1 /*
   2  * Copyright (c) 2005, 2025, 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 "ci/bcEscapeAnalyzer.hpp"
  26 #include "compiler/compileLog.hpp"
  27 #include "gc/shared/barrierSet.hpp"
  28 #include "gc/shared/c2/barrierSetC2.hpp"
  29 #include "libadt/vectset.hpp"
  30 #include "memory/allocation.hpp"
  31 #include "memory/resourceArea.hpp"
  32 #include "opto/c2compiler.hpp"
  33 #include "opto/arraycopynode.hpp"
  34 #include "opto/callnode.hpp"
  35 #include "opto/cfgnode.hpp"
  36 #include "opto/compile.hpp"
  37 #include "opto/escape.hpp"
  38 #include "opto/macro.hpp"
  39 #include "opto/locknode.hpp"
  40 #include "opto/phaseX.hpp"
  41 #include "opto/movenode.hpp"
  42 #include "opto/narrowptrnode.hpp"
  43 #include "opto/castnode.hpp"
  44 #include "opto/rootnode.hpp"
  45 #include "utilities/macros.hpp"
  46 
  47 ConnectionGraph::ConnectionGraph(Compile * C, PhaseIterGVN *igvn, int invocation) :
  48   // If ReduceAllocationMerges is enabled we might call split_through_phi during
  49   // split_unique_types and that will create additional nodes that need to be
  50   // pushed to the ConnectionGraph. The code below bumps the initial capacity of
  51   // _nodes by 10% to account for these additional nodes. If capacity is exceeded
  52   // the array will be reallocated.
  53   _nodes(C->comp_arena(), C->do_reduce_allocation_merges() ? C->unique()*1.10 : C->unique(), C->unique(), nullptr),
  54   _in_worklist(C->comp_arena()),
  55   _next_pidx(0),
  56   _collecting(true),
  57   _verify(false),
  58   _compile(C),
  59   _igvn(igvn),
  60   _invocation(invocation),
  61   _build_iterations(0),
  62   _build_time(0.),
  63   _node_map(C->comp_arena()) {
  64   // Add unknown java object.
  65   add_java_object(C->top(), PointsToNode::GlobalEscape);
  66   phantom_obj = ptnode_adr(C->top()->_idx)->as_JavaObject();
  67   set_not_scalar_replaceable(phantom_obj NOT_PRODUCT(COMMA "Phantom object"));
  68   // Add ConP and ConN null oop nodes
  69   Node* oop_null = igvn->zerocon(T_OBJECT);
  70   assert(oop_null->_idx < nodes_size(), "should be created already");
  71   add_java_object(oop_null, PointsToNode::NoEscape);
  72   null_obj = ptnode_adr(oop_null->_idx)->as_JavaObject();
  73   set_not_scalar_replaceable(null_obj NOT_PRODUCT(COMMA "Null object"));
  74   if (UseCompressedOops) {
  75     Node* noop_null = igvn->zerocon(T_NARROWOOP);
  76     assert(noop_null->_idx < nodes_size(), "should be created already");
  77     map_ideal_node(noop_null, null_obj);
  78   }
  79 }
  80 
  81 bool ConnectionGraph::has_candidates(Compile *C) {
  82   // EA brings benefits only when the code has allocations and/or locks which
  83   // are represented by ideal Macro nodes.
  84   int cnt = C->macro_count();
  85   for (int i = 0; i < cnt; i++) {
  86     Node *n = C->macro_node(i);
  87     if (n->is_Allocate()) {
  88       return true;
  89     }
  90     if (n->is_Lock()) {
  91       Node* obj = n->as_Lock()->obj_node()->uncast();
  92       if (!(obj->is_Parm() || obj->is_Con())) {
  93         return true;
  94       }
  95     }
  96     if (n->is_CallStaticJava() &&
  97         n->as_CallStaticJava()->is_boxing_method()) {
  98       return true;
  99     }
 100   }
 101   return false;
 102 }
 103 
 104 void ConnectionGraph::do_analysis(Compile *C, PhaseIterGVN *igvn) {
 105   Compile::TracePhase tp(Phase::_t_escapeAnalysis);
 106   ResourceMark rm;
 107 
 108   // Add ConP and ConN null oop nodes before ConnectionGraph construction
 109   // to create space for them in ConnectionGraph::_nodes[].
 110   Node* oop_null = igvn->zerocon(T_OBJECT);
 111   Node* noop_null = igvn->zerocon(T_NARROWOOP);
 112   int invocation = 0;
 113   if (C->congraph() != nullptr) {
 114     invocation = C->congraph()->_invocation + 1;
 115   }
 116   ConnectionGraph* congraph = new(C->comp_arena()) ConnectionGraph(C, igvn, invocation);
 117   // Perform escape analysis
 118   if (congraph->compute_escape()) {
 119     // There are non escaping objects.
 120     C->set_congraph(congraph);
 121   }
 122   // Cleanup.
 123   if (oop_null->outcnt() == 0) {
 124     igvn->hash_delete(oop_null);
 125   }
 126   if (noop_null->outcnt() == 0) {
 127     igvn->hash_delete(noop_null);
 128   }
 129 }
 130 
 131 bool ConnectionGraph::compute_escape() {
 132   Compile* C = _compile;
 133   PhaseGVN* igvn = _igvn;
 134 
 135   // Worklists used by EA.
 136   Unique_Node_List delayed_worklist;
 137   Unique_Node_List reducible_merges;
 138   GrowableArray<Node*> alloc_worklist;
 139   GrowableArray<Node*> ptr_cmp_worklist;
 140   GrowableArray<MemBarStoreStoreNode*> storestore_worklist;
 141   GrowableArray<ArrayCopyNode*>  arraycopy_worklist;
 142   GrowableArray<PointsToNode*>   ptnodes_worklist;
 143   GrowableArray<JavaObjectNode*> java_objects_worklist;
 144   GrowableArray<JavaObjectNode*> non_escaped_allocs_worklist;
 145   GrowableArray<FieldNode*>      oop_fields_worklist;
 146   GrowableArray<SafePointNode*>  sfn_worklist;
 147   GrowableArray<MergeMemNode*>   mergemem_worklist;
 148   DEBUG_ONLY( GrowableArray<Node*> addp_worklist; )
 149 
 150   { Compile::TracePhase tp(Phase::_t_connectionGraph);
 151 
 152   // 1. Populate Connection Graph (CG) with PointsTo nodes.
 153   ideal_nodes.map(C->live_nodes(), nullptr);  // preallocate space
 154   // Initialize worklist
 155   if (C->root() != nullptr) {
 156     ideal_nodes.push(C->root());
 157   }
 158   // Processed ideal nodes are unique on ideal_nodes list
 159   // but several ideal nodes are mapped to the phantom_obj.
 160   // To avoid duplicated entries on the following worklists
 161   // add the phantom_obj only once to them.
 162   ptnodes_worklist.append(phantom_obj);
 163   java_objects_worklist.append(phantom_obj);
 164   for( uint next = 0; next < ideal_nodes.size(); ++next ) {
 165     Node* n = ideal_nodes.at(next);
 166     // Create PointsTo nodes and add them to Connection Graph. Called
 167     // only once per ideal node since ideal_nodes is Unique_Node list.
 168     add_node_to_connection_graph(n, &delayed_worklist);
 169     PointsToNode* ptn = ptnode_adr(n->_idx);
 170     if (ptn != nullptr && ptn != phantom_obj) {
 171       ptnodes_worklist.append(ptn);
 172       if (ptn->is_JavaObject()) {
 173         java_objects_worklist.append(ptn->as_JavaObject());
 174         if ((n->is_Allocate() || n->is_CallStaticJava()) &&
 175             (ptn->escape_state() < PointsToNode::GlobalEscape)) {
 176           // Only allocations and java static calls results are interesting.
 177           non_escaped_allocs_worklist.append(ptn->as_JavaObject());
 178         }
 179       } else if (ptn->is_Field() && ptn->as_Field()->is_oop()) {
 180         oop_fields_worklist.append(ptn->as_Field());
 181       }
 182     }
 183     // Collect some interesting nodes for further use.
 184     switch (n->Opcode()) {
 185       case Op_MergeMem:
 186         // Collect all MergeMem nodes to add memory slices for
 187         // scalar replaceable objects in split_unique_types().
 188         mergemem_worklist.append(n->as_MergeMem());
 189         break;
 190       case Op_CmpP:
 191       case Op_CmpN:
 192         // Collect compare pointers nodes.
 193         if (OptimizePtrCompare) {
 194           ptr_cmp_worklist.append(n);
 195         }
 196         break;
 197       case Op_MemBarStoreStore:
 198         // Collect all MemBarStoreStore nodes so that depending on the
 199         // escape status of the associated Allocate node some of them
 200         // may be eliminated.
 201         if (!UseStoreStoreForCtor || n->req() > MemBarNode::Precedent) {
 202           storestore_worklist.append(n->as_MemBarStoreStore());
 203         }
 204         break;
 205       case Op_MemBarRelease:
 206         if (n->req() > MemBarNode::Precedent) {
 207           record_for_optimizer(n);
 208         }
 209         break;
 210 #ifdef ASSERT
 211       case Op_AddP:
 212         // Collect address nodes for graph verification.
 213         addp_worklist.append(n);
 214         break;
 215 #endif
 216       case Op_ArrayCopy:
 217         // Keep a list of ArrayCopy nodes so if one of its input is non
 218         // escaping, we can record a unique type
 219         arraycopy_worklist.append(n->as_ArrayCopy());
 220         break;
 221       default:
 222         // not interested now, ignore...
 223         break;
 224     }
 225     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 226       Node* m = n->fast_out(i);   // Get user
 227       ideal_nodes.push(m);
 228     }
 229     if (n->is_SafePoint()) {
 230       sfn_worklist.append(n->as_SafePoint());
 231     }
 232   }
 233 
 234 #ifndef PRODUCT
 235   if (_compile->directive()->TraceEscapeAnalysisOption) {
 236     tty->print("+++++ Initial worklist for ");
 237     _compile->method()->print_name();
 238     tty->print_cr(" (ea_inv=%d)", _invocation);
 239     for (int i = 0; i < ptnodes_worklist.length(); i++) {
 240       PointsToNode* ptn = ptnodes_worklist.at(i);
 241       ptn->dump();
 242     }
 243     tty->print_cr("+++++ Calculating escape states and scalar replaceability");
 244   }
 245 #endif
 246 
 247   if (non_escaped_allocs_worklist.length() == 0) {
 248     _collecting = false;
 249     NOT_PRODUCT(escape_state_statistics(java_objects_worklist);)
 250     return false; // Nothing to do.
 251   }
 252   // Add final simple edges to graph.
 253   while(delayed_worklist.size() > 0) {
 254     Node* n = delayed_worklist.pop();
 255     add_final_edges(n);
 256   }
 257 
 258 #ifdef ASSERT
 259   if (VerifyConnectionGraph) {
 260     // Verify that no new simple edges could be created and all
 261     // local vars has edges.
 262     _verify = true;
 263     int ptnodes_length = ptnodes_worklist.length();
 264     for (int next = 0; next < ptnodes_length; ++next) {
 265       PointsToNode* ptn = ptnodes_worklist.at(next);
 266       add_final_edges(ptn->ideal_node());
 267       if (ptn->is_LocalVar() && ptn->edge_count() == 0) {
 268         ptn->dump();
 269         assert(ptn->as_LocalVar()->edge_count() > 0, "sanity");
 270       }
 271     }
 272     _verify = false;
 273   }
 274 #endif
 275   // Bytecode analyzer BCEscapeAnalyzer, used for Call nodes
 276   // processing, calls to CI to resolve symbols (types, fields, methods)
 277   // referenced in bytecode. During symbol resolution VM may throw
 278   // an exception which CI cleans and converts to compilation failure.
 279   if (C->failing()) {
 280     NOT_PRODUCT(escape_state_statistics(java_objects_worklist);)
 281     return false;
 282   }
 283 
 284   // 2. Finish Graph construction by propagating references to all
 285   //    java objects through graph.
 286   if (!complete_connection_graph(ptnodes_worklist, non_escaped_allocs_worklist,
 287                                  java_objects_worklist, oop_fields_worklist)) {
 288     // All objects escaped or hit time or iterations limits.
 289     _collecting = false;
 290     NOT_PRODUCT(escape_state_statistics(java_objects_worklist);)
 291     return false;
 292   }
 293 
 294   // 3. Adjust scalar_replaceable state of nonescaping objects and push
 295   //    scalar replaceable allocations on alloc_worklist for processing
 296   //    in split_unique_types().
 297   GrowableArray<JavaObjectNode*> jobj_worklist;
 298   int non_escaped_length = non_escaped_allocs_worklist.length();
 299   bool found_nsr_alloc = false;
 300   for (int next = 0; next < non_escaped_length; next++) {
 301     JavaObjectNode* ptn = non_escaped_allocs_worklist.at(next);
 302     bool noescape = (ptn->escape_state() == PointsToNode::NoEscape);
 303     Node* n = ptn->ideal_node();
 304     if (n->is_Allocate()) {
 305       n->as_Allocate()->_is_non_escaping = noescape;
 306     }
 307     if (noescape && ptn->scalar_replaceable()) {
 308       adjust_scalar_replaceable_state(ptn, reducible_merges);
 309       if (ptn->scalar_replaceable()) {
 310         jobj_worklist.push(ptn);
 311       } else {
 312         found_nsr_alloc = true;
 313       }
 314     }
 315   }
 316 
 317   // Propagate NSR (Not Scalar Replaceable) state.
 318   if (found_nsr_alloc) {
 319     find_scalar_replaceable_allocs(jobj_worklist, reducible_merges);
 320   }
 321 
 322   // alloc_worklist will be processed in reverse push order.
 323   // Therefore the reducible Phis will be processed for last and that's what we
 324   // want because by then the scalarizable inputs of the merge will already have
 325   // an unique instance type.
 326   for (uint i = 0; i < reducible_merges.size(); i++ ) {
 327     Node* n = reducible_merges.at(i);
 328     alloc_worklist.append(n);
 329   }
 330 
 331   for (int next = 0; next < jobj_worklist.length(); ++next) {
 332     JavaObjectNode* jobj = jobj_worklist.at(next);
 333     if (jobj->scalar_replaceable()) {
 334       alloc_worklist.append(jobj->ideal_node());
 335     }
 336   }
 337 
 338 #ifdef ASSERT
 339   if (VerifyConnectionGraph) {
 340     // Verify that graph is complete - no new edges could be added or needed.
 341     verify_connection_graph(ptnodes_worklist, non_escaped_allocs_worklist,
 342                             java_objects_worklist, addp_worklist);
 343   }
 344   assert(C->unique() == nodes_size(), "no new ideal nodes should be added during ConnectionGraph build");
 345   assert(null_obj->escape_state() == PointsToNode::NoEscape &&
 346          null_obj->edge_count() == 0 &&
 347          !null_obj->arraycopy_src() &&
 348          !null_obj->arraycopy_dst(), "sanity");
 349 #endif
 350 
 351   _collecting = false;
 352 
 353   } // TracePhase t3("connectionGraph")
 354 
 355   // 4. Optimize ideal graph based on EA information.
 356   bool has_non_escaping_obj = (non_escaped_allocs_worklist.length() > 0);
 357   if (has_non_escaping_obj) {
 358     optimize_ideal_graph(ptr_cmp_worklist, storestore_worklist);
 359   }
 360 
 361 #ifndef PRODUCT
 362   if (PrintEscapeAnalysis) {
 363     dump(ptnodes_worklist); // Dump ConnectionGraph
 364   }
 365 #endif
 366 
 367 #ifdef ASSERT
 368   if (VerifyConnectionGraph) {
 369     int alloc_length = alloc_worklist.length();
 370     for (int next = 0; next < alloc_length; ++next) {
 371       Node* n = alloc_worklist.at(next);
 372       PointsToNode* ptn = ptnode_adr(n->_idx);
 373       assert(ptn->escape_state() == PointsToNode::NoEscape && ptn->scalar_replaceable(), "sanity");
 374     }
 375   }
 376 
 377   if (VerifyReduceAllocationMerges) {
 378     for (uint i = 0; i < reducible_merges.size(); i++ ) {
 379       Node* n = reducible_merges.at(i);
 380       if (!can_reduce_phi(n->as_Phi())) {
 381         TraceReduceAllocationMerges = true;
 382         n->dump(2);
 383         n->dump(-2);
 384         assert(can_reduce_phi(n->as_Phi()), "Sanity: previous reducible Phi is no longer reducible before SUT.");
 385       }
 386     }
 387   }
 388 #endif
 389 
 390   // 5. Separate memory graph for scalar replaceable allcations.
 391   bool has_scalar_replaceable_candidates = (alloc_worklist.length() > 0);
 392   if (has_scalar_replaceable_candidates && EliminateAllocations) {
 393     assert(C->do_aliasing(), "Aliasing should be enabled");
 394     // Now use the escape information to create unique types for
 395     // scalar replaceable objects.
 396     split_unique_types(alloc_worklist, arraycopy_worklist, mergemem_worklist, reducible_merges);
 397     if (C->failing()) {
 398       NOT_PRODUCT(escape_state_statistics(java_objects_worklist);)
 399       return false;
 400     }
 401     C->print_method(PHASE_AFTER_EA, 2);
 402 
 403 #ifdef ASSERT
 404   } else if (Verbose && (PrintEscapeAnalysis || PrintEliminateAllocations)) {
 405     tty->print("=== No allocations eliminated for ");
 406     C->method()->print_short_name();
 407     if (!EliminateAllocations) {
 408       tty->print(" since EliminateAllocations is off ===");
 409     } else if(!has_scalar_replaceable_candidates) {
 410       tty->print(" since there are no scalar replaceable candidates ===");
 411     }
 412     tty->cr();
 413 #endif
 414   }
 415 
 416   // 6. Reduce allocation merges used as debug information. This is done after
 417   // split_unique_types because the methods used to create SafePointScalarObject
 418   // need to traverse the memory graph to find values for object fields. We also
 419   // set to null the scalarized inputs of reducible Phis so that the Allocate
 420   // that they point can be later scalar replaced.
 421   bool delay = _igvn->delay_transform();
 422   _igvn->set_delay_transform(true);
 423   for (uint i = 0; i < reducible_merges.size(); i++) {
 424     Node* n = reducible_merges.at(i);
 425     if (n->outcnt() > 0) {
 426       if (!reduce_phi_on_safepoints(n->as_Phi())) {
 427         NOT_PRODUCT(escape_state_statistics(java_objects_worklist);)
 428         C->record_failure(C2Compiler::retry_no_reduce_allocation_merges());
 429         return false;
 430       }
 431 
 432       // Now we set the scalar replaceable inputs of ophi to null, which is
 433       // the last piece that would prevent it from being scalar replaceable.
 434       reset_scalar_replaceable_entries(n->as_Phi());
 435     }
 436   }
 437   _igvn->set_delay_transform(delay);
 438 
 439   // Annotate at safepoints if they have <= ArgEscape objects in their scope and at
 440   // java calls if they pass ArgEscape objects as parameters.
 441   if (has_non_escaping_obj &&
 442       (C->env()->should_retain_local_variables() ||
 443        C->env()->jvmti_can_get_owned_monitor_info() ||
 444        C->env()->jvmti_can_walk_any_space() ||
 445        DeoptimizeObjectsALot)) {
 446     int sfn_length = sfn_worklist.length();
 447     for (int next = 0; next < sfn_length; next++) {
 448       SafePointNode* sfn = sfn_worklist.at(next);
 449       sfn->set_has_ea_local_in_scope(has_ea_local_in_scope(sfn));
 450       if (sfn->is_CallJava()) {
 451         CallJavaNode* call = sfn->as_CallJava();
 452         call->set_arg_escape(has_arg_escape(call));
 453       }
 454     }
 455   }
 456 
 457   NOT_PRODUCT(escape_state_statistics(java_objects_worklist);)
 458   return has_non_escaping_obj;
 459 }
 460 
 461 // Check if it's profitable to reduce the Phi passed as parameter.  Returns true
 462 // if at least one scalar replaceable allocation participates in the merge.
 463 bool ConnectionGraph::can_reduce_phi_check_inputs(PhiNode* ophi) const {
 464   bool found_sr_allocate = false;
 465 
 466   for (uint i = 1; i < ophi->req(); i++) {
 467     JavaObjectNode* ptn = unique_java_object(ophi->in(i));
 468     if (ptn != nullptr && ptn->scalar_replaceable()) {
 469       AllocateNode* alloc = ptn->ideal_node()->as_Allocate();
 470 
 471       // Don't handle arrays.
 472       if (alloc->Opcode() != Op_Allocate) {
 473         assert(alloc->Opcode() == Op_AllocateArray, "Unexpected type of allocation.");
 474         continue;
 475       }
 476 
 477       if (PhaseMacroExpand::can_eliminate_allocation(_igvn, alloc, nullptr)) {
 478         found_sr_allocate = true;
 479       } else {
 480         NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("%dth input of Phi %d is SR but can't be eliminated.", i, ophi->_idx);)
 481         ptn->set_scalar_replaceable(false);
 482       }
 483     }
 484   }
 485 
 486   NOT_PRODUCT(if (TraceReduceAllocationMerges && !found_sr_allocate) tty->print_cr("Can NOT reduce Phi %d on invocation %d. No SR Allocate as input.", ophi->_idx, _invocation);)
 487   return found_sr_allocate;
 488 }
 489 
 490 // We can reduce the Cmp if it's a comparison between the Phi and a constant.
 491 // I require the 'other' input to be a constant so that I can move the Cmp
 492 // around safely.
 493 bool ConnectionGraph::can_reduce_cmp(Node* n, Node* cmp) const {
 494   assert(cmp->Opcode() == Op_CmpP || cmp->Opcode() == Op_CmpN, "not expected node: %s", cmp->Name());
 495   Node* left = cmp->in(1);
 496   Node* right = cmp->in(2);
 497 
 498   return (left == n || right == n) &&
 499          (left->is_Con() || right->is_Con()) &&
 500          cmp->outcnt() == 1;
 501 }
 502 
 503 // We are going to check if any of the SafePointScalarMerge entries
 504 // in the SafePoint reference the Phi that we are checking.
 505 bool ConnectionGraph::has_been_reduced(PhiNode* n, SafePointNode* sfpt) const {
 506   JVMState *jvms = sfpt->jvms();
 507 
 508   for (uint i = jvms->debug_start(); i < jvms->debug_end(); i++) {
 509     Node* sfpt_in = sfpt->in(i);
 510     if (sfpt_in->is_SafePointScalarMerge()) {
 511       SafePointScalarMergeNode* smerge = sfpt_in->as_SafePointScalarMerge();
 512       Node* nsr_ptr = sfpt->in(smerge->merge_pointer_idx(jvms));
 513       if (nsr_ptr == n) {
 514         return true;
 515       }
 516     }
 517   }
 518 
 519   return false;
 520 }
 521 
 522 // Check if we are able to untangle the merge. The following patterns are
 523 // supported:
 524 //  - Phi -> SafePoints
 525 //  - Phi -> CmpP/N
 526 //  - Phi -> AddP -> Load
 527 //  - Phi -> CastPP -> SafePoints
 528 //  - Phi -> CastPP -> AddP -> Load
 529 bool ConnectionGraph::can_reduce_check_users(Node* n, uint nesting) const {
 530   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 531     Node* use = n->fast_out(i);
 532 
 533     if (use->is_SafePoint()) {
 534       if (use->is_Call() && use->as_Call()->has_non_debug_use(n)) {
 535         NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Can NOT reduce Phi %d on invocation %d. Call has non_debug_use().", n->_idx, _invocation);)
 536         return false;
 537       } else if (has_been_reduced(n->is_Phi() ? n->as_Phi() : n->as_CastPP()->in(1)->as_Phi(), use->as_SafePoint())) {
 538         NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Can NOT reduce Phi %d on invocation %d. It has already been reduced.", n->_idx, _invocation);)
 539         return false;
 540       }
 541     } else if (use->is_AddP()) {
 542       Node* addp = use;
 543       for (DUIterator_Fast jmax, j = addp->fast_outs(jmax); j < jmax; j++) {
 544         Node* use_use = addp->fast_out(j);
 545         const Type* load_type = _igvn->type(use_use);
 546 
 547         if (!use_use->is_Load() || !use_use->as_Load()->can_split_through_phi_base(_igvn)) {
 548           NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Can NOT reduce Phi %d on invocation %d. AddP user isn't a [splittable] Load(): %s", n->_idx, _invocation, use_use->Name());)
 549           return false;
 550         } else if (load_type->isa_narrowklass() || load_type->isa_klassptr()) {
 551           NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Can NOT reduce Phi %d on invocation %d. [Narrow] Klass Load: %s", n->_idx, _invocation, use_use->Name());)
 552           return false;
 553         }
 554       }
 555     } else if (nesting > 0) {
 556       NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Can NOT reduce Phi %d on invocation %d. Unsupported user %s at nesting level %d.", n->_idx, _invocation, use->Name(), nesting);)
 557       return false;
 558     } else if (use->is_CastPP()) {
 559       const Type* cast_t = _igvn->type(use);
 560       if (cast_t == nullptr || cast_t->make_ptr()->isa_instptr() == nullptr) {
 561 #ifndef PRODUCT
 562         if (TraceReduceAllocationMerges) {
 563           tty->print_cr("Can NOT reduce Phi %d on invocation %d. CastPP is not to an instance.", n->_idx, _invocation);
 564           use->dump();
 565         }
 566 #endif
 567         return false;
 568       }
 569 
 570       bool is_trivial_control = use->in(0) == nullptr || use->in(0) == n->in(0);
 571       if (!is_trivial_control) {
 572         // If it's not a trivial control then we check if we can reduce the
 573         // CmpP/N used by the If controlling the cast.
 574         if (use->in(0)->is_IfTrue() || use->in(0)->is_IfFalse()) {
 575           Node* iff = use->in(0)->in(0);
 576           // We may have an OpaqueNotNull node between If and Bool nodes. But we could also have a sub class of IfNode,
 577           // for example, an OuterStripMinedLoopEnd or a Parse Predicate. Bail out in all these cases.
 578           bool can_reduce = (iff->Opcode() == Op_If) && iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp();
 579           if (can_reduce) {
 580             Node* iff_cmp = iff->in(1)->in(1);
 581             int opc = iff_cmp->Opcode();
 582             can_reduce = (opc == Op_CmpP || opc == Op_CmpN) && can_reduce_cmp(n, iff_cmp);
 583           }
 584           if (!can_reduce) {
 585 #ifndef PRODUCT
 586             if (TraceReduceAllocationMerges) {
 587               tty->print_cr("Can NOT reduce Phi %d on invocation %d. CastPP %d doesn't have simple control.", n->_idx, _invocation, use->_idx);
 588               n->dump(5);
 589             }
 590 #endif
 591             return false;
 592           }
 593         }
 594       }
 595 
 596       if (!can_reduce_check_users(use, nesting+1)) {
 597         return false;
 598       }
 599     } else if (use->Opcode() == Op_CmpP || use->Opcode() == Op_CmpN) {
 600       if (!can_reduce_cmp(n, use)) {
 601         NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Can NOT reduce Phi %d on invocation %d. CmpP/N %d isn't reducible.", n->_idx, _invocation, use->_idx);)
 602         return false;
 603       }
 604     } else {
 605       NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Can NOT reduce Phi %d on invocation %d. One of the uses is: %d %s", n->_idx, _invocation, use->_idx, use->Name());)
 606       return false;
 607     }
 608   }
 609 
 610   return true;
 611 }
 612 
 613 // Returns true if: 1) It's profitable to reduce the merge, and 2) The Phi is
 614 // only used in some certain code shapes. Check comments in
 615 // 'can_reduce_phi_inputs' and 'can_reduce_phi_users' for more
 616 // details.
 617 bool ConnectionGraph::can_reduce_phi(PhiNode* ophi) const {
 618   // If there was an error attempting to reduce allocation merges for this
 619   // method we might have disabled the compilation and be retrying with RAM
 620   // disabled.
 621   if (!_compile->do_reduce_allocation_merges() || ophi->region()->Opcode() != Op_Region) {
 622     return false;
 623   }
 624 
 625   const Type* phi_t = _igvn->type(ophi);
 626   if (phi_t == nullptr ||
 627       phi_t->make_ptr() == nullptr ||
 628       phi_t->make_ptr()->isa_aryptr() != nullptr) {
 629     return false;
 630   }
 631 
 632   if (!can_reduce_phi_check_inputs(ophi) || !can_reduce_check_users(ophi, /* nesting: */ 0)) {
 633     return false;
 634   }
 635 
 636   NOT_PRODUCT(if (TraceReduceAllocationMerges) { tty->print_cr("Can reduce Phi %d during invocation %d: ", ophi->_idx, _invocation); })
 637   return true;
 638 }
 639 
 640 // This method will return a CmpP/N that we need to use on the If controlling a
 641 // CastPP after it was split. This method is only called on bases that are
 642 // nullable therefore we always need a controlling if for the splitted CastPP.
 643 //
 644 // 'curr_ctrl' is the control of the CastPP that we want to split through phi.
 645 // If the CastPP currently doesn't have a control then the CmpP/N will be
 646 // against the null constant, otherwise it will be against the constant input of
 647 // the existing CmpP/N. It's guaranteed that there will be a CmpP/N in the later
 648 // case because we have constraints on it and because the CastPP has a control
 649 // input.
 650 Node* ConnectionGraph::specialize_cmp(Node* base, Node* curr_ctrl) {
 651   const Type* t = base->bottom_type();
 652   Node* con = nullptr;
 653 
 654   if (curr_ctrl == nullptr || curr_ctrl->is_Region()) {
 655     con = _igvn->zerocon(t->basic_type());
 656   } else {
 657     // can_reduce_check_users() verified graph: true/false -> if -> bool -> cmp
 658     assert(curr_ctrl->in(0)->Opcode() == Op_If, "unexpected node %s", curr_ctrl->in(0)->Name());
 659     Node* bol = curr_ctrl->in(0)->in(1);
 660     assert(bol->is_Bool(), "unexpected node %s", bol->Name());
 661     Node* curr_cmp = bol->in(1);
 662     assert(curr_cmp->Opcode() == Op_CmpP || curr_cmp->Opcode() == Op_CmpN, "unexpected node %s", curr_cmp->Name());
 663     con = curr_cmp->in(1)->is_Con() ? curr_cmp->in(1) : curr_cmp->in(2);
 664   }
 665 
 666   return CmpNode::make(base, con, t->basic_type());
 667 }
 668 
 669 // This method 'specializes' the CastPP passed as parameter to the base passed
 670 // as parameter. Note that the existing CastPP input is a Phi. "Specialize"
 671 // means that the CastPP now will be specific for a given base instead of a Phi.
 672 // An If-Then-Else-Region block is inserted to control the CastPP. The control
 673 // of the CastPP is a copy of the current one (if there is one) or a check
 674 // against null.
 675 //
 676 // Before:
 677 //
 678 //    C1     C2  ... Cn
 679 //     \      |      /
 680 //      \     |     /
 681 //       \    |    /
 682 //        \   |   /
 683 //         \  |  /
 684 //          \ | /
 685 //           \|/
 686 //          Region     B1      B2  ... Bn
 687 //            |          \      |      /
 688 //            |           \     |     /
 689 //            |            \    |    /
 690 //            |             \   |   /
 691 //            |              \  |  /
 692 //            |               \ | /
 693 //            ---------------> Phi
 694 //                              |
 695 //                      X       |
 696 //                      |       |
 697 //                      |       |
 698 //                      ------> CastPP
 699 //
 700 // After (only partial illustration; base = B2, current_control = C2):
 701 //
 702 //                      C2
 703 //                      |
 704 //                      If
 705 //                     / \
 706 //                    /   \
 707 //                   T     F
 708 //                  /\     /
 709 //                 /  \   /
 710 //                /    \ /
 711 //      C1    CastPP   Reg        Cn
 712 //       |              |          |
 713 //       |              |          |
 714 //       |              |          |
 715 //       -------------- | ----------
 716 //                    | | |
 717 //                    Region
 718 //
 719 Node* ConnectionGraph::specialize_castpp(Node* castpp, Node* base, Node* current_control) {
 720   Node* control_successor  = current_control->unique_ctrl_out();
 721   Node* cmp                = _igvn->transform(specialize_cmp(base, castpp->in(0)));
 722   Node* bol                = _igvn->transform(new BoolNode(cmp, BoolTest::ne));
 723   IfNode* if_ne            = _igvn->transform(new IfNode(current_control, bol, PROB_MIN, COUNT_UNKNOWN))->as_If();
 724   Node* not_eq_control     = _igvn->transform(new IfTrueNode(if_ne));
 725   Node* yes_eq_control     = _igvn->transform(new IfFalseNode(if_ne));
 726   Node* end_region         = _igvn->transform(new RegionNode(3));
 727 
 728   // Insert the new if-else-region block into the graph
 729   end_region->set_req(1, not_eq_control);
 730   end_region->set_req(2, yes_eq_control);
 731   control_successor->replace_edge(current_control, end_region, _igvn);
 732 
 733   _igvn->_worklist.push(current_control);
 734   _igvn->_worklist.push(control_successor);
 735 
 736   return _igvn->transform(ConstraintCastNode::make_cast_for_type(not_eq_control, base, _igvn->type(castpp), ConstraintCastNode::UnconditionalDependency, nullptr));
 737 }
 738 
 739 Node* ConnectionGraph::split_castpp_load_through_phi(Node* curr_addp, Node* curr_load, Node* region, GrowableArray<Node*>* bases_for_loads, GrowableArray<Node *>  &alloc_worklist) {
 740   const Type* load_type = _igvn->type(curr_load);
 741   Node* nsr_value = _igvn->zerocon(load_type->basic_type());
 742   Node* memory = curr_load->in(MemNode::Memory);
 743 
 744   // The data_phi merging the loads needs to be nullable if
 745   // we are loading pointers.
 746   if (load_type->make_ptr() != nullptr) {
 747     if (load_type->isa_narrowoop()) {
 748       load_type = load_type->meet(TypeNarrowOop::NULL_PTR);
 749     } else if (load_type->isa_ptr()) {
 750       load_type = load_type->meet(TypePtr::NULL_PTR);
 751     } else {
 752       assert(false, "Unexpected load ptr type.");
 753     }
 754   }
 755 
 756   Node* data_phi = PhiNode::make(region, nsr_value, load_type);
 757 
 758   for (int i = 1; i < bases_for_loads->length(); i++) {
 759     Node* base = bases_for_loads->at(i);
 760     Node* cmp_region = nullptr;
 761     if (base != nullptr) {
 762       if (base->is_CFG()) { // means that we added a CastPP as child of this CFG node
 763         cmp_region = base->unique_ctrl_out_or_null();
 764         assert(cmp_region != nullptr, "There should be.");
 765         base = base->find_out_with(Op_CastPP);
 766       }
 767 
 768       Node* addr = _igvn->transform(new AddPNode(base, base, curr_addp->in(AddPNode::Offset)));
 769       Node* mem = (memory->is_Phi() && (memory->in(0) == region)) ? memory->in(i) : memory;
 770       Node* load = curr_load->clone();
 771       load->set_req(0, nullptr);
 772       load->set_req(1, mem);
 773       load->set_req(2, addr);
 774 
 775       if (cmp_region != nullptr) { // see comment on previous if
 776         Node* intermediate_phi = PhiNode::make(cmp_region, nsr_value, load_type);
 777         intermediate_phi->set_req(1, _igvn->transform(load));
 778         load = intermediate_phi;
 779       }
 780 
 781       data_phi->set_req(i, _igvn->transform(load));
 782     } else {
 783       // Just use the default, which is already in phi
 784     }
 785   }
 786 
 787   // Takes care of updating CG and split_unique_types worklists due
 788   // to cloned AddP->Load.
 789   updates_after_load_split(data_phi, curr_load, alloc_worklist);
 790 
 791   return _igvn->transform(data_phi);
 792 }
 793 
 794 // This method only reduces CastPP fields loads; SafePoints are handled
 795 // separately. The idea here is basically to clone the CastPP and place copies
 796 // on each input of the Phi, including non-scalar replaceable inputs.
 797 // Experimentation shows that the resulting IR graph is simpler that way than if
 798 // we just split the cast through scalar-replaceable inputs.
 799 //
 800 // The reduction process requires that CastPP's control be one of:
 801 //  1) no control,
 802 //  2) the same region as Ophi, or
 803 //  3) an IfTrue/IfFalse coming from an CmpP/N between Ophi and a constant.
 804 //
 805 // After splitting the CastPP we'll put it under an If-Then-Else-Region control
 806 // flow. If the CastPP originally had an IfTrue/False control input then we'll
 807 // use a similar CmpP/N to control the new If-Then-Else-Region. Otherwise, we'll
 808 // juse use a CmpP/N against the null constant.
 809 //
 810 // The If-Then-Else-Region isn't always needed. For instance, if input to
 811 // splitted cast was not nullable (or if it was the null constant) then we don't
 812 // need (shouldn't) use a CastPP at all.
 813 //
 814 // After the casts are splitted we'll split the AddP->Loads through the Phi and
 815 // connect them to the just split CastPPs.
 816 //
 817 // Before (CastPP control is same as Phi):
 818 //
 819 //          Region     Allocate   Null    Call
 820 //            |             \      |      /
 821 //            |              \     |     /
 822 //            |               \    |    /
 823 //            |                \   |   /
 824 //            |                 \  |  /
 825 //            |                  \ | /
 826 //            ------------------> Phi            # Oop Phi
 827 //            |                    |
 828 //            |                    |
 829 //            |                    |
 830 //            |                    |
 831 //            ----------------> CastPP
 832 //                                 |
 833 //                               AddP
 834 //                                 |
 835 //                               Load
 836 //
 837 // After (Very much simplified):
 838 //
 839 //                         Call  Null
 840 //                            \  /
 841 //                            CmpP
 842 //                             |
 843 //                           Bool#NE
 844 //                             |
 845 //                             If
 846 //                            / \
 847 //                           T   F
 848 //                          / \ /
 849 //                         /   R
 850 //                     CastPP  |
 851 //                       |     |
 852 //                     AddP    |
 853 //                       |     |
 854 //                     Load    |
 855 //                         \   |   0
 856 //            Allocate      \  |  /
 857 //                \          \ | /
 858 //               AddP         Phi
 859 //                  \         /
 860 //                 Load      /
 861 //                    \  0  /
 862 //                     \ | /
 863 //                      \|/
 864 //                      Phi        # "Field" Phi
 865 //
 866 void ConnectionGraph::reduce_phi_on_castpp_field_load(Node* curr_castpp, GrowableArray<Node *>  &alloc_worklist, GrowableArray<Node *>  &memnode_worklist) {
 867   Node* ophi = curr_castpp->in(1);
 868   assert(ophi->is_Phi(), "Expected this to be a Phi node.");
 869 
 870   // Identify which base should be used for AddP->Load later when spliting the
 871   // CastPP->Loads through ophi. Three kind of values may be stored in this
 872   // array, depending on the nullability status of the corresponding input in
 873   // ophi.
 874   //
 875   //  - nullptr:    Meaning that the base is actually the null constant and therefore
 876   //                we won't try to load from it.
 877   //
 878   //  - CFG Node:   Meaning that the base is a CastPP that was specialized for
 879   //                this input of Ophi. I.e., we added an If->Then->Else-Region
 880   //                that will 'activate' the CastPp only when the input is not Null.
 881   //
 882   //  - Other Node: Meaning that the base is not nullable and therefore we'll try
 883   //                to load directly from it.
 884   GrowableArray<Node*> bases_for_loads(ophi->req(), ophi->req(), nullptr);
 885 
 886   for (uint i = 1; i < ophi->req(); i++) {
 887     Node* base = ophi->in(i);
 888     const Type* base_t = _igvn->type(base);
 889 
 890     if (base_t->maybe_null()) {
 891       if (base->is_Con()) {
 892         // Nothing todo as bases_for_loads[i] is already null
 893       } else {
 894         Node* new_castpp = specialize_castpp(curr_castpp, base, ophi->in(0)->in(i));
 895         bases_for_loads.at_put(i, new_castpp->in(0)); // Use the ctrl of the new node just as a flag
 896       }
 897     } else {
 898       bases_for_loads.at_put(i, base);
 899     }
 900   }
 901 
 902   // Now let's split the CastPP->Loads through the Phi
 903   for (int i = curr_castpp->outcnt()-1; i >= 0;) {
 904     Node* use = curr_castpp->raw_out(i);
 905     if (use->is_AddP()) {
 906       for (int j = use->outcnt()-1; j >= 0;) {
 907         Node* use_use = use->raw_out(j);
 908         assert(use_use->is_Load(), "Expected this to be a Load node.");
 909 
 910         // We can't make an unconditional load from a nullable input. The
 911         // 'split_castpp_load_through_phi` method will add an
 912         // 'If-Then-Else-Region` around nullable bases and only load from them
 913         // when the input is not null.
 914         Node* phi = split_castpp_load_through_phi(use, use_use, ophi->in(0), &bases_for_loads, alloc_worklist);
 915         _igvn->replace_node(use_use, phi);
 916 
 917         --j;
 918         j = MIN2(j, (int)use->outcnt()-1);
 919       }
 920 
 921       _igvn->remove_dead_node(use);
 922     }
 923     --i;
 924     i = MIN2(i, (int)curr_castpp->outcnt()-1);
 925   }
 926 }
 927 
 928 // This method split a given CmpP/N through the Phi used in one of its inputs.
 929 // As a result we convert a comparison with a pointer to a comparison with an
 930 // integer.
 931 // The only requirement is that one of the inputs of the CmpP/N must be a Phi
 932 // while the other must be a constant.
 933 // The splitting process is basically just cloning the CmpP/N above the input
 934 // Phi.  However, some (most) of the cloned CmpP/Ns won't be requred because we
 935 // can prove at compile time the result of the comparison.
 936 //
 937 // Before:
 938 //
 939 //             in1    in2 ... inN
 940 //              \      |      /
 941 //               \     |     /
 942 //                \    |    /
 943 //                 \   |   /
 944 //                  \  |  /
 945 //                   \ | /
 946 //                    Phi
 947 //                     |   Other
 948 //                     |    /
 949 //                     |   /
 950 //                     |  /
 951 //                    CmpP/N
 952 //
 953 // After:
 954 //
 955 //        in1  Other   in2 Other  inN  Other
 956 //         |    |      |   |      |    |
 957 //         \    |      |   |      |    |
 958 //          \  /       |   /      |    /
 959 //          CmpP/N    CmpP/N     CmpP/N
 960 //          Bool      Bool       Bool
 961 //            \        |        /
 962 //             \       |       /
 963 //              \      |      /
 964 //               \     |     /
 965 //                \    |    /
 966 //                 \   |   /
 967 //                  \  |  /
 968 //                   \ | /
 969 //                    Phi
 970 //                     |
 971 //                     |   Zero
 972 //                     |    /
 973 //                     |   /
 974 //                     |  /
 975 //                     CmpI
 976 //
 977 //
 978 void ConnectionGraph::reduce_phi_on_cmp(Node* cmp) {
 979   Node* ophi = cmp->in(1)->is_Con() ? cmp->in(2) : cmp->in(1);
 980   assert(ophi->is_Phi(), "Expected this to be a Phi node.");
 981 
 982   Node* other = cmp->in(1)->is_Con() ? cmp->in(1) : cmp->in(2);
 983   Node* zero = _igvn->intcon(0);
 984   Node* one = _igvn->intcon(1);
 985   BoolTest::mask mask = cmp->unique_out()->as_Bool()->_test._test;
 986 
 987   // This Phi will merge the result of the Cmps split through the Phi
 988   Node* res_phi = PhiNode::make(ophi->in(0), zero, TypeInt::INT);
 989 
 990   for (uint i=1; i<ophi->req(); i++) {
 991     Node* ophi_input = ophi->in(i);
 992     Node* res_phi_input = nullptr;
 993 
 994     const TypeInt* tcmp = optimize_ptr_compare(ophi_input, other);
 995     if (tcmp->singleton()) {
 996       if ((mask == BoolTest::mask::eq && tcmp == TypeInt::CC_EQ) ||
 997           (mask == BoolTest::mask::ne && tcmp == TypeInt::CC_GT)) {
 998         res_phi_input = one;
 999       } else {
1000         res_phi_input = zero;
1001       }
1002     } else {
1003       Node* ncmp = _igvn->transform(cmp->clone());
1004       ncmp->set_req(1, ophi_input);
1005       ncmp->set_req(2, other);
1006       Node* bol = _igvn->transform(new BoolNode(ncmp, mask));
1007       res_phi_input = bol->as_Bool()->as_int_value(_igvn);
1008     }
1009 
1010     res_phi->set_req(i, res_phi_input);
1011   }
1012 
1013   // This CMP always compares whether the output of "res_phi" is TRUE as far as the "mask".
1014   Node* new_cmp = _igvn->transform(new CmpINode(_igvn->transform(res_phi), (mask == BoolTest::mask::eq) ? one : zero));
1015   _igvn->replace_node(cmp, new_cmp);
1016 }
1017 
1018 // Push the newly created AddP on alloc_worklist and patch
1019 // the connection graph. Note that the changes in the CG below
1020 // won't affect the ES of objects since the new nodes have the
1021 // same status as the old ones.
1022 void ConnectionGraph::updates_after_load_split(Node* data_phi, Node* previous_load, GrowableArray<Node *>  &alloc_worklist) {
1023   assert(data_phi != nullptr, "Output of split_through_phi is null.");
1024   assert(data_phi != previous_load, "Output of split_through_phi is same as input.");
1025   assert(data_phi->is_Phi(), "Output of split_through_phi isn't a Phi.");
1026 
1027   if (data_phi == nullptr || !data_phi->is_Phi()) {
1028     // Make this a retry?
1029     return ;
1030   }
1031 
1032   Node* previous_addp = previous_load->in(MemNode::Address);
1033   FieldNode* fn = ptnode_adr(previous_addp->_idx)->as_Field();
1034   for (uint i = 1; i < data_phi->req(); i++) {
1035     Node* new_load = data_phi->in(i);
1036 
1037     if (new_load->is_Phi()) {
1038       // new_load is currently the "intermediate_phi" from an specialized
1039       // CastPP.
1040       new_load = new_load->in(1);
1041     }
1042 
1043     // "new_load" might actually be a constant, parameter, etc.
1044     if (new_load->is_Load()) {
1045       Node* new_addp = new_load->in(MemNode::Address);
1046       Node* base = get_addp_base(new_addp);
1047 
1048       // The base might not be something that we can create an unique
1049       // type for. If that's the case we are done with that input.
1050       PointsToNode* jobj_ptn = unique_java_object(base);
1051       if (jobj_ptn == nullptr || !jobj_ptn->scalar_replaceable()) {
1052         continue;
1053       }
1054 
1055       // Push to alloc_worklist since the base has an unique_type
1056       alloc_worklist.append_if_missing(new_addp);
1057 
1058       // Now let's add the node to the connection graph
1059       _nodes.at_grow(new_addp->_idx, nullptr);
1060       add_field(new_addp, fn->escape_state(), fn->offset());
1061       add_base(ptnode_adr(new_addp->_idx)->as_Field(), ptnode_adr(base->_idx));
1062 
1063       // If the load doesn't load an object then it won't be
1064       // part of the connection graph
1065       PointsToNode* curr_load_ptn = ptnode_adr(previous_load->_idx);
1066       if (curr_load_ptn != nullptr) {
1067         _nodes.at_grow(new_load->_idx, nullptr);
1068         add_local_var(new_load, curr_load_ptn->escape_state());
1069         add_edge(ptnode_adr(new_load->_idx), ptnode_adr(new_addp->_idx)->as_Field());
1070       }
1071     }
1072   }
1073 }
1074 
1075 void ConnectionGraph::reduce_phi_on_field_access(Node* previous_addp, GrowableArray<Node *>  &alloc_worklist) {
1076   // We'll pass this to 'split_through_phi' so that it'll do the split even
1077   // though the load doesn't have an unique instance type.
1078   bool ignore_missing_instance_id = true;
1079 
1080   // All AddPs are present in the connection graph
1081   FieldNode* fn = ptnode_adr(previous_addp->_idx)->as_Field();
1082 
1083   // Iterate over AddP looking for a Load
1084   for (int k = previous_addp->outcnt()-1; k >= 0;) {
1085     Node* previous_load = previous_addp->raw_out(k);
1086     if (previous_load->is_Load()) {
1087       Node* data_phi = previous_load->as_Load()->split_through_phi(_igvn, ignore_missing_instance_id);
1088 
1089       // Takes care of updating CG and split_unique_types worklists due to cloned
1090       // AddP->Load.
1091       updates_after_load_split(data_phi, previous_load, alloc_worklist);
1092 
1093       _igvn->replace_node(previous_load, data_phi);
1094     }
1095     --k;
1096     k = MIN2(k, (int)previous_addp->outcnt()-1);
1097   }
1098 
1099   // Remove the old AddP from the processing list because it's dead now
1100   assert(previous_addp->outcnt() == 0, "AddP should be dead now.");
1101   alloc_worklist.remove_if_existing(previous_addp);
1102 }
1103 
1104 // Create a 'selector' Phi based on the inputs of 'ophi'. If index 'i' of the
1105 // selector is:
1106 //    -> a '-1' constant, the i'th input of the original Phi is NSR.
1107 //    -> a 'x' constant >=0, the i'th input of of original Phi will be SR and
1108 //       the info about the scalarized object will be at index x of ObjectMergeValue::possible_objects
1109 PhiNode* ConnectionGraph::create_selector(PhiNode* ophi) const {
1110   Node* minus_one = _igvn->register_new_node_with_optimizer(ConINode::make(-1));
1111   Node* selector  = _igvn->register_new_node_with_optimizer(PhiNode::make(ophi->region(), minus_one, TypeInt::INT));
1112   uint number_of_sr_objects = 0;
1113   for (uint i = 1; i < ophi->req(); i++) {
1114     Node* base = ophi->in(i);
1115     JavaObjectNode* ptn = unique_java_object(base);
1116 
1117     if (ptn != nullptr && ptn->scalar_replaceable()) {
1118       Node* sr_obj_idx = _igvn->register_new_node_with_optimizer(ConINode::make(number_of_sr_objects));
1119       selector->set_req(i, sr_obj_idx);
1120       number_of_sr_objects++;
1121     }
1122   }
1123 
1124   return selector->as_Phi();
1125 }
1126 
1127 // Returns true if the AddP node 'n' has at least one base that is a reducible
1128 // merge. If the base is a CastPP/CheckCastPP then the input of the cast is
1129 // checked instead.
1130 bool ConnectionGraph::has_reducible_merge_base(AddPNode* n, Unique_Node_List &reducible_merges) {
1131   PointsToNode* ptn = ptnode_adr(n->_idx);
1132   if (ptn == nullptr || !ptn->is_Field() || ptn->as_Field()->base_count() < 2) {
1133     return false;
1134   }
1135 
1136   for (BaseIterator i(ptn->as_Field()); i.has_next(); i.next()) {
1137     Node* base = i.get()->ideal_node();
1138 
1139     if (reducible_merges.member(base)) {
1140       return true;
1141     }
1142 
1143     if (base->is_CastPP() || base->is_CheckCastPP()) {
1144       base = base->in(1);
1145       if (reducible_merges.member(base)) {
1146         return true;
1147       }
1148     }
1149   }
1150 
1151   return false;
1152 }
1153 
1154 // This method will call its helper method to reduce SafePoint nodes that use
1155 // 'ophi' or a casted version of 'ophi'. All SafePoint nodes using the same
1156 // "version" of Phi use the same debug information (regarding the Phi).
1157 // Therefore, I collect all safepoints and patch them all at once.
1158 //
1159 // The safepoints using the Phi node have to be processed before safepoints of
1160 // CastPP nodes. The reason is, when reducing a CastPP we add a reference (the
1161 // NSR merge pointer) to the input of the CastPP (i.e., the Phi) in the
1162 // safepoint. If we process CastPP's safepoints before Phi's safepoints the
1163 // algorithm that process Phi's safepoints will think that the added Phi
1164 // reference is a regular reference.
1165 bool ConnectionGraph::reduce_phi_on_safepoints(PhiNode* ophi) {
1166   PhiNode* selector = create_selector(ophi);
1167   Unique_Node_List safepoints;
1168   Unique_Node_List casts;
1169 
1170   // Just collect the users of the Phis for later processing
1171   // in the needed order.
1172   for (uint i = 0; i < ophi->outcnt(); i++) {
1173     Node* use = ophi->raw_out(i);
1174     if (use->is_SafePoint()) {
1175       safepoints.push(use);
1176     } else if (use->is_CastPP()) {
1177       casts.push(use);
1178     } else {
1179       assert(use->outcnt() == 0, "Only CastPP & SafePoint users should be left.");
1180     }
1181   }
1182 
1183   // Need to process safepoints using the Phi first
1184   if (!reduce_phi_on_safepoints_helper(ophi, nullptr, selector, safepoints)) {
1185     return false;
1186   }
1187 
1188   // Now process CastPP->safepoints
1189   for (uint i = 0; i < casts.size(); i++) {
1190     Node* cast = casts.at(i);
1191     Unique_Node_List cast_sfpts;
1192 
1193     for (DUIterator_Fast jmax, j = cast->fast_outs(jmax); j < jmax; j++) {
1194       Node* use_use = cast->fast_out(j);
1195       if (use_use->is_SafePoint()) {
1196         cast_sfpts.push(use_use);
1197       } else {
1198         assert(use_use->outcnt() == 0, "Only SafePoint users should be left.");
1199       }
1200     }
1201 
1202     if (!reduce_phi_on_safepoints_helper(ophi, cast, selector, cast_sfpts)) {
1203       return false;
1204     }
1205   }
1206 
1207   return true;
1208 }
1209 
1210 // This method will create a SafePointScalarMERGEnode for each SafePoint in
1211 // 'safepoints'. It then will iterate on the inputs of 'ophi' and create a
1212 // SafePointScalarObjectNode for each scalar replaceable input. Each
1213 // SafePointScalarMergeNode may describe multiple scalar replaced objects -
1214 // check detailed description in SafePointScalarMergeNode class header.
1215 bool ConnectionGraph::reduce_phi_on_safepoints_helper(Node* ophi, Node* cast, Node* selector, Unique_Node_List& safepoints) {
1216   PhaseMacroExpand mexp(*_igvn);
1217   Node* original_sfpt_parent =  cast != nullptr ? cast : ophi;
1218   const TypeOopPtr* merge_t = _igvn->type(original_sfpt_parent)->make_oopptr();
1219 
1220   Node* nsr_merge_pointer = ophi;
1221   if (cast != nullptr) {
1222     const Type* new_t = merge_t->meet(TypePtr::NULL_PTR);
1223     nsr_merge_pointer = _igvn->transform(ConstraintCastNode::make_cast_for_type(cast->in(0), cast->in(1), new_t, ConstraintCastNode::RegularDependency, nullptr));
1224   }
1225 
1226   for (uint spi = 0; spi < safepoints.size(); spi++) {
1227     SafePointNode* sfpt = safepoints.at(spi)->as_SafePoint();
1228     JVMState *jvms      = sfpt->jvms();
1229     uint merge_idx      = (sfpt->req() - jvms->scloff());
1230     int debug_start     = jvms->debug_start();
1231 
1232     SafePointScalarMergeNode* smerge = new SafePointScalarMergeNode(merge_t, merge_idx);
1233     smerge->init_req(0, _compile->root());
1234     _igvn->register_new_node_with_optimizer(smerge);
1235 
1236     // The next two inputs are:
1237     //  (1) A copy of the original pointer to NSR objects.
1238     //  (2) A selector, used to decide if we need to rematerialize an object
1239     //      or use the pointer to a NSR object.
1240     // See more details of these fields in the declaration of SafePointScalarMergeNode
1241     sfpt->add_req(nsr_merge_pointer);
1242     sfpt->add_req(selector);
1243 
1244     for (uint i = 1; i < ophi->req(); i++) {
1245       Node* base = ophi->in(i);
1246       JavaObjectNode* ptn = unique_java_object(base);
1247 
1248       // If the base is not scalar replaceable we don't need to register information about
1249       // it at this time.
1250       if (ptn == nullptr || !ptn->scalar_replaceable()) {
1251         continue;
1252       }
1253 
1254       AllocateNode* alloc = ptn->ideal_node()->as_Allocate();
1255       SafePointScalarObjectNode* sobj = mexp.create_scalarized_object_description(alloc, sfpt);
1256       if (sobj == nullptr) {
1257         return false;
1258       }
1259 
1260       // Now make a pass over the debug information replacing any references
1261       // to the allocated object with "sobj"
1262       Node* ccpp = alloc->result_cast();
1263       sfpt->replace_edges_in_range(ccpp, sobj, debug_start, jvms->debug_end(), _igvn);
1264 
1265       // Register the scalarized object as a candidate for reallocation
1266       smerge->add_req(sobj);
1267     }
1268 
1269     // Replaces debug information references to "original_sfpt_parent" in "sfpt" with references to "smerge"
1270     sfpt->replace_edges_in_range(original_sfpt_parent, smerge, debug_start, jvms->debug_end(), _igvn);
1271 
1272     // The call to 'replace_edges_in_range' above might have removed the
1273     // reference to ophi that we need at _merge_pointer_idx. The line below make
1274     // sure the reference is maintained.
1275     sfpt->set_req(smerge->merge_pointer_idx(jvms), nsr_merge_pointer);
1276     _igvn->_worklist.push(sfpt);
1277   }
1278 
1279   return true;
1280 }
1281 
1282 void ConnectionGraph::reduce_phi(PhiNode* ophi, GrowableArray<Node *>  &alloc_worklist, GrowableArray<Node *>  &memnode_worklist) {
1283   bool delay = _igvn->delay_transform();
1284   _igvn->set_delay_transform(true);
1285   _igvn->hash_delete(ophi);
1286 
1287   // Copying all users first because some will be removed and others won't.
1288   // Ophi also may acquire some new users as part of Cast reduction.
1289   // CastPPs also need to be processed before CmpPs.
1290   Unique_Node_List castpps;
1291   Unique_Node_List others;
1292   for (DUIterator_Fast imax, i = ophi->fast_outs(imax); i < imax; i++) {
1293     Node* use = ophi->fast_out(i);
1294 
1295     if (use->is_CastPP()) {
1296       castpps.push(use);
1297     } else if (use->is_AddP() || use->is_Cmp()) {
1298       others.push(use);
1299     } else if (use->is_SafePoint()) {
1300       // processed later
1301     } else {
1302       assert(use->is_SafePoint(), "Unexpected user of reducible Phi %d -> %d:%s:%d", ophi->_idx, use->_idx, use->Name(), use->outcnt());
1303     }
1304   }
1305 
1306   // CastPPs need to be processed before Cmps because during the process of
1307   // splitting CastPPs we make reference to the inputs of the Cmp that is used
1308   // by the If controlling the CastPP.
1309   for (uint i = 0; i < castpps.size(); i++) {
1310     reduce_phi_on_castpp_field_load(castpps.at(i), alloc_worklist, memnode_worklist);
1311   }
1312 
1313   for (uint i = 0; i < others.size(); i++) {
1314     Node* use = others.at(i);
1315 
1316     if (use->is_AddP()) {
1317       reduce_phi_on_field_access(use, alloc_worklist);
1318     } else if(use->is_Cmp()) {
1319       reduce_phi_on_cmp(use);
1320     }
1321   }
1322 
1323   _igvn->set_delay_transform(delay);
1324 }
1325 
1326 void ConnectionGraph::reset_scalar_replaceable_entries(PhiNode* ophi) {
1327   Node* null_ptr            = _igvn->makecon(TypePtr::NULL_PTR);
1328   const TypeOopPtr* merge_t = _igvn->type(ophi)->make_oopptr();
1329   const Type* new_t         = merge_t->meet(TypePtr::NULL_PTR);
1330   Node* new_phi             = _igvn->register_new_node_with_optimizer(PhiNode::make(ophi->region(), null_ptr, new_t));
1331 
1332   for (uint i = 1; i < ophi->req(); i++) {
1333     Node* base          = ophi->in(i);
1334     JavaObjectNode* ptn = unique_java_object(base);
1335 
1336     if (ptn != nullptr && ptn->scalar_replaceable()) {
1337       new_phi->set_req(i, null_ptr);
1338     } else {
1339       new_phi->set_req(i, ophi->in(i));
1340     }
1341   }
1342 
1343   for (int i = ophi->outcnt()-1; i >= 0;) {
1344     Node* out = ophi->raw_out(i);
1345 
1346     if (out->is_ConstraintCast()) {
1347       const Type* out_t = _igvn->type(out)->make_ptr();
1348       const Type* out_new_t = out_t->meet(TypePtr::NULL_PTR);
1349       bool change = out_new_t != out_t;
1350 
1351       for (int j = out->outcnt()-1; change && j >= 0; --j) {
1352         Node* out2 = out->raw_out(j);
1353         if (!out2->is_SafePoint()) {
1354           change = false;
1355           break;
1356         }
1357       }
1358 
1359       if (change) {
1360         Node* new_cast = ConstraintCastNode::make_cast_for_type(out->in(0), out->in(1), out_new_t, ConstraintCastNode::StrongDependency, nullptr);
1361         _igvn->replace_node(out, new_cast);
1362         _igvn->register_new_node_with_optimizer(new_cast);
1363       }
1364     }
1365 
1366     --i;
1367     i = MIN2(i, (int)ophi->outcnt()-1);
1368   }
1369 
1370   _igvn->replace_node(ophi, new_phi);
1371 }
1372 
1373 void ConnectionGraph::verify_ram_nodes(Compile* C, Node* root) {
1374   if (!C->do_reduce_allocation_merges()) return;
1375 
1376   Unique_Node_List ideal_nodes;
1377   ideal_nodes.map(C->live_nodes(), nullptr);  // preallocate space
1378   ideal_nodes.push(root);
1379 
1380   for (uint next = 0; next < ideal_nodes.size(); ++next) {
1381     Node* n = ideal_nodes.at(next);
1382 
1383     if (n->is_SafePointScalarMerge()) {
1384       SafePointScalarMergeNode* merge = n->as_SafePointScalarMerge();
1385 
1386       // Validate inputs of merge
1387       for (uint i = 1; i < merge->req(); i++) {
1388         if (merge->in(i) != nullptr && !merge->in(i)->is_top() && !merge->in(i)->is_SafePointScalarObject()) {
1389           assert(false, "SafePointScalarMerge inputs should be null/top or SafePointScalarObject.");
1390           C->record_failure(C2Compiler::retry_no_reduce_allocation_merges());
1391         }
1392       }
1393 
1394       // Validate users of merge
1395       for (DUIterator_Fast imax, i = merge->fast_outs(imax); i < imax; i++) {
1396         Node* sfpt = merge->fast_out(i);
1397         if (sfpt->is_SafePoint()) {
1398           int merge_idx = merge->merge_pointer_idx(sfpt->as_SafePoint()->jvms());
1399 
1400           if (sfpt->in(merge_idx) != nullptr && sfpt->in(merge_idx)->is_SafePointScalarMerge()) {
1401             assert(false, "SafePointScalarMerge nodes can't be nested.");
1402             C->record_failure(C2Compiler::retry_no_reduce_allocation_merges());
1403           }
1404         } else {
1405           assert(false, "Only safepoints can use SafePointScalarMerge nodes.");
1406           C->record_failure(C2Compiler::retry_no_reduce_allocation_merges());
1407         }
1408       }
1409     }
1410 
1411     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1412       Node* m = n->fast_out(i);
1413       ideal_nodes.push(m);
1414     }
1415   }
1416 }
1417 
1418 // Returns true if there is an object in the scope of sfn that does not escape globally.
1419 bool ConnectionGraph::has_ea_local_in_scope(SafePointNode* sfn) {
1420   Compile* C = _compile;
1421   for (JVMState* jvms = sfn->jvms(); jvms != nullptr; jvms = jvms->caller()) {
1422     if (C->env()->should_retain_local_variables() || C->env()->jvmti_can_walk_any_space() ||
1423         DeoptimizeObjectsALot) {
1424       // Jvmti agents can access locals. Must provide info about local objects at runtime.
1425       int num_locs = jvms->loc_size();
1426       for (int idx = 0; idx < num_locs; idx++) {
1427         Node* l = sfn->local(jvms, idx);
1428         if (not_global_escape(l)) {
1429           return true;
1430         }
1431       }
1432     }
1433     if (C->env()->jvmti_can_get_owned_monitor_info() ||
1434         C->env()->jvmti_can_walk_any_space() || DeoptimizeObjectsALot) {
1435       // Jvmti agents can read monitors. Must provide info about locked objects at runtime.
1436       int num_mon = jvms->nof_monitors();
1437       for (int idx = 0; idx < num_mon; idx++) {
1438         Node* m = sfn->monitor_obj(jvms, idx);
1439         if (m != nullptr && not_global_escape(m)) {
1440           return true;
1441         }
1442       }
1443     }
1444   }
1445   return false;
1446 }
1447 
1448 // Returns true if at least one of the arguments to the call is an object
1449 // that does not escape globally.
1450 bool ConnectionGraph::has_arg_escape(CallJavaNode* call) {
1451   if (call->method() != nullptr) {
1452     uint max_idx = TypeFunc::Parms + call->method()->arg_size();
1453     for (uint idx = TypeFunc::Parms; idx < max_idx; idx++) {
1454       Node* p = call->in(idx);
1455       if (not_global_escape(p)) {
1456         return true;
1457       }
1458     }
1459   } else {
1460     const char* name = call->as_CallStaticJava()->_name;
1461     assert(name != nullptr, "no name");
1462     // no arg escapes through uncommon traps
1463     if (strcmp(name, "uncommon_trap") != 0) {
1464       // process_call_arguments() assumes that all arguments escape globally
1465       const TypeTuple* d = call->tf()->domain();
1466       for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
1467         const Type* at = d->field_at(i);
1468         if (at->isa_oopptr() != nullptr) {
1469           return true;
1470         }
1471       }
1472     }
1473   }
1474   return false;
1475 }
1476 
1477 
1478 
1479 // Utility function for nodes that load an object
1480 void ConnectionGraph::add_objload_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist) {
1481   // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
1482   // ThreadLocal has RawPtr type.
1483   const Type* t = _igvn->type(n);
1484   if (t->make_ptr() != nullptr) {
1485     Node* adr = n->in(MemNode::Address);
1486 #ifdef ASSERT
1487     if (!adr->is_AddP()) {
1488       assert(_igvn->type(adr)->isa_rawptr(), "sanity");
1489     } else {
1490       assert((ptnode_adr(adr->_idx) == nullptr ||
1491               ptnode_adr(adr->_idx)->as_Field()->is_oop()), "sanity");
1492     }
1493 #endif
1494     add_local_var_and_edge(n, PointsToNode::NoEscape,
1495                            adr, delayed_worklist);
1496   }
1497 }
1498 
1499 // Populate Connection Graph with PointsTo nodes and create simple
1500 // connection graph edges.
1501 void ConnectionGraph::add_node_to_connection_graph(Node *n, Unique_Node_List *delayed_worklist) {
1502   assert(!_verify, "this method should not be called for verification");
1503   PhaseGVN* igvn = _igvn;
1504   uint n_idx = n->_idx;
1505   PointsToNode* n_ptn = ptnode_adr(n_idx);
1506   if (n_ptn != nullptr) {
1507     return; // No need to redefine PointsTo node during first iteration.
1508   }
1509   int opcode = n->Opcode();
1510   bool gc_handled = BarrierSet::barrier_set()->barrier_set_c2()->escape_add_to_con_graph(this, igvn, delayed_worklist, n, opcode);
1511   if (gc_handled) {
1512     return; // Ignore node if already handled by GC.
1513   }
1514 
1515   if (n->is_Call()) {
1516     // Arguments to allocation and locking don't escape.
1517     if (n->is_AbstractLock()) {
1518       // Put Lock and Unlock nodes on IGVN worklist to process them during
1519       // first IGVN optimization when escape information is still available.
1520       record_for_optimizer(n);
1521     } else if (n->is_Allocate()) {
1522       add_call_node(n->as_Call());
1523       record_for_optimizer(n);
1524     } else {
1525       if (n->is_CallStaticJava()) {
1526         const char* name = n->as_CallStaticJava()->_name;
1527         if (name != nullptr && strcmp(name, "uncommon_trap") == 0) {
1528           return; // Skip uncommon traps
1529         }
1530       }
1531       // Don't mark as processed since call's arguments have to be processed.
1532       delayed_worklist->push(n);
1533       // Check if a call returns an object.
1534       if ((n->as_Call()->returns_pointer() &&
1535            n->as_Call()->proj_out_or_null(TypeFunc::Parms) != nullptr) ||
1536           (n->is_CallStaticJava() &&
1537            n->as_CallStaticJava()->is_boxing_method())) {
1538         add_call_node(n->as_Call());
1539       }
1540     }
1541     return;
1542   }
1543   // Put this check here to process call arguments since some call nodes
1544   // point to phantom_obj.
1545   if (n_ptn == phantom_obj || n_ptn == null_obj) {
1546     return; // Skip predefined nodes.
1547   }
1548   switch (opcode) {
1549     case Op_AddP: {
1550       Node* base = get_addp_base(n);
1551       PointsToNode* ptn_base = ptnode_adr(base->_idx);
1552       // Field nodes are created for all field types. They are used in
1553       // adjust_scalar_replaceable_state() and split_unique_types().
1554       // Note, non-oop fields will have only base edges in Connection
1555       // Graph because such fields are not used for oop loads and stores.
1556       int offset = address_offset(n, igvn);
1557       add_field(n, PointsToNode::NoEscape, offset);
1558       if (ptn_base == nullptr) {
1559         delayed_worklist->push(n); // Process it later.
1560       } else {
1561         n_ptn = ptnode_adr(n_idx);
1562         add_base(n_ptn->as_Field(), ptn_base);
1563       }
1564       break;
1565     }
1566     case Op_CastX2P: {
1567       map_ideal_node(n, phantom_obj);
1568       break;
1569     }
1570     case Op_CastPP:
1571     case Op_CheckCastPP:
1572     case Op_EncodeP:
1573     case Op_DecodeN:
1574     case Op_EncodePKlass:
1575     case Op_DecodeNKlass: {
1576       add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), delayed_worklist);
1577       break;
1578     }
1579     case Op_CMoveP: {
1580       add_local_var(n, PointsToNode::NoEscape);
1581       // Do not add edges during first iteration because some could be
1582       // not defined yet.
1583       delayed_worklist->push(n);
1584       break;
1585     }
1586     case Op_ConP:
1587     case Op_ConN:
1588     case Op_ConNKlass: {
1589       // assume all oop constants globally escape except for null
1590       PointsToNode::EscapeState es;
1591       const Type* t = igvn->type(n);
1592       if (t == TypePtr::NULL_PTR || t == TypeNarrowOop::NULL_PTR) {
1593         es = PointsToNode::NoEscape;
1594       } else {
1595         es = PointsToNode::GlobalEscape;
1596       }
1597       PointsToNode* ptn_con = add_java_object(n, es);
1598       set_not_scalar_replaceable(ptn_con NOT_PRODUCT(COMMA "Constant pointer"));
1599       break;
1600     }
1601     case Op_CreateEx: {
1602       // assume that all exception objects globally escape
1603       map_ideal_node(n, phantom_obj);
1604       break;
1605     }
1606     case Op_LoadKlass:
1607     case Op_LoadNKlass: {
1608       // Unknown class is loaded
1609       map_ideal_node(n, phantom_obj);
1610       break;
1611     }
1612     case Op_LoadP:
1613     case Op_LoadN: {
1614       add_objload_to_connection_graph(n, delayed_worklist);
1615       break;
1616     }
1617     case Op_Parm: {
1618       map_ideal_node(n, phantom_obj);
1619       break;
1620     }
1621     case Op_PartialSubtypeCheck: {
1622       // Produces Null or notNull and is used in only in CmpP so
1623       // phantom_obj could be used.
1624       map_ideal_node(n, phantom_obj); // Result is unknown
1625       break;
1626     }
1627     case Op_Phi: {
1628       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
1629       // ThreadLocal has RawPtr type.
1630       const Type* t = n->as_Phi()->type();
1631       if (t->make_ptr() != nullptr) {
1632         add_local_var(n, PointsToNode::NoEscape);
1633         // Do not add edges during first iteration because some could be
1634         // not defined yet.
1635         delayed_worklist->push(n);
1636       }
1637       break;
1638     }
1639     case Op_Proj: {
1640       // we are only interested in the oop result projection from a call
1641       if (n->as_Proj()->_con == TypeFunc::Parms && n->in(0)->is_Call() &&
1642           n->in(0)->as_Call()->returns_pointer()) {
1643         add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(0), delayed_worklist);
1644       }
1645       break;
1646     }
1647     case Op_Rethrow: // Exception object escapes
1648     case Op_Return: {
1649       if (n->req() > TypeFunc::Parms &&
1650           igvn->type(n->in(TypeFunc::Parms))->isa_oopptr()) {
1651         // Treat Return value as LocalVar with GlobalEscape escape state.
1652         add_local_var_and_edge(n, PointsToNode::GlobalEscape, n->in(TypeFunc::Parms), delayed_worklist);
1653       }
1654       break;
1655     }
1656     case Op_CompareAndExchangeP:
1657     case Op_CompareAndExchangeN:
1658     case Op_GetAndSetP:
1659     case Op_GetAndSetN: {
1660       add_objload_to_connection_graph(n, delayed_worklist);
1661       // fall-through
1662     }
1663     case Op_StoreP:
1664     case Op_StoreN:
1665     case Op_StoreNKlass:
1666     case Op_WeakCompareAndSwapP:
1667     case Op_WeakCompareAndSwapN:
1668     case Op_CompareAndSwapP:
1669     case Op_CompareAndSwapN: {
1670       add_to_congraph_unsafe_access(n, opcode, delayed_worklist);
1671       break;
1672     }
1673     case Op_AryEq:
1674     case Op_CountPositives:
1675     case Op_StrComp:
1676     case Op_StrEquals:
1677     case Op_StrIndexOf:
1678     case Op_StrIndexOfChar:
1679     case Op_StrInflatedCopy:
1680     case Op_StrCompressedCopy:
1681     case Op_VectorizedHashCode:
1682     case Op_EncodeISOArray: {
1683       add_local_var(n, PointsToNode::ArgEscape);
1684       delayed_worklist->push(n); // Process it later.
1685       break;
1686     }
1687     case Op_ThreadLocal: {
1688       PointsToNode* ptn_thr = add_java_object(n, PointsToNode::ArgEscape);
1689       set_not_scalar_replaceable(ptn_thr NOT_PRODUCT(COMMA "Constant pointer"));
1690       break;
1691     }
1692     case Op_Blackhole: {
1693       // All blackhole pointer arguments are globally escaping.
1694       // Only do this if there is at least one pointer argument.
1695       // Do not add edges during first iteration because some could be
1696       // not defined yet, defer to final step.
1697       for (uint i = 0; i < n->req(); i++) {
1698         Node* in = n->in(i);
1699         if (in != nullptr) {
1700           const Type* at = _igvn->type(in);
1701           if (!at->isa_ptr()) continue;
1702 
1703           add_local_var(n, PointsToNode::GlobalEscape);
1704           delayed_worklist->push(n);
1705           break;
1706         }
1707       }
1708       break;
1709     }
1710     default:
1711       ; // Do nothing for nodes not related to EA.
1712   }
1713   return;
1714 }
1715 
1716 // Add final simple edges to graph.
1717 void ConnectionGraph::add_final_edges(Node *n) {
1718   PointsToNode* n_ptn = ptnode_adr(n->_idx);
1719 #ifdef ASSERT
1720   if (_verify && n_ptn->is_JavaObject())
1721     return; // This method does not change graph for JavaObject.
1722 #endif
1723 
1724   if (n->is_Call()) {
1725     process_call_arguments(n->as_Call());
1726     return;
1727   }
1728   assert(n->is_Store() || n->is_LoadStore() ||
1729          ((n_ptn != nullptr) && (n_ptn->ideal_node() != nullptr)),
1730          "node should be registered already");
1731   int opcode = n->Opcode();
1732   bool gc_handled = BarrierSet::barrier_set()->barrier_set_c2()->escape_add_final_edges(this, _igvn, n, opcode);
1733   if (gc_handled) {
1734     return; // Ignore node if already handled by GC.
1735   }
1736   switch (opcode) {
1737     case Op_AddP: {
1738       Node* base = get_addp_base(n);
1739       PointsToNode* ptn_base = ptnode_adr(base->_idx);
1740       assert(ptn_base != nullptr, "field's base should be registered");
1741       add_base(n_ptn->as_Field(), ptn_base);
1742       break;
1743     }
1744     case Op_CastPP:
1745     case Op_CheckCastPP:
1746     case Op_EncodeP:
1747     case Op_DecodeN:
1748     case Op_EncodePKlass:
1749     case Op_DecodeNKlass: {
1750       add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), nullptr);
1751       break;
1752     }
1753     case Op_CMoveP: {
1754       for (uint i = CMoveNode::IfFalse; i < n->req(); i++) {
1755         Node* in = n->in(i);
1756         if (in == nullptr) {
1757           continue;  // ignore null
1758         }
1759         Node* uncast_in = in->uncast();
1760         if (uncast_in->is_top() || uncast_in == n) {
1761           continue;  // ignore top or inputs which go back this node
1762         }
1763         PointsToNode* ptn = ptnode_adr(in->_idx);
1764         assert(ptn != nullptr, "node should be registered");
1765         add_edge(n_ptn, ptn);
1766       }
1767       break;
1768     }
1769     case Op_LoadP:
1770     case Op_LoadN: {
1771       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
1772       // ThreadLocal has RawPtr type.
1773       assert(_igvn->type(n)->make_ptr() != nullptr, "Unexpected node type");
1774       add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(MemNode::Address), nullptr);
1775       break;
1776     }
1777     case Op_Phi: {
1778       // Using isa_ptr() instead of isa_oopptr() for LoadP and Phi because
1779       // ThreadLocal has RawPtr type.
1780       assert(n->as_Phi()->type()->make_ptr() != nullptr, "Unexpected node type");
1781       for (uint i = 1; i < n->req(); i++) {
1782         Node* in = n->in(i);
1783         if (in == nullptr) {
1784           continue;  // ignore null
1785         }
1786         Node* uncast_in = in->uncast();
1787         if (uncast_in->is_top() || uncast_in == n) {
1788           continue;  // ignore top or inputs which go back this node
1789         }
1790         PointsToNode* ptn = ptnode_adr(in->_idx);
1791         assert(ptn != nullptr, "node should be registered");
1792         add_edge(n_ptn, ptn);
1793       }
1794       break;
1795     }
1796     case Op_Proj: {
1797       // we are only interested in the oop result projection from a call
1798       assert(n->as_Proj()->_con == TypeFunc::Parms && n->in(0)->is_Call() &&
1799              n->in(0)->as_Call()->returns_pointer(), "Unexpected node type");
1800       add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(0), nullptr);
1801       break;
1802     }
1803     case Op_Rethrow: // Exception object escapes
1804     case Op_Return: {
1805       assert(n->req() > TypeFunc::Parms && _igvn->type(n->in(TypeFunc::Parms))->isa_oopptr(),
1806              "Unexpected node type");
1807       // Treat Return value as LocalVar with GlobalEscape escape state.
1808       add_local_var_and_edge(n, PointsToNode::GlobalEscape, n->in(TypeFunc::Parms), nullptr);
1809       break;
1810     }
1811     case Op_CompareAndExchangeP:
1812     case Op_CompareAndExchangeN:
1813     case Op_GetAndSetP:
1814     case Op_GetAndSetN:{
1815       assert(_igvn->type(n)->make_ptr() != nullptr, "Unexpected node type");
1816       add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(MemNode::Address), nullptr);
1817       // fall-through
1818     }
1819     case Op_CompareAndSwapP:
1820     case Op_CompareAndSwapN:
1821     case Op_WeakCompareAndSwapP:
1822     case Op_WeakCompareAndSwapN:
1823     case Op_StoreP:
1824     case Op_StoreN:
1825     case Op_StoreNKlass:{
1826       add_final_edges_unsafe_access(n, opcode);
1827       break;
1828     }
1829     case Op_VectorizedHashCode:
1830     case Op_AryEq:
1831     case Op_CountPositives:
1832     case Op_StrComp:
1833     case Op_StrEquals:
1834     case Op_StrIndexOf:
1835     case Op_StrIndexOfChar:
1836     case Op_StrInflatedCopy:
1837     case Op_StrCompressedCopy:
1838     case Op_EncodeISOArray: {
1839       // char[]/byte[] arrays passed to string intrinsic do not escape but
1840       // they are not scalar replaceable. Adjust escape state for them.
1841       // Start from in(2) edge since in(1) is memory edge.
1842       for (uint i = 2; i < n->req(); i++) {
1843         Node* adr = n->in(i);
1844         const Type* at = _igvn->type(adr);
1845         if (!adr->is_top() && at->isa_ptr()) {
1846           assert(at == Type::TOP || at == TypePtr::NULL_PTR ||
1847                  at->isa_ptr() != nullptr, "expecting a pointer");
1848           if (adr->is_AddP()) {
1849             adr = get_addp_base(adr);
1850           }
1851           PointsToNode* ptn = ptnode_adr(adr->_idx);
1852           assert(ptn != nullptr, "node should be registered");
1853           add_edge(n_ptn, ptn);
1854         }
1855       }
1856       break;
1857     }
1858     case Op_Blackhole: {
1859       // All blackhole pointer arguments are globally escaping.
1860       for (uint i = 0; i < n->req(); i++) {
1861         Node* in = n->in(i);
1862         if (in != nullptr) {
1863           const Type* at = _igvn->type(in);
1864           if (!at->isa_ptr()) continue;
1865 
1866           if (in->is_AddP()) {
1867             in = get_addp_base(in);
1868           }
1869 
1870           PointsToNode* ptn = ptnode_adr(in->_idx);
1871           assert(ptn != nullptr, "should be defined already");
1872           set_escape_state(ptn, PointsToNode::GlobalEscape NOT_PRODUCT(COMMA "blackhole"));
1873           add_edge(n_ptn, ptn);
1874         }
1875       }
1876       break;
1877     }
1878     default: {
1879       // This method should be called only for EA specific nodes which may
1880       // miss some edges when they were created.
1881 #ifdef ASSERT
1882       n->dump(1);
1883 #endif
1884       guarantee(false, "unknown node");
1885     }
1886   }
1887   return;
1888 }
1889 
1890 void ConnectionGraph::add_to_congraph_unsafe_access(Node* n, uint opcode, Unique_Node_List* delayed_worklist) {
1891   Node* adr = n->in(MemNode::Address);
1892   const Type* adr_type = _igvn->type(adr);
1893   adr_type = adr_type->make_ptr();
1894   if (adr_type == nullptr) {
1895     return; // skip dead nodes
1896   }
1897   if (adr_type->isa_oopptr()
1898       || ((opcode == Op_StoreP || opcode == Op_StoreN || opcode == Op_StoreNKlass)
1899           && adr_type == TypeRawPtr::NOTNULL
1900           && is_captured_store_address(adr))) {
1901     delayed_worklist->push(n); // Process it later.
1902 #ifdef ASSERT
1903     assert (adr->is_AddP(), "expecting an AddP");
1904     if (adr_type == TypeRawPtr::NOTNULL) {
1905       // Verify a raw address for a store captured by Initialize node.
1906       int offs = (int) _igvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
1907       assert(offs != Type::OffsetBot, "offset must be a constant");
1908     }
1909 #endif
1910   } else {
1911     // Ignore copy the displaced header to the BoxNode (OSR compilation).
1912     if (adr->is_BoxLock()) {
1913       return;
1914     }
1915     // Stored value escapes in unsafe access.
1916     if ((opcode == Op_StoreP) && adr_type->isa_rawptr()) {
1917       delayed_worklist->push(n); // Process unsafe access later.
1918       return;
1919     }
1920 #ifdef ASSERT
1921     n->dump(1);
1922     assert(false, "not unsafe");
1923 #endif
1924   }
1925 }
1926 
1927 bool ConnectionGraph::add_final_edges_unsafe_access(Node* n, uint opcode) {
1928   Node* adr = n->in(MemNode::Address);
1929   const Type *adr_type = _igvn->type(adr);
1930   adr_type = adr_type->make_ptr();
1931 #ifdef ASSERT
1932   if (adr_type == nullptr) {
1933     n->dump(1);
1934     assert(adr_type != nullptr, "dead node should not be on list");
1935     return true;
1936   }
1937 #endif
1938 
1939   if (adr_type->isa_oopptr()
1940       || ((opcode == Op_StoreP || opcode == Op_StoreN || opcode == Op_StoreNKlass)
1941            && adr_type == TypeRawPtr::NOTNULL
1942            && is_captured_store_address(adr))) {
1943     // Point Address to Value
1944     PointsToNode* adr_ptn = ptnode_adr(adr->_idx);
1945     assert(adr_ptn != nullptr &&
1946            adr_ptn->as_Field()->is_oop(), "node should be registered");
1947     Node* val = n->in(MemNode::ValueIn);
1948     PointsToNode* ptn = ptnode_adr(val->_idx);
1949     assert(ptn != nullptr, "node should be registered");
1950     add_edge(adr_ptn, ptn);
1951     return true;
1952   } else if ((opcode == Op_StoreP) && adr_type->isa_rawptr()) {
1953     // Stored value escapes in unsafe access.
1954     Node* val = n->in(MemNode::ValueIn);
1955     PointsToNode* ptn = ptnode_adr(val->_idx);
1956     assert(ptn != nullptr, "node should be registered");
1957     set_escape_state(ptn, PointsToNode::GlobalEscape NOT_PRODUCT(COMMA "stored at raw address"));
1958     // Add edge to object for unsafe access with offset.
1959     PointsToNode* adr_ptn = ptnode_adr(adr->_idx);
1960     assert(adr_ptn != nullptr, "node should be registered");
1961     if (adr_ptn->is_Field()) {
1962       assert(adr_ptn->as_Field()->is_oop(), "should be oop field");
1963       add_edge(adr_ptn, ptn);
1964     }
1965     return true;
1966   }
1967 #ifdef ASSERT
1968   n->dump(1);
1969   assert(false, "not unsafe");
1970 #endif
1971   return false;
1972 }
1973 
1974 void ConnectionGraph::add_call_node(CallNode* call) {
1975   assert(call->returns_pointer(), "only for call which returns pointer");
1976   uint call_idx = call->_idx;
1977   if (call->is_Allocate()) {
1978     Node* k = call->in(AllocateNode::KlassNode);
1979     const TypeKlassPtr* kt = k->bottom_type()->isa_klassptr();
1980     assert(kt != nullptr, "TypeKlassPtr  required.");
1981     PointsToNode::EscapeState es = PointsToNode::NoEscape;
1982     bool scalar_replaceable = true;
1983     NOT_PRODUCT(const char* nsr_reason = "");
1984     if (call->is_AllocateArray()) {
1985       if (!kt->isa_aryklassptr()) { // StressReflectiveCode
1986         es = PointsToNode::GlobalEscape;
1987       } else {
1988         int length = call->in(AllocateNode::ALength)->find_int_con(-1);
1989         if (length < 0) {
1990           // Not scalar replaceable if the length is not constant.
1991           scalar_replaceable = false;
1992           NOT_PRODUCT(nsr_reason = "has a non-constant length");
1993         } else if (length > EliminateAllocationArraySizeLimit) {
1994           // Not scalar replaceable if the length is too big.
1995           scalar_replaceable = false;
1996           NOT_PRODUCT(nsr_reason = "has a length that is too big");
1997         }
1998       }
1999     } else {  // Allocate instance
2000       if (!kt->isa_instklassptr()) { // StressReflectiveCode
2001         es = PointsToNode::GlobalEscape;
2002       } else {
2003         const TypeInstKlassPtr* ikt = kt->is_instklassptr();
2004         ciInstanceKlass* ik = ikt->klass_is_exact() ? ikt->exact_klass()->as_instance_klass() : ikt->instance_klass();
2005         if (ik->is_subclass_of(_compile->env()->Thread_klass()) ||
2006             ik->is_subclass_of(_compile->env()->Reference_klass()) ||
2007             !ik->can_be_instantiated() ||
2008             ik->has_finalizer()) {
2009           es = PointsToNode::GlobalEscape;
2010         } else {
2011           int nfields = ik->as_instance_klass()->nof_nonstatic_fields();
2012           if (nfields > EliminateAllocationFieldsLimit) {
2013             // Not scalar replaceable if there are too many fields.
2014             scalar_replaceable = false;
2015             NOT_PRODUCT(nsr_reason = "has too many fields");
2016           }
2017         }
2018       }
2019     }
2020     add_java_object(call, es);
2021     PointsToNode* ptn = ptnode_adr(call_idx);
2022     if (!scalar_replaceable && ptn->scalar_replaceable()) {
2023       set_not_scalar_replaceable(ptn NOT_PRODUCT(COMMA nsr_reason));
2024     }
2025   } else if (call->is_CallStaticJava()) {
2026     // Call nodes could be different types:
2027     //
2028     // 1. CallDynamicJavaNode (what happened during call is unknown):
2029     //
2030     //    - mapped to GlobalEscape JavaObject node if oop is returned;
2031     //
2032     //    - all oop arguments are escaping globally;
2033     //
2034     // 2. CallStaticJavaNode (execute bytecode analysis if possible):
2035     //
2036     //    - the same as CallDynamicJavaNode if can't do bytecode analysis;
2037     //
2038     //    - mapped to GlobalEscape JavaObject node if unknown oop is returned;
2039     //    - mapped to NoEscape JavaObject node if non-escaping object allocated
2040     //      during call is returned;
2041     //    - mapped to ArgEscape LocalVar node pointed to object arguments
2042     //      which are returned and does not escape during call;
2043     //
2044     //    - oop arguments escaping status is defined by bytecode analysis;
2045     //
2046     // For a static call, we know exactly what method is being called.
2047     // Use bytecode estimator to record whether the call's return value escapes.
2048     ciMethod* meth = call->as_CallJava()->method();
2049     if (meth == nullptr) {
2050       const char* name = call->as_CallStaticJava()->_name;
2051       assert(strncmp(name, "C2 Runtime multianewarray", 25) == 0, "TODO: add failed case check");
2052       // Returns a newly allocated non-escaped object.
2053       add_java_object(call, PointsToNode::NoEscape);
2054       set_not_scalar_replaceable(ptnode_adr(call_idx) NOT_PRODUCT(COMMA "is result of multinewarray"));
2055     } else if (meth->is_boxing_method()) {
2056       // Returns boxing object
2057       PointsToNode::EscapeState es;
2058       vmIntrinsics::ID intr = meth->intrinsic_id();
2059       if (intr == vmIntrinsics::_floatValue || intr == vmIntrinsics::_doubleValue) {
2060         // It does not escape if object is always allocated.
2061         es = PointsToNode::NoEscape;
2062       } else {
2063         // It escapes globally if object could be loaded from cache.
2064         es = PointsToNode::GlobalEscape;
2065       }
2066       add_java_object(call, es);
2067       if (es == PointsToNode::GlobalEscape) {
2068         set_not_scalar_replaceable(ptnode_adr(call->_idx) NOT_PRODUCT(COMMA "object can be loaded from boxing cache"));
2069       }
2070     } else {
2071       BCEscapeAnalyzer* call_analyzer = meth->get_bcea();
2072       call_analyzer->copy_dependencies(_compile->dependencies());
2073       if (call_analyzer->is_return_allocated()) {
2074         // Returns a newly allocated non-escaped object, simply
2075         // update dependency information.
2076         // Mark it as NoEscape so that objects referenced by
2077         // it's fields will be marked as NoEscape at least.
2078         add_java_object(call, PointsToNode::NoEscape);
2079         set_not_scalar_replaceable(ptnode_adr(call_idx) NOT_PRODUCT(COMMA "is result of call"));
2080       } else {
2081         // Determine whether any arguments are returned.
2082         const TypeTuple* d = call->tf()->domain();
2083         bool ret_arg = false;
2084         for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
2085           if (d->field_at(i)->isa_ptr() != nullptr &&
2086               call_analyzer->is_arg_returned(i - TypeFunc::Parms)) {
2087             ret_arg = true;
2088             break;
2089           }
2090         }
2091         if (ret_arg) {
2092           add_local_var(call, PointsToNode::ArgEscape);
2093         } else {
2094           // Returns unknown object.
2095           map_ideal_node(call, phantom_obj);
2096         }
2097       }
2098     }
2099   } else {
2100     // An other type of call, assume the worst case:
2101     // returned value is unknown and globally escapes.
2102     assert(call->Opcode() == Op_CallDynamicJava, "add failed case check");
2103     map_ideal_node(call, phantom_obj);
2104   }
2105 }
2106 
2107 void ConnectionGraph::process_call_arguments(CallNode *call) {
2108     bool is_arraycopy = false;
2109     switch (call->Opcode()) {
2110 #ifdef ASSERT
2111     case Op_Allocate:
2112     case Op_AllocateArray:
2113     case Op_Lock:
2114     case Op_Unlock:
2115       assert(false, "should be done already");
2116       break;
2117 #endif
2118     case Op_ArrayCopy:
2119     case Op_CallLeafNoFP:
2120       // Most array copies are ArrayCopy nodes at this point but there
2121       // are still a few direct calls to the copy subroutines (See
2122       // PhaseStringOpts::copy_string())
2123       is_arraycopy = (call->Opcode() == Op_ArrayCopy) ||
2124         call->as_CallLeaf()->is_call_to_arraycopystub();
2125       // fall through
2126     case Op_CallLeafVector:
2127     case Op_CallLeaf: {
2128       // Stub calls, objects do not escape but they are not scale replaceable.
2129       // Adjust escape state for outgoing arguments.
2130       const TypeTuple * d = call->tf()->domain();
2131       bool src_has_oops = false;
2132       for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
2133         const Type* at = d->field_at(i);
2134         Node *arg = call->in(i);
2135         if (arg == nullptr) {
2136           continue;
2137         }
2138         const Type *aat = _igvn->type(arg);
2139         if (arg->is_top() || !at->isa_ptr() || !aat->isa_ptr()) {
2140           continue;
2141         }
2142         if (arg->is_AddP()) {
2143           //
2144           // The inline_native_clone() case when the arraycopy stub is called
2145           // after the allocation before Initialize and CheckCastPP nodes.
2146           // Or normal arraycopy for object arrays case.
2147           //
2148           // Set AddP's base (Allocate) as not scalar replaceable since
2149           // pointer to the base (with offset) is passed as argument.
2150           //
2151           arg = get_addp_base(arg);
2152         }
2153         PointsToNode* arg_ptn = ptnode_adr(arg->_idx);
2154         assert(arg_ptn != nullptr, "should be registered");
2155         PointsToNode::EscapeState arg_esc = arg_ptn->escape_state();
2156         if (is_arraycopy || arg_esc < PointsToNode::ArgEscape) {
2157           assert(aat == Type::TOP || aat == TypePtr::NULL_PTR ||
2158                  aat->isa_ptr() != nullptr, "expecting an Ptr");
2159           bool arg_has_oops = aat->isa_oopptr() &&
2160                               (aat->isa_instptr() ||
2161                                (aat->isa_aryptr() && (aat->isa_aryptr()->elem() == Type::BOTTOM || aat->isa_aryptr()->elem()->make_oopptr() != nullptr)));
2162           if (i == TypeFunc::Parms) {
2163             src_has_oops = arg_has_oops;
2164           }
2165           //
2166           // src or dst could be j.l.Object when other is basic type array:
2167           //
2168           //   arraycopy(char[],0,Object*,0,size);
2169           //   arraycopy(Object*,0,char[],0,size);
2170           //
2171           // Don't add edges in such cases.
2172           //
2173           bool arg_is_arraycopy_dest = src_has_oops && is_arraycopy &&
2174                                        arg_has_oops && (i > TypeFunc::Parms);
2175 #ifdef ASSERT
2176           if (!(is_arraycopy ||
2177                 BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(call) ||
2178                 (call->as_CallLeaf()->_name != nullptr &&
2179                  (strcmp(call->as_CallLeaf()->_name, "updateBytesCRC32") == 0 ||
2180                   strcmp(call->as_CallLeaf()->_name, "updateBytesCRC32C") == 0 ||
2181                   strcmp(call->as_CallLeaf()->_name, "updateBytesAdler32") == 0 ||
2182                   strcmp(call->as_CallLeaf()->_name, "aescrypt_encryptBlock") == 0 ||
2183                   strcmp(call->as_CallLeaf()->_name, "aescrypt_decryptBlock") == 0 ||
2184                   strcmp(call->as_CallLeaf()->_name, "cipherBlockChaining_encryptAESCrypt") == 0 ||
2185                   strcmp(call->as_CallLeaf()->_name, "cipherBlockChaining_decryptAESCrypt") == 0 ||
2186                   strcmp(call->as_CallLeaf()->_name, "electronicCodeBook_encryptAESCrypt") == 0 ||
2187                   strcmp(call->as_CallLeaf()->_name, "electronicCodeBook_decryptAESCrypt") == 0 ||
2188                   strcmp(call->as_CallLeaf()->_name, "counterMode_AESCrypt") == 0 ||
2189                   strcmp(call->as_CallLeaf()->_name, "galoisCounterMode_AESCrypt") == 0 ||
2190                   strcmp(call->as_CallLeaf()->_name, "poly1305_processBlocks") == 0 ||
2191                   strcmp(call->as_CallLeaf()->_name, "intpoly_montgomeryMult_P256") == 0 ||
2192                   strcmp(call->as_CallLeaf()->_name, "intpoly_assign") == 0 ||
2193                   strcmp(call->as_CallLeaf()->_name, "ghash_processBlocks") == 0 ||
2194                   strcmp(call->as_CallLeaf()->_name, "chacha20Block") == 0 ||
2195                   strcmp(call->as_CallLeaf()->_name, "kyberNtt") == 0 ||
2196                   strcmp(call->as_CallLeaf()->_name, "kyberInverseNtt") == 0 ||
2197                   strcmp(call->as_CallLeaf()->_name, "kyberNttMult") == 0 ||
2198                   strcmp(call->as_CallLeaf()->_name, "kyberAddPoly_2") == 0 ||
2199                   strcmp(call->as_CallLeaf()->_name, "kyberAddPoly_3") == 0 ||
2200                   strcmp(call->as_CallLeaf()->_name, "kyber12To16") == 0 ||
2201                   strcmp(call->as_CallLeaf()->_name, "kyberBarrettReduce") == 0 ||
2202                   strcmp(call->as_CallLeaf()->_name, "dilithiumAlmostNtt") == 0 ||
2203                   strcmp(call->as_CallLeaf()->_name, "dilithiumAlmostInverseNtt") == 0 ||
2204                   strcmp(call->as_CallLeaf()->_name, "dilithiumNttMult") == 0 ||
2205                   strcmp(call->as_CallLeaf()->_name, "dilithiumMontMulByConstant") == 0 ||
2206                   strcmp(call->as_CallLeaf()->_name, "dilithiumDecomposePoly") == 0 ||
2207                   strcmp(call->as_CallLeaf()->_name, "encodeBlock") == 0 ||
2208                   strcmp(call->as_CallLeaf()->_name, "decodeBlock") == 0 ||
2209                   strcmp(call->as_CallLeaf()->_name, "md5_implCompress") == 0 ||
2210                   strcmp(call->as_CallLeaf()->_name, "md5_implCompressMB") == 0 ||
2211                   strcmp(call->as_CallLeaf()->_name, "sha1_implCompress") == 0 ||
2212                   strcmp(call->as_CallLeaf()->_name, "sha1_implCompressMB") == 0 ||
2213                   strcmp(call->as_CallLeaf()->_name, "sha256_implCompress") == 0 ||
2214                   strcmp(call->as_CallLeaf()->_name, "sha256_implCompressMB") == 0 ||
2215                   strcmp(call->as_CallLeaf()->_name, "sha512_implCompress") == 0 ||
2216                   strcmp(call->as_CallLeaf()->_name, "sha512_implCompressMB") == 0 ||
2217                   strcmp(call->as_CallLeaf()->_name, "sha3_implCompress") == 0 ||
2218                   strcmp(call->as_CallLeaf()->_name, "double_keccak") == 0 ||
2219                   strcmp(call->as_CallLeaf()->_name, "sha3_implCompressMB") == 0 ||
2220                   strcmp(call->as_CallLeaf()->_name, "multiplyToLen") == 0 ||
2221                   strcmp(call->as_CallLeaf()->_name, "squareToLen") == 0 ||
2222                   strcmp(call->as_CallLeaf()->_name, "mulAdd") == 0 ||
2223                   strcmp(call->as_CallLeaf()->_name, "montgomery_multiply") == 0 ||
2224                   strcmp(call->as_CallLeaf()->_name, "montgomery_square") == 0 ||
2225                   strcmp(call->as_CallLeaf()->_name, "bigIntegerRightShiftWorker") == 0 ||
2226                   strcmp(call->as_CallLeaf()->_name, "bigIntegerLeftShiftWorker") == 0 ||
2227                   strcmp(call->as_CallLeaf()->_name, "vectorizedMismatch") == 0 ||
2228                   strcmp(call->as_CallLeaf()->_name, "stringIndexOf") == 0 ||
2229                   strcmp(call->as_CallLeaf()->_name, "arraysort_stub") == 0 ||
2230                   strcmp(call->as_CallLeaf()->_name, "array_partition_stub") == 0 ||
2231                   strcmp(call->as_CallLeaf()->_name, "get_class_id_intrinsic") == 0 ||
2232                   strcmp(call->as_CallLeaf()->_name, "unsafe_setmemory") == 0)
2233                  ))) {
2234             call->dump();
2235             fatal("EA unexpected CallLeaf %s", call->as_CallLeaf()->_name);
2236           }
2237 #endif
2238           // Always process arraycopy's destination object since
2239           // we need to add all possible edges to references in
2240           // source object.
2241           if (arg_esc >= PointsToNode::ArgEscape &&
2242               !arg_is_arraycopy_dest) {
2243             continue;
2244           }
2245           PointsToNode::EscapeState es = PointsToNode::ArgEscape;
2246           if (call->is_ArrayCopy()) {
2247             ArrayCopyNode* ac = call->as_ArrayCopy();
2248             if (ac->is_clonebasic() ||
2249                 ac->is_arraycopy_validated() ||
2250                 ac->is_copyof_validated() ||
2251                 ac->is_copyofrange_validated()) {
2252               es = PointsToNode::NoEscape;
2253             }
2254           }
2255           set_escape_state(arg_ptn, es NOT_PRODUCT(COMMA trace_arg_escape_message(call)));
2256           if (arg_is_arraycopy_dest) {
2257             Node* src = call->in(TypeFunc::Parms);
2258             if (src->is_AddP()) {
2259               src = get_addp_base(src);
2260             }
2261             PointsToNode* src_ptn = ptnode_adr(src->_idx);
2262             assert(src_ptn != nullptr, "should be registered");
2263             if (arg_ptn != src_ptn) {
2264               // Special arraycopy edge:
2265               // A destination object's field can't have the source object
2266               // as base since objects escape states are not related.
2267               // Only escape state of destination object's fields affects
2268               // escape state of fields in source object.
2269               add_arraycopy(call, es, src_ptn, arg_ptn);
2270             }
2271           }
2272         }
2273       }
2274       break;
2275     }
2276     case Op_CallStaticJava: {
2277       // For a static call, we know exactly what method is being called.
2278       // Use bytecode estimator to record the call's escape affects
2279 #ifdef ASSERT
2280       const char* name = call->as_CallStaticJava()->_name;
2281       assert((name == nullptr || strcmp(name, "uncommon_trap") != 0), "normal calls only");
2282 #endif
2283       ciMethod* meth = call->as_CallJava()->method();
2284       if ((meth != nullptr) && meth->is_boxing_method()) {
2285         break; // Boxing methods do not modify any oops.
2286       }
2287       BCEscapeAnalyzer* call_analyzer = (meth !=nullptr) ? meth->get_bcea() : nullptr;
2288       // fall-through if not a Java method or no analyzer information
2289       if (call_analyzer != nullptr) {
2290         PointsToNode* call_ptn = ptnode_adr(call->_idx);
2291         const TypeTuple* d = call->tf()->domain();
2292         for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
2293           const Type* at = d->field_at(i);
2294           int k = i - TypeFunc::Parms;
2295           Node* arg = call->in(i);
2296           PointsToNode* arg_ptn = ptnode_adr(arg->_idx);
2297           if (at->isa_ptr() != nullptr &&
2298               call_analyzer->is_arg_returned(k)) {
2299             // The call returns arguments.
2300             if (call_ptn != nullptr) { // Is call's result used?
2301               assert(call_ptn->is_LocalVar(), "node should be registered");
2302               assert(arg_ptn != nullptr, "node should be registered");
2303               add_edge(call_ptn, arg_ptn);
2304             }
2305           }
2306           if (at->isa_oopptr() != nullptr &&
2307               arg_ptn->escape_state() < PointsToNode::GlobalEscape) {
2308             if (!call_analyzer->is_arg_stack(k)) {
2309               // The argument global escapes
2310               set_escape_state(arg_ptn, PointsToNode::GlobalEscape NOT_PRODUCT(COMMA trace_arg_escape_message(call)));
2311             } else {
2312               set_escape_state(arg_ptn, PointsToNode::ArgEscape NOT_PRODUCT(COMMA trace_arg_escape_message(call)));
2313               if (!call_analyzer->is_arg_local(k)) {
2314                 // The argument itself doesn't escape, but any fields might
2315                 set_fields_escape_state(arg_ptn, PointsToNode::GlobalEscape NOT_PRODUCT(COMMA trace_arg_escape_message(call)));
2316               }
2317             }
2318           }
2319         }
2320         if (call_ptn != nullptr && call_ptn->is_LocalVar()) {
2321           // The call returns arguments.
2322           assert(call_ptn->edge_count() > 0, "sanity");
2323           if (!call_analyzer->is_return_local()) {
2324             // Returns also unknown object.
2325             add_edge(call_ptn, phantom_obj);
2326           }
2327         }
2328         break;
2329       }
2330     }
2331     default: {
2332       // Fall-through here if not a Java method or no analyzer information
2333       // or some other type of call, assume the worst case: all arguments
2334       // globally escape.
2335       const TypeTuple* d = call->tf()->domain();
2336       for (uint i = TypeFunc::Parms; i < d->cnt(); i++) {
2337         const Type* at = d->field_at(i);
2338         if (at->isa_oopptr() != nullptr) {
2339           Node* arg = call->in(i);
2340           if (arg->is_AddP()) {
2341             arg = get_addp_base(arg);
2342           }
2343           assert(ptnode_adr(arg->_idx) != nullptr, "should be defined already");
2344           set_escape_state(ptnode_adr(arg->_idx), PointsToNode::GlobalEscape NOT_PRODUCT(COMMA trace_arg_escape_message(call)));
2345         }
2346       }
2347     }
2348   }
2349 }
2350 
2351 
2352 // Finish Graph construction.
2353 bool ConnectionGraph::complete_connection_graph(
2354                          GrowableArray<PointsToNode*>&   ptnodes_worklist,
2355                          GrowableArray<JavaObjectNode*>& non_escaped_allocs_worklist,
2356                          GrowableArray<JavaObjectNode*>& java_objects_worklist,
2357                          GrowableArray<FieldNode*>&      oop_fields_worklist) {
2358   // Normally only 1-3 passes needed to build Connection Graph depending
2359   // on graph complexity. Observed 8 passes in jvm2008 compiler.compiler.
2360   // Set limit to 20 to catch situation when something did go wrong and
2361   // bailout Escape Analysis.
2362   // Also limit build time to 20 sec (60 in debug VM), EscapeAnalysisTimeout flag.
2363 #define GRAPH_BUILD_ITER_LIMIT 20
2364 
2365   // Propagate GlobalEscape and ArgEscape escape states and check that
2366   // we still have non-escaping objects. The method pushs on _worklist
2367   // Field nodes which reference phantom_object.
2368   if (!find_non_escaped_objects(ptnodes_worklist, non_escaped_allocs_worklist)) {
2369     return false; // Nothing to do.
2370   }
2371   // Now propagate references to all JavaObject nodes.
2372   int java_objects_length = java_objects_worklist.length();
2373   elapsedTimer build_time;
2374   build_time.start();
2375   elapsedTimer time;
2376   bool timeout = false;
2377   int new_edges = 1;
2378   int iterations = 0;
2379   do {
2380     while ((new_edges > 0) &&
2381            (iterations++ < GRAPH_BUILD_ITER_LIMIT)) {
2382       double start_time = time.seconds();
2383       time.start();
2384       new_edges = 0;
2385       // Propagate references to phantom_object for nodes pushed on _worklist
2386       // by find_non_escaped_objects() and find_field_value().
2387       new_edges += add_java_object_edges(phantom_obj, false);
2388       for (int next = 0; next < java_objects_length; ++next) {
2389         JavaObjectNode* ptn = java_objects_worklist.at(next);
2390         new_edges += add_java_object_edges(ptn, true);
2391 
2392 #define SAMPLE_SIZE 4
2393         if ((next % SAMPLE_SIZE) == 0) {
2394           // Each 4 iterations calculate how much time it will take
2395           // to complete graph construction.
2396           time.stop();
2397           // Poll for requests from shutdown mechanism to quiesce compiler
2398           // because Connection graph construction may take long time.
2399           CompileBroker::maybe_block();
2400           double stop_time = time.seconds();
2401           double time_per_iter = (stop_time - start_time) / (double)SAMPLE_SIZE;
2402           double time_until_end = time_per_iter * (double)(java_objects_length - next);
2403           if ((start_time + time_until_end) >= EscapeAnalysisTimeout) {
2404             timeout = true;
2405             break; // Timeout
2406           }
2407           start_time = stop_time;
2408           time.start();
2409         }
2410 #undef SAMPLE_SIZE
2411 
2412       }
2413       if (timeout) break;
2414       if (new_edges > 0) {
2415         // Update escape states on each iteration if graph was updated.
2416         if (!find_non_escaped_objects(ptnodes_worklist, non_escaped_allocs_worklist)) {
2417           return false; // Nothing to do.
2418         }
2419       }
2420       time.stop();
2421       if (time.seconds() >= EscapeAnalysisTimeout) {
2422         timeout = true;
2423         break;
2424       }
2425     }
2426     if ((iterations < GRAPH_BUILD_ITER_LIMIT) && !timeout) {
2427       time.start();
2428       // Find fields which have unknown value.
2429       int fields_length = oop_fields_worklist.length();
2430       for (int next = 0; next < fields_length; next++) {
2431         FieldNode* field = oop_fields_worklist.at(next);
2432         if (field->edge_count() == 0) {
2433           new_edges += find_field_value(field);
2434           // This code may added new edges to phantom_object.
2435           // Need an other cycle to propagate references to phantom_object.
2436         }
2437       }
2438       time.stop();
2439       if (time.seconds() >= EscapeAnalysisTimeout) {
2440         timeout = true;
2441         break;
2442       }
2443     } else {
2444       new_edges = 0; // Bailout
2445     }
2446   } while (new_edges > 0);
2447 
2448   build_time.stop();
2449   _build_time = build_time.seconds();
2450   _build_iterations = iterations;
2451 
2452   // Bailout if passed limits.
2453   if ((iterations >= GRAPH_BUILD_ITER_LIMIT) || timeout) {
2454     Compile* C = _compile;
2455     if (C->log() != nullptr) {
2456       C->log()->begin_elem("connectionGraph_bailout reason='reached ");
2457       C->log()->text("%s", timeout ? "time" : "iterations");
2458       C->log()->end_elem(" limit'");
2459     }
2460     assert(ExitEscapeAnalysisOnTimeout, "infinite EA connection graph build during invocation %d (%f sec, %d iterations) with %d nodes and worklist size %d",
2461            _invocation, _build_time, _build_iterations, nodes_size(), ptnodes_worklist.length());
2462     // Possible infinite build_connection_graph loop,
2463     // bailout (no changes to ideal graph were made).
2464     return false;
2465   }
2466 
2467 #undef GRAPH_BUILD_ITER_LIMIT
2468 
2469   // Find fields initialized by null for non-escaping Allocations.
2470   int non_escaped_length = non_escaped_allocs_worklist.length();
2471   for (int next = 0; next < non_escaped_length; next++) {
2472     JavaObjectNode* ptn = non_escaped_allocs_worklist.at(next);
2473     PointsToNode::EscapeState es = ptn->escape_state();
2474     assert(es <= PointsToNode::ArgEscape, "sanity");
2475     if (es == PointsToNode::NoEscape) {
2476       if (find_init_values_null(ptn, _igvn) > 0) {
2477         // Adding references to null object does not change escape states
2478         // since it does not escape. Also no fields are added to null object.
2479         add_java_object_edges(null_obj, false);
2480       }
2481     }
2482     Node* n = ptn->ideal_node();
2483     if (n->is_Allocate()) {
2484       // The object allocated by this Allocate node will never be
2485       // seen by an other thread. Mark it so that when it is
2486       // expanded no MemBarStoreStore is added.
2487       InitializeNode* ini = n->as_Allocate()->initialization();
2488       if (ini != nullptr)
2489         ini->set_does_not_escape();
2490     }
2491   }
2492   return true; // Finished graph construction.
2493 }
2494 
2495 // Propagate GlobalEscape and ArgEscape escape states to all nodes
2496 // and check that we still have non-escaping java objects.
2497 bool ConnectionGraph::find_non_escaped_objects(GrowableArray<PointsToNode*>& ptnodes_worklist,
2498                                                GrowableArray<JavaObjectNode*>& non_escaped_allocs_worklist) {
2499   GrowableArray<PointsToNode*> escape_worklist;
2500   // First, put all nodes with GlobalEscape and ArgEscape states on worklist.
2501   int ptnodes_length = ptnodes_worklist.length();
2502   for (int next = 0; next < ptnodes_length; ++next) {
2503     PointsToNode* ptn = ptnodes_worklist.at(next);
2504     if (ptn->escape_state() >= PointsToNode::ArgEscape ||
2505         ptn->fields_escape_state() >= PointsToNode::ArgEscape) {
2506       escape_worklist.push(ptn);
2507     }
2508   }
2509   // Set escape states to referenced nodes (edges list).
2510   while (escape_worklist.length() > 0) {
2511     PointsToNode* ptn = escape_worklist.pop();
2512     PointsToNode::EscapeState es  = ptn->escape_state();
2513     PointsToNode::EscapeState field_es = ptn->fields_escape_state();
2514     if (ptn->is_Field() && ptn->as_Field()->is_oop() &&
2515         es >= PointsToNode::ArgEscape) {
2516       // GlobalEscape or ArgEscape state of field means it has unknown value.
2517       if (add_edge(ptn, phantom_obj)) {
2518         // New edge was added
2519         add_field_uses_to_worklist(ptn->as_Field());
2520       }
2521     }
2522     for (EdgeIterator i(ptn); i.has_next(); i.next()) {
2523       PointsToNode* e = i.get();
2524       if (e->is_Arraycopy()) {
2525         assert(ptn->arraycopy_dst(), "sanity");
2526         // Propagate only fields escape state through arraycopy edge.
2527         if (e->fields_escape_state() < field_es) {
2528           set_fields_escape_state(e, field_es NOT_PRODUCT(COMMA trace_propagate_message(ptn)));
2529           escape_worklist.push(e);
2530         }
2531       } else if (es >= field_es) {
2532         // fields_escape_state is also set to 'es' if it is less than 'es'.
2533         if (e->escape_state() < es) {
2534           set_escape_state(e, es NOT_PRODUCT(COMMA trace_propagate_message(ptn)));
2535           escape_worklist.push(e);
2536         }
2537       } else {
2538         // Propagate field escape state.
2539         bool es_changed = false;
2540         if (e->fields_escape_state() < field_es) {
2541           set_fields_escape_state(e, field_es NOT_PRODUCT(COMMA trace_propagate_message(ptn)));
2542           es_changed = true;
2543         }
2544         if ((e->escape_state() < field_es) &&
2545             e->is_Field() && ptn->is_JavaObject() &&
2546             e->as_Field()->is_oop()) {
2547           // Change escape state of referenced fields.
2548           set_escape_state(e, field_es NOT_PRODUCT(COMMA trace_propagate_message(ptn)));
2549           es_changed = true;
2550         } else if (e->escape_state() < es) {
2551           set_escape_state(e, es NOT_PRODUCT(COMMA trace_propagate_message(ptn)));
2552           es_changed = true;
2553         }
2554         if (es_changed) {
2555           escape_worklist.push(e);
2556         }
2557       }
2558     }
2559   }
2560   // Remove escaped objects from non_escaped list.
2561   for (int next = non_escaped_allocs_worklist.length()-1; next >= 0 ; --next) {
2562     JavaObjectNode* ptn = non_escaped_allocs_worklist.at(next);
2563     if (ptn->escape_state() >= PointsToNode::GlobalEscape) {
2564       non_escaped_allocs_worklist.delete_at(next);
2565     }
2566     if (ptn->escape_state() == PointsToNode::NoEscape) {
2567       // Find fields in non-escaped allocations which have unknown value.
2568       find_init_values_phantom(ptn);
2569     }
2570   }
2571   return (non_escaped_allocs_worklist.length() > 0);
2572 }
2573 
2574 // Add all references to JavaObject node by walking over all uses.
2575 int ConnectionGraph::add_java_object_edges(JavaObjectNode* jobj, bool populate_worklist) {
2576   int new_edges = 0;
2577   if (populate_worklist) {
2578     // Populate _worklist by uses of jobj's uses.
2579     for (UseIterator i(jobj); i.has_next(); i.next()) {
2580       PointsToNode* use = i.get();
2581       if (use->is_Arraycopy()) {
2582         continue;
2583       }
2584       add_uses_to_worklist(use);
2585       if (use->is_Field() && use->as_Field()->is_oop()) {
2586         // Put on worklist all field's uses (loads) and
2587         // related field nodes (same base and offset).
2588         add_field_uses_to_worklist(use->as_Field());
2589       }
2590     }
2591   }
2592   for (int l = 0; l < _worklist.length(); l++) {
2593     PointsToNode* use = _worklist.at(l);
2594     if (PointsToNode::is_base_use(use)) {
2595       // Add reference from jobj to field and from field to jobj (field's base).
2596       use = PointsToNode::get_use_node(use)->as_Field();
2597       if (add_base(use->as_Field(), jobj)) {
2598         new_edges++;
2599       }
2600       continue;
2601     }
2602     assert(!use->is_JavaObject(), "sanity");
2603     if (use->is_Arraycopy()) {
2604       if (jobj == null_obj) { // null object does not have field edges
2605         continue;
2606       }
2607       // Added edge from Arraycopy node to arraycopy's source java object
2608       if (add_edge(use, jobj)) {
2609         jobj->set_arraycopy_src();
2610         new_edges++;
2611       }
2612       // and stop here.
2613       continue;
2614     }
2615     if (!add_edge(use, jobj)) {
2616       continue; // No new edge added, there was such edge already.
2617     }
2618     new_edges++;
2619     if (use->is_LocalVar()) {
2620       add_uses_to_worklist(use);
2621       if (use->arraycopy_dst()) {
2622         for (EdgeIterator i(use); i.has_next(); i.next()) {
2623           PointsToNode* e = i.get();
2624           if (e->is_Arraycopy()) {
2625             if (jobj == null_obj) { // null object does not have field edges
2626               continue;
2627             }
2628             // Add edge from arraycopy's destination java object to Arraycopy node.
2629             if (add_edge(jobj, e)) {
2630               new_edges++;
2631               jobj->set_arraycopy_dst();
2632             }
2633           }
2634         }
2635       }
2636     } else {
2637       // Added new edge to stored in field values.
2638       // Put on worklist all field's uses (loads) and
2639       // related field nodes (same base and offset).
2640       add_field_uses_to_worklist(use->as_Field());
2641     }
2642   }
2643   _worklist.clear();
2644   _in_worklist.reset();
2645   return new_edges;
2646 }
2647 
2648 // Put on worklist all related field nodes.
2649 void ConnectionGraph::add_field_uses_to_worklist(FieldNode* field) {
2650   assert(field->is_oop(), "sanity");
2651   int offset = field->offset();
2652   add_uses_to_worklist(field);
2653   // Loop over all bases of this field and push on worklist Field nodes
2654   // with the same offset and base (since they may reference the same field).
2655   for (BaseIterator i(field); i.has_next(); i.next()) {
2656     PointsToNode* base = i.get();
2657     add_fields_to_worklist(field, base);
2658     // Check if the base was source object of arraycopy and go over arraycopy's
2659     // destination objects since values stored to a field of source object are
2660     // accessible by uses (loads) of fields of destination objects.
2661     if (base->arraycopy_src()) {
2662       for (UseIterator j(base); j.has_next(); j.next()) {
2663         PointsToNode* arycp = j.get();
2664         if (arycp->is_Arraycopy()) {
2665           for (UseIterator k(arycp); k.has_next(); k.next()) {
2666             PointsToNode* abase = k.get();
2667             if (abase->arraycopy_dst() && abase != base) {
2668               // Look for the same arraycopy reference.
2669               add_fields_to_worklist(field, abase);
2670             }
2671           }
2672         }
2673       }
2674     }
2675   }
2676 }
2677 
2678 // Put on worklist all related field nodes.
2679 void ConnectionGraph::add_fields_to_worklist(FieldNode* field, PointsToNode* base) {
2680   int offset = field->offset();
2681   if (base->is_LocalVar()) {
2682     for (UseIterator j(base); j.has_next(); j.next()) {
2683       PointsToNode* f = j.get();
2684       if (PointsToNode::is_base_use(f)) { // Field
2685         f = PointsToNode::get_use_node(f);
2686         if (f == field || !f->as_Field()->is_oop()) {
2687           continue;
2688         }
2689         int offs = f->as_Field()->offset();
2690         if (offs == offset || offset == Type::OffsetBot || offs == Type::OffsetBot) {
2691           add_to_worklist(f);
2692         }
2693       }
2694     }
2695   } else {
2696     assert(base->is_JavaObject(), "sanity");
2697     if (// Skip phantom_object since it is only used to indicate that
2698         // this field's content globally escapes.
2699         (base != phantom_obj) &&
2700         // null object node does not have fields.
2701         (base != null_obj)) {
2702       for (EdgeIterator i(base); i.has_next(); i.next()) {
2703         PointsToNode* f = i.get();
2704         // Skip arraycopy edge since store to destination object field
2705         // does not update value in source object field.
2706         if (f->is_Arraycopy()) {
2707           assert(base->arraycopy_dst(), "sanity");
2708           continue;
2709         }
2710         if (f == field || !f->as_Field()->is_oop()) {
2711           continue;
2712         }
2713         int offs = f->as_Field()->offset();
2714         if (offs == offset || offset == Type::OffsetBot || offs == Type::OffsetBot) {
2715           add_to_worklist(f);
2716         }
2717       }
2718     }
2719   }
2720 }
2721 
2722 // Find fields which have unknown value.
2723 int ConnectionGraph::find_field_value(FieldNode* field) {
2724   // Escaped fields should have init value already.
2725   assert(field->escape_state() == PointsToNode::NoEscape, "sanity");
2726   int new_edges = 0;
2727   for (BaseIterator i(field); i.has_next(); i.next()) {
2728     PointsToNode* base = i.get();
2729     if (base->is_JavaObject()) {
2730       // Skip Allocate's fields which will be processed later.
2731       if (base->ideal_node()->is_Allocate()) {
2732         return 0;
2733       }
2734       assert(base == null_obj, "only null ptr base expected here");
2735     }
2736   }
2737   if (add_edge(field, phantom_obj)) {
2738     // New edge was added
2739     new_edges++;
2740     add_field_uses_to_worklist(field);
2741   }
2742   return new_edges;
2743 }
2744 
2745 // Find fields initializing values for allocations.
2746 int ConnectionGraph::find_init_values_phantom(JavaObjectNode* pta) {
2747   assert(pta->escape_state() == PointsToNode::NoEscape, "Not escaped Allocate nodes only");
2748   Node* alloc = pta->ideal_node();
2749 
2750   // Do nothing for Allocate nodes since its fields values are
2751   // "known" unless they are initialized by arraycopy/clone.
2752   if (alloc->is_Allocate() && !pta->arraycopy_dst()) {
2753     return 0;
2754   }
2755   assert(pta->arraycopy_dst() || alloc->as_CallStaticJava(), "sanity");
2756 #ifdef ASSERT
2757   if (!pta->arraycopy_dst() && alloc->as_CallStaticJava()->method() == nullptr) {
2758     const char* name = alloc->as_CallStaticJava()->_name;
2759     assert(strncmp(name, "C2 Runtime multianewarray", 25) == 0, "sanity");
2760   }
2761 #endif
2762   // Non-escaped allocation returned from Java or runtime call have unknown values in fields.
2763   int new_edges = 0;
2764   for (EdgeIterator i(pta); i.has_next(); i.next()) {
2765     PointsToNode* field = i.get();
2766     if (field->is_Field() && field->as_Field()->is_oop()) {
2767       if (add_edge(field, phantom_obj)) {
2768         // New edge was added
2769         new_edges++;
2770         add_field_uses_to_worklist(field->as_Field());
2771       }
2772     }
2773   }
2774   return new_edges;
2775 }
2776 
2777 // Find fields initializing values for allocations.
2778 int ConnectionGraph::find_init_values_null(JavaObjectNode* pta, PhaseValues* phase) {
2779   assert(pta->escape_state() == PointsToNode::NoEscape, "Not escaped Allocate nodes only");
2780   Node* alloc = pta->ideal_node();
2781   // Do nothing for Call nodes since its fields values are unknown.
2782   if (!alloc->is_Allocate()) {
2783     return 0;
2784   }
2785   InitializeNode* ini = alloc->as_Allocate()->initialization();
2786   bool visited_bottom_offset = false;
2787   GrowableArray<int> offsets_worklist;
2788   int new_edges = 0;
2789 
2790   // Check if an oop field's initializing value is recorded and add
2791   // a corresponding null if field's value if it is not recorded.
2792   // Connection Graph does not record a default initialization by null
2793   // captured by Initialize node.
2794   //
2795   for (EdgeIterator i(pta); i.has_next(); i.next()) {
2796     PointsToNode* field = i.get(); // Field (AddP)
2797     if (!field->is_Field() || !field->as_Field()->is_oop()) {
2798       continue; // Not oop field
2799     }
2800     int offset = field->as_Field()->offset();
2801     if (offset == Type::OffsetBot) {
2802       if (!visited_bottom_offset) {
2803         // OffsetBot is used to reference array's element,
2804         // always add reference to null to all Field nodes since we don't
2805         // known which element is referenced.
2806         if (add_edge(field, null_obj)) {
2807           // New edge was added
2808           new_edges++;
2809           add_field_uses_to_worklist(field->as_Field());
2810           visited_bottom_offset = true;
2811         }
2812       }
2813     } else {
2814       // Check only oop fields.
2815       const Type* adr_type = field->ideal_node()->as_AddP()->bottom_type();
2816       if (adr_type->isa_rawptr()) {
2817 #ifdef ASSERT
2818         // Raw pointers are used for initializing stores so skip it
2819         // since it should be recorded already
2820         Node* base = get_addp_base(field->ideal_node());
2821         assert(adr_type->isa_rawptr() && is_captured_store_address(field->ideal_node()), "unexpected pointer type");
2822 #endif
2823         continue;
2824       }
2825       if (!offsets_worklist.contains(offset)) {
2826         offsets_worklist.append(offset);
2827         Node* value = nullptr;
2828         if (ini != nullptr) {
2829           // StoreP::value_basic_type() == T_ADDRESS
2830           BasicType ft = UseCompressedOops ? T_NARROWOOP : T_ADDRESS;
2831           Node* store = ini->find_captured_store(offset, type2aelembytes(ft, true), phase);
2832           // Make sure initializing store has the same type as this AddP.
2833           // This AddP may reference non existing field because it is on a
2834           // dead branch of bimorphic call which is not eliminated yet.
2835           if (store != nullptr && store->is_Store() &&
2836               store->as_Store()->value_basic_type() == ft) {
2837             value = store->in(MemNode::ValueIn);
2838 #ifdef ASSERT
2839             if (VerifyConnectionGraph) {
2840               // Verify that AddP already points to all objects the value points to.
2841               PointsToNode* val = ptnode_adr(value->_idx);
2842               assert((val != nullptr), "should be processed already");
2843               PointsToNode* missed_obj = nullptr;
2844               if (val->is_JavaObject()) {
2845                 if (!field->points_to(val->as_JavaObject())) {
2846                   missed_obj = val;
2847                 }
2848               } else {
2849                 if (!val->is_LocalVar() || (val->edge_count() == 0)) {
2850                   tty->print_cr("----------init store has invalid value -----");
2851                   store->dump();
2852                   val->dump();
2853                   assert(val->is_LocalVar() && (val->edge_count() > 0), "should be processed already");
2854                 }
2855                 for (EdgeIterator j(val); j.has_next(); j.next()) {
2856                   PointsToNode* obj = j.get();
2857                   if (obj->is_JavaObject()) {
2858                     if (!field->points_to(obj->as_JavaObject())) {
2859                       missed_obj = obj;
2860                       break;
2861                     }
2862                   }
2863                 }
2864               }
2865               if (missed_obj != nullptr) {
2866                 tty->print_cr("----------field---------------------------------");
2867                 field->dump();
2868                 tty->print_cr("----------missed referernce to object-----------");
2869                 missed_obj->dump();
2870                 tty->print_cr("----------object referernced by init store -----");
2871                 store->dump();
2872                 val->dump();
2873                 assert(!field->points_to(missed_obj->as_JavaObject()), "missed JavaObject reference");
2874               }
2875             }
2876 #endif
2877           } else {
2878             // There could be initializing stores which follow allocation.
2879             // For example, a volatile field store is not collected
2880             // by Initialize node.
2881             //
2882             // Need to check for dependent loads to separate such stores from
2883             // stores which follow loads. For now, add initial value null so
2884             // that compare pointers optimization works correctly.
2885           }
2886         }
2887         if (value == nullptr) {
2888           // A field's initializing value was not recorded. Add null.
2889           if (add_edge(field, null_obj)) {
2890             // New edge was added
2891             new_edges++;
2892             add_field_uses_to_worklist(field->as_Field());
2893           }
2894         }
2895       }
2896     }
2897   }
2898   return new_edges;
2899 }
2900 
2901 // Adjust scalar_replaceable state after Connection Graph is built.
2902 void ConnectionGraph::adjust_scalar_replaceable_state(JavaObjectNode* jobj, Unique_Node_List &reducible_merges) {
2903   // A Phi 'x' is a _candidate_ to be reducible if 'can_reduce_phi(x)'
2904   // returns true. If one of the constraints in this method set 'jobj' to NSR
2905   // then the candidate Phi is discarded. If the Phi has another SR 'jobj' as
2906   // input, 'adjust_scalar_replaceable_state' will eventually be called with
2907   // that other object and the Phi will become a reducible Phi.
2908   // There could be multiple merges involving the same jobj.
2909   Unique_Node_List candidates;
2910 
2911   // Search for non-escaping objects which are not scalar replaceable
2912   // and mark them to propagate the state to referenced objects.
2913 
2914   for (UseIterator i(jobj); i.has_next(); i.next()) {
2915     PointsToNode* use = i.get();
2916     if (use->is_Arraycopy()) {
2917       continue;
2918     }
2919     if (use->is_Field()) {
2920       FieldNode* field = use->as_Field();
2921       assert(field->is_oop() && field->scalar_replaceable(), "sanity");
2922       // 1. An object is not scalar replaceable if the field into which it is
2923       // stored has unknown offset (stored into unknown element of an array).
2924       if (field->offset() == Type::OffsetBot) {
2925         set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "is stored at unknown offset"));
2926         return;
2927       }
2928       for (BaseIterator i(field); i.has_next(); i.next()) {
2929         PointsToNode* base = i.get();
2930         // 2. An object is not scalar replaceable if the field into which it is
2931         // stored has multiple bases one of which is null.
2932         if ((base == null_obj) && (field->base_count() > 1)) {
2933           set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "is stored into field with potentially null base"));
2934           return;
2935         }
2936         // 2.5. An object is not scalar replaceable if the field into which it is
2937         // stored has NSR base.
2938         if (!base->scalar_replaceable()) {
2939           set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "is stored into field with NSR base"));
2940           return;
2941         }
2942       }
2943     }
2944     assert(use->is_Field() || use->is_LocalVar(), "sanity");
2945     // 3. An object is not scalar replaceable if it is merged with other objects
2946     // and we can't remove the merge
2947     for (EdgeIterator j(use); j.has_next(); j.next()) {
2948       PointsToNode* ptn = j.get();
2949       if (ptn->is_JavaObject() && ptn != jobj) {
2950         Node* use_n = use->ideal_node();
2951 
2952         // These other local vars may point to multiple objects through a Phi
2953         // In this case we skip them and see if we can reduce the Phi.
2954         if (use_n->is_CastPP() || use_n->is_CheckCastPP()) {
2955           use_n = use_n->in(1);
2956         }
2957 
2958         // If it's already a candidate or confirmed reducible merge we can skip verification
2959         if (candidates.member(use_n) || reducible_merges.member(use_n)) {
2960           continue;
2961         }
2962 
2963         if (use_n->is_Phi() && can_reduce_phi(use_n->as_Phi())) {
2964           candidates.push(use_n);
2965         } else {
2966           // Mark all objects as NSR if we can't remove the merge
2967           set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA trace_merged_message(ptn)));
2968           set_not_scalar_replaceable(ptn NOT_PRODUCT(COMMA trace_merged_message(jobj)));
2969         }
2970       }
2971     }
2972     if (!jobj->scalar_replaceable()) {
2973       return;
2974     }
2975   }
2976 
2977   for (EdgeIterator j(jobj); j.has_next(); j.next()) {
2978     if (j.get()->is_Arraycopy()) {
2979       continue;
2980     }
2981 
2982     // Non-escaping object node should point only to field nodes.
2983     FieldNode* field = j.get()->as_Field();
2984     int offset = field->as_Field()->offset();
2985 
2986     // 4. An object is not scalar replaceable if it has a field with unknown
2987     // offset (array's element is accessed in loop).
2988     if (offset == Type::OffsetBot) {
2989       set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "has field with unknown offset"));
2990       return;
2991     }
2992     // 5. Currently an object is not scalar replaceable if a LoadStore node
2993     // access its field since the field value is unknown after it.
2994     //
2995     Node* n = field->ideal_node();
2996 
2997     // Test for an unsafe access that was parsed as maybe off heap
2998     // (with a CheckCastPP to raw memory).
2999     assert(n->is_AddP(), "expect an address computation");
3000     if (n->in(AddPNode::Base)->is_top() &&
3001         n->in(AddPNode::Address)->Opcode() == Op_CheckCastPP) {
3002       assert(n->in(AddPNode::Address)->bottom_type()->isa_rawptr(), "raw address so raw cast expected");
3003       assert(_igvn->type(n->in(AddPNode::Address)->in(1))->isa_oopptr(), "cast pattern at unsafe access expected");
3004       set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "is used as base of mixed unsafe access"));
3005       return;
3006     }
3007 
3008     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3009       Node* u = n->fast_out(i);
3010       if (u->is_LoadStore() || (u->is_Mem() && u->as_Mem()->is_mismatched_access())) {
3011         set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "is used in LoadStore or mismatched access"));
3012         return;
3013       }
3014     }
3015 
3016     // 6. Or the address may point to more then one object. This may produce
3017     // the false positive result (set not scalar replaceable)
3018     // since the flow-insensitive escape analysis can't separate
3019     // the case when stores overwrite the field's value from the case
3020     // when stores happened on different control branches.
3021     //
3022     // Note: it will disable scalar replacement in some cases:
3023     //
3024     //    Point p[] = new Point[1];
3025     //    p[0] = new Point(); // Will be not scalar replaced
3026     //
3027     // but it will save us from incorrect optimizations in next cases:
3028     //
3029     //    Point p[] = new Point[1];
3030     //    if ( x ) p[0] = new Point(); // Will be not scalar replaced
3031     //
3032     if (field->base_count() > 1 && candidates.size() == 0) {
3033       if (has_non_reducible_merge(field, reducible_merges)) {
3034         for (BaseIterator i(field); i.has_next(); i.next()) {
3035           PointsToNode* base = i.get();
3036           // Don't take into account LocalVar nodes which
3037           // may point to only one object which should be also
3038           // this field's base by now.
3039           if (base->is_JavaObject() && base != jobj) {
3040             // Mark all bases.
3041             set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "may point to more than one object"));
3042             set_not_scalar_replaceable(base NOT_PRODUCT(COMMA "may point to more than one object"));
3043           }
3044         }
3045 
3046         if (!jobj->scalar_replaceable()) {
3047           return;
3048         }
3049       }
3050     }
3051   }
3052 
3053   // The candidate is truly a reducible merge only if none of the other
3054   // constraints ruled it as NSR. There could be multiple merges involving the
3055   // same jobj.
3056   assert(jobj->scalar_replaceable(), "sanity");
3057   for (uint i = 0; i < candidates.size(); i++ ) {
3058     Node* candidate = candidates.at(i);
3059     reducible_merges.push(candidate);
3060   }
3061 }
3062 
3063 bool ConnectionGraph::has_non_reducible_merge(FieldNode* field, Unique_Node_List& reducible_merges) {
3064   for (BaseIterator i(field); i.has_next(); i.next()) {
3065     Node* base = i.get()->ideal_node();
3066     if (base->is_Phi() && !reducible_merges.member(base)) {
3067       return true;
3068     }
3069   }
3070   return false;
3071 }
3072 
3073 void ConnectionGraph::revisit_reducible_phi_status(JavaObjectNode* jobj, Unique_Node_List& reducible_merges) {
3074   assert(jobj != nullptr && !jobj->scalar_replaceable(), "jobj should be set as NSR before calling this function.");
3075 
3076   // Look for 'phis' that refer to 'jobj' as the last
3077   // remaining scalar replaceable input.
3078   uint reducible_merges_cnt = reducible_merges.size();
3079   for (uint i = 0; i < reducible_merges_cnt; i++) {
3080     Node* phi = reducible_merges.at(i);
3081 
3082     // This 'Phi' will be a 'good' if it still points to
3083     // at least one scalar replaceable object. Note that 'obj'
3084     // was/should be marked as NSR before calling this function.
3085     bool good_phi = false;
3086 
3087     for (uint j = 1; j < phi->req(); j++) {
3088       JavaObjectNode* phi_in_obj = unique_java_object(phi->in(j));
3089       if (phi_in_obj != nullptr && phi_in_obj->scalar_replaceable()) {
3090         good_phi = true;
3091         break;
3092       }
3093     }
3094 
3095     if (!good_phi) {
3096       NOT_PRODUCT(if (TraceReduceAllocationMerges) tty->print_cr("Phi %d became non-reducible after node %d became NSR.", phi->_idx, jobj->ideal_node()->_idx);)
3097       reducible_merges.remove(i);
3098 
3099       // Decrement the index because the 'remove' call above actually
3100       // moves the last entry of the list to position 'i'.
3101       i--;
3102 
3103       reducible_merges_cnt--;
3104     }
3105   }
3106 }
3107 
3108 // Propagate NSR (Not scalar replaceable) state.
3109 void ConnectionGraph::find_scalar_replaceable_allocs(GrowableArray<JavaObjectNode*>& jobj_worklist, Unique_Node_List &reducible_merges) {
3110   int jobj_length = jobj_worklist.length();
3111   bool found_nsr_alloc = true;
3112   while (found_nsr_alloc) {
3113     found_nsr_alloc = false;
3114     for (int next = 0; next < jobj_length; ++next) {
3115       JavaObjectNode* jobj = jobj_worklist.at(next);
3116       for (UseIterator i(jobj); (jobj->scalar_replaceable() && i.has_next()); i.next()) {
3117         PointsToNode* use = i.get();
3118         if (use->is_Field()) {
3119           FieldNode* field = use->as_Field();
3120           assert(field->is_oop() && field->scalar_replaceable(), "sanity");
3121           assert(field->offset() != Type::OffsetBot, "sanity");
3122           for (BaseIterator i(field); i.has_next(); i.next()) {
3123             PointsToNode* base = i.get();
3124             // An object is not scalar replaceable if the field into which
3125             // it is stored has NSR base.
3126             if ((base != null_obj) && !base->scalar_replaceable()) {
3127               set_not_scalar_replaceable(jobj NOT_PRODUCT(COMMA "is stored into field with NSR base"));
3128               // Any merge that had only 'jobj' as scalar-replaceable will now be non-reducible,
3129               // because there is no point in reducing a Phi that won't improve the number of SR
3130               // objects.
3131               revisit_reducible_phi_status(jobj, reducible_merges);
3132               found_nsr_alloc = true;
3133               break;
3134             }
3135           }
3136         }
3137       }
3138     }
3139   }
3140 }
3141 
3142 #ifdef ASSERT
3143 void ConnectionGraph::verify_connection_graph(
3144                          GrowableArray<PointsToNode*>&   ptnodes_worklist,
3145                          GrowableArray<JavaObjectNode*>& non_escaped_allocs_worklist,
3146                          GrowableArray<JavaObjectNode*>& java_objects_worklist,
3147                          GrowableArray<Node*>& addp_worklist) {
3148   // Verify that graph is complete - no new edges could be added.
3149   int java_objects_length = java_objects_worklist.length();
3150   int non_escaped_length  = non_escaped_allocs_worklist.length();
3151   int new_edges = 0;
3152   for (int next = 0; next < java_objects_length; ++next) {
3153     JavaObjectNode* ptn = java_objects_worklist.at(next);
3154     new_edges += add_java_object_edges(ptn, true);
3155   }
3156   assert(new_edges == 0, "graph was not complete");
3157   // Verify that escape state is final.
3158   int length = non_escaped_allocs_worklist.length();
3159   find_non_escaped_objects(ptnodes_worklist, non_escaped_allocs_worklist);
3160   assert((non_escaped_length == non_escaped_allocs_worklist.length()) &&
3161          (non_escaped_length == length) &&
3162          (_worklist.length() == 0), "escape state was not final");
3163 
3164   // Verify fields information.
3165   int addp_length = addp_worklist.length();
3166   for (int next = 0; next < addp_length; ++next ) {
3167     Node* n = addp_worklist.at(next);
3168     FieldNode* field = ptnode_adr(n->_idx)->as_Field();
3169     if (field->is_oop()) {
3170       // Verify that field has all bases
3171       Node* base = get_addp_base(n);
3172       PointsToNode* ptn = ptnode_adr(base->_idx);
3173       if (ptn->is_JavaObject()) {
3174         assert(field->has_base(ptn->as_JavaObject()), "sanity");
3175       } else {
3176         assert(ptn->is_LocalVar(), "sanity");
3177         for (EdgeIterator i(ptn); i.has_next(); i.next()) {
3178           PointsToNode* e = i.get();
3179           if (e->is_JavaObject()) {
3180             assert(field->has_base(e->as_JavaObject()), "sanity");
3181           }
3182         }
3183       }
3184       // Verify that all fields have initializing values.
3185       if (field->edge_count() == 0) {
3186         tty->print_cr("----------field does not have references----------");
3187         field->dump();
3188         for (BaseIterator i(field); i.has_next(); i.next()) {
3189           PointsToNode* base = i.get();
3190           tty->print_cr("----------field has next base---------------------");
3191           base->dump();
3192           if (base->is_JavaObject() && (base != phantom_obj) && (base != null_obj)) {
3193             tty->print_cr("----------base has fields-------------------------");
3194             for (EdgeIterator j(base); j.has_next(); j.next()) {
3195               j.get()->dump();
3196             }
3197             tty->print_cr("----------base has references---------------------");
3198             for (UseIterator j(base); j.has_next(); j.next()) {
3199               j.get()->dump();
3200             }
3201           }
3202         }
3203         for (UseIterator i(field); i.has_next(); i.next()) {
3204           i.get()->dump();
3205         }
3206         assert(field->edge_count() > 0, "sanity");
3207       }
3208     }
3209   }
3210 }
3211 #endif
3212 
3213 // Optimize ideal graph.
3214 void ConnectionGraph::optimize_ideal_graph(GrowableArray<Node*>& ptr_cmp_worklist,
3215                                            GrowableArray<MemBarStoreStoreNode*>& storestore_worklist) {
3216   Compile* C = _compile;
3217   PhaseIterGVN* igvn = _igvn;
3218   if (EliminateLocks) {
3219     // Mark locks before changing ideal graph.
3220     int cnt = C->macro_count();
3221     for (int i = 0; i < cnt; i++) {
3222       Node *n = C->macro_node(i);
3223       if (n->is_AbstractLock()) { // Lock and Unlock nodes
3224         AbstractLockNode* alock = n->as_AbstractLock();
3225         if (!alock->is_non_esc_obj()) {
3226           if (can_eliminate_lock(alock)) {
3227             assert(!alock->is_eliminated() || alock->is_coarsened(), "sanity");
3228             // The lock could be marked eliminated by lock coarsening
3229             // code during first IGVN before EA. Replace coarsened flag
3230             // to eliminate all associated locks/unlocks.
3231 #ifdef ASSERT
3232             alock->log_lock_optimization(C, "eliminate_lock_set_non_esc3");
3233 #endif
3234             alock->set_non_esc_obj();
3235           }
3236         }
3237       }
3238     }
3239   }
3240 
3241   if (OptimizePtrCompare) {
3242     for (int i = 0; i < ptr_cmp_worklist.length(); i++) {
3243       Node *n = ptr_cmp_worklist.at(i);
3244       assert(n->Opcode() == Op_CmpN || n->Opcode() == Op_CmpP, "must be");
3245       const TypeInt* tcmp = optimize_ptr_compare(n->in(1), n->in(2));
3246       if (tcmp->singleton()) {
3247         Node* cmp = igvn->makecon(tcmp);
3248 #ifndef PRODUCT
3249         if (PrintOptimizePtrCompare) {
3250           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, (tcmp == TypeInt::CC_EQ ? "EQ" : "NotEQ"));
3251           if (Verbose) {
3252             n->dump(1);
3253           }
3254         }
3255 #endif
3256         igvn->replace_node(n, cmp);
3257       }
3258     }
3259   }
3260 
3261   // For MemBarStoreStore nodes added in library_call.cpp, check
3262   // escape status of associated AllocateNode and optimize out
3263   // MemBarStoreStore node if the allocated object never escapes.
3264   for (int i = 0; i < storestore_worklist.length(); i++) {
3265     Node* storestore = storestore_worklist.at(i);
3266     Node* alloc = storestore->in(MemBarNode::Precedent)->in(0);
3267     if (alloc->is_Allocate() && not_global_escape(alloc)) {
3268       MemBarNode* mb = MemBarNode::make(C, Op_MemBarCPUOrder, Compile::AliasIdxBot);
3269       mb->init_req(TypeFunc::Memory,  storestore->in(TypeFunc::Memory));
3270       mb->init_req(TypeFunc::Control, storestore->in(TypeFunc::Control));
3271       igvn->register_new_node_with_optimizer(mb);
3272       igvn->replace_node(storestore, mb);
3273     }
3274   }
3275 }
3276 
3277 // Optimize objects compare.
3278 const TypeInt* ConnectionGraph::optimize_ptr_compare(Node* left, Node* right) {
3279   assert(OptimizePtrCompare, "sanity");
3280   const TypeInt* EQ = TypeInt::CC_EQ; // [0] == ZERO
3281   const TypeInt* NE = TypeInt::CC_GT; // [1] == ONE
3282   const TypeInt* UNKNOWN = TypeInt::CC;    // [-1, 0,1]
3283 
3284   PointsToNode* ptn1 = ptnode_adr(left->_idx);
3285   PointsToNode* ptn2 = ptnode_adr(right->_idx);
3286   JavaObjectNode* jobj1 = unique_java_object(left);
3287   JavaObjectNode* jobj2 = unique_java_object(right);
3288 
3289   // The use of this method during allocation merge reduction may cause 'left'
3290   // or 'right' be something (e.g., a Phi) that isn't in the connection graph or
3291   // that doesn't reference an unique java object.
3292   if (ptn1 == nullptr || ptn2 == nullptr ||
3293       jobj1 == nullptr || jobj2 == nullptr) {
3294     return UNKNOWN;
3295   }
3296 
3297   assert(ptn1->is_JavaObject() || ptn1->is_LocalVar(), "sanity");
3298   assert(ptn2->is_JavaObject() || ptn2->is_LocalVar(), "sanity");
3299 
3300   // Check simple cases first.
3301   if (jobj1 != nullptr) {
3302     if (jobj1->escape_state() == PointsToNode::NoEscape) {
3303       if (jobj1 == jobj2) {
3304         // Comparing the same not escaping object.
3305         return EQ;
3306       }
3307       Node* obj = jobj1->ideal_node();
3308       // Comparing not escaping allocation.
3309       if ((obj->is_Allocate() || obj->is_CallStaticJava()) &&
3310           !ptn2->points_to(jobj1)) {
3311         return NE; // This includes nullness check.
3312       }
3313     }
3314   }
3315   if (jobj2 != nullptr) {
3316     if (jobj2->escape_state() == PointsToNode::NoEscape) {
3317       Node* obj = jobj2->ideal_node();
3318       // Comparing not escaping allocation.
3319       if ((obj->is_Allocate() || obj->is_CallStaticJava()) &&
3320           !ptn1->points_to(jobj2)) {
3321         return NE; // This includes nullness check.
3322       }
3323     }
3324   }
3325   if (jobj1 != nullptr && jobj1 != phantom_obj &&
3326       jobj2 != nullptr && jobj2 != phantom_obj &&
3327       jobj1->ideal_node()->is_Con() &&
3328       jobj2->ideal_node()->is_Con()) {
3329     // Klass or String constants compare. Need to be careful with
3330     // compressed pointers - compare types of ConN and ConP instead of nodes.
3331     const Type* t1 = jobj1->ideal_node()->get_ptr_type();
3332     const Type* t2 = jobj2->ideal_node()->get_ptr_type();
3333     if (t1->make_ptr() == t2->make_ptr()) {
3334       return EQ;
3335     } else {
3336       return NE;
3337     }
3338   }
3339   if (ptn1->meet(ptn2)) {
3340     return UNKNOWN; // Sets are not disjoint
3341   }
3342 
3343   // Sets are disjoint.
3344   bool set1_has_unknown_ptr = ptn1->points_to(phantom_obj);
3345   bool set2_has_unknown_ptr = ptn2->points_to(phantom_obj);
3346   bool set1_has_null_ptr    = ptn1->points_to(null_obj);
3347   bool set2_has_null_ptr    = ptn2->points_to(null_obj);
3348   if ((set1_has_unknown_ptr && set2_has_null_ptr) ||
3349       (set2_has_unknown_ptr && set1_has_null_ptr)) {
3350     // Check nullness of unknown object.
3351     return UNKNOWN;
3352   }
3353 
3354   // Disjointness by itself is not sufficient since
3355   // alias analysis is not complete for escaped objects.
3356   // Disjoint sets are definitely unrelated only when
3357   // at least one set has only not escaping allocations.
3358   if (!set1_has_unknown_ptr && !set1_has_null_ptr) {
3359     if (ptn1->non_escaping_allocation()) {
3360       return NE;
3361     }
3362   }
3363   if (!set2_has_unknown_ptr && !set2_has_null_ptr) {
3364     if (ptn2->non_escaping_allocation()) {
3365       return NE;
3366     }
3367   }
3368   return UNKNOWN;
3369 }
3370 
3371 // Connection Graph construction functions.
3372 
3373 void ConnectionGraph::add_local_var(Node *n, PointsToNode::EscapeState es) {
3374   PointsToNode* ptadr = _nodes.at(n->_idx);
3375   if (ptadr != nullptr) {
3376     assert(ptadr->is_LocalVar() && ptadr->ideal_node() == n, "sanity");
3377     return;
3378   }
3379   Compile* C = _compile;
3380   ptadr = new (C->comp_arena()) LocalVarNode(this, n, es);
3381   map_ideal_node(n, ptadr);
3382 }
3383 
3384 PointsToNode* ConnectionGraph::add_java_object(Node *n, PointsToNode::EscapeState es) {
3385   PointsToNode* ptadr = _nodes.at(n->_idx);
3386   if (ptadr != nullptr) {
3387     assert(ptadr->is_JavaObject() && ptadr->ideal_node() == n, "sanity");
3388     return ptadr;
3389   }
3390   Compile* C = _compile;
3391   ptadr = new (C->comp_arena()) JavaObjectNode(this, n, es);
3392   map_ideal_node(n, ptadr);
3393   return ptadr;
3394 }
3395 
3396 void ConnectionGraph::add_field(Node *n, PointsToNode::EscapeState es, int offset) {
3397   PointsToNode* ptadr = _nodes.at(n->_idx);
3398   if (ptadr != nullptr) {
3399     assert(ptadr->is_Field() && ptadr->ideal_node() == n, "sanity");
3400     return;
3401   }
3402   bool unsafe = false;
3403   bool is_oop = is_oop_field(n, offset, &unsafe);
3404   if (unsafe) {
3405     es = PointsToNode::GlobalEscape;
3406   }
3407   Compile* C = _compile;
3408   FieldNode* field = new (C->comp_arena()) FieldNode(this, n, es, offset, is_oop);
3409   map_ideal_node(n, field);
3410 }
3411 
3412 void ConnectionGraph::add_arraycopy(Node *n, PointsToNode::EscapeState es,
3413                                     PointsToNode* src, PointsToNode* dst) {
3414   assert(!src->is_Field() && !dst->is_Field(), "only for JavaObject and LocalVar");
3415   assert((src != null_obj) && (dst != null_obj), "not for ConP null");
3416   PointsToNode* ptadr = _nodes.at(n->_idx);
3417   if (ptadr != nullptr) {
3418     assert(ptadr->is_Arraycopy() && ptadr->ideal_node() == n, "sanity");
3419     return;
3420   }
3421   Compile* C = _compile;
3422   ptadr = new (C->comp_arena()) ArraycopyNode(this, n, es);
3423   map_ideal_node(n, ptadr);
3424   // Add edge from arraycopy node to source object.
3425   (void)add_edge(ptadr, src);
3426   src->set_arraycopy_src();
3427   // Add edge from destination object to arraycopy node.
3428   (void)add_edge(dst, ptadr);
3429   dst->set_arraycopy_dst();
3430 }
3431 
3432 bool ConnectionGraph::is_oop_field(Node* n, int offset, bool* unsafe) {
3433   const Type* adr_type = n->as_AddP()->bottom_type();
3434   BasicType bt = T_INT;
3435   if (offset == Type::OffsetBot) {
3436     // Check only oop fields.
3437     if (!adr_type->isa_aryptr() ||
3438         adr_type->isa_aryptr()->elem() == Type::BOTTOM ||
3439         adr_type->isa_aryptr()->elem()->make_oopptr() != nullptr) {
3440       // OffsetBot is used to reference array's element. Ignore first AddP.
3441       if (find_second_addp(n, n->in(AddPNode::Base)) == nullptr) {
3442         bt = T_OBJECT;
3443       }
3444     }
3445   } else if (offset != Type::klass_offset()) {
3446     if (adr_type->isa_instptr()) {
3447       ciField* field = _compile->alias_type(adr_type->isa_instptr())->field();
3448       if (field != nullptr) {
3449         bt = field->layout_type();
3450       } else {
3451         // Check for unsafe oop field access
3452         if (n->has_out_with(Op_StoreP, Op_LoadP, Op_StoreN, Op_LoadN) ||
3453             n->has_out_with(Op_GetAndSetP, Op_GetAndSetN, Op_CompareAndExchangeP, Op_CompareAndExchangeN) ||
3454             n->has_out_with(Op_CompareAndSwapP, Op_CompareAndSwapN, Op_WeakCompareAndSwapP, Op_WeakCompareAndSwapN) ||
3455             BarrierSet::barrier_set()->barrier_set_c2()->escape_has_out_with_unsafe_object(n)) {
3456           bt = T_OBJECT;
3457           (*unsafe) = true;
3458         }
3459       }
3460     } else if (adr_type->isa_aryptr()) {
3461       if (offset == arrayOopDesc::length_offset_in_bytes()) {
3462         // Ignore array length load.
3463       } else if (find_second_addp(n, n->in(AddPNode::Base)) != nullptr) {
3464         // Ignore first AddP.
3465       } else {
3466         const Type* elemtype = adr_type->isa_aryptr()->elem();
3467         bt = elemtype->array_element_basic_type();
3468       }
3469     } else if (adr_type->isa_rawptr() || adr_type->isa_klassptr()) {
3470       // Allocation initialization, ThreadLocal field access, unsafe access
3471       if (n->has_out_with(Op_StoreP, Op_LoadP, Op_StoreN, Op_LoadN) ||
3472           n->has_out_with(Op_GetAndSetP, Op_GetAndSetN, Op_CompareAndExchangeP, Op_CompareAndExchangeN) ||
3473           n->has_out_with(Op_CompareAndSwapP, Op_CompareAndSwapN, Op_WeakCompareAndSwapP, Op_WeakCompareAndSwapN) ||
3474           BarrierSet::barrier_set()->barrier_set_c2()->escape_has_out_with_unsafe_object(n)) {
3475         bt = T_OBJECT;
3476       }
3477     }
3478   }
3479   // Note: T_NARROWOOP is not classed as a real reference type
3480   return (is_reference_type(bt) || bt == T_NARROWOOP);
3481 }
3482 
3483 // Returns unique pointed java object or null.
3484 JavaObjectNode* ConnectionGraph::unique_java_object(Node *n) const {
3485   // If the node was created after the escape computation we can't answer.
3486   uint idx = n->_idx;
3487   if (idx >= nodes_size()) {
3488     return nullptr;
3489   }
3490   PointsToNode* ptn = ptnode_adr(idx);
3491   if (ptn == nullptr) {
3492     return nullptr;
3493   }
3494   if (ptn->is_JavaObject()) {
3495     return ptn->as_JavaObject();
3496   }
3497   assert(ptn->is_LocalVar(), "sanity");
3498   // Check all java objects it points to.
3499   JavaObjectNode* jobj = nullptr;
3500   for (EdgeIterator i(ptn); i.has_next(); i.next()) {
3501     PointsToNode* e = i.get();
3502     if (e->is_JavaObject()) {
3503       if (jobj == nullptr) {
3504         jobj = e->as_JavaObject();
3505       } else if (jobj != e) {
3506         return nullptr;
3507       }
3508     }
3509   }
3510   return jobj;
3511 }
3512 
3513 // Return true if this node points only to non-escaping allocations.
3514 bool PointsToNode::non_escaping_allocation() {
3515   if (is_JavaObject()) {
3516     Node* n = ideal_node();
3517     if (n->is_Allocate() || n->is_CallStaticJava()) {
3518       return (escape_state() == PointsToNode::NoEscape);
3519     } else {
3520       return false;
3521     }
3522   }
3523   assert(is_LocalVar(), "sanity");
3524   // Check all java objects it points to.
3525   for (EdgeIterator i(this); i.has_next(); i.next()) {
3526     PointsToNode* e = i.get();
3527     if (e->is_JavaObject()) {
3528       Node* n = e->ideal_node();
3529       if ((e->escape_state() != PointsToNode::NoEscape) ||
3530           !(n->is_Allocate() || n->is_CallStaticJava())) {
3531         return false;
3532       }
3533     }
3534   }
3535   return true;
3536 }
3537 
3538 // Return true if we know the node does not escape globally.
3539 bool ConnectionGraph::not_global_escape(Node *n) {
3540   assert(!_collecting, "should not call during graph construction");
3541   // If the node was created after the escape computation we can't answer.
3542   uint idx = n->_idx;
3543   if (idx >= nodes_size()) {
3544     return false;
3545   }
3546   PointsToNode* ptn = ptnode_adr(idx);
3547   if (ptn == nullptr) {
3548     return false; // not in congraph (e.g. ConI)
3549   }
3550   PointsToNode::EscapeState es = ptn->escape_state();
3551   // If we have already computed a value, return it.
3552   if (es >= PointsToNode::GlobalEscape) {
3553     return false;
3554   }
3555   if (ptn->is_JavaObject()) {
3556     return true; // (es < PointsToNode::GlobalEscape);
3557   }
3558   assert(ptn->is_LocalVar(), "sanity");
3559   // Check all java objects it points to.
3560   for (EdgeIterator i(ptn); i.has_next(); i.next()) {
3561     if (i.get()->escape_state() >= PointsToNode::GlobalEscape) {
3562       return false;
3563     }
3564   }
3565   return true;
3566 }
3567 
3568 // Return true if locked object does not escape globally
3569 // and locked code region (identified by BoxLockNode) is balanced:
3570 // all compiled code paths have corresponding Lock/Unlock pairs.
3571 bool ConnectionGraph::can_eliminate_lock(AbstractLockNode* alock) {
3572   if (alock->is_balanced() && not_global_escape(alock->obj_node())) {
3573     if (EliminateNestedLocks) {
3574       // We can mark whole locking region as Local only when only
3575       // one object is used for locking.
3576       alock->box_node()->as_BoxLock()->set_local();
3577     }
3578     return true;
3579   }
3580   return false;
3581 }
3582 
3583 // Helper functions
3584 
3585 // Return true if this node points to specified node or nodes it points to.
3586 bool PointsToNode::points_to(JavaObjectNode* ptn) const {
3587   if (is_JavaObject()) {
3588     return (this == ptn);
3589   }
3590   assert(is_LocalVar() || is_Field(), "sanity");
3591   for (EdgeIterator i(this); i.has_next(); i.next()) {
3592     if (i.get() == ptn) {
3593       return true;
3594     }
3595   }
3596   return false;
3597 }
3598 
3599 // Return true if one node points to an other.
3600 bool PointsToNode::meet(PointsToNode* ptn) {
3601   if (this == ptn) {
3602     return true;
3603   } else if (ptn->is_JavaObject()) {
3604     return this->points_to(ptn->as_JavaObject());
3605   } else if (this->is_JavaObject()) {
3606     return ptn->points_to(this->as_JavaObject());
3607   }
3608   assert(this->is_LocalVar() && ptn->is_LocalVar(), "sanity");
3609   int ptn_count =  ptn->edge_count();
3610   for (EdgeIterator i(this); i.has_next(); i.next()) {
3611     PointsToNode* this_e = i.get();
3612     for (int j = 0; j < ptn_count; j++) {
3613       if (this_e == ptn->edge(j)) {
3614         return true;
3615       }
3616     }
3617   }
3618   return false;
3619 }
3620 
3621 #ifdef ASSERT
3622 // Return true if bases point to this java object.
3623 bool FieldNode::has_base(JavaObjectNode* jobj) const {
3624   for (BaseIterator i(this); i.has_next(); i.next()) {
3625     if (i.get() == jobj) {
3626       return true;
3627     }
3628   }
3629   return false;
3630 }
3631 #endif
3632 
3633 bool ConnectionGraph::is_captured_store_address(Node* addp) {
3634   // Handle simple case first.
3635   assert(_igvn->type(addp)->isa_oopptr() == nullptr, "should be raw access");
3636   if (addp->in(AddPNode::Address)->is_Proj() && addp->in(AddPNode::Address)->in(0)->is_Allocate()) {
3637     return true;
3638   } else if (addp->in(AddPNode::Address)->is_Phi()) {
3639     for (DUIterator_Fast imax, i = addp->fast_outs(imax); i < imax; i++) {
3640       Node* addp_use = addp->fast_out(i);
3641       if (addp_use->is_Store()) {
3642         for (DUIterator_Fast jmax, j = addp_use->fast_outs(jmax); j < jmax; j++) {
3643           if (addp_use->fast_out(j)->is_Initialize()) {
3644             return true;
3645           }
3646         }
3647       }
3648     }
3649   }
3650   return false;
3651 }
3652 
3653 int ConnectionGraph::address_offset(Node* adr, PhaseValues* phase) {
3654   const Type *adr_type = phase->type(adr);
3655   if (adr->is_AddP() && adr_type->isa_oopptr() == nullptr && is_captured_store_address(adr)) {
3656     // We are computing a raw address for a store captured by an Initialize
3657     // compute an appropriate address type. AddP cases #3 and #5 (see below).
3658     int offs = (int)phase->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
3659     assert(offs != Type::OffsetBot ||
3660            adr->in(AddPNode::Address)->in(0)->is_AllocateArray(),
3661            "offset must be a constant or it is initialization of array");
3662     return offs;
3663   }
3664   const TypePtr *t_ptr = adr_type->isa_ptr();
3665   assert(t_ptr != nullptr, "must be a pointer type");
3666   return t_ptr->offset();
3667 }
3668 
3669 Node* ConnectionGraph::get_addp_base(Node *addp) {
3670   assert(addp->is_AddP(), "must be AddP");
3671   //
3672   // AddP cases for Base and Address inputs:
3673   // case #1. Direct object's field reference:
3674   //     Allocate
3675   //       |
3676   //     Proj #5 ( oop result )
3677   //       |
3678   //     CheckCastPP (cast to instance type)
3679   //      | |
3680   //     AddP  ( base == address )
3681   //
3682   // case #2. Indirect object's field reference:
3683   //      Phi
3684   //       |
3685   //     CastPP (cast to instance type)
3686   //      | |
3687   //     AddP  ( base == address )
3688   //
3689   // case #3. Raw object's field reference for Initialize node:
3690   //      Allocate
3691   //        |
3692   //      Proj #5 ( oop result )
3693   //  top   |
3694   //     \  |
3695   //     AddP  ( base == top )
3696   //
3697   // case #4. Array's element reference:
3698   //   {CheckCastPP | CastPP}
3699   //     |  | |
3700   //     |  AddP ( array's element offset )
3701   //     |  |
3702   //     AddP ( array's offset )
3703   //
3704   // case #5. Raw object's field reference for arraycopy stub call:
3705   //          The inline_native_clone() case when the arraycopy stub is called
3706   //          after the allocation before Initialize and CheckCastPP nodes.
3707   //      Allocate
3708   //        |
3709   //      Proj #5 ( oop result )
3710   //       | |
3711   //       AddP  ( base == address )
3712   //
3713   // case #6. Constant Pool, ThreadLocal, CastX2P or
3714   //          Raw object's field reference:
3715   //      {ConP, ThreadLocal, CastX2P, raw Load}
3716   //  top   |
3717   //     \  |
3718   //     AddP  ( base == top )
3719   //
3720   // case #7. Klass's field reference.
3721   //      LoadKlass
3722   //       | |
3723   //       AddP  ( base == address )
3724   //
3725   // case #8. narrow Klass's field reference.
3726   //      LoadNKlass
3727   //       |
3728   //      DecodeN
3729   //       | |
3730   //       AddP  ( base == address )
3731   //
3732   // case #9. Mixed unsafe access
3733   //    {instance}
3734   //        |
3735   //      CheckCastPP (raw)
3736   //  top   |
3737   //     \  |
3738   //     AddP  ( base == top )
3739   //
3740   Node *base = addp->in(AddPNode::Base);
3741   if (base->uncast()->is_top()) { // The AddP case #3 and #6 and #9.
3742     base = addp->in(AddPNode::Address);
3743     while (base->is_AddP()) {
3744       // Case #6 (unsafe access) may have several chained AddP nodes.
3745       assert(base->in(AddPNode::Base)->uncast()->is_top(), "expected unsafe access address only");
3746       base = base->in(AddPNode::Address);
3747     }
3748     if (base->Opcode() == Op_CheckCastPP &&
3749         base->bottom_type()->isa_rawptr() &&
3750         _igvn->type(base->in(1))->isa_oopptr()) {
3751       base = base->in(1); // Case #9
3752     } else {
3753       Node* uncast_base = base->uncast();
3754       int opcode = uncast_base->Opcode();
3755       assert(opcode == Op_ConP || opcode == Op_ThreadLocal ||
3756              opcode == Op_CastX2P || uncast_base->is_DecodeNarrowPtr() ||
3757              (uncast_base->is_Mem() && (uncast_base->bottom_type()->isa_rawptr() != nullptr)) ||
3758              is_captured_store_address(addp), "sanity");
3759     }
3760   }
3761   return base;
3762 }
3763 
3764 Node* ConnectionGraph::find_second_addp(Node* addp, Node* n) {
3765   assert(addp->is_AddP() && addp->outcnt() > 0, "Don't process dead nodes");
3766   Node* addp2 = addp->raw_out(0);
3767   if (addp->outcnt() == 1 && addp2->is_AddP() &&
3768       addp2->in(AddPNode::Base) == n &&
3769       addp2->in(AddPNode::Address) == addp) {
3770     assert(addp->in(AddPNode::Base) == n, "expecting the same base");
3771     //
3772     // Find array's offset to push it on worklist first and
3773     // as result process an array's element offset first (pushed second)
3774     // to avoid CastPP for the array's offset.
3775     // Otherwise the inserted CastPP (LocalVar) will point to what
3776     // the AddP (Field) points to. Which would be wrong since
3777     // the algorithm expects the CastPP has the same point as
3778     // as AddP's base CheckCastPP (LocalVar).
3779     //
3780     //    ArrayAllocation
3781     //     |
3782     //    CheckCastPP
3783     //     |
3784     //    memProj (from ArrayAllocation CheckCastPP)
3785     //     |  ||
3786     //     |  ||   Int (element index)
3787     //     |  ||    |   ConI (log(element size))
3788     //     |  ||    |   /
3789     //     |  ||   LShift
3790     //     |  ||  /
3791     //     |  AddP (array's element offset)
3792     //     |  |
3793     //     |  | ConI (array's offset: #12(32-bits) or #24(64-bits))
3794     //     | / /
3795     //     AddP (array's offset)
3796     //      |
3797     //     Load/Store (memory operation on array's element)
3798     //
3799     return addp2;
3800   }
3801   return nullptr;
3802 }
3803 
3804 //
3805 // Adjust the type and inputs of an AddP which computes the
3806 // address of a field of an instance
3807 //
3808 bool ConnectionGraph::split_AddP(Node *addp, Node *base) {
3809   PhaseGVN* igvn = _igvn;
3810   const TypeOopPtr *base_t = igvn->type(base)->isa_oopptr();
3811   assert(base_t != nullptr && base_t->is_known_instance(), "expecting instance oopptr");
3812   const TypeOopPtr *t = igvn->type(addp)->isa_oopptr();
3813   if (t == nullptr) {
3814     // We are computing a raw address for a store captured by an Initialize
3815     // compute an appropriate address type (cases #3 and #5).
3816     assert(igvn->type(addp) == TypeRawPtr::NOTNULL, "must be raw pointer");
3817     assert(addp->in(AddPNode::Address)->is_Proj(), "base of raw address must be result projection from allocation");
3818     intptr_t offs = (int)igvn->find_intptr_t_con(addp->in(AddPNode::Offset), Type::OffsetBot);
3819     assert(offs != Type::OffsetBot, "offset must be a constant");
3820     t = base_t->add_offset(offs)->is_oopptr();
3821   }
3822   int inst_id =  base_t->instance_id();
3823   assert(!t->is_known_instance() || t->instance_id() == inst_id,
3824                              "old type must be non-instance or match new type");
3825 
3826   // The type 't' could be subclass of 'base_t'.
3827   // As result t->offset() could be large then base_t's size and it will
3828   // cause the failure in add_offset() with narrow oops since TypeOopPtr()
3829   // constructor verifies correctness of the offset.
3830   //
3831   // It could happened on subclass's branch (from the type profiling
3832   // inlining) which was not eliminated during parsing since the exactness
3833   // of the allocation type was not propagated to the subclass type check.
3834   //
3835   // Or the type 't' could be not related to 'base_t' at all.
3836   // It could happened when CHA type is different from MDO type on a dead path
3837   // (for example, from instanceof check) which is not collapsed during parsing.
3838   //
3839   // Do nothing for such AddP node and don't process its users since
3840   // this code branch will go away.
3841   //
3842   if (!t->is_known_instance() &&
3843       !base_t->maybe_java_subtype_of(t)) {
3844      return false; // bail out
3845   }
3846   const TypeOopPtr *tinst = base_t->add_offset(t->offset())->is_oopptr();
3847   // Do NOT remove the next line: ensure a new alias index is allocated
3848   // for the instance type. Note: C++ will not remove it since the call
3849   // has side effect.
3850   int alias_idx = _compile->get_alias_index(tinst);
3851   igvn->set_type(addp, tinst);
3852   // record the allocation in the node map
3853   set_map(addp, get_map(base->_idx));
3854   // Set addp's Base and Address to 'base'.
3855   Node *abase = addp->in(AddPNode::Base);
3856   Node *adr   = addp->in(AddPNode::Address);
3857   if (adr->is_Proj() && adr->in(0)->is_Allocate() &&
3858       adr->in(0)->_idx == (uint)inst_id) {
3859     // Skip AddP cases #3 and #5.
3860   } else {
3861     assert(!abase->is_top(), "sanity"); // AddP case #3
3862     if (abase != base) {
3863       igvn->hash_delete(addp);
3864       addp->set_req(AddPNode::Base, base);
3865       if (abase == adr) {
3866         addp->set_req(AddPNode::Address, base);
3867       } else {
3868         // AddP case #4 (adr is array's element offset AddP node)
3869 #ifdef ASSERT
3870         const TypeOopPtr *atype = igvn->type(adr)->isa_oopptr();
3871         assert(adr->is_AddP() && atype != nullptr &&
3872                atype->instance_id() == inst_id, "array's element offset should be processed first");
3873 #endif
3874       }
3875       igvn->hash_insert(addp);
3876     }
3877   }
3878   // Put on IGVN worklist since at least addp's type was changed above.
3879   record_for_optimizer(addp);
3880   return true;
3881 }
3882 
3883 //
3884 // Create a new version of orig_phi if necessary. Returns either the newly
3885 // created phi or an existing phi.  Sets create_new to indicate whether a new
3886 // phi was created.  Cache the last newly created phi in the node map.
3887 //
3888 PhiNode *ConnectionGraph::create_split_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *>  &orig_phi_worklist, bool &new_created) {
3889   Compile *C = _compile;
3890   PhaseGVN* igvn = _igvn;
3891   new_created = false;
3892   int phi_alias_idx = C->get_alias_index(orig_phi->adr_type());
3893   // nothing to do if orig_phi is bottom memory or matches alias_idx
3894   if (phi_alias_idx == alias_idx) {
3895     return orig_phi;
3896   }
3897   // Have we recently created a Phi for this alias index?
3898   PhiNode *result = get_map_phi(orig_phi->_idx);
3899   if (result != nullptr && C->get_alias_index(result->adr_type()) == alias_idx) {
3900     return result;
3901   }
3902   // Previous check may fail when the same wide memory Phi was split into Phis
3903   // for different memory slices. Search all Phis for this region.
3904   if (result != nullptr) {
3905     Node* region = orig_phi->in(0);
3906     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
3907       Node* phi = region->fast_out(i);
3908       if (phi->is_Phi() &&
3909           C->get_alias_index(phi->as_Phi()->adr_type()) == alias_idx) {
3910         assert(phi->_idx >= nodes_size(), "only new Phi per instance memory slice");
3911         return phi->as_Phi();
3912       }
3913     }
3914   }
3915   if (C->live_nodes() + 2*NodeLimitFudgeFactor > C->max_node_limit()) {
3916     if (C->do_escape_analysis() == true && !C->failing()) {
3917       // Retry compilation without escape analysis.
3918       // If this is the first failure, the sentinel string will "stick"
3919       // to the Compile object, and the C2Compiler will see it and retry.
3920       C->record_failure(_invocation > 0 ? C2Compiler::retry_no_iterative_escape_analysis() : C2Compiler::retry_no_escape_analysis());
3921     }
3922     return nullptr;
3923   }
3924   orig_phi_worklist.append_if_missing(orig_phi);
3925   const TypePtr *atype = C->get_adr_type(alias_idx);
3926   result = PhiNode::make(orig_phi->in(0), nullptr, Type::MEMORY, atype);
3927   C->copy_node_notes_to(result, orig_phi);
3928   igvn->set_type(result, result->bottom_type());
3929   record_for_optimizer(result);
3930   set_map(orig_phi, result);
3931   new_created = true;
3932   return result;
3933 }
3934 
3935 //
3936 // Return a new version of Memory Phi "orig_phi" with the inputs having the
3937 // specified alias index.
3938 //
3939 PhiNode *ConnectionGraph::split_memory_phi(PhiNode *orig_phi, int alias_idx, GrowableArray<PhiNode *> &orig_phi_worklist, uint rec_depth) {
3940   assert(alias_idx != Compile::AliasIdxBot, "can't split out bottom memory");
3941   Compile *C = _compile;
3942   PhaseGVN* igvn = _igvn;
3943   bool new_phi_created;
3944   PhiNode *result = create_split_phi(orig_phi, alias_idx, orig_phi_worklist, new_phi_created);
3945   if (!new_phi_created) {
3946     return result;
3947   }
3948   GrowableArray<PhiNode *>  phi_list;
3949   GrowableArray<uint>  cur_input;
3950   PhiNode *phi = orig_phi;
3951   uint idx = 1;
3952   bool finished = false;
3953   while(!finished) {
3954     while (idx < phi->req()) {
3955       Node *mem = find_inst_mem(phi->in(idx), alias_idx, orig_phi_worklist, rec_depth + 1);
3956       if (mem != nullptr && mem->is_Phi()) {
3957         PhiNode *newphi = create_split_phi(mem->as_Phi(), alias_idx, orig_phi_worklist, new_phi_created);
3958         if (new_phi_created) {
3959           // found an phi for which we created a new split, push current one on worklist and begin
3960           // processing new one
3961           phi_list.push(phi);
3962           cur_input.push(idx);
3963           phi = mem->as_Phi();
3964           result = newphi;
3965           idx = 1;
3966           continue;
3967         } else {
3968           mem = newphi;
3969         }
3970       }
3971       if (C->failing()) {
3972         return nullptr;
3973       }
3974       result->set_req(idx++, mem);
3975     }
3976 #ifdef ASSERT
3977     // verify that the new Phi has an input for each input of the original
3978     assert( phi->req() == result->req(), "must have same number of inputs.");
3979     assert( result->in(0) != nullptr && result->in(0) == phi->in(0), "regions must match");
3980 #endif
3981     // Check if all new phi's inputs have specified alias index.
3982     // Otherwise use old phi.
3983     for (uint i = 1; i < phi->req(); i++) {
3984       Node* in = result->in(i);
3985       assert((phi->in(i) == nullptr) == (in == nullptr), "inputs must correspond.");
3986     }
3987     // we have finished processing a Phi, see if there are any more to do
3988     finished = (phi_list.length() == 0 );
3989     if (!finished) {
3990       phi = phi_list.pop();
3991       idx = cur_input.pop();
3992       PhiNode *prev_result = get_map_phi(phi->_idx);
3993       prev_result->set_req(idx++, result);
3994       result = prev_result;
3995     }
3996   }
3997   return result;
3998 }
3999 
4000 //
4001 // The next methods are derived from methods in MemNode.
4002 //
4003 Node* ConnectionGraph::step_through_mergemem(MergeMemNode *mmem, int alias_idx, const TypeOopPtr *toop) {
4004   Node *mem = mmem;
4005   // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
4006   // means an array I have not precisely typed yet.  Do not do any
4007   // alias stuff with it any time soon.
4008   if (toop->base() != Type::AnyPtr &&
4009       !(toop->isa_instptr() &&
4010         toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
4011         toop->offset() == Type::OffsetBot)) {
4012     mem = mmem->memory_at(alias_idx);
4013     // Update input if it is progress over what we have now
4014   }
4015   return mem;
4016 }
4017 
4018 //
4019 // Move memory users to their memory slices.
4020 //
4021 void ConnectionGraph::move_inst_mem(Node* n, GrowableArray<PhiNode *>  &orig_phis) {
4022   Compile* C = _compile;
4023   PhaseGVN* igvn = _igvn;
4024   const TypePtr* tp = igvn->type(n->in(MemNode::Address))->isa_ptr();
4025   assert(tp != nullptr, "ptr type");
4026   int alias_idx = C->get_alias_index(tp);
4027   int general_idx = C->get_general_index(alias_idx);
4028 
4029   // Move users first
4030   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
4031     Node* use = n->fast_out(i);
4032     if (use->is_MergeMem()) {
4033       MergeMemNode* mmem = use->as_MergeMem();
4034       assert(n == mmem->memory_at(alias_idx), "should be on instance memory slice");
4035       if (n != mmem->memory_at(general_idx) || alias_idx == general_idx) {
4036         continue; // Nothing to do
4037       }
4038       // Replace previous general reference to mem node.
4039       uint orig_uniq = C->unique();
4040       Node* m = find_inst_mem(n, general_idx, orig_phis);
4041       assert(orig_uniq == C->unique(), "no new nodes");
4042       mmem->set_memory_at(general_idx, m);
4043       --imax;
4044       --i;
4045     } else if (use->is_MemBar()) {
4046       assert(!use->is_Initialize(), "initializing stores should not be moved");
4047       if (use->req() > MemBarNode::Precedent &&
4048           use->in(MemBarNode::Precedent) == n) {
4049         // Don't move related membars.
4050         record_for_optimizer(use);
4051         continue;
4052       }
4053       tp = use->as_MemBar()->adr_type()->isa_ptr();
4054       if ((tp != nullptr && C->get_alias_index(tp) == alias_idx) ||
4055           alias_idx == general_idx) {
4056         continue; // Nothing to do
4057       }
4058       // Move to general memory slice.
4059       uint orig_uniq = C->unique();
4060       Node* m = find_inst_mem(n, general_idx, orig_phis);
4061       assert(orig_uniq == C->unique(), "no new nodes");
4062       igvn->hash_delete(use);
4063       imax -= use->replace_edge(n, m, igvn);
4064       igvn->hash_insert(use);
4065       record_for_optimizer(use);
4066       --i;
4067 #ifdef ASSERT
4068     } else if (use->is_Mem()) {
4069       // Memory nodes should have new memory input.
4070       tp = igvn->type(use->in(MemNode::Address))->isa_ptr();
4071       assert(tp != nullptr, "ptr type");
4072       int idx = C->get_alias_index(tp);
4073       assert(get_map(use->_idx) != nullptr || idx == alias_idx,
4074              "Following memory nodes should have new memory input or be on the same memory slice");
4075     } else if (use->is_Phi()) {
4076       // Phi nodes should be split and moved already.
4077       tp = use->as_Phi()->adr_type()->isa_ptr();
4078       assert(tp != nullptr, "ptr type");
4079       int idx = C->get_alias_index(tp);
4080       assert(idx == alias_idx, "Following Phi nodes should be on the same memory slice");
4081     } else {
4082       use->dump();
4083       assert(false, "should not be here");
4084 #endif
4085     }
4086   }
4087 }
4088 
4089 //
4090 // Search memory chain of "mem" to find a MemNode whose address
4091 // is the specified alias index.
4092 //
4093 #define FIND_INST_MEM_RECURSION_DEPTH_LIMIT 1000
4094 Node* ConnectionGraph::find_inst_mem(Node *orig_mem, int alias_idx, GrowableArray<PhiNode *>  &orig_phis, uint rec_depth) {
4095   if (rec_depth > FIND_INST_MEM_RECURSION_DEPTH_LIMIT) {
4096     _compile->record_failure(_invocation > 0 ? C2Compiler::retry_no_iterative_escape_analysis() : C2Compiler::retry_no_escape_analysis());
4097     return nullptr;
4098   }
4099   if (orig_mem == nullptr) {
4100     return orig_mem;
4101   }
4102   Compile* C = _compile;
4103   PhaseGVN* igvn = _igvn;
4104   const TypeOopPtr *toop = C->get_adr_type(alias_idx)->isa_oopptr();
4105   bool is_instance = (toop != nullptr) && toop->is_known_instance();
4106   Node *start_mem = C->start()->proj_out_or_null(TypeFunc::Memory);
4107   Node *prev = nullptr;
4108   Node *result = orig_mem;
4109   while (prev != result) {
4110     prev = result;
4111     if (result == start_mem) {
4112       break;  // hit one of our sentinels
4113     }
4114     if (result->is_Mem()) {
4115       const Type *at = igvn->type(result->in(MemNode::Address));
4116       if (at == Type::TOP) {
4117         break; // Dead
4118       }
4119       assert (at->isa_ptr() != nullptr, "pointer type required.");
4120       int idx = C->get_alias_index(at->is_ptr());
4121       if (idx == alias_idx) {
4122         break; // Found
4123       }
4124       if (!is_instance && (at->isa_oopptr() == nullptr ||
4125                            !at->is_oopptr()->is_known_instance())) {
4126         break; // Do not skip store to general memory slice.
4127       }
4128       result = result->in(MemNode::Memory);
4129     }
4130     if (!is_instance) {
4131       continue;  // don't search further for non-instance types
4132     }
4133     // skip over a call which does not affect this memory slice
4134     if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
4135       Node *proj_in = result->in(0);
4136       if (proj_in->is_Allocate() && proj_in->_idx == (uint)toop->instance_id()) {
4137         break;  // hit one of our sentinels
4138       } else if (proj_in->is_Call()) {
4139         // ArrayCopy node processed here as well
4140         CallNode *call = proj_in->as_Call();
4141         if (!call->may_modify(toop, igvn)) {
4142           result = call->in(TypeFunc::Memory);
4143         }
4144       } else if (proj_in->is_Initialize()) {
4145         AllocateNode* alloc = proj_in->as_Initialize()->allocation();
4146         // Stop if this is the initialization for the object instance which
4147         // which contains this memory slice, otherwise skip over it.
4148         if (alloc == nullptr || alloc->_idx != (uint)toop->instance_id()) {
4149           result = proj_in->in(TypeFunc::Memory);
4150         }
4151       } else if (proj_in->is_MemBar()) {
4152         // Check if there is an array copy for a clone
4153         // Step over GC barrier when ReduceInitialCardMarks is disabled
4154         BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4155         Node* control_proj_ac = bs->step_over_gc_barrier(proj_in->in(0));
4156 
4157         if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
4158           // Stop if it is a clone
4159           ArrayCopyNode* ac = control_proj_ac->in(0)->as_ArrayCopy();
4160           if (ac->may_modify(toop, igvn)) {
4161             break;
4162           }
4163         }
4164         result = proj_in->in(TypeFunc::Memory);
4165       }
4166     } else if (result->is_MergeMem()) {
4167       MergeMemNode *mmem = result->as_MergeMem();
4168       result = step_through_mergemem(mmem, alias_idx, toop);
4169       if (result == mmem->base_memory()) {
4170         // Didn't find instance memory, search through general slice recursively.
4171         result = mmem->memory_at(C->get_general_index(alias_idx));
4172         result = find_inst_mem(result, alias_idx, orig_phis, rec_depth + 1);
4173         if (C->failing()) {
4174           return nullptr;
4175         }
4176         mmem->set_memory_at(alias_idx, result);
4177       }
4178     } else if (result->is_Phi() &&
4179                C->get_alias_index(result->as_Phi()->adr_type()) != alias_idx) {
4180       Node *un = result->as_Phi()->unique_input(igvn);
4181       if (un != nullptr) {
4182         orig_phis.append_if_missing(result->as_Phi());
4183         result = un;
4184       } else {
4185         break;
4186       }
4187     } else if (result->is_ClearArray()) {
4188       if (!ClearArrayNode::step_through(&result, (uint)toop->instance_id(), igvn)) {
4189         // Can not bypass initialization of the instance
4190         // we are looking for.
4191         break;
4192       }
4193       // Otherwise skip it (the call updated 'result' value).
4194     } else if (result->Opcode() == Op_SCMemProj) {
4195       Node* mem = result->in(0);
4196       Node* adr = nullptr;
4197       if (mem->is_LoadStore()) {
4198         adr = mem->in(MemNode::Address);
4199       } else {
4200         assert(mem->Opcode() == Op_EncodeISOArray ||
4201                mem->Opcode() == Op_StrCompressedCopy, "sanity");
4202         adr = mem->in(3); // Memory edge corresponds to destination array
4203       }
4204       const Type *at = igvn->type(adr);
4205       if (at != Type::TOP) {
4206         assert(at->isa_ptr() != nullptr, "pointer type required.");
4207         int idx = C->get_alias_index(at->is_ptr());
4208         if (idx == alias_idx) {
4209           // Assert in debug mode
4210           assert(false, "Object is not scalar replaceable if a LoadStore node accesses its field");
4211           break; // In product mode return SCMemProj node
4212         }
4213       }
4214       result = mem->in(MemNode::Memory);
4215     } else if (result->Opcode() == Op_StrInflatedCopy) {
4216       Node* adr = result->in(3); // Memory edge corresponds to destination array
4217       const Type *at = igvn->type(adr);
4218       if (at != Type::TOP) {
4219         assert(at->isa_ptr() != nullptr, "pointer type required.");
4220         int idx = C->get_alias_index(at->is_ptr());
4221         if (idx == alias_idx) {
4222           // Assert in debug mode
4223           assert(false, "Object is not scalar replaceable if a StrInflatedCopy node accesses its field");
4224           break; // In product mode return SCMemProj node
4225         }
4226       }
4227       result = result->in(MemNode::Memory);
4228     }
4229   }
4230   if (result->is_Phi()) {
4231     PhiNode *mphi = result->as_Phi();
4232     assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
4233     const TypePtr *t = mphi->adr_type();
4234     if (!is_instance) {
4235       // Push all non-instance Phis on the orig_phis worklist to update inputs
4236       // during Phase 4 if needed.
4237       orig_phis.append_if_missing(mphi);
4238     } else if (C->get_alias_index(t) != alias_idx) {
4239       // Create a new Phi with the specified alias index type.
4240       result = split_memory_phi(mphi, alias_idx, orig_phis, rec_depth + 1);
4241     }
4242   }
4243   // the result is either MemNode, PhiNode, InitializeNode.
4244   return result;
4245 }
4246 
4247 //
4248 //  Convert the types of non-escaped object to instance types where possible,
4249 //  propagate the new type information through the graph, and update memory
4250 //  edges and MergeMem inputs to reflect the new type.
4251 //
4252 //  We start with allocations (and calls which may be allocations)  on alloc_worklist.
4253 //  The processing is done in 4 phases:
4254 //
4255 //  Phase 1:  Process possible allocations from alloc_worklist.  Create instance
4256 //            types for the CheckCastPP for allocations where possible.
4257 //            Propagate the new types through users as follows:
4258 //               casts and Phi:  push users on alloc_worklist
4259 //               AddP:  cast Base and Address inputs to the instance type
4260 //                      push any AddP users on alloc_worklist and push any memnode
4261 //                      users onto memnode_worklist.
4262 //  Phase 2:  Process MemNode's from memnode_worklist. compute new address type and
4263 //            search the Memory chain for a store with the appropriate type
4264 //            address type.  If a Phi is found, create a new version with
4265 //            the appropriate memory slices from each of the Phi inputs.
4266 //            For stores, process the users as follows:
4267 //               MemNode:  push on memnode_worklist
4268 //               MergeMem: push on mergemem_worklist
4269 //  Phase 3:  Process MergeMem nodes from mergemem_worklist.  Walk each memory slice
4270 //            moving the first node encountered of each  instance type to the
4271 //            the input corresponding to its alias index.
4272 //            appropriate memory slice.
4273 //  Phase 4:  Update the inputs of non-instance memory Phis and the Memory input of memnodes.
4274 //
4275 // In the following example, the CheckCastPP nodes are the cast of allocation
4276 // results and the allocation of node 29 is non-escaped and eligible to be an
4277 // instance type.
4278 //
4279 // We start with:
4280 //
4281 //     7 Parm #memory
4282 //    10  ConI  "12"
4283 //    19  CheckCastPP   "Foo"
4284 //    20  AddP  _ 19 19 10  Foo+12  alias_index=4
4285 //    29  CheckCastPP   "Foo"
4286 //    30  AddP  _ 29 29 10  Foo+12  alias_index=4
4287 //
4288 //    40  StoreP  25   7  20   ... alias_index=4
4289 //    50  StoreP  35  40  30   ... alias_index=4
4290 //    60  StoreP  45  50  20   ... alias_index=4
4291 //    70  LoadP    _  60  30   ... alias_index=4
4292 //    80  Phi     75  50  60   Memory alias_index=4
4293 //    90  LoadP    _  80  30   ... alias_index=4
4294 //   100  LoadP    _  80  20   ... alias_index=4
4295 //
4296 //
4297 // Phase 1 creates an instance type for node 29 assigning it an instance id of 24
4298 // and creating a new alias index for node 30.  This gives:
4299 //
4300 //     7 Parm #memory
4301 //    10  ConI  "12"
4302 //    19  CheckCastPP   "Foo"
4303 //    20  AddP  _ 19 19 10  Foo+12  alias_index=4
4304 //    29  CheckCastPP   "Foo"  iid=24
4305 //    30  AddP  _ 29 29 10  Foo+12  alias_index=6  iid=24
4306 //
4307 //    40  StoreP  25   7  20   ... alias_index=4
4308 //    50  StoreP  35  40  30   ... alias_index=6
4309 //    60  StoreP  45  50  20   ... alias_index=4
4310 //    70  LoadP    _  60  30   ... alias_index=6
4311 //    80  Phi     75  50  60   Memory alias_index=4
4312 //    90  LoadP    _  80  30   ... alias_index=6
4313 //   100  LoadP    _  80  20   ... alias_index=4
4314 //
4315 // In phase 2, new memory inputs are computed for the loads and stores,
4316 // And a new version of the phi is created.  In phase 4, the inputs to
4317 // node 80 are updated and then the memory nodes are updated with the
4318 // values computed in phase 2.  This results in:
4319 //
4320 //     7 Parm #memory
4321 //    10  ConI  "12"
4322 //    19  CheckCastPP   "Foo"
4323 //    20  AddP  _ 19 19 10  Foo+12  alias_index=4
4324 //    29  CheckCastPP   "Foo"  iid=24
4325 //    30  AddP  _ 29 29 10  Foo+12  alias_index=6  iid=24
4326 //
4327 //    40  StoreP  25  7   20   ... alias_index=4
4328 //    50  StoreP  35  7   30   ... alias_index=6
4329 //    60  StoreP  45  40  20   ... alias_index=4
4330 //    70  LoadP    _  50  30   ... alias_index=6
4331 //    80  Phi     75  40  60   Memory alias_index=4
4332 //   120  Phi     75  50  50   Memory alias_index=6
4333 //    90  LoadP    _ 120  30   ... alias_index=6
4334 //   100  LoadP    _  80  20   ... alias_index=4
4335 //
4336 void ConnectionGraph::split_unique_types(GrowableArray<Node *>  &alloc_worklist,
4337                                          GrowableArray<ArrayCopyNode*> &arraycopy_worklist,
4338                                          GrowableArray<MergeMemNode*> &mergemem_worklist,
4339                                          Unique_Node_List &reducible_merges) {
4340   DEBUG_ONLY(Unique_Node_List reduced_merges;)
4341   GrowableArray<Node *>  memnode_worklist;
4342   GrowableArray<PhiNode *>  orig_phis;
4343   PhaseIterGVN  *igvn = _igvn;
4344   uint new_index_start = (uint) _compile->num_alias_types();
4345   VectorSet visited;
4346   ideal_nodes.clear(); // Reset for use with set_map/get_map.
4347   uint unique_old = _compile->unique();
4348 
4349   //  Phase 1:  Process possible allocations from alloc_worklist.
4350   //  Create instance types for the CheckCastPP for allocations where possible.
4351   //
4352   // (Note: don't forget to change the order of the second AddP node on
4353   //  the alloc_worklist if the order of the worklist processing is changed,
4354   //  see the comment in find_second_addp().)
4355   //
4356   while (alloc_worklist.length() != 0) {
4357     Node *n = alloc_worklist.pop();
4358     uint ni = n->_idx;
4359     if (n->is_Call()) {
4360       CallNode *alloc = n->as_Call();
4361       // copy escape information to call node
4362       PointsToNode* ptn = ptnode_adr(alloc->_idx);
4363       PointsToNode::EscapeState es = ptn->escape_state();
4364       // We have an allocation or call which returns a Java object,
4365       // see if it is non-escaped.
4366       if (es != PointsToNode::NoEscape || !ptn->scalar_replaceable()) {
4367         continue;
4368       }
4369       // Find CheckCastPP for the allocate or for the return value of a call
4370       n = alloc->result_cast();
4371       if (n == nullptr) {            // No uses except Initialize node
4372         if (alloc->is_Allocate()) {
4373           // Set the scalar_replaceable flag for allocation
4374           // so it could be eliminated if it has no uses.
4375           alloc->as_Allocate()->_is_scalar_replaceable = true;
4376         }
4377         continue;
4378       }
4379       if (!n->is_CheckCastPP()) { // not unique CheckCastPP.
4380         // we could reach here for allocate case if one init is associated with many allocs.
4381         if (alloc->is_Allocate()) {
4382           alloc->as_Allocate()->_is_scalar_replaceable = false;
4383         }
4384         continue;
4385       }
4386 
4387       // The inline code for Object.clone() casts the allocation result to
4388       // java.lang.Object and then to the actual type of the allocated
4389       // object. Detect this case and use the second cast.
4390       // Also detect j.l.reflect.Array.newInstance(jobject, jint) case when
4391       // the allocation result is cast to java.lang.Object and then
4392       // to the actual Array type.
4393       if (alloc->is_Allocate() && n->as_Type()->type() == TypeInstPtr::NOTNULL
4394           && (alloc->is_AllocateArray() ||
4395               igvn->type(alloc->in(AllocateNode::KlassNode)) != TypeInstKlassPtr::OBJECT)) {
4396         Node *cast2 = nullptr;
4397         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
4398           Node *use = n->fast_out(i);
4399           if (use->is_CheckCastPP()) {
4400             cast2 = use;
4401             break;
4402           }
4403         }
4404         if (cast2 != nullptr) {
4405           n = cast2;
4406         } else {
4407           // Non-scalar replaceable if the allocation type is unknown statically
4408           // (reflection allocation), the object can't be restored during
4409           // deoptimization without precise type.
4410           continue;
4411         }
4412       }
4413 
4414       const TypeOopPtr *t = igvn->type(n)->isa_oopptr();
4415       if (t == nullptr) {
4416         continue;  // not a TypeOopPtr
4417       }
4418       if (!t->klass_is_exact()) {
4419         continue; // not an unique type
4420       }
4421       if (alloc->is_Allocate()) {
4422         // Set the scalar_replaceable flag for allocation
4423         // so it could be eliminated.
4424         alloc->as_Allocate()->_is_scalar_replaceable = true;
4425       }
4426       set_escape_state(ptnode_adr(n->_idx), es NOT_PRODUCT(COMMA trace_propagate_message(ptn))); // CheckCastPP escape state
4427       // in order for an object to be scalar-replaceable, it must be:
4428       //   - a direct allocation (not a call returning an object)
4429       //   - non-escaping
4430       //   - eligible to be a unique type
4431       //   - not determined to be ineligible by escape analysis
4432       set_map(alloc, n);
4433       set_map(n, alloc);
4434       const TypeOopPtr* tinst = t->cast_to_instance_id(ni);
4435       igvn->hash_delete(n);
4436       igvn->set_type(n,  tinst);
4437       n->raise_bottom_type(tinst);
4438       igvn->hash_insert(n);
4439       record_for_optimizer(n);
4440       // Allocate an alias index for the header fields. Accesses to
4441       // the header emitted during macro expansion wouldn't have
4442       // correct memory state otherwise.
4443       _compile->get_alias_index(tinst->add_offset(oopDesc::mark_offset_in_bytes()));
4444       _compile->get_alias_index(tinst->add_offset(Type::klass_offset()));
4445       if (alloc->is_Allocate() && (t->isa_instptr() || t->isa_aryptr())) {
4446 
4447         // First, put on the worklist all Field edges from Connection Graph
4448         // which is more accurate than putting immediate users from Ideal Graph.
4449         for (EdgeIterator e(ptn); e.has_next(); e.next()) {
4450           PointsToNode* tgt = e.get();
4451           if (tgt->is_Arraycopy()) {
4452             continue;
4453           }
4454           Node* use = tgt->ideal_node();
4455           assert(tgt->is_Field() && use->is_AddP(),
4456                  "only AddP nodes are Field edges in CG");
4457           if (use->outcnt() > 0) { // Don't process dead nodes
4458             Node* addp2 = find_second_addp(use, use->in(AddPNode::Base));
4459             if (addp2 != nullptr) {
4460               assert(alloc->is_AllocateArray(),"array allocation was expected");
4461               alloc_worklist.append_if_missing(addp2);
4462             }
4463             alloc_worklist.append_if_missing(use);
4464           }
4465         }
4466 
4467         // An allocation may have an Initialize which has raw stores. Scan
4468         // the users of the raw allocation result and push AddP users
4469         // on alloc_worklist.
4470         Node *raw_result = alloc->proj_out_or_null(TypeFunc::Parms);
4471         assert (raw_result != nullptr, "must have an allocation result");
4472         for (DUIterator_Fast imax, i = raw_result->fast_outs(imax); i < imax; i++) {
4473           Node *use = raw_result->fast_out(i);
4474           if (use->is_AddP() && use->outcnt() > 0) { // Don't process dead nodes
4475             Node* addp2 = find_second_addp(use, raw_result);
4476             if (addp2 != nullptr) {
4477               assert(alloc->is_AllocateArray(),"array allocation was expected");
4478               alloc_worklist.append_if_missing(addp2);
4479             }
4480             alloc_worklist.append_if_missing(use);
4481           } else if (use->is_MemBar()) {
4482             memnode_worklist.append_if_missing(use);
4483           }
4484         }
4485       }
4486     } else if (n->is_AddP()) {
4487       if (has_reducible_merge_base(n->as_AddP(), reducible_merges)) {
4488         // This AddP will go away when we reduce the Phi
4489         continue;
4490       }
4491       Node* addp_base = get_addp_base(n);
4492       JavaObjectNode* jobj = unique_java_object(addp_base);
4493       if (jobj == nullptr || jobj == phantom_obj) {
4494 #ifdef ASSERT
4495         ptnode_adr(get_addp_base(n)->_idx)->dump();
4496         ptnode_adr(n->_idx)->dump();
4497         assert(jobj != nullptr && jobj != phantom_obj, "escaped allocation");
4498 #endif
4499         _compile->record_failure(_invocation > 0 ? C2Compiler::retry_no_iterative_escape_analysis() : C2Compiler::retry_no_escape_analysis());
4500         return;
4501       }
4502       Node *base = get_map(jobj->idx());  // CheckCastPP node
4503       if (!split_AddP(n, base)) continue; // wrong type from dead path
4504     } else if (n->is_Phi() ||
4505                n->is_CheckCastPP() ||
4506                n->is_EncodeP() ||
4507                n->is_DecodeN() ||
4508                (n->is_ConstraintCast() && n->Opcode() == Op_CastPP)) {
4509       if (visited.test_set(n->_idx)) {
4510         assert(n->is_Phi(), "loops only through Phi's");
4511         continue;  // already processed
4512       }
4513       // Reducible Phi's will be removed from the graph after split_unique_types
4514       // finishes. For now we just try to split out the SR inputs of the merge.
4515       Node* parent = n->in(1);
4516       if (reducible_merges.member(n)) {
4517         reduce_phi(n->as_Phi(), alloc_worklist, memnode_worklist);
4518 #ifdef ASSERT
4519         if (VerifyReduceAllocationMerges) {
4520           reduced_merges.push(n);
4521         }
4522 #endif
4523         continue;
4524       } else if (reducible_merges.member(parent)) {
4525         // 'n' is an user of a reducible merge (a Phi). It will be simplified as
4526         // part of reduce_merge.
4527         continue;
4528       }
4529       JavaObjectNode* jobj = unique_java_object(n);
4530       if (jobj == nullptr || jobj == phantom_obj) {
4531 #ifdef ASSERT
4532         ptnode_adr(n->_idx)->dump();
4533         assert(jobj != nullptr && jobj != phantom_obj, "escaped allocation");
4534 #endif
4535         _compile->record_failure(_invocation > 0 ? C2Compiler::retry_no_iterative_escape_analysis() : C2Compiler::retry_no_escape_analysis());
4536         return;
4537       } else {
4538         Node *val = get_map(jobj->idx());   // CheckCastPP node
4539         TypeNode *tn = n->as_Type();
4540         const TypeOopPtr* tinst = igvn->type(val)->isa_oopptr();
4541         assert(tinst != nullptr && tinst->is_known_instance() &&
4542                tinst->instance_id() == jobj->idx() , "instance type expected.");
4543 
4544         const Type *tn_type = igvn->type(tn);
4545         const TypeOopPtr *tn_t;
4546         if (tn_type->isa_narrowoop()) {
4547           tn_t = tn_type->make_ptr()->isa_oopptr();
4548         } else {
4549           tn_t = tn_type->isa_oopptr();
4550         }
4551         if (tn_t != nullptr && tinst->maybe_java_subtype_of(tn_t)) {
4552           if (tn_type->isa_narrowoop()) {
4553             tn_type = tinst->make_narrowoop();
4554           } else {
4555             tn_type = tinst;
4556           }
4557           igvn->hash_delete(tn);
4558           igvn->set_type(tn, tn_type);
4559           tn->set_type(tn_type);
4560           igvn->hash_insert(tn);
4561           record_for_optimizer(n);
4562         } else {
4563           assert(tn_type == TypePtr::NULL_PTR ||
4564                  (tn_t != nullptr && !tinst->maybe_java_subtype_of(tn_t)),
4565                  "unexpected type");
4566           continue; // Skip dead path with different type
4567         }
4568       }
4569     } else {
4570       DEBUG_ONLY(n->dump();)
4571       assert(false, "EA: unexpected node");
4572       continue;
4573     }
4574     // push allocation's users on appropriate worklist
4575     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
4576       Node *use = n->fast_out(i);
4577       if(use->is_Mem() && use->in(MemNode::Address) == n) {
4578         // Load/store to instance's field
4579         memnode_worklist.append_if_missing(use);
4580       } else if (use->is_MemBar()) {
4581         if (use->in(TypeFunc::Memory) == n) { // Ignore precedent edge
4582           memnode_worklist.append_if_missing(use);
4583         }
4584       } else if (use->is_AddP() && use->outcnt() > 0) { // No dead nodes
4585         Node* addp2 = find_second_addp(use, n);
4586         if (addp2 != nullptr) {
4587           alloc_worklist.append_if_missing(addp2);
4588         }
4589         alloc_worklist.append_if_missing(use);
4590       } else if (use->is_Phi() ||
4591                  use->is_CheckCastPP() ||
4592                  use->is_EncodeNarrowPtr() ||
4593                  use->is_DecodeNarrowPtr() ||
4594                  (use->is_ConstraintCast() && use->Opcode() == Op_CastPP)) {
4595         alloc_worklist.append_if_missing(use);
4596 #ifdef ASSERT
4597       } else if (use->is_Mem()) {
4598         assert(use->in(MemNode::Address) != n, "EA: missing allocation reference path");
4599       } else if (use->is_MergeMem()) {
4600         assert(mergemem_worklist.contains(use->as_MergeMem()), "EA: missing MergeMem node in the worklist");
4601       } else if (use->is_SafePoint()) {
4602         // Look for MergeMem nodes for calls which reference unique allocation
4603         // (through CheckCastPP nodes) even for debug info.
4604         Node* m = use->in(TypeFunc::Memory);
4605         if (m->is_MergeMem()) {
4606           assert(mergemem_worklist.contains(m->as_MergeMem()), "EA: missing MergeMem node in the worklist");
4607         }
4608       } else if (use->Opcode() == Op_EncodeISOArray) {
4609         if (use->in(MemNode::Memory) == n || use->in(3) == n) {
4610           // EncodeISOArray overwrites destination array
4611           memnode_worklist.append_if_missing(use);
4612         }
4613       } else {
4614         uint op = use->Opcode();
4615         if ((op == Op_StrCompressedCopy || op == Op_StrInflatedCopy) &&
4616             (use->in(MemNode::Memory) == n)) {
4617           // They overwrite memory edge corresponding to destination array,
4618           memnode_worklist.append_if_missing(use);
4619         } else if (!(op == Op_CmpP || op == Op_Conv2B ||
4620               op == Op_CastP2X ||
4621               op == Op_FastLock || op == Op_AryEq ||
4622               op == Op_StrComp || op == Op_CountPositives ||
4623               op == Op_StrCompressedCopy || op == Op_StrInflatedCopy ||
4624               op == Op_StrEquals || op == Op_VectorizedHashCode ||
4625               op == Op_StrIndexOf || op == Op_StrIndexOfChar ||
4626               op == Op_SubTypeCheck ||
4627               op == Op_ReinterpretS2HF ||
4628               BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(use))) {
4629           n->dump();
4630           use->dump();
4631           assert(false, "EA: missing allocation reference path");
4632         }
4633 #endif
4634       }
4635     }
4636 
4637   }
4638 
4639 #ifdef ASSERT
4640   if (VerifyReduceAllocationMerges) {
4641     for (uint i = 0; i < reducible_merges.size(); i++) {
4642       Node* phi = reducible_merges.at(i);
4643 
4644       if (!reduced_merges.member(phi)) {
4645         phi->dump(2);
4646         phi->dump(-2);
4647         assert(false, "This reducible merge wasn't reduced.");
4648       }
4649 
4650       // At this point reducible Phis shouldn't have AddP users anymore; only SafePoints or Casts.
4651       for (DUIterator_Fast jmax, j = phi->fast_outs(jmax); j < jmax; j++) {
4652         Node* use = phi->fast_out(j);
4653         if (!use->is_SafePoint() && !use->is_CastPP()) {
4654           phi->dump(2);
4655           phi->dump(-2);
4656           assert(false, "Unexpected user of reducible Phi -> %d:%s:%d", use->_idx, use->Name(), use->outcnt());
4657         }
4658       }
4659     }
4660   }
4661 #endif
4662 
4663   // Go over all ArrayCopy nodes and if one of the inputs has a unique
4664   // type, record it in the ArrayCopy node so we know what memory this
4665   // node uses/modified.
4666   for (int next = 0; next < arraycopy_worklist.length(); next++) {
4667     ArrayCopyNode* ac = arraycopy_worklist.at(next);
4668     Node* dest = ac->in(ArrayCopyNode::Dest);
4669     if (dest->is_AddP()) {
4670       dest = get_addp_base(dest);
4671     }
4672     JavaObjectNode* jobj = unique_java_object(dest);
4673     if (jobj != nullptr) {
4674       Node *base = get_map(jobj->idx());
4675       if (base != nullptr) {
4676         const TypeOopPtr *base_t = _igvn->type(base)->isa_oopptr();
4677         ac->_dest_type = base_t;
4678       }
4679     }
4680     Node* src = ac->in(ArrayCopyNode::Src);
4681     if (src->is_AddP()) {
4682       src = get_addp_base(src);
4683     }
4684     jobj = unique_java_object(src);
4685     if (jobj != nullptr) {
4686       Node* base = get_map(jobj->idx());
4687       if (base != nullptr) {
4688         const TypeOopPtr *base_t = _igvn->type(base)->isa_oopptr();
4689         ac->_src_type = base_t;
4690       }
4691     }
4692   }
4693 
4694   // New alias types were created in split_AddP().
4695   uint new_index_end = (uint) _compile->num_alias_types();
4696 
4697   //  Phase 2:  Process MemNode's from memnode_worklist. compute new address type and
4698   //            compute new values for Memory inputs  (the Memory inputs are not
4699   //            actually updated until phase 4.)
4700   if (memnode_worklist.length() == 0)
4701     return;  // nothing to do
4702   while (memnode_worklist.length() != 0) {
4703     Node *n = memnode_worklist.pop();
4704     if (visited.test_set(n->_idx)) {
4705       continue;
4706     }
4707     if (n->is_Phi() || n->is_ClearArray()) {
4708       // we don't need to do anything, but the users must be pushed
4709     } else if (n->is_MemBar()) { // Initialize, MemBar nodes
4710       // we don't need to do anything, but the users must be pushed
4711       n = n->as_MemBar()->proj_out_or_null(TypeFunc::Memory);
4712       if (n == nullptr) {
4713         continue;
4714       }
4715     } else if (n->is_CallLeaf()) {
4716       // Runtime calls with narrow memory input (no MergeMem node)
4717       // get the memory projection
4718       n = n->as_Call()->proj_out_or_null(TypeFunc::Memory);
4719       if (n == nullptr) {
4720         continue;
4721       }
4722     } else if (n->Opcode() == Op_StrInflatedCopy) {
4723       // Check direct uses of StrInflatedCopy.
4724       // It is memory type Node - no special SCMemProj node.
4725     } else if (n->Opcode() == Op_StrCompressedCopy ||
4726                n->Opcode() == Op_EncodeISOArray) {
4727       // get the memory projection
4728       n = n->find_out_with(Op_SCMemProj);
4729       assert(n != nullptr && n->Opcode() == Op_SCMemProj, "memory projection required");
4730     } else {
4731 #ifdef ASSERT
4732       if (!n->is_Mem()) {
4733         n->dump();
4734       }
4735       assert(n->is_Mem(), "memory node required.");
4736 #endif
4737       Node *addr = n->in(MemNode::Address);
4738       const Type *addr_t = igvn->type(addr);
4739       if (addr_t == Type::TOP) {
4740         continue;
4741       }
4742       assert (addr_t->isa_ptr() != nullptr, "pointer type required.");
4743       int alias_idx = _compile->get_alias_index(addr_t->is_ptr());
4744       assert ((uint)alias_idx < new_index_end, "wrong alias index");
4745       Node *mem = find_inst_mem(n->in(MemNode::Memory), alias_idx, orig_phis);
4746       if (_compile->failing()) {
4747         return;
4748       }
4749       if (mem != n->in(MemNode::Memory)) {
4750         // We delay the memory edge update since we need old one in
4751         // MergeMem code below when instances memory slices are separated.
4752         set_map(n, mem);
4753       }
4754       if (n->is_Load()) {
4755         continue;  // don't push users
4756       } else if (n->is_LoadStore()) {
4757         // get the memory projection
4758         n = n->find_out_with(Op_SCMemProj);
4759         assert(n != nullptr && n->Opcode() == Op_SCMemProj, "memory projection required");
4760       }
4761     }
4762     // push user on appropriate worklist
4763     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
4764       Node *use = n->fast_out(i);
4765       if (use->is_Phi() || use->is_ClearArray()) {
4766         memnode_worklist.append_if_missing(use);
4767       } else if (use->is_Mem() && use->in(MemNode::Memory) == n) {
4768         memnode_worklist.append_if_missing(use);
4769       } else if (use->is_MemBar() || use->is_CallLeaf()) {
4770         if (use->in(TypeFunc::Memory) == n) { // Ignore precedent edge
4771           memnode_worklist.append_if_missing(use);
4772         }
4773 #ifdef ASSERT
4774       } else if(use->is_Mem()) {
4775         assert(use->in(MemNode::Memory) != n, "EA: missing memory path");
4776       } else if (use->is_MergeMem()) {
4777         assert(mergemem_worklist.contains(use->as_MergeMem()), "EA: missing MergeMem node in the worklist");
4778       } else if (use->Opcode() == Op_EncodeISOArray) {
4779         if (use->in(MemNode::Memory) == n || use->in(3) == n) {
4780           // EncodeISOArray overwrites destination array
4781           memnode_worklist.append_if_missing(use);
4782         }
4783       } else {
4784         uint op = use->Opcode();
4785         if ((use->in(MemNode::Memory) == n) &&
4786             (op == Op_StrCompressedCopy || op == Op_StrInflatedCopy)) {
4787           // They overwrite memory edge corresponding to destination array,
4788           memnode_worklist.append_if_missing(use);
4789         } else if (!(BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(use) ||
4790               op == Op_AryEq || op == Op_StrComp || op == Op_CountPositives ||
4791               op == Op_StrCompressedCopy || op == Op_StrInflatedCopy || op == Op_VectorizedHashCode ||
4792               op == Op_StrEquals || op == Op_StrIndexOf || op == Op_StrIndexOfChar)) {
4793           n->dump();
4794           use->dump();
4795           assert(false, "EA: missing memory path");
4796         }
4797 #endif
4798       }
4799     }
4800   }
4801 
4802   //  Phase 3:  Process MergeMem nodes from mergemem_worklist.
4803   //            Walk each memory slice moving the first node encountered of each
4804   //            instance type to the input corresponding to its alias index.
4805   uint length = mergemem_worklist.length();
4806   for( uint next = 0; next < length; ++next ) {
4807     MergeMemNode* nmm = mergemem_worklist.at(next);
4808     assert(!visited.test_set(nmm->_idx), "should not be visited before");
4809     // Note: we don't want to use MergeMemStream here because we only want to
4810     // scan inputs which exist at the start, not ones we add during processing.
4811     // Note 2: MergeMem may already contains instance memory slices added
4812     // during find_inst_mem() call when memory nodes were processed above.
4813     igvn->hash_delete(nmm);
4814     uint nslices = MIN2(nmm->req(), new_index_start);
4815     for (uint i = Compile::AliasIdxRaw+1; i < nslices; i++) {
4816       Node* mem = nmm->in(i);
4817       Node* cur = nullptr;
4818       if (mem == nullptr || mem->is_top()) {
4819         continue;
4820       }
4821       // First, update mergemem by moving memory nodes to corresponding slices
4822       // if their type became more precise since this mergemem was created.
4823       while (mem->is_Mem()) {
4824         const Type *at = igvn->type(mem->in(MemNode::Address));
4825         if (at != Type::TOP) {
4826           assert (at->isa_ptr() != nullptr, "pointer type required.");
4827           uint idx = (uint)_compile->get_alias_index(at->is_ptr());
4828           if (idx == i) {
4829             if (cur == nullptr) {
4830               cur = mem;
4831             }
4832           } else {
4833             if (idx >= nmm->req() || nmm->is_empty_memory(nmm->in(idx))) {
4834               nmm->set_memory_at(idx, mem);
4835             }
4836           }
4837         }
4838         mem = mem->in(MemNode::Memory);
4839       }
4840       nmm->set_memory_at(i, (cur != nullptr) ? cur : mem);
4841       // Find any instance of the current type if we haven't encountered
4842       // already a memory slice of the instance along the memory chain.
4843       for (uint ni = new_index_start; ni < new_index_end; ni++) {
4844         if((uint)_compile->get_general_index(ni) == i) {
4845           Node *m = (ni >= nmm->req()) ? nmm->empty_memory() : nmm->in(ni);
4846           if (nmm->is_empty_memory(m)) {
4847             Node* result = find_inst_mem(mem, ni, orig_phis);
4848             if (_compile->failing()) {
4849               return;
4850             }
4851             nmm->set_memory_at(ni, result);
4852           }
4853         }
4854       }
4855     }
4856     // Find the rest of instances values
4857     for (uint ni = new_index_start; ni < new_index_end; ni++) {
4858       const TypeOopPtr *tinst = _compile->get_adr_type(ni)->isa_oopptr();
4859       Node* result = step_through_mergemem(nmm, ni, tinst);
4860       if (result == nmm->base_memory()) {
4861         // Didn't find instance memory, search through general slice recursively.
4862         result = nmm->memory_at(_compile->get_general_index(ni));
4863         result = find_inst_mem(result, ni, orig_phis);
4864         if (_compile->failing()) {
4865           return;
4866         }
4867         nmm->set_memory_at(ni, result);
4868       }
4869     }
4870 
4871     // If we have crossed the 3/4 point of max node limit it's too risky
4872     // to continue with EA/SR because we might hit the max node limit.
4873     if (_compile->live_nodes() >= _compile->max_node_limit() * 0.75) {
4874       if (_compile->do_reduce_allocation_merges()) {
4875         _compile->record_failure(C2Compiler::retry_no_reduce_allocation_merges());
4876       } else if (_invocation > 0) {
4877         _compile->record_failure(C2Compiler::retry_no_iterative_escape_analysis());
4878       } else {
4879         _compile->record_failure(C2Compiler::retry_no_escape_analysis());
4880       }
4881       return;
4882     }
4883 
4884     igvn->hash_insert(nmm);
4885     record_for_optimizer(nmm);
4886   }
4887 
4888   //  Phase 4:  Update the inputs of non-instance memory Phis and
4889   //            the Memory input of memnodes
4890   // First update the inputs of any non-instance Phi's from
4891   // which we split out an instance Phi.  Note we don't have
4892   // to recursively process Phi's encountered on the input memory
4893   // chains as is done in split_memory_phi() since they  will
4894   // also be processed here.
4895   for (int j = 0; j < orig_phis.length(); j++) {
4896     PhiNode *phi = orig_phis.at(j);
4897     int alias_idx = _compile->get_alias_index(phi->adr_type());
4898     igvn->hash_delete(phi);
4899     for (uint i = 1; i < phi->req(); i++) {
4900       Node *mem = phi->in(i);
4901       Node *new_mem = find_inst_mem(mem, alias_idx, orig_phis);
4902       if (_compile->failing()) {
4903         return;
4904       }
4905       if (mem != new_mem) {
4906         phi->set_req(i, new_mem);
4907       }
4908     }
4909     igvn->hash_insert(phi);
4910     record_for_optimizer(phi);
4911   }
4912 
4913   // Update the memory inputs of MemNodes with the value we computed
4914   // in Phase 2 and move stores memory users to corresponding memory slices.
4915   // Disable memory split verification code until the fix for 6984348.
4916   // Currently it produces false negative results since it does not cover all cases.
4917 #if 0 // ifdef ASSERT
4918   visited.Reset();
4919   Node_Stack old_mems(arena, _compile->unique() >> 2);
4920 #endif
4921   for (uint i = 0; i < ideal_nodes.size(); i++) {
4922     Node*    n = ideal_nodes.at(i);
4923     Node* nmem = get_map(n->_idx);
4924     assert(nmem != nullptr, "sanity");
4925     if (n->is_Mem()) {
4926 #if 0 // ifdef ASSERT
4927       Node* old_mem = n->in(MemNode::Memory);
4928       if (!visited.test_set(old_mem->_idx)) {
4929         old_mems.push(old_mem, old_mem->outcnt());
4930       }
4931 #endif
4932       assert(n->in(MemNode::Memory) != nmem, "sanity");
4933       if (!n->is_Load()) {
4934         // Move memory users of a store first.
4935         move_inst_mem(n, orig_phis);
4936       }
4937       // Now update memory input
4938       igvn->hash_delete(n);
4939       n->set_req(MemNode::Memory, nmem);
4940       igvn->hash_insert(n);
4941       record_for_optimizer(n);
4942     } else {
4943       assert(n->is_Allocate() || n->is_CheckCastPP() ||
4944              n->is_AddP() || n->is_Phi(), "unknown node used for set_map()");
4945     }
4946   }
4947 #if 0 // ifdef ASSERT
4948   // Verify that memory was split correctly
4949   while (old_mems.is_nonempty()) {
4950     Node* old_mem = old_mems.node();
4951     uint  old_cnt = old_mems.index();
4952     old_mems.pop();
4953     assert(old_cnt == old_mem->outcnt(), "old mem could be lost");
4954   }
4955 #endif
4956 }
4957 
4958 #ifndef PRODUCT
4959 int ConnectionGraph::_no_escape_counter = 0;
4960 int ConnectionGraph::_arg_escape_counter = 0;
4961 int ConnectionGraph::_global_escape_counter = 0;
4962 
4963 static const char *node_type_names[] = {
4964   "UnknownType",
4965   "JavaObject",
4966   "LocalVar",
4967   "Field",
4968   "Arraycopy"
4969 };
4970 
4971 static const char *esc_names[] = {
4972   "UnknownEscape",
4973   "NoEscape",
4974   "ArgEscape",
4975   "GlobalEscape"
4976 };
4977 
4978 void PointsToNode::dump_header(bool print_state, outputStream* out) const {
4979   NodeType nt = node_type();
4980   out->print("%s(%d) ", node_type_names[(int) nt], _pidx);
4981   if (print_state) {
4982     EscapeState es = escape_state();
4983     EscapeState fields_es = fields_escape_state();
4984     out->print("%s(%s) ", esc_names[(int)es], esc_names[(int)fields_es]);
4985     if (nt == PointsToNode::JavaObject && !this->scalar_replaceable()) {
4986       out->print("NSR ");
4987     }
4988   }
4989 }
4990 
4991 void PointsToNode::dump(bool print_state, outputStream* out, bool newline) const {
4992   dump_header(print_state, out);
4993   if (is_Field()) {
4994     FieldNode* f = (FieldNode*)this;
4995     if (f->is_oop()) {
4996       out->print("oop ");
4997     }
4998     if (f->offset() > 0) {
4999       out->print("+%d ", f->offset());
5000     }
5001     out->print("(");
5002     for (BaseIterator i(f); i.has_next(); i.next()) {
5003       PointsToNode* b = i.get();
5004       out->print(" %d%s", b->idx(),(b->is_JavaObject() ? "P" : ""));
5005     }
5006     out->print(" )");
5007   }
5008   out->print("[");
5009   for (EdgeIterator i(this); i.has_next(); i.next()) {
5010     PointsToNode* e = i.get();
5011     out->print(" %d%s%s", e->idx(),(e->is_JavaObject() ? "P" : (e->is_Field() ? "F" : "")), e->is_Arraycopy() ? "cp" : "");
5012   }
5013   out->print(" [");
5014   for (UseIterator i(this); i.has_next(); i.next()) {
5015     PointsToNode* u = i.get();
5016     bool is_base = false;
5017     if (PointsToNode::is_base_use(u)) {
5018       is_base = true;
5019       u = PointsToNode::get_use_node(u)->as_Field();
5020     }
5021     out->print(" %d%s%s", u->idx(), is_base ? "b" : "", u->is_Arraycopy() ? "cp" : "");
5022   }
5023   out->print(" ]]  ");
5024   if (_node == nullptr) {
5025     out->print("<null>%s", newline ? "\n" : "");
5026   } else {
5027     _node->dump(newline ? "\n" : "", false, out);
5028   }
5029 }
5030 
5031 void ConnectionGraph::dump(GrowableArray<PointsToNode*>& ptnodes_worklist) {
5032   bool first = true;
5033   int ptnodes_length = ptnodes_worklist.length();
5034   for (int i = 0; i < ptnodes_length; i++) {
5035     PointsToNode *ptn = ptnodes_worklist.at(i);
5036     if (ptn == nullptr || !ptn->is_JavaObject()) {
5037       continue;
5038     }
5039     PointsToNode::EscapeState es = ptn->escape_state();
5040     if ((es != PointsToNode::NoEscape) && !Verbose) {
5041       continue;
5042     }
5043     Node* n = ptn->ideal_node();
5044     if (n->is_Allocate() || (n->is_CallStaticJava() &&
5045                              n->as_CallStaticJava()->is_boxing_method())) {
5046       if (first) {
5047         tty->cr();
5048         tty->print("======== Connection graph for ");
5049         _compile->method()->print_short_name();
5050         tty->cr();
5051         tty->print_cr("invocation #%d: %d iterations and %f sec to build connection graph with %d nodes and worklist size %d",
5052                       _invocation, _build_iterations, _build_time, nodes_size(), ptnodes_worklist.length());
5053         tty->cr();
5054         first = false;
5055       }
5056       ptn->dump();
5057       // Print all locals and fields which reference this allocation
5058       for (UseIterator j(ptn); j.has_next(); j.next()) {
5059         PointsToNode* use = j.get();
5060         if (use->is_LocalVar()) {
5061           use->dump(Verbose);
5062         } else if (Verbose) {
5063           use->dump();
5064         }
5065       }
5066       tty->cr();
5067     }
5068   }
5069 }
5070 
5071 void ConnectionGraph::print_statistics() {
5072   tty->print_cr("No escape = %d, Arg escape = %d, Global escape = %d", Atomic::load(&_no_escape_counter), Atomic::load(&_arg_escape_counter), Atomic::load(&_global_escape_counter));
5073 }
5074 
5075 void ConnectionGraph::escape_state_statistics(GrowableArray<JavaObjectNode*>& java_objects_worklist) {
5076   if (!PrintOptoStatistics || (_invocation > 0)) { // Collect data only for the first invocation
5077     return;
5078   }
5079   for (int next = 0; next < java_objects_worklist.length(); ++next) {
5080     JavaObjectNode* ptn = java_objects_worklist.at(next);
5081     if (ptn->ideal_node()->is_Allocate()) {
5082       if (ptn->escape_state() == PointsToNode::NoEscape) {
5083         Atomic::inc(&ConnectionGraph::_no_escape_counter);
5084       } else if (ptn->escape_state() == PointsToNode::ArgEscape) {
5085         Atomic::inc(&ConnectionGraph::_arg_escape_counter);
5086       } else if (ptn->escape_state() == PointsToNode::GlobalEscape) {
5087         Atomic::inc(&ConnectionGraph::_global_escape_counter);
5088       } else {
5089         assert(false, "Unexpected Escape State");
5090       }
5091     }
5092   }
5093 }
5094 
5095 void ConnectionGraph::trace_es_update_helper(PointsToNode* ptn, PointsToNode::EscapeState es, bool fields, const char* reason) const {
5096   if (_compile->directive()->TraceEscapeAnalysisOption) {
5097     assert(ptn != nullptr, "should not be null");
5098     assert(reason != nullptr, "should not be null");
5099     ptn->dump_header(true);
5100     PointsToNode::EscapeState new_es = fields ? ptn->escape_state() : es;
5101     PointsToNode::EscapeState new_fields_es = fields ? es : ptn->fields_escape_state();
5102     tty->print_cr("-> %s(%s) %s", esc_names[(int)new_es], esc_names[(int)new_fields_es], reason);
5103   }
5104 }
5105 
5106 const char* ConnectionGraph::trace_propagate_message(PointsToNode* from) const {
5107   if (_compile->directive()->TraceEscapeAnalysisOption) {
5108     stringStream ss;
5109     ss.print("propagated from: ");
5110     from->dump(true, &ss, false);
5111     return ss.as_string();
5112   } else {
5113     return nullptr;
5114   }
5115 }
5116 
5117 const char* ConnectionGraph::trace_arg_escape_message(CallNode* call) const {
5118   if (_compile->directive()->TraceEscapeAnalysisOption) {
5119     stringStream ss;
5120     ss.print("escapes as arg to:");
5121     call->dump("", false, &ss);
5122     return ss.as_string();
5123   } else {
5124     return nullptr;
5125   }
5126 }
5127 
5128 const char* ConnectionGraph::trace_merged_message(PointsToNode* other) const {
5129   if (_compile->directive()->TraceEscapeAnalysisOption) {
5130     stringStream ss;
5131     ss.print("is merged with other object: ");
5132     other->dump_header(true, &ss);
5133     return ss.as_string();
5134   } else {
5135     return nullptr;
5136   }
5137 }
5138 
5139 #endif
5140 
5141 void ConnectionGraph::record_for_optimizer(Node *n) {
5142   _igvn->_worklist.push(n);
5143   _igvn->add_users_to_worklist(n);
5144 }