1 /*
   2  * Copyright (c) 2005, 2016, 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/bcEscapeAnalyzer.hpp"
  27 #include "compiler/compileLog.hpp"
  28 #include "libadt/vectset.hpp"
  29 #include "memory/allocation.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "opto/c2compiler.hpp"
  32 #include "opto/arraycopynode.hpp"
  33 #include "opto/callnode.hpp"
  34 #include "opto/cfgnode.hpp"
  35 #include "opto/compile.hpp"
  36 #include "opto/escape.hpp"
  37 #include "opto/phaseX.hpp"
  38 #include "opto/movenode.hpp"
  39 #include "opto/rootnode.hpp"
  40 
  41 ConnectionGraph::ConnectionGraph(Compile * C, PhaseIterGVN *igvn) :
  42   _nodes(C->comp_arena(), C->unique(), C->unique(), NULL),
  43   _in_worklist(C->comp_arena()),
  44   _next_pidx(0),
  45   _collecting(true),
  46   _verify(false),
  47   _compile(C),
  48   _igvn(igvn),
  49   _node_map(C->comp_arena()) {
  50   // Add unknown java object.
  51   add_java_object(C->top(), PointsToNode::GlobalEscape);
  52   phantom_obj = ptnode_adr(C->top()->_idx)->as_JavaObject();
  53   // Add ConP(#NULL) and ConN(#NULL) nodes.
  54   Node* oop_null = igvn->zerocon(T_OBJECT);
  55   assert(oop_null->_idx < nodes_size(), "should be created already");
  56   add_java_object(oop_null, PointsToNode::NoEscape);
  57   null_obj = ptnode_adr(oop_null->_idx)->as_JavaObject();
  58   if (UseCompressedOops) {
  59     Node* noop_null = igvn->zerocon(T_NARROWOOP);
  60     assert(noop_null->_idx < nodes_size(), "should be created already");
  61     map_ideal_node(noop_null, null_obj);
  62   }
  63   _pcmp_neq = NULL; // Should be initialized
  64   _pcmp_eq  = NULL;
  65 }
  66 
  67 bool ConnectionGraph::has_candidates(Compile *C) {
  68   // EA brings benefits only when the code has allocations and/or locks which
  69   // are represented by ideal Macro nodes.
  70   int cnt = C->macro_count();
  71   for (int i = 0; i < cnt; i++) {
  72     Node *n = C->macro_node(i);
  73     if (n->is_Allocate())
  74       return true;
  75     if (n->is_Lock()) {
  76       Node* obj = n->as_Lock()->obj_node()->uncast();
  77       if (!(obj->is_Parm() || obj->is_Con()))
  78         return true;
  79     }
  80     if (n->is_CallStaticJava() &&
  81         n->as_CallStaticJava()->is_boxing_method()) {
  82       return true;
  83     }
  84   }
  85   return false;
  86 }
  87 
  88 void ConnectionGraph::do_analysis(Compile *C, PhaseIterGVN *igvn) {
  89   Compile::TracePhase tp("escapeAnalysis", &Phase::timers[Phase::_t_escapeAnalysis]);
  90   ResourceMark rm;
  91 
  92   // Add ConP#NULL and ConN#NULL nodes before ConnectionGraph construction
  93   // to create space for them in ConnectionGraph::_nodes[].
  94   Node* oop_null = igvn->zerocon(T_OBJECT);
  95   Node* noop_null = igvn->zerocon(T_NARROWOOP);
  96   ConnectionGraph* congraph = new(C->comp_arena()) ConnectionGraph(C, igvn);
  97   // Perform escape analysis
  98   if (congraph->compute_escape()) {
  99     // There are non escaping objects.
 100     C->set_congraph(congraph);
 101   }
 102   // Cleanup.
 103   if (oop_null->outcnt() == 0)
 104     igvn->hash_delete(oop_null);
 105   if (noop_null->outcnt() == 0)
 106     igvn->hash_delete(noop_null);
 107 }
 108 
 109 bool ConnectionGraph::compute_escape() {
 110   Compile* C = _compile;
 111   PhaseGVN* igvn = _igvn;
 112 
 113   // Worklists used by EA.
 114   Unique_Node_List delayed_worklist;
 115   GrowableArray<Node*> alloc_worklist;
 116   GrowableArray<Node*> ptr_cmp_worklist;
 117   GrowableArray<Node*> storestore_worklist;
 118   GrowableArray<ArrayCopyNode*> arraycopy_worklist;
 119   GrowableArray<PointsToNode*>   ptnodes_worklist;
 120   GrowableArray<JavaObjectNode*> java_objects_worklist;
 121   GrowableArray<JavaObjectNode*> non_escaped_worklist;
 122   GrowableArray<FieldNode*>      oop_fields_worklist;
 123   DEBUG_ONLY( GrowableArray<Node*> addp_worklist; )
 124 
 125   { Compile::TracePhase tp("connectionGraph", &Phase::timers[Phase::_t_connectionGraph]);
 126 
 127   // 1. Populate Connection Graph (CG) with PointsTo nodes.
 128   ideal_nodes.map(C->live_nodes(), NULL);  // preallocate space
 129   // Initialize worklist
 130   if (C->root() != NULL) {
 131     ideal_nodes.push(C->root());
 132   }
 133   // Processed ideal nodes are unique on ideal_nodes list
 134   // but several ideal nodes are mapped to the phantom_obj.
 135   // To avoid duplicated entries on the following worklists
 136   // add the phantom_obj only once to them.
 137   ptnodes_worklist.append(phantom_obj);
 138   java_objects_worklist.append(phantom_obj);
 139   for( uint next = 0; next < ideal_nodes.size(); ++next ) {
 140     Node* n = ideal_nodes.at(next);
 141     // Create PointsTo nodes and add them to Connection Graph. Called
 142     // only once per ideal node since ideal_nodes is Unique_Node list.
 143     add_node_to_connection_graph(n, &delayed_worklist);
 144     PointsToNode* ptn = ptnode_adr(n->_idx);
 145     if (ptn != NULL && ptn != phantom_obj) {
 146       ptnodes_worklist.append(ptn);
 147       if (ptn->is_JavaObject()) {
 148         java_objects_worklist.append(ptn->as_JavaObject());
 149         if ((n->is_Allocate() || n->is_CallStaticJava()) &&
 150             (ptn->escape_state() < PointsToNode::GlobalEscape)) {
 151           // Only allocations and java static calls results are interesting.
 152           non_escaped_worklist.append(ptn->as_JavaObject());
 153         }
 154       } else if (ptn->is_Field() && ptn->as_Field()->is_oop()) {
 155         oop_fields_worklist.append(ptn->as_Field());
 156       }
 157     }
 158     if (n->is_MergeMem()) {
 159       // Collect all MergeMem nodes to add memory slices for
 160       // scalar replaceable objects in split_unique_types().
 161       _mergemem_worklist.append(n->as_MergeMem());
 162     } else if (OptimizePtrCompare && n->is_Cmp() &&
 163                (n->Opcode() == Op_CmpP || n->Opcode() == Op_CmpN)) {
 164       // Collect compare pointers nodes.
 165       ptr_cmp_worklist.append(n);
 166     } else if (n->is_MemBarStoreStore()) {
 167       // Collect all MemBarStoreStore nodes so that depending on the
 168       // escape status of the associated Allocate node some of them
 169       // may be eliminated.
 170       storestore_worklist.append(n);
 171     } else if (n->is_MemBar() && (n->Opcode() == Op_MemBarRelease) &&
 172                (n->req() > MemBarNode::Precedent)) {
 173       record_for_optimizer(n);
 174 #ifdef ASSERT
 175     } else if (n->is_AddP()) {
 176       // Collect address nodes for graph verification.
 177       addp_worklist.append(n);
 178 #endif
 179     } else if (n->is_ArrayCopy()) {
 180       // Keep a list of ArrayCopy nodes so if one of its input is non
 181       // escaping, we can record a unique type
 182       arraycopy_worklist.append(n->as_ArrayCopy());
 183     }
 184     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 185       Node* m = n->fast_out(i);   // Get user
 186       ideal_nodes.push(m);
 187     }
 188   }
 189   if (non_escaped_worklist.length() == 0) {
 190     _collecting = false;
 191     return false; // Nothing to do.
 192   }
 193   // Add final simple edges to graph.
 194   while(delayed_worklist.size() > 0) {
 195     Node* n = delayed_worklist.pop();
 196     add_final_edges(n);
 197   }
 198   int ptnodes_length = ptnodes_worklist.length();
 199 
 200 #ifdef ASSERT
 201   if (VerifyConnectionGraph) {
 202     // Verify that no new simple edges could be created and all
 203     // local vars has edges.
 204     _verify = true;
 205     for (int next = 0; next < ptnodes_length; ++next) {
 206       PointsToNode* ptn = ptnodes_worklist.at(next);
 207       add_final_edges(ptn->ideal_node());
 208       if (ptn->is_LocalVar() && ptn->edge_count() == 0) {
 209         ptn->dump();
 210         assert(ptn->as_LocalVar()->edge_count() > 0, "sanity");
 211       }
 212     }
 213     _verify = false;
 214   }
 215 #endif
 216   // Bytecode analyzer BCEscapeAnalyzer, used for Call nodes
 217   // processing, calls to CI to resolve symbols (types, fields, methods)
 218   // referenced in bytecode. During symbol resolution VM may throw
 219   // an exception which CI cleans and converts to compilation failure.
 220   if (C->failing())  return false;
 221 
 222   // 2. Finish Graph construction by propagating references to all
 223   //    java objects through graph.
 224   if (!complete_connection_graph(ptnodes_worklist, non_escaped_worklist,
 225                                  java_objects_worklist, oop_fields_worklist)) {
 226     // All objects escaped or hit time or iterations limits.
 227     _collecting = false;
 228     return false;
 229   }
 230 
 231   // 3. Adjust scalar_replaceable state of nonescaping objects and push
 232   //    scalar replaceable allocations on alloc_worklist for processing
 233   //    in split_unique_types().
 234   int non_escaped_length = non_escaped_worklist.length();
 235   for (int next = 0; next < non_escaped_length; next++) {
 236     JavaObjectNode* ptn = non_escaped_worklist.at(next);
 237     bool noescape = (ptn->escape_state() == PointsToNode::NoEscape);
 238     Node* n = ptn->ideal_node();
 239     if (n->is_Allocate()) {
 240       n->as_Allocate()->_is_non_escaping = noescape;
 241     }
 242     if (n->is_CallStaticJava()) {
 243       n->as_CallStaticJava()->_is_non_escaping = noescape;
 244     }
 245     if (noescape && ptn->scalar_replaceable()) {
 246       adjust_scalar_replaceable_state(ptn);
 247       if (ptn->scalar_replaceable()) {
 248         alloc_worklist.append(ptn->ideal_node());
 249       }
 250     }
 251   }
 252 
 253 #ifdef ASSERT
 254   if (VerifyConnectionGraph) {
 255     // Verify that graph is complete - no new edges could be added or needed.
 256     verify_connection_graph(ptnodes_worklist, non_escaped_worklist,
 257                             java_objects_worklist, addp_worklist);
 258   }
 259   assert(C->unique() == nodes_size(), "no new ideal nodes should be added during ConnectionGraph build");
 260   assert(null_obj->escape_state() == PointsToNode::NoEscape &&
 261          null_obj->edge_count() == 0 &&
 262          !null_obj->arraycopy_src() &&
 263          !null_obj->arraycopy_dst(), "sanity");
 264 #endif
 265 
 266   _collecting = false;
 267 
 268   } // TracePhase t3("connectionGraph")
 269 
 270   // 4. Optimize ideal graph based on EA information.
 271   bool has_non_escaping_obj = (non_escaped_worklist.length() > 0);
 272   if (has_non_escaping_obj) {
 273     optimize_ideal_graph(ptr_cmp_worklist, storestore_worklist);
 274   }
 275 
 276 #ifndef PRODUCT
 277   if (PrintEscapeAnalysis) {
 278     dump(ptnodes_worklist); // Dump ConnectionGraph
 279   }
 280 #endif
 281 
 282   bool has_scalar_replaceable_candidates = (alloc_worklist.length() > 0);
 283 #ifdef ASSERT
 284   if (VerifyConnectionGraph) {
 285     int alloc_length = alloc_worklist.length();
 286     for (int next = 0; next < alloc_length; ++next) {
 287       Node* n = alloc_worklist.at(next);
 288       PointsToNode* ptn = ptnode_adr(n->_idx);
 289       assert(ptn->escape_state() == PointsToNode::NoEscape && ptn->scalar_replaceable(), "sanity");
 290     }
 291   }
 292 #endif
 293 
 294   // 5. Separate memory graph for scalar replaceable allcations.
 295   if (has_scalar_replaceable_candidates &&
 296       C->AliasLevel() >= 3 && EliminateAllocations) {
 297     // Now use the escape information to create unique types for
 298     // scalar replaceable objects.
 299     split_unique_types(alloc_worklist, arraycopy_worklist);
 300     if (C->failing())  return false;
 301     C->print_method(PHASE_AFTER_EA, 2);
 302 
 303 #ifdef ASSERT
 304   } else if (Verbose && (PrintEscapeAnalysis || PrintEliminateAllocations)) {
 305     tty->print("=== No allocations eliminated for ");
 306     C->method()->print_short_name();
 307     if(!EliminateAllocations) {
 308       tty->print(" since EliminateAllocations is off ===");
 309     } else if(!has_scalar_replaceable_candidates) {
 310       tty->print(" since there are no scalar replaceable candidates ===");
 311     } else if(C->AliasLevel() < 3) {
 312       tty->print(" since AliasLevel < 3 ===");
 313     }
 314     tty->cr();
 315 #endif
 316   }
 317   return has_non_escaping_obj;
 318 }
 319 
 320 // Utility function for nodes that load an object
 321 void ConnectionGraph::add_objload_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist) {
 322   // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
 323   // ThreadLocal has RawPtr type.
 324   const Type* t = _igvn->type(n);
 325   if (t->make_ptr() != NULL) {
 326     Node* adr = n->in(MemNode::Address);
 327 #ifdef ASSERT
 328     if (!adr->is_AddP()) {
 329       assert(_igvn->type(adr)->isa_rawptr(), "sanity");
 330     } else {
 331       assert((ptnode_adr(adr->_idx) == NULL ||
 332               ptnode_adr(adr->_idx)->as_Field()->is_oop()), "sanity");
 333     }
 334 #endif
 335     add_local_var_and_edge(n, PointsToNode::NoEscape,
 336                            adr, delayed_worklist);
 337   }
 338 }
 339 
 340 // Populate Connection Graph with PointsTo nodes and create simple
 341 // connection graph edges.
 342 void ConnectionGraph::add_node_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist) {
 343   assert(!_verify, "this method should not be called for verification");
 344   PhaseGVN* igvn = _igvn;
 345   uint n_idx = n->_idx;
 346   PointsToNode* n_ptn = ptnode_adr(n_idx);
 347   if (n_ptn != NULL)
 348     return; // No need to redefine PointsTo node during first iteration.
 349 
 350   if (n->is_Call()) {
 351     // Arguments to allocation and locking don't escape.
 352     if (n->is_AbstractLock()) {
 353       // Put Lock and Unlock nodes on IGVN worklist to process them during
 354       // first IGVN optimization when escape information is still available.
 355       record_for_optimizer(n);
 356     } else if (n->is_Allocate()) {
 357       add_call_node(n->as_Call());
 358       record_for_optimizer(n);
 359     } else {
 360       if (n->is_CallStaticJava()) {
 361         const char* name = n->as_CallStaticJava()->_name;
 362         if (name != NULL && strcmp(name, "uncommon_trap") == 0)
 363           return; // Skip uncommon traps
 364       }
 365       // Don't mark as processed since call's arguments have to be processed.
 366       delayed_worklist->push(n);
 367       // Check if a call returns an object.
 368       if ((n->as_Call()->returns_pointer() &&
 369            n->as_Call()->proj_out(TypeFunc::Parms) != NULL) ||
 370           (n->is_CallStaticJava() &&
 371            n->as_CallStaticJava()->is_boxing_method())) {
 372         add_call_node(n->as_Call());
 373       }
 374     }
 375     return;
 376   }
 377   // Put this check here to process call arguments since some call nodes
 378   // point to phantom_obj.
 379   if (n_ptn == phantom_obj || n_ptn == null_obj)
 380     return; // Skip predefined nodes.
 381 
 382   int opcode = n->Opcode();
 383   switch (opcode) {
 384     case Op_AddP: {
 385       Node* base = get_addp_base(n);
 386       PointsToNode* ptn_base = ptnode_adr(base->_idx);
 387       // Field nodes are created for all field types. They are used in
 388       // adjust_scalar_replaceable_state() and split_unique_types().
 389       // Note, non-oop fields will have only base edges in Connection
 390       // Graph because such fields are not used for oop loads and stores.
 391       int offset = address_offset(n, igvn);
 392       add_field(n, PointsToNode::NoEscape, offset);
 393       if (ptn_base == NULL) {
 394         delayed_worklist->push(n); // Process it later.
 395       } else {
 396         n_ptn = ptnode_adr(n_idx);
 397         add_base(n_ptn->as_Field(), ptn_base);
 398       }
 399       break;
 400     }
 401     case Op_CastX2P: {
 402       map_ideal_node(n, phantom_obj);
 403       break;
 404     }
 405     case Op_CastPP:
 406     case Op_CheckCastPP:
 407     case Op_EncodeP:
 408     case Op_DecodeN:
 409     case Op_EncodePKlass:
 410     case Op_DecodeNKlass: {
 411       add_local_var_and_edge(n, PointsToNode::NoEscape,
 412                              n->in(1), delayed_worklist);
 413       break;
 414     }
 415     case Op_CMoveP: {
 416       add_local_var(n, PointsToNode::NoEscape);
 417       // Do not add edges during first iteration because some could be
 418       // not defined yet.
 419       delayed_worklist->push(n);
 420       break;
 421     }
 422     case Op_ConP:
 423     case Op_ConN:
 424     case Op_ConNKlass: {
 425       // assume all oop constants globally escape except for null
 426       PointsToNode::EscapeState es;
 427       const Type* t = igvn->type(n);
 428       if (t == TypePtr::NULL_PTR || t == TypeNarrowOop::NULL_PTR) {
 429         es = PointsToNode::NoEscape;
 430       } else {
 431         es = PointsToNode::GlobalEscape;
 432       }
 433       add_java_object(n, es);
 434       break;
 435     }
 436     case Op_CreateEx: {
 437       // assume that all exception objects globally escape
 438       map_ideal_node(n, phantom_obj);
 439       break;
 440     }
 441     case Op_LoadKlass:
 442     case Op_LoadNKlass: {
 443       // Unknown class is loaded
 444       map_ideal_node(n, phantom_obj);
 445       break;
 446     }
 447     case Op_LoadP:
 448     case Op_LoadN:
 449     case Op_LoadPLocked: {
 450       add_objload_to_connection_graph(n, delayed_worklist);
 451       break;
 452     }
 453     case Op_Parm: {
 454       map_ideal_node(n, phantom_obj);
 455       break;
 456     }
 457     case Op_PartialSubtypeCheck: {
 458       // Produces Null or notNull and is used in only in CmpP so
 459       // phantom_obj could be used.
 460       map_ideal_node(n, phantom_obj); // Result is unknown
 461       break;
 462     }
 463     case Op_Phi: {
 464       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
 465       // ThreadLocal has RawPtr type.
 466       const Type* t = n->as_Phi()->type();
 467       if (t->make_ptr() != NULL) {
 468         add_local_var(n, PointsToNode::NoEscape);
 469         // Do not add edges during first iteration because some could be
 470         // not defined yet.
 471         delayed_worklist->push(n);
 472       }
 473       break;
 474     }
 475     case Op_Proj: {
 476       // we are only interested in the oop result projection from a call
 477       if (n->as_Proj()->_con == TypeFunc::Parms && n->in(0)->is_Call() &&
 478           n->in(0)->as_Call()->returns_pointer()) {
 479         add_local_var_and_edge(n, PointsToNode::NoEscape,
 480                                n->in(0), delayed_worklist);
 481       }
 482       break;
 483     }
 484     case Op_Rethrow: // Exception object escapes
 485     case Op_Return: {
 486       if (n->req() > TypeFunc::Parms &&
 487           igvn->type(n->in(TypeFunc::Parms))->isa_oopptr()) {
 488         // Treat Return value as LocalVar with GlobalEscape escape state.
 489         add_local_var_and_edge(n, PointsToNode::GlobalEscape,
 490                                n->in(TypeFunc::Parms), delayed_worklist);
 491       }
 492       break;
 493     }
 494     case Op_CompareAndExchangeP:
 495     case Op_CompareAndExchangeN:
 496     case Op_GetAndSetP:
 497     case Op_GetAndSetN: {
 498       add_objload_to_connection_graph(n, delayed_worklist);
 499       // fallthrough
 500     }
 501     case Op_StoreP:
 502     case Op_StoreN:
 503     case Op_StoreNKlass:
 504     case Op_StorePConditional:
 505     case Op_WeakCompareAndSwapP:
 506     case Op_WeakCompareAndSwapN:
 507     case Op_CompareAndSwapP:
 508     case Op_CompareAndSwapN: {
 509       Node* adr = n->in(MemNode::Address);
 510       const Type *adr_type = igvn->type(adr);
 511       adr_type = adr_type->make_ptr();
 512       if (adr_type == NULL) {
 513         break; // skip dead nodes
 514       }
 515       if (adr_type->isa_oopptr() ||
 516           (opcode == Op_StoreP || opcode == Op_StoreN || opcode == Op_StoreNKlass) &&
 517                         (adr_type == TypeRawPtr::NOTNULL &&
 518                          adr->in(AddPNode::Address)->is_Proj() &&
 519                          adr->in(AddPNode::Address)->in(0)->is_Allocate())) {
 520         delayed_worklist->push(n); // Process it later.
 521 #ifdef ASSERT
 522         assert(adr->is_AddP(), "expecting an AddP");
 523         if (adr_type == TypeRawPtr::NOTNULL) {
 524           // Verify a raw address for a store captured by Initialize node.
 525           int offs = (int)igvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
 526           assert(offs != Type::OffsetBot, "offset must be a constant");
 527         }
 528 #endif
 529       } else {
 530         // Ignore copy the displaced header to the BoxNode (OSR compilation).
 531         if (adr->is_BoxLock())
 532           break;
 533         // Stored value escapes in unsafe access.
 534         if ((opcode == Op_StoreP) && adr_type->isa_rawptr()) {
 535           // Pointer stores in G1 barriers looks like unsafe access.
 536           // Ignore such stores to be able scalar replace non-escaping
 537           // allocations.
 538           if (UseG1GC && adr->is_AddP()) {
 539             Node* base = get_addp_base(adr);
 540             if (base->Opcode() == Op_LoadP &&
 541                 base->in(MemNode::Address)->is_AddP()) {
 542               adr = base->in(MemNode::Address);
 543               Node* tls = get_addp_base(adr);
 544               if (tls->Opcode() == Op_ThreadLocal) {
 545                 int offs = (int)igvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
 546                 if (offs == in_bytes(JavaThread::satb_mark_queue_offset() +
 547                                      SATBMarkQueue::byte_offset_of_buf())) {
 548                   break; // G1 pre barrier previous oop value store.
 549                 }
 550                 if (offs == in_bytes(JavaThread::dirty_card_queue_offset() +
 551                                      DirtyCardQueue::byte_offset_of_buf())) {
 552                   break; // G1 post barrier card address store.
 553                 }
 554               }
 555             }
 556           }
 557           delayed_worklist->push(n); // Process unsafe access later.
 558           break;
 559         }
 560 #ifdef ASSERT
 561         n->dump(1);
 562         assert(false, "not unsafe or G1 barrier raw StoreP");
 563 #endif
 564       }
 565       break;
 566     }
 567     case Op_AryEq:
 568     case Op_HasNegatives:
 569     case Op_StrComp:
 570     case Op_StrEquals:
 571     case Op_StrIndexOf:
 572     case Op_StrIndexOfChar:
 573     case Op_StrInflatedCopy:
 574     case Op_StrCompressedCopy:
 575     case Op_EncodeISOArray: {
 576       add_local_var(n, PointsToNode::ArgEscape);
 577       delayed_worklist->push(n); // Process it later.
 578       break;
 579     }
 580     case Op_ThreadLocal: {
 581       add_java_object(n, PointsToNode::ArgEscape);
 582       break;
 583     }
 584     default:
 585       ; // Do nothing for nodes not related to EA.
 586   }
 587   return;
 588 }
 589 
 590 #ifdef ASSERT
 591 #define ELSE_FAIL(name)                               \
 592       /* Should not be called for not pointer type. */  \
 593       n->dump(1);                                       \
 594       assert(false, name);                              \
 595       break;
 596 #else
 597 #define ELSE_FAIL(name) \
 598       break;
 599 #endif
 600 
 601 // Add final simple edges to graph.
 602 void ConnectionGraph::add_final_edges(Node *n) {
 603   PointsToNode* n_ptn = ptnode_adr(n->_idx);
 604 #ifdef ASSERT
 605   if (_verify && n_ptn->is_JavaObject())
 606     return; // This method does not change graph for JavaObject.
 607 #endif
 608 
 609   if (n->is_Call()) {
 610     process_call_arguments(n->as_Call());
 611     return;
 612   }
 613   assert(n->is_Store() || n->is_LoadStore() ||
 614          (n_ptn != NULL) && (n_ptn->ideal_node() != NULL),
 615          "node should be registered already");
 616   int opcode = n->Opcode();
 617   switch (opcode) {
 618     case Op_AddP: {
 619       Node* base = get_addp_base(n);
 620       PointsToNode* ptn_base = ptnode_adr(base->_idx);
 621       assert(ptn_base != NULL, "field's base should be registered");
 622       add_base(n_ptn->as_Field(), ptn_base);
 623       break;
 624     }
 625     case Op_CastPP:
 626     case Op_CheckCastPP:
 627     case Op_EncodeP:
 628     case Op_DecodeN:
 629     case Op_EncodePKlass:
 630     case Op_DecodeNKlass: {
 631       add_local_var_and_edge(n, PointsToNode::NoEscape,
 632                              n->in(1), NULL);
 633       break;
 634     }
 635     case Op_CMoveP: {
 636       for (uint i = CMoveNode::IfFalse; i < n->req(); i++) {
 637         Node* in = n->in(i);
 638         if (in == NULL)
 639           continue;  // ignore NULL
 640         Node* uncast_in = in->uncast();
 641         if (uncast_in->is_top() || uncast_in == n)
 642           continue;  // ignore top or inputs which go back this node
 643         PointsToNode* ptn = ptnode_adr(in->_idx);
 644         assert(ptn != NULL, "node should be registered");
 645         add_edge(n_ptn, ptn);
 646       }
 647       break;
 648     }
 649     case Op_LoadP:
 650     case Op_LoadN:
 651     case Op_LoadPLocked: {
 652       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
 653       // ThreadLocal has RawPtr type.
 654       const Type* t = _igvn->type(n);
 655       if (t->make_ptr() != NULL) {
 656         Node* adr = n->in(MemNode::Address);
 657         add_local_var_and_edge(n, PointsToNode::NoEscape, adr, NULL);
 658         break;
 659       }
 660       ELSE_FAIL("Op_LoadP");
 661     }
 662     case Op_Phi: {
 663       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
 664       // ThreadLocal has RawPtr type.
 665       const Type* t = n->as_Phi()->type();
 666       if (t->make_ptr() != NULL) {
 667         for (uint i = 1; i < n->req(); i++) {
 668           Node* in = n->in(i);
 669           if (in == NULL)
 670             continue;  // ignore NULL
 671           Node* uncast_in = in->uncast();
 672           if (uncast_in->is_top() || uncast_in == n)
 673             continue;  // ignore top or inputs which go back this node
 674           PointsToNode* ptn = ptnode_adr(in->_idx);
 675           assert(ptn != NULL, "node should be registered");
 676           add_edge(n_ptn, ptn);
 677         }
 678         break;
 679       }
 680       ELSE_FAIL("Op_Phi");
 681     }
 682     case Op_Proj: {
 683       // we are only interested in the oop result projection from a call
 684       if (n->as_Proj()->_con == TypeFunc::Parms && n->in(0)->is_Call() &&
 685           n->in(0)->as_Call()->returns_pointer()) {
 686         add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(0), NULL);
 687         break;
 688       }
 689       ELSE_FAIL("Op_Proj");
 690     }
 691     case Op_Rethrow: // Exception object escapes
 692     case Op_Return: {
 693       if (n->req() > TypeFunc::Parms &&
 694           _igvn->type(n->in(TypeFunc::Parms))->isa_oopptr()) {
 695         // Treat Return value as LocalVar with GlobalEscape escape state.
 696         add_local_var_and_edge(n, PointsToNode::GlobalEscape,
 697                                n->in(TypeFunc::Parms), NULL);
 698         break;
 699       }
 700       ELSE_FAIL("Op_Return");
 701     }
 702     case Op_StoreP:
 703     case Op_StoreN:
 704     case Op_StoreNKlass:
 705     case Op_StorePConditional:
 706     case Op_CompareAndExchangeP:
 707     case Op_CompareAndExchangeN:
 708     case Op_CompareAndSwapP:
 709     case Op_CompareAndSwapN:
 710     case Op_WeakCompareAndSwapP:
 711     case Op_WeakCompareAndSwapN:
 712     case Op_GetAndSetP:
 713     case Op_GetAndSetN: {
 714       Node* adr = n->in(MemNode::Address);
 715       const Type *adr_type = _igvn->type(adr);
 716       adr_type = adr_type->make_ptr();
 717 #ifdef ASSERT
 718       if (adr_type == NULL) {
 719         n->dump(1);
 720         assert(adr_type != NULL, "dead node should not be on list");
 721         break;
 722       }
 723 #endif
 724       if (opcode == Op_GetAndSetP || opcode == Op_GetAndSetN) {
 725         add_local_var_and_edge(n, PointsToNode::NoEscape, adr, NULL);
 726       }
 727       if (adr_type->isa_oopptr() ||
 728           (opcode == Op_StoreP || opcode == Op_StoreN || opcode == Op_StoreNKlass) &&
 729                         (adr_type == TypeRawPtr::NOTNULL &&
 730                          adr->in(AddPNode::Address)->is_Proj() &&
 731                          adr->in(AddPNode::Address)->in(0)->is_Allocate())) {
 732         // Point Address to Value
 733         PointsToNode* adr_ptn = ptnode_adr(adr->_idx);
 734         assert(adr_ptn != NULL &&
 735                adr_ptn->as_Field()->is_oop(), "node should be registered");
 736         Node *val = n->in(MemNode::ValueIn);
 737         PointsToNode* ptn = ptnode_adr(val->_idx);
 738         assert(ptn != NULL, "node should be registered");
 739         add_edge(adr_ptn, ptn);
 740         break;
 741       } else if ((opcode == Op_StoreP) && adr_type->isa_rawptr()) {
 742         // Stored value escapes in unsafe access.
 743         Node *val = n->in(MemNode::ValueIn);
 744         PointsToNode* ptn = ptnode_adr(val->_idx);
 745         assert(ptn != NULL, "node should be registered");
 746         set_escape_state(ptn, PointsToNode::GlobalEscape);
 747         // Add edge to object for unsafe access with offset.
 748         PointsToNode* adr_ptn = ptnode_adr(adr->_idx);
 749         assert(adr_ptn != NULL, "node should be registered");
 750         if (adr_ptn->is_Field()) {
 751           assert(adr_ptn->as_Field()->is_oop(), "should be oop field");
 752           add_edge(adr_ptn, ptn);
 753         }
 754         break;
 755       }
 756       ELSE_FAIL("Op_StoreP");
 757     }
 758     case Op_AryEq:
 759     case Op_HasNegatives:
 760     case Op_StrComp:
 761     case Op_StrEquals:
 762     case Op_StrIndexOf:
 763     case Op_StrIndexOfChar:
 764     case Op_StrInflatedCopy:
 765     case Op_StrCompressedCopy:
 766     case Op_EncodeISOArray: {
 767       // char[]/byte[] arrays passed to string intrinsic do not escape but
 768       // they are not scalar replaceable. Adjust escape state for them.
 769       // Start from in(2) edge since in(1) is memory edge.
 770       for (uint i = 2; i < n->req(); i++) {
 771         Node* adr = n->in(i);
 772         const Type* at = _igvn->type(adr);
 773         if (!adr->is_top() && at->isa_ptr()) {
 774           assert(at == Type::TOP || at == TypePtr::NULL_PTR ||
 775                  at->isa_ptr() != NULL, "expecting a pointer");
 776           if (adr->is_AddP()) {
 777             adr = get_addp_base(adr);
 778           }
 779           PointsToNode* ptn = ptnode_adr(adr->_idx);
 780           assert(ptn != NULL, "node should be registered");
 781           add_edge(n_ptn, ptn);
 782         }
 783       }
 784       break;
 785     }
 786     default: {
 787       // This method should be called only for EA specific nodes which may
 788       // miss some edges when they were created.
 789 #ifdef ASSERT
 790       n->dump(1);
 791 #endif
 792       guarantee(false, "unknown node");
 793     }
 794   }
 795   return;
 796 }
 797 
 798 void ConnectionGraph::add_call_node(CallNode* call) {
 799   assert(call->returns_pointer(), "only for call which returns pointer");
 800   uint call_idx = call->_idx;
 801   if (call->is_Allocate()) {
 802     Node* k = call->in(AllocateNode::KlassNode);
 803     const TypeKlassPtr* kt = k->bottom_type()->isa_klassptr();
 804     assert(kt != NULL, "TypeKlassPtr  required.");
 805     ciKlass* cik = kt->klass();
 806     PointsToNode::EscapeState es = PointsToNode::NoEscape;
 807     bool scalar_replaceable = true;
 808     if (call->is_AllocateArray()) {
 809       if (!cik->is_array_klass()) { // StressReflectiveCode
 810         es = PointsToNode::GlobalEscape;
 811       } else {
 812         int length = call->in(AllocateNode::ALength)->find_int_con(-1);
 813         if (length < 0 || length > EliminateAllocationArraySizeLimit) {
 814           // Not scalar replaceable if the length is not constant or too big.
 815           scalar_replaceable = false;
 816         }
 817       }
 818     } else {  // Allocate instance
 819       if (cik->is_subclass_of(_compile->env()->Thread_klass()) ||
 820           cik->is_subclass_of(_compile->env()->Reference_klass()) ||
 821          !cik->is_instance_klass() || // StressReflectiveCode
 822          !cik->as_instance_klass()->can_be_instantiated() ||
 823           cik->as_instance_klass()->has_finalizer()) {
 824         es = PointsToNode::GlobalEscape;
 825       }
 826     }
 827     add_java_object(call, es);
 828     PointsToNode* ptn = ptnode_adr(call_idx);
 829     if (!scalar_replaceable && ptn->scalar_replaceable()) {
 830       ptn->set_scalar_replaceable(false);
 831     }
 832   } else if (call->is_CallStaticJava()) {
 833     // Call nodes could be different types:
 834     //
 835     // 1. CallDynamicJavaNode (what happened during call is unknown):
 836     //
 837     //    - mapped to GlobalEscape JavaObject node if oop is returned;
 838     //
 839     //    - all oop arguments are escaping globally;
 840     //
 841     // 2. CallStaticJavaNode (execute bytecode analysis if possible):
 842     //
 843     //    - the same as CallDynamicJavaNode if can't do bytecode analysis;
 844     //
 845     //    - mapped to GlobalEscape JavaObject node if unknown oop is returned;
 846     //    - mapped to NoEscape JavaObject node if non-escaping object allocated
 847     //      during call is returned;
 848     //    - mapped to ArgEscape LocalVar node pointed to object arguments
 849     //      which are returned and does not escape during call;
 850     //
 851     //    - oop arguments escaping status is defined by bytecode analysis;
 852     //
 853     // For a static call, we know exactly what method is being called.
 854     // Use bytecode estimator to record whether the call's return value escapes.
 855     ciMethod* meth = call->as_CallJava()->method();
 856     if (meth == NULL) {
 857       const char* name = call->as_CallStaticJava()->_name;
 858       assert(strncmp(name, "_multianewarray", 15) == 0, "TODO: add failed case check");
 859       // Returns a newly allocated unescaped object.
 860       add_java_object(call, PointsToNode::NoEscape);
 861       ptnode_adr(call_idx)->set_scalar_replaceable(false);
 862     } else if (meth->is_boxing_method()) {
 863       // Returns boxing object
 864       PointsToNode::EscapeState es;
 865       vmIntrinsics::ID intr = meth->intrinsic_id();
 866       if (intr == vmIntrinsics::_floatValue || intr == vmIntrinsics::_doubleValue) {
 867         // It does not escape if object is always allocated.
 868         es = PointsToNode::NoEscape;
 869       } else {
 870         // It escapes globally if object could be loaded from cache.
 871         es = PointsToNode::GlobalEscape;
 872       }
 873       add_java_object(call, es);
 874     } else {
 875       BCEscapeAnalyzer* call_analyzer = meth->get_bcea();
 876       call_analyzer->copy_dependencies(_compile->dependencies());
 877       if (call_analyzer->is_return_allocated()) {
 878         // Returns a newly allocated unescaped object, simply
 879         // update dependency information.
 880         // Mark it as NoEscape so that objects referenced by
 881         // it's fields will be marked as NoEscape at least.
 882         add_java_object(call, PointsToNode::NoEscape);
 883         ptnode_adr(call_idx)->set_scalar_replaceable(false);
 884       } else {
 885         // Determine whether any arguments are returned.
 886         const TypeTuple* d = call->tf()->domain();
 887         bool ret_arg = false;
 888         for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
 889           if (d->field_at(i)->isa_ptr() != NULL &&
 890               call_analyzer->is_arg_returned(i - TypeFunc::Parms)) {
 891             ret_arg = true;
 892             break;
 893           }
 894         }
 895         if (ret_arg) {
 896           add_local_var(call, PointsToNode::ArgEscape);
 897         } else {
 898           // Returns unknown object.
 899           map_ideal_node(call, phantom_obj);
 900         }
 901       }
 902     }
 903   } else {
 904     // An other type of call, assume the worst case:
 905     // returned value is unknown and globally escapes.
 906     assert(call->Opcode() == Op_CallDynamicJava, "add failed case check");
 907     map_ideal_node(call, phantom_obj);
 908   }
 909 }
 910 
 911 void ConnectionGraph::process_call_arguments(CallNode *call) {
 912     bool is_arraycopy = false;
 913     switch (call->Opcode()) {
 914 #ifdef ASSERT
 915     case Op_Allocate:
 916     case Op_AllocateArray:
 917     case Op_Lock:
 918     case Op_Unlock:
 919       assert(false, "should be done already");
 920       break;
 921 #endif
 922     case Op_ArrayCopy:
 923     case Op_CallLeafNoFP:
 924       // Most array copies are ArrayCopy nodes at this point but there
 925       // are still a few direct calls to the copy subroutines (See
 926       // PhaseStringOpts::copy_string())
 927       is_arraycopy = (call->Opcode() == Op_ArrayCopy) ||
 928         call->as_CallLeaf()->is_call_to_arraycopystub();
 929       // fall through
 930     case Op_CallLeaf: {
 931       // Stub calls, objects do not escape but they are not scale replaceable.
 932       // Adjust escape state for outgoing arguments.
 933       const TypeTuple * d = call->tf()->domain();
 934       bool src_has_oops = false;
 935       for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
 936         const Type* at = d->field_at(i);
 937         Node *arg = call->in(i);
 938         if (arg == NULL) {
 939           continue;
 940         }
 941         const Type *aat = _igvn->type(arg);
 942         if (arg->is_top() || !at->isa_ptr() || !aat->isa_ptr())
 943           continue;
 944         if (arg->is_AddP()) {
 945           //
 946           // The inline_native_clone() case when the arraycopy stub is called
 947           // after the allocation before Initialize and CheckCastPP nodes.
 948           // Or normal arraycopy for object arrays case.
 949           //
 950           // Set AddP's base (Allocate) as not scalar replaceable since
 951           // pointer to the base (with offset) is passed as argument.
 952           //
 953           arg = get_addp_base(arg);
 954         }
 955         PointsToNode* arg_ptn = ptnode_adr(arg->_idx);
 956         assert(arg_ptn != NULL, "should be registered");
 957         PointsToNode::EscapeState arg_esc = arg_ptn->escape_state();
 958         if (is_arraycopy || arg_esc < PointsToNode::ArgEscape) {
 959           assert(aat == Type::TOP || aat == TypePtr::NULL_PTR ||
 960                  aat->isa_ptr() != NULL, "expecting an Ptr");
 961           bool arg_has_oops = aat->isa_oopptr() &&
 962                               (aat->isa_oopptr()->klass() == NULL || aat->isa_instptr() ||
 963                                (aat->isa_aryptr() && aat->isa_aryptr()->klass()->is_obj_array_klass()));
 964           if (i == TypeFunc::Parms) {
 965             src_has_oops = arg_has_oops;
 966           }
 967           //
 968           // src or dst could be j.l.Object when other is basic type array:
 969           //
 970           //   arraycopy(char[],0,Object*,0,size);
 971           //   arraycopy(Object*,0,char[],0,size);
 972           //
 973           // Don't add edges in such cases.
 974           //
 975           bool arg_is_arraycopy_dest = src_has_oops && is_arraycopy &&
 976                                        arg_has_oops && (i > TypeFunc::Parms);
 977 #ifdef ASSERT
 978           if (!(is_arraycopy ||
 979                 (call->as_CallLeaf()->_name != NULL &&
 980                  (strcmp(call->as_CallLeaf()->_name, "g1_wb_pre")  == 0 ||
 981                   strcmp(call->as_CallLeaf()->_name, "g1_wb_post") == 0 ||
 982                   strcmp(call->as_CallLeaf()->_name, "updateBytesCRC32") == 0 ||
 983                   strcmp(call->as_CallLeaf()->_name, "updateBytesCRC32C") == 0 ||
 984                   strcmp(call->as_CallLeaf()->_name, "updateBytesAdler32") == 0 ||
 985                   strcmp(call->as_CallLeaf()->_name, "aescrypt_encryptBlock") == 0 ||
 986                   strcmp(call->as_CallLeaf()->_name, "aescrypt_decryptBlock") == 0 ||
 987                   strcmp(call->as_CallLeaf()->_name, "cipherBlockChaining_encryptAESCrypt") == 0 ||
 988                   strcmp(call->as_CallLeaf()->_name, "cipherBlockChaining_decryptAESCrypt") == 0 ||
 989                   strcmp(call->as_CallLeaf()->_name, "counterMode_AESCrypt") == 0 ||
 990                   strcmp(call->as_CallLeaf()->_name, "ghash_processBlocks") == 0 ||
 991                   strcmp(call->as_CallLeaf()->_name, "sha1_implCompress") == 0 ||
 992                   strcmp(call->as_CallLeaf()->_name, "sha1_implCompressMB") == 0 ||
 993                   strcmp(call->as_CallLeaf()->_name, "sha256_implCompress") == 0 ||
 994                   strcmp(call->as_CallLeaf()->_name, "sha256_implCompressMB") == 0 ||
 995                   strcmp(call->as_CallLeaf()->_name, "sha512_implCompress") == 0 ||
 996                   strcmp(call->as_CallLeaf()->_name, "sha512_implCompressMB") == 0 ||
 997                   strcmp(call->as_CallLeaf()->_name, "multiplyToLen") == 0 ||
 998                   strcmp(call->as_CallLeaf()->_name, "squareToLen") == 0 ||
 999                   strcmp(call->as_CallLeaf()->_name, "mulAdd") == 0 ||
1000                   strcmp(call->as_CallLeaf()->_name, "montgomery_multiply") == 0 ||
1001                   strcmp(call->as_CallLeaf()->_name, "montgomery_square") == 0 ||
1002                   strcmp(call->as_CallLeaf()->_name, "vectorizedMismatch") == 0)
1003                  ))) {
1004             call->dump();
1005             fatal("EA unexpected CallLeaf %s", call->as_CallLeaf()->_name);
1006           }
1007 #endif
1008           // Always process arraycopy's destination object since
1009           // we need to add all possible edges to references in
1010           // source object.
1011           if (arg_esc >= PointsToNode::ArgEscape &&
1012               !arg_is_arraycopy_dest) {
1013             continue;
1014           }
1015           PointsToNode::EscapeState es = PointsToNode::ArgEscape;
1016           if (call->is_ArrayCopy()) {
1017             ArrayCopyNode* ac = call->as_ArrayCopy();
1018             if (ac->is_clonebasic() ||
1019                 ac->is_arraycopy_validated() ||
1020                 ac->is_copyof_validated() ||
1021                 ac->is_copyofrange_validated()) {
1022               es = PointsToNode::NoEscape;
1023             }
1024           }
1025           set_escape_state(arg_ptn, es);
1026           if (arg_is_arraycopy_dest) {
1027             Node* src = call->in(TypeFunc::Parms);
1028             if (src->is_AddP()) {
1029               src = get_addp_base(src);
1030             }
1031             PointsToNode* src_ptn = ptnode_adr(src->_idx);
1032             assert(src_ptn != NULL, "should be registered");
1033             if (arg_ptn != src_ptn) {
1034               // Special arraycopy edge:
1035               // A destination object's field can't have the source object
1036               // as base since objects escape states are not related.
1037               // Only escape state of destination object's fields affects
1038               // escape state of fields in source object.
1039               add_arraycopy(call, es, src_ptn, arg_ptn);
1040             }
1041           }
1042         }
1043       }
1044       break;
1045     }
1046     case Op_CallStaticJava: {
1047       // For a static call, we know exactly what method is being called.
1048       // Use bytecode estimator to record the call's escape affects
1049 #ifdef ASSERT
1050       const char* name = call->as_CallStaticJava()->_name;
1051       assert((name == NULL || strcmp(name, "uncommon_trap") != 0), "normal calls only");
1052 #endif
1053       ciMethod* meth = call->as_CallJava()->method();
1054       if ((meth != NULL) && meth->is_boxing_method()) {
1055         break; // Boxing methods do not modify any oops.
1056       }
1057       BCEscapeAnalyzer* call_analyzer = (meth !=NULL) ? meth->get_bcea() : NULL;
1058       // fall-through if not a Java method or no analyzer information
1059       if (call_analyzer != NULL) {
1060         PointsToNode* call_ptn = ptnode_adr(call->_idx);
1061         const TypeTuple* d = call->tf()->domain();
1062         for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
1063           const Type* at = d->field_at(i);
1064           int k = i - TypeFunc::Parms;
1065           Node* arg = call->in(i);
1066           PointsToNode* arg_ptn = ptnode_adr(arg->_idx);
1067           if (at->isa_ptr() != NULL &&
1068               call_analyzer->is_arg_returned(k)) {
1069             // The call returns arguments.
1070             if (call_ptn != NULL) { // Is call's result used?
1071               assert(call_ptn->is_LocalVar(), "node should be registered");
1072               assert(arg_ptn != NULL, "node should be registered");
1073               add_edge(call_ptn, arg_ptn);
1074             }
1075           }
1076           if (at->isa_oopptr() != NULL &&
1077               arg_ptn->escape_state() < PointsToNode::GlobalEscape) {
1078             if (!call_analyzer->is_arg_stack(k)) {
1079               // The argument global escapes
1080               set_escape_state(arg_ptn, PointsToNode::GlobalEscape);
1081             } else {
1082               set_escape_state(arg_ptn, PointsToNode::ArgEscape);
1083               if (!call_analyzer->is_arg_local(k)) {
1084                 // The argument itself doesn't escape, but any fields might
1085                 set_fields_escape_state(arg_ptn, PointsToNode::GlobalEscape);
1086               }
1087             }
1088           }
1089         }
1090         if (call_ptn != NULL && call_ptn->is_LocalVar()) {
1091           // The call returns arguments.
1092           assert(call_ptn->edge_count() > 0, "sanity");
1093           if (!call_analyzer->is_return_local()) {
1094             // Returns also unknown object.
1095             add_edge(call_ptn, phantom_obj);
1096           }
1097         }
1098         break;
1099       }
1100     }
1101     default: {
1102       // Fall-through here if not a Java method or no analyzer information
1103       // or some other type of call, assume the worst case: all arguments
1104       // globally escape.
1105       const TypeTuple* d = call->tf()->domain();
1106       for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
1107         const Type* at = d->field_at(i);
1108         if (at->isa_oopptr() != NULL) {
1109           Node* arg = call->in(i);
1110           if (arg->is_AddP()) {
1111             arg = get_addp_base(arg);
1112           }
1113           assert(ptnode_adr(arg->_idx) != NULL, "should be defined already");
1114           set_escape_state(ptnode_adr(arg->_idx), PointsToNode::GlobalEscape);
1115         }
1116       }
1117     }
1118   }
1119 }
1120 
1121 
1122 // Finish Graph construction.
1123 bool ConnectionGraph::complete_connection_graph(
1124                          GrowableArray<PointsToNode*>&   ptnodes_worklist,
1125                          GrowableArray<JavaObjectNode*>& non_escaped_worklist,
1126                          GrowableArray<JavaObjectNode*>& java_objects_worklist,
1127                          GrowableArray<FieldNode*>&      oop_fields_worklist) {
1128   // Normally only 1-3 passes needed to build Connection Graph depending
1129   // on graph complexity. Observed 8 passes in jvm2008 compiler.compiler.
1130   // Set limit to 20 to catch situation when something did go wrong and
1131   // bailout Escape Analysis.
1132   // Also limit build time to 20 sec (60 in debug VM), EscapeAnalysisTimeout flag.
1133 #define CG_BUILD_ITER_LIMIT 20
1134 
1135   // Propagate GlobalEscape and ArgEscape escape states and check that
1136   // we still have non-escaping objects. The method pushs on _worklist
1137   // Field nodes which reference phantom_object.
1138   if (!find_non_escaped_objects(ptnodes_worklist, non_escaped_worklist)) {
1139     return false; // Nothing to do.
1140   }
1141   // Now propagate references to all JavaObject nodes.
1142   int java_objects_length = java_objects_worklist.length();
1143   elapsedTimer time;
1144   bool timeout = false;
1145   int new_edges = 1;
1146   int iterations = 0;
1147   do {
1148     while ((new_edges > 0) &&
1149            (iterations++ < CG_BUILD_ITER_LIMIT)) {
1150       double start_time = time.seconds();
1151       time.start();
1152       new_edges = 0;
1153       // Propagate references to phantom_object for nodes pushed on _worklist
1154       // by find_non_escaped_objects() and find_field_value().
1155       new_edges += add_java_object_edges(phantom_obj, false);
1156       for (int next = 0; next < java_objects_length; ++next) {
1157         JavaObjectNode* ptn = java_objects_worklist.at(next);
1158         new_edges += add_java_object_edges(ptn, true);
1159 
1160 #define SAMPLE_SIZE 4
1161         if ((next % SAMPLE_SIZE) == 0) {
1162           // Each 4 iterations calculate how much time it will take
1163           // to complete graph construction.
1164           time.stop();
1165           // Poll for requests from shutdown mechanism to quiesce compiler
1166           // because Connection graph construction may take long time.
1167           CompileBroker::maybe_block();
1168           double stop_time = time.seconds();
1169           double time_per_iter = (stop_time - start_time) / (double)SAMPLE_SIZE;
1170           double time_until_end = time_per_iter * (double)(java_objects_length - next);
1171           if ((start_time + time_until_end) >= EscapeAnalysisTimeout) {
1172             timeout = true;
1173             break; // Timeout
1174           }
1175           start_time = stop_time;
1176           time.start();
1177         }
1178 #undef SAMPLE_SIZE
1179 
1180       }
1181       if (timeout) break;
1182       if (new_edges > 0) {
1183         // Update escape states on each iteration if graph was updated.
1184         if (!find_non_escaped_objects(ptnodes_worklist, non_escaped_worklist)) {
1185           return false; // Nothing to do.
1186         }
1187       }
1188       time.stop();
1189       if (time.seconds() >= EscapeAnalysisTimeout) {
1190         timeout = true;
1191         break;
1192       }
1193     }
1194     if ((iterations < CG_BUILD_ITER_LIMIT) && !timeout) {
1195       time.start();
1196       // Find fields which have unknown value.
1197       int fields_length = oop_fields_worklist.length();
1198       for (int next = 0; next < fields_length; next++) {
1199         FieldNode* field = oop_fields_worklist.at(next);
1200         if (field->edge_count() == 0) {
1201           new_edges += find_field_value(field);
1202           // This code may added new edges to phantom_object.
1203           // Need an other cycle to propagate references to phantom_object.
1204         }
1205       }
1206       time.stop();
1207       if (time.seconds() >= EscapeAnalysisTimeout) {
1208         timeout = true;
1209         break;
1210       }
1211     } else {
1212       new_edges = 0; // Bailout
1213     }
1214   } while (new_edges > 0);
1215 
1216   // Bailout if passed limits.
1217   if ((iterations >= CG_BUILD_ITER_LIMIT) || timeout) {
1218     Compile* C = _compile;
1219     if (C->log() != NULL) {
1220       C->log()->begin_elem("connectionGraph_bailout reason='reached ");
1221       C->log()->text("%s", timeout ? "time" : "iterations");
1222       C->log()->end_elem(" limit'");
1223     }
1224     assert(ExitEscapeAnalysisOnTimeout, "infinite EA connection graph build (%f sec, %d iterations) with %d nodes and worklist size %d",
1225            time.seconds(), iterations, nodes_size(), ptnodes_worklist.length());
1226     // Possible infinite build_connection_graph loop,
1227     // bailout (no changes to ideal graph were made).
1228     return false;
1229   }
1230 #ifdef ASSERT
1231   if (Verbose && PrintEscapeAnalysis) {
1232     tty->print_cr("EA: %d iterations to build connection graph with %d nodes and worklist size %d",
1233                   iterations, nodes_size(), ptnodes_worklist.length());
1234   }
1235 #endif
1236 
1237 #undef CG_BUILD_ITER_LIMIT
1238 
1239   // Find fields initialized by NULL for non-escaping Allocations.
1240   int non_escaped_length = non_escaped_worklist.length();
1241   for (int next = 0; next < non_escaped_length; next++) {
1242     JavaObjectNode* ptn = non_escaped_worklist.at(next);
1243     PointsToNode::EscapeState es = ptn->escape_state();
1244     assert(es <= PointsToNode::ArgEscape, "sanity");
1245     if (es == PointsToNode::NoEscape) {
1246       if (find_init_values(ptn, null_obj, _igvn) > 0) {
1247         // Adding references to NULL object does not change escape states
1248         // since it does not escape. Also no fields are added to NULL object.
1249         add_java_object_edges(null_obj, false);
1250       }
1251     }
1252     Node* n = ptn->ideal_node();
1253     if (n->is_Allocate()) {
1254       // The object allocated by this Allocate node will never be
1255       // seen by an other thread. Mark it so that when it is
1256       // expanded no MemBarStoreStore is added.
1257       InitializeNode* ini = n->as_Allocate()->initialization();
1258       if (ini != NULL)
1259         ini->set_does_not_escape();
1260     }
1261   }
1262   return true; // Finished graph construction.
1263 }
1264 
1265 // Propagate GlobalEscape and ArgEscape escape states to all nodes
1266 // and check that we still have non-escaping java objects.
1267 bool ConnectionGraph::find_non_escaped_objects(GrowableArray<PointsToNode*>& ptnodes_worklist,
1268                                                GrowableArray<JavaObjectNode*>& non_escaped_worklist) {
1269   GrowableArray<PointsToNode*> escape_worklist;
1270   // First, put all nodes with GlobalEscape and ArgEscape states on worklist.
1271   int ptnodes_length = ptnodes_worklist.length();
1272   for (int next = 0; next < ptnodes_length; ++next) {
1273     PointsToNode* ptn = ptnodes_worklist.at(next);
1274     if (ptn->escape_state() >= PointsToNode::ArgEscape ||
1275         ptn->fields_escape_state() >= PointsToNode::ArgEscape) {
1276       escape_worklist.push(ptn);
1277     }
1278   }
1279   // Set escape states to referenced nodes (edges list).
1280   while (escape_worklist.length() > 0) {
1281     PointsToNode* ptn = escape_worklist.pop();
1282     PointsToNode::EscapeState es  = ptn->escape_state();
1283     PointsToNode::EscapeState field_es = ptn->fields_escape_state();
1284     if (ptn->is_Field() && ptn->as_Field()->is_oop() &&
1285         es >= PointsToNode::ArgEscape) {
1286       // GlobalEscape or ArgEscape state of field means it has unknown value.
1287       if (add_edge(ptn, phantom_obj)) {
1288         // New edge was added
1289         add_field_uses_to_worklist(ptn->as_Field());
1290       }
1291     }
1292     for (EdgeIterator i(ptn); i.has_next(); i.next()) {
1293       PointsToNode* e = i.get();
1294       if (e->is_Arraycopy()) {
1295         assert(ptn->arraycopy_dst(), "sanity");
1296         // Propagate only fields escape state through arraycopy edge.
1297         if (e->fields_escape_state() < field_es) {
1298           set_fields_escape_state(e, field_es);
1299           escape_worklist.push(e);
1300         }
1301       } else if (es >= field_es) {
1302         // fields_escape_state is also set to 'es' if it is less than 'es'.
1303         if (e->escape_state() < es) {
1304           set_escape_state(e, es);
1305           escape_worklist.push(e);
1306         }
1307       } else {
1308         // Propagate field escape state.
1309         bool es_changed = false;
1310         if (e->fields_escape_state() < field_es) {
1311           set_fields_escape_state(e, field_es);
1312           es_changed = true;
1313         }
1314         if ((e->escape_state() < field_es) &&
1315             e->is_Field() && ptn->is_JavaObject() &&
1316             e->as_Field()->is_oop()) {
1317           // Change escape state of referenced fields.
1318           set_escape_state(e, field_es);
1319           es_changed = true;
1320         } else if (e->escape_state() < es) {
1321           set_escape_state(e, es);
1322           es_changed = true;
1323         }
1324         if (es_changed) {
1325           escape_worklist.push(e);
1326         }
1327       }
1328     }
1329   }
1330   // Remove escaped objects from non_escaped list.
1331   for (int next = non_escaped_worklist.length()-1; next >= 0 ; --next) {
1332     JavaObjectNode* ptn = non_escaped_worklist.at(next);
1333     if (ptn->escape_state() >= PointsToNode::GlobalEscape) {
1334       non_escaped_worklist.delete_at(next);
1335     }
1336     if (ptn->escape_state() == PointsToNode::NoEscape) {
1337       // Find fields in non-escaped allocations which have unknown value.
1338       find_init_values(ptn, phantom_obj, NULL);
1339     }
1340   }
1341   return (non_escaped_worklist.length() > 0);
1342 }
1343 
1344 // Add all references to JavaObject node by walking over all uses.
1345 int ConnectionGraph::add_java_object_edges(JavaObjectNode* jobj, bool populate_worklist) {
1346   int new_edges = 0;
1347   if (populate_worklist) {
1348     // Populate _worklist by uses of jobj's uses.
1349     for (UseIterator i(jobj); i.has_next(); i.next()) {
1350       PointsToNode* use = i.get();
1351       if (use->is_Arraycopy())
1352         continue;
1353       add_uses_to_worklist(use);
1354       if (use->is_Field() && use->as_Field()->is_oop()) {
1355         // Put on worklist all field's uses (loads) and
1356         // related field nodes (same base and offset).
1357         add_field_uses_to_worklist(use->as_Field());
1358       }
1359     }
1360   }
1361   for (int l = 0; l < _worklist.length(); l++) {
1362     PointsToNode* use = _worklist.at(l);
1363     if (PointsToNode::is_base_use(use)) {
1364       // Add reference from jobj to field and from field to jobj (field's base).
1365       use = PointsToNode::get_use_node(use)->as_Field();
1366       if (add_base(use->as_Field(), jobj)) {
1367         new_edges++;
1368       }
1369       continue;
1370     }
1371     assert(!use->is_JavaObject(), "sanity");
1372     if (use->is_Arraycopy()) {
1373       if (jobj == null_obj) // NULL object does not have field edges
1374         continue;
1375       // Added edge from Arraycopy node to arraycopy's source java object
1376       if (add_edge(use, jobj)) {
1377         jobj->set_arraycopy_src();
1378         new_edges++;
1379       }
1380       // and stop here.
1381       continue;
1382     }
1383     if (!add_edge(use, jobj))
1384       continue; // No new edge added, there was such edge already.
1385     new_edges++;
1386     if (use->is_LocalVar()) {
1387       add_uses_to_worklist(use);
1388       if (use->arraycopy_dst()) {
1389         for (EdgeIterator i(use); i.has_next(); i.next()) {
1390           PointsToNode* e = i.get();
1391           if (e->is_Arraycopy()) {
1392             if (jobj == null_obj) // NULL object does not have field edges
1393               continue;
1394             // Add edge from arraycopy's destination java object to Arraycopy node.
1395             if (add_edge(jobj, e)) {
1396               new_edges++;
1397               jobj->set_arraycopy_dst();
1398             }
1399           }
1400         }
1401       }
1402     } else {
1403       // Added new edge to stored in field values.
1404       // Put on worklist all field's uses (loads) and
1405       // related field nodes (same base and offset).
1406       add_field_uses_to_worklist(use->as_Field());
1407     }
1408   }
1409   _worklist.clear();
1410   _in_worklist.Reset();
1411   return new_edges;
1412 }
1413 
1414 // Put on worklist all related field nodes.
1415 void ConnectionGraph::add_field_uses_to_worklist(FieldNode* field) {
1416   assert(field->is_oop(), "sanity");
1417   int offset = field->offset();
1418   add_uses_to_worklist(field);
1419   // Loop over all bases of this field and push on worklist Field nodes
1420   // with the same offset and base (since they may reference the same field).
1421   for (BaseIterator i(field); i.has_next(); i.next()) {
1422     PointsToNode* base = i.get();
1423     add_fields_to_worklist(field, base);
1424     // Check if the base was source object of arraycopy and go over arraycopy's
1425     // destination objects since values stored to a field of source object are
1426     // accessable by uses (loads) of fields of destination objects.
1427     if (base->arraycopy_src()) {
1428       for (UseIterator j(base); j.has_next(); j.next()) {
1429         PointsToNode* arycp = j.get();
1430         if (arycp->is_Arraycopy()) {
1431           for (UseIterator k(arycp); k.has_next(); k.next()) {
1432             PointsToNode* abase = k.get();
1433             if (abase->arraycopy_dst() && abase != base) {
1434               // Look for the same arraycopy reference.
1435               add_fields_to_worklist(field, abase);
1436             }
1437           }
1438         }
1439       }
1440     }
1441   }
1442 }
1443 
1444 // Put on worklist all related field nodes.
1445 void ConnectionGraph::add_fields_to_worklist(FieldNode* field, PointsToNode* base) {
1446   int offset = field->offset();
1447   if (base->is_LocalVar()) {
1448     for (UseIterator j(base); j.has_next(); j.next()) {
1449       PointsToNode* f = j.get();
1450       if (PointsToNode::is_base_use(f)) { // Field
1451         f = PointsToNode::get_use_node(f);
1452         if (f == field || !f->as_Field()->is_oop())
1453           continue;
1454         int offs = f->as_Field()->offset();
1455         if (offs == offset || offset == Type::OffsetBot || offs == Type::OffsetBot) {
1456           add_to_worklist(f);
1457         }
1458       }
1459     }
1460   } else {
1461     assert(base->is_JavaObject(), "sanity");
1462     if (// Skip phantom_object since it is only used to indicate that
1463         // this field's content globally escapes.
1464         (base != phantom_obj) &&
1465         // NULL object node does not have fields.
1466         (base != null_obj)) {
1467       for (EdgeIterator i(base); i.has_next(); i.next()) {
1468         PointsToNode* f = i.get();
1469         // Skip arraycopy edge since store to destination object field
1470         // does not update value in source object field.
1471         if (f->is_Arraycopy()) {
1472           assert(base->arraycopy_dst(), "sanity");
1473           continue;
1474         }
1475         if (f == field || !f->as_Field()->is_oop())
1476           continue;
1477         int offs = f->as_Field()->offset();
1478         if (offs == offset || offset == Type::OffsetBot || offs == Type::OffsetBot) {
1479           add_to_worklist(f);
1480         }
1481       }
1482     }
1483   }
1484 }
1485 
1486 // Find fields which have unknown value.
1487 int ConnectionGraph::find_field_value(FieldNode* field) {
1488   // Escaped fields should have init value already.
1489   assert(field->escape_state() == PointsToNode::NoEscape, "sanity");
1490   int new_edges = 0;
1491   for (BaseIterator i(field); i.has_next(); i.next()) {
1492     PointsToNode* base = i.get();
1493     if (base->is_JavaObject()) {
1494       // Skip Allocate's fields which will be processed later.
1495       if (base->ideal_node()->is_Allocate())
1496         return 0;
1497       assert(base == null_obj, "only NULL ptr base expected here");
1498     }
1499   }
1500   if (add_edge(field, phantom_obj)) {
1501     // New edge was added
1502     new_edges++;
1503     add_field_uses_to_worklist(field);
1504   }
1505   return new_edges;
1506 }
1507 
1508 // Find fields initializing values for allocations.
1509 int ConnectionGraph::find_init_values(JavaObjectNode* pta, PointsToNode* init_val, PhaseTransform* phase) {
1510   assert(pta->escape_state() == PointsToNode::NoEscape, "Not escaped Allocate nodes only");
1511   int new_edges = 0;
1512   Node* alloc = pta->ideal_node();
1513   if (init_val == phantom_obj) {
1514     // Do nothing for Allocate nodes since its fields values are
1515     // "known" unless they are initialized by arraycopy/clone.
1516     if (alloc->is_Allocate() && !pta->arraycopy_dst())
1517       return 0;
1518     assert(pta->arraycopy_dst() || alloc->as_CallStaticJava(), "sanity");
1519 #ifdef ASSERT
1520     if (!pta->arraycopy_dst() && alloc->as_CallStaticJava()->method() == NULL) {
1521       const char* name = alloc->as_CallStaticJava()->_name;
1522       assert(strncmp(name, "_multianewarray", 15) == 0, "sanity");
1523     }
1524 #endif
1525     // Non-escaped allocation returned from Java or runtime call have
1526     // unknown values in fields.
1527     for (EdgeIterator i(pta); i.has_next(); i.next()) {
1528       PointsToNode* field = i.get();
1529       if (field->is_Field() && field->as_Field()->is_oop()) {
1530         if (add_edge(field, phantom_obj)) {
1531           // New edge was added
1532           new_edges++;
1533           add_field_uses_to_worklist(field->as_Field());
1534         }
1535       }
1536     }
1537     return new_edges;
1538   }
1539   assert(init_val == null_obj, "sanity");
1540   // Do nothing for Call nodes since its fields values are unknown.
1541   if (!alloc->is_Allocate())
1542     return 0;
1543 
1544   InitializeNode* ini = alloc->as_Allocate()->initialization();
1545   bool visited_bottom_offset = false;
1546   GrowableArray<int> offsets_worklist;
1547 
1548   // Check if an oop field's initializing value is recorded and add
1549   // a corresponding NULL if field's value if it is not recorded.
1550   // Connection Graph does not record a default initialization by NULL
1551   // captured by Initialize node.
1552   //
1553   for (EdgeIterator i(pta); i.has_next(); i.next()) {
1554     PointsToNode* field = i.get(); // Field (AddP)
1555     if (!field->is_Field() || !field->as_Field()->is_oop())
1556       continue; // Not oop field
1557     int offset = field->as_Field()->offset();
1558     if (offset == Type::OffsetBot) {
1559       if (!visited_bottom_offset) {
1560         // OffsetBot is used to reference array's element,
1561         // always add reference to NULL to all Field nodes since we don't
1562         // known which element is referenced.
1563         if (add_edge(field, null_obj)) {
1564           // New edge was added
1565           new_edges++;
1566           add_field_uses_to_worklist(field->as_Field());
1567           visited_bottom_offset = true;
1568         }
1569       }
1570     } else {
1571       // Check only oop fields.
1572       const Type* adr_type = field->ideal_node()->as_AddP()->bottom_type();
1573       if (adr_type->isa_rawptr()) {
1574 #ifdef ASSERT
1575         // Raw pointers are used for initializing stores so skip it
1576         // since it should be recorded already
1577         Node* base = get_addp_base(field->ideal_node());
1578         assert(adr_type->isa_rawptr() && base->is_Proj() &&
1579                (base->in(0) == alloc),"unexpected pointer type");
1580 #endif
1581         continue;
1582       }
1583       if (!offsets_worklist.contains(offset)) {
1584         offsets_worklist.append(offset);
1585         Node* value = NULL;
1586         if (ini != NULL) {
1587           // StoreP::memory_type() == T_ADDRESS
1588           BasicType ft = UseCompressedOops ? T_NARROWOOP : T_ADDRESS;
1589           Node* store = ini->find_captured_store(offset, type2aelembytes(ft, true), phase);
1590           // Make sure initializing store has the same type as this AddP.
1591           // This AddP may reference non existing field because it is on a
1592           // dead branch of bimorphic call which is not eliminated yet.
1593           if (store != NULL && store->is_Store() &&
1594               store->as_Store()->memory_type() == ft) {
1595             value = store->in(MemNode::ValueIn);
1596 #ifdef ASSERT
1597             if (VerifyConnectionGraph) {
1598               // Verify that AddP already points to all objects the value points to.
1599               PointsToNode* val = ptnode_adr(value->_idx);
1600               assert((val != NULL), "should be processed already");
1601               PointsToNode* missed_obj = NULL;
1602               if (val->is_JavaObject()) {
1603                 if (!field->points_to(val->as_JavaObject())) {
1604                   missed_obj = val;
1605                 }
1606               } else {
1607                 if (!val->is_LocalVar() || (val->edge_count() == 0)) {
1608                   tty->print_cr("----------init store has invalid value -----");
1609                   store->dump();
1610                   val->dump();
1611                   assert(val->is_LocalVar() && (val->edge_count() > 0), "should be processed already");
1612                 }
1613                 for (EdgeIterator j(val); j.has_next(); j.next()) {
1614                   PointsToNode* obj = j.get();
1615                   if (obj->is_JavaObject()) {
1616                     if (!field->points_to(obj->as_JavaObject())) {
1617                       missed_obj = obj;
1618                       break;
1619                     }
1620                   }
1621                 }
1622               }
1623               if (missed_obj != NULL) {
1624                 tty->print_cr("----------field---------------------------------");
1625                 field->dump();
1626                 tty->print_cr("----------missed referernce to object-----------");
1627                 missed_obj->dump();
1628                 tty->print_cr("----------object referernced by init store -----");
1629                 store->dump();
1630                 val->dump();
1631                 assert(!field->points_to(missed_obj->as_JavaObject()), "missed JavaObject reference");
1632               }
1633             }
1634 #endif
1635           } else {
1636             // There could be initializing stores which follow allocation.
1637             // For example, a volatile field store is not collected
1638             // by Initialize node.
1639             //
1640             // Need to check for dependent loads to separate such stores from
1641             // stores which follow loads. For now, add initial value NULL so
1642             // that compare pointers optimization works correctly.
1643           }
1644         }
1645         if (value == NULL) {
1646           // A field's initializing value was not recorded. Add NULL.
1647           if (add_edge(field, null_obj)) {
1648             // New edge was added
1649             new_edges++;
1650             add_field_uses_to_worklist(field->as_Field());
1651           }
1652         }
1653       }
1654     }
1655   }
1656   return new_edges;
1657 }
1658 
1659 // Adjust scalar_replaceable state after Connection Graph is built.
1660 void ConnectionGraph::adjust_scalar_replaceable_state(JavaObjectNode* jobj) {
1661   // Search for non-escaping objects which are not scalar replaceable
1662   // and mark them to propagate the state to referenced objects.
1663 
1664   // 1. An object is not scalar replaceable if the field into which it is
1665   // stored has unknown offset (stored into unknown element of an array).
1666   //
1667   for (UseIterator i(jobj); i.has_next(); i.next()) {
1668     PointsToNode* use = i.get();
1669     if (use->is_Arraycopy()) {
1670       continue;
1671     }
1672     if (use->is_Field()) {
1673       FieldNode* field = use->as_Field();
1674       assert(field->is_oop() && field->scalar_replaceable(), "sanity");
1675       if (field->offset() == Type::OffsetBot) {
1676         jobj->set_scalar_replaceable(false);
1677         return;
1678       }
1679       // 2. An object is not scalar replaceable if the field into which it is
1680       // stored has multiple bases one of which is null.
1681       if (field->base_count() > 1) {
1682         for (BaseIterator i(field); i.has_next(); i.next()) {
1683           PointsToNode* base = i.get();
1684           if (base == null_obj) {
1685             jobj->set_scalar_replaceable(false);
1686             return;
1687           }
1688         }
1689       }
1690     }
1691     assert(use->is_Field() || use->is_LocalVar(), "sanity");
1692     // 3. An object is not scalar replaceable if it is merged with other objects.
1693     for (EdgeIterator j(use); j.has_next(); j.next()) {
1694       PointsToNode* ptn = j.get();
1695       if (ptn->is_JavaObject() && ptn != jobj) {
1696         // Mark all objects.
1697         jobj->set_scalar_replaceable(false);
1698          ptn->set_scalar_replaceable(false);
1699       }
1700     }
1701     if (!jobj->scalar_replaceable()) {
1702       return;
1703     }
1704   }
1705 
1706   for (EdgeIterator j(jobj); j.has_next(); j.next()) {
1707     if (j.get()->is_Arraycopy()) {
1708       continue;
1709     }
1710 
1711     // Non-escaping object node should point only to field nodes.
1712     FieldNode* field = j.get()->as_Field();
1713     int offset = field->as_Field()->offset();
1714 
1715     // 4. An object is not scalar replaceable if it has a field with unknown
1716     // offset (array's element is accessed in loop).
1717     if (offset == Type::OffsetBot) {
1718       jobj->set_scalar_replaceable(false);
1719       return;
1720     }
1721     // 5. Currently an object is not scalar replaceable if a LoadStore node
1722     // access its field since the field value is unknown after it.
1723     //
1724     Node* n = field->ideal_node();
1725     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1726       if (n->fast_out(i)->is_LoadStore()) {
1727         jobj->set_scalar_replaceable(false);
1728         return;
1729       }
1730     }
1731 
1732     // 6. Or the address may point to more then one object. This may produce
1733     // the false positive result (set not scalar replaceable)
1734     // since the flow-insensitive escape analysis can't separate
1735     // the case when stores overwrite the field's value from the case
1736     // when stores happened on different control branches.
1737     //
1738     // Note: it will disable scalar replacement in some cases:
1739     //
1740     //    Point p[] = new Point[1];
1741     //    p[0] = new Point(); // Will be not scalar replaced
1742     //
1743     // but it will save us from incorrect optimizations in next cases:
1744     //
1745     //    Point p[] = new Point[1];
1746     //    if ( x ) p[0] = new Point(); // Will be not scalar replaced
1747     //
1748     if (field->base_count() > 1) {
1749       for (BaseIterator i(field); i.has_next(); i.next()) {
1750         PointsToNode* base = i.get();
1751         // Don't take into account LocalVar nodes which
1752         // may point to only one object which should be also
1753         // this field's base by now.
1754         if (base->is_JavaObject() && base != jobj) {
1755           // Mark all bases.
1756           jobj->set_scalar_replaceable(false);
1757           base->set_scalar_replaceable(false);
1758         }
1759       }
1760     }
1761   }
1762 }
1763 
1764 #ifdef ASSERT
1765 void ConnectionGraph::verify_connection_graph(
1766                          GrowableArray<PointsToNode*>&   ptnodes_worklist,
1767                          GrowableArray<JavaObjectNode*>& non_escaped_worklist,
1768                          GrowableArray<JavaObjectNode*>& java_objects_worklist,
1769                          GrowableArray<Node*>& addp_worklist) {
1770   // Verify that graph is complete - no new edges could be added.
1771   int java_objects_length = java_objects_worklist.length();
1772   int non_escaped_length  = non_escaped_worklist.length();
1773   int new_edges = 0;
1774   for (int next = 0; next < java_objects_length; ++next) {
1775     JavaObjectNode* ptn = java_objects_worklist.at(next);
1776     new_edges += add_java_object_edges(ptn, true);
1777   }
1778   assert(new_edges == 0, "graph was not complete");
1779   // Verify that escape state is final.
1780   int length = non_escaped_worklist.length();
1781   find_non_escaped_objects(ptnodes_worklist, non_escaped_worklist);
1782   assert((non_escaped_length == non_escaped_worklist.length()) &&
1783          (non_escaped_length == length) &&
1784          (_worklist.length() == 0), "escape state was not final");
1785 
1786   // Verify fields information.
1787   int addp_length = addp_worklist.length();
1788   for (int next = 0; next < addp_length; ++next ) {
1789     Node* n = addp_worklist.at(next);
1790     FieldNode* field = ptnode_adr(n->_idx)->as_Field();
1791     if (field->is_oop()) {
1792       // Verify that field has all bases
1793       Node* base = get_addp_base(n);
1794       PointsToNode* ptn = ptnode_adr(base->_idx);
1795       if (ptn->is_JavaObject()) {
1796         assert(field->has_base(ptn->as_JavaObject()), "sanity");
1797       } else {
1798         assert(ptn->is_LocalVar(), "sanity");
1799         for (EdgeIterator i(ptn); i.has_next(); i.next()) {
1800           PointsToNode* e = i.get();
1801           if (e->is_JavaObject()) {
1802             assert(field->has_base(e->as_JavaObject()), "sanity");
1803           }
1804         }
1805       }
1806       // Verify that all fields have initializing values.
1807       if (field->edge_count() == 0) {
1808         tty->print_cr("----------field does not have references----------");
1809         field->dump();
1810         for (BaseIterator i(field); i.has_next(); i.next()) {
1811           PointsToNode* base = i.get();
1812           tty->print_cr("----------field has next base---------------------");
1813           base->dump();
1814           if (base->is_JavaObject() && (base != phantom_obj) && (base != null_obj)) {
1815             tty->print_cr("----------base has fields-------------------------");
1816             for (EdgeIterator j(base); j.has_next(); j.next()) {
1817               j.get()->dump();
1818             }
1819             tty->print_cr("----------base has references---------------------");
1820             for (UseIterator j(base); j.has_next(); j.next()) {
1821               j.get()->dump();
1822             }
1823           }
1824         }
1825         for (UseIterator i(field); i.has_next(); i.next()) {
1826           i.get()->dump();
1827         }
1828         assert(field->edge_count() > 0, "sanity");
1829       }
1830     }
1831   }
1832 }
1833 #endif
1834 
1835 // Optimize ideal graph.
1836 void ConnectionGraph::optimize_ideal_graph(GrowableArray<Node*>& ptr_cmp_worklist,
1837                                            GrowableArray<Node*>& storestore_worklist) {
1838   Compile* C = _compile;
1839   PhaseIterGVN* igvn = _igvn;
1840   if (EliminateLocks) {
1841     // Mark locks before changing ideal graph.
1842     int cnt = C->macro_count();
1843     for( int i=0; i < cnt; i++ ) {
1844       Node *n = C->macro_node(i);
1845       if (n->is_AbstractLock()) { // Lock and Unlock nodes
1846         AbstractLockNode* alock = n->as_AbstractLock();
1847         if (!alock->is_non_esc_obj()) {
1848           if (not_global_escape(alock->obj_node())) {
1849             assert(!alock->is_eliminated() || alock->is_coarsened(), "sanity");
1850             // The lock could be marked eliminated by lock coarsening
1851             // code during first IGVN before EA. Replace coarsened flag
1852             // to eliminate all associated locks/unlocks.
1853 #ifdef ASSERT
1854             alock->log_lock_optimization(C, "eliminate_lock_set_non_esc3");
1855 #endif
1856             alock->set_non_esc_obj();
1857           }
1858         }
1859       }
1860     }
1861   }
1862 
1863   if (OptimizePtrCompare) {
1864     // Add ConI(#CC_GT) and ConI(#CC_EQ).
1865     _pcmp_neq = igvn->makecon(TypeInt::CC_GT);
1866     _pcmp_eq = igvn->makecon(TypeInt::CC_EQ);
1867     // Optimize objects compare.
1868     while (ptr_cmp_worklist.length() != 0) {
1869       Node *n = ptr_cmp_worklist.pop();
1870       Node *res = optimize_ptr_compare(n);
1871       if (res != NULL) {
1872 #ifndef PRODUCT
1873         if (PrintOptimizePtrCompare) {
1874           tty->print_cr("++++ Replaced: %d %s(%d,%d) --> %s", n->_idx, (n->Opcode() == Op_CmpP ? "CmpP" : "CmpN"), n->in(1)->_idx, n->in(2)->_idx, (res == _pcmp_eq ? "EQ" : "NotEQ"));
1875           if (Verbose) {
1876             n->dump(1);
1877           }
1878         }
1879 #endif
1880         igvn->replace_node(n, res);
1881       }
1882     }
1883     // cleanup
1884     if (_pcmp_neq->outcnt() == 0)
1885       igvn->hash_delete(_pcmp_neq);
1886     if (_pcmp_eq->outcnt()  == 0)
1887       igvn->hash_delete(_pcmp_eq);
1888   }
1889 
1890   // For MemBarStoreStore nodes added in library_call.cpp, check
1891   // escape status of associated AllocateNode and optimize out
1892   // MemBarStoreStore node if the allocated object never escapes.
1893   while (storestore_worklist.length() != 0) {
1894     Node *n = storestore_worklist.pop();
1895     MemBarStoreStoreNode *storestore = n ->as_MemBarStoreStore();
1896     Node *alloc = storestore->in(MemBarNode::Precedent)->in(0);
1897     assert (alloc->is_Allocate(), "storestore should point to AllocateNode");
1898     if (not_global_escape(alloc)) {
1899       MemBarNode* mb = MemBarNode::make(C, Op_MemBarCPUOrder, Compile::AliasIdxBot);
1900       mb->init_req(TypeFunc::Memory, storestore->in(TypeFunc::Memory));
1901       mb->init_req(TypeFunc::Control, storestore->in(TypeFunc::Control));
1902       igvn->register_new_node_with_optimizer(mb);
1903       igvn->replace_node(storestore, mb);
1904     }
1905   }
1906 }
1907 
1908 // Optimize objects compare.
1909 Node* ConnectionGraph::optimize_ptr_compare(Node* n) {
1910   assert(OptimizePtrCompare, "sanity");
1911   PointsToNode* ptn1 = ptnode_adr(n->in(1)->_idx);
1912   PointsToNode* ptn2 = ptnode_adr(n->in(2)->_idx);
1913   JavaObjectNode* jobj1 = unique_java_object(n->in(1));
1914   JavaObjectNode* jobj2 = unique_java_object(n->in(2));
1915   assert(ptn1->is_JavaObject() || ptn1->is_LocalVar(), "sanity");
1916   assert(ptn2->is_JavaObject() || ptn2->is_LocalVar(), "sanity");
1917 
1918   // Check simple cases first.
1919   if (jobj1 != NULL) {
1920     if (jobj1->escape_state() == PointsToNode::NoEscape) {
1921       if (jobj1 == jobj2) {
1922         // Comparing the same not escaping object.
1923         return _pcmp_eq;
1924       }
1925       Node* obj = jobj1->ideal_node();
1926       // Comparing not escaping allocation.
1927       if ((obj->is_Allocate() || obj->is_CallStaticJava()) &&
1928           !ptn2->points_to(jobj1)) {
1929         return _pcmp_neq; // This includes nullness check.
1930       }
1931     }
1932   }
1933   if (jobj2 != NULL) {
1934     if (jobj2->escape_state() == PointsToNode::NoEscape) {
1935       Node* obj = jobj2->ideal_node();
1936       // Comparing not escaping allocation.
1937       if ((obj->is_Allocate() || obj->is_CallStaticJava()) &&
1938           !ptn1->points_to(jobj2)) {
1939         return _pcmp_neq; // This includes nullness check.
1940       }
1941     }
1942   }
1943   if (jobj1 != NULL && jobj1 != phantom_obj &&
1944       jobj2 != NULL && jobj2 != phantom_obj &&
1945       jobj1->ideal_node()->is_Con() &&
1946       jobj2->ideal_node()->is_Con()) {
1947     // Klass or String constants compare. Need to be careful with
1948     // compressed pointers - compare types of ConN and ConP instead of nodes.
1949     const Type* t1 = jobj1->ideal_node()->get_ptr_type();
1950     const Type* t2 = jobj2->ideal_node()->get_ptr_type();
1951     if (t1->make_ptr() == t2->make_ptr()) {
1952       return _pcmp_eq;
1953     } else {
1954       return _pcmp_neq;
1955     }
1956   }
1957   if (ptn1->meet(ptn2)) {
1958     return NULL; // Sets are not disjoint
1959   }
1960 
1961   // Sets are disjoint.
1962   bool set1_has_unknown_ptr = ptn1->points_to(phantom_obj);
1963   bool set2_has_unknown_ptr = ptn2->points_to(phantom_obj);
1964   bool set1_has_null_ptr    = ptn1->points_to(null_obj);
1965   bool set2_has_null_ptr    = ptn2->points_to(null_obj);
1966   if (set1_has_unknown_ptr && set2_has_null_ptr ||
1967       set2_has_unknown_ptr && set1_has_null_ptr) {
1968     // Check nullness of unknown object.
1969     return NULL;
1970   }
1971 
1972   // Disjointness by itself is not sufficient since
1973   // alias analysis is not complete for escaped objects.
1974   // Disjoint sets are definitely unrelated only when
1975   // at least one set has only not escaping allocations.
1976   if (!set1_has_unknown_ptr && !set1_has_null_ptr) {
1977     if (ptn1->non_escaping_allocation()) {
1978       return _pcmp_neq;
1979     }
1980   }
1981   if (!set2_has_unknown_ptr && !set2_has_null_ptr) {
1982     if (ptn2->non_escaping_allocation()) {
1983       return _pcmp_neq;
1984     }
1985   }
1986   return NULL;
1987 }
1988 
1989 // Connection Graph constuction functions.
1990 
1991 void ConnectionGraph::add_local_var(Node *n, PointsToNode::EscapeState es) {
1992   PointsToNode* ptadr = _nodes.at(n->_idx);
1993   if (ptadr != NULL) {
1994     assert(ptadr->is_LocalVar() && ptadr->ideal_node() == n, "sanity");
1995     return;
1996   }
1997   Compile* C = _compile;
1998   ptadr = new (C->comp_arena()) LocalVarNode(this, n, es);
1999   _nodes.at_put(n->_idx, ptadr);
2000 }
2001 
2002 void ConnectionGraph::add_java_object(Node *n, PointsToNode::EscapeState es) {
2003   PointsToNode* ptadr = _nodes.at(n->_idx);
2004   if (ptadr != NULL) {
2005     assert(ptadr->is_JavaObject() && ptadr->ideal_node() == n, "sanity");
2006     return;
2007   }
2008   Compile* C = _compile;
2009   ptadr = new (C->comp_arena()) JavaObjectNode(this, n, es);
2010   _nodes.at_put(n->_idx, ptadr);
2011 }
2012 
2013 void ConnectionGraph::add_field(Node *n, PointsToNode::EscapeState es, int offset) {
2014   PointsToNode* ptadr = _nodes.at(n->_idx);
2015   if (ptadr != NULL) {
2016     assert(ptadr->is_Field() && ptadr->ideal_node() == n, "sanity");
2017     return;
2018   }
2019   bool unsafe = false;
2020   bool is_oop = is_oop_field(n, offset, &unsafe);
2021   if (unsafe) {
2022     es = PointsToNode::GlobalEscape;
2023   }
2024   Compile* C = _compile;
2025   FieldNode* field = new (C->comp_arena()) FieldNode(this, n, es, offset, is_oop);
2026   _nodes.at_put(n->_idx, field);
2027 }
2028 
2029 void ConnectionGraph::add_arraycopy(Node *n, PointsToNode::EscapeState es,
2030                                     PointsToNode* src, PointsToNode* dst) {
2031   assert(!src->is_Field() && !dst->is_Field(), "only for JavaObject and LocalVar");
2032   assert((src != null_obj) && (dst != null_obj), "not for ConP NULL");
2033   PointsToNode* ptadr = _nodes.at(n->_idx);
2034   if (ptadr != NULL) {
2035     assert(ptadr->is_Arraycopy() && ptadr->ideal_node() == n, "sanity");
2036     return;
2037   }
2038   Compile* C = _compile;
2039   ptadr = new (C->comp_arena()) ArraycopyNode(this, n, es);
2040   _nodes.at_put(n->_idx, ptadr);
2041   // Add edge from arraycopy node to source object.
2042   (void)add_edge(ptadr, src);
2043   src->set_arraycopy_src();
2044   // Add edge from destination object to arraycopy node.
2045   (void)add_edge(dst, ptadr);
2046   dst->set_arraycopy_dst();
2047 }
2048 
2049 bool ConnectionGraph::is_oop_field(Node* n, int offset, bool* unsafe) {
2050   const Type* adr_type = n->as_AddP()->bottom_type();
2051   BasicType bt = T_INT;
2052   if (offset == Type::OffsetBot) {
2053     // Check only oop fields.
2054     if (!adr_type->isa_aryptr() ||
2055         (adr_type->isa_aryptr()->klass() == NULL) ||
2056          adr_type->isa_aryptr()->klass()->is_obj_array_klass()) {
2057       // OffsetBot is used to reference array's element. Ignore first AddP.
2058       if (find_second_addp(n, n->in(AddPNode::Base)) == NULL) {
2059         bt = T_OBJECT;
2060       }
2061     }
2062   } else if (offset != oopDesc::klass_offset_in_bytes()) {
2063     if (adr_type->isa_instptr()) {
2064       ciField* field = _compile->alias_type(adr_type->isa_instptr())->field();
2065       if (field != NULL) {
2066         bt = field->layout_type();
2067       } else {
2068         // Check for unsafe oop field access
2069         if (n->has_out_with(Op_StoreP, Op_LoadP, Op_StoreN, Op_LoadN)) {
2070           bt = T_OBJECT;
2071           (*unsafe) = true;
2072         }
2073       }
2074     } else if (adr_type->isa_aryptr()) {
2075       if (offset == arrayOopDesc::length_offset_in_bytes()) {
2076         // Ignore array length load.
2077       } else if (find_second_addp(n, n->in(AddPNode::Base)) != NULL) {
2078         // Ignore first AddP.
2079       } else {
2080         const Type* elemtype = adr_type->isa_aryptr()->elem();
2081         bt = elemtype->array_element_basic_type();
2082       }
2083     } else if (adr_type->isa_rawptr() || adr_type->isa_klassptr()) {
2084       // Allocation initialization, ThreadLocal field access, unsafe access
2085       if (n->has_out_with(Op_StoreP, Op_LoadP, Op_StoreN, Op_LoadN)) {
2086         bt = T_OBJECT;
2087       }
2088     }
2089   }
2090   return (bt == T_OBJECT || bt == T_NARROWOOP || bt == T_ARRAY);
2091 }
2092 
2093 // Returns unique pointed java object or NULL.
2094 JavaObjectNode* ConnectionGraph::unique_java_object(Node *n) {
2095   assert(!_collecting, "should not call when contructed graph");
2096   // If the node was created after the escape computation we can't answer.
2097   uint idx = n->_idx;
2098   if (idx >= nodes_size()) {
2099     return NULL;
2100   }
2101   PointsToNode* ptn = ptnode_adr(idx);
2102   if (ptn->is_JavaObject()) {
2103     return ptn->as_JavaObject();
2104   }
2105   assert(ptn->is_LocalVar(), "sanity");
2106   // Check all java objects it points to.
2107   JavaObjectNode* jobj = NULL;
2108   for (EdgeIterator i(ptn); i.has_next(); i.next()) {
2109     PointsToNode* e = i.get();
2110     if (e->is_JavaObject()) {
2111       if (jobj == NULL) {
2112         jobj = e->as_JavaObject();
2113       } else if (jobj != e) {
2114         return NULL;
2115       }
2116     }
2117   }
2118   return jobj;
2119 }
2120 
2121 // Return true if this node points only to non-escaping allocations.
2122 bool PointsToNode::non_escaping_allocation() {
2123   if (is_JavaObject()) {
2124     Node* n = ideal_node();
2125     if (n->is_Allocate() || n->is_CallStaticJava()) {
2126       return (escape_state() == PointsToNode::NoEscape);
2127     } else {
2128       return false;
2129     }
2130   }
2131   assert(is_LocalVar(), "sanity");
2132   // Check all java objects it points to.
2133   for (EdgeIterator i(this); i.has_next(); i.next()) {
2134     PointsToNode* e = i.get();
2135     if (e->is_JavaObject()) {
2136       Node* n = e->ideal_node();
2137       if ((e->escape_state() != PointsToNode::NoEscape) ||
2138           !(n->is_Allocate() || n->is_CallStaticJava())) {
2139         return false;
2140       }
2141     }
2142   }
2143   return true;
2144 }
2145 
2146 // Return true if we know the node does not escape globally.
2147 bool ConnectionGraph::not_global_escape(Node *n) {
2148   assert(!_collecting, "should not call during graph construction");
2149   // If the node was created after the escape computation we can't answer.
2150   uint idx = n->_idx;
2151   if (idx >= nodes_size()) {
2152     return false;
2153   }
2154   PointsToNode* ptn = ptnode_adr(idx);
2155   PointsToNode::EscapeState es = ptn->escape_state();
2156   // If we have already computed a value, return it.
2157   if (es >= PointsToNode::GlobalEscape)
2158     return false;
2159   if (ptn->is_JavaObject()) {
2160     return true; // (es < PointsToNode::GlobalEscape);
2161   }
2162   assert(ptn->is_LocalVar(), "sanity");
2163   // Check all java objects it points to.
2164   for (EdgeIterator i(ptn); i.has_next(); i.next()) {
2165     if (i.get()->escape_state() >= PointsToNode::GlobalEscape)
2166       return false;
2167   }
2168   return true;
2169 }
2170 
2171 
2172 // Helper functions
2173 
2174 // Return true if this node points to specified node or nodes it points to.
2175 bool PointsToNode::points_to(JavaObjectNode* ptn) const {
2176   if (is_JavaObject()) {
2177     return (this == ptn);
2178   }
2179   assert(is_LocalVar() || is_Field(), "sanity");
2180   for (EdgeIterator i(this); i.has_next(); i.next()) {
2181     if (i.get() == ptn)
2182       return true;
2183   }
2184   return false;
2185 }
2186 
2187 // Return true if one node points to an other.
2188 bool PointsToNode::meet(PointsToNode* ptn) {
2189   if (this == ptn) {
2190     return true;
2191   } else if (ptn->is_JavaObject()) {
2192     return this->points_to(ptn->as_JavaObject());
2193   } else if (this->is_JavaObject()) {
2194     return ptn->points_to(this->as_JavaObject());
2195   }
2196   assert(this->is_LocalVar() && ptn->is_LocalVar(), "sanity");
2197   int ptn_count =  ptn->edge_count();
2198   for (EdgeIterator i(this); i.has_next(); i.next()) {
2199     PointsToNode* this_e = i.get();
2200     for (int j = 0; j < ptn_count; j++) {
2201       if (this_e == ptn->edge(j))
2202         return true;
2203     }
2204   }
2205   return false;
2206 }
2207 
2208 #ifdef ASSERT
2209 // Return true if bases point to this java object.
2210 bool FieldNode::has_base(JavaObjectNode* jobj) const {
2211   for (BaseIterator i(this); i.has_next(); i.next()) {
2212     if (i.get() == jobj)
2213       return true;
2214   }
2215   return false;
2216 }
2217 #endif
2218 
2219 int ConnectionGraph::address_offset(Node* adr, PhaseTransform *phase) {
2220   const Type *adr_type = phase->type(adr);
2221   if (adr->is_AddP() && adr_type->isa_oopptr() == NULL &&
2222       adr->in(AddPNode::Address)->is_Proj() &&
2223       adr->in(AddPNode::Address)->in(0)->is_Allocate()) {
2224     // We are computing a raw address for a store captured by an Initialize
2225     // compute an appropriate address type. AddP cases #3 and #5 (see below).
2226     int offs = (int)phase->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
2227     assert(offs != Type::OffsetBot ||
2228            adr->in(AddPNode::Address)->in(0)->is_AllocateArray(),
2229            "offset must be a constant or it is initialization of array");
2230     return offs;
2231   }
2232   const TypePtr *t_ptr = adr_type->isa_ptr();
2233   assert(t_ptr != NULL, "must be a pointer type");
2234   return t_ptr->offset();
2235 }
2236 
2237 Node* ConnectionGraph::get_addp_base(Node *addp) {
2238   assert(addp->is_AddP(), "must be AddP");
2239   //
2240   // AddP cases for Base and Address inputs:
2241   // case #1. Direct object's field reference:
2242   //     Allocate
2243   //       |
2244   //     Proj #5 ( oop result )
2245   //       |
2246   //     CheckCastPP (cast to instance type)
2247   //      | |
2248   //     AddP  ( base == address )
2249   //
2250   // case #2. Indirect object's field reference:
2251   //      Phi
2252   //       |
2253   //     CastPP (cast to instance type)
2254   //      | |
2255   //     AddP  ( base == address )
2256   //
2257   // case #3. Raw object's field reference for Initialize node:
2258   //      Allocate
2259   //        |
2260   //      Proj #5 ( oop result )
2261   //  top   |
2262   //     \  |
2263   //     AddP  ( base == top )
2264   //
2265   // case #4. Array's element reference:
2266   //   {CheckCastPP | CastPP}
2267   //     |  | |
2268   //     |  AddP ( array's element offset )
2269   //     |  |
2270   //     AddP ( array's offset )
2271   //
2272   // case #5. Raw object's field reference for arraycopy stub call:
2273   //          The inline_native_clone() case when the arraycopy stub is called
2274   //          after the allocation before Initialize and CheckCastPP nodes.
2275   //      Allocate
2276   //        |
2277   //      Proj #5 ( oop result )
2278   //       | |
2279   //       AddP  ( base == address )
2280   //
2281   // case #6. Constant Pool, ThreadLocal, CastX2P or
2282   //          Raw object's field reference:
2283   //      {ConP, ThreadLocal, CastX2P, raw Load}
2284   //  top   |
2285   //     \  |
2286   //     AddP  ( base == top )
2287   //
2288   // case #7. Klass's field reference.
2289   //      LoadKlass
2290   //       | |
2291   //       AddP  ( base == address )
2292   //
2293   // case #8. narrow Klass's field reference.
2294   //      LoadNKlass
2295   //       |
2296   //      DecodeN
2297   //       | |
2298   //       AddP  ( base == address )
2299   //
2300   Node *base = addp->in(AddPNode::Base);
2301   if (base->uncast()->is_top()) { // The AddP case #3 and #6.
2302     base = addp->in(AddPNode::Address);
2303     while (base->is_AddP()) {
2304       // Case #6 (unsafe access) may have several chained AddP nodes.
2305       assert(base->in(AddPNode::Base)->uncast()->is_top(), "expected unsafe access address only");
2306       base = base->in(AddPNode::Address);
2307     }
2308     Node* uncast_base = base->uncast();
2309     int opcode = uncast_base->Opcode();
2310     assert(opcode == Op_ConP || opcode == Op_ThreadLocal ||
2311            opcode == Op_CastX2P || uncast_base->is_DecodeNarrowPtr() ||
2312            (uncast_base->is_Mem() && (uncast_base->bottom_type()->isa_rawptr() != NULL)) ||
2313            (uncast_base->is_Proj() && uncast_base->in(0)->is_Allocate()), "sanity");
2314   }
2315   return base;
2316 }
2317 
2318 Node* ConnectionGraph::find_second_addp(Node* addp, Node* n) {
2319   assert(addp->is_AddP() && addp->outcnt() > 0, "Don't process dead nodes");
2320   Node* addp2 = addp->raw_out(0);
2321   if (addp->outcnt() == 1 && addp2->is_AddP() &&
2322       addp2->in(AddPNode::Base) == n &&
2323       addp2->in(AddPNode::Address) == addp) {
2324     assert(addp->in(AddPNode::Base) == n, "expecting the same base");
2325     //
2326     // Find array's offset to push it on worklist first and
2327     // as result process an array's element offset first (pushed second)
2328     // to avoid CastPP for the array's offset.
2329     // Otherwise the inserted CastPP (LocalVar) will point to what
2330     // the AddP (Field) points to. Which would be wrong since
2331     // the algorithm expects the CastPP has the same point as
2332     // as AddP's base CheckCastPP (LocalVar).
2333     //
2334     //    ArrayAllocation
2335     //     |
2336     //    CheckCastPP
2337     //     |
2338     //    memProj (from ArrayAllocation CheckCastPP)
2339     //     |  ||
2340     //     |  ||   Int (element index)
2341     //     |  ||    |   ConI (log(element size))
2342     //     |  ||    |   /
2343     //     |  ||   LShift
2344     //     |  ||  /
2345     //     |  AddP (array's element offset)
2346     //     |  |
2347     //     |  | ConI (array's offset: #12(32-bits) or #24(64-bits))
2348     //     | / /
2349     //     AddP (array's offset)
2350     //      |
2351     //     Load/Store (memory operation on array's element)
2352     //
2353     return addp2;
2354   }
2355   return NULL;
2356 }
2357 
2358 //
2359 // Adjust the type and inputs of an AddP which computes the
2360 // address of a field of an instance
2361 //
2362 bool ConnectionGraph::split_AddP(Node *addp, Node *base) {
2363   PhaseGVN* igvn = _igvn;
2364   const TypeOopPtr *base_t = igvn->type(base)->isa_oopptr();
2365   assert(base_t != NULL && base_t->is_known_instance(), "expecting instance oopptr");
2366   const TypeOopPtr *t = igvn->type(addp)->isa_oopptr();
2367   if (t == NULL) {
2368     // We are computing a raw address for a store captured by an Initialize
2369     // compute an appropriate address type (cases #3 and #5).
2370     assert(igvn->type(addp) == TypeRawPtr::NOTNULL, "must be raw pointer");
2371     assert(addp->in(AddPNode::Address)->is_Proj(), "base of raw address must be result projection from allocation");
2372     intptr_t offs = (int)igvn->find_intptr_t_con(addp->in(AddPNode::Offset), Type::OffsetBot);
2373     assert(offs != Type::OffsetBot, "offset must be a constant");
2374     t = base_t->add_offset(offs)->is_oopptr();
2375   }
2376   int inst_id =  base_t->instance_id();
2377   assert(!t->is_known_instance() || t->instance_id() == inst_id,
2378                              "old type must be non-instance or match new type");
2379 
2380   // The type 't' could be subclass of 'base_t'.
2381   // As result t->offset() could be large then base_t's size and it will
2382   // cause the failure in add_offset() with narrow oops since TypeOopPtr()
2383   // constructor verifies correctness of the offset.
2384   //
2385   // It could happened on subclass's branch (from the type profiling
2386   // inlining) which was not eliminated during parsing since the exactness
2387   // of the allocation type was not propagated to the subclass type check.
2388   //
2389   // Or the type 't' could be not related to 'base_t' at all.
2390   // It could happened when CHA type is different from MDO type on a dead path
2391   // (for example, from instanceof check) which is not collapsed during parsing.
2392   //
2393   // Do nothing for such AddP node and don't process its users since
2394   // this code branch will go away.
2395   //
2396   if (!t->is_known_instance() &&
2397       !base_t->klass()->is_subtype_of(t->klass())) {
2398      return false; // bail out
2399   }
2400   const TypeOopPtr *tinst = base_t->add_offset(t->offset())->is_oopptr();
2401   // Do NOT remove the next line: ensure a new alias index is allocated
2402   // for the instance type. Note: C++ will not remove it since the call
2403   // has side effect.
2404   int alias_idx = _compile->get_alias_index(tinst);
2405   igvn->set_type(addp, tinst);
2406   // record the allocation in the node map
2407   set_map(addp, get_map(base->_idx));
2408   // Set addp's Base and Address to 'base'.
2409   Node *abase = addp->in(AddPNode::Base);
2410   Node *adr   = addp->in(AddPNode::Address);
2411   if (adr->is_Proj() && adr->in(0)->is_Allocate() &&
2412       adr->in(0)->_idx == (uint)inst_id) {
2413     // Skip AddP cases #3 and #5.
2414   } else {
2415     assert(!abase->is_top(), "sanity"); // AddP case #3
2416     if (abase != base) {
2417       igvn->hash_delete(addp);
2418       addp->set_req(AddPNode::Base, base);
2419       if (abase == adr) {
2420         addp->set_req(AddPNode::Address, base);
2421       } else {
2422         // AddP case #4 (adr is array's element offset AddP node)
2423 #ifdef ASSERT
2424         const TypeOopPtr *atype = igvn->type(adr)->isa_oopptr();
2425         assert(adr->is_AddP() && atype != NULL &&
2426                atype->instance_id() == inst_id, "array's element offset should be processed first");
2427 #endif
2428       }
2429       igvn->hash_insert(addp);
2430     }
2431   }
2432   // Put on IGVN worklist since at least addp's type was changed above.
2433   record_for_optimizer(addp);
2434   return true;
2435 }
2436 
2437 //
2438 // Create a new version of orig_phi if necessary. Returns either the newly
2439 // created phi or an existing phi.  Sets create_new to indicate whether a new
2440 // phi was created.  Cache the last newly created phi in the node map.
2441 //
2442 PhiNode *ConnectionGraph::create_split_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist, bool &new_created) {
2443   Compile *C = _compile;
2444   PhaseGVN* igvn = _igvn;
2445   new_created = false;
2446   int phi_alias_idx = C->get_alias_index(orig_phi->adr_type());
2447   // nothing to do if orig_phi is bottom memory or matches alias_idx
2448   if (phi_alias_idx == alias_idx) {
2449     return orig_phi;
2450   }
2451   // Have we recently created a Phi for this alias index?
2452   PhiNode *result = get_map_phi(orig_phi->_idx);
2453   if (result != NULL && C->get_alias_index(result->adr_type()) == alias_idx) {
2454     return result;
2455   }
2456   // Previous check may fail when the same wide memory Phi was split into Phis
2457   // for different memory slices. Search all Phis for this region.
2458   if (result != NULL) {
2459     Node* region = orig_phi->in(0);
2460     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
2461       Node* phi = region->fast_out(i);
2462       if (phi->is_Phi() &&
2463           C->get_alias_index(phi->as_Phi()->adr_type()) == alias_idx) {
2464         assert(phi->_idx >= nodes_size(), "only new Phi per instance memory slice");
2465         return phi->as_Phi();
2466       }
2467     }
2468   }
2469   if (C->live_nodes() + 2*NodeLimitFudgeFactor > C->max_node_limit()) {
2470     if (C->do_escape_analysis() == true && !C->failing()) {
2471       // Retry compilation without escape analysis.
2472       // If this is the first failure, the sentinel string will "stick"
2473       // to the Compile object, and the C2Compiler will see it and retry.
2474       C->record_failure(C2Compiler::retry_no_escape_analysis());
2475     }
2476     return NULL;
2477   }
2478   orig_phi_worklist.append_if_missing(orig_phi);
2479   const TypePtr *atype = C->get_adr_type(alias_idx);
2480   result = PhiNode::make(orig_phi->in(0), NULL, Type::MEMORY, atype);
2481   C->copy_node_notes_to(result, orig_phi);
2482   igvn->set_type(result, result->bottom_type());
2483   record_for_optimizer(result);
2484   set_map(orig_phi, result);
2485   new_created = true;
2486   return result;
2487 }
2488 
2489 //
2490 // Return a new version of Memory Phi "orig_phi" with the inputs having the
2491 // specified alias index.
2492 //
2493 PhiNode *ConnectionGraph::split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist) {
2494   assert(alias_idx != Compile::AliasIdxBot, "can't split out bottom memory");
2495   Compile *C = _compile;
2496   PhaseGVN* igvn = _igvn;
2497   bool new_phi_created;
2498   PhiNode *result = create_split_phi(orig_phi, alias_idx, orig_phi_worklist, new_phi_created);
2499   if (!new_phi_created) {
2500     return result;
2501   }
2502   GrowableArray<PhiNode *>  phi_list;
2503   GrowableArray<uint>  cur_input;
2504   PhiNode *phi = orig_phi;
2505   uint idx = 1;
2506   bool finished = false;
2507   while(!finished) {
2508     while (idx < phi->req()) {
2509       Node *mem = find_inst_mem(phi->in(idx), alias_idx, orig_phi_worklist);
2510       if (mem != NULL && mem->is_Phi()) {
2511         PhiNode *newphi = create_split_phi(mem->as_Phi(), alias_idx, orig_phi_worklist, new_phi_created);
2512         if (new_phi_created) {
2513           // found an phi for which we created a new split, push current one on worklist and begin
2514           // processing new one
2515           phi_list.push(phi);
2516           cur_input.push(idx);
2517           phi = mem->as_Phi();
2518           result = newphi;
2519           idx = 1;
2520           continue;
2521         } else {
2522           mem = newphi;
2523         }
2524       }
2525       if (C->failing()) {
2526         return NULL;
2527       }
2528       result->set_req(idx++, mem);
2529     }
2530 #ifdef ASSERT
2531     // verify that the new Phi has an input for each input of the original
2532     assert( phi->req() == result->req(), "must have same number of inputs.");
2533     assert( result->in(0) != NULL && result->in(0) == phi->in(0), "regions must match");
2534 #endif
2535     // Check if all new phi's inputs have specified alias index.
2536     // Otherwise use old phi.
2537     for (uint i = 1; i < phi->req(); i++) {
2538       Node* in = result->in(i);
2539       assert((phi->in(i) == NULL) == (in == NULL), "inputs must correspond.");
2540     }
2541     // we have finished processing a Phi, see if there are any more to do
2542     finished = (phi_list.length() == 0 );
2543     if (!finished) {
2544       phi = phi_list.pop();
2545       idx = cur_input.pop();
2546       PhiNode *prev_result = get_map_phi(phi->_idx);
2547       prev_result->set_req(idx++, result);
2548       result = prev_result;
2549     }
2550   }
2551   return result;
2552 }
2553 
2554 //
2555 // The next methods are derived from methods in MemNode.
2556 //
2557 Node* ConnectionGraph::step_through_mergemem(MergeMemNode *mmem, int alias_idx, const TypeOopPtr *toop) {
2558   Node *mem = mmem;
2559   // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
2560   // means an array I have not precisely typed yet.  Do not do any
2561   // alias stuff with it any time soon.
2562   if (toop->base() != Type::AnyPtr &&
2563       !(toop->klass() != NULL &&
2564         toop->klass()->is_java_lang_Object() &&
2565         toop->offset() == Type::OffsetBot)) {
2566     mem = mmem->memory_at(alias_idx);
2567     // Update input if it is progress over what we have now
2568   }
2569   return mem;
2570 }
2571 
2572 //
2573 // Move memory users to their memory slices.
2574 //
2575 void ConnectionGraph::move_inst_mem(Node* n, GrowableArray<PhiNode *>  &orig_phis) {
2576   Compile* C = _compile;
2577   PhaseGVN* igvn = _igvn;
2578   const TypePtr* tp = igvn->type(n->in(MemNode::Address))->isa_ptr();
2579   assert(tp != NULL, "ptr type");
2580   int alias_idx = C->get_alias_index(tp);
2581   int general_idx = C->get_general_index(alias_idx);
2582 
2583   // Move users first
2584   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2585     Node* use = n->fast_out(i);
2586     if (use->is_MergeMem()) {
2587       MergeMemNode* mmem = use->as_MergeMem();
2588       assert(n == mmem->memory_at(alias_idx), "should be on instance memory slice");
2589       if (n != mmem->memory_at(general_idx) || alias_idx == general_idx) {
2590         continue; // Nothing to do
2591       }
2592       // Replace previous general reference to mem node.
2593       uint orig_uniq = C->unique();
2594       Node* m = find_inst_mem(n, general_idx, orig_phis);
2595       assert(orig_uniq == C->unique(), "no new nodes");
2596       mmem->set_memory_at(general_idx, m);
2597       --imax;
2598       --i;
2599     } else if (use->is_MemBar()) {
2600       assert(!use->is_Initialize(), "initializing stores should not be moved");
2601       if (use->req() > MemBarNode::Precedent &&
2602           use->in(MemBarNode::Precedent) == n) {
2603         // Don't move related membars.
2604         record_for_optimizer(use);
2605         continue;
2606       }
2607       tp = use->as_MemBar()->adr_type()->isa_ptr();
2608       if (tp != NULL && C->get_alias_index(tp) == alias_idx ||
2609           alias_idx == general_idx) {
2610         continue; // Nothing to do
2611       }
2612       // Move to general memory slice.
2613       uint orig_uniq = C->unique();
2614       Node* m = find_inst_mem(n, general_idx, orig_phis);
2615       assert(orig_uniq == C->unique(), "no new nodes");
2616       igvn->hash_delete(use);
2617       imax -= use->replace_edge(n, m);
2618       igvn->hash_insert(use);
2619       record_for_optimizer(use);
2620       --i;
2621 #ifdef ASSERT
2622     } else if (use->is_Mem()) {
2623       if (use->Opcode() == Op_StoreCM && use->in(MemNode::OopStore) == n) {
2624         // Don't move related cardmark.
2625         continue;
2626       }
2627       // Memory nodes should have new memory input.
2628       tp = igvn->type(use->in(MemNode::Address))->isa_ptr();
2629       assert(tp != NULL, "ptr type");
2630       int idx = C->get_alias_index(tp);
2631       assert(get_map(use->_idx) != NULL || idx == alias_idx,
2632              "Following memory nodes should have new memory input or be on the same memory slice");
2633     } else if (use->is_Phi()) {
2634       // Phi nodes should be split and moved already.
2635       tp = use->as_Phi()->adr_type()->isa_ptr();
2636       assert(tp != NULL, "ptr type");
2637       int idx = C->get_alias_index(tp);
2638       assert(idx == alias_idx, "Following Phi nodes should be on the same memory slice");
2639     } else {
2640       use->dump();
2641       assert(false, "should not be here");
2642 #endif
2643     }
2644   }
2645 }
2646 
2647 //
2648 // Search memory chain of "mem" to find a MemNode whose address
2649 // is the specified alias index.
2650 //
2651 Node* ConnectionGraph::find_inst_mem(Node *orig_mem, int alias_idx, GrowableArray<PhiNode *>  &orig_phis) {
2652   if (orig_mem == NULL)
2653     return orig_mem;
2654   Compile* C = _compile;
2655   PhaseGVN* igvn = _igvn;
2656   const TypeOopPtr *toop = C->get_adr_type(alias_idx)->isa_oopptr();
2657   bool is_instance = (toop != NULL) && toop->is_known_instance();
2658   Node *start_mem = C->start()->proj_out(TypeFunc::Memory);
2659   Node *prev = NULL;
2660   Node *result = orig_mem;
2661   while (prev != result) {
2662     prev = result;
2663     if (result == start_mem)
2664       break;  // hit one of our sentinels
2665     if (result->is_Mem()) {
2666       const Type *at = igvn->type(result->in(MemNode::Address));
2667       if (at == Type::TOP)
2668         break; // Dead
2669       assert (at->isa_ptr() != NULL, "pointer type required.");
2670       int idx = C->get_alias_index(at->is_ptr());
2671       if (idx == alias_idx)
2672         break; // Found
2673       if (!is_instance && (at->isa_oopptr() == NULL ||
2674                            !at->is_oopptr()->is_known_instance())) {
2675         break; // Do not skip store to general memory slice.
2676       }
2677       result = result->in(MemNode::Memory);
2678     }
2679     if (!is_instance)
2680       continue;  // don't search further for non-instance types
2681     // skip over a call which does not affect this memory slice
2682     if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
2683       Node *proj_in = result->in(0);
2684       if (proj_in->is_Allocate() && proj_in->_idx == (uint)toop->instance_id()) {
2685         break;  // hit one of our sentinels
2686       } else if (proj_in->is_Call()) {
2687         // ArrayCopy node processed here as well
2688         CallNode *call = proj_in->as_Call();
2689         if (!call->may_modify(toop, igvn)) {
2690           result = call->in(TypeFunc::Memory);
2691         }
2692       } else if (proj_in->is_Initialize()) {
2693         AllocateNode* alloc = proj_in->as_Initialize()->allocation();
2694         // Stop if this is the initialization for the object instance which
2695         // which contains this memory slice, otherwise skip over it.
2696         if (alloc == NULL || alloc->_idx != (uint)toop->instance_id()) {
2697           result = proj_in->in(TypeFunc::Memory);
2698         }
2699       } else if (proj_in->is_MemBar()) {
2700         if (proj_in->in(TypeFunc::Memory)->is_MergeMem() &&
2701             proj_in->in(TypeFunc::Memory)->as_MergeMem()->in(Compile::AliasIdxRaw)->is_Proj() &&
2702             proj_in->in(TypeFunc::Memory)->as_MergeMem()->in(Compile::AliasIdxRaw)->in(0)->is_ArrayCopy()) {
2703           // clone
2704           ArrayCopyNode* ac = proj_in->in(TypeFunc::Memory)->as_MergeMem()->in(Compile::AliasIdxRaw)->in(0)->as_ArrayCopy();
2705           if (ac->may_modify(toop, igvn)) {
2706             break;
2707           }
2708         }
2709         result = proj_in->in(TypeFunc::Memory);
2710       }
2711     } else if (result->is_MergeMem()) {
2712       MergeMemNode *mmem = result->as_MergeMem();
2713       result = step_through_mergemem(mmem, alias_idx, toop);
2714       if (result == mmem->base_memory()) {
2715         // Didn't find instance memory, search through general slice recursively.
2716         result = mmem->memory_at(C->get_general_index(alias_idx));
2717         result = find_inst_mem(result, alias_idx, orig_phis);
2718         if (C->failing()) {
2719           return NULL;
2720         }
2721         mmem->set_memory_at(alias_idx, result);
2722       }
2723     } else if (result->is_Phi() &&
2724                C->get_alias_index(result->as_Phi()->adr_type()) != alias_idx) {
2725       Node *un = result->as_Phi()->unique_input(igvn);
2726       if (un != NULL) {
2727         orig_phis.append_if_missing(result->as_Phi());
2728         result = un;
2729       } else {
2730         break;
2731       }
2732     } else if (result->is_ClearArray()) {
2733       if (!ClearArrayNode::step_through(&result, (uint)toop->instance_id(), igvn)) {
2734         // Can not bypass initialization of the instance
2735         // we are looking for.
2736         break;
2737       }
2738       // Otherwise skip it (the call updated 'result' value).
2739     } else if (result->Opcode() == Op_SCMemProj) {
2740       Node* mem = result->in(0);
2741       Node* adr = NULL;
2742       if (mem->is_LoadStore()) {
2743         adr = mem->in(MemNode::Address);
2744       } else {
2745         assert(mem->Opcode() == Op_EncodeISOArray ||
2746                mem->Opcode() == Op_StrCompressedCopy, "sanity");
2747         adr = mem->in(3); // Memory edge corresponds to destination array
2748       }
2749       const Type *at = igvn->type(adr);
2750       if (at != Type::TOP) {
2751         assert(at->isa_ptr() != NULL, "pointer type required.");
2752         int idx = C->get_alias_index(at->is_ptr());
2753         if (idx == alias_idx) {
2754           // Assert in debug mode
2755           assert(false, "Object is not scalar replaceable if a LoadStore node accesses its field");
2756           break; // In product mode return SCMemProj node
2757         }
2758       }
2759       result = mem->in(MemNode::Memory);
2760     } else if (result->Opcode() == Op_StrInflatedCopy) {
2761       Node* adr = result->in(3); // Memory edge corresponds to destination array
2762       const Type *at = igvn->type(adr);
2763       if (at != Type::TOP) {
2764         assert(at->isa_ptr() != NULL, "pointer type required.");
2765         int idx = C->get_alias_index(at->is_ptr());
2766         if (idx == alias_idx) {
2767           // Assert in debug mode
2768           assert(false, "Object is not scalar replaceable if a StrInflatedCopy node accesses its field");
2769           break; // In product mode return SCMemProj node
2770         }
2771       }
2772       result = result->in(MemNode::Memory);
2773     }
2774   }
2775   if (result->is_Phi()) {
2776     PhiNode *mphi = result->as_Phi();
2777     assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
2778     const TypePtr *t = mphi->adr_type();
2779     if (!is_instance) {
2780       // Push all non-instance Phis on the orig_phis worklist to update inputs
2781       // during Phase 4 if needed.
2782       orig_phis.append_if_missing(mphi);
2783     } else if (C->get_alias_index(t) != alias_idx) {
2784       // Create a new Phi with the specified alias index type.
2785       result = split_memory_phi(mphi, alias_idx, orig_phis);
2786     }
2787   }
2788   // the result is either MemNode, PhiNode, InitializeNode.
2789   return result;
2790 }
2791 
2792 //
2793 //  Convert the types of unescaped object to instance types where possible,
2794 //  propagate the new type information through the graph, and update memory
2795 //  edges and MergeMem inputs to reflect the new type.
2796 //
2797 //  We start with allocations (and calls which may be allocations)  on alloc_worklist.
2798 //  The processing is done in 4 phases:
2799 //
2800 //  Phase 1:  Process possible allocations from alloc_worklist.  Create instance
2801 //            types for the CheckCastPP for allocations where possible.
2802 //            Propagate the new types through users as follows:
2803 //               casts and Phi:  push users on alloc_worklist
2804 //               AddP:  cast Base and Address inputs to the instance type
2805 //                      push any AddP users on alloc_worklist and push any memnode
2806 //                      users onto memnode_worklist.
2807 //  Phase 2:  Process MemNode's from memnode_worklist. compute new address type and
2808 //            search the Memory chain for a store with the appropriate type
2809 //            address type.  If a Phi is found, create a new version with
2810 //            the appropriate memory slices from each of the Phi inputs.
2811 //            For stores, process the users as follows:
2812 //               MemNode:  push on memnode_worklist
2813 //               MergeMem: push on mergemem_worklist
2814 //  Phase 3:  Process MergeMem nodes from mergemem_worklist.  Walk each memory slice
2815 //            moving the first node encountered of each  instance type to the
2816 //            the input corresponding to its alias index.
2817 //            appropriate memory slice.
2818 //  Phase 4:  Update the inputs of non-instance memory Phis and the Memory input of memnodes.
2819 //
2820 // In the following example, the CheckCastPP nodes are the cast of allocation
2821 // results and the allocation of node 29 is unescaped and eligible to be an
2822 // instance type.
2823 //
2824 // We start with:
2825 //
2826 //     7 Parm #memory
2827 //    10  ConI  "12"
2828 //    19  CheckCastPP   "Foo"
2829 //    20  AddP  _ 19 19 10  Foo+12  alias_index=4
2830 //    29  CheckCastPP   "Foo"
2831 //    30  AddP  _ 29 29 10  Foo+12  alias_index=4
2832 //
2833 //    40  StoreP  25   7  20   ... alias_index=4
2834 //    50  StoreP  35  40  30   ... alias_index=4
2835 //    60  StoreP  45  50  20   ... alias_index=4
2836 //    70  LoadP    _  60  30   ... alias_index=4
2837 //    80  Phi     75  50  60   Memory alias_index=4
2838 //    90  LoadP    _  80  30   ... alias_index=4
2839 //   100  LoadP    _  80  20   ... alias_index=4
2840 //
2841 //
2842 // Phase 1 creates an instance type for node 29 assigning it an instance id of 24
2843 // and creating a new alias index for node 30.  This gives:
2844 //
2845 //     7 Parm #memory
2846 //    10  ConI  "12"
2847 //    19  CheckCastPP   "Foo"
2848 //    20  AddP  _ 19 19 10  Foo+12  alias_index=4
2849 //    29  CheckCastPP   "Foo"  iid=24
2850 //    30  AddP  _ 29 29 10  Foo+12  alias_index=6  iid=24
2851 //
2852 //    40  StoreP  25   7  20   ... alias_index=4
2853 //    50  StoreP  35  40  30   ... alias_index=6
2854 //    60  StoreP  45  50  20   ... alias_index=4
2855 //    70  LoadP    _  60  30   ... alias_index=6
2856 //    80  Phi     75  50  60   Memory alias_index=4
2857 //    90  LoadP    _  80  30   ... alias_index=6
2858 //   100  LoadP    _  80  20   ... alias_index=4
2859 //
2860 // In phase 2, new memory inputs are computed for the loads and stores,
2861 // And a new version of the phi is created.  In phase 4, the inputs to
2862 // node 80 are updated and then the memory nodes are updated with the
2863 // values computed in phase 2.  This results in:
2864 //
2865 //     7 Parm #memory
2866 //    10  ConI  "12"
2867 //    19  CheckCastPP   "Foo"
2868 //    20  AddP  _ 19 19 10  Foo+12  alias_index=4
2869 //    29  CheckCastPP   "Foo"  iid=24
2870 //    30  AddP  _ 29 29 10  Foo+12  alias_index=6  iid=24
2871 //
2872 //    40  StoreP  25  7   20   ... alias_index=4
2873 //    50  StoreP  35  7   30   ... alias_index=6
2874 //    60  StoreP  45  40  20   ... alias_index=4
2875 //    70  LoadP    _  50  30   ... alias_index=6
2876 //    80  Phi     75  40  60   Memory alias_index=4
2877 //   120  Phi     75  50  50   Memory alias_index=6
2878 //    90  LoadP    _ 120  30   ... alias_index=6
2879 //   100  LoadP    _  80  20   ... alias_index=4
2880 //
2881 void ConnectionGraph::split_unique_types(GrowableArray<Node *>  &alloc_worklist, GrowableArray<ArrayCopyNode*> &arraycopy_worklist) {
2882   GrowableArray<Node *>  memnode_worklist;
2883   GrowableArray<PhiNode *>  orig_phis;
2884   PhaseIterGVN  *igvn = _igvn;
2885   uint new_index_start = (uint) _compile->num_alias_types();
2886   Arena* arena = Thread::current()->resource_area();
2887   VectorSet visited(arena);
2888   ideal_nodes.clear(); // Reset for use with set_map/get_map.
2889   uint unique_old = _compile->unique();
2890 
2891   //  Phase 1:  Process possible allocations from alloc_worklist.
2892   //  Create instance types for the CheckCastPP for allocations where possible.
2893   //
2894   // (Note: don't forget to change the order of the second AddP node on
2895   //  the alloc_worklist if the order of the worklist processing is changed,
2896   //  see the comment in find_second_addp().)
2897   //
2898   while (alloc_worklist.length() != 0) {
2899     Node *n = alloc_worklist.pop();
2900     uint ni = n->_idx;
2901     if (n->is_Call()) {
2902       CallNode *alloc = n->as_Call();
2903       // copy escape information to call node
2904       PointsToNode* ptn = ptnode_adr(alloc->_idx);
2905       PointsToNode::EscapeState es = ptn->escape_state();
2906       // We have an allocation or call which returns a Java object,
2907       // see if it is unescaped.
2908       if (es != PointsToNode::NoEscape || !ptn->scalar_replaceable())
2909         continue;
2910       // Find CheckCastPP for the allocate or for the return value of a call
2911       n = alloc->result_cast();
2912       if (n == NULL) {            // No uses except Initialize node
2913         if (alloc->is_Allocate()) {
2914           // Set the scalar_replaceable flag for allocation
2915           // so it could be eliminated if it has no uses.
2916           alloc->as_Allocate()->_is_scalar_replaceable = true;
2917         }
2918         if (alloc->is_CallStaticJava()) {
2919           // Set the scalar_replaceable flag for boxing method
2920           // so it could be eliminated if it has no uses.
2921           alloc->as_CallStaticJava()->_is_scalar_replaceable = true;
2922         }
2923         continue;
2924       }
2925       if (!n->is_CheckCastPP()) { // not unique CheckCastPP.
2926         assert(!alloc->is_Allocate(), "allocation should have unique type");
2927         continue;
2928       }
2929 
2930       // The inline code for Object.clone() casts the allocation result to
2931       // java.lang.Object and then to the actual type of the allocated
2932       // object. Detect this case and use the second cast.
2933       // Also detect j.l.reflect.Array.newInstance(jobject, jint) case when
2934       // the allocation result is cast to java.lang.Object and then
2935       // to the actual Array type.
2936       if (alloc->is_Allocate() && n->as_Type()->type() == TypeInstPtr::NOTNULL
2937           && (alloc->is_AllocateArray() ||
2938               igvn->type(alloc->in(AllocateNode::KlassNode)) != TypeKlassPtr::OBJECT)) {
2939         Node *cast2 = NULL;
2940         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2941           Node *use = n->fast_out(i);
2942           if (use->is_CheckCastPP()) {
2943             cast2 = use;
2944             break;
2945           }
2946         }
2947         if (cast2 != NULL) {
2948           n = cast2;
2949         } else {
2950           // Non-scalar replaceable if the allocation type is unknown statically
2951           // (reflection allocation), the object can't be restored during
2952           // deoptimization without precise type.
2953           continue;
2954         }
2955       }
2956 
2957       const TypeOopPtr *t = igvn->type(n)->isa_oopptr();
2958       if (t == NULL)
2959         continue;  // not a TypeOopPtr
2960       if (!t->klass_is_exact())
2961         continue; // not an unique type
2962 
2963       if (alloc->is_Allocate()) {
2964         // Set the scalar_replaceable flag for allocation
2965         // so it could be eliminated.
2966         alloc->as_Allocate()->_is_scalar_replaceable = true;
2967       }
2968       if (alloc->is_CallStaticJava()) {
2969         // Set the scalar_replaceable flag for boxing method
2970         // so it could be eliminated.
2971         alloc->as_CallStaticJava()->_is_scalar_replaceable = true;
2972       }
2973       set_escape_state(ptnode_adr(n->_idx), es); // CheckCastPP escape state
2974       // in order for an object to be scalar-replaceable, it must be:
2975       //   - a direct allocation (not a call returning an object)
2976       //   - non-escaping
2977       //   - eligible to be a unique type
2978       //   - not determined to be ineligible by escape analysis
2979       set_map(alloc, n);
2980       set_map(n, alloc);
2981       const TypeOopPtr* tinst = t->cast_to_instance_id(ni);
2982       igvn->hash_delete(n);
2983       igvn->set_type(n,  tinst);
2984       n->raise_bottom_type(tinst);
2985       igvn->hash_insert(n);
2986       record_for_optimizer(n);
2987       if (alloc->is_Allocate() && (t->isa_instptr() || t->isa_aryptr())) {
2988 
2989         // First, put on the worklist all Field edges from Connection Graph
2990         // which is more accurate than putting immediate users from Ideal Graph.
2991         for (EdgeIterator e(ptn); e.has_next(); e.next()) {
2992           PointsToNode* tgt = e.get();
2993           if (tgt->is_Arraycopy()) {
2994             continue;
2995           }
2996           Node* use = tgt->ideal_node();
2997           assert(tgt->is_Field() && use->is_AddP(),
2998                  "only AddP nodes are Field edges in CG");
2999           if (use->outcnt() > 0) { // Don't process dead nodes
3000             Node* addp2 = find_second_addp(use, use->in(AddPNode::Base));
3001             if (addp2 != NULL) {
3002               assert(alloc->is_AllocateArray(),"array allocation was expected");
3003               alloc_worklist.append_if_missing(addp2);
3004             }
3005             alloc_worklist.append_if_missing(use);
3006           }
3007         }
3008 
3009         // An allocation may have an Initialize which has raw stores. Scan
3010         // the users of the raw allocation result and push AddP users
3011         // on alloc_worklist.
3012         Node *raw_result = alloc->proj_out(TypeFunc::Parms);
3013         assert (raw_result != NULL, "must have an allocation result");
3014         for (DUIterator_Fast imax, i = raw_result->fast_outs(imax); i < imax; i++) {
3015           Node *use = raw_result->fast_out(i);
3016           if (use->is_AddP() && use->outcnt() > 0) { // Don't process dead nodes
3017             Node* addp2 = find_second_addp(use, raw_result);
3018             if (addp2 != NULL) {
3019               assert(alloc->is_AllocateArray(),"array allocation was expected");
3020               alloc_worklist.append_if_missing(addp2);
3021             }
3022             alloc_worklist.append_if_missing(use);
3023           } else if (use->is_MemBar()) {
3024             memnode_worklist.append_if_missing(use);
3025           }
3026         }
3027       }
3028     } else if (n->is_AddP()) {
3029       JavaObjectNode* jobj = unique_java_object(get_addp_base(n));
3030       if (jobj == NULL || jobj == phantom_obj) {
3031 #ifdef ASSERT
3032         ptnode_adr(get_addp_base(n)->_idx)->dump();
3033         ptnode_adr(n->_idx)->dump();
3034         assert(jobj != NULL && jobj != phantom_obj, "escaped allocation");
3035 #endif
3036         _compile->record_failure(C2Compiler::retry_no_escape_analysis());
3037         return;
3038       }
3039       Node *base = get_map(jobj->idx());  // CheckCastPP node
3040       if (!split_AddP(n, base)) continue; // wrong type from dead path
3041     } else if (n->is_Phi() ||
3042                n->is_CheckCastPP() ||
3043                n->is_EncodeP() ||
3044                n->is_DecodeN() ||
3045                (n->is_ConstraintCast() && n->Opcode() == Op_CastPP)) {
3046       if (visited.test_set(n->_idx)) {
3047         assert(n->is_Phi(), "loops only through Phi's");
3048         continue;  // already processed
3049       }
3050       JavaObjectNode* jobj = unique_java_object(n);
3051       if (jobj == NULL || jobj == phantom_obj) {
3052 #ifdef ASSERT
3053         ptnode_adr(n->_idx)->dump();
3054         assert(jobj != NULL && jobj != phantom_obj, "escaped allocation");
3055 #endif
3056         _compile->record_failure(C2Compiler::retry_no_escape_analysis());
3057         return;
3058       } else {
3059         Node *val = get_map(jobj->idx());   // CheckCastPP node
3060         TypeNode *tn = n->as_Type();
3061         const TypeOopPtr* tinst = igvn->type(val)->isa_oopptr();
3062         assert(tinst != NULL && tinst->is_known_instance() &&
3063                tinst->instance_id() == jobj->idx() , "instance type expected.");
3064 
3065         const Type *tn_type = igvn->type(tn);
3066         const TypeOopPtr *tn_t;
3067         if (tn_type->isa_narrowoop()) {
3068           tn_t = tn_type->make_ptr()->isa_oopptr();
3069         } else {
3070           tn_t = tn_type->isa_oopptr();
3071         }
3072         if (tn_t != NULL && tinst->klass()->is_subtype_of(tn_t->klass())) {
3073           if (tn_type->isa_narrowoop()) {
3074             tn_type = tinst->make_narrowoop();
3075           } else {
3076             tn_type = tinst;
3077           }
3078           igvn->hash_delete(tn);
3079           igvn->set_type(tn, tn_type);
3080           tn->set_type(tn_type);
3081           igvn->hash_insert(tn);
3082           record_for_optimizer(n);
3083         } else {
3084           assert(tn_type == TypePtr::NULL_PTR ||
3085                  tn_t != NULL && !tinst->klass()->is_subtype_of(tn_t->klass()),
3086                  "unexpected type");
3087           continue; // Skip dead path with different type
3088         }
3089       }
3090     } else {
3091       debug_only(n->dump();)
3092       assert(false, "EA: unexpected node");
3093       continue;
3094     }
3095     // push allocation's users on appropriate worklist
3096     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3097       Node *use = n->fast_out(i);
3098       if(use->is_Mem() && use->in(MemNode::Address) == n) {
3099         // Load/store to instance's field
3100         memnode_worklist.append_if_missing(use);
3101       } else if (use->is_MemBar()) {
3102         if (use->in(TypeFunc::Memory) == n) { // Ignore precedent edge
3103           memnode_worklist.append_if_missing(use);
3104         }
3105       } else if (use->is_AddP() && use->outcnt() > 0) { // No dead nodes
3106         Node* addp2 = find_second_addp(use, n);
3107         if (addp2 != NULL) {
3108           alloc_worklist.append_if_missing(addp2);
3109         }
3110         alloc_worklist.append_if_missing(use);
3111       } else if (use->is_Phi() ||
3112                  use->is_CheckCastPP() ||
3113                  use->is_EncodeNarrowPtr() ||
3114                  use->is_DecodeNarrowPtr() ||
3115                  (use->is_ConstraintCast() && use->Opcode() == Op_CastPP)) {
3116         alloc_worklist.append_if_missing(use);
3117 #ifdef ASSERT
3118       } else if (use->is_Mem()) {
3119         assert(use->in(MemNode::Address) != n, "EA: missing allocation reference path");
3120       } else if (use->is_MergeMem()) {
3121         assert(_mergemem_worklist.contains(use->as_MergeMem()), "EA: missing MergeMem node in the worklist");
3122       } else if (use->is_SafePoint()) {
3123         // Look for MergeMem nodes for calls which reference unique allocation
3124         // (through CheckCastPP nodes) even for debug info.
3125         Node* m = use->in(TypeFunc::Memory);
3126         if (m->is_MergeMem()) {
3127           assert(_mergemem_worklist.contains(m->as_MergeMem()), "EA: missing MergeMem node in the worklist");
3128         }
3129       } else if (use->Opcode() == Op_EncodeISOArray) {
3130         if (use->in(MemNode::Memory) == n || use->in(3) == n) {
3131           // EncodeISOArray overwrites destination array
3132           memnode_worklist.append_if_missing(use);
3133         }
3134       } else {
3135         uint op = use->Opcode();
3136         if ((use->in(MemNode::Memory) == n) &&
3137             (op == Op_StrCompressedCopy || op == Op_StrInflatedCopy)) {
3138           // They overwrite memory edge corresponding to destination array,
3139           memnode_worklist.append_if_missing(use);
3140         } else if (!(op == Op_CmpP || op == Op_Conv2B ||
3141               op == Op_CastP2X || op == Op_StoreCM ||
3142               op == Op_FastLock || op == Op_AryEq || op == Op_StrComp || op == Op_HasNegatives ||
3143               op == Op_StrCompressedCopy || op == Op_StrInflatedCopy ||
3144               op == Op_StrEquals || op == Op_StrIndexOf || op == Op_StrIndexOfChar)) {
3145           n->dump();
3146           use->dump();
3147           assert(false, "EA: missing allocation reference path");
3148         }
3149 #endif
3150       }
3151     }
3152 
3153   }
3154 
3155   // Go over all ArrayCopy nodes and if one of the inputs has a unique
3156   // type, record it in the ArrayCopy node so we know what memory this
3157   // node uses/modified.
3158   for (int next = 0; next < arraycopy_worklist.length(); next++) {
3159     ArrayCopyNode* ac = arraycopy_worklist.at(next);
3160     Node* dest = ac->in(ArrayCopyNode::Dest);
3161     if (dest->is_AddP()) {
3162       dest = get_addp_base(dest);
3163     }
3164     JavaObjectNode* jobj = unique_java_object(dest);
3165     if (jobj != NULL) {
3166       Node *base = get_map(jobj->idx());
3167       if (base != NULL) {
3168         const TypeOopPtr *base_t = _igvn->type(base)->isa_oopptr();
3169         ac->_dest_type = base_t;
3170       }
3171     }
3172     Node* src = ac->in(ArrayCopyNode::Src);
3173     if (src->is_AddP()) {
3174       src = get_addp_base(src);
3175     }
3176     jobj = unique_java_object(src);
3177     if (jobj != NULL) {
3178       Node* base = get_map(jobj->idx());
3179       if (base != NULL) {
3180         const TypeOopPtr *base_t = _igvn->type(base)->isa_oopptr();
3181         ac->_src_type = base_t;
3182       }
3183     }
3184   }
3185 
3186   // New alias types were created in split_AddP().
3187   uint new_index_end = (uint) _compile->num_alias_types();
3188   assert(unique_old == _compile->unique(), "there should be no new ideal nodes after Phase 1");
3189 
3190   //  Phase 2:  Process MemNode's from memnode_worklist. compute new address type and
3191   //            compute new values for Memory inputs  (the Memory inputs are not
3192   //            actually updated until phase 4.)
3193   if (memnode_worklist.length() == 0)
3194     return;  // nothing to do
3195   while (memnode_worklist.length() != 0) {
3196     Node *n = memnode_worklist.pop();
3197     if (visited.test_set(n->_idx))
3198       continue;
3199     if (n->is_Phi() || n->is_ClearArray()) {
3200       // we don't need to do anything, but the users must be pushed
3201     } else if (n->is_MemBar()) { // Initialize, MemBar nodes
3202       // we don't need to do anything, but the users must be pushed
3203       n = n->as_MemBar()->proj_out(TypeFunc::Memory);
3204       if (n == NULL)
3205         continue;
3206     } else if (n->Opcode() == Op_StrCompressedCopy ||
3207                n->Opcode() == Op_EncodeISOArray) {
3208       // get the memory projection
3209       n = n->find_out_with(Op_SCMemProj);
3210       assert(n->Opcode() == Op_SCMemProj, "memory projection required");
3211     } else {
3212       assert(n->is_Mem(), "memory node required.");
3213       Node *addr = n->in(MemNode::Address);
3214       const Type *addr_t = igvn->type(addr);
3215       if (addr_t == Type::TOP)
3216         continue;
3217       assert (addr_t->isa_ptr() != NULL, "pointer type required.");
3218       int alias_idx = _compile->get_alias_index(addr_t->is_ptr());
3219       assert ((uint)alias_idx < new_index_end, "wrong alias index");
3220       Node *mem = find_inst_mem(n->in(MemNode::Memory), alias_idx, orig_phis);
3221       if (_compile->failing()) {
3222         return;
3223       }
3224       if (mem != n->in(MemNode::Memory)) {
3225         // We delay the memory edge update since we need old one in
3226         // MergeMem code below when instances memory slices are separated.
3227         set_map(n, mem);
3228       }
3229       if (n->is_Load()) {
3230         continue;  // don't push users
3231       } else if (n->is_LoadStore()) {
3232         // get the memory projection
3233         n = n->find_out_with(Op_SCMemProj);
3234         assert(n->Opcode() == Op_SCMemProj, "memory projection required");
3235       }
3236     }
3237     // push user on appropriate worklist
3238     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3239       Node *use = n->fast_out(i);
3240       if (use->is_Phi() || use->is_ClearArray()) {
3241         memnode_worklist.append_if_missing(use);
3242       } else if (use->is_Mem() && use->in(MemNode::Memory) == n) {
3243         if (use->Opcode() == Op_StoreCM) // Ignore cardmark stores
3244           continue;
3245         memnode_worklist.append_if_missing(use);
3246       } else if (use->is_MemBar()) {
3247         if (use->in(TypeFunc::Memory) == n) { // Ignore precedent edge
3248           memnode_worklist.append_if_missing(use);
3249         }
3250 #ifdef ASSERT
3251       } else if(use->is_Mem()) {
3252         assert(use->in(MemNode::Memory) != n, "EA: missing memory path");
3253       } else if (use->is_MergeMem()) {
3254         assert(_mergemem_worklist.contains(use->as_MergeMem()), "EA: missing MergeMem node in the worklist");
3255       } else if (use->Opcode() == Op_EncodeISOArray) {
3256         if (use->in(MemNode::Memory) == n || use->in(3) == n) {
3257           // EncodeISOArray overwrites destination array
3258           memnode_worklist.append_if_missing(use);
3259         }
3260       } else {
3261         uint op = use->Opcode();
3262         if ((use->in(MemNode::Memory) == n) &&
3263             (op == Op_StrCompressedCopy || op == Op_StrInflatedCopy)) {
3264           // They overwrite memory edge corresponding to destination array,
3265           memnode_worklist.append_if_missing(use);
3266         } else if (!(op == Op_StoreCM ||
3267               (op == Op_CallLeaf && use->as_CallLeaf()->_name != NULL &&
3268                strcmp(use->as_CallLeaf()->_name, "g1_wb_pre") == 0) ||
3269               op == Op_AryEq || op == Op_StrComp || op == Op_HasNegatives ||
3270               op == Op_StrCompressedCopy || op == Op_StrInflatedCopy ||
3271               op == Op_StrEquals || op == Op_StrIndexOf || op == Op_StrIndexOfChar)) {
3272           n->dump();
3273           use->dump();
3274           assert(false, "EA: missing memory path");
3275         }
3276 #endif
3277       }
3278     }
3279   }
3280 
3281   //  Phase 3:  Process MergeMem nodes from mergemem_worklist.
3282   //            Walk each memory slice moving the first node encountered of each
3283   //            instance type to the the input corresponding to its alias index.
3284   uint length = _mergemem_worklist.length();
3285   for( uint next = 0; next < length; ++next ) {
3286     MergeMemNode* nmm = _mergemem_worklist.at(next);
3287     assert(!visited.test_set(nmm->_idx), "should not be visited before");
3288     // Note: we don't want to use MergeMemStream here because we only want to
3289     // scan inputs which exist at the start, not ones we add during processing.
3290     // Note 2: MergeMem may already contains instance memory slices added
3291     // during find_inst_mem() call when memory nodes were processed above.
3292     igvn->hash_delete(nmm);
3293     uint nslices = MIN2(nmm->req(), new_index_start);
3294     for (uint i = Compile::AliasIdxRaw+1; i < nslices; i++) {
3295       Node* mem = nmm->in(i);
3296       Node* cur = NULL;
3297       if (mem == NULL || mem->is_top())
3298         continue;
3299       // First, update mergemem by moving memory nodes to corresponding slices
3300       // if their type became more precise since this mergemem was created.
3301       while (mem->is_Mem()) {
3302         const Type *at = igvn->type(mem->in(MemNode::Address));
3303         if (at != Type::TOP) {
3304           assert (at->isa_ptr() != NULL, "pointer type required.");
3305           uint idx = (uint)_compile->get_alias_index(at->is_ptr());
3306           if (idx == i) {
3307             if (cur == NULL)
3308               cur = mem;
3309           } else {
3310             if (idx >= nmm->req() || nmm->is_empty_memory(nmm->in(idx))) {
3311               nmm->set_memory_at(idx, mem);
3312             }
3313           }
3314         }
3315         mem = mem->in(MemNode::Memory);
3316       }
3317       nmm->set_memory_at(i, (cur != NULL) ? cur : mem);
3318       // Find any instance of the current type if we haven't encountered
3319       // already a memory slice of the instance along the memory chain.
3320       for (uint ni = new_index_start; ni < new_index_end; ni++) {
3321         if((uint)_compile->get_general_index(ni) == i) {
3322           Node *m = (ni >= nmm->req()) ? nmm->empty_memory() : nmm->in(ni);
3323           if (nmm->is_empty_memory(m)) {
3324             Node* result = find_inst_mem(mem, ni, orig_phis);
3325             if (_compile->failing()) {
3326               return;
3327             }
3328             nmm->set_memory_at(ni, result);
3329           }
3330         }
3331       }
3332     }
3333     // Find the rest of instances values
3334     for (uint ni = new_index_start; ni < new_index_end; ni++) {
3335       const TypeOopPtr *tinst = _compile->get_adr_type(ni)->isa_oopptr();
3336       Node* result = step_through_mergemem(nmm, ni, tinst);
3337       if (result == nmm->base_memory()) {
3338         // Didn't find instance memory, search through general slice recursively.
3339         result = nmm->memory_at(_compile->get_general_index(ni));
3340         result = find_inst_mem(result, ni, orig_phis);
3341         if (_compile->failing()) {
3342           return;
3343         }
3344         nmm->set_memory_at(ni, result);
3345       }
3346     }
3347     igvn->hash_insert(nmm);
3348     record_for_optimizer(nmm);
3349   }
3350 
3351   //  Phase 4:  Update the inputs of non-instance memory Phis and
3352   //            the Memory input of memnodes
3353   // First update the inputs of any non-instance Phi's from
3354   // which we split out an instance Phi.  Note we don't have
3355   // to recursively process Phi's encounted on the input memory
3356   // chains as is done in split_memory_phi() since they  will
3357   // also be processed here.
3358   for (int j = 0; j < orig_phis.length(); j++) {
3359     PhiNode *phi = orig_phis.at(j);
3360     int alias_idx = _compile->get_alias_index(phi->adr_type());
3361     igvn->hash_delete(phi);
3362     for (uint i = 1; i < phi->req(); i++) {
3363       Node *mem = phi->in(i);
3364       Node *new_mem = find_inst_mem(mem, alias_idx, orig_phis);
3365       if (_compile->failing()) {
3366         return;
3367       }
3368       if (mem != new_mem) {
3369         phi->set_req(i, new_mem);
3370       }
3371     }
3372     igvn->hash_insert(phi);
3373     record_for_optimizer(phi);
3374   }
3375 
3376   // Update the memory inputs of MemNodes with the value we computed
3377   // in Phase 2 and move stores memory users to corresponding memory slices.
3378   // Disable memory split verification code until the fix for 6984348.
3379   // Currently it produces false negative results since it does not cover all cases.
3380 #if 0 // ifdef ASSERT
3381   visited.Reset();
3382   Node_Stack old_mems(arena, _compile->unique() >> 2);
3383 #endif
3384   for (uint i = 0; i < ideal_nodes.size(); i++) {
3385     Node*    n = ideal_nodes.at(i);
3386     Node* nmem = get_map(n->_idx);
3387     assert(nmem != NULL, "sanity");
3388     if (n->is_Mem()) {
3389 #if 0 // ifdef ASSERT
3390       Node* old_mem = n->in(MemNode::Memory);
3391       if (!visited.test_set(old_mem->_idx)) {
3392         old_mems.push(old_mem, old_mem->outcnt());
3393       }
3394 #endif
3395       assert(n->in(MemNode::Memory) != nmem, "sanity");
3396       if (!n->is_Load()) {
3397         // Move memory users of a store first.
3398         move_inst_mem(n, orig_phis);
3399       }
3400       // Now update memory input
3401       igvn->hash_delete(n);
3402       n->set_req(MemNode::Memory, nmem);
3403       igvn->hash_insert(n);
3404       record_for_optimizer(n);
3405     } else {
3406       assert(n->is_Allocate() || n->is_CheckCastPP() ||
3407              n->is_AddP() || n->is_Phi(), "unknown node used for set_map()");
3408     }
3409   }
3410 #if 0 // ifdef ASSERT
3411   // Verify that memory was split correctly
3412   while (old_mems.is_nonempty()) {
3413     Node* old_mem = old_mems.node();
3414     uint  old_cnt = old_mems.index();
3415     old_mems.pop();
3416     assert(old_cnt == old_mem->outcnt(), "old mem could be lost");
3417   }
3418 #endif
3419 }
3420 
3421 #ifndef PRODUCT
3422 static const char *node_type_names[] = {
3423   "UnknownType",
3424   "JavaObject",
3425   "LocalVar",
3426   "Field",
3427   "Arraycopy"
3428 };
3429 
3430 static const char *esc_names[] = {
3431   "UnknownEscape",
3432   "NoEscape",
3433   "ArgEscape",
3434   "GlobalEscape"
3435 };
3436 
3437 void PointsToNode::dump(bool print_state) const {
3438   NodeType nt = node_type();
3439   tty->print("%s ", node_type_names[(int) nt]);
3440   if (print_state) {
3441     EscapeState es = escape_state();
3442     EscapeState fields_es = fields_escape_state();
3443     tty->print("%s(%s) ", esc_names[(int)es], esc_names[(int)fields_es]);
3444     if (nt == PointsToNode::JavaObject && !this->scalar_replaceable())
3445       tty->print("NSR ");
3446   }
3447   if (is_Field()) {
3448     FieldNode* f = (FieldNode*)this;
3449     if (f->is_oop())
3450       tty->print("oop ");
3451     if (f->offset() > 0)
3452       tty->print("+%d ", f->offset());
3453     tty->print("(");
3454     for (BaseIterator i(f); i.has_next(); i.next()) {
3455       PointsToNode* b = i.get();
3456       tty->print(" %d%s", b->idx(),(b->is_JavaObject() ? "P" : ""));
3457     }
3458     tty->print(" )");
3459   }
3460   tty->print("[");
3461   for (EdgeIterator i(this); i.has_next(); i.next()) {
3462     PointsToNode* e = i.get();
3463     tty->print(" %d%s%s", e->idx(),(e->is_JavaObject() ? "P" : (e->is_Field() ? "F" : "")), e->is_Arraycopy() ? "cp" : "");
3464   }
3465   tty->print(" [");
3466   for (UseIterator i(this); i.has_next(); i.next()) {
3467     PointsToNode* u = i.get();
3468     bool is_base = false;
3469     if (PointsToNode::is_base_use(u)) {
3470       is_base = true;
3471       u = PointsToNode::get_use_node(u)->as_Field();
3472     }
3473     tty->print(" %d%s%s", u->idx(), is_base ? "b" : "", u->is_Arraycopy() ? "cp" : "");
3474   }
3475   tty->print(" ]]  ");
3476   if (_node == NULL)
3477     tty->print_cr("<null>");
3478   else
3479     _node->dump();
3480 }
3481 
3482 void ConnectionGraph::dump(GrowableArray<PointsToNode*>& ptnodes_worklist) {
3483   bool first = true;
3484   int ptnodes_length = ptnodes_worklist.length();
3485   for (int i = 0; i < ptnodes_length; i++) {
3486     PointsToNode *ptn = ptnodes_worklist.at(i);
3487     if (ptn == NULL || !ptn->is_JavaObject())
3488       continue;
3489     PointsToNode::EscapeState es = ptn->escape_state();
3490     if ((es != PointsToNode::NoEscape) && !Verbose) {
3491       continue;
3492     }
3493     Node* n = ptn->ideal_node();
3494     if (n->is_Allocate() || (n->is_CallStaticJava() &&
3495                              n->as_CallStaticJava()->is_boxing_method())) {
3496       if (first) {
3497         tty->cr();
3498         tty->print("======== Connection graph for ");
3499         _compile->method()->print_short_name();
3500         tty->cr();
3501         first = false;
3502       }
3503       ptn->dump();
3504       // Print all locals and fields which reference this allocation
3505       for (UseIterator j(ptn); j.has_next(); j.next()) {
3506         PointsToNode* use = j.get();
3507         if (use->is_LocalVar()) {
3508           use->dump(Verbose);
3509         } else if (Verbose) {
3510           use->dump();
3511         }
3512       }
3513       tty->cr();
3514     }
3515   }
3516 }
3517 #endif