
1026         ciFlatArrayKlass* vak = ary_t->klass()->as_flat_array_klass();
1027         shift = vak->log2_element_size();
1028       }
1029 
1030       Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1031 #ifdef _LP64
1032       diff = phase->transform(new ConvI2LNode(diff));
1033 #endif
1034       diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1035 
1036       Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1037       addp->set_req(AddPNode::Offset, offset);
1038     }
1039     addp = phase->transform(addp);
1040 #ifdef ASSERT
1041     const TypePtr* adr_type = phase->type(addp)->is_ptr();
1042     ld->_adr_type = adr_type;
1043 #endif
1044     ld->set_req(MemNode::Address, addp);
1045     ld->set_req(0, ctl);
1046     ld->set_req(MemNode::Memory, mem);
1047     // load depends on the tests that validate the arraycopy
1048     ld->_control_dependency = UnknownControl;
1049     return ld;
1050   }
1051   return NULL;
1052 }
1053 
1054 
1055 //---------------------------can_see_stored_value------------------------------
1056 // This routine exists to make sure this set of tests is done the same
1057 // everywhere.  We need to make a coordinated change: first LoadNode::Ideal
1058 // will change the graph shape in a way which makes memory alive twice at the
1059 // same time (uses the Oracle model of aliasing), then some
1060 // LoadXNode::Identity will fold things back to the equivalence-class model
1061 // of aliasing.
1062 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1063   Node* ld_adr = in(MemNode::Address);
1064   intptr_t ld_off = 0;
1065   Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1066   Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1067   const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1068   Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1069   // This is more general than load from boxing objects.
1070   if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1071     uint alias_idx = atp->index();
1072     Node* result = NULL;
1073     Node* current = st;
1074     // Skip through chains of MemBarNodes checking the MergeMems for
1075     // new states for the slice of this load.  Stop once any other
1076     // kind of node is encountered.  Loads from final memory can skip
1077     // through any kind of MemBar but normal loads shouldn't skip
1078     // through MemBarAcquire since the could allow them to move out of
1079     // a synchronized region. It is not safe to step over MemBarCPUOrder,
1080     // because alias info above them may be inaccurate (e.g., due to
1081     // mixed/mismatched unsafe accesses).
1082     bool is_final_mem = !atp->is_rewritable();
1083     while (current->is_Proj()) {
1084       int opc = current->in(0)->Opcode();
1085       if ((is_final_mem && (opc == Op_MemBarAcquire ||
1086                             opc == Op_MemBarAcquireLock ||
1087                             opc == Op_LoadFence)) ||
1088           opc == Op_MemBarRelease ||
1089           opc == Op_StoreFence ||
1090           opc == Op_MemBarReleaseLock ||
1091           opc == Op_MemBarStoreStore ||
1092           opc == Op_StoreStoreFence) {
1093         Node* mem = current->in(0)->in(TypeFunc::Memory);
1094         if (mem->is_MergeMem()) {
1095           MergeMemNode* merge = mem->as_MergeMem();
1096           Node* new_st = merge->memory_at(alias_idx);
1097           if (new_st == merge->base_memory()) {
1098             // Keep searching
1099             current = new_st;
1100             continue;
1101           }
1102           // Save the new memory state for the slice and fall through
1103           // to exit.
1104           result = new_st;
1105         }
1106       }
1107       break;
1108     }
1109     if (result != NULL) {
1110       st = result;
1111     }
1112   }
1113 
1114   // Loop around twice in the case Load -> Initialize -> Store.
1115   // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1116   for (int trip = 0; trip <= 1; trip++) {
1117 
1118     if (st->is_Store()) {
1119       Node* st_adr = st->in(MemNode::Address);
1120       if (st_adr != ld_adr) {
1121         // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1122         intptr_t st_off = 0;
1123         Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1124         if (ld_base == NULL)                                   return NULL;
1125         if (st_base == NULL)                                   return NULL;
1126         if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL;
1127         if (ld_off != st_off)                                  return NULL;
1128         if (ld_off == Type::OffsetBot)                         return NULL;
1129         // Same base, same offset.
1130         // Possible improvement for arrays: check index value instead of absolute offset.
1131 
1132         // At this point we have proven something like this setup:
1133         //   B = << base >>
1134         //   L =  LoadQ(AddP(Check/CastPP(B), #Off))
1135         //   S = StoreQ(AddP(             B , #Off), V)
1136         // (Actually, we haven't yet proven the Q's are the same.)
1137         // In other words, we are loading from a casted version of
1138         // the same pointer-and-offset that we stored to.
1139         // Casted version may carry a dependency and it is respected.
1140         // Thus, we are able to replace L by V.
1141       }
1142       // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1143       if (store_Opcode() != st->Opcode()) {
1144         return NULL;
1145       }
1146       // LoadVector/StoreVector needs additional check to ensure the types match.
1147       if (st->is_StoreVector()) {
1148         const TypeVect*  in_vt = st->as_StoreVector()->vect_type();
1149         const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1150         if (in_vt != out_vt) {
1151           return NULL;
1152         }
1153       }
1154       return st->in(MemNode::ValueIn);
1155     }
1156 
1157     // A load from a freshly-created object always returns zero.
1158     // (This can happen after LoadNode::Ideal resets the load's memory input
1159     // to find_captured_store, which returned InitializeNode::zero_memory.)
1160     if (st->is_Proj() && st->in(0)->is_Allocate() &&
1161         (st->in(0) == ld_alloc) &&
1162         (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1163       // return a zero value for the load's basic type
1164       // (This is one of the few places where a generic PhaseTransform
1165       // can create new nodes.  Think of it as lazily manifesting
1166       // virtually pre-existing constants.)
1167       assert(memory_type() != T_PRIMITIVE_OBJECT, "should not be used for inline types");
1168       Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1169       if (default_value != NULL) {
1170         return default_value;
1171       }
1172       assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null");
1173       if (memory_type() != T_VOID) {
1174         if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == NULL) {
1175           // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1176           // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1177           // by the ArrayCopyNode.
1178           return phase->zerocon(memory_type());
1179         }
1180       } else {
1181         // TODO: materialize all-zero vector constant
1182         assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1183       }
1184     }
1185 
1186     // A load from an initialization barrier can match a captured store.
1187     if (st->is_Proj() && st->in(0)->is_Initialize()) {
1188       InitializeNode* init = st->in(0)->as_Initialize();
1189       AllocateNode* alloc = init->allocation();
1190       if ((alloc != NULL) && (alloc == ld_alloc)) {
1191         // examine a captured store value
1192         st = init->find_captured_store(ld_off, memory_size(), phase);
1193         if (st != NULL) {
1194           continue;             // take one more trip around
1195         }
1196       }
1197     }
1198 
1199     // Load boxed value from result of valueOf() call is input parameter.
1200     if (this->is_Load() && ld_adr->is_AddP() &&
1201         (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1202       intptr_t ignore = 0;
1203       Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1204       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1205       base = bs->step_over_gc_barrier(base);
1206       if (base != NULL && base->is_Proj() &&
1207           base->as_Proj()->_con == TypeFunc::Parms &&
1208           base->in(0)->is_CallStaticJava() &&
1209           base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1210         return base->in(0)->in(TypeFunc::Parms);
1211       }
1212     }
1213 
1214     break;
1215   }
1216 
1217   return NULL;
1218 }
1219 
1220 //----------------------is_instance_field_load_with_local_phi------------------
1221 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1222   if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1223       in(Address)->is_AddP() ) {
1224     const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1225     // Only instances and boxed values.
1226     if( t_oop != NULL &&
1227         (t_oop->is_ptr_to_boxed_value() ||
1228          t_oop->is_known_instance_field()) &&
1229         t_oop->offset() != Type::OffsetBot &&
1230         t_oop->offset() != Type::OffsetTop) {
1231       return true;
1232     }
1233   }
1234   return false;
1235 }
1236 
1237 //------------------------------Identity---------------------------------------
1238 // Loads are identity if previous store is to same address
1239 Node* LoadNode::Identity(PhaseGVN* phase) {
1240   // Loading from an InlineTypePtr? The InlineTypePtr has the values of
1241   // all fields as input. Look for the field with matching offset.
1242   Node* addr = in(Address);
1243   intptr_t offset;
1244   Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1245   if (base != NULL && base->is_InlineTypePtr() && offset > oopDesc::klass_offset_in_bytes()) {
1246     Node* value = base->as_InlineTypePtr()->field_value_by_offset((int)offset, true);
1247     if (value->is_InlineType()) {
1248       // Non-flattened inline type field
1249       InlineTypeNode* vt = value->as_InlineType();
1250       if (vt->is_allocated(phase)) {
1251         value = vt->get_oop();
1252       } else {
1253         // Not yet allocated, bail out
1254         value = NULL;
1255       }
1256     }
1257     if (value != NULL) {
1258       if (Opcode() == Op_LoadN) {
1259         // Encode oop value if we are loading a narrow oop
1260         assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1261         value = phase->transform(new EncodePNode(value, bottom_type()));
1262       }
1263       return value;
1264     }
1265   }
1266 
1267   // If the previous store-maker is the right kind of Store, and the store is
1268   // to the same address, then we are equal to the value stored.
1269   Node* mem = in(Memory);
1270   Node* value = can_see_stored_value(mem, phase);
1271   if( value ) {
1272     // byte, short & char stores truncate naturally.
1273     // A load has to load the truncated value which requires
1274     // some sort of masking operation and that requires an
1275     // Ideal call instead of an Identity call.
1276     if (memory_size() < BytesPerInt) {
1277       // If the input to the store does not fit with the load's result type,
1278       // it must be truncated via an Ideal call.
1279       if (!phase->type(value)->higher_equal(phase->type(this)))
1280         return this;
1281     }
1282     // (This works even when value is a Con, but LoadNode::Value
1283     // usually runs first, producing the singleton type of the Con.)
1284     return value;
1285   }
1286 
1287   // Search for an existing data phi which was generated before for the same
1288   // instance's field to avoid infinite generation of phis in a loop.
1289   Node *region = mem->in(0);
1290   if (is_instance_field_load_with_local_phi(region)) {
1291     const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1292     int this_index  = phase->C->get_alias_index(addr_t);
1293     int this_offset = addr_t->offset();
1294     int this_iid    = addr_t->instance_id();
1295     if (!addr_t->is_known_instance() &&
1296          addr_t->is_ptr_to_boxed_value()) {
1297       // Use _idx of address base (could be Phi node) for boxed values.
1298       intptr_t   ignore = 0;
1299       Node*      base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1300       if (base == NULL) {
1301         return this;
1302       }
1303       this_iid = base->_idx;
1304     }
1305     const Type* this_type = bottom_type();
1306     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1307       Node* phi = region->fast_out(i);
1308       if (phi->is_Phi() && phi != mem &&
1309           phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1310         return phi;
1311       }
1312     }
1313   }
1314 
1315   return this;
1316 }
1317 
1318 // Construct an equivalent unsigned load.
1319 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1320   BasicType bt = T_ILLEGAL;
1321   const Type* rt = NULL;
1322   switch (Opcode()) {
1323     case Op_LoadUB: return this;
1324     case Op_LoadUS: return this;
1325     case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1326     case Op_LoadS: bt = T_CHAR;    rt = TypeInt::CHAR;  break;
1327     default:
1328       assert(false, "no unsigned variant: %s", Name());
1329       return NULL;
1330   }
1331   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1332                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1333                         is_unaligned_access(), is_mismatched_access());
1334 }
1335 
1336 // Construct an equivalent signed load.
1337 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1338   BasicType bt = T_ILLEGAL;
1339   const Type* rt = NULL;
1340   switch (Opcode()) {
1341     case Op_LoadUB: bt = T_BYTE;  rt = TypeInt::BYTE;  break;
1342     case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1343     case Op_LoadB: // fall through
1344     case Op_LoadS: // fall through
1345     case Op_LoadI: // fall through
1346     case Op_LoadL: return this;
1347     default:
1348       assert(false, "no signed variant: %s", Name());
1349       return NULL;
1350   }
1351   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1352                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1353                         is_unaligned_access(), is_mismatched_access());
1354 }
1355 
1356 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1357   BasicType bt = rt->basic_type();
1358   switch (Opcode()) {
1359     case Op_LoadI: return (bt == T_FLOAT);
1360     case Op_LoadL: return (bt == T_DOUBLE);
1361     case Op_LoadF: return (bt == T_INT);
1362     case Op_LoadD: return (bt == T_LONG);
1363 
1364     default: return false;
1365   }
1366 }
1367 
1368 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1369   BasicType bt = rt->basic_type();
1370   assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1371   bool is_mismatched = is_mismatched_access();
1372   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1373   if (raw_type == NULL) {
1374     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1375   }
1376   return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1377                         raw_adr_type(), rt, bt, _mo, _control_dependency,
1378                         is_unaligned_access(), is_mismatched);
1379 }
1380 
1381 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1382   BasicType bt = vt->basic_type();
1383   switch (Opcode()) {
1384     case Op_StoreI: return (bt == T_FLOAT);
1385     case Op_StoreL: return (bt == T_DOUBLE);
1386     case Op_StoreF: return (bt == T_INT);
1387     case Op_StoreD: return (bt == T_LONG);
1388 
1389     default: return false;
1390   }
1391 }
1392 
1393 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1394   BasicType bt = vt->basic_type();
1395   assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1396   StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), raw_adr_type(), val, bt, _mo);
1397 
1398   bool is_mismatched = is_mismatched_access();
1399   const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1400   if (raw_type == NULL) {
1401     is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1402   }
1403   if (is_mismatched) {
1404     st->set_mismatched_access();
1405   }
1406   return st;
1407 }
1408 
1409 // We're loading from an object which has autobox behaviour.
1410 // If this object is result of a valueOf call we'll have a phi
1411 // merging a newly allocated object and a load from the cache.
1412 // We want to replace this load with the original incoming
1413 // argument to the valueOf call.
1414 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1415   assert(igvn->C->eliminate_boxing(), "sanity");
1416   intptr_t ignore = 0;
1417   Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1418   if ((base == NULL) || base->is_Phi()) {
1419     // Push the loads from the phi that comes from valueOf up
1420     // through it to allow elimination of the loads and the recovery
1421     // of the original value. It is done in split_through_phi().
1422     return NULL;
1423   } else if (base->is_Load() ||
1424              (base->is_DecodeN() && base->in(1)->is_Load())) {
1425     // Eliminate the load of boxed value for integer types from the cache
1426     // array by deriving the value from the index into the array.
1427     // Capture the offset of the load and then reverse the computation.
1428 
1429     // Get LoadN node which loads a boxing object from 'cache' array.
1430     if (base->is_DecodeN()) {
1431       base = base->in(1);
1432     }
1433     if (!base->in(Address)->is_AddP()) {
1434       return NULL; // Complex address
1435     }
1436     AddPNode* address = base->in(Address)->as_AddP();
1437     Node* cache_base = address->in(AddPNode::Base);
1438     if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1439       // Get ConP node which is static 'cache' field.
1440       cache_base = cache_base->in(1);
1441     }
1442     if ((cache_base != NULL) && cache_base->is_Con()) {
1443       const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1444       if ((base_type != NULL) && base_type->is_autobox_cache()) {
1445         Node* elements[4];
1446         int shift = exact_log2(type2aelembytes(T_OBJECT));
1447         int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1448         if (count > 0 && elements[0]->is_Con() &&
1449             (count == 1 ||
1450              (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1451                             elements[1]->in(2) == igvn->intcon(shift)))) {
1452           ciObjArray* array = base_type->const_oop()->as_obj_array();
1453           // Fetch the box object cache[0] at the base of the array and get its value
1454           ciInstance* box = array->obj_at(0)->as_instance();
1455           ciInstanceKlass* ik = box->klass()->as_instance_klass();
1456           assert(ik->is_box_klass(), "sanity");
1457           assert(ik->nof_nonstatic_fields() == 1, "change following code");
1458           if (ik->nof_nonstatic_fields() == 1) {
1459             // This should be true nonstatic_field_at requires calling
1460             // nof_nonstatic_fields so check it anyway
1461             ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1462             BasicType bt = c.basic_type();
1463             // Only integer types have boxing cache.
1464             assert(bt == T_BOOLEAN || bt == T_CHAR  ||
1465                    bt == T_BYTE    || bt == T_SHORT ||
1466                    bt == T_INT     || bt == T_LONG, "wrong type = %s", type2name(bt));
1467             jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1468             if (cache_low != (int)cache_low) {
1469               return NULL; // should not happen since cache is array indexed by value
1470             }
1471             jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1472             if (offset != (int)offset) {
1473               return NULL; // should not happen since cache is array indexed by value
1474             }
1475            // Add up all the offsets making of the address of the load
1476             Node* result = elements[0];
1477             for (int i = 1; i < count; i++) {
1478               result = igvn->transform(new AddXNode(result, elements[i]));
1479             }
1480             // Remove the constant offset from the address and then
1481             result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1482             // remove the scaling of the offset to recover the original index.
1483             if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1484               // Peel the shift off directly but wrap it in a dummy node
1485               // since Ideal can't return existing nodes
1486               igvn->_worklist.push(result); // remove dead node later
1487               result = new RShiftXNode(result->in(1), igvn->intcon(0));
1488             } else if (result->is_Add() && result->in(2)->is_Con() &&
1489                        result->in(1)->Opcode() == Op_LShiftX &&
1490                        result->in(1)->in(2) == igvn->intcon(shift)) {
1491               // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1492               // but for boxing cache access we know that X<<Z will not overflow
1493               // (there is range check) so we do this optimizatrion by hand here.
1494               igvn->_worklist.push(result); // remove dead node later
1495               Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1496               result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1497             } else {
1498               result = new RShiftXNode(result, igvn->intcon(shift));
1499             }
1500 #ifdef _LP64
1501             if (bt != T_LONG) {
1502               result = new ConvL2INode(igvn->transform(result));
1503             }
1504 #else
1505             if (bt == T_LONG) {
1506               result = new ConvI2LNode(igvn->transform(result));
1507             }
1508 #endif
1509             // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1510             // Need to preserve unboxing load type if it is unsigned.
1511             switch(this->Opcode()) {
1512               case Op_LoadUB:
1513                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1514                 break;
1515               case Op_LoadUS:
1516                 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1517                 break;
1518             }
1519             return result;
1520           }
1521         }
1522       }
1523     }
1524   }
1525   return NULL;
1526 }
1527 
1528 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1529   Node* region = phi->in(0);
1530   if (region == NULL) {
1531     return false; // Wait stable graph
1532   }
1533   uint cnt = phi->req();
1534   for (uint i = 1; i < cnt; i++) {
1535     Node* rc = region->in(i);
1536     if (rc == NULL || phase->type(rc) == Type::TOP)
1537       return false; // Wait stable graph
1538     Node* in = phi->in(i);
1539     if (in == NULL || phase->type(in) == Type::TOP)
1540       return false; // Wait stable graph
1541   }
1542   return true;
1543 }
1544 //------------------------------split_through_phi------------------------------
1545 // Split instance or boxed field load through Phi.
1546 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1547   Node* mem     = in(Memory);
1548   Node* address = in(Address);
1549   const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1550 
1551   assert((t_oop != NULL) &&
1552          (t_oop->is_known_instance_field() ||
1553           t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1554 
1555   Compile* C = phase->C;
1556   intptr_t ignore = 0;
1557   Node*    base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1558   bool base_is_phi = (base != NULL) && base->is_Phi();
1559   bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1560                            (base != NULL) && (base == address->in(AddPNode::Base)) &&
1561                            phase->type(base)->higher_equal(TypePtr::NOTNULL);
1562 
1563   if (!((mem->is_Phi() || base_is_phi) &&
1564         (load_boxed_values || t_oop->is_known_instance_field()))) {
1565     return NULL; // memory is not Phi
1566   }
1567 
1568   if (mem->is_Phi()) {
1569     if (!stable_phi(mem->as_Phi(), phase)) {
1570       return NULL; // Wait stable graph
1571     }
1572     uint cnt = mem->req();
1573     // Check for loop invariant memory.
1574     if (cnt == 3) {
1575       for (uint i = 1; i < cnt; i++) {
1576         Node* in = mem->in(i);
1577         Node*  m = optimize_memory_chain(in, t_oop, this, phase);
1578         if (m == mem) {
1579           if (i == 1) {
1580             // if the first edge was a loop, check second edge too.
1581             // If both are replaceable - we are in an infinite loop
1582             Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1583             if (n == mem) {
1584               break;
1585             }
1586           }
1587           set_req(Memory, mem->in(cnt - i));
1588           return this; // made change
1589         }
1590       }
1591     }
1592   }
1593   if (base_is_phi) {
1594     if (!stable_phi(base->as_Phi(), phase)) {
1595       return NULL; // Wait stable graph
1596     }
1597     uint cnt = base->req();
1598     // Check for loop invariant memory.
1599     if (cnt == 3) {
1600       for (uint i = 1; i < cnt; i++) {
1601         if (base->in(i) == base) {
1602           return NULL; // Wait stable graph
1603         }
1604       }
1605     }
1606   }
1607 
1608   // Split through Phi (see original code in loopopts.cpp).
1609   assert(C->have_alias_type(t_oop), "instance should have alias type");
1610 
1611   // Do nothing here if Identity will find a value
1612   // (to avoid infinite chain of value phis generation).
1613   if (this != Identity(phase)) {
1614     return NULL;
1615   }
1616 
1617   // Select Region to split through.
1618   Node* region;
1619   if (!base_is_phi) {
1620     assert(mem->is_Phi(), "sanity");
1621     region = mem->in(0);
1622     // Skip if the region dominates some control edge of the address.
1623     if (!MemNode::all_controls_dominate(address, region))
1624       return NULL;
1625   } else if (!mem->is_Phi()) {
1626     assert(base_is_phi, "sanity");
1627     region = base->in(0);
1628     // Skip if the region dominates some control edge of the memory.
1629     if (!MemNode::all_controls_dominate(mem, region))
1630       return NULL;
1631   } else if (base->in(0) != mem->in(0)) {
1632     assert(base_is_phi && mem->is_Phi(), "sanity");
1633     if (MemNode::all_controls_dominate(mem, base->in(0))) {
1634       region = base->in(0);
1635     } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1636       region = mem->in(0);
1637     } else {
1638       return NULL; // complex graph
1639     }
1640   } else {
1641     assert(base->in(0) == mem->in(0), "sanity");
1642     region = mem->in(0);
1643   }
1644 
1645   const Type* this_type = this->bottom_type();
1646   int this_index  = C->get_alias_index(t_oop);
1647   int this_offset = t_oop->offset();
1648   int this_iid    = t_oop->instance_id();
1649   if (!t_oop->is_known_instance() && load_boxed_values) {
1650     // Use _idx of address base for boxed values.
1651     this_iid = base->_idx;
1652   }
1653   PhaseIterGVN* igvn = phase->is_IterGVN();
1654   Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1655   for (uint i = 1; i < region->req(); i++) {
1656     Node* x;
1657     Node* the_clone = NULL;
1658     Node* in = region->in(i);
1659     if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1660         in != NULL && in->is_OuterStripMinedLoop()) {
1661       // No node should go in the outer strip mined loop
1662       in = in->in(LoopNode::EntryControl);
1663     }
1664     if (in == NULL || in == C->top()) {
1665       x = C->top();      // Dead path?  Use a dead data op
1666     } else {
1667       x = this->clone();        // Else clone up the data op
1668       the_clone = x;            // Remember for possible deletion.
1669       // Alter data node to use pre-phi inputs
1670       if (this->in(0) == region) {
1671         x->set_req(0, in);
1672       } else {
1673         x->set_req(0, NULL);
1674       }
1675       if (mem->is_Phi() && (mem->in(0) == region)) {
1676         x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1677       }
1678       if (address->is_Phi() && address->in(0) == region) {
1679         x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1680       }
1681       if (base_is_phi && (base->in(0) == region)) {
1682         Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1683         Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1684         x->set_req(Address, adr_x);
1685       }
1686     }
1687     // Check for a 'win' on some paths
1688     const Type *t = x->Value(igvn);
1689 
1690     bool singleton = t->singleton();
1691 
1692     // See comments in PhaseIdealLoop::split_thru_phi().
1693     if (singleton && t == Type::TOP) {
1694       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1695     }
1696 
1697     if (singleton) {
1698       x = igvn->makecon(t);
1699     } else {
1700       // We now call Identity to try to simplify the cloned node.
1701       // Note that some Identity methods call phase->type(this).
1702       // Make sure that the type array is big enough for
1703       // our new node, even though we may throw the node away.
1704       // (This tweaking with igvn only works because x is a new node.)
1705       igvn->set_type(x, t);
1706       // If x is a TypeNode, capture any more-precise type permanently into Node
1707       // otherwise it will be not updated during igvn->transform since
1708       // igvn->type(x) is set to x->Value() already.
1709       x->raise_bottom_type(t);
1710       Node* y = x->Identity(igvn);
1711       if (y != x) {
1712         x = y;
1713       } else {
1714         y = igvn->hash_find_insert(x);
1715         if (y) {
1716           x = y;
1717         } else {
1718           // Else x is a new node we are keeping
1719           // We do not need register_new_node_with_optimizer
1720           // because set_type has already been called.
1721           igvn->_worklist.push(x);
1722         }
1723       }
1724     }
1725     if (x != the_clone && the_clone != NULL) {
1726       igvn->remove_dead_node(the_clone);
1727     }
1728     phi->set_req(i, x);
1729   }
1730   // Record Phi
1731   igvn->register_new_node_with_optimizer(phi);
1732   return phi;
1733 }
1734 
1735 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1736   if (Opcode() == Op_LoadX) {
1737     Node* address = in(MemNode::Address);
1738     AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1739     Node* mem = in(MemNode::Memory);
1740     if (alloc != NULL && mem->is_Proj() &&
1741         mem->in(0) != NULL &&
1742         mem->in(0) == alloc->initialization() &&
1743         alloc->initialization()->proj_out_or_null(0) != NULL) {
1744       return alloc;
1745     }
1746   }
1747   return NULL;
1748 }
1749 
1750 
1751 //------------------------------Ideal------------------------------------------
1752 // If the load is from Field memory and the pointer is non-null, it might be possible to
1753 // zero out the control input.
1754 // If the offset is constant and the base is an object allocation,
1755 // try to hook me up to the exact initializing store.
1756 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1757   Node* p = MemNode::Ideal_common(phase, can_reshape);
1758   if (p)  return (p == NodeSentinel) ? NULL : p;
1759 
1760   Node* ctrl    = in(MemNode::Control);
1761   Node* address = in(MemNode::Address);
1762   bool progress = false;
1763 
1764   bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1765          phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1766 
1767   // Skip up past a SafePoint control.  Cannot do this for Stores because
1768   // pointer stores & cardmarks must stay on the same side of a SafePoint.
1769   if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1770       phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw  &&
1771       !addr_mark &&
1772       (depends_only_on_test() || has_unknown_control_dependency())) {
1773     ctrl = ctrl->in(0);
1774     set_req(MemNode::Control,ctrl);
1775     progress = true;
1776   }
1777 
1778   intptr_t ignore = 0;
1779   Node*    base   = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1780   if (base != NULL
1781       && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1782     // Check for useless control edge in some common special cases
1783     if (in(MemNode::Control) != NULL
1784         && can_remove_control()
1785         && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1786         && all_controls_dominate(base, phase->C->start())) {
1787       // A method-invariant, non-null address (constant or 'this' argument).
1788       set_req(MemNode::Control, NULL);
1789       progress = true;
1790     }
1791   }
1792 
1793   Node* mem = in(MemNode::Memory);
1794   const TypePtr *addr_t = phase->type(address)->isa_ptr();
1795 
1796   if (can_reshape && (addr_t != NULL)) {
1797     // try to optimize our memory input
1798     Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1799     if (opt_mem != mem) {
1800       set_req_X(MemNode::Memory, opt_mem, phase);
1801       if (phase->type( opt_mem ) == Type::TOP) return NULL;
1802       return this;
1803     }
1804     const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1805     if ((t_oop != NULL) &&
1806         (t_oop->is_known_instance_field() ||
1807          t_oop->is_ptr_to_boxed_value())) {
1808       PhaseIterGVN *igvn = phase->is_IterGVN();
1809       assert(igvn != NULL, "must be PhaseIterGVN when can_reshape is true");
1810       if (igvn->_worklist.member(opt_mem)) {
1811         // Delay this transformation until memory Phi is processed.
1812         igvn->_worklist.push(this);
1813         return NULL;
1814       }
1815       // Split instance field load through Phi.
1816       Node* result = split_through_phi(phase);
1817       if (result != NULL) return result;
1818 
1819       if (t_oop->is_ptr_to_boxed_value()) {
1820         Node* result = eliminate_autobox(igvn);
1821         if (result != NULL) return result;
1822       }
1823     }
1824   }
1825 
1826   // Is there a dominating load that loads the same value?  Leave
1827   // anything that is not a load of a field/array element (like
1828   // barriers etc.) alone
1829   if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1830     for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1831       Node *use = mem->fast_out(i);
1832       if (use != this &&
1833           use->Opcode() == Opcode() &&
1834           use->in(0) != NULL &&
1835           use->in(0) != in(0) &&
1836           use->in(Address) == in(Address)) {
1837         Node* ctl = in(0);
1838         for (int i = 0; i < 10 && ctl != NULL; i++) {
1839           ctl = IfNode::up_one_dom(ctl);
1840           if (ctl == use->in(0)) {
1841             set_req(0, use->in(0));
1842             return this;
1843           }
1844         }
1845       }
1846     }
1847   }
1848 
1849   // Check for prior store with a different base or offset; make Load
1850   // independent.  Skip through any number of them.  Bail out if the stores
1851   // are in an endless dead cycle and report no progress.  This is a key
1852   // transform for Reflection.  However, if after skipping through the Stores
1853   // we can't then fold up against a prior store do NOT do the transform as
1854   // this amounts to using the 'Oracle' model of aliasing.  It leaves the same
1855   // array memory alive twice: once for the hoisted Load and again after the
1856   // bypassed Store.  This situation only works if EVERYBODY who does
1857   // anti-dependence work knows how to bypass.  I.e. we need all
1858   // anti-dependence checks to ask the same Oracle.  Right now, that Oracle is
1859   // the alias index stuff.  So instead, peek through Stores and IFF we can
1860   // fold up, do so.
1861   Node* prev_mem = find_previous_store(phase);
1862   if (prev_mem != NULL) {
1863     Node* value = can_see_arraycopy_value(prev_mem, phase);
1864     if (value != NULL) {
1865       return value;
1866     }
1867   }
1868   // Steps (a), (b):  Walk past independent stores to find an exact match.
1869   if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1870     // (c) See if we can fold up on the spot, but don't fold up here.
1871     // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1872     // just return a prior value, which is done by Identity calls.
1873     if (can_see_stored_value(prev_mem, phase)) {
1874       // Make ready for step (d):
1875       set_req_X(MemNode::Memory, prev_mem, phase);
1876       return this;
1877     }
1878   }
1879 
1880   return progress ? this : NULL;
1881 }
1882 
1883 // Helper to recognize certain Klass fields which are invariant across
1884 // some group of array types (e.g., int[] or all T[] where T < Object).
1885 const Type*
1886 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1887                                  ciKlass* klass) const {
1888   if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1889     // The field is Klass::_modifier_flags.  Return its (constant) value.
1890     // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1891     assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1892     return TypeInt::make(klass->modifier_flags());
1893   }
1894   if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1895     // The field is Klass::_access_flags.  Return its (constant) value.
1896     // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1897     assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1898     return TypeInt::make(klass->access_flags());
1899   }
1900   if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1901     // The field is Klass::_layout_helper.  Return its constant value if known.
1902     assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1903     return TypeInt::make(klass->layout_helper());
1904   }
1905 
1906   // No match.
1907   return NULL;
1908 }
1909 
1910 //------------------------------Value-----------------------------------------
1911 const Type* LoadNode::Value(PhaseGVN* phase) const {
1912   // Either input is TOP ==> the result is TOP
1913   Node* mem = in(MemNode::Memory);
1914   const Type *t1 = phase->type(mem);
1915   if (t1 == Type::TOP)  return Type::TOP;
1916   Node* adr = in(MemNode::Address);
1917   const TypePtr* tp = phase->type(adr)->isa_ptr();
1918   if (tp == NULL || tp->empty())  return Type::TOP;
1919   int off = tp->offset();
1920   assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1921   Compile* C = phase->C;
1922 
1923   // Try to guess loaded type from pointer type
1924   if (tp->isa_aryptr()) {
1925     const TypeAryPtr* ary = tp->is_aryptr();
1926     const Type* t = ary->elem();
1927 
1928     // Determine whether the reference is beyond the header or not, by comparing
1929     // the offset against the offset of the start of the array's data.
1930     // Different array types begin at slightly different offsets (12 vs. 16).
1931     // We choose T_BYTE as an example base type that is least restrictive
1932     // as to alignment, which will therefore produce the smallest
1933     // possible base offset.
1934     const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1935     const bool off_beyond_header = (off >= min_base_off);
1936 
1937     // Try to constant-fold a stable array element.
1938     if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1939       // Make sure the reference is not into the header and the offset is constant
1940       ciObject* aobj = ary->const_oop();
1941       if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1942         int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1943         const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1944                                                                       stable_dimension,
1945                                                                       memory_type(), is_unsigned());
1946         if (con_type != NULL) {
1947           return con_type;
1948         }
1949       }
1950     }
1951 
1952     // Don't do this for integer types. There is only potential profit if
1953     // the element type t is lower than _type; that is, for int types, if _type is
1954     // more restrictive than t.  This only happens here if one is short and the other
1955     // char (both 16 bits), and in those cases we've made an intentional decision
1956     // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1957     // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1958     //
1959     // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1960     // where the _gvn.type of the AddP is wider than 8.  This occurs when an earlier
1961     // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1962     // subsumed by p1.  If p1 is on the worklist but has not yet been re-transformed,
1963     // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1964     // In fact, that could have been the original type of p1, and p1 could have
1965     // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1966     // expression (LShiftL quux 3) independently optimized to the constant 8.
1967     if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1968         && (_type->isa_vect() == NULL)
1969         && t->isa_inlinetype() == NULL
1970         && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1971       // t might actually be lower than _type, if _type is a unique
1972       // concrete subclass of abstract class t.
1973       if (off_beyond_header || off == Type::OffsetBot) {  // is the offset beyond the header?
1974         const Type* jt = t->join_speculative(_type);
1975         // In any case, do not allow the join, per se, to empty out the type.
1976         if (jt->empty() && !t->empty()) {
1977           // This can happen if a interface-typed array narrows to a class type.
1978           jt = _type;
1979         }
1980 #ifdef ASSERT
1981         if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1982           // The pointers in the autobox arrays are always non-null
1983           Node* base = adr->in(AddPNode::Base);
1984           if ((base != NULL) && base->is_DecodeN()) {
1985             // Get LoadN node which loads IntegerCache.cache field
1986             base = base->in(1);
1987           }
1988           if ((base != NULL) && base->is_Con()) {
1989             const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1990             if ((base_type != NULL) && base_type->is_autobox_cache()) {
1991               // It could be narrow oop
1992               assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1993             }
1994           }
1995         }
1996 #endif
1997         return jt;
1998       }
1999     }
2000   } else if (tp->base() == Type::InstPtr) {
2001     assert( off != Type::OffsetBot ||
2002             // arrays can be cast to Objects
2003             tp->is_oopptr()->klass()->is_java_lang_Object() ||
2004             tp->is_oopptr()->klass() == ciEnv::current()->Class_klass() ||
2005             // unsafe field access may not have a constant offset
2006             C->has_unsafe_access(),
2007             "Field accesses must be precise" );
2008     // For oop loads, we expect the _type to be precise.
2009 
2010     const TypeInstPtr* tinst = tp->is_instptr();
2011     BasicType bt = memory_type();
2012 
2013     // Optimize loads from constant fields.
2014     ciObject* const_oop = tinst->const_oop();
2015     if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
2016       ciType* mirror_type = const_oop->as_instance()->java_mirror_type();
2017       if (mirror_type != NULL) {
2018         const Type* const_oop = NULL;
2019         ciInlineKlass* vk = mirror_type->is_inlinetype() ? mirror_type->as_inline_klass() : NULL;
2020         // Fold default value loads
2021         if (vk != NULL && off == vk->default_value_offset()) {
2022           const_oop = TypeInstPtr::make(vk->default_instance());
2023         }
2024         // Fold class mirror loads
2025         if (off == java_lang_Class::primary_mirror_offset()) {
2026           const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->ref_instance());
2027         } else if (off == java_lang_Class::secondary_mirror_offset()) {
2028           const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->val_instance());
2029         }
2030         if (const_oop != NULL) {
2031           return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
2032         }
2033       }
2034       const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2035       if (con_type != NULL) {
2036         return con_type;
2037       }
2038     }
2039   } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2040     assert( off != Type::OffsetBot ||
2041             // arrays can be cast to Objects
2042             tp->is_klassptr()->klass() == NULL ||
2043             tp->is_klassptr()->klass()->is_java_lang_Object() ||
2044             // also allow array-loading from the primary supertype
2045             // array during subtype checks
2046             Opcode() == Op_LoadKlass,
2047             "Field accesses must be precise" );
2048     // For klass/static loads, we expect the _type to be precise
2049   } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
2050     if (adr->is_Load() && off == 0) {
2051       /* With mirrors being an indirect in the Klass*
2052        * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2053        * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2054        *
2055        * So check the type and klass of the node before the LoadP.
2056        */
2057       Node* adr2 = adr->in(MemNode::Address);
2058       const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2059       if (tkls != NULL) {
2060         ciKlass* klass = tkls->klass();
2061         if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2062           assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2063           assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2064           return TypeInstPtr::make(klass->java_mirror());
2065         }
2066       }
2067     } else {
2068       // Check for a load of the default value offset from the InlineKlassFixedBlock:
2069       // LoadI(LoadP(inline_klass, adr_inlineklass_fixed_block_offset), default_value_offset_offset)
2070       intptr_t offset = 0;
2071       Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2072       if (base != NULL && base->is_Load() && offset == in_bytes(InlineKlass::default_value_offset_offset())) {
2073         const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
2074         if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->isa_inlinetype() &&
2075             tkls->offset() == in_bytes(InstanceKlass::adr_inlineklass_fixed_block_offset())) {
2076           assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
2077           assert(Opcode() == Op_LoadI, "must load an int from fixed block");
2078           return TypeInt::make(tkls->klass()->as_inline_klass()->default_value_offset());
2079         }
2080       }
2081     }
2082   }
2083 
2084   const TypeKlassPtr *tkls = tp->isa_klassptr();
2085   if (tkls != NULL && !StressReflectiveCode) {
2086     ciKlass* klass = tkls->klass();
2087     if (tkls->is_loaded() && tkls->klass_is_exact()) {
2088       // We are loading a field from a Klass metaobject whose identity
2089       // is known at compile time (the type is "exact" or "precise").
2090       // Check for fields we know are maintained as constants by the VM.
2091       if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2092         // The field is Klass::_super_check_offset.  Return its (constant) value.
2093         // (Folds up type checking code.)
2094         assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2095         return TypeInt::make(klass->super_check_offset());
2096       }
2097       // Compute index into primary_supers array
2098       juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2099       // Check for overflowing; use unsigned compare to handle the negative case.
2100       if( depth < ciKlass::primary_super_limit() ) {
2101         // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2102         // (Folds up type checking code.)
2103         assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2104         ciKlass *ss = klass->super_of_depth(depth);
2105         return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2106       }
2107       const Type* aift = load_array_final_field(tkls, klass);
2108       if (aift != NULL)  return aift;
2109     }
2110 
2111     // We can still check if we are loading from the primary_supers array at a
2112     // shallow enough depth.  Even though the klass is not exact, entries less
2113     // than or equal to its super depth are correct.
2114     if (tkls->is_loaded()) {
2115       ciType *inner = klass;
2116       while( inner->is_obj_array_klass() )
2117         inner = inner->as_obj_array_klass()->base_element_type();
2118       if( inner->is_instance_klass() &&
2119           !inner->as_instance_klass()->flags().is_interface() ) {
2120         // Compute index into primary_supers array
2121         juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2122         // Check for overflowing; use unsigned compare to handle the negative case.
2123         if( depth < ciKlass::primary_super_limit() &&
2124             depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
2125           // The field is an element of Klass::_primary_supers.  Return its (constant) value.
2126           // (Folds up type checking code.)
2127           assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2128           ciKlass *ss = klass->super_of_depth(depth);
2129           return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2130         }
2131       }
2132     }
2133 
2134     // If the type is enough to determine that the thing is not an array,
2135     // we can give the layout_helper a positive interval type.
2136     // This will help short-circuit some reflective code.
2137     if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
2138         && !klass->is_array_klass() // not directly typed as an array
2139         && !klass->is_interface()  // specifically not Serializable & Cloneable
2140         && !klass->is_java_lang_Object()   // not the supertype of all T[]
2141         ) {
2142       // Note:  When interfaces are reliable, we can narrow the interface
2143       // test to (klass != Serializable && klass != Cloneable).
2144       assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2145       jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2146       // The key property of this type is that it folds up tests
2147       // for array-ness, since it proves that the layout_helper is positive.
2148       // Thus, a generic value like the basic object layout helper works fine.
2149       return TypeInt::make(min_size, max_jint, Type::WidenMin);
2150     }
2151   }
2152 
2153   // If we are loading from a freshly-allocated object, produce a zero,
2154   // if the load is provably beyond the header of the object.
2155   // (Also allow a variable load from a fresh array to produce zero.)
2156   const TypeOopPtr *tinst = tp->isa_oopptr();
2157   bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
2158   bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
2159   if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2160     Node* value = can_see_stored_value(mem,phase);
2161     if (value != NULL && value->is_Con()) {
2162       assert(value->bottom_type()->higher_equal(_type),"sanity");
2163       return value->bottom_type();
2164     }
2165   }
2166 
2167   bool is_vect = (_type->isa_vect() != NULL);
2168   if (is_instance && !is_vect) {
2169     // If we have an instance type and our memory input is the
2170     // programs's initial memory state, there is no matching store,
2171     // so just return a zero of the appropriate type -
2172     // except if it is vectorized - then we have no zero constant.
2173     Node *mem = in(MemNode::Memory);
2174     if (mem->is_Parm() && mem->in(0)->is_Start()) {
2175       assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2176       return Type::get_zero_type(_type->basic_type());
2177     }
2178   }
2179   Node* alloc = is_new_object_mark_load(phase);
2180   if (alloc != NULL) {
2181     if (EnableValhalla) {
2182       // The mark word may contain property bits (inline, flat, null-free)
2183       Node* klass_node = alloc->in(AllocateNode::KlassNode);
2184       const TypeKlassPtr* tkls = phase->type(klass_node)->is_klassptr();
2185       ciKlass* klass = tkls->klass();
2186       if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact()) {
2187         return TypeX::make(klass->prototype_header().value());
2188       }
2189     } else {
2190       return TypeX::make(markWord::prototype().value());
2191     }
2192   }
2193 
2194   return _type;
2195 }
2196 
2197 //------------------------------match_edge-------------------------------------
2198 // Do we Match on this edge index or not?  Match only the address.
2199 uint LoadNode::match_edge(uint idx) const {
2200   return idx == MemNode::Address;
2201 }
2202 
2203 //--------------------------LoadBNode::Ideal--------------------------------------
2204 //
2205 //  If the previous store is to the same address as this load,
2206 //  and the value stored was larger than a byte, replace this load
2207 //  with the value stored truncated to a byte.  If no truncation is
2208 //  needed, the replacement is done in LoadNode::Identity().
2209 //
2210 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2211   Node* mem = in(MemNode::Memory);
2212   Node* value = can_see_stored_value(mem,phase);
2213   if (value != NULL) {
2214     Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2215     if (narrow != value) {
2216       return narrow;
2217     }
2218   }
2219   // Identity call will handle the case where truncation is not needed.
2220   return LoadNode::Ideal(phase, can_reshape);
2221 }
2222 
2223 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2224   Node* mem = in(MemNode::Memory);
2225   Node* value = can_see_stored_value(mem,phase);
2226   if (value != NULL && value->is_Con() &&
2227       !value->bottom_type()->higher_equal(_type)) {
2228     // If the input to the store does not fit with the load's result type,
2229     // it must be truncated. We can't delay until Ideal call since
2230     // a singleton Value is needed for split_thru_phi optimization.
2231     int con = value->get_int();
2232     return TypeInt::make((con << 24) >> 24);
2233   }
2234   return LoadNode::Value(phase);
2235 }
2236 
2237 //--------------------------LoadUBNode::Ideal-------------------------------------
2238 //
2239 //  If the previous store is to the same address as this load,
2240 //  and the value stored was larger than a byte, replace this load
2241 //  with the value stored truncated to a byte.  If no truncation is
2242 //  needed, the replacement is done in LoadNode::Identity().
2243 //
2244 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2245   Node* mem = in(MemNode::Memory);
2246   Node* value = can_see_stored_value(mem, phase);
2247   if (value != NULL) {
2248     Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2249     if (narrow != value) {
2250       return narrow;
2251     }
2252   }
2253   // Identity call will handle the case where truncation is not needed.
2254   return LoadNode::Ideal(phase, can_reshape);
2255 }
2256 
2257 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2258   Node* mem = in(MemNode::Memory);
2259   Node* value = can_see_stored_value(mem,phase);
2260   if (value != NULL && value->is_Con() &&
2261       !value->bottom_type()->higher_equal(_type)) {
2262     // If the input to the store does not fit with the load's result type,
2263     // it must be truncated. We can't delay until Ideal call since
2264     // a singleton Value is needed for split_thru_phi optimization.
2265     int con = value->get_int();
2266     return TypeInt::make(con & 0xFF);
2267   }
2268   return LoadNode::Value(phase);
2269 }
2270 
2271 //--------------------------LoadUSNode::Ideal-------------------------------------
2272 //
2273 //  If the previous store is to the same address as this load,
2274 //  and the value stored was larger than a char, replace this load
2275 //  with the value stored truncated to a char.  If no truncation is
2276 //  needed, the replacement is done in LoadNode::Identity().
2277 //
2278 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2279   Node* mem = in(MemNode::Memory);
2280   Node* value = can_see_stored_value(mem,phase);
2281   if (value != NULL) {
2282     Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2283     if (narrow != value) {
2284       return narrow;
2285     }
2286   }
2287   // Identity call will handle the case where truncation is not needed.
2288   return LoadNode::Ideal(phase, can_reshape);
2289 }
2290 
2291 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2292   Node* mem = in(MemNode::Memory);
2293   Node* value = can_see_stored_value(mem,phase);
2294   if (value != NULL && value->is_Con() &&
2295       !value->bottom_type()->higher_equal(_type)) {
2296     // If the input to the store does not fit with the load's result type,
2297     // it must be truncated. We can't delay until Ideal call since
2298     // a singleton Value is needed for split_thru_phi optimization.
2299     int con = value->get_int();
2300     return TypeInt::make(con & 0xFFFF);
2301   }
2302   return LoadNode::Value(phase);
2303 }
2304 
2305 //--------------------------LoadSNode::Ideal--------------------------------------
2306 //
2307 //  If the previous store is to the same address as this load,
2308 //  and the value stored was larger than a short, replace this load
2309 //  with the value stored truncated to a short.  If no truncation is
2310 //  needed, the replacement is done in LoadNode::Identity().
2311 //
2312 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2313   Node* mem = in(MemNode::Memory);
2314   Node* value = can_see_stored_value(mem,phase);
2315   if (value != NULL) {
2316     Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2317     if (narrow != value) {
2318       return narrow;
2319     }
2320   }
2321   // Identity call will handle the case where truncation is not needed.
2322   return LoadNode::Ideal(phase, can_reshape);
2323 }
2324 
2325 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2326   Node* mem = in(MemNode::Memory);
2327   Node* value = can_see_stored_value(mem,phase);
2328   if (value != NULL && value->is_Con() &&
2329       !value->bottom_type()->higher_equal(_type)) {
2330     // If the input to the store does not fit with the load's result type,
2331     // it must be truncated. We can't delay until Ideal call since
2332     // a singleton Value is needed for split_thru_phi optimization.
2333     int con = value->get_int();
2334     return TypeInt::make((con << 16) >> 16);
2335   }
2336   return LoadNode::Value(phase);
2337 }
2338 
2339 //=============================================================================
2340 //----------------------------LoadKlassNode::make------------------------------
2341 // Polymorphic factory method:
2342 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
2343                           const TypeKlassPtr* tk) {
2344   // sanity check the alias category against the created node type
2345   const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2346   assert(adr_type != NULL, "expecting TypeKlassPtr");
2347 #ifdef _LP64
2348   if (adr_type->is_ptr_to_narrowklass()) {
2349     assert(UseCompressedClassPointers, "no compressed klasses");
2350     Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2351     return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2352   }
2353 #endif
2354   assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2355   return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2356 }
2357 
2358 //------------------------------Value------------------------------------------
2359 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2360   return klass_value_common(phase);
2361 }
2362 
2363 // In most cases, LoadKlassNode does not have the control input set. If the control
2364 // input is set, it must not be removed (by LoadNode::Ideal()).
2365 bool LoadKlassNode::can_remove_control() const {
2366   return false;
2367 }
2368 
2369 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2370   // Either input is TOP ==> the result is TOP
2371   const Type *t1 = phase->type( in(MemNode::Memory) );
2372   if (t1 == Type::TOP)  return Type::TOP;
2373   Node *adr = in(MemNode::Address);
2374   const Type *t2 = phase->type( adr );
2375   if (t2 == Type::TOP)  return Type::TOP;
2376   const TypePtr *tp = t2->is_ptr();
2377   if (TypePtr::above_centerline(tp->ptr()) ||
2378       tp->ptr() == TypePtr::Null)  return Type::TOP;
2379 
2380   // Return a more precise klass, if possible
2381   const TypeInstPtr *tinst = tp->isa_instptr();
2382   if (tinst != NULL) {
2383     ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2384     int offset = tinst->offset();
2385     if (ik == phase->C->env()->Class_klass()
2386         && (offset == java_lang_Class::klass_offset() ||
2387             offset == java_lang_Class::array_klass_offset())) {
2388       // We are loading a special hidden field from a Class mirror object,
2389       // the field which points to the VM's Klass metaobject.
2390       bool null_free = false;
2391       ciType* t = tinst->java_mirror_type(&null_free);
2392       // java_mirror_type returns non-null for compile-time Class constants.
2393       if (t != NULL) {
2394         // constant oop => constant klass
2395         if (offset == java_lang_Class::array_klass_offset()) {
2396           if (t->is_void()) {
2397             // We cannot create a void array.  Since void is a primitive type return null
2398             // klass.  Users of this result need to do a null check on the returned klass.
2399             return TypePtr::NULL_PTR;
2400           }
2401           return TypeKlassPtr::make(ciArrayKlass::make(t, null_free));
2402         }
2403         if (!t->is_klass()) {
2404           // a primitive Class (e.g., int.class) has NULL for a klass field
2405           return TypePtr::NULL_PTR;
2406         }
2407         // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2408         return TypeKlassPtr::make(t->as_klass());
2409       }
2410       // non-constant mirror, so we can't tell what's going on
2411     }
2412     if( !ik->is_loaded() )
2413       return _type;             // Bail out if not loaded
2414     if (offset == oopDesc::klass_offset_in_bytes()) {
2415       if (tinst->klass_is_exact()) {
2416         return TypeKlassPtr::make(ik);
2417       }
2418       // See if we can become precise: no subklasses and no interface
2419       // (Note:  We need to support verified interfaces.)
2420       if (!ik->is_interface() && !ik->has_subklass()) {
2421         // Add a dependence; if any subclass added we need to recompile
2422         if (!ik->is_final()) {
2423           // %%% should use stronger assert_unique_concrete_subtype instead
2424           phase->C->dependencies()->assert_leaf_type(ik);
2425         }
2426         // Return precise klass
2427         return TypeKlassPtr::make(ik);
2428       }
2429 
2430       // Return root of possible klass
2431       return TypeInstKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0), tinst->flatten_array());
2432     }
2433   }
2434 
2435   // Check for loading klass from an array
2436   const TypeAryPtr *tary = tp->isa_aryptr();
2437   if (tary != NULL) {
2438     ciKlass *tary_klass = tary->klass();
2439     if (tary_klass != NULL   // can be NULL when at BOTTOM or TOP
2440         && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2441       if (tary->klass_is_exact()) {
2442         return TypeKlassPtr::make(tary_klass);
2443       }
2444       ciArrayKlass* ak = tary_klass->as_array_klass();
2445       // If the klass is an object array, we defer the question to the
2446       // array component klass.
2447       if (ak->is_obj_array_klass()) {
2448         assert(ak->is_loaded(), "");
2449         ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2450         if (base_k->is_loaded() && base_k->is_instance_klass()) {
2451           ciInstanceKlass *ik = base_k->as_instance_klass();
2452           // See if we can become precise: no subklasses and no interface
2453           // Do not fold klass loads from [LMyValue. The runtime type might be [QMyValue due to [QMyValue <: [LMyValue
2454           // and the klass for [QMyValue is not equal to the klass for [LMyValue.
2455           if (!ik->is_interface() && !ik->has_subklass() && (!ik->is_inlinetype() || ak->is_elem_null_free())) {
2456             // Add a dependence; if any subclass added we need to recompile
2457             if (!ik->is_final()) {
2458               phase->C->dependencies()->assert_leaf_type(ik);
2459             }
2460             // Return precise array klass
2461             return TypeKlassPtr::make(ak);
2462           }
2463         }
2464         return TypeAryKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0), tary->is_not_flat(), tary->is_not_null_free(), tary->is_null_free());
2465       } else if (ak->is_type_array_klass()) {
2466         return TypeKlassPtr::make(ak); // These are always precise
2467       }
2468     }
2469   }
2470 
2471   // Check for loading klass from an array klass
2472   const TypeKlassPtr *tkls = tp->isa_klassptr();
2473   if (tkls != NULL && !StressReflectiveCode) {
2474     if (!tkls->is_loaded()) {
2475       return _type;             // Bail out if not loaded
2476     }
2477     ciKlass* klass = tkls->klass();
2478     if( klass->is_obj_array_klass() &&
2479         tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2480       ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2481       // // Always returning precise element type is incorrect,
2482       // // e.g., element type could be object and array may contain strings
2483       // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2484 
2485       // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2486       // according to the element type's subclassing.
2487       return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0));
2488     } else if (klass->is_flat_array_klass() &&
2489                tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2490       ciKlass* elem = klass->as_flat_array_klass()->element_klass();
2491       return TypeInstKlassPtr::make(tkls->ptr(), elem, Type::Offset(0), /* flatten_array= */ true);
2492     }
2493     if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2494         tkls->offset() == in_bytes(Klass::super_offset())) {
2495       ciKlass* sup = klass->as_instance_klass()->super();
2496       // The field is Klass::_super.  Return its (constant) value.
2497       // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2498       return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2499     }
2500   }
2501 
2502   // Bailout case
2503   return LoadNode::Value(phase);
2504 }
2505 
2506 //------------------------------Identity---------------------------------------
2507 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2508 // Also feed through the klass in Allocate(...klass...)._klass.
2509 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2510   return klass_identity_common(phase);
2511 }
2512 
2513 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2514   Node* x = LoadNode::Identity(phase);
2515   if (x != this)  return x;
2516 
2517   // Take apart the address into an oop and and offset.
2518   // Return 'this' if we cannot.
2519   Node*    adr    = in(MemNode::Address);
2520   intptr_t offset = 0;
2521   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2522   if (base == NULL)     return this;
2523   const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2524   if (toop == NULL)     return this;
2525 
2526   // Step over potential GC barrier for OopHandle resolve
2527   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2528   if (bs->is_gc_barrier_node(base)) {
2529     base = bs->step_over_gc_barrier(base);
2530   }
2531 
2532   // We can fetch the klass directly through an AllocateNode.
2533   // This works even if the klass is not constant (clone or newArray).
2534   if (offset == oopDesc::klass_offset_in_bytes()) {
2535     Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2536     if (allocated_klass != NULL) {
2537       return allocated_klass;
2538     }
2539   }
2540 
2541   // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2542   // See inline_native_Class_query for occurrences of these patterns.
2543   // Java Example:  x.getClass().isAssignableFrom(y)
2544   //
2545   // This improves reflective code, often making the Class
2546   // mirror go completely dead.  (Current exception:  Class
2547   // mirrors may appear in debug info, but we could clean them out by
2548   // introducing a new debug info operator for Klass.java_mirror).
2549 
2550   if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2551       && offset == java_lang_Class::klass_offset()) {
2552     if (base->is_Load()) {
2553       Node* base2 = base->in(MemNode::Address);
2554       if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2555         Node* adr2 = base2->in(MemNode::Address);
2556         const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2557         if (tkls != NULL && !tkls->empty()
2558             && (tkls->klass()->is_instance_klass() ||
2559               tkls->klass()->is_array_klass())
2560             && adr2->is_AddP()
2561            ) {
2562           int mirror_field = in_bytes(Klass::java_mirror_offset());
2563           if (tkls->offset() == mirror_field) {
2564             return adr2->in(AddPNode::Base);
2565           }
2566         }
2567       }
2568     }
2569   }
2570 
2571   return this;
2572 }
2573 
2574 
2575 //------------------------------Value------------------------------------------
2576 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2577   const Type *t = klass_value_common(phase);
2578   if (t == Type::TOP)
2579     return t;
2580 
2581   return t->make_narrowklass();
2582 }
2583 
2584 //------------------------------Identity---------------------------------------
2585 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2586 // Also feed through the klass in Allocate(...klass...)._klass.
2587 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2588   Node *x = klass_identity_common(phase);
2589 
2590   const Type *t = phase->type( x );
2591   if( t == Type::TOP ) return x;
2592   if( t->isa_narrowklass()) return x;
2593   assert (!t->isa_narrowoop(), "no narrow oop here");
2594 
2595   return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2596 }
2597 
2598 //------------------------------Value-----------------------------------------
2599 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2600   // Either input is TOP ==> the result is TOP
2601   const Type *t1 = phase->type( in(MemNode::Memory) );
2602   if( t1 == Type::TOP ) return Type::TOP;
2603   Node *adr = in(MemNode::Address);
2604   const Type *t2 = phase->type( adr );
2605   if( t2 == Type::TOP ) return Type::TOP;
2606   const TypePtr *tp = t2->is_ptr();
2607   if (TypePtr::above_centerline(tp->ptr()))  return Type::TOP;
2608   const TypeAryPtr *tap = tp->isa_aryptr();
2609   if( !tap ) return _type;
2610   return tap->size();
2611 }
2612 
2613 //-------------------------------Ideal---------------------------------------
2614 // Feed through the length in AllocateArray(...length...)._length.
2615 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2616   Node* p = MemNode::Ideal_common(phase, can_reshape);
2617   if (p)  return (p == NodeSentinel) ? NULL : p;
2618 
2619   // Take apart the address into an oop and and offset.
2620   // Return 'this' if we cannot.
2621   Node*    adr    = in(MemNode::Address);
2622   intptr_t offset = 0;
2623   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase,  offset);
2624   if (base == NULL)     return NULL;
2625   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2626   if (tary == NULL)     return NULL;
2627 
2628   // We can fetch the length directly through an AllocateArrayNode.
2629   // This works even if the length is not constant (clone or newArray).
2630   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2631     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2632     if (alloc != NULL) {
2633       Node* allocated_length = alloc->Ideal_length();
2634       Node* len = alloc->make_ideal_length(tary, phase);
2635       if (allocated_length != len) {
2636         // New CastII improves on this.
2637         return len;
2638       }
2639     }
2640   }
2641 
2642   return NULL;
2643 }
2644 
2645 //------------------------------Identity---------------------------------------
2646 // Feed through the length in AllocateArray(...length...)._length.
2647 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2648   Node* x = LoadINode::Identity(phase);
2649   if (x != this)  return x;
2650 
2651   // Take apart the address into an oop and and offset.
2652   // Return 'this' if we cannot.
2653   Node*    adr    = in(MemNode::Address);
2654   intptr_t offset = 0;
2655   Node*    base   = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2656   if (base == NULL)     return this;
2657   const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2658   if (tary == NULL)     return this;
2659 
2660   // We can fetch the length directly through an AllocateArrayNode.
2661   // This works even if the length is not constant (clone or newArray).
2662   if (offset == arrayOopDesc::length_offset_in_bytes()) {
2663     AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2664     if (alloc != NULL) {
2665       Node* allocated_length = alloc->Ideal_length();
2666       // Do not allow make_ideal_length to allocate a CastII node.
2667       Node* len = alloc->make_ideal_length(tary, phase, false);
2668       if (allocated_length == len) {
2669         // Return allocated_length only if it would not be improved by a CastII.
2670         return allocated_length;
2671       }
2672     }
2673   }
2674 
2675   return this;
2676 
2677 }
2678 
2679 //=============================================================================
2680 //---------------------------StoreNode::make-----------------------------------
2681 // Polymorphic factory method:
2682 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2683   assert((mo == unordered || mo == release), "unexpected");
2684   Compile* C = gvn.C;
2685   assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2686          ctl != NULL, "raw memory operations should have control edge");
2687 
2688   switch (bt) {
2689   case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2690   case T_BYTE:    return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2691   case T_INT:     return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2692   case T_CHAR:
2693   case T_SHORT:   return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2694   case T_LONG:    return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2695   case T_FLOAT:   return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2696   case T_DOUBLE:  return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2697   case T_METADATA:
2698   case T_ADDRESS:
2699   case T_PRIMITIVE_OBJECT:
2700   case T_OBJECT:
2701 #ifdef _LP64
2702     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2703       val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2704       return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2705     } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2706                (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2707                 adr->bottom_type()->isa_rawptr())) {
2708       val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2709       return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2710     }
2711 #endif
2712     {
2713       return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2714     }
2715   default:
2716     ShouldNotReachHere();
2717     return (StoreNode*)NULL;
2718   }
2719 }
2720 
2721 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2722   bool require_atomic = true;
2723   return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2724 }
2725 
2726 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2727   bool require_atomic = true;
2728   return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2729 }
2730 
2731 
2732 //--------------------------bottom_type----------------------------------------
2733 const Type *StoreNode::bottom_type() const {
2734   return Type::MEMORY;
2735 }
2736 
2737 //------------------------------hash-------------------------------------------
2738 uint StoreNode::hash() const {
2739   // unroll addition of interesting fields
2740   //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2741 
2742   // Since they are not commoned, do not hash them:
2743   return NO_HASH;
2744 }
2745 
2746 //------------------------------Ideal------------------------------------------
2747 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2748 // When a store immediately follows a relevant allocation/initialization,
2749 // try to capture it into the initialization, or hoist it above.
2750 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2751   Node* p = MemNode::Ideal_common(phase, can_reshape);
2752   if (p)  return (p == NodeSentinel) ? NULL : p;
2753 
2754   Node* mem     = in(MemNode::Memory);
2755   Node* address = in(MemNode::Address);
2756   Node* value   = in(MemNode::ValueIn);
2757   // Back-to-back stores to same address?  Fold em up.  Generally
2758   // unsafe if I have intervening uses...  Also disallowed for StoreCM
2759   // since they must follow each StoreP operation.  Redundant StoreCMs
2760   // are eliminated just before matching in final_graph_reshape.
2761   if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
2762     Node* st = mem;
2763     // If Store 'st' has more than one use, we cannot fold 'st' away.
2764     // For example, 'st' might be the final state at a conditional
2765     // return.  Or, 'st' might be used by some node which is live at
2766     // the same time 'st' is live, which might be unschedulable.  So,
2767     // require exactly ONE user until such time as we clone 'mem' for
2768     // each of 'mem's uses (thus making the exactly-1-user-rule hold
2769     // true).
2770     while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2771       // Looking at a dead closed cycle of memory?
2772       assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2773       assert(Opcode() == st->Opcode() ||
2774              st->Opcode() == Op_StoreVector ||
2775              Opcode() == Op_StoreVector ||
2776              st->Opcode() == Op_StoreVectorScatter ||
2777              Opcode() == Op_StoreVectorScatter ||
2778              phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2779              (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2780              (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2781              (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2782              (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2783              "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2784 
2785       if (st->in(MemNode::Address)->eqv_uncast(address) &&
2786           st->as_Store()->memory_size() <= this->memory_size()) {
2787         Node* use = st->raw_out(0);
2788         if (phase->is_IterGVN()) {
2789           phase->is_IterGVN()->rehash_node_delayed(use);
2790         }
2791         // It's OK to do this in the parser, since DU info is always accurate,
2792         // and the parser always refers to nodes via SafePointNode maps.
2793         use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2794         return this;
2795       }
2796       st = st->in(MemNode::Memory);
2797     }
2798   }
2799 
2800 
2801   // Capture an unaliased, unconditional, simple store into an initializer.
2802   // Or, if it is independent of the allocation, hoist it above the allocation.
2803   if (ReduceFieldZeroing && /*can_reshape &&*/
2804       mem->is_Proj() && mem->in(0)->is_Initialize()) {
2805     InitializeNode* init = mem->in(0)->as_Initialize();
2806     intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2807     if (offset > 0) {
2808       Node* moved = init->capture_store(this, offset, phase, can_reshape);
2809       // If the InitializeNode captured me, it made a raw copy of me,
2810       // and I need to disappear.
2811       if (moved != NULL) {
2812         // %%% hack to ensure that Ideal returns a new node:
2813         mem = MergeMemNode::make(mem);
2814         return mem;             // fold me away
2815       }
2816     }
2817   }
2818 
2819   // Fold reinterpret cast into memory operation:
2820   //    StoreX mem (MoveY2X v) => StoreY mem v
2821   if (value->is_Move()) {
2822     const Type* vt = value->in(1)->bottom_type();
2823     if (has_reinterpret_variant(vt)) {
2824       if (phase->C->post_loop_opts_phase()) {
2825         return convert_to_reinterpret_store(*phase, value->in(1), vt);
2826       } else {
2827         phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2828       }
2829     }
2830   }
2831 
2832   return NULL;                  // No further progress
2833 }
2834 
2835 //------------------------------Value-----------------------------------------
2836 const Type* StoreNode::Value(PhaseGVN* phase) const {
2837   // Either input is TOP ==> the result is TOP
2838   const Type *t1 = phase->type( in(MemNode::Memory) );
2839   if( t1 == Type::TOP ) return Type::TOP;
2840   const Type *t2 = phase->type( in(MemNode::Address) );
2841   if( t2 == Type::TOP ) return Type::TOP;
2842   const Type *t3 = phase->type( in(MemNode::ValueIn) );
2843   if( t3 == Type::TOP ) return Type::TOP;
2844   return Type::MEMORY;
2845 }
2846 
2847 //------------------------------Identity---------------------------------------
2848 // Remove redundant stores:
2849 //   Store(m, p, Load(m, p)) changes to m.
2850 //   Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2851 Node* StoreNode::Identity(PhaseGVN* phase) {
2852   Node* mem = in(MemNode::Memory);
2853   Node* adr = in(MemNode::Address);
2854   Node* val = in(MemNode::ValueIn);
2855 
2856   Node* result = this;
2857 
2858   // Load then Store?  Then the Store is useless
2859   if (val->is_Load() &&
2860       val->in(MemNode::Address)->eqv_uncast(adr) &&
2861       val->in(MemNode::Memory )->eqv_uncast(mem) &&
2862       val->as_Load()->store_Opcode() == Opcode()) {
2863     result = mem;
2864   }
2865 
2866   // Two stores in a row of the same value?
2867   if (result == this &&
2868       mem->is_Store() &&
2869       mem->in(MemNode::Address)->eqv_uncast(adr) &&
2870       mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2871       mem->Opcode() == Opcode()) {
2872     result = mem;
2873   }
2874 
2875   // Store of zero anywhere into a freshly-allocated object?
2876   // Then the store is useless.
2877   // (It must already have been captured by the InitializeNode.)
2878   if (result == this && ReduceFieldZeroing) {
2879     // a newly allocated object is already all-zeroes everywhere
2880     if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2881         (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2882       assert(!phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == NULL, "storing null to inline type array is forbidden");
2883       result = mem;
2884     }
2885 
2886     if (result == this && phase->type(val)->is_zero_type()) {
2887       // the store may also apply to zero-bits in an earlier object
2888       Node* prev_mem = find_previous_store(phase);
2889       // Steps (a), (b):  Walk past independent stores to find an exact match.
2890       if (prev_mem != NULL) {
2891         Node* prev_val = can_see_stored_value(prev_mem, phase);
2892         if (prev_val != NULL && prev_val == val) {
2893           // prev_val and val might differ by a cast; it would be good
2894           // to keep the more informative of the two.
2895           result = mem;
2896         }
2897       }
2898     }
2899   }
2900 
2901   PhaseIterGVN* igvn = phase->is_IterGVN();
2902   if (result != this && igvn != NULL) {
2903     MemBarNode* trailing = trailing_membar();
2904     if (trailing != NULL) {
2905 #ifdef ASSERT
2906       const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2907       assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2908 #endif
2909       trailing->remove(igvn);
2910     }
2911   }
2912 
2913   return result;
2914 }
2915 
2916 //------------------------------match_edge-------------------------------------
2917 // Do we Match on this edge index or not?  Match only memory & value
2918 uint StoreNode::match_edge(uint idx) const {
2919   return idx == MemNode::Address || idx == MemNode::ValueIn;
2920 }
2921 
2922 //------------------------------cmp--------------------------------------------
2923 // Do not common stores up together.  They generally have to be split
2924 // back up anyways, so do not bother.
2925 bool StoreNode::cmp( const Node &n ) const {
2926   return (&n == this);          // Always fail except on self
2927 }
2928 
2929 //------------------------------Ideal_masked_input-----------------------------
2930 // Check for a useless mask before a partial-word store
2931 // (StoreB ... (AndI valIn conIa) )
2932 // If (conIa & mask == mask) this simplifies to
2933 // (StoreB ... (valIn) )
2934 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2935   Node *val = in(MemNode::ValueIn);
2936   if( val->Opcode() == Op_AndI ) {
2937     const TypeInt *t = phase->type( val->in(2) )->isa_int();
2938     if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2939       set_req_X(MemNode::ValueIn, val->in(1), phase);
2940       return this;
2941     }
2942   }
2943   return NULL;
2944 }
2945 
2946 
2947 //------------------------------Ideal_sign_extended_input----------------------
2948 // Check for useless sign-extension before a partial-word store
2949 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2950 // If (conIL == conIR && conIR <= num_bits)  this simplifies to
2951 // (StoreB ... (valIn) )
2952 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2953   Node *val = in(MemNode::ValueIn);
2954   if( val->Opcode() == Op_RShiftI ) {
2955     const TypeInt *t = phase->type( val->in(2) )->isa_int();
2956     if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2957       Node *shl = val->in(1);
2958       if( shl->Opcode() == Op_LShiftI ) {
2959         const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2960         if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2961           set_req_X(MemNode::ValueIn, shl->in(1), phase);
2962           return this;
2963         }
2964       }
2965     }
2966   }
2967   return NULL;
2968 }
2969 
2970 //------------------------------value_never_loaded-----------------------------------
2971 // Determine whether there are any possible loads of the value stored.
2972 // For simplicity, we actually check if there are any loads from the
2973 // address stored to, not just for loads of the value stored by this node.
2974 //
2975 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2976   Node *adr = in(Address);
2977   const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2978   if (adr_oop == NULL)
2979     return false;
2980   if (!adr_oop->is_known_instance_field())
2981     return false; // if not a distinct instance, there may be aliases of the address
2982   for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2983     Node *use = adr->fast_out(i);
2984     if (use->is_Load() || use->is_LoadStore()) {
2985       return false;
2986     }
2987   }
2988   return true;
2989 }
2990 
2991 MemBarNode* StoreNode::trailing_membar() const {
2992   if (is_release()) {
2993     MemBarNode* trailing_mb = NULL;
2994     for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2995       Node* u = fast_out(i);
2996       if (u->is_MemBar()) {
2997         if (u->as_MemBar()->trailing_store()) {
2998           assert(u->Opcode() == Op_MemBarVolatile, "");
2999           assert(trailing_mb == NULL, "only one");
3000           trailing_mb = u->as_MemBar();
3001 #ifdef ASSERT
3002           Node* leading = u->as_MemBar()->leading_membar();
3003           assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3004           assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3005           assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3006 #endif
3007         } else {
3008           assert(u->as_MemBar()->standalone(), "");
3009         }
3010       }
3011     }
3012     return trailing_mb;
3013   }
3014   return NULL;
3015 }
3016 
3017 
3018 //=============================================================================
3019 //------------------------------Ideal------------------------------------------
3020 // If the store is from an AND mask that leaves the low bits untouched, then
3021 // we can skip the AND operation.  If the store is from a sign-extension
3022 // (a left shift, then right shift) we can skip both.
3023 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3024   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3025   if( progress != NULL ) return progress;
3026 
3027   progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3028   if( progress != NULL ) return progress;
3029 
3030   // Finally check the default case
3031   return StoreNode::Ideal(phase, can_reshape);
3032 }
3033 
3034 //=============================================================================
3035 //------------------------------Ideal------------------------------------------
3036 // If the store is from an AND mask that leaves the low bits untouched, then
3037 // we can skip the AND operation
3038 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3039   Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3040   if( progress != NULL ) return progress;
3041 
3042   progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3043   if( progress != NULL ) return progress;
3044 
3045   // Finally check the default case
3046   return StoreNode::Ideal(phase, can_reshape);
3047 }
3048 
3049 //=============================================================================
3050 //------------------------------Identity---------------------------------------
3051 Node* StoreCMNode::Identity(PhaseGVN* phase) {
3052   // No need to card mark when storing a null ptr
3053   Node* my_store = in(MemNode::OopStore);
3054   if (my_store->is_Store()) {
3055     const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
3056     if( t1 == TypePtr::NULL_PTR ) {
3057       return in(MemNode::Memory);
3058     }
3059   }
3060   return this;
3061 }
3062 
3063 //=============================================================================
3064 //------------------------------Ideal---------------------------------------
3065 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
3066   Node* progress = StoreNode::Ideal(phase, can_reshape);
3067   if (progress != NULL) return progress;
3068 
3069   Node* my_store = in(MemNode::OopStore);
3070   if (my_store->is_MergeMem()) {
3071     if (oop_alias_idx() != phase->C->get_alias_index(TypeAryPtr::INLINES) ||
3072         phase->C->flattened_accesses_share_alias()) {
3073       // The alias that was recorded is no longer accurate enough.
3074       Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
3075       set_req_X(MemNode::OopStore, mem, phase);
3076       return this;
3077     }
3078   }
3079 
3080   return NULL;
3081 }
3082 
3083 //------------------------------Value-----------------------------------------
3084 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
3085   // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
3086   // If extra input is TOP ==> the result is TOP
3087   const Type* t = phase->type(in(MemNode::OopStore));
3088   if (t == Type::TOP) {
3089     return Type::TOP;
3090   }
3091   return StoreNode::Value(phase);
3092 }
3093 
3094 
3095 //=============================================================================
3096 //----------------------------------SCMemProjNode------------------------------
3097 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3098 {
3099   if (in(0) == NULL || phase->type(in(0)) == Type::TOP) {
3100     return Type::TOP;
3101   }
3102   return bottom_type();
3103 }
3104 
3105 //=============================================================================
3106 //----------------------------------LoadStoreNode------------------------------
3107 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3108   : Node(required),
3109     _type(rt),
3110     _adr_type(at),
3111     _barrier_data(0)
3112 {
3113   init_req(MemNode::Control, c  );
3114   init_req(MemNode::Memory , mem);
3115   init_req(MemNode::Address, adr);
3116   init_req(MemNode::ValueIn, val);
3117   init_class_id(Class_LoadStore);
3118 }
3119 
3120 //------------------------------Value-----------------------------------------
3121 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3122   // Either input is TOP ==> the result is TOP
3123   if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3124     return Type::TOP;
3125   }
3126   const Type* t = phase->type(in(MemNode::Memory));
3127   if (t == Type::TOP) {
3128     return Type::TOP;
3129   }
3130   t = phase->type(in(MemNode::Address));
3131   if (t == Type::TOP) {
3132     return Type::TOP;
3133   }
3134   t = phase->type(in(MemNode::ValueIn));
3135   if (t == Type::TOP) {
3136     return Type::TOP;
3137   }
3138   return bottom_type();
3139 }
3140 
3141 uint LoadStoreNode::ideal_reg() const {
3142   return _type->ideal_reg();
3143 }
3144 
3145 bool LoadStoreNode::result_not_used() const {
3146   for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3147     Node *x = fast_out(i);
3148     if (x->Opcode() == Op_SCMemProj) continue;
3149     return false;
3150   }
3151   return true;
3152 }
3153 
3154 MemBarNode* LoadStoreNode::trailing_membar() const {
3155   MemBarNode* trailing = NULL;
3156   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3157     Node* u = fast_out(i);
3158     if (u->is_MemBar()) {
3159       if (u->as_MemBar()->trailing_load_store()) {
3160         assert(u->Opcode() == Op_MemBarAcquire, "");
3161         assert(trailing == NULL, "only one");
3162         trailing = u->as_MemBar();
3163 #ifdef ASSERT
3164         Node* leading = trailing->leading_membar();
3165         assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3166         assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3167         assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3168 #endif
3169       } else {
3170         assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3171       }
3172     }
3173   }
3174 
3175   return trailing;
3176 }
3177 
3178 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3179 
3180 //=============================================================================
3181 //----------------------------------LoadStoreConditionalNode--------------------
3182 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
3183   init_req(ExpectedIn, ex );
3184 }
3185 
3186 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3187   // Either input is TOP ==> the result is TOP
3188   const Type* t = phase->type(in(ExpectedIn));
3189   if (t == Type::TOP) {
3190     return Type::TOP;
3191   }
3192   return LoadStoreNode::Value(phase);
3193 }
3194 
3195 //=============================================================================
3196 //-------------------------------adr_type--------------------------------------
3197 const TypePtr* ClearArrayNode::adr_type() const {
3198   Node *adr = in(3);
3199   if (adr == NULL)  return NULL; // node is dead
3200   return MemNode::calculate_adr_type(adr->bottom_type());
3201 }
3202 
3203 //------------------------------match_edge-------------------------------------
3204 // Do we Match on this edge index or not?  Do not match memory
3205 uint ClearArrayNode::match_edge(uint idx) const {
3206   return idx > 1;
3207 }
3208 
3209 //------------------------------Identity---------------------------------------
3210 // Clearing a zero length array does nothing
3211 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3212   return phase->type(in(2))->higher_equal(TypeX::ZERO)  ? in(1) : this;
3213 }
3214 
3215 //------------------------------Idealize---------------------------------------
3216 // Clearing a short array is faster with stores
3217 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3218   // Already know this is a large node, do not try to ideal it
3219   if (!IdealizeClearArrayNode || _is_large) return NULL;
3220 
3221   const int unit = BytesPerLong;
3222   const TypeX* t = phase->type(in(2))->isa_intptr_t();
3223   if (!t)  return NULL;
3224   if (!t->is_con())  return NULL;
3225   intptr_t raw_count = t->get_con();
3226   intptr_t size = raw_count;
3227   if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3228   // Clearing nothing uses the Identity call.
3229   // Negative clears are possible on dead ClearArrays
3230   // (see jck test stmt114.stmt11402.val).
3231   if (size <= 0 || size % unit != 0)  return NULL;
3232   intptr_t count = size / unit;
3233   // Length too long; communicate this to matchers and assemblers.
3234   // Assemblers are responsible to produce fast hardware clears for it.
3235   if (size > InitArrayShortSize) {
3236     return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
3237   } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3238     return NULL;
3239   }
3240   Node *mem = in(1);
3241   if( phase->type(mem)==Type::TOP ) return NULL;
3242   Node *adr = in(3);
3243   const Type* at = phase->type(adr);
3244   if( at==Type::TOP ) return NULL;
3245   const TypePtr* atp = at->isa_ptr();
3246   // adjust atp to be the correct array element address type
3247   if (atp == NULL)  atp = TypePtr::BOTTOM;
3248   else              atp = atp->add_offset(Type::OffsetBot);
3249   // Get base for derived pointer purposes
3250   if( adr->Opcode() != Op_AddP ) Unimplemented();
3251   Node *base = adr->in(1);
3252 
3253   Node *val = in(4);
3254   Node *off  = phase->MakeConX(BytesPerLong);
3255   mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3256   count--;
3257   while( count-- ) {
3258     mem = phase->transform(mem);
3259     adr = phase->transform(new AddPNode(base,adr,off));
3260     mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3261   }
3262   return mem;
3263 }
3264 
3265 //----------------------------step_through----------------------------------
3266 // Return allocation input memory edge if it is different instance
3267 // or itself if it is the one we are looking for.
3268 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3269   Node* n = *np;
3270   assert(n->is_ClearArray(), "sanity");
3271   intptr_t offset;
3272   AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3273   // This method is called only before Allocate nodes are expanded
3274   // during macro nodes expansion. Before that ClearArray nodes are
3275   // only generated in PhaseMacroExpand::generate_arraycopy() (before
3276   // Allocate nodes are expanded) which follows allocations.
3277   assert(alloc != NULL, "should have allocation");
3278   if (alloc->_idx == instance_id) {
3279     // Can not bypass initialization of the instance we are looking for.
3280     return false;
3281   }
3282   // Otherwise skip it.
3283   InitializeNode* init = alloc->initialization();
3284   if (init != NULL)
3285     *np = init->in(TypeFunc::Memory);
3286   else
3287     *np = alloc->in(TypeFunc::Memory);
3288   return true;
3289 }
3290 
3291 //----------------------------clear_memory-------------------------------------
3292 // Generate code to initialize object storage to zero.
3293 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3294                                    Node* val,
3295                                    Node* raw_val,
3296                                    intptr_t start_offset,
3297                                    Node* end_offset,
3298                                    PhaseGVN* phase) {
3299   intptr_t offset = start_offset;
3300 
3301   int unit = BytesPerLong;
3302   if ((offset % unit) != 0) {
3303     Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3304     adr = phase->transform(adr);
3305     const TypePtr* atp = TypeRawPtr::BOTTOM;
3306     if (val != NULL) {
3307       assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3308       mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3309     } else {
3310       assert(raw_val == NULL, "val may not be null");
3311       mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3312     }
3313     mem = phase->transform(mem);
3314     offset += BytesPerInt;
3315   }
3316   assert((offset % unit) == 0, "");
3317 
3318   // Initialize the remaining stuff, if any, with a ClearArray.
3319   return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3320 }
3321 
3322 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3323                                    Node* raw_val,
3324                                    Node* start_offset,
3325                                    Node* end_offset,
3326                                    PhaseGVN* phase) {
3327   if (start_offset == end_offset) {
3328     // nothing to do
3329     return mem;
3330   }
3331 
3332   int unit = BytesPerLong;
3333   Node* zbase = start_offset;
3334   Node* zend  = end_offset;
3335 
3336   // Scale to the unit required by the CPU:
3337   if (!Matcher::init_array_count_is_in_bytes) {
3338     Node* shift = phase->intcon(exact_log2(unit));
3339     zbase = phase->transform(new URShiftXNode(zbase, shift) );
3340     zend  = phase->transform(new URShiftXNode(zend,  shift) );
3341   }
3342 
3343   // Bulk clear double-words
3344   Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3345   Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3346   if (raw_val == NULL) {
3347     raw_val = phase->MakeConX(0);
3348   }
3349   mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3350   return phase->transform(mem);
3351 }
3352 
3353 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3354                                    Node* val,
3355                                    Node* raw_val,
3356                                    intptr_t start_offset,
3357                                    intptr_t end_offset,
3358                                    PhaseGVN* phase) {
3359   if (start_offset == end_offset) {
3360     // nothing to do
3361     return mem;
3362   }
3363 
3364   assert((end_offset % BytesPerInt) == 0, "odd end offset");
3365   intptr_t done_offset = end_offset;
3366   if ((done_offset % BytesPerLong) != 0) {
3367     done_offset -= BytesPerInt;
3368   }
3369   if (done_offset > start_offset) {
3370     mem = clear_memory(ctl, mem, dest, val, raw_val,
3371                        start_offset, phase->MakeConX(done_offset), phase);
3372   }
3373   if (done_offset < end_offset) { // emit the final 32-bit store
3374     Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3375     adr = phase->transform(adr);
3376     const TypePtr* atp = TypeRawPtr::BOTTOM;
3377     if (val != NULL) {
3378       assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3379       mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3380     } else {
3381       assert(raw_val == NULL, "val may not be null");
3382       mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3383     }
3384     mem = phase->transform(mem);
3385     done_offset += BytesPerInt;
3386   }
3387   assert(done_offset == end_offset, "");
3388   return mem;
3389 }
3390 
3391 //=============================================================================
3392 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3393   : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3394     _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3395 #ifdef ASSERT
3396   , _pair_idx(0)
3397 #endif
3398 {
3399   init_class_id(Class_MemBar);
3400   Node* top = C->top();
3401   init_req(TypeFunc::I_O,top);
3402   init_req(TypeFunc::FramePtr,top);
3403   init_req(TypeFunc::ReturnAdr,top);
3404   if (precedent != NULL)
3405     init_req(TypeFunc::Parms, precedent);
3406 }
3407 
3408 //------------------------------cmp--------------------------------------------
3409 uint MemBarNode::hash() const { return NO_HASH; }
3410 bool MemBarNode::cmp( const Node &n ) const {
3411   return (&n == this);          // Always fail except on self
3412 }
3413 
3414 //------------------------------make-------------------------------------------
3415 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3416   switch (opcode) {
3417   case Op_MemBarAcquire:     return new MemBarAcquireNode(C, atp, pn);
3418   case Op_LoadFence:         return new LoadFenceNode(C, atp, pn);
3419   case Op_MemBarRelease:     return new MemBarReleaseNode(C, atp, pn);
3420   case Op_StoreFence:        return new StoreFenceNode(C, atp, pn);
3421   case Op_MemBarStoreStore:  return new MemBarStoreStoreNode(C, atp, pn);
3422   case Op_StoreStoreFence:   return new StoreStoreFenceNode(C, atp, pn);
3423   case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3424   case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3425   case Op_MemBarVolatile:    return new MemBarVolatileNode(C, atp, pn);
3426   case Op_MemBarCPUOrder:    return new MemBarCPUOrderNode(C, atp, pn);
3427   case Op_OnSpinWait:        return new OnSpinWaitNode(C, atp, pn);
3428   case Op_Initialize:        return new InitializeNode(C, atp, pn);
3429   case Op_Blackhole:         return new BlackholeNode(C, atp, pn);
3430   default: ShouldNotReachHere(); return NULL;
3431   }
3432 }
3433 
3434 void MemBarNode::remove(PhaseIterGVN *igvn) {
3435   if (outcnt() != 2) {
3436     assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3437     assert(outcnt() == 1, "Only control then");
3438   }
3439   if (trailing_store() || trailing_load_store()) {
3440     MemBarNode* leading = leading_membar();
3441     if (leading != NULL) {
3442       assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3443       leading->remove(igvn);
3444     }
3445   }
3446   if (proj_out_or_null(TypeFunc::Memory) != NULL) {
3447     igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3448   }
3449   if (proj_out_or_null(TypeFunc::Control) != NULL) {
3450     igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3451   }
3452 }
3453 
3454 //------------------------------Ideal------------------------------------------
3455 // Return a node which is more "ideal" than the current node.  Strip out
3456 // control copies
3457 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3458   if (remove_dead_region(phase, can_reshape)) return this;
3459   // Don't bother trying to transform a dead node
3460   if (in(0) && in(0)->is_top()) {
3461     return NULL;
3462   }
3463 
3464   bool progress = false;
3465   // Eliminate volatile MemBars for scalar replaced objects.
3466   if (can_reshape && req() == (Precedent+1)) {
3467     bool eliminate = false;
3468     int opc = Opcode();
3469     if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3470       // Volatile field loads and stores.
3471       Node* my_mem = in(MemBarNode::Precedent);
3472       // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3473       if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3474         // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3475         // replace this Precedent (decodeN) with the Load instead.
3476         if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1))  {
3477           Node* load_node = my_mem->in(1);
3478           set_req(MemBarNode::Precedent, load_node);
3479           phase->is_IterGVN()->_worklist.push(my_mem);
3480           my_mem = load_node;
3481         } else {
3482           assert(my_mem->unique_out() == this, "sanity");
3483           del_req(Precedent);
3484           phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3485           my_mem = NULL;
3486         }
3487         progress = true;
3488       }
3489       if (my_mem != NULL && my_mem->is_Mem()) {
3490         const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3491         // Check for scalar replaced object reference.
3492         if( t_oop != NULL && t_oop->is_known_instance_field() &&
3493             t_oop->offset() != Type::OffsetBot &&
3494             t_oop->offset() != Type::OffsetTop) {
3495           eliminate = true;
3496         }
3497       }
3498     } else if (opc == Op_MemBarRelease) {
3499       // Final field stores.
3500       Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3501       if ((alloc != NULL) && alloc->is_Allocate() &&
3502           alloc->as_Allocate()->does_not_escape_thread()) {
3503         // The allocated object does not escape.
3504         eliminate = true;
3505       }
3506     }
3507     if (eliminate) {
3508       // Replace MemBar projections by its inputs.
3509       PhaseIterGVN* igvn = phase->is_IterGVN();
3510       remove(igvn);
3511       // Must return either the original node (now dead) or a new node
3512       // (Do not return a top here, since that would break the uniqueness of top.)
3513       return new ConINode(TypeInt::ZERO);
3514     }
3515   }
3516   return progress ? this : NULL;
3517 }
3518 
3519 //------------------------------Value------------------------------------------
3520 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3521   if( !in(0) ) return Type::TOP;
3522   if( phase->type(in(0)) == Type::TOP )
3523     return Type::TOP;
3524   return TypeTuple::MEMBAR;
3525 }
3526 
3527 //------------------------------match------------------------------------------
3528 // Construct projections for memory.
3529 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3530   switch (proj->_con) {
3531   case TypeFunc::Control:
3532   case TypeFunc::Memory:
3533     return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3534   }
3535   ShouldNotReachHere();
3536   return NULL;
3537 }
3538 
3539 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3540   trailing->_kind = TrailingStore;
3541   leading->_kind = LeadingStore;
3542 #ifdef ASSERT
3543   trailing->_pair_idx = leading->_idx;
3544   leading->_pair_idx = leading->_idx;
3545 #endif
3546 }
3547 
3548 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3549   trailing->_kind = TrailingLoadStore;
3550   leading->_kind = LeadingLoadStore;
3551 #ifdef ASSERT
3552   trailing->_pair_idx = leading->_idx;
3553   leading->_pair_idx = leading->_idx;
3554 #endif
3555 }
3556 
3557 MemBarNode* MemBarNode::trailing_membar() const {
3558   ResourceMark rm;
3559   Node* trailing = (Node*)this;
3560   VectorSet seen;
3561   Node_Stack multis(0);
3562   do {
3563     Node* c = trailing;
3564     uint i = 0;
3565     do {
3566       trailing = NULL;
3567       for (; i < c->outcnt(); i++) {
3568         Node* next = c->raw_out(i);
3569         if (next != c && next->is_CFG()) {
3570           if (c->is_MultiBranch()) {
3571             if (multis.node() == c) {
3572               multis.set_index(i+1);
3573             } else {
3574               multis.push(c, i+1);
3575             }
3576           }
3577           trailing = next;
3578           break;
3579         }
3580       }
3581       if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3582         break;
3583       }
3584       while (multis.size() > 0) {
3585         c = multis.node();
3586         i = multis.index();
3587         if (i < c->req()) {
3588           break;
3589         }
3590         multis.pop();
3591       }
3592     } while (multis.size() > 0);
3593   } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3594 
3595   MemBarNode* mb = trailing->as_MemBar();
3596   assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3597          (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3598   assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3599   return mb;
3600 }
3601 
3602 MemBarNode* MemBarNode::leading_membar() const {
3603   ResourceMark rm;
3604   VectorSet seen;
3605   Node_Stack regions(0);
3606   Node* leading = in(0);
3607   while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3608     while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3609       leading = NULL;
3610       while (regions.size() > 0 && leading == NULL) {
3611         Node* r = regions.node();
3612         uint i = regions.index();
3613         if (i < r->req()) {
3614           leading = r->in(i);
3615           regions.set_index(i+1);
3616         } else {
3617           regions.pop();
3618         }
3619       }
3620       if (leading == NULL) {
3621         assert(regions.size() == 0, "all paths should have been tried");
3622         return NULL;
3623       }
3624     }
3625     if (leading->is_Region()) {
3626       regions.push(leading, 2);
3627       leading = leading->in(1);
3628     } else {
3629       leading = leading->in(0);
3630     }
3631   }
3632 #ifdef ASSERT
3633   Unique_Node_List wq;
3634   wq.push((Node*)this);
3635   uint found = 0;
3636   for (uint i = 0; i < wq.size(); i++) {
3637     Node* n = wq.at(i);
3638     if (n->is_Region()) {
3639       for (uint j = 1; j < n->req(); j++) {
3640         Node* in = n->in(j);
3641         if (in != NULL && !in->is_top()) {
3642           wq.push(in);
3643         }
3644       }
3645     } else {
3646       if (n->is_MemBar() && n->as_MemBar()->leading()) {
3647         assert(n == leading, "consistency check failed");
3648         found++;
3649       } else {
3650         Node* in = n->in(0);
3651         if (in != NULL && !in->is_top()) {
3652           wq.push(in);
3653         }
3654       }
3655     }
3656   }
3657   assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3658 #endif
3659   if (leading == NULL) {
3660     return NULL;
3661   }
3662   MemBarNode* mb = leading->as_MemBar();
3663   assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3664          (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3665   assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3666   return mb;
3667 }
3668 
3669 #ifndef PRODUCT
3670 void BlackholeNode::format(PhaseRegAlloc* ra, outputStream* st) const {
3671   st->print("blackhole ");
3672   bool first = true;
3673   for (uint i = 0; i < req(); i++) {
3674     Node* n = in(i);
3675     if (n != NULL && OptoReg::is_valid(ra->get_reg_first(n))) {
3676       if (first) {
3677         first = false;
3678       } else {
3679         st->print(", ");
3680       }
3681       char buf[128];
3682       ra->dump_register(n, buf);
3683       st->print("%s", buf);
3684     }
3685   }
3686   st->cr();
3687 }
3688 #endif
3689 
3690 //===========================InitializeNode====================================
3691 // SUMMARY:
3692 // This node acts as a memory barrier on raw memory, after some raw stores.
3693 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3694 // The Initialize can 'capture' suitably constrained stores as raw inits.
3695 // It can coalesce related raw stores into larger units (called 'tiles').
3696 // It can avoid zeroing new storage for memory units which have raw inits.
3697 // At macro-expansion, it is marked 'complete', and does not optimize further.
3698 //
3699 // EXAMPLE:
3700 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3701 //   ctl = incoming control; mem* = incoming memory
3702 // (Note:  A star * on a memory edge denotes I/O and other standard edges.)
3703 // First allocate uninitialized memory and fill in the header:
3704 //   alloc = (Allocate ctl mem* 16 #short[].klass ...)
3705 //   ctl := alloc.Control; mem* := alloc.Memory*
3706 //   rawmem = alloc.Memory; rawoop = alloc.RawAddress
3707 // Then initialize to zero the non-header parts of the raw memory block:
3708 //   init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3709 //   ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3710 // After the initialize node executes, the object is ready for service:
3711 //   oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3712 // Suppose its body is immediately initialized as {1,2}:
3713 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3714 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
3715 //   mem.SLICE(#short[*]) := store2
3716 //
3717 // DETAILS:
3718 // An InitializeNode collects and isolates object initialization after
3719 // an AllocateNode and before the next possible safepoint.  As a
3720 // memory barrier (MemBarNode), it keeps critical stores from drifting
3721 // down past any safepoint or any publication of the allocation.
3722 // Before this barrier, a newly-allocated object may have uninitialized bits.
3723 // After this barrier, it may be treated as a real oop, and GC is allowed.
3724 //
3725 // The semantics of the InitializeNode include an implicit zeroing of
3726 // the new object from object header to the end of the object.
3727 // (The object header and end are determined by the AllocateNode.)
3728 //
3729 // Certain stores may be added as direct inputs to the InitializeNode.
3730 // These stores must update raw memory, and they must be to addresses
3731 // derived from the raw address produced by AllocateNode, and with
3732 // a constant offset.  They must be ordered by increasing offset.
3733 // The first one is at in(RawStores), the last at in(req()-1).
3734 // Unlike most memory operations, they are not linked in a chain,
3735 // but are displayed in parallel as users of the rawmem output of
3736 // the allocation.
3737 //
3738 // (See comments in InitializeNode::capture_store, which continue
3739 // the example given above.)
3740 //
3741 // When the associated Allocate is macro-expanded, the InitializeNode
3742 // may be rewritten to optimize collected stores.  A ClearArrayNode
3743 // may also be created at that point to represent any required zeroing.
3744 // The InitializeNode is then marked 'complete', prohibiting further
3745 // capturing of nearby memory operations.
3746 //
3747 // During macro-expansion, all captured initializations which store
3748 // constant values of 32 bits or smaller are coalesced (if advantageous)
3749 // into larger 'tiles' 32 or 64 bits.  This allows an object to be
3750 // initialized in fewer memory operations.  Memory words which are
3751 // covered by neither tiles nor non-constant stores are pre-zeroed
3752 // by explicit stores of zero.  (The code shape happens to do all
3753 // zeroing first, then all other stores, with both sequences occurring
3754 // in order of ascending offsets.)
3755 //
3756 // Alternatively, code may be inserted between an AllocateNode and its
3757 // InitializeNode, to perform arbitrary initialization of the new object.
3758 // E.g., the object copying intrinsics insert complex data transfers here.
3759 // The initialization must then be marked as 'complete' disable the
3760 // built-in zeroing semantics and the collection of initializing stores.
3761 //
3762 // While an InitializeNode is incomplete, reads from the memory state
3763 // produced by it are optimizable if they match the control edge and
3764 // new oop address associated with the allocation/initialization.
3765 // They return a stored value (if the offset matches) or else zero.
3766 // A write to the memory state, if it matches control and address,
3767 // and if it is to a constant offset, may be 'captured' by the
3768 // InitializeNode.  It is cloned as a raw memory operation and rewired
3769 // inside the initialization, to the raw oop produced by the allocation.
3770 // Operations on addresses which are provably distinct (e.g., to
3771 // other AllocateNodes) are allowed to bypass the initialization.
3772 //
3773 // The effect of all this is to consolidate object initialization
3774 // (both arrays and non-arrays, both piecewise and bulk) into a
3775 // single location, where it can be optimized as a unit.
3776 //
3777 // Only stores with an offset less than TrackedInitializationLimit words
3778 // will be considered for capture by an InitializeNode.  This puts a
3779 // reasonable limit on the complexity of optimized initializations.
3780 
3781 //---------------------------InitializeNode------------------------------------
3782 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3783   : MemBarNode(C, adr_type, rawoop),
3784     _is_complete(Incomplete), _does_not_escape(false)
3785 {
3786   init_class_id(Class_Initialize);
3787 
3788   assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3789   assert(in(RawAddress) == rawoop, "proper init");
3790   // Note:  allocation() can be NULL, for secondary initialization barriers
3791 }
3792 
3793 // Since this node is not matched, it will be processed by the
3794 // register allocator.  Declare that there are no constraints
3795 // on the allocation of the RawAddress edge.
3796 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3797   // This edge should be set to top, by the set_complete.  But be conservative.
3798   if (idx == InitializeNode::RawAddress)
3799     return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3800   return RegMask::Empty;
3801 }
3802 
3803 Node* InitializeNode::memory(uint alias_idx) {
3804   Node* mem = in(Memory);
3805   if (mem->is_MergeMem()) {
3806     return mem->as_MergeMem()->memory_at(alias_idx);
3807   } else {
3808     // incoming raw memory is not split
3809     return mem;
3810   }
3811 }
3812 
3813 bool InitializeNode::is_non_zero() {
3814   if (is_complete())  return false;
3815   remove_extra_zeroes();
3816   return (req() > RawStores);
3817 }
3818 
3819 void InitializeNode::set_complete(PhaseGVN* phase) {
3820   assert(!is_complete(), "caller responsibility");
3821   _is_complete = Complete;
3822 
3823   // After this node is complete, it contains a bunch of
3824   // raw-memory initializations.  There is no need for
3825   // it to have anything to do with non-raw memory effects.
3826   // Therefore, tell all non-raw users to re-optimize themselves,
3827   // after skipping the memory effects of this initialization.
3828   PhaseIterGVN* igvn = phase->is_IterGVN();
3829   if (igvn)  igvn->add_users_to_worklist(this);
3830 }
3831 
3832 // convenience function
3833 // return false if the init contains any stores already
3834 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3835   InitializeNode* init = initialization();
3836   if (init == NULL || init->is_complete()) {
3837     return false;
3838   }
3839   init->remove_extra_zeroes();
3840   // for now, if this allocation has already collected any inits, bail:
3841   if (init->is_non_zero())  return false;
3842   init->set_complete(phase);
3843   return true;
3844 }
3845 
3846 void InitializeNode::remove_extra_zeroes() {
3847   if (req() == RawStores)  return;
3848   Node* zmem = zero_memory();
3849   uint fill = RawStores;
3850   for (uint i = fill; i < req(); i++) {
3851     Node* n = in(i);
3852     if (n->is_top() || n == zmem)  continue;  // skip
3853     if (fill < i)  set_req(fill, n);          // compact
3854     ++fill;
3855   }
3856   // delete any empty spaces created:
3857   while (fill < req()) {
3858     del_req(fill);
3859   }
3860 }
3861 
3862 // Helper for remembering which stores go with which offsets.
3863 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3864   if (!st->is_Store())  return -1;  // can happen to dead code via subsume_node
3865   intptr_t offset = -1;
3866   Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3867                                                phase, offset);
3868   if (base == NULL)     return -1;  // something is dead,
3869   if (offset < 0)       return -1;  //        dead, dead
3870   return offset;
3871 }
3872 
3873 // Helper for proving that an initialization expression is
3874 // "simple enough" to be folded into an object initialization.
3875 // Attempts to prove that a store's initial value 'n' can be captured
3876 // within the initialization without creating a vicious cycle, such as:
3877 //     { Foo p = new Foo(); p.next = p; }
3878 // True for constants and parameters and small combinations thereof.
3879 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3880   ResourceMark rm;
3881   Unique_Node_List worklist;
3882   worklist.push(value);
3883 
3884   uint complexity_limit = 20;
3885   for (uint j = 0; j < worklist.size(); j++) {
3886     if (j >= complexity_limit) {
3887       return false;  // Bail out if processed too many nodes
3888     }
3889 
3890     Node* n = worklist.at(j);
3891     if (n == NULL)      continue;   // (can this really happen?)
3892     if (n->is_Proj())   n = n->in(0);
3893     if (n == this)      return false;  // found a cycle
3894     if (n->is_Con())    continue;
3895     if (n->is_Start())  continue;   // params, etc., are OK
3896     if (n->is_Root())   continue;   // even better
3897 
3898     // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3899     if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3900       continue;
3901     }
3902 
3903     Node* ctl = n->in(0);
3904     if (ctl != NULL && !ctl->is_top()) {
3905       if (ctl->is_Proj())  ctl = ctl->in(0);
3906       if (ctl == this)  return false;
3907 
3908       // If we already know that the enclosing memory op is pinned right after
3909       // the init, then any control flow that the store has picked up
3910       // must have preceded the init, or else be equal to the init.
3911       // Even after loop optimizations (which might change control edges)
3912       // a store is never pinned *before* the availability of its inputs.
3913       if (!MemNode::all_controls_dominate(n, this))
3914         return false;                  // failed to prove a good control
3915     }
3916 
3917     // Check data edges for possible dependencies on 'this'.
3918     for (uint i = 1; i < n->req(); i++) {
3919       Node* m = n->in(i);
3920       if (m == NULL || m == n || m->is_top())  continue;
3921 
3922       // Only process data inputs once
3923       worklist.push(m);
3924     }
3925   }
3926 
3927   return true;
3928 }
3929 
3930 // Here are all the checks a Store must pass before it can be moved into
3931 // an initialization.  Returns zero if a check fails.
3932 // On success, returns the (constant) offset to which the store applies,
3933 // within the initialized memory.
3934 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3935   const int FAIL = 0;
3936   if (st->req() != MemNode::ValueIn + 1)
3937     return FAIL;                // an inscrutable StoreNode (card mark?)
3938   Node* ctl = st->in(MemNode::Control);
3939   if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3940     return FAIL;                // must be unconditional after the initialization
3941   Node* mem = st->in(MemNode::Memory);
3942   if (!(mem->is_Proj() && mem->in(0) == this))
3943     return FAIL;                // must not be preceded by other stores
3944   Node* adr = st->in(MemNode::Address);
3945   intptr_t offset;
3946   AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3947   if (alloc == NULL)
3948     return FAIL;                // inscrutable address
3949   if (alloc != allocation())
3950     return FAIL;                // wrong allocation!  (store needs to float up)
3951   int size_in_bytes = st->memory_size();
3952   if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3953     return FAIL;                // mismatched access
3954   }
3955   Node* val = st->in(MemNode::ValueIn);
3956 
3957   if (!detect_init_independence(val, phase))
3958     return FAIL;                // stored value must be 'simple enough'
3959 
3960   // The Store can be captured only if nothing after the allocation
3961   // and before the Store is using the memory location that the store
3962   // overwrites.
3963   bool failed = false;
3964   // If is_complete_with_arraycopy() is true the shape of the graph is
3965   // well defined and is safe so no need for extra checks.
3966   if (!is_complete_with_arraycopy()) {
3967     // We are going to look at each use of the memory state following
3968     // the allocation to make sure nothing reads the memory that the
3969     // Store writes.
3970     const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3971     int alias_idx = phase->C->get_alias_index(t_adr);
3972     ResourceMark rm;
3973     Unique_Node_List mems;
3974     mems.push(mem);
3975     Node* unique_merge = NULL;
3976     for (uint next = 0; next < mems.size(); ++next) {
3977       Node *m  = mems.at(next);
3978       for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3979         Node *n = m->fast_out(j);
3980         if (n->outcnt() == 0) {
3981           continue;
3982         }
3983         if (n == st) {
3984           continue;
3985         } else if (n->in(0) != NULL && n->in(0) != ctl) {
3986           // If the control of this use is different from the control
3987           // of the Store which is right after the InitializeNode then
3988           // this node cannot be between the InitializeNode and the
3989           // Store.
3990           continue;
3991         } else if (n->is_MergeMem()) {
3992           if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3993             // We can hit a MergeMemNode (that will likely go away
3994             // later) that is a direct use of the memory state
3995             // following the InitializeNode on the same slice as the
3996             // store node that we'd like to capture. We need to check
3997             // the uses of the MergeMemNode.
3998             mems.push(n);
3999           }
4000         } else if (n->is_Mem()) {
4001           Node* other_adr = n->in(MemNode::Address);
4002           if (other_adr == adr) {
4003             failed = true;
4004             break;
4005           } else {
4006             const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4007             if (other_t_adr != NULL) {
4008               int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4009               if (other_alias_idx == alias_idx) {
4010                 // A load from the same memory slice as the store right
4011                 // after the InitializeNode. We check the control of the
4012                 // object/array that is loaded from. If it's the same as
4013                 // the store control then we cannot capture the store.
4014                 assert(!n->is_Store(), "2 stores to same slice on same control?");
4015                 Node* base = other_adr;
4016                 if (base->is_Phi()) {
4017                   // In rare case, base may be a PhiNode and it may read
4018                   // the same memory slice between InitializeNode and store.
4019                   failed = true;
4020                   break;
4021                 }
4022                 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4023                 base = base->in(AddPNode::Base);
4024                 if (base != NULL) {
4025                   base = base->uncast();
4026                   if (base->is_Proj() && base->in(0) == alloc) {
4027                     failed = true;
4028                     break;
4029                   }
4030                 }
4031               }
4032             }
4033           }
4034         } else {
4035           failed = true;
4036           break;
4037         }
4038       }
4039     }
4040   }
4041   if (failed) {
4042     if (!can_reshape) {
4043       // We decided we couldn't capture the store during parsing. We
4044       // should try again during the next IGVN once the graph is
4045       // cleaner.
4046       phase->C->record_for_igvn(st);
4047     }
4048     return FAIL;
4049   }
4050 
4051   return offset;                // success
4052 }
4053 
4054 // Find the captured store in(i) which corresponds to the range
4055 // [start..start+size) in the initialized object.
4056 // If there is one, return its index i.  If there isn't, return the
4057 // negative of the index where it should be inserted.
4058 // Return 0 if the queried range overlaps an initialization boundary
4059 // or if dead code is encountered.
4060 // If size_in_bytes is zero, do not bother with overlap checks.
4061 int InitializeNode::captured_store_insertion_point(intptr_t start,
4062                                                    int size_in_bytes,
4063                                                    PhaseTransform* phase) {
4064   const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4065 
4066   if (is_complete())
4067     return FAIL;                // arraycopy got here first; punt
4068 
4069   assert(allocation() != NULL, "must be present");
4070 
4071   // no negatives, no header fields:
4072   if (start < (intptr_t) allocation()->minimum_header_size())  return FAIL;
4073 
4074   // after a certain size, we bail out on tracking all the stores:
4075   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4076   if (start >= ti_limit)  return FAIL;
4077 
4078   for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4079     if (i >= limit)  return -(int)i; // not found; here is where to put it
4080 
4081     Node*    st     = in(i);
4082     intptr_t st_off = get_store_offset(st, phase);
4083     if (st_off < 0) {
4084       if (st != zero_memory()) {
4085         return FAIL;            // bail out if there is dead garbage
4086       }
4087     } else if (st_off > start) {
4088       // ...we are done, since stores are ordered
4089       if (st_off < start + size_in_bytes) {
4090         return FAIL;            // the next store overlaps
4091       }
4092       return -(int)i;           // not found; here is where to put it
4093     } else if (st_off < start) {
4094       assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4095       if (size_in_bytes != 0 &&
4096           start < st_off + MAX_STORE &&
4097           start < st_off + st->as_Store()->memory_size()) {
4098         return FAIL;            // the previous store overlaps
4099       }
4100     } else {
4101       if (size_in_bytes != 0 &&
4102           st->as_Store()->memory_size() != size_in_bytes) {
4103         return FAIL;            // mismatched store size
4104       }
4105       return i;
4106     }
4107 
4108     ++i;
4109   }
4110 }
4111 
4112 // Look for a captured store which initializes at the offset 'start'
4113 // with the given size.  If there is no such store, and no other
4114 // initialization interferes, then return zero_memory (the memory
4115 // projection of the AllocateNode).
4116 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4117                                           PhaseTransform* phase) {
4118   assert(stores_are_sane(phase), "");
4119   int i = captured_store_insertion_point(start, size_in_bytes, phase);
4120   if (i == 0) {
4121     return NULL;                // something is dead
4122   } else if (i < 0) {
4123     return zero_memory();       // just primordial zero bits here
4124   } else {
4125     Node* st = in(i);           // here is the store at this position
4126     assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4127     return st;
4128   }
4129 }
4130 
4131 // Create, as a raw pointer, an address within my new object at 'offset'.
4132 Node* InitializeNode::make_raw_address(intptr_t offset,
4133                                        PhaseTransform* phase) {
4134   Node* addr = in(RawAddress);
4135   if (offset != 0) {
4136     Compile* C = phase->C;
4137     addr = phase->transform( new AddPNode(C->top(), addr,
4138                                                  phase->MakeConX(offset)) );
4139   }
4140   return addr;
4141 }
4142 
4143 // Clone the given store, converting it into a raw store
4144 // initializing a field or element of my new object.
4145 // Caller is responsible for retiring the original store,
4146 // with subsume_node or the like.
4147 //
4148 // From the example above InitializeNode::InitializeNode,
4149 // here are the old stores to be captured:
4150 //   store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4151 //   store2 = (StoreC init.Control store1      (+ oop 14) 2)
4152 //
4153 // Here is the changed code; note the extra edges on init:
4154 //   alloc = (Allocate ...)
4155 //   rawoop = alloc.RawAddress
4156 //   rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4157 //   rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4158 //   init = (Initialize alloc.Control alloc.Memory rawoop
4159 //                      rawstore1 rawstore2)
4160 //
4161 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4162                                     PhaseGVN* phase, bool can_reshape) {
4163   assert(stores_are_sane(phase), "");
4164 
4165   if (start < 0)  return NULL;
4166   assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4167 
4168   Compile* C = phase->C;
4169   int size_in_bytes = st->memory_size();
4170   int i = captured_store_insertion_point(start, size_in_bytes, phase);
4171   if (i == 0)  return NULL;     // bail out
4172   Node* prev_mem = NULL;        // raw memory for the captured store
4173   if (i > 0) {
4174     prev_mem = in(i);           // there is a pre-existing store under this one
4175     set_req(i, C->top());       // temporarily disconnect it
4176     // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4177   } else {
4178     i = -i;                     // no pre-existing store
4179     prev_mem = zero_memory();   // a slice of the newly allocated object
4180     if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4181       set_req(--i, C->top());   // reuse this edge; it has been folded away
4182     else
4183       ins_req(i, C->top());     // build a new edge
4184   }
4185   Node* new_st = st->clone();
4186   new_st->set_req(MemNode::Control, in(Control));
4187   new_st->set_req(MemNode::Memory,  prev_mem);
4188   new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4189   new_st = phase->transform(new_st);
4190 
4191   // At this point, new_st might have swallowed a pre-existing store
4192   // at the same offset, or perhaps new_st might have disappeared,
4193   // if it redundantly stored the same value (or zero to fresh memory).
4194 
4195   // In any case, wire it in:
4196   PhaseIterGVN* igvn = phase->is_IterGVN();
4197   if (igvn) {
4198     igvn->rehash_node_delayed(this);
4199   }
4200   set_req(i, new_st);
4201 
4202   // The caller may now kill the old guy.
4203   DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4204   assert(check_st == new_st || check_st == NULL, "must be findable");
4205   assert(!is_complete(), "");
4206   return new_st;
4207 }
4208 
4209 static bool store_constant(jlong* tiles, int num_tiles,
4210                            intptr_t st_off, int st_size,
4211                            jlong con) {
4212   if ((st_off & (st_size-1)) != 0)
4213     return false;               // strange store offset (assume size==2**N)
4214   address addr = (address)tiles + st_off;
4215   assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4216   switch (st_size) {
4217   case sizeof(jbyte):  *(jbyte*) addr = (jbyte) con; break;
4218   case sizeof(jchar):  *(jchar*) addr = (jchar) con; break;
4219   case sizeof(jint):   *(jint*)  addr = (jint)  con; break;
4220   case sizeof(jlong):  *(jlong*) addr = (jlong) con; break;
4221   default: return false;        // strange store size (detect size!=2**N here)
4222   }
4223   return true;                  // return success to caller
4224 }
4225 
4226 // Coalesce subword constants into int constants and possibly
4227 // into long constants.  The goal, if the CPU permits,
4228 // is to initialize the object with a small number of 64-bit tiles.
4229 // Also, convert floating-point constants to bit patterns.
4230 // Non-constants are not relevant to this pass.
4231 //
4232 // In terms of the running example on InitializeNode::InitializeNode
4233 // and InitializeNode::capture_store, here is the transformation
4234 // of rawstore1 and rawstore2 into rawstore12:
4235 //   alloc = (Allocate ...)
4236 //   rawoop = alloc.RawAddress
4237 //   tile12 = 0x00010002
4238 //   rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4239 //   init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4240 //
4241 void
4242 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4243                                         Node* size_in_bytes,
4244                                         PhaseGVN* phase) {
4245   Compile* C = phase->C;
4246 
4247   assert(stores_are_sane(phase), "");
4248   // Note:  After this pass, they are not completely sane,
4249   // since there may be some overlaps.
4250 
4251   int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4252 
4253   intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4254   intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4255   size_limit = MIN2(size_limit, ti_limit);
4256   size_limit = align_up(size_limit, BytesPerLong);
4257   int num_tiles = size_limit / BytesPerLong;
4258 
4259   // allocate space for the tile map:
4260   const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4261   jlong  tiles_buf[small_len];
4262   Node*  nodes_buf[small_len];
4263   jlong  inits_buf[small_len];
4264   jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4265                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4266   Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4267                   : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4268   jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4269                   : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4270   // tiles: exact bitwise model of all primitive constants
4271   // nodes: last constant-storing node subsumed into the tiles model
4272   // inits: which bytes (in each tile) are touched by any initializations
4273 
4274   //// Pass A: Fill in the tile model with any relevant stores.
4275 
4276   Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4277   Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4278   Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4279   Node* zmem = zero_memory(); // initially zero memory state
4280   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4281     Node* st = in(i);
4282     intptr_t st_off = get_store_offset(st, phase);
4283 
4284     // Figure out the store's offset and constant value:
4285     if (st_off < header_size)             continue; //skip (ignore header)
4286     if (st->in(MemNode::Memory) != zmem)  continue; //skip (odd store chain)
4287     int st_size = st->as_Store()->memory_size();
4288     if (st_off + st_size > size_limit)    break;
4289 
4290     // Record which bytes are touched, whether by constant or not.
4291     if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4292       continue;                 // skip (strange store size)
4293 
4294     const Type* val = phase->type(st->in(MemNode::ValueIn));
4295     if (!val->singleton())                continue; //skip (non-con store)
4296     BasicType type = val->basic_type();
4297 
4298     jlong con = 0;
4299     switch (type) {
4300     case T_INT:    con = val->is_int()->get_con();  break;
4301     case T_LONG:   con = val->is_long()->get_con(); break;
4302     case T_FLOAT:  con = jint_cast(val->getf());    break;
4303     case T_DOUBLE: con = jlong_cast(val->getd());   break;
4304     default:                              continue; //skip (odd store type)
4305     }
4306 
4307     if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4308         st->Opcode() == Op_StoreL) {
4309       continue;                 // This StoreL is already optimal.
4310     }
4311 
4312     // Store down the constant.
4313     store_constant(tiles, num_tiles, st_off, st_size, con);
4314 
4315     intptr_t j = st_off >> LogBytesPerLong;
4316 
4317     if (type == T_INT && st_size == BytesPerInt
4318         && (st_off & BytesPerInt) == BytesPerInt) {
4319       jlong lcon = tiles[j];
4320       if (!Matcher::isSimpleConstant64(lcon) &&
4321           st->Opcode() == Op_StoreI) {
4322         // This StoreI is already optimal by itself.
4323         jint* intcon = (jint*) &tiles[j];
4324         intcon[1] = 0;  // undo the store_constant()
4325 
4326         // If the previous store is also optimal by itself, back up and
4327         // undo the action of the previous loop iteration... if we can.
4328         // But if we can't, just let the previous half take care of itself.
4329         st = nodes[j];
4330         st_off -= BytesPerInt;
4331         con = intcon[0];
4332         if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4333           assert(st_off >= header_size, "still ignoring header");
4334           assert(get_store_offset(st, phase) == st_off, "must be");
4335           assert(in(i-1) == zmem, "must be");
4336           DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4337           assert(con == tcon->is_int()->get_con(), "must be");
4338           // Undo the effects of the previous loop trip, which swallowed st:
4339           intcon[0] = 0;        // undo store_constant()
4340           set_req(i-1, st);     // undo set_req(i, zmem)
4341           nodes[j] = NULL;      // undo nodes[j] = st
4342           --old_subword;        // undo ++old_subword
4343         }
4344         continue;               // This StoreI is already optimal.
4345       }
4346     }
4347 
4348     // This store is not needed.
4349     set_req(i, zmem);
4350     nodes[j] = st;              // record for the moment
4351     if (st_size < BytesPerLong) // something has changed
4352           ++old_subword;        // includes int/float, but who's counting...
4353     else  ++old_long;
4354   }
4355 
4356   if ((old_subword + old_long) == 0)
4357     return;                     // nothing more to do
4358 
4359   //// Pass B: Convert any non-zero tiles into optimal constant stores.
4360   // Be sure to insert them before overlapping non-constant stores.
4361   // (E.g., byte[] x = { 1,2,y,4 }  =>  x[int 0] = 0x01020004, x[2]=y.)
4362   for (int j = 0; j < num_tiles; j++) {
4363     jlong con  = tiles[j];
4364     jlong init = inits[j];
4365     if (con == 0)  continue;
4366     jint con0,  con1;           // split the constant, address-wise
4367     jint init0, init1;          // split the init map, address-wise
4368     { union { jlong con; jint intcon[2]; } u;
4369       u.con = con;
4370       con0  = u.intcon[0];
4371       con1  = u.intcon[1];
4372       u.con = init;
4373       init0 = u.intcon[0];
4374       init1 = u.intcon[1];
4375     }
4376 
4377     Node* old = nodes[j];
4378     assert(old != NULL, "need the prior store");
4379     intptr_t offset = (j * BytesPerLong);
4380 
4381     bool split = !Matcher::isSimpleConstant64(con);
4382 
4383     if (offset < header_size) {
4384       assert(offset + BytesPerInt >= header_size, "second int counts");
4385       assert(*(jint*)&tiles[j] == 0, "junk in header");
4386       split = true;             // only the second word counts
4387       // Example:  int a[] = { 42 ... }
4388     } else if (con0 == 0 && init0 == -1) {
4389       split = true;             // first word is covered by full inits
4390       // Example:  int a[] = { ... foo(), 42 ... }
4391     } else if (con1 == 0 && init1 == -1) {
4392       split = true;             // second word is covered by full inits
4393       // Example:  int a[] = { ... 42, foo() ... }
4394     }
4395 
4396     // Here's a case where init0 is neither 0 nor -1:
4397     //   byte a[] = { ... 0,0,foo(),0,  0,0,0,42 ... }
4398     // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4399     // In this case the tile is not split; it is (jlong)42.
4400     // The big tile is stored down, and then the foo() value is inserted.
4401     // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4402 
4403     Node* ctl = old->in(MemNode::Control);
4404     Node* adr = make_raw_address(offset, phase);
4405     const TypePtr* atp = TypeRawPtr::BOTTOM;
4406 
4407     // One or two coalesced stores to plop down.
4408     Node*    st[2];
4409     intptr_t off[2];
4410     int  nst = 0;
4411     if (!split) {
4412       ++new_long;
4413       off[nst] = offset;
4414       st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4415                                   phase->longcon(con), T_LONG, MemNode::unordered);
4416     } else {
4417       // Omit either if it is a zero.
4418       if (con0 != 0) {
4419         ++new_int;
4420         off[nst]  = offset;
4421         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4422                                     phase->intcon(con0), T_INT, MemNode::unordered);
4423       }
4424       if (con1 != 0) {
4425         ++new_int;
4426         offset += BytesPerInt;
4427         adr = make_raw_address(offset, phase);
4428         off[nst]  = offset;
4429         st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4430                                     phase->intcon(con1), T_INT, MemNode::unordered);
4431       }
4432     }
4433 
4434     // Insert second store first, then the first before the second.
4435     // Insert each one just before any overlapping non-constant stores.
4436     while (nst > 0) {
4437       Node* st1 = st[--nst];
4438       C->copy_node_notes_to(st1, old);
4439       st1 = phase->transform(st1);
4440       offset = off[nst];
4441       assert(offset >= header_size, "do not smash header");
4442       int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4443       guarantee(ins_idx != 0, "must re-insert constant store");
4444       if (ins_idx < 0)  ins_idx = -ins_idx;  // never overlap
4445       if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4446         set_req(--ins_idx, st1);
4447       else
4448         ins_req(ins_idx, st1);
4449     }
4450   }
4451 
4452   if (PrintCompilation && WizardMode)
4453     tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4454                   old_subword, old_long, new_int, new_long);
4455   if (C->log() != NULL)
4456     C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4457                    old_subword, old_long, new_int, new_long);
4458 
4459   // Clean up any remaining occurrences of zmem:
4460   remove_extra_zeroes();
4461 }
4462 
4463 // Explore forward from in(start) to find the first fully initialized
4464 // word, and return its offset.  Skip groups of subword stores which
4465 // together initialize full words.  If in(start) is itself part of a
4466 // fully initialized word, return the offset of in(start).  If there
4467 // are no following full-word stores, or if something is fishy, return
4468 // a negative value.
4469 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4470   int       int_map = 0;
4471   intptr_t  int_map_off = 0;
4472   const int FULL_MAP = right_n_bits(BytesPerInt);  // the int_map we hope for
4473 
4474   for (uint i = start, limit = req(); i < limit; i++) {
4475     Node* st = in(i);
4476 
4477     intptr_t st_off = get_store_offset(st, phase);
4478     if (st_off < 0)  break;  // return conservative answer
4479 
4480     int st_size = st->as_Store()->memory_size();
4481     if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4482       return st_off;            // we found a complete word init
4483     }
4484 
4485     // update the map:
4486 
4487     intptr_t this_int_off = align_down(st_off, BytesPerInt);
4488     if (this_int_off != int_map_off) {
4489       // reset the map:
4490       int_map = 0;
4491       int_map_off = this_int_off;
4492     }
4493 
4494     int subword_off = st_off - this_int_off;
4495     int_map |= right_n_bits(st_size) << subword_off;
4496     if ((int_map & FULL_MAP) == FULL_MAP) {
4497       return this_int_off;      // we found a complete word init
4498     }
4499 
4500     // Did this store hit or cross the word boundary?
4501     intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4502     if (next_int_off == this_int_off + BytesPerInt) {
4503       // We passed the current int, without fully initializing it.
4504       int_map_off = next_int_off;
4505       int_map >>= BytesPerInt;
4506     } else if (next_int_off > this_int_off + BytesPerInt) {
4507       // We passed the current and next int.
4508       return this_int_off + BytesPerInt;
4509     }
4510   }
4511 
4512   return -1;
4513 }
4514 
4515 
4516 // Called when the associated AllocateNode is expanded into CFG.
4517 // At this point, we may perform additional optimizations.
4518 // Linearize the stores by ascending offset, to make memory
4519 // activity as coherent as possible.
4520 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4521                                       intptr_t header_size,
4522                                       Node* size_in_bytes,
4523                                       PhaseIterGVN* phase) {
4524   assert(!is_complete(), "not already complete");
4525   assert(stores_are_sane(phase), "");
4526   assert(allocation() != NULL, "must be present");
4527 
4528   remove_extra_zeroes();
4529 
4530   if (ReduceFieldZeroing || ReduceBulkZeroing)
4531     // reduce instruction count for common initialization patterns
4532     coalesce_subword_stores(header_size, size_in_bytes, phase);
4533 
4534   Node* zmem = zero_memory();   // initially zero memory state
4535   Node* inits = zmem;           // accumulating a linearized chain of inits
4536   #ifdef ASSERT
4537   intptr_t first_offset = allocation()->minimum_header_size();
4538   intptr_t last_init_off = first_offset;  // previous init offset
4539   intptr_t last_init_end = first_offset;  // previous init offset+size
4540   intptr_t last_tile_end = first_offset;  // previous tile offset+size
4541   #endif
4542   intptr_t zeroes_done = header_size;
4543 
4544   bool do_zeroing = true;       // we might give up if inits are very sparse
4545   int  big_init_gaps = 0;       // how many large gaps have we seen?
4546 
4547   if (UseTLAB && ZeroTLAB)  do_zeroing = false;
4548   if (!ReduceFieldZeroing && !ReduceBulkZeroing)  do_zeroing = false;
4549 
4550   for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4551     Node* st = in(i);
4552     intptr_t st_off = get_store_offset(st, phase);
4553     if (st_off < 0)
4554       break;                    // unknown junk in the inits
4555     if (st->in(MemNode::Memory) != zmem)
4556       break;                    // complicated store chains somehow in list
4557 
4558     int st_size = st->as_Store()->memory_size();
4559     intptr_t next_init_off = st_off + st_size;
4560 
4561     if (do_zeroing && zeroes_done < next_init_off) {
4562       // See if this store needs a zero before it or under it.
4563       intptr_t zeroes_needed = st_off;
4564 
4565       if (st_size < BytesPerInt) {
4566         // Look for subword stores which only partially initialize words.
4567         // If we find some, we must lay down some word-level zeroes first,
4568         // underneath the subword stores.
4569         //
4570         // Examples:
4571         //   byte[] a = { p,q,r,s }  =>  a[0]=p,a[1]=q,a[2]=r,a[3]=s
4572         //   byte[] a = { x,y,0,0 }  =>  a[0..3] = 0, a[0]=x,a[1]=y
4573         //   byte[] a = { 0,0,z,0 }  =>  a[0..3] = 0, a[2]=z
4574         //
4575         // Note:  coalesce_subword_stores may have already done this,
4576         // if it was prompted by constant non-zero subword initializers.
4577         // But this case can still arise with non-constant stores.
4578 
4579         intptr_t next_full_store = find_next_fullword_store(i, phase);
4580 
4581         // In the examples above:
4582         //   in(i)          p   q   r   s     x   y     z
4583         //   st_off        12  13  14  15    12  13    14
4584         //   st_size        1   1   1   1     1   1     1
4585         //   next_full_s.  12  16  16  16    16  16    16
4586         //   z's_done      12  16  16  16    12  16    12
4587         //   z's_needed    12  16  16  16    16  16    16
4588         //   zsize          0   0   0   0     4   0     4
4589         if (next_full_store < 0) {
4590           // Conservative tack:  Zero to end of current word.
4591           zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4592         } else {
4593           // Zero to beginning of next fully initialized word.
4594           // Or, don't zero at all, if we are already in that word.
4595           assert(next_full_store >= zeroes_needed, "must go forward");
4596           assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4597           zeroes_needed = next_full_store;
4598         }
4599       }
4600 
4601       if (zeroes_needed > zeroes_done) {
4602         intptr_t zsize = zeroes_needed - zeroes_done;
4603         // Do some incremental zeroing on rawmem, in parallel with inits.
4604         zeroes_done = align_down(zeroes_done, BytesPerInt);
4605         rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4606                                               allocation()->in(AllocateNode::DefaultValue),
4607                                               allocation()->in(AllocateNode::RawDefaultValue),
4608                                               zeroes_done, zeroes_needed,
4609                                               phase);
4610         zeroes_done = zeroes_needed;
4611         if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4612           do_zeroing = false;   // leave the hole, next time
4613       }
4614     }
4615 
4616     // Collect the store and move on:
4617     phase->replace_input_of(st, MemNode::Memory, inits);
4618     inits = st;                 // put it on the linearized chain
4619     set_req(i, zmem);           // unhook from previous position
4620 
4621     if (zeroes_done == st_off)
4622       zeroes_done = next_init_off;
4623 
4624     assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4625 
4626     #ifdef ASSERT
4627     // Various order invariants.  Weaker than stores_are_sane because
4628     // a large constant tile can be filled in by smaller non-constant stores.
4629     assert(st_off >= last_init_off, "inits do not reverse");
4630     last_init_off = st_off;
4631     const Type* val = NULL;
4632     if (st_size >= BytesPerInt &&
4633         (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4634         (int)val->basic_type() < (int)T_OBJECT) {
4635       assert(st_off >= last_tile_end, "tiles do not overlap");
4636       assert(st_off >= last_init_end, "tiles do not overwrite inits");
4637       last_tile_end = MAX2(last_tile_end, next_init_off);
4638     } else {
4639       intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4640       assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4641       assert(st_off      >= last_init_end, "inits do not overlap");
4642       last_init_end = next_init_off;  // it's a non-tile
4643     }
4644     #endif //ASSERT
4645   }
4646 
4647   remove_extra_zeroes();        // clear out all the zmems left over
4648   add_req(inits);
4649 
4650   if (!(UseTLAB && ZeroTLAB)) {
4651     // If anything remains to be zeroed, zero it all now.
4652     zeroes_done = align_down(zeroes_done, BytesPerInt);
4653     // if it is the last unused 4 bytes of an instance, forget about it
4654     intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4655     if (zeroes_done + BytesPerLong >= size_limit) {
4656       AllocateNode* alloc = allocation();
4657       assert(alloc != NULL, "must be present");
4658       if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4659         Node* klass_node = alloc->in(AllocateNode::KlassNode);
4660         ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4661         if (zeroes_done == k->layout_helper())
4662           zeroes_done = size_limit;
4663       }
4664     }
4665     if (zeroes_done < size_limit) {
4666       rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4667                                             allocation()->in(AllocateNode::DefaultValue),
4668                                             allocation()->in(AllocateNode::RawDefaultValue),
4669                                             zeroes_done, size_in_bytes, phase);
4670     }
4671   }
4672 
4673   set_complete(phase);
4674   return rawmem;
4675 }
4676 
4677 
4678 #ifdef ASSERT
4679 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4680   if (is_complete())
4681     return true;                // stores could be anything at this point
4682   assert(allocation() != NULL, "must be present");
4683   intptr_t last_off = allocation()->minimum_header_size();
4684   for (uint i = InitializeNode::RawStores; i < req(); i++) {
4685     Node* st = in(i);
4686     intptr_t st_off = get_store_offset(st, phase);
4687     if (st_off < 0)  continue;  // ignore dead garbage
4688     if (last_off > st_off) {
4689       tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4690       this->dump(2);
4691       assert(false, "ascending store offsets");
4692       return false;
4693     }
4694     last_off = st_off + st->as_Store()->memory_size();
4695   }
4696   return true;
4697 }
4698 #endif //ASSERT
4699 
4700 
4701 
4702 
4703 //============================MergeMemNode=====================================
4704 //
4705 // SEMANTICS OF MEMORY MERGES:  A MergeMem is a memory state assembled from several
4706 // contributing store or call operations.  Each contributor provides the memory
4707 // state for a particular "alias type" (see Compile::alias_type).  For example,
4708 // if a MergeMem has an input X for alias category #6, then any memory reference
4709 // to alias category #6 may use X as its memory state input, as an exact equivalent
4710 // to using the MergeMem as a whole.
4711 //   Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4712 //
4713 // (Here, the <N> notation gives the index of the relevant adr_type.)
4714 //
4715 // In one special case (and more cases in the future), alias categories overlap.
4716 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4717 // states.  Therefore, if a MergeMem has only one contributing input W for Bot,
4718 // it is exactly equivalent to that state W:
4719 //   MergeMem(<Bot>: W) <==> W
4720 //
4721 // Usually, the merge has more than one input.  In that case, where inputs
4722 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4723 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4724 //   Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4725 //   Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4726 //
4727 // A merge can take a "wide" memory state as one of its narrow inputs.
4728 // This simply means that the merge observes out only the relevant parts of
4729 // the wide input.  That is, wide memory states arriving at narrow merge inputs
4730 // are implicitly "filtered" or "sliced" as necessary.  (This is rare.)
4731 //
4732 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4733 // and that memory slices "leak through":
4734 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4735 //
4736 // But, in such a cascade, repeated memory slices can "block the leak":
4737 //   MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4738 //
4739 // In the last example, Y is not part of the combined memory state of the
4740 // outermost MergeMem.  The system must, of course, prevent unschedulable
4741 // memory states from arising, so you can be sure that the state Y is somehow
4742 // a precursor to state Y'.
4743 //
4744 //
4745 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4746 // of each MergeMemNode array are exactly the numerical alias indexes, including
4747 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw.  The functions
4748 // Compile::alias_type (and kin) produce and manage these indexes.
4749 //
4750 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4751 // (Note that this provides quick access to the top node inside MergeMem methods,
4752 // without the need to reach out via TLS to Compile::current.)
4753 //
4754 // As a consequence of what was just described, a MergeMem that represents a full
4755 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4756 // containing all alias categories.
4757 //
4758 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4759 //
4760 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4761 // a memory state for the alias type <N>, or else the top node, meaning that
4762 // there is no particular input for that alias type.  Note that the length of
4763 // a MergeMem is variable, and may be extended at any time to accommodate new
4764 // memory states at larger alias indexes.  When merges grow, they are of course
4765 // filled with "top" in the unused in() positions.
4766 //
4767 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4768 // (Top was chosen because it works smoothly with passes like GCM.)
4769 //
4770 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM.  (It is
4771 // the type of random VM bits like TLS references.)  Since it is always the
4772 // first non-Bot memory slice, some low-level loops use it to initialize an
4773 // index variable:  for (i = AliasIdxRaw; i < req(); i++).
4774 //
4775 //
4776 // ACCESSORS:  There is a special accessor MergeMemNode::base_memory which returns
4777 // the distinguished "wide" state.  The accessor MergeMemNode::memory_at(N) returns
4778 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4779 // it returns the base memory.  To prevent bugs, memory_at does not accept <Top>
4780 // or <Bot> indexes.  The iterator MergeMemStream provides robust iteration over
4781 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4782 //
4783 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4784 // really that different from the other memory inputs.  An abbreviation called
4785 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4786 //
4787 //
4788 // PARTIAL MEMORY STATES:  During optimization, MergeMem nodes may arise that represent
4789 // partial memory states.  When a Phi splits through a MergeMem, the copy of the Phi
4790 // that "emerges though" the base memory will be marked as excluding the alias types
4791 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4792 //
4793 //   Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4794 //     ==Ideal=>  MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4795 //
4796 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4797 // (It is currently unimplemented.)  As you can see, the resulting merge is
4798 // actually a disjoint union of memory states, rather than an overlay.
4799 //
4800 
4801 //------------------------------MergeMemNode-----------------------------------
4802 Node* MergeMemNode::make_empty_memory() {
4803   Node* empty_memory = (Node*) Compile::current()->top();
4804   assert(empty_memory->is_top(), "correct sentinel identity");
4805   return empty_memory;
4806 }
4807 
4808 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4809   init_class_id(Class_MergeMem);
4810   // all inputs are nullified in Node::Node(int)
4811   // set_input(0, NULL);  // no control input
4812 
4813   // Initialize the edges uniformly to top, for starters.
4814   Node* empty_mem = make_empty_memory();
4815   for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4816     init_req(i,empty_mem);
4817   }
4818   assert(empty_memory() == empty_mem, "");
4819 
4820   if( new_base != NULL && new_base->is_MergeMem() ) {
4821     MergeMemNode* mdef = new_base->as_MergeMem();
4822     assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4823     for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4824       mms.set_memory(mms.memory2());
4825     }
4826     assert(base_memory() == mdef->base_memory(), "");
4827   } else {
4828     set_base_memory(new_base);
4829   }
4830 }
4831 
4832 // Make a new, untransformed MergeMem with the same base as 'mem'.
4833 // If mem is itself a MergeMem, populate the result with the same edges.
4834 MergeMemNode* MergeMemNode::make(Node* mem) {
4835   return new MergeMemNode(mem);
4836 }
4837 
4838 //------------------------------cmp--------------------------------------------
4839 uint MergeMemNode::hash() const { return NO_HASH; }
4840 bool MergeMemNode::cmp( const Node &n ) const {
4841   return (&n == this);          // Always fail except on self
4842 }
4843 
4844 //------------------------------Identity---------------------------------------
4845 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4846   // Identity if this merge point does not record any interesting memory
4847   // disambiguations.
4848   Node* base_mem = base_memory();
4849   Node* empty_mem = empty_memory();
4850   if (base_mem != empty_mem) {  // Memory path is not dead?
4851     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4852       Node* mem = in(i);
4853       if (mem != empty_mem && mem != base_mem) {
4854         return this;            // Many memory splits; no change
4855       }
4856     }
4857   }
4858   return base_mem;              // No memory splits; ID on the one true input
4859 }
4860 
4861 //------------------------------Ideal------------------------------------------
4862 // This method is invoked recursively on chains of MergeMem nodes
4863 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4864   // Remove chain'd MergeMems
4865   //
4866   // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4867   // relative to the "in(Bot)".  Since we are patching both at the same time,
4868   // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4869   // but rewrite each "in(i)" relative to the new "in(Bot)".
4870   Node *progress = NULL;
4871 
4872 
4873   Node* old_base = base_memory();
4874   Node* empty_mem = empty_memory();
4875   if (old_base == empty_mem)
4876     return NULL; // Dead memory path.
4877 
4878   MergeMemNode* old_mbase;
4879   if (old_base != NULL && old_base->is_MergeMem())
4880     old_mbase = old_base->as_MergeMem();
4881   else
4882     old_mbase = NULL;
4883   Node* new_base = old_base;
4884 
4885   // simplify stacked MergeMems in base memory
4886   if (old_mbase)  new_base = old_mbase->base_memory();
4887 
4888   // the base memory might contribute new slices beyond my req()
4889   if (old_mbase)  grow_to_match(old_mbase);
4890 
4891   // Note:  We do not call verify_sparse on entry, because inputs
4892   // can normalize to the base_memory via subsume_node or similar
4893   // mechanisms.  This method repairs that damage.
4894 
4895   assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4896 
4897   // Look at each slice.
4898   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4899     Node* old_in = in(i);
4900     // calculate the old memory value
4901     Node* old_mem = old_in;
4902     if (old_mem == empty_mem)  old_mem = old_base;
4903     assert(old_mem == memory_at(i), "");
4904 
4905     // maybe update (reslice) the old memory value
4906 
4907     // simplify stacked MergeMems
4908     Node* new_mem = old_mem;
4909     MergeMemNode* old_mmem;
4910     if (old_mem != NULL && old_mem->is_MergeMem())
4911       old_mmem = old_mem->as_MergeMem();
4912     else
4913       old_mmem = NULL;
4914     if (old_mmem == this) {
4915       // This can happen if loops break up and safepoints disappear.
4916       // A merge of BotPtr (default) with a RawPtr memory derived from a
4917       // safepoint can be rewritten to a merge of the same BotPtr with
4918       // the BotPtr phi coming into the loop.  If that phi disappears
4919       // also, we can end up with a self-loop of the mergemem.
4920       // In general, if loops degenerate and memory effects disappear,
4921       // a mergemem can be left looking at itself.  This simply means
4922       // that the mergemem's default should be used, since there is
4923       // no longer any apparent effect on this slice.
4924       // Note: If a memory slice is a MergeMem cycle, it is unreachable
4925       //       from start.  Update the input to TOP.
4926       new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4927     }
4928     else if (old_mmem != NULL) {
4929       new_mem = old_mmem->memory_at(i);
4930     }
4931     // else preceding memory was not a MergeMem
4932 
4933     // maybe store down a new value
4934     Node* new_in = new_mem;
4935     if (new_in == new_base)  new_in = empty_mem;
4936 
4937     if (new_in != old_in) {
4938       // Warning:  Do not combine this "if" with the previous "if"
4939       // A memory slice might have be be rewritten even if it is semantically
4940       // unchanged, if the base_memory value has changed.
4941       set_req_X(i, new_in, phase);
4942       progress = this;          // Report progress
4943     }
4944   }
4945 
4946   if (new_base != old_base) {
4947     set_req_X(Compile::AliasIdxBot, new_base, phase);
4948     // Don't use set_base_memory(new_base), because we need to update du.
4949     assert(base_memory() == new_base, "");
4950     progress = this;
4951   }
4952 
4953   if( base_memory() == this ) {
4954     // a self cycle indicates this memory path is dead
4955     set_req(Compile::AliasIdxBot, empty_mem);
4956   }
4957 
4958   // Resolve external cycles by calling Ideal on a MergeMem base_memory
4959   // Recursion must occur after the self cycle check above
4960   if( base_memory()->is_MergeMem() ) {
4961     MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4962     Node *m = phase->transform(new_mbase);  // Rollup any cycles
4963     if( m != NULL &&
4964         (m->is_top() ||
4965          (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4966       // propagate rollup of dead cycle to self
4967       set_req(Compile::AliasIdxBot, empty_mem);
4968     }
4969   }
4970 
4971   if( base_memory() == empty_mem ) {
4972     progress = this;
4973     // Cut inputs during Parse phase only.
4974     // During Optimize phase a dead MergeMem node will be subsumed by Top.
4975     if( !can_reshape ) {
4976       for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4977         if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4978       }
4979     }
4980   }
4981 
4982   if( !progress && base_memory()->is_Phi() && can_reshape ) {
4983     // Check if PhiNode::Ideal's "Split phis through memory merges"
4984     // transform should be attempted. Look for this->phi->this cycle.
4985     uint merge_width = req();
4986     if (merge_width > Compile::AliasIdxRaw) {
4987       PhiNode* phi = base_memory()->as_Phi();
4988       for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4989         if (phi->in(i) == this) {
4990           phase->is_IterGVN()->_worklist.push(phi);
4991           break;
4992         }
4993       }
4994     }
4995   }
4996 
4997   assert(progress || verify_sparse(), "please, no dups of base");
4998   return progress;
4999 }
5000 
5001 //-------------------------set_base_memory-------------------------------------
5002 void MergeMemNode::set_base_memory(Node *new_base) {
5003   Node* empty_mem = empty_memory();
5004   set_req(Compile::AliasIdxBot, new_base);
5005   assert(memory_at(req()) == new_base, "must set default memory");
5006   // Clear out other occurrences of new_base:
5007   if (new_base != empty_mem) {
5008     for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5009       if (in(i) == new_base)  set_req(i, empty_mem);
5010     }
5011   }
5012 }
5013 
5014 //------------------------------out_RegMask------------------------------------
5015 const RegMask &MergeMemNode::out_RegMask() const {
5016   return RegMask::Empty;
5017 }
5018 
5019 //------------------------------dump_spec--------------------------------------
5020 #ifndef PRODUCT
5021 void MergeMemNode::dump_spec(outputStream *st) const {
5022   st->print(" {");
5023   Node* base_mem = base_memory();
5024   for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5025     Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
5026     if (mem == base_mem) { st->print(" -"); continue; }
5027     st->print( " N%d:", mem->_idx );
5028     Compile::current()->get_adr_type(i)->dump_on(st);
5029   }
5030   st->print(" }");
5031 }
5032 #endif // !PRODUCT
5033 
5034 
5035 #ifdef ASSERT
5036 static bool might_be_same(Node* a, Node* b) {
5037   if (a == b)  return true;
5038   if (!(a->is_Phi() || b->is_Phi()))  return false;
5039   // phis shift around during optimization
5040   return true;  // pretty stupid...
5041 }
5042 
5043 // verify a narrow slice (either incoming or outgoing)
5044 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5045   if (!VerifyAliases)                return;  // don't bother to verify unless requested
5046   if (VMError::is_error_reported())  return;  // muzzle asserts when debugging an error
5047   if (Node::in_dump())               return;  // muzzle asserts when printing
5048   assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5049   assert(n != NULL, "");
5050   // Elide intervening MergeMem's
5051   while (n->is_MergeMem()) {
5052     n = n->as_MergeMem()->memory_at(alias_idx);
5053   }
5054   Compile* C = Compile::current();
5055   const TypePtr* n_adr_type = n->adr_type();
5056   if (n == m->empty_memory()) {
5057     // Implicit copy of base_memory()
5058   } else if (n_adr_type != TypePtr::BOTTOM) {
5059     assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
5060     assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5061   } else {
5062     // A few places like make_runtime_call "know" that VM calls are narrow,
5063     // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5064     bool expected_wide_mem = false;
5065     if (n == m->base_memory()) {
5066       expected_wide_mem = true;
5067     } else if (alias_idx == Compile::AliasIdxRaw ||
5068                n == m->memory_at(Compile::AliasIdxRaw)) {
5069       expected_wide_mem = true;
5070     } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5071       // memory can "leak through" calls on channels that
5072       // are write-once.  Allow this also.
5073       expected_wide_mem = true;
5074     }
5075     assert(expected_wide_mem, "expected narrow slice replacement");
5076   }
5077 }
5078 #else // !ASSERT
5079 #define verify_memory_slice(m,i,n) (void)(0)  // PRODUCT version is no-op
5080 #endif
5081 
5082 
5083 //-----------------------------memory_at---------------------------------------
5084 Node* MergeMemNode::memory_at(uint alias_idx) const {
5085   assert(alias_idx >= Compile::AliasIdxRaw ||
5086          alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
5087          "must avoid base_memory and AliasIdxTop");
5088 
5089   // Otherwise, it is a narrow slice.
5090   Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5091   if (is_empty_memory(n)) {
5092     // the array is sparse; empty slots are the "top" node
5093     n = base_memory();
5094     assert(Node::in_dump()
5095            || n == NULL || n->bottom_type() == Type::TOP
5096            || n->adr_type() == NULL // address is TOP
5097            || n->adr_type() == TypePtr::BOTTOM
5098            || n->adr_type() == TypeRawPtr::BOTTOM
5099            || Compile::current()->AliasLevel() == 0,
5100            "must be a wide memory");
5101     // AliasLevel == 0 if we are organizing the memory states manually.
5102     // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5103   } else {
5104     // make sure the stored slice is sane
5105     #ifdef ASSERT
5106     if (VMError::is_error_reported() || Node::in_dump()) {
5107     } else if (might_be_same(n, base_memory())) {
5108       // Give it a pass:  It is a mostly harmless repetition of the base.
5109       // This can arise normally from node subsumption during optimization.
5110     } else {
5111       verify_memory_slice(this, alias_idx, n);
5112     }
5113     #endif
5114   }
5115   return n;
5116 }
5117 
5118 //---------------------------set_memory_at-------------------------------------
5119 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5120   verify_memory_slice(this, alias_idx, n);
5121   Node* empty_mem = empty_memory();
5122   if (n == base_memory())  n = empty_mem;  // collapse default
5123   uint need_req = alias_idx+1;
5124   if (req() < need_req) {
5125     if (n == empty_mem)  return;  // already the default, so do not grow me
5126     // grow the sparse array
5127     do {
5128       add_req(empty_mem);
5129     } while (req() < need_req);
5130   }
5131   set_req( alias_idx, n );
5132 }
5133 
5134 
5135 
5136 //--------------------------iteration_setup------------------------------------
5137 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5138   if (other != NULL) {
5139     grow_to_match(other);
5140     // invariant:  the finite support of mm2 is within mm->req()
5141     #ifdef ASSERT
5142     for (uint i = req(); i < other->req(); i++) {
5143       assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5144     }
5145     #endif
5146   }
5147   // Replace spurious copies of base_memory by top.
5148   Node* base_mem = base_memory();
5149   if (base_mem != NULL && !base_mem->is_top()) {
5150     for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5151       if (in(i) == base_mem)
5152         set_req(i, empty_memory());
5153     }
5154   }
5155 }
5156 
5157 //---------------------------grow_to_match-------------------------------------
5158 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5159   Node* empty_mem = empty_memory();
5160   assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5161   // look for the finite support of the other memory
5162   for (uint i = other->req(); --i >= req(); ) {
5163     if (other->in(i) != empty_mem) {
5164       uint new_len = i+1;
5165       while (req() < new_len)  add_req(empty_mem);
5166       break;
5167     }
5168   }
5169 }
5170 
5171 //---------------------------verify_sparse-------------------------------------
5172 #ifndef PRODUCT
5173 bool MergeMemNode::verify_sparse() const {
5174   assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5175   Node* base_mem = base_memory();
5176   // The following can happen in degenerate cases, since empty==top.
5177   if (is_empty_memory(base_mem))  return true;
5178   for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5179     assert(in(i) != NULL, "sane slice");
5180     if (in(i) == base_mem)  return false;  // should have been the sentinel value!
5181   }
5182   return true;
5183 }
5184 
5185 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5186   Node* n;
5187   n = mm->in(idx);
5188   if (mem == n)  return true;  // might be empty_memory()
5189   n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5190   if (mem == n)  return true;
5191   return false;
5192 }
5193 #endif // !PRODUCT